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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kernel/lockdep.c
4 *
5 * Runtime locking correctness validator
6 *
7 * Started by Ingo Molnar:
8 *
9 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
10 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
11 *
12 * this code maps all the lock dependencies as they occur in a live kernel
13 * and will warn about the following classes of locking bugs:
14 *
15 * - lock inversion scenarios
16 * - circular lock dependencies
17 * - hardirq/softirq safe/unsafe locking bugs
18 *
19 * Bugs are reported even if the current locking scenario does not cause
20 * any deadlock at this point.
21 *
22 * I.e. if anytime in the past two locks were taken in a different order,
23 * even if it happened for another task, even if those were different
24 * locks (but of the same class as this lock), this code will detect it.
25 *
26 * Thanks to Arjan van de Ven for coming up with the initial idea of
27 * mapping lock dependencies runtime.
28 */
29#define DISABLE_BRANCH_PROFILING
30#include <linux/mutex.h>
31#include <linux/sched.h>
32#include <linux/sched/clock.h>
33#include <linux/sched/task.h>
34#include <linux/sched/mm.h>
35#include <linux/delay.h>
36#include <linux/module.h>
37#include <linux/proc_fs.h>
38#include <linux/seq_file.h>
39#include <linux/spinlock.h>
40#include <linux/kallsyms.h>
41#include <linux/interrupt.h>
42#include <linux/stacktrace.h>
43#include <linux/debug_locks.h>
44#include <linux/irqflags.h>
45#include <linux/utsname.h>
46#include <linux/hash.h>
47#include <linux/ftrace.h>
48#include <linux/stringify.h>
49#include <linux/bitmap.h>
50#include <linux/bitops.h>
51#include <linux/gfp.h>
52#include <linux/random.h>
53#include <linux/jhash.h>
54#include <linux/nmi.h>
55#include <linux/rcupdate.h>
56#include <linux/kprobes.h>
57
58#include <asm/sections.h>
59
60#include "lockdep_internals.h"
61
62#define CREATE_TRACE_POINTS
63#include <trace/events/lock.h>
64
65#ifdef CONFIG_PROVE_LOCKING
66int prove_locking = 1;
67module_param(prove_locking, int, 0644);
68#else
69#define prove_locking 0
70#endif
71
72#ifdef CONFIG_LOCK_STAT
73int lock_stat = 1;
74module_param(lock_stat, int, 0644);
75#else
76#define lock_stat 0
77#endif
78
79/*
80 * lockdep_lock: protects the lockdep graph, the hashes and the
81 * class/list/hash allocators.
82 *
83 * This is one of the rare exceptions where it's justified
84 * to use a raw spinlock - we really dont want the spinlock
85 * code to recurse back into the lockdep code...
86 */
87static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
88static struct task_struct *lockdep_selftest_task_struct;
89
90static int graph_lock(void)
91{
92 arch_spin_lock(&lockdep_lock);
93 /*
94 * Make sure that if another CPU detected a bug while
95 * walking the graph we dont change it (while the other
96 * CPU is busy printing out stuff with the graph lock
97 * dropped already)
98 */
99 if (!debug_locks) {
100 arch_spin_unlock(&lockdep_lock);
101 return 0;
102 }
103 /* prevent any recursions within lockdep from causing deadlocks */
104 current->lockdep_recursion++;
105 return 1;
106}
107
108static inline int graph_unlock(void)
109{
110 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
111 /*
112 * The lockdep graph lock isn't locked while we expect it to
113 * be, we're confused now, bye!
114 */
115 return DEBUG_LOCKS_WARN_ON(1);
116 }
117
118 current->lockdep_recursion--;
119 arch_spin_unlock(&lockdep_lock);
120 return 0;
121}
122
123/*
124 * Turn lock debugging off and return with 0 if it was off already,
125 * and also release the graph lock:
126 */
127static inline int debug_locks_off_graph_unlock(void)
128{
129 int ret = debug_locks_off();
130
131 arch_spin_unlock(&lockdep_lock);
132
133 return ret;
134}
135
136unsigned long nr_list_entries;
137static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
138static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES);
139
140/*
141 * All data structures here are protected by the global debug_lock.
142 *
143 * nr_lock_classes is the number of elements of lock_classes[] that is
144 * in use.
145 */
146#define KEYHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
147#define KEYHASH_SIZE (1UL << KEYHASH_BITS)
148static struct hlist_head lock_keys_hash[KEYHASH_SIZE];
149unsigned long nr_lock_classes;
150#ifndef CONFIG_DEBUG_LOCKDEP
151static
152#endif
153struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
154static DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS);
155
156static inline struct lock_class *hlock_class(struct held_lock *hlock)
157{
158 unsigned int class_idx = hlock->class_idx;
159
160 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfield */
161 barrier();
162
163 if (!test_bit(class_idx, lock_classes_in_use)) {
164 /*
165 * Someone passed in garbage, we give up.
166 */
167 DEBUG_LOCKS_WARN_ON(1);
168 return NULL;
169 }
170
171 /*
172 * At this point, if the passed hlock->class_idx is still garbage,
173 * we just have to live with it
174 */
175 return lock_classes + class_idx;
176}
177
178#ifdef CONFIG_LOCK_STAT
179static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
180
181static inline u64 lockstat_clock(void)
182{
183 return local_clock();
184}
185
186static int lock_point(unsigned long points[], unsigned long ip)
187{
188 int i;
189
190 for (i = 0; i < LOCKSTAT_POINTS; i++) {
191 if (points[i] == 0) {
192 points[i] = ip;
193 break;
194 }
195 if (points[i] == ip)
196 break;
197 }
198
199 return i;
200}
201
202static void lock_time_inc(struct lock_time *lt, u64 time)
203{
204 if (time > lt->max)
205 lt->max = time;
206
207 if (time < lt->min || !lt->nr)
208 lt->min = time;
209
210 lt->total += time;
211 lt->nr++;
212}
213
214static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
215{
216 if (!src->nr)
217 return;
218
219 if (src->max > dst->max)
220 dst->max = src->max;
221
222 if (src->min < dst->min || !dst->nr)
223 dst->min = src->min;
224
225 dst->total += src->total;
226 dst->nr += src->nr;
227}
228
229struct lock_class_stats lock_stats(struct lock_class *class)
230{
231 struct lock_class_stats stats;
232 int cpu, i;
233
234 memset(&stats, 0, sizeof(struct lock_class_stats));
235 for_each_possible_cpu(cpu) {
236 struct lock_class_stats *pcs =
237 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
238
239 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
240 stats.contention_point[i] += pcs->contention_point[i];
241
242 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
243 stats.contending_point[i] += pcs->contending_point[i];
244
245 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
246 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
247
248 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
249 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
250
251 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
252 stats.bounces[i] += pcs->bounces[i];
253 }
254
255 return stats;
256}
257
258void clear_lock_stats(struct lock_class *class)
259{
260 int cpu;
261
262 for_each_possible_cpu(cpu) {
263 struct lock_class_stats *cpu_stats =
264 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
265
266 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
267 }
268 memset(class->contention_point, 0, sizeof(class->contention_point));
269 memset(class->contending_point, 0, sizeof(class->contending_point));
270}
271
272static struct lock_class_stats *get_lock_stats(struct lock_class *class)
273{
274 return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes];
275}
276
277static void lock_release_holdtime(struct held_lock *hlock)
278{
279 struct lock_class_stats *stats;
280 u64 holdtime;
281
282 if (!lock_stat)
283 return;
284
285 holdtime = lockstat_clock() - hlock->holdtime_stamp;
286
287 stats = get_lock_stats(hlock_class(hlock));
288 if (hlock->read)
289 lock_time_inc(&stats->read_holdtime, holdtime);
290 else
291 lock_time_inc(&stats->write_holdtime, holdtime);
292}
293#else
294static inline void lock_release_holdtime(struct held_lock *hlock)
295{
296}
297#endif
298
299/*
300 * We keep a global list of all lock classes. The list is only accessed with
301 * the lockdep spinlock lock held. free_lock_classes is a list with free
302 * elements. These elements are linked together by the lock_entry member in
303 * struct lock_class.
304 */
305LIST_HEAD(all_lock_classes);
306static LIST_HEAD(free_lock_classes);
307
308/**
309 * struct pending_free - information about data structures about to be freed
310 * @zapped: Head of a list with struct lock_class elements.
311 * @lock_chains_being_freed: Bitmap that indicates which lock_chains[] elements
312 * are about to be freed.
313 */
314struct pending_free {
315 struct list_head zapped;
316 DECLARE_BITMAP(lock_chains_being_freed, MAX_LOCKDEP_CHAINS);
317};
318
319/**
320 * struct delayed_free - data structures used for delayed freeing
321 *
322 * A data structure for delayed freeing of data structures that may be
323 * accessed by RCU readers at the time these were freed.
324 *
325 * @rcu_head: Used to schedule an RCU callback for freeing data structures.
326 * @index: Index of @pf to which freed data structures are added.
327 * @scheduled: Whether or not an RCU callback has been scheduled.
328 * @pf: Array with information about data structures about to be freed.
329 */
330static struct delayed_free {
331 struct rcu_head rcu_head;
332 int index;
333 int scheduled;
334 struct pending_free pf[2];
335} delayed_free;
336
337/*
338 * The lockdep classes are in a hash-table as well, for fast lookup:
339 */
340#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
341#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
342#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
343#define classhashentry(key) (classhash_table + __classhashfn((key)))
344
345static struct hlist_head classhash_table[CLASSHASH_SIZE];
346
347/*
348 * We put the lock dependency chains into a hash-table as well, to cache
349 * their existence:
350 */
351#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
352#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
353#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
354#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
355
356static struct hlist_head chainhash_table[CHAINHASH_SIZE];
357
358/*
359 * The hash key of the lock dependency chains is a hash itself too:
360 * it's a hash of all locks taken up to that lock, including that lock.
361 * It's a 64-bit hash, because it's important for the keys to be
362 * unique.
363 */
364static inline u64 iterate_chain_key(u64 key, u32 idx)
365{
366 u32 k0 = key, k1 = key >> 32;
367
368 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
369
370 return k0 | (u64)k1 << 32;
371}
372
373void lockdep_init_task(struct task_struct *task)
374{
375 task->lockdep_depth = 0; /* no locks held yet */
376 task->curr_chain_key = INITIAL_CHAIN_KEY;
377 task->lockdep_recursion = 0;
378}
379
380void lockdep_off(void)
381{
382 current->lockdep_recursion++;
383}
384EXPORT_SYMBOL(lockdep_off);
385
386void lockdep_on(void)
387{
388 current->lockdep_recursion--;
389}
390EXPORT_SYMBOL(lockdep_on);
391
392void lockdep_set_selftest_task(struct task_struct *task)
393{
394 lockdep_selftest_task_struct = task;
395}
396
397/*
398 * Debugging switches:
399 */
400
401#define VERBOSE 0
402#define VERY_VERBOSE 0
403
404#if VERBOSE
405# define HARDIRQ_VERBOSE 1
406# define SOFTIRQ_VERBOSE 1
407#else
408# define HARDIRQ_VERBOSE 0
409# define SOFTIRQ_VERBOSE 0
410#endif
411
412#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
413/*
414 * Quick filtering for interesting events:
415 */
416static int class_filter(struct lock_class *class)
417{
418#if 0
419 /* Example */
420 if (class->name_version == 1 &&
421 !strcmp(class->name, "lockname"))
422 return 1;
423 if (class->name_version == 1 &&
424 !strcmp(class->name, "&struct->lockfield"))
425 return 1;
426#endif
427 /* Filter everything else. 1 would be to allow everything else */
428 return 0;
429}
430#endif
431
432static int verbose(struct lock_class *class)
433{
434#if VERBOSE
435 return class_filter(class);
436#endif
437 return 0;
438}
439
440static void print_lockdep_off(const char *bug_msg)
441{
442 printk(KERN_DEBUG "%s\n", bug_msg);
443 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
444#ifdef CONFIG_LOCK_STAT
445 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
446#endif
447}
448
449unsigned long nr_stack_trace_entries;
450
451#ifdef CONFIG_PROVE_LOCKING
452/**
453 * struct lock_trace - single stack backtrace
454 * @hash_entry: Entry in a stack_trace_hash[] list.
455 * @hash: jhash() of @entries.
456 * @nr_entries: Number of entries in @entries.
457 * @entries: Actual stack backtrace.
458 */
459struct lock_trace {
460 struct hlist_node hash_entry;
461 u32 hash;
462 u32 nr_entries;
463 unsigned long entries[0] __aligned(sizeof(unsigned long));
464};
465#define LOCK_TRACE_SIZE_IN_LONGS \
466 (sizeof(struct lock_trace) / sizeof(unsigned long))
467/*
468 * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock.
469 */
470static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
471static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE];
472
473static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2)
474{
475 return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries &&
476 memcmp(t1->entries, t2->entries,
477 t1->nr_entries * sizeof(t1->entries[0])) == 0;
478}
479
480static struct lock_trace *save_trace(void)
481{
482 struct lock_trace *trace, *t2;
483 struct hlist_head *hash_head;
484 u32 hash;
485 unsigned int max_entries;
486
487 BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE);
488 BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES);
489
490 trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries);
491 max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries -
492 LOCK_TRACE_SIZE_IN_LONGS;
493 trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
494
495 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES -
496 LOCK_TRACE_SIZE_IN_LONGS - 1) {
497 if (!debug_locks_off_graph_unlock())
498 return NULL;
499
500 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
501 dump_stack();
502
503 return NULL;
504 }
505
506 hash = jhash(trace->entries, trace->nr_entries *
507 sizeof(trace->entries[0]), 0);
508 trace->hash = hash;
509 hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1));
510 hlist_for_each_entry(t2, hash_head, hash_entry) {
511 if (traces_identical(trace, t2))
512 return t2;
513 }
514 nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries;
515 hlist_add_head(&trace->hash_entry, hash_head);
516
517 return trace;
518}
519
520/* Return the number of stack traces in the stack_trace[] array. */
521u64 lockdep_stack_trace_count(void)
522{
523 struct lock_trace *trace;
524 u64 c = 0;
525 int i;
526
527 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) {
528 hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) {
529 c++;
530 }
531 }
532
533 return c;
534}
535
536/* Return the number of stack hash chains that have at least one stack trace. */
537u64 lockdep_stack_hash_count(void)
538{
539 u64 c = 0;
540 int i;
541
542 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++)
543 if (!hlist_empty(&stack_trace_hash[i]))
544 c++;
545
546 return c;
547}
548#endif
549
550unsigned int nr_hardirq_chains;
551unsigned int nr_softirq_chains;
552unsigned int nr_process_chains;
553unsigned int max_lockdep_depth;
554
555#ifdef CONFIG_DEBUG_LOCKDEP
556/*
557 * Various lockdep statistics:
558 */
559DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
560#endif
561
562#ifdef CONFIG_PROVE_LOCKING
563/*
564 * Locking printouts:
565 */
566
567#define __USAGE(__STATE) \
568 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
569 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
570 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
571 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
572
573static const char *usage_str[] =
574{
575#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
576#include "lockdep_states.h"
577#undef LOCKDEP_STATE
578 [LOCK_USED] = "INITIAL USE",
579};
580#endif
581
582const char *__get_key_name(const struct lockdep_subclass_key *key, char *str)
583{
584 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
585}
586
587static inline unsigned long lock_flag(enum lock_usage_bit bit)
588{
589 return 1UL << bit;
590}
591
592static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
593{
594 /*
595 * The usage character defaults to '.' (i.e., irqs disabled and not in
596 * irq context), which is the safest usage category.
597 */
598 char c = '.';
599
600 /*
601 * The order of the following usage checks matters, which will
602 * result in the outcome character as follows:
603 *
604 * - '+': irq is enabled and not in irq context
605 * - '-': in irq context and irq is disabled
606 * - '?': in irq context and irq is enabled
607 */
608 if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) {
609 c = '+';
610 if (class->usage_mask & lock_flag(bit))
611 c = '?';
612 } else if (class->usage_mask & lock_flag(bit))
613 c = '-';
614
615 return c;
616}
617
618void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
619{
620 int i = 0;
621
622#define LOCKDEP_STATE(__STATE) \
623 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
624 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
625#include "lockdep_states.h"
626#undef LOCKDEP_STATE
627
628 usage[i] = '\0';
629}
630
631static void __print_lock_name(struct lock_class *class)
632{
633 char str[KSYM_NAME_LEN];
634 const char *name;
635
636 name = class->name;
637 if (!name) {
638 name = __get_key_name(class->key, str);
639 printk(KERN_CONT "%s", name);
640 } else {
641 printk(KERN_CONT "%s", name);
642 if (class->name_version > 1)
643 printk(KERN_CONT "#%d", class->name_version);
644 if (class->subclass)
645 printk(KERN_CONT "/%d", class->subclass);
646 }
647}
648
649static void print_lock_name(struct lock_class *class)
650{
651 char usage[LOCK_USAGE_CHARS];
652
653 get_usage_chars(class, usage);
654
655 printk(KERN_CONT " (");
656 __print_lock_name(class);
657 printk(KERN_CONT "){%s}", usage);
658}
659
660static void print_lockdep_cache(struct lockdep_map *lock)
661{
662 const char *name;
663 char str[KSYM_NAME_LEN];
664
665 name = lock->name;
666 if (!name)
667 name = __get_key_name(lock->key->subkeys, str);
668
669 printk(KERN_CONT "%s", name);
670}
671
672static void print_lock(struct held_lock *hlock)
673{
674 /*
675 * We can be called locklessly through debug_show_all_locks() so be
676 * extra careful, the hlock might have been released and cleared.
677 *
678 * If this indeed happens, lets pretend it does not hurt to continue
679 * to print the lock unless the hlock class_idx does not point to a
680 * registered class. The rationale here is: since we don't attempt
681 * to distinguish whether we are in this situation, if it just
682 * happened we can't count on class_idx to tell either.
683 */
684 struct lock_class *lock = hlock_class(hlock);
685
686 if (!lock) {
687 printk(KERN_CONT "<RELEASED>\n");
688 return;
689 }
690
691 printk(KERN_CONT "%px", hlock->instance);
692 print_lock_name(lock);
693 printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
694}
695
696static void lockdep_print_held_locks(struct task_struct *p)
697{
698 int i, depth = READ_ONCE(p->lockdep_depth);
699
700 if (!depth)
701 printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p));
702 else
703 printk("%d lock%s held by %s/%d:\n", depth,
704 depth > 1 ? "s" : "", p->comm, task_pid_nr(p));
705 /*
706 * It's not reliable to print a task's held locks if it's not sleeping
707 * and it's not the current task.
708 */
709 if (p->state == TASK_RUNNING && p != current)
710 return;
711 for (i = 0; i < depth; i++) {
712 printk(" #%d: ", i);
713 print_lock(p->held_locks + i);
714 }
715}
716
717static void print_kernel_ident(void)
718{
719 printk("%s %.*s %s\n", init_utsname()->release,
720 (int)strcspn(init_utsname()->version, " "),
721 init_utsname()->version,
722 print_tainted());
723}
724
725static int very_verbose(struct lock_class *class)
726{
727#if VERY_VERBOSE
728 return class_filter(class);
729#endif
730 return 0;
731}
732
733/*
734 * Is this the address of a static object:
735 */
736#ifdef __KERNEL__
737static int static_obj(const void *obj)
738{
739 unsigned long start = (unsigned long) &_stext,
740 end = (unsigned long) &_end,
741 addr = (unsigned long) obj;
742
743 if (arch_is_kernel_initmem_freed(addr))
744 return 0;
745
746 /*
747 * static variable?
748 */
749 if ((addr >= start) && (addr < end))
750 return 1;
751
752 if (arch_is_kernel_data(addr))
753 return 1;
754
755 /*
756 * in-kernel percpu var?
757 */
758 if (is_kernel_percpu_address(addr))
759 return 1;
760
761 /*
762 * module static or percpu var?
763 */
764 return is_module_address(addr) || is_module_percpu_address(addr);
765}
766#endif
767
768/*
769 * To make lock name printouts unique, we calculate a unique
770 * class->name_version generation counter. The caller must hold the graph
771 * lock.
772 */
773static int count_matching_names(struct lock_class *new_class)
774{
775 struct lock_class *class;
776 int count = 0;
777
778 if (!new_class->name)
779 return 0;
780
781 list_for_each_entry(class, &all_lock_classes, lock_entry) {
782 if (new_class->key - new_class->subclass == class->key)
783 return class->name_version;
784 if (class->name && !strcmp(class->name, new_class->name))
785 count = max(count, class->name_version);
786 }
787
788 return count + 1;
789}
790
791static inline struct lock_class *
792look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
793{
794 struct lockdep_subclass_key *key;
795 struct hlist_head *hash_head;
796 struct lock_class *class;
797
798 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
799 debug_locks_off();
800 printk(KERN_ERR
801 "BUG: looking up invalid subclass: %u\n", subclass);
802 printk(KERN_ERR
803 "turning off the locking correctness validator.\n");
804 dump_stack();
805 return NULL;
806 }
807
808 /*
809 * If it is not initialised then it has never been locked,
810 * so it won't be present in the hash table.
811 */
812 if (unlikely(!lock->key))
813 return NULL;
814
815 /*
816 * NOTE: the class-key must be unique. For dynamic locks, a static
817 * lock_class_key variable is passed in through the mutex_init()
818 * (or spin_lock_init()) call - which acts as the key. For static
819 * locks we use the lock object itself as the key.
820 */
821 BUILD_BUG_ON(sizeof(struct lock_class_key) >
822 sizeof(struct lockdep_map));
823
824 key = lock->key->subkeys + subclass;
825
826 hash_head = classhashentry(key);
827
828 /*
829 * We do an RCU walk of the hash, see lockdep_free_key_range().
830 */
831 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
832 return NULL;
833
834 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
835 if (class->key == key) {
836 /*
837 * Huh! same key, different name? Did someone trample
838 * on some memory? We're most confused.
839 */
840 WARN_ON_ONCE(class->name != lock->name &&
841 lock->key != &__lockdep_no_validate__);
842 return class;
843 }
844 }
845
846 return NULL;
847}
848
849/*
850 * Static locks do not have their class-keys yet - for them the key is
851 * the lock object itself. If the lock is in the per cpu area, the
852 * canonical address of the lock (per cpu offset removed) is used.
853 */
854static bool assign_lock_key(struct lockdep_map *lock)
855{
856 unsigned long can_addr, addr = (unsigned long)lock;
857
858#ifdef __KERNEL__
859 /*
860 * lockdep_free_key_range() assumes that struct lock_class_key
861 * objects do not overlap. Since we use the address of lock
862 * objects as class key for static objects, check whether the
863 * size of lock_class_key objects does not exceed the size of
864 * the smallest lock object.
865 */
866 BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
867#endif
868
869 if (__is_kernel_percpu_address(addr, &can_addr))
870 lock->key = (void *)can_addr;
871 else if (__is_module_percpu_address(addr, &can_addr))
872 lock->key = (void *)can_addr;
873 else if (static_obj(lock))
874 lock->key = (void *)lock;
875 else {
876 /* Debug-check: all keys must be persistent! */
877 debug_locks_off();
878 pr_err("INFO: trying to register non-static key.\n");
879 pr_err("the code is fine but needs lockdep annotation.\n");
880 pr_err("turning off the locking correctness validator.\n");
881 dump_stack();
882 return false;
883 }
884
885 return true;
886}
887
888#ifdef CONFIG_DEBUG_LOCKDEP
889
890/* Check whether element @e occurs in list @h */
891static bool in_list(struct list_head *e, struct list_head *h)
892{
893 struct list_head *f;
894
895 list_for_each(f, h) {
896 if (e == f)
897 return true;
898 }
899
900 return false;
901}
902
903/*
904 * Check whether entry @e occurs in any of the locks_after or locks_before
905 * lists.
906 */
907static bool in_any_class_list(struct list_head *e)
908{
909 struct lock_class *class;
910 int i;
911
912 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
913 class = &lock_classes[i];
914 if (in_list(e, &class->locks_after) ||
915 in_list(e, &class->locks_before))
916 return true;
917 }
918 return false;
919}
920
921static bool class_lock_list_valid(struct lock_class *c, struct list_head *h)
922{
923 struct lock_list *e;
924
925 list_for_each_entry(e, h, entry) {
926 if (e->links_to != c) {
927 printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s",
928 c->name ? : "(?)",
929 (unsigned long)(e - list_entries),
930 e->links_to && e->links_to->name ?
931 e->links_to->name : "(?)",
932 e->class && e->class->name ? e->class->name :
933 "(?)");
934 return false;
935 }
936 }
937 return true;
938}
939
940#ifdef CONFIG_PROVE_LOCKING
941static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
942#endif
943
944static bool check_lock_chain_key(struct lock_chain *chain)
945{
946#ifdef CONFIG_PROVE_LOCKING
947 u64 chain_key = INITIAL_CHAIN_KEY;
948 int i;
949
950 for (i = chain->base; i < chain->base + chain->depth; i++)
951 chain_key = iterate_chain_key(chain_key, chain_hlocks[i]);
952 /*
953 * The 'unsigned long long' casts avoid that a compiler warning
954 * is reported when building tools/lib/lockdep.
955 */
956 if (chain->chain_key != chain_key) {
957 printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n",
958 (unsigned long long)(chain - lock_chains),
959 (unsigned long long)chain->chain_key,
960 (unsigned long long)chain_key);
961 return false;
962 }
963#endif
964 return true;
965}
966
967static bool in_any_zapped_class_list(struct lock_class *class)
968{
969 struct pending_free *pf;
970 int i;
971
972 for (i = 0, pf = delayed_free.pf; i < ARRAY_SIZE(delayed_free.pf); i++, pf++) {
973 if (in_list(&class->lock_entry, &pf->zapped))
974 return true;
975 }
976
977 return false;
978}
979
980static bool __check_data_structures(void)
981{
982 struct lock_class *class;
983 struct lock_chain *chain;
984 struct hlist_head *head;
985 struct lock_list *e;
986 int i;
987
988 /* Check whether all classes occur in a lock list. */
989 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
990 class = &lock_classes[i];
991 if (!in_list(&class->lock_entry, &all_lock_classes) &&
992 !in_list(&class->lock_entry, &free_lock_classes) &&
993 !in_any_zapped_class_list(class)) {
994 printk(KERN_INFO "class %px/%s is not in any class list\n",
995 class, class->name ? : "(?)");
996 return false;
997 }
998 }
999
1000 /* Check whether all classes have valid lock lists. */
1001 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1002 class = &lock_classes[i];
1003 if (!class_lock_list_valid(class, &class->locks_before))
1004 return false;
1005 if (!class_lock_list_valid(class, &class->locks_after))
1006 return false;
1007 }
1008
1009 /* Check the chain_key of all lock chains. */
1010 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
1011 head = chainhash_table + i;
1012 hlist_for_each_entry_rcu(chain, head, entry) {
1013 if (!check_lock_chain_key(chain))
1014 return false;
1015 }
1016 }
1017
1018 /*
1019 * Check whether all list entries that are in use occur in a class
1020 * lock list.
1021 */
1022 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1023 e = list_entries + i;
1024 if (!in_any_class_list(&e->entry)) {
1025 printk(KERN_INFO "list entry %d is not in any class list; class %s <> %s\n",
1026 (unsigned int)(e - list_entries),
1027 e->class->name ? : "(?)",
1028 e->links_to->name ? : "(?)");
1029 return false;
1030 }
1031 }
1032
1033 /*
1034 * Check whether all list entries that are not in use do not occur in
1035 * a class lock list.
1036 */
1037 for_each_clear_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1038 e = list_entries + i;
1039 if (in_any_class_list(&e->entry)) {
1040 printk(KERN_INFO "list entry %d occurs in a class list; class %s <> %s\n",
1041 (unsigned int)(e - list_entries),
1042 e->class && e->class->name ? e->class->name :
1043 "(?)",
1044 e->links_to && e->links_to->name ?
1045 e->links_to->name : "(?)");
1046 return false;
1047 }
1048 }
1049
1050 return true;
1051}
1052
1053int check_consistency = 0;
1054module_param(check_consistency, int, 0644);
1055
1056static void check_data_structures(void)
1057{
1058 static bool once = false;
1059
1060 if (check_consistency && !once) {
1061 if (!__check_data_structures()) {
1062 once = true;
1063 WARN_ON(once);
1064 }
1065 }
1066}
1067
1068#else /* CONFIG_DEBUG_LOCKDEP */
1069
1070static inline void check_data_structures(void) { }
1071
1072#endif /* CONFIG_DEBUG_LOCKDEP */
1073
1074/*
1075 * Initialize the lock_classes[] array elements, the free_lock_classes list
1076 * and also the delayed_free structure.
1077 */
1078static void init_data_structures_once(void)
1079{
1080 static bool ds_initialized, rcu_head_initialized;
1081 int i;
1082
1083 if (likely(rcu_head_initialized))
1084 return;
1085
1086 if (system_state >= SYSTEM_SCHEDULING) {
1087 init_rcu_head(&delayed_free.rcu_head);
1088 rcu_head_initialized = true;
1089 }
1090
1091 if (ds_initialized)
1092 return;
1093
1094 ds_initialized = true;
1095
1096 INIT_LIST_HEAD(&delayed_free.pf[0].zapped);
1097 INIT_LIST_HEAD(&delayed_free.pf[1].zapped);
1098
1099 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1100 list_add_tail(&lock_classes[i].lock_entry, &free_lock_classes);
1101 INIT_LIST_HEAD(&lock_classes[i].locks_after);
1102 INIT_LIST_HEAD(&lock_classes[i].locks_before);
1103 }
1104}
1105
1106static inline struct hlist_head *keyhashentry(const struct lock_class_key *key)
1107{
1108 unsigned long hash = hash_long((uintptr_t)key, KEYHASH_BITS);
1109
1110 return lock_keys_hash + hash;
1111}
1112
1113/* Register a dynamically allocated key. */
1114void lockdep_register_key(struct lock_class_key *key)
1115{
1116 struct hlist_head *hash_head;
1117 struct lock_class_key *k;
1118 unsigned long flags;
1119
1120 if (WARN_ON_ONCE(static_obj(key)))
1121 return;
1122 hash_head = keyhashentry(key);
1123
1124 raw_local_irq_save(flags);
1125 if (!graph_lock())
1126 goto restore_irqs;
1127 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1128 if (WARN_ON_ONCE(k == key))
1129 goto out_unlock;
1130 }
1131 hlist_add_head_rcu(&key->hash_entry, hash_head);
1132out_unlock:
1133 graph_unlock();
1134restore_irqs:
1135 raw_local_irq_restore(flags);
1136}
1137EXPORT_SYMBOL_GPL(lockdep_register_key);
1138
1139/* Check whether a key has been registered as a dynamic key. */
1140static bool is_dynamic_key(const struct lock_class_key *key)
1141{
1142 struct hlist_head *hash_head;
1143 struct lock_class_key *k;
1144 bool found = false;
1145
1146 if (WARN_ON_ONCE(static_obj(key)))
1147 return false;
1148
1149 /*
1150 * If lock debugging is disabled lock_keys_hash[] may contain
1151 * pointers to memory that has already been freed. Avoid triggering
1152 * a use-after-free in that case by returning early.
1153 */
1154 if (!debug_locks)
1155 return true;
1156
1157 hash_head = keyhashentry(key);
1158
1159 rcu_read_lock();
1160 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1161 if (k == key) {
1162 found = true;
1163 break;
1164 }
1165 }
1166 rcu_read_unlock();
1167
1168 return found;
1169}
1170
1171/*
1172 * Register a lock's class in the hash-table, if the class is not present
1173 * yet. Otherwise we look it up. We cache the result in the lock object
1174 * itself, so actual lookup of the hash should be once per lock object.
1175 */
1176static struct lock_class *
1177register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
1178{
1179 struct lockdep_subclass_key *key;
1180 struct hlist_head *hash_head;
1181 struct lock_class *class;
1182
1183 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1184
1185 class = look_up_lock_class(lock, subclass);
1186 if (likely(class))
1187 goto out_set_class_cache;
1188
1189 if (!lock->key) {
1190 if (!assign_lock_key(lock))
1191 return NULL;
1192 } else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) {
1193 return NULL;
1194 }
1195
1196 key = lock->key->subkeys + subclass;
1197 hash_head = classhashentry(key);
1198
1199 if (!graph_lock()) {
1200 return NULL;
1201 }
1202 /*
1203 * We have to do the hash-walk again, to avoid races
1204 * with another CPU:
1205 */
1206 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
1207 if (class->key == key)
1208 goto out_unlock_set;
1209 }
1210
1211 init_data_structures_once();
1212
1213 /* Allocate a new lock class and add it to the hash. */
1214 class = list_first_entry_or_null(&free_lock_classes, typeof(*class),
1215 lock_entry);
1216 if (!class) {
1217 if (!debug_locks_off_graph_unlock()) {
1218 return NULL;
1219 }
1220
1221 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
1222 dump_stack();
1223 return NULL;
1224 }
1225 nr_lock_classes++;
1226 __set_bit(class - lock_classes, lock_classes_in_use);
1227 debug_atomic_inc(nr_unused_locks);
1228 class->key = key;
1229 class->name = lock->name;
1230 class->subclass = subclass;
1231 WARN_ON_ONCE(!list_empty(&class->locks_before));
1232 WARN_ON_ONCE(!list_empty(&class->locks_after));
1233 class->name_version = count_matching_names(class);
1234 /*
1235 * We use RCU's safe list-add method to make
1236 * parallel walking of the hash-list safe:
1237 */
1238 hlist_add_head_rcu(&class->hash_entry, hash_head);
1239 /*
1240 * Remove the class from the free list and add it to the global list
1241 * of classes.
1242 */
1243 list_move_tail(&class->lock_entry, &all_lock_classes);
1244
1245 if (verbose(class)) {
1246 graph_unlock();
1247
1248 printk("\nnew class %px: %s", class->key, class->name);
1249 if (class->name_version > 1)
1250 printk(KERN_CONT "#%d", class->name_version);
1251 printk(KERN_CONT "\n");
1252 dump_stack();
1253
1254 if (!graph_lock()) {
1255 return NULL;
1256 }
1257 }
1258out_unlock_set:
1259 graph_unlock();
1260
1261out_set_class_cache:
1262 if (!subclass || force)
1263 lock->class_cache[0] = class;
1264 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
1265 lock->class_cache[subclass] = class;
1266
1267 /*
1268 * Hash collision, did we smoke some? We found a class with a matching
1269 * hash but the subclass -- which is hashed in -- didn't match.
1270 */
1271 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
1272 return NULL;
1273
1274 return class;
1275}
1276
1277#ifdef CONFIG_PROVE_LOCKING
1278/*
1279 * Allocate a lockdep entry. (assumes the graph_lock held, returns
1280 * with NULL on failure)
1281 */
1282static struct lock_list *alloc_list_entry(void)
1283{
1284 int idx = find_first_zero_bit(list_entries_in_use,
1285 ARRAY_SIZE(list_entries));
1286
1287 if (idx >= ARRAY_SIZE(list_entries)) {
1288 if (!debug_locks_off_graph_unlock())
1289 return NULL;
1290
1291 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
1292 dump_stack();
1293 return NULL;
1294 }
1295 nr_list_entries++;
1296 __set_bit(idx, list_entries_in_use);
1297 return list_entries + idx;
1298}
1299
1300/*
1301 * Add a new dependency to the head of the list:
1302 */
1303static int add_lock_to_list(struct lock_class *this,
1304 struct lock_class *links_to, struct list_head *head,
1305 unsigned long ip, int distance,
1306 const struct lock_trace *trace)
1307{
1308 struct lock_list *entry;
1309 /*
1310 * Lock not present yet - get a new dependency struct and
1311 * add it to the list:
1312 */
1313 entry = alloc_list_entry();
1314 if (!entry)
1315 return 0;
1316
1317 entry->class = this;
1318 entry->links_to = links_to;
1319 entry->distance = distance;
1320 entry->trace = trace;
1321 /*
1322 * Both allocation and removal are done under the graph lock; but
1323 * iteration is under RCU-sched; see look_up_lock_class() and
1324 * lockdep_free_key_range().
1325 */
1326 list_add_tail_rcu(&entry->entry, head);
1327
1328 return 1;
1329}
1330
1331/*
1332 * For good efficiency of modular, we use power of 2
1333 */
1334#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
1335#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
1336
1337/*
1338 * The circular_queue and helpers are used to implement graph
1339 * breadth-first search (BFS) algorithm, by which we can determine
1340 * whether there is a path from a lock to another. In deadlock checks,
1341 * a path from the next lock to be acquired to a previous held lock
1342 * indicates that adding the <prev> -> <next> lock dependency will
1343 * produce a circle in the graph. Breadth-first search instead of
1344 * depth-first search is used in order to find the shortest (circular)
1345 * path.
1346 */
1347struct circular_queue {
1348 struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE];
1349 unsigned int front, rear;
1350};
1351
1352static struct circular_queue lock_cq;
1353
1354unsigned int max_bfs_queue_depth;
1355
1356static unsigned int lockdep_dependency_gen_id;
1357
1358static inline void __cq_init(struct circular_queue *cq)
1359{
1360 cq->front = cq->rear = 0;
1361 lockdep_dependency_gen_id++;
1362}
1363
1364static inline int __cq_empty(struct circular_queue *cq)
1365{
1366 return (cq->front == cq->rear);
1367}
1368
1369static inline int __cq_full(struct circular_queue *cq)
1370{
1371 return ((cq->rear + 1) & CQ_MASK) == cq->front;
1372}
1373
1374static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem)
1375{
1376 if (__cq_full(cq))
1377 return -1;
1378
1379 cq->element[cq->rear] = elem;
1380 cq->rear = (cq->rear + 1) & CQ_MASK;
1381 return 0;
1382}
1383
1384/*
1385 * Dequeue an element from the circular_queue, return a lock_list if
1386 * the queue is not empty, or NULL if otherwise.
1387 */
1388static inline struct lock_list * __cq_dequeue(struct circular_queue *cq)
1389{
1390 struct lock_list * lock;
1391
1392 if (__cq_empty(cq))
1393 return NULL;
1394
1395 lock = cq->element[cq->front];
1396 cq->front = (cq->front + 1) & CQ_MASK;
1397
1398 return lock;
1399}
1400
1401static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
1402{
1403 return (cq->rear - cq->front) & CQ_MASK;
1404}
1405
1406static inline void mark_lock_accessed(struct lock_list *lock,
1407 struct lock_list *parent)
1408{
1409 unsigned long nr;
1410
1411 nr = lock - list_entries;
1412 WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */
1413 lock->parent = parent;
1414 lock->class->dep_gen_id = lockdep_dependency_gen_id;
1415}
1416
1417static inline unsigned long lock_accessed(struct lock_list *lock)
1418{
1419 unsigned long nr;
1420
1421 nr = lock - list_entries;
1422 WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */
1423 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
1424}
1425
1426static inline struct lock_list *get_lock_parent(struct lock_list *child)
1427{
1428 return child->parent;
1429}
1430
1431static inline int get_lock_depth(struct lock_list *child)
1432{
1433 int depth = 0;
1434 struct lock_list *parent;
1435
1436 while ((parent = get_lock_parent(child))) {
1437 child = parent;
1438 depth++;
1439 }
1440 return depth;
1441}
1442
1443/*
1444 * Return the forward or backward dependency list.
1445 *
1446 * @lock: the lock_list to get its class's dependency list
1447 * @offset: the offset to struct lock_class to determine whether it is
1448 * locks_after or locks_before
1449 */
1450static inline struct list_head *get_dep_list(struct lock_list *lock, int offset)
1451{
1452 void *lock_class = lock->class;
1453
1454 return lock_class + offset;
1455}
1456
1457/*
1458 * Forward- or backward-dependency search, used for both circular dependency
1459 * checking and hardirq-unsafe/softirq-unsafe checking.
1460 */
1461static int __bfs(struct lock_list *source_entry,
1462 void *data,
1463 int (*match)(struct lock_list *entry, void *data),
1464 struct lock_list **target_entry,
1465 int offset)
1466{
1467 struct lock_list *entry;
1468 struct lock_list *lock;
1469 struct list_head *head;
1470 struct circular_queue *cq = &lock_cq;
1471 int ret = 1;
1472
1473 if (match(source_entry, data)) {
1474 *target_entry = source_entry;
1475 ret = 0;
1476 goto exit;
1477 }
1478
1479 head = get_dep_list(source_entry, offset);
1480 if (list_empty(head))
1481 goto exit;
1482
1483 __cq_init(cq);
1484 __cq_enqueue(cq, source_entry);
1485
1486 while ((lock = __cq_dequeue(cq))) {
1487
1488 if (!lock->class) {
1489 ret = -2;
1490 goto exit;
1491 }
1492
1493 head = get_dep_list(lock, offset);
1494
1495 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1496
1497 list_for_each_entry_rcu(entry, head, entry) {
1498 if (!lock_accessed(entry)) {
1499 unsigned int cq_depth;
1500 mark_lock_accessed(entry, lock);
1501 if (match(entry, data)) {
1502 *target_entry = entry;
1503 ret = 0;
1504 goto exit;
1505 }
1506
1507 if (__cq_enqueue(cq, entry)) {
1508 ret = -1;
1509 goto exit;
1510 }
1511 cq_depth = __cq_get_elem_count(cq);
1512 if (max_bfs_queue_depth < cq_depth)
1513 max_bfs_queue_depth = cq_depth;
1514 }
1515 }
1516 }
1517exit:
1518 return ret;
1519}
1520
1521static inline int __bfs_forwards(struct lock_list *src_entry,
1522 void *data,
1523 int (*match)(struct lock_list *entry, void *data),
1524 struct lock_list **target_entry)
1525{
1526 return __bfs(src_entry, data, match, target_entry,
1527 offsetof(struct lock_class, locks_after));
1528
1529}
1530
1531static inline int __bfs_backwards(struct lock_list *src_entry,
1532 void *data,
1533 int (*match)(struct lock_list *entry, void *data),
1534 struct lock_list **target_entry)
1535{
1536 return __bfs(src_entry, data, match, target_entry,
1537 offsetof(struct lock_class, locks_before));
1538
1539}
1540
1541static void print_lock_trace(const struct lock_trace *trace,
1542 unsigned int spaces)
1543{
1544 stack_trace_print(trace->entries, trace->nr_entries, spaces);
1545}
1546
1547/*
1548 * Print a dependency chain entry (this is only done when a deadlock
1549 * has been detected):
1550 */
1551static noinline void
1552print_circular_bug_entry(struct lock_list *target, int depth)
1553{
1554 if (debug_locks_silent)
1555 return;
1556 printk("\n-> #%u", depth);
1557 print_lock_name(target->class);
1558 printk(KERN_CONT ":\n");
1559 print_lock_trace(target->trace, 6);
1560}
1561
1562static void
1563print_circular_lock_scenario(struct held_lock *src,
1564 struct held_lock *tgt,
1565 struct lock_list *prt)
1566{
1567 struct lock_class *source = hlock_class(src);
1568 struct lock_class *target = hlock_class(tgt);
1569 struct lock_class *parent = prt->class;
1570
1571 /*
1572 * A direct locking problem where unsafe_class lock is taken
1573 * directly by safe_class lock, then all we need to show
1574 * is the deadlock scenario, as it is obvious that the
1575 * unsafe lock is taken under the safe lock.
1576 *
1577 * But if there is a chain instead, where the safe lock takes
1578 * an intermediate lock (middle_class) where this lock is
1579 * not the same as the safe lock, then the lock chain is
1580 * used to describe the problem. Otherwise we would need
1581 * to show a different CPU case for each link in the chain
1582 * from the safe_class lock to the unsafe_class lock.
1583 */
1584 if (parent != source) {
1585 printk("Chain exists of:\n ");
1586 __print_lock_name(source);
1587 printk(KERN_CONT " --> ");
1588 __print_lock_name(parent);
1589 printk(KERN_CONT " --> ");
1590 __print_lock_name(target);
1591 printk(KERN_CONT "\n\n");
1592 }
1593
1594 printk(" Possible unsafe locking scenario:\n\n");
1595 printk(" CPU0 CPU1\n");
1596 printk(" ---- ----\n");
1597 printk(" lock(");
1598 __print_lock_name(target);
1599 printk(KERN_CONT ");\n");
1600 printk(" lock(");
1601 __print_lock_name(parent);
1602 printk(KERN_CONT ");\n");
1603 printk(" lock(");
1604 __print_lock_name(target);
1605 printk(KERN_CONT ");\n");
1606 printk(" lock(");
1607 __print_lock_name(source);
1608 printk(KERN_CONT ");\n");
1609 printk("\n *** DEADLOCK ***\n\n");
1610}
1611
1612/*
1613 * When a circular dependency is detected, print the
1614 * header first:
1615 */
1616static noinline void
1617print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1618 struct held_lock *check_src,
1619 struct held_lock *check_tgt)
1620{
1621 struct task_struct *curr = current;
1622
1623 if (debug_locks_silent)
1624 return;
1625
1626 pr_warn("\n");
1627 pr_warn("======================================================\n");
1628 pr_warn("WARNING: possible circular locking dependency detected\n");
1629 print_kernel_ident();
1630 pr_warn("------------------------------------------------------\n");
1631 pr_warn("%s/%d is trying to acquire lock:\n",
1632 curr->comm, task_pid_nr(curr));
1633 print_lock(check_src);
1634
1635 pr_warn("\nbut task is already holding lock:\n");
1636
1637 print_lock(check_tgt);
1638 pr_warn("\nwhich lock already depends on the new lock.\n\n");
1639 pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1640
1641 print_circular_bug_entry(entry, depth);
1642}
1643
1644static inline int class_equal(struct lock_list *entry, void *data)
1645{
1646 return entry->class == data;
1647}
1648
1649static noinline void print_circular_bug(struct lock_list *this,
1650 struct lock_list *target,
1651 struct held_lock *check_src,
1652 struct held_lock *check_tgt)
1653{
1654 struct task_struct *curr = current;
1655 struct lock_list *parent;
1656 struct lock_list *first_parent;
1657 int depth;
1658
1659 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1660 return;
1661
1662 this->trace = save_trace();
1663 if (!this->trace)
1664 return;
1665
1666 depth = get_lock_depth(target);
1667
1668 print_circular_bug_header(target, depth, check_src, check_tgt);
1669
1670 parent = get_lock_parent(target);
1671 first_parent = parent;
1672
1673 while (parent) {
1674 print_circular_bug_entry(parent, --depth);
1675 parent = get_lock_parent(parent);
1676 }
1677
1678 printk("\nother info that might help us debug this:\n\n");
1679 print_circular_lock_scenario(check_src, check_tgt,
1680 first_parent);
1681
1682 lockdep_print_held_locks(curr);
1683
1684 printk("\nstack backtrace:\n");
1685 dump_stack();
1686}
1687
1688static noinline void print_bfs_bug(int ret)
1689{
1690 if (!debug_locks_off_graph_unlock())
1691 return;
1692
1693 /*
1694 * Breadth-first-search failed, graph got corrupted?
1695 */
1696 WARN(1, "lockdep bfs error:%d\n", ret);
1697}
1698
1699static int noop_count(struct lock_list *entry, void *data)
1700{
1701 (*(unsigned long *)data)++;
1702 return 0;
1703}
1704
1705static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1706{
1707 unsigned long count = 0;
1708 struct lock_list *uninitialized_var(target_entry);
1709
1710 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1711
1712 return count;
1713}
1714unsigned long lockdep_count_forward_deps(struct lock_class *class)
1715{
1716 unsigned long ret, flags;
1717 struct lock_list this;
1718
1719 this.parent = NULL;
1720 this.class = class;
1721
1722 raw_local_irq_save(flags);
1723 arch_spin_lock(&lockdep_lock);
1724 ret = __lockdep_count_forward_deps(&this);
1725 arch_spin_unlock(&lockdep_lock);
1726 raw_local_irq_restore(flags);
1727
1728 return ret;
1729}
1730
1731static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1732{
1733 unsigned long count = 0;
1734 struct lock_list *uninitialized_var(target_entry);
1735
1736 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1737
1738 return count;
1739}
1740
1741unsigned long lockdep_count_backward_deps(struct lock_class *class)
1742{
1743 unsigned long ret, flags;
1744 struct lock_list this;
1745
1746 this.parent = NULL;
1747 this.class = class;
1748
1749 raw_local_irq_save(flags);
1750 arch_spin_lock(&lockdep_lock);
1751 ret = __lockdep_count_backward_deps(&this);
1752 arch_spin_unlock(&lockdep_lock);
1753 raw_local_irq_restore(flags);
1754
1755 return ret;
1756}
1757
1758/*
1759 * Check that the dependency graph starting at <src> can lead to
1760 * <target> or not. Print an error and return 0 if it does.
1761 */
1762static noinline int
1763check_path(struct lock_class *target, struct lock_list *src_entry,
1764 struct lock_list **target_entry)
1765{
1766 int ret;
1767
1768 ret = __bfs_forwards(src_entry, (void *)target, class_equal,
1769 target_entry);
1770
1771 if (unlikely(ret < 0))
1772 print_bfs_bug(ret);
1773
1774 return ret;
1775}
1776
1777/*
1778 * Prove that the dependency graph starting at <src> can not
1779 * lead to <target>. If it can, there is a circle when adding
1780 * <target> -> <src> dependency.
1781 *
1782 * Print an error and return 0 if it does.
1783 */
1784static noinline int
1785check_noncircular(struct held_lock *src, struct held_lock *target,
1786 struct lock_trace **const trace)
1787{
1788 int ret;
1789 struct lock_list *uninitialized_var(target_entry);
1790 struct lock_list src_entry = {
1791 .class = hlock_class(src),
1792 .parent = NULL,
1793 };
1794
1795 debug_atomic_inc(nr_cyclic_checks);
1796
1797 ret = check_path(hlock_class(target), &src_entry, &target_entry);
1798
1799 if (unlikely(!ret)) {
1800 if (!*trace) {
1801 /*
1802 * If save_trace fails here, the printing might
1803 * trigger a WARN but because of the !nr_entries it
1804 * should not do bad things.
1805 */
1806 *trace = save_trace();
1807 }
1808
1809 print_circular_bug(&src_entry, target_entry, src, target);
1810 }
1811
1812 return ret;
1813}
1814
1815#ifdef CONFIG_LOCKDEP_SMALL
1816/*
1817 * Check that the dependency graph starting at <src> can lead to
1818 * <target> or not. If it can, <src> -> <target> dependency is already
1819 * in the graph.
1820 *
1821 * Print an error and return 2 if it does or 1 if it does not.
1822 */
1823static noinline int
1824check_redundant(struct held_lock *src, struct held_lock *target)
1825{
1826 int ret;
1827 struct lock_list *uninitialized_var(target_entry);
1828 struct lock_list src_entry = {
1829 .class = hlock_class(src),
1830 .parent = NULL,
1831 };
1832
1833 debug_atomic_inc(nr_redundant_checks);
1834
1835 ret = check_path(hlock_class(target), &src_entry, &target_entry);
1836
1837 if (!ret) {
1838 debug_atomic_inc(nr_redundant);
1839 ret = 2;
1840 } else if (ret < 0)
1841 ret = 0;
1842
1843 return ret;
1844}
1845#endif
1846
1847#ifdef CONFIG_TRACE_IRQFLAGS
1848
1849static inline int usage_accumulate(struct lock_list *entry, void *mask)
1850{
1851 *(unsigned long *)mask |= entry->class->usage_mask;
1852
1853 return 0;
1854}
1855
1856/*
1857 * Forwards and backwards subgraph searching, for the purposes of
1858 * proving that two subgraphs can be connected by a new dependency
1859 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1860 */
1861
1862static inline int usage_match(struct lock_list *entry, void *mask)
1863{
1864 return entry->class->usage_mask & *(unsigned long *)mask;
1865}
1866
1867/*
1868 * Find a node in the forwards-direction dependency sub-graph starting
1869 * at @root->class that matches @bit.
1870 *
1871 * Return 0 if such a node exists in the subgraph, and put that node
1872 * into *@target_entry.
1873 *
1874 * Return 1 otherwise and keep *@target_entry unchanged.
1875 * Return <0 on error.
1876 */
1877static int
1878find_usage_forwards(struct lock_list *root, unsigned long usage_mask,
1879 struct lock_list **target_entry)
1880{
1881 int result;
1882
1883 debug_atomic_inc(nr_find_usage_forwards_checks);
1884
1885 result = __bfs_forwards(root, &usage_mask, usage_match, target_entry);
1886
1887 return result;
1888}
1889
1890/*
1891 * Find a node in the backwards-direction dependency sub-graph starting
1892 * at @root->class that matches @bit.
1893 *
1894 * Return 0 if such a node exists in the subgraph, and put that node
1895 * into *@target_entry.
1896 *
1897 * Return 1 otherwise and keep *@target_entry unchanged.
1898 * Return <0 on error.
1899 */
1900static int
1901find_usage_backwards(struct lock_list *root, unsigned long usage_mask,
1902 struct lock_list **target_entry)
1903{
1904 int result;
1905
1906 debug_atomic_inc(nr_find_usage_backwards_checks);
1907
1908 result = __bfs_backwards(root, &usage_mask, usage_match, target_entry);
1909
1910 return result;
1911}
1912
1913static void print_lock_class_header(struct lock_class *class, int depth)
1914{
1915 int bit;
1916
1917 printk("%*s->", depth, "");
1918 print_lock_name(class);
1919#ifdef CONFIG_DEBUG_LOCKDEP
1920 printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
1921#endif
1922 printk(KERN_CONT " {\n");
1923
1924 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1925 if (class->usage_mask & (1 << bit)) {
1926 int len = depth;
1927
1928 len += printk("%*s %s", depth, "", usage_str[bit]);
1929 len += printk(KERN_CONT " at:\n");
1930 print_lock_trace(class->usage_traces[bit], len);
1931 }
1932 }
1933 printk("%*s }\n", depth, "");
1934
1935 printk("%*s ... key at: [<%px>] %pS\n",
1936 depth, "", class->key, class->key);
1937}
1938
1939/*
1940 * printk the shortest lock dependencies from @start to @end in reverse order:
1941 */
1942static void __used
1943print_shortest_lock_dependencies(struct lock_list *leaf,
1944 struct lock_list *root)
1945{
1946 struct lock_list *entry = leaf;
1947 int depth;
1948
1949 /*compute depth from generated tree by BFS*/
1950 depth = get_lock_depth(leaf);
1951
1952 do {
1953 print_lock_class_header(entry->class, depth);
1954 printk("%*s ... acquired at:\n", depth, "");
1955 print_lock_trace(entry->trace, 2);
1956 printk("\n");
1957
1958 if (depth == 0 && (entry != root)) {
1959 printk("lockdep:%s bad path found in chain graph\n", __func__);
1960 break;
1961 }
1962
1963 entry = get_lock_parent(entry);
1964 depth--;
1965 } while (entry && (depth >= 0));
1966}
1967
1968static void
1969print_irq_lock_scenario(struct lock_list *safe_entry,
1970 struct lock_list *unsafe_entry,
1971 struct lock_class *prev_class,
1972 struct lock_class *next_class)
1973{
1974 struct lock_class *safe_class = safe_entry->class;
1975 struct lock_class *unsafe_class = unsafe_entry->class;
1976 struct lock_class *middle_class = prev_class;
1977
1978 if (middle_class == safe_class)
1979 middle_class = next_class;
1980
1981 /*
1982 * A direct locking problem where unsafe_class lock is taken
1983 * directly by safe_class lock, then all we need to show
1984 * is the deadlock scenario, as it is obvious that the
1985 * unsafe lock is taken under the safe lock.
1986 *
1987 * But if there is a chain instead, where the safe lock takes
1988 * an intermediate lock (middle_class) where this lock is
1989 * not the same as the safe lock, then the lock chain is
1990 * used to describe the problem. Otherwise we would need
1991 * to show a different CPU case for each link in the chain
1992 * from the safe_class lock to the unsafe_class lock.
1993 */
1994 if (middle_class != unsafe_class) {
1995 printk("Chain exists of:\n ");
1996 __print_lock_name(safe_class);
1997 printk(KERN_CONT " --> ");
1998 __print_lock_name(middle_class);
1999 printk(KERN_CONT " --> ");
2000 __print_lock_name(unsafe_class);
2001 printk(KERN_CONT "\n\n");
2002 }
2003
2004 printk(" Possible interrupt unsafe locking scenario:\n\n");
2005 printk(" CPU0 CPU1\n");
2006 printk(" ---- ----\n");
2007 printk(" lock(");
2008 __print_lock_name(unsafe_class);
2009 printk(KERN_CONT ");\n");
2010 printk(" local_irq_disable();\n");
2011 printk(" lock(");
2012 __print_lock_name(safe_class);
2013 printk(KERN_CONT ");\n");
2014 printk(" lock(");
2015 __print_lock_name(middle_class);
2016 printk(KERN_CONT ");\n");
2017 printk(" <Interrupt>\n");
2018 printk(" lock(");
2019 __print_lock_name(safe_class);
2020 printk(KERN_CONT ");\n");
2021 printk("\n *** DEADLOCK ***\n\n");
2022}
2023
2024static void
2025print_bad_irq_dependency(struct task_struct *curr,
2026 struct lock_list *prev_root,
2027 struct lock_list *next_root,
2028 struct lock_list *backwards_entry,
2029 struct lock_list *forwards_entry,
2030 struct held_lock *prev,
2031 struct held_lock *next,
2032 enum lock_usage_bit bit1,
2033 enum lock_usage_bit bit2,
2034 const char *irqclass)
2035{
2036 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2037 return;
2038
2039 pr_warn("\n");
2040 pr_warn("=====================================================\n");
2041 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
2042 irqclass, irqclass);
2043 print_kernel_ident();
2044 pr_warn("-----------------------------------------------------\n");
2045 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
2046 curr->comm, task_pid_nr(curr),
2047 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
2048 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
2049 curr->hardirqs_enabled,
2050 curr->softirqs_enabled);
2051 print_lock(next);
2052
2053 pr_warn("\nand this task is already holding:\n");
2054 print_lock(prev);
2055 pr_warn("which would create a new lock dependency:\n");
2056 print_lock_name(hlock_class(prev));
2057 pr_cont(" ->");
2058 print_lock_name(hlock_class(next));
2059 pr_cont("\n");
2060
2061 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
2062 irqclass);
2063 print_lock_name(backwards_entry->class);
2064 pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
2065
2066 print_lock_trace(backwards_entry->class->usage_traces[bit1], 1);
2067
2068 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
2069 print_lock_name(forwards_entry->class);
2070 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
2071 pr_warn("...");
2072
2073 print_lock_trace(forwards_entry->class->usage_traces[bit2], 1);
2074
2075 pr_warn("\nother info that might help us debug this:\n\n");
2076 print_irq_lock_scenario(backwards_entry, forwards_entry,
2077 hlock_class(prev), hlock_class(next));
2078
2079 lockdep_print_held_locks(curr);
2080
2081 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
2082 prev_root->trace = save_trace();
2083 if (!prev_root->trace)
2084 return;
2085 print_shortest_lock_dependencies(backwards_entry, prev_root);
2086
2087 pr_warn("\nthe dependencies between the lock to be acquired");
2088 pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
2089 next_root->trace = save_trace();
2090 if (!next_root->trace)
2091 return;
2092 print_shortest_lock_dependencies(forwards_entry, next_root);
2093
2094 pr_warn("\nstack backtrace:\n");
2095 dump_stack();
2096}
2097
2098static const char *state_names[] = {
2099#define LOCKDEP_STATE(__STATE) \
2100 __stringify(__STATE),
2101#include "lockdep_states.h"
2102#undef LOCKDEP_STATE
2103};
2104
2105static const char *state_rnames[] = {
2106#define LOCKDEP_STATE(__STATE) \
2107 __stringify(__STATE)"-READ",
2108#include "lockdep_states.h"
2109#undef LOCKDEP_STATE
2110};
2111
2112static inline const char *state_name(enum lock_usage_bit bit)
2113{
2114 if (bit & LOCK_USAGE_READ_MASK)
2115 return state_rnames[bit >> LOCK_USAGE_DIR_MASK];
2116 else
2117 return state_names[bit >> LOCK_USAGE_DIR_MASK];
2118}
2119
2120/*
2121 * The bit number is encoded like:
2122 *
2123 * bit0: 0 exclusive, 1 read lock
2124 * bit1: 0 used in irq, 1 irq enabled
2125 * bit2-n: state
2126 */
2127static int exclusive_bit(int new_bit)
2128{
2129 int state = new_bit & LOCK_USAGE_STATE_MASK;
2130 int dir = new_bit & LOCK_USAGE_DIR_MASK;
2131
2132 /*
2133 * keep state, bit flip the direction and strip read.
2134 */
2135 return state | (dir ^ LOCK_USAGE_DIR_MASK);
2136}
2137
2138/*
2139 * Observe that when given a bitmask where each bitnr is encoded as above, a
2140 * right shift of the mask transforms the individual bitnrs as -1 and
2141 * conversely, a left shift transforms into +1 for the individual bitnrs.
2142 *
2143 * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can
2144 * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0)
2145 * instead by subtracting the bit number by 2, or shifting the mask right by 2.
2146 *
2147 * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2.
2148 *
2149 * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is
2150 * all bits set) and recompose with bitnr1 flipped.
2151 */
2152static unsigned long invert_dir_mask(unsigned long mask)
2153{
2154 unsigned long excl = 0;
2155
2156 /* Invert dir */
2157 excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK;
2158 excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK;
2159
2160 return excl;
2161}
2162
2163/*
2164 * As above, we clear bitnr0 (LOCK_*_READ off) with bitmask ops. First, for all
2165 * bits with bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*).
2166 * And then mask out all bitnr0.
2167 */
2168static unsigned long exclusive_mask(unsigned long mask)
2169{
2170 unsigned long excl = invert_dir_mask(mask);
2171
2172 /* Strip read */
2173 excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
2174 excl &= ~LOCKF_IRQ_READ;
2175
2176 return excl;
2177}
2178
2179/*
2180 * Retrieve the _possible_ original mask to which @mask is
2181 * exclusive. Ie: this is the opposite of exclusive_mask().
2182 * Note that 2 possible original bits can match an exclusive
2183 * bit: one has LOCK_USAGE_READ_MASK set, the other has it
2184 * cleared. So both are returned for each exclusive bit.
2185 */
2186static unsigned long original_mask(unsigned long mask)
2187{
2188 unsigned long excl = invert_dir_mask(mask);
2189
2190 /* Include read in existing usages */
2191 excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
2192
2193 return excl;
2194}
2195
2196/*
2197 * Find the first pair of bit match between an original
2198 * usage mask and an exclusive usage mask.
2199 */
2200static int find_exclusive_match(unsigned long mask,
2201 unsigned long excl_mask,
2202 enum lock_usage_bit *bitp,
2203 enum lock_usage_bit *excl_bitp)
2204{
2205 int bit, excl;
2206
2207 for_each_set_bit(bit, &mask, LOCK_USED) {
2208 excl = exclusive_bit(bit);
2209 if (excl_mask & lock_flag(excl)) {
2210 *bitp = bit;
2211 *excl_bitp = excl;
2212 return 0;
2213 }
2214 }
2215 return -1;
2216}
2217
2218/*
2219 * Prove that the new dependency does not connect a hardirq-safe(-read)
2220 * lock with a hardirq-unsafe lock - to achieve this we search
2221 * the backwards-subgraph starting at <prev>, and the
2222 * forwards-subgraph starting at <next>:
2223 */
2224static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
2225 struct held_lock *next)
2226{
2227 unsigned long usage_mask = 0, forward_mask, backward_mask;
2228 enum lock_usage_bit forward_bit = 0, backward_bit = 0;
2229 struct lock_list *uninitialized_var(target_entry1);
2230 struct lock_list *uninitialized_var(target_entry);
2231 struct lock_list this, that;
2232 int ret;
2233
2234 /*
2235 * Step 1: gather all hard/soft IRQs usages backward in an
2236 * accumulated usage mask.
2237 */
2238 this.parent = NULL;
2239 this.class = hlock_class(prev);
2240
2241 ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL);
2242 if (ret < 0) {
2243 print_bfs_bug(ret);
2244 return 0;
2245 }
2246
2247 usage_mask &= LOCKF_USED_IN_IRQ_ALL;
2248 if (!usage_mask)
2249 return 1;
2250
2251 /*
2252 * Step 2: find exclusive uses forward that match the previous
2253 * backward accumulated mask.
2254 */
2255 forward_mask = exclusive_mask(usage_mask);
2256
2257 that.parent = NULL;
2258 that.class = hlock_class(next);
2259
2260 ret = find_usage_forwards(&that, forward_mask, &target_entry1);
2261 if (ret < 0) {
2262 print_bfs_bug(ret);
2263 return 0;
2264 }
2265 if (ret == 1)
2266 return ret;
2267
2268 /*
2269 * Step 3: we found a bad match! Now retrieve a lock from the backward
2270 * list whose usage mask matches the exclusive usage mask from the
2271 * lock found on the forward list.
2272 */
2273 backward_mask = original_mask(target_entry1->class->usage_mask);
2274
2275 ret = find_usage_backwards(&this, backward_mask, &target_entry);
2276 if (ret < 0) {
2277 print_bfs_bug(ret);
2278 return 0;
2279 }
2280 if (DEBUG_LOCKS_WARN_ON(ret == 1))
2281 return 1;
2282
2283 /*
2284 * Step 4: narrow down to a pair of incompatible usage bits
2285 * and report it.
2286 */
2287 ret = find_exclusive_match(target_entry->class->usage_mask,
2288 target_entry1->class->usage_mask,
2289 &backward_bit, &forward_bit);
2290 if (DEBUG_LOCKS_WARN_ON(ret == -1))
2291 return 1;
2292
2293 print_bad_irq_dependency(curr, &this, &that,
2294 target_entry, target_entry1,
2295 prev, next,
2296 backward_bit, forward_bit,
2297 state_name(backward_bit));
2298
2299 return 0;
2300}
2301
2302static void inc_chains(void)
2303{
2304 if (current->hardirq_context)
2305 nr_hardirq_chains++;
2306 else {
2307 if (current->softirq_context)
2308 nr_softirq_chains++;
2309 else
2310 nr_process_chains++;
2311 }
2312}
2313
2314#else
2315
2316static inline int check_irq_usage(struct task_struct *curr,
2317 struct held_lock *prev, struct held_lock *next)
2318{
2319 return 1;
2320}
2321
2322static inline void inc_chains(void)
2323{
2324 nr_process_chains++;
2325}
2326
2327#endif /* CONFIG_TRACE_IRQFLAGS */
2328
2329static void
2330print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
2331{
2332 struct lock_class *next = hlock_class(nxt);
2333 struct lock_class *prev = hlock_class(prv);
2334
2335 printk(" Possible unsafe locking scenario:\n\n");
2336 printk(" CPU0\n");
2337 printk(" ----\n");
2338 printk(" lock(");
2339 __print_lock_name(prev);
2340 printk(KERN_CONT ");\n");
2341 printk(" lock(");
2342 __print_lock_name(next);
2343 printk(KERN_CONT ");\n");
2344 printk("\n *** DEADLOCK ***\n\n");
2345 printk(" May be due to missing lock nesting notation\n\n");
2346}
2347
2348static void
2349print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
2350 struct held_lock *next)
2351{
2352 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2353 return;
2354
2355 pr_warn("\n");
2356 pr_warn("============================================\n");
2357 pr_warn("WARNING: possible recursive locking detected\n");
2358 print_kernel_ident();
2359 pr_warn("--------------------------------------------\n");
2360 pr_warn("%s/%d is trying to acquire lock:\n",
2361 curr->comm, task_pid_nr(curr));
2362 print_lock(next);
2363 pr_warn("\nbut task is already holding lock:\n");
2364 print_lock(prev);
2365
2366 pr_warn("\nother info that might help us debug this:\n");
2367 print_deadlock_scenario(next, prev);
2368 lockdep_print_held_locks(curr);
2369
2370 pr_warn("\nstack backtrace:\n");
2371 dump_stack();
2372}
2373
2374/*
2375 * Check whether we are holding such a class already.
2376 *
2377 * (Note that this has to be done separately, because the graph cannot
2378 * detect such classes of deadlocks.)
2379 *
2380 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
2381 */
2382static int
2383check_deadlock(struct task_struct *curr, struct held_lock *next)
2384{
2385 struct held_lock *prev;
2386 struct held_lock *nest = NULL;
2387 int i;
2388
2389 for (i = 0; i < curr->lockdep_depth; i++) {
2390 prev = curr->held_locks + i;
2391
2392 if (prev->instance == next->nest_lock)
2393 nest = prev;
2394
2395 if (hlock_class(prev) != hlock_class(next))
2396 continue;
2397
2398 /*
2399 * Allow read-after-read recursion of the same
2400 * lock class (i.e. read_lock(lock)+read_lock(lock)):
2401 */
2402 if ((next->read == 2) && prev->read)
2403 return 2;
2404
2405 /*
2406 * We're holding the nest_lock, which serializes this lock's
2407 * nesting behaviour.
2408 */
2409 if (nest)
2410 return 2;
2411
2412 print_deadlock_bug(curr, prev, next);
2413 return 0;
2414 }
2415 return 1;
2416}
2417
2418/*
2419 * There was a chain-cache miss, and we are about to add a new dependency
2420 * to a previous lock. We validate the following rules:
2421 *
2422 * - would the adding of the <prev> -> <next> dependency create a
2423 * circular dependency in the graph? [== circular deadlock]
2424 *
2425 * - does the new prev->next dependency connect any hardirq-safe lock
2426 * (in the full backwards-subgraph starting at <prev>) with any
2427 * hardirq-unsafe lock (in the full forwards-subgraph starting at
2428 * <next>)? [== illegal lock inversion with hardirq contexts]
2429 *
2430 * - does the new prev->next dependency connect any softirq-safe lock
2431 * (in the full backwards-subgraph starting at <prev>) with any
2432 * softirq-unsafe lock (in the full forwards-subgraph starting at
2433 * <next>)? [== illegal lock inversion with softirq contexts]
2434 *
2435 * any of these scenarios could lead to a deadlock.
2436 *
2437 * Then if all the validations pass, we add the forwards and backwards
2438 * dependency.
2439 */
2440static int
2441check_prev_add(struct task_struct *curr, struct held_lock *prev,
2442 struct held_lock *next, int distance,
2443 struct lock_trace **const trace)
2444{
2445 struct lock_list *entry;
2446 int ret;
2447
2448 if (!hlock_class(prev)->key || !hlock_class(next)->key) {
2449 /*
2450 * The warning statements below may trigger a use-after-free
2451 * of the class name. It is better to trigger a use-after free
2452 * and to have the class name most of the time instead of not
2453 * having the class name available.
2454 */
2455 WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key,
2456 "Detected use-after-free of lock class %px/%s\n",
2457 hlock_class(prev),
2458 hlock_class(prev)->name);
2459 WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key,
2460 "Detected use-after-free of lock class %px/%s\n",
2461 hlock_class(next),
2462 hlock_class(next)->name);
2463 return 2;
2464 }
2465
2466 /*
2467 * Prove that the new <prev> -> <next> dependency would not
2468 * create a circular dependency in the graph. (We do this by
2469 * a breadth-first search into the graph starting at <next>,
2470 * and check whether we can reach <prev>.)
2471 *
2472 * The search is limited by the size of the circular queue (i.e.,
2473 * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes
2474 * in the graph whose neighbours are to be checked.
2475 */
2476 ret = check_noncircular(next, prev, trace);
2477 if (unlikely(ret <= 0))
2478 return 0;
2479
2480 if (!check_irq_usage(curr, prev, next))
2481 return 0;
2482
2483 /*
2484 * For recursive read-locks we do all the dependency checks,
2485 * but we dont store read-triggered dependencies (only
2486 * write-triggered dependencies). This ensures that only the
2487 * write-side dependencies matter, and that if for example a
2488 * write-lock never takes any other locks, then the reads are
2489 * equivalent to a NOP.
2490 */
2491 if (next->read == 2 || prev->read == 2)
2492 return 1;
2493 /*
2494 * Is the <prev> -> <next> dependency already present?
2495 *
2496 * (this may occur even though this is a new chain: consider
2497 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
2498 * chains - the second one will be new, but L1 already has
2499 * L2 added to its dependency list, due to the first chain.)
2500 */
2501 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
2502 if (entry->class == hlock_class(next)) {
2503 if (distance == 1)
2504 entry->distance = 1;
2505 return 1;
2506 }
2507 }
2508
2509#ifdef CONFIG_LOCKDEP_SMALL
2510 /*
2511 * Is the <prev> -> <next> link redundant?
2512 */
2513 ret = check_redundant(prev, next);
2514 if (ret != 1)
2515 return ret;
2516#endif
2517
2518 if (!*trace) {
2519 *trace = save_trace();
2520 if (!*trace)
2521 return 0;
2522 }
2523
2524 /*
2525 * Ok, all validations passed, add the new lock
2526 * to the previous lock's dependency list:
2527 */
2528 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
2529 &hlock_class(prev)->locks_after,
2530 next->acquire_ip, distance, *trace);
2531
2532 if (!ret)
2533 return 0;
2534
2535 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
2536 &hlock_class(next)->locks_before,
2537 next->acquire_ip, distance, *trace);
2538 if (!ret)
2539 return 0;
2540
2541 return 2;
2542}
2543
2544/*
2545 * Add the dependency to all directly-previous locks that are 'relevant'.
2546 * The ones that are relevant are (in increasing distance from curr):
2547 * all consecutive trylock entries and the final non-trylock entry - or
2548 * the end of this context's lock-chain - whichever comes first.
2549 */
2550static int
2551check_prevs_add(struct task_struct *curr, struct held_lock *next)
2552{
2553 struct lock_trace *trace = NULL;
2554 int depth = curr->lockdep_depth;
2555 struct held_lock *hlock;
2556
2557 /*
2558 * Debugging checks.
2559 *
2560 * Depth must not be zero for a non-head lock:
2561 */
2562 if (!depth)
2563 goto out_bug;
2564 /*
2565 * At least two relevant locks must exist for this
2566 * to be a head:
2567 */
2568 if (curr->held_locks[depth].irq_context !=
2569 curr->held_locks[depth-1].irq_context)
2570 goto out_bug;
2571
2572 for (;;) {
2573 int distance = curr->lockdep_depth - depth + 1;
2574 hlock = curr->held_locks + depth - 1;
2575
2576 /*
2577 * Only non-recursive-read entries get new dependencies
2578 * added:
2579 */
2580 if (hlock->read != 2 && hlock->check) {
2581 int ret = check_prev_add(curr, hlock, next, distance,
2582 &trace);
2583 if (!ret)
2584 return 0;
2585
2586 /*
2587 * Stop after the first non-trylock entry,
2588 * as non-trylock entries have added their
2589 * own direct dependencies already, so this
2590 * lock is connected to them indirectly:
2591 */
2592 if (!hlock->trylock)
2593 break;
2594 }
2595
2596 depth--;
2597 /*
2598 * End of lock-stack?
2599 */
2600 if (!depth)
2601 break;
2602 /*
2603 * Stop the search if we cross into another context:
2604 */
2605 if (curr->held_locks[depth].irq_context !=
2606 curr->held_locks[depth-1].irq_context)
2607 break;
2608 }
2609 return 1;
2610out_bug:
2611 if (!debug_locks_off_graph_unlock())
2612 return 0;
2613
2614 /*
2615 * Clearly we all shouldn't be here, but since we made it we
2616 * can reliable say we messed up our state. See the above two
2617 * gotos for reasons why we could possibly end up here.
2618 */
2619 WARN_ON(1);
2620
2621 return 0;
2622}
2623
2624struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
2625static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS);
2626int nr_chain_hlocks;
2627static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
2628
2629struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
2630{
2631 return lock_classes + chain_hlocks[chain->base + i];
2632}
2633
2634/*
2635 * Returns the index of the first held_lock of the current chain
2636 */
2637static inline int get_first_held_lock(struct task_struct *curr,
2638 struct held_lock *hlock)
2639{
2640 int i;
2641 struct held_lock *hlock_curr;
2642
2643 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2644 hlock_curr = curr->held_locks + i;
2645 if (hlock_curr->irq_context != hlock->irq_context)
2646 break;
2647
2648 }
2649
2650 return ++i;
2651}
2652
2653#ifdef CONFIG_DEBUG_LOCKDEP
2654/*
2655 * Returns the next chain_key iteration
2656 */
2657static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2658{
2659 u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2660
2661 printk(" class_idx:%d -> chain_key:%016Lx",
2662 class_idx,
2663 (unsigned long long)new_chain_key);
2664 return new_chain_key;
2665}
2666
2667static void
2668print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2669{
2670 struct held_lock *hlock;
2671 u64 chain_key = INITIAL_CHAIN_KEY;
2672 int depth = curr->lockdep_depth;
2673 int i = get_first_held_lock(curr, hlock_next);
2674
2675 printk("depth: %u (irq_context %u)\n", depth - i + 1,
2676 hlock_next->irq_context);
2677 for (; i < depth; i++) {
2678 hlock = curr->held_locks + i;
2679 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2680
2681 print_lock(hlock);
2682 }
2683
2684 print_chain_key_iteration(hlock_next->class_idx, chain_key);
2685 print_lock(hlock_next);
2686}
2687
2688static void print_chain_keys_chain(struct lock_chain *chain)
2689{
2690 int i;
2691 u64 chain_key = INITIAL_CHAIN_KEY;
2692 int class_id;
2693
2694 printk("depth: %u\n", chain->depth);
2695 for (i = 0; i < chain->depth; i++) {
2696 class_id = chain_hlocks[chain->base + i];
2697 chain_key = print_chain_key_iteration(class_id, chain_key);
2698
2699 print_lock_name(lock_classes + class_id);
2700 printk("\n");
2701 }
2702}
2703
2704static void print_collision(struct task_struct *curr,
2705 struct held_lock *hlock_next,
2706 struct lock_chain *chain)
2707{
2708 pr_warn("\n");
2709 pr_warn("============================\n");
2710 pr_warn("WARNING: chain_key collision\n");
2711 print_kernel_ident();
2712 pr_warn("----------------------------\n");
2713 pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
2714 pr_warn("Hash chain already cached but the contents don't match!\n");
2715
2716 pr_warn("Held locks:");
2717 print_chain_keys_held_locks(curr, hlock_next);
2718
2719 pr_warn("Locks in cached chain:");
2720 print_chain_keys_chain(chain);
2721
2722 pr_warn("\nstack backtrace:\n");
2723 dump_stack();
2724}
2725#endif
2726
2727/*
2728 * Checks whether the chain and the current held locks are consistent
2729 * in depth and also in content. If they are not it most likely means
2730 * that there was a collision during the calculation of the chain_key.
2731 * Returns: 0 not passed, 1 passed
2732 */
2733static int check_no_collision(struct task_struct *curr,
2734 struct held_lock *hlock,
2735 struct lock_chain *chain)
2736{
2737#ifdef CONFIG_DEBUG_LOCKDEP
2738 int i, j, id;
2739
2740 i = get_first_held_lock(curr, hlock);
2741
2742 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2743 print_collision(curr, hlock, chain);
2744 return 0;
2745 }
2746
2747 for (j = 0; j < chain->depth - 1; j++, i++) {
2748 id = curr->held_locks[i].class_idx;
2749
2750 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2751 print_collision(curr, hlock, chain);
2752 return 0;
2753 }
2754 }
2755#endif
2756 return 1;
2757}
2758
2759/*
2760 * Given an index that is >= -1, return the index of the next lock chain.
2761 * Return -2 if there is no next lock chain.
2762 */
2763long lockdep_next_lockchain(long i)
2764{
2765 i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1);
2766 return i < ARRAY_SIZE(lock_chains) ? i : -2;
2767}
2768
2769unsigned long lock_chain_count(void)
2770{
2771 return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains));
2772}
2773
2774/* Must be called with the graph lock held. */
2775static struct lock_chain *alloc_lock_chain(void)
2776{
2777 int idx = find_first_zero_bit(lock_chains_in_use,
2778 ARRAY_SIZE(lock_chains));
2779
2780 if (unlikely(idx >= ARRAY_SIZE(lock_chains)))
2781 return NULL;
2782 __set_bit(idx, lock_chains_in_use);
2783 return lock_chains + idx;
2784}
2785
2786/*
2787 * Adds a dependency chain into chain hashtable. And must be called with
2788 * graph_lock held.
2789 *
2790 * Return 0 if fail, and graph_lock is released.
2791 * Return 1 if succeed, with graph_lock held.
2792 */
2793static inline int add_chain_cache(struct task_struct *curr,
2794 struct held_lock *hlock,
2795 u64 chain_key)
2796{
2797 struct lock_class *class = hlock_class(hlock);
2798 struct hlist_head *hash_head = chainhashentry(chain_key);
2799 struct lock_chain *chain;
2800 int i, j;
2801
2802 /*
2803 * The caller must hold the graph lock, ensure we've got IRQs
2804 * disabled to make this an IRQ-safe lock.. for recursion reasons
2805 * lockdep won't complain about its own locking errors.
2806 */
2807 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2808 return 0;
2809
2810 chain = alloc_lock_chain();
2811 if (!chain) {
2812 if (!debug_locks_off_graph_unlock())
2813 return 0;
2814
2815 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2816 dump_stack();
2817 return 0;
2818 }
2819 chain->chain_key = chain_key;
2820 chain->irq_context = hlock->irq_context;
2821 i = get_first_held_lock(curr, hlock);
2822 chain->depth = curr->lockdep_depth + 1 - i;
2823
2824 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2825 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
2826 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2827
2828 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2829 chain->base = nr_chain_hlocks;
2830 for (j = 0; j < chain->depth - 1; j++, i++) {
2831 int lock_id = curr->held_locks[i].class_idx;
2832 chain_hlocks[chain->base + j] = lock_id;
2833 }
2834 chain_hlocks[chain->base + j] = class - lock_classes;
2835 nr_chain_hlocks += chain->depth;
2836 } else {
2837 if (!debug_locks_off_graph_unlock())
2838 return 0;
2839
2840 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2841 dump_stack();
2842 return 0;
2843 }
2844
2845 hlist_add_head_rcu(&chain->entry, hash_head);
2846 debug_atomic_inc(chain_lookup_misses);
2847 inc_chains();
2848
2849 return 1;
2850}
2851
2852/*
2853 * Look up a dependency chain. Must be called with either the graph lock or
2854 * the RCU read lock held.
2855 */
2856static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
2857{
2858 struct hlist_head *hash_head = chainhashentry(chain_key);
2859 struct lock_chain *chain;
2860
2861 hlist_for_each_entry_rcu(chain, hash_head, entry) {
2862 if (READ_ONCE(chain->chain_key) == chain_key) {
2863 debug_atomic_inc(chain_lookup_hits);
2864 return chain;
2865 }
2866 }
2867 return NULL;
2868}
2869
2870/*
2871 * If the key is not present yet in dependency chain cache then
2872 * add it and return 1 - in this case the new dependency chain is
2873 * validated. If the key is already hashed, return 0.
2874 * (On return with 1 graph_lock is held.)
2875 */
2876static inline int lookup_chain_cache_add(struct task_struct *curr,
2877 struct held_lock *hlock,
2878 u64 chain_key)
2879{
2880 struct lock_class *class = hlock_class(hlock);
2881 struct lock_chain *chain = lookup_chain_cache(chain_key);
2882
2883 if (chain) {
2884cache_hit:
2885 if (!check_no_collision(curr, hlock, chain))
2886 return 0;
2887
2888 if (very_verbose(class)) {
2889 printk("\nhash chain already cached, key: "
2890 "%016Lx tail class: [%px] %s\n",
2891 (unsigned long long)chain_key,
2892 class->key, class->name);
2893 }
2894
2895 return 0;
2896 }
2897
2898 if (very_verbose(class)) {
2899 printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
2900 (unsigned long long)chain_key, class->key, class->name);
2901 }
2902
2903 if (!graph_lock())
2904 return 0;
2905
2906 /*
2907 * We have to walk the chain again locked - to avoid duplicates:
2908 */
2909 chain = lookup_chain_cache(chain_key);
2910 if (chain) {
2911 graph_unlock();
2912 goto cache_hit;
2913 }
2914
2915 if (!add_chain_cache(curr, hlock, chain_key))
2916 return 0;
2917
2918 return 1;
2919}
2920
2921static int validate_chain(struct task_struct *curr,
2922 struct held_lock *hlock,
2923 int chain_head, u64 chain_key)
2924{
2925 /*
2926 * Trylock needs to maintain the stack of held locks, but it
2927 * does not add new dependencies, because trylock can be done
2928 * in any order.
2929 *
2930 * We look up the chain_key and do the O(N^2) check and update of
2931 * the dependencies only if this is a new dependency chain.
2932 * (If lookup_chain_cache_add() return with 1 it acquires
2933 * graph_lock for us)
2934 */
2935 if (!hlock->trylock && hlock->check &&
2936 lookup_chain_cache_add(curr, hlock, chain_key)) {
2937 /*
2938 * Check whether last held lock:
2939 *
2940 * - is irq-safe, if this lock is irq-unsafe
2941 * - is softirq-safe, if this lock is hardirq-unsafe
2942 *
2943 * And check whether the new lock's dependency graph
2944 * could lead back to the previous lock:
2945 *
2946 * - within the current held-lock stack
2947 * - across our accumulated lock dependency records
2948 *
2949 * any of these scenarios could lead to a deadlock.
2950 */
2951 /*
2952 * The simple case: does the current hold the same lock
2953 * already?
2954 */
2955 int ret = check_deadlock(curr, hlock);
2956
2957 if (!ret)
2958 return 0;
2959 /*
2960 * Mark recursive read, as we jump over it when
2961 * building dependencies (just like we jump over
2962 * trylock entries):
2963 */
2964 if (ret == 2)
2965 hlock->read = 2;
2966 /*
2967 * Add dependency only if this lock is not the head
2968 * of the chain, and if it's not a secondary read-lock:
2969 */
2970 if (!chain_head && ret != 2) {
2971 if (!check_prevs_add(curr, hlock))
2972 return 0;
2973 }
2974
2975 graph_unlock();
2976 } else {
2977 /* after lookup_chain_cache_add(): */
2978 if (unlikely(!debug_locks))
2979 return 0;
2980 }
2981
2982 return 1;
2983}
2984#else
2985static inline int validate_chain(struct task_struct *curr,
2986 struct held_lock *hlock,
2987 int chain_head, u64 chain_key)
2988{
2989 return 1;
2990}
2991#endif /* CONFIG_PROVE_LOCKING */
2992
2993/*
2994 * We are building curr_chain_key incrementally, so double-check
2995 * it from scratch, to make sure that it's done correctly:
2996 */
2997static void check_chain_key(struct task_struct *curr)
2998{
2999#ifdef CONFIG_DEBUG_LOCKDEP
3000 struct held_lock *hlock, *prev_hlock = NULL;
3001 unsigned int i;
3002 u64 chain_key = INITIAL_CHAIN_KEY;
3003
3004 for (i = 0; i < curr->lockdep_depth; i++) {
3005 hlock = curr->held_locks + i;
3006 if (chain_key != hlock->prev_chain_key) {
3007 debug_locks_off();
3008 /*
3009 * We got mighty confused, our chain keys don't match
3010 * with what we expect, someone trample on our task state?
3011 */
3012 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
3013 curr->lockdep_depth, i,
3014 (unsigned long long)chain_key,
3015 (unsigned long long)hlock->prev_chain_key);
3016 return;
3017 }
3018
3019 /*
3020 * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is
3021 * it registered lock class index?
3022 */
3023 if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use)))
3024 return;
3025
3026 if (prev_hlock && (prev_hlock->irq_context !=
3027 hlock->irq_context))
3028 chain_key = INITIAL_CHAIN_KEY;
3029 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
3030 prev_hlock = hlock;
3031 }
3032 if (chain_key != curr->curr_chain_key) {
3033 debug_locks_off();
3034 /*
3035 * More smoking hash instead of calculating it, damn see these
3036 * numbers float.. I bet that a pink elephant stepped on my memory.
3037 */
3038 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
3039 curr->lockdep_depth, i,
3040 (unsigned long long)chain_key,
3041 (unsigned long long)curr->curr_chain_key);
3042 }
3043#endif
3044}
3045
3046#ifdef CONFIG_PROVE_LOCKING
3047static int mark_lock(struct task_struct *curr, struct held_lock *this,
3048 enum lock_usage_bit new_bit);
3049
3050static void print_usage_bug_scenario(struct held_lock *lock)
3051{
3052 struct lock_class *class = hlock_class(lock);
3053
3054 printk(" Possible unsafe locking scenario:\n\n");
3055 printk(" CPU0\n");
3056 printk(" ----\n");
3057 printk(" lock(");
3058 __print_lock_name(class);
3059 printk(KERN_CONT ");\n");
3060 printk(" <Interrupt>\n");
3061 printk(" lock(");
3062 __print_lock_name(class);
3063 printk(KERN_CONT ");\n");
3064 printk("\n *** DEADLOCK ***\n\n");
3065}
3066
3067static void
3068print_usage_bug(struct task_struct *curr, struct held_lock *this,
3069 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
3070{
3071 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
3072 return;
3073
3074 pr_warn("\n");
3075 pr_warn("================================\n");
3076 pr_warn("WARNING: inconsistent lock state\n");
3077 print_kernel_ident();
3078 pr_warn("--------------------------------\n");
3079
3080 pr_warn("inconsistent {%s} -> {%s} usage.\n",
3081 usage_str[prev_bit], usage_str[new_bit]);
3082
3083 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
3084 curr->comm, task_pid_nr(curr),
3085 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
3086 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
3087 trace_hardirqs_enabled(curr),
3088 trace_softirqs_enabled(curr));
3089 print_lock(this);
3090
3091 pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
3092 print_lock_trace(hlock_class(this)->usage_traces[prev_bit], 1);
3093
3094 print_irqtrace_events(curr);
3095 pr_warn("\nother info that might help us debug this:\n");
3096 print_usage_bug_scenario(this);
3097
3098 lockdep_print_held_locks(curr);
3099
3100 pr_warn("\nstack backtrace:\n");
3101 dump_stack();
3102}
3103
3104/*
3105 * Print out an error if an invalid bit is set:
3106 */
3107static inline int
3108valid_state(struct task_struct *curr, struct held_lock *this,
3109 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
3110{
3111 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) {
3112 print_usage_bug(curr, this, bad_bit, new_bit);
3113 return 0;
3114 }
3115 return 1;
3116}
3117
3118
3119/*
3120 * print irq inversion bug:
3121 */
3122static void
3123print_irq_inversion_bug(struct task_struct *curr,
3124 struct lock_list *root, struct lock_list *other,
3125 struct held_lock *this, int forwards,
3126 const char *irqclass)
3127{
3128 struct lock_list *entry = other;
3129 struct lock_list *middle = NULL;
3130 int depth;
3131
3132 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
3133 return;
3134
3135 pr_warn("\n");
3136 pr_warn("========================================================\n");
3137 pr_warn("WARNING: possible irq lock inversion dependency detected\n");
3138 print_kernel_ident();
3139 pr_warn("--------------------------------------------------------\n");
3140 pr_warn("%s/%d just changed the state of lock:\n",
3141 curr->comm, task_pid_nr(curr));
3142 print_lock(this);
3143 if (forwards)
3144 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
3145 else
3146 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
3147 print_lock_name(other->class);
3148 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
3149
3150 pr_warn("\nother info that might help us debug this:\n");
3151
3152 /* Find a middle lock (if one exists) */
3153 depth = get_lock_depth(other);
3154 do {
3155 if (depth == 0 && (entry != root)) {
3156 pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
3157 break;
3158 }
3159 middle = entry;
3160 entry = get_lock_parent(entry);
3161 depth--;
3162 } while (entry && entry != root && (depth >= 0));
3163 if (forwards)
3164 print_irq_lock_scenario(root, other,
3165 middle ? middle->class : root->class, other->class);
3166 else
3167 print_irq_lock_scenario(other, root,
3168 middle ? middle->class : other->class, root->class);
3169
3170 lockdep_print_held_locks(curr);
3171
3172 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
3173 root->trace = save_trace();
3174 if (!root->trace)
3175 return;
3176 print_shortest_lock_dependencies(other, root);
3177
3178 pr_warn("\nstack backtrace:\n");
3179 dump_stack();
3180}
3181
3182/*
3183 * Prove that in the forwards-direction subgraph starting at <this>
3184 * there is no lock matching <mask>:
3185 */
3186static int
3187check_usage_forwards(struct task_struct *curr, struct held_lock *this,
3188 enum lock_usage_bit bit, const char *irqclass)
3189{
3190 int ret;
3191 struct lock_list root;
3192 struct lock_list *uninitialized_var(target_entry);
3193
3194 root.parent = NULL;
3195 root.class = hlock_class(this);
3196 ret = find_usage_forwards(&root, lock_flag(bit), &target_entry);
3197 if (ret < 0) {
3198 print_bfs_bug(ret);
3199 return 0;
3200 }
3201 if (ret == 1)
3202 return ret;
3203
3204 print_irq_inversion_bug(curr, &root, target_entry,
3205 this, 1, irqclass);
3206 return 0;
3207}
3208
3209/*
3210 * Prove that in the backwards-direction subgraph starting at <this>
3211 * there is no lock matching <mask>:
3212 */
3213static int
3214check_usage_backwards(struct task_struct *curr, struct held_lock *this,
3215 enum lock_usage_bit bit, const char *irqclass)
3216{
3217 int ret;
3218 struct lock_list root;
3219 struct lock_list *uninitialized_var(target_entry);
3220
3221 root.parent = NULL;
3222 root.class = hlock_class(this);
3223 ret = find_usage_backwards(&root, lock_flag(bit), &target_entry);
3224 if (ret < 0) {
3225 print_bfs_bug(ret);
3226 return 0;
3227 }
3228 if (ret == 1)
3229 return ret;
3230
3231 print_irq_inversion_bug(curr, &root, target_entry,
3232 this, 0, irqclass);
3233 return 0;
3234}
3235
3236void print_irqtrace_events(struct task_struct *curr)
3237{
3238 printk("irq event stamp: %u\n", curr->irq_events);
3239 printk("hardirqs last enabled at (%u): [<%px>] %pS\n",
3240 curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
3241 (void *)curr->hardirq_enable_ip);
3242 printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
3243 curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
3244 (void *)curr->hardirq_disable_ip);
3245 printk("softirqs last enabled at (%u): [<%px>] %pS\n",
3246 curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
3247 (void *)curr->softirq_enable_ip);
3248 printk("softirqs last disabled at (%u): [<%px>] %pS\n",
3249 curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
3250 (void *)curr->softirq_disable_ip);
3251}
3252
3253static int HARDIRQ_verbose(struct lock_class *class)
3254{
3255#if HARDIRQ_VERBOSE
3256 return class_filter(class);
3257#endif
3258 return 0;
3259}
3260
3261static int SOFTIRQ_verbose(struct lock_class *class)
3262{
3263#if SOFTIRQ_VERBOSE
3264 return class_filter(class);
3265#endif
3266 return 0;
3267}
3268
3269#define STRICT_READ_CHECKS 1
3270
3271static int (*state_verbose_f[])(struct lock_class *class) = {
3272#define LOCKDEP_STATE(__STATE) \
3273 __STATE##_verbose,
3274#include "lockdep_states.h"
3275#undef LOCKDEP_STATE
3276};
3277
3278static inline int state_verbose(enum lock_usage_bit bit,
3279 struct lock_class *class)
3280{
3281 return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class);
3282}
3283
3284typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
3285 enum lock_usage_bit bit, const char *name);
3286
3287static int
3288mark_lock_irq(struct task_struct *curr, struct held_lock *this,
3289 enum lock_usage_bit new_bit)
3290{
3291 int excl_bit = exclusive_bit(new_bit);
3292 int read = new_bit & LOCK_USAGE_READ_MASK;
3293 int dir = new_bit & LOCK_USAGE_DIR_MASK;
3294
3295 /*
3296 * mark USED_IN has to look forwards -- to ensure no dependency
3297 * has ENABLED state, which would allow recursion deadlocks.
3298 *
3299 * mark ENABLED has to look backwards -- to ensure no dependee
3300 * has USED_IN state, which, again, would allow recursion deadlocks.
3301 */
3302 check_usage_f usage = dir ?
3303 check_usage_backwards : check_usage_forwards;
3304
3305 /*
3306 * Validate that this particular lock does not have conflicting
3307 * usage states.
3308 */
3309 if (!valid_state(curr, this, new_bit, excl_bit))
3310 return 0;
3311
3312 /*
3313 * Validate that the lock dependencies don't have conflicting usage
3314 * states.
3315 */
3316 if ((!read || STRICT_READ_CHECKS) &&
3317 !usage(curr, this, excl_bit, state_name(new_bit & ~LOCK_USAGE_READ_MASK)))
3318 return 0;
3319
3320 /*
3321 * Check for read in write conflicts
3322 */
3323 if (!read) {
3324 if (!valid_state(curr, this, new_bit, excl_bit + LOCK_USAGE_READ_MASK))
3325 return 0;
3326
3327 if (STRICT_READ_CHECKS &&
3328 !usage(curr, this, excl_bit + LOCK_USAGE_READ_MASK,
3329 state_name(new_bit + LOCK_USAGE_READ_MASK)))
3330 return 0;
3331 }
3332
3333 if (state_verbose(new_bit, hlock_class(this)))
3334 return 2;
3335
3336 return 1;
3337}
3338
3339/*
3340 * Mark all held locks with a usage bit:
3341 */
3342static int
3343mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit)
3344{
3345 struct held_lock *hlock;
3346 int i;
3347
3348 for (i = 0; i < curr->lockdep_depth; i++) {
3349 enum lock_usage_bit hlock_bit = base_bit;
3350 hlock = curr->held_locks + i;
3351
3352 if (hlock->read)
3353 hlock_bit += LOCK_USAGE_READ_MASK;
3354
3355 BUG_ON(hlock_bit >= LOCK_USAGE_STATES);
3356
3357 if (!hlock->check)
3358 continue;
3359
3360 if (!mark_lock(curr, hlock, hlock_bit))
3361 return 0;
3362 }
3363
3364 return 1;
3365}
3366
3367/*
3368 * Hardirqs will be enabled:
3369 */
3370static void __trace_hardirqs_on_caller(unsigned long ip)
3371{
3372 struct task_struct *curr = current;
3373
3374 /* we'll do an OFF -> ON transition: */
3375 curr->hardirqs_enabled = 1;
3376
3377 /*
3378 * We are going to turn hardirqs on, so set the
3379 * usage bit for all held locks:
3380 */
3381 if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ))
3382 return;
3383 /*
3384 * If we have softirqs enabled, then set the usage
3385 * bit for all held locks. (disabled hardirqs prevented
3386 * this bit from being set before)
3387 */
3388 if (curr->softirqs_enabled)
3389 if (!mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ))
3390 return;
3391
3392 curr->hardirq_enable_ip = ip;
3393 curr->hardirq_enable_event = ++curr->irq_events;
3394 debug_atomic_inc(hardirqs_on_events);
3395}
3396
3397void lockdep_hardirqs_on(unsigned long ip)
3398{
3399 if (unlikely(!debug_locks || current->lockdep_recursion))
3400 return;
3401
3402 if (unlikely(current->hardirqs_enabled)) {
3403 /*
3404 * Neither irq nor preemption are disabled here
3405 * so this is racy by nature but losing one hit
3406 * in a stat is not a big deal.
3407 */
3408 __debug_atomic_inc(redundant_hardirqs_on);
3409 return;
3410 }
3411
3412 /*
3413 * We're enabling irqs and according to our state above irqs weren't
3414 * already enabled, yet we find the hardware thinks they are in fact
3415 * enabled.. someone messed up their IRQ state tracing.
3416 */
3417 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3418 return;
3419
3420 /*
3421 * See the fine text that goes along with this variable definition.
3422 */
3423 if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled))
3424 return;
3425
3426 /*
3427 * Can't allow enabling interrupts while in an interrupt handler,
3428 * that's general bad form and such. Recursion, limited stack etc..
3429 */
3430 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
3431 return;
3432
3433 current->lockdep_recursion = 1;
3434 __trace_hardirqs_on_caller(ip);
3435 current->lockdep_recursion = 0;
3436}
3437NOKPROBE_SYMBOL(lockdep_hardirqs_on);
3438
3439/*
3440 * Hardirqs were disabled:
3441 */
3442void lockdep_hardirqs_off(unsigned long ip)
3443{
3444 struct task_struct *curr = current;
3445
3446 if (unlikely(!debug_locks || current->lockdep_recursion))
3447 return;
3448
3449 /*
3450 * So we're supposed to get called after you mask local IRQs, but for
3451 * some reason the hardware doesn't quite think you did a proper job.
3452 */
3453 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3454 return;
3455
3456 if (curr->hardirqs_enabled) {
3457 /*
3458 * We have done an ON -> OFF transition:
3459 */
3460 curr->hardirqs_enabled = 0;
3461 curr->hardirq_disable_ip = ip;
3462 curr->hardirq_disable_event = ++curr->irq_events;
3463 debug_atomic_inc(hardirqs_off_events);
3464 } else
3465 debug_atomic_inc(redundant_hardirqs_off);
3466}
3467NOKPROBE_SYMBOL(lockdep_hardirqs_off);
3468
3469/*
3470 * Softirqs will be enabled:
3471 */
3472void trace_softirqs_on(unsigned long ip)
3473{
3474 struct task_struct *curr = current;
3475
3476 if (unlikely(!debug_locks || current->lockdep_recursion))
3477 return;
3478
3479 /*
3480 * We fancy IRQs being disabled here, see softirq.c, avoids
3481 * funny state and nesting things.
3482 */
3483 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3484 return;
3485
3486 if (curr->softirqs_enabled) {
3487 debug_atomic_inc(redundant_softirqs_on);
3488 return;
3489 }
3490
3491 current->lockdep_recursion = 1;
3492 /*
3493 * We'll do an OFF -> ON transition:
3494 */
3495 curr->softirqs_enabled = 1;
3496 curr->softirq_enable_ip = ip;
3497 curr->softirq_enable_event = ++curr->irq_events;
3498 debug_atomic_inc(softirqs_on_events);
3499 /*
3500 * We are going to turn softirqs on, so set the
3501 * usage bit for all held locks, if hardirqs are
3502 * enabled too:
3503 */
3504 if (curr->hardirqs_enabled)
3505 mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
3506 current->lockdep_recursion = 0;
3507}
3508
3509/*
3510 * Softirqs were disabled:
3511 */
3512void trace_softirqs_off(unsigned long ip)
3513{
3514 struct task_struct *curr = current;
3515
3516 if (unlikely(!debug_locks || current->lockdep_recursion))
3517 return;
3518
3519 /*
3520 * We fancy IRQs being disabled here, see softirq.c
3521 */
3522 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3523 return;
3524
3525 if (curr->softirqs_enabled) {
3526 /*
3527 * We have done an ON -> OFF transition:
3528 */
3529 curr->softirqs_enabled = 0;
3530 curr->softirq_disable_ip = ip;
3531 curr->softirq_disable_event = ++curr->irq_events;
3532 debug_atomic_inc(softirqs_off_events);
3533 /*
3534 * Whoops, we wanted softirqs off, so why aren't they?
3535 */
3536 DEBUG_LOCKS_WARN_ON(!softirq_count());
3537 } else
3538 debug_atomic_inc(redundant_softirqs_off);
3539}
3540
3541static int
3542mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
3543{
3544 if (!check)
3545 goto lock_used;
3546
3547 /*
3548 * If non-trylock use in a hardirq or softirq context, then
3549 * mark the lock as used in these contexts:
3550 */
3551 if (!hlock->trylock) {
3552 if (hlock->read) {
3553 if (curr->hardirq_context)
3554 if (!mark_lock(curr, hlock,
3555 LOCK_USED_IN_HARDIRQ_READ))
3556 return 0;
3557 if (curr->softirq_context)
3558 if (!mark_lock(curr, hlock,
3559 LOCK_USED_IN_SOFTIRQ_READ))
3560 return 0;
3561 } else {
3562 if (curr->hardirq_context)
3563 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
3564 return 0;
3565 if (curr->softirq_context)
3566 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
3567 return 0;
3568 }
3569 }
3570 if (!hlock->hardirqs_off) {
3571 if (hlock->read) {
3572 if (!mark_lock(curr, hlock,
3573 LOCK_ENABLED_HARDIRQ_READ))
3574 return 0;
3575 if (curr->softirqs_enabled)
3576 if (!mark_lock(curr, hlock,
3577 LOCK_ENABLED_SOFTIRQ_READ))
3578 return 0;
3579 } else {
3580 if (!mark_lock(curr, hlock,
3581 LOCK_ENABLED_HARDIRQ))
3582 return 0;
3583 if (curr->softirqs_enabled)
3584 if (!mark_lock(curr, hlock,
3585 LOCK_ENABLED_SOFTIRQ))
3586 return 0;
3587 }
3588 }
3589
3590lock_used:
3591 /* mark it as used: */
3592 if (!mark_lock(curr, hlock, LOCK_USED))
3593 return 0;
3594
3595 return 1;
3596}
3597
3598static inline unsigned int task_irq_context(struct task_struct *task)
3599{
3600 return 2 * !!task->hardirq_context + !!task->softirq_context;
3601}
3602
3603static int separate_irq_context(struct task_struct *curr,
3604 struct held_lock *hlock)
3605{
3606 unsigned int depth = curr->lockdep_depth;
3607
3608 /*
3609 * Keep track of points where we cross into an interrupt context:
3610 */
3611 if (depth) {
3612 struct held_lock *prev_hlock;
3613
3614 prev_hlock = curr->held_locks + depth-1;
3615 /*
3616 * If we cross into another context, reset the
3617 * hash key (this also prevents the checking and the
3618 * adding of the dependency to 'prev'):
3619 */
3620 if (prev_hlock->irq_context != hlock->irq_context)
3621 return 1;
3622 }
3623 return 0;
3624}
3625
3626/*
3627 * Mark a lock with a usage bit, and validate the state transition:
3628 */
3629static int mark_lock(struct task_struct *curr, struct held_lock *this,
3630 enum lock_usage_bit new_bit)
3631{
3632 unsigned int new_mask = 1 << new_bit, ret = 1;
3633
3634 if (new_bit >= LOCK_USAGE_STATES) {
3635 DEBUG_LOCKS_WARN_ON(1);
3636 return 0;
3637 }
3638
3639 /*
3640 * If already set then do not dirty the cacheline,
3641 * nor do any checks:
3642 */
3643 if (likely(hlock_class(this)->usage_mask & new_mask))
3644 return 1;
3645
3646 if (!graph_lock())
3647 return 0;
3648 /*
3649 * Make sure we didn't race:
3650 */
3651 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3652 graph_unlock();
3653 return 1;
3654 }
3655
3656 hlock_class(this)->usage_mask |= new_mask;
3657
3658 if (!(hlock_class(this)->usage_traces[new_bit] = save_trace()))
3659 return 0;
3660
3661 switch (new_bit) {
3662 case LOCK_USED:
3663 debug_atomic_dec(nr_unused_locks);
3664 break;
3665 default:
3666 ret = mark_lock_irq(curr, this, new_bit);
3667 if (!ret)
3668 return 0;
3669 }
3670
3671 graph_unlock();
3672
3673 /*
3674 * We must printk outside of the graph_lock:
3675 */
3676 if (ret == 2) {
3677 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3678 print_lock(this);
3679 print_irqtrace_events(curr);
3680 dump_stack();
3681 }
3682
3683 return ret;
3684}
3685
3686#else /* CONFIG_PROVE_LOCKING */
3687
3688static inline int
3689mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
3690{
3691 return 1;
3692}
3693
3694static inline unsigned int task_irq_context(struct task_struct *task)
3695{
3696 return 0;
3697}
3698
3699static inline int separate_irq_context(struct task_struct *curr,
3700 struct held_lock *hlock)
3701{
3702 return 0;
3703}
3704
3705#endif /* CONFIG_PROVE_LOCKING */
3706
3707/*
3708 * Initialize a lock instance's lock-class mapping info:
3709 */
3710void lockdep_init_map(struct lockdep_map *lock, const char *name,
3711 struct lock_class_key *key, int subclass)
3712{
3713 int i;
3714
3715 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3716 lock->class_cache[i] = NULL;
3717
3718#ifdef CONFIG_LOCK_STAT
3719 lock->cpu = raw_smp_processor_id();
3720#endif
3721
3722 /*
3723 * Can't be having no nameless bastards around this place!
3724 */
3725 if (DEBUG_LOCKS_WARN_ON(!name)) {
3726 lock->name = "NULL";
3727 return;
3728 }
3729
3730 lock->name = name;
3731
3732 /*
3733 * No key, no joy, we need to hash something.
3734 */
3735 if (DEBUG_LOCKS_WARN_ON(!key))
3736 return;
3737 /*
3738 * Sanity check, the lock-class key must either have been allocated
3739 * statically or must have been registered as a dynamic key.
3740 */
3741 if (!static_obj(key) && !is_dynamic_key(key)) {
3742 if (debug_locks)
3743 printk(KERN_ERR "BUG: key %px has not been registered!\n", key);
3744 DEBUG_LOCKS_WARN_ON(1);
3745 return;
3746 }
3747 lock->key = key;
3748
3749 if (unlikely(!debug_locks))
3750 return;
3751
3752 if (subclass) {
3753 unsigned long flags;
3754
3755 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3756 return;
3757
3758 raw_local_irq_save(flags);
3759 current->lockdep_recursion = 1;
3760 register_lock_class(lock, subclass, 1);
3761 current->lockdep_recursion = 0;
3762 raw_local_irq_restore(flags);
3763 }
3764}
3765EXPORT_SYMBOL_GPL(lockdep_init_map);
3766
3767struct lock_class_key __lockdep_no_validate__;
3768EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3769
3770static void
3771print_lock_nested_lock_not_held(struct task_struct *curr,
3772 struct held_lock *hlock,
3773 unsigned long ip)
3774{
3775 if (!debug_locks_off())
3776 return;
3777 if (debug_locks_silent)
3778 return;
3779
3780 pr_warn("\n");
3781 pr_warn("==================================\n");
3782 pr_warn("WARNING: Nested lock was not taken\n");
3783 print_kernel_ident();
3784 pr_warn("----------------------------------\n");
3785
3786 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3787 print_lock(hlock);
3788
3789 pr_warn("\nbut this task is not holding:\n");
3790 pr_warn("%s\n", hlock->nest_lock->name);
3791
3792 pr_warn("\nstack backtrace:\n");
3793 dump_stack();
3794
3795 pr_warn("\nother info that might help us debug this:\n");
3796 lockdep_print_held_locks(curr);
3797
3798 pr_warn("\nstack backtrace:\n");
3799 dump_stack();
3800}
3801
3802static int __lock_is_held(const struct lockdep_map *lock, int read);
3803
3804/*
3805 * This gets called for every mutex_lock*()/spin_lock*() operation.
3806 * We maintain the dependency maps and validate the locking attempt:
3807 *
3808 * The callers must make sure that IRQs are disabled before calling it,
3809 * otherwise we could get an interrupt which would want to take locks,
3810 * which would end up in lockdep again.
3811 */
3812static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3813 int trylock, int read, int check, int hardirqs_off,
3814 struct lockdep_map *nest_lock, unsigned long ip,
3815 int references, int pin_count)
3816{
3817 struct task_struct *curr = current;
3818 struct lock_class *class = NULL;
3819 struct held_lock *hlock;
3820 unsigned int depth;
3821 int chain_head = 0;
3822 int class_idx;
3823 u64 chain_key;
3824
3825 if (unlikely(!debug_locks))
3826 return 0;
3827
3828 if (!prove_locking || lock->key == &__lockdep_no_validate__)
3829 check = 0;
3830
3831 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3832 class = lock->class_cache[subclass];
3833 /*
3834 * Not cached?
3835 */
3836 if (unlikely(!class)) {
3837 class = register_lock_class(lock, subclass, 0);
3838 if (!class)
3839 return 0;
3840 }
3841
3842 debug_class_ops_inc(class);
3843
3844 if (very_verbose(class)) {
3845 printk("\nacquire class [%px] %s", class->key, class->name);
3846 if (class->name_version > 1)
3847 printk(KERN_CONT "#%d", class->name_version);
3848 printk(KERN_CONT "\n");
3849 dump_stack();
3850 }
3851
3852 /*
3853 * Add the lock to the list of currently held locks.
3854 * (we dont increase the depth just yet, up until the
3855 * dependency checks are done)
3856 */
3857 depth = curr->lockdep_depth;
3858 /*
3859 * Ran out of static storage for our per-task lock stack again have we?
3860 */
3861 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3862 return 0;
3863
3864 class_idx = class - lock_classes;
3865
3866 if (depth) {
3867 hlock = curr->held_locks + depth - 1;
3868 if (hlock->class_idx == class_idx && nest_lock) {
3869 if (!references)
3870 references++;
3871
3872 if (!hlock->references)
3873 hlock->references++;
3874
3875 hlock->references += references;
3876
3877 /* Overflow */
3878 if (DEBUG_LOCKS_WARN_ON(hlock->references < references))
3879 return 0;
3880
3881 return 2;
3882 }
3883 }
3884
3885 hlock = curr->held_locks + depth;
3886 /*
3887 * Plain impossible, we just registered it and checked it weren't no
3888 * NULL like.. I bet this mushroom I ate was good!
3889 */
3890 if (DEBUG_LOCKS_WARN_ON(!class))
3891 return 0;
3892 hlock->class_idx = class_idx;
3893 hlock->acquire_ip = ip;
3894 hlock->instance = lock;
3895 hlock->nest_lock = nest_lock;
3896 hlock->irq_context = task_irq_context(curr);
3897 hlock->trylock = trylock;
3898 hlock->read = read;
3899 hlock->check = check;
3900 hlock->hardirqs_off = !!hardirqs_off;
3901 hlock->references = references;
3902#ifdef CONFIG_LOCK_STAT
3903 hlock->waittime_stamp = 0;
3904 hlock->holdtime_stamp = lockstat_clock();
3905#endif
3906 hlock->pin_count = pin_count;
3907
3908 /* Initialize the lock usage bit */
3909 if (!mark_usage(curr, hlock, check))
3910 return 0;
3911
3912 /*
3913 * Calculate the chain hash: it's the combined hash of all the
3914 * lock keys along the dependency chain. We save the hash value
3915 * at every step so that we can get the current hash easily
3916 * after unlock. The chain hash is then used to cache dependency
3917 * results.
3918 *
3919 * The 'key ID' is what is the most compact key value to drive
3920 * the hash, not class->key.
3921 */
3922 /*
3923 * Whoops, we did it again.. class_idx is invalid.
3924 */
3925 if (DEBUG_LOCKS_WARN_ON(!test_bit(class_idx, lock_classes_in_use)))
3926 return 0;
3927
3928 chain_key = curr->curr_chain_key;
3929 if (!depth) {
3930 /*
3931 * How can we have a chain hash when we ain't got no keys?!
3932 */
3933 if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY))
3934 return 0;
3935 chain_head = 1;
3936 }
3937
3938 hlock->prev_chain_key = chain_key;
3939 if (separate_irq_context(curr, hlock)) {
3940 chain_key = INITIAL_CHAIN_KEY;
3941 chain_head = 1;
3942 }
3943 chain_key = iterate_chain_key(chain_key, class_idx);
3944
3945 if (nest_lock && !__lock_is_held(nest_lock, -1)) {
3946 print_lock_nested_lock_not_held(curr, hlock, ip);
3947 return 0;
3948 }
3949
3950 if (!debug_locks_silent) {
3951 WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key);
3952 WARN_ON_ONCE(!hlock_class(hlock)->key);
3953 }
3954
3955 if (!validate_chain(curr, hlock, chain_head, chain_key))
3956 return 0;
3957
3958 curr->curr_chain_key = chain_key;
3959 curr->lockdep_depth++;
3960 check_chain_key(curr);
3961#ifdef CONFIG_DEBUG_LOCKDEP
3962 if (unlikely(!debug_locks))
3963 return 0;
3964#endif
3965 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3966 debug_locks_off();
3967 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3968 printk(KERN_DEBUG "depth: %i max: %lu!\n",
3969 curr->lockdep_depth, MAX_LOCK_DEPTH);
3970
3971 lockdep_print_held_locks(current);
3972 debug_show_all_locks();
3973 dump_stack();
3974
3975 return 0;
3976 }
3977
3978 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3979 max_lockdep_depth = curr->lockdep_depth;
3980
3981 return 1;
3982}
3983
3984static void print_unlock_imbalance_bug(struct task_struct *curr,
3985 struct lockdep_map *lock,
3986 unsigned long ip)
3987{
3988 if (!debug_locks_off())
3989 return;
3990 if (debug_locks_silent)
3991 return;
3992
3993 pr_warn("\n");
3994 pr_warn("=====================================\n");
3995 pr_warn("WARNING: bad unlock balance detected!\n");
3996 print_kernel_ident();
3997 pr_warn("-------------------------------------\n");
3998 pr_warn("%s/%d is trying to release lock (",
3999 curr->comm, task_pid_nr(curr));
4000 print_lockdep_cache(lock);
4001 pr_cont(") at:\n");
4002 print_ip_sym(ip);
4003 pr_warn("but there are no more locks to release!\n");
4004 pr_warn("\nother info that might help us debug this:\n");
4005 lockdep_print_held_locks(curr);
4006
4007 pr_warn("\nstack backtrace:\n");
4008 dump_stack();
4009}
4010
4011static int match_held_lock(const struct held_lock *hlock,
4012 const struct lockdep_map *lock)
4013{
4014 if (hlock->instance == lock)
4015 return 1;
4016
4017 if (hlock->references) {
4018 const struct lock_class *class = lock->class_cache[0];
4019
4020 if (!class)
4021 class = look_up_lock_class(lock, 0);
4022
4023 /*
4024 * If look_up_lock_class() failed to find a class, we're trying
4025 * to test if we hold a lock that has never yet been acquired.
4026 * Clearly if the lock hasn't been acquired _ever_, we're not
4027 * holding it either, so report failure.
4028 */
4029 if (!class)
4030 return 0;
4031
4032 /*
4033 * References, but not a lock we're actually ref-counting?
4034 * State got messed up, follow the sites that change ->references
4035 * and try to make sense of it.
4036 */
4037 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
4038 return 0;
4039
4040 if (hlock->class_idx == class - lock_classes)
4041 return 1;
4042 }
4043
4044 return 0;
4045}
4046
4047/* @depth must not be zero */
4048static struct held_lock *find_held_lock(struct task_struct *curr,
4049 struct lockdep_map *lock,
4050 unsigned int depth, int *idx)
4051{
4052 struct held_lock *ret, *hlock, *prev_hlock;
4053 int i;
4054
4055 i = depth - 1;
4056 hlock = curr->held_locks + i;
4057 ret = hlock;
4058 if (match_held_lock(hlock, lock))
4059 goto out;
4060
4061 ret = NULL;
4062 for (i--, prev_hlock = hlock--;
4063 i >= 0;
4064 i--, prev_hlock = hlock--) {
4065 /*
4066 * We must not cross into another context:
4067 */
4068 if (prev_hlock->irq_context != hlock->irq_context) {
4069 ret = NULL;
4070 break;
4071 }
4072 if (match_held_lock(hlock, lock)) {
4073 ret = hlock;
4074 break;
4075 }
4076 }
4077
4078out:
4079 *idx = i;
4080 return ret;
4081}
4082
4083static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
4084 int idx, unsigned int *merged)
4085{
4086 struct held_lock *hlock;
4087 int first_idx = idx;
4088
4089 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4090 return 0;
4091
4092 for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
4093 switch (__lock_acquire(hlock->instance,
4094 hlock_class(hlock)->subclass,
4095 hlock->trylock,
4096 hlock->read, hlock->check,
4097 hlock->hardirqs_off,
4098 hlock->nest_lock, hlock->acquire_ip,
4099 hlock->references, hlock->pin_count)) {
4100 case 0:
4101 return 1;
4102 case 1:
4103 break;
4104 case 2:
4105 *merged += (idx == first_idx);
4106 break;
4107 default:
4108 WARN_ON(1);
4109 return 0;
4110 }
4111 }
4112 return 0;
4113}
4114
4115static int
4116__lock_set_class(struct lockdep_map *lock, const char *name,
4117 struct lock_class_key *key, unsigned int subclass,
4118 unsigned long ip)
4119{
4120 struct task_struct *curr = current;
4121 unsigned int depth, merged = 0;
4122 struct held_lock *hlock;
4123 struct lock_class *class;
4124 int i;
4125
4126 if (unlikely(!debug_locks))
4127 return 0;
4128
4129 depth = curr->lockdep_depth;
4130 /*
4131 * This function is about (re)setting the class of a held lock,
4132 * yet we're not actually holding any locks. Naughty user!
4133 */
4134 if (DEBUG_LOCKS_WARN_ON(!depth))
4135 return 0;
4136
4137 hlock = find_held_lock(curr, lock, depth, &i);
4138 if (!hlock) {
4139 print_unlock_imbalance_bug(curr, lock, ip);
4140 return 0;
4141 }
4142
4143 lockdep_init_map(lock, name, key, 0);
4144 class = register_lock_class(lock, subclass, 0);
4145 hlock->class_idx = class - lock_classes;
4146
4147 curr->lockdep_depth = i;
4148 curr->curr_chain_key = hlock->prev_chain_key;
4149
4150 if (reacquire_held_locks(curr, depth, i, &merged))
4151 return 0;
4152
4153 /*
4154 * I took it apart and put it back together again, except now I have
4155 * these 'spare' parts.. where shall I put them.
4156 */
4157 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged))
4158 return 0;
4159 return 1;
4160}
4161
4162static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
4163{
4164 struct task_struct *curr = current;
4165 unsigned int depth, merged = 0;
4166 struct held_lock *hlock;
4167 int i;
4168
4169 if (unlikely(!debug_locks))
4170 return 0;
4171
4172 depth = curr->lockdep_depth;
4173 /*
4174 * This function is about (re)setting the class of a held lock,
4175 * yet we're not actually holding any locks. Naughty user!
4176 */
4177 if (DEBUG_LOCKS_WARN_ON(!depth))
4178 return 0;
4179
4180 hlock = find_held_lock(curr, lock, depth, &i);
4181 if (!hlock) {
4182 print_unlock_imbalance_bug(curr, lock, ip);
4183 return 0;
4184 }
4185
4186 curr->lockdep_depth = i;
4187 curr->curr_chain_key = hlock->prev_chain_key;
4188
4189 WARN(hlock->read, "downgrading a read lock");
4190 hlock->read = 1;
4191 hlock->acquire_ip = ip;
4192
4193 if (reacquire_held_locks(curr, depth, i, &merged))
4194 return 0;
4195
4196 /* Merging can't happen with unchanged classes.. */
4197 if (DEBUG_LOCKS_WARN_ON(merged))
4198 return 0;
4199
4200 /*
4201 * I took it apart and put it back together again, except now I have
4202 * these 'spare' parts.. where shall I put them.
4203 */
4204 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
4205 return 0;
4206
4207 return 1;
4208}
4209
4210/*
4211 * Remove the lock to the list of currently held locks - this gets
4212 * called on mutex_unlock()/spin_unlock*() (or on a failed
4213 * mutex_lock_interruptible()).
4214 *
4215 * @nested is an hysterical artifact, needs a tree wide cleanup.
4216 */
4217static int
4218__lock_release(struct lockdep_map *lock, unsigned long ip)
4219{
4220 struct task_struct *curr = current;
4221 unsigned int depth, merged = 1;
4222 struct held_lock *hlock;
4223 int i;
4224
4225 if (unlikely(!debug_locks))
4226 return 0;
4227
4228 depth = curr->lockdep_depth;
4229 /*
4230 * So we're all set to release this lock.. wait what lock? We don't
4231 * own any locks, you've been drinking again?
4232 */
4233 if (depth <= 0) {
4234 print_unlock_imbalance_bug(curr, lock, ip);
4235 return 0;
4236 }
4237
4238 /*
4239 * Check whether the lock exists in the current stack
4240 * of held locks:
4241 */
4242 hlock = find_held_lock(curr, lock, depth, &i);
4243 if (!hlock) {
4244 print_unlock_imbalance_bug(curr, lock, ip);
4245 return 0;
4246 }
4247
4248 if (hlock->instance == lock)
4249 lock_release_holdtime(hlock);
4250
4251 WARN(hlock->pin_count, "releasing a pinned lock\n");
4252
4253 if (hlock->references) {
4254 hlock->references--;
4255 if (hlock->references) {
4256 /*
4257 * We had, and after removing one, still have
4258 * references, the current lock stack is still
4259 * valid. We're done!
4260 */
4261 return 1;
4262 }
4263 }
4264
4265 /*
4266 * We have the right lock to unlock, 'hlock' points to it.
4267 * Now we remove it from the stack, and add back the other
4268 * entries (if any), recalculating the hash along the way:
4269 */
4270
4271 curr->lockdep_depth = i;
4272 curr->curr_chain_key = hlock->prev_chain_key;
4273
4274 /*
4275 * The most likely case is when the unlock is on the innermost
4276 * lock. In this case, we are done!
4277 */
4278 if (i == depth-1)
4279 return 1;
4280
4281 if (reacquire_held_locks(curr, depth, i + 1, &merged))
4282 return 0;
4283
4284 /*
4285 * We had N bottles of beer on the wall, we drank one, but now
4286 * there's not N-1 bottles of beer left on the wall...
4287 * Pouring two of the bottles together is acceptable.
4288 */
4289 DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged);
4290
4291 /*
4292 * Since reacquire_held_locks() would have called check_chain_key()
4293 * indirectly via __lock_acquire(), we don't need to do it again
4294 * on return.
4295 */
4296 return 0;
4297}
4298
4299static nokprobe_inline
4300int __lock_is_held(const struct lockdep_map *lock, int read)
4301{
4302 struct task_struct *curr = current;
4303 int i;
4304
4305 for (i = 0; i < curr->lockdep_depth; i++) {
4306 struct held_lock *hlock = curr->held_locks + i;
4307
4308 if (match_held_lock(hlock, lock)) {
4309 if (read == -1 || hlock->read == read)
4310 return 1;
4311
4312 return 0;
4313 }
4314 }
4315
4316 return 0;
4317}
4318
4319static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
4320{
4321 struct pin_cookie cookie = NIL_COOKIE;
4322 struct task_struct *curr = current;
4323 int i;
4324
4325 if (unlikely(!debug_locks))
4326 return cookie;
4327
4328 for (i = 0; i < curr->lockdep_depth; i++) {
4329 struct held_lock *hlock = curr->held_locks + i;
4330
4331 if (match_held_lock(hlock, lock)) {
4332 /*
4333 * Grab 16bits of randomness; this is sufficient to not
4334 * be guessable and still allows some pin nesting in
4335 * our u32 pin_count.
4336 */
4337 cookie.val = 1 + (prandom_u32() >> 16);
4338 hlock->pin_count += cookie.val;
4339 return cookie;
4340 }
4341 }
4342
4343 WARN(1, "pinning an unheld lock\n");
4344 return cookie;
4345}
4346
4347static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4348{
4349 struct task_struct *curr = current;
4350 int i;
4351
4352 if (unlikely(!debug_locks))
4353 return;
4354
4355 for (i = 0; i < curr->lockdep_depth; i++) {
4356 struct held_lock *hlock = curr->held_locks + i;
4357
4358 if (match_held_lock(hlock, lock)) {
4359 hlock->pin_count += cookie.val;
4360 return;
4361 }
4362 }
4363
4364 WARN(1, "pinning an unheld lock\n");
4365}
4366
4367static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4368{
4369 struct task_struct *curr = current;
4370 int i;
4371
4372 if (unlikely(!debug_locks))
4373 return;
4374
4375 for (i = 0; i < curr->lockdep_depth; i++) {
4376 struct held_lock *hlock = curr->held_locks + i;
4377
4378 if (match_held_lock(hlock, lock)) {
4379 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
4380 return;
4381
4382 hlock->pin_count -= cookie.val;
4383
4384 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
4385 hlock->pin_count = 0;
4386
4387 return;
4388 }
4389 }
4390
4391 WARN(1, "unpinning an unheld lock\n");
4392}
4393
4394/*
4395 * Check whether we follow the irq-flags state precisely:
4396 */
4397static void check_flags(unsigned long flags)
4398{
4399#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP)
4400 if (!debug_locks)
4401 return;
4402
4403 if (irqs_disabled_flags(flags)) {
4404 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
4405 printk("possible reason: unannotated irqs-off.\n");
4406 }
4407 } else {
4408 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
4409 printk("possible reason: unannotated irqs-on.\n");
4410 }
4411 }
4412
4413 /*
4414 * We dont accurately track softirq state in e.g.
4415 * hardirq contexts (such as on 4KSTACKS), so only
4416 * check if not in hardirq contexts:
4417 */
4418 if (!hardirq_count()) {
4419 if (softirq_count()) {
4420 /* like the above, but with softirqs */
4421 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
4422 } else {
4423 /* lick the above, does it taste good? */
4424 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
4425 }
4426 }
4427
4428 if (!debug_locks)
4429 print_irqtrace_events(current);
4430#endif
4431}
4432
4433void lock_set_class(struct lockdep_map *lock, const char *name,
4434 struct lock_class_key *key, unsigned int subclass,
4435 unsigned long ip)
4436{
4437 unsigned long flags;
4438
4439 if (unlikely(current->lockdep_recursion))
4440 return;
4441
4442 raw_local_irq_save(flags);
4443 current->lockdep_recursion = 1;
4444 check_flags(flags);
4445 if (__lock_set_class(lock, name, key, subclass, ip))
4446 check_chain_key(current);
4447 current->lockdep_recursion = 0;
4448 raw_local_irq_restore(flags);
4449}
4450EXPORT_SYMBOL_GPL(lock_set_class);
4451
4452void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
4453{
4454 unsigned long flags;
4455
4456 if (unlikely(current->lockdep_recursion))
4457 return;
4458
4459 raw_local_irq_save(flags);
4460 current->lockdep_recursion = 1;
4461 check_flags(flags);
4462 if (__lock_downgrade(lock, ip))
4463 check_chain_key(current);
4464 current->lockdep_recursion = 0;
4465 raw_local_irq_restore(flags);
4466}
4467EXPORT_SYMBOL_GPL(lock_downgrade);
4468
4469/*
4470 * We are not always called with irqs disabled - do that here,
4471 * and also avoid lockdep recursion:
4472 */
4473void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
4474 int trylock, int read, int check,
4475 struct lockdep_map *nest_lock, unsigned long ip)
4476{
4477 unsigned long flags;
4478
4479 if (unlikely(current->lockdep_recursion))
4480 return;
4481
4482 raw_local_irq_save(flags);
4483 check_flags(flags);
4484
4485 current->lockdep_recursion = 1;
4486 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
4487 __lock_acquire(lock, subclass, trylock, read, check,
4488 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
4489 current->lockdep_recursion = 0;
4490 raw_local_irq_restore(flags);
4491}
4492EXPORT_SYMBOL_GPL(lock_acquire);
4493
4494void lock_release(struct lockdep_map *lock, int nested,
4495 unsigned long ip)
4496{
4497 unsigned long flags;
4498
4499 if (unlikely(current->lockdep_recursion))
4500 return;
4501
4502 raw_local_irq_save(flags);
4503 check_flags(flags);
4504 current->lockdep_recursion = 1;
4505 trace_lock_release(lock, ip);
4506 if (__lock_release(lock, ip))
4507 check_chain_key(current);
4508 current->lockdep_recursion = 0;
4509 raw_local_irq_restore(flags);
4510}
4511EXPORT_SYMBOL_GPL(lock_release);
4512
4513int lock_is_held_type(const struct lockdep_map *lock, int read)
4514{
4515 unsigned long flags;
4516 int ret = 0;
4517
4518 if (unlikely(current->lockdep_recursion))
4519 return 1; /* avoid false negative lockdep_assert_held() */
4520
4521 raw_local_irq_save(flags);
4522 check_flags(flags);
4523
4524 current->lockdep_recursion = 1;
4525 ret = __lock_is_held(lock, read);
4526 current->lockdep_recursion = 0;
4527 raw_local_irq_restore(flags);
4528
4529 return ret;
4530}
4531EXPORT_SYMBOL_GPL(lock_is_held_type);
4532NOKPROBE_SYMBOL(lock_is_held_type);
4533
4534struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
4535{
4536 struct pin_cookie cookie = NIL_COOKIE;
4537 unsigned long flags;
4538
4539 if (unlikely(current->lockdep_recursion))
4540 return cookie;
4541
4542 raw_local_irq_save(flags);
4543 check_flags(flags);
4544
4545 current->lockdep_recursion = 1;
4546 cookie = __lock_pin_lock(lock);
4547 current->lockdep_recursion = 0;
4548 raw_local_irq_restore(flags);
4549
4550 return cookie;
4551}
4552EXPORT_SYMBOL_GPL(lock_pin_lock);
4553
4554void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4555{
4556 unsigned long flags;
4557
4558 if (unlikely(current->lockdep_recursion))
4559 return;
4560
4561 raw_local_irq_save(flags);
4562 check_flags(flags);
4563
4564 current->lockdep_recursion = 1;
4565 __lock_repin_lock(lock, cookie);
4566 current->lockdep_recursion = 0;
4567 raw_local_irq_restore(flags);
4568}
4569EXPORT_SYMBOL_GPL(lock_repin_lock);
4570
4571void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4572{
4573 unsigned long flags;
4574
4575 if (unlikely(current->lockdep_recursion))
4576 return;
4577
4578 raw_local_irq_save(flags);
4579 check_flags(flags);
4580
4581 current->lockdep_recursion = 1;
4582 __lock_unpin_lock(lock, cookie);
4583 current->lockdep_recursion = 0;
4584 raw_local_irq_restore(flags);
4585}
4586EXPORT_SYMBOL_GPL(lock_unpin_lock);
4587
4588#ifdef CONFIG_LOCK_STAT
4589static void print_lock_contention_bug(struct task_struct *curr,
4590 struct lockdep_map *lock,
4591 unsigned long ip)
4592{
4593 if (!debug_locks_off())
4594 return;
4595 if (debug_locks_silent)
4596 return;
4597
4598 pr_warn("\n");
4599 pr_warn("=================================\n");
4600 pr_warn("WARNING: bad contention detected!\n");
4601 print_kernel_ident();
4602 pr_warn("---------------------------------\n");
4603 pr_warn("%s/%d is trying to contend lock (",
4604 curr->comm, task_pid_nr(curr));
4605 print_lockdep_cache(lock);
4606 pr_cont(") at:\n");
4607 print_ip_sym(ip);
4608 pr_warn("but there are no locks held!\n");
4609 pr_warn("\nother info that might help us debug this:\n");
4610 lockdep_print_held_locks(curr);
4611
4612 pr_warn("\nstack backtrace:\n");
4613 dump_stack();
4614}
4615
4616static void
4617__lock_contended(struct lockdep_map *lock, unsigned long ip)
4618{
4619 struct task_struct *curr = current;
4620 struct held_lock *hlock;
4621 struct lock_class_stats *stats;
4622 unsigned int depth;
4623 int i, contention_point, contending_point;
4624
4625 depth = curr->lockdep_depth;
4626 /*
4627 * Whee, we contended on this lock, except it seems we're not
4628 * actually trying to acquire anything much at all..
4629 */
4630 if (DEBUG_LOCKS_WARN_ON(!depth))
4631 return;
4632
4633 hlock = find_held_lock(curr, lock, depth, &i);
4634 if (!hlock) {
4635 print_lock_contention_bug(curr, lock, ip);
4636 return;
4637 }
4638
4639 if (hlock->instance != lock)
4640 return;
4641
4642 hlock->waittime_stamp = lockstat_clock();
4643
4644 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
4645 contending_point = lock_point(hlock_class(hlock)->contending_point,
4646 lock->ip);
4647
4648 stats = get_lock_stats(hlock_class(hlock));
4649 if (contention_point < LOCKSTAT_POINTS)
4650 stats->contention_point[contention_point]++;
4651 if (contending_point < LOCKSTAT_POINTS)
4652 stats->contending_point[contending_point]++;
4653 if (lock->cpu != smp_processor_id())
4654 stats->bounces[bounce_contended + !!hlock->read]++;
4655}
4656
4657static void
4658__lock_acquired(struct lockdep_map *lock, unsigned long ip)
4659{
4660 struct task_struct *curr = current;
4661 struct held_lock *hlock;
4662 struct lock_class_stats *stats;
4663 unsigned int depth;
4664 u64 now, waittime = 0;
4665 int i, cpu;
4666
4667 depth = curr->lockdep_depth;
4668 /*
4669 * Yay, we acquired ownership of this lock we didn't try to
4670 * acquire, how the heck did that happen?
4671 */
4672 if (DEBUG_LOCKS_WARN_ON(!depth))
4673 return;
4674
4675 hlock = find_held_lock(curr, lock, depth, &i);
4676 if (!hlock) {
4677 print_lock_contention_bug(curr, lock, _RET_IP_);
4678 return;
4679 }
4680
4681 if (hlock->instance != lock)
4682 return;
4683
4684 cpu = smp_processor_id();
4685 if (hlock->waittime_stamp) {
4686 now = lockstat_clock();
4687 waittime = now - hlock->waittime_stamp;
4688 hlock->holdtime_stamp = now;
4689 }
4690
4691 trace_lock_acquired(lock, ip);
4692
4693 stats = get_lock_stats(hlock_class(hlock));
4694 if (waittime) {
4695 if (hlock->read)
4696 lock_time_inc(&stats->read_waittime, waittime);
4697 else
4698 lock_time_inc(&stats->write_waittime, waittime);
4699 }
4700 if (lock->cpu != cpu)
4701 stats->bounces[bounce_acquired + !!hlock->read]++;
4702
4703 lock->cpu = cpu;
4704 lock->ip = ip;
4705}
4706
4707void lock_contended(struct lockdep_map *lock, unsigned long ip)
4708{
4709 unsigned long flags;
4710
4711 if (unlikely(!lock_stat || !debug_locks))
4712 return;
4713
4714 if (unlikely(current->lockdep_recursion))
4715 return;
4716
4717 raw_local_irq_save(flags);
4718 check_flags(flags);
4719 current->lockdep_recursion = 1;
4720 trace_lock_contended(lock, ip);
4721 __lock_contended(lock, ip);
4722 current->lockdep_recursion = 0;
4723 raw_local_irq_restore(flags);
4724}
4725EXPORT_SYMBOL_GPL(lock_contended);
4726
4727void lock_acquired(struct lockdep_map *lock, unsigned long ip)
4728{
4729 unsigned long flags;
4730
4731 if (unlikely(!lock_stat || !debug_locks))
4732 return;
4733
4734 if (unlikely(current->lockdep_recursion))
4735 return;
4736
4737 raw_local_irq_save(flags);
4738 check_flags(flags);
4739 current->lockdep_recursion = 1;
4740 __lock_acquired(lock, ip);
4741 current->lockdep_recursion = 0;
4742 raw_local_irq_restore(flags);
4743}
4744EXPORT_SYMBOL_GPL(lock_acquired);
4745#endif
4746
4747/*
4748 * Used by the testsuite, sanitize the validator state
4749 * after a simulated failure:
4750 */
4751
4752void lockdep_reset(void)
4753{
4754 unsigned long flags;
4755 int i;
4756
4757 raw_local_irq_save(flags);
4758 lockdep_init_task(current);
4759 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
4760 nr_hardirq_chains = 0;
4761 nr_softirq_chains = 0;
4762 nr_process_chains = 0;
4763 debug_locks = 1;
4764 for (i = 0; i < CHAINHASH_SIZE; i++)
4765 INIT_HLIST_HEAD(chainhash_table + i);
4766 raw_local_irq_restore(flags);
4767}
4768
4769/* Remove a class from a lock chain. Must be called with the graph lock held. */
4770static void remove_class_from_lock_chain(struct pending_free *pf,
4771 struct lock_chain *chain,
4772 struct lock_class *class)
4773{
4774#ifdef CONFIG_PROVE_LOCKING
4775 struct lock_chain *new_chain;
4776 u64 chain_key;
4777 int i;
4778
4779 for (i = chain->base; i < chain->base + chain->depth; i++) {
4780 if (chain_hlocks[i] != class - lock_classes)
4781 continue;
4782 /* The code below leaks one chain_hlock[] entry. */
4783 if (--chain->depth > 0) {
4784 memmove(&chain_hlocks[i], &chain_hlocks[i + 1],
4785 (chain->base + chain->depth - i) *
4786 sizeof(chain_hlocks[0]));
4787 }
4788 /*
4789 * Each lock class occurs at most once in a lock chain so once
4790 * we found a match we can break out of this loop.
4791 */
4792 goto recalc;
4793 }
4794 /* Since the chain has not been modified, return. */
4795 return;
4796
4797recalc:
4798 chain_key = INITIAL_CHAIN_KEY;
4799 for (i = chain->base; i < chain->base + chain->depth; i++)
4800 chain_key = iterate_chain_key(chain_key, chain_hlocks[i]);
4801 if (chain->depth && chain->chain_key == chain_key)
4802 return;
4803 /* Overwrite the chain key for concurrent RCU readers. */
4804 WRITE_ONCE(chain->chain_key, chain_key);
4805 /*
4806 * Note: calling hlist_del_rcu() from inside a
4807 * hlist_for_each_entry_rcu() loop is safe.
4808 */
4809 hlist_del_rcu(&chain->entry);
4810 __set_bit(chain - lock_chains, pf->lock_chains_being_freed);
4811 if (chain->depth == 0)
4812 return;
4813 /*
4814 * If the modified lock chain matches an existing lock chain, drop
4815 * the modified lock chain.
4816 */
4817 if (lookup_chain_cache(chain_key))
4818 return;
4819 new_chain = alloc_lock_chain();
4820 if (WARN_ON_ONCE(!new_chain)) {
4821 debug_locks_off();
4822 return;
4823 }
4824 *new_chain = *chain;
4825 hlist_add_head_rcu(&new_chain->entry, chainhashentry(chain_key));
4826#endif
4827}
4828
4829/* Must be called with the graph lock held. */
4830static void remove_class_from_lock_chains(struct pending_free *pf,
4831 struct lock_class *class)
4832{
4833 struct lock_chain *chain;
4834 struct hlist_head *head;
4835 int i;
4836
4837 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
4838 head = chainhash_table + i;
4839 hlist_for_each_entry_rcu(chain, head, entry) {
4840 remove_class_from_lock_chain(pf, chain, class);
4841 }
4842 }
4843}
4844
4845/*
4846 * Remove all references to a lock class. The caller must hold the graph lock.
4847 */
4848static void zap_class(struct pending_free *pf, struct lock_class *class)
4849{
4850 struct lock_list *entry;
4851 int i;
4852
4853 WARN_ON_ONCE(!class->key);
4854
4855 /*
4856 * Remove all dependencies this lock is
4857 * involved in:
4858 */
4859 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
4860 entry = list_entries + i;
4861 if (entry->class != class && entry->links_to != class)
4862 continue;
4863 __clear_bit(i, list_entries_in_use);
4864 nr_list_entries--;
4865 list_del_rcu(&entry->entry);
4866 }
4867 if (list_empty(&class->locks_after) &&
4868 list_empty(&class->locks_before)) {
4869 list_move_tail(&class->lock_entry, &pf->zapped);
4870 hlist_del_rcu(&class->hash_entry);
4871 WRITE_ONCE(class->key, NULL);
4872 WRITE_ONCE(class->name, NULL);
4873 nr_lock_classes--;
4874 __clear_bit(class - lock_classes, lock_classes_in_use);
4875 } else {
4876 WARN_ONCE(true, "%s() failed for class %s\n", __func__,
4877 class->name);
4878 }
4879
4880 remove_class_from_lock_chains(pf, class);
4881}
4882
4883static void reinit_class(struct lock_class *class)
4884{
4885 void *const p = class;
4886 const unsigned int offset = offsetof(struct lock_class, key);
4887
4888 WARN_ON_ONCE(!class->lock_entry.next);
4889 WARN_ON_ONCE(!list_empty(&class->locks_after));
4890 WARN_ON_ONCE(!list_empty(&class->locks_before));
4891 memset(p + offset, 0, sizeof(*class) - offset);
4892 WARN_ON_ONCE(!class->lock_entry.next);
4893 WARN_ON_ONCE(!list_empty(&class->locks_after));
4894 WARN_ON_ONCE(!list_empty(&class->locks_before));
4895}
4896
4897static inline int within(const void *addr, void *start, unsigned long size)
4898{
4899 return addr >= start && addr < start + size;
4900}
4901
4902static bool inside_selftest(void)
4903{
4904 return current == lockdep_selftest_task_struct;
4905}
4906
4907/* The caller must hold the graph lock. */
4908static struct pending_free *get_pending_free(void)
4909{
4910 return delayed_free.pf + delayed_free.index;
4911}
4912
4913static void free_zapped_rcu(struct rcu_head *cb);
4914
4915/*
4916 * Schedule an RCU callback if no RCU callback is pending. Must be called with
4917 * the graph lock held.
4918 */
4919static void call_rcu_zapped(struct pending_free *pf)
4920{
4921 WARN_ON_ONCE(inside_selftest());
4922
4923 if (list_empty(&pf->zapped))
4924 return;
4925
4926 if (delayed_free.scheduled)
4927 return;
4928
4929 delayed_free.scheduled = true;
4930
4931 WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf);
4932 delayed_free.index ^= 1;
4933
4934 call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
4935}
4936
4937/* The caller must hold the graph lock. May be called from RCU context. */
4938static void __free_zapped_classes(struct pending_free *pf)
4939{
4940 struct lock_class *class;
4941
4942 check_data_structures();
4943
4944 list_for_each_entry(class, &pf->zapped, lock_entry)
4945 reinit_class(class);
4946
4947 list_splice_init(&pf->zapped, &free_lock_classes);
4948
4949#ifdef CONFIG_PROVE_LOCKING
4950 bitmap_andnot(lock_chains_in_use, lock_chains_in_use,
4951 pf->lock_chains_being_freed, ARRAY_SIZE(lock_chains));
4952 bitmap_clear(pf->lock_chains_being_freed, 0, ARRAY_SIZE(lock_chains));
4953#endif
4954}
4955
4956static void free_zapped_rcu(struct rcu_head *ch)
4957{
4958 struct pending_free *pf;
4959 unsigned long flags;
4960
4961 if (WARN_ON_ONCE(ch != &delayed_free.rcu_head))
4962 return;
4963
4964 raw_local_irq_save(flags);
4965 arch_spin_lock(&lockdep_lock);
4966 current->lockdep_recursion = 1;
4967
4968 /* closed head */
4969 pf = delayed_free.pf + (delayed_free.index ^ 1);
4970 __free_zapped_classes(pf);
4971 delayed_free.scheduled = false;
4972
4973 /*
4974 * If there's anything on the open list, close and start a new callback.
4975 */
4976 call_rcu_zapped(delayed_free.pf + delayed_free.index);
4977
4978 current->lockdep_recursion = 0;
4979 arch_spin_unlock(&lockdep_lock);
4980 raw_local_irq_restore(flags);
4981}
4982
4983/*
4984 * Remove all lock classes from the class hash table and from the
4985 * all_lock_classes list whose key or name is in the address range [start,
4986 * start + size). Move these lock classes to the zapped_classes list. Must
4987 * be called with the graph lock held.
4988 */
4989static void __lockdep_free_key_range(struct pending_free *pf, void *start,
4990 unsigned long size)
4991{
4992 struct lock_class *class;
4993 struct hlist_head *head;
4994 int i;
4995
4996 /* Unhash all classes that were created by a module. */
4997 for (i = 0; i < CLASSHASH_SIZE; i++) {
4998 head = classhash_table + i;
4999 hlist_for_each_entry_rcu(class, head, hash_entry) {
5000 if (!within(class->key, start, size) &&
5001 !within(class->name, start, size))
5002 continue;
5003 zap_class(pf, class);
5004 }
5005 }
5006}
5007
5008/*
5009 * Used in module.c to remove lock classes from memory that is going to be
5010 * freed; and possibly re-used by other modules.
5011 *
5012 * We will have had one synchronize_rcu() before getting here, so we're
5013 * guaranteed nobody will look up these exact classes -- they're properly dead
5014 * but still allocated.
5015 */
5016static void lockdep_free_key_range_reg(void *start, unsigned long size)
5017{
5018 struct pending_free *pf;
5019 unsigned long flags;
5020
5021 init_data_structures_once();
5022
5023 raw_local_irq_save(flags);
5024 arch_spin_lock(&lockdep_lock);
5025 current->lockdep_recursion = 1;
5026 pf = get_pending_free();
5027 __lockdep_free_key_range(pf, start, size);
5028 call_rcu_zapped(pf);
5029 current->lockdep_recursion = 0;
5030 arch_spin_unlock(&lockdep_lock);
5031 raw_local_irq_restore(flags);
5032
5033 /*
5034 * Wait for any possible iterators from look_up_lock_class() to pass
5035 * before continuing to free the memory they refer to.
5036 */
5037 synchronize_rcu();
5038}
5039
5040/*
5041 * Free all lockdep keys in the range [start, start+size). Does not sleep.
5042 * Ignores debug_locks. Must only be used by the lockdep selftests.
5043 */
5044static void lockdep_free_key_range_imm(void *start, unsigned long size)
5045{
5046 struct pending_free *pf = delayed_free.pf;
5047 unsigned long flags;
5048
5049 init_data_structures_once();
5050
5051 raw_local_irq_save(flags);
5052 arch_spin_lock(&lockdep_lock);
5053 __lockdep_free_key_range(pf, start, size);
5054 __free_zapped_classes(pf);
5055 arch_spin_unlock(&lockdep_lock);
5056 raw_local_irq_restore(flags);
5057}
5058
5059void lockdep_free_key_range(void *start, unsigned long size)
5060{
5061 init_data_structures_once();
5062
5063 if (inside_selftest())
5064 lockdep_free_key_range_imm(start, size);
5065 else
5066 lockdep_free_key_range_reg(start, size);
5067}
5068
5069/*
5070 * Check whether any element of the @lock->class_cache[] array refers to a
5071 * registered lock class. The caller must hold either the graph lock or the
5072 * RCU read lock.
5073 */
5074static bool lock_class_cache_is_registered(struct lockdep_map *lock)
5075{
5076 struct lock_class *class;
5077 struct hlist_head *head;
5078 int i, j;
5079
5080 for (i = 0; i < CLASSHASH_SIZE; i++) {
5081 head = classhash_table + i;
5082 hlist_for_each_entry_rcu(class, head, hash_entry) {
5083 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
5084 if (lock->class_cache[j] == class)
5085 return true;
5086 }
5087 }
5088 return false;
5089}
5090
5091/* The caller must hold the graph lock. Does not sleep. */
5092static void __lockdep_reset_lock(struct pending_free *pf,
5093 struct lockdep_map *lock)
5094{
5095 struct lock_class *class;
5096 int j;
5097
5098 /*
5099 * Remove all classes this lock might have:
5100 */
5101 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
5102 /*
5103 * If the class exists we look it up and zap it:
5104 */
5105 class = look_up_lock_class(lock, j);
5106 if (class)
5107 zap_class(pf, class);
5108 }
5109 /*
5110 * Debug check: in the end all mapped classes should
5111 * be gone.
5112 */
5113 if (WARN_ON_ONCE(lock_class_cache_is_registered(lock)))
5114 debug_locks_off();
5115}
5116
5117/*
5118 * Remove all information lockdep has about a lock if debug_locks == 1. Free
5119 * released data structures from RCU context.
5120 */
5121static void lockdep_reset_lock_reg(struct lockdep_map *lock)
5122{
5123 struct pending_free *pf;
5124 unsigned long flags;
5125 int locked;
5126
5127 raw_local_irq_save(flags);
5128 locked = graph_lock();
5129 if (!locked)
5130 goto out_irq;
5131
5132 pf = get_pending_free();
5133 __lockdep_reset_lock(pf, lock);
5134 call_rcu_zapped(pf);
5135
5136 graph_unlock();
5137out_irq:
5138 raw_local_irq_restore(flags);
5139}
5140
5141/*
5142 * Reset a lock. Does not sleep. Ignores debug_locks. Must only be used by the
5143 * lockdep selftests.
5144 */
5145static void lockdep_reset_lock_imm(struct lockdep_map *lock)
5146{
5147 struct pending_free *pf = delayed_free.pf;
5148 unsigned long flags;
5149
5150 raw_local_irq_save(flags);
5151 arch_spin_lock(&lockdep_lock);
5152 __lockdep_reset_lock(pf, lock);
5153 __free_zapped_classes(pf);
5154 arch_spin_unlock(&lockdep_lock);
5155 raw_local_irq_restore(flags);
5156}
5157
5158void lockdep_reset_lock(struct lockdep_map *lock)
5159{
5160 init_data_structures_once();
5161
5162 if (inside_selftest())
5163 lockdep_reset_lock_imm(lock);
5164 else
5165 lockdep_reset_lock_reg(lock);
5166}
5167
5168/* Unregister a dynamically allocated key. */
5169void lockdep_unregister_key(struct lock_class_key *key)
5170{
5171 struct hlist_head *hash_head = keyhashentry(key);
5172 struct lock_class_key *k;
5173 struct pending_free *pf;
5174 unsigned long flags;
5175 bool found = false;
5176
5177 might_sleep();
5178
5179 if (WARN_ON_ONCE(static_obj(key)))
5180 return;
5181
5182 raw_local_irq_save(flags);
5183 if (!graph_lock())
5184 goto out_irq;
5185
5186 pf = get_pending_free();
5187 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
5188 if (k == key) {
5189 hlist_del_rcu(&k->hash_entry);
5190 found = true;
5191 break;
5192 }
5193 }
5194 WARN_ON_ONCE(!found);
5195 __lockdep_free_key_range(pf, key, 1);
5196 call_rcu_zapped(pf);
5197 graph_unlock();
5198out_irq:
5199 raw_local_irq_restore(flags);
5200
5201 /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */
5202 synchronize_rcu();
5203}
5204EXPORT_SYMBOL_GPL(lockdep_unregister_key);
5205
5206void __init lockdep_init(void)
5207{
5208 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
5209
5210 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
5211 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
5212 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
5213 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
5214 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
5215 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
5216 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
5217
5218 printk(" memory used by lock dependency info: %zu kB\n",
5219 (sizeof(lock_classes) +
5220 sizeof(lock_classes_in_use) +
5221 sizeof(classhash_table) +
5222 sizeof(list_entries) +
5223 sizeof(list_entries_in_use) +
5224 sizeof(chainhash_table) +
5225 sizeof(delayed_free)
5226#ifdef CONFIG_PROVE_LOCKING
5227 + sizeof(lock_cq)
5228 + sizeof(lock_chains)
5229 + sizeof(lock_chains_in_use)
5230 + sizeof(chain_hlocks)
5231#endif
5232 ) / 1024
5233 );
5234
5235#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
5236 printk(" memory used for stack traces: %zu kB\n",
5237 (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024
5238 );
5239#endif
5240
5241 printk(" per task-struct memory footprint: %zu bytes\n",
5242 sizeof(((struct task_struct *)NULL)->held_locks));
5243}
5244
5245static void
5246print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
5247 const void *mem_to, struct held_lock *hlock)
5248{
5249 if (!debug_locks_off())
5250 return;
5251 if (debug_locks_silent)
5252 return;
5253
5254 pr_warn("\n");
5255 pr_warn("=========================\n");
5256 pr_warn("WARNING: held lock freed!\n");
5257 print_kernel_ident();
5258 pr_warn("-------------------------\n");
5259 pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
5260 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
5261 print_lock(hlock);
5262 lockdep_print_held_locks(curr);
5263
5264 pr_warn("\nstack backtrace:\n");
5265 dump_stack();
5266}
5267
5268static inline int not_in_range(const void* mem_from, unsigned long mem_len,
5269 const void* lock_from, unsigned long lock_len)
5270{
5271 return lock_from + lock_len <= mem_from ||
5272 mem_from + mem_len <= lock_from;
5273}
5274
5275/*
5276 * Called when kernel memory is freed (or unmapped), or if a lock
5277 * is destroyed or reinitialized - this code checks whether there is
5278 * any held lock in the memory range of <from> to <to>:
5279 */
5280void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
5281{
5282 struct task_struct *curr = current;
5283 struct held_lock *hlock;
5284 unsigned long flags;
5285 int i;
5286
5287 if (unlikely(!debug_locks))
5288 return;
5289
5290 raw_local_irq_save(flags);
5291 for (i = 0; i < curr->lockdep_depth; i++) {
5292 hlock = curr->held_locks + i;
5293
5294 if (not_in_range(mem_from, mem_len, hlock->instance,
5295 sizeof(*hlock->instance)))
5296 continue;
5297
5298 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
5299 break;
5300 }
5301 raw_local_irq_restore(flags);
5302}
5303EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
5304
5305static void print_held_locks_bug(void)
5306{
5307 if (!debug_locks_off())
5308 return;
5309 if (debug_locks_silent)
5310 return;
5311
5312 pr_warn("\n");
5313 pr_warn("====================================\n");
5314 pr_warn("WARNING: %s/%d still has locks held!\n",
5315 current->comm, task_pid_nr(current));
5316 print_kernel_ident();
5317 pr_warn("------------------------------------\n");
5318 lockdep_print_held_locks(current);
5319 pr_warn("\nstack backtrace:\n");
5320 dump_stack();
5321}
5322
5323void debug_check_no_locks_held(void)
5324{
5325 if (unlikely(current->lockdep_depth > 0))
5326 print_held_locks_bug();
5327}
5328EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
5329
5330#ifdef __KERNEL__
5331void debug_show_all_locks(void)
5332{
5333 struct task_struct *g, *p;
5334
5335 if (unlikely(!debug_locks)) {
5336 pr_warn("INFO: lockdep is turned off.\n");
5337 return;
5338 }
5339 pr_warn("\nShowing all locks held in the system:\n");
5340
5341 rcu_read_lock();
5342 for_each_process_thread(g, p) {
5343 if (!p->lockdep_depth)
5344 continue;
5345 lockdep_print_held_locks(p);
5346 touch_nmi_watchdog();
5347 touch_all_softlockup_watchdogs();
5348 }
5349 rcu_read_unlock();
5350
5351 pr_warn("\n");
5352 pr_warn("=============================================\n\n");
5353}
5354EXPORT_SYMBOL_GPL(debug_show_all_locks);
5355#endif
5356
5357/*
5358 * Careful: only use this function if you are sure that
5359 * the task cannot run in parallel!
5360 */
5361void debug_show_held_locks(struct task_struct *task)
5362{
5363 if (unlikely(!debug_locks)) {
5364 printk("INFO: lockdep is turned off.\n");
5365 return;
5366 }
5367 lockdep_print_held_locks(task);
5368}
5369EXPORT_SYMBOL_GPL(debug_show_held_locks);
5370
5371asmlinkage __visible void lockdep_sys_exit(void)
5372{
5373 struct task_struct *curr = current;
5374
5375 if (unlikely(curr->lockdep_depth)) {
5376 if (!debug_locks_off())
5377 return;
5378 pr_warn("\n");
5379 pr_warn("================================================\n");
5380 pr_warn("WARNING: lock held when returning to user space!\n");
5381 print_kernel_ident();
5382 pr_warn("------------------------------------------------\n");
5383 pr_warn("%s/%d is leaving the kernel with locks still held!\n",
5384 curr->comm, curr->pid);
5385 lockdep_print_held_locks(curr);
5386 }
5387
5388 /*
5389 * The lock history for each syscall should be independent. So wipe the
5390 * slate clean on return to userspace.
5391 */
5392 lockdep_invariant_state(false);
5393}
5394
5395void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
5396{
5397 struct task_struct *curr = current;
5398
5399 /* Note: the following can be executed concurrently, so be careful. */
5400 pr_warn("\n");
5401 pr_warn("=============================\n");
5402 pr_warn("WARNING: suspicious RCU usage\n");
5403 print_kernel_ident();
5404 pr_warn("-----------------------------\n");
5405 pr_warn("%s:%d %s!\n", file, line, s);
5406 pr_warn("\nother info that might help us debug this:\n\n");
5407 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
5408 !rcu_lockdep_current_cpu_online()
5409 ? "RCU used illegally from offline CPU!\n"
5410 : !rcu_is_watching()
5411 ? "RCU used illegally from idle CPU!\n"
5412 : "",
5413 rcu_scheduler_active, debug_locks);
5414
5415 /*
5416 * If a CPU is in the RCU-free window in idle (ie: in the section
5417 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
5418 * considers that CPU to be in an "extended quiescent state",
5419 * which means that RCU will be completely ignoring that CPU.
5420 * Therefore, rcu_read_lock() and friends have absolutely no
5421 * effect on a CPU running in that state. In other words, even if
5422 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
5423 * delete data structures out from under it. RCU really has no
5424 * choice here: we need to keep an RCU-free window in idle where
5425 * the CPU may possibly enter into low power mode. This way we can
5426 * notice an extended quiescent state to other CPUs that started a grace
5427 * period. Otherwise we would delay any grace period as long as we run
5428 * in the idle task.
5429 *
5430 * So complain bitterly if someone does call rcu_read_lock(),
5431 * rcu_read_lock_bh() and so on from extended quiescent states.
5432 */
5433 if (!rcu_is_watching())
5434 pr_warn("RCU used illegally from extended quiescent state!\n");
5435
5436 lockdep_print_held_locks(curr);
5437 pr_warn("\nstack backtrace:\n");
5438 dump_stack();
5439}
5440EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kernel/lockdep.c
4 *
5 * Runtime locking correctness validator
6 *
7 * Started by Ingo Molnar:
8 *
9 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
10 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
11 *
12 * this code maps all the lock dependencies as they occur in a live kernel
13 * and will warn about the following classes of locking bugs:
14 *
15 * - lock inversion scenarios
16 * - circular lock dependencies
17 * - hardirq/softirq safe/unsafe locking bugs
18 *
19 * Bugs are reported even if the current locking scenario does not cause
20 * any deadlock at this point.
21 *
22 * I.e. if anytime in the past two locks were taken in a different order,
23 * even if it happened for another task, even if those were different
24 * locks (but of the same class as this lock), this code will detect it.
25 *
26 * Thanks to Arjan van de Ven for coming up with the initial idea of
27 * mapping lock dependencies runtime.
28 */
29#define DISABLE_BRANCH_PROFILING
30#include <linux/mutex.h>
31#include <linux/sched.h>
32#include <linux/sched/clock.h>
33#include <linux/sched/task.h>
34#include <linux/sched/mm.h>
35#include <linux/delay.h>
36#include <linux/module.h>
37#include <linux/proc_fs.h>
38#include <linux/seq_file.h>
39#include <linux/spinlock.h>
40#include <linux/kallsyms.h>
41#include <linux/interrupt.h>
42#include <linux/stacktrace.h>
43#include <linux/debug_locks.h>
44#include <linux/irqflags.h>
45#include <linux/utsname.h>
46#include <linux/hash.h>
47#include <linux/ftrace.h>
48#include <linux/stringify.h>
49#include <linux/bitmap.h>
50#include <linux/bitops.h>
51#include <linux/gfp.h>
52#include <linux/random.h>
53#include <linux/jhash.h>
54#include <linux/nmi.h>
55#include <linux/rcupdate.h>
56#include <linux/kprobes.h>
57
58#include <asm/sections.h>
59
60#include "lockdep_internals.h"
61
62#define CREATE_TRACE_POINTS
63#include <trace/events/lock.h>
64
65#ifdef CONFIG_PROVE_LOCKING
66int prove_locking = 1;
67module_param(prove_locking, int, 0644);
68#else
69#define prove_locking 0
70#endif
71
72#ifdef CONFIG_LOCK_STAT
73int lock_stat = 1;
74module_param(lock_stat, int, 0644);
75#else
76#define lock_stat 0
77#endif
78
79/*
80 * lockdep_lock: protects the lockdep graph, the hashes and the
81 * class/list/hash allocators.
82 *
83 * This is one of the rare exceptions where it's justified
84 * to use a raw spinlock - we really dont want the spinlock
85 * code to recurse back into the lockdep code...
86 */
87static arch_spinlock_t __lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
88static struct task_struct *__owner;
89
90static inline void lockdep_lock(void)
91{
92 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
93
94 arch_spin_lock(&__lock);
95 __owner = current;
96 current->lockdep_recursion++;
97}
98
99static inline void lockdep_unlock(void)
100{
101 if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current))
102 return;
103
104 current->lockdep_recursion--;
105 __owner = NULL;
106 arch_spin_unlock(&__lock);
107}
108
109static inline bool lockdep_assert_locked(void)
110{
111 return DEBUG_LOCKS_WARN_ON(__owner != current);
112}
113
114static struct task_struct *lockdep_selftest_task_struct;
115
116
117static int graph_lock(void)
118{
119 lockdep_lock();
120 /*
121 * Make sure that if another CPU detected a bug while
122 * walking the graph we dont change it (while the other
123 * CPU is busy printing out stuff with the graph lock
124 * dropped already)
125 */
126 if (!debug_locks) {
127 lockdep_unlock();
128 return 0;
129 }
130 return 1;
131}
132
133static inline void graph_unlock(void)
134{
135 lockdep_unlock();
136}
137
138/*
139 * Turn lock debugging off and return with 0 if it was off already,
140 * and also release the graph lock:
141 */
142static inline int debug_locks_off_graph_unlock(void)
143{
144 int ret = debug_locks_off();
145
146 lockdep_unlock();
147
148 return ret;
149}
150
151unsigned long nr_list_entries;
152static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
153static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES);
154
155/*
156 * All data structures here are protected by the global debug_lock.
157 *
158 * nr_lock_classes is the number of elements of lock_classes[] that is
159 * in use.
160 */
161#define KEYHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
162#define KEYHASH_SIZE (1UL << KEYHASH_BITS)
163static struct hlist_head lock_keys_hash[KEYHASH_SIZE];
164unsigned long nr_lock_classes;
165unsigned long nr_zapped_classes;
166#ifndef CONFIG_DEBUG_LOCKDEP
167static
168#endif
169struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
170static DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS);
171
172static inline struct lock_class *hlock_class(struct held_lock *hlock)
173{
174 unsigned int class_idx = hlock->class_idx;
175
176 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfield */
177 barrier();
178
179 if (!test_bit(class_idx, lock_classes_in_use)) {
180 /*
181 * Someone passed in garbage, we give up.
182 */
183 DEBUG_LOCKS_WARN_ON(1);
184 return NULL;
185 }
186
187 /*
188 * At this point, if the passed hlock->class_idx is still garbage,
189 * we just have to live with it
190 */
191 return lock_classes + class_idx;
192}
193
194#ifdef CONFIG_LOCK_STAT
195static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
196
197static inline u64 lockstat_clock(void)
198{
199 return local_clock();
200}
201
202static int lock_point(unsigned long points[], unsigned long ip)
203{
204 int i;
205
206 for (i = 0; i < LOCKSTAT_POINTS; i++) {
207 if (points[i] == 0) {
208 points[i] = ip;
209 break;
210 }
211 if (points[i] == ip)
212 break;
213 }
214
215 return i;
216}
217
218static void lock_time_inc(struct lock_time *lt, u64 time)
219{
220 if (time > lt->max)
221 lt->max = time;
222
223 if (time < lt->min || !lt->nr)
224 lt->min = time;
225
226 lt->total += time;
227 lt->nr++;
228}
229
230static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
231{
232 if (!src->nr)
233 return;
234
235 if (src->max > dst->max)
236 dst->max = src->max;
237
238 if (src->min < dst->min || !dst->nr)
239 dst->min = src->min;
240
241 dst->total += src->total;
242 dst->nr += src->nr;
243}
244
245struct lock_class_stats lock_stats(struct lock_class *class)
246{
247 struct lock_class_stats stats;
248 int cpu, i;
249
250 memset(&stats, 0, sizeof(struct lock_class_stats));
251 for_each_possible_cpu(cpu) {
252 struct lock_class_stats *pcs =
253 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
254
255 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
256 stats.contention_point[i] += pcs->contention_point[i];
257
258 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
259 stats.contending_point[i] += pcs->contending_point[i];
260
261 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
262 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
263
264 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
265 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
266
267 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
268 stats.bounces[i] += pcs->bounces[i];
269 }
270
271 return stats;
272}
273
274void clear_lock_stats(struct lock_class *class)
275{
276 int cpu;
277
278 for_each_possible_cpu(cpu) {
279 struct lock_class_stats *cpu_stats =
280 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
281
282 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
283 }
284 memset(class->contention_point, 0, sizeof(class->contention_point));
285 memset(class->contending_point, 0, sizeof(class->contending_point));
286}
287
288static struct lock_class_stats *get_lock_stats(struct lock_class *class)
289{
290 return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes];
291}
292
293static void lock_release_holdtime(struct held_lock *hlock)
294{
295 struct lock_class_stats *stats;
296 u64 holdtime;
297
298 if (!lock_stat)
299 return;
300
301 holdtime = lockstat_clock() - hlock->holdtime_stamp;
302
303 stats = get_lock_stats(hlock_class(hlock));
304 if (hlock->read)
305 lock_time_inc(&stats->read_holdtime, holdtime);
306 else
307 lock_time_inc(&stats->write_holdtime, holdtime);
308}
309#else
310static inline void lock_release_holdtime(struct held_lock *hlock)
311{
312}
313#endif
314
315/*
316 * We keep a global list of all lock classes. The list is only accessed with
317 * the lockdep spinlock lock held. free_lock_classes is a list with free
318 * elements. These elements are linked together by the lock_entry member in
319 * struct lock_class.
320 */
321LIST_HEAD(all_lock_classes);
322static LIST_HEAD(free_lock_classes);
323
324/**
325 * struct pending_free - information about data structures about to be freed
326 * @zapped: Head of a list with struct lock_class elements.
327 * @lock_chains_being_freed: Bitmap that indicates which lock_chains[] elements
328 * are about to be freed.
329 */
330struct pending_free {
331 struct list_head zapped;
332 DECLARE_BITMAP(lock_chains_being_freed, MAX_LOCKDEP_CHAINS);
333};
334
335/**
336 * struct delayed_free - data structures used for delayed freeing
337 *
338 * A data structure for delayed freeing of data structures that may be
339 * accessed by RCU readers at the time these were freed.
340 *
341 * @rcu_head: Used to schedule an RCU callback for freeing data structures.
342 * @index: Index of @pf to which freed data structures are added.
343 * @scheduled: Whether or not an RCU callback has been scheduled.
344 * @pf: Array with information about data structures about to be freed.
345 */
346static struct delayed_free {
347 struct rcu_head rcu_head;
348 int index;
349 int scheduled;
350 struct pending_free pf[2];
351} delayed_free;
352
353/*
354 * The lockdep classes are in a hash-table as well, for fast lookup:
355 */
356#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
357#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
358#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
359#define classhashentry(key) (classhash_table + __classhashfn((key)))
360
361static struct hlist_head classhash_table[CLASSHASH_SIZE];
362
363/*
364 * We put the lock dependency chains into a hash-table as well, to cache
365 * their existence:
366 */
367#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
368#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
369#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
370#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
371
372static struct hlist_head chainhash_table[CHAINHASH_SIZE];
373
374/*
375 * The hash key of the lock dependency chains is a hash itself too:
376 * it's a hash of all locks taken up to that lock, including that lock.
377 * It's a 64-bit hash, because it's important for the keys to be
378 * unique.
379 */
380static inline u64 iterate_chain_key(u64 key, u32 idx)
381{
382 u32 k0 = key, k1 = key >> 32;
383
384 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
385
386 return k0 | (u64)k1 << 32;
387}
388
389void lockdep_init_task(struct task_struct *task)
390{
391 task->lockdep_depth = 0; /* no locks held yet */
392 task->curr_chain_key = INITIAL_CHAIN_KEY;
393 task->lockdep_recursion = 0;
394}
395
396static __always_inline void lockdep_recursion_finish(void)
397{
398 if (WARN_ON_ONCE((--current->lockdep_recursion) & LOCKDEP_RECURSION_MASK))
399 current->lockdep_recursion = 0;
400}
401
402void lockdep_set_selftest_task(struct task_struct *task)
403{
404 lockdep_selftest_task_struct = task;
405}
406
407/*
408 * Debugging switches:
409 */
410
411#define VERBOSE 0
412#define VERY_VERBOSE 0
413
414#if VERBOSE
415# define HARDIRQ_VERBOSE 1
416# define SOFTIRQ_VERBOSE 1
417#else
418# define HARDIRQ_VERBOSE 0
419# define SOFTIRQ_VERBOSE 0
420#endif
421
422#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
423/*
424 * Quick filtering for interesting events:
425 */
426static int class_filter(struct lock_class *class)
427{
428#if 0
429 /* Example */
430 if (class->name_version == 1 &&
431 !strcmp(class->name, "lockname"))
432 return 1;
433 if (class->name_version == 1 &&
434 !strcmp(class->name, "&struct->lockfield"))
435 return 1;
436#endif
437 /* Filter everything else. 1 would be to allow everything else */
438 return 0;
439}
440#endif
441
442static int verbose(struct lock_class *class)
443{
444#if VERBOSE
445 return class_filter(class);
446#endif
447 return 0;
448}
449
450static void print_lockdep_off(const char *bug_msg)
451{
452 printk(KERN_DEBUG "%s\n", bug_msg);
453 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
454#ifdef CONFIG_LOCK_STAT
455 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
456#endif
457}
458
459unsigned long nr_stack_trace_entries;
460
461#ifdef CONFIG_PROVE_LOCKING
462/**
463 * struct lock_trace - single stack backtrace
464 * @hash_entry: Entry in a stack_trace_hash[] list.
465 * @hash: jhash() of @entries.
466 * @nr_entries: Number of entries in @entries.
467 * @entries: Actual stack backtrace.
468 */
469struct lock_trace {
470 struct hlist_node hash_entry;
471 u32 hash;
472 u32 nr_entries;
473 unsigned long entries[] __aligned(sizeof(unsigned long));
474};
475#define LOCK_TRACE_SIZE_IN_LONGS \
476 (sizeof(struct lock_trace) / sizeof(unsigned long))
477/*
478 * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock.
479 */
480static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
481static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE];
482
483static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2)
484{
485 return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries &&
486 memcmp(t1->entries, t2->entries,
487 t1->nr_entries * sizeof(t1->entries[0])) == 0;
488}
489
490static struct lock_trace *save_trace(void)
491{
492 struct lock_trace *trace, *t2;
493 struct hlist_head *hash_head;
494 u32 hash;
495 int max_entries;
496
497 BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE);
498 BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES);
499
500 trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries);
501 max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries -
502 LOCK_TRACE_SIZE_IN_LONGS;
503
504 if (max_entries <= 0) {
505 if (!debug_locks_off_graph_unlock())
506 return NULL;
507
508 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
509 dump_stack();
510
511 return NULL;
512 }
513 trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
514
515 hash = jhash(trace->entries, trace->nr_entries *
516 sizeof(trace->entries[0]), 0);
517 trace->hash = hash;
518 hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1));
519 hlist_for_each_entry(t2, hash_head, hash_entry) {
520 if (traces_identical(trace, t2))
521 return t2;
522 }
523 nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries;
524 hlist_add_head(&trace->hash_entry, hash_head);
525
526 return trace;
527}
528
529/* Return the number of stack traces in the stack_trace[] array. */
530u64 lockdep_stack_trace_count(void)
531{
532 struct lock_trace *trace;
533 u64 c = 0;
534 int i;
535
536 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) {
537 hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) {
538 c++;
539 }
540 }
541
542 return c;
543}
544
545/* Return the number of stack hash chains that have at least one stack trace. */
546u64 lockdep_stack_hash_count(void)
547{
548 u64 c = 0;
549 int i;
550
551 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++)
552 if (!hlist_empty(&stack_trace_hash[i]))
553 c++;
554
555 return c;
556}
557#endif
558
559unsigned int nr_hardirq_chains;
560unsigned int nr_softirq_chains;
561unsigned int nr_process_chains;
562unsigned int max_lockdep_depth;
563
564#ifdef CONFIG_DEBUG_LOCKDEP
565/*
566 * Various lockdep statistics:
567 */
568DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
569#endif
570
571#ifdef CONFIG_PROVE_LOCKING
572/*
573 * Locking printouts:
574 */
575
576#define __USAGE(__STATE) \
577 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
578 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
579 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
580 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
581
582static const char *usage_str[] =
583{
584#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
585#include "lockdep_states.h"
586#undef LOCKDEP_STATE
587 [LOCK_USED] = "INITIAL USE",
588 [LOCK_USAGE_STATES] = "IN-NMI",
589};
590#endif
591
592const char *__get_key_name(const struct lockdep_subclass_key *key, char *str)
593{
594 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
595}
596
597static inline unsigned long lock_flag(enum lock_usage_bit bit)
598{
599 return 1UL << bit;
600}
601
602static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
603{
604 /*
605 * The usage character defaults to '.' (i.e., irqs disabled and not in
606 * irq context), which is the safest usage category.
607 */
608 char c = '.';
609
610 /*
611 * The order of the following usage checks matters, which will
612 * result in the outcome character as follows:
613 *
614 * - '+': irq is enabled and not in irq context
615 * - '-': in irq context and irq is disabled
616 * - '?': in irq context and irq is enabled
617 */
618 if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) {
619 c = '+';
620 if (class->usage_mask & lock_flag(bit))
621 c = '?';
622 } else if (class->usage_mask & lock_flag(bit))
623 c = '-';
624
625 return c;
626}
627
628void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
629{
630 int i = 0;
631
632#define LOCKDEP_STATE(__STATE) \
633 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
634 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
635#include "lockdep_states.h"
636#undef LOCKDEP_STATE
637
638 usage[i] = '\0';
639}
640
641static void __print_lock_name(struct lock_class *class)
642{
643 char str[KSYM_NAME_LEN];
644 const char *name;
645
646 name = class->name;
647 if (!name) {
648 name = __get_key_name(class->key, str);
649 printk(KERN_CONT "%s", name);
650 } else {
651 printk(KERN_CONT "%s", name);
652 if (class->name_version > 1)
653 printk(KERN_CONT "#%d", class->name_version);
654 if (class->subclass)
655 printk(KERN_CONT "/%d", class->subclass);
656 }
657}
658
659static void print_lock_name(struct lock_class *class)
660{
661 char usage[LOCK_USAGE_CHARS];
662
663 get_usage_chars(class, usage);
664
665 printk(KERN_CONT " (");
666 __print_lock_name(class);
667 printk(KERN_CONT "){%s}-{%hd:%hd}", usage,
668 class->wait_type_outer ?: class->wait_type_inner,
669 class->wait_type_inner);
670}
671
672static void print_lockdep_cache(struct lockdep_map *lock)
673{
674 const char *name;
675 char str[KSYM_NAME_LEN];
676
677 name = lock->name;
678 if (!name)
679 name = __get_key_name(lock->key->subkeys, str);
680
681 printk(KERN_CONT "%s", name);
682}
683
684static void print_lock(struct held_lock *hlock)
685{
686 /*
687 * We can be called locklessly through debug_show_all_locks() so be
688 * extra careful, the hlock might have been released and cleared.
689 *
690 * If this indeed happens, lets pretend it does not hurt to continue
691 * to print the lock unless the hlock class_idx does not point to a
692 * registered class. The rationale here is: since we don't attempt
693 * to distinguish whether we are in this situation, if it just
694 * happened we can't count on class_idx to tell either.
695 */
696 struct lock_class *lock = hlock_class(hlock);
697
698 if (!lock) {
699 printk(KERN_CONT "<RELEASED>\n");
700 return;
701 }
702
703 printk(KERN_CONT "%px", hlock->instance);
704 print_lock_name(lock);
705 printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
706}
707
708static void lockdep_print_held_locks(struct task_struct *p)
709{
710 int i, depth = READ_ONCE(p->lockdep_depth);
711
712 if (!depth)
713 printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p));
714 else
715 printk("%d lock%s held by %s/%d:\n", depth,
716 depth > 1 ? "s" : "", p->comm, task_pid_nr(p));
717 /*
718 * It's not reliable to print a task's held locks if it's not sleeping
719 * and it's not the current task.
720 */
721 if (p->state == TASK_RUNNING && p != current)
722 return;
723 for (i = 0; i < depth; i++) {
724 printk(" #%d: ", i);
725 print_lock(p->held_locks + i);
726 }
727}
728
729static void print_kernel_ident(void)
730{
731 printk("%s %.*s %s\n", init_utsname()->release,
732 (int)strcspn(init_utsname()->version, " "),
733 init_utsname()->version,
734 print_tainted());
735}
736
737static int very_verbose(struct lock_class *class)
738{
739#if VERY_VERBOSE
740 return class_filter(class);
741#endif
742 return 0;
743}
744
745/*
746 * Is this the address of a static object:
747 */
748#ifdef __KERNEL__
749static int static_obj(const void *obj)
750{
751 unsigned long start = (unsigned long) &_stext,
752 end = (unsigned long) &_end,
753 addr = (unsigned long) obj;
754
755 if (arch_is_kernel_initmem_freed(addr))
756 return 0;
757
758 /*
759 * static variable?
760 */
761 if ((addr >= start) && (addr < end))
762 return 1;
763
764 if (arch_is_kernel_data(addr))
765 return 1;
766
767 /*
768 * in-kernel percpu var?
769 */
770 if (is_kernel_percpu_address(addr))
771 return 1;
772
773 /*
774 * module static or percpu var?
775 */
776 return is_module_address(addr) || is_module_percpu_address(addr);
777}
778#endif
779
780/*
781 * To make lock name printouts unique, we calculate a unique
782 * class->name_version generation counter. The caller must hold the graph
783 * lock.
784 */
785static int count_matching_names(struct lock_class *new_class)
786{
787 struct lock_class *class;
788 int count = 0;
789
790 if (!new_class->name)
791 return 0;
792
793 list_for_each_entry(class, &all_lock_classes, lock_entry) {
794 if (new_class->key - new_class->subclass == class->key)
795 return class->name_version;
796 if (class->name && !strcmp(class->name, new_class->name))
797 count = max(count, class->name_version);
798 }
799
800 return count + 1;
801}
802
803/* used from NMI context -- must be lockless */
804static __always_inline struct lock_class *
805look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
806{
807 struct lockdep_subclass_key *key;
808 struct hlist_head *hash_head;
809 struct lock_class *class;
810
811 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
812 debug_locks_off();
813 printk(KERN_ERR
814 "BUG: looking up invalid subclass: %u\n", subclass);
815 printk(KERN_ERR
816 "turning off the locking correctness validator.\n");
817 dump_stack();
818 return NULL;
819 }
820
821 /*
822 * If it is not initialised then it has never been locked,
823 * so it won't be present in the hash table.
824 */
825 if (unlikely(!lock->key))
826 return NULL;
827
828 /*
829 * NOTE: the class-key must be unique. For dynamic locks, a static
830 * lock_class_key variable is passed in through the mutex_init()
831 * (or spin_lock_init()) call - which acts as the key. For static
832 * locks we use the lock object itself as the key.
833 */
834 BUILD_BUG_ON(sizeof(struct lock_class_key) >
835 sizeof(struct lockdep_map));
836
837 key = lock->key->subkeys + subclass;
838
839 hash_head = classhashentry(key);
840
841 /*
842 * We do an RCU walk of the hash, see lockdep_free_key_range().
843 */
844 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
845 return NULL;
846
847 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
848 if (class->key == key) {
849 /*
850 * Huh! same key, different name? Did someone trample
851 * on some memory? We're most confused.
852 */
853 WARN_ON_ONCE(class->name != lock->name &&
854 lock->key != &__lockdep_no_validate__);
855 return class;
856 }
857 }
858
859 return NULL;
860}
861
862/*
863 * Static locks do not have their class-keys yet - for them the key is
864 * the lock object itself. If the lock is in the per cpu area, the
865 * canonical address of the lock (per cpu offset removed) is used.
866 */
867static bool assign_lock_key(struct lockdep_map *lock)
868{
869 unsigned long can_addr, addr = (unsigned long)lock;
870
871#ifdef __KERNEL__
872 /*
873 * lockdep_free_key_range() assumes that struct lock_class_key
874 * objects do not overlap. Since we use the address of lock
875 * objects as class key for static objects, check whether the
876 * size of lock_class_key objects does not exceed the size of
877 * the smallest lock object.
878 */
879 BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
880#endif
881
882 if (__is_kernel_percpu_address(addr, &can_addr))
883 lock->key = (void *)can_addr;
884 else if (__is_module_percpu_address(addr, &can_addr))
885 lock->key = (void *)can_addr;
886 else if (static_obj(lock))
887 lock->key = (void *)lock;
888 else {
889 /* Debug-check: all keys must be persistent! */
890 debug_locks_off();
891 pr_err("INFO: trying to register non-static key.\n");
892 pr_err("the code is fine but needs lockdep annotation.\n");
893 pr_err("turning off the locking correctness validator.\n");
894 dump_stack();
895 return false;
896 }
897
898 return true;
899}
900
901#ifdef CONFIG_DEBUG_LOCKDEP
902
903/* Check whether element @e occurs in list @h */
904static bool in_list(struct list_head *e, struct list_head *h)
905{
906 struct list_head *f;
907
908 list_for_each(f, h) {
909 if (e == f)
910 return true;
911 }
912
913 return false;
914}
915
916/*
917 * Check whether entry @e occurs in any of the locks_after or locks_before
918 * lists.
919 */
920static bool in_any_class_list(struct list_head *e)
921{
922 struct lock_class *class;
923 int i;
924
925 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
926 class = &lock_classes[i];
927 if (in_list(e, &class->locks_after) ||
928 in_list(e, &class->locks_before))
929 return true;
930 }
931 return false;
932}
933
934static bool class_lock_list_valid(struct lock_class *c, struct list_head *h)
935{
936 struct lock_list *e;
937
938 list_for_each_entry(e, h, entry) {
939 if (e->links_to != c) {
940 printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s",
941 c->name ? : "(?)",
942 (unsigned long)(e - list_entries),
943 e->links_to && e->links_to->name ?
944 e->links_to->name : "(?)",
945 e->class && e->class->name ? e->class->name :
946 "(?)");
947 return false;
948 }
949 }
950 return true;
951}
952
953#ifdef CONFIG_PROVE_LOCKING
954static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
955#endif
956
957static bool check_lock_chain_key(struct lock_chain *chain)
958{
959#ifdef CONFIG_PROVE_LOCKING
960 u64 chain_key = INITIAL_CHAIN_KEY;
961 int i;
962
963 for (i = chain->base; i < chain->base + chain->depth; i++)
964 chain_key = iterate_chain_key(chain_key, chain_hlocks[i]);
965 /*
966 * The 'unsigned long long' casts avoid that a compiler warning
967 * is reported when building tools/lib/lockdep.
968 */
969 if (chain->chain_key != chain_key) {
970 printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n",
971 (unsigned long long)(chain - lock_chains),
972 (unsigned long long)chain->chain_key,
973 (unsigned long long)chain_key);
974 return false;
975 }
976#endif
977 return true;
978}
979
980static bool in_any_zapped_class_list(struct lock_class *class)
981{
982 struct pending_free *pf;
983 int i;
984
985 for (i = 0, pf = delayed_free.pf; i < ARRAY_SIZE(delayed_free.pf); i++, pf++) {
986 if (in_list(&class->lock_entry, &pf->zapped))
987 return true;
988 }
989
990 return false;
991}
992
993static bool __check_data_structures(void)
994{
995 struct lock_class *class;
996 struct lock_chain *chain;
997 struct hlist_head *head;
998 struct lock_list *e;
999 int i;
1000
1001 /* Check whether all classes occur in a lock list. */
1002 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1003 class = &lock_classes[i];
1004 if (!in_list(&class->lock_entry, &all_lock_classes) &&
1005 !in_list(&class->lock_entry, &free_lock_classes) &&
1006 !in_any_zapped_class_list(class)) {
1007 printk(KERN_INFO "class %px/%s is not in any class list\n",
1008 class, class->name ? : "(?)");
1009 return false;
1010 }
1011 }
1012
1013 /* Check whether all classes have valid lock lists. */
1014 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1015 class = &lock_classes[i];
1016 if (!class_lock_list_valid(class, &class->locks_before))
1017 return false;
1018 if (!class_lock_list_valid(class, &class->locks_after))
1019 return false;
1020 }
1021
1022 /* Check the chain_key of all lock chains. */
1023 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
1024 head = chainhash_table + i;
1025 hlist_for_each_entry_rcu(chain, head, entry) {
1026 if (!check_lock_chain_key(chain))
1027 return false;
1028 }
1029 }
1030
1031 /*
1032 * Check whether all list entries that are in use occur in a class
1033 * lock list.
1034 */
1035 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1036 e = list_entries + i;
1037 if (!in_any_class_list(&e->entry)) {
1038 printk(KERN_INFO "list entry %d is not in any class list; class %s <> %s\n",
1039 (unsigned int)(e - list_entries),
1040 e->class->name ? : "(?)",
1041 e->links_to->name ? : "(?)");
1042 return false;
1043 }
1044 }
1045
1046 /*
1047 * Check whether all list entries that are not in use do not occur in
1048 * a class lock list.
1049 */
1050 for_each_clear_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1051 e = list_entries + i;
1052 if (in_any_class_list(&e->entry)) {
1053 printk(KERN_INFO "list entry %d occurs in a class list; class %s <> %s\n",
1054 (unsigned int)(e - list_entries),
1055 e->class && e->class->name ? e->class->name :
1056 "(?)",
1057 e->links_to && e->links_to->name ?
1058 e->links_to->name : "(?)");
1059 return false;
1060 }
1061 }
1062
1063 return true;
1064}
1065
1066int check_consistency = 0;
1067module_param(check_consistency, int, 0644);
1068
1069static void check_data_structures(void)
1070{
1071 static bool once = false;
1072
1073 if (check_consistency && !once) {
1074 if (!__check_data_structures()) {
1075 once = true;
1076 WARN_ON(once);
1077 }
1078 }
1079}
1080
1081#else /* CONFIG_DEBUG_LOCKDEP */
1082
1083static inline void check_data_structures(void) { }
1084
1085#endif /* CONFIG_DEBUG_LOCKDEP */
1086
1087static void init_chain_block_buckets(void);
1088
1089/*
1090 * Initialize the lock_classes[] array elements, the free_lock_classes list
1091 * and also the delayed_free structure.
1092 */
1093static void init_data_structures_once(void)
1094{
1095 static bool __read_mostly ds_initialized, rcu_head_initialized;
1096 int i;
1097
1098 if (likely(rcu_head_initialized))
1099 return;
1100
1101 if (system_state >= SYSTEM_SCHEDULING) {
1102 init_rcu_head(&delayed_free.rcu_head);
1103 rcu_head_initialized = true;
1104 }
1105
1106 if (ds_initialized)
1107 return;
1108
1109 ds_initialized = true;
1110
1111 INIT_LIST_HEAD(&delayed_free.pf[0].zapped);
1112 INIT_LIST_HEAD(&delayed_free.pf[1].zapped);
1113
1114 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1115 list_add_tail(&lock_classes[i].lock_entry, &free_lock_classes);
1116 INIT_LIST_HEAD(&lock_classes[i].locks_after);
1117 INIT_LIST_HEAD(&lock_classes[i].locks_before);
1118 }
1119 init_chain_block_buckets();
1120}
1121
1122static inline struct hlist_head *keyhashentry(const struct lock_class_key *key)
1123{
1124 unsigned long hash = hash_long((uintptr_t)key, KEYHASH_BITS);
1125
1126 return lock_keys_hash + hash;
1127}
1128
1129/* Register a dynamically allocated key. */
1130void lockdep_register_key(struct lock_class_key *key)
1131{
1132 struct hlist_head *hash_head;
1133 struct lock_class_key *k;
1134 unsigned long flags;
1135
1136 if (WARN_ON_ONCE(static_obj(key)))
1137 return;
1138 hash_head = keyhashentry(key);
1139
1140 raw_local_irq_save(flags);
1141 if (!graph_lock())
1142 goto restore_irqs;
1143 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1144 if (WARN_ON_ONCE(k == key))
1145 goto out_unlock;
1146 }
1147 hlist_add_head_rcu(&key->hash_entry, hash_head);
1148out_unlock:
1149 graph_unlock();
1150restore_irqs:
1151 raw_local_irq_restore(flags);
1152}
1153EXPORT_SYMBOL_GPL(lockdep_register_key);
1154
1155/* Check whether a key has been registered as a dynamic key. */
1156static bool is_dynamic_key(const struct lock_class_key *key)
1157{
1158 struct hlist_head *hash_head;
1159 struct lock_class_key *k;
1160 bool found = false;
1161
1162 if (WARN_ON_ONCE(static_obj(key)))
1163 return false;
1164
1165 /*
1166 * If lock debugging is disabled lock_keys_hash[] may contain
1167 * pointers to memory that has already been freed. Avoid triggering
1168 * a use-after-free in that case by returning early.
1169 */
1170 if (!debug_locks)
1171 return true;
1172
1173 hash_head = keyhashentry(key);
1174
1175 rcu_read_lock();
1176 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1177 if (k == key) {
1178 found = true;
1179 break;
1180 }
1181 }
1182 rcu_read_unlock();
1183
1184 return found;
1185}
1186
1187/*
1188 * Register a lock's class in the hash-table, if the class is not present
1189 * yet. Otherwise we look it up. We cache the result in the lock object
1190 * itself, so actual lookup of the hash should be once per lock object.
1191 */
1192static struct lock_class *
1193register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
1194{
1195 struct lockdep_subclass_key *key;
1196 struct hlist_head *hash_head;
1197 struct lock_class *class;
1198
1199 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1200
1201 class = look_up_lock_class(lock, subclass);
1202 if (likely(class))
1203 goto out_set_class_cache;
1204
1205 if (!lock->key) {
1206 if (!assign_lock_key(lock))
1207 return NULL;
1208 } else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) {
1209 return NULL;
1210 }
1211
1212 key = lock->key->subkeys + subclass;
1213 hash_head = classhashentry(key);
1214
1215 if (!graph_lock()) {
1216 return NULL;
1217 }
1218 /*
1219 * We have to do the hash-walk again, to avoid races
1220 * with another CPU:
1221 */
1222 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
1223 if (class->key == key)
1224 goto out_unlock_set;
1225 }
1226
1227 init_data_structures_once();
1228
1229 /* Allocate a new lock class and add it to the hash. */
1230 class = list_first_entry_or_null(&free_lock_classes, typeof(*class),
1231 lock_entry);
1232 if (!class) {
1233 if (!debug_locks_off_graph_unlock()) {
1234 return NULL;
1235 }
1236
1237 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
1238 dump_stack();
1239 return NULL;
1240 }
1241 nr_lock_classes++;
1242 __set_bit(class - lock_classes, lock_classes_in_use);
1243 debug_atomic_inc(nr_unused_locks);
1244 class->key = key;
1245 class->name = lock->name;
1246 class->subclass = subclass;
1247 WARN_ON_ONCE(!list_empty(&class->locks_before));
1248 WARN_ON_ONCE(!list_empty(&class->locks_after));
1249 class->name_version = count_matching_names(class);
1250 class->wait_type_inner = lock->wait_type_inner;
1251 class->wait_type_outer = lock->wait_type_outer;
1252 /*
1253 * We use RCU's safe list-add method to make
1254 * parallel walking of the hash-list safe:
1255 */
1256 hlist_add_head_rcu(&class->hash_entry, hash_head);
1257 /*
1258 * Remove the class from the free list and add it to the global list
1259 * of classes.
1260 */
1261 list_move_tail(&class->lock_entry, &all_lock_classes);
1262
1263 if (verbose(class)) {
1264 graph_unlock();
1265
1266 printk("\nnew class %px: %s", class->key, class->name);
1267 if (class->name_version > 1)
1268 printk(KERN_CONT "#%d", class->name_version);
1269 printk(KERN_CONT "\n");
1270 dump_stack();
1271
1272 if (!graph_lock()) {
1273 return NULL;
1274 }
1275 }
1276out_unlock_set:
1277 graph_unlock();
1278
1279out_set_class_cache:
1280 if (!subclass || force)
1281 lock->class_cache[0] = class;
1282 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
1283 lock->class_cache[subclass] = class;
1284
1285 /*
1286 * Hash collision, did we smoke some? We found a class with a matching
1287 * hash but the subclass -- which is hashed in -- didn't match.
1288 */
1289 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
1290 return NULL;
1291
1292 return class;
1293}
1294
1295#ifdef CONFIG_PROVE_LOCKING
1296/*
1297 * Allocate a lockdep entry. (assumes the graph_lock held, returns
1298 * with NULL on failure)
1299 */
1300static struct lock_list *alloc_list_entry(void)
1301{
1302 int idx = find_first_zero_bit(list_entries_in_use,
1303 ARRAY_SIZE(list_entries));
1304
1305 if (idx >= ARRAY_SIZE(list_entries)) {
1306 if (!debug_locks_off_graph_unlock())
1307 return NULL;
1308
1309 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
1310 dump_stack();
1311 return NULL;
1312 }
1313 nr_list_entries++;
1314 __set_bit(idx, list_entries_in_use);
1315 return list_entries + idx;
1316}
1317
1318/*
1319 * Add a new dependency to the head of the list:
1320 */
1321static int add_lock_to_list(struct lock_class *this,
1322 struct lock_class *links_to, struct list_head *head,
1323 unsigned long ip, int distance,
1324 const struct lock_trace *trace)
1325{
1326 struct lock_list *entry;
1327 /*
1328 * Lock not present yet - get a new dependency struct and
1329 * add it to the list:
1330 */
1331 entry = alloc_list_entry();
1332 if (!entry)
1333 return 0;
1334
1335 entry->class = this;
1336 entry->links_to = links_to;
1337 entry->distance = distance;
1338 entry->trace = trace;
1339 /*
1340 * Both allocation and removal are done under the graph lock; but
1341 * iteration is under RCU-sched; see look_up_lock_class() and
1342 * lockdep_free_key_range().
1343 */
1344 list_add_tail_rcu(&entry->entry, head);
1345
1346 return 1;
1347}
1348
1349/*
1350 * For good efficiency of modular, we use power of 2
1351 */
1352#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
1353#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
1354
1355/*
1356 * The circular_queue and helpers are used to implement graph
1357 * breadth-first search (BFS) algorithm, by which we can determine
1358 * whether there is a path from a lock to another. In deadlock checks,
1359 * a path from the next lock to be acquired to a previous held lock
1360 * indicates that adding the <prev> -> <next> lock dependency will
1361 * produce a circle in the graph. Breadth-first search instead of
1362 * depth-first search is used in order to find the shortest (circular)
1363 * path.
1364 */
1365struct circular_queue {
1366 struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE];
1367 unsigned int front, rear;
1368};
1369
1370static struct circular_queue lock_cq;
1371
1372unsigned int max_bfs_queue_depth;
1373
1374static unsigned int lockdep_dependency_gen_id;
1375
1376static inline void __cq_init(struct circular_queue *cq)
1377{
1378 cq->front = cq->rear = 0;
1379 lockdep_dependency_gen_id++;
1380}
1381
1382static inline int __cq_empty(struct circular_queue *cq)
1383{
1384 return (cq->front == cq->rear);
1385}
1386
1387static inline int __cq_full(struct circular_queue *cq)
1388{
1389 return ((cq->rear + 1) & CQ_MASK) == cq->front;
1390}
1391
1392static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem)
1393{
1394 if (__cq_full(cq))
1395 return -1;
1396
1397 cq->element[cq->rear] = elem;
1398 cq->rear = (cq->rear + 1) & CQ_MASK;
1399 return 0;
1400}
1401
1402/*
1403 * Dequeue an element from the circular_queue, return a lock_list if
1404 * the queue is not empty, or NULL if otherwise.
1405 */
1406static inline struct lock_list * __cq_dequeue(struct circular_queue *cq)
1407{
1408 struct lock_list * lock;
1409
1410 if (__cq_empty(cq))
1411 return NULL;
1412
1413 lock = cq->element[cq->front];
1414 cq->front = (cq->front + 1) & CQ_MASK;
1415
1416 return lock;
1417}
1418
1419static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
1420{
1421 return (cq->rear - cq->front) & CQ_MASK;
1422}
1423
1424static inline void mark_lock_accessed(struct lock_list *lock,
1425 struct lock_list *parent)
1426{
1427 unsigned long nr;
1428
1429 nr = lock - list_entries;
1430 WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */
1431 lock->parent = parent;
1432 lock->class->dep_gen_id = lockdep_dependency_gen_id;
1433}
1434
1435static inline unsigned long lock_accessed(struct lock_list *lock)
1436{
1437 unsigned long nr;
1438
1439 nr = lock - list_entries;
1440 WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */
1441 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
1442}
1443
1444static inline struct lock_list *get_lock_parent(struct lock_list *child)
1445{
1446 return child->parent;
1447}
1448
1449static inline int get_lock_depth(struct lock_list *child)
1450{
1451 int depth = 0;
1452 struct lock_list *parent;
1453
1454 while ((parent = get_lock_parent(child))) {
1455 child = parent;
1456 depth++;
1457 }
1458 return depth;
1459}
1460
1461/*
1462 * Return the forward or backward dependency list.
1463 *
1464 * @lock: the lock_list to get its class's dependency list
1465 * @offset: the offset to struct lock_class to determine whether it is
1466 * locks_after or locks_before
1467 */
1468static inline struct list_head *get_dep_list(struct lock_list *lock, int offset)
1469{
1470 void *lock_class = lock->class;
1471
1472 return lock_class + offset;
1473}
1474
1475/*
1476 * Forward- or backward-dependency search, used for both circular dependency
1477 * checking and hardirq-unsafe/softirq-unsafe checking.
1478 */
1479static int __bfs(struct lock_list *source_entry,
1480 void *data,
1481 int (*match)(struct lock_list *entry, void *data),
1482 struct lock_list **target_entry,
1483 int offset)
1484{
1485 struct lock_list *entry;
1486 struct lock_list *lock;
1487 struct list_head *head;
1488 struct circular_queue *cq = &lock_cq;
1489 int ret = 1;
1490
1491 lockdep_assert_locked();
1492
1493 if (match(source_entry, data)) {
1494 *target_entry = source_entry;
1495 ret = 0;
1496 goto exit;
1497 }
1498
1499 head = get_dep_list(source_entry, offset);
1500 if (list_empty(head))
1501 goto exit;
1502
1503 __cq_init(cq);
1504 __cq_enqueue(cq, source_entry);
1505
1506 while ((lock = __cq_dequeue(cq))) {
1507
1508 if (!lock->class) {
1509 ret = -2;
1510 goto exit;
1511 }
1512
1513 head = get_dep_list(lock, offset);
1514
1515 list_for_each_entry_rcu(entry, head, entry) {
1516 if (!lock_accessed(entry)) {
1517 unsigned int cq_depth;
1518 mark_lock_accessed(entry, lock);
1519 if (match(entry, data)) {
1520 *target_entry = entry;
1521 ret = 0;
1522 goto exit;
1523 }
1524
1525 if (__cq_enqueue(cq, entry)) {
1526 ret = -1;
1527 goto exit;
1528 }
1529 cq_depth = __cq_get_elem_count(cq);
1530 if (max_bfs_queue_depth < cq_depth)
1531 max_bfs_queue_depth = cq_depth;
1532 }
1533 }
1534 }
1535exit:
1536 return ret;
1537}
1538
1539static inline int __bfs_forwards(struct lock_list *src_entry,
1540 void *data,
1541 int (*match)(struct lock_list *entry, void *data),
1542 struct lock_list **target_entry)
1543{
1544 return __bfs(src_entry, data, match, target_entry,
1545 offsetof(struct lock_class, locks_after));
1546
1547}
1548
1549static inline int __bfs_backwards(struct lock_list *src_entry,
1550 void *data,
1551 int (*match)(struct lock_list *entry, void *data),
1552 struct lock_list **target_entry)
1553{
1554 return __bfs(src_entry, data, match, target_entry,
1555 offsetof(struct lock_class, locks_before));
1556
1557}
1558
1559static void print_lock_trace(const struct lock_trace *trace,
1560 unsigned int spaces)
1561{
1562 stack_trace_print(trace->entries, trace->nr_entries, spaces);
1563}
1564
1565/*
1566 * Print a dependency chain entry (this is only done when a deadlock
1567 * has been detected):
1568 */
1569static noinline void
1570print_circular_bug_entry(struct lock_list *target, int depth)
1571{
1572 if (debug_locks_silent)
1573 return;
1574 printk("\n-> #%u", depth);
1575 print_lock_name(target->class);
1576 printk(KERN_CONT ":\n");
1577 print_lock_trace(target->trace, 6);
1578}
1579
1580static void
1581print_circular_lock_scenario(struct held_lock *src,
1582 struct held_lock *tgt,
1583 struct lock_list *prt)
1584{
1585 struct lock_class *source = hlock_class(src);
1586 struct lock_class *target = hlock_class(tgt);
1587 struct lock_class *parent = prt->class;
1588
1589 /*
1590 * A direct locking problem where unsafe_class lock is taken
1591 * directly by safe_class lock, then all we need to show
1592 * is the deadlock scenario, as it is obvious that the
1593 * unsafe lock is taken under the safe lock.
1594 *
1595 * But if there is a chain instead, where the safe lock takes
1596 * an intermediate lock (middle_class) where this lock is
1597 * not the same as the safe lock, then the lock chain is
1598 * used to describe the problem. Otherwise we would need
1599 * to show a different CPU case for each link in the chain
1600 * from the safe_class lock to the unsafe_class lock.
1601 */
1602 if (parent != source) {
1603 printk("Chain exists of:\n ");
1604 __print_lock_name(source);
1605 printk(KERN_CONT " --> ");
1606 __print_lock_name(parent);
1607 printk(KERN_CONT " --> ");
1608 __print_lock_name(target);
1609 printk(KERN_CONT "\n\n");
1610 }
1611
1612 printk(" Possible unsafe locking scenario:\n\n");
1613 printk(" CPU0 CPU1\n");
1614 printk(" ---- ----\n");
1615 printk(" lock(");
1616 __print_lock_name(target);
1617 printk(KERN_CONT ");\n");
1618 printk(" lock(");
1619 __print_lock_name(parent);
1620 printk(KERN_CONT ");\n");
1621 printk(" lock(");
1622 __print_lock_name(target);
1623 printk(KERN_CONT ");\n");
1624 printk(" lock(");
1625 __print_lock_name(source);
1626 printk(KERN_CONT ");\n");
1627 printk("\n *** DEADLOCK ***\n\n");
1628}
1629
1630/*
1631 * When a circular dependency is detected, print the
1632 * header first:
1633 */
1634static noinline void
1635print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1636 struct held_lock *check_src,
1637 struct held_lock *check_tgt)
1638{
1639 struct task_struct *curr = current;
1640
1641 if (debug_locks_silent)
1642 return;
1643
1644 pr_warn("\n");
1645 pr_warn("======================================================\n");
1646 pr_warn("WARNING: possible circular locking dependency detected\n");
1647 print_kernel_ident();
1648 pr_warn("------------------------------------------------------\n");
1649 pr_warn("%s/%d is trying to acquire lock:\n",
1650 curr->comm, task_pid_nr(curr));
1651 print_lock(check_src);
1652
1653 pr_warn("\nbut task is already holding lock:\n");
1654
1655 print_lock(check_tgt);
1656 pr_warn("\nwhich lock already depends on the new lock.\n\n");
1657 pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1658
1659 print_circular_bug_entry(entry, depth);
1660}
1661
1662static inline int class_equal(struct lock_list *entry, void *data)
1663{
1664 return entry->class == data;
1665}
1666
1667static noinline void print_circular_bug(struct lock_list *this,
1668 struct lock_list *target,
1669 struct held_lock *check_src,
1670 struct held_lock *check_tgt)
1671{
1672 struct task_struct *curr = current;
1673 struct lock_list *parent;
1674 struct lock_list *first_parent;
1675 int depth;
1676
1677 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1678 return;
1679
1680 this->trace = save_trace();
1681 if (!this->trace)
1682 return;
1683
1684 depth = get_lock_depth(target);
1685
1686 print_circular_bug_header(target, depth, check_src, check_tgt);
1687
1688 parent = get_lock_parent(target);
1689 first_parent = parent;
1690
1691 while (parent) {
1692 print_circular_bug_entry(parent, --depth);
1693 parent = get_lock_parent(parent);
1694 }
1695
1696 printk("\nother info that might help us debug this:\n\n");
1697 print_circular_lock_scenario(check_src, check_tgt,
1698 first_parent);
1699
1700 lockdep_print_held_locks(curr);
1701
1702 printk("\nstack backtrace:\n");
1703 dump_stack();
1704}
1705
1706static noinline void print_bfs_bug(int ret)
1707{
1708 if (!debug_locks_off_graph_unlock())
1709 return;
1710
1711 /*
1712 * Breadth-first-search failed, graph got corrupted?
1713 */
1714 WARN(1, "lockdep bfs error:%d\n", ret);
1715}
1716
1717static int noop_count(struct lock_list *entry, void *data)
1718{
1719 (*(unsigned long *)data)++;
1720 return 0;
1721}
1722
1723static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1724{
1725 unsigned long count = 0;
1726 struct lock_list *target_entry;
1727
1728 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1729
1730 return count;
1731}
1732unsigned long lockdep_count_forward_deps(struct lock_class *class)
1733{
1734 unsigned long ret, flags;
1735 struct lock_list this;
1736
1737 this.parent = NULL;
1738 this.class = class;
1739
1740 raw_local_irq_save(flags);
1741 lockdep_lock();
1742 ret = __lockdep_count_forward_deps(&this);
1743 lockdep_unlock();
1744 raw_local_irq_restore(flags);
1745
1746 return ret;
1747}
1748
1749static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1750{
1751 unsigned long count = 0;
1752 struct lock_list *target_entry;
1753
1754 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1755
1756 return count;
1757}
1758
1759unsigned long lockdep_count_backward_deps(struct lock_class *class)
1760{
1761 unsigned long ret, flags;
1762 struct lock_list this;
1763
1764 this.parent = NULL;
1765 this.class = class;
1766
1767 raw_local_irq_save(flags);
1768 lockdep_lock();
1769 ret = __lockdep_count_backward_deps(&this);
1770 lockdep_unlock();
1771 raw_local_irq_restore(flags);
1772
1773 return ret;
1774}
1775
1776/*
1777 * Check that the dependency graph starting at <src> can lead to
1778 * <target> or not. Print an error and return 0 if it does.
1779 */
1780static noinline int
1781check_path(struct lock_class *target, struct lock_list *src_entry,
1782 struct lock_list **target_entry)
1783{
1784 int ret;
1785
1786 ret = __bfs_forwards(src_entry, (void *)target, class_equal,
1787 target_entry);
1788
1789 if (unlikely(ret < 0))
1790 print_bfs_bug(ret);
1791
1792 return ret;
1793}
1794
1795/*
1796 * Prove that the dependency graph starting at <src> can not
1797 * lead to <target>. If it can, there is a circle when adding
1798 * <target> -> <src> dependency.
1799 *
1800 * Print an error and return 0 if it does.
1801 */
1802static noinline int
1803check_noncircular(struct held_lock *src, struct held_lock *target,
1804 struct lock_trace **const trace)
1805{
1806 int ret;
1807 struct lock_list *target_entry;
1808 struct lock_list src_entry = {
1809 .class = hlock_class(src),
1810 .parent = NULL,
1811 };
1812
1813 debug_atomic_inc(nr_cyclic_checks);
1814
1815 ret = check_path(hlock_class(target), &src_entry, &target_entry);
1816
1817 if (unlikely(!ret)) {
1818 if (!*trace) {
1819 /*
1820 * If save_trace fails here, the printing might
1821 * trigger a WARN but because of the !nr_entries it
1822 * should not do bad things.
1823 */
1824 *trace = save_trace();
1825 }
1826
1827 print_circular_bug(&src_entry, target_entry, src, target);
1828 }
1829
1830 return ret;
1831}
1832
1833#ifdef CONFIG_LOCKDEP_SMALL
1834/*
1835 * Check that the dependency graph starting at <src> can lead to
1836 * <target> or not. If it can, <src> -> <target> dependency is already
1837 * in the graph.
1838 *
1839 * Print an error and return 2 if it does or 1 if it does not.
1840 */
1841static noinline int
1842check_redundant(struct held_lock *src, struct held_lock *target)
1843{
1844 int ret;
1845 struct lock_list *target_entry;
1846 struct lock_list src_entry = {
1847 .class = hlock_class(src),
1848 .parent = NULL,
1849 };
1850
1851 debug_atomic_inc(nr_redundant_checks);
1852
1853 ret = check_path(hlock_class(target), &src_entry, &target_entry);
1854
1855 if (!ret) {
1856 debug_atomic_inc(nr_redundant);
1857 ret = 2;
1858 } else if (ret < 0)
1859 ret = 0;
1860
1861 return ret;
1862}
1863#endif
1864
1865#ifdef CONFIG_TRACE_IRQFLAGS
1866
1867static inline int usage_accumulate(struct lock_list *entry, void *mask)
1868{
1869 *(unsigned long *)mask |= entry->class->usage_mask;
1870
1871 return 0;
1872}
1873
1874/*
1875 * Forwards and backwards subgraph searching, for the purposes of
1876 * proving that two subgraphs can be connected by a new dependency
1877 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1878 */
1879
1880static inline int usage_match(struct lock_list *entry, void *mask)
1881{
1882 return entry->class->usage_mask & *(unsigned long *)mask;
1883}
1884
1885/*
1886 * Find a node in the forwards-direction dependency sub-graph starting
1887 * at @root->class that matches @bit.
1888 *
1889 * Return 0 if such a node exists in the subgraph, and put that node
1890 * into *@target_entry.
1891 *
1892 * Return 1 otherwise and keep *@target_entry unchanged.
1893 * Return <0 on error.
1894 */
1895static int
1896find_usage_forwards(struct lock_list *root, unsigned long usage_mask,
1897 struct lock_list **target_entry)
1898{
1899 int result;
1900
1901 debug_atomic_inc(nr_find_usage_forwards_checks);
1902
1903 result = __bfs_forwards(root, &usage_mask, usage_match, target_entry);
1904
1905 return result;
1906}
1907
1908/*
1909 * Find a node in the backwards-direction dependency sub-graph starting
1910 * at @root->class that matches @bit.
1911 *
1912 * Return 0 if such a node exists in the subgraph, and put that node
1913 * into *@target_entry.
1914 *
1915 * Return 1 otherwise and keep *@target_entry unchanged.
1916 * Return <0 on error.
1917 */
1918static int
1919find_usage_backwards(struct lock_list *root, unsigned long usage_mask,
1920 struct lock_list **target_entry)
1921{
1922 int result;
1923
1924 debug_atomic_inc(nr_find_usage_backwards_checks);
1925
1926 result = __bfs_backwards(root, &usage_mask, usage_match, target_entry);
1927
1928 return result;
1929}
1930
1931static void print_lock_class_header(struct lock_class *class, int depth)
1932{
1933 int bit;
1934
1935 printk("%*s->", depth, "");
1936 print_lock_name(class);
1937#ifdef CONFIG_DEBUG_LOCKDEP
1938 printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
1939#endif
1940 printk(KERN_CONT " {\n");
1941
1942 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1943 if (class->usage_mask & (1 << bit)) {
1944 int len = depth;
1945
1946 len += printk("%*s %s", depth, "", usage_str[bit]);
1947 len += printk(KERN_CONT " at:\n");
1948 print_lock_trace(class->usage_traces[bit], len);
1949 }
1950 }
1951 printk("%*s }\n", depth, "");
1952
1953 printk("%*s ... key at: [<%px>] %pS\n",
1954 depth, "", class->key, class->key);
1955}
1956
1957/*
1958 * printk the shortest lock dependencies from @start to @end in reverse order:
1959 */
1960static void __used
1961print_shortest_lock_dependencies(struct lock_list *leaf,
1962 struct lock_list *root)
1963{
1964 struct lock_list *entry = leaf;
1965 int depth;
1966
1967 /*compute depth from generated tree by BFS*/
1968 depth = get_lock_depth(leaf);
1969
1970 do {
1971 print_lock_class_header(entry->class, depth);
1972 printk("%*s ... acquired at:\n", depth, "");
1973 print_lock_trace(entry->trace, 2);
1974 printk("\n");
1975
1976 if (depth == 0 && (entry != root)) {
1977 printk("lockdep:%s bad path found in chain graph\n", __func__);
1978 break;
1979 }
1980
1981 entry = get_lock_parent(entry);
1982 depth--;
1983 } while (entry && (depth >= 0));
1984}
1985
1986static void
1987print_irq_lock_scenario(struct lock_list *safe_entry,
1988 struct lock_list *unsafe_entry,
1989 struct lock_class *prev_class,
1990 struct lock_class *next_class)
1991{
1992 struct lock_class *safe_class = safe_entry->class;
1993 struct lock_class *unsafe_class = unsafe_entry->class;
1994 struct lock_class *middle_class = prev_class;
1995
1996 if (middle_class == safe_class)
1997 middle_class = next_class;
1998
1999 /*
2000 * A direct locking problem where unsafe_class lock is taken
2001 * directly by safe_class lock, then all we need to show
2002 * is the deadlock scenario, as it is obvious that the
2003 * unsafe lock is taken under the safe lock.
2004 *
2005 * But if there is a chain instead, where the safe lock takes
2006 * an intermediate lock (middle_class) where this lock is
2007 * not the same as the safe lock, then the lock chain is
2008 * used to describe the problem. Otherwise we would need
2009 * to show a different CPU case for each link in the chain
2010 * from the safe_class lock to the unsafe_class lock.
2011 */
2012 if (middle_class != unsafe_class) {
2013 printk("Chain exists of:\n ");
2014 __print_lock_name(safe_class);
2015 printk(KERN_CONT " --> ");
2016 __print_lock_name(middle_class);
2017 printk(KERN_CONT " --> ");
2018 __print_lock_name(unsafe_class);
2019 printk(KERN_CONT "\n\n");
2020 }
2021
2022 printk(" Possible interrupt unsafe locking scenario:\n\n");
2023 printk(" CPU0 CPU1\n");
2024 printk(" ---- ----\n");
2025 printk(" lock(");
2026 __print_lock_name(unsafe_class);
2027 printk(KERN_CONT ");\n");
2028 printk(" local_irq_disable();\n");
2029 printk(" lock(");
2030 __print_lock_name(safe_class);
2031 printk(KERN_CONT ");\n");
2032 printk(" lock(");
2033 __print_lock_name(middle_class);
2034 printk(KERN_CONT ");\n");
2035 printk(" <Interrupt>\n");
2036 printk(" lock(");
2037 __print_lock_name(safe_class);
2038 printk(KERN_CONT ");\n");
2039 printk("\n *** DEADLOCK ***\n\n");
2040}
2041
2042static void
2043print_bad_irq_dependency(struct task_struct *curr,
2044 struct lock_list *prev_root,
2045 struct lock_list *next_root,
2046 struct lock_list *backwards_entry,
2047 struct lock_list *forwards_entry,
2048 struct held_lock *prev,
2049 struct held_lock *next,
2050 enum lock_usage_bit bit1,
2051 enum lock_usage_bit bit2,
2052 const char *irqclass)
2053{
2054 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2055 return;
2056
2057 pr_warn("\n");
2058 pr_warn("=====================================================\n");
2059 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
2060 irqclass, irqclass);
2061 print_kernel_ident();
2062 pr_warn("-----------------------------------------------------\n");
2063 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
2064 curr->comm, task_pid_nr(curr),
2065 lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
2066 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
2067 lockdep_hardirqs_enabled(),
2068 curr->softirqs_enabled);
2069 print_lock(next);
2070
2071 pr_warn("\nand this task is already holding:\n");
2072 print_lock(prev);
2073 pr_warn("which would create a new lock dependency:\n");
2074 print_lock_name(hlock_class(prev));
2075 pr_cont(" ->");
2076 print_lock_name(hlock_class(next));
2077 pr_cont("\n");
2078
2079 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
2080 irqclass);
2081 print_lock_name(backwards_entry->class);
2082 pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
2083
2084 print_lock_trace(backwards_entry->class->usage_traces[bit1], 1);
2085
2086 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
2087 print_lock_name(forwards_entry->class);
2088 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
2089 pr_warn("...");
2090
2091 print_lock_trace(forwards_entry->class->usage_traces[bit2], 1);
2092
2093 pr_warn("\nother info that might help us debug this:\n\n");
2094 print_irq_lock_scenario(backwards_entry, forwards_entry,
2095 hlock_class(prev), hlock_class(next));
2096
2097 lockdep_print_held_locks(curr);
2098
2099 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
2100 prev_root->trace = save_trace();
2101 if (!prev_root->trace)
2102 return;
2103 print_shortest_lock_dependencies(backwards_entry, prev_root);
2104
2105 pr_warn("\nthe dependencies between the lock to be acquired");
2106 pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
2107 next_root->trace = save_trace();
2108 if (!next_root->trace)
2109 return;
2110 print_shortest_lock_dependencies(forwards_entry, next_root);
2111
2112 pr_warn("\nstack backtrace:\n");
2113 dump_stack();
2114}
2115
2116static const char *state_names[] = {
2117#define LOCKDEP_STATE(__STATE) \
2118 __stringify(__STATE),
2119#include "lockdep_states.h"
2120#undef LOCKDEP_STATE
2121};
2122
2123static const char *state_rnames[] = {
2124#define LOCKDEP_STATE(__STATE) \
2125 __stringify(__STATE)"-READ",
2126#include "lockdep_states.h"
2127#undef LOCKDEP_STATE
2128};
2129
2130static inline const char *state_name(enum lock_usage_bit bit)
2131{
2132 if (bit & LOCK_USAGE_READ_MASK)
2133 return state_rnames[bit >> LOCK_USAGE_DIR_MASK];
2134 else
2135 return state_names[bit >> LOCK_USAGE_DIR_MASK];
2136}
2137
2138/*
2139 * The bit number is encoded like:
2140 *
2141 * bit0: 0 exclusive, 1 read lock
2142 * bit1: 0 used in irq, 1 irq enabled
2143 * bit2-n: state
2144 */
2145static int exclusive_bit(int new_bit)
2146{
2147 int state = new_bit & LOCK_USAGE_STATE_MASK;
2148 int dir = new_bit & LOCK_USAGE_DIR_MASK;
2149
2150 /*
2151 * keep state, bit flip the direction and strip read.
2152 */
2153 return state | (dir ^ LOCK_USAGE_DIR_MASK);
2154}
2155
2156/*
2157 * Observe that when given a bitmask where each bitnr is encoded as above, a
2158 * right shift of the mask transforms the individual bitnrs as -1 and
2159 * conversely, a left shift transforms into +1 for the individual bitnrs.
2160 *
2161 * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can
2162 * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0)
2163 * instead by subtracting the bit number by 2, or shifting the mask right by 2.
2164 *
2165 * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2.
2166 *
2167 * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is
2168 * all bits set) and recompose with bitnr1 flipped.
2169 */
2170static unsigned long invert_dir_mask(unsigned long mask)
2171{
2172 unsigned long excl = 0;
2173
2174 /* Invert dir */
2175 excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK;
2176 excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK;
2177
2178 return excl;
2179}
2180
2181/*
2182 * As above, we clear bitnr0 (LOCK_*_READ off) with bitmask ops. First, for all
2183 * bits with bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*).
2184 * And then mask out all bitnr0.
2185 */
2186static unsigned long exclusive_mask(unsigned long mask)
2187{
2188 unsigned long excl = invert_dir_mask(mask);
2189
2190 /* Strip read */
2191 excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
2192 excl &= ~LOCKF_IRQ_READ;
2193
2194 return excl;
2195}
2196
2197/*
2198 * Retrieve the _possible_ original mask to which @mask is
2199 * exclusive. Ie: this is the opposite of exclusive_mask().
2200 * Note that 2 possible original bits can match an exclusive
2201 * bit: one has LOCK_USAGE_READ_MASK set, the other has it
2202 * cleared. So both are returned for each exclusive bit.
2203 */
2204static unsigned long original_mask(unsigned long mask)
2205{
2206 unsigned long excl = invert_dir_mask(mask);
2207
2208 /* Include read in existing usages */
2209 excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
2210
2211 return excl;
2212}
2213
2214/*
2215 * Find the first pair of bit match between an original
2216 * usage mask and an exclusive usage mask.
2217 */
2218static int find_exclusive_match(unsigned long mask,
2219 unsigned long excl_mask,
2220 enum lock_usage_bit *bitp,
2221 enum lock_usage_bit *excl_bitp)
2222{
2223 int bit, excl;
2224
2225 for_each_set_bit(bit, &mask, LOCK_USED) {
2226 excl = exclusive_bit(bit);
2227 if (excl_mask & lock_flag(excl)) {
2228 *bitp = bit;
2229 *excl_bitp = excl;
2230 return 0;
2231 }
2232 }
2233 return -1;
2234}
2235
2236/*
2237 * Prove that the new dependency does not connect a hardirq-safe(-read)
2238 * lock with a hardirq-unsafe lock - to achieve this we search
2239 * the backwards-subgraph starting at <prev>, and the
2240 * forwards-subgraph starting at <next>:
2241 */
2242static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
2243 struct held_lock *next)
2244{
2245 unsigned long usage_mask = 0, forward_mask, backward_mask;
2246 enum lock_usage_bit forward_bit = 0, backward_bit = 0;
2247 struct lock_list *target_entry1;
2248 struct lock_list *target_entry;
2249 struct lock_list this, that;
2250 int ret;
2251
2252 /*
2253 * Step 1: gather all hard/soft IRQs usages backward in an
2254 * accumulated usage mask.
2255 */
2256 this.parent = NULL;
2257 this.class = hlock_class(prev);
2258
2259 ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL);
2260 if (ret < 0) {
2261 print_bfs_bug(ret);
2262 return 0;
2263 }
2264
2265 usage_mask &= LOCKF_USED_IN_IRQ_ALL;
2266 if (!usage_mask)
2267 return 1;
2268
2269 /*
2270 * Step 2: find exclusive uses forward that match the previous
2271 * backward accumulated mask.
2272 */
2273 forward_mask = exclusive_mask(usage_mask);
2274
2275 that.parent = NULL;
2276 that.class = hlock_class(next);
2277
2278 ret = find_usage_forwards(&that, forward_mask, &target_entry1);
2279 if (ret < 0) {
2280 print_bfs_bug(ret);
2281 return 0;
2282 }
2283 if (ret == 1)
2284 return ret;
2285
2286 /*
2287 * Step 3: we found a bad match! Now retrieve a lock from the backward
2288 * list whose usage mask matches the exclusive usage mask from the
2289 * lock found on the forward list.
2290 */
2291 backward_mask = original_mask(target_entry1->class->usage_mask);
2292
2293 ret = find_usage_backwards(&this, backward_mask, &target_entry);
2294 if (ret < 0) {
2295 print_bfs_bug(ret);
2296 return 0;
2297 }
2298 if (DEBUG_LOCKS_WARN_ON(ret == 1))
2299 return 1;
2300
2301 /*
2302 * Step 4: narrow down to a pair of incompatible usage bits
2303 * and report it.
2304 */
2305 ret = find_exclusive_match(target_entry->class->usage_mask,
2306 target_entry1->class->usage_mask,
2307 &backward_bit, &forward_bit);
2308 if (DEBUG_LOCKS_WARN_ON(ret == -1))
2309 return 1;
2310
2311 print_bad_irq_dependency(curr, &this, &that,
2312 target_entry, target_entry1,
2313 prev, next,
2314 backward_bit, forward_bit,
2315 state_name(backward_bit));
2316
2317 return 0;
2318}
2319
2320#else
2321
2322static inline int check_irq_usage(struct task_struct *curr,
2323 struct held_lock *prev, struct held_lock *next)
2324{
2325 return 1;
2326}
2327#endif /* CONFIG_TRACE_IRQFLAGS */
2328
2329static void inc_chains(int irq_context)
2330{
2331 if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
2332 nr_hardirq_chains++;
2333 else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
2334 nr_softirq_chains++;
2335 else
2336 nr_process_chains++;
2337}
2338
2339static void dec_chains(int irq_context)
2340{
2341 if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
2342 nr_hardirq_chains--;
2343 else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
2344 nr_softirq_chains--;
2345 else
2346 nr_process_chains--;
2347}
2348
2349static void
2350print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
2351{
2352 struct lock_class *next = hlock_class(nxt);
2353 struct lock_class *prev = hlock_class(prv);
2354
2355 printk(" Possible unsafe locking scenario:\n\n");
2356 printk(" CPU0\n");
2357 printk(" ----\n");
2358 printk(" lock(");
2359 __print_lock_name(prev);
2360 printk(KERN_CONT ");\n");
2361 printk(" lock(");
2362 __print_lock_name(next);
2363 printk(KERN_CONT ");\n");
2364 printk("\n *** DEADLOCK ***\n\n");
2365 printk(" May be due to missing lock nesting notation\n\n");
2366}
2367
2368static void
2369print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
2370 struct held_lock *next)
2371{
2372 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2373 return;
2374
2375 pr_warn("\n");
2376 pr_warn("============================================\n");
2377 pr_warn("WARNING: possible recursive locking detected\n");
2378 print_kernel_ident();
2379 pr_warn("--------------------------------------------\n");
2380 pr_warn("%s/%d is trying to acquire lock:\n",
2381 curr->comm, task_pid_nr(curr));
2382 print_lock(next);
2383 pr_warn("\nbut task is already holding lock:\n");
2384 print_lock(prev);
2385
2386 pr_warn("\nother info that might help us debug this:\n");
2387 print_deadlock_scenario(next, prev);
2388 lockdep_print_held_locks(curr);
2389
2390 pr_warn("\nstack backtrace:\n");
2391 dump_stack();
2392}
2393
2394/*
2395 * Check whether we are holding such a class already.
2396 *
2397 * (Note that this has to be done separately, because the graph cannot
2398 * detect such classes of deadlocks.)
2399 *
2400 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
2401 */
2402static int
2403check_deadlock(struct task_struct *curr, struct held_lock *next)
2404{
2405 struct held_lock *prev;
2406 struct held_lock *nest = NULL;
2407 int i;
2408
2409 for (i = 0; i < curr->lockdep_depth; i++) {
2410 prev = curr->held_locks + i;
2411
2412 if (prev->instance == next->nest_lock)
2413 nest = prev;
2414
2415 if (hlock_class(prev) != hlock_class(next))
2416 continue;
2417
2418 /*
2419 * Allow read-after-read recursion of the same
2420 * lock class (i.e. read_lock(lock)+read_lock(lock)):
2421 */
2422 if ((next->read == 2) && prev->read)
2423 return 2;
2424
2425 /*
2426 * We're holding the nest_lock, which serializes this lock's
2427 * nesting behaviour.
2428 */
2429 if (nest)
2430 return 2;
2431
2432 print_deadlock_bug(curr, prev, next);
2433 return 0;
2434 }
2435 return 1;
2436}
2437
2438/*
2439 * There was a chain-cache miss, and we are about to add a new dependency
2440 * to a previous lock. We validate the following rules:
2441 *
2442 * - would the adding of the <prev> -> <next> dependency create a
2443 * circular dependency in the graph? [== circular deadlock]
2444 *
2445 * - does the new prev->next dependency connect any hardirq-safe lock
2446 * (in the full backwards-subgraph starting at <prev>) with any
2447 * hardirq-unsafe lock (in the full forwards-subgraph starting at
2448 * <next>)? [== illegal lock inversion with hardirq contexts]
2449 *
2450 * - does the new prev->next dependency connect any softirq-safe lock
2451 * (in the full backwards-subgraph starting at <prev>) with any
2452 * softirq-unsafe lock (in the full forwards-subgraph starting at
2453 * <next>)? [== illegal lock inversion with softirq contexts]
2454 *
2455 * any of these scenarios could lead to a deadlock.
2456 *
2457 * Then if all the validations pass, we add the forwards and backwards
2458 * dependency.
2459 */
2460static int
2461check_prev_add(struct task_struct *curr, struct held_lock *prev,
2462 struct held_lock *next, int distance,
2463 struct lock_trace **const trace)
2464{
2465 struct lock_list *entry;
2466 int ret;
2467
2468 if (!hlock_class(prev)->key || !hlock_class(next)->key) {
2469 /*
2470 * The warning statements below may trigger a use-after-free
2471 * of the class name. It is better to trigger a use-after free
2472 * and to have the class name most of the time instead of not
2473 * having the class name available.
2474 */
2475 WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key,
2476 "Detected use-after-free of lock class %px/%s\n",
2477 hlock_class(prev),
2478 hlock_class(prev)->name);
2479 WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key,
2480 "Detected use-after-free of lock class %px/%s\n",
2481 hlock_class(next),
2482 hlock_class(next)->name);
2483 return 2;
2484 }
2485
2486 /*
2487 * Prove that the new <prev> -> <next> dependency would not
2488 * create a circular dependency in the graph. (We do this by
2489 * a breadth-first search into the graph starting at <next>,
2490 * and check whether we can reach <prev>.)
2491 *
2492 * The search is limited by the size of the circular queue (i.e.,
2493 * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes
2494 * in the graph whose neighbours are to be checked.
2495 */
2496 ret = check_noncircular(next, prev, trace);
2497 if (unlikely(ret <= 0))
2498 return 0;
2499
2500 if (!check_irq_usage(curr, prev, next))
2501 return 0;
2502
2503 /*
2504 * For recursive read-locks we do all the dependency checks,
2505 * but we dont store read-triggered dependencies (only
2506 * write-triggered dependencies). This ensures that only the
2507 * write-side dependencies matter, and that if for example a
2508 * write-lock never takes any other locks, then the reads are
2509 * equivalent to a NOP.
2510 */
2511 if (next->read == 2 || prev->read == 2)
2512 return 1;
2513 /*
2514 * Is the <prev> -> <next> dependency already present?
2515 *
2516 * (this may occur even though this is a new chain: consider
2517 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
2518 * chains - the second one will be new, but L1 already has
2519 * L2 added to its dependency list, due to the first chain.)
2520 */
2521 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
2522 if (entry->class == hlock_class(next)) {
2523 if (distance == 1)
2524 entry->distance = 1;
2525 return 1;
2526 }
2527 }
2528
2529#ifdef CONFIG_LOCKDEP_SMALL
2530 /*
2531 * Is the <prev> -> <next> link redundant?
2532 */
2533 ret = check_redundant(prev, next);
2534 if (ret != 1)
2535 return ret;
2536#endif
2537
2538 if (!*trace) {
2539 *trace = save_trace();
2540 if (!*trace)
2541 return 0;
2542 }
2543
2544 /*
2545 * Ok, all validations passed, add the new lock
2546 * to the previous lock's dependency list:
2547 */
2548 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
2549 &hlock_class(prev)->locks_after,
2550 next->acquire_ip, distance, *trace);
2551
2552 if (!ret)
2553 return 0;
2554
2555 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
2556 &hlock_class(next)->locks_before,
2557 next->acquire_ip, distance, *trace);
2558 if (!ret)
2559 return 0;
2560
2561 return 2;
2562}
2563
2564/*
2565 * Add the dependency to all directly-previous locks that are 'relevant'.
2566 * The ones that are relevant are (in increasing distance from curr):
2567 * all consecutive trylock entries and the final non-trylock entry - or
2568 * the end of this context's lock-chain - whichever comes first.
2569 */
2570static int
2571check_prevs_add(struct task_struct *curr, struct held_lock *next)
2572{
2573 struct lock_trace *trace = NULL;
2574 int depth = curr->lockdep_depth;
2575 struct held_lock *hlock;
2576
2577 /*
2578 * Debugging checks.
2579 *
2580 * Depth must not be zero for a non-head lock:
2581 */
2582 if (!depth)
2583 goto out_bug;
2584 /*
2585 * At least two relevant locks must exist for this
2586 * to be a head:
2587 */
2588 if (curr->held_locks[depth].irq_context !=
2589 curr->held_locks[depth-1].irq_context)
2590 goto out_bug;
2591
2592 for (;;) {
2593 int distance = curr->lockdep_depth - depth + 1;
2594 hlock = curr->held_locks + depth - 1;
2595
2596 /*
2597 * Only non-recursive-read entries get new dependencies
2598 * added:
2599 */
2600 if (hlock->read != 2 && hlock->check) {
2601 int ret = check_prev_add(curr, hlock, next, distance,
2602 &trace);
2603 if (!ret)
2604 return 0;
2605
2606 /*
2607 * Stop after the first non-trylock entry,
2608 * as non-trylock entries have added their
2609 * own direct dependencies already, so this
2610 * lock is connected to them indirectly:
2611 */
2612 if (!hlock->trylock)
2613 break;
2614 }
2615
2616 depth--;
2617 /*
2618 * End of lock-stack?
2619 */
2620 if (!depth)
2621 break;
2622 /*
2623 * Stop the search if we cross into another context:
2624 */
2625 if (curr->held_locks[depth].irq_context !=
2626 curr->held_locks[depth-1].irq_context)
2627 break;
2628 }
2629 return 1;
2630out_bug:
2631 if (!debug_locks_off_graph_unlock())
2632 return 0;
2633
2634 /*
2635 * Clearly we all shouldn't be here, but since we made it we
2636 * can reliable say we messed up our state. See the above two
2637 * gotos for reasons why we could possibly end up here.
2638 */
2639 WARN_ON(1);
2640
2641 return 0;
2642}
2643
2644struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
2645static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS);
2646static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
2647unsigned long nr_zapped_lock_chains;
2648unsigned int nr_free_chain_hlocks; /* Free chain_hlocks in buckets */
2649unsigned int nr_lost_chain_hlocks; /* Lost chain_hlocks */
2650unsigned int nr_large_chain_blocks; /* size > MAX_CHAIN_BUCKETS */
2651
2652/*
2653 * The first 2 chain_hlocks entries in the chain block in the bucket
2654 * list contains the following meta data:
2655 *
2656 * entry[0]:
2657 * Bit 15 - always set to 1 (it is not a class index)
2658 * Bits 0-14 - upper 15 bits of the next block index
2659 * entry[1] - lower 16 bits of next block index
2660 *
2661 * A next block index of all 1 bits means it is the end of the list.
2662 *
2663 * On the unsized bucket (bucket-0), the 3rd and 4th entries contain
2664 * the chain block size:
2665 *
2666 * entry[2] - upper 16 bits of the chain block size
2667 * entry[3] - lower 16 bits of the chain block size
2668 */
2669#define MAX_CHAIN_BUCKETS 16
2670#define CHAIN_BLK_FLAG (1U << 15)
2671#define CHAIN_BLK_LIST_END 0xFFFFU
2672
2673static int chain_block_buckets[MAX_CHAIN_BUCKETS];
2674
2675static inline int size_to_bucket(int size)
2676{
2677 if (size > MAX_CHAIN_BUCKETS)
2678 return 0;
2679
2680 return size - 1;
2681}
2682
2683/*
2684 * Iterate all the chain blocks in a bucket.
2685 */
2686#define for_each_chain_block(bucket, prev, curr) \
2687 for ((prev) = -1, (curr) = chain_block_buckets[bucket]; \
2688 (curr) >= 0; \
2689 (prev) = (curr), (curr) = chain_block_next(curr))
2690
2691/*
2692 * next block or -1
2693 */
2694static inline int chain_block_next(int offset)
2695{
2696 int next = chain_hlocks[offset];
2697
2698 WARN_ON_ONCE(!(next & CHAIN_BLK_FLAG));
2699
2700 if (next == CHAIN_BLK_LIST_END)
2701 return -1;
2702
2703 next &= ~CHAIN_BLK_FLAG;
2704 next <<= 16;
2705 next |= chain_hlocks[offset + 1];
2706
2707 return next;
2708}
2709
2710/*
2711 * bucket-0 only
2712 */
2713static inline int chain_block_size(int offset)
2714{
2715 return (chain_hlocks[offset + 2] << 16) | chain_hlocks[offset + 3];
2716}
2717
2718static inline void init_chain_block(int offset, int next, int bucket, int size)
2719{
2720 chain_hlocks[offset] = (next >> 16) | CHAIN_BLK_FLAG;
2721 chain_hlocks[offset + 1] = (u16)next;
2722
2723 if (size && !bucket) {
2724 chain_hlocks[offset + 2] = size >> 16;
2725 chain_hlocks[offset + 3] = (u16)size;
2726 }
2727}
2728
2729static inline void add_chain_block(int offset, int size)
2730{
2731 int bucket = size_to_bucket(size);
2732 int next = chain_block_buckets[bucket];
2733 int prev, curr;
2734
2735 if (unlikely(size < 2)) {
2736 /*
2737 * We can't store single entries on the freelist. Leak them.
2738 *
2739 * One possible way out would be to uniquely mark them, other
2740 * than with CHAIN_BLK_FLAG, such that we can recover them when
2741 * the block before it is re-added.
2742 */
2743 if (size)
2744 nr_lost_chain_hlocks++;
2745 return;
2746 }
2747
2748 nr_free_chain_hlocks += size;
2749 if (!bucket) {
2750 nr_large_chain_blocks++;
2751
2752 /*
2753 * Variable sized, sort large to small.
2754 */
2755 for_each_chain_block(0, prev, curr) {
2756 if (size >= chain_block_size(curr))
2757 break;
2758 }
2759 init_chain_block(offset, curr, 0, size);
2760 if (prev < 0)
2761 chain_block_buckets[0] = offset;
2762 else
2763 init_chain_block(prev, offset, 0, 0);
2764 return;
2765 }
2766 /*
2767 * Fixed size, add to head.
2768 */
2769 init_chain_block(offset, next, bucket, size);
2770 chain_block_buckets[bucket] = offset;
2771}
2772
2773/*
2774 * Only the first block in the list can be deleted.
2775 *
2776 * For the variable size bucket[0], the first block (the largest one) is
2777 * returned, broken up and put back into the pool. So if a chain block of
2778 * length > MAX_CHAIN_BUCKETS is ever used and zapped, it will just be
2779 * queued up after the primordial chain block and never be used until the
2780 * hlock entries in the primordial chain block is almost used up. That
2781 * causes fragmentation and reduce allocation efficiency. That can be
2782 * monitored by looking at the "large chain blocks" number in lockdep_stats.
2783 */
2784static inline void del_chain_block(int bucket, int size, int next)
2785{
2786 nr_free_chain_hlocks -= size;
2787 chain_block_buckets[bucket] = next;
2788
2789 if (!bucket)
2790 nr_large_chain_blocks--;
2791}
2792
2793static void init_chain_block_buckets(void)
2794{
2795 int i;
2796
2797 for (i = 0; i < MAX_CHAIN_BUCKETS; i++)
2798 chain_block_buckets[i] = -1;
2799
2800 add_chain_block(0, ARRAY_SIZE(chain_hlocks));
2801}
2802
2803/*
2804 * Return offset of a chain block of the right size or -1 if not found.
2805 *
2806 * Fairly simple worst-fit allocator with the addition of a number of size
2807 * specific free lists.
2808 */
2809static int alloc_chain_hlocks(int req)
2810{
2811 int bucket, curr, size;
2812
2813 /*
2814 * We rely on the MSB to act as an escape bit to denote freelist
2815 * pointers. Make sure this bit isn't set in 'normal' class_idx usage.
2816 */
2817 BUILD_BUG_ON((MAX_LOCKDEP_KEYS-1) & CHAIN_BLK_FLAG);
2818
2819 init_data_structures_once();
2820
2821 if (nr_free_chain_hlocks < req)
2822 return -1;
2823
2824 /*
2825 * We require a minimum of 2 (u16) entries to encode a freelist
2826 * 'pointer'.
2827 */
2828 req = max(req, 2);
2829 bucket = size_to_bucket(req);
2830 curr = chain_block_buckets[bucket];
2831
2832 if (bucket) {
2833 if (curr >= 0) {
2834 del_chain_block(bucket, req, chain_block_next(curr));
2835 return curr;
2836 }
2837 /* Try bucket 0 */
2838 curr = chain_block_buckets[0];
2839 }
2840
2841 /*
2842 * The variable sized freelist is sorted by size; the first entry is
2843 * the largest. Use it if it fits.
2844 */
2845 if (curr >= 0) {
2846 size = chain_block_size(curr);
2847 if (likely(size >= req)) {
2848 del_chain_block(0, size, chain_block_next(curr));
2849 add_chain_block(curr + req, size - req);
2850 return curr;
2851 }
2852 }
2853
2854 /*
2855 * Last resort, split a block in a larger sized bucket.
2856 */
2857 for (size = MAX_CHAIN_BUCKETS; size > req; size--) {
2858 bucket = size_to_bucket(size);
2859 curr = chain_block_buckets[bucket];
2860 if (curr < 0)
2861 continue;
2862
2863 del_chain_block(bucket, size, chain_block_next(curr));
2864 add_chain_block(curr + req, size - req);
2865 return curr;
2866 }
2867
2868 return -1;
2869}
2870
2871static inline void free_chain_hlocks(int base, int size)
2872{
2873 add_chain_block(base, max(size, 2));
2874}
2875
2876struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
2877{
2878 return lock_classes + chain_hlocks[chain->base + i];
2879}
2880
2881/*
2882 * Returns the index of the first held_lock of the current chain
2883 */
2884static inline int get_first_held_lock(struct task_struct *curr,
2885 struct held_lock *hlock)
2886{
2887 int i;
2888 struct held_lock *hlock_curr;
2889
2890 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2891 hlock_curr = curr->held_locks + i;
2892 if (hlock_curr->irq_context != hlock->irq_context)
2893 break;
2894
2895 }
2896
2897 return ++i;
2898}
2899
2900#ifdef CONFIG_DEBUG_LOCKDEP
2901/*
2902 * Returns the next chain_key iteration
2903 */
2904static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2905{
2906 u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2907
2908 printk(" class_idx:%d -> chain_key:%016Lx",
2909 class_idx,
2910 (unsigned long long)new_chain_key);
2911 return new_chain_key;
2912}
2913
2914static void
2915print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2916{
2917 struct held_lock *hlock;
2918 u64 chain_key = INITIAL_CHAIN_KEY;
2919 int depth = curr->lockdep_depth;
2920 int i = get_first_held_lock(curr, hlock_next);
2921
2922 printk("depth: %u (irq_context %u)\n", depth - i + 1,
2923 hlock_next->irq_context);
2924 for (; i < depth; i++) {
2925 hlock = curr->held_locks + i;
2926 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2927
2928 print_lock(hlock);
2929 }
2930
2931 print_chain_key_iteration(hlock_next->class_idx, chain_key);
2932 print_lock(hlock_next);
2933}
2934
2935static void print_chain_keys_chain(struct lock_chain *chain)
2936{
2937 int i;
2938 u64 chain_key = INITIAL_CHAIN_KEY;
2939 int class_id;
2940
2941 printk("depth: %u\n", chain->depth);
2942 for (i = 0; i < chain->depth; i++) {
2943 class_id = chain_hlocks[chain->base + i];
2944 chain_key = print_chain_key_iteration(class_id, chain_key);
2945
2946 print_lock_name(lock_classes + class_id);
2947 printk("\n");
2948 }
2949}
2950
2951static void print_collision(struct task_struct *curr,
2952 struct held_lock *hlock_next,
2953 struct lock_chain *chain)
2954{
2955 pr_warn("\n");
2956 pr_warn("============================\n");
2957 pr_warn("WARNING: chain_key collision\n");
2958 print_kernel_ident();
2959 pr_warn("----------------------------\n");
2960 pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
2961 pr_warn("Hash chain already cached but the contents don't match!\n");
2962
2963 pr_warn("Held locks:");
2964 print_chain_keys_held_locks(curr, hlock_next);
2965
2966 pr_warn("Locks in cached chain:");
2967 print_chain_keys_chain(chain);
2968
2969 pr_warn("\nstack backtrace:\n");
2970 dump_stack();
2971}
2972#endif
2973
2974/*
2975 * Checks whether the chain and the current held locks are consistent
2976 * in depth and also in content. If they are not it most likely means
2977 * that there was a collision during the calculation of the chain_key.
2978 * Returns: 0 not passed, 1 passed
2979 */
2980static int check_no_collision(struct task_struct *curr,
2981 struct held_lock *hlock,
2982 struct lock_chain *chain)
2983{
2984#ifdef CONFIG_DEBUG_LOCKDEP
2985 int i, j, id;
2986
2987 i = get_first_held_lock(curr, hlock);
2988
2989 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2990 print_collision(curr, hlock, chain);
2991 return 0;
2992 }
2993
2994 for (j = 0; j < chain->depth - 1; j++, i++) {
2995 id = curr->held_locks[i].class_idx;
2996
2997 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2998 print_collision(curr, hlock, chain);
2999 return 0;
3000 }
3001 }
3002#endif
3003 return 1;
3004}
3005
3006/*
3007 * Given an index that is >= -1, return the index of the next lock chain.
3008 * Return -2 if there is no next lock chain.
3009 */
3010long lockdep_next_lockchain(long i)
3011{
3012 i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1);
3013 return i < ARRAY_SIZE(lock_chains) ? i : -2;
3014}
3015
3016unsigned long lock_chain_count(void)
3017{
3018 return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains));
3019}
3020
3021/* Must be called with the graph lock held. */
3022static struct lock_chain *alloc_lock_chain(void)
3023{
3024 int idx = find_first_zero_bit(lock_chains_in_use,
3025 ARRAY_SIZE(lock_chains));
3026
3027 if (unlikely(idx >= ARRAY_SIZE(lock_chains)))
3028 return NULL;
3029 __set_bit(idx, lock_chains_in_use);
3030 return lock_chains + idx;
3031}
3032
3033/*
3034 * Adds a dependency chain into chain hashtable. And must be called with
3035 * graph_lock held.
3036 *
3037 * Return 0 if fail, and graph_lock is released.
3038 * Return 1 if succeed, with graph_lock held.
3039 */
3040static inline int add_chain_cache(struct task_struct *curr,
3041 struct held_lock *hlock,
3042 u64 chain_key)
3043{
3044 struct lock_class *class = hlock_class(hlock);
3045 struct hlist_head *hash_head = chainhashentry(chain_key);
3046 struct lock_chain *chain;
3047 int i, j;
3048
3049 /*
3050 * The caller must hold the graph lock, ensure we've got IRQs
3051 * disabled to make this an IRQ-safe lock.. for recursion reasons
3052 * lockdep won't complain about its own locking errors.
3053 */
3054 if (lockdep_assert_locked())
3055 return 0;
3056
3057 chain = alloc_lock_chain();
3058 if (!chain) {
3059 if (!debug_locks_off_graph_unlock())
3060 return 0;
3061
3062 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
3063 dump_stack();
3064 return 0;
3065 }
3066 chain->chain_key = chain_key;
3067 chain->irq_context = hlock->irq_context;
3068 i = get_first_held_lock(curr, hlock);
3069 chain->depth = curr->lockdep_depth + 1 - i;
3070
3071 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
3072 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
3073 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
3074
3075 j = alloc_chain_hlocks(chain->depth);
3076 if (j < 0) {
3077 if (!debug_locks_off_graph_unlock())
3078 return 0;
3079
3080 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
3081 dump_stack();
3082 return 0;
3083 }
3084
3085 chain->base = j;
3086 for (j = 0; j < chain->depth - 1; j++, i++) {
3087 int lock_id = curr->held_locks[i].class_idx;
3088
3089 chain_hlocks[chain->base + j] = lock_id;
3090 }
3091 chain_hlocks[chain->base + j] = class - lock_classes;
3092 hlist_add_head_rcu(&chain->entry, hash_head);
3093 debug_atomic_inc(chain_lookup_misses);
3094 inc_chains(chain->irq_context);
3095
3096 return 1;
3097}
3098
3099/*
3100 * Look up a dependency chain. Must be called with either the graph lock or
3101 * the RCU read lock held.
3102 */
3103static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
3104{
3105 struct hlist_head *hash_head = chainhashentry(chain_key);
3106 struct lock_chain *chain;
3107
3108 hlist_for_each_entry_rcu(chain, hash_head, entry) {
3109 if (READ_ONCE(chain->chain_key) == chain_key) {
3110 debug_atomic_inc(chain_lookup_hits);
3111 return chain;
3112 }
3113 }
3114 return NULL;
3115}
3116
3117/*
3118 * If the key is not present yet in dependency chain cache then
3119 * add it and return 1 - in this case the new dependency chain is
3120 * validated. If the key is already hashed, return 0.
3121 * (On return with 1 graph_lock is held.)
3122 */
3123static inline int lookup_chain_cache_add(struct task_struct *curr,
3124 struct held_lock *hlock,
3125 u64 chain_key)
3126{
3127 struct lock_class *class = hlock_class(hlock);
3128 struct lock_chain *chain = lookup_chain_cache(chain_key);
3129
3130 if (chain) {
3131cache_hit:
3132 if (!check_no_collision(curr, hlock, chain))
3133 return 0;
3134
3135 if (very_verbose(class)) {
3136 printk("\nhash chain already cached, key: "
3137 "%016Lx tail class: [%px] %s\n",
3138 (unsigned long long)chain_key,
3139 class->key, class->name);
3140 }
3141
3142 return 0;
3143 }
3144
3145 if (very_verbose(class)) {
3146 printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
3147 (unsigned long long)chain_key, class->key, class->name);
3148 }
3149
3150 if (!graph_lock())
3151 return 0;
3152
3153 /*
3154 * We have to walk the chain again locked - to avoid duplicates:
3155 */
3156 chain = lookup_chain_cache(chain_key);
3157 if (chain) {
3158 graph_unlock();
3159 goto cache_hit;
3160 }
3161
3162 if (!add_chain_cache(curr, hlock, chain_key))
3163 return 0;
3164
3165 return 1;
3166}
3167
3168static int validate_chain(struct task_struct *curr,
3169 struct held_lock *hlock,
3170 int chain_head, u64 chain_key)
3171{
3172 /*
3173 * Trylock needs to maintain the stack of held locks, but it
3174 * does not add new dependencies, because trylock can be done
3175 * in any order.
3176 *
3177 * We look up the chain_key and do the O(N^2) check and update of
3178 * the dependencies only if this is a new dependency chain.
3179 * (If lookup_chain_cache_add() return with 1 it acquires
3180 * graph_lock for us)
3181 */
3182 if (!hlock->trylock && hlock->check &&
3183 lookup_chain_cache_add(curr, hlock, chain_key)) {
3184 /*
3185 * Check whether last held lock:
3186 *
3187 * - is irq-safe, if this lock is irq-unsafe
3188 * - is softirq-safe, if this lock is hardirq-unsafe
3189 *
3190 * And check whether the new lock's dependency graph
3191 * could lead back to the previous lock:
3192 *
3193 * - within the current held-lock stack
3194 * - across our accumulated lock dependency records
3195 *
3196 * any of these scenarios could lead to a deadlock.
3197 */
3198 /*
3199 * The simple case: does the current hold the same lock
3200 * already?
3201 */
3202 int ret = check_deadlock(curr, hlock);
3203
3204 if (!ret)
3205 return 0;
3206 /*
3207 * Mark recursive read, as we jump over it when
3208 * building dependencies (just like we jump over
3209 * trylock entries):
3210 */
3211 if (ret == 2)
3212 hlock->read = 2;
3213 /*
3214 * Add dependency only if this lock is not the head
3215 * of the chain, and if it's not a secondary read-lock:
3216 */
3217 if (!chain_head && ret != 2) {
3218 if (!check_prevs_add(curr, hlock))
3219 return 0;
3220 }
3221
3222 graph_unlock();
3223 } else {
3224 /* after lookup_chain_cache_add(): */
3225 if (unlikely(!debug_locks))
3226 return 0;
3227 }
3228
3229 return 1;
3230}
3231#else
3232static inline int validate_chain(struct task_struct *curr,
3233 struct held_lock *hlock,
3234 int chain_head, u64 chain_key)
3235{
3236 return 1;
3237}
3238
3239static void init_chain_block_buckets(void) { }
3240#endif /* CONFIG_PROVE_LOCKING */
3241
3242/*
3243 * We are building curr_chain_key incrementally, so double-check
3244 * it from scratch, to make sure that it's done correctly:
3245 */
3246static void check_chain_key(struct task_struct *curr)
3247{
3248#ifdef CONFIG_DEBUG_LOCKDEP
3249 struct held_lock *hlock, *prev_hlock = NULL;
3250 unsigned int i;
3251 u64 chain_key = INITIAL_CHAIN_KEY;
3252
3253 for (i = 0; i < curr->lockdep_depth; i++) {
3254 hlock = curr->held_locks + i;
3255 if (chain_key != hlock->prev_chain_key) {
3256 debug_locks_off();
3257 /*
3258 * We got mighty confused, our chain keys don't match
3259 * with what we expect, someone trample on our task state?
3260 */
3261 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
3262 curr->lockdep_depth, i,
3263 (unsigned long long)chain_key,
3264 (unsigned long long)hlock->prev_chain_key);
3265 return;
3266 }
3267
3268 /*
3269 * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is
3270 * it registered lock class index?
3271 */
3272 if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use)))
3273 return;
3274
3275 if (prev_hlock && (prev_hlock->irq_context !=
3276 hlock->irq_context))
3277 chain_key = INITIAL_CHAIN_KEY;
3278 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
3279 prev_hlock = hlock;
3280 }
3281 if (chain_key != curr->curr_chain_key) {
3282 debug_locks_off();
3283 /*
3284 * More smoking hash instead of calculating it, damn see these
3285 * numbers float.. I bet that a pink elephant stepped on my memory.
3286 */
3287 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
3288 curr->lockdep_depth, i,
3289 (unsigned long long)chain_key,
3290 (unsigned long long)curr->curr_chain_key);
3291 }
3292#endif
3293}
3294
3295#ifdef CONFIG_PROVE_LOCKING
3296static int mark_lock(struct task_struct *curr, struct held_lock *this,
3297 enum lock_usage_bit new_bit);
3298
3299static void print_usage_bug_scenario(struct held_lock *lock)
3300{
3301 struct lock_class *class = hlock_class(lock);
3302
3303 printk(" Possible unsafe locking scenario:\n\n");
3304 printk(" CPU0\n");
3305 printk(" ----\n");
3306 printk(" lock(");
3307 __print_lock_name(class);
3308 printk(KERN_CONT ");\n");
3309 printk(" <Interrupt>\n");
3310 printk(" lock(");
3311 __print_lock_name(class);
3312 printk(KERN_CONT ");\n");
3313 printk("\n *** DEADLOCK ***\n\n");
3314}
3315
3316static void
3317print_usage_bug(struct task_struct *curr, struct held_lock *this,
3318 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
3319{
3320 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
3321 return;
3322
3323 pr_warn("\n");
3324 pr_warn("================================\n");
3325 pr_warn("WARNING: inconsistent lock state\n");
3326 print_kernel_ident();
3327 pr_warn("--------------------------------\n");
3328
3329 pr_warn("inconsistent {%s} -> {%s} usage.\n",
3330 usage_str[prev_bit], usage_str[new_bit]);
3331
3332 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
3333 curr->comm, task_pid_nr(curr),
3334 lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
3335 lockdep_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
3336 lockdep_hardirqs_enabled(),
3337 lockdep_softirqs_enabled(curr));
3338 print_lock(this);
3339
3340 pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
3341 print_lock_trace(hlock_class(this)->usage_traces[prev_bit], 1);
3342
3343 print_irqtrace_events(curr);
3344 pr_warn("\nother info that might help us debug this:\n");
3345 print_usage_bug_scenario(this);
3346
3347 lockdep_print_held_locks(curr);
3348
3349 pr_warn("\nstack backtrace:\n");
3350 dump_stack();
3351}
3352
3353/*
3354 * Print out an error if an invalid bit is set:
3355 */
3356static inline int
3357valid_state(struct task_struct *curr, struct held_lock *this,
3358 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
3359{
3360 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) {
3361 print_usage_bug(curr, this, bad_bit, new_bit);
3362 return 0;
3363 }
3364 return 1;
3365}
3366
3367
3368/*
3369 * print irq inversion bug:
3370 */
3371static void
3372print_irq_inversion_bug(struct task_struct *curr,
3373 struct lock_list *root, struct lock_list *other,
3374 struct held_lock *this, int forwards,
3375 const char *irqclass)
3376{
3377 struct lock_list *entry = other;
3378 struct lock_list *middle = NULL;
3379 int depth;
3380
3381 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
3382 return;
3383
3384 pr_warn("\n");
3385 pr_warn("========================================================\n");
3386 pr_warn("WARNING: possible irq lock inversion dependency detected\n");
3387 print_kernel_ident();
3388 pr_warn("--------------------------------------------------------\n");
3389 pr_warn("%s/%d just changed the state of lock:\n",
3390 curr->comm, task_pid_nr(curr));
3391 print_lock(this);
3392 if (forwards)
3393 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
3394 else
3395 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
3396 print_lock_name(other->class);
3397 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
3398
3399 pr_warn("\nother info that might help us debug this:\n");
3400
3401 /* Find a middle lock (if one exists) */
3402 depth = get_lock_depth(other);
3403 do {
3404 if (depth == 0 && (entry != root)) {
3405 pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
3406 break;
3407 }
3408 middle = entry;
3409 entry = get_lock_parent(entry);
3410 depth--;
3411 } while (entry && entry != root && (depth >= 0));
3412 if (forwards)
3413 print_irq_lock_scenario(root, other,
3414 middle ? middle->class : root->class, other->class);
3415 else
3416 print_irq_lock_scenario(other, root,
3417 middle ? middle->class : other->class, root->class);
3418
3419 lockdep_print_held_locks(curr);
3420
3421 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
3422 root->trace = save_trace();
3423 if (!root->trace)
3424 return;
3425 print_shortest_lock_dependencies(other, root);
3426
3427 pr_warn("\nstack backtrace:\n");
3428 dump_stack();
3429}
3430
3431/*
3432 * Prove that in the forwards-direction subgraph starting at <this>
3433 * there is no lock matching <mask>:
3434 */
3435static int
3436check_usage_forwards(struct task_struct *curr, struct held_lock *this,
3437 enum lock_usage_bit bit, const char *irqclass)
3438{
3439 int ret;
3440 struct lock_list root;
3441 struct lock_list *target_entry;
3442
3443 root.parent = NULL;
3444 root.class = hlock_class(this);
3445 ret = find_usage_forwards(&root, lock_flag(bit), &target_entry);
3446 if (ret < 0) {
3447 print_bfs_bug(ret);
3448 return 0;
3449 }
3450 if (ret == 1)
3451 return ret;
3452
3453 print_irq_inversion_bug(curr, &root, target_entry,
3454 this, 1, irqclass);
3455 return 0;
3456}
3457
3458/*
3459 * Prove that in the backwards-direction subgraph starting at <this>
3460 * there is no lock matching <mask>:
3461 */
3462static int
3463check_usage_backwards(struct task_struct *curr, struct held_lock *this,
3464 enum lock_usage_bit bit, const char *irqclass)
3465{
3466 int ret;
3467 struct lock_list root;
3468 struct lock_list *target_entry;
3469
3470 root.parent = NULL;
3471 root.class = hlock_class(this);
3472 ret = find_usage_backwards(&root, lock_flag(bit), &target_entry);
3473 if (ret < 0) {
3474 print_bfs_bug(ret);
3475 return 0;
3476 }
3477 if (ret == 1)
3478 return ret;
3479
3480 print_irq_inversion_bug(curr, &root, target_entry,
3481 this, 0, irqclass);
3482 return 0;
3483}
3484
3485void print_irqtrace_events(struct task_struct *curr)
3486{
3487 const struct irqtrace_events *trace = &curr->irqtrace;
3488
3489 printk("irq event stamp: %u\n", trace->irq_events);
3490 printk("hardirqs last enabled at (%u): [<%px>] %pS\n",
3491 trace->hardirq_enable_event, (void *)trace->hardirq_enable_ip,
3492 (void *)trace->hardirq_enable_ip);
3493 printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
3494 trace->hardirq_disable_event, (void *)trace->hardirq_disable_ip,
3495 (void *)trace->hardirq_disable_ip);
3496 printk("softirqs last enabled at (%u): [<%px>] %pS\n",
3497 trace->softirq_enable_event, (void *)trace->softirq_enable_ip,
3498 (void *)trace->softirq_enable_ip);
3499 printk("softirqs last disabled at (%u): [<%px>] %pS\n",
3500 trace->softirq_disable_event, (void *)trace->softirq_disable_ip,
3501 (void *)trace->softirq_disable_ip);
3502}
3503
3504static int HARDIRQ_verbose(struct lock_class *class)
3505{
3506#if HARDIRQ_VERBOSE
3507 return class_filter(class);
3508#endif
3509 return 0;
3510}
3511
3512static int SOFTIRQ_verbose(struct lock_class *class)
3513{
3514#if SOFTIRQ_VERBOSE
3515 return class_filter(class);
3516#endif
3517 return 0;
3518}
3519
3520#define STRICT_READ_CHECKS 1
3521
3522static int (*state_verbose_f[])(struct lock_class *class) = {
3523#define LOCKDEP_STATE(__STATE) \
3524 __STATE##_verbose,
3525#include "lockdep_states.h"
3526#undef LOCKDEP_STATE
3527};
3528
3529static inline int state_verbose(enum lock_usage_bit bit,
3530 struct lock_class *class)
3531{
3532 return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class);
3533}
3534
3535typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
3536 enum lock_usage_bit bit, const char *name);
3537
3538static int
3539mark_lock_irq(struct task_struct *curr, struct held_lock *this,
3540 enum lock_usage_bit new_bit)
3541{
3542 int excl_bit = exclusive_bit(new_bit);
3543 int read = new_bit & LOCK_USAGE_READ_MASK;
3544 int dir = new_bit & LOCK_USAGE_DIR_MASK;
3545
3546 /*
3547 * mark USED_IN has to look forwards -- to ensure no dependency
3548 * has ENABLED state, which would allow recursion deadlocks.
3549 *
3550 * mark ENABLED has to look backwards -- to ensure no dependee
3551 * has USED_IN state, which, again, would allow recursion deadlocks.
3552 */
3553 check_usage_f usage = dir ?
3554 check_usage_backwards : check_usage_forwards;
3555
3556 /*
3557 * Validate that this particular lock does not have conflicting
3558 * usage states.
3559 */
3560 if (!valid_state(curr, this, new_bit, excl_bit))
3561 return 0;
3562
3563 /*
3564 * Validate that the lock dependencies don't have conflicting usage
3565 * states.
3566 */
3567 if ((!read || STRICT_READ_CHECKS) &&
3568 !usage(curr, this, excl_bit, state_name(new_bit & ~LOCK_USAGE_READ_MASK)))
3569 return 0;
3570
3571 /*
3572 * Check for read in write conflicts
3573 */
3574 if (!read) {
3575 if (!valid_state(curr, this, new_bit, excl_bit + LOCK_USAGE_READ_MASK))
3576 return 0;
3577
3578 if (STRICT_READ_CHECKS &&
3579 !usage(curr, this, excl_bit + LOCK_USAGE_READ_MASK,
3580 state_name(new_bit + LOCK_USAGE_READ_MASK)))
3581 return 0;
3582 }
3583
3584 if (state_verbose(new_bit, hlock_class(this)))
3585 return 2;
3586
3587 return 1;
3588}
3589
3590/*
3591 * Mark all held locks with a usage bit:
3592 */
3593static int
3594mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit)
3595{
3596 struct held_lock *hlock;
3597 int i;
3598
3599 for (i = 0; i < curr->lockdep_depth; i++) {
3600 enum lock_usage_bit hlock_bit = base_bit;
3601 hlock = curr->held_locks + i;
3602
3603 if (hlock->read)
3604 hlock_bit += LOCK_USAGE_READ_MASK;
3605
3606 BUG_ON(hlock_bit >= LOCK_USAGE_STATES);
3607
3608 if (!hlock->check)
3609 continue;
3610
3611 if (!mark_lock(curr, hlock, hlock_bit))
3612 return 0;
3613 }
3614
3615 return 1;
3616}
3617
3618/*
3619 * Hardirqs will be enabled:
3620 */
3621static void __trace_hardirqs_on_caller(void)
3622{
3623 struct task_struct *curr = current;
3624
3625 /*
3626 * We are going to turn hardirqs on, so set the
3627 * usage bit for all held locks:
3628 */
3629 if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ))
3630 return;
3631 /*
3632 * If we have softirqs enabled, then set the usage
3633 * bit for all held locks. (disabled hardirqs prevented
3634 * this bit from being set before)
3635 */
3636 if (curr->softirqs_enabled)
3637 mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
3638}
3639
3640/**
3641 * lockdep_hardirqs_on_prepare - Prepare for enabling interrupts
3642 * @ip: Caller address
3643 *
3644 * Invoked before a possible transition to RCU idle from exit to user or
3645 * guest mode. This ensures that all RCU operations are done before RCU
3646 * stops watching. After the RCU transition lockdep_hardirqs_on() has to be
3647 * invoked to set the final state.
3648 */
3649void lockdep_hardirqs_on_prepare(unsigned long ip)
3650{
3651 if (unlikely(!debug_locks))
3652 return;
3653
3654 /*
3655 * NMIs do not (and cannot) track lock dependencies, nothing to do.
3656 */
3657 if (unlikely(in_nmi()))
3658 return;
3659
3660 if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
3661 return;
3662
3663 if (unlikely(lockdep_hardirqs_enabled())) {
3664 /*
3665 * Neither irq nor preemption are disabled here
3666 * so this is racy by nature but losing one hit
3667 * in a stat is not a big deal.
3668 */
3669 __debug_atomic_inc(redundant_hardirqs_on);
3670 return;
3671 }
3672
3673 /*
3674 * We're enabling irqs and according to our state above irqs weren't
3675 * already enabled, yet we find the hardware thinks they are in fact
3676 * enabled.. someone messed up their IRQ state tracing.
3677 */
3678 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3679 return;
3680
3681 /*
3682 * See the fine text that goes along with this variable definition.
3683 */
3684 if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled))
3685 return;
3686
3687 /*
3688 * Can't allow enabling interrupts while in an interrupt handler,
3689 * that's general bad form and such. Recursion, limited stack etc..
3690 */
3691 if (DEBUG_LOCKS_WARN_ON(lockdep_hardirq_context()))
3692 return;
3693
3694 current->hardirq_chain_key = current->curr_chain_key;
3695
3696 current->lockdep_recursion++;
3697 __trace_hardirqs_on_caller();
3698 lockdep_recursion_finish();
3699}
3700EXPORT_SYMBOL_GPL(lockdep_hardirqs_on_prepare);
3701
3702void noinstr lockdep_hardirqs_on(unsigned long ip)
3703{
3704 struct irqtrace_events *trace = ¤t->irqtrace;
3705
3706 if (unlikely(!debug_locks))
3707 return;
3708
3709 /*
3710 * NMIs can happen in the middle of local_irq_{en,dis}able() where the
3711 * tracking state and hardware state are out of sync.
3712 *
3713 * NMIs must save lockdep_hardirqs_enabled() to restore IRQ state from,
3714 * and not rely on hardware state like normal interrupts.
3715 */
3716 if (unlikely(in_nmi())) {
3717 if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
3718 return;
3719
3720 /*
3721 * Skip:
3722 * - recursion check, because NMI can hit lockdep;
3723 * - hardware state check, because above;
3724 * - chain_key check, see lockdep_hardirqs_on_prepare().
3725 */
3726 goto skip_checks;
3727 }
3728
3729 if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
3730 return;
3731
3732 if (lockdep_hardirqs_enabled()) {
3733 /*
3734 * Neither irq nor preemption are disabled here
3735 * so this is racy by nature but losing one hit
3736 * in a stat is not a big deal.
3737 */
3738 __debug_atomic_inc(redundant_hardirqs_on);
3739 return;
3740 }
3741
3742 /*
3743 * We're enabling irqs and according to our state above irqs weren't
3744 * already enabled, yet we find the hardware thinks they are in fact
3745 * enabled.. someone messed up their IRQ state tracing.
3746 */
3747 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3748 return;
3749
3750 /*
3751 * Ensure the lock stack remained unchanged between
3752 * lockdep_hardirqs_on_prepare() and lockdep_hardirqs_on().
3753 */
3754 DEBUG_LOCKS_WARN_ON(current->hardirq_chain_key !=
3755 current->curr_chain_key);
3756
3757skip_checks:
3758 /* we'll do an OFF -> ON transition: */
3759 __this_cpu_write(hardirqs_enabled, 1);
3760 trace->hardirq_enable_ip = ip;
3761 trace->hardirq_enable_event = ++trace->irq_events;
3762 debug_atomic_inc(hardirqs_on_events);
3763}
3764EXPORT_SYMBOL_GPL(lockdep_hardirqs_on);
3765
3766/*
3767 * Hardirqs were disabled:
3768 */
3769void noinstr lockdep_hardirqs_off(unsigned long ip)
3770{
3771 if (unlikely(!debug_locks))
3772 return;
3773
3774 /*
3775 * Matching lockdep_hardirqs_on(), allow NMIs in the middle of lockdep;
3776 * they will restore the software state. This ensures the software
3777 * state is consistent inside NMIs as well.
3778 */
3779 if (in_nmi()) {
3780 if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
3781 return;
3782 } else if (current->lockdep_recursion & LOCKDEP_RECURSION_MASK)
3783 return;
3784
3785 /*
3786 * So we're supposed to get called after you mask local IRQs, but for
3787 * some reason the hardware doesn't quite think you did a proper job.
3788 */
3789 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3790 return;
3791
3792 if (lockdep_hardirqs_enabled()) {
3793 struct irqtrace_events *trace = ¤t->irqtrace;
3794
3795 /*
3796 * We have done an ON -> OFF transition:
3797 */
3798 __this_cpu_write(hardirqs_enabled, 0);
3799 trace->hardirq_disable_ip = ip;
3800 trace->hardirq_disable_event = ++trace->irq_events;
3801 debug_atomic_inc(hardirqs_off_events);
3802 } else {
3803 debug_atomic_inc(redundant_hardirqs_off);
3804 }
3805}
3806EXPORT_SYMBOL_GPL(lockdep_hardirqs_off);
3807
3808/*
3809 * Softirqs will be enabled:
3810 */
3811void lockdep_softirqs_on(unsigned long ip)
3812{
3813 struct irqtrace_events *trace = ¤t->irqtrace;
3814
3815 if (unlikely(!debug_locks || current->lockdep_recursion))
3816 return;
3817
3818 /*
3819 * We fancy IRQs being disabled here, see softirq.c, avoids
3820 * funny state and nesting things.
3821 */
3822 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3823 return;
3824
3825 if (current->softirqs_enabled) {
3826 debug_atomic_inc(redundant_softirqs_on);
3827 return;
3828 }
3829
3830 current->lockdep_recursion++;
3831 /*
3832 * We'll do an OFF -> ON transition:
3833 */
3834 current->softirqs_enabled = 1;
3835 trace->softirq_enable_ip = ip;
3836 trace->softirq_enable_event = ++trace->irq_events;
3837 debug_atomic_inc(softirqs_on_events);
3838 /*
3839 * We are going to turn softirqs on, so set the
3840 * usage bit for all held locks, if hardirqs are
3841 * enabled too:
3842 */
3843 if (lockdep_hardirqs_enabled())
3844 mark_held_locks(current, LOCK_ENABLED_SOFTIRQ);
3845 lockdep_recursion_finish();
3846}
3847
3848/*
3849 * Softirqs were disabled:
3850 */
3851void lockdep_softirqs_off(unsigned long ip)
3852{
3853 if (unlikely(!debug_locks || current->lockdep_recursion))
3854 return;
3855
3856 /*
3857 * We fancy IRQs being disabled here, see softirq.c
3858 */
3859 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3860 return;
3861
3862 if (current->softirqs_enabled) {
3863 struct irqtrace_events *trace = ¤t->irqtrace;
3864
3865 /*
3866 * We have done an ON -> OFF transition:
3867 */
3868 current->softirqs_enabled = 0;
3869 trace->softirq_disable_ip = ip;
3870 trace->softirq_disable_event = ++trace->irq_events;
3871 debug_atomic_inc(softirqs_off_events);
3872 /*
3873 * Whoops, we wanted softirqs off, so why aren't they?
3874 */
3875 DEBUG_LOCKS_WARN_ON(!softirq_count());
3876 } else
3877 debug_atomic_inc(redundant_softirqs_off);
3878}
3879
3880static int
3881mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
3882{
3883 if (!check)
3884 goto lock_used;
3885
3886 /*
3887 * If non-trylock use in a hardirq or softirq context, then
3888 * mark the lock as used in these contexts:
3889 */
3890 if (!hlock->trylock) {
3891 if (hlock->read) {
3892 if (lockdep_hardirq_context())
3893 if (!mark_lock(curr, hlock,
3894 LOCK_USED_IN_HARDIRQ_READ))
3895 return 0;
3896 if (curr->softirq_context)
3897 if (!mark_lock(curr, hlock,
3898 LOCK_USED_IN_SOFTIRQ_READ))
3899 return 0;
3900 } else {
3901 if (lockdep_hardirq_context())
3902 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
3903 return 0;
3904 if (curr->softirq_context)
3905 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
3906 return 0;
3907 }
3908 }
3909 if (!hlock->hardirqs_off) {
3910 if (hlock->read) {
3911 if (!mark_lock(curr, hlock,
3912 LOCK_ENABLED_HARDIRQ_READ))
3913 return 0;
3914 if (curr->softirqs_enabled)
3915 if (!mark_lock(curr, hlock,
3916 LOCK_ENABLED_SOFTIRQ_READ))
3917 return 0;
3918 } else {
3919 if (!mark_lock(curr, hlock,
3920 LOCK_ENABLED_HARDIRQ))
3921 return 0;
3922 if (curr->softirqs_enabled)
3923 if (!mark_lock(curr, hlock,
3924 LOCK_ENABLED_SOFTIRQ))
3925 return 0;
3926 }
3927 }
3928
3929lock_used:
3930 /* mark it as used: */
3931 if (!mark_lock(curr, hlock, LOCK_USED))
3932 return 0;
3933
3934 return 1;
3935}
3936
3937static inline unsigned int task_irq_context(struct task_struct *task)
3938{
3939 return LOCK_CHAIN_HARDIRQ_CONTEXT * !!lockdep_hardirq_context() +
3940 LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context;
3941}
3942
3943static int separate_irq_context(struct task_struct *curr,
3944 struct held_lock *hlock)
3945{
3946 unsigned int depth = curr->lockdep_depth;
3947
3948 /*
3949 * Keep track of points where we cross into an interrupt context:
3950 */
3951 if (depth) {
3952 struct held_lock *prev_hlock;
3953
3954 prev_hlock = curr->held_locks + depth-1;
3955 /*
3956 * If we cross into another context, reset the
3957 * hash key (this also prevents the checking and the
3958 * adding of the dependency to 'prev'):
3959 */
3960 if (prev_hlock->irq_context != hlock->irq_context)
3961 return 1;
3962 }
3963 return 0;
3964}
3965
3966/*
3967 * Mark a lock with a usage bit, and validate the state transition:
3968 */
3969static int mark_lock(struct task_struct *curr, struct held_lock *this,
3970 enum lock_usage_bit new_bit)
3971{
3972 unsigned int old_mask, new_mask, ret = 1;
3973
3974 if (new_bit >= LOCK_USAGE_STATES) {
3975 DEBUG_LOCKS_WARN_ON(1);
3976 return 0;
3977 }
3978
3979 if (new_bit == LOCK_USED && this->read)
3980 new_bit = LOCK_USED_READ;
3981
3982 new_mask = 1 << new_bit;
3983
3984 /*
3985 * If already set then do not dirty the cacheline,
3986 * nor do any checks:
3987 */
3988 if (likely(hlock_class(this)->usage_mask & new_mask))
3989 return 1;
3990
3991 if (!graph_lock())
3992 return 0;
3993 /*
3994 * Make sure we didn't race:
3995 */
3996 if (unlikely(hlock_class(this)->usage_mask & new_mask))
3997 goto unlock;
3998
3999 old_mask = hlock_class(this)->usage_mask;
4000 hlock_class(this)->usage_mask |= new_mask;
4001
4002 /*
4003 * Save one usage_traces[] entry and map both LOCK_USED and
4004 * LOCK_USED_READ onto the same entry.
4005 */
4006 if (new_bit == LOCK_USED || new_bit == LOCK_USED_READ) {
4007 if (old_mask & (LOCKF_USED | LOCKF_USED_READ))
4008 goto unlock;
4009 new_bit = LOCK_USED;
4010 }
4011
4012 if (!(hlock_class(this)->usage_traces[new_bit] = save_trace()))
4013 return 0;
4014
4015 switch (new_bit) {
4016 case LOCK_USED:
4017 debug_atomic_dec(nr_unused_locks);
4018 break;
4019 default:
4020 ret = mark_lock_irq(curr, this, new_bit);
4021 if (!ret)
4022 return 0;
4023 }
4024
4025unlock:
4026 graph_unlock();
4027
4028 /*
4029 * We must printk outside of the graph_lock:
4030 */
4031 if (ret == 2) {
4032 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
4033 print_lock(this);
4034 print_irqtrace_events(curr);
4035 dump_stack();
4036 }
4037
4038 return ret;
4039}
4040
4041static inline short task_wait_context(struct task_struct *curr)
4042{
4043 /*
4044 * Set appropriate wait type for the context; for IRQs we have to take
4045 * into account force_irqthread as that is implied by PREEMPT_RT.
4046 */
4047 if (lockdep_hardirq_context()) {
4048 /*
4049 * Check if force_irqthreads will run us threaded.
4050 */
4051 if (curr->hardirq_threaded || curr->irq_config)
4052 return LD_WAIT_CONFIG;
4053
4054 return LD_WAIT_SPIN;
4055 } else if (curr->softirq_context) {
4056 /*
4057 * Softirqs are always threaded.
4058 */
4059 return LD_WAIT_CONFIG;
4060 }
4061
4062 return LD_WAIT_MAX;
4063}
4064
4065static int
4066print_lock_invalid_wait_context(struct task_struct *curr,
4067 struct held_lock *hlock)
4068{
4069 short curr_inner;
4070
4071 if (!debug_locks_off())
4072 return 0;
4073 if (debug_locks_silent)
4074 return 0;
4075
4076 pr_warn("\n");
4077 pr_warn("=============================\n");
4078 pr_warn("[ BUG: Invalid wait context ]\n");
4079 print_kernel_ident();
4080 pr_warn("-----------------------------\n");
4081
4082 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
4083 print_lock(hlock);
4084
4085 pr_warn("other info that might help us debug this:\n");
4086
4087 curr_inner = task_wait_context(curr);
4088 pr_warn("context-{%d:%d}\n", curr_inner, curr_inner);
4089
4090 lockdep_print_held_locks(curr);
4091
4092 pr_warn("stack backtrace:\n");
4093 dump_stack();
4094
4095 return 0;
4096}
4097
4098/*
4099 * Verify the wait_type context.
4100 *
4101 * This check validates we takes locks in the right wait-type order; that is it
4102 * ensures that we do not take mutexes inside spinlocks and do not attempt to
4103 * acquire spinlocks inside raw_spinlocks and the sort.
4104 *
4105 * The entire thing is slightly more complex because of RCU, RCU is a lock that
4106 * can be taken from (pretty much) any context but also has constraints.
4107 * However when taken in a stricter environment the RCU lock does not loosen
4108 * the constraints.
4109 *
4110 * Therefore we must look for the strictest environment in the lock stack and
4111 * compare that to the lock we're trying to acquire.
4112 */
4113static int check_wait_context(struct task_struct *curr, struct held_lock *next)
4114{
4115 short next_inner = hlock_class(next)->wait_type_inner;
4116 short next_outer = hlock_class(next)->wait_type_outer;
4117 short curr_inner;
4118 int depth;
4119
4120 if (!curr->lockdep_depth || !next_inner || next->trylock)
4121 return 0;
4122
4123 if (!next_outer)
4124 next_outer = next_inner;
4125
4126 /*
4127 * Find start of current irq_context..
4128 */
4129 for (depth = curr->lockdep_depth - 1; depth >= 0; depth--) {
4130 struct held_lock *prev = curr->held_locks + depth;
4131 if (prev->irq_context != next->irq_context)
4132 break;
4133 }
4134 depth++;
4135
4136 curr_inner = task_wait_context(curr);
4137
4138 for (; depth < curr->lockdep_depth; depth++) {
4139 struct held_lock *prev = curr->held_locks + depth;
4140 short prev_inner = hlock_class(prev)->wait_type_inner;
4141
4142 if (prev_inner) {
4143 /*
4144 * We can have a bigger inner than a previous one
4145 * when outer is smaller than inner, as with RCU.
4146 *
4147 * Also due to trylocks.
4148 */
4149 curr_inner = min(curr_inner, prev_inner);
4150 }
4151 }
4152
4153 if (next_outer > curr_inner)
4154 return print_lock_invalid_wait_context(curr, next);
4155
4156 return 0;
4157}
4158
4159#else /* CONFIG_PROVE_LOCKING */
4160
4161static inline int
4162mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
4163{
4164 return 1;
4165}
4166
4167static inline unsigned int task_irq_context(struct task_struct *task)
4168{
4169 return 0;
4170}
4171
4172static inline int separate_irq_context(struct task_struct *curr,
4173 struct held_lock *hlock)
4174{
4175 return 0;
4176}
4177
4178static inline int check_wait_context(struct task_struct *curr,
4179 struct held_lock *next)
4180{
4181 return 0;
4182}
4183
4184#endif /* CONFIG_PROVE_LOCKING */
4185
4186/*
4187 * Initialize a lock instance's lock-class mapping info:
4188 */
4189void lockdep_init_map_waits(struct lockdep_map *lock, const char *name,
4190 struct lock_class_key *key, int subclass,
4191 short inner, short outer)
4192{
4193 int i;
4194
4195 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
4196 lock->class_cache[i] = NULL;
4197
4198#ifdef CONFIG_LOCK_STAT
4199 lock->cpu = raw_smp_processor_id();
4200#endif
4201
4202 /*
4203 * Can't be having no nameless bastards around this place!
4204 */
4205 if (DEBUG_LOCKS_WARN_ON(!name)) {
4206 lock->name = "NULL";
4207 return;
4208 }
4209
4210 lock->name = name;
4211
4212 lock->wait_type_outer = outer;
4213 lock->wait_type_inner = inner;
4214
4215 /*
4216 * No key, no joy, we need to hash something.
4217 */
4218 if (DEBUG_LOCKS_WARN_ON(!key))
4219 return;
4220 /*
4221 * Sanity check, the lock-class key must either have been allocated
4222 * statically or must have been registered as a dynamic key.
4223 */
4224 if (!static_obj(key) && !is_dynamic_key(key)) {
4225 if (debug_locks)
4226 printk(KERN_ERR "BUG: key %px has not been registered!\n", key);
4227 DEBUG_LOCKS_WARN_ON(1);
4228 return;
4229 }
4230 lock->key = key;
4231
4232 if (unlikely(!debug_locks))
4233 return;
4234
4235 if (subclass) {
4236 unsigned long flags;
4237
4238 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
4239 return;
4240
4241 raw_local_irq_save(flags);
4242 current->lockdep_recursion++;
4243 register_lock_class(lock, subclass, 1);
4244 lockdep_recursion_finish();
4245 raw_local_irq_restore(flags);
4246 }
4247}
4248EXPORT_SYMBOL_GPL(lockdep_init_map_waits);
4249
4250struct lock_class_key __lockdep_no_validate__;
4251EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
4252
4253static void
4254print_lock_nested_lock_not_held(struct task_struct *curr,
4255 struct held_lock *hlock,
4256 unsigned long ip)
4257{
4258 if (!debug_locks_off())
4259 return;
4260 if (debug_locks_silent)
4261 return;
4262
4263 pr_warn("\n");
4264 pr_warn("==================================\n");
4265 pr_warn("WARNING: Nested lock was not taken\n");
4266 print_kernel_ident();
4267 pr_warn("----------------------------------\n");
4268
4269 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
4270 print_lock(hlock);
4271
4272 pr_warn("\nbut this task is not holding:\n");
4273 pr_warn("%s\n", hlock->nest_lock->name);
4274
4275 pr_warn("\nstack backtrace:\n");
4276 dump_stack();
4277
4278 pr_warn("\nother info that might help us debug this:\n");
4279 lockdep_print_held_locks(curr);
4280
4281 pr_warn("\nstack backtrace:\n");
4282 dump_stack();
4283}
4284
4285static int __lock_is_held(const struct lockdep_map *lock, int read);
4286
4287/*
4288 * This gets called for every mutex_lock*()/spin_lock*() operation.
4289 * We maintain the dependency maps and validate the locking attempt:
4290 *
4291 * The callers must make sure that IRQs are disabled before calling it,
4292 * otherwise we could get an interrupt which would want to take locks,
4293 * which would end up in lockdep again.
4294 */
4295static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
4296 int trylock, int read, int check, int hardirqs_off,
4297 struct lockdep_map *nest_lock, unsigned long ip,
4298 int references, int pin_count)
4299{
4300 struct task_struct *curr = current;
4301 struct lock_class *class = NULL;
4302 struct held_lock *hlock;
4303 unsigned int depth;
4304 int chain_head = 0;
4305 int class_idx;
4306 u64 chain_key;
4307
4308 if (unlikely(!debug_locks))
4309 return 0;
4310
4311 if (!prove_locking || lock->key == &__lockdep_no_validate__)
4312 check = 0;
4313
4314 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
4315 class = lock->class_cache[subclass];
4316 /*
4317 * Not cached?
4318 */
4319 if (unlikely(!class)) {
4320 class = register_lock_class(lock, subclass, 0);
4321 if (!class)
4322 return 0;
4323 }
4324
4325 debug_class_ops_inc(class);
4326
4327 if (very_verbose(class)) {
4328 printk("\nacquire class [%px] %s", class->key, class->name);
4329 if (class->name_version > 1)
4330 printk(KERN_CONT "#%d", class->name_version);
4331 printk(KERN_CONT "\n");
4332 dump_stack();
4333 }
4334
4335 /*
4336 * Add the lock to the list of currently held locks.
4337 * (we dont increase the depth just yet, up until the
4338 * dependency checks are done)
4339 */
4340 depth = curr->lockdep_depth;
4341 /*
4342 * Ran out of static storage for our per-task lock stack again have we?
4343 */
4344 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
4345 return 0;
4346
4347 class_idx = class - lock_classes;
4348
4349 if (depth) { /* we're holding locks */
4350 hlock = curr->held_locks + depth - 1;
4351 if (hlock->class_idx == class_idx && nest_lock) {
4352 if (!references)
4353 references++;
4354
4355 if (!hlock->references)
4356 hlock->references++;
4357
4358 hlock->references += references;
4359
4360 /* Overflow */
4361 if (DEBUG_LOCKS_WARN_ON(hlock->references < references))
4362 return 0;
4363
4364 return 2;
4365 }
4366 }
4367
4368 hlock = curr->held_locks + depth;
4369 /*
4370 * Plain impossible, we just registered it and checked it weren't no
4371 * NULL like.. I bet this mushroom I ate was good!
4372 */
4373 if (DEBUG_LOCKS_WARN_ON(!class))
4374 return 0;
4375 hlock->class_idx = class_idx;
4376 hlock->acquire_ip = ip;
4377 hlock->instance = lock;
4378 hlock->nest_lock = nest_lock;
4379 hlock->irq_context = task_irq_context(curr);
4380 hlock->trylock = trylock;
4381 hlock->read = read;
4382 hlock->check = check;
4383 hlock->hardirqs_off = !!hardirqs_off;
4384 hlock->references = references;
4385#ifdef CONFIG_LOCK_STAT
4386 hlock->waittime_stamp = 0;
4387 hlock->holdtime_stamp = lockstat_clock();
4388#endif
4389 hlock->pin_count = pin_count;
4390
4391 if (check_wait_context(curr, hlock))
4392 return 0;
4393
4394 /* Initialize the lock usage bit */
4395 if (!mark_usage(curr, hlock, check))
4396 return 0;
4397
4398 /*
4399 * Calculate the chain hash: it's the combined hash of all the
4400 * lock keys along the dependency chain. We save the hash value
4401 * at every step so that we can get the current hash easily
4402 * after unlock. The chain hash is then used to cache dependency
4403 * results.
4404 *
4405 * The 'key ID' is what is the most compact key value to drive
4406 * the hash, not class->key.
4407 */
4408 /*
4409 * Whoops, we did it again.. class_idx is invalid.
4410 */
4411 if (DEBUG_LOCKS_WARN_ON(!test_bit(class_idx, lock_classes_in_use)))
4412 return 0;
4413
4414 chain_key = curr->curr_chain_key;
4415 if (!depth) {
4416 /*
4417 * How can we have a chain hash when we ain't got no keys?!
4418 */
4419 if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY))
4420 return 0;
4421 chain_head = 1;
4422 }
4423
4424 hlock->prev_chain_key = chain_key;
4425 if (separate_irq_context(curr, hlock)) {
4426 chain_key = INITIAL_CHAIN_KEY;
4427 chain_head = 1;
4428 }
4429 chain_key = iterate_chain_key(chain_key, class_idx);
4430
4431 if (nest_lock && !__lock_is_held(nest_lock, -1)) {
4432 print_lock_nested_lock_not_held(curr, hlock, ip);
4433 return 0;
4434 }
4435
4436 if (!debug_locks_silent) {
4437 WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key);
4438 WARN_ON_ONCE(!hlock_class(hlock)->key);
4439 }
4440
4441 if (!validate_chain(curr, hlock, chain_head, chain_key))
4442 return 0;
4443
4444 curr->curr_chain_key = chain_key;
4445 curr->lockdep_depth++;
4446 check_chain_key(curr);
4447#ifdef CONFIG_DEBUG_LOCKDEP
4448 if (unlikely(!debug_locks))
4449 return 0;
4450#endif
4451 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
4452 debug_locks_off();
4453 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
4454 printk(KERN_DEBUG "depth: %i max: %lu!\n",
4455 curr->lockdep_depth, MAX_LOCK_DEPTH);
4456
4457 lockdep_print_held_locks(current);
4458 debug_show_all_locks();
4459 dump_stack();
4460
4461 return 0;
4462 }
4463
4464 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
4465 max_lockdep_depth = curr->lockdep_depth;
4466
4467 return 1;
4468}
4469
4470static void print_unlock_imbalance_bug(struct task_struct *curr,
4471 struct lockdep_map *lock,
4472 unsigned long ip)
4473{
4474 if (!debug_locks_off())
4475 return;
4476 if (debug_locks_silent)
4477 return;
4478
4479 pr_warn("\n");
4480 pr_warn("=====================================\n");
4481 pr_warn("WARNING: bad unlock balance detected!\n");
4482 print_kernel_ident();
4483 pr_warn("-------------------------------------\n");
4484 pr_warn("%s/%d is trying to release lock (",
4485 curr->comm, task_pid_nr(curr));
4486 print_lockdep_cache(lock);
4487 pr_cont(") at:\n");
4488 print_ip_sym(KERN_WARNING, ip);
4489 pr_warn("but there are no more locks to release!\n");
4490 pr_warn("\nother info that might help us debug this:\n");
4491 lockdep_print_held_locks(curr);
4492
4493 pr_warn("\nstack backtrace:\n");
4494 dump_stack();
4495}
4496
4497static noinstr int match_held_lock(const struct held_lock *hlock,
4498 const struct lockdep_map *lock)
4499{
4500 if (hlock->instance == lock)
4501 return 1;
4502
4503 if (hlock->references) {
4504 const struct lock_class *class = lock->class_cache[0];
4505
4506 if (!class)
4507 class = look_up_lock_class(lock, 0);
4508
4509 /*
4510 * If look_up_lock_class() failed to find a class, we're trying
4511 * to test if we hold a lock that has never yet been acquired.
4512 * Clearly if the lock hasn't been acquired _ever_, we're not
4513 * holding it either, so report failure.
4514 */
4515 if (!class)
4516 return 0;
4517
4518 /*
4519 * References, but not a lock we're actually ref-counting?
4520 * State got messed up, follow the sites that change ->references
4521 * and try to make sense of it.
4522 */
4523 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
4524 return 0;
4525
4526 if (hlock->class_idx == class - lock_classes)
4527 return 1;
4528 }
4529
4530 return 0;
4531}
4532
4533/* @depth must not be zero */
4534static struct held_lock *find_held_lock(struct task_struct *curr,
4535 struct lockdep_map *lock,
4536 unsigned int depth, int *idx)
4537{
4538 struct held_lock *ret, *hlock, *prev_hlock;
4539 int i;
4540
4541 i = depth - 1;
4542 hlock = curr->held_locks + i;
4543 ret = hlock;
4544 if (match_held_lock(hlock, lock))
4545 goto out;
4546
4547 ret = NULL;
4548 for (i--, prev_hlock = hlock--;
4549 i >= 0;
4550 i--, prev_hlock = hlock--) {
4551 /*
4552 * We must not cross into another context:
4553 */
4554 if (prev_hlock->irq_context != hlock->irq_context) {
4555 ret = NULL;
4556 break;
4557 }
4558 if (match_held_lock(hlock, lock)) {
4559 ret = hlock;
4560 break;
4561 }
4562 }
4563
4564out:
4565 *idx = i;
4566 return ret;
4567}
4568
4569static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
4570 int idx, unsigned int *merged)
4571{
4572 struct held_lock *hlock;
4573 int first_idx = idx;
4574
4575 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4576 return 0;
4577
4578 for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
4579 switch (__lock_acquire(hlock->instance,
4580 hlock_class(hlock)->subclass,
4581 hlock->trylock,
4582 hlock->read, hlock->check,
4583 hlock->hardirqs_off,
4584 hlock->nest_lock, hlock->acquire_ip,
4585 hlock->references, hlock->pin_count)) {
4586 case 0:
4587 return 1;
4588 case 1:
4589 break;
4590 case 2:
4591 *merged += (idx == first_idx);
4592 break;
4593 default:
4594 WARN_ON(1);
4595 return 0;
4596 }
4597 }
4598 return 0;
4599}
4600
4601static int
4602__lock_set_class(struct lockdep_map *lock, const char *name,
4603 struct lock_class_key *key, unsigned int subclass,
4604 unsigned long ip)
4605{
4606 struct task_struct *curr = current;
4607 unsigned int depth, merged = 0;
4608 struct held_lock *hlock;
4609 struct lock_class *class;
4610 int i;
4611
4612 if (unlikely(!debug_locks))
4613 return 0;
4614
4615 depth = curr->lockdep_depth;
4616 /*
4617 * This function is about (re)setting the class of a held lock,
4618 * yet we're not actually holding any locks. Naughty user!
4619 */
4620 if (DEBUG_LOCKS_WARN_ON(!depth))
4621 return 0;
4622
4623 hlock = find_held_lock(curr, lock, depth, &i);
4624 if (!hlock) {
4625 print_unlock_imbalance_bug(curr, lock, ip);
4626 return 0;
4627 }
4628
4629 lockdep_init_map_waits(lock, name, key, 0,
4630 lock->wait_type_inner,
4631 lock->wait_type_outer);
4632 class = register_lock_class(lock, subclass, 0);
4633 hlock->class_idx = class - lock_classes;
4634
4635 curr->lockdep_depth = i;
4636 curr->curr_chain_key = hlock->prev_chain_key;
4637
4638 if (reacquire_held_locks(curr, depth, i, &merged))
4639 return 0;
4640
4641 /*
4642 * I took it apart and put it back together again, except now I have
4643 * these 'spare' parts.. where shall I put them.
4644 */
4645 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged))
4646 return 0;
4647 return 1;
4648}
4649
4650static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
4651{
4652 struct task_struct *curr = current;
4653 unsigned int depth, merged = 0;
4654 struct held_lock *hlock;
4655 int i;
4656
4657 if (unlikely(!debug_locks))
4658 return 0;
4659
4660 depth = curr->lockdep_depth;
4661 /*
4662 * This function is about (re)setting the class of a held lock,
4663 * yet we're not actually holding any locks. Naughty user!
4664 */
4665 if (DEBUG_LOCKS_WARN_ON(!depth))
4666 return 0;
4667
4668 hlock = find_held_lock(curr, lock, depth, &i);
4669 if (!hlock) {
4670 print_unlock_imbalance_bug(curr, lock, ip);
4671 return 0;
4672 }
4673
4674 curr->lockdep_depth = i;
4675 curr->curr_chain_key = hlock->prev_chain_key;
4676
4677 WARN(hlock->read, "downgrading a read lock");
4678 hlock->read = 1;
4679 hlock->acquire_ip = ip;
4680
4681 if (reacquire_held_locks(curr, depth, i, &merged))
4682 return 0;
4683
4684 /* Merging can't happen with unchanged classes.. */
4685 if (DEBUG_LOCKS_WARN_ON(merged))
4686 return 0;
4687
4688 /*
4689 * I took it apart and put it back together again, except now I have
4690 * these 'spare' parts.. where shall I put them.
4691 */
4692 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
4693 return 0;
4694
4695 return 1;
4696}
4697
4698/*
4699 * Remove the lock from the list of currently held locks - this gets
4700 * called on mutex_unlock()/spin_unlock*() (or on a failed
4701 * mutex_lock_interruptible()).
4702 */
4703static int
4704__lock_release(struct lockdep_map *lock, unsigned long ip)
4705{
4706 struct task_struct *curr = current;
4707 unsigned int depth, merged = 1;
4708 struct held_lock *hlock;
4709 int i;
4710
4711 if (unlikely(!debug_locks))
4712 return 0;
4713
4714 depth = curr->lockdep_depth;
4715 /*
4716 * So we're all set to release this lock.. wait what lock? We don't
4717 * own any locks, you've been drinking again?
4718 */
4719 if (depth <= 0) {
4720 print_unlock_imbalance_bug(curr, lock, ip);
4721 return 0;
4722 }
4723
4724 /*
4725 * Check whether the lock exists in the current stack
4726 * of held locks:
4727 */
4728 hlock = find_held_lock(curr, lock, depth, &i);
4729 if (!hlock) {
4730 print_unlock_imbalance_bug(curr, lock, ip);
4731 return 0;
4732 }
4733
4734 if (hlock->instance == lock)
4735 lock_release_holdtime(hlock);
4736
4737 WARN(hlock->pin_count, "releasing a pinned lock\n");
4738
4739 if (hlock->references) {
4740 hlock->references--;
4741 if (hlock->references) {
4742 /*
4743 * We had, and after removing one, still have
4744 * references, the current lock stack is still
4745 * valid. We're done!
4746 */
4747 return 1;
4748 }
4749 }
4750
4751 /*
4752 * We have the right lock to unlock, 'hlock' points to it.
4753 * Now we remove it from the stack, and add back the other
4754 * entries (if any), recalculating the hash along the way:
4755 */
4756
4757 curr->lockdep_depth = i;
4758 curr->curr_chain_key = hlock->prev_chain_key;
4759
4760 /*
4761 * The most likely case is when the unlock is on the innermost
4762 * lock. In this case, we are done!
4763 */
4764 if (i == depth-1)
4765 return 1;
4766
4767 if (reacquire_held_locks(curr, depth, i + 1, &merged))
4768 return 0;
4769
4770 /*
4771 * We had N bottles of beer on the wall, we drank one, but now
4772 * there's not N-1 bottles of beer left on the wall...
4773 * Pouring two of the bottles together is acceptable.
4774 */
4775 DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged);
4776
4777 /*
4778 * Since reacquire_held_locks() would have called check_chain_key()
4779 * indirectly via __lock_acquire(), we don't need to do it again
4780 * on return.
4781 */
4782 return 0;
4783}
4784
4785static __always_inline
4786int __lock_is_held(const struct lockdep_map *lock, int read)
4787{
4788 struct task_struct *curr = current;
4789 int i;
4790
4791 for (i = 0; i < curr->lockdep_depth; i++) {
4792 struct held_lock *hlock = curr->held_locks + i;
4793
4794 if (match_held_lock(hlock, lock)) {
4795 if (read == -1 || hlock->read == read)
4796 return 1;
4797
4798 return 0;
4799 }
4800 }
4801
4802 return 0;
4803}
4804
4805static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
4806{
4807 struct pin_cookie cookie = NIL_COOKIE;
4808 struct task_struct *curr = current;
4809 int i;
4810
4811 if (unlikely(!debug_locks))
4812 return cookie;
4813
4814 for (i = 0; i < curr->lockdep_depth; i++) {
4815 struct held_lock *hlock = curr->held_locks + i;
4816
4817 if (match_held_lock(hlock, lock)) {
4818 /*
4819 * Grab 16bits of randomness; this is sufficient to not
4820 * be guessable and still allows some pin nesting in
4821 * our u32 pin_count.
4822 */
4823 cookie.val = 1 + (prandom_u32() >> 16);
4824 hlock->pin_count += cookie.val;
4825 return cookie;
4826 }
4827 }
4828
4829 WARN(1, "pinning an unheld lock\n");
4830 return cookie;
4831}
4832
4833static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4834{
4835 struct task_struct *curr = current;
4836 int i;
4837
4838 if (unlikely(!debug_locks))
4839 return;
4840
4841 for (i = 0; i < curr->lockdep_depth; i++) {
4842 struct held_lock *hlock = curr->held_locks + i;
4843
4844 if (match_held_lock(hlock, lock)) {
4845 hlock->pin_count += cookie.val;
4846 return;
4847 }
4848 }
4849
4850 WARN(1, "pinning an unheld lock\n");
4851}
4852
4853static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4854{
4855 struct task_struct *curr = current;
4856 int i;
4857
4858 if (unlikely(!debug_locks))
4859 return;
4860
4861 for (i = 0; i < curr->lockdep_depth; i++) {
4862 struct held_lock *hlock = curr->held_locks + i;
4863
4864 if (match_held_lock(hlock, lock)) {
4865 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
4866 return;
4867
4868 hlock->pin_count -= cookie.val;
4869
4870 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
4871 hlock->pin_count = 0;
4872
4873 return;
4874 }
4875 }
4876
4877 WARN(1, "unpinning an unheld lock\n");
4878}
4879
4880/*
4881 * Check whether we follow the irq-flags state precisely:
4882 */
4883static void check_flags(unsigned long flags)
4884{
4885#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP)
4886 if (!debug_locks)
4887 return;
4888
4889 if (irqs_disabled_flags(flags)) {
4890 if (DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())) {
4891 printk("possible reason: unannotated irqs-off.\n");
4892 }
4893 } else {
4894 if (DEBUG_LOCKS_WARN_ON(!lockdep_hardirqs_enabled())) {
4895 printk("possible reason: unannotated irqs-on.\n");
4896 }
4897 }
4898
4899 /*
4900 * We dont accurately track softirq state in e.g.
4901 * hardirq contexts (such as on 4KSTACKS), so only
4902 * check if not in hardirq contexts:
4903 */
4904 if (!hardirq_count()) {
4905 if (softirq_count()) {
4906 /* like the above, but with softirqs */
4907 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
4908 } else {
4909 /* lick the above, does it taste good? */
4910 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
4911 }
4912 }
4913
4914 if (!debug_locks)
4915 print_irqtrace_events(current);
4916#endif
4917}
4918
4919void lock_set_class(struct lockdep_map *lock, const char *name,
4920 struct lock_class_key *key, unsigned int subclass,
4921 unsigned long ip)
4922{
4923 unsigned long flags;
4924
4925 if (unlikely(current->lockdep_recursion))
4926 return;
4927
4928 raw_local_irq_save(flags);
4929 current->lockdep_recursion++;
4930 check_flags(flags);
4931 if (__lock_set_class(lock, name, key, subclass, ip))
4932 check_chain_key(current);
4933 lockdep_recursion_finish();
4934 raw_local_irq_restore(flags);
4935}
4936EXPORT_SYMBOL_GPL(lock_set_class);
4937
4938void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
4939{
4940 unsigned long flags;
4941
4942 if (unlikely(current->lockdep_recursion))
4943 return;
4944
4945 raw_local_irq_save(flags);
4946 current->lockdep_recursion++;
4947 check_flags(flags);
4948 if (__lock_downgrade(lock, ip))
4949 check_chain_key(current);
4950 lockdep_recursion_finish();
4951 raw_local_irq_restore(flags);
4952}
4953EXPORT_SYMBOL_GPL(lock_downgrade);
4954
4955/* NMI context !!! */
4956static void verify_lock_unused(struct lockdep_map *lock, struct held_lock *hlock, int subclass)
4957{
4958#ifdef CONFIG_PROVE_LOCKING
4959 struct lock_class *class = look_up_lock_class(lock, subclass);
4960 unsigned long mask = LOCKF_USED;
4961
4962 /* if it doesn't have a class (yet), it certainly hasn't been used yet */
4963 if (!class)
4964 return;
4965
4966 /*
4967 * READ locks only conflict with USED, such that if we only ever use
4968 * READ locks, there is no deadlock possible -- RCU.
4969 */
4970 if (!hlock->read)
4971 mask |= LOCKF_USED_READ;
4972
4973 if (!(class->usage_mask & mask))
4974 return;
4975
4976 hlock->class_idx = class - lock_classes;
4977
4978 print_usage_bug(current, hlock, LOCK_USED, LOCK_USAGE_STATES);
4979#endif
4980}
4981
4982static bool lockdep_nmi(void)
4983{
4984 if (current->lockdep_recursion & LOCKDEP_RECURSION_MASK)
4985 return false;
4986
4987 if (!in_nmi())
4988 return false;
4989
4990 return true;
4991}
4992
4993/*
4994 * We are not always called with irqs disabled - do that here,
4995 * and also avoid lockdep recursion:
4996 */
4997void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
4998 int trylock, int read, int check,
4999 struct lockdep_map *nest_lock, unsigned long ip)
5000{
5001 unsigned long flags;
5002
5003 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
5004
5005 if (unlikely(current->lockdep_recursion)) {
5006 /* XXX allow trylock from NMI ?!? */
5007 if (lockdep_nmi() && !trylock) {
5008 struct held_lock hlock;
5009
5010 hlock.acquire_ip = ip;
5011 hlock.instance = lock;
5012 hlock.nest_lock = nest_lock;
5013 hlock.irq_context = 2; // XXX
5014 hlock.trylock = trylock;
5015 hlock.read = read;
5016 hlock.check = check;
5017 hlock.hardirqs_off = true;
5018 hlock.references = 0;
5019
5020 verify_lock_unused(lock, &hlock, subclass);
5021 }
5022 return;
5023 }
5024
5025 raw_local_irq_save(flags);
5026 check_flags(flags);
5027
5028 current->lockdep_recursion++;
5029 __lock_acquire(lock, subclass, trylock, read, check,
5030 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
5031 lockdep_recursion_finish();
5032 raw_local_irq_restore(flags);
5033}
5034EXPORT_SYMBOL_GPL(lock_acquire);
5035
5036void lock_release(struct lockdep_map *lock, unsigned long ip)
5037{
5038 unsigned long flags;
5039
5040 trace_lock_release(lock, ip);
5041
5042 if (unlikely(current->lockdep_recursion))
5043 return;
5044
5045 raw_local_irq_save(flags);
5046 check_flags(flags);
5047
5048 current->lockdep_recursion++;
5049 if (__lock_release(lock, ip))
5050 check_chain_key(current);
5051 lockdep_recursion_finish();
5052 raw_local_irq_restore(flags);
5053}
5054EXPORT_SYMBOL_GPL(lock_release);
5055
5056noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
5057{
5058 unsigned long flags;
5059 int ret = 0;
5060
5061 if (unlikely(current->lockdep_recursion))
5062 return 1; /* avoid false negative lockdep_assert_held() */
5063
5064 raw_local_irq_save(flags);
5065 check_flags(flags);
5066
5067 current->lockdep_recursion++;
5068 ret = __lock_is_held(lock, read);
5069 lockdep_recursion_finish();
5070 raw_local_irq_restore(flags);
5071
5072 return ret;
5073}
5074EXPORT_SYMBOL_GPL(lock_is_held_type);
5075NOKPROBE_SYMBOL(lock_is_held_type);
5076
5077struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
5078{
5079 struct pin_cookie cookie = NIL_COOKIE;
5080 unsigned long flags;
5081
5082 if (unlikely(current->lockdep_recursion))
5083 return cookie;
5084
5085 raw_local_irq_save(flags);
5086 check_flags(flags);
5087
5088 current->lockdep_recursion++;
5089 cookie = __lock_pin_lock(lock);
5090 lockdep_recursion_finish();
5091 raw_local_irq_restore(flags);
5092
5093 return cookie;
5094}
5095EXPORT_SYMBOL_GPL(lock_pin_lock);
5096
5097void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5098{
5099 unsigned long flags;
5100
5101 if (unlikely(current->lockdep_recursion))
5102 return;
5103
5104 raw_local_irq_save(flags);
5105 check_flags(flags);
5106
5107 current->lockdep_recursion++;
5108 __lock_repin_lock(lock, cookie);
5109 lockdep_recursion_finish();
5110 raw_local_irq_restore(flags);
5111}
5112EXPORT_SYMBOL_GPL(lock_repin_lock);
5113
5114void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5115{
5116 unsigned long flags;
5117
5118 if (unlikely(current->lockdep_recursion))
5119 return;
5120
5121 raw_local_irq_save(flags);
5122 check_flags(flags);
5123
5124 current->lockdep_recursion++;
5125 __lock_unpin_lock(lock, cookie);
5126 lockdep_recursion_finish();
5127 raw_local_irq_restore(flags);
5128}
5129EXPORT_SYMBOL_GPL(lock_unpin_lock);
5130
5131#ifdef CONFIG_LOCK_STAT
5132static void print_lock_contention_bug(struct task_struct *curr,
5133 struct lockdep_map *lock,
5134 unsigned long ip)
5135{
5136 if (!debug_locks_off())
5137 return;
5138 if (debug_locks_silent)
5139 return;
5140
5141 pr_warn("\n");
5142 pr_warn("=================================\n");
5143 pr_warn("WARNING: bad contention detected!\n");
5144 print_kernel_ident();
5145 pr_warn("---------------------------------\n");
5146 pr_warn("%s/%d is trying to contend lock (",
5147 curr->comm, task_pid_nr(curr));
5148 print_lockdep_cache(lock);
5149 pr_cont(") at:\n");
5150 print_ip_sym(KERN_WARNING, ip);
5151 pr_warn("but there are no locks held!\n");
5152 pr_warn("\nother info that might help us debug this:\n");
5153 lockdep_print_held_locks(curr);
5154
5155 pr_warn("\nstack backtrace:\n");
5156 dump_stack();
5157}
5158
5159static void
5160__lock_contended(struct lockdep_map *lock, unsigned long ip)
5161{
5162 struct task_struct *curr = current;
5163 struct held_lock *hlock;
5164 struct lock_class_stats *stats;
5165 unsigned int depth;
5166 int i, contention_point, contending_point;
5167
5168 depth = curr->lockdep_depth;
5169 /*
5170 * Whee, we contended on this lock, except it seems we're not
5171 * actually trying to acquire anything much at all..
5172 */
5173 if (DEBUG_LOCKS_WARN_ON(!depth))
5174 return;
5175
5176 hlock = find_held_lock(curr, lock, depth, &i);
5177 if (!hlock) {
5178 print_lock_contention_bug(curr, lock, ip);
5179 return;
5180 }
5181
5182 if (hlock->instance != lock)
5183 return;
5184
5185 hlock->waittime_stamp = lockstat_clock();
5186
5187 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
5188 contending_point = lock_point(hlock_class(hlock)->contending_point,
5189 lock->ip);
5190
5191 stats = get_lock_stats(hlock_class(hlock));
5192 if (contention_point < LOCKSTAT_POINTS)
5193 stats->contention_point[contention_point]++;
5194 if (contending_point < LOCKSTAT_POINTS)
5195 stats->contending_point[contending_point]++;
5196 if (lock->cpu != smp_processor_id())
5197 stats->bounces[bounce_contended + !!hlock->read]++;
5198}
5199
5200static void
5201__lock_acquired(struct lockdep_map *lock, unsigned long ip)
5202{
5203 struct task_struct *curr = current;
5204 struct held_lock *hlock;
5205 struct lock_class_stats *stats;
5206 unsigned int depth;
5207 u64 now, waittime = 0;
5208 int i, cpu;
5209
5210 depth = curr->lockdep_depth;
5211 /*
5212 * Yay, we acquired ownership of this lock we didn't try to
5213 * acquire, how the heck did that happen?
5214 */
5215 if (DEBUG_LOCKS_WARN_ON(!depth))
5216 return;
5217
5218 hlock = find_held_lock(curr, lock, depth, &i);
5219 if (!hlock) {
5220 print_lock_contention_bug(curr, lock, _RET_IP_);
5221 return;
5222 }
5223
5224 if (hlock->instance != lock)
5225 return;
5226
5227 cpu = smp_processor_id();
5228 if (hlock->waittime_stamp) {
5229 now = lockstat_clock();
5230 waittime = now - hlock->waittime_stamp;
5231 hlock->holdtime_stamp = now;
5232 }
5233
5234 stats = get_lock_stats(hlock_class(hlock));
5235 if (waittime) {
5236 if (hlock->read)
5237 lock_time_inc(&stats->read_waittime, waittime);
5238 else
5239 lock_time_inc(&stats->write_waittime, waittime);
5240 }
5241 if (lock->cpu != cpu)
5242 stats->bounces[bounce_acquired + !!hlock->read]++;
5243
5244 lock->cpu = cpu;
5245 lock->ip = ip;
5246}
5247
5248void lock_contended(struct lockdep_map *lock, unsigned long ip)
5249{
5250 unsigned long flags;
5251
5252 trace_lock_acquired(lock, ip);
5253
5254 if (unlikely(!lock_stat || !debug_locks))
5255 return;
5256
5257 if (unlikely(current->lockdep_recursion))
5258 return;
5259
5260 raw_local_irq_save(flags);
5261 check_flags(flags);
5262 current->lockdep_recursion++;
5263 __lock_contended(lock, ip);
5264 lockdep_recursion_finish();
5265 raw_local_irq_restore(flags);
5266}
5267EXPORT_SYMBOL_GPL(lock_contended);
5268
5269void lock_acquired(struct lockdep_map *lock, unsigned long ip)
5270{
5271 unsigned long flags;
5272
5273 trace_lock_contended(lock, ip);
5274
5275 if (unlikely(!lock_stat || !debug_locks))
5276 return;
5277
5278 if (unlikely(current->lockdep_recursion))
5279 return;
5280
5281 raw_local_irq_save(flags);
5282 check_flags(flags);
5283 current->lockdep_recursion++;
5284 __lock_acquired(lock, ip);
5285 lockdep_recursion_finish();
5286 raw_local_irq_restore(flags);
5287}
5288EXPORT_SYMBOL_GPL(lock_acquired);
5289#endif
5290
5291/*
5292 * Used by the testsuite, sanitize the validator state
5293 * after a simulated failure:
5294 */
5295
5296void lockdep_reset(void)
5297{
5298 unsigned long flags;
5299 int i;
5300
5301 raw_local_irq_save(flags);
5302 lockdep_init_task(current);
5303 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
5304 nr_hardirq_chains = 0;
5305 nr_softirq_chains = 0;
5306 nr_process_chains = 0;
5307 debug_locks = 1;
5308 for (i = 0; i < CHAINHASH_SIZE; i++)
5309 INIT_HLIST_HEAD(chainhash_table + i);
5310 raw_local_irq_restore(flags);
5311}
5312
5313/* Remove a class from a lock chain. Must be called with the graph lock held. */
5314static void remove_class_from_lock_chain(struct pending_free *pf,
5315 struct lock_chain *chain,
5316 struct lock_class *class)
5317{
5318#ifdef CONFIG_PROVE_LOCKING
5319 int i;
5320
5321 for (i = chain->base; i < chain->base + chain->depth; i++) {
5322 if (chain_hlocks[i] != class - lock_classes)
5323 continue;
5324 /*
5325 * Each lock class occurs at most once in a lock chain so once
5326 * we found a match we can break out of this loop.
5327 */
5328 goto free_lock_chain;
5329 }
5330 /* Since the chain has not been modified, return. */
5331 return;
5332
5333free_lock_chain:
5334 free_chain_hlocks(chain->base, chain->depth);
5335 /* Overwrite the chain key for concurrent RCU readers. */
5336 WRITE_ONCE(chain->chain_key, INITIAL_CHAIN_KEY);
5337 dec_chains(chain->irq_context);
5338
5339 /*
5340 * Note: calling hlist_del_rcu() from inside a
5341 * hlist_for_each_entry_rcu() loop is safe.
5342 */
5343 hlist_del_rcu(&chain->entry);
5344 __set_bit(chain - lock_chains, pf->lock_chains_being_freed);
5345 nr_zapped_lock_chains++;
5346#endif
5347}
5348
5349/* Must be called with the graph lock held. */
5350static void remove_class_from_lock_chains(struct pending_free *pf,
5351 struct lock_class *class)
5352{
5353 struct lock_chain *chain;
5354 struct hlist_head *head;
5355 int i;
5356
5357 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
5358 head = chainhash_table + i;
5359 hlist_for_each_entry_rcu(chain, head, entry) {
5360 remove_class_from_lock_chain(pf, chain, class);
5361 }
5362 }
5363}
5364
5365/*
5366 * Remove all references to a lock class. The caller must hold the graph lock.
5367 */
5368static void zap_class(struct pending_free *pf, struct lock_class *class)
5369{
5370 struct lock_list *entry;
5371 int i;
5372
5373 WARN_ON_ONCE(!class->key);
5374
5375 /*
5376 * Remove all dependencies this lock is
5377 * involved in:
5378 */
5379 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
5380 entry = list_entries + i;
5381 if (entry->class != class && entry->links_to != class)
5382 continue;
5383 __clear_bit(i, list_entries_in_use);
5384 nr_list_entries--;
5385 list_del_rcu(&entry->entry);
5386 }
5387 if (list_empty(&class->locks_after) &&
5388 list_empty(&class->locks_before)) {
5389 list_move_tail(&class->lock_entry, &pf->zapped);
5390 hlist_del_rcu(&class->hash_entry);
5391 WRITE_ONCE(class->key, NULL);
5392 WRITE_ONCE(class->name, NULL);
5393 nr_lock_classes--;
5394 __clear_bit(class - lock_classes, lock_classes_in_use);
5395 } else {
5396 WARN_ONCE(true, "%s() failed for class %s\n", __func__,
5397 class->name);
5398 }
5399
5400 remove_class_from_lock_chains(pf, class);
5401 nr_zapped_classes++;
5402}
5403
5404static void reinit_class(struct lock_class *class)
5405{
5406 void *const p = class;
5407 const unsigned int offset = offsetof(struct lock_class, key);
5408
5409 WARN_ON_ONCE(!class->lock_entry.next);
5410 WARN_ON_ONCE(!list_empty(&class->locks_after));
5411 WARN_ON_ONCE(!list_empty(&class->locks_before));
5412 memset(p + offset, 0, sizeof(*class) - offset);
5413 WARN_ON_ONCE(!class->lock_entry.next);
5414 WARN_ON_ONCE(!list_empty(&class->locks_after));
5415 WARN_ON_ONCE(!list_empty(&class->locks_before));
5416}
5417
5418static inline int within(const void *addr, void *start, unsigned long size)
5419{
5420 return addr >= start && addr < start + size;
5421}
5422
5423static bool inside_selftest(void)
5424{
5425 return current == lockdep_selftest_task_struct;
5426}
5427
5428/* The caller must hold the graph lock. */
5429static struct pending_free *get_pending_free(void)
5430{
5431 return delayed_free.pf + delayed_free.index;
5432}
5433
5434static void free_zapped_rcu(struct rcu_head *cb);
5435
5436/*
5437 * Schedule an RCU callback if no RCU callback is pending. Must be called with
5438 * the graph lock held.
5439 */
5440static void call_rcu_zapped(struct pending_free *pf)
5441{
5442 WARN_ON_ONCE(inside_selftest());
5443
5444 if (list_empty(&pf->zapped))
5445 return;
5446
5447 if (delayed_free.scheduled)
5448 return;
5449
5450 delayed_free.scheduled = true;
5451
5452 WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf);
5453 delayed_free.index ^= 1;
5454
5455 call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
5456}
5457
5458/* The caller must hold the graph lock. May be called from RCU context. */
5459static void __free_zapped_classes(struct pending_free *pf)
5460{
5461 struct lock_class *class;
5462
5463 check_data_structures();
5464
5465 list_for_each_entry(class, &pf->zapped, lock_entry)
5466 reinit_class(class);
5467
5468 list_splice_init(&pf->zapped, &free_lock_classes);
5469
5470#ifdef CONFIG_PROVE_LOCKING
5471 bitmap_andnot(lock_chains_in_use, lock_chains_in_use,
5472 pf->lock_chains_being_freed, ARRAY_SIZE(lock_chains));
5473 bitmap_clear(pf->lock_chains_being_freed, 0, ARRAY_SIZE(lock_chains));
5474#endif
5475}
5476
5477static void free_zapped_rcu(struct rcu_head *ch)
5478{
5479 struct pending_free *pf;
5480 unsigned long flags;
5481
5482 if (WARN_ON_ONCE(ch != &delayed_free.rcu_head))
5483 return;
5484
5485 raw_local_irq_save(flags);
5486 lockdep_lock();
5487
5488 /* closed head */
5489 pf = delayed_free.pf + (delayed_free.index ^ 1);
5490 __free_zapped_classes(pf);
5491 delayed_free.scheduled = false;
5492
5493 /*
5494 * If there's anything on the open list, close and start a new callback.
5495 */
5496 call_rcu_zapped(delayed_free.pf + delayed_free.index);
5497
5498 lockdep_unlock();
5499 raw_local_irq_restore(flags);
5500}
5501
5502/*
5503 * Remove all lock classes from the class hash table and from the
5504 * all_lock_classes list whose key or name is in the address range [start,
5505 * start + size). Move these lock classes to the zapped_classes list. Must
5506 * be called with the graph lock held.
5507 */
5508static void __lockdep_free_key_range(struct pending_free *pf, void *start,
5509 unsigned long size)
5510{
5511 struct lock_class *class;
5512 struct hlist_head *head;
5513 int i;
5514
5515 /* Unhash all classes that were created by a module. */
5516 for (i = 0; i < CLASSHASH_SIZE; i++) {
5517 head = classhash_table + i;
5518 hlist_for_each_entry_rcu(class, head, hash_entry) {
5519 if (!within(class->key, start, size) &&
5520 !within(class->name, start, size))
5521 continue;
5522 zap_class(pf, class);
5523 }
5524 }
5525}
5526
5527/*
5528 * Used in module.c to remove lock classes from memory that is going to be
5529 * freed; and possibly re-used by other modules.
5530 *
5531 * We will have had one synchronize_rcu() before getting here, so we're
5532 * guaranteed nobody will look up these exact classes -- they're properly dead
5533 * but still allocated.
5534 */
5535static void lockdep_free_key_range_reg(void *start, unsigned long size)
5536{
5537 struct pending_free *pf;
5538 unsigned long flags;
5539
5540 init_data_structures_once();
5541
5542 raw_local_irq_save(flags);
5543 lockdep_lock();
5544 pf = get_pending_free();
5545 __lockdep_free_key_range(pf, start, size);
5546 call_rcu_zapped(pf);
5547 lockdep_unlock();
5548 raw_local_irq_restore(flags);
5549
5550 /*
5551 * Wait for any possible iterators from look_up_lock_class() to pass
5552 * before continuing to free the memory they refer to.
5553 */
5554 synchronize_rcu();
5555}
5556
5557/*
5558 * Free all lockdep keys in the range [start, start+size). Does not sleep.
5559 * Ignores debug_locks. Must only be used by the lockdep selftests.
5560 */
5561static void lockdep_free_key_range_imm(void *start, unsigned long size)
5562{
5563 struct pending_free *pf = delayed_free.pf;
5564 unsigned long flags;
5565
5566 init_data_structures_once();
5567
5568 raw_local_irq_save(flags);
5569 lockdep_lock();
5570 __lockdep_free_key_range(pf, start, size);
5571 __free_zapped_classes(pf);
5572 lockdep_unlock();
5573 raw_local_irq_restore(flags);
5574}
5575
5576void lockdep_free_key_range(void *start, unsigned long size)
5577{
5578 init_data_structures_once();
5579
5580 if (inside_selftest())
5581 lockdep_free_key_range_imm(start, size);
5582 else
5583 lockdep_free_key_range_reg(start, size);
5584}
5585
5586/*
5587 * Check whether any element of the @lock->class_cache[] array refers to a
5588 * registered lock class. The caller must hold either the graph lock or the
5589 * RCU read lock.
5590 */
5591static bool lock_class_cache_is_registered(struct lockdep_map *lock)
5592{
5593 struct lock_class *class;
5594 struct hlist_head *head;
5595 int i, j;
5596
5597 for (i = 0; i < CLASSHASH_SIZE; i++) {
5598 head = classhash_table + i;
5599 hlist_for_each_entry_rcu(class, head, hash_entry) {
5600 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
5601 if (lock->class_cache[j] == class)
5602 return true;
5603 }
5604 }
5605 return false;
5606}
5607
5608/* The caller must hold the graph lock. Does not sleep. */
5609static void __lockdep_reset_lock(struct pending_free *pf,
5610 struct lockdep_map *lock)
5611{
5612 struct lock_class *class;
5613 int j;
5614
5615 /*
5616 * Remove all classes this lock might have:
5617 */
5618 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
5619 /*
5620 * If the class exists we look it up and zap it:
5621 */
5622 class = look_up_lock_class(lock, j);
5623 if (class)
5624 zap_class(pf, class);
5625 }
5626 /*
5627 * Debug check: in the end all mapped classes should
5628 * be gone.
5629 */
5630 if (WARN_ON_ONCE(lock_class_cache_is_registered(lock)))
5631 debug_locks_off();
5632}
5633
5634/*
5635 * Remove all information lockdep has about a lock if debug_locks == 1. Free
5636 * released data structures from RCU context.
5637 */
5638static void lockdep_reset_lock_reg(struct lockdep_map *lock)
5639{
5640 struct pending_free *pf;
5641 unsigned long flags;
5642 int locked;
5643
5644 raw_local_irq_save(flags);
5645 locked = graph_lock();
5646 if (!locked)
5647 goto out_irq;
5648
5649 pf = get_pending_free();
5650 __lockdep_reset_lock(pf, lock);
5651 call_rcu_zapped(pf);
5652
5653 graph_unlock();
5654out_irq:
5655 raw_local_irq_restore(flags);
5656}
5657
5658/*
5659 * Reset a lock. Does not sleep. Ignores debug_locks. Must only be used by the
5660 * lockdep selftests.
5661 */
5662static void lockdep_reset_lock_imm(struct lockdep_map *lock)
5663{
5664 struct pending_free *pf = delayed_free.pf;
5665 unsigned long flags;
5666
5667 raw_local_irq_save(flags);
5668 lockdep_lock();
5669 __lockdep_reset_lock(pf, lock);
5670 __free_zapped_classes(pf);
5671 lockdep_unlock();
5672 raw_local_irq_restore(flags);
5673}
5674
5675void lockdep_reset_lock(struct lockdep_map *lock)
5676{
5677 init_data_structures_once();
5678
5679 if (inside_selftest())
5680 lockdep_reset_lock_imm(lock);
5681 else
5682 lockdep_reset_lock_reg(lock);
5683}
5684
5685/* Unregister a dynamically allocated key. */
5686void lockdep_unregister_key(struct lock_class_key *key)
5687{
5688 struct hlist_head *hash_head = keyhashentry(key);
5689 struct lock_class_key *k;
5690 struct pending_free *pf;
5691 unsigned long flags;
5692 bool found = false;
5693
5694 might_sleep();
5695
5696 if (WARN_ON_ONCE(static_obj(key)))
5697 return;
5698
5699 raw_local_irq_save(flags);
5700 if (!graph_lock())
5701 goto out_irq;
5702
5703 pf = get_pending_free();
5704 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
5705 if (k == key) {
5706 hlist_del_rcu(&k->hash_entry);
5707 found = true;
5708 break;
5709 }
5710 }
5711 WARN_ON_ONCE(!found);
5712 __lockdep_free_key_range(pf, key, 1);
5713 call_rcu_zapped(pf);
5714 graph_unlock();
5715out_irq:
5716 raw_local_irq_restore(flags);
5717
5718 /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */
5719 synchronize_rcu();
5720}
5721EXPORT_SYMBOL_GPL(lockdep_unregister_key);
5722
5723void __init lockdep_init(void)
5724{
5725 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
5726
5727 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
5728 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
5729 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
5730 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
5731 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
5732 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
5733 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
5734
5735 printk(" memory used by lock dependency info: %zu kB\n",
5736 (sizeof(lock_classes) +
5737 sizeof(lock_classes_in_use) +
5738 sizeof(classhash_table) +
5739 sizeof(list_entries) +
5740 sizeof(list_entries_in_use) +
5741 sizeof(chainhash_table) +
5742 sizeof(delayed_free)
5743#ifdef CONFIG_PROVE_LOCKING
5744 + sizeof(lock_cq)
5745 + sizeof(lock_chains)
5746 + sizeof(lock_chains_in_use)
5747 + sizeof(chain_hlocks)
5748#endif
5749 ) / 1024
5750 );
5751
5752#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
5753 printk(" memory used for stack traces: %zu kB\n",
5754 (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024
5755 );
5756#endif
5757
5758 printk(" per task-struct memory footprint: %zu bytes\n",
5759 sizeof(((struct task_struct *)NULL)->held_locks));
5760}
5761
5762static void
5763print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
5764 const void *mem_to, struct held_lock *hlock)
5765{
5766 if (!debug_locks_off())
5767 return;
5768 if (debug_locks_silent)
5769 return;
5770
5771 pr_warn("\n");
5772 pr_warn("=========================\n");
5773 pr_warn("WARNING: held lock freed!\n");
5774 print_kernel_ident();
5775 pr_warn("-------------------------\n");
5776 pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
5777 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
5778 print_lock(hlock);
5779 lockdep_print_held_locks(curr);
5780
5781 pr_warn("\nstack backtrace:\n");
5782 dump_stack();
5783}
5784
5785static inline int not_in_range(const void* mem_from, unsigned long mem_len,
5786 const void* lock_from, unsigned long lock_len)
5787{
5788 return lock_from + lock_len <= mem_from ||
5789 mem_from + mem_len <= lock_from;
5790}
5791
5792/*
5793 * Called when kernel memory is freed (or unmapped), or if a lock
5794 * is destroyed or reinitialized - this code checks whether there is
5795 * any held lock in the memory range of <from> to <to>:
5796 */
5797void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
5798{
5799 struct task_struct *curr = current;
5800 struct held_lock *hlock;
5801 unsigned long flags;
5802 int i;
5803
5804 if (unlikely(!debug_locks))
5805 return;
5806
5807 raw_local_irq_save(flags);
5808 for (i = 0; i < curr->lockdep_depth; i++) {
5809 hlock = curr->held_locks + i;
5810
5811 if (not_in_range(mem_from, mem_len, hlock->instance,
5812 sizeof(*hlock->instance)))
5813 continue;
5814
5815 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
5816 break;
5817 }
5818 raw_local_irq_restore(flags);
5819}
5820EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
5821
5822static void print_held_locks_bug(void)
5823{
5824 if (!debug_locks_off())
5825 return;
5826 if (debug_locks_silent)
5827 return;
5828
5829 pr_warn("\n");
5830 pr_warn("====================================\n");
5831 pr_warn("WARNING: %s/%d still has locks held!\n",
5832 current->comm, task_pid_nr(current));
5833 print_kernel_ident();
5834 pr_warn("------------------------------------\n");
5835 lockdep_print_held_locks(current);
5836 pr_warn("\nstack backtrace:\n");
5837 dump_stack();
5838}
5839
5840void debug_check_no_locks_held(void)
5841{
5842 if (unlikely(current->lockdep_depth > 0))
5843 print_held_locks_bug();
5844}
5845EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
5846
5847#ifdef __KERNEL__
5848void debug_show_all_locks(void)
5849{
5850 struct task_struct *g, *p;
5851
5852 if (unlikely(!debug_locks)) {
5853 pr_warn("INFO: lockdep is turned off.\n");
5854 return;
5855 }
5856 pr_warn("\nShowing all locks held in the system:\n");
5857
5858 rcu_read_lock();
5859 for_each_process_thread(g, p) {
5860 if (!p->lockdep_depth)
5861 continue;
5862 lockdep_print_held_locks(p);
5863 touch_nmi_watchdog();
5864 touch_all_softlockup_watchdogs();
5865 }
5866 rcu_read_unlock();
5867
5868 pr_warn("\n");
5869 pr_warn("=============================================\n\n");
5870}
5871EXPORT_SYMBOL_GPL(debug_show_all_locks);
5872#endif
5873
5874/*
5875 * Careful: only use this function if you are sure that
5876 * the task cannot run in parallel!
5877 */
5878void debug_show_held_locks(struct task_struct *task)
5879{
5880 if (unlikely(!debug_locks)) {
5881 printk("INFO: lockdep is turned off.\n");
5882 return;
5883 }
5884 lockdep_print_held_locks(task);
5885}
5886EXPORT_SYMBOL_GPL(debug_show_held_locks);
5887
5888asmlinkage __visible void lockdep_sys_exit(void)
5889{
5890 struct task_struct *curr = current;
5891
5892 if (unlikely(curr->lockdep_depth)) {
5893 if (!debug_locks_off())
5894 return;
5895 pr_warn("\n");
5896 pr_warn("================================================\n");
5897 pr_warn("WARNING: lock held when returning to user space!\n");
5898 print_kernel_ident();
5899 pr_warn("------------------------------------------------\n");
5900 pr_warn("%s/%d is leaving the kernel with locks still held!\n",
5901 curr->comm, curr->pid);
5902 lockdep_print_held_locks(curr);
5903 }
5904
5905 /*
5906 * The lock history for each syscall should be independent. So wipe the
5907 * slate clean on return to userspace.
5908 */
5909 lockdep_invariant_state(false);
5910}
5911
5912void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
5913{
5914 struct task_struct *curr = current;
5915
5916 /* Note: the following can be executed concurrently, so be careful. */
5917 pr_warn("\n");
5918 pr_warn("=============================\n");
5919 pr_warn("WARNING: suspicious RCU usage\n");
5920 print_kernel_ident();
5921 pr_warn("-----------------------------\n");
5922 pr_warn("%s:%d %s!\n", file, line, s);
5923 pr_warn("\nother info that might help us debug this:\n\n");
5924 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
5925 !rcu_lockdep_current_cpu_online()
5926 ? "RCU used illegally from offline CPU!\n"
5927 : "",
5928 rcu_scheduler_active, debug_locks);
5929
5930 /*
5931 * If a CPU is in the RCU-free window in idle (ie: in the section
5932 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
5933 * considers that CPU to be in an "extended quiescent state",
5934 * which means that RCU will be completely ignoring that CPU.
5935 * Therefore, rcu_read_lock() and friends have absolutely no
5936 * effect on a CPU running in that state. In other words, even if
5937 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
5938 * delete data structures out from under it. RCU really has no
5939 * choice here: we need to keep an RCU-free window in idle where
5940 * the CPU may possibly enter into low power mode. This way we can
5941 * notice an extended quiescent state to other CPUs that started a grace
5942 * period. Otherwise we would delay any grace period as long as we run
5943 * in the idle task.
5944 *
5945 * So complain bitterly if someone does call rcu_read_lock(),
5946 * rcu_read_lock_bh() and so on from extended quiescent states.
5947 */
5948 if (!rcu_is_watching())
5949 pr_warn("RCU used illegally from extended quiescent state!\n");
5950
5951 lockdep_print_held_locks(curr);
5952 pr_warn("\nstack backtrace:\n");
5953 dump_stack();
5954}
5955EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);