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1/*
2 * kernel/lockdep.c
3 *
4 * Runtime locking correctness validator
5 *
6 * Started by Ingo Molnar:
7 *
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
10 *
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
13 *
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
17 *
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
20 *
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
24 *
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
27 */
28#define DISABLE_BRANCH_PROFILING
29#include <linux/mutex.h>
30#include <linux/sched.h>
31#include <linux/delay.h>
32#include <linux/module.h>
33#include <linux/proc_fs.h>
34#include <linux/seq_file.h>
35#include <linux/spinlock.h>
36#include <linux/kallsyms.h>
37#include <linux/interrupt.h>
38#include <linux/stacktrace.h>
39#include <linux/debug_locks.h>
40#include <linux/irqflags.h>
41#include <linux/utsname.h>
42#include <linux/hash.h>
43#include <linux/ftrace.h>
44#include <linux/stringify.h>
45#include <linux/bitops.h>
46#include <linux/gfp.h>
47#include <linux/kmemcheck.h>
48#include <linux/random.h>
49#include <linux/jhash.h>
50
51#include <asm/sections.h>
52
53#include "lockdep_internals.h"
54
55#define CREATE_TRACE_POINTS
56#include <trace/events/lock.h>
57
58#ifdef CONFIG_PROVE_LOCKING
59int prove_locking = 1;
60module_param(prove_locking, int, 0644);
61#else
62#define prove_locking 0
63#endif
64
65#ifdef CONFIG_LOCK_STAT
66int lock_stat = 1;
67module_param(lock_stat, int, 0644);
68#else
69#define lock_stat 0
70#endif
71
72/*
73 * lockdep_lock: protects the lockdep graph, the hashes and the
74 * class/list/hash allocators.
75 *
76 * This is one of the rare exceptions where it's justified
77 * to use a raw spinlock - we really dont want the spinlock
78 * code to recurse back into the lockdep code...
79 */
80static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
81
82static int graph_lock(void)
83{
84 arch_spin_lock(&lockdep_lock);
85 /*
86 * Make sure that if another CPU detected a bug while
87 * walking the graph we dont change it (while the other
88 * CPU is busy printing out stuff with the graph lock
89 * dropped already)
90 */
91 if (!debug_locks) {
92 arch_spin_unlock(&lockdep_lock);
93 return 0;
94 }
95 /* prevent any recursions within lockdep from causing deadlocks */
96 current->lockdep_recursion++;
97 return 1;
98}
99
100static inline int graph_unlock(void)
101{
102 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
103 /*
104 * The lockdep graph lock isn't locked while we expect it to
105 * be, we're confused now, bye!
106 */
107 return DEBUG_LOCKS_WARN_ON(1);
108 }
109
110 current->lockdep_recursion--;
111 arch_spin_unlock(&lockdep_lock);
112 return 0;
113}
114
115/*
116 * Turn lock debugging off and return with 0 if it was off already,
117 * and also release the graph lock:
118 */
119static inline int debug_locks_off_graph_unlock(void)
120{
121 int ret = debug_locks_off();
122
123 arch_spin_unlock(&lockdep_lock);
124
125 return ret;
126}
127
128unsigned long nr_list_entries;
129static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
130
131/*
132 * All data structures here are protected by the global debug_lock.
133 *
134 * Mutex key structs only get allocated, once during bootup, and never
135 * get freed - this significantly simplifies the debugging code.
136 */
137unsigned long nr_lock_classes;
138static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
139
140static inline struct lock_class *hlock_class(struct held_lock *hlock)
141{
142 if (!hlock->class_idx) {
143 /*
144 * Someone passed in garbage, we give up.
145 */
146 DEBUG_LOCKS_WARN_ON(1);
147 return NULL;
148 }
149 return lock_classes + hlock->class_idx - 1;
150}
151
152#ifdef CONFIG_LOCK_STAT
153static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
154
155static inline u64 lockstat_clock(void)
156{
157 return local_clock();
158}
159
160static int lock_point(unsigned long points[], unsigned long ip)
161{
162 int i;
163
164 for (i = 0; i < LOCKSTAT_POINTS; i++) {
165 if (points[i] == 0) {
166 points[i] = ip;
167 break;
168 }
169 if (points[i] == ip)
170 break;
171 }
172
173 return i;
174}
175
176static void lock_time_inc(struct lock_time *lt, u64 time)
177{
178 if (time > lt->max)
179 lt->max = time;
180
181 if (time < lt->min || !lt->nr)
182 lt->min = time;
183
184 lt->total += time;
185 lt->nr++;
186}
187
188static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
189{
190 if (!src->nr)
191 return;
192
193 if (src->max > dst->max)
194 dst->max = src->max;
195
196 if (src->min < dst->min || !dst->nr)
197 dst->min = src->min;
198
199 dst->total += src->total;
200 dst->nr += src->nr;
201}
202
203struct lock_class_stats lock_stats(struct lock_class *class)
204{
205 struct lock_class_stats stats;
206 int cpu, i;
207
208 memset(&stats, 0, sizeof(struct lock_class_stats));
209 for_each_possible_cpu(cpu) {
210 struct lock_class_stats *pcs =
211 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
212
213 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
214 stats.contention_point[i] += pcs->contention_point[i];
215
216 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
217 stats.contending_point[i] += pcs->contending_point[i];
218
219 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
220 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
221
222 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
223 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
224
225 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
226 stats.bounces[i] += pcs->bounces[i];
227 }
228
229 return stats;
230}
231
232void clear_lock_stats(struct lock_class *class)
233{
234 int cpu;
235
236 for_each_possible_cpu(cpu) {
237 struct lock_class_stats *cpu_stats =
238 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
239
240 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
241 }
242 memset(class->contention_point, 0, sizeof(class->contention_point));
243 memset(class->contending_point, 0, sizeof(class->contending_point));
244}
245
246static struct lock_class_stats *get_lock_stats(struct lock_class *class)
247{
248 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
249}
250
251static void put_lock_stats(struct lock_class_stats *stats)
252{
253 put_cpu_var(cpu_lock_stats);
254}
255
256static void lock_release_holdtime(struct held_lock *hlock)
257{
258 struct lock_class_stats *stats;
259 u64 holdtime;
260
261 if (!lock_stat)
262 return;
263
264 holdtime = lockstat_clock() - hlock->holdtime_stamp;
265
266 stats = get_lock_stats(hlock_class(hlock));
267 if (hlock->read)
268 lock_time_inc(&stats->read_holdtime, holdtime);
269 else
270 lock_time_inc(&stats->write_holdtime, holdtime);
271 put_lock_stats(stats);
272}
273#else
274static inline void lock_release_holdtime(struct held_lock *hlock)
275{
276}
277#endif
278
279/*
280 * We keep a global list of all lock classes. The list only grows,
281 * never shrinks. The list is only accessed with the lockdep
282 * spinlock lock held.
283 */
284LIST_HEAD(all_lock_classes);
285
286/*
287 * The lockdep classes are in a hash-table as well, for fast lookup:
288 */
289#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
290#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
291#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
292#define classhashentry(key) (classhash_table + __classhashfn((key)))
293
294static struct hlist_head classhash_table[CLASSHASH_SIZE];
295
296/*
297 * We put the lock dependency chains into a hash-table as well, to cache
298 * their existence:
299 */
300#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
301#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
302#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
303#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
304
305static struct hlist_head chainhash_table[CHAINHASH_SIZE];
306
307/*
308 * The hash key of the lock dependency chains is a hash itself too:
309 * it's a hash of all locks taken up to that lock, including that lock.
310 * It's a 64-bit hash, because it's important for the keys to be
311 * unique.
312 */
313static inline u64 iterate_chain_key(u64 key, u32 idx)
314{
315 u32 k0 = key, k1 = key >> 32;
316
317 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
318
319 return k0 | (u64)k1 << 32;
320}
321
322void lockdep_off(void)
323{
324 current->lockdep_recursion++;
325}
326EXPORT_SYMBOL(lockdep_off);
327
328void lockdep_on(void)
329{
330 current->lockdep_recursion--;
331}
332EXPORT_SYMBOL(lockdep_on);
333
334/*
335 * Debugging switches:
336 */
337
338#define VERBOSE 0
339#define VERY_VERBOSE 0
340
341#if VERBOSE
342# define HARDIRQ_VERBOSE 1
343# define SOFTIRQ_VERBOSE 1
344# define RECLAIM_VERBOSE 1
345#else
346# define HARDIRQ_VERBOSE 0
347# define SOFTIRQ_VERBOSE 0
348# define RECLAIM_VERBOSE 0
349#endif
350
351#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
352/*
353 * Quick filtering for interesting events:
354 */
355static int class_filter(struct lock_class *class)
356{
357#if 0
358 /* Example */
359 if (class->name_version == 1 &&
360 !strcmp(class->name, "lockname"))
361 return 1;
362 if (class->name_version == 1 &&
363 !strcmp(class->name, "&struct->lockfield"))
364 return 1;
365#endif
366 /* Filter everything else. 1 would be to allow everything else */
367 return 0;
368}
369#endif
370
371static int verbose(struct lock_class *class)
372{
373#if VERBOSE
374 return class_filter(class);
375#endif
376 return 0;
377}
378
379/*
380 * Stack-trace: tightly packed array of stack backtrace
381 * addresses. Protected by the graph_lock.
382 */
383unsigned long nr_stack_trace_entries;
384static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
385
386static void print_lockdep_off(const char *bug_msg)
387{
388 printk(KERN_DEBUG "%s\n", bug_msg);
389 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
390#ifdef CONFIG_LOCK_STAT
391 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
392#endif
393}
394
395static int save_trace(struct stack_trace *trace)
396{
397 trace->nr_entries = 0;
398 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
399 trace->entries = stack_trace + nr_stack_trace_entries;
400
401 trace->skip = 3;
402
403 save_stack_trace(trace);
404
405 /*
406 * Some daft arches put -1 at the end to indicate its a full trace.
407 *
408 * <rant> this is buggy anyway, since it takes a whole extra entry so a
409 * complete trace that maxes out the entries provided will be reported
410 * as incomplete, friggin useless </rant>
411 */
412 if (trace->nr_entries != 0 &&
413 trace->entries[trace->nr_entries-1] == ULONG_MAX)
414 trace->nr_entries--;
415
416 trace->max_entries = trace->nr_entries;
417
418 nr_stack_trace_entries += trace->nr_entries;
419
420 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
421 if (!debug_locks_off_graph_unlock())
422 return 0;
423
424 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
425 dump_stack();
426
427 return 0;
428 }
429
430 return 1;
431}
432
433unsigned int nr_hardirq_chains;
434unsigned int nr_softirq_chains;
435unsigned int nr_process_chains;
436unsigned int max_lockdep_depth;
437
438#ifdef CONFIG_DEBUG_LOCKDEP
439/*
440 * Various lockdep statistics:
441 */
442DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
443#endif
444
445/*
446 * Locking printouts:
447 */
448
449#define __USAGE(__STATE) \
450 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
451 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
452 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
453 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
454
455static const char *usage_str[] =
456{
457#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
458#include "lockdep_states.h"
459#undef LOCKDEP_STATE
460 [LOCK_USED] = "INITIAL USE",
461};
462
463const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
464{
465 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
466}
467
468static inline unsigned long lock_flag(enum lock_usage_bit bit)
469{
470 return 1UL << bit;
471}
472
473static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
474{
475 char c = '.';
476
477 if (class->usage_mask & lock_flag(bit + 2))
478 c = '+';
479 if (class->usage_mask & lock_flag(bit)) {
480 c = '-';
481 if (class->usage_mask & lock_flag(bit + 2))
482 c = '?';
483 }
484
485 return c;
486}
487
488void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
489{
490 int i = 0;
491
492#define LOCKDEP_STATE(__STATE) \
493 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
494 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
495#include "lockdep_states.h"
496#undef LOCKDEP_STATE
497
498 usage[i] = '\0';
499}
500
501static void __print_lock_name(struct lock_class *class)
502{
503 char str[KSYM_NAME_LEN];
504 const char *name;
505
506 name = class->name;
507 if (!name) {
508 name = __get_key_name(class->key, str);
509 printk(KERN_CONT "%s", name);
510 } else {
511 printk(KERN_CONT "%s", name);
512 if (class->name_version > 1)
513 printk(KERN_CONT "#%d", class->name_version);
514 if (class->subclass)
515 printk(KERN_CONT "/%d", class->subclass);
516 }
517}
518
519static void print_lock_name(struct lock_class *class)
520{
521 char usage[LOCK_USAGE_CHARS];
522
523 get_usage_chars(class, usage);
524
525 printk(KERN_CONT " (");
526 __print_lock_name(class);
527 printk(KERN_CONT "){%s}", usage);
528}
529
530static void print_lockdep_cache(struct lockdep_map *lock)
531{
532 const char *name;
533 char str[KSYM_NAME_LEN];
534
535 name = lock->name;
536 if (!name)
537 name = __get_key_name(lock->key->subkeys, str);
538
539 printk(KERN_CONT "%s", name);
540}
541
542static void print_lock(struct held_lock *hlock)
543{
544 /*
545 * We can be called locklessly through debug_show_all_locks() so be
546 * extra careful, the hlock might have been released and cleared.
547 */
548 unsigned int class_idx = hlock->class_idx;
549
550 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
551 barrier();
552
553 if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
554 printk(KERN_CONT "<RELEASED>\n");
555 return;
556 }
557
558 print_lock_name(lock_classes + class_idx - 1);
559 printk(KERN_CONT ", at: [<%p>] %pS\n",
560 (void *)hlock->acquire_ip, (void *)hlock->acquire_ip);
561}
562
563static void lockdep_print_held_locks(struct task_struct *curr)
564{
565 int i, depth = curr->lockdep_depth;
566
567 if (!depth) {
568 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
569 return;
570 }
571 printk("%d lock%s held by %s/%d:\n",
572 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
573
574 for (i = 0; i < depth; i++) {
575 printk(" #%d: ", i);
576 print_lock(curr->held_locks + i);
577 }
578}
579
580static void print_kernel_ident(void)
581{
582 printk("%s %.*s %s\n", init_utsname()->release,
583 (int)strcspn(init_utsname()->version, " "),
584 init_utsname()->version,
585 print_tainted());
586}
587
588static int very_verbose(struct lock_class *class)
589{
590#if VERY_VERBOSE
591 return class_filter(class);
592#endif
593 return 0;
594}
595
596/*
597 * Is this the address of a static object:
598 */
599#ifdef __KERNEL__
600static int static_obj(void *obj)
601{
602 unsigned long start = (unsigned long) &_stext,
603 end = (unsigned long) &_end,
604 addr = (unsigned long) obj;
605
606 /*
607 * static variable?
608 */
609 if ((addr >= start) && (addr < end))
610 return 1;
611
612 if (arch_is_kernel_data(addr))
613 return 1;
614
615 /*
616 * in-kernel percpu var?
617 */
618 if (is_kernel_percpu_address(addr))
619 return 1;
620
621 /*
622 * module static or percpu var?
623 */
624 return is_module_address(addr) || is_module_percpu_address(addr);
625}
626#endif
627
628/*
629 * To make lock name printouts unique, we calculate a unique
630 * class->name_version generation counter:
631 */
632static int count_matching_names(struct lock_class *new_class)
633{
634 struct lock_class *class;
635 int count = 0;
636
637 if (!new_class->name)
638 return 0;
639
640 list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
641 if (new_class->key - new_class->subclass == class->key)
642 return class->name_version;
643 if (class->name && !strcmp(class->name, new_class->name))
644 count = max(count, class->name_version);
645 }
646
647 return count + 1;
648}
649
650/*
651 * Register a lock's class in the hash-table, if the class is not present
652 * yet. Otherwise we look it up. We cache the result in the lock object
653 * itself, so actual lookup of the hash should be once per lock object.
654 */
655static inline struct lock_class *
656look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
657{
658 struct lockdep_subclass_key *key;
659 struct hlist_head *hash_head;
660 struct lock_class *class;
661
662 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
663 debug_locks_off();
664 printk(KERN_ERR
665 "BUG: looking up invalid subclass: %u\n", subclass);
666 printk(KERN_ERR
667 "turning off the locking correctness validator.\n");
668 dump_stack();
669 return NULL;
670 }
671
672 /*
673 * Static locks do not have their class-keys yet - for them the key
674 * is the lock object itself:
675 */
676 if (unlikely(!lock->key))
677 lock->key = (void *)lock;
678
679 /*
680 * NOTE: the class-key must be unique. For dynamic locks, a static
681 * lock_class_key variable is passed in through the mutex_init()
682 * (or spin_lock_init()) call - which acts as the key. For static
683 * locks we use the lock object itself as the key.
684 */
685 BUILD_BUG_ON(sizeof(struct lock_class_key) >
686 sizeof(struct lockdep_map));
687
688 key = lock->key->subkeys + subclass;
689
690 hash_head = classhashentry(key);
691
692 /*
693 * We do an RCU walk of the hash, see lockdep_free_key_range().
694 */
695 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
696 return NULL;
697
698 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
699 if (class->key == key) {
700 /*
701 * Huh! same key, different name? Did someone trample
702 * on some memory? We're most confused.
703 */
704 WARN_ON_ONCE(class->name != lock->name);
705 return class;
706 }
707 }
708
709 return NULL;
710}
711
712/*
713 * Register a lock's class in the hash-table, if the class is not present
714 * yet. Otherwise we look it up. We cache the result in the lock object
715 * itself, so actual lookup of the hash should be once per lock object.
716 */
717static struct lock_class *
718register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
719{
720 struct lockdep_subclass_key *key;
721 struct hlist_head *hash_head;
722 struct lock_class *class;
723
724 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
725
726 class = look_up_lock_class(lock, subclass);
727 if (likely(class))
728 goto out_set_class_cache;
729
730 /*
731 * Debug-check: all keys must be persistent!
732 */
733 if (!static_obj(lock->key)) {
734 debug_locks_off();
735 printk("INFO: trying to register non-static key.\n");
736 printk("the code is fine but needs lockdep annotation.\n");
737 printk("turning off the locking correctness validator.\n");
738 dump_stack();
739
740 return NULL;
741 }
742
743 key = lock->key->subkeys + subclass;
744 hash_head = classhashentry(key);
745
746 if (!graph_lock()) {
747 return NULL;
748 }
749 /*
750 * We have to do the hash-walk again, to avoid races
751 * with another CPU:
752 */
753 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
754 if (class->key == key)
755 goto out_unlock_set;
756 }
757
758 /*
759 * Allocate a new key from the static array, and add it to
760 * the hash:
761 */
762 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
763 if (!debug_locks_off_graph_unlock()) {
764 return NULL;
765 }
766
767 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
768 dump_stack();
769 return NULL;
770 }
771 class = lock_classes + nr_lock_classes++;
772 debug_atomic_inc(nr_unused_locks);
773 class->key = key;
774 class->name = lock->name;
775 class->subclass = subclass;
776 INIT_LIST_HEAD(&class->lock_entry);
777 INIT_LIST_HEAD(&class->locks_before);
778 INIT_LIST_HEAD(&class->locks_after);
779 class->name_version = count_matching_names(class);
780 /*
781 * We use RCU's safe list-add method to make
782 * parallel walking of the hash-list safe:
783 */
784 hlist_add_head_rcu(&class->hash_entry, hash_head);
785 /*
786 * Add it to the global list of classes:
787 */
788 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
789
790 if (verbose(class)) {
791 graph_unlock();
792
793 printk("\nnew class %p: %s", class->key, class->name);
794 if (class->name_version > 1)
795 printk(KERN_CONT "#%d", class->name_version);
796 printk(KERN_CONT "\n");
797 dump_stack();
798
799 if (!graph_lock()) {
800 return NULL;
801 }
802 }
803out_unlock_set:
804 graph_unlock();
805
806out_set_class_cache:
807 if (!subclass || force)
808 lock->class_cache[0] = class;
809 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
810 lock->class_cache[subclass] = class;
811
812 /*
813 * Hash collision, did we smoke some? We found a class with a matching
814 * hash but the subclass -- which is hashed in -- didn't match.
815 */
816 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
817 return NULL;
818
819 return class;
820}
821
822#ifdef CONFIG_PROVE_LOCKING
823/*
824 * Allocate a lockdep entry. (assumes the graph_lock held, returns
825 * with NULL on failure)
826 */
827static struct lock_list *alloc_list_entry(void)
828{
829 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
830 if (!debug_locks_off_graph_unlock())
831 return NULL;
832
833 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
834 dump_stack();
835 return NULL;
836 }
837 return list_entries + nr_list_entries++;
838}
839
840/*
841 * Add a new dependency to the head of the list:
842 */
843static int add_lock_to_list(struct lock_class *this, struct list_head *head,
844 unsigned long ip, int distance,
845 struct stack_trace *trace)
846{
847 struct lock_list *entry;
848 /*
849 * Lock not present yet - get a new dependency struct and
850 * add it to the list:
851 */
852 entry = alloc_list_entry();
853 if (!entry)
854 return 0;
855
856 entry->class = this;
857 entry->distance = distance;
858 entry->trace = *trace;
859 /*
860 * Both allocation and removal are done under the graph lock; but
861 * iteration is under RCU-sched; see look_up_lock_class() and
862 * lockdep_free_key_range().
863 */
864 list_add_tail_rcu(&entry->entry, head);
865
866 return 1;
867}
868
869/*
870 * For good efficiency of modular, we use power of 2
871 */
872#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
873#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
874
875/*
876 * The circular_queue and helpers is used to implement the
877 * breadth-first search(BFS)algorithem, by which we can build
878 * the shortest path from the next lock to be acquired to the
879 * previous held lock if there is a circular between them.
880 */
881struct circular_queue {
882 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
883 unsigned int front, rear;
884};
885
886static struct circular_queue lock_cq;
887
888unsigned int max_bfs_queue_depth;
889
890static unsigned int lockdep_dependency_gen_id;
891
892static inline void __cq_init(struct circular_queue *cq)
893{
894 cq->front = cq->rear = 0;
895 lockdep_dependency_gen_id++;
896}
897
898static inline int __cq_empty(struct circular_queue *cq)
899{
900 return (cq->front == cq->rear);
901}
902
903static inline int __cq_full(struct circular_queue *cq)
904{
905 return ((cq->rear + 1) & CQ_MASK) == cq->front;
906}
907
908static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
909{
910 if (__cq_full(cq))
911 return -1;
912
913 cq->element[cq->rear] = elem;
914 cq->rear = (cq->rear + 1) & CQ_MASK;
915 return 0;
916}
917
918static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
919{
920 if (__cq_empty(cq))
921 return -1;
922
923 *elem = cq->element[cq->front];
924 cq->front = (cq->front + 1) & CQ_MASK;
925 return 0;
926}
927
928static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
929{
930 return (cq->rear - cq->front) & CQ_MASK;
931}
932
933static inline void mark_lock_accessed(struct lock_list *lock,
934 struct lock_list *parent)
935{
936 unsigned long nr;
937
938 nr = lock - list_entries;
939 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
940 lock->parent = parent;
941 lock->class->dep_gen_id = lockdep_dependency_gen_id;
942}
943
944static inline unsigned long lock_accessed(struct lock_list *lock)
945{
946 unsigned long nr;
947
948 nr = lock - list_entries;
949 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
950 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
951}
952
953static inline struct lock_list *get_lock_parent(struct lock_list *child)
954{
955 return child->parent;
956}
957
958static inline int get_lock_depth(struct lock_list *child)
959{
960 int depth = 0;
961 struct lock_list *parent;
962
963 while ((parent = get_lock_parent(child))) {
964 child = parent;
965 depth++;
966 }
967 return depth;
968}
969
970static int __bfs(struct lock_list *source_entry,
971 void *data,
972 int (*match)(struct lock_list *entry, void *data),
973 struct lock_list **target_entry,
974 int forward)
975{
976 struct lock_list *entry;
977 struct list_head *head;
978 struct circular_queue *cq = &lock_cq;
979 int ret = 1;
980
981 if (match(source_entry, data)) {
982 *target_entry = source_entry;
983 ret = 0;
984 goto exit;
985 }
986
987 if (forward)
988 head = &source_entry->class->locks_after;
989 else
990 head = &source_entry->class->locks_before;
991
992 if (list_empty(head))
993 goto exit;
994
995 __cq_init(cq);
996 __cq_enqueue(cq, (unsigned long)source_entry);
997
998 while (!__cq_empty(cq)) {
999 struct lock_list *lock;
1000
1001 __cq_dequeue(cq, (unsigned long *)&lock);
1002
1003 if (!lock->class) {
1004 ret = -2;
1005 goto exit;
1006 }
1007
1008 if (forward)
1009 head = &lock->class->locks_after;
1010 else
1011 head = &lock->class->locks_before;
1012
1013 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1014
1015 list_for_each_entry_rcu(entry, head, entry) {
1016 if (!lock_accessed(entry)) {
1017 unsigned int cq_depth;
1018 mark_lock_accessed(entry, lock);
1019 if (match(entry, data)) {
1020 *target_entry = entry;
1021 ret = 0;
1022 goto exit;
1023 }
1024
1025 if (__cq_enqueue(cq, (unsigned long)entry)) {
1026 ret = -1;
1027 goto exit;
1028 }
1029 cq_depth = __cq_get_elem_count(cq);
1030 if (max_bfs_queue_depth < cq_depth)
1031 max_bfs_queue_depth = cq_depth;
1032 }
1033 }
1034 }
1035exit:
1036 return ret;
1037}
1038
1039static inline int __bfs_forwards(struct lock_list *src_entry,
1040 void *data,
1041 int (*match)(struct lock_list *entry, void *data),
1042 struct lock_list **target_entry)
1043{
1044 return __bfs(src_entry, data, match, target_entry, 1);
1045
1046}
1047
1048static inline int __bfs_backwards(struct lock_list *src_entry,
1049 void *data,
1050 int (*match)(struct lock_list *entry, void *data),
1051 struct lock_list **target_entry)
1052{
1053 return __bfs(src_entry, data, match, target_entry, 0);
1054
1055}
1056
1057/*
1058 * Recursive, forwards-direction lock-dependency checking, used for
1059 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1060 * checking.
1061 */
1062
1063/*
1064 * Print a dependency chain entry (this is only done when a deadlock
1065 * has been detected):
1066 */
1067static noinline int
1068print_circular_bug_entry(struct lock_list *target, int depth)
1069{
1070 if (debug_locks_silent)
1071 return 0;
1072 printk("\n-> #%u", depth);
1073 print_lock_name(target->class);
1074 printk(KERN_CONT ":\n");
1075 print_stack_trace(&target->trace, 6);
1076
1077 return 0;
1078}
1079
1080static void
1081print_circular_lock_scenario(struct held_lock *src,
1082 struct held_lock *tgt,
1083 struct lock_list *prt)
1084{
1085 struct lock_class *source = hlock_class(src);
1086 struct lock_class *target = hlock_class(tgt);
1087 struct lock_class *parent = prt->class;
1088
1089 /*
1090 * A direct locking problem where unsafe_class lock is taken
1091 * directly by safe_class lock, then all we need to show
1092 * is the deadlock scenario, as it is obvious that the
1093 * unsafe lock is taken under the safe lock.
1094 *
1095 * But if there is a chain instead, where the safe lock takes
1096 * an intermediate lock (middle_class) where this lock is
1097 * not the same as the safe lock, then the lock chain is
1098 * used to describe the problem. Otherwise we would need
1099 * to show a different CPU case for each link in the chain
1100 * from the safe_class lock to the unsafe_class lock.
1101 */
1102 if (parent != source) {
1103 printk("Chain exists of:\n ");
1104 __print_lock_name(source);
1105 printk(KERN_CONT " --> ");
1106 __print_lock_name(parent);
1107 printk(KERN_CONT " --> ");
1108 __print_lock_name(target);
1109 printk(KERN_CONT "\n\n");
1110 }
1111
1112 printk(" Possible unsafe locking scenario:\n\n");
1113 printk(" CPU0 CPU1\n");
1114 printk(" ---- ----\n");
1115 printk(" lock(");
1116 __print_lock_name(target);
1117 printk(KERN_CONT ");\n");
1118 printk(" lock(");
1119 __print_lock_name(parent);
1120 printk(KERN_CONT ");\n");
1121 printk(" lock(");
1122 __print_lock_name(target);
1123 printk(KERN_CONT ");\n");
1124 printk(" lock(");
1125 __print_lock_name(source);
1126 printk(KERN_CONT ");\n");
1127 printk("\n *** DEADLOCK ***\n\n");
1128}
1129
1130/*
1131 * When a circular dependency is detected, print the
1132 * header first:
1133 */
1134static noinline int
1135print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1136 struct held_lock *check_src,
1137 struct held_lock *check_tgt)
1138{
1139 struct task_struct *curr = current;
1140
1141 if (debug_locks_silent)
1142 return 0;
1143
1144 printk("\n");
1145 printk("======================================================\n");
1146 printk("[ INFO: possible circular locking dependency detected ]\n");
1147 print_kernel_ident();
1148 printk("-------------------------------------------------------\n");
1149 printk("%s/%d is trying to acquire lock:\n",
1150 curr->comm, task_pid_nr(curr));
1151 print_lock(check_src);
1152 printk("\nbut task is already holding lock:\n");
1153 print_lock(check_tgt);
1154 printk("\nwhich lock already depends on the new lock.\n\n");
1155 printk("\nthe existing dependency chain (in reverse order) is:\n");
1156
1157 print_circular_bug_entry(entry, depth);
1158
1159 return 0;
1160}
1161
1162static inline int class_equal(struct lock_list *entry, void *data)
1163{
1164 return entry->class == data;
1165}
1166
1167static noinline int print_circular_bug(struct lock_list *this,
1168 struct lock_list *target,
1169 struct held_lock *check_src,
1170 struct held_lock *check_tgt)
1171{
1172 struct task_struct *curr = current;
1173 struct lock_list *parent;
1174 struct lock_list *first_parent;
1175 int depth;
1176
1177 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1178 return 0;
1179
1180 if (!save_trace(&this->trace))
1181 return 0;
1182
1183 depth = get_lock_depth(target);
1184
1185 print_circular_bug_header(target, depth, check_src, check_tgt);
1186
1187 parent = get_lock_parent(target);
1188 first_parent = parent;
1189
1190 while (parent) {
1191 print_circular_bug_entry(parent, --depth);
1192 parent = get_lock_parent(parent);
1193 }
1194
1195 printk("\nother info that might help us debug this:\n\n");
1196 print_circular_lock_scenario(check_src, check_tgt,
1197 first_parent);
1198
1199 lockdep_print_held_locks(curr);
1200
1201 printk("\nstack backtrace:\n");
1202 dump_stack();
1203
1204 return 0;
1205}
1206
1207static noinline int print_bfs_bug(int ret)
1208{
1209 if (!debug_locks_off_graph_unlock())
1210 return 0;
1211
1212 /*
1213 * Breadth-first-search failed, graph got corrupted?
1214 */
1215 WARN(1, "lockdep bfs error:%d\n", ret);
1216
1217 return 0;
1218}
1219
1220static int noop_count(struct lock_list *entry, void *data)
1221{
1222 (*(unsigned long *)data)++;
1223 return 0;
1224}
1225
1226static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1227{
1228 unsigned long count = 0;
1229 struct lock_list *uninitialized_var(target_entry);
1230
1231 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1232
1233 return count;
1234}
1235unsigned long lockdep_count_forward_deps(struct lock_class *class)
1236{
1237 unsigned long ret, flags;
1238 struct lock_list this;
1239
1240 this.parent = NULL;
1241 this.class = class;
1242
1243 local_irq_save(flags);
1244 arch_spin_lock(&lockdep_lock);
1245 ret = __lockdep_count_forward_deps(&this);
1246 arch_spin_unlock(&lockdep_lock);
1247 local_irq_restore(flags);
1248
1249 return ret;
1250}
1251
1252static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1253{
1254 unsigned long count = 0;
1255 struct lock_list *uninitialized_var(target_entry);
1256
1257 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1258
1259 return count;
1260}
1261
1262unsigned long lockdep_count_backward_deps(struct lock_class *class)
1263{
1264 unsigned long ret, flags;
1265 struct lock_list this;
1266
1267 this.parent = NULL;
1268 this.class = class;
1269
1270 local_irq_save(flags);
1271 arch_spin_lock(&lockdep_lock);
1272 ret = __lockdep_count_backward_deps(&this);
1273 arch_spin_unlock(&lockdep_lock);
1274 local_irq_restore(flags);
1275
1276 return ret;
1277}
1278
1279/*
1280 * Prove that the dependency graph starting at <entry> can not
1281 * lead to <target>. Print an error and return 0 if it does.
1282 */
1283static noinline int
1284check_noncircular(struct lock_list *root, struct lock_class *target,
1285 struct lock_list **target_entry)
1286{
1287 int result;
1288
1289 debug_atomic_inc(nr_cyclic_checks);
1290
1291 result = __bfs_forwards(root, target, class_equal, target_entry);
1292
1293 return result;
1294}
1295
1296#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1297/*
1298 * Forwards and backwards subgraph searching, for the purposes of
1299 * proving that two subgraphs can be connected by a new dependency
1300 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1301 */
1302
1303static inline int usage_match(struct lock_list *entry, void *bit)
1304{
1305 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1306}
1307
1308
1309
1310/*
1311 * Find a node in the forwards-direction dependency sub-graph starting
1312 * at @root->class that matches @bit.
1313 *
1314 * Return 0 if such a node exists in the subgraph, and put that node
1315 * into *@target_entry.
1316 *
1317 * Return 1 otherwise and keep *@target_entry unchanged.
1318 * Return <0 on error.
1319 */
1320static int
1321find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1322 struct lock_list **target_entry)
1323{
1324 int result;
1325
1326 debug_atomic_inc(nr_find_usage_forwards_checks);
1327
1328 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1329
1330 return result;
1331}
1332
1333/*
1334 * Find a node in the backwards-direction dependency sub-graph starting
1335 * at @root->class that matches @bit.
1336 *
1337 * Return 0 if such a node exists in the subgraph, and put that node
1338 * into *@target_entry.
1339 *
1340 * Return 1 otherwise and keep *@target_entry unchanged.
1341 * Return <0 on error.
1342 */
1343static int
1344find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1345 struct lock_list **target_entry)
1346{
1347 int result;
1348
1349 debug_atomic_inc(nr_find_usage_backwards_checks);
1350
1351 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1352
1353 return result;
1354}
1355
1356static void print_lock_class_header(struct lock_class *class, int depth)
1357{
1358 int bit;
1359
1360 printk("%*s->", depth, "");
1361 print_lock_name(class);
1362 printk(KERN_CONT " ops: %lu", class->ops);
1363 printk(KERN_CONT " {\n");
1364
1365 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1366 if (class->usage_mask & (1 << bit)) {
1367 int len = depth;
1368
1369 len += printk("%*s %s", depth, "", usage_str[bit]);
1370 len += printk(KERN_CONT " at:\n");
1371 print_stack_trace(class->usage_traces + bit, len);
1372 }
1373 }
1374 printk("%*s }\n", depth, "");
1375
1376 printk("%*s ... key at: [<%p>] %pS\n",
1377 depth, "", class->key, class->key);
1378}
1379
1380/*
1381 * printk the shortest lock dependencies from @start to @end in reverse order:
1382 */
1383static void __used
1384print_shortest_lock_dependencies(struct lock_list *leaf,
1385 struct lock_list *root)
1386{
1387 struct lock_list *entry = leaf;
1388 int depth;
1389
1390 /*compute depth from generated tree by BFS*/
1391 depth = get_lock_depth(leaf);
1392
1393 do {
1394 print_lock_class_header(entry->class, depth);
1395 printk("%*s ... acquired at:\n", depth, "");
1396 print_stack_trace(&entry->trace, 2);
1397 printk("\n");
1398
1399 if (depth == 0 && (entry != root)) {
1400 printk("lockdep:%s bad path found in chain graph\n", __func__);
1401 break;
1402 }
1403
1404 entry = get_lock_parent(entry);
1405 depth--;
1406 } while (entry && (depth >= 0));
1407
1408 return;
1409}
1410
1411static void
1412print_irq_lock_scenario(struct lock_list *safe_entry,
1413 struct lock_list *unsafe_entry,
1414 struct lock_class *prev_class,
1415 struct lock_class *next_class)
1416{
1417 struct lock_class *safe_class = safe_entry->class;
1418 struct lock_class *unsafe_class = unsafe_entry->class;
1419 struct lock_class *middle_class = prev_class;
1420
1421 if (middle_class == safe_class)
1422 middle_class = next_class;
1423
1424 /*
1425 * A direct locking problem where unsafe_class lock is taken
1426 * directly by safe_class lock, then all we need to show
1427 * is the deadlock scenario, as it is obvious that the
1428 * unsafe lock is taken under the safe lock.
1429 *
1430 * But if there is a chain instead, where the safe lock takes
1431 * an intermediate lock (middle_class) where this lock is
1432 * not the same as the safe lock, then the lock chain is
1433 * used to describe the problem. Otherwise we would need
1434 * to show a different CPU case for each link in the chain
1435 * from the safe_class lock to the unsafe_class lock.
1436 */
1437 if (middle_class != unsafe_class) {
1438 printk("Chain exists of:\n ");
1439 __print_lock_name(safe_class);
1440 printk(KERN_CONT " --> ");
1441 __print_lock_name(middle_class);
1442 printk(KERN_CONT " --> ");
1443 __print_lock_name(unsafe_class);
1444 printk(KERN_CONT "\n\n");
1445 }
1446
1447 printk(" Possible interrupt unsafe locking scenario:\n\n");
1448 printk(" CPU0 CPU1\n");
1449 printk(" ---- ----\n");
1450 printk(" lock(");
1451 __print_lock_name(unsafe_class);
1452 printk(KERN_CONT ");\n");
1453 printk(" local_irq_disable();\n");
1454 printk(" lock(");
1455 __print_lock_name(safe_class);
1456 printk(KERN_CONT ");\n");
1457 printk(" lock(");
1458 __print_lock_name(middle_class);
1459 printk(KERN_CONT ");\n");
1460 printk(" <Interrupt>\n");
1461 printk(" lock(");
1462 __print_lock_name(safe_class);
1463 printk(KERN_CONT ");\n");
1464 printk("\n *** DEADLOCK ***\n\n");
1465}
1466
1467static int
1468print_bad_irq_dependency(struct task_struct *curr,
1469 struct lock_list *prev_root,
1470 struct lock_list *next_root,
1471 struct lock_list *backwards_entry,
1472 struct lock_list *forwards_entry,
1473 struct held_lock *prev,
1474 struct held_lock *next,
1475 enum lock_usage_bit bit1,
1476 enum lock_usage_bit bit2,
1477 const char *irqclass)
1478{
1479 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1480 return 0;
1481
1482 printk("\n");
1483 printk("======================================================\n");
1484 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1485 irqclass, irqclass);
1486 print_kernel_ident();
1487 printk("------------------------------------------------------\n");
1488 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1489 curr->comm, task_pid_nr(curr),
1490 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1491 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1492 curr->hardirqs_enabled,
1493 curr->softirqs_enabled);
1494 print_lock(next);
1495
1496 printk("\nand this task is already holding:\n");
1497 print_lock(prev);
1498 printk("which would create a new lock dependency:\n");
1499 print_lock_name(hlock_class(prev));
1500 printk(KERN_CONT " ->");
1501 print_lock_name(hlock_class(next));
1502 printk(KERN_CONT "\n");
1503
1504 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1505 irqclass);
1506 print_lock_name(backwards_entry->class);
1507 printk("\n... which became %s-irq-safe at:\n", irqclass);
1508
1509 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1510
1511 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1512 print_lock_name(forwards_entry->class);
1513 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1514 printk("...");
1515
1516 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1517
1518 printk("\nother info that might help us debug this:\n\n");
1519 print_irq_lock_scenario(backwards_entry, forwards_entry,
1520 hlock_class(prev), hlock_class(next));
1521
1522 lockdep_print_held_locks(curr);
1523
1524 printk("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
1525 if (!save_trace(&prev_root->trace))
1526 return 0;
1527 print_shortest_lock_dependencies(backwards_entry, prev_root);
1528
1529 printk("\nthe dependencies between the lock to be acquired");
1530 printk(" and %s-irq-unsafe lock:\n", irqclass);
1531 if (!save_trace(&next_root->trace))
1532 return 0;
1533 print_shortest_lock_dependencies(forwards_entry, next_root);
1534
1535 printk("\nstack backtrace:\n");
1536 dump_stack();
1537
1538 return 0;
1539}
1540
1541static int
1542check_usage(struct task_struct *curr, struct held_lock *prev,
1543 struct held_lock *next, enum lock_usage_bit bit_backwards,
1544 enum lock_usage_bit bit_forwards, const char *irqclass)
1545{
1546 int ret;
1547 struct lock_list this, that;
1548 struct lock_list *uninitialized_var(target_entry);
1549 struct lock_list *uninitialized_var(target_entry1);
1550
1551 this.parent = NULL;
1552
1553 this.class = hlock_class(prev);
1554 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1555 if (ret < 0)
1556 return print_bfs_bug(ret);
1557 if (ret == 1)
1558 return ret;
1559
1560 that.parent = NULL;
1561 that.class = hlock_class(next);
1562 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1563 if (ret < 0)
1564 return print_bfs_bug(ret);
1565 if (ret == 1)
1566 return ret;
1567
1568 return print_bad_irq_dependency(curr, &this, &that,
1569 target_entry, target_entry1,
1570 prev, next,
1571 bit_backwards, bit_forwards, irqclass);
1572}
1573
1574static const char *state_names[] = {
1575#define LOCKDEP_STATE(__STATE) \
1576 __stringify(__STATE),
1577#include "lockdep_states.h"
1578#undef LOCKDEP_STATE
1579};
1580
1581static const char *state_rnames[] = {
1582#define LOCKDEP_STATE(__STATE) \
1583 __stringify(__STATE)"-READ",
1584#include "lockdep_states.h"
1585#undef LOCKDEP_STATE
1586};
1587
1588static inline const char *state_name(enum lock_usage_bit bit)
1589{
1590 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1591}
1592
1593static int exclusive_bit(int new_bit)
1594{
1595 /*
1596 * USED_IN
1597 * USED_IN_READ
1598 * ENABLED
1599 * ENABLED_READ
1600 *
1601 * bit 0 - write/read
1602 * bit 1 - used_in/enabled
1603 * bit 2+ state
1604 */
1605
1606 int state = new_bit & ~3;
1607 int dir = new_bit & 2;
1608
1609 /*
1610 * keep state, bit flip the direction and strip read.
1611 */
1612 return state | (dir ^ 2);
1613}
1614
1615static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1616 struct held_lock *next, enum lock_usage_bit bit)
1617{
1618 /*
1619 * Prove that the new dependency does not connect a hardirq-safe
1620 * lock with a hardirq-unsafe lock - to achieve this we search
1621 * the backwards-subgraph starting at <prev>, and the
1622 * forwards-subgraph starting at <next>:
1623 */
1624 if (!check_usage(curr, prev, next, bit,
1625 exclusive_bit(bit), state_name(bit)))
1626 return 0;
1627
1628 bit++; /* _READ */
1629
1630 /*
1631 * Prove that the new dependency does not connect a hardirq-safe-read
1632 * lock with a hardirq-unsafe lock - to achieve this we search
1633 * the backwards-subgraph starting at <prev>, and the
1634 * forwards-subgraph starting at <next>:
1635 */
1636 if (!check_usage(curr, prev, next, bit,
1637 exclusive_bit(bit), state_name(bit)))
1638 return 0;
1639
1640 return 1;
1641}
1642
1643static int
1644check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1645 struct held_lock *next)
1646{
1647#define LOCKDEP_STATE(__STATE) \
1648 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1649 return 0;
1650#include "lockdep_states.h"
1651#undef LOCKDEP_STATE
1652
1653 return 1;
1654}
1655
1656static void inc_chains(void)
1657{
1658 if (current->hardirq_context)
1659 nr_hardirq_chains++;
1660 else {
1661 if (current->softirq_context)
1662 nr_softirq_chains++;
1663 else
1664 nr_process_chains++;
1665 }
1666}
1667
1668#else
1669
1670static inline int
1671check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1672 struct held_lock *next)
1673{
1674 return 1;
1675}
1676
1677static inline void inc_chains(void)
1678{
1679 nr_process_chains++;
1680}
1681
1682#endif
1683
1684static void
1685print_deadlock_scenario(struct held_lock *nxt,
1686 struct held_lock *prv)
1687{
1688 struct lock_class *next = hlock_class(nxt);
1689 struct lock_class *prev = hlock_class(prv);
1690
1691 printk(" Possible unsafe locking scenario:\n\n");
1692 printk(" CPU0\n");
1693 printk(" ----\n");
1694 printk(" lock(");
1695 __print_lock_name(prev);
1696 printk(KERN_CONT ");\n");
1697 printk(" lock(");
1698 __print_lock_name(next);
1699 printk(KERN_CONT ");\n");
1700 printk("\n *** DEADLOCK ***\n\n");
1701 printk(" May be due to missing lock nesting notation\n\n");
1702}
1703
1704static int
1705print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1706 struct held_lock *next)
1707{
1708 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1709 return 0;
1710
1711 printk("\n");
1712 printk("=============================================\n");
1713 printk("[ INFO: possible recursive locking detected ]\n");
1714 print_kernel_ident();
1715 printk("---------------------------------------------\n");
1716 printk("%s/%d is trying to acquire lock:\n",
1717 curr->comm, task_pid_nr(curr));
1718 print_lock(next);
1719 printk("\nbut task is already holding lock:\n");
1720 print_lock(prev);
1721
1722 printk("\nother info that might help us debug this:\n");
1723 print_deadlock_scenario(next, prev);
1724 lockdep_print_held_locks(curr);
1725
1726 printk("\nstack backtrace:\n");
1727 dump_stack();
1728
1729 return 0;
1730}
1731
1732/*
1733 * Check whether we are holding such a class already.
1734 *
1735 * (Note that this has to be done separately, because the graph cannot
1736 * detect such classes of deadlocks.)
1737 *
1738 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1739 */
1740static int
1741check_deadlock(struct task_struct *curr, struct held_lock *next,
1742 struct lockdep_map *next_instance, int read)
1743{
1744 struct held_lock *prev;
1745 struct held_lock *nest = NULL;
1746 int i;
1747
1748 for (i = 0; i < curr->lockdep_depth; i++) {
1749 prev = curr->held_locks + i;
1750
1751 if (prev->instance == next->nest_lock)
1752 nest = prev;
1753
1754 if (hlock_class(prev) != hlock_class(next))
1755 continue;
1756
1757 /*
1758 * Allow read-after-read recursion of the same
1759 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1760 */
1761 if ((read == 2) && prev->read)
1762 return 2;
1763
1764 /*
1765 * We're holding the nest_lock, which serializes this lock's
1766 * nesting behaviour.
1767 */
1768 if (nest)
1769 return 2;
1770
1771 return print_deadlock_bug(curr, prev, next);
1772 }
1773 return 1;
1774}
1775
1776/*
1777 * There was a chain-cache miss, and we are about to add a new dependency
1778 * to a previous lock. We recursively validate the following rules:
1779 *
1780 * - would the adding of the <prev> -> <next> dependency create a
1781 * circular dependency in the graph? [== circular deadlock]
1782 *
1783 * - does the new prev->next dependency connect any hardirq-safe lock
1784 * (in the full backwards-subgraph starting at <prev>) with any
1785 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1786 * <next>)? [== illegal lock inversion with hardirq contexts]
1787 *
1788 * - does the new prev->next dependency connect any softirq-safe lock
1789 * (in the full backwards-subgraph starting at <prev>) with any
1790 * softirq-unsafe lock (in the full forwards-subgraph starting at
1791 * <next>)? [== illegal lock inversion with softirq contexts]
1792 *
1793 * any of these scenarios could lead to a deadlock.
1794 *
1795 * Then if all the validations pass, we add the forwards and backwards
1796 * dependency.
1797 */
1798static int
1799check_prev_add(struct task_struct *curr, struct held_lock *prev,
1800 struct held_lock *next, int distance, int *stack_saved)
1801{
1802 struct lock_list *entry;
1803 int ret;
1804 struct lock_list this;
1805 struct lock_list *uninitialized_var(target_entry);
1806 /*
1807 * Static variable, serialized by the graph_lock().
1808 *
1809 * We use this static variable to save the stack trace in case
1810 * we call into this function multiple times due to encountering
1811 * trylocks in the held lock stack.
1812 */
1813 static struct stack_trace trace;
1814
1815 /*
1816 * Prove that the new <prev> -> <next> dependency would not
1817 * create a circular dependency in the graph. (We do this by
1818 * forward-recursing into the graph starting at <next>, and
1819 * checking whether we can reach <prev>.)
1820 *
1821 * We are using global variables to control the recursion, to
1822 * keep the stackframe size of the recursive functions low:
1823 */
1824 this.class = hlock_class(next);
1825 this.parent = NULL;
1826 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1827 if (unlikely(!ret))
1828 return print_circular_bug(&this, target_entry, next, prev);
1829 else if (unlikely(ret < 0))
1830 return print_bfs_bug(ret);
1831
1832 if (!check_prev_add_irq(curr, prev, next))
1833 return 0;
1834
1835 /*
1836 * For recursive read-locks we do all the dependency checks,
1837 * but we dont store read-triggered dependencies (only
1838 * write-triggered dependencies). This ensures that only the
1839 * write-side dependencies matter, and that if for example a
1840 * write-lock never takes any other locks, then the reads are
1841 * equivalent to a NOP.
1842 */
1843 if (next->read == 2 || prev->read == 2)
1844 return 1;
1845 /*
1846 * Is the <prev> -> <next> dependency already present?
1847 *
1848 * (this may occur even though this is a new chain: consider
1849 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1850 * chains - the second one will be new, but L1 already has
1851 * L2 added to its dependency list, due to the first chain.)
1852 */
1853 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1854 if (entry->class == hlock_class(next)) {
1855 if (distance == 1)
1856 entry->distance = 1;
1857 return 2;
1858 }
1859 }
1860
1861 if (!*stack_saved) {
1862 if (!save_trace(&trace))
1863 return 0;
1864 *stack_saved = 1;
1865 }
1866
1867 /*
1868 * Ok, all validations passed, add the new lock
1869 * to the previous lock's dependency list:
1870 */
1871 ret = add_lock_to_list(hlock_class(next),
1872 &hlock_class(prev)->locks_after,
1873 next->acquire_ip, distance, &trace);
1874
1875 if (!ret)
1876 return 0;
1877
1878 ret = add_lock_to_list(hlock_class(prev),
1879 &hlock_class(next)->locks_before,
1880 next->acquire_ip, distance, &trace);
1881 if (!ret)
1882 return 0;
1883
1884 /*
1885 * Debugging printouts:
1886 */
1887 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1888 /* We drop graph lock, so another thread can overwrite trace. */
1889 *stack_saved = 0;
1890 graph_unlock();
1891 printk("\n new dependency: ");
1892 print_lock_name(hlock_class(prev));
1893 printk(KERN_CONT " => ");
1894 print_lock_name(hlock_class(next));
1895 printk(KERN_CONT "\n");
1896 dump_stack();
1897 return graph_lock();
1898 }
1899 return 1;
1900}
1901
1902/*
1903 * Add the dependency to all directly-previous locks that are 'relevant'.
1904 * The ones that are relevant are (in increasing distance from curr):
1905 * all consecutive trylock entries and the final non-trylock entry - or
1906 * the end of this context's lock-chain - whichever comes first.
1907 */
1908static int
1909check_prevs_add(struct task_struct *curr, struct held_lock *next)
1910{
1911 int depth = curr->lockdep_depth;
1912 int stack_saved = 0;
1913 struct held_lock *hlock;
1914
1915 /*
1916 * Debugging checks.
1917 *
1918 * Depth must not be zero for a non-head lock:
1919 */
1920 if (!depth)
1921 goto out_bug;
1922 /*
1923 * At least two relevant locks must exist for this
1924 * to be a head:
1925 */
1926 if (curr->held_locks[depth].irq_context !=
1927 curr->held_locks[depth-1].irq_context)
1928 goto out_bug;
1929
1930 for (;;) {
1931 int distance = curr->lockdep_depth - depth + 1;
1932 hlock = curr->held_locks + depth - 1;
1933 /*
1934 * Only non-recursive-read entries get new dependencies
1935 * added:
1936 */
1937 if (hlock->read != 2 && hlock->check) {
1938 if (!check_prev_add(curr, hlock, next,
1939 distance, &stack_saved))
1940 return 0;
1941 /*
1942 * Stop after the first non-trylock entry,
1943 * as non-trylock entries have added their
1944 * own direct dependencies already, so this
1945 * lock is connected to them indirectly:
1946 */
1947 if (!hlock->trylock)
1948 break;
1949 }
1950 depth--;
1951 /*
1952 * End of lock-stack?
1953 */
1954 if (!depth)
1955 break;
1956 /*
1957 * Stop the search if we cross into another context:
1958 */
1959 if (curr->held_locks[depth].irq_context !=
1960 curr->held_locks[depth-1].irq_context)
1961 break;
1962 }
1963 return 1;
1964out_bug:
1965 if (!debug_locks_off_graph_unlock())
1966 return 0;
1967
1968 /*
1969 * Clearly we all shouldn't be here, but since we made it we
1970 * can reliable say we messed up our state. See the above two
1971 * gotos for reasons why we could possibly end up here.
1972 */
1973 WARN_ON(1);
1974
1975 return 0;
1976}
1977
1978unsigned long nr_lock_chains;
1979struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1980int nr_chain_hlocks;
1981static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1982
1983struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1984{
1985 return lock_classes + chain_hlocks[chain->base + i];
1986}
1987
1988/*
1989 * Returns the index of the first held_lock of the current chain
1990 */
1991static inline int get_first_held_lock(struct task_struct *curr,
1992 struct held_lock *hlock)
1993{
1994 int i;
1995 struct held_lock *hlock_curr;
1996
1997 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1998 hlock_curr = curr->held_locks + i;
1999 if (hlock_curr->irq_context != hlock->irq_context)
2000 break;
2001
2002 }
2003
2004 return ++i;
2005}
2006
2007#ifdef CONFIG_DEBUG_LOCKDEP
2008/*
2009 * Returns the next chain_key iteration
2010 */
2011static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2012{
2013 u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2014
2015 printk(" class_idx:%d -> chain_key:%016Lx",
2016 class_idx,
2017 (unsigned long long)new_chain_key);
2018 return new_chain_key;
2019}
2020
2021static void
2022print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2023{
2024 struct held_lock *hlock;
2025 u64 chain_key = 0;
2026 int depth = curr->lockdep_depth;
2027 int i;
2028
2029 printk("depth: %u\n", depth + 1);
2030 for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
2031 hlock = curr->held_locks + i;
2032 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2033
2034 print_lock(hlock);
2035 }
2036
2037 print_chain_key_iteration(hlock_next->class_idx, chain_key);
2038 print_lock(hlock_next);
2039}
2040
2041static void print_chain_keys_chain(struct lock_chain *chain)
2042{
2043 int i;
2044 u64 chain_key = 0;
2045 int class_id;
2046
2047 printk("depth: %u\n", chain->depth);
2048 for (i = 0; i < chain->depth; i++) {
2049 class_id = chain_hlocks[chain->base + i];
2050 chain_key = print_chain_key_iteration(class_id + 1, chain_key);
2051
2052 print_lock_name(lock_classes + class_id);
2053 printk("\n");
2054 }
2055}
2056
2057static void print_collision(struct task_struct *curr,
2058 struct held_lock *hlock_next,
2059 struct lock_chain *chain)
2060{
2061 printk("\n");
2062 printk("======================\n");
2063 printk("[chain_key collision ]\n");
2064 print_kernel_ident();
2065 printk("----------------------\n");
2066 printk("%s/%d: ", current->comm, task_pid_nr(current));
2067 printk("Hash chain already cached but the contents don't match!\n");
2068
2069 printk("Held locks:");
2070 print_chain_keys_held_locks(curr, hlock_next);
2071
2072 printk("Locks in cached chain:");
2073 print_chain_keys_chain(chain);
2074
2075 printk("\nstack backtrace:\n");
2076 dump_stack();
2077}
2078#endif
2079
2080/*
2081 * Checks whether the chain and the current held locks are consistent
2082 * in depth and also in content. If they are not it most likely means
2083 * that there was a collision during the calculation of the chain_key.
2084 * Returns: 0 not passed, 1 passed
2085 */
2086static int check_no_collision(struct task_struct *curr,
2087 struct held_lock *hlock,
2088 struct lock_chain *chain)
2089{
2090#ifdef CONFIG_DEBUG_LOCKDEP
2091 int i, j, id;
2092
2093 i = get_first_held_lock(curr, hlock);
2094
2095 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2096 print_collision(curr, hlock, chain);
2097 return 0;
2098 }
2099
2100 for (j = 0; j < chain->depth - 1; j++, i++) {
2101 id = curr->held_locks[i].class_idx - 1;
2102
2103 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2104 print_collision(curr, hlock, chain);
2105 return 0;
2106 }
2107 }
2108#endif
2109 return 1;
2110}
2111
2112/*
2113 * Look up a dependency chain. If the key is not present yet then
2114 * add it and return 1 - in this case the new dependency chain is
2115 * validated. If the key is already hashed, return 0.
2116 * (On return with 1 graph_lock is held.)
2117 */
2118static inline int lookup_chain_cache(struct task_struct *curr,
2119 struct held_lock *hlock,
2120 u64 chain_key)
2121{
2122 struct lock_class *class = hlock_class(hlock);
2123 struct hlist_head *hash_head = chainhashentry(chain_key);
2124 struct lock_chain *chain;
2125 int i, j;
2126
2127 /*
2128 * We might need to take the graph lock, ensure we've got IRQs
2129 * disabled to make this an IRQ-safe lock.. for recursion reasons
2130 * lockdep won't complain about its own locking errors.
2131 */
2132 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2133 return 0;
2134 /*
2135 * We can walk it lock-free, because entries only get added
2136 * to the hash:
2137 */
2138 hlist_for_each_entry_rcu(chain, hash_head, entry) {
2139 if (chain->chain_key == chain_key) {
2140cache_hit:
2141 debug_atomic_inc(chain_lookup_hits);
2142 if (!check_no_collision(curr, hlock, chain))
2143 return 0;
2144
2145 if (very_verbose(class))
2146 printk("\nhash chain already cached, key: "
2147 "%016Lx tail class: [%p] %s\n",
2148 (unsigned long long)chain_key,
2149 class->key, class->name);
2150 return 0;
2151 }
2152 }
2153 if (very_verbose(class))
2154 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2155 (unsigned long long)chain_key, class->key, class->name);
2156 /*
2157 * Allocate a new chain entry from the static array, and add
2158 * it to the hash:
2159 */
2160 if (!graph_lock())
2161 return 0;
2162 /*
2163 * We have to walk the chain again locked - to avoid duplicates:
2164 */
2165 hlist_for_each_entry(chain, hash_head, entry) {
2166 if (chain->chain_key == chain_key) {
2167 graph_unlock();
2168 goto cache_hit;
2169 }
2170 }
2171 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2172 if (!debug_locks_off_graph_unlock())
2173 return 0;
2174
2175 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2176 dump_stack();
2177 return 0;
2178 }
2179 chain = lock_chains + nr_lock_chains++;
2180 chain->chain_key = chain_key;
2181 chain->irq_context = hlock->irq_context;
2182 i = get_first_held_lock(curr, hlock);
2183 chain->depth = curr->lockdep_depth + 1 - i;
2184
2185 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2186 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
2187 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2188
2189 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2190 chain->base = nr_chain_hlocks;
2191 for (j = 0; j < chain->depth - 1; j++, i++) {
2192 int lock_id = curr->held_locks[i].class_idx - 1;
2193 chain_hlocks[chain->base + j] = lock_id;
2194 }
2195 chain_hlocks[chain->base + j] = class - lock_classes;
2196 }
2197
2198 if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
2199 nr_chain_hlocks += chain->depth;
2200
2201#ifdef CONFIG_DEBUG_LOCKDEP
2202 /*
2203 * Important for check_no_collision().
2204 */
2205 if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
2206 if (debug_locks_off_graph_unlock())
2207 return 0;
2208
2209 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2210 dump_stack();
2211 return 0;
2212 }
2213#endif
2214
2215 hlist_add_head_rcu(&chain->entry, hash_head);
2216 debug_atomic_inc(chain_lookup_misses);
2217 inc_chains();
2218
2219 return 1;
2220}
2221
2222static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2223 struct held_lock *hlock, int chain_head, u64 chain_key)
2224{
2225 /*
2226 * Trylock needs to maintain the stack of held locks, but it
2227 * does not add new dependencies, because trylock can be done
2228 * in any order.
2229 *
2230 * We look up the chain_key and do the O(N^2) check and update of
2231 * the dependencies only if this is a new dependency chain.
2232 * (If lookup_chain_cache() returns with 1 it acquires
2233 * graph_lock for us)
2234 */
2235 if (!hlock->trylock && hlock->check &&
2236 lookup_chain_cache(curr, hlock, chain_key)) {
2237 /*
2238 * Check whether last held lock:
2239 *
2240 * - is irq-safe, if this lock is irq-unsafe
2241 * - is softirq-safe, if this lock is hardirq-unsafe
2242 *
2243 * And check whether the new lock's dependency graph
2244 * could lead back to the previous lock.
2245 *
2246 * any of these scenarios could lead to a deadlock. If
2247 * All validations
2248 */
2249 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2250
2251 if (!ret)
2252 return 0;
2253 /*
2254 * Mark recursive read, as we jump over it when
2255 * building dependencies (just like we jump over
2256 * trylock entries):
2257 */
2258 if (ret == 2)
2259 hlock->read = 2;
2260 /*
2261 * Add dependency only if this lock is not the head
2262 * of the chain, and if it's not a secondary read-lock:
2263 */
2264 if (!chain_head && ret != 2)
2265 if (!check_prevs_add(curr, hlock))
2266 return 0;
2267 graph_unlock();
2268 } else
2269 /* after lookup_chain_cache(): */
2270 if (unlikely(!debug_locks))
2271 return 0;
2272
2273 return 1;
2274}
2275#else
2276static inline int validate_chain(struct task_struct *curr,
2277 struct lockdep_map *lock, struct held_lock *hlock,
2278 int chain_head, u64 chain_key)
2279{
2280 return 1;
2281}
2282#endif
2283
2284/*
2285 * We are building curr_chain_key incrementally, so double-check
2286 * it from scratch, to make sure that it's done correctly:
2287 */
2288static void check_chain_key(struct task_struct *curr)
2289{
2290#ifdef CONFIG_DEBUG_LOCKDEP
2291 struct held_lock *hlock, *prev_hlock = NULL;
2292 unsigned int i;
2293 u64 chain_key = 0;
2294
2295 for (i = 0; i < curr->lockdep_depth; i++) {
2296 hlock = curr->held_locks + i;
2297 if (chain_key != hlock->prev_chain_key) {
2298 debug_locks_off();
2299 /*
2300 * We got mighty confused, our chain keys don't match
2301 * with what we expect, someone trample on our task state?
2302 */
2303 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2304 curr->lockdep_depth, i,
2305 (unsigned long long)chain_key,
2306 (unsigned long long)hlock->prev_chain_key);
2307 return;
2308 }
2309 /*
2310 * Whoops ran out of static storage again?
2311 */
2312 if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
2313 return;
2314
2315 if (prev_hlock && (prev_hlock->irq_context !=
2316 hlock->irq_context))
2317 chain_key = 0;
2318 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
2319 prev_hlock = hlock;
2320 }
2321 if (chain_key != curr->curr_chain_key) {
2322 debug_locks_off();
2323 /*
2324 * More smoking hash instead of calculating it, damn see these
2325 * numbers float.. I bet that a pink elephant stepped on my memory.
2326 */
2327 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2328 curr->lockdep_depth, i,
2329 (unsigned long long)chain_key,
2330 (unsigned long long)curr->curr_chain_key);
2331 }
2332#endif
2333}
2334
2335static void
2336print_usage_bug_scenario(struct held_lock *lock)
2337{
2338 struct lock_class *class = hlock_class(lock);
2339
2340 printk(" Possible unsafe locking scenario:\n\n");
2341 printk(" CPU0\n");
2342 printk(" ----\n");
2343 printk(" lock(");
2344 __print_lock_name(class);
2345 printk(KERN_CONT ");\n");
2346 printk(" <Interrupt>\n");
2347 printk(" lock(");
2348 __print_lock_name(class);
2349 printk(KERN_CONT ");\n");
2350 printk("\n *** DEADLOCK ***\n\n");
2351}
2352
2353static int
2354print_usage_bug(struct task_struct *curr, struct held_lock *this,
2355 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2356{
2357 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2358 return 0;
2359
2360 printk("\n");
2361 printk("=================================\n");
2362 printk("[ INFO: inconsistent lock state ]\n");
2363 print_kernel_ident();
2364 printk("---------------------------------\n");
2365
2366 printk("inconsistent {%s} -> {%s} usage.\n",
2367 usage_str[prev_bit], usage_str[new_bit]);
2368
2369 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2370 curr->comm, task_pid_nr(curr),
2371 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2372 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2373 trace_hardirqs_enabled(curr),
2374 trace_softirqs_enabled(curr));
2375 print_lock(this);
2376
2377 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2378 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2379
2380 print_irqtrace_events(curr);
2381 printk("\nother info that might help us debug this:\n");
2382 print_usage_bug_scenario(this);
2383
2384 lockdep_print_held_locks(curr);
2385
2386 printk("\nstack backtrace:\n");
2387 dump_stack();
2388
2389 return 0;
2390}
2391
2392/*
2393 * Print out an error if an invalid bit is set:
2394 */
2395static inline int
2396valid_state(struct task_struct *curr, struct held_lock *this,
2397 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2398{
2399 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2400 return print_usage_bug(curr, this, bad_bit, new_bit);
2401 return 1;
2402}
2403
2404static int mark_lock(struct task_struct *curr, struct held_lock *this,
2405 enum lock_usage_bit new_bit);
2406
2407#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2408
2409/*
2410 * print irq inversion bug:
2411 */
2412static int
2413print_irq_inversion_bug(struct task_struct *curr,
2414 struct lock_list *root, struct lock_list *other,
2415 struct held_lock *this, int forwards,
2416 const char *irqclass)
2417{
2418 struct lock_list *entry = other;
2419 struct lock_list *middle = NULL;
2420 int depth;
2421
2422 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2423 return 0;
2424
2425 printk("\n");
2426 printk("=========================================================\n");
2427 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2428 print_kernel_ident();
2429 printk("---------------------------------------------------------\n");
2430 printk("%s/%d just changed the state of lock:\n",
2431 curr->comm, task_pid_nr(curr));
2432 print_lock(this);
2433 if (forwards)
2434 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2435 else
2436 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2437 print_lock_name(other->class);
2438 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2439
2440 printk("\nother info that might help us debug this:\n");
2441
2442 /* Find a middle lock (if one exists) */
2443 depth = get_lock_depth(other);
2444 do {
2445 if (depth == 0 && (entry != root)) {
2446 printk("lockdep:%s bad path found in chain graph\n", __func__);
2447 break;
2448 }
2449 middle = entry;
2450 entry = get_lock_parent(entry);
2451 depth--;
2452 } while (entry && entry != root && (depth >= 0));
2453 if (forwards)
2454 print_irq_lock_scenario(root, other,
2455 middle ? middle->class : root->class, other->class);
2456 else
2457 print_irq_lock_scenario(other, root,
2458 middle ? middle->class : other->class, root->class);
2459
2460 lockdep_print_held_locks(curr);
2461
2462 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2463 if (!save_trace(&root->trace))
2464 return 0;
2465 print_shortest_lock_dependencies(other, root);
2466
2467 printk("\nstack backtrace:\n");
2468 dump_stack();
2469
2470 return 0;
2471}
2472
2473/*
2474 * Prove that in the forwards-direction subgraph starting at <this>
2475 * there is no lock matching <mask>:
2476 */
2477static int
2478check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2479 enum lock_usage_bit bit, const char *irqclass)
2480{
2481 int ret;
2482 struct lock_list root;
2483 struct lock_list *uninitialized_var(target_entry);
2484
2485 root.parent = NULL;
2486 root.class = hlock_class(this);
2487 ret = find_usage_forwards(&root, bit, &target_entry);
2488 if (ret < 0)
2489 return print_bfs_bug(ret);
2490 if (ret == 1)
2491 return ret;
2492
2493 return print_irq_inversion_bug(curr, &root, target_entry,
2494 this, 1, irqclass);
2495}
2496
2497/*
2498 * Prove that in the backwards-direction subgraph starting at <this>
2499 * there is no lock matching <mask>:
2500 */
2501static int
2502check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2503 enum lock_usage_bit bit, const char *irqclass)
2504{
2505 int ret;
2506 struct lock_list root;
2507 struct lock_list *uninitialized_var(target_entry);
2508
2509 root.parent = NULL;
2510 root.class = hlock_class(this);
2511 ret = find_usage_backwards(&root, bit, &target_entry);
2512 if (ret < 0)
2513 return print_bfs_bug(ret);
2514 if (ret == 1)
2515 return ret;
2516
2517 return print_irq_inversion_bug(curr, &root, target_entry,
2518 this, 0, irqclass);
2519}
2520
2521void print_irqtrace_events(struct task_struct *curr)
2522{
2523 printk("irq event stamp: %u\n", curr->irq_events);
2524 printk("hardirqs last enabled at (%u): [<%p>] %pS\n",
2525 curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
2526 (void *)curr->hardirq_enable_ip);
2527 printk("hardirqs last disabled at (%u): [<%p>] %pS\n",
2528 curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
2529 (void *)curr->hardirq_disable_ip);
2530 printk("softirqs last enabled at (%u): [<%p>] %pS\n",
2531 curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
2532 (void *)curr->softirq_enable_ip);
2533 printk("softirqs last disabled at (%u): [<%p>] %pS\n",
2534 curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
2535 (void *)curr->softirq_disable_ip);
2536}
2537
2538static int HARDIRQ_verbose(struct lock_class *class)
2539{
2540#if HARDIRQ_VERBOSE
2541 return class_filter(class);
2542#endif
2543 return 0;
2544}
2545
2546static int SOFTIRQ_verbose(struct lock_class *class)
2547{
2548#if SOFTIRQ_VERBOSE
2549 return class_filter(class);
2550#endif
2551 return 0;
2552}
2553
2554static int RECLAIM_FS_verbose(struct lock_class *class)
2555{
2556#if RECLAIM_VERBOSE
2557 return class_filter(class);
2558#endif
2559 return 0;
2560}
2561
2562#define STRICT_READ_CHECKS 1
2563
2564static int (*state_verbose_f[])(struct lock_class *class) = {
2565#define LOCKDEP_STATE(__STATE) \
2566 __STATE##_verbose,
2567#include "lockdep_states.h"
2568#undef LOCKDEP_STATE
2569};
2570
2571static inline int state_verbose(enum lock_usage_bit bit,
2572 struct lock_class *class)
2573{
2574 return state_verbose_f[bit >> 2](class);
2575}
2576
2577typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2578 enum lock_usage_bit bit, const char *name);
2579
2580static int
2581mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2582 enum lock_usage_bit new_bit)
2583{
2584 int excl_bit = exclusive_bit(new_bit);
2585 int read = new_bit & 1;
2586 int dir = new_bit & 2;
2587
2588 /*
2589 * mark USED_IN has to look forwards -- to ensure no dependency
2590 * has ENABLED state, which would allow recursion deadlocks.
2591 *
2592 * mark ENABLED has to look backwards -- to ensure no dependee
2593 * has USED_IN state, which, again, would allow recursion deadlocks.
2594 */
2595 check_usage_f usage = dir ?
2596 check_usage_backwards : check_usage_forwards;
2597
2598 /*
2599 * Validate that this particular lock does not have conflicting
2600 * usage states.
2601 */
2602 if (!valid_state(curr, this, new_bit, excl_bit))
2603 return 0;
2604
2605 /*
2606 * Validate that the lock dependencies don't have conflicting usage
2607 * states.
2608 */
2609 if ((!read || !dir || STRICT_READ_CHECKS) &&
2610 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2611 return 0;
2612
2613 /*
2614 * Check for read in write conflicts
2615 */
2616 if (!read) {
2617 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2618 return 0;
2619
2620 if (STRICT_READ_CHECKS &&
2621 !usage(curr, this, excl_bit + 1,
2622 state_name(new_bit + 1)))
2623 return 0;
2624 }
2625
2626 if (state_verbose(new_bit, hlock_class(this)))
2627 return 2;
2628
2629 return 1;
2630}
2631
2632enum mark_type {
2633#define LOCKDEP_STATE(__STATE) __STATE,
2634#include "lockdep_states.h"
2635#undef LOCKDEP_STATE
2636};
2637
2638/*
2639 * Mark all held locks with a usage bit:
2640 */
2641static int
2642mark_held_locks(struct task_struct *curr, enum mark_type mark)
2643{
2644 enum lock_usage_bit usage_bit;
2645 struct held_lock *hlock;
2646 int i;
2647
2648 for (i = 0; i < curr->lockdep_depth; i++) {
2649 hlock = curr->held_locks + i;
2650
2651 usage_bit = 2 + (mark << 2); /* ENABLED */
2652 if (hlock->read)
2653 usage_bit += 1; /* READ */
2654
2655 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2656
2657 if (!hlock->check)
2658 continue;
2659
2660 if (!mark_lock(curr, hlock, usage_bit))
2661 return 0;
2662 }
2663
2664 return 1;
2665}
2666
2667/*
2668 * Hardirqs will be enabled:
2669 */
2670static void __trace_hardirqs_on_caller(unsigned long ip)
2671{
2672 struct task_struct *curr = current;
2673
2674 /* we'll do an OFF -> ON transition: */
2675 curr->hardirqs_enabled = 1;
2676
2677 /*
2678 * We are going to turn hardirqs on, so set the
2679 * usage bit for all held locks:
2680 */
2681 if (!mark_held_locks(curr, HARDIRQ))
2682 return;
2683 /*
2684 * If we have softirqs enabled, then set the usage
2685 * bit for all held locks. (disabled hardirqs prevented
2686 * this bit from being set before)
2687 */
2688 if (curr->softirqs_enabled)
2689 if (!mark_held_locks(curr, SOFTIRQ))
2690 return;
2691
2692 curr->hardirq_enable_ip = ip;
2693 curr->hardirq_enable_event = ++curr->irq_events;
2694 debug_atomic_inc(hardirqs_on_events);
2695}
2696
2697__visible void trace_hardirqs_on_caller(unsigned long ip)
2698{
2699 time_hardirqs_on(CALLER_ADDR0, ip);
2700
2701 if (unlikely(!debug_locks || current->lockdep_recursion))
2702 return;
2703
2704 if (unlikely(current->hardirqs_enabled)) {
2705 /*
2706 * Neither irq nor preemption are disabled here
2707 * so this is racy by nature but losing one hit
2708 * in a stat is not a big deal.
2709 */
2710 __debug_atomic_inc(redundant_hardirqs_on);
2711 return;
2712 }
2713
2714 /*
2715 * We're enabling irqs and according to our state above irqs weren't
2716 * already enabled, yet we find the hardware thinks they are in fact
2717 * enabled.. someone messed up their IRQ state tracing.
2718 */
2719 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2720 return;
2721
2722 /*
2723 * See the fine text that goes along with this variable definition.
2724 */
2725 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2726 return;
2727
2728 /*
2729 * Can't allow enabling interrupts while in an interrupt handler,
2730 * that's general bad form and such. Recursion, limited stack etc..
2731 */
2732 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2733 return;
2734
2735 current->lockdep_recursion = 1;
2736 __trace_hardirqs_on_caller(ip);
2737 current->lockdep_recursion = 0;
2738}
2739EXPORT_SYMBOL(trace_hardirqs_on_caller);
2740
2741void trace_hardirqs_on(void)
2742{
2743 trace_hardirqs_on_caller(CALLER_ADDR0);
2744}
2745EXPORT_SYMBOL(trace_hardirqs_on);
2746
2747/*
2748 * Hardirqs were disabled:
2749 */
2750__visible void trace_hardirqs_off_caller(unsigned long ip)
2751{
2752 struct task_struct *curr = current;
2753
2754 time_hardirqs_off(CALLER_ADDR0, ip);
2755
2756 if (unlikely(!debug_locks || current->lockdep_recursion))
2757 return;
2758
2759 /*
2760 * So we're supposed to get called after you mask local IRQs, but for
2761 * some reason the hardware doesn't quite think you did a proper job.
2762 */
2763 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2764 return;
2765
2766 if (curr->hardirqs_enabled) {
2767 /*
2768 * We have done an ON -> OFF transition:
2769 */
2770 curr->hardirqs_enabled = 0;
2771 curr->hardirq_disable_ip = ip;
2772 curr->hardirq_disable_event = ++curr->irq_events;
2773 debug_atomic_inc(hardirqs_off_events);
2774 } else
2775 debug_atomic_inc(redundant_hardirqs_off);
2776}
2777EXPORT_SYMBOL(trace_hardirqs_off_caller);
2778
2779void trace_hardirqs_off(void)
2780{
2781 trace_hardirqs_off_caller(CALLER_ADDR0);
2782}
2783EXPORT_SYMBOL(trace_hardirqs_off);
2784
2785/*
2786 * Softirqs will be enabled:
2787 */
2788void trace_softirqs_on(unsigned long ip)
2789{
2790 struct task_struct *curr = current;
2791
2792 if (unlikely(!debug_locks || current->lockdep_recursion))
2793 return;
2794
2795 /*
2796 * We fancy IRQs being disabled here, see softirq.c, avoids
2797 * funny state and nesting things.
2798 */
2799 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2800 return;
2801
2802 if (curr->softirqs_enabled) {
2803 debug_atomic_inc(redundant_softirqs_on);
2804 return;
2805 }
2806
2807 current->lockdep_recursion = 1;
2808 /*
2809 * We'll do an OFF -> ON transition:
2810 */
2811 curr->softirqs_enabled = 1;
2812 curr->softirq_enable_ip = ip;
2813 curr->softirq_enable_event = ++curr->irq_events;
2814 debug_atomic_inc(softirqs_on_events);
2815 /*
2816 * We are going to turn softirqs on, so set the
2817 * usage bit for all held locks, if hardirqs are
2818 * enabled too:
2819 */
2820 if (curr->hardirqs_enabled)
2821 mark_held_locks(curr, SOFTIRQ);
2822 current->lockdep_recursion = 0;
2823}
2824
2825/*
2826 * Softirqs were disabled:
2827 */
2828void trace_softirqs_off(unsigned long ip)
2829{
2830 struct task_struct *curr = current;
2831
2832 if (unlikely(!debug_locks || current->lockdep_recursion))
2833 return;
2834
2835 /*
2836 * We fancy IRQs being disabled here, see softirq.c
2837 */
2838 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2839 return;
2840
2841 if (curr->softirqs_enabled) {
2842 /*
2843 * We have done an ON -> OFF transition:
2844 */
2845 curr->softirqs_enabled = 0;
2846 curr->softirq_disable_ip = ip;
2847 curr->softirq_disable_event = ++curr->irq_events;
2848 debug_atomic_inc(softirqs_off_events);
2849 /*
2850 * Whoops, we wanted softirqs off, so why aren't they?
2851 */
2852 DEBUG_LOCKS_WARN_ON(!softirq_count());
2853 } else
2854 debug_atomic_inc(redundant_softirqs_off);
2855}
2856
2857static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2858{
2859 struct task_struct *curr = current;
2860
2861 if (unlikely(!debug_locks))
2862 return;
2863
2864 /* no reclaim without waiting on it */
2865 if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
2866 return;
2867
2868 /* this guy won't enter reclaim */
2869 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2870 return;
2871
2872 /* We're only interested __GFP_FS allocations for now */
2873 if (!(gfp_mask & __GFP_FS))
2874 return;
2875
2876 /*
2877 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2878 */
2879 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2880 return;
2881
2882 mark_held_locks(curr, RECLAIM_FS);
2883}
2884
2885static void check_flags(unsigned long flags);
2886
2887void lockdep_trace_alloc(gfp_t gfp_mask)
2888{
2889 unsigned long flags;
2890
2891 if (unlikely(current->lockdep_recursion))
2892 return;
2893
2894 raw_local_irq_save(flags);
2895 check_flags(flags);
2896 current->lockdep_recursion = 1;
2897 __lockdep_trace_alloc(gfp_mask, flags);
2898 current->lockdep_recursion = 0;
2899 raw_local_irq_restore(flags);
2900}
2901
2902static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2903{
2904 /*
2905 * If non-trylock use in a hardirq or softirq context, then
2906 * mark the lock as used in these contexts:
2907 */
2908 if (!hlock->trylock) {
2909 if (hlock->read) {
2910 if (curr->hardirq_context)
2911 if (!mark_lock(curr, hlock,
2912 LOCK_USED_IN_HARDIRQ_READ))
2913 return 0;
2914 if (curr->softirq_context)
2915 if (!mark_lock(curr, hlock,
2916 LOCK_USED_IN_SOFTIRQ_READ))
2917 return 0;
2918 } else {
2919 if (curr->hardirq_context)
2920 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2921 return 0;
2922 if (curr->softirq_context)
2923 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2924 return 0;
2925 }
2926 }
2927 if (!hlock->hardirqs_off) {
2928 if (hlock->read) {
2929 if (!mark_lock(curr, hlock,
2930 LOCK_ENABLED_HARDIRQ_READ))
2931 return 0;
2932 if (curr->softirqs_enabled)
2933 if (!mark_lock(curr, hlock,
2934 LOCK_ENABLED_SOFTIRQ_READ))
2935 return 0;
2936 } else {
2937 if (!mark_lock(curr, hlock,
2938 LOCK_ENABLED_HARDIRQ))
2939 return 0;
2940 if (curr->softirqs_enabled)
2941 if (!mark_lock(curr, hlock,
2942 LOCK_ENABLED_SOFTIRQ))
2943 return 0;
2944 }
2945 }
2946
2947 /*
2948 * We reuse the irq context infrastructure more broadly as a general
2949 * context checking code. This tests GFP_FS recursion (a lock taken
2950 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2951 * allocation).
2952 */
2953 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2954 if (hlock->read) {
2955 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2956 return 0;
2957 } else {
2958 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2959 return 0;
2960 }
2961 }
2962
2963 return 1;
2964}
2965
2966static inline unsigned int task_irq_context(struct task_struct *task)
2967{
2968 return 2 * !!task->hardirq_context + !!task->softirq_context;
2969}
2970
2971static int separate_irq_context(struct task_struct *curr,
2972 struct held_lock *hlock)
2973{
2974 unsigned int depth = curr->lockdep_depth;
2975
2976 /*
2977 * Keep track of points where we cross into an interrupt context:
2978 */
2979 if (depth) {
2980 struct held_lock *prev_hlock;
2981
2982 prev_hlock = curr->held_locks + depth-1;
2983 /*
2984 * If we cross into another context, reset the
2985 * hash key (this also prevents the checking and the
2986 * adding of the dependency to 'prev'):
2987 */
2988 if (prev_hlock->irq_context != hlock->irq_context)
2989 return 1;
2990 }
2991 return 0;
2992}
2993
2994#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2995
2996static inline
2997int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2998 enum lock_usage_bit new_bit)
2999{
3000 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
3001 return 1;
3002}
3003
3004static inline int mark_irqflags(struct task_struct *curr,
3005 struct held_lock *hlock)
3006{
3007 return 1;
3008}
3009
3010static inline unsigned int task_irq_context(struct task_struct *task)
3011{
3012 return 0;
3013}
3014
3015static inline int separate_irq_context(struct task_struct *curr,
3016 struct held_lock *hlock)
3017{
3018 return 0;
3019}
3020
3021void lockdep_trace_alloc(gfp_t gfp_mask)
3022{
3023}
3024
3025#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3026
3027/*
3028 * Mark a lock with a usage bit, and validate the state transition:
3029 */
3030static int mark_lock(struct task_struct *curr, struct held_lock *this,
3031 enum lock_usage_bit new_bit)
3032{
3033 unsigned int new_mask = 1 << new_bit, ret = 1;
3034
3035 /*
3036 * If already set then do not dirty the cacheline,
3037 * nor do any checks:
3038 */
3039 if (likely(hlock_class(this)->usage_mask & new_mask))
3040 return 1;
3041
3042 if (!graph_lock())
3043 return 0;
3044 /*
3045 * Make sure we didn't race:
3046 */
3047 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3048 graph_unlock();
3049 return 1;
3050 }
3051
3052 hlock_class(this)->usage_mask |= new_mask;
3053
3054 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
3055 return 0;
3056
3057 switch (new_bit) {
3058#define LOCKDEP_STATE(__STATE) \
3059 case LOCK_USED_IN_##__STATE: \
3060 case LOCK_USED_IN_##__STATE##_READ: \
3061 case LOCK_ENABLED_##__STATE: \
3062 case LOCK_ENABLED_##__STATE##_READ:
3063#include "lockdep_states.h"
3064#undef LOCKDEP_STATE
3065 ret = mark_lock_irq(curr, this, new_bit);
3066 if (!ret)
3067 return 0;
3068 break;
3069 case LOCK_USED:
3070 debug_atomic_dec(nr_unused_locks);
3071 break;
3072 default:
3073 if (!debug_locks_off_graph_unlock())
3074 return 0;
3075 WARN_ON(1);
3076 return 0;
3077 }
3078
3079 graph_unlock();
3080
3081 /*
3082 * We must printk outside of the graph_lock:
3083 */
3084 if (ret == 2) {
3085 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3086 print_lock(this);
3087 print_irqtrace_events(curr);
3088 dump_stack();
3089 }
3090
3091 return ret;
3092}
3093
3094/*
3095 * Initialize a lock instance's lock-class mapping info:
3096 */
3097void lockdep_init_map(struct lockdep_map *lock, const char *name,
3098 struct lock_class_key *key, int subclass)
3099{
3100 int i;
3101
3102 kmemcheck_mark_initialized(lock, sizeof(*lock));
3103
3104 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3105 lock->class_cache[i] = NULL;
3106
3107#ifdef CONFIG_LOCK_STAT
3108 lock->cpu = raw_smp_processor_id();
3109#endif
3110
3111 /*
3112 * Can't be having no nameless bastards around this place!
3113 */
3114 if (DEBUG_LOCKS_WARN_ON(!name)) {
3115 lock->name = "NULL";
3116 return;
3117 }
3118
3119 lock->name = name;
3120
3121 /*
3122 * No key, no joy, we need to hash something.
3123 */
3124 if (DEBUG_LOCKS_WARN_ON(!key))
3125 return;
3126 /*
3127 * Sanity check, the lock-class key must be persistent:
3128 */
3129 if (!static_obj(key)) {
3130 printk("BUG: key %p not in .data!\n", key);
3131 /*
3132 * What it says above ^^^^^, I suggest you read it.
3133 */
3134 DEBUG_LOCKS_WARN_ON(1);
3135 return;
3136 }
3137 lock->key = key;
3138
3139 if (unlikely(!debug_locks))
3140 return;
3141
3142 if (subclass) {
3143 unsigned long flags;
3144
3145 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3146 return;
3147
3148 raw_local_irq_save(flags);
3149 current->lockdep_recursion = 1;
3150 register_lock_class(lock, subclass, 1);
3151 current->lockdep_recursion = 0;
3152 raw_local_irq_restore(flags);
3153 }
3154}
3155EXPORT_SYMBOL_GPL(lockdep_init_map);
3156
3157struct lock_class_key __lockdep_no_validate__;
3158EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3159
3160static int
3161print_lock_nested_lock_not_held(struct task_struct *curr,
3162 struct held_lock *hlock,
3163 unsigned long ip)
3164{
3165 if (!debug_locks_off())
3166 return 0;
3167 if (debug_locks_silent)
3168 return 0;
3169
3170 printk("\n");
3171 printk("==================================\n");
3172 printk("[ BUG: Nested lock was not taken ]\n");
3173 print_kernel_ident();
3174 printk("----------------------------------\n");
3175
3176 printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3177 print_lock(hlock);
3178
3179 printk("\nbut this task is not holding:\n");
3180 printk("%s\n", hlock->nest_lock->name);
3181
3182 printk("\nstack backtrace:\n");
3183 dump_stack();
3184
3185 printk("\nother info that might help us debug this:\n");
3186 lockdep_print_held_locks(curr);
3187
3188 printk("\nstack backtrace:\n");
3189 dump_stack();
3190
3191 return 0;
3192}
3193
3194static int __lock_is_held(struct lockdep_map *lock, int read);
3195
3196/*
3197 * This gets called for every mutex_lock*()/spin_lock*() operation.
3198 * We maintain the dependency maps and validate the locking attempt:
3199 */
3200static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3201 int trylock, int read, int check, int hardirqs_off,
3202 struct lockdep_map *nest_lock, unsigned long ip,
3203 int references, int pin_count)
3204{
3205 struct task_struct *curr = current;
3206 struct lock_class *class = NULL;
3207 struct held_lock *hlock;
3208 unsigned int depth;
3209 int chain_head = 0;
3210 int class_idx;
3211 u64 chain_key;
3212
3213 if (unlikely(!debug_locks))
3214 return 0;
3215
3216 /*
3217 * Lockdep should run with IRQs disabled, otherwise we could
3218 * get an interrupt which would want to take locks, which would
3219 * end up in lockdep and have you got a head-ache already?
3220 */
3221 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3222 return 0;
3223
3224 if (!prove_locking || lock->key == &__lockdep_no_validate__)
3225 check = 0;
3226
3227 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3228 class = lock->class_cache[subclass];
3229 /*
3230 * Not cached?
3231 */
3232 if (unlikely(!class)) {
3233 class = register_lock_class(lock, subclass, 0);
3234 if (!class)
3235 return 0;
3236 }
3237 atomic_inc((atomic_t *)&class->ops);
3238 if (very_verbose(class)) {
3239 printk("\nacquire class [%p] %s", class->key, class->name);
3240 if (class->name_version > 1)
3241 printk(KERN_CONT "#%d", class->name_version);
3242 printk(KERN_CONT "\n");
3243 dump_stack();
3244 }
3245
3246 /*
3247 * Add the lock to the list of currently held locks.
3248 * (we dont increase the depth just yet, up until the
3249 * dependency checks are done)
3250 */
3251 depth = curr->lockdep_depth;
3252 /*
3253 * Ran out of static storage for our per-task lock stack again have we?
3254 */
3255 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3256 return 0;
3257
3258 class_idx = class - lock_classes + 1;
3259
3260 if (depth) {
3261 hlock = curr->held_locks + depth - 1;
3262 if (hlock->class_idx == class_idx && nest_lock) {
3263 if (hlock->references)
3264 hlock->references++;
3265 else
3266 hlock->references = 2;
3267
3268 return 1;
3269 }
3270 }
3271
3272 hlock = curr->held_locks + depth;
3273 /*
3274 * Plain impossible, we just registered it and checked it weren't no
3275 * NULL like.. I bet this mushroom I ate was good!
3276 */
3277 if (DEBUG_LOCKS_WARN_ON(!class))
3278 return 0;
3279 hlock->class_idx = class_idx;
3280 hlock->acquire_ip = ip;
3281 hlock->instance = lock;
3282 hlock->nest_lock = nest_lock;
3283 hlock->irq_context = task_irq_context(curr);
3284 hlock->trylock = trylock;
3285 hlock->read = read;
3286 hlock->check = check;
3287 hlock->hardirqs_off = !!hardirqs_off;
3288 hlock->references = references;
3289#ifdef CONFIG_LOCK_STAT
3290 hlock->waittime_stamp = 0;
3291 hlock->holdtime_stamp = lockstat_clock();
3292#endif
3293 hlock->pin_count = pin_count;
3294
3295 if (check && !mark_irqflags(curr, hlock))
3296 return 0;
3297
3298 /* mark it as used: */
3299 if (!mark_lock(curr, hlock, LOCK_USED))
3300 return 0;
3301
3302 /*
3303 * Calculate the chain hash: it's the combined hash of all the
3304 * lock keys along the dependency chain. We save the hash value
3305 * at every step so that we can get the current hash easily
3306 * after unlock. The chain hash is then used to cache dependency
3307 * results.
3308 *
3309 * The 'key ID' is what is the most compact key value to drive
3310 * the hash, not class->key.
3311 */
3312 /*
3313 * Whoops, we did it again.. ran straight out of our static allocation.
3314 */
3315 if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
3316 return 0;
3317
3318 chain_key = curr->curr_chain_key;
3319 if (!depth) {
3320 /*
3321 * How can we have a chain hash when we ain't got no keys?!
3322 */
3323 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3324 return 0;
3325 chain_head = 1;
3326 }
3327
3328 hlock->prev_chain_key = chain_key;
3329 if (separate_irq_context(curr, hlock)) {
3330 chain_key = 0;
3331 chain_head = 1;
3332 }
3333 chain_key = iterate_chain_key(chain_key, class_idx);
3334
3335 if (nest_lock && !__lock_is_held(nest_lock, -1))
3336 return print_lock_nested_lock_not_held(curr, hlock, ip);
3337
3338 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3339 return 0;
3340
3341 curr->curr_chain_key = chain_key;
3342 curr->lockdep_depth++;
3343 check_chain_key(curr);
3344#ifdef CONFIG_DEBUG_LOCKDEP
3345 if (unlikely(!debug_locks))
3346 return 0;
3347#endif
3348 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3349 debug_locks_off();
3350 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3351 printk(KERN_DEBUG "depth: %i max: %lu!\n",
3352 curr->lockdep_depth, MAX_LOCK_DEPTH);
3353
3354 lockdep_print_held_locks(current);
3355 debug_show_all_locks();
3356 dump_stack();
3357
3358 return 0;
3359 }
3360
3361 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3362 max_lockdep_depth = curr->lockdep_depth;
3363
3364 return 1;
3365}
3366
3367static int
3368print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3369 unsigned long ip)
3370{
3371 if (!debug_locks_off())
3372 return 0;
3373 if (debug_locks_silent)
3374 return 0;
3375
3376 printk("\n");
3377 printk("=====================================\n");
3378 printk("[ BUG: bad unlock balance detected! ]\n");
3379 print_kernel_ident();
3380 printk("-------------------------------------\n");
3381 printk("%s/%d is trying to release lock (",
3382 curr->comm, task_pid_nr(curr));
3383 print_lockdep_cache(lock);
3384 printk(KERN_CONT ") at:\n");
3385 print_ip_sym(ip);
3386 printk("but there are no more locks to release!\n");
3387 printk("\nother info that might help us debug this:\n");
3388 lockdep_print_held_locks(curr);
3389
3390 printk("\nstack backtrace:\n");
3391 dump_stack();
3392
3393 return 0;
3394}
3395
3396static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3397{
3398 if (hlock->instance == lock)
3399 return 1;
3400
3401 if (hlock->references) {
3402 struct lock_class *class = lock->class_cache[0];
3403
3404 if (!class)
3405 class = look_up_lock_class(lock, 0);
3406
3407 /*
3408 * If look_up_lock_class() failed to find a class, we're trying
3409 * to test if we hold a lock that has never yet been acquired.
3410 * Clearly if the lock hasn't been acquired _ever_, we're not
3411 * holding it either, so report failure.
3412 */
3413 if (!class)
3414 return 0;
3415
3416 /*
3417 * References, but not a lock we're actually ref-counting?
3418 * State got messed up, follow the sites that change ->references
3419 * and try to make sense of it.
3420 */
3421 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3422 return 0;
3423
3424 if (hlock->class_idx == class - lock_classes + 1)
3425 return 1;
3426 }
3427
3428 return 0;
3429}
3430
3431static int
3432__lock_set_class(struct lockdep_map *lock, const char *name,
3433 struct lock_class_key *key, unsigned int subclass,
3434 unsigned long ip)
3435{
3436 struct task_struct *curr = current;
3437 struct held_lock *hlock, *prev_hlock;
3438 struct lock_class *class;
3439 unsigned int depth;
3440 int i;
3441
3442 depth = curr->lockdep_depth;
3443 /*
3444 * This function is about (re)setting the class of a held lock,
3445 * yet we're not actually holding any locks. Naughty user!
3446 */
3447 if (DEBUG_LOCKS_WARN_ON(!depth))
3448 return 0;
3449
3450 prev_hlock = NULL;
3451 for (i = depth-1; i >= 0; i--) {
3452 hlock = curr->held_locks + i;
3453 /*
3454 * We must not cross into another context:
3455 */
3456 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3457 break;
3458 if (match_held_lock(hlock, lock))
3459 goto found_it;
3460 prev_hlock = hlock;
3461 }
3462 return print_unlock_imbalance_bug(curr, lock, ip);
3463
3464found_it:
3465 lockdep_init_map(lock, name, key, 0);
3466 class = register_lock_class(lock, subclass, 0);
3467 hlock->class_idx = class - lock_classes + 1;
3468
3469 curr->lockdep_depth = i;
3470 curr->curr_chain_key = hlock->prev_chain_key;
3471
3472 for (; i < depth; i++) {
3473 hlock = curr->held_locks + i;
3474 if (!__lock_acquire(hlock->instance,
3475 hlock_class(hlock)->subclass, hlock->trylock,
3476 hlock->read, hlock->check, hlock->hardirqs_off,
3477 hlock->nest_lock, hlock->acquire_ip,
3478 hlock->references, hlock->pin_count))
3479 return 0;
3480 }
3481
3482 /*
3483 * I took it apart and put it back together again, except now I have
3484 * these 'spare' parts.. where shall I put them.
3485 */
3486 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3487 return 0;
3488 return 1;
3489}
3490
3491/*
3492 * Remove the lock to the list of currently held locks - this gets
3493 * called on mutex_unlock()/spin_unlock*() (or on a failed
3494 * mutex_lock_interruptible()).
3495 *
3496 * @nested is an hysterical artifact, needs a tree wide cleanup.
3497 */
3498static int
3499__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3500{
3501 struct task_struct *curr = current;
3502 struct held_lock *hlock, *prev_hlock;
3503 unsigned int depth;
3504 int i;
3505
3506 if (unlikely(!debug_locks))
3507 return 0;
3508
3509 depth = curr->lockdep_depth;
3510 /*
3511 * So we're all set to release this lock.. wait what lock? We don't
3512 * own any locks, you've been drinking again?
3513 */
3514 if (DEBUG_LOCKS_WARN_ON(depth <= 0))
3515 return print_unlock_imbalance_bug(curr, lock, ip);
3516
3517 /*
3518 * Check whether the lock exists in the current stack
3519 * of held locks:
3520 */
3521 prev_hlock = NULL;
3522 for (i = depth-1; i >= 0; i--) {
3523 hlock = curr->held_locks + i;
3524 /*
3525 * We must not cross into another context:
3526 */
3527 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3528 break;
3529 if (match_held_lock(hlock, lock))
3530 goto found_it;
3531 prev_hlock = hlock;
3532 }
3533 return print_unlock_imbalance_bug(curr, lock, ip);
3534
3535found_it:
3536 if (hlock->instance == lock)
3537 lock_release_holdtime(hlock);
3538
3539 WARN(hlock->pin_count, "releasing a pinned lock\n");
3540
3541 if (hlock->references) {
3542 hlock->references--;
3543 if (hlock->references) {
3544 /*
3545 * We had, and after removing one, still have
3546 * references, the current lock stack is still
3547 * valid. We're done!
3548 */
3549 return 1;
3550 }
3551 }
3552
3553 /*
3554 * We have the right lock to unlock, 'hlock' points to it.
3555 * Now we remove it from the stack, and add back the other
3556 * entries (if any), recalculating the hash along the way:
3557 */
3558
3559 curr->lockdep_depth = i;
3560 curr->curr_chain_key = hlock->prev_chain_key;
3561
3562 for (i++; i < depth; i++) {
3563 hlock = curr->held_locks + i;
3564 if (!__lock_acquire(hlock->instance,
3565 hlock_class(hlock)->subclass, hlock->trylock,
3566 hlock->read, hlock->check, hlock->hardirqs_off,
3567 hlock->nest_lock, hlock->acquire_ip,
3568 hlock->references, hlock->pin_count))
3569 return 0;
3570 }
3571
3572 /*
3573 * We had N bottles of beer on the wall, we drank one, but now
3574 * there's not N-1 bottles of beer left on the wall...
3575 */
3576 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3577 return 0;
3578
3579 return 1;
3580}
3581
3582static int __lock_is_held(struct lockdep_map *lock, int read)
3583{
3584 struct task_struct *curr = current;
3585 int i;
3586
3587 for (i = 0; i < curr->lockdep_depth; i++) {
3588 struct held_lock *hlock = curr->held_locks + i;
3589
3590 if (match_held_lock(hlock, lock)) {
3591 if (read == -1 || hlock->read == read)
3592 return 1;
3593
3594 return 0;
3595 }
3596 }
3597
3598 return 0;
3599}
3600
3601static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
3602{
3603 struct pin_cookie cookie = NIL_COOKIE;
3604 struct task_struct *curr = current;
3605 int i;
3606
3607 if (unlikely(!debug_locks))
3608 return cookie;
3609
3610 for (i = 0; i < curr->lockdep_depth; i++) {
3611 struct held_lock *hlock = curr->held_locks + i;
3612
3613 if (match_held_lock(hlock, lock)) {
3614 /*
3615 * Grab 16bits of randomness; this is sufficient to not
3616 * be guessable and still allows some pin nesting in
3617 * our u32 pin_count.
3618 */
3619 cookie.val = 1 + (prandom_u32() >> 16);
3620 hlock->pin_count += cookie.val;
3621 return cookie;
3622 }
3623 }
3624
3625 WARN(1, "pinning an unheld lock\n");
3626 return cookie;
3627}
3628
3629static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3630{
3631 struct task_struct *curr = current;
3632 int i;
3633
3634 if (unlikely(!debug_locks))
3635 return;
3636
3637 for (i = 0; i < curr->lockdep_depth; i++) {
3638 struct held_lock *hlock = curr->held_locks + i;
3639
3640 if (match_held_lock(hlock, lock)) {
3641 hlock->pin_count += cookie.val;
3642 return;
3643 }
3644 }
3645
3646 WARN(1, "pinning an unheld lock\n");
3647}
3648
3649static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3650{
3651 struct task_struct *curr = current;
3652 int i;
3653
3654 if (unlikely(!debug_locks))
3655 return;
3656
3657 for (i = 0; i < curr->lockdep_depth; i++) {
3658 struct held_lock *hlock = curr->held_locks + i;
3659
3660 if (match_held_lock(hlock, lock)) {
3661 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
3662 return;
3663
3664 hlock->pin_count -= cookie.val;
3665
3666 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
3667 hlock->pin_count = 0;
3668
3669 return;
3670 }
3671 }
3672
3673 WARN(1, "unpinning an unheld lock\n");
3674}
3675
3676/*
3677 * Check whether we follow the irq-flags state precisely:
3678 */
3679static void check_flags(unsigned long flags)
3680{
3681#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3682 defined(CONFIG_TRACE_IRQFLAGS)
3683 if (!debug_locks)
3684 return;
3685
3686 if (irqs_disabled_flags(flags)) {
3687 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3688 printk("possible reason: unannotated irqs-off.\n");
3689 }
3690 } else {
3691 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3692 printk("possible reason: unannotated irqs-on.\n");
3693 }
3694 }
3695
3696 /*
3697 * We dont accurately track softirq state in e.g.
3698 * hardirq contexts (such as on 4KSTACKS), so only
3699 * check if not in hardirq contexts:
3700 */
3701 if (!hardirq_count()) {
3702 if (softirq_count()) {
3703 /* like the above, but with softirqs */
3704 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3705 } else {
3706 /* lick the above, does it taste good? */
3707 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3708 }
3709 }
3710
3711 if (!debug_locks)
3712 print_irqtrace_events(current);
3713#endif
3714}
3715
3716void lock_set_class(struct lockdep_map *lock, const char *name,
3717 struct lock_class_key *key, unsigned int subclass,
3718 unsigned long ip)
3719{
3720 unsigned long flags;
3721
3722 if (unlikely(current->lockdep_recursion))
3723 return;
3724
3725 raw_local_irq_save(flags);
3726 current->lockdep_recursion = 1;
3727 check_flags(flags);
3728 if (__lock_set_class(lock, name, key, subclass, ip))
3729 check_chain_key(current);
3730 current->lockdep_recursion = 0;
3731 raw_local_irq_restore(flags);
3732}
3733EXPORT_SYMBOL_GPL(lock_set_class);
3734
3735/*
3736 * We are not always called with irqs disabled - do that here,
3737 * and also avoid lockdep recursion:
3738 */
3739void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3740 int trylock, int read, int check,
3741 struct lockdep_map *nest_lock, unsigned long ip)
3742{
3743 unsigned long flags;
3744
3745 if (unlikely(current->lockdep_recursion))
3746 return;
3747
3748 raw_local_irq_save(flags);
3749 check_flags(flags);
3750
3751 current->lockdep_recursion = 1;
3752 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3753 __lock_acquire(lock, subclass, trylock, read, check,
3754 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
3755 current->lockdep_recursion = 0;
3756 raw_local_irq_restore(flags);
3757}
3758EXPORT_SYMBOL_GPL(lock_acquire);
3759
3760void lock_release(struct lockdep_map *lock, int nested,
3761 unsigned long ip)
3762{
3763 unsigned long flags;
3764
3765 if (unlikely(current->lockdep_recursion))
3766 return;
3767
3768 raw_local_irq_save(flags);
3769 check_flags(flags);
3770 current->lockdep_recursion = 1;
3771 trace_lock_release(lock, ip);
3772 if (__lock_release(lock, nested, ip))
3773 check_chain_key(current);
3774 current->lockdep_recursion = 0;
3775 raw_local_irq_restore(flags);
3776}
3777EXPORT_SYMBOL_GPL(lock_release);
3778
3779int lock_is_held_type(struct lockdep_map *lock, int read)
3780{
3781 unsigned long flags;
3782 int ret = 0;
3783
3784 if (unlikely(current->lockdep_recursion))
3785 return 1; /* avoid false negative lockdep_assert_held() */
3786
3787 raw_local_irq_save(flags);
3788 check_flags(flags);
3789
3790 current->lockdep_recursion = 1;
3791 ret = __lock_is_held(lock, read);
3792 current->lockdep_recursion = 0;
3793 raw_local_irq_restore(flags);
3794
3795 return ret;
3796}
3797EXPORT_SYMBOL_GPL(lock_is_held_type);
3798
3799struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
3800{
3801 struct pin_cookie cookie = NIL_COOKIE;
3802 unsigned long flags;
3803
3804 if (unlikely(current->lockdep_recursion))
3805 return cookie;
3806
3807 raw_local_irq_save(flags);
3808 check_flags(flags);
3809
3810 current->lockdep_recursion = 1;
3811 cookie = __lock_pin_lock(lock);
3812 current->lockdep_recursion = 0;
3813 raw_local_irq_restore(flags);
3814
3815 return cookie;
3816}
3817EXPORT_SYMBOL_GPL(lock_pin_lock);
3818
3819void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3820{
3821 unsigned long flags;
3822
3823 if (unlikely(current->lockdep_recursion))
3824 return;
3825
3826 raw_local_irq_save(flags);
3827 check_flags(flags);
3828
3829 current->lockdep_recursion = 1;
3830 __lock_repin_lock(lock, cookie);
3831 current->lockdep_recursion = 0;
3832 raw_local_irq_restore(flags);
3833}
3834EXPORT_SYMBOL_GPL(lock_repin_lock);
3835
3836void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3837{
3838 unsigned long flags;
3839
3840 if (unlikely(current->lockdep_recursion))
3841 return;
3842
3843 raw_local_irq_save(flags);
3844 check_flags(flags);
3845
3846 current->lockdep_recursion = 1;
3847 __lock_unpin_lock(lock, cookie);
3848 current->lockdep_recursion = 0;
3849 raw_local_irq_restore(flags);
3850}
3851EXPORT_SYMBOL_GPL(lock_unpin_lock);
3852
3853void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3854{
3855 current->lockdep_reclaim_gfp = gfp_mask;
3856}
3857
3858void lockdep_clear_current_reclaim_state(void)
3859{
3860 current->lockdep_reclaim_gfp = 0;
3861}
3862
3863#ifdef CONFIG_LOCK_STAT
3864static int
3865print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3866 unsigned long ip)
3867{
3868 if (!debug_locks_off())
3869 return 0;
3870 if (debug_locks_silent)
3871 return 0;
3872
3873 printk("\n");
3874 printk("=================================\n");
3875 printk("[ BUG: bad contention detected! ]\n");
3876 print_kernel_ident();
3877 printk("---------------------------------\n");
3878 printk("%s/%d is trying to contend lock (",
3879 curr->comm, task_pid_nr(curr));
3880 print_lockdep_cache(lock);
3881 printk(KERN_CONT ") at:\n");
3882 print_ip_sym(ip);
3883 printk("but there are no locks held!\n");
3884 printk("\nother info that might help us debug this:\n");
3885 lockdep_print_held_locks(curr);
3886
3887 printk("\nstack backtrace:\n");
3888 dump_stack();
3889
3890 return 0;
3891}
3892
3893static void
3894__lock_contended(struct lockdep_map *lock, unsigned long ip)
3895{
3896 struct task_struct *curr = current;
3897 struct held_lock *hlock, *prev_hlock;
3898 struct lock_class_stats *stats;
3899 unsigned int depth;
3900 int i, contention_point, contending_point;
3901
3902 depth = curr->lockdep_depth;
3903 /*
3904 * Whee, we contended on this lock, except it seems we're not
3905 * actually trying to acquire anything much at all..
3906 */
3907 if (DEBUG_LOCKS_WARN_ON(!depth))
3908 return;
3909
3910 prev_hlock = NULL;
3911 for (i = depth-1; i >= 0; i--) {
3912 hlock = curr->held_locks + i;
3913 /*
3914 * We must not cross into another context:
3915 */
3916 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3917 break;
3918 if (match_held_lock(hlock, lock))
3919 goto found_it;
3920 prev_hlock = hlock;
3921 }
3922 print_lock_contention_bug(curr, lock, ip);
3923 return;
3924
3925found_it:
3926 if (hlock->instance != lock)
3927 return;
3928
3929 hlock->waittime_stamp = lockstat_clock();
3930
3931 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3932 contending_point = lock_point(hlock_class(hlock)->contending_point,
3933 lock->ip);
3934
3935 stats = get_lock_stats(hlock_class(hlock));
3936 if (contention_point < LOCKSTAT_POINTS)
3937 stats->contention_point[contention_point]++;
3938 if (contending_point < LOCKSTAT_POINTS)
3939 stats->contending_point[contending_point]++;
3940 if (lock->cpu != smp_processor_id())
3941 stats->bounces[bounce_contended + !!hlock->read]++;
3942 put_lock_stats(stats);
3943}
3944
3945static void
3946__lock_acquired(struct lockdep_map *lock, unsigned long ip)
3947{
3948 struct task_struct *curr = current;
3949 struct held_lock *hlock, *prev_hlock;
3950 struct lock_class_stats *stats;
3951 unsigned int depth;
3952 u64 now, waittime = 0;
3953 int i, cpu;
3954
3955 depth = curr->lockdep_depth;
3956 /*
3957 * Yay, we acquired ownership of this lock we didn't try to
3958 * acquire, how the heck did that happen?
3959 */
3960 if (DEBUG_LOCKS_WARN_ON(!depth))
3961 return;
3962
3963 prev_hlock = NULL;
3964 for (i = depth-1; i >= 0; i--) {
3965 hlock = curr->held_locks + i;
3966 /*
3967 * We must not cross into another context:
3968 */
3969 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3970 break;
3971 if (match_held_lock(hlock, lock))
3972 goto found_it;
3973 prev_hlock = hlock;
3974 }
3975 print_lock_contention_bug(curr, lock, _RET_IP_);
3976 return;
3977
3978found_it:
3979 if (hlock->instance != lock)
3980 return;
3981
3982 cpu = smp_processor_id();
3983 if (hlock->waittime_stamp) {
3984 now = lockstat_clock();
3985 waittime = now - hlock->waittime_stamp;
3986 hlock->holdtime_stamp = now;
3987 }
3988
3989 trace_lock_acquired(lock, ip);
3990
3991 stats = get_lock_stats(hlock_class(hlock));
3992 if (waittime) {
3993 if (hlock->read)
3994 lock_time_inc(&stats->read_waittime, waittime);
3995 else
3996 lock_time_inc(&stats->write_waittime, waittime);
3997 }
3998 if (lock->cpu != cpu)
3999 stats->bounces[bounce_acquired + !!hlock->read]++;
4000 put_lock_stats(stats);
4001
4002 lock->cpu = cpu;
4003 lock->ip = ip;
4004}
4005
4006void lock_contended(struct lockdep_map *lock, unsigned long ip)
4007{
4008 unsigned long flags;
4009
4010 if (unlikely(!lock_stat))
4011 return;
4012
4013 if (unlikely(current->lockdep_recursion))
4014 return;
4015
4016 raw_local_irq_save(flags);
4017 check_flags(flags);
4018 current->lockdep_recursion = 1;
4019 trace_lock_contended(lock, ip);
4020 __lock_contended(lock, ip);
4021 current->lockdep_recursion = 0;
4022 raw_local_irq_restore(flags);
4023}
4024EXPORT_SYMBOL_GPL(lock_contended);
4025
4026void lock_acquired(struct lockdep_map *lock, unsigned long ip)
4027{
4028 unsigned long flags;
4029
4030 if (unlikely(!lock_stat))
4031 return;
4032
4033 if (unlikely(current->lockdep_recursion))
4034 return;
4035
4036 raw_local_irq_save(flags);
4037 check_flags(flags);
4038 current->lockdep_recursion = 1;
4039 __lock_acquired(lock, ip);
4040 current->lockdep_recursion = 0;
4041 raw_local_irq_restore(flags);
4042}
4043EXPORT_SYMBOL_GPL(lock_acquired);
4044#endif
4045
4046/*
4047 * Used by the testsuite, sanitize the validator state
4048 * after a simulated failure:
4049 */
4050
4051void lockdep_reset(void)
4052{
4053 unsigned long flags;
4054 int i;
4055
4056 raw_local_irq_save(flags);
4057 current->curr_chain_key = 0;
4058 current->lockdep_depth = 0;
4059 current->lockdep_recursion = 0;
4060 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
4061 nr_hardirq_chains = 0;
4062 nr_softirq_chains = 0;
4063 nr_process_chains = 0;
4064 debug_locks = 1;
4065 for (i = 0; i < CHAINHASH_SIZE; i++)
4066 INIT_HLIST_HEAD(chainhash_table + i);
4067 raw_local_irq_restore(flags);
4068}
4069
4070static void zap_class(struct lock_class *class)
4071{
4072 int i;
4073
4074 /*
4075 * Remove all dependencies this lock is
4076 * involved in:
4077 */
4078 for (i = 0; i < nr_list_entries; i++) {
4079 if (list_entries[i].class == class)
4080 list_del_rcu(&list_entries[i].entry);
4081 }
4082 /*
4083 * Unhash the class and remove it from the all_lock_classes list:
4084 */
4085 hlist_del_rcu(&class->hash_entry);
4086 list_del_rcu(&class->lock_entry);
4087
4088 RCU_INIT_POINTER(class->key, NULL);
4089 RCU_INIT_POINTER(class->name, NULL);
4090}
4091
4092static inline int within(const void *addr, void *start, unsigned long size)
4093{
4094 return addr >= start && addr < start + size;
4095}
4096
4097/*
4098 * Used in module.c to remove lock classes from memory that is going to be
4099 * freed; and possibly re-used by other modules.
4100 *
4101 * We will have had one sync_sched() before getting here, so we're guaranteed
4102 * nobody will look up these exact classes -- they're properly dead but still
4103 * allocated.
4104 */
4105void lockdep_free_key_range(void *start, unsigned long size)
4106{
4107 struct lock_class *class;
4108 struct hlist_head *head;
4109 unsigned long flags;
4110 int i;
4111 int locked;
4112
4113 raw_local_irq_save(flags);
4114 locked = graph_lock();
4115
4116 /*
4117 * Unhash all classes that were created by this module:
4118 */
4119 for (i = 0; i < CLASSHASH_SIZE; i++) {
4120 head = classhash_table + i;
4121 hlist_for_each_entry_rcu(class, head, hash_entry) {
4122 if (within(class->key, start, size))
4123 zap_class(class);
4124 else if (within(class->name, start, size))
4125 zap_class(class);
4126 }
4127 }
4128
4129 if (locked)
4130 graph_unlock();
4131 raw_local_irq_restore(flags);
4132
4133 /*
4134 * Wait for any possible iterators from look_up_lock_class() to pass
4135 * before continuing to free the memory they refer to.
4136 *
4137 * sync_sched() is sufficient because the read-side is IRQ disable.
4138 */
4139 synchronize_sched();
4140
4141 /*
4142 * XXX at this point we could return the resources to the pool;
4143 * instead we leak them. We would need to change to bitmap allocators
4144 * instead of the linear allocators we have now.
4145 */
4146}
4147
4148void lockdep_reset_lock(struct lockdep_map *lock)
4149{
4150 struct lock_class *class;
4151 struct hlist_head *head;
4152 unsigned long flags;
4153 int i, j;
4154 int locked;
4155
4156 raw_local_irq_save(flags);
4157
4158 /*
4159 * Remove all classes this lock might have:
4160 */
4161 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
4162 /*
4163 * If the class exists we look it up and zap it:
4164 */
4165 class = look_up_lock_class(lock, j);
4166 if (class)
4167 zap_class(class);
4168 }
4169 /*
4170 * Debug check: in the end all mapped classes should
4171 * be gone.
4172 */
4173 locked = graph_lock();
4174 for (i = 0; i < CLASSHASH_SIZE; i++) {
4175 head = classhash_table + i;
4176 hlist_for_each_entry_rcu(class, head, hash_entry) {
4177 int match = 0;
4178
4179 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
4180 match |= class == lock->class_cache[j];
4181
4182 if (unlikely(match)) {
4183 if (debug_locks_off_graph_unlock()) {
4184 /*
4185 * We all just reset everything, how did it match?
4186 */
4187 WARN_ON(1);
4188 }
4189 goto out_restore;
4190 }
4191 }
4192 }
4193 if (locked)
4194 graph_unlock();
4195
4196out_restore:
4197 raw_local_irq_restore(flags);
4198}
4199
4200void __init lockdep_info(void)
4201{
4202 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4203
4204 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
4205 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
4206 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
4207 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
4208 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
4209 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
4210 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
4211
4212 printk(" memory used by lock dependency info: %lu kB\n",
4213 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4214 sizeof(struct list_head) * CLASSHASH_SIZE +
4215 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4216 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4217 sizeof(struct list_head) * CHAINHASH_SIZE
4218#ifdef CONFIG_PROVE_LOCKING
4219 + sizeof(struct circular_queue)
4220#endif
4221 ) / 1024
4222 );
4223
4224 printk(" per task-struct memory footprint: %lu bytes\n",
4225 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4226}
4227
4228static void
4229print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4230 const void *mem_to, struct held_lock *hlock)
4231{
4232 if (!debug_locks_off())
4233 return;
4234 if (debug_locks_silent)
4235 return;
4236
4237 printk("\n");
4238 printk("=========================\n");
4239 printk("[ BUG: held lock freed! ]\n");
4240 print_kernel_ident();
4241 printk("-------------------------\n");
4242 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4243 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4244 print_lock(hlock);
4245 lockdep_print_held_locks(curr);
4246
4247 printk("\nstack backtrace:\n");
4248 dump_stack();
4249}
4250
4251static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4252 const void* lock_from, unsigned long lock_len)
4253{
4254 return lock_from + lock_len <= mem_from ||
4255 mem_from + mem_len <= lock_from;
4256}
4257
4258/*
4259 * Called when kernel memory is freed (or unmapped), or if a lock
4260 * is destroyed or reinitialized - this code checks whether there is
4261 * any held lock in the memory range of <from> to <to>:
4262 */
4263void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4264{
4265 struct task_struct *curr = current;
4266 struct held_lock *hlock;
4267 unsigned long flags;
4268 int i;
4269
4270 if (unlikely(!debug_locks))
4271 return;
4272
4273 local_irq_save(flags);
4274 for (i = 0; i < curr->lockdep_depth; i++) {
4275 hlock = curr->held_locks + i;
4276
4277 if (not_in_range(mem_from, mem_len, hlock->instance,
4278 sizeof(*hlock->instance)))
4279 continue;
4280
4281 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4282 break;
4283 }
4284 local_irq_restore(flags);
4285}
4286EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4287
4288static void print_held_locks_bug(void)
4289{
4290 if (!debug_locks_off())
4291 return;
4292 if (debug_locks_silent)
4293 return;
4294
4295 printk("\n");
4296 printk("=====================================\n");
4297 printk("[ BUG: %s/%d still has locks held! ]\n",
4298 current->comm, task_pid_nr(current));
4299 print_kernel_ident();
4300 printk("-------------------------------------\n");
4301 lockdep_print_held_locks(current);
4302 printk("\nstack backtrace:\n");
4303 dump_stack();
4304}
4305
4306void debug_check_no_locks_held(void)
4307{
4308 if (unlikely(current->lockdep_depth > 0))
4309 print_held_locks_bug();
4310}
4311EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
4312
4313#ifdef __KERNEL__
4314void debug_show_all_locks(void)
4315{
4316 struct task_struct *g, *p;
4317 int count = 10;
4318 int unlock = 1;
4319
4320 if (unlikely(!debug_locks)) {
4321 printk("INFO: lockdep is turned off.\n");
4322 return;
4323 }
4324 printk("\nShowing all locks held in the system:\n");
4325
4326 /*
4327 * Here we try to get the tasklist_lock as hard as possible,
4328 * if not successful after 2 seconds we ignore it (but keep
4329 * trying). This is to enable a debug printout even if a
4330 * tasklist_lock-holding task deadlocks or crashes.
4331 */
4332retry:
4333 if (!read_trylock(&tasklist_lock)) {
4334 if (count == 10)
4335 printk("hm, tasklist_lock locked, retrying... ");
4336 if (count) {
4337 count--;
4338 printk(" #%d", 10-count);
4339 mdelay(200);
4340 goto retry;
4341 }
4342 printk(" ignoring it.\n");
4343 unlock = 0;
4344 } else {
4345 if (count != 10)
4346 printk(KERN_CONT " locked it.\n");
4347 }
4348
4349 do_each_thread(g, p) {
4350 /*
4351 * It's not reliable to print a task's held locks
4352 * if it's not sleeping (or if it's not the current
4353 * task):
4354 */
4355 if (p->state == TASK_RUNNING && p != current)
4356 continue;
4357 if (p->lockdep_depth)
4358 lockdep_print_held_locks(p);
4359 if (!unlock)
4360 if (read_trylock(&tasklist_lock))
4361 unlock = 1;
4362 } while_each_thread(g, p);
4363
4364 printk("\n");
4365 printk("=============================================\n\n");
4366
4367 if (unlock)
4368 read_unlock(&tasklist_lock);
4369}
4370EXPORT_SYMBOL_GPL(debug_show_all_locks);
4371#endif
4372
4373/*
4374 * Careful: only use this function if you are sure that
4375 * the task cannot run in parallel!
4376 */
4377void debug_show_held_locks(struct task_struct *task)
4378{
4379 if (unlikely(!debug_locks)) {
4380 printk("INFO: lockdep is turned off.\n");
4381 return;
4382 }
4383 lockdep_print_held_locks(task);
4384}
4385EXPORT_SYMBOL_GPL(debug_show_held_locks);
4386
4387asmlinkage __visible void lockdep_sys_exit(void)
4388{
4389 struct task_struct *curr = current;
4390
4391 if (unlikely(curr->lockdep_depth)) {
4392 if (!debug_locks_off())
4393 return;
4394 printk("\n");
4395 printk("================================================\n");
4396 printk("[ BUG: lock held when returning to user space! ]\n");
4397 print_kernel_ident();
4398 printk("------------------------------------------------\n");
4399 printk("%s/%d is leaving the kernel with locks still held!\n",
4400 curr->comm, curr->pid);
4401 lockdep_print_held_locks(curr);
4402 }
4403}
4404
4405void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4406{
4407 struct task_struct *curr = current;
4408
4409#ifndef CONFIG_PROVE_RCU_REPEATEDLY
4410 if (!debug_locks_off())
4411 return;
4412#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4413 /* Note: the following can be executed concurrently, so be careful. */
4414 printk("\n");
4415 printk("===============================\n");
4416 printk("[ INFO: suspicious RCU usage. ]\n");
4417 print_kernel_ident();
4418 printk("-------------------------------\n");
4419 printk("%s:%d %s!\n", file, line, s);
4420 printk("\nother info that might help us debug this:\n\n");
4421 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4422 !rcu_lockdep_current_cpu_online()
4423 ? "RCU used illegally from offline CPU!\n"
4424 : !rcu_is_watching()
4425 ? "RCU used illegally from idle CPU!\n"
4426 : "",
4427 rcu_scheduler_active, debug_locks);
4428
4429 /*
4430 * If a CPU is in the RCU-free window in idle (ie: in the section
4431 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4432 * considers that CPU to be in an "extended quiescent state",
4433 * which means that RCU will be completely ignoring that CPU.
4434 * Therefore, rcu_read_lock() and friends have absolutely no
4435 * effect on a CPU running in that state. In other words, even if
4436 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4437 * delete data structures out from under it. RCU really has no
4438 * choice here: we need to keep an RCU-free window in idle where
4439 * the CPU may possibly enter into low power mode. This way we can
4440 * notice an extended quiescent state to other CPUs that started a grace
4441 * period. Otherwise we would delay any grace period as long as we run
4442 * in the idle task.
4443 *
4444 * So complain bitterly if someone does call rcu_read_lock(),
4445 * rcu_read_lock_bh() and so on from extended quiescent states.
4446 */
4447 if (!rcu_is_watching())
4448 printk("RCU used illegally from extended quiescent state!\n");
4449
4450 lockdep_print_held_locks(curr);
4451 printk("\nstack backtrace:\n");
4452 dump_stack();
4453}
4454EXPORT_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#include <linux/lockdep.h>
58#include <linux/context_tracking.h>
59
60#include <asm/sections.h>
61
62#include "lockdep_internals.h"
63
64#include <trace/events/lock.h>
65
66#ifdef CONFIG_PROVE_LOCKING
67static int prove_locking = 1;
68module_param(prove_locking, int, 0644);
69#else
70#define prove_locking 0
71#endif
72
73#ifdef CONFIG_LOCK_STAT
74static int lock_stat = 1;
75module_param(lock_stat, int, 0644);
76#else
77#define lock_stat 0
78#endif
79
80#ifdef CONFIG_SYSCTL
81static struct ctl_table kern_lockdep_table[] = {
82#ifdef CONFIG_PROVE_LOCKING
83 {
84 .procname = "prove_locking",
85 .data = &prove_locking,
86 .maxlen = sizeof(int),
87 .mode = 0644,
88 .proc_handler = proc_dointvec,
89 },
90#endif /* CONFIG_PROVE_LOCKING */
91#ifdef CONFIG_LOCK_STAT
92 {
93 .procname = "lock_stat",
94 .data = &lock_stat,
95 .maxlen = sizeof(int),
96 .mode = 0644,
97 .proc_handler = proc_dointvec,
98 },
99#endif /* CONFIG_LOCK_STAT */
100 { }
101};
102
103static __init int kernel_lockdep_sysctls_init(void)
104{
105 register_sysctl_init("kernel", kern_lockdep_table);
106 return 0;
107}
108late_initcall(kernel_lockdep_sysctls_init);
109#endif /* CONFIG_SYSCTL */
110
111DEFINE_PER_CPU(unsigned int, lockdep_recursion);
112EXPORT_PER_CPU_SYMBOL_GPL(lockdep_recursion);
113
114static __always_inline bool lockdep_enabled(void)
115{
116 if (!debug_locks)
117 return false;
118
119 if (this_cpu_read(lockdep_recursion))
120 return false;
121
122 if (current->lockdep_recursion)
123 return false;
124
125 return true;
126}
127
128/*
129 * lockdep_lock: protects the lockdep graph, the hashes and the
130 * class/list/hash allocators.
131 *
132 * This is one of the rare exceptions where it's justified
133 * to use a raw spinlock - we really dont want the spinlock
134 * code to recurse back into the lockdep code...
135 */
136static arch_spinlock_t __lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
137static struct task_struct *__owner;
138
139static inline void lockdep_lock(void)
140{
141 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
142
143 __this_cpu_inc(lockdep_recursion);
144 arch_spin_lock(&__lock);
145 __owner = current;
146}
147
148static inline void lockdep_unlock(void)
149{
150 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
151
152 if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current))
153 return;
154
155 __owner = NULL;
156 arch_spin_unlock(&__lock);
157 __this_cpu_dec(lockdep_recursion);
158}
159
160static inline bool lockdep_assert_locked(void)
161{
162 return DEBUG_LOCKS_WARN_ON(__owner != current);
163}
164
165static struct task_struct *lockdep_selftest_task_struct;
166
167
168static int graph_lock(void)
169{
170 lockdep_lock();
171 /*
172 * Make sure that if another CPU detected a bug while
173 * walking the graph we dont change it (while the other
174 * CPU is busy printing out stuff with the graph lock
175 * dropped already)
176 */
177 if (!debug_locks) {
178 lockdep_unlock();
179 return 0;
180 }
181 return 1;
182}
183
184static inline void graph_unlock(void)
185{
186 lockdep_unlock();
187}
188
189/*
190 * Turn lock debugging off and return with 0 if it was off already,
191 * and also release the graph lock:
192 */
193static inline int debug_locks_off_graph_unlock(void)
194{
195 int ret = debug_locks_off();
196
197 lockdep_unlock();
198
199 return ret;
200}
201
202unsigned long nr_list_entries;
203static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
204static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES);
205
206/*
207 * All data structures here are protected by the global debug_lock.
208 *
209 * nr_lock_classes is the number of elements of lock_classes[] that is
210 * in use.
211 */
212#define KEYHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
213#define KEYHASH_SIZE (1UL << KEYHASH_BITS)
214static struct hlist_head lock_keys_hash[KEYHASH_SIZE];
215unsigned long nr_lock_classes;
216unsigned long nr_zapped_classes;
217unsigned long max_lock_class_idx;
218struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
219DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS);
220
221static inline struct lock_class *hlock_class(struct held_lock *hlock)
222{
223 unsigned int class_idx = hlock->class_idx;
224
225 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfield */
226 barrier();
227
228 if (!test_bit(class_idx, lock_classes_in_use)) {
229 /*
230 * Someone passed in garbage, we give up.
231 */
232 DEBUG_LOCKS_WARN_ON(1);
233 return NULL;
234 }
235
236 /*
237 * At this point, if the passed hlock->class_idx is still garbage,
238 * we just have to live with it
239 */
240 return lock_classes + class_idx;
241}
242
243#ifdef CONFIG_LOCK_STAT
244static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
245
246static inline u64 lockstat_clock(void)
247{
248 return local_clock();
249}
250
251static int lock_point(unsigned long points[], unsigned long ip)
252{
253 int i;
254
255 for (i = 0; i < LOCKSTAT_POINTS; i++) {
256 if (points[i] == 0) {
257 points[i] = ip;
258 break;
259 }
260 if (points[i] == ip)
261 break;
262 }
263
264 return i;
265}
266
267static void lock_time_inc(struct lock_time *lt, u64 time)
268{
269 if (time > lt->max)
270 lt->max = time;
271
272 if (time < lt->min || !lt->nr)
273 lt->min = time;
274
275 lt->total += time;
276 lt->nr++;
277}
278
279static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
280{
281 if (!src->nr)
282 return;
283
284 if (src->max > dst->max)
285 dst->max = src->max;
286
287 if (src->min < dst->min || !dst->nr)
288 dst->min = src->min;
289
290 dst->total += src->total;
291 dst->nr += src->nr;
292}
293
294struct lock_class_stats lock_stats(struct lock_class *class)
295{
296 struct lock_class_stats stats;
297 int cpu, i;
298
299 memset(&stats, 0, sizeof(struct lock_class_stats));
300 for_each_possible_cpu(cpu) {
301 struct lock_class_stats *pcs =
302 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
303
304 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
305 stats.contention_point[i] += pcs->contention_point[i];
306
307 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
308 stats.contending_point[i] += pcs->contending_point[i];
309
310 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
311 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
312
313 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
314 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
315
316 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
317 stats.bounces[i] += pcs->bounces[i];
318 }
319
320 return stats;
321}
322
323void clear_lock_stats(struct lock_class *class)
324{
325 int cpu;
326
327 for_each_possible_cpu(cpu) {
328 struct lock_class_stats *cpu_stats =
329 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
330
331 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
332 }
333 memset(class->contention_point, 0, sizeof(class->contention_point));
334 memset(class->contending_point, 0, sizeof(class->contending_point));
335}
336
337static struct lock_class_stats *get_lock_stats(struct lock_class *class)
338{
339 return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes];
340}
341
342static void lock_release_holdtime(struct held_lock *hlock)
343{
344 struct lock_class_stats *stats;
345 u64 holdtime;
346
347 if (!lock_stat)
348 return;
349
350 holdtime = lockstat_clock() - hlock->holdtime_stamp;
351
352 stats = get_lock_stats(hlock_class(hlock));
353 if (hlock->read)
354 lock_time_inc(&stats->read_holdtime, holdtime);
355 else
356 lock_time_inc(&stats->write_holdtime, holdtime);
357}
358#else
359static inline void lock_release_holdtime(struct held_lock *hlock)
360{
361}
362#endif
363
364/*
365 * We keep a global list of all lock classes. The list is only accessed with
366 * the lockdep spinlock lock held. free_lock_classes is a list with free
367 * elements. These elements are linked together by the lock_entry member in
368 * struct lock_class.
369 */
370static LIST_HEAD(all_lock_classes);
371static LIST_HEAD(free_lock_classes);
372
373/**
374 * struct pending_free - information about data structures about to be freed
375 * @zapped: Head of a list with struct lock_class elements.
376 * @lock_chains_being_freed: Bitmap that indicates which lock_chains[] elements
377 * are about to be freed.
378 */
379struct pending_free {
380 struct list_head zapped;
381 DECLARE_BITMAP(lock_chains_being_freed, MAX_LOCKDEP_CHAINS);
382};
383
384/**
385 * struct delayed_free - data structures used for delayed freeing
386 *
387 * A data structure for delayed freeing of data structures that may be
388 * accessed by RCU readers at the time these were freed.
389 *
390 * @rcu_head: Used to schedule an RCU callback for freeing data structures.
391 * @index: Index of @pf to which freed data structures are added.
392 * @scheduled: Whether or not an RCU callback has been scheduled.
393 * @pf: Array with information about data structures about to be freed.
394 */
395static struct delayed_free {
396 struct rcu_head rcu_head;
397 int index;
398 int scheduled;
399 struct pending_free pf[2];
400} delayed_free;
401
402/*
403 * The lockdep classes are in a hash-table as well, for fast lookup:
404 */
405#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
406#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
407#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
408#define classhashentry(key) (classhash_table + __classhashfn((key)))
409
410static struct hlist_head classhash_table[CLASSHASH_SIZE];
411
412/*
413 * We put the lock dependency chains into a hash-table as well, to cache
414 * their existence:
415 */
416#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
417#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
418#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
419#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
420
421static struct hlist_head chainhash_table[CHAINHASH_SIZE];
422
423/*
424 * the id of held_lock
425 */
426static inline u16 hlock_id(struct held_lock *hlock)
427{
428 BUILD_BUG_ON(MAX_LOCKDEP_KEYS_BITS + 2 > 16);
429
430 return (hlock->class_idx | (hlock->read << MAX_LOCKDEP_KEYS_BITS));
431}
432
433static inline unsigned int chain_hlock_class_idx(u16 hlock_id)
434{
435 return hlock_id & (MAX_LOCKDEP_KEYS - 1);
436}
437
438/*
439 * The hash key of the lock dependency chains is a hash itself too:
440 * it's a hash of all locks taken up to that lock, including that lock.
441 * It's a 64-bit hash, because it's important for the keys to be
442 * unique.
443 */
444static inline u64 iterate_chain_key(u64 key, u32 idx)
445{
446 u32 k0 = key, k1 = key >> 32;
447
448 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
449
450 return k0 | (u64)k1 << 32;
451}
452
453void lockdep_init_task(struct task_struct *task)
454{
455 task->lockdep_depth = 0; /* no locks held yet */
456 task->curr_chain_key = INITIAL_CHAIN_KEY;
457 task->lockdep_recursion = 0;
458}
459
460static __always_inline void lockdep_recursion_inc(void)
461{
462 __this_cpu_inc(lockdep_recursion);
463}
464
465static __always_inline void lockdep_recursion_finish(void)
466{
467 if (WARN_ON_ONCE(__this_cpu_dec_return(lockdep_recursion)))
468 __this_cpu_write(lockdep_recursion, 0);
469}
470
471void lockdep_set_selftest_task(struct task_struct *task)
472{
473 lockdep_selftest_task_struct = task;
474}
475
476/*
477 * Debugging switches:
478 */
479
480#define VERBOSE 0
481#define VERY_VERBOSE 0
482
483#if VERBOSE
484# define HARDIRQ_VERBOSE 1
485# define SOFTIRQ_VERBOSE 1
486#else
487# define HARDIRQ_VERBOSE 0
488# define SOFTIRQ_VERBOSE 0
489#endif
490
491#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
492/*
493 * Quick filtering for interesting events:
494 */
495static int class_filter(struct lock_class *class)
496{
497#if 0
498 /* Example */
499 if (class->name_version == 1 &&
500 !strcmp(class->name, "lockname"))
501 return 1;
502 if (class->name_version == 1 &&
503 !strcmp(class->name, "&struct->lockfield"))
504 return 1;
505#endif
506 /* Filter everything else. 1 would be to allow everything else */
507 return 0;
508}
509#endif
510
511static int verbose(struct lock_class *class)
512{
513#if VERBOSE
514 return class_filter(class);
515#endif
516 return 0;
517}
518
519static void print_lockdep_off(const char *bug_msg)
520{
521 printk(KERN_DEBUG "%s\n", bug_msg);
522 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
523#ifdef CONFIG_LOCK_STAT
524 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
525#endif
526}
527
528unsigned long nr_stack_trace_entries;
529
530#ifdef CONFIG_PROVE_LOCKING
531/**
532 * struct lock_trace - single stack backtrace
533 * @hash_entry: Entry in a stack_trace_hash[] list.
534 * @hash: jhash() of @entries.
535 * @nr_entries: Number of entries in @entries.
536 * @entries: Actual stack backtrace.
537 */
538struct lock_trace {
539 struct hlist_node hash_entry;
540 u32 hash;
541 u32 nr_entries;
542 unsigned long entries[] __aligned(sizeof(unsigned long));
543};
544#define LOCK_TRACE_SIZE_IN_LONGS \
545 (sizeof(struct lock_trace) / sizeof(unsigned long))
546/*
547 * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock.
548 */
549static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
550static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE];
551
552static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2)
553{
554 return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries &&
555 memcmp(t1->entries, t2->entries,
556 t1->nr_entries * sizeof(t1->entries[0])) == 0;
557}
558
559static struct lock_trace *save_trace(void)
560{
561 struct lock_trace *trace, *t2;
562 struct hlist_head *hash_head;
563 u32 hash;
564 int max_entries;
565
566 BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE);
567 BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES);
568
569 trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries);
570 max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries -
571 LOCK_TRACE_SIZE_IN_LONGS;
572
573 if (max_entries <= 0) {
574 if (!debug_locks_off_graph_unlock())
575 return NULL;
576
577 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
578 dump_stack();
579
580 return NULL;
581 }
582 trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
583
584 hash = jhash(trace->entries, trace->nr_entries *
585 sizeof(trace->entries[0]), 0);
586 trace->hash = hash;
587 hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1));
588 hlist_for_each_entry(t2, hash_head, hash_entry) {
589 if (traces_identical(trace, t2))
590 return t2;
591 }
592 nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries;
593 hlist_add_head(&trace->hash_entry, hash_head);
594
595 return trace;
596}
597
598/* Return the number of stack traces in the stack_trace[] array. */
599u64 lockdep_stack_trace_count(void)
600{
601 struct lock_trace *trace;
602 u64 c = 0;
603 int i;
604
605 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) {
606 hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) {
607 c++;
608 }
609 }
610
611 return c;
612}
613
614/* Return the number of stack hash chains that have at least one stack trace. */
615u64 lockdep_stack_hash_count(void)
616{
617 u64 c = 0;
618 int i;
619
620 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++)
621 if (!hlist_empty(&stack_trace_hash[i]))
622 c++;
623
624 return c;
625}
626#endif
627
628unsigned int nr_hardirq_chains;
629unsigned int nr_softirq_chains;
630unsigned int nr_process_chains;
631unsigned int max_lockdep_depth;
632
633#ifdef CONFIG_DEBUG_LOCKDEP
634/*
635 * Various lockdep statistics:
636 */
637DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
638#endif
639
640#ifdef CONFIG_PROVE_LOCKING
641/*
642 * Locking printouts:
643 */
644
645#define __USAGE(__STATE) \
646 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
647 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
648 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
649 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
650
651static const char *usage_str[] =
652{
653#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
654#include "lockdep_states.h"
655#undef LOCKDEP_STATE
656 [LOCK_USED] = "INITIAL USE",
657 [LOCK_USED_READ] = "INITIAL READ USE",
658 /* abused as string storage for verify_lock_unused() */
659 [LOCK_USAGE_STATES] = "IN-NMI",
660};
661#endif
662
663const char *__get_key_name(const struct lockdep_subclass_key *key, char *str)
664{
665 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
666}
667
668static inline unsigned long lock_flag(enum lock_usage_bit bit)
669{
670 return 1UL << bit;
671}
672
673static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
674{
675 /*
676 * The usage character defaults to '.' (i.e., irqs disabled and not in
677 * irq context), which is the safest usage category.
678 */
679 char c = '.';
680
681 /*
682 * The order of the following usage checks matters, which will
683 * result in the outcome character as follows:
684 *
685 * - '+': irq is enabled and not in irq context
686 * - '-': in irq context and irq is disabled
687 * - '?': in irq context and irq is enabled
688 */
689 if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) {
690 c = '+';
691 if (class->usage_mask & lock_flag(bit))
692 c = '?';
693 } else if (class->usage_mask & lock_flag(bit))
694 c = '-';
695
696 return c;
697}
698
699void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
700{
701 int i = 0;
702
703#define LOCKDEP_STATE(__STATE) \
704 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
705 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
706#include "lockdep_states.h"
707#undef LOCKDEP_STATE
708
709 usage[i] = '\0';
710}
711
712static void __print_lock_name(struct held_lock *hlock, struct lock_class *class)
713{
714 char str[KSYM_NAME_LEN];
715 const char *name;
716
717 name = class->name;
718 if (!name) {
719 name = __get_key_name(class->key, str);
720 printk(KERN_CONT "%s", name);
721 } else {
722 printk(KERN_CONT "%s", name);
723 if (class->name_version > 1)
724 printk(KERN_CONT "#%d", class->name_version);
725 if (class->subclass)
726 printk(KERN_CONT "/%d", class->subclass);
727 if (hlock && class->print_fn)
728 class->print_fn(hlock->instance);
729 }
730}
731
732static void print_lock_name(struct held_lock *hlock, struct lock_class *class)
733{
734 char usage[LOCK_USAGE_CHARS];
735
736 get_usage_chars(class, usage);
737
738 printk(KERN_CONT " (");
739 __print_lock_name(hlock, class);
740 printk(KERN_CONT "){%s}-{%d:%d}", usage,
741 class->wait_type_outer ?: class->wait_type_inner,
742 class->wait_type_inner);
743}
744
745static void print_lockdep_cache(struct lockdep_map *lock)
746{
747 const char *name;
748 char str[KSYM_NAME_LEN];
749
750 name = lock->name;
751 if (!name)
752 name = __get_key_name(lock->key->subkeys, str);
753
754 printk(KERN_CONT "%s", name);
755}
756
757static void print_lock(struct held_lock *hlock)
758{
759 /*
760 * We can be called locklessly through debug_show_all_locks() so be
761 * extra careful, the hlock might have been released and cleared.
762 *
763 * If this indeed happens, lets pretend it does not hurt to continue
764 * to print the lock unless the hlock class_idx does not point to a
765 * registered class. The rationale here is: since we don't attempt
766 * to distinguish whether we are in this situation, if it just
767 * happened we can't count on class_idx to tell either.
768 */
769 struct lock_class *lock = hlock_class(hlock);
770
771 if (!lock) {
772 printk(KERN_CONT "<RELEASED>\n");
773 return;
774 }
775
776 printk(KERN_CONT "%px", hlock->instance);
777 print_lock_name(hlock, lock);
778 printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
779}
780
781static void lockdep_print_held_locks(struct task_struct *p)
782{
783 int i, depth = READ_ONCE(p->lockdep_depth);
784
785 if (!depth)
786 printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p));
787 else
788 printk("%d lock%s held by %s/%d:\n", depth,
789 depth > 1 ? "s" : "", p->comm, task_pid_nr(p));
790 /*
791 * It's not reliable to print a task's held locks if it's not sleeping
792 * and it's not the current task.
793 */
794 if (p != current && task_is_running(p))
795 return;
796 for (i = 0; i < depth; i++) {
797 printk(" #%d: ", i);
798 print_lock(p->held_locks + i);
799 }
800}
801
802static void print_kernel_ident(void)
803{
804 printk("%s %.*s %s\n", init_utsname()->release,
805 (int)strcspn(init_utsname()->version, " "),
806 init_utsname()->version,
807 print_tainted());
808}
809
810static int very_verbose(struct lock_class *class)
811{
812#if VERY_VERBOSE
813 return class_filter(class);
814#endif
815 return 0;
816}
817
818/*
819 * Is this the address of a static object:
820 */
821#ifdef __KERNEL__
822static int static_obj(const void *obj)
823{
824 unsigned long addr = (unsigned long) obj;
825
826 if (is_kernel_core_data(addr))
827 return 1;
828
829 /*
830 * keys are allowed in the __ro_after_init section.
831 */
832 if (is_kernel_rodata(addr))
833 return 1;
834
835 /*
836 * in initdata section and used during bootup only?
837 * NOTE: On some platforms the initdata section is
838 * outside of the _stext ... _end range.
839 */
840 if (system_state < SYSTEM_FREEING_INITMEM &&
841 init_section_contains((void *)addr, 1))
842 return 1;
843
844 /*
845 * in-kernel percpu var?
846 */
847 if (is_kernel_percpu_address(addr))
848 return 1;
849
850 /*
851 * module static or percpu var?
852 */
853 return is_module_address(addr) || is_module_percpu_address(addr);
854}
855#endif
856
857/*
858 * To make lock name printouts unique, we calculate a unique
859 * class->name_version generation counter. The caller must hold the graph
860 * lock.
861 */
862static int count_matching_names(struct lock_class *new_class)
863{
864 struct lock_class *class;
865 int count = 0;
866
867 if (!new_class->name)
868 return 0;
869
870 list_for_each_entry(class, &all_lock_classes, lock_entry) {
871 if (new_class->key - new_class->subclass == class->key)
872 return class->name_version;
873 if (class->name && !strcmp(class->name, new_class->name))
874 count = max(count, class->name_version);
875 }
876
877 return count + 1;
878}
879
880/* used from NMI context -- must be lockless */
881static noinstr struct lock_class *
882look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
883{
884 struct lockdep_subclass_key *key;
885 struct hlist_head *hash_head;
886 struct lock_class *class;
887
888 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
889 instrumentation_begin();
890 debug_locks_off();
891 printk(KERN_ERR
892 "BUG: looking up invalid subclass: %u\n", subclass);
893 printk(KERN_ERR
894 "turning off the locking correctness validator.\n");
895 dump_stack();
896 instrumentation_end();
897 return NULL;
898 }
899
900 /*
901 * If it is not initialised then it has never been locked,
902 * so it won't be present in the hash table.
903 */
904 if (unlikely(!lock->key))
905 return NULL;
906
907 /*
908 * NOTE: the class-key must be unique. For dynamic locks, a static
909 * lock_class_key variable is passed in through the mutex_init()
910 * (or spin_lock_init()) call - which acts as the key. For static
911 * locks we use the lock object itself as the key.
912 */
913 BUILD_BUG_ON(sizeof(struct lock_class_key) >
914 sizeof(struct lockdep_map));
915
916 key = lock->key->subkeys + subclass;
917
918 hash_head = classhashentry(key);
919
920 /*
921 * We do an RCU walk of the hash, see lockdep_free_key_range().
922 */
923 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
924 return NULL;
925
926 hlist_for_each_entry_rcu_notrace(class, hash_head, hash_entry) {
927 if (class->key == key) {
928 /*
929 * Huh! same key, different name? Did someone trample
930 * on some memory? We're most confused.
931 */
932 WARN_ONCE(class->name != lock->name &&
933 lock->key != &__lockdep_no_validate__,
934 "Looking for class \"%s\" with key %ps, but found a different class \"%s\" with the same key\n",
935 lock->name, lock->key, class->name);
936 return class;
937 }
938 }
939
940 return NULL;
941}
942
943/*
944 * Static locks do not have their class-keys yet - for them the key is
945 * the lock object itself. If the lock is in the per cpu area, the
946 * canonical address of the lock (per cpu offset removed) is used.
947 */
948static bool assign_lock_key(struct lockdep_map *lock)
949{
950 unsigned long can_addr, addr = (unsigned long)lock;
951
952#ifdef __KERNEL__
953 /*
954 * lockdep_free_key_range() assumes that struct lock_class_key
955 * objects do not overlap. Since we use the address of lock
956 * objects as class key for static objects, check whether the
957 * size of lock_class_key objects does not exceed the size of
958 * the smallest lock object.
959 */
960 BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
961#endif
962
963 if (__is_kernel_percpu_address(addr, &can_addr))
964 lock->key = (void *)can_addr;
965 else if (__is_module_percpu_address(addr, &can_addr))
966 lock->key = (void *)can_addr;
967 else if (static_obj(lock))
968 lock->key = (void *)lock;
969 else {
970 /* Debug-check: all keys must be persistent! */
971 debug_locks_off();
972 pr_err("INFO: trying to register non-static key.\n");
973 pr_err("The code is fine but needs lockdep annotation, or maybe\n");
974 pr_err("you didn't initialize this object before use?\n");
975 pr_err("turning off the locking correctness validator.\n");
976 dump_stack();
977 return false;
978 }
979
980 return true;
981}
982
983#ifdef CONFIG_DEBUG_LOCKDEP
984
985/* Check whether element @e occurs in list @h */
986static bool in_list(struct list_head *e, struct list_head *h)
987{
988 struct list_head *f;
989
990 list_for_each(f, h) {
991 if (e == f)
992 return true;
993 }
994
995 return false;
996}
997
998/*
999 * Check whether entry @e occurs in any of the locks_after or locks_before
1000 * lists.
1001 */
1002static bool in_any_class_list(struct list_head *e)
1003{
1004 struct lock_class *class;
1005 int i;
1006
1007 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1008 class = &lock_classes[i];
1009 if (in_list(e, &class->locks_after) ||
1010 in_list(e, &class->locks_before))
1011 return true;
1012 }
1013 return false;
1014}
1015
1016static bool class_lock_list_valid(struct lock_class *c, struct list_head *h)
1017{
1018 struct lock_list *e;
1019
1020 list_for_each_entry(e, h, entry) {
1021 if (e->links_to != c) {
1022 printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s",
1023 c->name ? : "(?)",
1024 (unsigned long)(e - list_entries),
1025 e->links_to && e->links_to->name ?
1026 e->links_to->name : "(?)",
1027 e->class && e->class->name ? e->class->name :
1028 "(?)");
1029 return false;
1030 }
1031 }
1032 return true;
1033}
1034
1035#ifdef CONFIG_PROVE_LOCKING
1036static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1037#endif
1038
1039static bool check_lock_chain_key(struct lock_chain *chain)
1040{
1041#ifdef CONFIG_PROVE_LOCKING
1042 u64 chain_key = INITIAL_CHAIN_KEY;
1043 int i;
1044
1045 for (i = chain->base; i < chain->base + chain->depth; i++)
1046 chain_key = iterate_chain_key(chain_key, chain_hlocks[i]);
1047 /*
1048 * The 'unsigned long long' casts avoid that a compiler warning
1049 * is reported when building tools/lib/lockdep.
1050 */
1051 if (chain->chain_key != chain_key) {
1052 printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n",
1053 (unsigned long long)(chain - lock_chains),
1054 (unsigned long long)chain->chain_key,
1055 (unsigned long long)chain_key);
1056 return false;
1057 }
1058#endif
1059 return true;
1060}
1061
1062static bool in_any_zapped_class_list(struct lock_class *class)
1063{
1064 struct pending_free *pf;
1065 int i;
1066
1067 for (i = 0, pf = delayed_free.pf; i < ARRAY_SIZE(delayed_free.pf); i++, pf++) {
1068 if (in_list(&class->lock_entry, &pf->zapped))
1069 return true;
1070 }
1071
1072 return false;
1073}
1074
1075static bool __check_data_structures(void)
1076{
1077 struct lock_class *class;
1078 struct lock_chain *chain;
1079 struct hlist_head *head;
1080 struct lock_list *e;
1081 int i;
1082
1083 /* Check whether all classes occur in a lock list. */
1084 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1085 class = &lock_classes[i];
1086 if (!in_list(&class->lock_entry, &all_lock_classes) &&
1087 !in_list(&class->lock_entry, &free_lock_classes) &&
1088 !in_any_zapped_class_list(class)) {
1089 printk(KERN_INFO "class %px/%s is not in any class list\n",
1090 class, class->name ? : "(?)");
1091 return false;
1092 }
1093 }
1094
1095 /* Check whether all classes have valid lock lists. */
1096 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1097 class = &lock_classes[i];
1098 if (!class_lock_list_valid(class, &class->locks_before))
1099 return false;
1100 if (!class_lock_list_valid(class, &class->locks_after))
1101 return false;
1102 }
1103
1104 /* Check the chain_key of all lock chains. */
1105 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
1106 head = chainhash_table + i;
1107 hlist_for_each_entry_rcu(chain, head, entry) {
1108 if (!check_lock_chain_key(chain))
1109 return false;
1110 }
1111 }
1112
1113 /*
1114 * Check whether all list entries that are in use occur in a class
1115 * lock list.
1116 */
1117 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1118 e = list_entries + i;
1119 if (!in_any_class_list(&e->entry)) {
1120 printk(KERN_INFO "list entry %d is not in any class list; class %s <> %s\n",
1121 (unsigned int)(e - list_entries),
1122 e->class->name ? : "(?)",
1123 e->links_to->name ? : "(?)");
1124 return false;
1125 }
1126 }
1127
1128 /*
1129 * Check whether all list entries that are not in use do not occur in
1130 * a class lock list.
1131 */
1132 for_each_clear_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1133 e = list_entries + i;
1134 if (in_any_class_list(&e->entry)) {
1135 printk(KERN_INFO "list entry %d occurs in a class list; class %s <> %s\n",
1136 (unsigned int)(e - list_entries),
1137 e->class && e->class->name ? e->class->name :
1138 "(?)",
1139 e->links_to && e->links_to->name ?
1140 e->links_to->name : "(?)");
1141 return false;
1142 }
1143 }
1144
1145 return true;
1146}
1147
1148int check_consistency = 0;
1149module_param(check_consistency, int, 0644);
1150
1151static void check_data_structures(void)
1152{
1153 static bool once = false;
1154
1155 if (check_consistency && !once) {
1156 if (!__check_data_structures()) {
1157 once = true;
1158 WARN_ON(once);
1159 }
1160 }
1161}
1162
1163#else /* CONFIG_DEBUG_LOCKDEP */
1164
1165static inline void check_data_structures(void) { }
1166
1167#endif /* CONFIG_DEBUG_LOCKDEP */
1168
1169static void init_chain_block_buckets(void);
1170
1171/*
1172 * Initialize the lock_classes[] array elements, the free_lock_classes list
1173 * and also the delayed_free structure.
1174 */
1175static void init_data_structures_once(void)
1176{
1177 static bool __read_mostly ds_initialized, rcu_head_initialized;
1178 int i;
1179
1180 if (likely(rcu_head_initialized))
1181 return;
1182
1183 if (system_state >= SYSTEM_SCHEDULING) {
1184 init_rcu_head(&delayed_free.rcu_head);
1185 rcu_head_initialized = true;
1186 }
1187
1188 if (ds_initialized)
1189 return;
1190
1191 ds_initialized = true;
1192
1193 INIT_LIST_HEAD(&delayed_free.pf[0].zapped);
1194 INIT_LIST_HEAD(&delayed_free.pf[1].zapped);
1195
1196 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1197 list_add_tail(&lock_classes[i].lock_entry, &free_lock_classes);
1198 INIT_LIST_HEAD(&lock_classes[i].locks_after);
1199 INIT_LIST_HEAD(&lock_classes[i].locks_before);
1200 }
1201 init_chain_block_buckets();
1202}
1203
1204static inline struct hlist_head *keyhashentry(const struct lock_class_key *key)
1205{
1206 unsigned long hash = hash_long((uintptr_t)key, KEYHASH_BITS);
1207
1208 return lock_keys_hash + hash;
1209}
1210
1211/* Register a dynamically allocated key. */
1212void lockdep_register_key(struct lock_class_key *key)
1213{
1214 struct hlist_head *hash_head;
1215 struct lock_class_key *k;
1216 unsigned long flags;
1217
1218 if (WARN_ON_ONCE(static_obj(key)))
1219 return;
1220 hash_head = keyhashentry(key);
1221
1222 raw_local_irq_save(flags);
1223 if (!graph_lock())
1224 goto restore_irqs;
1225 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1226 if (WARN_ON_ONCE(k == key))
1227 goto out_unlock;
1228 }
1229 hlist_add_head_rcu(&key->hash_entry, hash_head);
1230out_unlock:
1231 graph_unlock();
1232restore_irqs:
1233 raw_local_irq_restore(flags);
1234}
1235EXPORT_SYMBOL_GPL(lockdep_register_key);
1236
1237/* Check whether a key has been registered as a dynamic key. */
1238static bool is_dynamic_key(const struct lock_class_key *key)
1239{
1240 struct hlist_head *hash_head;
1241 struct lock_class_key *k;
1242 bool found = false;
1243
1244 if (WARN_ON_ONCE(static_obj(key)))
1245 return false;
1246
1247 /*
1248 * If lock debugging is disabled lock_keys_hash[] may contain
1249 * pointers to memory that has already been freed. Avoid triggering
1250 * a use-after-free in that case by returning early.
1251 */
1252 if (!debug_locks)
1253 return true;
1254
1255 hash_head = keyhashentry(key);
1256
1257 rcu_read_lock();
1258 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1259 if (k == key) {
1260 found = true;
1261 break;
1262 }
1263 }
1264 rcu_read_unlock();
1265
1266 return found;
1267}
1268
1269/*
1270 * Register a lock's class in the hash-table, if the class is not present
1271 * yet. Otherwise we look it up. We cache the result in the lock object
1272 * itself, so actual lookup of the hash should be once per lock object.
1273 */
1274static struct lock_class *
1275register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
1276{
1277 struct lockdep_subclass_key *key;
1278 struct hlist_head *hash_head;
1279 struct lock_class *class;
1280 int idx;
1281
1282 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1283
1284 class = look_up_lock_class(lock, subclass);
1285 if (likely(class))
1286 goto out_set_class_cache;
1287
1288 if (!lock->key) {
1289 if (!assign_lock_key(lock))
1290 return NULL;
1291 } else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) {
1292 return NULL;
1293 }
1294
1295 key = lock->key->subkeys + subclass;
1296 hash_head = classhashentry(key);
1297
1298 if (!graph_lock()) {
1299 return NULL;
1300 }
1301 /*
1302 * We have to do the hash-walk again, to avoid races
1303 * with another CPU:
1304 */
1305 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
1306 if (class->key == key)
1307 goto out_unlock_set;
1308 }
1309
1310 init_data_structures_once();
1311
1312 /* Allocate a new lock class and add it to the hash. */
1313 class = list_first_entry_or_null(&free_lock_classes, typeof(*class),
1314 lock_entry);
1315 if (!class) {
1316 if (!debug_locks_off_graph_unlock()) {
1317 return NULL;
1318 }
1319
1320 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
1321 dump_stack();
1322 return NULL;
1323 }
1324 nr_lock_classes++;
1325 __set_bit(class - lock_classes, lock_classes_in_use);
1326 debug_atomic_inc(nr_unused_locks);
1327 class->key = key;
1328 class->name = lock->name;
1329 class->subclass = subclass;
1330 WARN_ON_ONCE(!list_empty(&class->locks_before));
1331 WARN_ON_ONCE(!list_empty(&class->locks_after));
1332 class->name_version = count_matching_names(class);
1333 class->wait_type_inner = lock->wait_type_inner;
1334 class->wait_type_outer = lock->wait_type_outer;
1335 class->lock_type = lock->lock_type;
1336 /*
1337 * We use RCU's safe list-add method to make
1338 * parallel walking of the hash-list safe:
1339 */
1340 hlist_add_head_rcu(&class->hash_entry, hash_head);
1341 /*
1342 * Remove the class from the free list and add it to the global list
1343 * of classes.
1344 */
1345 list_move_tail(&class->lock_entry, &all_lock_classes);
1346 idx = class - lock_classes;
1347 if (idx > max_lock_class_idx)
1348 max_lock_class_idx = idx;
1349
1350 if (verbose(class)) {
1351 graph_unlock();
1352
1353 printk("\nnew class %px: %s", class->key, class->name);
1354 if (class->name_version > 1)
1355 printk(KERN_CONT "#%d", class->name_version);
1356 printk(KERN_CONT "\n");
1357 dump_stack();
1358
1359 if (!graph_lock()) {
1360 return NULL;
1361 }
1362 }
1363out_unlock_set:
1364 graph_unlock();
1365
1366out_set_class_cache:
1367 if (!subclass || force)
1368 lock->class_cache[0] = class;
1369 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
1370 lock->class_cache[subclass] = class;
1371
1372 /*
1373 * Hash collision, did we smoke some? We found a class with a matching
1374 * hash but the subclass -- which is hashed in -- didn't match.
1375 */
1376 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
1377 return NULL;
1378
1379 return class;
1380}
1381
1382#ifdef CONFIG_PROVE_LOCKING
1383/*
1384 * Allocate a lockdep entry. (assumes the graph_lock held, returns
1385 * with NULL on failure)
1386 */
1387static struct lock_list *alloc_list_entry(void)
1388{
1389 int idx = find_first_zero_bit(list_entries_in_use,
1390 ARRAY_SIZE(list_entries));
1391
1392 if (idx >= ARRAY_SIZE(list_entries)) {
1393 if (!debug_locks_off_graph_unlock())
1394 return NULL;
1395
1396 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
1397 dump_stack();
1398 return NULL;
1399 }
1400 nr_list_entries++;
1401 __set_bit(idx, list_entries_in_use);
1402 return list_entries + idx;
1403}
1404
1405/*
1406 * Add a new dependency to the head of the list:
1407 */
1408static int add_lock_to_list(struct lock_class *this,
1409 struct lock_class *links_to, struct list_head *head,
1410 u16 distance, u8 dep,
1411 const struct lock_trace *trace)
1412{
1413 struct lock_list *entry;
1414 /*
1415 * Lock not present yet - get a new dependency struct and
1416 * add it to the list:
1417 */
1418 entry = alloc_list_entry();
1419 if (!entry)
1420 return 0;
1421
1422 entry->class = this;
1423 entry->links_to = links_to;
1424 entry->dep = dep;
1425 entry->distance = distance;
1426 entry->trace = trace;
1427 /*
1428 * Both allocation and removal are done under the graph lock; but
1429 * iteration is under RCU-sched; see look_up_lock_class() and
1430 * lockdep_free_key_range().
1431 */
1432 list_add_tail_rcu(&entry->entry, head);
1433
1434 return 1;
1435}
1436
1437/*
1438 * For good efficiency of modular, we use power of 2
1439 */
1440#define MAX_CIRCULAR_QUEUE_SIZE (1UL << CONFIG_LOCKDEP_CIRCULAR_QUEUE_BITS)
1441#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
1442
1443/*
1444 * The circular_queue and helpers are used to implement graph
1445 * breadth-first search (BFS) algorithm, by which we can determine
1446 * whether there is a path from a lock to another. In deadlock checks,
1447 * a path from the next lock to be acquired to a previous held lock
1448 * indicates that adding the <prev> -> <next> lock dependency will
1449 * produce a circle in the graph. Breadth-first search instead of
1450 * depth-first search is used in order to find the shortest (circular)
1451 * path.
1452 */
1453struct circular_queue {
1454 struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE];
1455 unsigned int front, rear;
1456};
1457
1458static struct circular_queue lock_cq;
1459
1460unsigned int max_bfs_queue_depth;
1461
1462static unsigned int lockdep_dependency_gen_id;
1463
1464static inline void __cq_init(struct circular_queue *cq)
1465{
1466 cq->front = cq->rear = 0;
1467 lockdep_dependency_gen_id++;
1468}
1469
1470static inline int __cq_empty(struct circular_queue *cq)
1471{
1472 return (cq->front == cq->rear);
1473}
1474
1475static inline int __cq_full(struct circular_queue *cq)
1476{
1477 return ((cq->rear + 1) & CQ_MASK) == cq->front;
1478}
1479
1480static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem)
1481{
1482 if (__cq_full(cq))
1483 return -1;
1484
1485 cq->element[cq->rear] = elem;
1486 cq->rear = (cq->rear + 1) & CQ_MASK;
1487 return 0;
1488}
1489
1490/*
1491 * Dequeue an element from the circular_queue, return a lock_list if
1492 * the queue is not empty, or NULL if otherwise.
1493 */
1494static inline struct lock_list * __cq_dequeue(struct circular_queue *cq)
1495{
1496 struct lock_list * lock;
1497
1498 if (__cq_empty(cq))
1499 return NULL;
1500
1501 lock = cq->element[cq->front];
1502 cq->front = (cq->front + 1) & CQ_MASK;
1503
1504 return lock;
1505}
1506
1507static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
1508{
1509 return (cq->rear - cq->front) & CQ_MASK;
1510}
1511
1512static inline void mark_lock_accessed(struct lock_list *lock)
1513{
1514 lock->class->dep_gen_id = lockdep_dependency_gen_id;
1515}
1516
1517static inline void visit_lock_entry(struct lock_list *lock,
1518 struct lock_list *parent)
1519{
1520 lock->parent = parent;
1521}
1522
1523static inline unsigned long lock_accessed(struct lock_list *lock)
1524{
1525 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
1526}
1527
1528static inline struct lock_list *get_lock_parent(struct lock_list *child)
1529{
1530 return child->parent;
1531}
1532
1533static inline int get_lock_depth(struct lock_list *child)
1534{
1535 int depth = 0;
1536 struct lock_list *parent;
1537
1538 while ((parent = get_lock_parent(child))) {
1539 child = parent;
1540 depth++;
1541 }
1542 return depth;
1543}
1544
1545/*
1546 * Return the forward or backward dependency list.
1547 *
1548 * @lock: the lock_list to get its class's dependency list
1549 * @offset: the offset to struct lock_class to determine whether it is
1550 * locks_after or locks_before
1551 */
1552static inline struct list_head *get_dep_list(struct lock_list *lock, int offset)
1553{
1554 void *lock_class = lock->class;
1555
1556 return lock_class + offset;
1557}
1558/*
1559 * Return values of a bfs search:
1560 *
1561 * BFS_E* indicates an error
1562 * BFS_R* indicates a result (match or not)
1563 *
1564 * BFS_EINVALIDNODE: Find a invalid node in the graph.
1565 *
1566 * BFS_EQUEUEFULL: The queue is full while doing the bfs.
1567 *
1568 * BFS_RMATCH: Find the matched node in the graph, and put that node into
1569 * *@target_entry.
1570 *
1571 * BFS_RNOMATCH: Haven't found the matched node and keep *@target_entry
1572 * _unchanged_.
1573 */
1574enum bfs_result {
1575 BFS_EINVALIDNODE = -2,
1576 BFS_EQUEUEFULL = -1,
1577 BFS_RMATCH = 0,
1578 BFS_RNOMATCH = 1,
1579};
1580
1581/*
1582 * bfs_result < 0 means error
1583 */
1584static inline bool bfs_error(enum bfs_result res)
1585{
1586 return res < 0;
1587}
1588
1589/*
1590 * DEP_*_BIT in lock_list::dep
1591 *
1592 * For dependency @prev -> @next:
1593 *
1594 * SR: @prev is shared reader (->read != 0) and @next is recursive reader
1595 * (->read == 2)
1596 * ER: @prev is exclusive locker (->read == 0) and @next is recursive reader
1597 * SN: @prev is shared reader and @next is non-recursive locker (->read != 2)
1598 * EN: @prev is exclusive locker and @next is non-recursive locker
1599 *
1600 * Note that we define the value of DEP_*_BITs so that:
1601 * bit0 is prev->read == 0
1602 * bit1 is next->read != 2
1603 */
1604#define DEP_SR_BIT (0 + (0 << 1)) /* 0 */
1605#define DEP_ER_BIT (1 + (0 << 1)) /* 1 */
1606#define DEP_SN_BIT (0 + (1 << 1)) /* 2 */
1607#define DEP_EN_BIT (1 + (1 << 1)) /* 3 */
1608
1609#define DEP_SR_MASK (1U << (DEP_SR_BIT))
1610#define DEP_ER_MASK (1U << (DEP_ER_BIT))
1611#define DEP_SN_MASK (1U << (DEP_SN_BIT))
1612#define DEP_EN_MASK (1U << (DEP_EN_BIT))
1613
1614static inline unsigned int
1615__calc_dep_bit(struct held_lock *prev, struct held_lock *next)
1616{
1617 return (prev->read == 0) + ((next->read != 2) << 1);
1618}
1619
1620static inline u8 calc_dep(struct held_lock *prev, struct held_lock *next)
1621{
1622 return 1U << __calc_dep_bit(prev, next);
1623}
1624
1625/*
1626 * calculate the dep_bit for backwards edges. We care about whether @prev is
1627 * shared and whether @next is recursive.
1628 */
1629static inline unsigned int
1630__calc_dep_bitb(struct held_lock *prev, struct held_lock *next)
1631{
1632 return (next->read != 2) + ((prev->read == 0) << 1);
1633}
1634
1635static inline u8 calc_depb(struct held_lock *prev, struct held_lock *next)
1636{
1637 return 1U << __calc_dep_bitb(prev, next);
1638}
1639
1640/*
1641 * Initialize a lock_list entry @lock belonging to @class as the root for a BFS
1642 * search.
1643 */
1644static inline void __bfs_init_root(struct lock_list *lock,
1645 struct lock_class *class)
1646{
1647 lock->class = class;
1648 lock->parent = NULL;
1649 lock->only_xr = 0;
1650}
1651
1652/*
1653 * Initialize a lock_list entry @lock based on a lock acquisition @hlock as the
1654 * root for a BFS search.
1655 *
1656 * ->only_xr of the initial lock node is set to @hlock->read == 2, to make sure
1657 * that <prev> -> @hlock and @hlock -> <whatever __bfs() found> is not -(*R)->
1658 * and -(S*)->.
1659 */
1660static inline void bfs_init_root(struct lock_list *lock,
1661 struct held_lock *hlock)
1662{
1663 __bfs_init_root(lock, hlock_class(hlock));
1664 lock->only_xr = (hlock->read == 2);
1665}
1666
1667/*
1668 * Similar to bfs_init_root() but initialize the root for backwards BFS.
1669 *
1670 * ->only_xr of the initial lock node is set to @hlock->read != 0, to make sure
1671 * that <next> -> @hlock and @hlock -> <whatever backwards BFS found> is not
1672 * -(*S)-> and -(R*)-> (reverse order of -(*R)-> and -(S*)->).
1673 */
1674static inline void bfs_init_rootb(struct lock_list *lock,
1675 struct held_lock *hlock)
1676{
1677 __bfs_init_root(lock, hlock_class(hlock));
1678 lock->only_xr = (hlock->read != 0);
1679}
1680
1681static inline struct lock_list *__bfs_next(struct lock_list *lock, int offset)
1682{
1683 if (!lock || !lock->parent)
1684 return NULL;
1685
1686 return list_next_or_null_rcu(get_dep_list(lock->parent, offset),
1687 &lock->entry, struct lock_list, entry);
1688}
1689
1690/*
1691 * Breadth-First Search to find a strong path in the dependency graph.
1692 *
1693 * @source_entry: the source of the path we are searching for.
1694 * @data: data used for the second parameter of @match function
1695 * @match: match function for the search
1696 * @target_entry: pointer to the target of a matched path
1697 * @offset: the offset to struct lock_class to determine whether it is
1698 * locks_after or locks_before
1699 *
1700 * We may have multiple edges (considering different kinds of dependencies,
1701 * e.g. ER and SN) between two nodes in the dependency graph. But
1702 * only the strong dependency path in the graph is relevant to deadlocks. A
1703 * strong dependency path is a dependency path that doesn't have two adjacent
1704 * dependencies as -(*R)-> -(S*)->, please see:
1705 *
1706 * Documentation/locking/lockdep-design.rst
1707 *
1708 * for more explanation of the definition of strong dependency paths
1709 *
1710 * In __bfs(), we only traverse in the strong dependency path:
1711 *
1712 * In lock_list::only_xr, we record whether the previous dependency only
1713 * has -(*R)-> in the search, and if it does (prev only has -(*R)->), we
1714 * filter out any -(S*)-> in the current dependency and after that, the
1715 * ->only_xr is set according to whether we only have -(*R)-> left.
1716 */
1717static enum bfs_result __bfs(struct lock_list *source_entry,
1718 void *data,
1719 bool (*match)(struct lock_list *entry, void *data),
1720 bool (*skip)(struct lock_list *entry, void *data),
1721 struct lock_list **target_entry,
1722 int offset)
1723{
1724 struct circular_queue *cq = &lock_cq;
1725 struct lock_list *lock = NULL;
1726 struct lock_list *entry;
1727 struct list_head *head;
1728 unsigned int cq_depth;
1729 bool first;
1730
1731 lockdep_assert_locked();
1732
1733 __cq_init(cq);
1734 __cq_enqueue(cq, source_entry);
1735
1736 while ((lock = __bfs_next(lock, offset)) || (lock = __cq_dequeue(cq))) {
1737 if (!lock->class)
1738 return BFS_EINVALIDNODE;
1739
1740 /*
1741 * Step 1: check whether we already finish on this one.
1742 *
1743 * If we have visited all the dependencies from this @lock to
1744 * others (iow, if we have visited all lock_list entries in
1745 * @lock->class->locks_{after,before}) we skip, otherwise go
1746 * and visit all the dependencies in the list and mark this
1747 * list accessed.
1748 */
1749 if (lock_accessed(lock))
1750 continue;
1751 else
1752 mark_lock_accessed(lock);
1753
1754 /*
1755 * Step 2: check whether prev dependency and this form a strong
1756 * dependency path.
1757 */
1758 if (lock->parent) { /* Parent exists, check prev dependency */
1759 u8 dep = lock->dep;
1760 bool prev_only_xr = lock->parent->only_xr;
1761
1762 /*
1763 * Mask out all -(S*)-> if we only have *R in previous
1764 * step, because -(*R)-> -(S*)-> don't make up a strong
1765 * dependency.
1766 */
1767 if (prev_only_xr)
1768 dep &= ~(DEP_SR_MASK | DEP_SN_MASK);
1769
1770 /* If nothing left, we skip */
1771 if (!dep)
1772 continue;
1773
1774 /* If there are only -(*R)-> left, set that for the next step */
1775 lock->only_xr = !(dep & (DEP_SN_MASK | DEP_EN_MASK));
1776 }
1777
1778 /*
1779 * Step 3: we haven't visited this and there is a strong
1780 * dependency path to this, so check with @match.
1781 * If @skip is provide and returns true, we skip this
1782 * lock (and any path this lock is in).
1783 */
1784 if (skip && skip(lock, data))
1785 continue;
1786
1787 if (match(lock, data)) {
1788 *target_entry = lock;
1789 return BFS_RMATCH;
1790 }
1791
1792 /*
1793 * Step 4: if not match, expand the path by adding the
1794 * forward or backwards dependencies in the search
1795 *
1796 */
1797 first = true;
1798 head = get_dep_list(lock, offset);
1799 list_for_each_entry_rcu(entry, head, entry) {
1800 visit_lock_entry(entry, lock);
1801
1802 /*
1803 * Note we only enqueue the first of the list into the
1804 * queue, because we can always find a sibling
1805 * dependency from one (see __bfs_next()), as a result
1806 * the space of queue is saved.
1807 */
1808 if (!first)
1809 continue;
1810
1811 first = false;
1812
1813 if (__cq_enqueue(cq, entry))
1814 return BFS_EQUEUEFULL;
1815
1816 cq_depth = __cq_get_elem_count(cq);
1817 if (max_bfs_queue_depth < cq_depth)
1818 max_bfs_queue_depth = cq_depth;
1819 }
1820 }
1821
1822 return BFS_RNOMATCH;
1823}
1824
1825static inline enum bfs_result
1826__bfs_forwards(struct lock_list *src_entry,
1827 void *data,
1828 bool (*match)(struct lock_list *entry, void *data),
1829 bool (*skip)(struct lock_list *entry, void *data),
1830 struct lock_list **target_entry)
1831{
1832 return __bfs(src_entry, data, match, skip, target_entry,
1833 offsetof(struct lock_class, locks_after));
1834
1835}
1836
1837static inline enum bfs_result
1838__bfs_backwards(struct lock_list *src_entry,
1839 void *data,
1840 bool (*match)(struct lock_list *entry, void *data),
1841 bool (*skip)(struct lock_list *entry, void *data),
1842 struct lock_list **target_entry)
1843{
1844 return __bfs(src_entry, data, match, skip, target_entry,
1845 offsetof(struct lock_class, locks_before));
1846
1847}
1848
1849static void print_lock_trace(const struct lock_trace *trace,
1850 unsigned int spaces)
1851{
1852 stack_trace_print(trace->entries, trace->nr_entries, spaces);
1853}
1854
1855/*
1856 * Print a dependency chain entry (this is only done when a deadlock
1857 * has been detected):
1858 */
1859static noinline void
1860print_circular_bug_entry(struct lock_list *target, int depth)
1861{
1862 if (debug_locks_silent)
1863 return;
1864 printk("\n-> #%u", depth);
1865 print_lock_name(NULL, target->class);
1866 printk(KERN_CONT ":\n");
1867 print_lock_trace(target->trace, 6);
1868}
1869
1870static void
1871print_circular_lock_scenario(struct held_lock *src,
1872 struct held_lock *tgt,
1873 struct lock_list *prt)
1874{
1875 struct lock_class *source = hlock_class(src);
1876 struct lock_class *target = hlock_class(tgt);
1877 struct lock_class *parent = prt->class;
1878 int src_read = src->read;
1879 int tgt_read = tgt->read;
1880
1881 /*
1882 * A direct locking problem where unsafe_class lock is taken
1883 * directly by safe_class lock, then all we need to show
1884 * is the deadlock scenario, as it is obvious that the
1885 * unsafe lock is taken under the safe lock.
1886 *
1887 * But if there is a chain instead, where the safe lock takes
1888 * an intermediate lock (middle_class) where this lock is
1889 * not the same as the safe lock, then the lock chain is
1890 * used to describe the problem. Otherwise we would need
1891 * to show a different CPU case for each link in the chain
1892 * from the safe_class lock to the unsafe_class lock.
1893 */
1894 if (parent != source) {
1895 printk("Chain exists of:\n ");
1896 __print_lock_name(src, source);
1897 printk(KERN_CONT " --> ");
1898 __print_lock_name(NULL, parent);
1899 printk(KERN_CONT " --> ");
1900 __print_lock_name(tgt, target);
1901 printk(KERN_CONT "\n\n");
1902 }
1903
1904 printk(" Possible unsafe locking scenario:\n\n");
1905 printk(" CPU0 CPU1\n");
1906 printk(" ---- ----\n");
1907 if (tgt_read != 0)
1908 printk(" rlock(");
1909 else
1910 printk(" lock(");
1911 __print_lock_name(tgt, target);
1912 printk(KERN_CONT ");\n");
1913 printk(" lock(");
1914 __print_lock_name(NULL, parent);
1915 printk(KERN_CONT ");\n");
1916 printk(" lock(");
1917 __print_lock_name(tgt, target);
1918 printk(KERN_CONT ");\n");
1919 if (src_read != 0)
1920 printk(" rlock(");
1921 else if (src->sync)
1922 printk(" sync(");
1923 else
1924 printk(" lock(");
1925 __print_lock_name(src, source);
1926 printk(KERN_CONT ");\n");
1927 printk("\n *** DEADLOCK ***\n\n");
1928}
1929
1930/*
1931 * When a circular dependency is detected, print the
1932 * header first:
1933 */
1934static noinline void
1935print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1936 struct held_lock *check_src,
1937 struct held_lock *check_tgt)
1938{
1939 struct task_struct *curr = current;
1940
1941 if (debug_locks_silent)
1942 return;
1943
1944 pr_warn("\n");
1945 pr_warn("======================================================\n");
1946 pr_warn("WARNING: possible circular locking dependency detected\n");
1947 print_kernel_ident();
1948 pr_warn("------------------------------------------------------\n");
1949 pr_warn("%s/%d is trying to acquire lock:\n",
1950 curr->comm, task_pid_nr(curr));
1951 print_lock(check_src);
1952
1953 pr_warn("\nbut task is already holding lock:\n");
1954
1955 print_lock(check_tgt);
1956 pr_warn("\nwhich lock already depends on the new lock.\n\n");
1957 pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1958
1959 print_circular_bug_entry(entry, depth);
1960}
1961
1962/*
1963 * We are about to add A -> B into the dependency graph, and in __bfs() a
1964 * strong dependency path A -> .. -> B is found: hlock_class equals
1965 * entry->class.
1966 *
1967 * If A -> .. -> B can replace A -> B in any __bfs() search (means the former
1968 * is _stronger_ than or equal to the latter), we consider A -> B as redundant.
1969 * For example if A -> .. -> B is -(EN)-> (i.e. A -(E*)-> .. -(*N)-> B), and A
1970 * -> B is -(ER)-> or -(EN)->, then we don't need to add A -> B into the
1971 * dependency graph, as any strong path ..-> A -> B ->.. we can get with
1972 * having dependency A -> B, we could already get a equivalent path ..-> A ->
1973 * .. -> B -> .. with A -> .. -> B. Therefore A -> B is redundant.
1974 *
1975 * We need to make sure both the start and the end of A -> .. -> B is not
1976 * weaker than A -> B. For the start part, please see the comment in
1977 * check_redundant(). For the end part, we need:
1978 *
1979 * Either
1980 *
1981 * a) A -> B is -(*R)-> (everything is not weaker than that)
1982 *
1983 * or
1984 *
1985 * b) A -> .. -> B is -(*N)-> (nothing is stronger than this)
1986 *
1987 */
1988static inline bool hlock_equal(struct lock_list *entry, void *data)
1989{
1990 struct held_lock *hlock = (struct held_lock *)data;
1991
1992 return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */
1993 (hlock->read == 2 || /* A -> B is -(*R)-> */
1994 !entry->only_xr); /* A -> .. -> B is -(*N)-> */
1995}
1996
1997/*
1998 * We are about to add B -> A into the dependency graph, and in __bfs() a
1999 * strong dependency path A -> .. -> B is found: hlock_class equals
2000 * entry->class.
2001 *
2002 * We will have a deadlock case (conflict) if A -> .. -> B -> A is a strong
2003 * dependency cycle, that means:
2004 *
2005 * Either
2006 *
2007 * a) B -> A is -(E*)->
2008 *
2009 * or
2010 *
2011 * b) A -> .. -> B is -(*N)-> (i.e. A -> .. -(*N)-> B)
2012 *
2013 * as then we don't have -(*R)-> -(S*)-> in the cycle.
2014 */
2015static inline bool hlock_conflict(struct lock_list *entry, void *data)
2016{
2017 struct held_lock *hlock = (struct held_lock *)data;
2018
2019 return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */
2020 (hlock->read == 0 || /* B -> A is -(E*)-> */
2021 !entry->only_xr); /* A -> .. -> B is -(*N)-> */
2022}
2023
2024static noinline void print_circular_bug(struct lock_list *this,
2025 struct lock_list *target,
2026 struct held_lock *check_src,
2027 struct held_lock *check_tgt)
2028{
2029 struct task_struct *curr = current;
2030 struct lock_list *parent;
2031 struct lock_list *first_parent;
2032 int depth;
2033
2034 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2035 return;
2036
2037 this->trace = save_trace();
2038 if (!this->trace)
2039 return;
2040
2041 depth = get_lock_depth(target);
2042
2043 print_circular_bug_header(target, depth, check_src, check_tgt);
2044
2045 parent = get_lock_parent(target);
2046 first_parent = parent;
2047
2048 while (parent) {
2049 print_circular_bug_entry(parent, --depth);
2050 parent = get_lock_parent(parent);
2051 }
2052
2053 printk("\nother info that might help us debug this:\n\n");
2054 print_circular_lock_scenario(check_src, check_tgt,
2055 first_parent);
2056
2057 lockdep_print_held_locks(curr);
2058
2059 printk("\nstack backtrace:\n");
2060 dump_stack();
2061}
2062
2063static noinline void print_bfs_bug(int ret)
2064{
2065 if (!debug_locks_off_graph_unlock())
2066 return;
2067
2068 /*
2069 * Breadth-first-search failed, graph got corrupted?
2070 */
2071 WARN(1, "lockdep bfs error:%d\n", ret);
2072}
2073
2074static bool noop_count(struct lock_list *entry, void *data)
2075{
2076 (*(unsigned long *)data)++;
2077 return false;
2078}
2079
2080static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
2081{
2082 unsigned long count = 0;
2083 struct lock_list *target_entry;
2084
2085 __bfs_forwards(this, (void *)&count, noop_count, NULL, &target_entry);
2086
2087 return count;
2088}
2089unsigned long lockdep_count_forward_deps(struct lock_class *class)
2090{
2091 unsigned long ret, flags;
2092 struct lock_list this;
2093
2094 __bfs_init_root(&this, class);
2095
2096 raw_local_irq_save(flags);
2097 lockdep_lock();
2098 ret = __lockdep_count_forward_deps(&this);
2099 lockdep_unlock();
2100 raw_local_irq_restore(flags);
2101
2102 return ret;
2103}
2104
2105static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
2106{
2107 unsigned long count = 0;
2108 struct lock_list *target_entry;
2109
2110 __bfs_backwards(this, (void *)&count, noop_count, NULL, &target_entry);
2111
2112 return count;
2113}
2114
2115unsigned long lockdep_count_backward_deps(struct lock_class *class)
2116{
2117 unsigned long ret, flags;
2118 struct lock_list this;
2119
2120 __bfs_init_root(&this, class);
2121
2122 raw_local_irq_save(flags);
2123 lockdep_lock();
2124 ret = __lockdep_count_backward_deps(&this);
2125 lockdep_unlock();
2126 raw_local_irq_restore(flags);
2127
2128 return ret;
2129}
2130
2131/*
2132 * Check that the dependency graph starting at <src> can lead to
2133 * <target> or not.
2134 */
2135static noinline enum bfs_result
2136check_path(struct held_lock *target, struct lock_list *src_entry,
2137 bool (*match)(struct lock_list *entry, void *data),
2138 bool (*skip)(struct lock_list *entry, void *data),
2139 struct lock_list **target_entry)
2140{
2141 enum bfs_result ret;
2142
2143 ret = __bfs_forwards(src_entry, target, match, skip, target_entry);
2144
2145 if (unlikely(bfs_error(ret)))
2146 print_bfs_bug(ret);
2147
2148 return ret;
2149}
2150
2151static void print_deadlock_bug(struct task_struct *, struct held_lock *, struct held_lock *);
2152
2153/*
2154 * Prove that the dependency graph starting at <src> can not
2155 * lead to <target>. If it can, there is a circle when adding
2156 * <target> -> <src> dependency.
2157 *
2158 * Print an error and return BFS_RMATCH if it does.
2159 */
2160static noinline enum bfs_result
2161check_noncircular(struct held_lock *src, struct held_lock *target,
2162 struct lock_trace **const trace)
2163{
2164 enum bfs_result ret;
2165 struct lock_list *target_entry;
2166 struct lock_list src_entry;
2167
2168 bfs_init_root(&src_entry, src);
2169
2170 debug_atomic_inc(nr_cyclic_checks);
2171
2172 ret = check_path(target, &src_entry, hlock_conflict, NULL, &target_entry);
2173
2174 if (unlikely(ret == BFS_RMATCH)) {
2175 if (!*trace) {
2176 /*
2177 * If save_trace fails here, the printing might
2178 * trigger a WARN but because of the !nr_entries it
2179 * should not do bad things.
2180 */
2181 *trace = save_trace();
2182 }
2183
2184 if (src->class_idx == target->class_idx)
2185 print_deadlock_bug(current, src, target);
2186 else
2187 print_circular_bug(&src_entry, target_entry, src, target);
2188 }
2189
2190 return ret;
2191}
2192
2193#ifdef CONFIG_TRACE_IRQFLAGS
2194
2195/*
2196 * Forwards and backwards subgraph searching, for the purposes of
2197 * proving that two subgraphs can be connected by a new dependency
2198 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
2199 *
2200 * A irq safe->unsafe deadlock happens with the following conditions:
2201 *
2202 * 1) We have a strong dependency path A -> ... -> B
2203 *
2204 * 2) and we have ENABLED_IRQ usage of B and USED_IN_IRQ usage of A, therefore
2205 * irq can create a new dependency B -> A (consider the case that a holder
2206 * of B gets interrupted by an irq whose handler will try to acquire A).
2207 *
2208 * 3) the dependency circle A -> ... -> B -> A we get from 1) and 2) is a
2209 * strong circle:
2210 *
2211 * For the usage bits of B:
2212 * a) if A -> B is -(*N)->, then B -> A could be any type, so any
2213 * ENABLED_IRQ usage suffices.
2214 * b) if A -> B is -(*R)->, then B -> A must be -(E*)->, so only
2215 * ENABLED_IRQ_*_READ usage suffices.
2216 *
2217 * For the usage bits of A:
2218 * c) if A -> B is -(E*)->, then B -> A could be any type, so any
2219 * USED_IN_IRQ usage suffices.
2220 * d) if A -> B is -(S*)->, then B -> A must be -(*N)->, so only
2221 * USED_IN_IRQ_*_READ usage suffices.
2222 */
2223
2224/*
2225 * There is a strong dependency path in the dependency graph: A -> B, and now
2226 * we need to decide which usage bit of A should be accumulated to detect
2227 * safe->unsafe bugs.
2228 *
2229 * Note that usage_accumulate() is used in backwards search, so ->only_xr
2230 * stands for whether A -> B only has -(S*)-> (in this case ->only_xr is true).
2231 *
2232 * As above, if only_xr is false, which means A -> B has -(E*)-> dependency
2233 * path, any usage of A should be considered. Otherwise, we should only
2234 * consider _READ usage.
2235 */
2236static inline bool usage_accumulate(struct lock_list *entry, void *mask)
2237{
2238 if (!entry->only_xr)
2239 *(unsigned long *)mask |= entry->class->usage_mask;
2240 else /* Mask out _READ usage bits */
2241 *(unsigned long *)mask |= (entry->class->usage_mask & LOCKF_IRQ);
2242
2243 return false;
2244}
2245
2246/*
2247 * There is a strong dependency path in the dependency graph: A -> B, and now
2248 * we need to decide which usage bit of B conflicts with the usage bits of A,
2249 * i.e. which usage bit of B may introduce safe->unsafe deadlocks.
2250 *
2251 * As above, if only_xr is false, which means A -> B has -(*N)-> dependency
2252 * path, any usage of B should be considered. Otherwise, we should only
2253 * consider _READ usage.
2254 */
2255static inline bool usage_match(struct lock_list *entry, void *mask)
2256{
2257 if (!entry->only_xr)
2258 return !!(entry->class->usage_mask & *(unsigned long *)mask);
2259 else /* Mask out _READ usage bits */
2260 return !!((entry->class->usage_mask & LOCKF_IRQ) & *(unsigned long *)mask);
2261}
2262
2263static inline bool usage_skip(struct lock_list *entry, void *mask)
2264{
2265 if (entry->class->lock_type == LD_LOCK_NORMAL)
2266 return false;
2267
2268 /*
2269 * Skip local_lock() for irq inversion detection.
2270 *
2271 * For !RT, local_lock() is not a real lock, so it won't carry any
2272 * dependency.
2273 *
2274 * For RT, an irq inversion happens when we have lock A and B, and on
2275 * some CPU we can have:
2276 *
2277 * lock(A);
2278 * <interrupted>
2279 * lock(B);
2280 *
2281 * where lock(B) cannot sleep, and we have a dependency B -> ... -> A.
2282 *
2283 * Now we prove local_lock() cannot exist in that dependency. First we
2284 * have the observation for any lock chain L1 -> ... -> Ln, for any
2285 * 1 <= i <= n, Li.inner_wait_type <= L1.inner_wait_type, otherwise
2286 * wait context check will complain. And since B is not a sleep lock,
2287 * therefore B.inner_wait_type >= 2, and since the inner_wait_type of
2288 * local_lock() is 3, which is greater than 2, therefore there is no
2289 * way the local_lock() exists in the dependency B -> ... -> A.
2290 *
2291 * As a result, we will skip local_lock(), when we search for irq
2292 * inversion bugs.
2293 */
2294 if (entry->class->lock_type == LD_LOCK_PERCPU &&
2295 DEBUG_LOCKS_WARN_ON(entry->class->wait_type_inner < LD_WAIT_CONFIG))
2296 return false;
2297
2298 /*
2299 * Skip WAIT_OVERRIDE for irq inversion detection -- it's not actually
2300 * a lock and only used to override the wait_type.
2301 */
2302
2303 return true;
2304}
2305
2306/*
2307 * Find a node in the forwards-direction dependency sub-graph starting
2308 * at @root->class that matches @bit.
2309 *
2310 * Return BFS_MATCH if such a node exists in the subgraph, and put that node
2311 * into *@target_entry.
2312 */
2313static enum bfs_result
2314find_usage_forwards(struct lock_list *root, unsigned long usage_mask,
2315 struct lock_list **target_entry)
2316{
2317 enum bfs_result result;
2318
2319 debug_atomic_inc(nr_find_usage_forwards_checks);
2320
2321 result = __bfs_forwards(root, &usage_mask, usage_match, usage_skip, target_entry);
2322
2323 return result;
2324}
2325
2326/*
2327 * Find a node in the backwards-direction dependency sub-graph starting
2328 * at @root->class that matches @bit.
2329 */
2330static enum bfs_result
2331find_usage_backwards(struct lock_list *root, unsigned long usage_mask,
2332 struct lock_list **target_entry)
2333{
2334 enum bfs_result result;
2335
2336 debug_atomic_inc(nr_find_usage_backwards_checks);
2337
2338 result = __bfs_backwards(root, &usage_mask, usage_match, usage_skip, target_entry);
2339
2340 return result;
2341}
2342
2343static void print_lock_class_header(struct lock_class *class, int depth)
2344{
2345 int bit;
2346
2347 printk("%*s->", depth, "");
2348 print_lock_name(NULL, class);
2349#ifdef CONFIG_DEBUG_LOCKDEP
2350 printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
2351#endif
2352 printk(KERN_CONT " {\n");
2353
2354 for (bit = 0; bit < LOCK_TRACE_STATES; bit++) {
2355 if (class->usage_mask & (1 << bit)) {
2356 int len = depth;
2357
2358 len += printk("%*s %s", depth, "", usage_str[bit]);
2359 len += printk(KERN_CONT " at:\n");
2360 print_lock_trace(class->usage_traces[bit], len);
2361 }
2362 }
2363 printk("%*s }\n", depth, "");
2364
2365 printk("%*s ... key at: [<%px>] %pS\n",
2366 depth, "", class->key, class->key);
2367}
2368
2369/*
2370 * Dependency path printing:
2371 *
2372 * After BFS we get a lock dependency path (linked via ->parent of lock_list),
2373 * printing out each lock in the dependency path will help on understanding how
2374 * the deadlock could happen. Here are some details about dependency path
2375 * printing:
2376 *
2377 * 1) A lock_list can be either forwards or backwards for a lock dependency,
2378 * for a lock dependency A -> B, there are two lock_lists:
2379 *
2380 * a) lock_list in the ->locks_after list of A, whose ->class is B and
2381 * ->links_to is A. In this case, we can say the lock_list is
2382 * "A -> B" (forwards case).
2383 *
2384 * b) lock_list in the ->locks_before list of B, whose ->class is A
2385 * and ->links_to is B. In this case, we can say the lock_list is
2386 * "B <- A" (bacwards case).
2387 *
2388 * The ->trace of both a) and b) point to the call trace where B was
2389 * acquired with A held.
2390 *
2391 * 2) A "helper" lock_list is introduced during BFS, this lock_list doesn't
2392 * represent a certain lock dependency, it only provides an initial entry
2393 * for BFS. For example, BFS may introduce a "helper" lock_list whose
2394 * ->class is A, as a result BFS will search all dependencies starting with
2395 * A, e.g. A -> B or A -> C.
2396 *
2397 * The notation of a forwards helper lock_list is like "-> A", which means
2398 * we should search the forwards dependencies starting with "A", e.g A -> B
2399 * or A -> C.
2400 *
2401 * The notation of a bacwards helper lock_list is like "<- B", which means
2402 * we should search the backwards dependencies ending with "B", e.g.
2403 * B <- A or B <- C.
2404 */
2405
2406/*
2407 * printk the shortest lock dependencies from @root to @leaf in reverse order.
2408 *
2409 * We have a lock dependency path as follow:
2410 *
2411 * @root @leaf
2412 * | |
2413 * V V
2414 * ->parent ->parent
2415 * | lock_list | <--------- | lock_list | ... | lock_list | <--------- | lock_list |
2416 * | -> L1 | | L1 -> L2 | ... |Ln-2 -> Ln-1| | Ln-1 -> Ln|
2417 *
2418 * , so it's natural that we start from @leaf and print every ->class and
2419 * ->trace until we reach the @root.
2420 */
2421static void __used
2422print_shortest_lock_dependencies(struct lock_list *leaf,
2423 struct lock_list *root)
2424{
2425 struct lock_list *entry = leaf;
2426 int depth;
2427
2428 /*compute depth from generated tree by BFS*/
2429 depth = get_lock_depth(leaf);
2430
2431 do {
2432 print_lock_class_header(entry->class, depth);
2433 printk("%*s ... acquired at:\n", depth, "");
2434 print_lock_trace(entry->trace, 2);
2435 printk("\n");
2436
2437 if (depth == 0 && (entry != root)) {
2438 printk("lockdep:%s bad path found in chain graph\n", __func__);
2439 break;
2440 }
2441
2442 entry = get_lock_parent(entry);
2443 depth--;
2444 } while (entry && (depth >= 0));
2445}
2446
2447/*
2448 * printk the shortest lock dependencies from @leaf to @root.
2449 *
2450 * We have a lock dependency path (from a backwards search) as follow:
2451 *
2452 * @leaf @root
2453 * | |
2454 * V V
2455 * ->parent ->parent
2456 * | lock_list | ---------> | lock_list | ... | lock_list | ---------> | lock_list |
2457 * | L2 <- L1 | | L3 <- L2 | ... | Ln <- Ln-1 | | <- Ln |
2458 *
2459 * , so when we iterate from @leaf to @root, we actually print the lock
2460 * dependency path L1 -> L2 -> .. -> Ln in the non-reverse order.
2461 *
2462 * Another thing to notice here is that ->class of L2 <- L1 is L1, while the
2463 * ->trace of L2 <- L1 is the call trace of L2, in fact we don't have the call
2464 * trace of L1 in the dependency path, which is alright, because most of the
2465 * time we can figure out where L1 is held from the call trace of L2.
2466 */
2467static void __used
2468print_shortest_lock_dependencies_backwards(struct lock_list *leaf,
2469 struct lock_list *root)
2470{
2471 struct lock_list *entry = leaf;
2472 const struct lock_trace *trace = NULL;
2473 int depth;
2474
2475 /*compute depth from generated tree by BFS*/
2476 depth = get_lock_depth(leaf);
2477
2478 do {
2479 print_lock_class_header(entry->class, depth);
2480 if (trace) {
2481 printk("%*s ... acquired at:\n", depth, "");
2482 print_lock_trace(trace, 2);
2483 printk("\n");
2484 }
2485
2486 /*
2487 * Record the pointer to the trace for the next lock_list
2488 * entry, see the comments for the function.
2489 */
2490 trace = entry->trace;
2491
2492 if (depth == 0 && (entry != root)) {
2493 printk("lockdep:%s bad path found in chain graph\n", __func__);
2494 break;
2495 }
2496
2497 entry = get_lock_parent(entry);
2498 depth--;
2499 } while (entry && (depth >= 0));
2500}
2501
2502static void
2503print_irq_lock_scenario(struct lock_list *safe_entry,
2504 struct lock_list *unsafe_entry,
2505 struct lock_class *prev_class,
2506 struct lock_class *next_class)
2507{
2508 struct lock_class *safe_class = safe_entry->class;
2509 struct lock_class *unsafe_class = unsafe_entry->class;
2510 struct lock_class *middle_class = prev_class;
2511
2512 if (middle_class == safe_class)
2513 middle_class = next_class;
2514
2515 /*
2516 * A direct locking problem where unsafe_class lock is taken
2517 * directly by safe_class lock, then all we need to show
2518 * is the deadlock scenario, as it is obvious that the
2519 * unsafe lock is taken under the safe lock.
2520 *
2521 * But if there is a chain instead, where the safe lock takes
2522 * an intermediate lock (middle_class) where this lock is
2523 * not the same as the safe lock, then the lock chain is
2524 * used to describe the problem. Otherwise we would need
2525 * to show a different CPU case for each link in the chain
2526 * from the safe_class lock to the unsafe_class lock.
2527 */
2528 if (middle_class != unsafe_class) {
2529 printk("Chain exists of:\n ");
2530 __print_lock_name(NULL, safe_class);
2531 printk(KERN_CONT " --> ");
2532 __print_lock_name(NULL, middle_class);
2533 printk(KERN_CONT " --> ");
2534 __print_lock_name(NULL, unsafe_class);
2535 printk(KERN_CONT "\n\n");
2536 }
2537
2538 printk(" Possible interrupt unsafe locking scenario:\n\n");
2539 printk(" CPU0 CPU1\n");
2540 printk(" ---- ----\n");
2541 printk(" lock(");
2542 __print_lock_name(NULL, unsafe_class);
2543 printk(KERN_CONT ");\n");
2544 printk(" local_irq_disable();\n");
2545 printk(" lock(");
2546 __print_lock_name(NULL, safe_class);
2547 printk(KERN_CONT ");\n");
2548 printk(" lock(");
2549 __print_lock_name(NULL, middle_class);
2550 printk(KERN_CONT ");\n");
2551 printk(" <Interrupt>\n");
2552 printk(" lock(");
2553 __print_lock_name(NULL, safe_class);
2554 printk(KERN_CONT ");\n");
2555 printk("\n *** DEADLOCK ***\n\n");
2556}
2557
2558static void
2559print_bad_irq_dependency(struct task_struct *curr,
2560 struct lock_list *prev_root,
2561 struct lock_list *next_root,
2562 struct lock_list *backwards_entry,
2563 struct lock_list *forwards_entry,
2564 struct held_lock *prev,
2565 struct held_lock *next,
2566 enum lock_usage_bit bit1,
2567 enum lock_usage_bit bit2,
2568 const char *irqclass)
2569{
2570 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2571 return;
2572
2573 pr_warn("\n");
2574 pr_warn("=====================================================\n");
2575 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
2576 irqclass, irqclass);
2577 print_kernel_ident();
2578 pr_warn("-----------------------------------------------------\n");
2579 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
2580 curr->comm, task_pid_nr(curr),
2581 lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
2582 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
2583 lockdep_hardirqs_enabled(),
2584 curr->softirqs_enabled);
2585 print_lock(next);
2586
2587 pr_warn("\nand this task is already holding:\n");
2588 print_lock(prev);
2589 pr_warn("which would create a new lock dependency:\n");
2590 print_lock_name(prev, hlock_class(prev));
2591 pr_cont(" ->");
2592 print_lock_name(next, hlock_class(next));
2593 pr_cont("\n");
2594
2595 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
2596 irqclass);
2597 print_lock_name(NULL, backwards_entry->class);
2598 pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
2599
2600 print_lock_trace(backwards_entry->class->usage_traces[bit1], 1);
2601
2602 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
2603 print_lock_name(NULL, forwards_entry->class);
2604 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
2605 pr_warn("...");
2606
2607 print_lock_trace(forwards_entry->class->usage_traces[bit2], 1);
2608
2609 pr_warn("\nother info that might help us debug this:\n\n");
2610 print_irq_lock_scenario(backwards_entry, forwards_entry,
2611 hlock_class(prev), hlock_class(next));
2612
2613 lockdep_print_held_locks(curr);
2614
2615 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
2616 print_shortest_lock_dependencies_backwards(backwards_entry, prev_root);
2617
2618 pr_warn("\nthe dependencies between the lock to be acquired");
2619 pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
2620 next_root->trace = save_trace();
2621 if (!next_root->trace)
2622 return;
2623 print_shortest_lock_dependencies(forwards_entry, next_root);
2624
2625 pr_warn("\nstack backtrace:\n");
2626 dump_stack();
2627}
2628
2629static const char *state_names[] = {
2630#define LOCKDEP_STATE(__STATE) \
2631 __stringify(__STATE),
2632#include "lockdep_states.h"
2633#undef LOCKDEP_STATE
2634};
2635
2636static const char *state_rnames[] = {
2637#define LOCKDEP_STATE(__STATE) \
2638 __stringify(__STATE)"-READ",
2639#include "lockdep_states.h"
2640#undef LOCKDEP_STATE
2641};
2642
2643static inline const char *state_name(enum lock_usage_bit bit)
2644{
2645 if (bit & LOCK_USAGE_READ_MASK)
2646 return state_rnames[bit >> LOCK_USAGE_DIR_MASK];
2647 else
2648 return state_names[bit >> LOCK_USAGE_DIR_MASK];
2649}
2650
2651/*
2652 * The bit number is encoded like:
2653 *
2654 * bit0: 0 exclusive, 1 read lock
2655 * bit1: 0 used in irq, 1 irq enabled
2656 * bit2-n: state
2657 */
2658static int exclusive_bit(int new_bit)
2659{
2660 int state = new_bit & LOCK_USAGE_STATE_MASK;
2661 int dir = new_bit & LOCK_USAGE_DIR_MASK;
2662
2663 /*
2664 * keep state, bit flip the direction and strip read.
2665 */
2666 return state | (dir ^ LOCK_USAGE_DIR_MASK);
2667}
2668
2669/*
2670 * Observe that when given a bitmask where each bitnr is encoded as above, a
2671 * right shift of the mask transforms the individual bitnrs as -1 and
2672 * conversely, a left shift transforms into +1 for the individual bitnrs.
2673 *
2674 * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can
2675 * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0)
2676 * instead by subtracting the bit number by 2, or shifting the mask right by 2.
2677 *
2678 * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2.
2679 *
2680 * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is
2681 * all bits set) and recompose with bitnr1 flipped.
2682 */
2683static unsigned long invert_dir_mask(unsigned long mask)
2684{
2685 unsigned long excl = 0;
2686
2687 /* Invert dir */
2688 excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK;
2689 excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK;
2690
2691 return excl;
2692}
2693
2694/*
2695 * Note that a LOCK_ENABLED_IRQ_*_READ usage and a LOCK_USED_IN_IRQ_*_READ
2696 * usage may cause deadlock too, for example:
2697 *
2698 * P1 P2
2699 * <irq disabled>
2700 * write_lock(l1); <irq enabled>
2701 * read_lock(l2);
2702 * write_lock(l2);
2703 * <in irq>
2704 * read_lock(l1);
2705 *
2706 * , in above case, l1 will be marked as LOCK_USED_IN_IRQ_HARDIRQ_READ and l2
2707 * will marked as LOCK_ENABLE_IRQ_HARDIRQ_READ, and this is a possible
2708 * deadlock.
2709 *
2710 * In fact, all of the following cases may cause deadlocks:
2711 *
2712 * LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_*
2713 * LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_*
2714 * LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_*_READ
2715 * LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_*_READ
2716 *
2717 * As a result, to calculate the "exclusive mask", first we invert the
2718 * direction (USED_IN/ENABLED) of the original mask, and 1) for all bits with
2719 * bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*). 2) for all
2720 * bits with bitnr0 cleared (LOCK_*_READ), add those with bitnr0 set (LOCK_*).
2721 */
2722static unsigned long exclusive_mask(unsigned long mask)
2723{
2724 unsigned long excl = invert_dir_mask(mask);
2725
2726 excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
2727 excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
2728
2729 return excl;
2730}
2731
2732/*
2733 * Retrieve the _possible_ original mask to which @mask is
2734 * exclusive. Ie: this is the opposite of exclusive_mask().
2735 * Note that 2 possible original bits can match an exclusive
2736 * bit: one has LOCK_USAGE_READ_MASK set, the other has it
2737 * cleared. So both are returned for each exclusive bit.
2738 */
2739static unsigned long original_mask(unsigned long mask)
2740{
2741 unsigned long excl = invert_dir_mask(mask);
2742
2743 /* Include read in existing usages */
2744 excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
2745 excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
2746
2747 return excl;
2748}
2749
2750/*
2751 * Find the first pair of bit match between an original
2752 * usage mask and an exclusive usage mask.
2753 */
2754static int find_exclusive_match(unsigned long mask,
2755 unsigned long excl_mask,
2756 enum lock_usage_bit *bitp,
2757 enum lock_usage_bit *excl_bitp)
2758{
2759 int bit, excl, excl_read;
2760
2761 for_each_set_bit(bit, &mask, LOCK_USED) {
2762 /*
2763 * exclusive_bit() strips the read bit, however,
2764 * LOCK_ENABLED_IRQ_*_READ may cause deadlocks too, so we need
2765 * to search excl | LOCK_USAGE_READ_MASK as well.
2766 */
2767 excl = exclusive_bit(bit);
2768 excl_read = excl | LOCK_USAGE_READ_MASK;
2769 if (excl_mask & lock_flag(excl)) {
2770 *bitp = bit;
2771 *excl_bitp = excl;
2772 return 0;
2773 } else if (excl_mask & lock_flag(excl_read)) {
2774 *bitp = bit;
2775 *excl_bitp = excl_read;
2776 return 0;
2777 }
2778 }
2779 return -1;
2780}
2781
2782/*
2783 * Prove that the new dependency does not connect a hardirq-safe(-read)
2784 * lock with a hardirq-unsafe lock - to achieve this we search
2785 * the backwards-subgraph starting at <prev>, and the
2786 * forwards-subgraph starting at <next>:
2787 */
2788static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
2789 struct held_lock *next)
2790{
2791 unsigned long usage_mask = 0, forward_mask, backward_mask;
2792 enum lock_usage_bit forward_bit = 0, backward_bit = 0;
2793 struct lock_list *target_entry1;
2794 struct lock_list *target_entry;
2795 struct lock_list this, that;
2796 enum bfs_result ret;
2797
2798 /*
2799 * Step 1: gather all hard/soft IRQs usages backward in an
2800 * accumulated usage mask.
2801 */
2802 bfs_init_rootb(&this, prev);
2803
2804 ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, usage_skip, NULL);
2805 if (bfs_error(ret)) {
2806 print_bfs_bug(ret);
2807 return 0;
2808 }
2809
2810 usage_mask &= LOCKF_USED_IN_IRQ_ALL;
2811 if (!usage_mask)
2812 return 1;
2813
2814 /*
2815 * Step 2: find exclusive uses forward that match the previous
2816 * backward accumulated mask.
2817 */
2818 forward_mask = exclusive_mask(usage_mask);
2819
2820 bfs_init_root(&that, next);
2821
2822 ret = find_usage_forwards(&that, forward_mask, &target_entry1);
2823 if (bfs_error(ret)) {
2824 print_bfs_bug(ret);
2825 return 0;
2826 }
2827 if (ret == BFS_RNOMATCH)
2828 return 1;
2829
2830 /*
2831 * Step 3: we found a bad match! Now retrieve a lock from the backward
2832 * list whose usage mask matches the exclusive usage mask from the
2833 * lock found on the forward list.
2834 *
2835 * Note, we should only keep the LOCKF_ENABLED_IRQ_ALL bits, considering
2836 * the follow case:
2837 *
2838 * When trying to add A -> B to the graph, we find that there is a
2839 * hardirq-safe L, that L -> ... -> A, and another hardirq-unsafe M,
2840 * that B -> ... -> M. However M is **softirq-safe**, if we use exact
2841 * invert bits of M's usage_mask, we will find another lock N that is
2842 * **softirq-unsafe** and N -> ... -> A, however N -> .. -> M will not
2843 * cause a inversion deadlock.
2844 */
2845 backward_mask = original_mask(target_entry1->class->usage_mask & LOCKF_ENABLED_IRQ_ALL);
2846
2847 ret = find_usage_backwards(&this, backward_mask, &target_entry);
2848 if (bfs_error(ret)) {
2849 print_bfs_bug(ret);
2850 return 0;
2851 }
2852 if (DEBUG_LOCKS_WARN_ON(ret == BFS_RNOMATCH))
2853 return 1;
2854
2855 /*
2856 * Step 4: narrow down to a pair of incompatible usage bits
2857 * and report it.
2858 */
2859 ret = find_exclusive_match(target_entry->class->usage_mask,
2860 target_entry1->class->usage_mask,
2861 &backward_bit, &forward_bit);
2862 if (DEBUG_LOCKS_WARN_ON(ret == -1))
2863 return 1;
2864
2865 print_bad_irq_dependency(curr, &this, &that,
2866 target_entry, target_entry1,
2867 prev, next,
2868 backward_bit, forward_bit,
2869 state_name(backward_bit));
2870
2871 return 0;
2872}
2873
2874#else
2875
2876static inline int check_irq_usage(struct task_struct *curr,
2877 struct held_lock *prev, struct held_lock *next)
2878{
2879 return 1;
2880}
2881
2882static inline bool usage_skip(struct lock_list *entry, void *mask)
2883{
2884 return false;
2885}
2886
2887#endif /* CONFIG_TRACE_IRQFLAGS */
2888
2889#ifdef CONFIG_LOCKDEP_SMALL
2890/*
2891 * Check that the dependency graph starting at <src> can lead to
2892 * <target> or not. If it can, <src> -> <target> dependency is already
2893 * in the graph.
2894 *
2895 * Return BFS_RMATCH if it does, or BFS_RNOMATCH if it does not, return BFS_E* if
2896 * any error appears in the bfs search.
2897 */
2898static noinline enum bfs_result
2899check_redundant(struct held_lock *src, struct held_lock *target)
2900{
2901 enum bfs_result ret;
2902 struct lock_list *target_entry;
2903 struct lock_list src_entry;
2904
2905 bfs_init_root(&src_entry, src);
2906 /*
2907 * Special setup for check_redundant().
2908 *
2909 * To report redundant, we need to find a strong dependency path that
2910 * is equal to or stronger than <src> -> <target>. So if <src> is E,
2911 * we need to let __bfs() only search for a path starting at a -(E*)->,
2912 * we achieve this by setting the initial node's ->only_xr to true in
2913 * that case. And if <prev> is S, we set initial ->only_xr to false
2914 * because both -(S*)-> (equal) and -(E*)-> (stronger) are redundant.
2915 */
2916 src_entry.only_xr = src->read == 0;
2917
2918 debug_atomic_inc(nr_redundant_checks);
2919
2920 /*
2921 * Note: we skip local_lock() for redundant check, because as the
2922 * comment in usage_skip(), A -> local_lock() -> B and A -> B are not
2923 * the same.
2924 */
2925 ret = check_path(target, &src_entry, hlock_equal, usage_skip, &target_entry);
2926
2927 if (ret == BFS_RMATCH)
2928 debug_atomic_inc(nr_redundant);
2929
2930 return ret;
2931}
2932
2933#else
2934
2935static inline enum bfs_result
2936check_redundant(struct held_lock *src, struct held_lock *target)
2937{
2938 return BFS_RNOMATCH;
2939}
2940
2941#endif
2942
2943static void inc_chains(int irq_context)
2944{
2945 if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
2946 nr_hardirq_chains++;
2947 else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
2948 nr_softirq_chains++;
2949 else
2950 nr_process_chains++;
2951}
2952
2953static void dec_chains(int irq_context)
2954{
2955 if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
2956 nr_hardirq_chains--;
2957 else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
2958 nr_softirq_chains--;
2959 else
2960 nr_process_chains--;
2961}
2962
2963static void
2964print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
2965{
2966 struct lock_class *next = hlock_class(nxt);
2967 struct lock_class *prev = hlock_class(prv);
2968
2969 printk(" Possible unsafe locking scenario:\n\n");
2970 printk(" CPU0\n");
2971 printk(" ----\n");
2972 printk(" lock(");
2973 __print_lock_name(prv, prev);
2974 printk(KERN_CONT ");\n");
2975 printk(" lock(");
2976 __print_lock_name(nxt, next);
2977 printk(KERN_CONT ");\n");
2978 printk("\n *** DEADLOCK ***\n\n");
2979 printk(" May be due to missing lock nesting notation\n\n");
2980}
2981
2982static void
2983print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
2984 struct held_lock *next)
2985{
2986 struct lock_class *class = hlock_class(prev);
2987
2988 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2989 return;
2990
2991 pr_warn("\n");
2992 pr_warn("============================================\n");
2993 pr_warn("WARNING: possible recursive locking detected\n");
2994 print_kernel_ident();
2995 pr_warn("--------------------------------------------\n");
2996 pr_warn("%s/%d is trying to acquire lock:\n",
2997 curr->comm, task_pid_nr(curr));
2998 print_lock(next);
2999 pr_warn("\nbut task is already holding lock:\n");
3000 print_lock(prev);
3001
3002 if (class->cmp_fn) {
3003 pr_warn("and the lock comparison function returns %i:\n",
3004 class->cmp_fn(prev->instance, next->instance));
3005 }
3006
3007 pr_warn("\nother info that might help us debug this:\n");
3008 print_deadlock_scenario(next, prev);
3009 lockdep_print_held_locks(curr);
3010
3011 pr_warn("\nstack backtrace:\n");
3012 dump_stack();
3013}
3014
3015/*
3016 * Check whether we are holding such a class already.
3017 *
3018 * (Note that this has to be done separately, because the graph cannot
3019 * detect such classes of deadlocks.)
3020 *
3021 * Returns: 0 on deadlock detected, 1 on OK, 2 if another lock with the same
3022 * lock class is held but nest_lock is also held, i.e. we rely on the
3023 * nest_lock to avoid the deadlock.
3024 */
3025static int
3026check_deadlock(struct task_struct *curr, struct held_lock *next)
3027{
3028 struct lock_class *class;
3029 struct held_lock *prev;
3030 struct held_lock *nest = NULL;
3031 int i;
3032
3033 for (i = 0; i < curr->lockdep_depth; i++) {
3034 prev = curr->held_locks + i;
3035
3036 if (prev->instance == next->nest_lock)
3037 nest = prev;
3038
3039 if (hlock_class(prev) != hlock_class(next))
3040 continue;
3041
3042 /*
3043 * Allow read-after-read recursion of the same
3044 * lock class (i.e. read_lock(lock)+read_lock(lock)):
3045 */
3046 if ((next->read == 2) && prev->read)
3047 continue;
3048
3049 class = hlock_class(prev);
3050
3051 if (class->cmp_fn &&
3052 class->cmp_fn(prev->instance, next->instance) < 0)
3053 continue;
3054
3055 /*
3056 * We're holding the nest_lock, which serializes this lock's
3057 * nesting behaviour.
3058 */
3059 if (nest)
3060 return 2;
3061
3062 print_deadlock_bug(curr, prev, next);
3063 return 0;
3064 }
3065 return 1;
3066}
3067
3068/*
3069 * There was a chain-cache miss, and we are about to add a new dependency
3070 * to a previous lock. We validate the following rules:
3071 *
3072 * - would the adding of the <prev> -> <next> dependency create a
3073 * circular dependency in the graph? [== circular deadlock]
3074 *
3075 * - does the new prev->next dependency connect any hardirq-safe lock
3076 * (in the full backwards-subgraph starting at <prev>) with any
3077 * hardirq-unsafe lock (in the full forwards-subgraph starting at
3078 * <next>)? [== illegal lock inversion with hardirq contexts]
3079 *
3080 * - does the new prev->next dependency connect any softirq-safe lock
3081 * (in the full backwards-subgraph starting at <prev>) with any
3082 * softirq-unsafe lock (in the full forwards-subgraph starting at
3083 * <next>)? [== illegal lock inversion with softirq contexts]
3084 *
3085 * any of these scenarios could lead to a deadlock.
3086 *
3087 * Then if all the validations pass, we add the forwards and backwards
3088 * dependency.
3089 */
3090static int
3091check_prev_add(struct task_struct *curr, struct held_lock *prev,
3092 struct held_lock *next, u16 distance,
3093 struct lock_trace **const trace)
3094{
3095 struct lock_list *entry;
3096 enum bfs_result ret;
3097
3098 if (!hlock_class(prev)->key || !hlock_class(next)->key) {
3099 /*
3100 * The warning statements below may trigger a use-after-free
3101 * of the class name. It is better to trigger a use-after free
3102 * and to have the class name most of the time instead of not
3103 * having the class name available.
3104 */
3105 WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key,
3106 "Detected use-after-free of lock class %px/%s\n",
3107 hlock_class(prev),
3108 hlock_class(prev)->name);
3109 WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key,
3110 "Detected use-after-free of lock class %px/%s\n",
3111 hlock_class(next),
3112 hlock_class(next)->name);
3113 return 2;
3114 }
3115
3116 if (prev->class_idx == next->class_idx) {
3117 struct lock_class *class = hlock_class(prev);
3118
3119 if (class->cmp_fn &&
3120 class->cmp_fn(prev->instance, next->instance) < 0)
3121 return 2;
3122 }
3123
3124 /*
3125 * Prove that the new <prev> -> <next> dependency would not
3126 * create a circular dependency in the graph. (We do this by
3127 * a breadth-first search into the graph starting at <next>,
3128 * and check whether we can reach <prev>.)
3129 *
3130 * The search is limited by the size of the circular queue (i.e.,
3131 * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes
3132 * in the graph whose neighbours are to be checked.
3133 */
3134 ret = check_noncircular(next, prev, trace);
3135 if (unlikely(bfs_error(ret) || ret == BFS_RMATCH))
3136 return 0;
3137
3138 if (!check_irq_usage(curr, prev, next))
3139 return 0;
3140
3141 /*
3142 * Is the <prev> -> <next> dependency already present?
3143 *
3144 * (this may occur even though this is a new chain: consider
3145 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
3146 * chains - the second one will be new, but L1 already has
3147 * L2 added to its dependency list, due to the first chain.)
3148 */
3149 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
3150 if (entry->class == hlock_class(next)) {
3151 if (distance == 1)
3152 entry->distance = 1;
3153 entry->dep |= calc_dep(prev, next);
3154
3155 /*
3156 * Also, update the reverse dependency in @next's
3157 * ->locks_before list.
3158 *
3159 * Here we reuse @entry as the cursor, which is fine
3160 * because we won't go to the next iteration of the
3161 * outer loop:
3162 *
3163 * For normal cases, we return in the inner loop.
3164 *
3165 * If we fail to return, we have inconsistency, i.e.
3166 * <prev>::locks_after contains <next> while
3167 * <next>::locks_before doesn't contain <prev>. In
3168 * that case, we return after the inner and indicate
3169 * something is wrong.
3170 */
3171 list_for_each_entry(entry, &hlock_class(next)->locks_before, entry) {
3172 if (entry->class == hlock_class(prev)) {
3173 if (distance == 1)
3174 entry->distance = 1;
3175 entry->dep |= calc_depb(prev, next);
3176 return 1;
3177 }
3178 }
3179
3180 /* <prev> is not found in <next>::locks_before */
3181 return 0;
3182 }
3183 }
3184
3185 /*
3186 * Is the <prev> -> <next> link redundant?
3187 */
3188 ret = check_redundant(prev, next);
3189 if (bfs_error(ret))
3190 return 0;
3191 else if (ret == BFS_RMATCH)
3192 return 2;
3193
3194 if (!*trace) {
3195 *trace = save_trace();
3196 if (!*trace)
3197 return 0;
3198 }
3199
3200 /*
3201 * Ok, all validations passed, add the new lock
3202 * to the previous lock's dependency list:
3203 */
3204 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
3205 &hlock_class(prev)->locks_after, distance,
3206 calc_dep(prev, next), *trace);
3207
3208 if (!ret)
3209 return 0;
3210
3211 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
3212 &hlock_class(next)->locks_before, distance,
3213 calc_depb(prev, next), *trace);
3214 if (!ret)
3215 return 0;
3216
3217 return 2;
3218}
3219
3220/*
3221 * Add the dependency to all directly-previous locks that are 'relevant'.
3222 * The ones that are relevant are (in increasing distance from curr):
3223 * all consecutive trylock entries and the final non-trylock entry - or
3224 * the end of this context's lock-chain - whichever comes first.
3225 */
3226static int
3227check_prevs_add(struct task_struct *curr, struct held_lock *next)
3228{
3229 struct lock_trace *trace = NULL;
3230 int depth = curr->lockdep_depth;
3231 struct held_lock *hlock;
3232
3233 /*
3234 * Debugging checks.
3235 *
3236 * Depth must not be zero for a non-head lock:
3237 */
3238 if (!depth)
3239 goto out_bug;
3240 /*
3241 * At least two relevant locks must exist for this
3242 * to be a head:
3243 */
3244 if (curr->held_locks[depth].irq_context !=
3245 curr->held_locks[depth-1].irq_context)
3246 goto out_bug;
3247
3248 for (;;) {
3249 u16 distance = curr->lockdep_depth - depth + 1;
3250 hlock = curr->held_locks + depth - 1;
3251
3252 if (hlock->check) {
3253 int ret = check_prev_add(curr, hlock, next, distance, &trace);
3254 if (!ret)
3255 return 0;
3256
3257 /*
3258 * Stop after the first non-trylock entry,
3259 * as non-trylock entries have added their
3260 * own direct dependencies already, so this
3261 * lock is connected to them indirectly:
3262 */
3263 if (!hlock->trylock)
3264 break;
3265 }
3266
3267 depth--;
3268 /*
3269 * End of lock-stack?
3270 */
3271 if (!depth)
3272 break;
3273 /*
3274 * Stop the search if we cross into another context:
3275 */
3276 if (curr->held_locks[depth].irq_context !=
3277 curr->held_locks[depth-1].irq_context)
3278 break;
3279 }
3280 return 1;
3281out_bug:
3282 if (!debug_locks_off_graph_unlock())
3283 return 0;
3284
3285 /*
3286 * Clearly we all shouldn't be here, but since we made it we
3287 * can reliable say we messed up our state. See the above two
3288 * gotos for reasons why we could possibly end up here.
3289 */
3290 WARN_ON(1);
3291
3292 return 0;
3293}
3294
3295struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
3296static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS);
3297static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
3298unsigned long nr_zapped_lock_chains;
3299unsigned int nr_free_chain_hlocks; /* Free chain_hlocks in buckets */
3300unsigned int nr_lost_chain_hlocks; /* Lost chain_hlocks */
3301unsigned int nr_large_chain_blocks; /* size > MAX_CHAIN_BUCKETS */
3302
3303/*
3304 * The first 2 chain_hlocks entries in the chain block in the bucket
3305 * list contains the following meta data:
3306 *
3307 * entry[0]:
3308 * Bit 15 - always set to 1 (it is not a class index)
3309 * Bits 0-14 - upper 15 bits of the next block index
3310 * entry[1] - lower 16 bits of next block index
3311 *
3312 * A next block index of all 1 bits means it is the end of the list.
3313 *
3314 * On the unsized bucket (bucket-0), the 3rd and 4th entries contain
3315 * the chain block size:
3316 *
3317 * entry[2] - upper 16 bits of the chain block size
3318 * entry[3] - lower 16 bits of the chain block size
3319 */
3320#define MAX_CHAIN_BUCKETS 16
3321#define CHAIN_BLK_FLAG (1U << 15)
3322#define CHAIN_BLK_LIST_END 0xFFFFU
3323
3324static int chain_block_buckets[MAX_CHAIN_BUCKETS];
3325
3326static inline int size_to_bucket(int size)
3327{
3328 if (size > MAX_CHAIN_BUCKETS)
3329 return 0;
3330
3331 return size - 1;
3332}
3333
3334/*
3335 * Iterate all the chain blocks in a bucket.
3336 */
3337#define for_each_chain_block(bucket, prev, curr) \
3338 for ((prev) = -1, (curr) = chain_block_buckets[bucket]; \
3339 (curr) >= 0; \
3340 (prev) = (curr), (curr) = chain_block_next(curr))
3341
3342/*
3343 * next block or -1
3344 */
3345static inline int chain_block_next(int offset)
3346{
3347 int next = chain_hlocks[offset];
3348
3349 WARN_ON_ONCE(!(next & CHAIN_BLK_FLAG));
3350
3351 if (next == CHAIN_BLK_LIST_END)
3352 return -1;
3353
3354 next &= ~CHAIN_BLK_FLAG;
3355 next <<= 16;
3356 next |= chain_hlocks[offset + 1];
3357
3358 return next;
3359}
3360
3361/*
3362 * bucket-0 only
3363 */
3364static inline int chain_block_size(int offset)
3365{
3366 return (chain_hlocks[offset + 2] << 16) | chain_hlocks[offset + 3];
3367}
3368
3369static inline void init_chain_block(int offset, int next, int bucket, int size)
3370{
3371 chain_hlocks[offset] = (next >> 16) | CHAIN_BLK_FLAG;
3372 chain_hlocks[offset + 1] = (u16)next;
3373
3374 if (size && !bucket) {
3375 chain_hlocks[offset + 2] = size >> 16;
3376 chain_hlocks[offset + 3] = (u16)size;
3377 }
3378}
3379
3380static inline void add_chain_block(int offset, int size)
3381{
3382 int bucket = size_to_bucket(size);
3383 int next = chain_block_buckets[bucket];
3384 int prev, curr;
3385
3386 if (unlikely(size < 2)) {
3387 /*
3388 * We can't store single entries on the freelist. Leak them.
3389 *
3390 * One possible way out would be to uniquely mark them, other
3391 * than with CHAIN_BLK_FLAG, such that we can recover them when
3392 * the block before it is re-added.
3393 */
3394 if (size)
3395 nr_lost_chain_hlocks++;
3396 return;
3397 }
3398
3399 nr_free_chain_hlocks += size;
3400 if (!bucket) {
3401 nr_large_chain_blocks++;
3402
3403 /*
3404 * Variable sized, sort large to small.
3405 */
3406 for_each_chain_block(0, prev, curr) {
3407 if (size >= chain_block_size(curr))
3408 break;
3409 }
3410 init_chain_block(offset, curr, 0, size);
3411 if (prev < 0)
3412 chain_block_buckets[0] = offset;
3413 else
3414 init_chain_block(prev, offset, 0, 0);
3415 return;
3416 }
3417 /*
3418 * Fixed size, add to head.
3419 */
3420 init_chain_block(offset, next, bucket, size);
3421 chain_block_buckets[bucket] = offset;
3422}
3423
3424/*
3425 * Only the first block in the list can be deleted.
3426 *
3427 * For the variable size bucket[0], the first block (the largest one) is
3428 * returned, broken up and put back into the pool. So if a chain block of
3429 * length > MAX_CHAIN_BUCKETS is ever used and zapped, it will just be
3430 * queued up after the primordial chain block and never be used until the
3431 * hlock entries in the primordial chain block is almost used up. That
3432 * causes fragmentation and reduce allocation efficiency. That can be
3433 * monitored by looking at the "large chain blocks" number in lockdep_stats.
3434 */
3435static inline void del_chain_block(int bucket, int size, int next)
3436{
3437 nr_free_chain_hlocks -= size;
3438 chain_block_buckets[bucket] = next;
3439
3440 if (!bucket)
3441 nr_large_chain_blocks--;
3442}
3443
3444static void init_chain_block_buckets(void)
3445{
3446 int i;
3447
3448 for (i = 0; i < MAX_CHAIN_BUCKETS; i++)
3449 chain_block_buckets[i] = -1;
3450
3451 add_chain_block(0, ARRAY_SIZE(chain_hlocks));
3452}
3453
3454/*
3455 * Return offset of a chain block of the right size or -1 if not found.
3456 *
3457 * Fairly simple worst-fit allocator with the addition of a number of size
3458 * specific free lists.
3459 */
3460static int alloc_chain_hlocks(int req)
3461{
3462 int bucket, curr, size;
3463
3464 /*
3465 * We rely on the MSB to act as an escape bit to denote freelist
3466 * pointers. Make sure this bit isn't set in 'normal' class_idx usage.
3467 */
3468 BUILD_BUG_ON((MAX_LOCKDEP_KEYS-1) & CHAIN_BLK_FLAG);
3469
3470 init_data_structures_once();
3471
3472 if (nr_free_chain_hlocks < req)
3473 return -1;
3474
3475 /*
3476 * We require a minimum of 2 (u16) entries to encode a freelist
3477 * 'pointer'.
3478 */
3479 req = max(req, 2);
3480 bucket = size_to_bucket(req);
3481 curr = chain_block_buckets[bucket];
3482
3483 if (bucket) {
3484 if (curr >= 0) {
3485 del_chain_block(bucket, req, chain_block_next(curr));
3486 return curr;
3487 }
3488 /* Try bucket 0 */
3489 curr = chain_block_buckets[0];
3490 }
3491
3492 /*
3493 * The variable sized freelist is sorted by size; the first entry is
3494 * the largest. Use it if it fits.
3495 */
3496 if (curr >= 0) {
3497 size = chain_block_size(curr);
3498 if (likely(size >= req)) {
3499 del_chain_block(0, size, chain_block_next(curr));
3500 if (size > req)
3501 add_chain_block(curr + req, size - req);
3502 return curr;
3503 }
3504 }
3505
3506 /*
3507 * Last resort, split a block in a larger sized bucket.
3508 */
3509 for (size = MAX_CHAIN_BUCKETS; size > req; size--) {
3510 bucket = size_to_bucket(size);
3511 curr = chain_block_buckets[bucket];
3512 if (curr < 0)
3513 continue;
3514
3515 del_chain_block(bucket, size, chain_block_next(curr));
3516 add_chain_block(curr + req, size - req);
3517 return curr;
3518 }
3519
3520 return -1;
3521}
3522
3523static inline void free_chain_hlocks(int base, int size)
3524{
3525 add_chain_block(base, max(size, 2));
3526}
3527
3528struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
3529{
3530 u16 chain_hlock = chain_hlocks[chain->base + i];
3531 unsigned int class_idx = chain_hlock_class_idx(chain_hlock);
3532
3533 return lock_classes + class_idx;
3534}
3535
3536/*
3537 * Returns the index of the first held_lock of the current chain
3538 */
3539static inline int get_first_held_lock(struct task_struct *curr,
3540 struct held_lock *hlock)
3541{
3542 int i;
3543 struct held_lock *hlock_curr;
3544
3545 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
3546 hlock_curr = curr->held_locks + i;
3547 if (hlock_curr->irq_context != hlock->irq_context)
3548 break;
3549
3550 }
3551
3552 return ++i;
3553}
3554
3555#ifdef CONFIG_DEBUG_LOCKDEP
3556/*
3557 * Returns the next chain_key iteration
3558 */
3559static u64 print_chain_key_iteration(u16 hlock_id, u64 chain_key)
3560{
3561 u64 new_chain_key = iterate_chain_key(chain_key, hlock_id);
3562
3563 printk(" hlock_id:%d -> chain_key:%016Lx",
3564 (unsigned int)hlock_id,
3565 (unsigned long long)new_chain_key);
3566 return new_chain_key;
3567}
3568
3569static void
3570print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
3571{
3572 struct held_lock *hlock;
3573 u64 chain_key = INITIAL_CHAIN_KEY;
3574 int depth = curr->lockdep_depth;
3575 int i = get_first_held_lock(curr, hlock_next);
3576
3577 printk("depth: %u (irq_context %u)\n", depth - i + 1,
3578 hlock_next->irq_context);
3579 for (; i < depth; i++) {
3580 hlock = curr->held_locks + i;
3581 chain_key = print_chain_key_iteration(hlock_id(hlock), chain_key);
3582
3583 print_lock(hlock);
3584 }
3585
3586 print_chain_key_iteration(hlock_id(hlock_next), chain_key);
3587 print_lock(hlock_next);
3588}
3589
3590static void print_chain_keys_chain(struct lock_chain *chain)
3591{
3592 int i;
3593 u64 chain_key = INITIAL_CHAIN_KEY;
3594 u16 hlock_id;
3595
3596 printk("depth: %u\n", chain->depth);
3597 for (i = 0; i < chain->depth; i++) {
3598 hlock_id = chain_hlocks[chain->base + i];
3599 chain_key = print_chain_key_iteration(hlock_id, chain_key);
3600
3601 print_lock_name(NULL, lock_classes + chain_hlock_class_idx(hlock_id));
3602 printk("\n");
3603 }
3604}
3605
3606static void print_collision(struct task_struct *curr,
3607 struct held_lock *hlock_next,
3608 struct lock_chain *chain)
3609{
3610 pr_warn("\n");
3611 pr_warn("============================\n");
3612 pr_warn("WARNING: chain_key collision\n");
3613 print_kernel_ident();
3614 pr_warn("----------------------------\n");
3615 pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
3616 pr_warn("Hash chain already cached but the contents don't match!\n");
3617
3618 pr_warn("Held locks:");
3619 print_chain_keys_held_locks(curr, hlock_next);
3620
3621 pr_warn("Locks in cached chain:");
3622 print_chain_keys_chain(chain);
3623
3624 pr_warn("\nstack backtrace:\n");
3625 dump_stack();
3626}
3627#endif
3628
3629/*
3630 * Checks whether the chain and the current held locks are consistent
3631 * in depth and also in content. If they are not it most likely means
3632 * that there was a collision during the calculation of the chain_key.
3633 * Returns: 0 not passed, 1 passed
3634 */
3635static int check_no_collision(struct task_struct *curr,
3636 struct held_lock *hlock,
3637 struct lock_chain *chain)
3638{
3639#ifdef CONFIG_DEBUG_LOCKDEP
3640 int i, j, id;
3641
3642 i = get_first_held_lock(curr, hlock);
3643
3644 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
3645 print_collision(curr, hlock, chain);
3646 return 0;
3647 }
3648
3649 for (j = 0; j < chain->depth - 1; j++, i++) {
3650 id = hlock_id(&curr->held_locks[i]);
3651
3652 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
3653 print_collision(curr, hlock, chain);
3654 return 0;
3655 }
3656 }
3657#endif
3658 return 1;
3659}
3660
3661/*
3662 * Given an index that is >= -1, return the index of the next lock chain.
3663 * Return -2 if there is no next lock chain.
3664 */
3665long lockdep_next_lockchain(long i)
3666{
3667 i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1);
3668 return i < ARRAY_SIZE(lock_chains) ? i : -2;
3669}
3670
3671unsigned long lock_chain_count(void)
3672{
3673 return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains));
3674}
3675
3676/* Must be called with the graph lock held. */
3677static struct lock_chain *alloc_lock_chain(void)
3678{
3679 int idx = find_first_zero_bit(lock_chains_in_use,
3680 ARRAY_SIZE(lock_chains));
3681
3682 if (unlikely(idx >= ARRAY_SIZE(lock_chains)))
3683 return NULL;
3684 __set_bit(idx, lock_chains_in_use);
3685 return lock_chains + idx;
3686}
3687
3688/*
3689 * Adds a dependency chain into chain hashtable. And must be called with
3690 * graph_lock held.
3691 *
3692 * Return 0 if fail, and graph_lock is released.
3693 * Return 1 if succeed, with graph_lock held.
3694 */
3695static inline int add_chain_cache(struct task_struct *curr,
3696 struct held_lock *hlock,
3697 u64 chain_key)
3698{
3699 struct hlist_head *hash_head = chainhashentry(chain_key);
3700 struct lock_chain *chain;
3701 int i, j;
3702
3703 /*
3704 * The caller must hold the graph lock, ensure we've got IRQs
3705 * disabled to make this an IRQ-safe lock.. for recursion reasons
3706 * lockdep won't complain about its own locking errors.
3707 */
3708 if (lockdep_assert_locked())
3709 return 0;
3710
3711 chain = alloc_lock_chain();
3712 if (!chain) {
3713 if (!debug_locks_off_graph_unlock())
3714 return 0;
3715
3716 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
3717 dump_stack();
3718 return 0;
3719 }
3720 chain->chain_key = chain_key;
3721 chain->irq_context = hlock->irq_context;
3722 i = get_first_held_lock(curr, hlock);
3723 chain->depth = curr->lockdep_depth + 1 - i;
3724
3725 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
3726 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
3727 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
3728
3729 j = alloc_chain_hlocks(chain->depth);
3730 if (j < 0) {
3731 if (!debug_locks_off_graph_unlock())
3732 return 0;
3733
3734 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
3735 dump_stack();
3736 return 0;
3737 }
3738
3739 chain->base = j;
3740 for (j = 0; j < chain->depth - 1; j++, i++) {
3741 int lock_id = hlock_id(curr->held_locks + i);
3742
3743 chain_hlocks[chain->base + j] = lock_id;
3744 }
3745 chain_hlocks[chain->base + j] = hlock_id(hlock);
3746 hlist_add_head_rcu(&chain->entry, hash_head);
3747 debug_atomic_inc(chain_lookup_misses);
3748 inc_chains(chain->irq_context);
3749
3750 return 1;
3751}
3752
3753/*
3754 * Look up a dependency chain. Must be called with either the graph lock or
3755 * the RCU read lock held.
3756 */
3757static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
3758{
3759 struct hlist_head *hash_head = chainhashentry(chain_key);
3760 struct lock_chain *chain;
3761
3762 hlist_for_each_entry_rcu(chain, hash_head, entry) {
3763 if (READ_ONCE(chain->chain_key) == chain_key) {
3764 debug_atomic_inc(chain_lookup_hits);
3765 return chain;
3766 }
3767 }
3768 return NULL;
3769}
3770
3771/*
3772 * If the key is not present yet in dependency chain cache then
3773 * add it and return 1 - in this case the new dependency chain is
3774 * validated. If the key is already hashed, return 0.
3775 * (On return with 1 graph_lock is held.)
3776 */
3777static inline int lookup_chain_cache_add(struct task_struct *curr,
3778 struct held_lock *hlock,
3779 u64 chain_key)
3780{
3781 struct lock_class *class = hlock_class(hlock);
3782 struct lock_chain *chain = lookup_chain_cache(chain_key);
3783
3784 if (chain) {
3785cache_hit:
3786 if (!check_no_collision(curr, hlock, chain))
3787 return 0;
3788
3789 if (very_verbose(class)) {
3790 printk("\nhash chain already cached, key: "
3791 "%016Lx tail class: [%px] %s\n",
3792 (unsigned long long)chain_key,
3793 class->key, class->name);
3794 }
3795
3796 return 0;
3797 }
3798
3799 if (very_verbose(class)) {
3800 printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
3801 (unsigned long long)chain_key, class->key, class->name);
3802 }
3803
3804 if (!graph_lock())
3805 return 0;
3806
3807 /*
3808 * We have to walk the chain again locked - to avoid duplicates:
3809 */
3810 chain = lookup_chain_cache(chain_key);
3811 if (chain) {
3812 graph_unlock();
3813 goto cache_hit;
3814 }
3815
3816 if (!add_chain_cache(curr, hlock, chain_key))
3817 return 0;
3818
3819 return 1;
3820}
3821
3822static int validate_chain(struct task_struct *curr,
3823 struct held_lock *hlock,
3824 int chain_head, u64 chain_key)
3825{
3826 /*
3827 * Trylock needs to maintain the stack of held locks, but it
3828 * does not add new dependencies, because trylock can be done
3829 * in any order.
3830 *
3831 * We look up the chain_key and do the O(N^2) check and update of
3832 * the dependencies only if this is a new dependency chain.
3833 * (If lookup_chain_cache_add() return with 1 it acquires
3834 * graph_lock for us)
3835 */
3836 if (!hlock->trylock && hlock->check &&
3837 lookup_chain_cache_add(curr, hlock, chain_key)) {
3838 /*
3839 * Check whether last held lock:
3840 *
3841 * - is irq-safe, if this lock is irq-unsafe
3842 * - is softirq-safe, if this lock is hardirq-unsafe
3843 *
3844 * And check whether the new lock's dependency graph
3845 * could lead back to the previous lock:
3846 *
3847 * - within the current held-lock stack
3848 * - across our accumulated lock dependency records
3849 *
3850 * any of these scenarios could lead to a deadlock.
3851 */
3852 /*
3853 * The simple case: does the current hold the same lock
3854 * already?
3855 */
3856 int ret = check_deadlock(curr, hlock);
3857
3858 if (!ret)
3859 return 0;
3860 /*
3861 * Add dependency only if this lock is not the head
3862 * of the chain, and if the new lock introduces no more
3863 * lock dependency (because we already hold a lock with the
3864 * same lock class) nor deadlock (because the nest_lock
3865 * serializes nesting locks), see the comments for
3866 * check_deadlock().
3867 */
3868 if (!chain_head && ret != 2) {
3869 if (!check_prevs_add(curr, hlock))
3870 return 0;
3871 }
3872
3873 graph_unlock();
3874 } else {
3875 /* after lookup_chain_cache_add(): */
3876 if (unlikely(!debug_locks))
3877 return 0;
3878 }
3879
3880 return 1;
3881}
3882#else
3883static inline int validate_chain(struct task_struct *curr,
3884 struct held_lock *hlock,
3885 int chain_head, u64 chain_key)
3886{
3887 return 1;
3888}
3889
3890static void init_chain_block_buckets(void) { }
3891#endif /* CONFIG_PROVE_LOCKING */
3892
3893/*
3894 * We are building curr_chain_key incrementally, so double-check
3895 * it from scratch, to make sure that it's done correctly:
3896 */
3897static void check_chain_key(struct task_struct *curr)
3898{
3899#ifdef CONFIG_DEBUG_LOCKDEP
3900 struct held_lock *hlock, *prev_hlock = NULL;
3901 unsigned int i;
3902 u64 chain_key = INITIAL_CHAIN_KEY;
3903
3904 for (i = 0; i < curr->lockdep_depth; i++) {
3905 hlock = curr->held_locks + i;
3906 if (chain_key != hlock->prev_chain_key) {
3907 debug_locks_off();
3908 /*
3909 * We got mighty confused, our chain keys don't match
3910 * with what we expect, someone trample on our task state?
3911 */
3912 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
3913 curr->lockdep_depth, i,
3914 (unsigned long long)chain_key,
3915 (unsigned long long)hlock->prev_chain_key);
3916 return;
3917 }
3918
3919 /*
3920 * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is
3921 * it registered lock class index?
3922 */
3923 if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use)))
3924 return;
3925
3926 if (prev_hlock && (prev_hlock->irq_context !=
3927 hlock->irq_context))
3928 chain_key = INITIAL_CHAIN_KEY;
3929 chain_key = iterate_chain_key(chain_key, hlock_id(hlock));
3930 prev_hlock = hlock;
3931 }
3932 if (chain_key != curr->curr_chain_key) {
3933 debug_locks_off();
3934 /*
3935 * More smoking hash instead of calculating it, damn see these
3936 * numbers float.. I bet that a pink elephant stepped on my memory.
3937 */
3938 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
3939 curr->lockdep_depth, i,
3940 (unsigned long long)chain_key,
3941 (unsigned long long)curr->curr_chain_key);
3942 }
3943#endif
3944}
3945
3946#ifdef CONFIG_PROVE_LOCKING
3947static int mark_lock(struct task_struct *curr, struct held_lock *this,
3948 enum lock_usage_bit new_bit);
3949
3950static void print_usage_bug_scenario(struct held_lock *lock)
3951{
3952 struct lock_class *class = hlock_class(lock);
3953
3954 printk(" Possible unsafe locking scenario:\n\n");
3955 printk(" CPU0\n");
3956 printk(" ----\n");
3957 printk(" lock(");
3958 __print_lock_name(lock, class);
3959 printk(KERN_CONT ");\n");
3960 printk(" <Interrupt>\n");
3961 printk(" lock(");
3962 __print_lock_name(lock, class);
3963 printk(KERN_CONT ");\n");
3964 printk("\n *** DEADLOCK ***\n\n");
3965}
3966
3967static void
3968print_usage_bug(struct task_struct *curr, struct held_lock *this,
3969 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
3970{
3971 if (!debug_locks_off() || debug_locks_silent)
3972 return;
3973
3974 pr_warn("\n");
3975 pr_warn("================================\n");
3976 pr_warn("WARNING: inconsistent lock state\n");
3977 print_kernel_ident();
3978 pr_warn("--------------------------------\n");
3979
3980 pr_warn("inconsistent {%s} -> {%s} usage.\n",
3981 usage_str[prev_bit], usage_str[new_bit]);
3982
3983 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
3984 curr->comm, task_pid_nr(curr),
3985 lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
3986 lockdep_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
3987 lockdep_hardirqs_enabled(),
3988 lockdep_softirqs_enabled(curr));
3989 print_lock(this);
3990
3991 pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
3992 print_lock_trace(hlock_class(this)->usage_traces[prev_bit], 1);
3993
3994 print_irqtrace_events(curr);
3995 pr_warn("\nother info that might help us debug this:\n");
3996 print_usage_bug_scenario(this);
3997
3998 lockdep_print_held_locks(curr);
3999
4000 pr_warn("\nstack backtrace:\n");
4001 dump_stack();
4002}
4003
4004/*
4005 * Print out an error if an invalid bit is set:
4006 */
4007static inline int
4008valid_state(struct task_struct *curr, struct held_lock *this,
4009 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
4010{
4011 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) {
4012 graph_unlock();
4013 print_usage_bug(curr, this, bad_bit, new_bit);
4014 return 0;
4015 }
4016 return 1;
4017}
4018
4019
4020/*
4021 * print irq inversion bug:
4022 */
4023static void
4024print_irq_inversion_bug(struct task_struct *curr,
4025 struct lock_list *root, struct lock_list *other,
4026 struct held_lock *this, int forwards,
4027 const char *irqclass)
4028{
4029 struct lock_list *entry = other;
4030 struct lock_list *middle = NULL;
4031 int depth;
4032
4033 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
4034 return;
4035
4036 pr_warn("\n");
4037 pr_warn("========================================================\n");
4038 pr_warn("WARNING: possible irq lock inversion dependency detected\n");
4039 print_kernel_ident();
4040 pr_warn("--------------------------------------------------------\n");
4041 pr_warn("%s/%d just changed the state of lock:\n",
4042 curr->comm, task_pid_nr(curr));
4043 print_lock(this);
4044 if (forwards)
4045 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
4046 else
4047 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
4048 print_lock_name(NULL, other->class);
4049 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
4050
4051 pr_warn("\nother info that might help us debug this:\n");
4052
4053 /* Find a middle lock (if one exists) */
4054 depth = get_lock_depth(other);
4055 do {
4056 if (depth == 0 && (entry != root)) {
4057 pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
4058 break;
4059 }
4060 middle = entry;
4061 entry = get_lock_parent(entry);
4062 depth--;
4063 } while (entry && entry != root && (depth >= 0));
4064 if (forwards)
4065 print_irq_lock_scenario(root, other,
4066 middle ? middle->class : root->class, other->class);
4067 else
4068 print_irq_lock_scenario(other, root,
4069 middle ? middle->class : other->class, root->class);
4070
4071 lockdep_print_held_locks(curr);
4072
4073 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
4074 root->trace = save_trace();
4075 if (!root->trace)
4076 return;
4077 print_shortest_lock_dependencies(other, root);
4078
4079 pr_warn("\nstack backtrace:\n");
4080 dump_stack();
4081}
4082
4083/*
4084 * Prove that in the forwards-direction subgraph starting at <this>
4085 * there is no lock matching <mask>:
4086 */
4087static int
4088check_usage_forwards(struct task_struct *curr, struct held_lock *this,
4089 enum lock_usage_bit bit)
4090{
4091 enum bfs_result ret;
4092 struct lock_list root;
4093 struct lock_list *target_entry;
4094 enum lock_usage_bit read_bit = bit + LOCK_USAGE_READ_MASK;
4095 unsigned usage_mask = lock_flag(bit) | lock_flag(read_bit);
4096
4097 bfs_init_root(&root, this);
4098 ret = find_usage_forwards(&root, usage_mask, &target_entry);
4099 if (bfs_error(ret)) {
4100 print_bfs_bug(ret);
4101 return 0;
4102 }
4103 if (ret == BFS_RNOMATCH)
4104 return 1;
4105
4106 /* Check whether write or read usage is the match */
4107 if (target_entry->class->usage_mask & lock_flag(bit)) {
4108 print_irq_inversion_bug(curr, &root, target_entry,
4109 this, 1, state_name(bit));
4110 } else {
4111 print_irq_inversion_bug(curr, &root, target_entry,
4112 this, 1, state_name(read_bit));
4113 }
4114
4115 return 0;
4116}
4117
4118/*
4119 * Prove that in the backwards-direction subgraph starting at <this>
4120 * there is no lock matching <mask>:
4121 */
4122static int
4123check_usage_backwards(struct task_struct *curr, struct held_lock *this,
4124 enum lock_usage_bit bit)
4125{
4126 enum bfs_result ret;
4127 struct lock_list root;
4128 struct lock_list *target_entry;
4129 enum lock_usage_bit read_bit = bit + LOCK_USAGE_READ_MASK;
4130 unsigned usage_mask = lock_flag(bit) | lock_flag(read_bit);
4131
4132 bfs_init_rootb(&root, this);
4133 ret = find_usage_backwards(&root, usage_mask, &target_entry);
4134 if (bfs_error(ret)) {
4135 print_bfs_bug(ret);
4136 return 0;
4137 }
4138 if (ret == BFS_RNOMATCH)
4139 return 1;
4140
4141 /* Check whether write or read usage is the match */
4142 if (target_entry->class->usage_mask & lock_flag(bit)) {
4143 print_irq_inversion_bug(curr, &root, target_entry,
4144 this, 0, state_name(bit));
4145 } else {
4146 print_irq_inversion_bug(curr, &root, target_entry,
4147 this, 0, state_name(read_bit));
4148 }
4149
4150 return 0;
4151}
4152
4153void print_irqtrace_events(struct task_struct *curr)
4154{
4155 const struct irqtrace_events *trace = &curr->irqtrace;
4156
4157 printk("irq event stamp: %u\n", trace->irq_events);
4158 printk("hardirqs last enabled at (%u): [<%px>] %pS\n",
4159 trace->hardirq_enable_event, (void *)trace->hardirq_enable_ip,
4160 (void *)trace->hardirq_enable_ip);
4161 printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
4162 trace->hardirq_disable_event, (void *)trace->hardirq_disable_ip,
4163 (void *)trace->hardirq_disable_ip);
4164 printk("softirqs last enabled at (%u): [<%px>] %pS\n",
4165 trace->softirq_enable_event, (void *)trace->softirq_enable_ip,
4166 (void *)trace->softirq_enable_ip);
4167 printk("softirqs last disabled at (%u): [<%px>] %pS\n",
4168 trace->softirq_disable_event, (void *)trace->softirq_disable_ip,
4169 (void *)trace->softirq_disable_ip);
4170}
4171
4172static int HARDIRQ_verbose(struct lock_class *class)
4173{
4174#if HARDIRQ_VERBOSE
4175 return class_filter(class);
4176#endif
4177 return 0;
4178}
4179
4180static int SOFTIRQ_verbose(struct lock_class *class)
4181{
4182#if SOFTIRQ_VERBOSE
4183 return class_filter(class);
4184#endif
4185 return 0;
4186}
4187
4188static int (*state_verbose_f[])(struct lock_class *class) = {
4189#define LOCKDEP_STATE(__STATE) \
4190 __STATE##_verbose,
4191#include "lockdep_states.h"
4192#undef LOCKDEP_STATE
4193};
4194
4195static inline int state_verbose(enum lock_usage_bit bit,
4196 struct lock_class *class)
4197{
4198 return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class);
4199}
4200
4201typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
4202 enum lock_usage_bit bit, const char *name);
4203
4204static int
4205mark_lock_irq(struct task_struct *curr, struct held_lock *this,
4206 enum lock_usage_bit new_bit)
4207{
4208 int excl_bit = exclusive_bit(new_bit);
4209 int read = new_bit & LOCK_USAGE_READ_MASK;
4210 int dir = new_bit & LOCK_USAGE_DIR_MASK;
4211
4212 /*
4213 * Validate that this particular lock does not have conflicting
4214 * usage states.
4215 */
4216 if (!valid_state(curr, this, new_bit, excl_bit))
4217 return 0;
4218
4219 /*
4220 * Check for read in write conflicts
4221 */
4222 if (!read && !valid_state(curr, this, new_bit,
4223 excl_bit + LOCK_USAGE_READ_MASK))
4224 return 0;
4225
4226
4227 /*
4228 * Validate that the lock dependencies don't have conflicting usage
4229 * states.
4230 */
4231 if (dir) {
4232 /*
4233 * mark ENABLED has to look backwards -- to ensure no dependee
4234 * has USED_IN state, which, again, would allow recursion deadlocks.
4235 */
4236 if (!check_usage_backwards(curr, this, excl_bit))
4237 return 0;
4238 } else {
4239 /*
4240 * mark USED_IN has to look forwards -- to ensure no dependency
4241 * has ENABLED state, which would allow recursion deadlocks.
4242 */
4243 if (!check_usage_forwards(curr, this, excl_bit))
4244 return 0;
4245 }
4246
4247 if (state_verbose(new_bit, hlock_class(this)))
4248 return 2;
4249
4250 return 1;
4251}
4252
4253/*
4254 * Mark all held locks with a usage bit:
4255 */
4256static int
4257mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit)
4258{
4259 struct held_lock *hlock;
4260 int i;
4261
4262 for (i = 0; i < curr->lockdep_depth; i++) {
4263 enum lock_usage_bit hlock_bit = base_bit;
4264 hlock = curr->held_locks + i;
4265
4266 if (hlock->read)
4267 hlock_bit += LOCK_USAGE_READ_MASK;
4268
4269 BUG_ON(hlock_bit >= LOCK_USAGE_STATES);
4270
4271 if (!hlock->check)
4272 continue;
4273
4274 if (!mark_lock(curr, hlock, hlock_bit))
4275 return 0;
4276 }
4277
4278 return 1;
4279}
4280
4281/*
4282 * Hardirqs will be enabled:
4283 */
4284static void __trace_hardirqs_on_caller(void)
4285{
4286 struct task_struct *curr = current;
4287
4288 /*
4289 * We are going to turn hardirqs on, so set the
4290 * usage bit for all held locks:
4291 */
4292 if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ))
4293 return;
4294 /*
4295 * If we have softirqs enabled, then set the usage
4296 * bit for all held locks. (disabled hardirqs prevented
4297 * this bit from being set before)
4298 */
4299 if (curr->softirqs_enabled)
4300 mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
4301}
4302
4303/**
4304 * lockdep_hardirqs_on_prepare - Prepare for enabling interrupts
4305 *
4306 * Invoked before a possible transition to RCU idle from exit to user or
4307 * guest mode. This ensures that all RCU operations are done before RCU
4308 * stops watching. After the RCU transition lockdep_hardirqs_on() has to be
4309 * invoked to set the final state.
4310 */
4311void lockdep_hardirqs_on_prepare(void)
4312{
4313 if (unlikely(!debug_locks))
4314 return;
4315
4316 /*
4317 * NMIs do not (and cannot) track lock dependencies, nothing to do.
4318 */
4319 if (unlikely(in_nmi()))
4320 return;
4321
4322 if (unlikely(this_cpu_read(lockdep_recursion)))
4323 return;
4324
4325 if (unlikely(lockdep_hardirqs_enabled())) {
4326 /*
4327 * Neither irq nor preemption are disabled here
4328 * so this is racy by nature but losing one hit
4329 * in a stat is not a big deal.
4330 */
4331 __debug_atomic_inc(redundant_hardirqs_on);
4332 return;
4333 }
4334
4335 /*
4336 * We're enabling irqs and according to our state above irqs weren't
4337 * already enabled, yet we find the hardware thinks they are in fact
4338 * enabled.. someone messed up their IRQ state tracing.
4339 */
4340 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4341 return;
4342
4343 /*
4344 * See the fine text that goes along with this variable definition.
4345 */
4346 if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled))
4347 return;
4348
4349 /*
4350 * Can't allow enabling interrupts while in an interrupt handler,
4351 * that's general bad form and such. Recursion, limited stack etc..
4352 */
4353 if (DEBUG_LOCKS_WARN_ON(lockdep_hardirq_context()))
4354 return;
4355
4356 current->hardirq_chain_key = current->curr_chain_key;
4357
4358 lockdep_recursion_inc();
4359 __trace_hardirqs_on_caller();
4360 lockdep_recursion_finish();
4361}
4362EXPORT_SYMBOL_GPL(lockdep_hardirqs_on_prepare);
4363
4364void noinstr lockdep_hardirqs_on(unsigned long ip)
4365{
4366 struct irqtrace_events *trace = ¤t->irqtrace;
4367
4368 if (unlikely(!debug_locks))
4369 return;
4370
4371 /*
4372 * NMIs can happen in the middle of local_irq_{en,dis}able() where the
4373 * tracking state and hardware state are out of sync.
4374 *
4375 * NMIs must save lockdep_hardirqs_enabled() to restore IRQ state from,
4376 * and not rely on hardware state like normal interrupts.
4377 */
4378 if (unlikely(in_nmi())) {
4379 if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
4380 return;
4381
4382 /*
4383 * Skip:
4384 * - recursion check, because NMI can hit lockdep;
4385 * - hardware state check, because above;
4386 * - chain_key check, see lockdep_hardirqs_on_prepare().
4387 */
4388 goto skip_checks;
4389 }
4390
4391 if (unlikely(this_cpu_read(lockdep_recursion)))
4392 return;
4393
4394 if (lockdep_hardirqs_enabled()) {
4395 /*
4396 * Neither irq nor preemption are disabled here
4397 * so this is racy by nature but losing one hit
4398 * in a stat is not a big deal.
4399 */
4400 __debug_atomic_inc(redundant_hardirqs_on);
4401 return;
4402 }
4403
4404 /*
4405 * We're enabling irqs and according to our state above irqs weren't
4406 * already enabled, yet we find the hardware thinks they are in fact
4407 * enabled.. someone messed up their IRQ state tracing.
4408 */
4409 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4410 return;
4411
4412 /*
4413 * Ensure the lock stack remained unchanged between
4414 * lockdep_hardirqs_on_prepare() and lockdep_hardirqs_on().
4415 */
4416 DEBUG_LOCKS_WARN_ON(current->hardirq_chain_key !=
4417 current->curr_chain_key);
4418
4419skip_checks:
4420 /* we'll do an OFF -> ON transition: */
4421 __this_cpu_write(hardirqs_enabled, 1);
4422 trace->hardirq_enable_ip = ip;
4423 trace->hardirq_enable_event = ++trace->irq_events;
4424 debug_atomic_inc(hardirqs_on_events);
4425}
4426EXPORT_SYMBOL_GPL(lockdep_hardirqs_on);
4427
4428/*
4429 * Hardirqs were disabled:
4430 */
4431void noinstr lockdep_hardirqs_off(unsigned long ip)
4432{
4433 if (unlikely(!debug_locks))
4434 return;
4435
4436 /*
4437 * Matching lockdep_hardirqs_on(), allow NMIs in the middle of lockdep;
4438 * they will restore the software state. This ensures the software
4439 * state is consistent inside NMIs as well.
4440 */
4441 if (in_nmi()) {
4442 if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
4443 return;
4444 } else if (__this_cpu_read(lockdep_recursion))
4445 return;
4446
4447 /*
4448 * So we're supposed to get called after you mask local IRQs, but for
4449 * some reason the hardware doesn't quite think you did a proper job.
4450 */
4451 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4452 return;
4453
4454 if (lockdep_hardirqs_enabled()) {
4455 struct irqtrace_events *trace = ¤t->irqtrace;
4456
4457 /*
4458 * We have done an ON -> OFF transition:
4459 */
4460 __this_cpu_write(hardirqs_enabled, 0);
4461 trace->hardirq_disable_ip = ip;
4462 trace->hardirq_disable_event = ++trace->irq_events;
4463 debug_atomic_inc(hardirqs_off_events);
4464 } else {
4465 debug_atomic_inc(redundant_hardirqs_off);
4466 }
4467}
4468EXPORT_SYMBOL_GPL(lockdep_hardirqs_off);
4469
4470/*
4471 * Softirqs will be enabled:
4472 */
4473void lockdep_softirqs_on(unsigned long ip)
4474{
4475 struct irqtrace_events *trace = ¤t->irqtrace;
4476
4477 if (unlikely(!lockdep_enabled()))
4478 return;
4479
4480 /*
4481 * We fancy IRQs being disabled here, see softirq.c, avoids
4482 * funny state and nesting things.
4483 */
4484 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4485 return;
4486
4487 if (current->softirqs_enabled) {
4488 debug_atomic_inc(redundant_softirqs_on);
4489 return;
4490 }
4491
4492 lockdep_recursion_inc();
4493 /*
4494 * We'll do an OFF -> ON transition:
4495 */
4496 current->softirqs_enabled = 1;
4497 trace->softirq_enable_ip = ip;
4498 trace->softirq_enable_event = ++trace->irq_events;
4499 debug_atomic_inc(softirqs_on_events);
4500 /*
4501 * We are going to turn softirqs on, so set the
4502 * usage bit for all held locks, if hardirqs are
4503 * enabled too:
4504 */
4505 if (lockdep_hardirqs_enabled())
4506 mark_held_locks(current, LOCK_ENABLED_SOFTIRQ);
4507 lockdep_recursion_finish();
4508}
4509
4510/*
4511 * Softirqs were disabled:
4512 */
4513void lockdep_softirqs_off(unsigned long ip)
4514{
4515 if (unlikely(!lockdep_enabled()))
4516 return;
4517
4518 /*
4519 * We fancy IRQs being disabled here, see softirq.c
4520 */
4521 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4522 return;
4523
4524 if (current->softirqs_enabled) {
4525 struct irqtrace_events *trace = ¤t->irqtrace;
4526
4527 /*
4528 * We have done an ON -> OFF transition:
4529 */
4530 current->softirqs_enabled = 0;
4531 trace->softirq_disable_ip = ip;
4532 trace->softirq_disable_event = ++trace->irq_events;
4533 debug_atomic_inc(softirqs_off_events);
4534 /*
4535 * Whoops, we wanted softirqs off, so why aren't they?
4536 */
4537 DEBUG_LOCKS_WARN_ON(!softirq_count());
4538 } else
4539 debug_atomic_inc(redundant_softirqs_off);
4540}
4541
4542static int
4543mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
4544{
4545 if (!check)
4546 goto lock_used;
4547
4548 /*
4549 * If non-trylock use in a hardirq or softirq context, then
4550 * mark the lock as used in these contexts:
4551 */
4552 if (!hlock->trylock) {
4553 if (hlock->read) {
4554 if (lockdep_hardirq_context())
4555 if (!mark_lock(curr, hlock,
4556 LOCK_USED_IN_HARDIRQ_READ))
4557 return 0;
4558 if (curr->softirq_context)
4559 if (!mark_lock(curr, hlock,
4560 LOCK_USED_IN_SOFTIRQ_READ))
4561 return 0;
4562 } else {
4563 if (lockdep_hardirq_context())
4564 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
4565 return 0;
4566 if (curr->softirq_context)
4567 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
4568 return 0;
4569 }
4570 }
4571
4572 /*
4573 * For lock_sync(), don't mark the ENABLED usage, since lock_sync()
4574 * creates no critical section and no extra dependency can be introduced
4575 * by interrupts
4576 */
4577 if (!hlock->hardirqs_off && !hlock->sync) {
4578 if (hlock->read) {
4579 if (!mark_lock(curr, hlock,
4580 LOCK_ENABLED_HARDIRQ_READ))
4581 return 0;
4582 if (curr->softirqs_enabled)
4583 if (!mark_lock(curr, hlock,
4584 LOCK_ENABLED_SOFTIRQ_READ))
4585 return 0;
4586 } else {
4587 if (!mark_lock(curr, hlock,
4588 LOCK_ENABLED_HARDIRQ))
4589 return 0;
4590 if (curr->softirqs_enabled)
4591 if (!mark_lock(curr, hlock,
4592 LOCK_ENABLED_SOFTIRQ))
4593 return 0;
4594 }
4595 }
4596
4597lock_used:
4598 /* mark it as used: */
4599 if (!mark_lock(curr, hlock, LOCK_USED))
4600 return 0;
4601
4602 return 1;
4603}
4604
4605static inline unsigned int task_irq_context(struct task_struct *task)
4606{
4607 return LOCK_CHAIN_HARDIRQ_CONTEXT * !!lockdep_hardirq_context() +
4608 LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context;
4609}
4610
4611static int separate_irq_context(struct task_struct *curr,
4612 struct held_lock *hlock)
4613{
4614 unsigned int depth = curr->lockdep_depth;
4615
4616 /*
4617 * Keep track of points where we cross into an interrupt context:
4618 */
4619 if (depth) {
4620 struct held_lock *prev_hlock;
4621
4622 prev_hlock = curr->held_locks + depth-1;
4623 /*
4624 * If we cross into another context, reset the
4625 * hash key (this also prevents the checking and the
4626 * adding of the dependency to 'prev'):
4627 */
4628 if (prev_hlock->irq_context != hlock->irq_context)
4629 return 1;
4630 }
4631 return 0;
4632}
4633
4634/*
4635 * Mark a lock with a usage bit, and validate the state transition:
4636 */
4637static int mark_lock(struct task_struct *curr, struct held_lock *this,
4638 enum lock_usage_bit new_bit)
4639{
4640 unsigned int new_mask, ret = 1;
4641
4642 if (new_bit >= LOCK_USAGE_STATES) {
4643 DEBUG_LOCKS_WARN_ON(1);
4644 return 0;
4645 }
4646
4647 if (new_bit == LOCK_USED && this->read)
4648 new_bit = LOCK_USED_READ;
4649
4650 new_mask = 1 << new_bit;
4651
4652 /*
4653 * If already set then do not dirty the cacheline,
4654 * nor do any checks:
4655 */
4656 if (likely(hlock_class(this)->usage_mask & new_mask))
4657 return 1;
4658
4659 if (!graph_lock())
4660 return 0;
4661 /*
4662 * Make sure we didn't race:
4663 */
4664 if (unlikely(hlock_class(this)->usage_mask & new_mask))
4665 goto unlock;
4666
4667 if (!hlock_class(this)->usage_mask)
4668 debug_atomic_dec(nr_unused_locks);
4669
4670 hlock_class(this)->usage_mask |= new_mask;
4671
4672 if (new_bit < LOCK_TRACE_STATES) {
4673 if (!(hlock_class(this)->usage_traces[new_bit] = save_trace()))
4674 return 0;
4675 }
4676
4677 if (new_bit < LOCK_USED) {
4678 ret = mark_lock_irq(curr, this, new_bit);
4679 if (!ret)
4680 return 0;
4681 }
4682
4683unlock:
4684 graph_unlock();
4685
4686 /*
4687 * We must printk outside of the graph_lock:
4688 */
4689 if (ret == 2) {
4690 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
4691 print_lock(this);
4692 print_irqtrace_events(curr);
4693 dump_stack();
4694 }
4695
4696 return ret;
4697}
4698
4699static inline short task_wait_context(struct task_struct *curr)
4700{
4701 /*
4702 * Set appropriate wait type for the context; for IRQs we have to take
4703 * into account force_irqthread as that is implied by PREEMPT_RT.
4704 */
4705 if (lockdep_hardirq_context()) {
4706 /*
4707 * Check if force_irqthreads will run us threaded.
4708 */
4709 if (curr->hardirq_threaded || curr->irq_config)
4710 return LD_WAIT_CONFIG;
4711
4712 return LD_WAIT_SPIN;
4713 } else if (curr->softirq_context) {
4714 /*
4715 * Softirqs are always threaded.
4716 */
4717 return LD_WAIT_CONFIG;
4718 }
4719
4720 return LD_WAIT_MAX;
4721}
4722
4723static int
4724print_lock_invalid_wait_context(struct task_struct *curr,
4725 struct held_lock *hlock)
4726{
4727 short curr_inner;
4728
4729 if (!debug_locks_off())
4730 return 0;
4731 if (debug_locks_silent)
4732 return 0;
4733
4734 pr_warn("\n");
4735 pr_warn("=============================\n");
4736 pr_warn("[ BUG: Invalid wait context ]\n");
4737 print_kernel_ident();
4738 pr_warn("-----------------------------\n");
4739
4740 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
4741 print_lock(hlock);
4742
4743 pr_warn("other info that might help us debug this:\n");
4744
4745 curr_inner = task_wait_context(curr);
4746 pr_warn("context-{%d:%d}\n", curr_inner, curr_inner);
4747
4748 lockdep_print_held_locks(curr);
4749
4750 pr_warn("stack backtrace:\n");
4751 dump_stack();
4752
4753 return 0;
4754}
4755
4756/*
4757 * Verify the wait_type context.
4758 *
4759 * This check validates we take locks in the right wait-type order; that is it
4760 * ensures that we do not take mutexes inside spinlocks and do not attempt to
4761 * acquire spinlocks inside raw_spinlocks and the sort.
4762 *
4763 * The entire thing is slightly more complex because of RCU, RCU is a lock that
4764 * can be taken from (pretty much) any context but also has constraints.
4765 * However when taken in a stricter environment the RCU lock does not loosen
4766 * the constraints.
4767 *
4768 * Therefore we must look for the strictest environment in the lock stack and
4769 * compare that to the lock we're trying to acquire.
4770 */
4771static int check_wait_context(struct task_struct *curr, struct held_lock *next)
4772{
4773 u8 next_inner = hlock_class(next)->wait_type_inner;
4774 u8 next_outer = hlock_class(next)->wait_type_outer;
4775 u8 curr_inner;
4776 int depth;
4777
4778 if (!next_inner || next->trylock)
4779 return 0;
4780
4781 if (!next_outer)
4782 next_outer = next_inner;
4783
4784 /*
4785 * Find start of current irq_context..
4786 */
4787 for (depth = curr->lockdep_depth - 1; depth >= 0; depth--) {
4788 struct held_lock *prev = curr->held_locks + depth;
4789 if (prev->irq_context != next->irq_context)
4790 break;
4791 }
4792 depth++;
4793
4794 curr_inner = task_wait_context(curr);
4795
4796 for (; depth < curr->lockdep_depth; depth++) {
4797 struct held_lock *prev = curr->held_locks + depth;
4798 struct lock_class *class = hlock_class(prev);
4799 u8 prev_inner = class->wait_type_inner;
4800
4801 if (prev_inner) {
4802 /*
4803 * We can have a bigger inner than a previous one
4804 * when outer is smaller than inner, as with RCU.
4805 *
4806 * Also due to trylocks.
4807 */
4808 curr_inner = min(curr_inner, prev_inner);
4809
4810 /*
4811 * Allow override for annotations -- this is typically
4812 * only valid/needed for code that only exists when
4813 * CONFIG_PREEMPT_RT=n.
4814 */
4815 if (unlikely(class->lock_type == LD_LOCK_WAIT_OVERRIDE))
4816 curr_inner = prev_inner;
4817 }
4818 }
4819
4820 if (next_outer > curr_inner)
4821 return print_lock_invalid_wait_context(curr, next);
4822
4823 return 0;
4824}
4825
4826#else /* CONFIG_PROVE_LOCKING */
4827
4828static inline int
4829mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
4830{
4831 return 1;
4832}
4833
4834static inline unsigned int task_irq_context(struct task_struct *task)
4835{
4836 return 0;
4837}
4838
4839static inline int separate_irq_context(struct task_struct *curr,
4840 struct held_lock *hlock)
4841{
4842 return 0;
4843}
4844
4845static inline int check_wait_context(struct task_struct *curr,
4846 struct held_lock *next)
4847{
4848 return 0;
4849}
4850
4851#endif /* CONFIG_PROVE_LOCKING */
4852
4853/*
4854 * Initialize a lock instance's lock-class mapping info:
4855 */
4856void lockdep_init_map_type(struct lockdep_map *lock, const char *name,
4857 struct lock_class_key *key, int subclass,
4858 u8 inner, u8 outer, u8 lock_type)
4859{
4860 int i;
4861
4862 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
4863 lock->class_cache[i] = NULL;
4864
4865#ifdef CONFIG_LOCK_STAT
4866 lock->cpu = raw_smp_processor_id();
4867#endif
4868
4869 /*
4870 * Can't be having no nameless bastards around this place!
4871 */
4872 if (DEBUG_LOCKS_WARN_ON(!name)) {
4873 lock->name = "NULL";
4874 return;
4875 }
4876
4877 lock->name = name;
4878
4879 lock->wait_type_outer = outer;
4880 lock->wait_type_inner = inner;
4881 lock->lock_type = lock_type;
4882
4883 /*
4884 * No key, no joy, we need to hash something.
4885 */
4886 if (DEBUG_LOCKS_WARN_ON(!key))
4887 return;
4888 /*
4889 * Sanity check, the lock-class key must either have been allocated
4890 * statically or must have been registered as a dynamic key.
4891 */
4892 if (!static_obj(key) && !is_dynamic_key(key)) {
4893 if (debug_locks)
4894 printk(KERN_ERR "BUG: key %px has not been registered!\n", key);
4895 DEBUG_LOCKS_WARN_ON(1);
4896 return;
4897 }
4898 lock->key = key;
4899
4900 if (unlikely(!debug_locks))
4901 return;
4902
4903 if (subclass) {
4904 unsigned long flags;
4905
4906 if (DEBUG_LOCKS_WARN_ON(!lockdep_enabled()))
4907 return;
4908
4909 raw_local_irq_save(flags);
4910 lockdep_recursion_inc();
4911 register_lock_class(lock, subclass, 1);
4912 lockdep_recursion_finish();
4913 raw_local_irq_restore(flags);
4914 }
4915}
4916EXPORT_SYMBOL_GPL(lockdep_init_map_type);
4917
4918struct lock_class_key __lockdep_no_validate__;
4919EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
4920
4921#ifdef CONFIG_PROVE_LOCKING
4922void lockdep_set_lock_cmp_fn(struct lockdep_map *lock, lock_cmp_fn cmp_fn,
4923 lock_print_fn print_fn)
4924{
4925 struct lock_class *class = lock->class_cache[0];
4926 unsigned long flags;
4927
4928 raw_local_irq_save(flags);
4929 lockdep_recursion_inc();
4930
4931 if (!class)
4932 class = register_lock_class(lock, 0, 0);
4933
4934 if (class) {
4935 WARN_ON(class->cmp_fn && class->cmp_fn != cmp_fn);
4936 WARN_ON(class->print_fn && class->print_fn != print_fn);
4937
4938 class->cmp_fn = cmp_fn;
4939 class->print_fn = print_fn;
4940 }
4941
4942 lockdep_recursion_finish();
4943 raw_local_irq_restore(flags);
4944}
4945EXPORT_SYMBOL_GPL(lockdep_set_lock_cmp_fn);
4946#endif
4947
4948static void
4949print_lock_nested_lock_not_held(struct task_struct *curr,
4950 struct held_lock *hlock)
4951{
4952 if (!debug_locks_off())
4953 return;
4954 if (debug_locks_silent)
4955 return;
4956
4957 pr_warn("\n");
4958 pr_warn("==================================\n");
4959 pr_warn("WARNING: Nested lock was not taken\n");
4960 print_kernel_ident();
4961 pr_warn("----------------------------------\n");
4962
4963 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
4964 print_lock(hlock);
4965
4966 pr_warn("\nbut this task is not holding:\n");
4967 pr_warn("%s\n", hlock->nest_lock->name);
4968
4969 pr_warn("\nstack backtrace:\n");
4970 dump_stack();
4971
4972 pr_warn("\nother info that might help us debug this:\n");
4973 lockdep_print_held_locks(curr);
4974
4975 pr_warn("\nstack backtrace:\n");
4976 dump_stack();
4977}
4978
4979static int __lock_is_held(const struct lockdep_map *lock, int read);
4980
4981/*
4982 * This gets called for every mutex_lock*()/spin_lock*() operation.
4983 * We maintain the dependency maps and validate the locking attempt:
4984 *
4985 * The callers must make sure that IRQs are disabled before calling it,
4986 * otherwise we could get an interrupt which would want to take locks,
4987 * which would end up in lockdep again.
4988 */
4989static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
4990 int trylock, int read, int check, int hardirqs_off,
4991 struct lockdep_map *nest_lock, unsigned long ip,
4992 int references, int pin_count, int sync)
4993{
4994 struct task_struct *curr = current;
4995 struct lock_class *class = NULL;
4996 struct held_lock *hlock;
4997 unsigned int depth;
4998 int chain_head = 0;
4999 int class_idx;
5000 u64 chain_key;
5001
5002 if (unlikely(!debug_locks))
5003 return 0;
5004
5005 if (!prove_locking || lock->key == &__lockdep_no_validate__)
5006 check = 0;
5007
5008 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
5009 class = lock->class_cache[subclass];
5010 /*
5011 * Not cached?
5012 */
5013 if (unlikely(!class)) {
5014 class = register_lock_class(lock, subclass, 0);
5015 if (!class)
5016 return 0;
5017 }
5018
5019 debug_class_ops_inc(class);
5020
5021 if (very_verbose(class)) {
5022 printk("\nacquire class [%px] %s", class->key, class->name);
5023 if (class->name_version > 1)
5024 printk(KERN_CONT "#%d", class->name_version);
5025 printk(KERN_CONT "\n");
5026 dump_stack();
5027 }
5028
5029 /*
5030 * Add the lock to the list of currently held locks.
5031 * (we dont increase the depth just yet, up until the
5032 * dependency checks are done)
5033 */
5034 depth = curr->lockdep_depth;
5035 /*
5036 * Ran out of static storage for our per-task lock stack again have we?
5037 */
5038 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
5039 return 0;
5040
5041 class_idx = class - lock_classes;
5042
5043 if (depth && !sync) {
5044 /* we're holding locks and the new held lock is not a sync */
5045 hlock = curr->held_locks + depth - 1;
5046 if (hlock->class_idx == class_idx && nest_lock) {
5047 if (!references)
5048 references++;
5049
5050 if (!hlock->references)
5051 hlock->references++;
5052
5053 hlock->references += references;
5054
5055 /* Overflow */
5056 if (DEBUG_LOCKS_WARN_ON(hlock->references < references))
5057 return 0;
5058
5059 return 2;
5060 }
5061 }
5062
5063 hlock = curr->held_locks + depth;
5064 /*
5065 * Plain impossible, we just registered it and checked it weren't no
5066 * NULL like.. I bet this mushroom I ate was good!
5067 */
5068 if (DEBUG_LOCKS_WARN_ON(!class))
5069 return 0;
5070 hlock->class_idx = class_idx;
5071 hlock->acquire_ip = ip;
5072 hlock->instance = lock;
5073 hlock->nest_lock = nest_lock;
5074 hlock->irq_context = task_irq_context(curr);
5075 hlock->trylock = trylock;
5076 hlock->read = read;
5077 hlock->check = check;
5078 hlock->sync = !!sync;
5079 hlock->hardirqs_off = !!hardirqs_off;
5080 hlock->references = references;
5081#ifdef CONFIG_LOCK_STAT
5082 hlock->waittime_stamp = 0;
5083 hlock->holdtime_stamp = lockstat_clock();
5084#endif
5085 hlock->pin_count = pin_count;
5086
5087 if (check_wait_context(curr, hlock))
5088 return 0;
5089
5090 /* Initialize the lock usage bit */
5091 if (!mark_usage(curr, hlock, check))
5092 return 0;
5093
5094 /*
5095 * Calculate the chain hash: it's the combined hash of all the
5096 * lock keys along the dependency chain. We save the hash value
5097 * at every step so that we can get the current hash easily
5098 * after unlock. The chain hash is then used to cache dependency
5099 * results.
5100 *
5101 * The 'key ID' is what is the most compact key value to drive
5102 * the hash, not class->key.
5103 */
5104 /*
5105 * Whoops, we did it again.. class_idx is invalid.
5106 */
5107 if (DEBUG_LOCKS_WARN_ON(!test_bit(class_idx, lock_classes_in_use)))
5108 return 0;
5109
5110 chain_key = curr->curr_chain_key;
5111 if (!depth) {
5112 /*
5113 * How can we have a chain hash when we ain't got no keys?!
5114 */
5115 if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY))
5116 return 0;
5117 chain_head = 1;
5118 }
5119
5120 hlock->prev_chain_key = chain_key;
5121 if (separate_irq_context(curr, hlock)) {
5122 chain_key = INITIAL_CHAIN_KEY;
5123 chain_head = 1;
5124 }
5125 chain_key = iterate_chain_key(chain_key, hlock_id(hlock));
5126
5127 if (nest_lock && !__lock_is_held(nest_lock, -1)) {
5128 print_lock_nested_lock_not_held(curr, hlock);
5129 return 0;
5130 }
5131
5132 if (!debug_locks_silent) {
5133 WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key);
5134 WARN_ON_ONCE(!hlock_class(hlock)->key);
5135 }
5136
5137 if (!validate_chain(curr, hlock, chain_head, chain_key))
5138 return 0;
5139
5140 /* For lock_sync(), we are done here since no actual critical section */
5141 if (hlock->sync)
5142 return 1;
5143
5144 curr->curr_chain_key = chain_key;
5145 curr->lockdep_depth++;
5146 check_chain_key(curr);
5147#ifdef CONFIG_DEBUG_LOCKDEP
5148 if (unlikely(!debug_locks))
5149 return 0;
5150#endif
5151 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
5152 debug_locks_off();
5153 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
5154 printk(KERN_DEBUG "depth: %i max: %lu!\n",
5155 curr->lockdep_depth, MAX_LOCK_DEPTH);
5156
5157 lockdep_print_held_locks(current);
5158 debug_show_all_locks();
5159 dump_stack();
5160
5161 return 0;
5162 }
5163
5164 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
5165 max_lockdep_depth = curr->lockdep_depth;
5166
5167 return 1;
5168}
5169
5170static void print_unlock_imbalance_bug(struct task_struct *curr,
5171 struct lockdep_map *lock,
5172 unsigned long ip)
5173{
5174 if (!debug_locks_off())
5175 return;
5176 if (debug_locks_silent)
5177 return;
5178
5179 pr_warn("\n");
5180 pr_warn("=====================================\n");
5181 pr_warn("WARNING: bad unlock balance detected!\n");
5182 print_kernel_ident();
5183 pr_warn("-------------------------------------\n");
5184 pr_warn("%s/%d is trying to release lock (",
5185 curr->comm, task_pid_nr(curr));
5186 print_lockdep_cache(lock);
5187 pr_cont(") at:\n");
5188 print_ip_sym(KERN_WARNING, ip);
5189 pr_warn("but there are no more locks to release!\n");
5190 pr_warn("\nother info that might help us debug this:\n");
5191 lockdep_print_held_locks(curr);
5192
5193 pr_warn("\nstack backtrace:\n");
5194 dump_stack();
5195}
5196
5197static noinstr int match_held_lock(const struct held_lock *hlock,
5198 const struct lockdep_map *lock)
5199{
5200 if (hlock->instance == lock)
5201 return 1;
5202
5203 if (hlock->references) {
5204 const struct lock_class *class = lock->class_cache[0];
5205
5206 if (!class)
5207 class = look_up_lock_class(lock, 0);
5208
5209 /*
5210 * If look_up_lock_class() failed to find a class, we're trying
5211 * to test if we hold a lock that has never yet been acquired.
5212 * Clearly if the lock hasn't been acquired _ever_, we're not
5213 * holding it either, so report failure.
5214 */
5215 if (!class)
5216 return 0;
5217
5218 /*
5219 * References, but not a lock we're actually ref-counting?
5220 * State got messed up, follow the sites that change ->references
5221 * and try to make sense of it.
5222 */
5223 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
5224 return 0;
5225
5226 if (hlock->class_idx == class - lock_classes)
5227 return 1;
5228 }
5229
5230 return 0;
5231}
5232
5233/* @depth must not be zero */
5234static struct held_lock *find_held_lock(struct task_struct *curr,
5235 struct lockdep_map *lock,
5236 unsigned int depth, int *idx)
5237{
5238 struct held_lock *ret, *hlock, *prev_hlock;
5239 int i;
5240
5241 i = depth - 1;
5242 hlock = curr->held_locks + i;
5243 ret = hlock;
5244 if (match_held_lock(hlock, lock))
5245 goto out;
5246
5247 ret = NULL;
5248 for (i--, prev_hlock = hlock--;
5249 i >= 0;
5250 i--, prev_hlock = hlock--) {
5251 /*
5252 * We must not cross into another context:
5253 */
5254 if (prev_hlock->irq_context != hlock->irq_context) {
5255 ret = NULL;
5256 break;
5257 }
5258 if (match_held_lock(hlock, lock)) {
5259 ret = hlock;
5260 break;
5261 }
5262 }
5263
5264out:
5265 *idx = i;
5266 return ret;
5267}
5268
5269static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
5270 int idx, unsigned int *merged)
5271{
5272 struct held_lock *hlock;
5273 int first_idx = idx;
5274
5275 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
5276 return 0;
5277
5278 for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
5279 switch (__lock_acquire(hlock->instance,
5280 hlock_class(hlock)->subclass,
5281 hlock->trylock,
5282 hlock->read, hlock->check,
5283 hlock->hardirqs_off,
5284 hlock->nest_lock, hlock->acquire_ip,
5285 hlock->references, hlock->pin_count, 0)) {
5286 case 0:
5287 return 1;
5288 case 1:
5289 break;
5290 case 2:
5291 *merged += (idx == first_idx);
5292 break;
5293 default:
5294 WARN_ON(1);
5295 return 0;
5296 }
5297 }
5298 return 0;
5299}
5300
5301static int
5302__lock_set_class(struct lockdep_map *lock, const char *name,
5303 struct lock_class_key *key, unsigned int subclass,
5304 unsigned long ip)
5305{
5306 struct task_struct *curr = current;
5307 unsigned int depth, merged = 0;
5308 struct held_lock *hlock;
5309 struct lock_class *class;
5310 int i;
5311
5312 if (unlikely(!debug_locks))
5313 return 0;
5314
5315 depth = curr->lockdep_depth;
5316 /*
5317 * This function is about (re)setting the class of a held lock,
5318 * yet we're not actually holding any locks. Naughty user!
5319 */
5320 if (DEBUG_LOCKS_WARN_ON(!depth))
5321 return 0;
5322
5323 hlock = find_held_lock(curr, lock, depth, &i);
5324 if (!hlock) {
5325 print_unlock_imbalance_bug(curr, lock, ip);
5326 return 0;
5327 }
5328
5329 lockdep_init_map_type(lock, name, key, 0,
5330 lock->wait_type_inner,
5331 lock->wait_type_outer,
5332 lock->lock_type);
5333 class = register_lock_class(lock, subclass, 0);
5334 hlock->class_idx = class - lock_classes;
5335
5336 curr->lockdep_depth = i;
5337 curr->curr_chain_key = hlock->prev_chain_key;
5338
5339 if (reacquire_held_locks(curr, depth, i, &merged))
5340 return 0;
5341
5342 /*
5343 * I took it apart and put it back together again, except now I have
5344 * these 'spare' parts.. where shall I put them.
5345 */
5346 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged))
5347 return 0;
5348 return 1;
5349}
5350
5351static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
5352{
5353 struct task_struct *curr = current;
5354 unsigned int depth, merged = 0;
5355 struct held_lock *hlock;
5356 int i;
5357
5358 if (unlikely(!debug_locks))
5359 return 0;
5360
5361 depth = curr->lockdep_depth;
5362 /*
5363 * This function is about (re)setting the class of a held lock,
5364 * yet we're not actually holding any locks. Naughty user!
5365 */
5366 if (DEBUG_LOCKS_WARN_ON(!depth))
5367 return 0;
5368
5369 hlock = find_held_lock(curr, lock, depth, &i);
5370 if (!hlock) {
5371 print_unlock_imbalance_bug(curr, lock, ip);
5372 return 0;
5373 }
5374
5375 curr->lockdep_depth = i;
5376 curr->curr_chain_key = hlock->prev_chain_key;
5377
5378 WARN(hlock->read, "downgrading a read lock");
5379 hlock->read = 1;
5380 hlock->acquire_ip = ip;
5381
5382 if (reacquire_held_locks(curr, depth, i, &merged))
5383 return 0;
5384
5385 /* Merging can't happen with unchanged classes.. */
5386 if (DEBUG_LOCKS_WARN_ON(merged))
5387 return 0;
5388
5389 /*
5390 * I took it apart and put it back together again, except now I have
5391 * these 'spare' parts.. where shall I put them.
5392 */
5393 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
5394 return 0;
5395
5396 return 1;
5397}
5398
5399/*
5400 * Remove the lock from the list of currently held locks - this gets
5401 * called on mutex_unlock()/spin_unlock*() (or on a failed
5402 * mutex_lock_interruptible()).
5403 */
5404static int
5405__lock_release(struct lockdep_map *lock, unsigned long ip)
5406{
5407 struct task_struct *curr = current;
5408 unsigned int depth, merged = 1;
5409 struct held_lock *hlock;
5410 int i;
5411
5412 if (unlikely(!debug_locks))
5413 return 0;
5414
5415 depth = curr->lockdep_depth;
5416 /*
5417 * So we're all set to release this lock.. wait what lock? We don't
5418 * own any locks, you've been drinking again?
5419 */
5420 if (depth <= 0) {
5421 print_unlock_imbalance_bug(curr, lock, ip);
5422 return 0;
5423 }
5424
5425 /*
5426 * Check whether the lock exists in the current stack
5427 * of held locks:
5428 */
5429 hlock = find_held_lock(curr, lock, depth, &i);
5430 if (!hlock) {
5431 print_unlock_imbalance_bug(curr, lock, ip);
5432 return 0;
5433 }
5434
5435 if (hlock->instance == lock)
5436 lock_release_holdtime(hlock);
5437
5438 WARN(hlock->pin_count, "releasing a pinned lock\n");
5439
5440 if (hlock->references) {
5441 hlock->references--;
5442 if (hlock->references) {
5443 /*
5444 * We had, and after removing one, still have
5445 * references, the current lock stack is still
5446 * valid. We're done!
5447 */
5448 return 1;
5449 }
5450 }
5451
5452 /*
5453 * We have the right lock to unlock, 'hlock' points to it.
5454 * Now we remove it from the stack, and add back the other
5455 * entries (if any), recalculating the hash along the way:
5456 */
5457
5458 curr->lockdep_depth = i;
5459 curr->curr_chain_key = hlock->prev_chain_key;
5460
5461 /*
5462 * The most likely case is when the unlock is on the innermost
5463 * lock. In this case, we are done!
5464 */
5465 if (i == depth-1)
5466 return 1;
5467
5468 if (reacquire_held_locks(curr, depth, i + 1, &merged))
5469 return 0;
5470
5471 /*
5472 * We had N bottles of beer on the wall, we drank one, but now
5473 * there's not N-1 bottles of beer left on the wall...
5474 * Pouring two of the bottles together is acceptable.
5475 */
5476 DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged);
5477
5478 /*
5479 * Since reacquire_held_locks() would have called check_chain_key()
5480 * indirectly via __lock_acquire(), we don't need to do it again
5481 * on return.
5482 */
5483 return 0;
5484}
5485
5486static __always_inline
5487int __lock_is_held(const struct lockdep_map *lock, int read)
5488{
5489 struct task_struct *curr = current;
5490 int i;
5491
5492 for (i = 0; i < curr->lockdep_depth; i++) {
5493 struct held_lock *hlock = curr->held_locks + i;
5494
5495 if (match_held_lock(hlock, lock)) {
5496 if (read == -1 || !!hlock->read == read)
5497 return LOCK_STATE_HELD;
5498
5499 return LOCK_STATE_NOT_HELD;
5500 }
5501 }
5502
5503 return LOCK_STATE_NOT_HELD;
5504}
5505
5506static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
5507{
5508 struct pin_cookie cookie = NIL_COOKIE;
5509 struct task_struct *curr = current;
5510 int i;
5511
5512 if (unlikely(!debug_locks))
5513 return cookie;
5514
5515 for (i = 0; i < curr->lockdep_depth; i++) {
5516 struct held_lock *hlock = curr->held_locks + i;
5517
5518 if (match_held_lock(hlock, lock)) {
5519 /*
5520 * Grab 16bits of randomness; this is sufficient to not
5521 * be guessable and still allows some pin nesting in
5522 * our u32 pin_count.
5523 */
5524 cookie.val = 1 + (sched_clock() & 0xffff);
5525 hlock->pin_count += cookie.val;
5526 return cookie;
5527 }
5528 }
5529
5530 WARN(1, "pinning an unheld lock\n");
5531 return cookie;
5532}
5533
5534static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5535{
5536 struct task_struct *curr = current;
5537 int i;
5538
5539 if (unlikely(!debug_locks))
5540 return;
5541
5542 for (i = 0; i < curr->lockdep_depth; i++) {
5543 struct held_lock *hlock = curr->held_locks + i;
5544
5545 if (match_held_lock(hlock, lock)) {
5546 hlock->pin_count += cookie.val;
5547 return;
5548 }
5549 }
5550
5551 WARN(1, "pinning an unheld lock\n");
5552}
5553
5554static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5555{
5556 struct task_struct *curr = current;
5557 int i;
5558
5559 if (unlikely(!debug_locks))
5560 return;
5561
5562 for (i = 0; i < curr->lockdep_depth; i++) {
5563 struct held_lock *hlock = curr->held_locks + i;
5564
5565 if (match_held_lock(hlock, lock)) {
5566 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
5567 return;
5568
5569 hlock->pin_count -= cookie.val;
5570
5571 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
5572 hlock->pin_count = 0;
5573
5574 return;
5575 }
5576 }
5577
5578 WARN(1, "unpinning an unheld lock\n");
5579}
5580
5581/*
5582 * Check whether we follow the irq-flags state precisely:
5583 */
5584static noinstr void check_flags(unsigned long flags)
5585{
5586#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP)
5587 if (!debug_locks)
5588 return;
5589
5590 /* Get the warning out.. */
5591 instrumentation_begin();
5592
5593 if (irqs_disabled_flags(flags)) {
5594 if (DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())) {
5595 printk("possible reason: unannotated irqs-off.\n");
5596 }
5597 } else {
5598 if (DEBUG_LOCKS_WARN_ON(!lockdep_hardirqs_enabled())) {
5599 printk("possible reason: unannotated irqs-on.\n");
5600 }
5601 }
5602
5603#ifndef CONFIG_PREEMPT_RT
5604 /*
5605 * We dont accurately track softirq state in e.g.
5606 * hardirq contexts (such as on 4KSTACKS), so only
5607 * check if not in hardirq contexts:
5608 */
5609 if (!hardirq_count()) {
5610 if (softirq_count()) {
5611 /* like the above, but with softirqs */
5612 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
5613 } else {
5614 /* lick the above, does it taste good? */
5615 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
5616 }
5617 }
5618#endif
5619
5620 if (!debug_locks)
5621 print_irqtrace_events(current);
5622
5623 instrumentation_end();
5624#endif
5625}
5626
5627void lock_set_class(struct lockdep_map *lock, const char *name,
5628 struct lock_class_key *key, unsigned int subclass,
5629 unsigned long ip)
5630{
5631 unsigned long flags;
5632
5633 if (unlikely(!lockdep_enabled()))
5634 return;
5635
5636 raw_local_irq_save(flags);
5637 lockdep_recursion_inc();
5638 check_flags(flags);
5639 if (__lock_set_class(lock, name, key, subclass, ip))
5640 check_chain_key(current);
5641 lockdep_recursion_finish();
5642 raw_local_irq_restore(flags);
5643}
5644EXPORT_SYMBOL_GPL(lock_set_class);
5645
5646void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
5647{
5648 unsigned long flags;
5649
5650 if (unlikely(!lockdep_enabled()))
5651 return;
5652
5653 raw_local_irq_save(flags);
5654 lockdep_recursion_inc();
5655 check_flags(flags);
5656 if (__lock_downgrade(lock, ip))
5657 check_chain_key(current);
5658 lockdep_recursion_finish();
5659 raw_local_irq_restore(flags);
5660}
5661EXPORT_SYMBOL_GPL(lock_downgrade);
5662
5663/* NMI context !!! */
5664static void verify_lock_unused(struct lockdep_map *lock, struct held_lock *hlock, int subclass)
5665{
5666#ifdef CONFIG_PROVE_LOCKING
5667 struct lock_class *class = look_up_lock_class(lock, subclass);
5668 unsigned long mask = LOCKF_USED;
5669
5670 /* if it doesn't have a class (yet), it certainly hasn't been used yet */
5671 if (!class)
5672 return;
5673
5674 /*
5675 * READ locks only conflict with USED, such that if we only ever use
5676 * READ locks, there is no deadlock possible -- RCU.
5677 */
5678 if (!hlock->read)
5679 mask |= LOCKF_USED_READ;
5680
5681 if (!(class->usage_mask & mask))
5682 return;
5683
5684 hlock->class_idx = class - lock_classes;
5685
5686 print_usage_bug(current, hlock, LOCK_USED, LOCK_USAGE_STATES);
5687#endif
5688}
5689
5690static bool lockdep_nmi(void)
5691{
5692 if (raw_cpu_read(lockdep_recursion))
5693 return false;
5694
5695 if (!in_nmi())
5696 return false;
5697
5698 return true;
5699}
5700
5701/*
5702 * read_lock() is recursive if:
5703 * 1. We force lockdep think this way in selftests or
5704 * 2. The implementation is not queued read/write lock or
5705 * 3. The locker is at an in_interrupt() context.
5706 */
5707bool read_lock_is_recursive(void)
5708{
5709 return force_read_lock_recursive ||
5710 !IS_ENABLED(CONFIG_QUEUED_RWLOCKS) ||
5711 in_interrupt();
5712}
5713EXPORT_SYMBOL_GPL(read_lock_is_recursive);
5714
5715/*
5716 * We are not always called with irqs disabled - do that here,
5717 * and also avoid lockdep recursion:
5718 */
5719void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
5720 int trylock, int read, int check,
5721 struct lockdep_map *nest_lock, unsigned long ip)
5722{
5723 unsigned long flags;
5724
5725 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
5726
5727 if (!debug_locks)
5728 return;
5729
5730 if (unlikely(!lockdep_enabled())) {
5731 /* XXX allow trylock from NMI ?!? */
5732 if (lockdep_nmi() && !trylock) {
5733 struct held_lock hlock;
5734
5735 hlock.acquire_ip = ip;
5736 hlock.instance = lock;
5737 hlock.nest_lock = nest_lock;
5738 hlock.irq_context = 2; // XXX
5739 hlock.trylock = trylock;
5740 hlock.read = read;
5741 hlock.check = check;
5742 hlock.hardirqs_off = true;
5743 hlock.references = 0;
5744
5745 verify_lock_unused(lock, &hlock, subclass);
5746 }
5747 return;
5748 }
5749
5750 raw_local_irq_save(flags);
5751 check_flags(flags);
5752
5753 lockdep_recursion_inc();
5754 __lock_acquire(lock, subclass, trylock, read, check,
5755 irqs_disabled_flags(flags), nest_lock, ip, 0, 0, 0);
5756 lockdep_recursion_finish();
5757 raw_local_irq_restore(flags);
5758}
5759EXPORT_SYMBOL_GPL(lock_acquire);
5760
5761void lock_release(struct lockdep_map *lock, unsigned long ip)
5762{
5763 unsigned long flags;
5764
5765 trace_lock_release(lock, ip);
5766
5767 if (unlikely(!lockdep_enabled()))
5768 return;
5769
5770 raw_local_irq_save(flags);
5771 check_flags(flags);
5772
5773 lockdep_recursion_inc();
5774 if (__lock_release(lock, ip))
5775 check_chain_key(current);
5776 lockdep_recursion_finish();
5777 raw_local_irq_restore(flags);
5778}
5779EXPORT_SYMBOL_GPL(lock_release);
5780
5781/*
5782 * lock_sync() - A special annotation for synchronize_{s,}rcu()-like API.
5783 *
5784 * No actual critical section is created by the APIs annotated with this: these
5785 * APIs are used to wait for one or multiple critical sections (on other CPUs
5786 * or threads), and it means that calling these APIs inside these critical
5787 * sections is potential deadlock.
5788 */
5789void lock_sync(struct lockdep_map *lock, unsigned subclass, int read,
5790 int check, struct lockdep_map *nest_lock, unsigned long ip)
5791{
5792 unsigned long flags;
5793
5794 if (unlikely(!lockdep_enabled()))
5795 return;
5796
5797 raw_local_irq_save(flags);
5798 check_flags(flags);
5799
5800 lockdep_recursion_inc();
5801 __lock_acquire(lock, subclass, 0, read, check,
5802 irqs_disabled_flags(flags), nest_lock, ip, 0, 0, 1);
5803 check_chain_key(current);
5804 lockdep_recursion_finish();
5805 raw_local_irq_restore(flags);
5806}
5807EXPORT_SYMBOL_GPL(lock_sync);
5808
5809noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
5810{
5811 unsigned long flags;
5812 int ret = LOCK_STATE_NOT_HELD;
5813
5814 /*
5815 * Avoid false negative lockdep_assert_held() and
5816 * lockdep_assert_not_held().
5817 */
5818 if (unlikely(!lockdep_enabled()))
5819 return LOCK_STATE_UNKNOWN;
5820
5821 raw_local_irq_save(flags);
5822 check_flags(flags);
5823
5824 lockdep_recursion_inc();
5825 ret = __lock_is_held(lock, read);
5826 lockdep_recursion_finish();
5827 raw_local_irq_restore(flags);
5828
5829 return ret;
5830}
5831EXPORT_SYMBOL_GPL(lock_is_held_type);
5832NOKPROBE_SYMBOL(lock_is_held_type);
5833
5834struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
5835{
5836 struct pin_cookie cookie = NIL_COOKIE;
5837 unsigned long flags;
5838
5839 if (unlikely(!lockdep_enabled()))
5840 return cookie;
5841
5842 raw_local_irq_save(flags);
5843 check_flags(flags);
5844
5845 lockdep_recursion_inc();
5846 cookie = __lock_pin_lock(lock);
5847 lockdep_recursion_finish();
5848 raw_local_irq_restore(flags);
5849
5850 return cookie;
5851}
5852EXPORT_SYMBOL_GPL(lock_pin_lock);
5853
5854void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5855{
5856 unsigned long flags;
5857
5858 if (unlikely(!lockdep_enabled()))
5859 return;
5860
5861 raw_local_irq_save(flags);
5862 check_flags(flags);
5863
5864 lockdep_recursion_inc();
5865 __lock_repin_lock(lock, cookie);
5866 lockdep_recursion_finish();
5867 raw_local_irq_restore(flags);
5868}
5869EXPORT_SYMBOL_GPL(lock_repin_lock);
5870
5871void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5872{
5873 unsigned long flags;
5874
5875 if (unlikely(!lockdep_enabled()))
5876 return;
5877
5878 raw_local_irq_save(flags);
5879 check_flags(flags);
5880
5881 lockdep_recursion_inc();
5882 __lock_unpin_lock(lock, cookie);
5883 lockdep_recursion_finish();
5884 raw_local_irq_restore(flags);
5885}
5886EXPORT_SYMBOL_GPL(lock_unpin_lock);
5887
5888#ifdef CONFIG_LOCK_STAT
5889static void print_lock_contention_bug(struct task_struct *curr,
5890 struct lockdep_map *lock,
5891 unsigned long ip)
5892{
5893 if (!debug_locks_off())
5894 return;
5895 if (debug_locks_silent)
5896 return;
5897
5898 pr_warn("\n");
5899 pr_warn("=================================\n");
5900 pr_warn("WARNING: bad contention detected!\n");
5901 print_kernel_ident();
5902 pr_warn("---------------------------------\n");
5903 pr_warn("%s/%d is trying to contend lock (",
5904 curr->comm, task_pid_nr(curr));
5905 print_lockdep_cache(lock);
5906 pr_cont(") at:\n");
5907 print_ip_sym(KERN_WARNING, ip);
5908 pr_warn("but there are no locks held!\n");
5909 pr_warn("\nother info that might help us debug this:\n");
5910 lockdep_print_held_locks(curr);
5911
5912 pr_warn("\nstack backtrace:\n");
5913 dump_stack();
5914}
5915
5916static void
5917__lock_contended(struct lockdep_map *lock, unsigned long ip)
5918{
5919 struct task_struct *curr = current;
5920 struct held_lock *hlock;
5921 struct lock_class_stats *stats;
5922 unsigned int depth;
5923 int i, contention_point, contending_point;
5924
5925 depth = curr->lockdep_depth;
5926 /*
5927 * Whee, we contended on this lock, except it seems we're not
5928 * actually trying to acquire anything much at all..
5929 */
5930 if (DEBUG_LOCKS_WARN_ON(!depth))
5931 return;
5932
5933 hlock = find_held_lock(curr, lock, depth, &i);
5934 if (!hlock) {
5935 print_lock_contention_bug(curr, lock, ip);
5936 return;
5937 }
5938
5939 if (hlock->instance != lock)
5940 return;
5941
5942 hlock->waittime_stamp = lockstat_clock();
5943
5944 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
5945 contending_point = lock_point(hlock_class(hlock)->contending_point,
5946 lock->ip);
5947
5948 stats = get_lock_stats(hlock_class(hlock));
5949 if (contention_point < LOCKSTAT_POINTS)
5950 stats->contention_point[contention_point]++;
5951 if (contending_point < LOCKSTAT_POINTS)
5952 stats->contending_point[contending_point]++;
5953 if (lock->cpu != smp_processor_id())
5954 stats->bounces[bounce_contended + !!hlock->read]++;
5955}
5956
5957static void
5958__lock_acquired(struct lockdep_map *lock, unsigned long ip)
5959{
5960 struct task_struct *curr = current;
5961 struct held_lock *hlock;
5962 struct lock_class_stats *stats;
5963 unsigned int depth;
5964 u64 now, waittime = 0;
5965 int i, cpu;
5966
5967 depth = curr->lockdep_depth;
5968 /*
5969 * Yay, we acquired ownership of this lock we didn't try to
5970 * acquire, how the heck did that happen?
5971 */
5972 if (DEBUG_LOCKS_WARN_ON(!depth))
5973 return;
5974
5975 hlock = find_held_lock(curr, lock, depth, &i);
5976 if (!hlock) {
5977 print_lock_contention_bug(curr, lock, _RET_IP_);
5978 return;
5979 }
5980
5981 if (hlock->instance != lock)
5982 return;
5983
5984 cpu = smp_processor_id();
5985 if (hlock->waittime_stamp) {
5986 now = lockstat_clock();
5987 waittime = now - hlock->waittime_stamp;
5988 hlock->holdtime_stamp = now;
5989 }
5990
5991 stats = get_lock_stats(hlock_class(hlock));
5992 if (waittime) {
5993 if (hlock->read)
5994 lock_time_inc(&stats->read_waittime, waittime);
5995 else
5996 lock_time_inc(&stats->write_waittime, waittime);
5997 }
5998 if (lock->cpu != cpu)
5999 stats->bounces[bounce_acquired + !!hlock->read]++;
6000
6001 lock->cpu = cpu;
6002 lock->ip = ip;
6003}
6004
6005void lock_contended(struct lockdep_map *lock, unsigned long ip)
6006{
6007 unsigned long flags;
6008
6009 trace_lock_contended(lock, ip);
6010
6011 if (unlikely(!lock_stat || !lockdep_enabled()))
6012 return;
6013
6014 raw_local_irq_save(flags);
6015 check_flags(flags);
6016 lockdep_recursion_inc();
6017 __lock_contended(lock, ip);
6018 lockdep_recursion_finish();
6019 raw_local_irq_restore(flags);
6020}
6021EXPORT_SYMBOL_GPL(lock_contended);
6022
6023void lock_acquired(struct lockdep_map *lock, unsigned long ip)
6024{
6025 unsigned long flags;
6026
6027 trace_lock_acquired(lock, ip);
6028
6029 if (unlikely(!lock_stat || !lockdep_enabled()))
6030 return;
6031
6032 raw_local_irq_save(flags);
6033 check_flags(flags);
6034 lockdep_recursion_inc();
6035 __lock_acquired(lock, ip);
6036 lockdep_recursion_finish();
6037 raw_local_irq_restore(flags);
6038}
6039EXPORT_SYMBOL_GPL(lock_acquired);
6040#endif
6041
6042/*
6043 * Used by the testsuite, sanitize the validator state
6044 * after a simulated failure:
6045 */
6046
6047void lockdep_reset(void)
6048{
6049 unsigned long flags;
6050 int i;
6051
6052 raw_local_irq_save(flags);
6053 lockdep_init_task(current);
6054 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
6055 nr_hardirq_chains = 0;
6056 nr_softirq_chains = 0;
6057 nr_process_chains = 0;
6058 debug_locks = 1;
6059 for (i = 0; i < CHAINHASH_SIZE; i++)
6060 INIT_HLIST_HEAD(chainhash_table + i);
6061 raw_local_irq_restore(flags);
6062}
6063
6064/* Remove a class from a lock chain. Must be called with the graph lock held. */
6065static void remove_class_from_lock_chain(struct pending_free *pf,
6066 struct lock_chain *chain,
6067 struct lock_class *class)
6068{
6069#ifdef CONFIG_PROVE_LOCKING
6070 int i;
6071
6072 for (i = chain->base; i < chain->base + chain->depth; i++) {
6073 if (chain_hlock_class_idx(chain_hlocks[i]) != class - lock_classes)
6074 continue;
6075 /*
6076 * Each lock class occurs at most once in a lock chain so once
6077 * we found a match we can break out of this loop.
6078 */
6079 goto free_lock_chain;
6080 }
6081 /* Since the chain has not been modified, return. */
6082 return;
6083
6084free_lock_chain:
6085 free_chain_hlocks(chain->base, chain->depth);
6086 /* Overwrite the chain key for concurrent RCU readers. */
6087 WRITE_ONCE(chain->chain_key, INITIAL_CHAIN_KEY);
6088 dec_chains(chain->irq_context);
6089
6090 /*
6091 * Note: calling hlist_del_rcu() from inside a
6092 * hlist_for_each_entry_rcu() loop is safe.
6093 */
6094 hlist_del_rcu(&chain->entry);
6095 __set_bit(chain - lock_chains, pf->lock_chains_being_freed);
6096 nr_zapped_lock_chains++;
6097#endif
6098}
6099
6100/* Must be called with the graph lock held. */
6101static void remove_class_from_lock_chains(struct pending_free *pf,
6102 struct lock_class *class)
6103{
6104 struct lock_chain *chain;
6105 struct hlist_head *head;
6106 int i;
6107
6108 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
6109 head = chainhash_table + i;
6110 hlist_for_each_entry_rcu(chain, head, entry) {
6111 remove_class_from_lock_chain(pf, chain, class);
6112 }
6113 }
6114}
6115
6116/*
6117 * Remove all references to a lock class. The caller must hold the graph lock.
6118 */
6119static void zap_class(struct pending_free *pf, struct lock_class *class)
6120{
6121 struct lock_list *entry;
6122 int i;
6123
6124 WARN_ON_ONCE(!class->key);
6125
6126 /*
6127 * Remove all dependencies this lock is
6128 * involved in:
6129 */
6130 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
6131 entry = list_entries + i;
6132 if (entry->class != class && entry->links_to != class)
6133 continue;
6134 __clear_bit(i, list_entries_in_use);
6135 nr_list_entries--;
6136 list_del_rcu(&entry->entry);
6137 }
6138 if (list_empty(&class->locks_after) &&
6139 list_empty(&class->locks_before)) {
6140 list_move_tail(&class->lock_entry, &pf->zapped);
6141 hlist_del_rcu(&class->hash_entry);
6142 WRITE_ONCE(class->key, NULL);
6143 WRITE_ONCE(class->name, NULL);
6144 nr_lock_classes--;
6145 __clear_bit(class - lock_classes, lock_classes_in_use);
6146 if (class - lock_classes == max_lock_class_idx)
6147 max_lock_class_idx--;
6148 } else {
6149 WARN_ONCE(true, "%s() failed for class %s\n", __func__,
6150 class->name);
6151 }
6152
6153 remove_class_from_lock_chains(pf, class);
6154 nr_zapped_classes++;
6155}
6156
6157static void reinit_class(struct lock_class *class)
6158{
6159 WARN_ON_ONCE(!class->lock_entry.next);
6160 WARN_ON_ONCE(!list_empty(&class->locks_after));
6161 WARN_ON_ONCE(!list_empty(&class->locks_before));
6162 memset_startat(class, 0, key);
6163 WARN_ON_ONCE(!class->lock_entry.next);
6164 WARN_ON_ONCE(!list_empty(&class->locks_after));
6165 WARN_ON_ONCE(!list_empty(&class->locks_before));
6166}
6167
6168static inline int within(const void *addr, void *start, unsigned long size)
6169{
6170 return addr >= start && addr < start + size;
6171}
6172
6173static bool inside_selftest(void)
6174{
6175 return current == lockdep_selftest_task_struct;
6176}
6177
6178/* The caller must hold the graph lock. */
6179static struct pending_free *get_pending_free(void)
6180{
6181 return delayed_free.pf + delayed_free.index;
6182}
6183
6184static void free_zapped_rcu(struct rcu_head *cb);
6185
6186/*
6187 * Schedule an RCU callback if no RCU callback is pending. Must be called with
6188 * the graph lock held.
6189 */
6190static void call_rcu_zapped(struct pending_free *pf)
6191{
6192 WARN_ON_ONCE(inside_selftest());
6193
6194 if (list_empty(&pf->zapped))
6195 return;
6196
6197 if (delayed_free.scheduled)
6198 return;
6199
6200 delayed_free.scheduled = true;
6201
6202 WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf);
6203 delayed_free.index ^= 1;
6204
6205 call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
6206}
6207
6208/* The caller must hold the graph lock. May be called from RCU context. */
6209static void __free_zapped_classes(struct pending_free *pf)
6210{
6211 struct lock_class *class;
6212
6213 check_data_structures();
6214
6215 list_for_each_entry(class, &pf->zapped, lock_entry)
6216 reinit_class(class);
6217
6218 list_splice_init(&pf->zapped, &free_lock_classes);
6219
6220#ifdef CONFIG_PROVE_LOCKING
6221 bitmap_andnot(lock_chains_in_use, lock_chains_in_use,
6222 pf->lock_chains_being_freed, ARRAY_SIZE(lock_chains));
6223 bitmap_clear(pf->lock_chains_being_freed, 0, ARRAY_SIZE(lock_chains));
6224#endif
6225}
6226
6227static void free_zapped_rcu(struct rcu_head *ch)
6228{
6229 struct pending_free *pf;
6230 unsigned long flags;
6231
6232 if (WARN_ON_ONCE(ch != &delayed_free.rcu_head))
6233 return;
6234
6235 raw_local_irq_save(flags);
6236 lockdep_lock();
6237
6238 /* closed head */
6239 pf = delayed_free.pf + (delayed_free.index ^ 1);
6240 __free_zapped_classes(pf);
6241 delayed_free.scheduled = false;
6242
6243 /*
6244 * If there's anything on the open list, close and start a new callback.
6245 */
6246 call_rcu_zapped(delayed_free.pf + delayed_free.index);
6247
6248 lockdep_unlock();
6249 raw_local_irq_restore(flags);
6250}
6251
6252/*
6253 * Remove all lock classes from the class hash table and from the
6254 * all_lock_classes list whose key or name is in the address range [start,
6255 * start + size). Move these lock classes to the zapped_classes list. Must
6256 * be called with the graph lock held.
6257 */
6258static void __lockdep_free_key_range(struct pending_free *pf, void *start,
6259 unsigned long size)
6260{
6261 struct lock_class *class;
6262 struct hlist_head *head;
6263 int i;
6264
6265 /* Unhash all classes that were created by a module. */
6266 for (i = 0; i < CLASSHASH_SIZE; i++) {
6267 head = classhash_table + i;
6268 hlist_for_each_entry_rcu(class, head, hash_entry) {
6269 if (!within(class->key, start, size) &&
6270 !within(class->name, start, size))
6271 continue;
6272 zap_class(pf, class);
6273 }
6274 }
6275}
6276
6277/*
6278 * Used in module.c to remove lock classes from memory that is going to be
6279 * freed; and possibly re-used by other modules.
6280 *
6281 * We will have had one synchronize_rcu() before getting here, so we're
6282 * guaranteed nobody will look up these exact classes -- they're properly dead
6283 * but still allocated.
6284 */
6285static void lockdep_free_key_range_reg(void *start, unsigned long size)
6286{
6287 struct pending_free *pf;
6288 unsigned long flags;
6289
6290 init_data_structures_once();
6291
6292 raw_local_irq_save(flags);
6293 lockdep_lock();
6294 pf = get_pending_free();
6295 __lockdep_free_key_range(pf, start, size);
6296 call_rcu_zapped(pf);
6297 lockdep_unlock();
6298 raw_local_irq_restore(flags);
6299
6300 /*
6301 * Wait for any possible iterators from look_up_lock_class() to pass
6302 * before continuing to free the memory they refer to.
6303 */
6304 synchronize_rcu();
6305}
6306
6307/*
6308 * Free all lockdep keys in the range [start, start+size). Does not sleep.
6309 * Ignores debug_locks. Must only be used by the lockdep selftests.
6310 */
6311static void lockdep_free_key_range_imm(void *start, unsigned long size)
6312{
6313 struct pending_free *pf = delayed_free.pf;
6314 unsigned long flags;
6315
6316 init_data_structures_once();
6317
6318 raw_local_irq_save(flags);
6319 lockdep_lock();
6320 __lockdep_free_key_range(pf, start, size);
6321 __free_zapped_classes(pf);
6322 lockdep_unlock();
6323 raw_local_irq_restore(flags);
6324}
6325
6326void lockdep_free_key_range(void *start, unsigned long size)
6327{
6328 init_data_structures_once();
6329
6330 if (inside_selftest())
6331 lockdep_free_key_range_imm(start, size);
6332 else
6333 lockdep_free_key_range_reg(start, size);
6334}
6335
6336/*
6337 * Check whether any element of the @lock->class_cache[] array refers to a
6338 * registered lock class. The caller must hold either the graph lock or the
6339 * RCU read lock.
6340 */
6341static bool lock_class_cache_is_registered(struct lockdep_map *lock)
6342{
6343 struct lock_class *class;
6344 struct hlist_head *head;
6345 int i, j;
6346
6347 for (i = 0; i < CLASSHASH_SIZE; i++) {
6348 head = classhash_table + i;
6349 hlist_for_each_entry_rcu(class, head, hash_entry) {
6350 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
6351 if (lock->class_cache[j] == class)
6352 return true;
6353 }
6354 }
6355 return false;
6356}
6357
6358/* The caller must hold the graph lock. Does not sleep. */
6359static void __lockdep_reset_lock(struct pending_free *pf,
6360 struct lockdep_map *lock)
6361{
6362 struct lock_class *class;
6363 int j;
6364
6365 /*
6366 * Remove all classes this lock might have:
6367 */
6368 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
6369 /*
6370 * If the class exists we look it up and zap it:
6371 */
6372 class = look_up_lock_class(lock, j);
6373 if (class)
6374 zap_class(pf, class);
6375 }
6376 /*
6377 * Debug check: in the end all mapped classes should
6378 * be gone.
6379 */
6380 if (WARN_ON_ONCE(lock_class_cache_is_registered(lock)))
6381 debug_locks_off();
6382}
6383
6384/*
6385 * Remove all information lockdep has about a lock if debug_locks == 1. Free
6386 * released data structures from RCU context.
6387 */
6388static void lockdep_reset_lock_reg(struct lockdep_map *lock)
6389{
6390 struct pending_free *pf;
6391 unsigned long flags;
6392 int locked;
6393
6394 raw_local_irq_save(flags);
6395 locked = graph_lock();
6396 if (!locked)
6397 goto out_irq;
6398
6399 pf = get_pending_free();
6400 __lockdep_reset_lock(pf, lock);
6401 call_rcu_zapped(pf);
6402
6403 graph_unlock();
6404out_irq:
6405 raw_local_irq_restore(flags);
6406}
6407
6408/*
6409 * Reset a lock. Does not sleep. Ignores debug_locks. Must only be used by the
6410 * lockdep selftests.
6411 */
6412static void lockdep_reset_lock_imm(struct lockdep_map *lock)
6413{
6414 struct pending_free *pf = delayed_free.pf;
6415 unsigned long flags;
6416
6417 raw_local_irq_save(flags);
6418 lockdep_lock();
6419 __lockdep_reset_lock(pf, lock);
6420 __free_zapped_classes(pf);
6421 lockdep_unlock();
6422 raw_local_irq_restore(flags);
6423}
6424
6425void lockdep_reset_lock(struct lockdep_map *lock)
6426{
6427 init_data_structures_once();
6428
6429 if (inside_selftest())
6430 lockdep_reset_lock_imm(lock);
6431 else
6432 lockdep_reset_lock_reg(lock);
6433}
6434
6435/*
6436 * Unregister a dynamically allocated key.
6437 *
6438 * Unlike lockdep_register_key(), a search is always done to find a matching
6439 * key irrespective of debug_locks to avoid potential invalid access to freed
6440 * memory in lock_class entry.
6441 */
6442void lockdep_unregister_key(struct lock_class_key *key)
6443{
6444 struct hlist_head *hash_head = keyhashentry(key);
6445 struct lock_class_key *k;
6446 struct pending_free *pf;
6447 unsigned long flags;
6448 bool found = false;
6449
6450 might_sleep();
6451
6452 if (WARN_ON_ONCE(static_obj(key)))
6453 return;
6454
6455 raw_local_irq_save(flags);
6456 lockdep_lock();
6457
6458 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
6459 if (k == key) {
6460 hlist_del_rcu(&k->hash_entry);
6461 found = true;
6462 break;
6463 }
6464 }
6465 WARN_ON_ONCE(!found && debug_locks);
6466 if (found) {
6467 pf = get_pending_free();
6468 __lockdep_free_key_range(pf, key, 1);
6469 call_rcu_zapped(pf);
6470 }
6471 lockdep_unlock();
6472 raw_local_irq_restore(flags);
6473
6474 /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */
6475 synchronize_rcu();
6476}
6477EXPORT_SYMBOL_GPL(lockdep_unregister_key);
6478
6479void __init lockdep_init(void)
6480{
6481 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
6482
6483 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
6484 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
6485 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
6486 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
6487 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
6488 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
6489 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
6490
6491 printk(" memory used by lock dependency info: %zu kB\n",
6492 (sizeof(lock_classes) +
6493 sizeof(lock_classes_in_use) +
6494 sizeof(classhash_table) +
6495 sizeof(list_entries) +
6496 sizeof(list_entries_in_use) +
6497 sizeof(chainhash_table) +
6498 sizeof(delayed_free)
6499#ifdef CONFIG_PROVE_LOCKING
6500 + sizeof(lock_cq)
6501 + sizeof(lock_chains)
6502 + sizeof(lock_chains_in_use)
6503 + sizeof(chain_hlocks)
6504#endif
6505 ) / 1024
6506 );
6507
6508#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
6509 printk(" memory used for stack traces: %zu kB\n",
6510 (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024
6511 );
6512#endif
6513
6514 printk(" per task-struct memory footprint: %zu bytes\n",
6515 sizeof(((struct task_struct *)NULL)->held_locks));
6516}
6517
6518static void
6519print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
6520 const void *mem_to, struct held_lock *hlock)
6521{
6522 if (!debug_locks_off())
6523 return;
6524 if (debug_locks_silent)
6525 return;
6526
6527 pr_warn("\n");
6528 pr_warn("=========================\n");
6529 pr_warn("WARNING: held lock freed!\n");
6530 print_kernel_ident();
6531 pr_warn("-------------------------\n");
6532 pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
6533 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
6534 print_lock(hlock);
6535 lockdep_print_held_locks(curr);
6536
6537 pr_warn("\nstack backtrace:\n");
6538 dump_stack();
6539}
6540
6541static inline int not_in_range(const void* mem_from, unsigned long mem_len,
6542 const void* lock_from, unsigned long lock_len)
6543{
6544 return lock_from + lock_len <= mem_from ||
6545 mem_from + mem_len <= lock_from;
6546}
6547
6548/*
6549 * Called when kernel memory is freed (or unmapped), or if a lock
6550 * is destroyed or reinitialized - this code checks whether there is
6551 * any held lock in the memory range of <from> to <to>:
6552 */
6553void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
6554{
6555 struct task_struct *curr = current;
6556 struct held_lock *hlock;
6557 unsigned long flags;
6558 int i;
6559
6560 if (unlikely(!debug_locks))
6561 return;
6562
6563 raw_local_irq_save(flags);
6564 for (i = 0; i < curr->lockdep_depth; i++) {
6565 hlock = curr->held_locks + i;
6566
6567 if (not_in_range(mem_from, mem_len, hlock->instance,
6568 sizeof(*hlock->instance)))
6569 continue;
6570
6571 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
6572 break;
6573 }
6574 raw_local_irq_restore(flags);
6575}
6576EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
6577
6578static void print_held_locks_bug(void)
6579{
6580 if (!debug_locks_off())
6581 return;
6582 if (debug_locks_silent)
6583 return;
6584
6585 pr_warn("\n");
6586 pr_warn("====================================\n");
6587 pr_warn("WARNING: %s/%d still has locks held!\n",
6588 current->comm, task_pid_nr(current));
6589 print_kernel_ident();
6590 pr_warn("------------------------------------\n");
6591 lockdep_print_held_locks(current);
6592 pr_warn("\nstack backtrace:\n");
6593 dump_stack();
6594}
6595
6596void debug_check_no_locks_held(void)
6597{
6598 if (unlikely(current->lockdep_depth > 0))
6599 print_held_locks_bug();
6600}
6601EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
6602
6603#ifdef __KERNEL__
6604void debug_show_all_locks(void)
6605{
6606 struct task_struct *g, *p;
6607
6608 if (unlikely(!debug_locks)) {
6609 pr_warn("INFO: lockdep is turned off.\n");
6610 return;
6611 }
6612 pr_warn("\nShowing all locks held in the system:\n");
6613
6614 rcu_read_lock();
6615 for_each_process_thread(g, p) {
6616 if (!p->lockdep_depth)
6617 continue;
6618 lockdep_print_held_locks(p);
6619 touch_nmi_watchdog();
6620 touch_all_softlockup_watchdogs();
6621 }
6622 rcu_read_unlock();
6623
6624 pr_warn("\n");
6625 pr_warn("=============================================\n\n");
6626}
6627EXPORT_SYMBOL_GPL(debug_show_all_locks);
6628#endif
6629
6630/*
6631 * Careful: only use this function if you are sure that
6632 * the task cannot run in parallel!
6633 */
6634void debug_show_held_locks(struct task_struct *task)
6635{
6636 if (unlikely(!debug_locks)) {
6637 printk("INFO: lockdep is turned off.\n");
6638 return;
6639 }
6640 lockdep_print_held_locks(task);
6641}
6642EXPORT_SYMBOL_GPL(debug_show_held_locks);
6643
6644asmlinkage __visible void lockdep_sys_exit(void)
6645{
6646 struct task_struct *curr = current;
6647
6648 if (unlikely(curr->lockdep_depth)) {
6649 if (!debug_locks_off())
6650 return;
6651 pr_warn("\n");
6652 pr_warn("================================================\n");
6653 pr_warn("WARNING: lock held when returning to user space!\n");
6654 print_kernel_ident();
6655 pr_warn("------------------------------------------------\n");
6656 pr_warn("%s/%d is leaving the kernel with locks still held!\n",
6657 curr->comm, curr->pid);
6658 lockdep_print_held_locks(curr);
6659 }
6660
6661 /*
6662 * The lock history for each syscall should be independent. So wipe the
6663 * slate clean on return to userspace.
6664 */
6665 lockdep_invariant_state(false);
6666}
6667
6668void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
6669{
6670 struct task_struct *curr = current;
6671 int dl = READ_ONCE(debug_locks);
6672 bool rcu = warn_rcu_enter();
6673
6674 /* Note: the following can be executed concurrently, so be careful. */
6675 pr_warn("\n");
6676 pr_warn("=============================\n");
6677 pr_warn("WARNING: suspicious RCU usage\n");
6678 print_kernel_ident();
6679 pr_warn("-----------------------------\n");
6680 pr_warn("%s:%d %s!\n", file, line, s);
6681 pr_warn("\nother info that might help us debug this:\n\n");
6682 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n%s",
6683 !rcu_lockdep_current_cpu_online()
6684 ? "RCU used illegally from offline CPU!\n"
6685 : "",
6686 rcu_scheduler_active, dl,
6687 dl ? "" : "Possible false positive due to lockdep disabling via debug_locks = 0\n");
6688
6689 /*
6690 * If a CPU is in the RCU-free window in idle (ie: in the section
6691 * between ct_idle_enter() and ct_idle_exit(), then RCU
6692 * considers that CPU to be in an "extended quiescent state",
6693 * which means that RCU will be completely ignoring that CPU.
6694 * Therefore, rcu_read_lock() and friends have absolutely no
6695 * effect on a CPU running in that state. In other words, even if
6696 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
6697 * delete data structures out from under it. RCU really has no
6698 * choice here: we need to keep an RCU-free window in idle where
6699 * the CPU may possibly enter into low power mode. This way we can
6700 * notice an extended quiescent state to other CPUs that started a grace
6701 * period. Otherwise we would delay any grace period as long as we run
6702 * in the idle task.
6703 *
6704 * So complain bitterly if someone does call rcu_read_lock(),
6705 * rcu_read_lock_bh() and so on from extended quiescent states.
6706 */
6707 if (!rcu_is_watching())
6708 pr_warn("RCU used illegally from extended quiescent state!\n");
6709
6710 lockdep_print_held_locks(curr);
6711 pr_warn("\nstack backtrace:\n");
6712 dump_stack();
6713 warn_rcu_exit(rcu);
6714}
6715EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);