Loading...
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
49#include <asm/sections.h>
50
51#include "lockdep_internals.h"
52
53#define CREATE_TRACE_POINTS
54#include <trace/events/lock.h>
55
56#ifdef CONFIG_PROVE_LOCKING
57int prove_locking = 1;
58module_param(prove_locking, int, 0644);
59#else
60#define prove_locking 0
61#endif
62
63#ifdef CONFIG_LOCK_STAT
64int lock_stat = 1;
65module_param(lock_stat, int, 0644);
66#else
67#define lock_stat 0
68#endif
69
70/*
71 * lockdep_lock: protects the lockdep graph, the hashes and the
72 * class/list/hash allocators.
73 *
74 * This is one of the rare exceptions where it's justified
75 * to use a raw spinlock - we really dont want the spinlock
76 * code to recurse back into the lockdep code...
77 */
78static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
79
80static int graph_lock(void)
81{
82 arch_spin_lock(&lockdep_lock);
83 /*
84 * Make sure that if another CPU detected a bug while
85 * walking the graph we dont change it (while the other
86 * CPU is busy printing out stuff with the graph lock
87 * dropped already)
88 */
89 if (!debug_locks) {
90 arch_spin_unlock(&lockdep_lock);
91 return 0;
92 }
93 /* prevent any recursions within lockdep from causing deadlocks */
94 current->lockdep_recursion++;
95 return 1;
96}
97
98static inline int graph_unlock(void)
99{
100 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
101 /*
102 * The lockdep graph lock isn't locked while we expect it to
103 * be, we're confused now, bye!
104 */
105 return DEBUG_LOCKS_WARN_ON(1);
106 }
107
108 current->lockdep_recursion--;
109 arch_spin_unlock(&lockdep_lock);
110 return 0;
111}
112
113/*
114 * Turn lock debugging off and return with 0 if it was off already,
115 * and also release the graph lock:
116 */
117static inline int debug_locks_off_graph_unlock(void)
118{
119 int ret = debug_locks_off();
120
121 arch_spin_unlock(&lockdep_lock);
122
123 return ret;
124}
125
126unsigned long nr_list_entries;
127static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
128
129/*
130 * All data structures here are protected by the global debug_lock.
131 *
132 * Mutex key structs only get allocated, once during bootup, and never
133 * get freed - this significantly simplifies the debugging code.
134 */
135unsigned long nr_lock_classes;
136static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
137
138static inline struct lock_class *hlock_class(struct held_lock *hlock)
139{
140 if (!hlock->class_idx) {
141 /*
142 * Someone passed in garbage, we give up.
143 */
144 DEBUG_LOCKS_WARN_ON(1);
145 return NULL;
146 }
147 return lock_classes + hlock->class_idx - 1;
148}
149
150#ifdef CONFIG_LOCK_STAT
151static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
152
153static inline u64 lockstat_clock(void)
154{
155 return local_clock();
156}
157
158static int lock_point(unsigned long points[], unsigned long ip)
159{
160 int i;
161
162 for (i = 0; i < LOCKSTAT_POINTS; i++) {
163 if (points[i] == 0) {
164 points[i] = ip;
165 break;
166 }
167 if (points[i] == ip)
168 break;
169 }
170
171 return i;
172}
173
174static void lock_time_inc(struct lock_time *lt, u64 time)
175{
176 if (time > lt->max)
177 lt->max = time;
178
179 if (time < lt->min || !lt->nr)
180 lt->min = time;
181
182 lt->total += time;
183 lt->nr++;
184}
185
186static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
187{
188 if (!src->nr)
189 return;
190
191 if (src->max > dst->max)
192 dst->max = src->max;
193
194 if (src->min < dst->min || !dst->nr)
195 dst->min = src->min;
196
197 dst->total += src->total;
198 dst->nr += src->nr;
199}
200
201struct lock_class_stats lock_stats(struct lock_class *class)
202{
203 struct lock_class_stats stats;
204 int cpu, i;
205
206 memset(&stats, 0, sizeof(struct lock_class_stats));
207 for_each_possible_cpu(cpu) {
208 struct lock_class_stats *pcs =
209 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
210
211 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
212 stats.contention_point[i] += pcs->contention_point[i];
213
214 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
215 stats.contending_point[i] += pcs->contending_point[i];
216
217 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
218 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
219
220 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
221 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
222
223 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
224 stats.bounces[i] += pcs->bounces[i];
225 }
226
227 return stats;
228}
229
230void clear_lock_stats(struct lock_class *class)
231{
232 int cpu;
233
234 for_each_possible_cpu(cpu) {
235 struct lock_class_stats *cpu_stats =
236 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
237
238 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
239 }
240 memset(class->contention_point, 0, sizeof(class->contention_point));
241 memset(class->contending_point, 0, sizeof(class->contending_point));
242}
243
244static struct lock_class_stats *get_lock_stats(struct lock_class *class)
245{
246 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
247}
248
249static void put_lock_stats(struct lock_class_stats *stats)
250{
251 put_cpu_var(cpu_lock_stats);
252}
253
254static void lock_release_holdtime(struct held_lock *hlock)
255{
256 struct lock_class_stats *stats;
257 u64 holdtime;
258
259 if (!lock_stat)
260 return;
261
262 holdtime = lockstat_clock() - hlock->holdtime_stamp;
263
264 stats = get_lock_stats(hlock_class(hlock));
265 if (hlock->read)
266 lock_time_inc(&stats->read_holdtime, holdtime);
267 else
268 lock_time_inc(&stats->write_holdtime, holdtime);
269 put_lock_stats(stats);
270}
271#else
272static inline void lock_release_holdtime(struct held_lock *hlock)
273{
274}
275#endif
276
277/*
278 * We keep a global list of all lock classes. The list only grows,
279 * never shrinks. The list is only accessed with the lockdep
280 * spinlock lock held.
281 */
282LIST_HEAD(all_lock_classes);
283
284/*
285 * The lockdep classes are in a hash-table as well, for fast lookup:
286 */
287#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
288#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
289#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
290#define classhashentry(key) (classhash_table + __classhashfn((key)))
291
292static struct hlist_head classhash_table[CLASSHASH_SIZE];
293
294/*
295 * We put the lock dependency chains into a hash-table as well, to cache
296 * their existence:
297 */
298#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
299#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
300#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
301#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
302
303static struct hlist_head chainhash_table[CHAINHASH_SIZE];
304
305/*
306 * The hash key of the lock dependency chains is a hash itself too:
307 * it's a hash of all locks taken up to that lock, including that lock.
308 * It's a 64-bit hash, because it's important for the keys to be
309 * unique.
310 */
311#define iterate_chain_key(key1, key2) \
312 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
313 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
314 (key2))
315
316void lockdep_off(void)
317{
318 current->lockdep_recursion++;
319}
320EXPORT_SYMBOL(lockdep_off);
321
322void lockdep_on(void)
323{
324 current->lockdep_recursion--;
325}
326EXPORT_SYMBOL(lockdep_on);
327
328/*
329 * Debugging switches:
330 */
331
332#define VERBOSE 0
333#define VERY_VERBOSE 0
334
335#if VERBOSE
336# define HARDIRQ_VERBOSE 1
337# define SOFTIRQ_VERBOSE 1
338# define RECLAIM_VERBOSE 1
339#else
340# define HARDIRQ_VERBOSE 0
341# define SOFTIRQ_VERBOSE 0
342# define RECLAIM_VERBOSE 0
343#endif
344
345#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
346/*
347 * Quick filtering for interesting events:
348 */
349static int class_filter(struct lock_class *class)
350{
351#if 0
352 /* Example */
353 if (class->name_version == 1 &&
354 !strcmp(class->name, "lockname"))
355 return 1;
356 if (class->name_version == 1 &&
357 !strcmp(class->name, "&struct->lockfield"))
358 return 1;
359#endif
360 /* Filter everything else. 1 would be to allow everything else */
361 return 0;
362}
363#endif
364
365static int verbose(struct lock_class *class)
366{
367#if VERBOSE
368 return class_filter(class);
369#endif
370 return 0;
371}
372
373/*
374 * Stack-trace: tightly packed array of stack backtrace
375 * addresses. Protected by the graph_lock.
376 */
377unsigned long nr_stack_trace_entries;
378static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
379
380static void print_lockdep_off(const char *bug_msg)
381{
382 printk(KERN_DEBUG "%s\n", bug_msg);
383 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
384#ifdef CONFIG_LOCK_STAT
385 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
386#endif
387}
388
389static int save_trace(struct stack_trace *trace)
390{
391 trace->nr_entries = 0;
392 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
393 trace->entries = stack_trace + nr_stack_trace_entries;
394
395 trace->skip = 3;
396
397 save_stack_trace(trace);
398
399 /*
400 * Some daft arches put -1 at the end to indicate its a full trace.
401 *
402 * <rant> this is buggy anyway, since it takes a whole extra entry so a
403 * complete trace that maxes out the entries provided will be reported
404 * as incomplete, friggin useless </rant>
405 */
406 if (trace->nr_entries != 0 &&
407 trace->entries[trace->nr_entries-1] == ULONG_MAX)
408 trace->nr_entries--;
409
410 trace->max_entries = trace->nr_entries;
411
412 nr_stack_trace_entries += trace->nr_entries;
413
414 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
415 if (!debug_locks_off_graph_unlock())
416 return 0;
417
418 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
419 dump_stack();
420
421 return 0;
422 }
423
424 return 1;
425}
426
427unsigned int nr_hardirq_chains;
428unsigned int nr_softirq_chains;
429unsigned int nr_process_chains;
430unsigned int max_lockdep_depth;
431
432#ifdef CONFIG_DEBUG_LOCKDEP
433/*
434 * Various lockdep statistics:
435 */
436DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
437#endif
438
439/*
440 * Locking printouts:
441 */
442
443#define __USAGE(__STATE) \
444 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
445 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
446 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
447 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
448
449static const char *usage_str[] =
450{
451#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
452#include "lockdep_states.h"
453#undef LOCKDEP_STATE
454 [LOCK_USED] = "INITIAL USE",
455};
456
457const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
458{
459 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
460}
461
462static inline unsigned long lock_flag(enum lock_usage_bit bit)
463{
464 return 1UL << bit;
465}
466
467static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
468{
469 char c = '.';
470
471 if (class->usage_mask & lock_flag(bit + 2))
472 c = '+';
473 if (class->usage_mask & lock_flag(bit)) {
474 c = '-';
475 if (class->usage_mask & lock_flag(bit + 2))
476 c = '?';
477 }
478
479 return c;
480}
481
482void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
483{
484 int i = 0;
485
486#define LOCKDEP_STATE(__STATE) \
487 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
488 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
489#include "lockdep_states.h"
490#undef LOCKDEP_STATE
491
492 usage[i] = '\0';
493}
494
495static void __print_lock_name(struct lock_class *class)
496{
497 char str[KSYM_NAME_LEN];
498 const char *name;
499
500 name = class->name;
501 if (!name) {
502 name = __get_key_name(class->key, str);
503 printk("%s", name);
504 } else {
505 printk("%s", name);
506 if (class->name_version > 1)
507 printk("#%d", class->name_version);
508 if (class->subclass)
509 printk("/%d", class->subclass);
510 }
511}
512
513static void print_lock_name(struct lock_class *class)
514{
515 char usage[LOCK_USAGE_CHARS];
516
517 get_usage_chars(class, usage);
518
519 printk(" (");
520 __print_lock_name(class);
521 printk("){%s}", usage);
522}
523
524static void print_lockdep_cache(struct lockdep_map *lock)
525{
526 const char *name;
527 char str[KSYM_NAME_LEN];
528
529 name = lock->name;
530 if (!name)
531 name = __get_key_name(lock->key->subkeys, str);
532
533 printk("%s", name);
534}
535
536static void print_lock(struct held_lock *hlock)
537{
538 /*
539 * We can be called locklessly through debug_show_all_locks() so be
540 * extra careful, the hlock might have been released and cleared.
541 */
542 unsigned int class_idx = hlock->class_idx;
543
544 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
545 barrier();
546
547 if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
548 printk("<RELEASED>\n");
549 return;
550 }
551
552 print_lock_name(lock_classes + class_idx - 1);
553 printk(", at: ");
554 print_ip_sym(hlock->acquire_ip);
555}
556
557static void lockdep_print_held_locks(struct task_struct *curr)
558{
559 int i, depth = curr->lockdep_depth;
560
561 if (!depth) {
562 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
563 return;
564 }
565 printk("%d lock%s held by %s/%d:\n",
566 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
567
568 for (i = 0; i < depth; i++) {
569 printk(" #%d: ", i);
570 print_lock(curr->held_locks + i);
571 }
572}
573
574static void print_kernel_ident(void)
575{
576 printk("%s %.*s %s\n", init_utsname()->release,
577 (int)strcspn(init_utsname()->version, " "),
578 init_utsname()->version,
579 print_tainted());
580}
581
582static int very_verbose(struct lock_class *class)
583{
584#if VERY_VERBOSE
585 return class_filter(class);
586#endif
587 return 0;
588}
589
590/*
591 * Is this the address of a static object:
592 */
593#ifdef __KERNEL__
594static int static_obj(void *obj)
595{
596 unsigned long start = (unsigned long) &_stext,
597 end = (unsigned long) &_end,
598 addr = (unsigned long) obj;
599
600 /*
601 * static variable?
602 */
603 if ((addr >= start) && (addr < end))
604 return 1;
605
606 if (arch_is_kernel_data(addr))
607 return 1;
608
609 /*
610 * in-kernel percpu var?
611 */
612 if (is_kernel_percpu_address(addr))
613 return 1;
614
615 /*
616 * module static or percpu var?
617 */
618 return is_module_address(addr) || is_module_percpu_address(addr);
619}
620#endif
621
622/*
623 * To make lock name printouts unique, we calculate a unique
624 * class->name_version generation counter:
625 */
626static int count_matching_names(struct lock_class *new_class)
627{
628 struct lock_class *class;
629 int count = 0;
630
631 if (!new_class->name)
632 return 0;
633
634 list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
635 if (new_class->key - new_class->subclass == class->key)
636 return class->name_version;
637 if (class->name && !strcmp(class->name, new_class->name))
638 count = max(count, class->name_version);
639 }
640
641 return count + 1;
642}
643
644/*
645 * Register a lock's class in the hash-table, if the class is not present
646 * yet. Otherwise we look it up. We cache the result in the lock object
647 * itself, so actual lookup of the hash should be once per lock object.
648 */
649static inline struct lock_class *
650look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
651{
652 struct lockdep_subclass_key *key;
653 struct hlist_head *hash_head;
654 struct lock_class *class;
655
656 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
657 debug_locks_off();
658 printk(KERN_ERR
659 "BUG: looking up invalid subclass: %u\n", subclass);
660 printk(KERN_ERR
661 "turning off the locking correctness validator.\n");
662 dump_stack();
663 return NULL;
664 }
665
666 /*
667 * Static locks do not have their class-keys yet - for them the key
668 * is the lock object itself:
669 */
670 if (unlikely(!lock->key))
671 lock->key = (void *)lock;
672
673 /*
674 * NOTE: the class-key must be unique. For dynamic locks, a static
675 * lock_class_key variable is passed in through the mutex_init()
676 * (or spin_lock_init()) call - which acts as the key. For static
677 * locks we use the lock object itself as the key.
678 */
679 BUILD_BUG_ON(sizeof(struct lock_class_key) >
680 sizeof(struct lockdep_map));
681
682 key = lock->key->subkeys + subclass;
683
684 hash_head = classhashentry(key);
685
686 /*
687 * We do an RCU walk of the hash, see lockdep_free_key_range().
688 */
689 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
690 return NULL;
691
692 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
693 if (class->key == key) {
694 /*
695 * Huh! same key, different name? Did someone trample
696 * on some memory? We're most confused.
697 */
698 WARN_ON_ONCE(class->name != lock->name);
699 return class;
700 }
701 }
702
703 return NULL;
704}
705
706/*
707 * Register a lock's class in the hash-table, if the class is not present
708 * yet. Otherwise we look it up. We cache the result in the lock object
709 * itself, so actual lookup of the hash should be once per lock object.
710 */
711static inline struct lock_class *
712register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
713{
714 struct lockdep_subclass_key *key;
715 struct hlist_head *hash_head;
716 struct lock_class *class;
717
718 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
719
720 class = look_up_lock_class(lock, subclass);
721 if (likely(class))
722 goto out_set_class_cache;
723
724 /*
725 * Debug-check: all keys must be persistent!
726 */
727 if (!static_obj(lock->key)) {
728 debug_locks_off();
729 printk("INFO: trying to register non-static key.\n");
730 printk("the code is fine but needs lockdep annotation.\n");
731 printk("turning off the locking correctness validator.\n");
732 dump_stack();
733
734 return NULL;
735 }
736
737 key = lock->key->subkeys + subclass;
738 hash_head = classhashentry(key);
739
740 if (!graph_lock()) {
741 return NULL;
742 }
743 /*
744 * We have to do the hash-walk again, to avoid races
745 * with another CPU:
746 */
747 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
748 if (class->key == key)
749 goto out_unlock_set;
750 }
751
752 /*
753 * Allocate a new key from the static array, and add it to
754 * the hash:
755 */
756 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
757 if (!debug_locks_off_graph_unlock()) {
758 return NULL;
759 }
760
761 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
762 dump_stack();
763 return NULL;
764 }
765 class = lock_classes + nr_lock_classes++;
766 debug_atomic_inc(nr_unused_locks);
767 class->key = key;
768 class->name = lock->name;
769 class->subclass = subclass;
770 INIT_LIST_HEAD(&class->lock_entry);
771 INIT_LIST_HEAD(&class->locks_before);
772 INIT_LIST_HEAD(&class->locks_after);
773 class->name_version = count_matching_names(class);
774 /*
775 * We use RCU's safe list-add method to make
776 * parallel walking of the hash-list safe:
777 */
778 hlist_add_head_rcu(&class->hash_entry, hash_head);
779 /*
780 * Add it to the global list of classes:
781 */
782 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
783
784 if (verbose(class)) {
785 graph_unlock();
786
787 printk("\nnew class %p: %s", class->key, class->name);
788 if (class->name_version > 1)
789 printk("#%d", class->name_version);
790 printk("\n");
791 dump_stack();
792
793 if (!graph_lock()) {
794 return NULL;
795 }
796 }
797out_unlock_set:
798 graph_unlock();
799
800out_set_class_cache:
801 if (!subclass || force)
802 lock->class_cache[0] = class;
803 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
804 lock->class_cache[subclass] = class;
805
806 /*
807 * Hash collision, did we smoke some? We found a class with a matching
808 * hash but the subclass -- which is hashed in -- didn't match.
809 */
810 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
811 return NULL;
812
813 return class;
814}
815
816#ifdef CONFIG_PROVE_LOCKING
817/*
818 * Allocate a lockdep entry. (assumes the graph_lock held, returns
819 * with NULL on failure)
820 */
821static struct lock_list *alloc_list_entry(void)
822{
823 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
824 if (!debug_locks_off_graph_unlock())
825 return NULL;
826
827 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
828 dump_stack();
829 return NULL;
830 }
831 return list_entries + nr_list_entries++;
832}
833
834/*
835 * Add a new dependency to the head of the list:
836 */
837static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
838 struct list_head *head, unsigned long ip,
839 int distance, struct stack_trace *trace)
840{
841 struct lock_list *entry;
842 /*
843 * Lock not present yet - get a new dependency struct and
844 * add it to the list:
845 */
846 entry = alloc_list_entry();
847 if (!entry)
848 return 0;
849
850 entry->class = this;
851 entry->distance = distance;
852 entry->trace = *trace;
853 /*
854 * Both allocation and removal are done under the graph lock; but
855 * iteration is under RCU-sched; see look_up_lock_class() and
856 * lockdep_free_key_range().
857 */
858 list_add_tail_rcu(&entry->entry, head);
859
860 return 1;
861}
862
863/*
864 * For good efficiency of modular, we use power of 2
865 */
866#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
867#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
868
869/*
870 * The circular_queue and helpers is used to implement the
871 * breadth-first search(BFS)algorithem, by which we can build
872 * the shortest path from the next lock to be acquired to the
873 * previous held lock if there is a circular between them.
874 */
875struct circular_queue {
876 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
877 unsigned int front, rear;
878};
879
880static struct circular_queue lock_cq;
881
882unsigned int max_bfs_queue_depth;
883
884static unsigned int lockdep_dependency_gen_id;
885
886static inline void __cq_init(struct circular_queue *cq)
887{
888 cq->front = cq->rear = 0;
889 lockdep_dependency_gen_id++;
890}
891
892static inline int __cq_empty(struct circular_queue *cq)
893{
894 return (cq->front == cq->rear);
895}
896
897static inline int __cq_full(struct circular_queue *cq)
898{
899 return ((cq->rear + 1) & CQ_MASK) == cq->front;
900}
901
902static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
903{
904 if (__cq_full(cq))
905 return -1;
906
907 cq->element[cq->rear] = elem;
908 cq->rear = (cq->rear + 1) & CQ_MASK;
909 return 0;
910}
911
912static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
913{
914 if (__cq_empty(cq))
915 return -1;
916
917 *elem = cq->element[cq->front];
918 cq->front = (cq->front + 1) & CQ_MASK;
919 return 0;
920}
921
922static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
923{
924 return (cq->rear - cq->front) & CQ_MASK;
925}
926
927static inline void mark_lock_accessed(struct lock_list *lock,
928 struct lock_list *parent)
929{
930 unsigned long nr;
931
932 nr = lock - list_entries;
933 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
934 lock->parent = parent;
935 lock->class->dep_gen_id = lockdep_dependency_gen_id;
936}
937
938static inline unsigned long lock_accessed(struct lock_list *lock)
939{
940 unsigned long nr;
941
942 nr = lock - list_entries;
943 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
944 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
945}
946
947static inline struct lock_list *get_lock_parent(struct lock_list *child)
948{
949 return child->parent;
950}
951
952static inline int get_lock_depth(struct lock_list *child)
953{
954 int depth = 0;
955 struct lock_list *parent;
956
957 while ((parent = get_lock_parent(child))) {
958 child = parent;
959 depth++;
960 }
961 return depth;
962}
963
964static int __bfs(struct lock_list *source_entry,
965 void *data,
966 int (*match)(struct lock_list *entry, void *data),
967 struct lock_list **target_entry,
968 int forward)
969{
970 struct lock_list *entry;
971 struct list_head *head;
972 struct circular_queue *cq = &lock_cq;
973 int ret = 1;
974
975 if (match(source_entry, data)) {
976 *target_entry = source_entry;
977 ret = 0;
978 goto exit;
979 }
980
981 if (forward)
982 head = &source_entry->class->locks_after;
983 else
984 head = &source_entry->class->locks_before;
985
986 if (list_empty(head))
987 goto exit;
988
989 __cq_init(cq);
990 __cq_enqueue(cq, (unsigned long)source_entry);
991
992 while (!__cq_empty(cq)) {
993 struct lock_list *lock;
994
995 __cq_dequeue(cq, (unsigned long *)&lock);
996
997 if (!lock->class) {
998 ret = -2;
999 goto exit;
1000 }
1001
1002 if (forward)
1003 head = &lock->class->locks_after;
1004 else
1005 head = &lock->class->locks_before;
1006
1007 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1008
1009 list_for_each_entry_rcu(entry, head, entry) {
1010 if (!lock_accessed(entry)) {
1011 unsigned int cq_depth;
1012 mark_lock_accessed(entry, lock);
1013 if (match(entry, data)) {
1014 *target_entry = entry;
1015 ret = 0;
1016 goto exit;
1017 }
1018
1019 if (__cq_enqueue(cq, (unsigned long)entry)) {
1020 ret = -1;
1021 goto exit;
1022 }
1023 cq_depth = __cq_get_elem_count(cq);
1024 if (max_bfs_queue_depth < cq_depth)
1025 max_bfs_queue_depth = cq_depth;
1026 }
1027 }
1028 }
1029exit:
1030 return ret;
1031}
1032
1033static inline int __bfs_forwards(struct lock_list *src_entry,
1034 void *data,
1035 int (*match)(struct lock_list *entry, void *data),
1036 struct lock_list **target_entry)
1037{
1038 return __bfs(src_entry, data, match, target_entry, 1);
1039
1040}
1041
1042static inline int __bfs_backwards(struct lock_list *src_entry,
1043 void *data,
1044 int (*match)(struct lock_list *entry, void *data),
1045 struct lock_list **target_entry)
1046{
1047 return __bfs(src_entry, data, match, target_entry, 0);
1048
1049}
1050
1051/*
1052 * Recursive, forwards-direction lock-dependency checking, used for
1053 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1054 * checking.
1055 */
1056
1057/*
1058 * Print a dependency chain entry (this is only done when a deadlock
1059 * has been detected):
1060 */
1061static noinline int
1062print_circular_bug_entry(struct lock_list *target, int depth)
1063{
1064 if (debug_locks_silent)
1065 return 0;
1066 printk("\n-> #%u", depth);
1067 print_lock_name(target->class);
1068 printk(":\n");
1069 print_stack_trace(&target->trace, 6);
1070
1071 return 0;
1072}
1073
1074static void
1075print_circular_lock_scenario(struct held_lock *src,
1076 struct held_lock *tgt,
1077 struct lock_list *prt)
1078{
1079 struct lock_class *source = hlock_class(src);
1080 struct lock_class *target = hlock_class(tgt);
1081 struct lock_class *parent = prt->class;
1082
1083 /*
1084 * A direct locking problem where unsafe_class lock is taken
1085 * directly by safe_class lock, then all we need to show
1086 * is the deadlock scenario, as it is obvious that the
1087 * unsafe lock is taken under the safe lock.
1088 *
1089 * But if there is a chain instead, where the safe lock takes
1090 * an intermediate lock (middle_class) where this lock is
1091 * not the same as the safe lock, then the lock chain is
1092 * used to describe the problem. Otherwise we would need
1093 * to show a different CPU case for each link in the chain
1094 * from the safe_class lock to the unsafe_class lock.
1095 */
1096 if (parent != source) {
1097 printk("Chain exists of:\n ");
1098 __print_lock_name(source);
1099 printk(" --> ");
1100 __print_lock_name(parent);
1101 printk(" --> ");
1102 __print_lock_name(target);
1103 printk("\n\n");
1104 }
1105
1106 printk(" Possible unsafe locking scenario:\n\n");
1107 printk(" CPU0 CPU1\n");
1108 printk(" ---- ----\n");
1109 printk(" lock(");
1110 __print_lock_name(target);
1111 printk(");\n");
1112 printk(" lock(");
1113 __print_lock_name(parent);
1114 printk(");\n");
1115 printk(" lock(");
1116 __print_lock_name(target);
1117 printk(");\n");
1118 printk(" lock(");
1119 __print_lock_name(source);
1120 printk(");\n");
1121 printk("\n *** DEADLOCK ***\n\n");
1122}
1123
1124/*
1125 * When a circular dependency is detected, print the
1126 * header first:
1127 */
1128static noinline int
1129print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1130 struct held_lock *check_src,
1131 struct held_lock *check_tgt)
1132{
1133 struct task_struct *curr = current;
1134
1135 if (debug_locks_silent)
1136 return 0;
1137
1138 printk("\n");
1139 printk("======================================================\n");
1140 printk("[ INFO: possible circular locking dependency detected ]\n");
1141 print_kernel_ident();
1142 printk("-------------------------------------------------------\n");
1143 printk("%s/%d is trying to acquire lock:\n",
1144 curr->comm, task_pid_nr(curr));
1145 print_lock(check_src);
1146 printk("\nbut task is already holding lock:\n");
1147 print_lock(check_tgt);
1148 printk("\nwhich lock already depends on the new lock.\n\n");
1149 printk("\nthe existing dependency chain (in reverse order) is:\n");
1150
1151 print_circular_bug_entry(entry, depth);
1152
1153 return 0;
1154}
1155
1156static inline int class_equal(struct lock_list *entry, void *data)
1157{
1158 return entry->class == data;
1159}
1160
1161static noinline int print_circular_bug(struct lock_list *this,
1162 struct lock_list *target,
1163 struct held_lock *check_src,
1164 struct held_lock *check_tgt)
1165{
1166 struct task_struct *curr = current;
1167 struct lock_list *parent;
1168 struct lock_list *first_parent;
1169 int depth;
1170
1171 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1172 return 0;
1173
1174 if (!save_trace(&this->trace))
1175 return 0;
1176
1177 depth = get_lock_depth(target);
1178
1179 print_circular_bug_header(target, depth, check_src, check_tgt);
1180
1181 parent = get_lock_parent(target);
1182 first_parent = parent;
1183
1184 while (parent) {
1185 print_circular_bug_entry(parent, --depth);
1186 parent = get_lock_parent(parent);
1187 }
1188
1189 printk("\nother info that might help us debug this:\n\n");
1190 print_circular_lock_scenario(check_src, check_tgt,
1191 first_parent);
1192
1193 lockdep_print_held_locks(curr);
1194
1195 printk("\nstack backtrace:\n");
1196 dump_stack();
1197
1198 return 0;
1199}
1200
1201static noinline int print_bfs_bug(int ret)
1202{
1203 if (!debug_locks_off_graph_unlock())
1204 return 0;
1205
1206 /*
1207 * Breadth-first-search failed, graph got corrupted?
1208 */
1209 WARN(1, "lockdep bfs error:%d\n", ret);
1210
1211 return 0;
1212}
1213
1214static int noop_count(struct lock_list *entry, void *data)
1215{
1216 (*(unsigned long *)data)++;
1217 return 0;
1218}
1219
1220static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1221{
1222 unsigned long count = 0;
1223 struct lock_list *uninitialized_var(target_entry);
1224
1225 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1226
1227 return count;
1228}
1229unsigned long lockdep_count_forward_deps(struct lock_class *class)
1230{
1231 unsigned long ret, flags;
1232 struct lock_list this;
1233
1234 this.parent = NULL;
1235 this.class = class;
1236
1237 local_irq_save(flags);
1238 arch_spin_lock(&lockdep_lock);
1239 ret = __lockdep_count_forward_deps(&this);
1240 arch_spin_unlock(&lockdep_lock);
1241 local_irq_restore(flags);
1242
1243 return ret;
1244}
1245
1246static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1247{
1248 unsigned long count = 0;
1249 struct lock_list *uninitialized_var(target_entry);
1250
1251 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1252
1253 return count;
1254}
1255
1256unsigned long lockdep_count_backward_deps(struct lock_class *class)
1257{
1258 unsigned long ret, flags;
1259 struct lock_list this;
1260
1261 this.parent = NULL;
1262 this.class = class;
1263
1264 local_irq_save(flags);
1265 arch_spin_lock(&lockdep_lock);
1266 ret = __lockdep_count_backward_deps(&this);
1267 arch_spin_unlock(&lockdep_lock);
1268 local_irq_restore(flags);
1269
1270 return ret;
1271}
1272
1273/*
1274 * Prove that the dependency graph starting at <entry> can not
1275 * lead to <target>. Print an error and return 0 if it does.
1276 */
1277static noinline int
1278check_noncircular(struct lock_list *root, struct lock_class *target,
1279 struct lock_list **target_entry)
1280{
1281 int result;
1282
1283 debug_atomic_inc(nr_cyclic_checks);
1284
1285 result = __bfs_forwards(root, target, class_equal, target_entry);
1286
1287 return result;
1288}
1289
1290#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1291/*
1292 * Forwards and backwards subgraph searching, for the purposes of
1293 * proving that two subgraphs can be connected by a new dependency
1294 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1295 */
1296
1297static inline int usage_match(struct lock_list *entry, void *bit)
1298{
1299 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1300}
1301
1302
1303
1304/*
1305 * Find a node in the forwards-direction dependency sub-graph starting
1306 * at @root->class that matches @bit.
1307 *
1308 * Return 0 if such a node exists in the subgraph, and put that node
1309 * into *@target_entry.
1310 *
1311 * Return 1 otherwise and keep *@target_entry unchanged.
1312 * Return <0 on error.
1313 */
1314static int
1315find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1316 struct lock_list **target_entry)
1317{
1318 int result;
1319
1320 debug_atomic_inc(nr_find_usage_forwards_checks);
1321
1322 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1323
1324 return result;
1325}
1326
1327/*
1328 * Find a node in the backwards-direction dependency sub-graph starting
1329 * at @root->class that matches @bit.
1330 *
1331 * Return 0 if such a node exists in the subgraph, and put that node
1332 * into *@target_entry.
1333 *
1334 * Return 1 otherwise and keep *@target_entry unchanged.
1335 * Return <0 on error.
1336 */
1337static int
1338find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1339 struct lock_list **target_entry)
1340{
1341 int result;
1342
1343 debug_atomic_inc(nr_find_usage_backwards_checks);
1344
1345 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1346
1347 return result;
1348}
1349
1350static void print_lock_class_header(struct lock_class *class, int depth)
1351{
1352 int bit;
1353
1354 printk("%*s->", depth, "");
1355 print_lock_name(class);
1356 printk(" ops: %lu", class->ops);
1357 printk(" {\n");
1358
1359 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1360 if (class->usage_mask & (1 << bit)) {
1361 int len = depth;
1362
1363 len += printk("%*s %s", depth, "", usage_str[bit]);
1364 len += printk(" at:\n");
1365 print_stack_trace(class->usage_traces + bit, len);
1366 }
1367 }
1368 printk("%*s }\n", depth, "");
1369
1370 printk("%*s ... key at: ",depth,"");
1371 print_ip_sym((unsigned long)class->key);
1372}
1373
1374/*
1375 * printk the shortest lock dependencies from @start to @end in reverse order:
1376 */
1377static void __used
1378print_shortest_lock_dependencies(struct lock_list *leaf,
1379 struct lock_list *root)
1380{
1381 struct lock_list *entry = leaf;
1382 int depth;
1383
1384 /*compute depth from generated tree by BFS*/
1385 depth = get_lock_depth(leaf);
1386
1387 do {
1388 print_lock_class_header(entry->class, depth);
1389 printk("%*s ... acquired at:\n", depth, "");
1390 print_stack_trace(&entry->trace, 2);
1391 printk("\n");
1392
1393 if (depth == 0 && (entry != root)) {
1394 printk("lockdep:%s bad path found in chain graph\n", __func__);
1395 break;
1396 }
1397
1398 entry = get_lock_parent(entry);
1399 depth--;
1400 } while (entry && (depth >= 0));
1401
1402 return;
1403}
1404
1405static void
1406print_irq_lock_scenario(struct lock_list *safe_entry,
1407 struct lock_list *unsafe_entry,
1408 struct lock_class *prev_class,
1409 struct lock_class *next_class)
1410{
1411 struct lock_class *safe_class = safe_entry->class;
1412 struct lock_class *unsafe_class = unsafe_entry->class;
1413 struct lock_class *middle_class = prev_class;
1414
1415 if (middle_class == safe_class)
1416 middle_class = next_class;
1417
1418 /*
1419 * A direct locking problem where unsafe_class lock is taken
1420 * directly by safe_class lock, then all we need to show
1421 * is the deadlock scenario, as it is obvious that the
1422 * unsafe lock is taken under the safe lock.
1423 *
1424 * But if there is a chain instead, where the safe lock takes
1425 * an intermediate lock (middle_class) where this lock is
1426 * not the same as the safe lock, then the lock chain is
1427 * used to describe the problem. Otherwise we would need
1428 * to show a different CPU case for each link in the chain
1429 * from the safe_class lock to the unsafe_class lock.
1430 */
1431 if (middle_class != unsafe_class) {
1432 printk("Chain exists of:\n ");
1433 __print_lock_name(safe_class);
1434 printk(" --> ");
1435 __print_lock_name(middle_class);
1436 printk(" --> ");
1437 __print_lock_name(unsafe_class);
1438 printk("\n\n");
1439 }
1440
1441 printk(" Possible interrupt unsafe locking scenario:\n\n");
1442 printk(" CPU0 CPU1\n");
1443 printk(" ---- ----\n");
1444 printk(" lock(");
1445 __print_lock_name(unsafe_class);
1446 printk(");\n");
1447 printk(" local_irq_disable();\n");
1448 printk(" lock(");
1449 __print_lock_name(safe_class);
1450 printk(");\n");
1451 printk(" lock(");
1452 __print_lock_name(middle_class);
1453 printk(");\n");
1454 printk(" <Interrupt>\n");
1455 printk(" lock(");
1456 __print_lock_name(safe_class);
1457 printk(");\n");
1458 printk("\n *** DEADLOCK ***\n\n");
1459}
1460
1461static int
1462print_bad_irq_dependency(struct task_struct *curr,
1463 struct lock_list *prev_root,
1464 struct lock_list *next_root,
1465 struct lock_list *backwards_entry,
1466 struct lock_list *forwards_entry,
1467 struct held_lock *prev,
1468 struct held_lock *next,
1469 enum lock_usage_bit bit1,
1470 enum lock_usage_bit bit2,
1471 const char *irqclass)
1472{
1473 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1474 return 0;
1475
1476 printk("\n");
1477 printk("======================================================\n");
1478 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1479 irqclass, irqclass);
1480 print_kernel_ident();
1481 printk("------------------------------------------------------\n");
1482 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1483 curr->comm, task_pid_nr(curr),
1484 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1485 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1486 curr->hardirqs_enabled,
1487 curr->softirqs_enabled);
1488 print_lock(next);
1489
1490 printk("\nand this task is already holding:\n");
1491 print_lock(prev);
1492 printk("which would create a new lock dependency:\n");
1493 print_lock_name(hlock_class(prev));
1494 printk(" ->");
1495 print_lock_name(hlock_class(next));
1496 printk("\n");
1497
1498 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1499 irqclass);
1500 print_lock_name(backwards_entry->class);
1501 printk("\n... which became %s-irq-safe at:\n", irqclass);
1502
1503 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1504
1505 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1506 print_lock_name(forwards_entry->class);
1507 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1508 printk("...");
1509
1510 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1511
1512 printk("\nother info that might help us debug this:\n\n");
1513 print_irq_lock_scenario(backwards_entry, forwards_entry,
1514 hlock_class(prev), hlock_class(next));
1515
1516 lockdep_print_held_locks(curr);
1517
1518 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1519 printk(" and the holding lock:\n");
1520 if (!save_trace(&prev_root->trace))
1521 return 0;
1522 print_shortest_lock_dependencies(backwards_entry, prev_root);
1523
1524 printk("\nthe dependencies between the lock to be acquired");
1525 printk(" and %s-irq-unsafe lock:\n", irqclass);
1526 if (!save_trace(&next_root->trace))
1527 return 0;
1528 print_shortest_lock_dependencies(forwards_entry, next_root);
1529
1530 printk("\nstack backtrace:\n");
1531 dump_stack();
1532
1533 return 0;
1534}
1535
1536static int
1537check_usage(struct task_struct *curr, struct held_lock *prev,
1538 struct held_lock *next, enum lock_usage_bit bit_backwards,
1539 enum lock_usage_bit bit_forwards, const char *irqclass)
1540{
1541 int ret;
1542 struct lock_list this, that;
1543 struct lock_list *uninitialized_var(target_entry);
1544 struct lock_list *uninitialized_var(target_entry1);
1545
1546 this.parent = NULL;
1547
1548 this.class = hlock_class(prev);
1549 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1550 if (ret < 0)
1551 return print_bfs_bug(ret);
1552 if (ret == 1)
1553 return ret;
1554
1555 that.parent = NULL;
1556 that.class = hlock_class(next);
1557 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1558 if (ret < 0)
1559 return print_bfs_bug(ret);
1560 if (ret == 1)
1561 return ret;
1562
1563 return print_bad_irq_dependency(curr, &this, &that,
1564 target_entry, target_entry1,
1565 prev, next,
1566 bit_backwards, bit_forwards, irqclass);
1567}
1568
1569static const char *state_names[] = {
1570#define LOCKDEP_STATE(__STATE) \
1571 __stringify(__STATE),
1572#include "lockdep_states.h"
1573#undef LOCKDEP_STATE
1574};
1575
1576static const char *state_rnames[] = {
1577#define LOCKDEP_STATE(__STATE) \
1578 __stringify(__STATE)"-READ",
1579#include "lockdep_states.h"
1580#undef LOCKDEP_STATE
1581};
1582
1583static inline const char *state_name(enum lock_usage_bit bit)
1584{
1585 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1586}
1587
1588static int exclusive_bit(int new_bit)
1589{
1590 /*
1591 * USED_IN
1592 * USED_IN_READ
1593 * ENABLED
1594 * ENABLED_READ
1595 *
1596 * bit 0 - write/read
1597 * bit 1 - used_in/enabled
1598 * bit 2+ state
1599 */
1600
1601 int state = new_bit & ~3;
1602 int dir = new_bit & 2;
1603
1604 /*
1605 * keep state, bit flip the direction and strip read.
1606 */
1607 return state | (dir ^ 2);
1608}
1609
1610static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1611 struct held_lock *next, enum lock_usage_bit bit)
1612{
1613 /*
1614 * Prove that the new dependency does not connect a hardirq-safe
1615 * lock with a hardirq-unsafe lock - to achieve this we search
1616 * the backwards-subgraph starting at <prev>, and the
1617 * forwards-subgraph starting at <next>:
1618 */
1619 if (!check_usage(curr, prev, next, bit,
1620 exclusive_bit(bit), state_name(bit)))
1621 return 0;
1622
1623 bit++; /* _READ */
1624
1625 /*
1626 * Prove that the new dependency does not connect a hardirq-safe-read
1627 * lock with a hardirq-unsafe lock - to achieve this we search
1628 * the backwards-subgraph starting at <prev>, and the
1629 * forwards-subgraph starting at <next>:
1630 */
1631 if (!check_usage(curr, prev, next, bit,
1632 exclusive_bit(bit), state_name(bit)))
1633 return 0;
1634
1635 return 1;
1636}
1637
1638static int
1639check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1640 struct held_lock *next)
1641{
1642#define LOCKDEP_STATE(__STATE) \
1643 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1644 return 0;
1645#include "lockdep_states.h"
1646#undef LOCKDEP_STATE
1647
1648 return 1;
1649}
1650
1651static void inc_chains(void)
1652{
1653 if (current->hardirq_context)
1654 nr_hardirq_chains++;
1655 else {
1656 if (current->softirq_context)
1657 nr_softirq_chains++;
1658 else
1659 nr_process_chains++;
1660 }
1661}
1662
1663#else
1664
1665static inline int
1666check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1667 struct held_lock *next)
1668{
1669 return 1;
1670}
1671
1672static inline void inc_chains(void)
1673{
1674 nr_process_chains++;
1675}
1676
1677#endif
1678
1679static void
1680print_deadlock_scenario(struct held_lock *nxt,
1681 struct held_lock *prv)
1682{
1683 struct lock_class *next = hlock_class(nxt);
1684 struct lock_class *prev = hlock_class(prv);
1685
1686 printk(" Possible unsafe locking scenario:\n\n");
1687 printk(" CPU0\n");
1688 printk(" ----\n");
1689 printk(" lock(");
1690 __print_lock_name(prev);
1691 printk(");\n");
1692 printk(" lock(");
1693 __print_lock_name(next);
1694 printk(");\n");
1695 printk("\n *** DEADLOCK ***\n\n");
1696 printk(" May be due to missing lock nesting notation\n\n");
1697}
1698
1699static int
1700print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1701 struct held_lock *next)
1702{
1703 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1704 return 0;
1705
1706 printk("\n");
1707 printk("=============================================\n");
1708 printk("[ INFO: possible recursive locking detected ]\n");
1709 print_kernel_ident();
1710 printk("---------------------------------------------\n");
1711 printk("%s/%d is trying to acquire lock:\n",
1712 curr->comm, task_pid_nr(curr));
1713 print_lock(next);
1714 printk("\nbut task is already holding lock:\n");
1715 print_lock(prev);
1716
1717 printk("\nother info that might help us debug this:\n");
1718 print_deadlock_scenario(next, prev);
1719 lockdep_print_held_locks(curr);
1720
1721 printk("\nstack backtrace:\n");
1722 dump_stack();
1723
1724 return 0;
1725}
1726
1727/*
1728 * Check whether we are holding such a class already.
1729 *
1730 * (Note that this has to be done separately, because the graph cannot
1731 * detect such classes of deadlocks.)
1732 *
1733 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1734 */
1735static int
1736check_deadlock(struct task_struct *curr, struct held_lock *next,
1737 struct lockdep_map *next_instance, int read)
1738{
1739 struct held_lock *prev;
1740 struct held_lock *nest = NULL;
1741 int i;
1742
1743 for (i = 0; i < curr->lockdep_depth; i++) {
1744 prev = curr->held_locks + i;
1745
1746 if (prev->instance == next->nest_lock)
1747 nest = prev;
1748
1749 if (hlock_class(prev) != hlock_class(next))
1750 continue;
1751
1752 /*
1753 * Allow read-after-read recursion of the same
1754 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1755 */
1756 if ((read == 2) && prev->read)
1757 return 2;
1758
1759 /*
1760 * We're holding the nest_lock, which serializes this lock's
1761 * nesting behaviour.
1762 */
1763 if (nest)
1764 return 2;
1765
1766 return print_deadlock_bug(curr, prev, next);
1767 }
1768 return 1;
1769}
1770
1771/*
1772 * There was a chain-cache miss, and we are about to add a new dependency
1773 * to a previous lock. We recursively validate the following rules:
1774 *
1775 * - would the adding of the <prev> -> <next> dependency create a
1776 * circular dependency in the graph? [== circular deadlock]
1777 *
1778 * - does the new prev->next dependency connect any hardirq-safe lock
1779 * (in the full backwards-subgraph starting at <prev>) with any
1780 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1781 * <next>)? [== illegal lock inversion with hardirq contexts]
1782 *
1783 * - does the new prev->next dependency connect any softirq-safe lock
1784 * (in the full backwards-subgraph starting at <prev>) with any
1785 * softirq-unsafe lock (in the full forwards-subgraph starting at
1786 * <next>)? [== illegal lock inversion with softirq contexts]
1787 *
1788 * any of these scenarios could lead to a deadlock.
1789 *
1790 * Then if all the validations pass, we add the forwards and backwards
1791 * dependency.
1792 */
1793static int
1794check_prev_add(struct task_struct *curr, struct held_lock *prev,
1795 struct held_lock *next, int distance, int *stack_saved)
1796{
1797 struct lock_list *entry;
1798 int ret;
1799 struct lock_list this;
1800 struct lock_list *uninitialized_var(target_entry);
1801 /*
1802 * Static variable, serialized by the graph_lock().
1803 *
1804 * We use this static variable to save the stack trace in case
1805 * we call into this function multiple times due to encountering
1806 * trylocks in the held lock stack.
1807 */
1808 static struct stack_trace trace;
1809
1810 /*
1811 * Prove that the new <prev> -> <next> dependency would not
1812 * create a circular dependency in the graph. (We do this by
1813 * forward-recursing into the graph starting at <next>, and
1814 * checking whether we can reach <prev>.)
1815 *
1816 * We are using global variables to control the recursion, to
1817 * keep the stackframe size of the recursive functions low:
1818 */
1819 this.class = hlock_class(next);
1820 this.parent = NULL;
1821 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1822 if (unlikely(!ret))
1823 return print_circular_bug(&this, target_entry, next, prev);
1824 else if (unlikely(ret < 0))
1825 return print_bfs_bug(ret);
1826
1827 if (!check_prev_add_irq(curr, prev, next))
1828 return 0;
1829
1830 /*
1831 * For recursive read-locks we do all the dependency checks,
1832 * but we dont store read-triggered dependencies (only
1833 * write-triggered dependencies). This ensures that only the
1834 * write-side dependencies matter, and that if for example a
1835 * write-lock never takes any other locks, then the reads are
1836 * equivalent to a NOP.
1837 */
1838 if (next->read == 2 || prev->read == 2)
1839 return 1;
1840 /*
1841 * Is the <prev> -> <next> dependency already present?
1842 *
1843 * (this may occur even though this is a new chain: consider
1844 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1845 * chains - the second one will be new, but L1 already has
1846 * L2 added to its dependency list, due to the first chain.)
1847 */
1848 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1849 if (entry->class == hlock_class(next)) {
1850 if (distance == 1)
1851 entry->distance = 1;
1852 return 2;
1853 }
1854 }
1855
1856 if (!*stack_saved) {
1857 if (!save_trace(&trace))
1858 return 0;
1859 *stack_saved = 1;
1860 }
1861
1862 /*
1863 * Ok, all validations passed, add the new lock
1864 * to the previous lock's dependency list:
1865 */
1866 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1867 &hlock_class(prev)->locks_after,
1868 next->acquire_ip, distance, &trace);
1869
1870 if (!ret)
1871 return 0;
1872
1873 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1874 &hlock_class(next)->locks_before,
1875 next->acquire_ip, distance, &trace);
1876 if (!ret)
1877 return 0;
1878
1879 /*
1880 * Debugging printouts:
1881 */
1882 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1883 /* We drop graph lock, so another thread can overwrite trace. */
1884 *stack_saved = 0;
1885 graph_unlock();
1886 printk("\n new dependency: ");
1887 print_lock_name(hlock_class(prev));
1888 printk(" => ");
1889 print_lock_name(hlock_class(next));
1890 printk("\n");
1891 dump_stack();
1892 return graph_lock();
1893 }
1894 return 1;
1895}
1896
1897/*
1898 * Add the dependency to all directly-previous locks that are 'relevant'.
1899 * The ones that are relevant are (in increasing distance from curr):
1900 * all consecutive trylock entries and the final non-trylock entry - or
1901 * the end of this context's lock-chain - whichever comes first.
1902 */
1903static int
1904check_prevs_add(struct task_struct *curr, struct held_lock *next)
1905{
1906 int depth = curr->lockdep_depth;
1907 int stack_saved = 0;
1908 struct held_lock *hlock;
1909
1910 /*
1911 * Debugging checks.
1912 *
1913 * Depth must not be zero for a non-head lock:
1914 */
1915 if (!depth)
1916 goto out_bug;
1917 /*
1918 * At least two relevant locks must exist for this
1919 * to be a head:
1920 */
1921 if (curr->held_locks[depth].irq_context !=
1922 curr->held_locks[depth-1].irq_context)
1923 goto out_bug;
1924
1925 for (;;) {
1926 int distance = curr->lockdep_depth - depth + 1;
1927 hlock = curr->held_locks + depth - 1;
1928 /*
1929 * Only non-recursive-read entries get new dependencies
1930 * added:
1931 */
1932 if (hlock->read != 2 && hlock->check) {
1933 if (!check_prev_add(curr, hlock, next,
1934 distance, &stack_saved))
1935 return 0;
1936 /*
1937 * Stop after the first non-trylock entry,
1938 * as non-trylock entries have added their
1939 * own direct dependencies already, so this
1940 * lock is connected to them indirectly:
1941 */
1942 if (!hlock->trylock)
1943 break;
1944 }
1945 depth--;
1946 /*
1947 * End of lock-stack?
1948 */
1949 if (!depth)
1950 break;
1951 /*
1952 * Stop the search if we cross into another context:
1953 */
1954 if (curr->held_locks[depth].irq_context !=
1955 curr->held_locks[depth-1].irq_context)
1956 break;
1957 }
1958 return 1;
1959out_bug:
1960 if (!debug_locks_off_graph_unlock())
1961 return 0;
1962
1963 /*
1964 * Clearly we all shouldn't be here, but since we made it we
1965 * can reliable say we messed up our state. See the above two
1966 * gotos for reasons why we could possibly end up here.
1967 */
1968 WARN_ON(1);
1969
1970 return 0;
1971}
1972
1973unsigned long nr_lock_chains;
1974struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1975int nr_chain_hlocks;
1976static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1977
1978struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1979{
1980 return lock_classes + chain_hlocks[chain->base + i];
1981}
1982
1983/*
1984 * Returns the index of the first held_lock of the current chain
1985 */
1986static inline int get_first_held_lock(struct task_struct *curr,
1987 struct held_lock *hlock)
1988{
1989 int i;
1990 struct held_lock *hlock_curr;
1991
1992 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1993 hlock_curr = curr->held_locks + i;
1994 if (hlock_curr->irq_context != hlock->irq_context)
1995 break;
1996
1997 }
1998
1999 return ++i;
2000}
2001
2002#ifdef CONFIG_DEBUG_LOCKDEP
2003/*
2004 * Returns the next chain_key iteration
2005 */
2006static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2007{
2008 u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2009
2010 printk(" class_idx:%d -> chain_key:%016Lx",
2011 class_idx,
2012 (unsigned long long)new_chain_key);
2013 return new_chain_key;
2014}
2015
2016static void
2017print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2018{
2019 struct held_lock *hlock;
2020 u64 chain_key = 0;
2021 int depth = curr->lockdep_depth;
2022 int i;
2023
2024 printk("depth: %u\n", depth + 1);
2025 for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
2026 hlock = curr->held_locks + i;
2027 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2028
2029 print_lock(hlock);
2030 }
2031
2032 print_chain_key_iteration(hlock_next->class_idx, chain_key);
2033 print_lock(hlock_next);
2034}
2035
2036static void print_chain_keys_chain(struct lock_chain *chain)
2037{
2038 int i;
2039 u64 chain_key = 0;
2040 int class_id;
2041
2042 printk("depth: %u\n", chain->depth);
2043 for (i = 0; i < chain->depth; i++) {
2044 class_id = chain_hlocks[chain->base + i];
2045 chain_key = print_chain_key_iteration(class_id + 1, chain_key);
2046
2047 print_lock_name(lock_classes + class_id);
2048 printk("\n");
2049 }
2050}
2051
2052static void print_collision(struct task_struct *curr,
2053 struct held_lock *hlock_next,
2054 struct lock_chain *chain)
2055{
2056 printk("\n");
2057 printk("======================\n");
2058 printk("[chain_key collision ]\n");
2059 print_kernel_ident();
2060 printk("----------------------\n");
2061 printk("%s/%d: ", current->comm, task_pid_nr(current));
2062 printk("Hash chain already cached but the contents don't match!\n");
2063
2064 printk("Held locks:");
2065 print_chain_keys_held_locks(curr, hlock_next);
2066
2067 printk("Locks in cached chain:");
2068 print_chain_keys_chain(chain);
2069
2070 printk("\nstack backtrace:\n");
2071 dump_stack();
2072}
2073#endif
2074
2075/*
2076 * Checks whether the chain and the current held locks are consistent
2077 * in depth and also in content. If they are not it most likely means
2078 * that there was a collision during the calculation of the chain_key.
2079 * Returns: 0 not passed, 1 passed
2080 */
2081static int check_no_collision(struct task_struct *curr,
2082 struct held_lock *hlock,
2083 struct lock_chain *chain)
2084{
2085#ifdef CONFIG_DEBUG_LOCKDEP
2086 int i, j, id;
2087
2088 i = get_first_held_lock(curr, hlock);
2089
2090 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2091 print_collision(curr, hlock, chain);
2092 return 0;
2093 }
2094
2095 for (j = 0; j < chain->depth - 1; j++, i++) {
2096 id = curr->held_locks[i].class_idx - 1;
2097
2098 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2099 print_collision(curr, hlock, chain);
2100 return 0;
2101 }
2102 }
2103#endif
2104 return 1;
2105}
2106
2107/*
2108 * Look up a dependency chain. If the key is not present yet then
2109 * add it and return 1 - in this case the new dependency chain is
2110 * validated. If the key is already hashed, return 0.
2111 * (On return with 1 graph_lock is held.)
2112 */
2113static inline int lookup_chain_cache(struct task_struct *curr,
2114 struct held_lock *hlock,
2115 u64 chain_key)
2116{
2117 struct lock_class *class = hlock_class(hlock);
2118 struct hlist_head *hash_head = chainhashentry(chain_key);
2119 struct lock_chain *chain;
2120 int i, j;
2121
2122 /*
2123 * We might need to take the graph lock, ensure we've got IRQs
2124 * disabled to make this an IRQ-safe lock.. for recursion reasons
2125 * lockdep won't complain about its own locking errors.
2126 */
2127 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2128 return 0;
2129 /*
2130 * We can walk it lock-free, because entries only get added
2131 * to the hash:
2132 */
2133 hlist_for_each_entry_rcu(chain, hash_head, entry) {
2134 if (chain->chain_key == chain_key) {
2135cache_hit:
2136 debug_atomic_inc(chain_lookup_hits);
2137 if (!check_no_collision(curr, hlock, chain))
2138 return 0;
2139
2140 if (very_verbose(class))
2141 printk("\nhash chain already cached, key: "
2142 "%016Lx tail class: [%p] %s\n",
2143 (unsigned long long)chain_key,
2144 class->key, class->name);
2145 return 0;
2146 }
2147 }
2148 if (very_verbose(class))
2149 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2150 (unsigned long long)chain_key, class->key, class->name);
2151 /*
2152 * Allocate a new chain entry from the static array, and add
2153 * it to the hash:
2154 */
2155 if (!graph_lock())
2156 return 0;
2157 /*
2158 * We have to walk the chain again locked - to avoid duplicates:
2159 */
2160 hlist_for_each_entry(chain, hash_head, entry) {
2161 if (chain->chain_key == chain_key) {
2162 graph_unlock();
2163 goto cache_hit;
2164 }
2165 }
2166 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2167 if (!debug_locks_off_graph_unlock())
2168 return 0;
2169
2170 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2171 dump_stack();
2172 return 0;
2173 }
2174 chain = lock_chains + nr_lock_chains++;
2175 chain->chain_key = chain_key;
2176 chain->irq_context = hlock->irq_context;
2177 i = get_first_held_lock(curr, hlock);
2178 chain->depth = curr->lockdep_depth + 1 - i;
2179
2180 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2181 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
2182 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2183
2184 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2185 chain->base = nr_chain_hlocks;
2186 for (j = 0; j < chain->depth - 1; j++, i++) {
2187 int lock_id = curr->held_locks[i].class_idx - 1;
2188 chain_hlocks[chain->base + j] = lock_id;
2189 }
2190 chain_hlocks[chain->base + j] = class - lock_classes;
2191 }
2192
2193 if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
2194 nr_chain_hlocks += chain->depth;
2195
2196#ifdef CONFIG_DEBUG_LOCKDEP
2197 /*
2198 * Important for check_no_collision().
2199 */
2200 if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
2201 if (debug_locks_off_graph_unlock())
2202 return 0;
2203
2204 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2205 dump_stack();
2206 return 0;
2207 }
2208#endif
2209
2210 hlist_add_head_rcu(&chain->entry, hash_head);
2211 debug_atomic_inc(chain_lookup_misses);
2212 inc_chains();
2213
2214 return 1;
2215}
2216
2217static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2218 struct held_lock *hlock, int chain_head, u64 chain_key)
2219{
2220 /*
2221 * Trylock needs to maintain the stack of held locks, but it
2222 * does not add new dependencies, because trylock can be done
2223 * in any order.
2224 *
2225 * We look up the chain_key and do the O(N^2) check and update of
2226 * the dependencies only if this is a new dependency chain.
2227 * (If lookup_chain_cache() returns with 1 it acquires
2228 * graph_lock for us)
2229 */
2230 if (!hlock->trylock && hlock->check &&
2231 lookup_chain_cache(curr, hlock, chain_key)) {
2232 /*
2233 * Check whether last held lock:
2234 *
2235 * - is irq-safe, if this lock is irq-unsafe
2236 * - is softirq-safe, if this lock is hardirq-unsafe
2237 *
2238 * And check whether the new lock's dependency graph
2239 * could lead back to the previous lock.
2240 *
2241 * any of these scenarios could lead to a deadlock. If
2242 * All validations
2243 */
2244 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2245
2246 if (!ret)
2247 return 0;
2248 /*
2249 * Mark recursive read, as we jump over it when
2250 * building dependencies (just like we jump over
2251 * trylock entries):
2252 */
2253 if (ret == 2)
2254 hlock->read = 2;
2255 /*
2256 * Add dependency only if this lock is not the head
2257 * of the chain, and if it's not a secondary read-lock:
2258 */
2259 if (!chain_head && ret != 2)
2260 if (!check_prevs_add(curr, hlock))
2261 return 0;
2262 graph_unlock();
2263 } else
2264 /* after lookup_chain_cache(): */
2265 if (unlikely(!debug_locks))
2266 return 0;
2267
2268 return 1;
2269}
2270#else
2271static inline int validate_chain(struct task_struct *curr,
2272 struct lockdep_map *lock, struct held_lock *hlock,
2273 int chain_head, u64 chain_key)
2274{
2275 return 1;
2276}
2277#endif
2278
2279/*
2280 * We are building curr_chain_key incrementally, so double-check
2281 * it from scratch, to make sure that it's done correctly:
2282 */
2283static void check_chain_key(struct task_struct *curr)
2284{
2285#ifdef CONFIG_DEBUG_LOCKDEP
2286 struct held_lock *hlock, *prev_hlock = NULL;
2287 unsigned int i;
2288 u64 chain_key = 0;
2289
2290 for (i = 0; i < curr->lockdep_depth; i++) {
2291 hlock = curr->held_locks + i;
2292 if (chain_key != hlock->prev_chain_key) {
2293 debug_locks_off();
2294 /*
2295 * We got mighty confused, our chain keys don't match
2296 * with what we expect, someone trample on our task state?
2297 */
2298 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2299 curr->lockdep_depth, i,
2300 (unsigned long long)chain_key,
2301 (unsigned long long)hlock->prev_chain_key);
2302 return;
2303 }
2304 /*
2305 * Whoops ran out of static storage again?
2306 */
2307 if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
2308 return;
2309
2310 if (prev_hlock && (prev_hlock->irq_context !=
2311 hlock->irq_context))
2312 chain_key = 0;
2313 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
2314 prev_hlock = hlock;
2315 }
2316 if (chain_key != curr->curr_chain_key) {
2317 debug_locks_off();
2318 /*
2319 * More smoking hash instead of calculating it, damn see these
2320 * numbers float.. I bet that a pink elephant stepped on my memory.
2321 */
2322 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2323 curr->lockdep_depth, i,
2324 (unsigned long long)chain_key,
2325 (unsigned long long)curr->curr_chain_key);
2326 }
2327#endif
2328}
2329
2330static void
2331print_usage_bug_scenario(struct held_lock *lock)
2332{
2333 struct lock_class *class = hlock_class(lock);
2334
2335 printk(" Possible unsafe locking scenario:\n\n");
2336 printk(" CPU0\n");
2337 printk(" ----\n");
2338 printk(" lock(");
2339 __print_lock_name(class);
2340 printk(");\n");
2341 printk(" <Interrupt>\n");
2342 printk(" lock(");
2343 __print_lock_name(class);
2344 printk(");\n");
2345 printk("\n *** DEADLOCK ***\n\n");
2346}
2347
2348static int
2349print_usage_bug(struct task_struct *curr, struct held_lock *this,
2350 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2351{
2352 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2353 return 0;
2354
2355 printk("\n");
2356 printk("=================================\n");
2357 printk("[ INFO: inconsistent lock state ]\n");
2358 print_kernel_ident();
2359 printk("---------------------------------\n");
2360
2361 printk("inconsistent {%s} -> {%s} usage.\n",
2362 usage_str[prev_bit], usage_str[new_bit]);
2363
2364 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2365 curr->comm, task_pid_nr(curr),
2366 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2367 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2368 trace_hardirqs_enabled(curr),
2369 trace_softirqs_enabled(curr));
2370 print_lock(this);
2371
2372 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2373 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2374
2375 print_irqtrace_events(curr);
2376 printk("\nother info that might help us debug this:\n");
2377 print_usage_bug_scenario(this);
2378
2379 lockdep_print_held_locks(curr);
2380
2381 printk("\nstack backtrace:\n");
2382 dump_stack();
2383
2384 return 0;
2385}
2386
2387/*
2388 * Print out an error if an invalid bit is set:
2389 */
2390static inline int
2391valid_state(struct task_struct *curr, struct held_lock *this,
2392 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2393{
2394 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2395 return print_usage_bug(curr, this, bad_bit, new_bit);
2396 return 1;
2397}
2398
2399static int mark_lock(struct task_struct *curr, struct held_lock *this,
2400 enum lock_usage_bit new_bit);
2401
2402#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2403
2404/*
2405 * print irq inversion bug:
2406 */
2407static int
2408print_irq_inversion_bug(struct task_struct *curr,
2409 struct lock_list *root, struct lock_list *other,
2410 struct held_lock *this, int forwards,
2411 const char *irqclass)
2412{
2413 struct lock_list *entry = other;
2414 struct lock_list *middle = NULL;
2415 int depth;
2416
2417 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2418 return 0;
2419
2420 printk("\n");
2421 printk("=========================================================\n");
2422 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2423 print_kernel_ident();
2424 printk("---------------------------------------------------------\n");
2425 printk("%s/%d just changed the state of lock:\n",
2426 curr->comm, task_pid_nr(curr));
2427 print_lock(this);
2428 if (forwards)
2429 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2430 else
2431 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2432 print_lock_name(other->class);
2433 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2434
2435 printk("\nother info that might help us debug this:\n");
2436
2437 /* Find a middle lock (if one exists) */
2438 depth = get_lock_depth(other);
2439 do {
2440 if (depth == 0 && (entry != root)) {
2441 printk("lockdep:%s bad path found in chain graph\n", __func__);
2442 break;
2443 }
2444 middle = entry;
2445 entry = get_lock_parent(entry);
2446 depth--;
2447 } while (entry && entry != root && (depth >= 0));
2448 if (forwards)
2449 print_irq_lock_scenario(root, other,
2450 middle ? middle->class : root->class, other->class);
2451 else
2452 print_irq_lock_scenario(other, root,
2453 middle ? middle->class : other->class, root->class);
2454
2455 lockdep_print_held_locks(curr);
2456
2457 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2458 if (!save_trace(&root->trace))
2459 return 0;
2460 print_shortest_lock_dependencies(other, root);
2461
2462 printk("\nstack backtrace:\n");
2463 dump_stack();
2464
2465 return 0;
2466}
2467
2468/*
2469 * Prove that in the forwards-direction subgraph starting at <this>
2470 * there is no lock matching <mask>:
2471 */
2472static int
2473check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2474 enum lock_usage_bit bit, const char *irqclass)
2475{
2476 int ret;
2477 struct lock_list root;
2478 struct lock_list *uninitialized_var(target_entry);
2479
2480 root.parent = NULL;
2481 root.class = hlock_class(this);
2482 ret = find_usage_forwards(&root, bit, &target_entry);
2483 if (ret < 0)
2484 return print_bfs_bug(ret);
2485 if (ret == 1)
2486 return ret;
2487
2488 return print_irq_inversion_bug(curr, &root, target_entry,
2489 this, 1, irqclass);
2490}
2491
2492/*
2493 * Prove that in the backwards-direction subgraph starting at <this>
2494 * there is no lock matching <mask>:
2495 */
2496static int
2497check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2498 enum lock_usage_bit bit, const char *irqclass)
2499{
2500 int ret;
2501 struct lock_list root;
2502 struct lock_list *uninitialized_var(target_entry);
2503
2504 root.parent = NULL;
2505 root.class = hlock_class(this);
2506 ret = find_usage_backwards(&root, bit, &target_entry);
2507 if (ret < 0)
2508 return print_bfs_bug(ret);
2509 if (ret == 1)
2510 return ret;
2511
2512 return print_irq_inversion_bug(curr, &root, target_entry,
2513 this, 0, irqclass);
2514}
2515
2516void print_irqtrace_events(struct task_struct *curr)
2517{
2518 printk("irq event stamp: %u\n", curr->irq_events);
2519 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2520 print_ip_sym(curr->hardirq_enable_ip);
2521 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2522 print_ip_sym(curr->hardirq_disable_ip);
2523 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2524 print_ip_sym(curr->softirq_enable_ip);
2525 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2526 print_ip_sym(curr->softirq_disable_ip);
2527}
2528
2529static int HARDIRQ_verbose(struct lock_class *class)
2530{
2531#if HARDIRQ_VERBOSE
2532 return class_filter(class);
2533#endif
2534 return 0;
2535}
2536
2537static int SOFTIRQ_verbose(struct lock_class *class)
2538{
2539#if SOFTIRQ_VERBOSE
2540 return class_filter(class);
2541#endif
2542 return 0;
2543}
2544
2545static int RECLAIM_FS_verbose(struct lock_class *class)
2546{
2547#if RECLAIM_VERBOSE
2548 return class_filter(class);
2549#endif
2550 return 0;
2551}
2552
2553#define STRICT_READ_CHECKS 1
2554
2555static int (*state_verbose_f[])(struct lock_class *class) = {
2556#define LOCKDEP_STATE(__STATE) \
2557 __STATE##_verbose,
2558#include "lockdep_states.h"
2559#undef LOCKDEP_STATE
2560};
2561
2562static inline int state_verbose(enum lock_usage_bit bit,
2563 struct lock_class *class)
2564{
2565 return state_verbose_f[bit >> 2](class);
2566}
2567
2568typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2569 enum lock_usage_bit bit, const char *name);
2570
2571static int
2572mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2573 enum lock_usage_bit new_bit)
2574{
2575 int excl_bit = exclusive_bit(new_bit);
2576 int read = new_bit & 1;
2577 int dir = new_bit & 2;
2578
2579 /*
2580 * mark USED_IN has to look forwards -- to ensure no dependency
2581 * has ENABLED state, which would allow recursion deadlocks.
2582 *
2583 * mark ENABLED has to look backwards -- to ensure no dependee
2584 * has USED_IN state, which, again, would allow recursion deadlocks.
2585 */
2586 check_usage_f usage = dir ?
2587 check_usage_backwards : check_usage_forwards;
2588
2589 /*
2590 * Validate that this particular lock does not have conflicting
2591 * usage states.
2592 */
2593 if (!valid_state(curr, this, new_bit, excl_bit))
2594 return 0;
2595
2596 /*
2597 * Validate that the lock dependencies don't have conflicting usage
2598 * states.
2599 */
2600 if ((!read || !dir || STRICT_READ_CHECKS) &&
2601 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2602 return 0;
2603
2604 /*
2605 * Check for read in write conflicts
2606 */
2607 if (!read) {
2608 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2609 return 0;
2610
2611 if (STRICT_READ_CHECKS &&
2612 !usage(curr, this, excl_bit + 1,
2613 state_name(new_bit + 1)))
2614 return 0;
2615 }
2616
2617 if (state_verbose(new_bit, hlock_class(this)))
2618 return 2;
2619
2620 return 1;
2621}
2622
2623enum mark_type {
2624#define LOCKDEP_STATE(__STATE) __STATE,
2625#include "lockdep_states.h"
2626#undef LOCKDEP_STATE
2627};
2628
2629/*
2630 * Mark all held locks with a usage bit:
2631 */
2632static int
2633mark_held_locks(struct task_struct *curr, enum mark_type mark)
2634{
2635 enum lock_usage_bit usage_bit;
2636 struct held_lock *hlock;
2637 int i;
2638
2639 for (i = 0; i < curr->lockdep_depth; i++) {
2640 hlock = curr->held_locks + i;
2641
2642 usage_bit = 2 + (mark << 2); /* ENABLED */
2643 if (hlock->read)
2644 usage_bit += 1; /* READ */
2645
2646 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2647
2648 if (!hlock->check)
2649 continue;
2650
2651 if (!mark_lock(curr, hlock, usage_bit))
2652 return 0;
2653 }
2654
2655 return 1;
2656}
2657
2658/*
2659 * Hardirqs will be enabled:
2660 */
2661static void __trace_hardirqs_on_caller(unsigned long ip)
2662{
2663 struct task_struct *curr = current;
2664
2665 /* we'll do an OFF -> ON transition: */
2666 curr->hardirqs_enabled = 1;
2667
2668 /*
2669 * We are going to turn hardirqs on, so set the
2670 * usage bit for all held locks:
2671 */
2672 if (!mark_held_locks(curr, HARDIRQ))
2673 return;
2674 /*
2675 * If we have softirqs enabled, then set the usage
2676 * bit for all held locks. (disabled hardirqs prevented
2677 * this bit from being set before)
2678 */
2679 if (curr->softirqs_enabled)
2680 if (!mark_held_locks(curr, SOFTIRQ))
2681 return;
2682
2683 curr->hardirq_enable_ip = ip;
2684 curr->hardirq_enable_event = ++curr->irq_events;
2685 debug_atomic_inc(hardirqs_on_events);
2686}
2687
2688__visible void trace_hardirqs_on_caller(unsigned long ip)
2689{
2690 time_hardirqs_on(CALLER_ADDR0, ip);
2691
2692 if (unlikely(!debug_locks || current->lockdep_recursion))
2693 return;
2694
2695 if (unlikely(current->hardirqs_enabled)) {
2696 /*
2697 * Neither irq nor preemption are disabled here
2698 * so this is racy by nature but losing one hit
2699 * in a stat is not a big deal.
2700 */
2701 __debug_atomic_inc(redundant_hardirqs_on);
2702 return;
2703 }
2704
2705 /*
2706 * We're enabling irqs and according to our state above irqs weren't
2707 * already enabled, yet we find the hardware thinks they are in fact
2708 * enabled.. someone messed up their IRQ state tracing.
2709 */
2710 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2711 return;
2712
2713 /*
2714 * See the fine text that goes along with this variable definition.
2715 */
2716 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2717 return;
2718
2719 /*
2720 * Can't allow enabling interrupts while in an interrupt handler,
2721 * that's general bad form and such. Recursion, limited stack etc..
2722 */
2723 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2724 return;
2725
2726 current->lockdep_recursion = 1;
2727 __trace_hardirqs_on_caller(ip);
2728 current->lockdep_recursion = 0;
2729}
2730EXPORT_SYMBOL(trace_hardirqs_on_caller);
2731
2732void trace_hardirqs_on(void)
2733{
2734 trace_hardirqs_on_caller(CALLER_ADDR0);
2735}
2736EXPORT_SYMBOL(trace_hardirqs_on);
2737
2738/*
2739 * Hardirqs were disabled:
2740 */
2741__visible void trace_hardirqs_off_caller(unsigned long ip)
2742{
2743 struct task_struct *curr = current;
2744
2745 time_hardirqs_off(CALLER_ADDR0, ip);
2746
2747 if (unlikely(!debug_locks || current->lockdep_recursion))
2748 return;
2749
2750 /*
2751 * So we're supposed to get called after you mask local IRQs, but for
2752 * some reason the hardware doesn't quite think you did a proper job.
2753 */
2754 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2755 return;
2756
2757 if (curr->hardirqs_enabled) {
2758 /*
2759 * We have done an ON -> OFF transition:
2760 */
2761 curr->hardirqs_enabled = 0;
2762 curr->hardirq_disable_ip = ip;
2763 curr->hardirq_disable_event = ++curr->irq_events;
2764 debug_atomic_inc(hardirqs_off_events);
2765 } else
2766 debug_atomic_inc(redundant_hardirqs_off);
2767}
2768EXPORT_SYMBOL(trace_hardirqs_off_caller);
2769
2770void trace_hardirqs_off(void)
2771{
2772 trace_hardirqs_off_caller(CALLER_ADDR0);
2773}
2774EXPORT_SYMBOL(trace_hardirqs_off);
2775
2776/*
2777 * Softirqs will be enabled:
2778 */
2779void trace_softirqs_on(unsigned long ip)
2780{
2781 struct task_struct *curr = current;
2782
2783 if (unlikely(!debug_locks || current->lockdep_recursion))
2784 return;
2785
2786 /*
2787 * We fancy IRQs being disabled here, see softirq.c, avoids
2788 * funny state and nesting things.
2789 */
2790 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2791 return;
2792
2793 if (curr->softirqs_enabled) {
2794 debug_atomic_inc(redundant_softirqs_on);
2795 return;
2796 }
2797
2798 current->lockdep_recursion = 1;
2799 /*
2800 * We'll do an OFF -> ON transition:
2801 */
2802 curr->softirqs_enabled = 1;
2803 curr->softirq_enable_ip = ip;
2804 curr->softirq_enable_event = ++curr->irq_events;
2805 debug_atomic_inc(softirqs_on_events);
2806 /*
2807 * We are going to turn softirqs on, so set the
2808 * usage bit for all held locks, if hardirqs are
2809 * enabled too:
2810 */
2811 if (curr->hardirqs_enabled)
2812 mark_held_locks(curr, SOFTIRQ);
2813 current->lockdep_recursion = 0;
2814}
2815
2816/*
2817 * Softirqs were disabled:
2818 */
2819void trace_softirqs_off(unsigned long ip)
2820{
2821 struct task_struct *curr = current;
2822
2823 if (unlikely(!debug_locks || current->lockdep_recursion))
2824 return;
2825
2826 /*
2827 * We fancy IRQs being disabled here, see softirq.c
2828 */
2829 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2830 return;
2831
2832 if (curr->softirqs_enabled) {
2833 /*
2834 * We have done an ON -> OFF transition:
2835 */
2836 curr->softirqs_enabled = 0;
2837 curr->softirq_disable_ip = ip;
2838 curr->softirq_disable_event = ++curr->irq_events;
2839 debug_atomic_inc(softirqs_off_events);
2840 /*
2841 * Whoops, we wanted softirqs off, so why aren't they?
2842 */
2843 DEBUG_LOCKS_WARN_ON(!softirq_count());
2844 } else
2845 debug_atomic_inc(redundant_softirqs_off);
2846}
2847
2848static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2849{
2850 struct task_struct *curr = current;
2851
2852 if (unlikely(!debug_locks))
2853 return;
2854
2855 /* no reclaim without waiting on it */
2856 if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
2857 return;
2858
2859 /* this guy won't enter reclaim */
2860 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2861 return;
2862
2863 /* We're only interested __GFP_FS allocations for now */
2864 if (!(gfp_mask & __GFP_FS))
2865 return;
2866
2867 /*
2868 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2869 */
2870 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2871 return;
2872
2873 mark_held_locks(curr, RECLAIM_FS);
2874}
2875
2876static void check_flags(unsigned long flags);
2877
2878void lockdep_trace_alloc(gfp_t gfp_mask)
2879{
2880 unsigned long flags;
2881
2882 if (unlikely(current->lockdep_recursion))
2883 return;
2884
2885 raw_local_irq_save(flags);
2886 check_flags(flags);
2887 current->lockdep_recursion = 1;
2888 __lockdep_trace_alloc(gfp_mask, flags);
2889 current->lockdep_recursion = 0;
2890 raw_local_irq_restore(flags);
2891}
2892
2893static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2894{
2895 /*
2896 * If non-trylock use in a hardirq or softirq context, then
2897 * mark the lock as used in these contexts:
2898 */
2899 if (!hlock->trylock) {
2900 if (hlock->read) {
2901 if (curr->hardirq_context)
2902 if (!mark_lock(curr, hlock,
2903 LOCK_USED_IN_HARDIRQ_READ))
2904 return 0;
2905 if (curr->softirq_context)
2906 if (!mark_lock(curr, hlock,
2907 LOCK_USED_IN_SOFTIRQ_READ))
2908 return 0;
2909 } else {
2910 if (curr->hardirq_context)
2911 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2912 return 0;
2913 if (curr->softirq_context)
2914 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2915 return 0;
2916 }
2917 }
2918 if (!hlock->hardirqs_off) {
2919 if (hlock->read) {
2920 if (!mark_lock(curr, hlock,
2921 LOCK_ENABLED_HARDIRQ_READ))
2922 return 0;
2923 if (curr->softirqs_enabled)
2924 if (!mark_lock(curr, hlock,
2925 LOCK_ENABLED_SOFTIRQ_READ))
2926 return 0;
2927 } else {
2928 if (!mark_lock(curr, hlock,
2929 LOCK_ENABLED_HARDIRQ))
2930 return 0;
2931 if (curr->softirqs_enabled)
2932 if (!mark_lock(curr, hlock,
2933 LOCK_ENABLED_SOFTIRQ))
2934 return 0;
2935 }
2936 }
2937
2938 /*
2939 * We reuse the irq context infrastructure more broadly as a general
2940 * context checking code. This tests GFP_FS recursion (a lock taken
2941 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2942 * allocation).
2943 */
2944 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2945 if (hlock->read) {
2946 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2947 return 0;
2948 } else {
2949 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2950 return 0;
2951 }
2952 }
2953
2954 return 1;
2955}
2956
2957static inline unsigned int task_irq_context(struct task_struct *task)
2958{
2959 return 2 * !!task->hardirq_context + !!task->softirq_context;
2960}
2961
2962static int separate_irq_context(struct task_struct *curr,
2963 struct held_lock *hlock)
2964{
2965 unsigned int depth = curr->lockdep_depth;
2966
2967 /*
2968 * Keep track of points where we cross into an interrupt context:
2969 */
2970 if (depth) {
2971 struct held_lock *prev_hlock;
2972
2973 prev_hlock = curr->held_locks + depth-1;
2974 /*
2975 * If we cross into another context, reset the
2976 * hash key (this also prevents the checking and the
2977 * adding of the dependency to 'prev'):
2978 */
2979 if (prev_hlock->irq_context != hlock->irq_context)
2980 return 1;
2981 }
2982 return 0;
2983}
2984
2985#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2986
2987static inline
2988int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2989 enum lock_usage_bit new_bit)
2990{
2991 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2992 return 1;
2993}
2994
2995static inline int mark_irqflags(struct task_struct *curr,
2996 struct held_lock *hlock)
2997{
2998 return 1;
2999}
3000
3001static inline unsigned int task_irq_context(struct task_struct *task)
3002{
3003 return 0;
3004}
3005
3006static inline int separate_irq_context(struct task_struct *curr,
3007 struct held_lock *hlock)
3008{
3009 return 0;
3010}
3011
3012void lockdep_trace_alloc(gfp_t gfp_mask)
3013{
3014}
3015
3016#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3017
3018/*
3019 * Mark a lock with a usage bit, and validate the state transition:
3020 */
3021static int mark_lock(struct task_struct *curr, struct held_lock *this,
3022 enum lock_usage_bit new_bit)
3023{
3024 unsigned int new_mask = 1 << new_bit, ret = 1;
3025
3026 /*
3027 * If already set then do not dirty the cacheline,
3028 * nor do any checks:
3029 */
3030 if (likely(hlock_class(this)->usage_mask & new_mask))
3031 return 1;
3032
3033 if (!graph_lock())
3034 return 0;
3035 /*
3036 * Make sure we didn't race:
3037 */
3038 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3039 graph_unlock();
3040 return 1;
3041 }
3042
3043 hlock_class(this)->usage_mask |= new_mask;
3044
3045 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
3046 return 0;
3047
3048 switch (new_bit) {
3049#define LOCKDEP_STATE(__STATE) \
3050 case LOCK_USED_IN_##__STATE: \
3051 case LOCK_USED_IN_##__STATE##_READ: \
3052 case LOCK_ENABLED_##__STATE: \
3053 case LOCK_ENABLED_##__STATE##_READ:
3054#include "lockdep_states.h"
3055#undef LOCKDEP_STATE
3056 ret = mark_lock_irq(curr, this, new_bit);
3057 if (!ret)
3058 return 0;
3059 break;
3060 case LOCK_USED:
3061 debug_atomic_dec(nr_unused_locks);
3062 break;
3063 default:
3064 if (!debug_locks_off_graph_unlock())
3065 return 0;
3066 WARN_ON(1);
3067 return 0;
3068 }
3069
3070 graph_unlock();
3071
3072 /*
3073 * We must printk outside of the graph_lock:
3074 */
3075 if (ret == 2) {
3076 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3077 print_lock(this);
3078 print_irqtrace_events(curr);
3079 dump_stack();
3080 }
3081
3082 return ret;
3083}
3084
3085/*
3086 * Initialize a lock instance's lock-class mapping info:
3087 */
3088void lockdep_init_map(struct lockdep_map *lock, const char *name,
3089 struct lock_class_key *key, int subclass)
3090{
3091 int i;
3092
3093 kmemcheck_mark_initialized(lock, sizeof(*lock));
3094
3095 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3096 lock->class_cache[i] = NULL;
3097
3098#ifdef CONFIG_LOCK_STAT
3099 lock->cpu = raw_smp_processor_id();
3100#endif
3101
3102 /*
3103 * Can't be having no nameless bastards around this place!
3104 */
3105 if (DEBUG_LOCKS_WARN_ON(!name)) {
3106 lock->name = "NULL";
3107 return;
3108 }
3109
3110 lock->name = name;
3111
3112 /*
3113 * No key, no joy, we need to hash something.
3114 */
3115 if (DEBUG_LOCKS_WARN_ON(!key))
3116 return;
3117 /*
3118 * Sanity check, the lock-class key must be persistent:
3119 */
3120 if (!static_obj(key)) {
3121 printk("BUG: key %p not in .data!\n", key);
3122 /*
3123 * What it says above ^^^^^, I suggest you read it.
3124 */
3125 DEBUG_LOCKS_WARN_ON(1);
3126 return;
3127 }
3128 lock->key = key;
3129
3130 if (unlikely(!debug_locks))
3131 return;
3132
3133 if (subclass) {
3134 unsigned long flags;
3135
3136 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3137 return;
3138
3139 raw_local_irq_save(flags);
3140 current->lockdep_recursion = 1;
3141 register_lock_class(lock, subclass, 1);
3142 current->lockdep_recursion = 0;
3143 raw_local_irq_restore(flags);
3144 }
3145}
3146EXPORT_SYMBOL_GPL(lockdep_init_map);
3147
3148struct lock_class_key __lockdep_no_validate__;
3149EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3150
3151static int
3152print_lock_nested_lock_not_held(struct task_struct *curr,
3153 struct held_lock *hlock,
3154 unsigned long ip)
3155{
3156 if (!debug_locks_off())
3157 return 0;
3158 if (debug_locks_silent)
3159 return 0;
3160
3161 printk("\n");
3162 printk("==================================\n");
3163 printk("[ BUG: Nested lock was not taken ]\n");
3164 print_kernel_ident();
3165 printk("----------------------------------\n");
3166
3167 printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3168 print_lock(hlock);
3169
3170 printk("\nbut this task is not holding:\n");
3171 printk("%s\n", hlock->nest_lock->name);
3172
3173 printk("\nstack backtrace:\n");
3174 dump_stack();
3175
3176 printk("\nother info that might help us debug this:\n");
3177 lockdep_print_held_locks(curr);
3178
3179 printk("\nstack backtrace:\n");
3180 dump_stack();
3181
3182 return 0;
3183}
3184
3185static int __lock_is_held(struct lockdep_map *lock);
3186
3187/*
3188 * This gets called for every mutex_lock*()/spin_lock*() operation.
3189 * We maintain the dependency maps and validate the locking attempt:
3190 */
3191static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3192 int trylock, int read, int check, int hardirqs_off,
3193 struct lockdep_map *nest_lock, unsigned long ip,
3194 int references, int pin_count)
3195{
3196 struct task_struct *curr = current;
3197 struct lock_class *class = NULL;
3198 struct held_lock *hlock;
3199 unsigned int depth;
3200 int chain_head = 0;
3201 int class_idx;
3202 u64 chain_key;
3203
3204 if (unlikely(!debug_locks))
3205 return 0;
3206
3207 /*
3208 * Lockdep should run with IRQs disabled, otherwise we could
3209 * get an interrupt which would want to take locks, which would
3210 * end up in lockdep and have you got a head-ache already?
3211 */
3212 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3213 return 0;
3214
3215 if (!prove_locking || lock->key == &__lockdep_no_validate__)
3216 check = 0;
3217
3218 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3219 class = lock->class_cache[subclass];
3220 /*
3221 * Not cached?
3222 */
3223 if (unlikely(!class)) {
3224 class = register_lock_class(lock, subclass, 0);
3225 if (!class)
3226 return 0;
3227 }
3228 atomic_inc((atomic_t *)&class->ops);
3229 if (very_verbose(class)) {
3230 printk("\nacquire class [%p] %s", class->key, class->name);
3231 if (class->name_version > 1)
3232 printk("#%d", class->name_version);
3233 printk("\n");
3234 dump_stack();
3235 }
3236
3237 /*
3238 * Add the lock to the list of currently held locks.
3239 * (we dont increase the depth just yet, up until the
3240 * dependency checks are done)
3241 */
3242 depth = curr->lockdep_depth;
3243 /*
3244 * Ran out of static storage for our per-task lock stack again have we?
3245 */
3246 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3247 return 0;
3248
3249 class_idx = class - lock_classes + 1;
3250
3251 if (depth) {
3252 hlock = curr->held_locks + depth - 1;
3253 if (hlock->class_idx == class_idx && nest_lock) {
3254 if (hlock->references)
3255 hlock->references++;
3256 else
3257 hlock->references = 2;
3258
3259 return 1;
3260 }
3261 }
3262
3263 hlock = curr->held_locks + depth;
3264 /*
3265 * Plain impossible, we just registered it and checked it weren't no
3266 * NULL like.. I bet this mushroom I ate was good!
3267 */
3268 if (DEBUG_LOCKS_WARN_ON(!class))
3269 return 0;
3270 hlock->class_idx = class_idx;
3271 hlock->acquire_ip = ip;
3272 hlock->instance = lock;
3273 hlock->nest_lock = nest_lock;
3274 hlock->irq_context = task_irq_context(curr);
3275 hlock->trylock = trylock;
3276 hlock->read = read;
3277 hlock->check = check;
3278 hlock->hardirqs_off = !!hardirqs_off;
3279 hlock->references = references;
3280#ifdef CONFIG_LOCK_STAT
3281 hlock->waittime_stamp = 0;
3282 hlock->holdtime_stamp = lockstat_clock();
3283#endif
3284 hlock->pin_count = pin_count;
3285
3286 if (check && !mark_irqflags(curr, hlock))
3287 return 0;
3288
3289 /* mark it as used: */
3290 if (!mark_lock(curr, hlock, LOCK_USED))
3291 return 0;
3292
3293 /*
3294 * Calculate the chain hash: it's the combined hash of all the
3295 * lock keys along the dependency chain. We save the hash value
3296 * at every step so that we can get the current hash easily
3297 * after unlock. The chain hash is then used to cache dependency
3298 * results.
3299 *
3300 * The 'key ID' is what is the most compact key value to drive
3301 * the hash, not class->key.
3302 */
3303 /*
3304 * Whoops, we did it again.. ran straight out of our static allocation.
3305 */
3306 if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
3307 return 0;
3308
3309 chain_key = curr->curr_chain_key;
3310 if (!depth) {
3311 /*
3312 * How can we have a chain hash when we ain't got no keys?!
3313 */
3314 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3315 return 0;
3316 chain_head = 1;
3317 }
3318
3319 hlock->prev_chain_key = chain_key;
3320 if (separate_irq_context(curr, hlock)) {
3321 chain_key = 0;
3322 chain_head = 1;
3323 }
3324 chain_key = iterate_chain_key(chain_key, class_idx);
3325
3326 if (nest_lock && !__lock_is_held(nest_lock))
3327 return print_lock_nested_lock_not_held(curr, hlock, ip);
3328
3329 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3330 return 0;
3331
3332 curr->curr_chain_key = chain_key;
3333 curr->lockdep_depth++;
3334 check_chain_key(curr);
3335#ifdef CONFIG_DEBUG_LOCKDEP
3336 if (unlikely(!debug_locks))
3337 return 0;
3338#endif
3339 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3340 debug_locks_off();
3341 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3342 printk(KERN_DEBUG "depth: %i max: %lu!\n",
3343 curr->lockdep_depth, MAX_LOCK_DEPTH);
3344
3345 lockdep_print_held_locks(current);
3346 debug_show_all_locks();
3347 dump_stack();
3348
3349 return 0;
3350 }
3351
3352 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3353 max_lockdep_depth = curr->lockdep_depth;
3354
3355 return 1;
3356}
3357
3358static int
3359print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3360 unsigned long ip)
3361{
3362 if (!debug_locks_off())
3363 return 0;
3364 if (debug_locks_silent)
3365 return 0;
3366
3367 printk("\n");
3368 printk("=====================================\n");
3369 printk("[ BUG: bad unlock balance detected! ]\n");
3370 print_kernel_ident();
3371 printk("-------------------------------------\n");
3372 printk("%s/%d is trying to release lock (",
3373 curr->comm, task_pid_nr(curr));
3374 print_lockdep_cache(lock);
3375 printk(") at:\n");
3376 print_ip_sym(ip);
3377 printk("but there are no more locks to release!\n");
3378 printk("\nother info that might help us debug this:\n");
3379 lockdep_print_held_locks(curr);
3380
3381 printk("\nstack backtrace:\n");
3382 dump_stack();
3383
3384 return 0;
3385}
3386
3387static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3388{
3389 if (hlock->instance == lock)
3390 return 1;
3391
3392 if (hlock->references) {
3393 struct lock_class *class = lock->class_cache[0];
3394
3395 if (!class)
3396 class = look_up_lock_class(lock, 0);
3397
3398 /*
3399 * If look_up_lock_class() failed to find a class, we're trying
3400 * to test if we hold a lock that has never yet been acquired.
3401 * Clearly if the lock hasn't been acquired _ever_, we're not
3402 * holding it either, so report failure.
3403 */
3404 if (!class)
3405 return 0;
3406
3407 /*
3408 * References, but not a lock we're actually ref-counting?
3409 * State got messed up, follow the sites that change ->references
3410 * and try to make sense of it.
3411 */
3412 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3413 return 0;
3414
3415 if (hlock->class_idx == class - lock_classes + 1)
3416 return 1;
3417 }
3418
3419 return 0;
3420}
3421
3422static int
3423__lock_set_class(struct lockdep_map *lock, const char *name,
3424 struct lock_class_key *key, unsigned int subclass,
3425 unsigned long ip)
3426{
3427 struct task_struct *curr = current;
3428 struct held_lock *hlock, *prev_hlock;
3429 struct lock_class *class;
3430 unsigned int depth;
3431 int i;
3432
3433 depth = curr->lockdep_depth;
3434 /*
3435 * This function is about (re)setting the class of a held lock,
3436 * yet we're not actually holding any locks. Naughty user!
3437 */
3438 if (DEBUG_LOCKS_WARN_ON(!depth))
3439 return 0;
3440
3441 prev_hlock = NULL;
3442 for (i = depth-1; i >= 0; i--) {
3443 hlock = curr->held_locks + i;
3444 /*
3445 * We must not cross into another context:
3446 */
3447 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3448 break;
3449 if (match_held_lock(hlock, lock))
3450 goto found_it;
3451 prev_hlock = hlock;
3452 }
3453 return print_unlock_imbalance_bug(curr, lock, ip);
3454
3455found_it:
3456 lockdep_init_map(lock, name, key, 0);
3457 class = register_lock_class(lock, subclass, 0);
3458 hlock->class_idx = class - lock_classes + 1;
3459
3460 curr->lockdep_depth = i;
3461 curr->curr_chain_key = hlock->prev_chain_key;
3462
3463 for (; i < depth; i++) {
3464 hlock = curr->held_locks + i;
3465 if (!__lock_acquire(hlock->instance,
3466 hlock_class(hlock)->subclass, hlock->trylock,
3467 hlock->read, hlock->check, hlock->hardirqs_off,
3468 hlock->nest_lock, hlock->acquire_ip,
3469 hlock->references, hlock->pin_count))
3470 return 0;
3471 }
3472
3473 /*
3474 * I took it apart and put it back together again, except now I have
3475 * these 'spare' parts.. where shall I put them.
3476 */
3477 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3478 return 0;
3479 return 1;
3480}
3481
3482/*
3483 * Remove the lock to the list of currently held locks - this gets
3484 * called on mutex_unlock()/spin_unlock*() (or on a failed
3485 * mutex_lock_interruptible()).
3486 *
3487 * @nested is an hysterical artifact, needs a tree wide cleanup.
3488 */
3489static int
3490__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3491{
3492 struct task_struct *curr = current;
3493 struct held_lock *hlock, *prev_hlock;
3494 unsigned int depth;
3495 int i;
3496
3497 if (unlikely(!debug_locks))
3498 return 0;
3499
3500 depth = curr->lockdep_depth;
3501 /*
3502 * So we're all set to release this lock.. wait what lock? We don't
3503 * own any locks, you've been drinking again?
3504 */
3505 if (DEBUG_LOCKS_WARN_ON(depth <= 0))
3506 return print_unlock_imbalance_bug(curr, lock, ip);
3507
3508 /*
3509 * Check whether the lock exists in the current stack
3510 * of held locks:
3511 */
3512 prev_hlock = NULL;
3513 for (i = depth-1; i >= 0; i--) {
3514 hlock = curr->held_locks + i;
3515 /*
3516 * We must not cross into another context:
3517 */
3518 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3519 break;
3520 if (match_held_lock(hlock, lock))
3521 goto found_it;
3522 prev_hlock = hlock;
3523 }
3524 return print_unlock_imbalance_bug(curr, lock, ip);
3525
3526found_it:
3527 if (hlock->instance == lock)
3528 lock_release_holdtime(hlock);
3529
3530 WARN(hlock->pin_count, "releasing a pinned lock\n");
3531
3532 if (hlock->references) {
3533 hlock->references--;
3534 if (hlock->references) {
3535 /*
3536 * We had, and after removing one, still have
3537 * references, the current lock stack is still
3538 * valid. We're done!
3539 */
3540 return 1;
3541 }
3542 }
3543
3544 /*
3545 * We have the right lock to unlock, 'hlock' points to it.
3546 * Now we remove it from the stack, and add back the other
3547 * entries (if any), recalculating the hash along the way:
3548 */
3549
3550 curr->lockdep_depth = i;
3551 curr->curr_chain_key = hlock->prev_chain_key;
3552
3553 for (i++; i < depth; i++) {
3554 hlock = curr->held_locks + i;
3555 if (!__lock_acquire(hlock->instance,
3556 hlock_class(hlock)->subclass, hlock->trylock,
3557 hlock->read, hlock->check, hlock->hardirqs_off,
3558 hlock->nest_lock, hlock->acquire_ip,
3559 hlock->references, hlock->pin_count))
3560 return 0;
3561 }
3562
3563 /*
3564 * We had N bottles of beer on the wall, we drank one, but now
3565 * there's not N-1 bottles of beer left on the wall...
3566 */
3567 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3568 return 0;
3569
3570 return 1;
3571}
3572
3573static int __lock_is_held(struct lockdep_map *lock)
3574{
3575 struct task_struct *curr = current;
3576 int i;
3577
3578 for (i = 0; i < curr->lockdep_depth; i++) {
3579 struct held_lock *hlock = curr->held_locks + i;
3580
3581 if (match_held_lock(hlock, lock))
3582 return 1;
3583 }
3584
3585 return 0;
3586}
3587
3588static void __lock_pin_lock(struct lockdep_map *lock)
3589{
3590 struct task_struct *curr = current;
3591 int i;
3592
3593 if (unlikely(!debug_locks))
3594 return;
3595
3596 for (i = 0; i < curr->lockdep_depth; i++) {
3597 struct held_lock *hlock = curr->held_locks + i;
3598
3599 if (match_held_lock(hlock, lock)) {
3600 hlock->pin_count++;
3601 return;
3602 }
3603 }
3604
3605 WARN(1, "pinning an unheld lock\n");
3606}
3607
3608static void __lock_unpin_lock(struct lockdep_map *lock)
3609{
3610 struct task_struct *curr = current;
3611 int i;
3612
3613 if (unlikely(!debug_locks))
3614 return;
3615
3616 for (i = 0; i < curr->lockdep_depth; i++) {
3617 struct held_lock *hlock = curr->held_locks + i;
3618
3619 if (match_held_lock(hlock, lock)) {
3620 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
3621 return;
3622
3623 hlock->pin_count--;
3624 return;
3625 }
3626 }
3627
3628 WARN(1, "unpinning an unheld lock\n");
3629}
3630
3631/*
3632 * Check whether we follow the irq-flags state precisely:
3633 */
3634static void check_flags(unsigned long flags)
3635{
3636#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3637 defined(CONFIG_TRACE_IRQFLAGS)
3638 if (!debug_locks)
3639 return;
3640
3641 if (irqs_disabled_flags(flags)) {
3642 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3643 printk("possible reason: unannotated irqs-off.\n");
3644 }
3645 } else {
3646 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3647 printk("possible reason: unannotated irqs-on.\n");
3648 }
3649 }
3650
3651 /*
3652 * We dont accurately track softirq state in e.g.
3653 * hardirq contexts (such as on 4KSTACKS), so only
3654 * check if not in hardirq contexts:
3655 */
3656 if (!hardirq_count()) {
3657 if (softirq_count()) {
3658 /* like the above, but with softirqs */
3659 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3660 } else {
3661 /* lick the above, does it taste good? */
3662 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3663 }
3664 }
3665
3666 if (!debug_locks)
3667 print_irqtrace_events(current);
3668#endif
3669}
3670
3671void lock_set_class(struct lockdep_map *lock, const char *name,
3672 struct lock_class_key *key, unsigned int subclass,
3673 unsigned long ip)
3674{
3675 unsigned long flags;
3676
3677 if (unlikely(current->lockdep_recursion))
3678 return;
3679
3680 raw_local_irq_save(flags);
3681 current->lockdep_recursion = 1;
3682 check_flags(flags);
3683 if (__lock_set_class(lock, name, key, subclass, ip))
3684 check_chain_key(current);
3685 current->lockdep_recursion = 0;
3686 raw_local_irq_restore(flags);
3687}
3688EXPORT_SYMBOL_GPL(lock_set_class);
3689
3690/*
3691 * We are not always called with irqs disabled - do that here,
3692 * and also avoid lockdep recursion:
3693 */
3694void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3695 int trylock, int read, int check,
3696 struct lockdep_map *nest_lock, unsigned long ip)
3697{
3698 unsigned long flags;
3699
3700 if (unlikely(current->lockdep_recursion))
3701 return;
3702
3703 raw_local_irq_save(flags);
3704 check_flags(flags);
3705
3706 current->lockdep_recursion = 1;
3707 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3708 __lock_acquire(lock, subclass, trylock, read, check,
3709 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
3710 current->lockdep_recursion = 0;
3711 raw_local_irq_restore(flags);
3712}
3713EXPORT_SYMBOL_GPL(lock_acquire);
3714
3715void lock_release(struct lockdep_map *lock, int nested,
3716 unsigned long ip)
3717{
3718 unsigned long flags;
3719
3720 if (unlikely(current->lockdep_recursion))
3721 return;
3722
3723 raw_local_irq_save(flags);
3724 check_flags(flags);
3725 current->lockdep_recursion = 1;
3726 trace_lock_release(lock, ip);
3727 if (__lock_release(lock, nested, ip))
3728 check_chain_key(current);
3729 current->lockdep_recursion = 0;
3730 raw_local_irq_restore(flags);
3731}
3732EXPORT_SYMBOL_GPL(lock_release);
3733
3734int lock_is_held(struct lockdep_map *lock)
3735{
3736 unsigned long flags;
3737 int ret = 0;
3738
3739 if (unlikely(current->lockdep_recursion))
3740 return 1; /* avoid false negative lockdep_assert_held() */
3741
3742 raw_local_irq_save(flags);
3743 check_flags(flags);
3744
3745 current->lockdep_recursion = 1;
3746 ret = __lock_is_held(lock);
3747 current->lockdep_recursion = 0;
3748 raw_local_irq_restore(flags);
3749
3750 return ret;
3751}
3752EXPORT_SYMBOL_GPL(lock_is_held);
3753
3754void lock_pin_lock(struct lockdep_map *lock)
3755{
3756 unsigned long flags;
3757
3758 if (unlikely(current->lockdep_recursion))
3759 return;
3760
3761 raw_local_irq_save(flags);
3762 check_flags(flags);
3763
3764 current->lockdep_recursion = 1;
3765 __lock_pin_lock(lock);
3766 current->lockdep_recursion = 0;
3767 raw_local_irq_restore(flags);
3768}
3769EXPORT_SYMBOL_GPL(lock_pin_lock);
3770
3771void lock_unpin_lock(struct lockdep_map *lock)
3772{
3773 unsigned long flags;
3774
3775 if (unlikely(current->lockdep_recursion))
3776 return;
3777
3778 raw_local_irq_save(flags);
3779 check_flags(flags);
3780
3781 current->lockdep_recursion = 1;
3782 __lock_unpin_lock(lock);
3783 current->lockdep_recursion = 0;
3784 raw_local_irq_restore(flags);
3785}
3786EXPORT_SYMBOL_GPL(lock_unpin_lock);
3787
3788void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3789{
3790 current->lockdep_reclaim_gfp = gfp_mask;
3791}
3792
3793void lockdep_clear_current_reclaim_state(void)
3794{
3795 current->lockdep_reclaim_gfp = 0;
3796}
3797
3798#ifdef CONFIG_LOCK_STAT
3799static int
3800print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3801 unsigned long ip)
3802{
3803 if (!debug_locks_off())
3804 return 0;
3805 if (debug_locks_silent)
3806 return 0;
3807
3808 printk("\n");
3809 printk("=================================\n");
3810 printk("[ BUG: bad contention detected! ]\n");
3811 print_kernel_ident();
3812 printk("---------------------------------\n");
3813 printk("%s/%d is trying to contend lock (",
3814 curr->comm, task_pid_nr(curr));
3815 print_lockdep_cache(lock);
3816 printk(") at:\n");
3817 print_ip_sym(ip);
3818 printk("but there are no locks held!\n");
3819 printk("\nother info that might help us debug this:\n");
3820 lockdep_print_held_locks(curr);
3821
3822 printk("\nstack backtrace:\n");
3823 dump_stack();
3824
3825 return 0;
3826}
3827
3828static void
3829__lock_contended(struct lockdep_map *lock, unsigned long ip)
3830{
3831 struct task_struct *curr = current;
3832 struct held_lock *hlock, *prev_hlock;
3833 struct lock_class_stats *stats;
3834 unsigned int depth;
3835 int i, contention_point, contending_point;
3836
3837 depth = curr->lockdep_depth;
3838 /*
3839 * Whee, we contended on this lock, except it seems we're not
3840 * actually trying to acquire anything much at all..
3841 */
3842 if (DEBUG_LOCKS_WARN_ON(!depth))
3843 return;
3844
3845 prev_hlock = NULL;
3846 for (i = depth-1; i >= 0; i--) {
3847 hlock = curr->held_locks + i;
3848 /*
3849 * We must not cross into another context:
3850 */
3851 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3852 break;
3853 if (match_held_lock(hlock, lock))
3854 goto found_it;
3855 prev_hlock = hlock;
3856 }
3857 print_lock_contention_bug(curr, lock, ip);
3858 return;
3859
3860found_it:
3861 if (hlock->instance != lock)
3862 return;
3863
3864 hlock->waittime_stamp = lockstat_clock();
3865
3866 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3867 contending_point = lock_point(hlock_class(hlock)->contending_point,
3868 lock->ip);
3869
3870 stats = get_lock_stats(hlock_class(hlock));
3871 if (contention_point < LOCKSTAT_POINTS)
3872 stats->contention_point[contention_point]++;
3873 if (contending_point < LOCKSTAT_POINTS)
3874 stats->contending_point[contending_point]++;
3875 if (lock->cpu != smp_processor_id())
3876 stats->bounces[bounce_contended + !!hlock->read]++;
3877 put_lock_stats(stats);
3878}
3879
3880static void
3881__lock_acquired(struct lockdep_map *lock, unsigned long ip)
3882{
3883 struct task_struct *curr = current;
3884 struct held_lock *hlock, *prev_hlock;
3885 struct lock_class_stats *stats;
3886 unsigned int depth;
3887 u64 now, waittime = 0;
3888 int i, cpu;
3889
3890 depth = curr->lockdep_depth;
3891 /*
3892 * Yay, we acquired ownership of this lock we didn't try to
3893 * acquire, how the heck did that happen?
3894 */
3895 if (DEBUG_LOCKS_WARN_ON(!depth))
3896 return;
3897
3898 prev_hlock = NULL;
3899 for (i = depth-1; i >= 0; i--) {
3900 hlock = curr->held_locks + i;
3901 /*
3902 * We must not cross into another context:
3903 */
3904 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3905 break;
3906 if (match_held_lock(hlock, lock))
3907 goto found_it;
3908 prev_hlock = hlock;
3909 }
3910 print_lock_contention_bug(curr, lock, _RET_IP_);
3911 return;
3912
3913found_it:
3914 if (hlock->instance != lock)
3915 return;
3916
3917 cpu = smp_processor_id();
3918 if (hlock->waittime_stamp) {
3919 now = lockstat_clock();
3920 waittime = now - hlock->waittime_stamp;
3921 hlock->holdtime_stamp = now;
3922 }
3923
3924 trace_lock_acquired(lock, ip);
3925
3926 stats = get_lock_stats(hlock_class(hlock));
3927 if (waittime) {
3928 if (hlock->read)
3929 lock_time_inc(&stats->read_waittime, waittime);
3930 else
3931 lock_time_inc(&stats->write_waittime, waittime);
3932 }
3933 if (lock->cpu != cpu)
3934 stats->bounces[bounce_acquired + !!hlock->read]++;
3935 put_lock_stats(stats);
3936
3937 lock->cpu = cpu;
3938 lock->ip = ip;
3939}
3940
3941void lock_contended(struct lockdep_map *lock, unsigned long ip)
3942{
3943 unsigned long flags;
3944
3945 if (unlikely(!lock_stat))
3946 return;
3947
3948 if (unlikely(current->lockdep_recursion))
3949 return;
3950
3951 raw_local_irq_save(flags);
3952 check_flags(flags);
3953 current->lockdep_recursion = 1;
3954 trace_lock_contended(lock, ip);
3955 __lock_contended(lock, ip);
3956 current->lockdep_recursion = 0;
3957 raw_local_irq_restore(flags);
3958}
3959EXPORT_SYMBOL_GPL(lock_contended);
3960
3961void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3962{
3963 unsigned long flags;
3964
3965 if (unlikely(!lock_stat))
3966 return;
3967
3968 if (unlikely(current->lockdep_recursion))
3969 return;
3970
3971 raw_local_irq_save(flags);
3972 check_flags(flags);
3973 current->lockdep_recursion = 1;
3974 __lock_acquired(lock, ip);
3975 current->lockdep_recursion = 0;
3976 raw_local_irq_restore(flags);
3977}
3978EXPORT_SYMBOL_GPL(lock_acquired);
3979#endif
3980
3981/*
3982 * Used by the testsuite, sanitize the validator state
3983 * after a simulated failure:
3984 */
3985
3986void lockdep_reset(void)
3987{
3988 unsigned long flags;
3989 int i;
3990
3991 raw_local_irq_save(flags);
3992 current->curr_chain_key = 0;
3993 current->lockdep_depth = 0;
3994 current->lockdep_recursion = 0;
3995 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3996 nr_hardirq_chains = 0;
3997 nr_softirq_chains = 0;
3998 nr_process_chains = 0;
3999 debug_locks = 1;
4000 for (i = 0; i < CHAINHASH_SIZE; i++)
4001 INIT_HLIST_HEAD(chainhash_table + i);
4002 raw_local_irq_restore(flags);
4003}
4004
4005static void zap_class(struct lock_class *class)
4006{
4007 int i;
4008
4009 /*
4010 * Remove all dependencies this lock is
4011 * involved in:
4012 */
4013 for (i = 0; i < nr_list_entries; i++) {
4014 if (list_entries[i].class == class)
4015 list_del_rcu(&list_entries[i].entry);
4016 }
4017 /*
4018 * Unhash the class and remove it from the all_lock_classes list:
4019 */
4020 hlist_del_rcu(&class->hash_entry);
4021 list_del_rcu(&class->lock_entry);
4022
4023 RCU_INIT_POINTER(class->key, NULL);
4024 RCU_INIT_POINTER(class->name, NULL);
4025}
4026
4027static inline int within(const void *addr, void *start, unsigned long size)
4028{
4029 return addr >= start && addr < start + size;
4030}
4031
4032/*
4033 * Used in module.c to remove lock classes from memory that is going to be
4034 * freed; and possibly re-used by other modules.
4035 *
4036 * We will have had one sync_sched() before getting here, so we're guaranteed
4037 * nobody will look up these exact classes -- they're properly dead but still
4038 * allocated.
4039 */
4040void lockdep_free_key_range(void *start, unsigned long size)
4041{
4042 struct lock_class *class;
4043 struct hlist_head *head;
4044 unsigned long flags;
4045 int i;
4046 int locked;
4047
4048 raw_local_irq_save(flags);
4049 locked = graph_lock();
4050
4051 /*
4052 * Unhash all classes that were created by this module:
4053 */
4054 for (i = 0; i < CLASSHASH_SIZE; i++) {
4055 head = classhash_table + i;
4056 hlist_for_each_entry_rcu(class, head, hash_entry) {
4057 if (within(class->key, start, size))
4058 zap_class(class);
4059 else if (within(class->name, start, size))
4060 zap_class(class);
4061 }
4062 }
4063
4064 if (locked)
4065 graph_unlock();
4066 raw_local_irq_restore(flags);
4067
4068 /*
4069 * Wait for any possible iterators from look_up_lock_class() to pass
4070 * before continuing to free the memory they refer to.
4071 *
4072 * sync_sched() is sufficient because the read-side is IRQ disable.
4073 */
4074 synchronize_sched();
4075
4076 /*
4077 * XXX at this point we could return the resources to the pool;
4078 * instead we leak them. We would need to change to bitmap allocators
4079 * instead of the linear allocators we have now.
4080 */
4081}
4082
4083void lockdep_reset_lock(struct lockdep_map *lock)
4084{
4085 struct lock_class *class;
4086 struct hlist_head *head;
4087 unsigned long flags;
4088 int i, j;
4089 int locked;
4090
4091 raw_local_irq_save(flags);
4092
4093 /*
4094 * Remove all classes this lock might have:
4095 */
4096 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
4097 /*
4098 * If the class exists we look it up and zap it:
4099 */
4100 class = look_up_lock_class(lock, j);
4101 if (class)
4102 zap_class(class);
4103 }
4104 /*
4105 * Debug check: in the end all mapped classes should
4106 * be gone.
4107 */
4108 locked = graph_lock();
4109 for (i = 0; i < CLASSHASH_SIZE; i++) {
4110 head = classhash_table + i;
4111 hlist_for_each_entry_rcu(class, head, hash_entry) {
4112 int match = 0;
4113
4114 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
4115 match |= class == lock->class_cache[j];
4116
4117 if (unlikely(match)) {
4118 if (debug_locks_off_graph_unlock()) {
4119 /*
4120 * We all just reset everything, how did it match?
4121 */
4122 WARN_ON(1);
4123 }
4124 goto out_restore;
4125 }
4126 }
4127 }
4128 if (locked)
4129 graph_unlock();
4130
4131out_restore:
4132 raw_local_irq_restore(flags);
4133}
4134
4135void __init lockdep_info(void)
4136{
4137 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4138
4139 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
4140 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
4141 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
4142 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
4143 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
4144 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
4145 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
4146
4147 printk(" memory used by lock dependency info: %lu kB\n",
4148 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4149 sizeof(struct list_head) * CLASSHASH_SIZE +
4150 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4151 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4152 sizeof(struct list_head) * CHAINHASH_SIZE
4153#ifdef CONFIG_PROVE_LOCKING
4154 + sizeof(struct circular_queue)
4155#endif
4156 ) / 1024
4157 );
4158
4159 printk(" per task-struct memory footprint: %lu bytes\n",
4160 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4161}
4162
4163static void
4164print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4165 const void *mem_to, struct held_lock *hlock)
4166{
4167 if (!debug_locks_off())
4168 return;
4169 if (debug_locks_silent)
4170 return;
4171
4172 printk("\n");
4173 printk("=========================\n");
4174 printk("[ BUG: held lock freed! ]\n");
4175 print_kernel_ident();
4176 printk("-------------------------\n");
4177 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4178 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4179 print_lock(hlock);
4180 lockdep_print_held_locks(curr);
4181
4182 printk("\nstack backtrace:\n");
4183 dump_stack();
4184}
4185
4186static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4187 const void* lock_from, unsigned long lock_len)
4188{
4189 return lock_from + lock_len <= mem_from ||
4190 mem_from + mem_len <= lock_from;
4191}
4192
4193/*
4194 * Called when kernel memory is freed (or unmapped), or if a lock
4195 * is destroyed or reinitialized - this code checks whether there is
4196 * any held lock in the memory range of <from> to <to>:
4197 */
4198void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4199{
4200 struct task_struct *curr = current;
4201 struct held_lock *hlock;
4202 unsigned long flags;
4203 int i;
4204
4205 if (unlikely(!debug_locks))
4206 return;
4207
4208 local_irq_save(flags);
4209 for (i = 0; i < curr->lockdep_depth; i++) {
4210 hlock = curr->held_locks + i;
4211
4212 if (not_in_range(mem_from, mem_len, hlock->instance,
4213 sizeof(*hlock->instance)))
4214 continue;
4215
4216 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4217 break;
4218 }
4219 local_irq_restore(flags);
4220}
4221EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4222
4223static void print_held_locks_bug(void)
4224{
4225 if (!debug_locks_off())
4226 return;
4227 if (debug_locks_silent)
4228 return;
4229
4230 printk("\n");
4231 printk("=====================================\n");
4232 printk("[ BUG: %s/%d still has locks held! ]\n",
4233 current->comm, task_pid_nr(current));
4234 print_kernel_ident();
4235 printk("-------------------------------------\n");
4236 lockdep_print_held_locks(current);
4237 printk("\nstack backtrace:\n");
4238 dump_stack();
4239}
4240
4241void debug_check_no_locks_held(void)
4242{
4243 if (unlikely(current->lockdep_depth > 0))
4244 print_held_locks_bug();
4245}
4246EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
4247
4248#ifdef __KERNEL__
4249void debug_show_all_locks(void)
4250{
4251 struct task_struct *g, *p;
4252 int count = 10;
4253 int unlock = 1;
4254
4255 if (unlikely(!debug_locks)) {
4256 printk("INFO: lockdep is turned off.\n");
4257 return;
4258 }
4259 printk("\nShowing all locks held in the system:\n");
4260
4261 /*
4262 * Here we try to get the tasklist_lock as hard as possible,
4263 * if not successful after 2 seconds we ignore it (but keep
4264 * trying). This is to enable a debug printout even if a
4265 * tasklist_lock-holding task deadlocks or crashes.
4266 */
4267retry:
4268 if (!read_trylock(&tasklist_lock)) {
4269 if (count == 10)
4270 printk("hm, tasklist_lock locked, retrying... ");
4271 if (count) {
4272 count--;
4273 printk(" #%d", 10-count);
4274 mdelay(200);
4275 goto retry;
4276 }
4277 printk(" ignoring it.\n");
4278 unlock = 0;
4279 } else {
4280 if (count != 10)
4281 printk(KERN_CONT " locked it.\n");
4282 }
4283
4284 do_each_thread(g, p) {
4285 /*
4286 * It's not reliable to print a task's held locks
4287 * if it's not sleeping (or if it's not the current
4288 * task):
4289 */
4290 if (p->state == TASK_RUNNING && p != current)
4291 continue;
4292 if (p->lockdep_depth)
4293 lockdep_print_held_locks(p);
4294 if (!unlock)
4295 if (read_trylock(&tasklist_lock))
4296 unlock = 1;
4297 } while_each_thread(g, p);
4298
4299 printk("\n");
4300 printk("=============================================\n\n");
4301
4302 if (unlock)
4303 read_unlock(&tasklist_lock);
4304}
4305EXPORT_SYMBOL_GPL(debug_show_all_locks);
4306#endif
4307
4308/*
4309 * Careful: only use this function if you are sure that
4310 * the task cannot run in parallel!
4311 */
4312void debug_show_held_locks(struct task_struct *task)
4313{
4314 if (unlikely(!debug_locks)) {
4315 printk("INFO: lockdep is turned off.\n");
4316 return;
4317 }
4318 lockdep_print_held_locks(task);
4319}
4320EXPORT_SYMBOL_GPL(debug_show_held_locks);
4321
4322asmlinkage __visible void lockdep_sys_exit(void)
4323{
4324 struct task_struct *curr = current;
4325
4326 if (unlikely(curr->lockdep_depth)) {
4327 if (!debug_locks_off())
4328 return;
4329 printk("\n");
4330 printk("================================================\n");
4331 printk("[ BUG: lock held when returning to user space! ]\n");
4332 print_kernel_ident();
4333 printk("------------------------------------------------\n");
4334 printk("%s/%d is leaving the kernel with locks still held!\n",
4335 curr->comm, curr->pid);
4336 lockdep_print_held_locks(curr);
4337 }
4338}
4339
4340void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4341{
4342 struct task_struct *curr = current;
4343
4344#ifndef CONFIG_PROVE_RCU_REPEATEDLY
4345 if (!debug_locks_off())
4346 return;
4347#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4348 /* Note: the following can be executed concurrently, so be careful. */
4349 printk("\n");
4350 printk("===============================\n");
4351 printk("[ INFO: suspicious RCU usage. ]\n");
4352 print_kernel_ident();
4353 printk("-------------------------------\n");
4354 printk("%s:%d %s!\n", file, line, s);
4355 printk("\nother info that might help us debug this:\n\n");
4356 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4357 !rcu_lockdep_current_cpu_online()
4358 ? "RCU used illegally from offline CPU!\n"
4359 : !rcu_is_watching()
4360 ? "RCU used illegally from idle CPU!\n"
4361 : "",
4362 rcu_scheduler_active, debug_locks);
4363
4364 /*
4365 * If a CPU is in the RCU-free window in idle (ie: in the section
4366 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4367 * considers that CPU to be in an "extended quiescent state",
4368 * which means that RCU will be completely ignoring that CPU.
4369 * Therefore, rcu_read_lock() and friends have absolutely no
4370 * effect on a CPU running in that state. In other words, even if
4371 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4372 * delete data structures out from under it. RCU really has no
4373 * choice here: we need to keep an RCU-free window in idle where
4374 * the CPU may possibly enter into low power mode. This way we can
4375 * notice an extended quiescent state to other CPUs that started a grace
4376 * period. Otherwise we would delay any grace period as long as we run
4377 * in the idle task.
4378 *
4379 * So complain bitterly if someone does call rcu_read_lock(),
4380 * rcu_read_lock_bh() and so on from extended quiescent states.
4381 */
4382 if (!rcu_is_watching())
4383 printk("RCU used illegally from extended quiescent state!\n");
4384
4385 lockdep_print_held_locks(curr);
4386 printk("\nstack backtrace:\n");
4387 dump_stack();
4388}
4389EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kernel/lockdep.c
4 *
5 * Runtime locking correctness validator
6 *
7 * Started by Ingo Molnar:
8 *
9 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
10 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
11 *
12 * this code maps all the lock dependencies as they occur in a live kernel
13 * and will warn about the following classes of locking bugs:
14 *
15 * - lock inversion scenarios
16 * - circular lock dependencies
17 * - hardirq/softirq safe/unsafe locking bugs
18 *
19 * Bugs are reported even if the current locking scenario does not cause
20 * any deadlock at this point.
21 *
22 * I.e. if anytime in the past two locks were taken in a different order,
23 * even if it happened for another task, even if those were different
24 * locks (but of the same class as this lock), this code will detect it.
25 *
26 * Thanks to Arjan van de Ven for coming up with the initial idea of
27 * mapping lock dependencies runtime.
28 */
29#define DISABLE_BRANCH_PROFILING
30#include <linux/mutex.h>
31#include <linux/sched.h>
32#include <linux/sched/clock.h>
33#include <linux/sched/task.h>
34#include <linux/sched/mm.h>
35#include <linux/delay.h>
36#include <linux/module.h>
37#include <linux/proc_fs.h>
38#include <linux/seq_file.h>
39#include <linux/spinlock.h>
40#include <linux/kallsyms.h>
41#include <linux/interrupt.h>
42#include <linux/stacktrace.h>
43#include <linux/debug_locks.h>
44#include <linux/irqflags.h>
45#include <linux/utsname.h>
46#include <linux/hash.h>
47#include <linux/ftrace.h>
48#include <linux/stringify.h>
49#include <linux/bitmap.h>
50#include <linux/bitops.h>
51#include <linux/gfp.h>
52#include <linux/random.h>
53#include <linux/jhash.h>
54#include <linux/nmi.h>
55#include <linux/rcupdate.h>
56#include <linux/kprobes.h>
57
58#include <asm/sections.h>
59
60#include "lockdep_internals.h"
61
62#define CREATE_TRACE_POINTS
63#include <trace/events/lock.h>
64
65#ifdef CONFIG_PROVE_LOCKING
66int prove_locking = 1;
67module_param(prove_locking, int, 0644);
68#else
69#define prove_locking 0
70#endif
71
72#ifdef CONFIG_LOCK_STAT
73int lock_stat = 1;
74module_param(lock_stat, int, 0644);
75#else
76#define lock_stat 0
77#endif
78
79/*
80 * lockdep_lock: protects the lockdep graph, the hashes and the
81 * class/list/hash allocators.
82 *
83 * This is one of the rare exceptions where it's justified
84 * to use a raw spinlock - we really dont want the spinlock
85 * code to recurse back into the lockdep code...
86 */
87static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
88static struct task_struct *lockdep_selftest_task_struct;
89
90static int graph_lock(void)
91{
92 arch_spin_lock(&lockdep_lock);
93 /*
94 * Make sure that if another CPU detected a bug while
95 * walking the graph we dont change it (while the other
96 * CPU is busy printing out stuff with the graph lock
97 * dropped already)
98 */
99 if (!debug_locks) {
100 arch_spin_unlock(&lockdep_lock);
101 return 0;
102 }
103 /* prevent any recursions within lockdep from causing deadlocks */
104 current->lockdep_recursion++;
105 return 1;
106}
107
108static inline int graph_unlock(void)
109{
110 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
111 /*
112 * The lockdep graph lock isn't locked while we expect it to
113 * be, we're confused now, bye!
114 */
115 return DEBUG_LOCKS_WARN_ON(1);
116 }
117
118 current->lockdep_recursion--;
119 arch_spin_unlock(&lockdep_lock);
120 return 0;
121}
122
123/*
124 * Turn lock debugging off and return with 0 if it was off already,
125 * and also release the graph lock:
126 */
127static inline int debug_locks_off_graph_unlock(void)
128{
129 int ret = debug_locks_off();
130
131 arch_spin_unlock(&lockdep_lock);
132
133 return ret;
134}
135
136unsigned long nr_list_entries;
137static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
138static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES);
139
140/*
141 * All data structures here are protected by the global debug_lock.
142 *
143 * nr_lock_classes is the number of elements of lock_classes[] that is
144 * in use.
145 */
146#define KEYHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
147#define KEYHASH_SIZE (1UL << KEYHASH_BITS)
148static struct hlist_head lock_keys_hash[KEYHASH_SIZE];
149unsigned long nr_lock_classes;
150#ifndef CONFIG_DEBUG_LOCKDEP
151static
152#endif
153struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
154static DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS);
155
156static inline struct lock_class *hlock_class(struct held_lock *hlock)
157{
158 unsigned int class_idx = hlock->class_idx;
159
160 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfield */
161 barrier();
162
163 if (!test_bit(class_idx, lock_classes_in_use)) {
164 /*
165 * Someone passed in garbage, we give up.
166 */
167 DEBUG_LOCKS_WARN_ON(1);
168 return NULL;
169 }
170
171 /*
172 * At this point, if the passed hlock->class_idx is still garbage,
173 * we just have to live with it
174 */
175 return lock_classes + class_idx;
176}
177
178#ifdef CONFIG_LOCK_STAT
179static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
180
181static inline u64 lockstat_clock(void)
182{
183 return local_clock();
184}
185
186static int lock_point(unsigned long points[], unsigned long ip)
187{
188 int i;
189
190 for (i = 0; i < LOCKSTAT_POINTS; i++) {
191 if (points[i] == 0) {
192 points[i] = ip;
193 break;
194 }
195 if (points[i] == ip)
196 break;
197 }
198
199 return i;
200}
201
202static void lock_time_inc(struct lock_time *lt, u64 time)
203{
204 if (time > lt->max)
205 lt->max = time;
206
207 if (time < lt->min || !lt->nr)
208 lt->min = time;
209
210 lt->total += time;
211 lt->nr++;
212}
213
214static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
215{
216 if (!src->nr)
217 return;
218
219 if (src->max > dst->max)
220 dst->max = src->max;
221
222 if (src->min < dst->min || !dst->nr)
223 dst->min = src->min;
224
225 dst->total += src->total;
226 dst->nr += src->nr;
227}
228
229struct lock_class_stats lock_stats(struct lock_class *class)
230{
231 struct lock_class_stats stats;
232 int cpu, i;
233
234 memset(&stats, 0, sizeof(struct lock_class_stats));
235 for_each_possible_cpu(cpu) {
236 struct lock_class_stats *pcs =
237 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
238
239 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
240 stats.contention_point[i] += pcs->contention_point[i];
241
242 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
243 stats.contending_point[i] += pcs->contending_point[i];
244
245 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
246 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
247
248 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
249 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
250
251 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
252 stats.bounces[i] += pcs->bounces[i];
253 }
254
255 return stats;
256}
257
258void clear_lock_stats(struct lock_class *class)
259{
260 int cpu;
261
262 for_each_possible_cpu(cpu) {
263 struct lock_class_stats *cpu_stats =
264 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
265
266 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
267 }
268 memset(class->contention_point, 0, sizeof(class->contention_point));
269 memset(class->contending_point, 0, sizeof(class->contending_point));
270}
271
272static struct lock_class_stats *get_lock_stats(struct lock_class *class)
273{
274 return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes];
275}
276
277static void lock_release_holdtime(struct held_lock *hlock)
278{
279 struct lock_class_stats *stats;
280 u64 holdtime;
281
282 if (!lock_stat)
283 return;
284
285 holdtime = lockstat_clock() - hlock->holdtime_stamp;
286
287 stats = get_lock_stats(hlock_class(hlock));
288 if (hlock->read)
289 lock_time_inc(&stats->read_holdtime, holdtime);
290 else
291 lock_time_inc(&stats->write_holdtime, holdtime);
292}
293#else
294static inline void lock_release_holdtime(struct held_lock *hlock)
295{
296}
297#endif
298
299/*
300 * We keep a global list of all lock classes. The list is only accessed with
301 * the lockdep spinlock lock held. free_lock_classes is a list with free
302 * elements. These elements are linked together by the lock_entry member in
303 * struct lock_class.
304 */
305LIST_HEAD(all_lock_classes);
306static LIST_HEAD(free_lock_classes);
307
308/**
309 * struct pending_free - information about data structures about to be freed
310 * @zapped: Head of a list with struct lock_class elements.
311 * @lock_chains_being_freed: Bitmap that indicates which lock_chains[] elements
312 * are about to be freed.
313 */
314struct pending_free {
315 struct list_head zapped;
316 DECLARE_BITMAP(lock_chains_being_freed, MAX_LOCKDEP_CHAINS);
317};
318
319/**
320 * struct delayed_free - data structures used for delayed freeing
321 *
322 * A data structure for delayed freeing of data structures that may be
323 * accessed by RCU readers at the time these were freed.
324 *
325 * @rcu_head: Used to schedule an RCU callback for freeing data structures.
326 * @index: Index of @pf to which freed data structures are added.
327 * @scheduled: Whether or not an RCU callback has been scheduled.
328 * @pf: Array with information about data structures about to be freed.
329 */
330static struct delayed_free {
331 struct rcu_head rcu_head;
332 int index;
333 int scheduled;
334 struct pending_free pf[2];
335} delayed_free;
336
337/*
338 * The lockdep classes are in a hash-table as well, for fast lookup:
339 */
340#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
341#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
342#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
343#define classhashentry(key) (classhash_table + __classhashfn((key)))
344
345static struct hlist_head classhash_table[CLASSHASH_SIZE];
346
347/*
348 * We put the lock dependency chains into a hash-table as well, to cache
349 * their existence:
350 */
351#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
352#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
353#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
354#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
355
356static struct hlist_head chainhash_table[CHAINHASH_SIZE];
357
358/*
359 * The hash key of the lock dependency chains is a hash itself too:
360 * it's a hash of all locks taken up to that lock, including that lock.
361 * It's a 64-bit hash, because it's important for the keys to be
362 * unique.
363 */
364static inline u64 iterate_chain_key(u64 key, u32 idx)
365{
366 u32 k0 = key, k1 = key >> 32;
367
368 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
369
370 return k0 | (u64)k1 << 32;
371}
372
373void lockdep_init_task(struct task_struct *task)
374{
375 task->lockdep_depth = 0; /* no locks held yet */
376 task->curr_chain_key = INITIAL_CHAIN_KEY;
377 task->lockdep_recursion = 0;
378}
379
380void lockdep_off(void)
381{
382 current->lockdep_recursion++;
383}
384EXPORT_SYMBOL(lockdep_off);
385
386void lockdep_on(void)
387{
388 current->lockdep_recursion--;
389}
390EXPORT_SYMBOL(lockdep_on);
391
392void lockdep_set_selftest_task(struct task_struct *task)
393{
394 lockdep_selftest_task_struct = task;
395}
396
397/*
398 * Debugging switches:
399 */
400
401#define VERBOSE 0
402#define VERY_VERBOSE 0
403
404#if VERBOSE
405# define HARDIRQ_VERBOSE 1
406# define SOFTIRQ_VERBOSE 1
407#else
408# define HARDIRQ_VERBOSE 0
409# define SOFTIRQ_VERBOSE 0
410#endif
411
412#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
413/*
414 * Quick filtering for interesting events:
415 */
416static int class_filter(struct lock_class *class)
417{
418#if 0
419 /* Example */
420 if (class->name_version == 1 &&
421 !strcmp(class->name, "lockname"))
422 return 1;
423 if (class->name_version == 1 &&
424 !strcmp(class->name, "&struct->lockfield"))
425 return 1;
426#endif
427 /* Filter everything else. 1 would be to allow everything else */
428 return 0;
429}
430#endif
431
432static int verbose(struct lock_class *class)
433{
434#if VERBOSE
435 return class_filter(class);
436#endif
437 return 0;
438}
439
440static void print_lockdep_off(const char *bug_msg)
441{
442 printk(KERN_DEBUG "%s\n", bug_msg);
443 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
444#ifdef CONFIG_LOCK_STAT
445 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
446#endif
447}
448
449unsigned long nr_stack_trace_entries;
450
451#ifdef CONFIG_PROVE_LOCKING
452/**
453 * struct lock_trace - single stack backtrace
454 * @hash_entry: Entry in a stack_trace_hash[] list.
455 * @hash: jhash() of @entries.
456 * @nr_entries: Number of entries in @entries.
457 * @entries: Actual stack backtrace.
458 */
459struct lock_trace {
460 struct hlist_node hash_entry;
461 u32 hash;
462 u32 nr_entries;
463 unsigned long entries[0] __aligned(sizeof(unsigned long));
464};
465#define LOCK_TRACE_SIZE_IN_LONGS \
466 (sizeof(struct lock_trace) / sizeof(unsigned long))
467/*
468 * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock.
469 */
470static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
471static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE];
472
473static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2)
474{
475 return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries &&
476 memcmp(t1->entries, t2->entries,
477 t1->nr_entries * sizeof(t1->entries[0])) == 0;
478}
479
480static struct lock_trace *save_trace(void)
481{
482 struct lock_trace *trace, *t2;
483 struct hlist_head *hash_head;
484 u32 hash;
485 unsigned int max_entries;
486
487 BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE);
488 BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES);
489
490 trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries);
491 max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries -
492 LOCK_TRACE_SIZE_IN_LONGS;
493 trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
494
495 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES -
496 LOCK_TRACE_SIZE_IN_LONGS - 1) {
497 if (!debug_locks_off_graph_unlock())
498 return NULL;
499
500 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
501 dump_stack();
502
503 return NULL;
504 }
505
506 hash = jhash(trace->entries, trace->nr_entries *
507 sizeof(trace->entries[0]), 0);
508 trace->hash = hash;
509 hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1));
510 hlist_for_each_entry(t2, hash_head, hash_entry) {
511 if (traces_identical(trace, t2))
512 return t2;
513 }
514 nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries;
515 hlist_add_head(&trace->hash_entry, hash_head);
516
517 return trace;
518}
519
520/* Return the number of stack traces in the stack_trace[] array. */
521u64 lockdep_stack_trace_count(void)
522{
523 struct lock_trace *trace;
524 u64 c = 0;
525 int i;
526
527 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) {
528 hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) {
529 c++;
530 }
531 }
532
533 return c;
534}
535
536/* Return the number of stack hash chains that have at least one stack trace. */
537u64 lockdep_stack_hash_count(void)
538{
539 u64 c = 0;
540 int i;
541
542 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++)
543 if (!hlist_empty(&stack_trace_hash[i]))
544 c++;
545
546 return c;
547}
548#endif
549
550unsigned int nr_hardirq_chains;
551unsigned int nr_softirq_chains;
552unsigned int nr_process_chains;
553unsigned int max_lockdep_depth;
554
555#ifdef CONFIG_DEBUG_LOCKDEP
556/*
557 * Various lockdep statistics:
558 */
559DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
560#endif
561
562#ifdef CONFIG_PROVE_LOCKING
563/*
564 * Locking printouts:
565 */
566
567#define __USAGE(__STATE) \
568 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
569 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
570 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
571 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
572
573static const char *usage_str[] =
574{
575#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
576#include "lockdep_states.h"
577#undef LOCKDEP_STATE
578 [LOCK_USED] = "INITIAL USE",
579};
580#endif
581
582const char *__get_key_name(const struct lockdep_subclass_key *key, char *str)
583{
584 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
585}
586
587static inline unsigned long lock_flag(enum lock_usage_bit bit)
588{
589 return 1UL << bit;
590}
591
592static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
593{
594 /*
595 * The usage character defaults to '.' (i.e., irqs disabled and not in
596 * irq context), which is the safest usage category.
597 */
598 char c = '.';
599
600 /*
601 * The order of the following usage checks matters, which will
602 * result in the outcome character as follows:
603 *
604 * - '+': irq is enabled and not in irq context
605 * - '-': in irq context and irq is disabled
606 * - '?': in irq context and irq is enabled
607 */
608 if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) {
609 c = '+';
610 if (class->usage_mask & lock_flag(bit))
611 c = '?';
612 } else if (class->usage_mask & lock_flag(bit))
613 c = '-';
614
615 return c;
616}
617
618void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
619{
620 int i = 0;
621
622#define LOCKDEP_STATE(__STATE) \
623 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
624 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
625#include "lockdep_states.h"
626#undef LOCKDEP_STATE
627
628 usage[i] = '\0';
629}
630
631static void __print_lock_name(struct lock_class *class)
632{
633 char str[KSYM_NAME_LEN];
634 const char *name;
635
636 name = class->name;
637 if (!name) {
638 name = __get_key_name(class->key, str);
639 printk(KERN_CONT "%s", name);
640 } else {
641 printk(KERN_CONT "%s", name);
642 if (class->name_version > 1)
643 printk(KERN_CONT "#%d", class->name_version);
644 if (class->subclass)
645 printk(KERN_CONT "/%d", class->subclass);
646 }
647}
648
649static void print_lock_name(struct lock_class *class)
650{
651 char usage[LOCK_USAGE_CHARS];
652
653 get_usage_chars(class, usage);
654
655 printk(KERN_CONT " (");
656 __print_lock_name(class);
657 printk(KERN_CONT "){%s}", usage);
658}
659
660static void print_lockdep_cache(struct lockdep_map *lock)
661{
662 const char *name;
663 char str[KSYM_NAME_LEN];
664
665 name = lock->name;
666 if (!name)
667 name = __get_key_name(lock->key->subkeys, str);
668
669 printk(KERN_CONT "%s", name);
670}
671
672static void print_lock(struct held_lock *hlock)
673{
674 /*
675 * We can be called locklessly through debug_show_all_locks() so be
676 * extra careful, the hlock might have been released and cleared.
677 *
678 * If this indeed happens, lets pretend it does not hurt to continue
679 * to print the lock unless the hlock class_idx does not point to a
680 * registered class. The rationale here is: since we don't attempt
681 * to distinguish whether we are in this situation, if it just
682 * happened we can't count on class_idx to tell either.
683 */
684 struct lock_class *lock = hlock_class(hlock);
685
686 if (!lock) {
687 printk(KERN_CONT "<RELEASED>\n");
688 return;
689 }
690
691 printk(KERN_CONT "%px", hlock->instance);
692 print_lock_name(lock);
693 printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
694}
695
696static void lockdep_print_held_locks(struct task_struct *p)
697{
698 int i, depth = READ_ONCE(p->lockdep_depth);
699
700 if (!depth)
701 printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p));
702 else
703 printk("%d lock%s held by %s/%d:\n", depth,
704 depth > 1 ? "s" : "", p->comm, task_pid_nr(p));
705 /*
706 * It's not reliable to print a task's held locks if it's not sleeping
707 * and it's not the current task.
708 */
709 if (p->state == TASK_RUNNING && p != current)
710 return;
711 for (i = 0; i < depth; i++) {
712 printk(" #%d: ", i);
713 print_lock(p->held_locks + i);
714 }
715}
716
717static void print_kernel_ident(void)
718{
719 printk("%s %.*s %s\n", init_utsname()->release,
720 (int)strcspn(init_utsname()->version, " "),
721 init_utsname()->version,
722 print_tainted());
723}
724
725static int very_verbose(struct lock_class *class)
726{
727#if VERY_VERBOSE
728 return class_filter(class);
729#endif
730 return 0;
731}
732
733/*
734 * Is this the address of a static object:
735 */
736#ifdef __KERNEL__
737static int static_obj(const void *obj)
738{
739 unsigned long start = (unsigned long) &_stext,
740 end = (unsigned long) &_end,
741 addr = (unsigned long) obj;
742
743 if (arch_is_kernel_initmem_freed(addr))
744 return 0;
745
746 /*
747 * static variable?
748 */
749 if ((addr >= start) && (addr < end))
750 return 1;
751
752 if (arch_is_kernel_data(addr))
753 return 1;
754
755 /*
756 * in-kernel percpu var?
757 */
758 if (is_kernel_percpu_address(addr))
759 return 1;
760
761 /*
762 * module static or percpu var?
763 */
764 return is_module_address(addr) || is_module_percpu_address(addr);
765}
766#endif
767
768/*
769 * To make lock name printouts unique, we calculate a unique
770 * class->name_version generation counter. The caller must hold the graph
771 * lock.
772 */
773static int count_matching_names(struct lock_class *new_class)
774{
775 struct lock_class *class;
776 int count = 0;
777
778 if (!new_class->name)
779 return 0;
780
781 list_for_each_entry(class, &all_lock_classes, lock_entry) {
782 if (new_class->key - new_class->subclass == class->key)
783 return class->name_version;
784 if (class->name && !strcmp(class->name, new_class->name))
785 count = max(count, class->name_version);
786 }
787
788 return count + 1;
789}
790
791static inline struct lock_class *
792look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
793{
794 struct lockdep_subclass_key *key;
795 struct hlist_head *hash_head;
796 struct lock_class *class;
797
798 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
799 debug_locks_off();
800 printk(KERN_ERR
801 "BUG: looking up invalid subclass: %u\n", subclass);
802 printk(KERN_ERR
803 "turning off the locking correctness validator.\n");
804 dump_stack();
805 return NULL;
806 }
807
808 /*
809 * If it is not initialised then it has never been locked,
810 * so it won't be present in the hash table.
811 */
812 if (unlikely(!lock->key))
813 return NULL;
814
815 /*
816 * NOTE: the class-key must be unique. For dynamic locks, a static
817 * lock_class_key variable is passed in through the mutex_init()
818 * (or spin_lock_init()) call - which acts as the key. For static
819 * locks we use the lock object itself as the key.
820 */
821 BUILD_BUG_ON(sizeof(struct lock_class_key) >
822 sizeof(struct lockdep_map));
823
824 key = lock->key->subkeys + subclass;
825
826 hash_head = classhashentry(key);
827
828 /*
829 * We do an RCU walk of the hash, see lockdep_free_key_range().
830 */
831 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
832 return NULL;
833
834 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
835 if (class->key == key) {
836 /*
837 * Huh! same key, different name? Did someone trample
838 * on some memory? We're most confused.
839 */
840 WARN_ON_ONCE(class->name != lock->name &&
841 lock->key != &__lockdep_no_validate__);
842 return class;
843 }
844 }
845
846 return NULL;
847}
848
849/*
850 * Static locks do not have their class-keys yet - for them the key is
851 * the lock object itself. If the lock is in the per cpu area, the
852 * canonical address of the lock (per cpu offset removed) is used.
853 */
854static bool assign_lock_key(struct lockdep_map *lock)
855{
856 unsigned long can_addr, addr = (unsigned long)lock;
857
858#ifdef __KERNEL__
859 /*
860 * lockdep_free_key_range() assumes that struct lock_class_key
861 * objects do not overlap. Since we use the address of lock
862 * objects as class key for static objects, check whether the
863 * size of lock_class_key objects does not exceed the size of
864 * the smallest lock object.
865 */
866 BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
867#endif
868
869 if (__is_kernel_percpu_address(addr, &can_addr))
870 lock->key = (void *)can_addr;
871 else if (__is_module_percpu_address(addr, &can_addr))
872 lock->key = (void *)can_addr;
873 else if (static_obj(lock))
874 lock->key = (void *)lock;
875 else {
876 /* Debug-check: all keys must be persistent! */
877 debug_locks_off();
878 pr_err("INFO: trying to register non-static key.\n");
879 pr_err("the code is fine but needs lockdep annotation.\n");
880 pr_err("turning off the locking correctness validator.\n");
881 dump_stack();
882 return false;
883 }
884
885 return true;
886}
887
888#ifdef CONFIG_DEBUG_LOCKDEP
889
890/* Check whether element @e occurs in list @h */
891static bool in_list(struct list_head *e, struct list_head *h)
892{
893 struct list_head *f;
894
895 list_for_each(f, h) {
896 if (e == f)
897 return true;
898 }
899
900 return false;
901}
902
903/*
904 * Check whether entry @e occurs in any of the locks_after or locks_before
905 * lists.
906 */
907static bool in_any_class_list(struct list_head *e)
908{
909 struct lock_class *class;
910 int i;
911
912 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
913 class = &lock_classes[i];
914 if (in_list(e, &class->locks_after) ||
915 in_list(e, &class->locks_before))
916 return true;
917 }
918 return false;
919}
920
921static bool class_lock_list_valid(struct lock_class *c, struct list_head *h)
922{
923 struct lock_list *e;
924
925 list_for_each_entry(e, h, entry) {
926 if (e->links_to != c) {
927 printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s",
928 c->name ? : "(?)",
929 (unsigned long)(e - list_entries),
930 e->links_to && e->links_to->name ?
931 e->links_to->name : "(?)",
932 e->class && e->class->name ? e->class->name :
933 "(?)");
934 return false;
935 }
936 }
937 return true;
938}
939
940#ifdef CONFIG_PROVE_LOCKING
941static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
942#endif
943
944static bool check_lock_chain_key(struct lock_chain *chain)
945{
946#ifdef CONFIG_PROVE_LOCKING
947 u64 chain_key = INITIAL_CHAIN_KEY;
948 int i;
949
950 for (i = chain->base; i < chain->base + chain->depth; i++)
951 chain_key = iterate_chain_key(chain_key, chain_hlocks[i]);
952 /*
953 * The 'unsigned long long' casts avoid that a compiler warning
954 * is reported when building tools/lib/lockdep.
955 */
956 if (chain->chain_key != chain_key) {
957 printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n",
958 (unsigned long long)(chain - lock_chains),
959 (unsigned long long)chain->chain_key,
960 (unsigned long long)chain_key);
961 return false;
962 }
963#endif
964 return true;
965}
966
967static bool in_any_zapped_class_list(struct lock_class *class)
968{
969 struct pending_free *pf;
970 int i;
971
972 for (i = 0, pf = delayed_free.pf; i < ARRAY_SIZE(delayed_free.pf); i++, pf++) {
973 if (in_list(&class->lock_entry, &pf->zapped))
974 return true;
975 }
976
977 return false;
978}
979
980static bool __check_data_structures(void)
981{
982 struct lock_class *class;
983 struct lock_chain *chain;
984 struct hlist_head *head;
985 struct lock_list *e;
986 int i;
987
988 /* Check whether all classes occur in a lock list. */
989 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
990 class = &lock_classes[i];
991 if (!in_list(&class->lock_entry, &all_lock_classes) &&
992 !in_list(&class->lock_entry, &free_lock_classes) &&
993 !in_any_zapped_class_list(class)) {
994 printk(KERN_INFO "class %px/%s is not in any class list\n",
995 class, class->name ? : "(?)");
996 return false;
997 }
998 }
999
1000 /* Check whether all classes have valid lock lists. */
1001 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1002 class = &lock_classes[i];
1003 if (!class_lock_list_valid(class, &class->locks_before))
1004 return false;
1005 if (!class_lock_list_valid(class, &class->locks_after))
1006 return false;
1007 }
1008
1009 /* Check the chain_key of all lock chains. */
1010 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
1011 head = chainhash_table + i;
1012 hlist_for_each_entry_rcu(chain, head, entry) {
1013 if (!check_lock_chain_key(chain))
1014 return false;
1015 }
1016 }
1017
1018 /*
1019 * Check whether all list entries that are in use occur in a class
1020 * lock list.
1021 */
1022 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1023 e = list_entries + i;
1024 if (!in_any_class_list(&e->entry)) {
1025 printk(KERN_INFO "list entry %d is not in any class list; class %s <> %s\n",
1026 (unsigned int)(e - list_entries),
1027 e->class->name ? : "(?)",
1028 e->links_to->name ? : "(?)");
1029 return false;
1030 }
1031 }
1032
1033 /*
1034 * Check whether all list entries that are not in use do not occur in
1035 * a class lock list.
1036 */
1037 for_each_clear_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1038 e = list_entries + i;
1039 if (in_any_class_list(&e->entry)) {
1040 printk(KERN_INFO "list entry %d occurs in a class list; class %s <> %s\n",
1041 (unsigned int)(e - list_entries),
1042 e->class && e->class->name ? e->class->name :
1043 "(?)",
1044 e->links_to && e->links_to->name ?
1045 e->links_to->name : "(?)");
1046 return false;
1047 }
1048 }
1049
1050 return true;
1051}
1052
1053int check_consistency = 0;
1054module_param(check_consistency, int, 0644);
1055
1056static void check_data_structures(void)
1057{
1058 static bool once = false;
1059
1060 if (check_consistency && !once) {
1061 if (!__check_data_structures()) {
1062 once = true;
1063 WARN_ON(once);
1064 }
1065 }
1066}
1067
1068#else /* CONFIG_DEBUG_LOCKDEP */
1069
1070static inline void check_data_structures(void) { }
1071
1072#endif /* CONFIG_DEBUG_LOCKDEP */
1073
1074/*
1075 * Initialize the lock_classes[] array elements, the free_lock_classes list
1076 * and also the delayed_free structure.
1077 */
1078static void init_data_structures_once(void)
1079{
1080 static bool ds_initialized, rcu_head_initialized;
1081 int i;
1082
1083 if (likely(rcu_head_initialized))
1084 return;
1085
1086 if (system_state >= SYSTEM_SCHEDULING) {
1087 init_rcu_head(&delayed_free.rcu_head);
1088 rcu_head_initialized = true;
1089 }
1090
1091 if (ds_initialized)
1092 return;
1093
1094 ds_initialized = true;
1095
1096 INIT_LIST_HEAD(&delayed_free.pf[0].zapped);
1097 INIT_LIST_HEAD(&delayed_free.pf[1].zapped);
1098
1099 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1100 list_add_tail(&lock_classes[i].lock_entry, &free_lock_classes);
1101 INIT_LIST_HEAD(&lock_classes[i].locks_after);
1102 INIT_LIST_HEAD(&lock_classes[i].locks_before);
1103 }
1104}
1105
1106static inline struct hlist_head *keyhashentry(const struct lock_class_key *key)
1107{
1108 unsigned long hash = hash_long((uintptr_t)key, KEYHASH_BITS);
1109
1110 return lock_keys_hash + hash;
1111}
1112
1113/* Register a dynamically allocated key. */
1114void lockdep_register_key(struct lock_class_key *key)
1115{
1116 struct hlist_head *hash_head;
1117 struct lock_class_key *k;
1118 unsigned long flags;
1119
1120 if (WARN_ON_ONCE(static_obj(key)))
1121 return;
1122 hash_head = keyhashentry(key);
1123
1124 raw_local_irq_save(flags);
1125 if (!graph_lock())
1126 goto restore_irqs;
1127 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1128 if (WARN_ON_ONCE(k == key))
1129 goto out_unlock;
1130 }
1131 hlist_add_head_rcu(&key->hash_entry, hash_head);
1132out_unlock:
1133 graph_unlock();
1134restore_irqs:
1135 raw_local_irq_restore(flags);
1136}
1137EXPORT_SYMBOL_GPL(lockdep_register_key);
1138
1139/* Check whether a key has been registered as a dynamic key. */
1140static bool is_dynamic_key(const struct lock_class_key *key)
1141{
1142 struct hlist_head *hash_head;
1143 struct lock_class_key *k;
1144 bool found = false;
1145
1146 if (WARN_ON_ONCE(static_obj(key)))
1147 return false;
1148
1149 /*
1150 * If lock debugging is disabled lock_keys_hash[] may contain
1151 * pointers to memory that has already been freed. Avoid triggering
1152 * a use-after-free in that case by returning early.
1153 */
1154 if (!debug_locks)
1155 return true;
1156
1157 hash_head = keyhashentry(key);
1158
1159 rcu_read_lock();
1160 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1161 if (k == key) {
1162 found = true;
1163 break;
1164 }
1165 }
1166 rcu_read_unlock();
1167
1168 return found;
1169}
1170
1171/*
1172 * Register a lock's class in the hash-table, if the class is not present
1173 * yet. Otherwise we look it up. We cache the result in the lock object
1174 * itself, so actual lookup of the hash should be once per lock object.
1175 */
1176static struct lock_class *
1177register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
1178{
1179 struct lockdep_subclass_key *key;
1180 struct hlist_head *hash_head;
1181 struct lock_class *class;
1182
1183 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1184
1185 class = look_up_lock_class(lock, subclass);
1186 if (likely(class))
1187 goto out_set_class_cache;
1188
1189 if (!lock->key) {
1190 if (!assign_lock_key(lock))
1191 return NULL;
1192 } else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) {
1193 return NULL;
1194 }
1195
1196 key = lock->key->subkeys + subclass;
1197 hash_head = classhashentry(key);
1198
1199 if (!graph_lock()) {
1200 return NULL;
1201 }
1202 /*
1203 * We have to do the hash-walk again, to avoid races
1204 * with another CPU:
1205 */
1206 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
1207 if (class->key == key)
1208 goto out_unlock_set;
1209 }
1210
1211 init_data_structures_once();
1212
1213 /* Allocate a new lock class and add it to the hash. */
1214 class = list_first_entry_or_null(&free_lock_classes, typeof(*class),
1215 lock_entry);
1216 if (!class) {
1217 if (!debug_locks_off_graph_unlock()) {
1218 return NULL;
1219 }
1220
1221 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
1222 dump_stack();
1223 return NULL;
1224 }
1225 nr_lock_classes++;
1226 __set_bit(class - lock_classes, lock_classes_in_use);
1227 debug_atomic_inc(nr_unused_locks);
1228 class->key = key;
1229 class->name = lock->name;
1230 class->subclass = subclass;
1231 WARN_ON_ONCE(!list_empty(&class->locks_before));
1232 WARN_ON_ONCE(!list_empty(&class->locks_after));
1233 class->name_version = count_matching_names(class);
1234 /*
1235 * We use RCU's safe list-add method to make
1236 * parallel walking of the hash-list safe:
1237 */
1238 hlist_add_head_rcu(&class->hash_entry, hash_head);
1239 /*
1240 * Remove the class from the free list and add it to the global list
1241 * of classes.
1242 */
1243 list_move_tail(&class->lock_entry, &all_lock_classes);
1244
1245 if (verbose(class)) {
1246 graph_unlock();
1247
1248 printk("\nnew class %px: %s", class->key, class->name);
1249 if (class->name_version > 1)
1250 printk(KERN_CONT "#%d", class->name_version);
1251 printk(KERN_CONT "\n");
1252 dump_stack();
1253
1254 if (!graph_lock()) {
1255 return NULL;
1256 }
1257 }
1258out_unlock_set:
1259 graph_unlock();
1260
1261out_set_class_cache:
1262 if (!subclass || force)
1263 lock->class_cache[0] = class;
1264 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
1265 lock->class_cache[subclass] = class;
1266
1267 /*
1268 * Hash collision, did we smoke some? We found a class with a matching
1269 * hash but the subclass -- which is hashed in -- didn't match.
1270 */
1271 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
1272 return NULL;
1273
1274 return class;
1275}
1276
1277#ifdef CONFIG_PROVE_LOCKING
1278/*
1279 * Allocate a lockdep entry. (assumes the graph_lock held, returns
1280 * with NULL on failure)
1281 */
1282static struct lock_list *alloc_list_entry(void)
1283{
1284 int idx = find_first_zero_bit(list_entries_in_use,
1285 ARRAY_SIZE(list_entries));
1286
1287 if (idx >= ARRAY_SIZE(list_entries)) {
1288 if (!debug_locks_off_graph_unlock())
1289 return NULL;
1290
1291 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
1292 dump_stack();
1293 return NULL;
1294 }
1295 nr_list_entries++;
1296 __set_bit(idx, list_entries_in_use);
1297 return list_entries + idx;
1298}
1299
1300/*
1301 * Add a new dependency to the head of the list:
1302 */
1303static int add_lock_to_list(struct lock_class *this,
1304 struct lock_class *links_to, struct list_head *head,
1305 unsigned long ip, int distance,
1306 const struct lock_trace *trace)
1307{
1308 struct lock_list *entry;
1309 /*
1310 * Lock not present yet - get a new dependency struct and
1311 * add it to the list:
1312 */
1313 entry = alloc_list_entry();
1314 if (!entry)
1315 return 0;
1316
1317 entry->class = this;
1318 entry->links_to = links_to;
1319 entry->distance = distance;
1320 entry->trace = trace;
1321 /*
1322 * Both allocation and removal are done under the graph lock; but
1323 * iteration is under RCU-sched; see look_up_lock_class() and
1324 * lockdep_free_key_range().
1325 */
1326 list_add_tail_rcu(&entry->entry, head);
1327
1328 return 1;
1329}
1330
1331/*
1332 * For good efficiency of modular, we use power of 2
1333 */
1334#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
1335#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
1336
1337/*
1338 * The circular_queue and helpers are used to implement graph
1339 * breadth-first search (BFS) algorithm, by which we can determine
1340 * whether there is a path from a lock to another. In deadlock checks,
1341 * a path from the next lock to be acquired to a previous held lock
1342 * indicates that adding the <prev> -> <next> lock dependency will
1343 * produce a circle in the graph. Breadth-first search instead of
1344 * depth-first search is used in order to find the shortest (circular)
1345 * path.
1346 */
1347struct circular_queue {
1348 struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE];
1349 unsigned int front, rear;
1350};
1351
1352static struct circular_queue lock_cq;
1353
1354unsigned int max_bfs_queue_depth;
1355
1356static unsigned int lockdep_dependency_gen_id;
1357
1358static inline void __cq_init(struct circular_queue *cq)
1359{
1360 cq->front = cq->rear = 0;
1361 lockdep_dependency_gen_id++;
1362}
1363
1364static inline int __cq_empty(struct circular_queue *cq)
1365{
1366 return (cq->front == cq->rear);
1367}
1368
1369static inline int __cq_full(struct circular_queue *cq)
1370{
1371 return ((cq->rear + 1) & CQ_MASK) == cq->front;
1372}
1373
1374static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem)
1375{
1376 if (__cq_full(cq))
1377 return -1;
1378
1379 cq->element[cq->rear] = elem;
1380 cq->rear = (cq->rear + 1) & CQ_MASK;
1381 return 0;
1382}
1383
1384/*
1385 * Dequeue an element from the circular_queue, return a lock_list if
1386 * the queue is not empty, or NULL if otherwise.
1387 */
1388static inline struct lock_list * __cq_dequeue(struct circular_queue *cq)
1389{
1390 struct lock_list * lock;
1391
1392 if (__cq_empty(cq))
1393 return NULL;
1394
1395 lock = cq->element[cq->front];
1396 cq->front = (cq->front + 1) & CQ_MASK;
1397
1398 return lock;
1399}
1400
1401static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
1402{
1403 return (cq->rear - cq->front) & CQ_MASK;
1404}
1405
1406static inline void mark_lock_accessed(struct lock_list *lock,
1407 struct lock_list *parent)
1408{
1409 unsigned long nr;
1410
1411 nr = lock - list_entries;
1412 WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */
1413 lock->parent = parent;
1414 lock->class->dep_gen_id = lockdep_dependency_gen_id;
1415}
1416
1417static inline unsigned long lock_accessed(struct lock_list *lock)
1418{
1419 unsigned long nr;
1420
1421 nr = lock - list_entries;
1422 WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */
1423 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
1424}
1425
1426static inline struct lock_list *get_lock_parent(struct lock_list *child)
1427{
1428 return child->parent;
1429}
1430
1431static inline int get_lock_depth(struct lock_list *child)
1432{
1433 int depth = 0;
1434 struct lock_list *parent;
1435
1436 while ((parent = get_lock_parent(child))) {
1437 child = parent;
1438 depth++;
1439 }
1440 return depth;
1441}
1442
1443/*
1444 * Return the forward or backward dependency list.
1445 *
1446 * @lock: the lock_list to get its class's dependency list
1447 * @offset: the offset to struct lock_class to determine whether it is
1448 * locks_after or locks_before
1449 */
1450static inline struct list_head *get_dep_list(struct lock_list *lock, int offset)
1451{
1452 void *lock_class = lock->class;
1453
1454 return lock_class + offset;
1455}
1456
1457/*
1458 * Forward- or backward-dependency search, used for both circular dependency
1459 * checking and hardirq-unsafe/softirq-unsafe checking.
1460 */
1461static int __bfs(struct lock_list *source_entry,
1462 void *data,
1463 int (*match)(struct lock_list *entry, void *data),
1464 struct lock_list **target_entry,
1465 int offset)
1466{
1467 struct lock_list *entry;
1468 struct lock_list *lock;
1469 struct list_head *head;
1470 struct circular_queue *cq = &lock_cq;
1471 int ret = 1;
1472
1473 if (match(source_entry, data)) {
1474 *target_entry = source_entry;
1475 ret = 0;
1476 goto exit;
1477 }
1478
1479 head = get_dep_list(source_entry, offset);
1480 if (list_empty(head))
1481 goto exit;
1482
1483 __cq_init(cq);
1484 __cq_enqueue(cq, source_entry);
1485
1486 while ((lock = __cq_dequeue(cq))) {
1487
1488 if (!lock->class) {
1489 ret = -2;
1490 goto exit;
1491 }
1492
1493 head = get_dep_list(lock, offset);
1494
1495 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1496
1497 list_for_each_entry_rcu(entry, head, entry) {
1498 if (!lock_accessed(entry)) {
1499 unsigned int cq_depth;
1500 mark_lock_accessed(entry, lock);
1501 if (match(entry, data)) {
1502 *target_entry = entry;
1503 ret = 0;
1504 goto exit;
1505 }
1506
1507 if (__cq_enqueue(cq, entry)) {
1508 ret = -1;
1509 goto exit;
1510 }
1511 cq_depth = __cq_get_elem_count(cq);
1512 if (max_bfs_queue_depth < cq_depth)
1513 max_bfs_queue_depth = cq_depth;
1514 }
1515 }
1516 }
1517exit:
1518 return ret;
1519}
1520
1521static inline int __bfs_forwards(struct lock_list *src_entry,
1522 void *data,
1523 int (*match)(struct lock_list *entry, void *data),
1524 struct lock_list **target_entry)
1525{
1526 return __bfs(src_entry, data, match, target_entry,
1527 offsetof(struct lock_class, locks_after));
1528
1529}
1530
1531static inline int __bfs_backwards(struct lock_list *src_entry,
1532 void *data,
1533 int (*match)(struct lock_list *entry, void *data),
1534 struct lock_list **target_entry)
1535{
1536 return __bfs(src_entry, data, match, target_entry,
1537 offsetof(struct lock_class, locks_before));
1538
1539}
1540
1541static void print_lock_trace(const struct lock_trace *trace,
1542 unsigned int spaces)
1543{
1544 stack_trace_print(trace->entries, trace->nr_entries, spaces);
1545}
1546
1547/*
1548 * Print a dependency chain entry (this is only done when a deadlock
1549 * has been detected):
1550 */
1551static noinline void
1552print_circular_bug_entry(struct lock_list *target, int depth)
1553{
1554 if (debug_locks_silent)
1555 return;
1556 printk("\n-> #%u", depth);
1557 print_lock_name(target->class);
1558 printk(KERN_CONT ":\n");
1559 print_lock_trace(target->trace, 6);
1560}
1561
1562static void
1563print_circular_lock_scenario(struct held_lock *src,
1564 struct held_lock *tgt,
1565 struct lock_list *prt)
1566{
1567 struct lock_class *source = hlock_class(src);
1568 struct lock_class *target = hlock_class(tgt);
1569 struct lock_class *parent = prt->class;
1570
1571 /*
1572 * A direct locking problem where unsafe_class lock is taken
1573 * directly by safe_class lock, then all we need to show
1574 * is the deadlock scenario, as it is obvious that the
1575 * unsafe lock is taken under the safe lock.
1576 *
1577 * But if there is a chain instead, where the safe lock takes
1578 * an intermediate lock (middle_class) where this lock is
1579 * not the same as the safe lock, then the lock chain is
1580 * used to describe the problem. Otherwise we would need
1581 * to show a different CPU case for each link in the chain
1582 * from the safe_class lock to the unsafe_class lock.
1583 */
1584 if (parent != source) {
1585 printk("Chain exists of:\n ");
1586 __print_lock_name(source);
1587 printk(KERN_CONT " --> ");
1588 __print_lock_name(parent);
1589 printk(KERN_CONT " --> ");
1590 __print_lock_name(target);
1591 printk(KERN_CONT "\n\n");
1592 }
1593
1594 printk(" Possible unsafe locking scenario:\n\n");
1595 printk(" CPU0 CPU1\n");
1596 printk(" ---- ----\n");
1597 printk(" lock(");
1598 __print_lock_name(target);
1599 printk(KERN_CONT ");\n");
1600 printk(" lock(");
1601 __print_lock_name(parent);
1602 printk(KERN_CONT ");\n");
1603 printk(" lock(");
1604 __print_lock_name(target);
1605 printk(KERN_CONT ");\n");
1606 printk(" lock(");
1607 __print_lock_name(source);
1608 printk(KERN_CONT ");\n");
1609 printk("\n *** DEADLOCK ***\n\n");
1610}
1611
1612/*
1613 * When a circular dependency is detected, print the
1614 * header first:
1615 */
1616static noinline void
1617print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1618 struct held_lock *check_src,
1619 struct held_lock *check_tgt)
1620{
1621 struct task_struct *curr = current;
1622
1623 if (debug_locks_silent)
1624 return;
1625
1626 pr_warn("\n");
1627 pr_warn("======================================================\n");
1628 pr_warn("WARNING: possible circular locking dependency detected\n");
1629 print_kernel_ident();
1630 pr_warn("------------------------------------------------------\n");
1631 pr_warn("%s/%d is trying to acquire lock:\n",
1632 curr->comm, task_pid_nr(curr));
1633 print_lock(check_src);
1634
1635 pr_warn("\nbut task is already holding lock:\n");
1636
1637 print_lock(check_tgt);
1638 pr_warn("\nwhich lock already depends on the new lock.\n\n");
1639 pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1640
1641 print_circular_bug_entry(entry, depth);
1642}
1643
1644static inline int class_equal(struct lock_list *entry, void *data)
1645{
1646 return entry->class == data;
1647}
1648
1649static noinline void print_circular_bug(struct lock_list *this,
1650 struct lock_list *target,
1651 struct held_lock *check_src,
1652 struct held_lock *check_tgt)
1653{
1654 struct task_struct *curr = current;
1655 struct lock_list *parent;
1656 struct lock_list *first_parent;
1657 int depth;
1658
1659 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1660 return;
1661
1662 this->trace = save_trace();
1663 if (!this->trace)
1664 return;
1665
1666 depth = get_lock_depth(target);
1667
1668 print_circular_bug_header(target, depth, check_src, check_tgt);
1669
1670 parent = get_lock_parent(target);
1671 first_parent = parent;
1672
1673 while (parent) {
1674 print_circular_bug_entry(parent, --depth);
1675 parent = get_lock_parent(parent);
1676 }
1677
1678 printk("\nother info that might help us debug this:\n\n");
1679 print_circular_lock_scenario(check_src, check_tgt,
1680 first_parent);
1681
1682 lockdep_print_held_locks(curr);
1683
1684 printk("\nstack backtrace:\n");
1685 dump_stack();
1686}
1687
1688static noinline void print_bfs_bug(int ret)
1689{
1690 if (!debug_locks_off_graph_unlock())
1691 return;
1692
1693 /*
1694 * Breadth-first-search failed, graph got corrupted?
1695 */
1696 WARN(1, "lockdep bfs error:%d\n", ret);
1697}
1698
1699static int noop_count(struct lock_list *entry, void *data)
1700{
1701 (*(unsigned long *)data)++;
1702 return 0;
1703}
1704
1705static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1706{
1707 unsigned long count = 0;
1708 struct lock_list *uninitialized_var(target_entry);
1709
1710 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1711
1712 return count;
1713}
1714unsigned long lockdep_count_forward_deps(struct lock_class *class)
1715{
1716 unsigned long ret, flags;
1717 struct lock_list this;
1718
1719 this.parent = NULL;
1720 this.class = class;
1721
1722 raw_local_irq_save(flags);
1723 arch_spin_lock(&lockdep_lock);
1724 ret = __lockdep_count_forward_deps(&this);
1725 arch_spin_unlock(&lockdep_lock);
1726 raw_local_irq_restore(flags);
1727
1728 return ret;
1729}
1730
1731static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1732{
1733 unsigned long count = 0;
1734 struct lock_list *uninitialized_var(target_entry);
1735
1736 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1737
1738 return count;
1739}
1740
1741unsigned long lockdep_count_backward_deps(struct lock_class *class)
1742{
1743 unsigned long ret, flags;
1744 struct lock_list this;
1745
1746 this.parent = NULL;
1747 this.class = class;
1748
1749 raw_local_irq_save(flags);
1750 arch_spin_lock(&lockdep_lock);
1751 ret = __lockdep_count_backward_deps(&this);
1752 arch_spin_unlock(&lockdep_lock);
1753 raw_local_irq_restore(flags);
1754
1755 return ret;
1756}
1757
1758/*
1759 * Check that the dependency graph starting at <src> can lead to
1760 * <target> or not. Print an error and return 0 if it does.
1761 */
1762static noinline int
1763check_path(struct lock_class *target, struct lock_list *src_entry,
1764 struct lock_list **target_entry)
1765{
1766 int ret;
1767
1768 ret = __bfs_forwards(src_entry, (void *)target, class_equal,
1769 target_entry);
1770
1771 if (unlikely(ret < 0))
1772 print_bfs_bug(ret);
1773
1774 return ret;
1775}
1776
1777/*
1778 * Prove that the dependency graph starting at <src> can not
1779 * lead to <target>. If it can, there is a circle when adding
1780 * <target> -> <src> dependency.
1781 *
1782 * Print an error and return 0 if it does.
1783 */
1784static noinline int
1785check_noncircular(struct held_lock *src, struct held_lock *target,
1786 struct lock_trace **const trace)
1787{
1788 int ret;
1789 struct lock_list *uninitialized_var(target_entry);
1790 struct lock_list src_entry = {
1791 .class = hlock_class(src),
1792 .parent = NULL,
1793 };
1794
1795 debug_atomic_inc(nr_cyclic_checks);
1796
1797 ret = check_path(hlock_class(target), &src_entry, &target_entry);
1798
1799 if (unlikely(!ret)) {
1800 if (!*trace) {
1801 /*
1802 * If save_trace fails here, the printing might
1803 * trigger a WARN but because of the !nr_entries it
1804 * should not do bad things.
1805 */
1806 *trace = save_trace();
1807 }
1808
1809 print_circular_bug(&src_entry, target_entry, src, target);
1810 }
1811
1812 return ret;
1813}
1814
1815#ifdef CONFIG_LOCKDEP_SMALL
1816/*
1817 * Check that the dependency graph starting at <src> can lead to
1818 * <target> or not. If it can, <src> -> <target> dependency is already
1819 * in the graph.
1820 *
1821 * Print an error and return 2 if it does or 1 if it does not.
1822 */
1823static noinline int
1824check_redundant(struct held_lock *src, struct held_lock *target)
1825{
1826 int ret;
1827 struct lock_list *uninitialized_var(target_entry);
1828 struct lock_list src_entry = {
1829 .class = hlock_class(src),
1830 .parent = NULL,
1831 };
1832
1833 debug_atomic_inc(nr_redundant_checks);
1834
1835 ret = check_path(hlock_class(target), &src_entry, &target_entry);
1836
1837 if (!ret) {
1838 debug_atomic_inc(nr_redundant);
1839 ret = 2;
1840 } else if (ret < 0)
1841 ret = 0;
1842
1843 return ret;
1844}
1845#endif
1846
1847#ifdef CONFIG_TRACE_IRQFLAGS
1848
1849static inline int usage_accumulate(struct lock_list *entry, void *mask)
1850{
1851 *(unsigned long *)mask |= entry->class->usage_mask;
1852
1853 return 0;
1854}
1855
1856/*
1857 * Forwards and backwards subgraph searching, for the purposes of
1858 * proving that two subgraphs can be connected by a new dependency
1859 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1860 */
1861
1862static inline int usage_match(struct lock_list *entry, void *mask)
1863{
1864 return entry->class->usage_mask & *(unsigned long *)mask;
1865}
1866
1867/*
1868 * Find a node in the forwards-direction dependency sub-graph starting
1869 * at @root->class that matches @bit.
1870 *
1871 * Return 0 if such a node exists in the subgraph, and put that node
1872 * into *@target_entry.
1873 *
1874 * Return 1 otherwise and keep *@target_entry unchanged.
1875 * Return <0 on error.
1876 */
1877static int
1878find_usage_forwards(struct lock_list *root, unsigned long usage_mask,
1879 struct lock_list **target_entry)
1880{
1881 int result;
1882
1883 debug_atomic_inc(nr_find_usage_forwards_checks);
1884
1885 result = __bfs_forwards(root, &usage_mask, usage_match, target_entry);
1886
1887 return result;
1888}
1889
1890/*
1891 * Find a node in the backwards-direction dependency sub-graph starting
1892 * at @root->class that matches @bit.
1893 *
1894 * Return 0 if such a node exists in the subgraph, and put that node
1895 * into *@target_entry.
1896 *
1897 * Return 1 otherwise and keep *@target_entry unchanged.
1898 * Return <0 on error.
1899 */
1900static int
1901find_usage_backwards(struct lock_list *root, unsigned long usage_mask,
1902 struct lock_list **target_entry)
1903{
1904 int result;
1905
1906 debug_atomic_inc(nr_find_usage_backwards_checks);
1907
1908 result = __bfs_backwards(root, &usage_mask, usage_match, target_entry);
1909
1910 return result;
1911}
1912
1913static void print_lock_class_header(struct lock_class *class, int depth)
1914{
1915 int bit;
1916
1917 printk("%*s->", depth, "");
1918 print_lock_name(class);
1919#ifdef CONFIG_DEBUG_LOCKDEP
1920 printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
1921#endif
1922 printk(KERN_CONT " {\n");
1923
1924 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1925 if (class->usage_mask & (1 << bit)) {
1926 int len = depth;
1927
1928 len += printk("%*s %s", depth, "", usage_str[bit]);
1929 len += printk(KERN_CONT " at:\n");
1930 print_lock_trace(class->usage_traces[bit], len);
1931 }
1932 }
1933 printk("%*s }\n", depth, "");
1934
1935 printk("%*s ... key at: [<%px>] %pS\n",
1936 depth, "", class->key, class->key);
1937}
1938
1939/*
1940 * printk the shortest lock dependencies from @start to @end in reverse order:
1941 */
1942static void __used
1943print_shortest_lock_dependencies(struct lock_list *leaf,
1944 struct lock_list *root)
1945{
1946 struct lock_list *entry = leaf;
1947 int depth;
1948
1949 /*compute depth from generated tree by BFS*/
1950 depth = get_lock_depth(leaf);
1951
1952 do {
1953 print_lock_class_header(entry->class, depth);
1954 printk("%*s ... acquired at:\n", depth, "");
1955 print_lock_trace(entry->trace, 2);
1956 printk("\n");
1957
1958 if (depth == 0 && (entry != root)) {
1959 printk("lockdep:%s bad path found in chain graph\n", __func__);
1960 break;
1961 }
1962
1963 entry = get_lock_parent(entry);
1964 depth--;
1965 } while (entry && (depth >= 0));
1966}
1967
1968static void
1969print_irq_lock_scenario(struct lock_list *safe_entry,
1970 struct lock_list *unsafe_entry,
1971 struct lock_class *prev_class,
1972 struct lock_class *next_class)
1973{
1974 struct lock_class *safe_class = safe_entry->class;
1975 struct lock_class *unsafe_class = unsafe_entry->class;
1976 struct lock_class *middle_class = prev_class;
1977
1978 if (middle_class == safe_class)
1979 middle_class = next_class;
1980
1981 /*
1982 * A direct locking problem where unsafe_class lock is taken
1983 * directly by safe_class lock, then all we need to show
1984 * is the deadlock scenario, as it is obvious that the
1985 * unsafe lock is taken under the safe lock.
1986 *
1987 * But if there is a chain instead, where the safe lock takes
1988 * an intermediate lock (middle_class) where this lock is
1989 * not the same as the safe lock, then the lock chain is
1990 * used to describe the problem. Otherwise we would need
1991 * to show a different CPU case for each link in the chain
1992 * from the safe_class lock to the unsafe_class lock.
1993 */
1994 if (middle_class != unsafe_class) {
1995 printk("Chain exists of:\n ");
1996 __print_lock_name(safe_class);
1997 printk(KERN_CONT " --> ");
1998 __print_lock_name(middle_class);
1999 printk(KERN_CONT " --> ");
2000 __print_lock_name(unsafe_class);
2001 printk(KERN_CONT "\n\n");
2002 }
2003
2004 printk(" Possible interrupt unsafe locking scenario:\n\n");
2005 printk(" CPU0 CPU1\n");
2006 printk(" ---- ----\n");
2007 printk(" lock(");
2008 __print_lock_name(unsafe_class);
2009 printk(KERN_CONT ");\n");
2010 printk(" local_irq_disable();\n");
2011 printk(" lock(");
2012 __print_lock_name(safe_class);
2013 printk(KERN_CONT ");\n");
2014 printk(" lock(");
2015 __print_lock_name(middle_class);
2016 printk(KERN_CONT ");\n");
2017 printk(" <Interrupt>\n");
2018 printk(" lock(");
2019 __print_lock_name(safe_class);
2020 printk(KERN_CONT ");\n");
2021 printk("\n *** DEADLOCK ***\n\n");
2022}
2023
2024static void
2025print_bad_irq_dependency(struct task_struct *curr,
2026 struct lock_list *prev_root,
2027 struct lock_list *next_root,
2028 struct lock_list *backwards_entry,
2029 struct lock_list *forwards_entry,
2030 struct held_lock *prev,
2031 struct held_lock *next,
2032 enum lock_usage_bit bit1,
2033 enum lock_usage_bit bit2,
2034 const char *irqclass)
2035{
2036 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2037 return;
2038
2039 pr_warn("\n");
2040 pr_warn("=====================================================\n");
2041 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
2042 irqclass, irqclass);
2043 print_kernel_ident();
2044 pr_warn("-----------------------------------------------------\n");
2045 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
2046 curr->comm, task_pid_nr(curr),
2047 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
2048 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
2049 curr->hardirqs_enabled,
2050 curr->softirqs_enabled);
2051 print_lock(next);
2052
2053 pr_warn("\nand this task is already holding:\n");
2054 print_lock(prev);
2055 pr_warn("which would create a new lock dependency:\n");
2056 print_lock_name(hlock_class(prev));
2057 pr_cont(" ->");
2058 print_lock_name(hlock_class(next));
2059 pr_cont("\n");
2060
2061 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
2062 irqclass);
2063 print_lock_name(backwards_entry->class);
2064 pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
2065
2066 print_lock_trace(backwards_entry->class->usage_traces[bit1], 1);
2067
2068 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
2069 print_lock_name(forwards_entry->class);
2070 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
2071 pr_warn("...");
2072
2073 print_lock_trace(forwards_entry->class->usage_traces[bit2], 1);
2074
2075 pr_warn("\nother info that might help us debug this:\n\n");
2076 print_irq_lock_scenario(backwards_entry, forwards_entry,
2077 hlock_class(prev), hlock_class(next));
2078
2079 lockdep_print_held_locks(curr);
2080
2081 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
2082 prev_root->trace = save_trace();
2083 if (!prev_root->trace)
2084 return;
2085 print_shortest_lock_dependencies(backwards_entry, prev_root);
2086
2087 pr_warn("\nthe dependencies between the lock to be acquired");
2088 pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
2089 next_root->trace = save_trace();
2090 if (!next_root->trace)
2091 return;
2092 print_shortest_lock_dependencies(forwards_entry, next_root);
2093
2094 pr_warn("\nstack backtrace:\n");
2095 dump_stack();
2096}
2097
2098static const char *state_names[] = {
2099#define LOCKDEP_STATE(__STATE) \
2100 __stringify(__STATE),
2101#include "lockdep_states.h"
2102#undef LOCKDEP_STATE
2103};
2104
2105static const char *state_rnames[] = {
2106#define LOCKDEP_STATE(__STATE) \
2107 __stringify(__STATE)"-READ",
2108#include "lockdep_states.h"
2109#undef LOCKDEP_STATE
2110};
2111
2112static inline const char *state_name(enum lock_usage_bit bit)
2113{
2114 if (bit & LOCK_USAGE_READ_MASK)
2115 return state_rnames[bit >> LOCK_USAGE_DIR_MASK];
2116 else
2117 return state_names[bit >> LOCK_USAGE_DIR_MASK];
2118}
2119
2120/*
2121 * The bit number is encoded like:
2122 *
2123 * bit0: 0 exclusive, 1 read lock
2124 * bit1: 0 used in irq, 1 irq enabled
2125 * bit2-n: state
2126 */
2127static int exclusive_bit(int new_bit)
2128{
2129 int state = new_bit & LOCK_USAGE_STATE_MASK;
2130 int dir = new_bit & LOCK_USAGE_DIR_MASK;
2131
2132 /*
2133 * keep state, bit flip the direction and strip read.
2134 */
2135 return state | (dir ^ LOCK_USAGE_DIR_MASK);
2136}
2137
2138/*
2139 * Observe that when given a bitmask where each bitnr is encoded as above, a
2140 * right shift of the mask transforms the individual bitnrs as -1 and
2141 * conversely, a left shift transforms into +1 for the individual bitnrs.
2142 *
2143 * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can
2144 * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0)
2145 * instead by subtracting the bit number by 2, or shifting the mask right by 2.
2146 *
2147 * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2.
2148 *
2149 * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is
2150 * all bits set) and recompose with bitnr1 flipped.
2151 */
2152static unsigned long invert_dir_mask(unsigned long mask)
2153{
2154 unsigned long excl = 0;
2155
2156 /* Invert dir */
2157 excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK;
2158 excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK;
2159
2160 return excl;
2161}
2162
2163/*
2164 * As above, we clear bitnr0 (LOCK_*_READ off) with bitmask ops. First, for all
2165 * bits with bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*).
2166 * And then mask out all bitnr0.
2167 */
2168static unsigned long exclusive_mask(unsigned long mask)
2169{
2170 unsigned long excl = invert_dir_mask(mask);
2171
2172 /* Strip read */
2173 excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
2174 excl &= ~LOCKF_IRQ_READ;
2175
2176 return excl;
2177}
2178
2179/*
2180 * Retrieve the _possible_ original mask to which @mask is
2181 * exclusive. Ie: this is the opposite of exclusive_mask().
2182 * Note that 2 possible original bits can match an exclusive
2183 * bit: one has LOCK_USAGE_READ_MASK set, the other has it
2184 * cleared. So both are returned for each exclusive bit.
2185 */
2186static unsigned long original_mask(unsigned long mask)
2187{
2188 unsigned long excl = invert_dir_mask(mask);
2189
2190 /* Include read in existing usages */
2191 excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
2192
2193 return excl;
2194}
2195
2196/*
2197 * Find the first pair of bit match between an original
2198 * usage mask and an exclusive usage mask.
2199 */
2200static int find_exclusive_match(unsigned long mask,
2201 unsigned long excl_mask,
2202 enum lock_usage_bit *bitp,
2203 enum lock_usage_bit *excl_bitp)
2204{
2205 int bit, excl;
2206
2207 for_each_set_bit(bit, &mask, LOCK_USED) {
2208 excl = exclusive_bit(bit);
2209 if (excl_mask & lock_flag(excl)) {
2210 *bitp = bit;
2211 *excl_bitp = excl;
2212 return 0;
2213 }
2214 }
2215 return -1;
2216}
2217
2218/*
2219 * Prove that the new dependency does not connect a hardirq-safe(-read)
2220 * lock with a hardirq-unsafe lock - to achieve this we search
2221 * the backwards-subgraph starting at <prev>, and the
2222 * forwards-subgraph starting at <next>:
2223 */
2224static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
2225 struct held_lock *next)
2226{
2227 unsigned long usage_mask = 0, forward_mask, backward_mask;
2228 enum lock_usage_bit forward_bit = 0, backward_bit = 0;
2229 struct lock_list *uninitialized_var(target_entry1);
2230 struct lock_list *uninitialized_var(target_entry);
2231 struct lock_list this, that;
2232 int ret;
2233
2234 /*
2235 * Step 1: gather all hard/soft IRQs usages backward in an
2236 * accumulated usage mask.
2237 */
2238 this.parent = NULL;
2239 this.class = hlock_class(prev);
2240
2241 ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL);
2242 if (ret < 0) {
2243 print_bfs_bug(ret);
2244 return 0;
2245 }
2246
2247 usage_mask &= LOCKF_USED_IN_IRQ_ALL;
2248 if (!usage_mask)
2249 return 1;
2250
2251 /*
2252 * Step 2: find exclusive uses forward that match the previous
2253 * backward accumulated mask.
2254 */
2255 forward_mask = exclusive_mask(usage_mask);
2256
2257 that.parent = NULL;
2258 that.class = hlock_class(next);
2259
2260 ret = find_usage_forwards(&that, forward_mask, &target_entry1);
2261 if (ret < 0) {
2262 print_bfs_bug(ret);
2263 return 0;
2264 }
2265 if (ret == 1)
2266 return ret;
2267
2268 /*
2269 * Step 3: we found a bad match! Now retrieve a lock from the backward
2270 * list whose usage mask matches the exclusive usage mask from the
2271 * lock found on the forward list.
2272 */
2273 backward_mask = original_mask(target_entry1->class->usage_mask);
2274
2275 ret = find_usage_backwards(&this, backward_mask, &target_entry);
2276 if (ret < 0) {
2277 print_bfs_bug(ret);
2278 return 0;
2279 }
2280 if (DEBUG_LOCKS_WARN_ON(ret == 1))
2281 return 1;
2282
2283 /*
2284 * Step 4: narrow down to a pair of incompatible usage bits
2285 * and report it.
2286 */
2287 ret = find_exclusive_match(target_entry->class->usage_mask,
2288 target_entry1->class->usage_mask,
2289 &backward_bit, &forward_bit);
2290 if (DEBUG_LOCKS_WARN_ON(ret == -1))
2291 return 1;
2292
2293 print_bad_irq_dependency(curr, &this, &that,
2294 target_entry, target_entry1,
2295 prev, next,
2296 backward_bit, forward_bit,
2297 state_name(backward_bit));
2298
2299 return 0;
2300}
2301
2302static void inc_chains(void)
2303{
2304 if (current->hardirq_context)
2305 nr_hardirq_chains++;
2306 else {
2307 if (current->softirq_context)
2308 nr_softirq_chains++;
2309 else
2310 nr_process_chains++;
2311 }
2312}
2313
2314#else
2315
2316static inline int check_irq_usage(struct task_struct *curr,
2317 struct held_lock *prev, struct held_lock *next)
2318{
2319 return 1;
2320}
2321
2322static inline void inc_chains(void)
2323{
2324 nr_process_chains++;
2325}
2326
2327#endif /* CONFIG_TRACE_IRQFLAGS */
2328
2329static void
2330print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
2331{
2332 struct lock_class *next = hlock_class(nxt);
2333 struct lock_class *prev = hlock_class(prv);
2334
2335 printk(" Possible unsafe locking scenario:\n\n");
2336 printk(" CPU0\n");
2337 printk(" ----\n");
2338 printk(" lock(");
2339 __print_lock_name(prev);
2340 printk(KERN_CONT ");\n");
2341 printk(" lock(");
2342 __print_lock_name(next);
2343 printk(KERN_CONT ");\n");
2344 printk("\n *** DEADLOCK ***\n\n");
2345 printk(" May be due to missing lock nesting notation\n\n");
2346}
2347
2348static void
2349print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
2350 struct held_lock *next)
2351{
2352 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2353 return;
2354
2355 pr_warn("\n");
2356 pr_warn("============================================\n");
2357 pr_warn("WARNING: possible recursive locking detected\n");
2358 print_kernel_ident();
2359 pr_warn("--------------------------------------------\n");
2360 pr_warn("%s/%d is trying to acquire lock:\n",
2361 curr->comm, task_pid_nr(curr));
2362 print_lock(next);
2363 pr_warn("\nbut task is already holding lock:\n");
2364 print_lock(prev);
2365
2366 pr_warn("\nother info that might help us debug this:\n");
2367 print_deadlock_scenario(next, prev);
2368 lockdep_print_held_locks(curr);
2369
2370 pr_warn("\nstack backtrace:\n");
2371 dump_stack();
2372}
2373
2374/*
2375 * Check whether we are holding such a class already.
2376 *
2377 * (Note that this has to be done separately, because the graph cannot
2378 * detect such classes of deadlocks.)
2379 *
2380 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
2381 */
2382static int
2383check_deadlock(struct task_struct *curr, struct held_lock *next)
2384{
2385 struct held_lock *prev;
2386 struct held_lock *nest = NULL;
2387 int i;
2388
2389 for (i = 0; i < curr->lockdep_depth; i++) {
2390 prev = curr->held_locks + i;
2391
2392 if (prev->instance == next->nest_lock)
2393 nest = prev;
2394
2395 if (hlock_class(prev) != hlock_class(next))
2396 continue;
2397
2398 /*
2399 * Allow read-after-read recursion of the same
2400 * lock class (i.e. read_lock(lock)+read_lock(lock)):
2401 */
2402 if ((next->read == 2) && prev->read)
2403 return 2;
2404
2405 /*
2406 * We're holding the nest_lock, which serializes this lock's
2407 * nesting behaviour.
2408 */
2409 if (nest)
2410 return 2;
2411
2412 print_deadlock_bug(curr, prev, next);
2413 return 0;
2414 }
2415 return 1;
2416}
2417
2418/*
2419 * There was a chain-cache miss, and we are about to add a new dependency
2420 * to a previous lock. We validate the following rules:
2421 *
2422 * - would the adding of the <prev> -> <next> dependency create a
2423 * circular dependency in the graph? [== circular deadlock]
2424 *
2425 * - does the new prev->next dependency connect any hardirq-safe lock
2426 * (in the full backwards-subgraph starting at <prev>) with any
2427 * hardirq-unsafe lock (in the full forwards-subgraph starting at
2428 * <next>)? [== illegal lock inversion with hardirq contexts]
2429 *
2430 * - does the new prev->next dependency connect any softirq-safe lock
2431 * (in the full backwards-subgraph starting at <prev>) with any
2432 * softirq-unsafe lock (in the full forwards-subgraph starting at
2433 * <next>)? [== illegal lock inversion with softirq contexts]
2434 *
2435 * any of these scenarios could lead to a deadlock.
2436 *
2437 * Then if all the validations pass, we add the forwards and backwards
2438 * dependency.
2439 */
2440static int
2441check_prev_add(struct task_struct *curr, struct held_lock *prev,
2442 struct held_lock *next, int distance,
2443 struct lock_trace **const trace)
2444{
2445 struct lock_list *entry;
2446 int ret;
2447
2448 if (!hlock_class(prev)->key || !hlock_class(next)->key) {
2449 /*
2450 * The warning statements below may trigger a use-after-free
2451 * of the class name. It is better to trigger a use-after free
2452 * and to have the class name most of the time instead of not
2453 * having the class name available.
2454 */
2455 WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key,
2456 "Detected use-after-free of lock class %px/%s\n",
2457 hlock_class(prev),
2458 hlock_class(prev)->name);
2459 WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key,
2460 "Detected use-after-free of lock class %px/%s\n",
2461 hlock_class(next),
2462 hlock_class(next)->name);
2463 return 2;
2464 }
2465
2466 /*
2467 * Prove that the new <prev> -> <next> dependency would not
2468 * create a circular dependency in the graph. (We do this by
2469 * a breadth-first search into the graph starting at <next>,
2470 * and check whether we can reach <prev>.)
2471 *
2472 * The search is limited by the size of the circular queue (i.e.,
2473 * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes
2474 * in the graph whose neighbours are to be checked.
2475 */
2476 ret = check_noncircular(next, prev, trace);
2477 if (unlikely(ret <= 0))
2478 return 0;
2479
2480 if (!check_irq_usage(curr, prev, next))
2481 return 0;
2482
2483 /*
2484 * For recursive read-locks we do all the dependency checks,
2485 * but we dont store read-triggered dependencies (only
2486 * write-triggered dependencies). This ensures that only the
2487 * write-side dependencies matter, and that if for example a
2488 * write-lock never takes any other locks, then the reads are
2489 * equivalent to a NOP.
2490 */
2491 if (next->read == 2 || prev->read == 2)
2492 return 1;
2493 /*
2494 * Is the <prev> -> <next> dependency already present?
2495 *
2496 * (this may occur even though this is a new chain: consider
2497 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
2498 * chains - the second one will be new, but L1 already has
2499 * L2 added to its dependency list, due to the first chain.)
2500 */
2501 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
2502 if (entry->class == hlock_class(next)) {
2503 if (distance == 1)
2504 entry->distance = 1;
2505 return 1;
2506 }
2507 }
2508
2509#ifdef CONFIG_LOCKDEP_SMALL
2510 /*
2511 * Is the <prev> -> <next> link redundant?
2512 */
2513 ret = check_redundant(prev, next);
2514 if (ret != 1)
2515 return ret;
2516#endif
2517
2518 if (!*trace) {
2519 *trace = save_trace();
2520 if (!*trace)
2521 return 0;
2522 }
2523
2524 /*
2525 * Ok, all validations passed, add the new lock
2526 * to the previous lock's dependency list:
2527 */
2528 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
2529 &hlock_class(prev)->locks_after,
2530 next->acquire_ip, distance, *trace);
2531
2532 if (!ret)
2533 return 0;
2534
2535 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
2536 &hlock_class(next)->locks_before,
2537 next->acquire_ip, distance, *trace);
2538 if (!ret)
2539 return 0;
2540
2541 return 2;
2542}
2543
2544/*
2545 * Add the dependency to all directly-previous locks that are 'relevant'.
2546 * The ones that are relevant are (in increasing distance from curr):
2547 * all consecutive trylock entries and the final non-trylock entry - or
2548 * the end of this context's lock-chain - whichever comes first.
2549 */
2550static int
2551check_prevs_add(struct task_struct *curr, struct held_lock *next)
2552{
2553 struct lock_trace *trace = NULL;
2554 int depth = curr->lockdep_depth;
2555 struct held_lock *hlock;
2556
2557 /*
2558 * Debugging checks.
2559 *
2560 * Depth must not be zero for a non-head lock:
2561 */
2562 if (!depth)
2563 goto out_bug;
2564 /*
2565 * At least two relevant locks must exist for this
2566 * to be a head:
2567 */
2568 if (curr->held_locks[depth].irq_context !=
2569 curr->held_locks[depth-1].irq_context)
2570 goto out_bug;
2571
2572 for (;;) {
2573 int distance = curr->lockdep_depth - depth + 1;
2574 hlock = curr->held_locks + depth - 1;
2575
2576 /*
2577 * Only non-recursive-read entries get new dependencies
2578 * added:
2579 */
2580 if (hlock->read != 2 && hlock->check) {
2581 int ret = check_prev_add(curr, hlock, next, distance,
2582 &trace);
2583 if (!ret)
2584 return 0;
2585
2586 /*
2587 * Stop after the first non-trylock entry,
2588 * as non-trylock entries have added their
2589 * own direct dependencies already, so this
2590 * lock is connected to them indirectly:
2591 */
2592 if (!hlock->trylock)
2593 break;
2594 }
2595
2596 depth--;
2597 /*
2598 * End of lock-stack?
2599 */
2600 if (!depth)
2601 break;
2602 /*
2603 * Stop the search if we cross into another context:
2604 */
2605 if (curr->held_locks[depth].irq_context !=
2606 curr->held_locks[depth-1].irq_context)
2607 break;
2608 }
2609 return 1;
2610out_bug:
2611 if (!debug_locks_off_graph_unlock())
2612 return 0;
2613
2614 /*
2615 * Clearly we all shouldn't be here, but since we made it we
2616 * can reliable say we messed up our state. See the above two
2617 * gotos for reasons why we could possibly end up here.
2618 */
2619 WARN_ON(1);
2620
2621 return 0;
2622}
2623
2624struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
2625static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS);
2626int nr_chain_hlocks;
2627static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
2628
2629struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
2630{
2631 return lock_classes + chain_hlocks[chain->base + i];
2632}
2633
2634/*
2635 * Returns the index of the first held_lock of the current chain
2636 */
2637static inline int get_first_held_lock(struct task_struct *curr,
2638 struct held_lock *hlock)
2639{
2640 int i;
2641 struct held_lock *hlock_curr;
2642
2643 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2644 hlock_curr = curr->held_locks + i;
2645 if (hlock_curr->irq_context != hlock->irq_context)
2646 break;
2647
2648 }
2649
2650 return ++i;
2651}
2652
2653#ifdef CONFIG_DEBUG_LOCKDEP
2654/*
2655 * Returns the next chain_key iteration
2656 */
2657static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2658{
2659 u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2660
2661 printk(" class_idx:%d -> chain_key:%016Lx",
2662 class_idx,
2663 (unsigned long long)new_chain_key);
2664 return new_chain_key;
2665}
2666
2667static void
2668print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2669{
2670 struct held_lock *hlock;
2671 u64 chain_key = INITIAL_CHAIN_KEY;
2672 int depth = curr->lockdep_depth;
2673 int i = get_first_held_lock(curr, hlock_next);
2674
2675 printk("depth: %u (irq_context %u)\n", depth - i + 1,
2676 hlock_next->irq_context);
2677 for (; i < depth; i++) {
2678 hlock = curr->held_locks + i;
2679 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2680
2681 print_lock(hlock);
2682 }
2683
2684 print_chain_key_iteration(hlock_next->class_idx, chain_key);
2685 print_lock(hlock_next);
2686}
2687
2688static void print_chain_keys_chain(struct lock_chain *chain)
2689{
2690 int i;
2691 u64 chain_key = INITIAL_CHAIN_KEY;
2692 int class_id;
2693
2694 printk("depth: %u\n", chain->depth);
2695 for (i = 0; i < chain->depth; i++) {
2696 class_id = chain_hlocks[chain->base + i];
2697 chain_key = print_chain_key_iteration(class_id, chain_key);
2698
2699 print_lock_name(lock_classes + class_id);
2700 printk("\n");
2701 }
2702}
2703
2704static void print_collision(struct task_struct *curr,
2705 struct held_lock *hlock_next,
2706 struct lock_chain *chain)
2707{
2708 pr_warn("\n");
2709 pr_warn("============================\n");
2710 pr_warn("WARNING: chain_key collision\n");
2711 print_kernel_ident();
2712 pr_warn("----------------------------\n");
2713 pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
2714 pr_warn("Hash chain already cached but the contents don't match!\n");
2715
2716 pr_warn("Held locks:");
2717 print_chain_keys_held_locks(curr, hlock_next);
2718
2719 pr_warn("Locks in cached chain:");
2720 print_chain_keys_chain(chain);
2721
2722 pr_warn("\nstack backtrace:\n");
2723 dump_stack();
2724}
2725#endif
2726
2727/*
2728 * Checks whether the chain and the current held locks are consistent
2729 * in depth and also in content. If they are not it most likely means
2730 * that there was a collision during the calculation of the chain_key.
2731 * Returns: 0 not passed, 1 passed
2732 */
2733static int check_no_collision(struct task_struct *curr,
2734 struct held_lock *hlock,
2735 struct lock_chain *chain)
2736{
2737#ifdef CONFIG_DEBUG_LOCKDEP
2738 int i, j, id;
2739
2740 i = get_first_held_lock(curr, hlock);
2741
2742 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2743 print_collision(curr, hlock, chain);
2744 return 0;
2745 }
2746
2747 for (j = 0; j < chain->depth - 1; j++, i++) {
2748 id = curr->held_locks[i].class_idx;
2749
2750 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2751 print_collision(curr, hlock, chain);
2752 return 0;
2753 }
2754 }
2755#endif
2756 return 1;
2757}
2758
2759/*
2760 * Given an index that is >= -1, return the index of the next lock chain.
2761 * Return -2 if there is no next lock chain.
2762 */
2763long lockdep_next_lockchain(long i)
2764{
2765 i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1);
2766 return i < ARRAY_SIZE(lock_chains) ? i : -2;
2767}
2768
2769unsigned long lock_chain_count(void)
2770{
2771 return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains));
2772}
2773
2774/* Must be called with the graph lock held. */
2775static struct lock_chain *alloc_lock_chain(void)
2776{
2777 int idx = find_first_zero_bit(lock_chains_in_use,
2778 ARRAY_SIZE(lock_chains));
2779
2780 if (unlikely(idx >= ARRAY_SIZE(lock_chains)))
2781 return NULL;
2782 __set_bit(idx, lock_chains_in_use);
2783 return lock_chains + idx;
2784}
2785
2786/*
2787 * Adds a dependency chain into chain hashtable. And must be called with
2788 * graph_lock held.
2789 *
2790 * Return 0 if fail, and graph_lock is released.
2791 * Return 1 if succeed, with graph_lock held.
2792 */
2793static inline int add_chain_cache(struct task_struct *curr,
2794 struct held_lock *hlock,
2795 u64 chain_key)
2796{
2797 struct lock_class *class = hlock_class(hlock);
2798 struct hlist_head *hash_head = chainhashentry(chain_key);
2799 struct lock_chain *chain;
2800 int i, j;
2801
2802 /*
2803 * The caller must hold the graph lock, ensure we've got IRQs
2804 * disabled to make this an IRQ-safe lock.. for recursion reasons
2805 * lockdep won't complain about its own locking errors.
2806 */
2807 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2808 return 0;
2809
2810 chain = alloc_lock_chain();
2811 if (!chain) {
2812 if (!debug_locks_off_graph_unlock())
2813 return 0;
2814
2815 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2816 dump_stack();
2817 return 0;
2818 }
2819 chain->chain_key = chain_key;
2820 chain->irq_context = hlock->irq_context;
2821 i = get_first_held_lock(curr, hlock);
2822 chain->depth = curr->lockdep_depth + 1 - i;
2823
2824 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2825 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
2826 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2827
2828 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2829 chain->base = nr_chain_hlocks;
2830 for (j = 0; j < chain->depth - 1; j++, i++) {
2831 int lock_id = curr->held_locks[i].class_idx;
2832 chain_hlocks[chain->base + j] = lock_id;
2833 }
2834 chain_hlocks[chain->base + j] = class - lock_classes;
2835 nr_chain_hlocks += chain->depth;
2836 } else {
2837 if (!debug_locks_off_graph_unlock())
2838 return 0;
2839
2840 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2841 dump_stack();
2842 return 0;
2843 }
2844
2845 hlist_add_head_rcu(&chain->entry, hash_head);
2846 debug_atomic_inc(chain_lookup_misses);
2847 inc_chains();
2848
2849 return 1;
2850}
2851
2852/*
2853 * Look up a dependency chain. Must be called with either the graph lock or
2854 * the RCU read lock held.
2855 */
2856static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
2857{
2858 struct hlist_head *hash_head = chainhashentry(chain_key);
2859 struct lock_chain *chain;
2860
2861 hlist_for_each_entry_rcu(chain, hash_head, entry) {
2862 if (READ_ONCE(chain->chain_key) == chain_key) {
2863 debug_atomic_inc(chain_lookup_hits);
2864 return chain;
2865 }
2866 }
2867 return NULL;
2868}
2869
2870/*
2871 * If the key is not present yet in dependency chain cache then
2872 * add it and return 1 - in this case the new dependency chain is
2873 * validated. If the key is already hashed, return 0.
2874 * (On return with 1 graph_lock is held.)
2875 */
2876static inline int lookup_chain_cache_add(struct task_struct *curr,
2877 struct held_lock *hlock,
2878 u64 chain_key)
2879{
2880 struct lock_class *class = hlock_class(hlock);
2881 struct lock_chain *chain = lookup_chain_cache(chain_key);
2882
2883 if (chain) {
2884cache_hit:
2885 if (!check_no_collision(curr, hlock, chain))
2886 return 0;
2887
2888 if (very_verbose(class)) {
2889 printk("\nhash chain already cached, key: "
2890 "%016Lx tail class: [%px] %s\n",
2891 (unsigned long long)chain_key,
2892 class->key, class->name);
2893 }
2894
2895 return 0;
2896 }
2897
2898 if (very_verbose(class)) {
2899 printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
2900 (unsigned long long)chain_key, class->key, class->name);
2901 }
2902
2903 if (!graph_lock())
2904 return 0;
2905
2906 /*
2907 * We have to walk the chain again locked - to avoid duplicates:
2908 */
2909 chain = lookup_chain_cache(chain_key);
2910 if (chain) {
2911 graph_unlock();
2912 goto cache_hit;
2913 }
2914
2915 if (!add_chain_cache(curr, hlock, chain_key))
2916 return 0;
2917
2918 return 1;
2919}
2920
2921static int validate_chain(struct task_struct *curr,
2922 struct held_lock *hlock,
2923 int chain_head, u64 chain_key)
2924{
2925 /*
2926 * Trylock needs to maintain the stack of held locks, but it
2927 * does not add new dependencies, because trylock can be done
2928 * in any order.
2929 *
2930 * We look up the chain_key and do the O(N^2) check and update of
2931 * the dependencies only if this is a new dependency chain.
2932 * (If lookup_chain_cache_add() return with 1 it acquires
2933 * graph_lock for us)
2934 */
2935 if (!hlock->trylock && hlock->check &&
2936 lookup_chain_cache_add(curr, hlock, chain_key)) {
2937 /*
2938 * Check whether last held lock:
2939 *
2940 * - is irq-safe, if this lock is irq-unsafe
2941 * - is softirq-safe, if this lock is hardirq-unsafe
2942 *
2943 * And check whether the new lock's dependency graph
2944 * could lead back to the previous lock:
2945 *
2946 * - within the current held-lock stack
2947 * - across our accumulated lock dependency records
2948 *
2949 * any of these scenarios could lead to a deadlock.
2950 */
2951 /*
2952 * The simple case: does the current hold the same lock
2953 * already?
2954 */
2955 int ret = check_deadlock(curr, hlock);
2956
2957 if (!ret)
2958 return 0;
2959 /*
2960 * Mark recursive read, as we jump over it when
2961 * building dependencies (just like we jump over
2962 * trylock entries):
2963 */
2964 if (ret == 2)
2965 hlock->read = 2;
2966 /*
2967 * Add dependency only if this lock is not the head
2968 * of the chain, and if it's not a secondary read-lock:
2969 */
2970 if (!chain_head && ret != 2) {
2971 if (!check_prevs_add(curr, hlock))
2972 return 0;
2973 }
2974
2975 graph_unlock();
2976 } else {
2977 /* after lookup_chain_cache_add(): */
2978 if (unlikely(!debug_locks))
2979 return 0;
2980 }
2981
2982 return 1;
2983}
2984#else
2985static inline int validate_chain(struct task_struct *curr,
2986 struct held_lock *hlock,
2987 int chain_head, u64 chain_key)
2988{
2989 return 1;
2990}
2991#endif /* CONFIG_PROVE_LOCKING */
2992
2993/*
2994 * We are building curr_chain_key incrementally, so double-check
2995 * it from scratch, to make sure that it's done correctly:
2996 */
2997static void check_chain_key(struct task_struct *curr)
2998{
2999#ifdef CONFIG_DEBUG_LOCKDEP
3000 struct held_lock *hlock, *prev_hlock = NULL;
3001 unsigned int i;
3002 u64 chain_key = INITIAL_CHAIN_KEY;
3003
3004 for (i = 0; i < curr->lockdep_depth; i++) {
3005 hlock = curr->held_locks + i;
3006 if (chain_key != hlock->prev_chain_key) {
3007 debug_locks_off();
3008 /*
3009 * We got mighty confused, our chain keys don't match
3010 * with what we expect, someone trample on our task state?
3011 */
3012 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
3013 curr->lockdep_depth, i,
3014 (unsigned long long)chain_key,
3015 (unsigned long long)hlock->prev_chain_key);
3016 return;
3017 }
3018
3019 /*
3020 * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is
3021 * it registered lock class index?
3022 */
3023 if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use)))
3024 return;
3025
3026 if (prev_hlock && (prev_hlock->irq_context !=
3027 hlock->irq_context))
3028 chain_key = INITIAL_CHAIN_KEY;
3029 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
3030 prev_hlock = hlock;
3031 }
3032 if (chain_key != curr->curr_chain_key) {
3033 debug_locks_off();
3034 /*
3035 * More smoking hash instead of calculating it, damn see these
3036 * numbers float.. I bet that a pink elephant stepped on my memory.
3037 */
3038 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
3039 curr->lockdep_depth, i,
3040 (unsigned long long)chain_key,
3041 (unsigned long long)curr->curr_chain_key);
3042 }
3043#endif
3044}
3045
3046#ifdef CONFIG_PROVE_LOCKING
3047static int mark_lock(struct task_struct *curr, struct held_lock *this,
3048 enum lock_usage_bit new_bit);
3049
3050static void print_usage_bug_scenario(struct held_lock *lock)
3051{
3052 struct lock_class *class = hlock_class(lock);
3053
3054 printk(" Possible unsafe locking scenario:\n\n");
3055 printk(" CPU0\n");
3056 printk(" ----\n");
3057 printk(" lock(");
3058 __print_lock_name(class);
3059 printk(KERN_CONT ");\n");
3060 printk(" <Interrupt>\n");
3061 printk(" lock(");
3062 __print_lock_name(class);
3063 printk(KERN_CONT ");\n");
3064 printk("\n *** DEADLOCK ***\n\n");
3065}
3066
3067static void
3068print_usage_bug(struct task_struct *curr, struct held_lock *this,
3069 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
3070{
3071 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
3072 return;
3073
3074 pr_warn("\n");
3075 pr_warn("================================\n");
3076 pr_warn("WARNING: inconsistent lock state\n");
3077 print_kernel_ident();
3078 pr_warn("--------------------------------\n");
3079
3080 pr_warn("inconsistent {%s} -> {%s} usage.\n",
3081 usage_str[prev_bit], usage_str[new_bit]);
3082
3083 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
3084 curr->comm, task_pid_nr(curr),
3085 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
3086 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
3087 trace_hardirqs_enabled(curr),
3088 trace_softirqs_enabled(curr));
3089 print_lock(this);
3090
3091 pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
3092 print_lock_trace(hlock_class(this)->usage_traces[prev_bit], 1);
3093
3094 print_irqtrace_events(curr);
3095 pr_warn("\nother info that might help us debug this:\n");
3096 print_usage_bug_scenario(this);
3097
3098 lockdep_print_held_locks(curr);
3099
3100 pr_warn("\nstack backtrace:\n");
3101 dump_stack();
3102}
3103
3104/*
3105 * Print out an error if an invalid bit is set:
3106 */
3107static inline int
3108valid_state(struct task_struct *curr, struct held_lock *this,
3109 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
3110{
3111 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) {
3112 print_usage_bug(curr, this, bad_bit, new_bit);
3113 return 0;
3114 }
3115 return 1;
3116}
3117
3118
3119/*
3120 * print irq inversion bug:
3121 */
3122static void
3123print_irq_inversion_bug(struct task_struct *curr,
3124 struct lock_list *root, struct lock_list *other,
3125 struct held_lock *this, int forwards,
3126 const char *irqclass)
3127{
3128 struct lock_list *entry = other;
3129 struct lock_list *middle = NULL;
3130 int depth;
3131
3132 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
3133 return;
3134
3135 pr_warn("\n");
3136 pr_warn("========================================================\n");
3137 pr_warn("WARNING: possible irq lock inversion dependency detected\n");
3138 print_kernel_ident();
3139 pr_warn("--------------------------------------------------------\n");
3140 pr_warn("%s/%d just changed the state of lock:\n",
3141 curr->comm, task_pid_nr(curr));
3142 print_lock(this);
3143 if (forwards)
3144 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
3145 else
3146 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
3147 print_lock_name(other->class);
3148 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
3149
3150 pr_warn("\nother info that might help us debug this:\n");
3151
3152 /* Find a middle lock (if one exists) */
3153 depth = get_lock_depth(other);
3154 do {
3155 if (depth == 0 && (entry != root)) {
3156 pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
3157 break;
3158 }
3159 middle = entry;
3160 entry = get_lock_parent(entry);
3161 depth--;
3162 } while (entry && entry != root && (depth >= 0));
3163 if (forwards)
3164 print_irq_lock_scenario(root, other,
3165 middle ? middle->class : root->class, other->class);
3166 else
3167 print_irq_lock_scenario(other, root,
3168 middle ? middle->class : other->class, root->class);
3169
3170 lockdep_print_held_locks(curr);
3171
3172 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
3173 root->trace = save_trace();
3174 if (!root->trace)
3175 return;
3176 print_shortest_lock_dependencies(other, root);
3177
3178 pr_warn("\nstack backtrace:\n");
3179 dump_stack();
3180}
3181
3182/*
3183 * Prove that in the forwards-direction subgraph starting at <this>
3184 * there is no lock matching <mask>:
3185 */
3186static int
3187check_usage_forwards(struct task_struct *curr, struct held_lock *this,
3188 enum lock_usage_bit bit, const char *irqclass)
3189{
3190 int ret;
3191 struct lock_list root;
3192 struct lock_list *uninitialized_var(target_entry);
3193
3194 root.parent = NULL;
3195 root.class = hlock_class(this);
3196 ret = find_usage_forwards(&root, lock_flag(bit), &target_entry);
3197 if (ret < 0) {
3198 print_bfs_bug(ret);
3199 return 0;
3200 }
3201 if (ret == 1)
3202 return ret;
3203
3204 print_irq_inversion_bug(curr, &root, target_entry,
3205 this, 1, irqclass);
3206 return 0;
3207}
3208
3209/*
3210 * Prove that in the backwards-direction subgraph starting at <this>
3211 * there is no lock matching <mask>:
3212 */
3213static int
3214check_usage_backwards(struct task_struct *curr, struct held_lock *this,
3215 enum lock_usage_bit bit, const char *irqclass)
3216{
3217 int ret;
3218 struct lock_list root;
3219 struct lock_list *uninitialized_var(target_entry);
3220
3221 root.parent = NULL;
3222 root.class = hlock_class(this);
3223 ret = find_usage_backwards(&root, lock_flag(bit), &target_entry);
3224 if (ret < 0) {
3225 print_bfs_bug(ret);
3226 return 0;
3227 }
3228 if (ret == 1)
3229 return ret;
3230
3231 print_irq_inversion_bug(curr, &root, target_entry,
3232 this, 0, irqclass);
3233 return 0;
3234}
3235
3236void print_irqtrace_events(struct task_struct *curr)
3237{
3238 printk("irq event stamp: %u\n", curr->irq_events);
3239 printk("hardirqs last enabled at (%u): [<%px>] %pS\n",
3240 curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
3241 (void *)curr->hardirq_enable_ip);
3242 printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
3243 curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
3244 (void *)curr->hardirq_disable_ip);
3245 printk("softirqs last enabled at (%u): [<%px>] %pS\n",
3246 curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
3247 (void *)curr->softirq_enable_ip);
3248 printk("softirqs last disabled at (%u): [<%px>] %pS\n",
3249 curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
3250 (void *)curr->softirq_disable_ip);
3251}
3252
3253static int HARDIRQ_verbose(struct lock_class *class)
3254{
3255#if HARDIRQ_VERBOSE
3256 return class_filter(class);
3257#endif
3258 return 0;
3259}
3260
3261static int SOFTIRQ_verbose(struct lock_class *class)
3262{
3263#if SOFTIRQ_VERBOSE
3264 return class_filter(class);
3265#endif
3266 return 0;
3267}
3268
3269#define STRICT_READ_CHECKS 1
3270
3271static int (*state_verbose_f[])(struct lock_class *class) = {
3272#define LOCKDEP_STATE(__STATE) \
3273 __STATE##_verbose,
3274#include "lockdep_states.h"
3275#undef LOCKDEP_STATE
3276};
3277
3278static inline int state_verbose(enum lock_usage_bit bit,
3279 struct lock_class *class)
3280{
3281 return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class);
3282}
3283
3284typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
3285 enum lock_usage_bit bit, const char *name);
3286
3287static int
3288mark_lock_irq(struct task_struct *curr, struct held_lock *this,
3289 enum lock_usage_bit new_bit)
3290{
3291 int excl_bit = exclusive_bit(new_bit);
3292 int read = new_bit & LOCK_USAGE_READ_MASK;
3293 int dir = new_bit & LOCK_USAGE_DIR_MASK;
3294
3295 /*
3296 * mark USED_IN has to look forwards -- to ensure no dependency
3297 * has ENABLED state, which would allow recursion deadlocks.
3298 *
3299 * mark ENABLED has to look backwards -- to ensure no dependee
3300 * has USED_IN state, which, again, would allow recursion deadlocks.
3301 */
3302 check_usage_f usage = dir ?
3303 check_usage_backwards : check_usage_forwards;
3304
3305 /*
3306 * Validate that this particular lock does not have conflicting
3307 * usage states.
3308 */
3309 if (!valid_state(curr, this, new_bit, excl_bit))
3310 return 0;
3311
3312 /*
3313 * Validate that the lock dependencies don't have conflicting usage
3314 * states.
3315 */
3316 if ((!read || STRICT_READ_CHECKS) &&
3317 !usage(curr, this, excl_bit, state_name(new_bit & ~LOCK_USAGE_READ_MASK)))
3318 return 0;
3319
3320 /*
3321 * Check for read in write conflicts
3322 */
3323 if (!read) {
3324 if (!valid_state(curr, this, new_bit, excl_bit + LOCK_USAGE_READ_MASK))
3325 return 0;
3326
3327 if (STRICT_READ_CHECKS &&
3328 !usage(curr, this, excl_bit + LOCK_USAGE_READ_MASK,
3329 state_name(new_bit + LOCK_USAGE_READ_MASK)))
3330 return 0;
3331 }
3332
3333 if (state_verbose(new_bit, hlock_class(this)))
3334 return 2;
3335
3336 return 1;
3337}
3338
3339/*
3340 * Mark all held locks with a usage bit:
3341 */
3342static int
3343mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit)
3344{
3345 struct held_lock *hlock;
3346 int i;
3347
3348 for (i = 0; i < curr->lockdep_depth; i++) {
3349 enum lock_usage_bit hlock_bit = base_bit;
3350 hlock = curr->held_locks + i;
3351
3352 if (hlock->read)
3353 hlock_bit += LOCK_USAGE_READ_MASK;
3354
3355 BUG_ON(hlock_bit >= LOCK_USAGE_STATES);
3356
3357 if (!hlock->check)
3358 continue;
3359
3360 if (!mark_lock(curr, hlock, hlock_bit))
3361 return 0;
3362 }
3363
3364 return 1;
3365}
3366
3367/*
3368 * Hardirqs will be enabled:
3369 */
3370static void __trace_hardirqs_on_caller(unsigned long ip)
3371{
3372 struct task_struct *curr = current;
3373
3374 /* we'll do an OFF -> ON transition: */
3375 curr->hardirqs_enabled = 1;
3376
3377 /*
3378 * We are going to turn hardirqs on, so set the
3379 * usage bit for all held locks:
3380 */
3381 if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ))
3382 return;
3383 /*
3384 * If we have softirqs enabled, then set the usage
3385 * bit for all held locks. (disabled hardirqs prevented
3386 * this bit from being set before)
3387 */
3388 if (curr->softirqs_enabled)
3389 if (!mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ))
3390 return;
3391
3392 curr->hardirq_enable_ip = ip;
3393 curr->hardirq_enable_event = ++curr->irq_events;
3394 debug_atomic_inc(hardirqs_on_events);
3395}
3396
3397void lockdep_hardirqs_on(unsigned long ip)
3398{
3399 if (unlikely(!debug_locks || current->lockdep_recursion))
3400 return;
3401
3402 if (unlikely(current->hardirqs_enabled)) {
3403 /*
3404 * Neither irq nor preemption are disabled here
3405 * so this is racy by nature but losing one hit
3406 * in a stat is not a big deal.
3407 */
3408 __debug_atomic_inc(redundant_hardirqs_on);
3409 return;
3410 }
3411
3412 /*
3413 * We're enabling irqs and according to our state above irqs weren't
3414 * already enabled, yet we find the hardware thinks they are in fact
3415 * enabled.. someone messed up their IRQ state tracing.
3416 */
3417 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3418 return;
3419
3420 /*
3421 * See the fine text that goes along with this variable definition.
3422 */
3423 if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled))
3424 return;
3425
3426 /*
3427 * Can't allow enabling interrupts while in an interrupt handler,
3428 * that's general bad form and such. Recursion, limited stack etc..
3429 */
3430 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
3431 return;
3432
3433 current->lockdep_recursion = 1;
3434 __trace_hardirqs_on_caller(ip);
3435 current->lockdep_recursion = 0;
3436}
3437NOKPROBE_SYMBOL(lockdep_hardirqs_on);
3438
3439/*
3440 * Hardirqs were disabled:
3441 */
3442void lockdep_hardirqs_off(unsigned long ip)
3443{
3444 struct task_struct *curr = current;
3445
3446 if (unlikely(!debug_locks || current->lockdep_recursion))
3447 return;
3448
3449 /*
3450 * So we're supposed to get called after you mask local IRQs, but for
3451 * some reason the hardware doesn't quite think you did a proper job.
3452 */
3453 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3454 return;
3455
3456 if (curr->hardirqs_enabled) {
3457 /*
3458 * We have done an ON -> OFF transition:
3459 */
3460 curr->hardirqs_enabled = 0;
3461 curr->hardirq_disable_ip = ip;
3462 curr->hardirq_disable_event = ++curr->irq_events;
3463 debug_atomic_inc(hardirqs_off_events);
3464 } else
3465 debug_atomic_inc(redundant_hardirqs_off);
3466}
3467NOKPROBE_SYMBOL(lockdep_hardirqs_off);
3468
3469/*
3470 * Softirqs will be enabled:
3471 */
3472void trace_softirqs_on(unsigned long ip)
3473{
3474 struct task_struct *curr = current;
3475
3476 if (unlikely(!debug_locks || current->lockdep_recursion))
3477 return;
3478
3479 /*
3480 * We fancy IRQs being disabled here, see softirq.c, avoids
3481 * funny state and nesting things.
3482 */
3483 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3484 return;
3485
3486 if (curr->softirqs_enabled) {
3487 debug_atomic_inc(redundant_softirqs_on);
3488 return;
3489 }
3490
3491 current->lockdep_recursion = 1;
3492 /*
3493 * We'll do an OFF -> ON transition:
3494 */
3495 curr->softirqs_enabled = 1;
3496 curr->softirq_enable_ip = ip;
3497 curr->softirq_enable_event = ++curr->irq_events;
3498 debug_atomic_inc(softirqs_on_events);
3499 /*
3500 * We are going to turn softirqs on, so set the
3501 * usage bit for all held locks, if hardirqs are
3502 * enabled too:
3503 */
3504 if (curr->hardirqs_enabled)
3505 mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
3506 current->lockdep_recursion = 0;
3507}
3508
3509/*
3510 * Softirqs were disabled:
3511 */
3512void trace_softirqs_off(unsigned long ip)
3513{
3514 struct task_struct *curr = current;
3515
3516 if (unlikely(!debug_locks || current->lockdep_recursion))
3517 return;
3518
3519 /*
3520 * We fancy IRQs being disabled here, see softirq.c
3521 */
3522 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3523 return;
3524
3525 if (curr->softirqs_enabled) {
3526 /*
3527 * We have done an ON -> OFF transition:
3528 */
3529 curr->softirqs_enabled = 0;
3530 curr->softirq_disable_ip = ip;
3531 curr->softirq_disable_event = ++curr->irq_events;
3532 debug_atomic_inc(softirqs_off_events);
3533 /*
3534 * Whoops, we wanted softirqs off, so why aren't they?
3535 */
3536 DEBUG_LOCKS_WARN_ON(!softirq_count());
3537 } else
3538 debug_atomic_inc(redundant_softirqs_off);
3539}
3540
3541static int
3542mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
3543{
3544 if (!check)
3545 goto lock_used;
3546
3547 /*
3548 * If non-trylock use in a hardirq or softirq context, then
3549 * mark the lock as used in these contexts:
3550 */
3551 if (!hlock->trylock) {
3552 if (hlock->read) {
3553 if (curr->hardirq_context)
3554 if (!mark_lock(curr, hlock,
3555 LOCK_USED_IN_HARDIRQ_READ))
3556 return 0;
3557 if (curr->softirq_context)
3558 if (!mark_lock(curr, hlock,
3559 LOCK_USED_IN_SOFTIRQ_READ))
3560 return 0;
3561 } else {
3562 if (curr->hardirq_context)
3563 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
3564 return 0;
3565 if (curr->softirq_context)
3566 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
3567 return 0;
3568 }
3569 }
3570 if (!hlock->hardirqs_off) {
3571 if (hlock->read) {
3572 if (!mark_lock(curr, hlock,
3573 LOCK_ENABLED_HARDIRQ_READ))
3574 return 0;
3575 if (curr->softirqs_enabled)
3576 if (!mark_lock(curr, hlock,
3577 LOCK_ENABLED_SOFTIRQ_READ))
3578 return 0;
3579 } else {
3580 if (!mark_lock(curr, hlock,
3581 LOCK_ENABLED_HARDIRQ))
3582 return 0;
3583 if (curr->softirqs_enabled)
3584 if (!mark_lock(curr, hlock,
3585 LOCK_ENABLED_SOFTIRQ))
3586 return 0;
3587 }
3588 }
3589
3590lock_used:
3591 /* mark it as used: */
3592 if (!mark_lock(curr, hlock, LOCK_USED))
3593 return 0;
3594
3595 return 1;
3596}
3597
3598static inline unsigned int task_irq_context(struct task_struct *task)
3599{
3600 return 2 * !!task->hardirq_context + !!task->softirq_context;
3601}
3602
3603static int separate_irq_context(struct task_struct *curr,
3604 struct held_lock *hlock)
3605{
3606 unsigned int depth = curr->lockdep_depth;
3607
3608 /*
3609 * Keep track of points where we cross into an interrupt context:
3610 */
3611 if (depth) {
3612 struct held_lock *prev_hlock;
3613
3614 prev_hlock = curr->held_locks + depth-1;
3615 /*
3616 * If we cross into another context, reset the
3617 * hash key (this also prevents the checking and the
3618 * adding of the dependency to 'prev'):
3619 */
3620 if (prev_hlock->irq_context != hlock->irq_context)
3621 return 1;
3622 }
3623 return 0;
3624}
3625
3626/*
3627 * Mark a lock with a usage bit, and validate the state transition:
3628 */
3629static int mark_lock(struct task_struct *curr, struct held_lock *this,
3630 enum lock_usage_bit new_bit)
3631{
3632 unsigned int new_mask = 1 << new_bit, ret = 1;
3633
3634 if (new_bit >= LOCK_USAGE_STATES) {
3635 DEBUG_LOCKS_WARN_ON(1);
3636 return 0;
3637 }
3638
3639 /*
3640 * If already set then do not dirty the cacheline,
3641 * nor do any checks:
3642 */
3643 if (likely(hlock_class(this)->usage_mask & new_mask))
3644 return 1;
3645
3646 if (!graph_lock())
3647 return 0;
3648 /*
3649 * Make sure we didn't race:
3650 */
3651 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3652 graph_unlock();
3653 return 1;
3654 }
3655
3656 hlock_class(this)->usage_mask |= new_mask;
3657
3658 if (!(hlock_class(this)->usage_traces[new_bit] = save_trace()))
3659 return 0;
3660
3661 switch (new_bit) {
3662 case LOCK_USED:
3663 debug_atomic_dec(nr_unused_locks);
3664 break;
3665 default:
3666 ret = mark_lock_irq(curr, this, new_bit);
3667 if (!ret)
3668 return 0;
3669 }
3670
3671 graph_unlock();
3672
3673 /*
3674 * We must printk outside of the graph_lock:
3675 */
3676 if (ret == 2) {
3677 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3678 print_lock(this);
3679 print_irqtrace_events(curr);
3680 dump_stack();
3681 }
3682
3683 return ret;
3684}
3685
3686#else /* CONFIG_PROVE_LOCKING */
3687
3688static inline int
3689mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
3690{
3691 return 1;
3692}
3693
3694static inline unsigned int task_irq_context(struct task_struct *task)
3695{
3696 return 0;
3697}
3698
3699static inline int separate_irq_context(struct task_struct *curr,
3700 struct held_lock *hlock)
3701{
3702 return 0;
3703}
3704
3705#endif /* CONFIG_PROVE_LOCKING */
3706
3707/*
3708 * Initialize a lock instance's lock-class mapping info:
3709 */
3710void lockdep_init_map(struct lockdep_map *lock, const char *name,
3711 struct lock_class_key *key, int subclass)
3712{
3713 int i;
3714
3715 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3716 lock->class_cache[i] = NULL;
3717
3718#ifdef CONFIG_LOCK_STAT
3719 lock->cpu = raw_smp_processor_id();
3720#endif
3721
3722 /*
3723 * Can't be having no nameless bastards around this place!
3724 */
3725 if (DEBUG_LOCKS_WARN_ON(!name)) {
3726 lock->name = "NULL";
3727 return;
3728 }
3729
3730 lock->name = name;
3731
3732 /*
3733 * No key, no joy, we need to hash something.
3734 */
3735 if (DEBUG_LOCKS_WARN_ON(!key))
3736 return;
3737 /*
3738 * Sanity check, the lock-class key must either have been allocated
3739 * statically or must have been registered as a dynamic key.
3740 */
3741 if (!static_obj(key) && !is_dynamic_key(key)) {
3742 if (debug_locks)
3743 printk(KERN_ERR "BUG: key %px has not been registered!\n", key);
3744 DEBUG_LOCKS_WARN_ON(1);
3745 return;
3746 }
3747 lock->key = key;
3748
3749 if (unlikely(!debug_locks))
3750 return;
3751
3752 if (subclass) {
3753 unsigned long flags;
3754
3755 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3756 return;
3757
3758 raw_local_irq_save(flags);
3759 current->lockdep_recursion = 1;
3760 register_lock_class(lock, subclass, 1);
3761 current->lockdep_recursion = 0;
3762 raw_local_irq_restore(flags);
3763 }
3764}
3765EXPORT_SYMBOL_GPL(lockdep_init_map);
3766
3767struct lock_class_key __lockdep_no_validate__;
3768EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3769
3770static void
3771print_lock_nested_lock_not_held(struct task_struct *curr,
3772 struct held_lock *hlock,
3773 unsigned long ip)
3774{
3775 if (!debug_locks_off())
3776 return;
3777 if (debug_locks_silent)
3778 return;
3779
3780 pr_warn("\n");
3781 pr_warn("==================================\n");
3782 pr_warn("WARNING: Nested lock was not taken\n");
3783 print_kernel_ident();
3784 pr_warn("----------------------------------\n");
3785
3786 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3787 print_lock(hlock);
3788
3789 pr_warn("\nbut this task is not holding:\n");
3790 pr_warn("%s\n", hlock->nest_lock->name);
3791
3792 pr_warn("\nstack backtrace:\n");
3793 dump_stack();
3794
3795 pr_warn("\nother info that might help us debug this:\n");
3796 lockdep_print_held_locks(curr);
3797
3798 pr_warn("\nstack backtrace:\n");
3799 dump_stack();
3800}
3801
3802static int __lock_is_held(const struct lockdep_map *lock, int read);
3803
3804/*
3805 * This gets called for every mutex_lock*()/spin_lock*() operation.
3806 * We maintain the dependency maps and validate the locking attempt:
3807 *
3808 * The callers must make sure that IRQs are disabled before calling it,
3809 * otherwise we could get an interrupt which would want to take locks,
3810 * which would end up in lockdep again.
3811 */
3812static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3813 int trylock, int read, int check, int hardirqs_off,
3814 struct lockdep_map *nest_lock, unsigned long ip,
3815 int references, int pin_count)
3816{
3817 struct task_struct *curr = current;
3818 struct lock_class *class = NULL;
3819 struct held_lock *hlock;
3820 unsigned int depth;
3821 int chain_head = 0;
3822 int class_idx;
3823 u64 chain_key;
3824
3825 if (unlikely(!debug_locks))
3826 return 0;
3827
3828 if (!prove_locking || lock->key == &__lockdep_no_validate__)
3829 check = 0;
3830
3831 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3832 class = lock->class_cache[subclass];
3833 /*
3834 * Not cached?
3835 */
3836 if (unlikely(!class)) {
3837 class = register_lock_class(lock, subclass, 0);
3838 if (!class)
3839 return 0;
3840 }
3841
3842 debug_class_ops_inc(class);
3843
3844 if (very_verbose(class)) {
3845 printk("\nacquire class [%px] %s", class->key, class->name);
3846 if (class->name_version > 1)
3847 printk(KERN_CONT "#%d", class->name_version);
3848 printk(KERN_CONT "\n");
3849 dump_stack();
3850 }
3851
3852 /*
3853 * Add the lock to the list of currently held locks.
3854 * (we dont increase the depth just yet, up until the
3855 * dependency checks are done)
3856 */
3857 depth = curr->lockdep_depth;
3858 /*
3859 * Ran out of static storage for our per-task lock stack again have we?
3860 */
3861 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3862 return 0;
3863
3864 class_idx = class - lock_classes;
3865
3866 if (depth) {
3867 hlock = curr->held_locks + depth - 1;
3868 if (hlock->class_idx == class_idx && nest_lock) {
3869 if (!references)
3870 references++;
3871
3872 if (!hlock->references)
3873 hlock->references++;
3874
3875 hlock->references += references;
3876
3877 /* Overflow */
3878 if (DEBUG_LOCKS_WARN_ON(hlock->references < references))
3879 return 0;
3880
3881 return 2;
3882 }
3883 }
3884
3885 hlock = curr->held_locks + depth;
3886 /*
3887 * Plain impossible, we just registered it and checked it weren't no
3888 * NULL like.. I bet this mushroom I ate was good!
3889 */
3890 if (DEBUG_LOCKS_WARN_ON(!class))
3891 return 0;
3892 hlock->class_idx = class_idx;
3893 hlock->acquire_ip = ip;
3894 hlock->instance = lock;
3895 hlock->nest_lock = nest_lock;
3896 hlock->irq_context = task_irq_context(curr);
3897 hlock->trylock = trylock;
3898 hlock->read = read;
3899 hlock->check = check;
3900 hlock->hardirqs_off = !!hardirqs_off;
3901 hlock->references = references;
3902#ifdef CONFIG_LOCK_STAT
3903 hlock->waittime_stamp = 0;
3904 hlock->holdtime_stamp = lockstat_clock();
3905#endif
3906 hlock->pin_count = pin_count;
3907
3908 /* Initialize the lock usage bit */
3909 if (!mark_usage(curr, hlock, check))
3910 return 0;
3911
3912 /*
3913 * Calculate the chain hash: it's the combined hash of all the
3914 * lock keys along the dependency chain. We save the hash value
3915 * at every step so that we can get the current hash easily
3916 * after unlock. The chain hash is then used to cache dependency
3917 * results.
3918 *
3919 * The 'key ID' is what is the most compact key value to drive
3920 * the hash, not class->key.
3921 */
3922 /*
3923 * Whoops, we did it again.. class_idx is invalid.
3924 */
3925 if (DEBUG_LOCKS_WARN_ON(!test_bit(class_idx, lock_classes_in_use)))
3926 return 0;
3927
3928 chain_key = curr->curr_chain_key;
3929 if (!depth) {
3930 /*
3931 * How can we have a chain hash when we ain't got no keys?!
3932 */
3933 if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY))
3934 return 0;
3935 chain_head = 1;
3936 }
3937
3938 hlock->prev_chain_key = chain_key;
3939 if (separate_irq_context(curr, hlock)) {
3940 chain_key = INITIAL_CHAIN_KEY;
3941 chain_head = 1;
3942 }
3943 chain_key = iterate_chain_key(chain_key, class_idx);
3944
3945 if (nest_lock && !__lock_is_held(nest_lock, -1)) {
3946 print_lock_nested_lock_not_held(curr, hlock, ip);
3947 return 0;
3948 }
3949
3950 if (!debug_locks_silent) {
3951 WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key);
3952 WARN_ON_ONCE(!hlock_class(hlock)->key);
3953 }
3954
3955 if (!validate_chain(curr, hlock, chain_head, chain_key))
3956 return 0;
3957
3958 curr->curr_chain_key = chain_key;
3959 curr->lockdep_depth++;
3960 check_chain_key(curr);
3961#ifdef CONFIG_DEBUG_LOCKDEP
3962 if (unlikely(!debug_locks))
3963 return 0;
3964#endif
3965 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3966 debug_locks_off();
3967 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3968 printk(KERN_DEBUG "depth: %i max: %lu!\n",
3969 curr->lockdep_depth, MAX_LOCK_DEPTH);
3970
3971 lockdep_print_held_locks(current);
3972 debug_show_all_locks();
3973 dump_stack();
3974
3975 return 0;
3976 }
3977
3978 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3979 max_lockdep_depth = curr->lockdep_depth;
3980
3981 return 1;
3982}
3983
3984static void print_unlock_imbalance_bug(struct task_struct *curr,
3985 struct lockdep_map *lock,
3986 unsigned long ip)
3987{
3988 if (!debug_locks_off())
3989 return;
3990 if (debug_locks_silent)
3991 return;
3992
3993 pr_warn("\n");
3994 pr_warn("=====================================\n");
3995 pr_warn("WARNING: bad unlock balance detected!\n");
3996 print_kernel_ident();
3997 pr_warn("-------------------------------------\n");
3998 pr_warn("%s/%d is trying to release lock (",
3999 curr->comm, task_pid_nr(curr));
4000 print_lockdep_cache(lock);
4001 pr_cont(") at:\n");
4002 print_ip_sym(ip);
4003 pr_warn("but there are no more locks to release!\n");
4004 pr_warn("\nother info that might help us debug this:\n");
4005 lockdep_print_held_locks(curr);
4006
4007 pr_warn("\nstack backtrace:\n");
4008 dump_stack();
4009}
4010
4011static int match_held_lock(const struct held_lock *hlock,
4012 const struct lockdep_map *lock)
4013{
4014 if (hlock->instance == lock)
4015 return 1;
4016
4017 if (hlock->references) {
4018 const struct lock_class *class = lock->class_cache[0];
4019
4020 if (!class)
4021 class = look_up_lock_class(lock, 0);
4022
4023 /*
4024 * If look_up_lock_class() failed to find a class, we're trying
4025 * to test if we hold a lock that has never yet been acquired.
4026 * Clearly if the lock hasn't been acquired _ever_, we're not
4027 * holding it either, so report failure.
4028 */
4029 if (!class)
4030 return 0;
4031
4032 /*
4033 * References, but not a lock we're actually ref-counting?
4034 * State got messed up, follow the sites that change ->references
4035 * and try to make sense of it.
4036 */
4037 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
4038 return 0;
4039
4040 if (hlock->class_idx == class - lock_classes)
4041 return 1;
4042 }
4043
4044 return 0;
4045}
4046
4047/* @depth must not be zero */
4048static struct held_lock *find_held_lock(struct task_struct *curr,
4049 struct lockdep_map *lock,
4050 unsigned int depth, int *idx)
4051{
4052 struct held_lock *ret, *hlock, *prev_hlock;
4053 int i;
4054
4055 i = depth - 1;
4056 hlock = curr->held_locks + i;
4057 ret = hlock;
4058 if (match_held_lock(hlock, lock))
4059 goto out;
4060
4061 ret = NULL;
4062 for (i--, prev_hlock = hlock--;
4063 i >= 0;
4064 i--, prev_hlock = hlock--) {
4065 /*
4066 * We must not cross into another context:
4067 */
4068 if (prev_hlock->irq_context != hlock->irq_context) {
4069 ret = NULL;
4070 break;
4071 }
4072 if (match_held_lock(hlock, lock)) {
4073 ret = hlock;
4074 break;
4075 }
4076 }
4077
4078out:
4079 *idx = i;
4080 return ret;
4081}
4082
4083static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
4084 int idx, unsigned int *merged)
4085{
4086 struct held_lock *hlock;
4087 int first_idx = idx;
4088
4089 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4090 return 0;
4091
4092 for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
4093 switch (__lock_acquire(hlock->instance,
4094 hlock_class(hlock)->subclass,
4095 hlock->trylock,
4096 hlock->read, hlock->check,
4097 hlock->hardirqs_off,
4098 hlock->nest_lock, hlock->acquire_ip,
4099 hlock->references, hlock->pin_count)) {
4100 case 0:
4101 return 1;
4102 case 1:
4103 break;
4104 case 2:
4105 *merged += (idx == first_idx);
4106 break;
4107 default:
4108 WARN_ON(1);
4109 return 0;
4110 }
4111 }
4112 return 0;
4113}
4114
4115static int
4116__lock_set_class(struct lockdep_map *lock, const char *name,
4117 struct lock_class_key *key, unsigned int subclass,
4118 unsigned long ip)
4119{
4120 struct task_struct *curr = current;
4121 unsigned int depth, merged = 0;
4122 struct held_lock *hlock;
4123 struct lock_class *class;
4124 int i;
4125
4126 if (unlikely(!debug_locks))
4127 return 0;
4128
4129 depth = curr->lockdep_depth;
4130 /*
4131 * This function is about (re)setting the class of a held lock,
4132 * yet we're not actually holding any locks. Naughty user!
4133 */
4134 if (DEBUG_LOCKS_WARN_ON(!depth))
4135 return 0;
4136
4137 hlock = find_held_lock(curr, lock, depth, &i);
4138 if (!hlock) {
4139 print_unlock_imbalance_bug(curr, lock, ip);
4140 return 0;
4141 }
4142
4143 lockdep_init_map(lock, name, key, 0);
4144 class = register_lock_class(lock, subclass, 0);
4145 hlock->class_idx = class - lock_classes;
4146
4147 curr->lockdep_depth = i;
4148 curr->curr_chain_key = hlock->prev_chain_key;
4149
4150 if (reacquire_held_locks(curr, depth, i, &merged))
4151 return 0;
4152
4153 /*
4154 * I took it apart and put it back together again, except now I have
4155 * these 'spare' parts.. where shall I put them.
4156 */
4157 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged))
4158 return 0;
4159 return 1;
4160}
4161
4162static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
4163{
4164 struct task_struct *curr = current;
4165 unsigned int depth, merged = 0;
4166 struct held_lock *hlock;
4167 int i;
4168
4169 if (unlikely(!debug_locks))
4170 return 0;
4171
4172 depth = curr->lockdep_depth;
4173 /*
4174 * This function is about (re)setting the class of a held lock,
4175 * yet we're not actually holding any locks. Naughty user!
4176 */
4177 if (DEBUG_LOCKS_WARN_ON(!depth))
4178 return 0;
4179
4180 hlock = find_held_lock(curr, lock, depth, &i);
4181 if (!hlock) {
4182 print_unlock_imbalance_bug(curr, lock, ip);
4183 return 0;
4184 }
4185
4186 curr->lockdep_depth = i;
4187 curr->curr_chain_key = hlock->prev_chain_key;
4188
4189 WARN(hlock->read, "downgrading a read lock");
4190 hlock->read = 1;
4191 hlock->acquire_ip = ip;
4192
4193 if (reacquire_held_locks(curr, depth, i, &merged))
4194 return 0;
4195
4196 /* Merging can't happen with unchanged classes.. */
4197 if (DEBUG_LOCKS_WARN_ON(merged))
4198 return 0;
4199
4200 /*
4201 * I took it apart and put it back together again, except now I have
4202 * these 'spare' parts.. where shall I put them.
4203 */
4204 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
4205 return 0;
4206
4207 return 1;
4208}
4209
4210/*
4211 * Remove the lock to the list of currently held locks - this gets
4212 * called on mutex_unlock()/spin_unlock*() (or on a failed
4213 * mutex_lock_interruptible()).
4214 *
4215 * @nested is an hysterical artifact, needs a tree wide cleanup.
4216 */
4217static int
4218__lock_release(struct lockdep_map *lock, unsigned long ip)
4219{
4220 struct task_struct *curr = current;
4221 unsigned int depth, merged = 1;
4222 struct held_lock *hlock;
4223 int i;
4224
4225 if (unlikely(!debug_locks))
4226 return 0;
4227
4228 depth = curr->lockdep_depth;
4229 /*
4230 * So we're all set to release this lock.. wait what lock? We don't
4231 * own any locks, you've been drinking again?
4232 */
4233 if (depth <= 0) {
4234 print_unlock_imbalance_bug(curr, lock, ip);
4235 return 0;
4236 }
4237
4238 /*
4239 * Check whether the lock exists in the current stack
4240 * of held locks:
4241 */
4242 hlock = find_held_lock(curr, lock, depth, &i);
4243 if (!hlock) {
4244 print_unlock_imbalance_bug(curr, lock, ip);
4245 return 0;
4246 }
4247
4248 if (hlock->instance == lock)
4249 lock_release_holdtime(hlock);
4250
4251 WARN(hlock->pin_count, "releasing a pinned lock\n");
4252
4253 if (hlock->references) {
4254 hlock->references--;
4255 if (hlock->references) {
4256 /*
4257 * We had, and after removing one, still have
4258 * references, the current lock stack is still
4259 * valid. We're done!
4260 */
4261 return 1;
4262 }
4263 }
4264
4265 /*
4266 * We have the right lock to unlock, 'hlock' points to it.
4267 * Now we remove it from the stack, and add back the other
4268 * entries (if any), recalculating the hash along the way:
4269 */
4270
4271 curr->lockdep_depth = i;
4272 curr->curr_chain_key = hlock->prev_chain_key;
4273
4274 /*
4275 * The most likely case is when the unlock is on the innermost
4276 * lock. In this case, we are done!
4277 */
4278 if (i == depth-1)
4279 return 1;
4280
4281 if (reacquire_held_locks(curr, depth, i + 1, &merged))
4282 return 0;
4283
4284 /*
4285 * We had N bottles of beer on the wall, we drank one, but now
4286 * there's not N-1 bottles of beer left on the wall...
4287 * Pouring two of the bottles together is acceptable.
4288 */
4289 DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged);
4290
4291 /*
4292 * Since reacquire_held_locks() would have called check_chain_key()
4293 * indirectly via __lock_acquire(), we don't need to do it again
4294 * on return.
4295 */
4296 return 0;
4297}
4298
4299static nokprobe_inline
4300int __lock_is_held(const struct lockdep_map *lock, int read)
4301{
4302 struct task_struct *curr = current;
4303 int i;
4304
4305 for (i = 0; i < curr->lockdep_depth; i++) {
4306 struct held_lock *hlock = curr->held_locks + i;
4307
4308 if (match_held_lock(hlock, lock)) {
4309 if (read == -1 || hlock->read == read)
4310 return 1;
4311
4312 return 0;
4313 }
4314 }
4315
4316 return 0;
4317}
4318
4319static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
4320{
4321 struct pin_cookie cookie = NIL_COOKIE;
4322 struct task_struct *curr = current;
4323 int i;
4324
4325 if (unlikely(!debug_locks))
4326 return cookie;
4327
4328 for (i = 0; i < curr->lockdep_depth; i++) {
4329 struct held_lock *hlock = curr->held_locks + i;
4330
4331 if (match_held_lock(hlock, lock)) {
4332 /*
4333 * Grab 16bits of randomness; this is sufficient to not
4334 * be guessable and still allows some pin nesting in
4335 * our u32 pin_count.
4336 */
4337 cookie.val = 1 + (prandom_u32() >> 16);
4338 hlock->pin_count += cookie.val;
4339 return cookie;
4340 }
4341 }
4342
4343 WARN(1, "pinning an unheld lock\n");
4344 return cookie;
4345}
4346
4347static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4348{
4349 struct task_struct *curr = current;
4350 int i;
4351
4352 if (unlikely(!debug_locks))
4353 return;
4354
4355 for (i = 0; i < curr->lockdep_depth; i++) {
4356 struct held_lock *hlock = curr->held_locks + i;
4357
4358 if (match_held_lock(hlock, lock)) {
4359 hlock->pin_count += cookie.val;
4360 return;
4361 }
4362 }
4363
4364 WARN(1, "pinning an unheld lock\n");
4365}
4366
4367static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4368{
4369 struct task_struct *curr = current;
4370 int i;
4371
4372 if (unlikely(!debug_locks))
4373 return;
4374
4375 for (i = 0; i < curr->lockdep_depth; i++) {
4376 struct held_lock *hlock = curr->held_locks + i;
4377
4378 if (match_held_lock(hlock, lock)) {
4379 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
4380 return;
4381
4382 hlock->pin_count -= cookie.val;
4383
4384 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
4385 hlock->pin_count = 0;
4386
4387 return;
4388 }
4389 }
4390
4391 WARN(1, "unpinning an unheld lock\n");
4392}
4393
4394/*
4395 * Check whether we follow the irq-flags state precisely:
4396 */
4397static void check_flags(unsigned long flags)
4398{
4399#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP)
4400 if (!debug_locks)
4401 return;
4402
4403 if (irqs_disabled_flags(flags)) {
4404 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
4405 printk("possible reason: unannotated irqs-off.\n");
4406 }
4407 } else {
4408 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
4409 printk("possible reason: unannotated irqs-on.\n");
4410 }
4411 }
4412
4413 /*
4414 * We dont accurately track softirq state in e.g.
4415 * hardirq contexts (such as on 4KSTACKS), so only
4416 * check if not in hardirq contexts:
4417 */
4418 if (!hardirq_count()) {
4419 if (softirq_count()) {
4420 /* like the above, but with softirqs */
4421 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
4422 } else {
4423 /* lick the above, does it taste good? */
4424 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
4425 }
4426 }
4427
4428 if (!debug_locks)
4429 print_irqtrace_events(current);
4430#endif
4431}
4432
4433void lock_set_class(struct lockdep_map *lock, const char *name,
4434 struct lock_class_key *key, unsigned int subclass,
4435 unsigned long ip)
4436{
4437 unsigned long flags;
4438
4439 if (unlikely(current->lockdep_recursion))
4440 return;
4441
4442 raw_local_irq_save(flags);
4443 current->lockdep_recursion = 1;
4444 check_flags(flags);
4445 if (__lock_set_class(lock, name, key, subclass, ip))
4446 check_chain_key(current);
4447 current->lockdep_recursion = 0;
4448 raw_local_irq_restore(flags);
4449}
4450EXPORT_SYMBOL_GPL(lock_set_class);
4451
4452void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
4453{
4454 unsigned long flags;
4455
4456 if (unlikely(current->lockdep_recursion))
4457 return;
4458
4459 raw_local_irq_save(flags);
4460 current->lockdep_recursion = 1;
4461 check_flags(flags);
4462 if (__lock_downgrade(lock, ip))
4463 check_chain_key(current);
4464 current->lockdep_recursion = 0;
4465 raw_local_irq_restore(flags);
4466}
4467EXPORT_SYMBOL_GPL(lock_downgrade);
4468
4469/*
4470 * We are not always called with irqs disabled - do that here,
4471 * and also avoid lockdep recursion:
4472 */
4473void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
4474 int trylock, int read, int check,
4475 struct lockdep_map *nest_lock, unsigned long ip)
4476{
4477 unsigned long flags;
4478
4479 if (unlikely(current->lockdep_recursion))
4480 return;
4481
4482 raw_local_irq_save(flags);
4483 check_flags(flags);
4484
4485 current->lockdep_recursion = 1;
4486 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
4487 __lock_acquire(lock, subclass, trylock, read, check,
4488 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
4489 current->lockdep_recursion = 0;
4490 raw_local_irq_restore(flags);
4491}
4492EXPORT_SYMBOL_GPL(lock_acquire);
4493
4494void lock_release(struct lockdep_map *lock, int nested,
4495 unsigned long ip)
4496{
4497 unsigned long flags;
4498
4499 if (unlikely(current->lockdep_recursion))
4500 return;
4501
4502 raw_local_irq_save(flags);
4503 check_flags(flags);
4504 current->lockdep_recursion = 1;
4505 trace_lock_release(lock, ip);
4506 if (__lock_release(lock, ip))
4507 check_chain_key(current);
4508 current->lockdep_recursion = 0;
4509 raw_local_irq_restore(flags);
4510}
4511EXPORT_SYMBOL_GPL(lock_release);
4512
4513int lock_is_held_type(const struct lockdep_map *lock, int read)
4514{
4515 unsigned long flags;
4516 int ret = 0;
4517
4518 if (unlikely(current->lockdep_recursion))
4519 return 1; /* avoid false negative lockdep_assert_held() */
4520
4521 raw_local_irq_save(flags);
4522 check_flags(flags);
4523
4524 current->lockdep_recursion = 1;
4525 ret = __lock_is_held(lock, read);
4526 current->lockdep_recursion = 0;
4527 raw_local_irq_restore(flags);
4528
4529 return ret;
4530}
4531EXPORT_SYMBOL_GPL(lock_is_held_type);
4532NOKPROBE_SYMBOL(lock_is_held_type);
4533
4534struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
4535{
4536 struct pin_cookie cookie = NIL_COOKIE;
4537 unsigned long flags;
4538
4539 if (unlikely(current->lockdep_recursion))
4540 return cookie;
4541
4542 raw_local_irq_save(flags);
4543 check_flags(flags);
4544
4545 current->lockdep_recursion = 1;
4546 cookie = __lock_pin_lock(lock);
4547 current->lockdep_recursion = 0;
4548 raw_local_irq_restore(flags);
4549
4550 return cookie;
4551}
4552EXPORT_SYMBOL_GPL(lock_pin_lock);
4553
4554void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4555{
4556 unsigned long flags;
4557
4558 if (unlikely(current->lockdep_recursion))
4559 return;
4560
4561 raw_local_irq_save(flags);
4562 check_flags(flags);
4563
4564 current->lockdep_recursion = 1;
4565 __lock_repin_lock(lock, cookie);
4566 current->lockdep_recursion = 0;
4567 raw_local_irq_restore(flags);
4568}
4569EXPORT_SYMBOL_GPL(lock_repin_lock);
4570
4571void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4572{
4573 unsigned long flags;
4574
4575 if (unlikely(current->lockdep_recursion))
4576 return;
4577
4578 raw_local_irq_save(flags);
4579 check_flags(flags);
4580
4581 current->lockdep_recursion = 1;
4582 __lock_unpin_lock(lock, cookie);
4583 current->lockdep_recursion = 0;
4584 raw_local_irq_restore(flags);
4585}
4586EXPORT_SYMBOL_GPL(lock_unpin_lock);
4587
4588#ifdef CONFIG_LOCK_STAT
4589static void print_lock_contention_bug(struct task_struct *curr,
4590 struct lockdep_map *lock,
4591 unsigned long ip)
4592{
4593 if (!debug_locks_off())
4594 return;
4595 if (debug_locks_silent)
4596 return;
4597
4598 pr_warn("\n");
4599 pr_warn("=================================\n");
4600 pr_warn("WARNING: bad contention detected!\n");
4601 print_kernel_ident();
4602 pr_warn("---------------------------------\n");
4603 pr_warn("%s/%d is trying to contend lock (",
4604 curr->comm, task_pid_nr(curr));
4605 print_lockdep_cache(lock);
4606 pr_cont(") at:\n");
4607 print_ip_sym(ip);
4608 pr_warn("but there are no locks held!\n");
4609 pr_warn("\nother info that might help us debug this:\n");
4610 lockdep_print_held_locks(curr);
4611
4612 pr_warn("\nstack backtrace:\n");
4613 dump_stack();
4614}
4615
4616static void
4617__lock_contended(struct lockdep_map *lock, unsigned long ip)
4618{
4619 struct task_struct *curr = current;
4620 struct held_lock *hlock;
4621 struct lock_class_stats *stats;
4622 unsigned int depth;
4623 int i, contention_point, contending_point;
4624
4625 depth = curr->lockdep_depth;
4626 /*
4627 * Whee, we contended on this lock, except it seems we're not
4628 * actually trying to acquire anything much at all..
4629 */
4630 if (DEBUG_LOCKS_WARN_ON(!depth))
4631 return;
4632
4633 hlock = find_held_lock(curr, lock, depth, &i);
4634 if (!hlock) {
4635 print_lock_contention_bug(curr, lock, ip);
4636 return;
4637 }
4638
4639 if (hlock->instance != lock)
4640 return;
4641
4642 hlock->waittime_stamp = lockstat_clock();
4643
4644 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
4645 contending_point = lock_point(hlock_class(hlock)->contending_point,
4646 lock->ip);
4647
4648 stats = get_lock_stats(hlock_class(hlock));
4649 if (contention_point < LOCKSTAT_POINTS)
4650 stats->contention_point[contention_point]++;
4651 if (contending_point < LOCKSTAT_POINTS)
4652 stats->contending_point[contending_point]++;
4653 if (lock->cpu != smp_processor_id())
4654 stats->bounces[bounce_contended + !!hlock->read]++;
4655}
4656
4657static void
4658__lock_acquired(struct lockdep_map *lock, unsigned long ip)
4659{
4660 struct task_struct *curr = current;
4661 struct held_lock *hlock;
4662 struct lock_class_stats *stats;
4663 unsigned int depth;
4664 u64 now, waittime = 0;
4665 int i, cpu;
4666
4667 depth = curr->lockdep_depth;
4668 /*
4669 * Yay, we acquired ownership of this lock we didn't try to
4670 * acquire, how the heck did that happen?
4671 */
4672 if (DEBUG_LOCKS_WARN_ON(!depth))
4673 return;
4674
4675 hlock = find_held_lock(curr, lock, depth, &i);
4676 if (!hlock) {
4677 print_lock_contention_bug(curr, lock, _RET_IP_);
4678 return;
4679 }
4680
4681 if (hlock->instance != lock)
4682 return;
4683
4684 cpu = smp_processor_id();
4685 if (hlock->waittime_stamp) {
4686 now = lockstat_clock();
4687 waittime = now - hlock->waittime_stamp;
4688 hlock->holdtime_stamp = now;
4689 }
4690
4691 trace_lock_acquired(lock, ip);
4692
4693 stats = get_lock_stats(hlock_class(hlock));
4694 if (waittime) {
4695 if (hlock->read)
4696 lock_time_inc(&stats->read_waittime, waittime);
4697 else
4698 lock_time_inc(&stats->write_waittime, waittime);
4699 }
4700 if (lock->cpu != cpu)
4701 stats->bounces[bounce_acquired + !!hlock->read]++;
4702
4703 lock->cpu = cpu;
4704 lock->ip = ip;
4705}
4706
4707void lock_contended(struct lockdep_map *lock, unsigned long ip)
4708{
4709 unsigned long flags;
4710
4711 if (unlikely(!lock_stat || !debug_locks))
4712 return;
4713
4714 if (unlikely(current->lockdep_recursion))
4715 return;
4716
4717 raw_local_irq_save(flags);
4718 check_flags(flags);
4719 current->lockdep_recursion = 1;
4720 trace_lock_contended(lock, ip);
4721 __lock_contended(lock, ip);
4722 current->lockdep_recursion = 0;
4723 raw_local_irq_restore(flags);
4724}
4725EXPORT_SYMBOL_GPL(lock_contended);
4726
4727void lock_acquired(struct lockdep_map *lock, unsigned long ip)
4728{
4729 unsigned long flags;
4730
4731 if (unlikely(!lock_stat || !debug_locks))
4732 return;
4733
4734 if (unlikely(current->lockdep_recursion))
4735 return;
4736
4737 raw_local_irq_save(flags);
4738 check_flags(flags);
4739 current->lockdep_recursion = 1;
4740 __lock_acquired(lock, ip);
4741 current->lockdep_recursion = 0;
4742 raw_local_irq_restore(flags);
4743}
4744EXPORT_SYMBOL_GPL(lock_acquired);
4745#endif
4746
4747/*
4748 * Used by the testsuite, sanitize the validator state
4749 * after a simulated failure:
4750 */
4751
4752void lockdep_reset(void)
4753{
4754 unsigned long flags;
4755 int i;
4756
4757 raw_local_irq_save(flags);
4758 lockdep_init_task(current);
4759 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
4760 nr_hardirq_chains = 0;
4761 nr_softirq_chains = 0;
4762 nr_process_chains = 0;
4763 debug_locks = 1;
4764 for (i = 0; i < CHAINHASH_SIZE; i++)
4765 INIT_HLIST_HEAD(chainhash_table + i);
4766 raw_local_irq_restore(flags);
4767}
4768
4769/* Remove a class from a lock chain. Must be called with the graph lock held. */
4770static void remove_class_from_lock_chain(struct pending_free *pf,
4771 struct lock_chain *chain,
4772 struct lock_class *class)
4773{
4774#ifdef CONFIG_PROVE_LOCKING
4775 struct lock_chain *new_chain;
4776 u64 chain_key;
4777 int i;
4778
4779 for (i = chain->base; i < chain->base + chain->depth; i++) {
4780 if (chain_hlocks[i] != class - lock_classes)
4781 continue;
4782 /* The code below leaks one chain_hlock[] entry. */
4783 if (--chain->depth > 0) {
4784 memmove(&chain_hlocks[i], &chain_hlocks[i + 1],
4785 (chain->base + chain->depth - i) *
4786 sizeof(chain_hlocks[0]));
4787 }
4788 /*
4789 * Each lock class occurs at most once in a lock chain so once
4790 * we found a match we can break out of this loop.
4791 */
4792 goto recalc;
4793 }
4794 /* Since the chain has not been modified, return. */
4795 return;
4796
4797recalc:
4798 chain_key = INITIAL_CHAIN_KEY;
4799 for (i = chain->base; i < chain->base + chain->depth; i++)
4800 chain_key = iterate_chain_key(chain_key, chain_hlocks[i]);
4801 if (chain->depth && chain->chain_key == chain_key)
4802 return;
4803 /* Overwrite the chain key for concurrent RCU readers. */
4804 WRITE_ONCE(chain->chain_key, chain_key);
4805 /*
4806 * Note: calling hlist_del_rcu() from inside a
4807 * hlist_for_each_entry_rcu() loop is safe.
4808 */
4809 hlist_del_rcu(&chain->entry);
4810 __set_bit(chain - lock_chains, pf->lock_chains_being_freed);
4811 if (chain->depth == 0)
4812 return;
4813 /*
4814 * If the modified lock chain matches an existing lock chain, drop
4815 * the modified lock chain.
4816 */
4817 if (lookup_chain_cache(chain_key))
4818 return;
4819 new_chain = alloc_lock_chain();
4820 if (WARN_ON_ONCE(!new_chain)) {
4821 debug_locks_off();
4822 return;
4823 }
4824 *new_chain = *chain;
4825 hlist_add_head_rcu(&new_chain->entry, chainhashentry(chain_key));
4826#endif
4827}
4828
4829/* Must be called with the graph lock held. */
4830static void remove_class_from_lock_chains(struct pending_free *pf,
4831 struct lock_class *class)
4832{
4833 struct lock_chain *chain;
4834 struct hlist_head *head;
4835 int i;
4836
4837 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
4838 head = chainhash_table + i;
4839 hlist_for_each_entry_rcu(chain, head, entry) {
4840 remove_class_from_lock_chain(pf, chain, class);
4841 }
4842 }
4843}
4844
4845/*
4846 * Remove all references to a lock class. The caller must hold the graph lock.
4847 */
4848static void zap_class(struct pending_free *pf, struct lock_class *class)
4849{
4850 struct lock_list *entry;
4851 int i;
4852
4853 WARN_ON_ONCE(!class->key);
4854
4855 /*
4856 * Remove all dependencies this lock is
4857 * involved in:
4858 */
4859 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
4860 entry = list_entries + i;
4861 if (entry->class != class && entry->links_to != class)
4862 continue;
4863 __clear_bit(i, list_entries_in_use);
4864 nr_list_entries--;
4865 list_del_rcu(&entry->entry);
4866 }
4867 if (list_empty(&class->locks_after) &&
4868 list_empty(&class->locks_before)) {
4869 list_move_tail(&class->lock_entry, &pf->zapped);
4870 hlist_del_rcu(&class->hash_entry);
4871 WRITE_ONCE(class->key, NULL);
4872 WRITE_ONCE(class->name, NULL);
4873 nr_lock_classes--;
4874 __clear_bit(class - lock_classes, lock_classes_in_use);
4875 } else {
4876 WARN_ONCE(true, "%s() failed for class %s\n", __func__,
4877 class->name);
4878 }
4879
4880 remove_class_from_lock_chains(pf, class);
4881}
4882
4883static void reinit_class(struct lock_class *class)
4884{
4885 void *const p = class;
4886 const unsigned int offset = offsetof(struct lock_class, key);
4887
4888 WARN_ON_ONCE(!class->lock_entry.next);
4889 WARN_ON_ONCE(!list_empty(&class->locks_after));
4890 WARN_ON_ONCE(!list_empty(&class->locks_before));
4891 memset(p + offset, 0, sizeof(*class) - offset);
4892 WARN_ON_ONCE(!class->lock_entry.next);
4893 WARN_ON_ONCE(!list_empty(&class->locks_after));
4894 WARN_ON_ONCE(!list_empty(&class->locks_before));
4895}
4896
4897static inline int within(const void *addr, void *start, unsigned long size)
4898{
4899 return addr >= start && addr < start + size;
4900}
4901
4902static bool inside_selftest(void)
4903{
4904 return current == lockdep_selftest_task_struct;
4905}
4906
4907/* The caller must hold the graph lock. */
4908static struct pending_free *get_pending_free(void)
4909{
4910 return delayed_free.pf + delayed_free.index;
4911}
4912
4913static void free_zapped_rcu(struct rcu_head *cb);
4914
4915/*
4916 * Schedule an RCU callback if no RCU callback is pending. Must be called with
4917 * the graph lock held.
4918 */
4919static void call_rcu_zapped(struct pending_free *pf)
4920{
4921 WARN_ON_ONCE(inside_selftest());
4922
4923 if (list_empty(&pf->zapped))
4924 return;
4925
4926 if (delayed_free.scheduled)
4927 return;
4928
4929 delayed_free.scheduled = true;
4930
4931 WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf);
4932 delayed_free.index ^= 1;
4933
4934 call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
4935}
4936
4937/* The caller must hold the graph lock. May be called from RCU context. */
4938static void __free_zapped_classes(struct pending_free *pf)
4939{
4940 struct lock_class *class;
4941
4942 check_data_structures();
4943
4944 list_for_each_entry(class, &pf->zapped, lock_entry)
4945 reinit_class(class);
4946
4947 list_splice_init(&pf->zapped, &free_lock_classes);
4948
4949#ifdef CONFIG_PROVE_LOCKING
4950 bitmap_andnot(lock_chains_in_use, lock_chains_in_use,
4951 pf->lock_chains_being_freed, ARRAY_SIZE(lock_chains));
4952 bitmap_clear(pf->lock_chains_being_freed, 0, ARRAY_SIZE(lock_chains));
4953#endif
4954}
4955
4956static void free_zapped_rcu(struct rcu_head *ch)
4957{
4958 struct pending_free *pf;
4959 unsigned long flags;
4960
4961 if (WARN_ON_ONCE(ch != &delayed_free.rcu_head))
4962 return;
4963
4964 raw_local_irq_save(flags);
4965 arch_spin_lock(&lockdep_lock);
4966 current->lockdep_recursion = 1;
4967
4968 /* closed head */
4969 pf = delayed_free.pf + (delayed_free.index ^ 1);
4970 __free_zapped_classes(pf);
4971 delayed_free.scheduled = false;
4972
4973 /*
4974 * If there's anything on the open list, close and start a new callback.
4975 */
4976 call_rcu_zapped(delayed_free.pf + delayed_free.index);
4977
4978 current->lockdep_recursion = 0;
4979 arch_spin_unlock(&lockdep_lock);
4980 raw_local_irq_restore(flags);
4981}
4982
4983/*
4984 * Remove all lock classes from the class hash table and from the
4985 * all_lock_classes list whose key or name is in the address range [start,
4986 * start + size). Move these lock classes to the zapped_classes list. Must
4987 * be called with the graph lock held.
4988 */
4989static void __lockdep_free_key_range(struct pending_free *pf, void *start,
4990 unsigned long size)
4991{
4992 struct lock_class *class;
4993 struct hlist_head *head;
4994 int i;
4995
4996 /* Unhash all classes that were created by a module. */
4997 for (i = 0; i < CLASSHASH_SIZE; i++) {
4998 head = classhash_table + i;
4999 hlist_for_each_entry_rcu(class, head, hash_entry) {
5000 if (!within(class->key, start, size) &&
5001 !within(class->name, start, size))
5002 continue;
5003 zap_class(pf, class);
5004 }
5005 }
5006}
5007
5008/*
5009 * Used in module.c to remove lock classes from memory that is going to be
5010 * freed; and possibly re-used by other modules.
5011 *
5012 * We will have had one synchronize_rcu() before getting here, so we're
5013 * guaranteed nobody will look up these exact classes -- they're properly dead
5014 * but still allocated.
5015 */
5016static void lockdep_free_key_range_reg(void *start, unsigned long size)
5017{
5018 struct pending_free *pf;
5019 unsigned long flags;
5020
5021 init_data_structures_once();
5022
5023 raw_local_irq_save(flags);
5024 arch_spin_lock(&lockdep_lock);
5025 current->lockdep_recursion = 1;
5026 pf = get_pending_free();
5027 __lockdep_free_key_range(pf, start, size);
5028 call_rcu_zapped(pf);
5029 current->lockdep_recursion = 0;
5030 arch_spin_unlock(&lockdep_lock);
5031 raw_local_irq_restore(flags);
5032
5033 /*
5034 * Wait for any possible iterators from look_up_lock_class() to pass
5035 * before continuing to free the memory they refer to.
5036 */
5037 synchronize_rcu();
5038}
5039
5040/*
5041 * Free all lockdep keys in the range [start, start+size). Does not sleep.
5042 * Ignores debug_locks. Must only be used by the lockdep selftests.
5043 */
5044static void lockdep_free_key_range_imm(void *start, unsigned long size)
5045{
5046 struct pending_free *pf = delayed_free.pf;
5047 unsigned long flags;
5048
5049 init_data_structures_once();
5050
5051 raw_local_irq_save(flags);
5052 arch_spin_lock(&lockdep_lock);
5053 __lockdep_free_key_range(pf, start, size);
5054 __free_zapped_classes(pf);
5055 arch_spin_unlock(&lockdep_lock);
5056 raw_local_irq_restore(flags);
5057}
5058
5059void lockdep_free_key_range(void *start, unsigned long size)
5060{
5061 init_data_structures_once();
5062
5063 if (inside_selftest())
5064 lockdep_free_key_range_imm(start, size);
5065 else
5066 lockdep_free_key_range_reg(start, size);
5067}
5068
5069/*
5070 * Check whether any element of the @lock->class_cache[] array refers to a
5071 * registered lock class. The caller must hold either the graph lock or the
5072 * RCU read lock.
5073 */
5074static bool lock_class_cache_is_registered(struct lockdep_map *lock)
5075{
5076 struct lock_class *class;
5077 struct hlist_head *head;
5078 int i, j;
5079
5080 for (i = 0; i < CLASSHASH_SIZE; i++) {
5081 head = classhash_table + i;
5082 hlist_for_each_entry_rcu(class, head, hash_entry) {
5083 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
5084 if (lock->class_cache[j] == class)
5085 return true;
5086 }
5087 }
5088 return false;
5089}
5090
5091/* The caller must hold the graph lock. Does not sleep. */
5092static void __lockdep_reset_lock(struct pending_free *pf,
5093 struct lockdep_map *lock)
5094{
5095 struct lock_class *class;
5096 int j;
5097
5098 /*
5099 * Remove all classes this lock might have:
5100 */
5101 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
5102 /*
5103 * If the class exists we look it up and zap it:
5104 */
5105 class = look_up_lock_class(lock, j);
5106 if (class)
5107 zap_class(pf, class);
5108 }
5109 /*
5110 * Debug check: in the end all mapped classes should
5111 * be gone.
5112 */
5113 if (WARN_ON_ONCE(lock_class_cache_is_registered(lock)))
5114 debug_locks_off();
5115}
5116
5117/*
5118 * Remove all information lockdep has about a lock if debug_locks == 1. Free
5119 * released data structures from RCU context.
5120 */
5121static void lockdep_reset_lock_reg(struct lockdep_map *lock)
5122{
5123 struct pending_free *pf;
5124 unsigned long flags;
5125 int locked;
5126
5127 raw_local_irq_save(flags);
5128 locked = graph_lock();
5129 if (!locked)
5130 goto out_irq;
5131
5132 pf = get_pending_free();
5133 __lockdep_reset_lock(pf, lock);
5134 call_rcu_zapped(pf);
5135
5136 graph_unlock();
5137out_irq:
5138 raw_local_irq_restore(flags);
5139}
5140
5141/*
5142 * Reset a lock. Does not sleep. Ignores debug_locks. Must only be used by the
5143 * lockdep selftests.
5144 */
5145static void lockdep_reset_lock_imm(struct lockdep_map *lock)
5146{
5147 struct pending_free *pf = delayed_free.pf;
5148 unsigned long flags;
5149
5150 raw_local_irq_save(flags);
5151 arch_spin_lock(&lockdep_lock);
5152 __lockdep_reset_lock(pf, lock);
5153 __free_zapped_classes(pf);
5154 arch_spin_unlock(&lockdep_lock);
5155 raw_local_irq_restore(flags);
5156}
5157
5158void lockdep_reset_lock(struct lockdep_map *lock)
5159{
5160 init_data_structures_once();
5161
5162 if (inside_selftest())
5163 lockdep_reset_lock_imm(lock);
5164 else
5165 lockdep_reset_lock_reg(lock);
5166}
5167
5168/* Unregister a dynamically allocated key. */
5169void lockdep_unregister_key(struct lock_class_key *key)
5170{
5171 struct hlist_head *hash_head = keyhashentry(key);
5172 struct lock_class_key *k;
5173 struct pending_free *pf;
5174 unsigned long flags;
5175 bool found = false;
5176
5177 might_sleep();
5178
5179 if (WARN_ON_ONCE(static_obj(key)))
5180 return;
5181
5182 raw_local_irq_save(flags);
5183 if (!graph_lock())
5184 goto out_irq;
5185
5186 pf = get_pending_free();
5187 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
5188 if (k == key) {
5189 hlist_del_rcu(&k->hash_entry);
5190 found = true;
5191 break;
5192 }
5193 }
5194 WARN_ON_ONCE(!found);
5195 __lockdep_free_key_range(pf, key, 1);
5196 call_rcu_zapped(pf);
5197 graph_unlock();
5198out_irq:
5199 raw_local_irq_restore(flags);
5200
5201 /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */
5202 synchronize_rcu();
5203}
5204EXPORT_SYMBOL_GPL(lockdep_unregister_key);
5205
5206void __init lockdep_init(void)
5207{
5208 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
5209
5210 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
5211 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
5212 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
5213 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
5214 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
5215 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
5216 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
5217
5218 printk(" memory used by lock dependency info: %zu kB\n",
5219 (sizeof(lock_classes) +
5220 sizeof(lock_classes_in_use) +
5221 sizeof(classhash_table) +
5222 sizeof(list_entries) +
5223 sizeof(list_entries_in_use) +
5224 sizeof(chainhash_table) +
5225 sizeof(delayed_free)
5226#ifdef CONFIG_PROVE_LOCKING
5227 + sizeof(lock_cq)
5228 + sizeof(lock_chains)
5229 + sizeof(lock_chains_in_use)
5230 + sizeof(chain_hlocks)
5231#endif
5232 ) / 1024
5233 );
5234
5235#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
5236 printk(" memory used for stack traces: %zu kB\n",
5237 (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024
5238 );
5239#endif
5240
5241 printk(" per task-struct memory footprint: %zu bytes\n",
5242 sizeof(((struct task_struct *)NULL)->held_locks));
5243}
5244
5245static void
5246print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
5247 const void *mem_to, struct held_lock *hlock)
5248{
5249 if (!debug_locks_off())
5250 return;
5251 if (debug_locks_silent)
5252 return;
5253
5254 pr_warn("\n");
5255 pr_warn("=========================\n");
5256 pr_warn("WARNING: held lock freed!\n");
5257 print_kernel_ident();
5258 pr_warn("-------------------------\n");
5259 pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
5260 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
5261 print_lock(hlock);
5262 lockdep_print_held_locks(curr);
5263
5264 pr_warn("\nstack backtrace:\n");
5265 dump_stack();
5266}
5267
5268static inline int not_in_range(const void* mem_from, unsigned long mem_len,
5269 const void* lock_from, unsigned long lock_len)
5270{
5271 return lock_from + lock_len <= mem_from ||
5272 mem_from + mem_len <= lock_from;
5273}
5274
5275/*
5276 * Called when kernel memory is freed (or unmapped), or if a lock
5277 * is destroyed or reinitialized - this code checks whether there is
5278 * any held lock in the memory range of <from> to <to>:
5279 */
5280void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
5281{
5282 struct task_struct *curr = current;
5283 struct held_lock *hlock;
5284 unsigned long flags;
5285 int i;
5286
5287 if (unlikely(!debug_locks))
5288 return;
5289
5290 raw_local_irq_save(flags);
5291 for (i = 0; i < curr->lockdep_depth; i++) {
5292 hlock = curr->held_locks + i;
5293
5294 if (not_in_range(mem_from, mem_len, hlock->instance,
5295 sizeof(*hlock->instance)))
5296 continue;
5297
5298 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
5299 break;
5300 }
5301 raw_local_irq_restore(flags);
5302}
5303EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
5304
5305static void print_held_locks_bug(void)
5306{
5307 if (!debug_locks_off())
5308 return;
5309 if (debug_locks_silent)
5310 return;
5311
5312 pr_warn("\n");
5313 pr_warn("====================================\n");
5314 pr_warn("WARNING: %s/%d still has locks held!\n",
5315 current->comm, task_pid_nr(current));
5316 print_kernel_ident();
5317 pr_warn("------------------------------------\n");
5318 lockdep_print_held_locks(current);
5319 pr_warn("\nstack backtrace:\n");
5320 dump_stack();
5321}
5322
5323void debug_check_no_locks_held(void)
5324{
5325 if (unlikely(current->lockdep_depth > 0))
5326 print_held_locks_bug();
5327}
5328EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
5329
5330#ifdef __KERNEL__
5331void debug_show_all_locks(void)
5332{
5333 struct task_struct *g, *p;
5334
5335 if (unlikely(!debug_locks)) {
5336 pr_warn("INFO: lockdep is turned off.\n");
5337 return;
5338 }
5339 pr_warn("\nShowing all locks held in the system:\n");
5340
5341 rcu_read_lock();
5342 for_each_process_thread(g, p) {
5343 if (!p->lockdep_depth)
5344 continue;
5345 lockdep_print_held_locks(p);
5346 touch_nmi_watchdog();
5347 touch_all_softlockup_watchdogs();
5348 }
5349 rcu_read_unlock();
5350
5351 pr_warn("\n");
5352 pr_warn("=============================================\n\n");
5353}
5354EXPORT_SYMBOL_GPL(debug_show_all_locks);
5355#endif
5356
5357/*
5358 * Careful: only use this function if you are sure that
5359 * the task cannot run in parallel!
5360 */
5361void debug_show_held_locks(struct task_struct *task)
5362{
5363 if (unlikely(!debug_locks)) {
5364 printk("INFO: lockdep is turned off.\n");
5365 return;
5366 }
5367 lockdep_print_held_locks(task);
5368}
5369EXPORT_SYMBOL_GPL(debug_show_held_locks);
5370
5371asmlinkage __visible void lockdep_sys_exit(void)
5372{
5373 struct task_struct *curr = current;
5374
5375 if (unlikely(curr->lockdep_depth)) {
5376 if (!debug_locks_off())
5377 return;
5378 pr_warn("\n");
5379 pr_warn("================================================\n");
5380 pr_warn("WARNING: lock held when returning to user space!\n");
5381 print_kernel_ident();
5382 pr_warn("------------------------------------------------\n");
5383 pr_warn("%s/%d is leaving the kernel with locks still held!\n",
5384 curr->comm, curr->pid);
5385 lockdep_print_held_locks(curr);
5386 }
5387
5388 /*
5389 * The lock history for each syscall should be independent. So wipe the
5390 * slate clean on return to userspace.
5391 */
5392 lockdep_invariant_state(false);
5393}
5394
5395void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
5396{
5397 struct task_struct *curr = current;
5398
5399 /* Note: the following can be executed concurrently, so be careful. */
5400 pr_warn("\n");
5401 pr_warn("=============================\n");
5402 pr_warn("WARNING: suspicious RCU usage\n");
5403 print_kernel_ident();
5404 pr_warn("-----------------------------\n");
5405 pr_warn("%s:%d %s!\n", file, line, s);
5406 pr_warn("\nother info that might help us debug this:\n\n");
5407 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
5408 !rcu_lockdep_current_cpu_online()
5409 ? "RCU used illegally from offline CPU!\n"
5410 : !rcu_is_watching()
5411 ? "RCU used illegally from idle CPU!\n"
5412 : "",
5413 rcu_scheduler_active, debug_locks);
5414
5415 /*
5416 * If a CPU is in the RCU-free window in idle (ie: in the section
5417 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
5418 * considers that CPU to be in an "extended quiescent state",
5419 * which means that RCU will be completely ignoring that CPU.
5420 * Therefore, rcu_read_lock() and friends have absolutely no
5421 * effect on a CPU running in that state. In other words, even if
5422 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
5423 * delete data structures out from under it. RCU really has no
5424 * choice here: we need to keep an RCU-free window in idle where
5425 * the CPU may possibly enter into low power mode. This way we can
5426 * notice an extended quiescent state to other CPUs that started a grace
5427 * period. Otherwise we would delay any grace period as long as we run
5428 * in the idle task.
5429 *
5430 * So complain bitterly if someone does call rcu_read_lock(),
5431 * rcu_read_lock_bh() and so on from extended quiescent states.
5432 */
5433 if (!rcu_is_watching())
5434 pr_warn("RCU used illegally from extended quiescent state!\n");
5435
5436 lockdep_print_held_locks(curr);
5437 pr_warn("\nstack backtrace:\n");
5438 dump_stack();
5439}
5440EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);