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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kernel/lockdep.c
4 *
5 * Runtime locking correctness validator
6 *
7 * Started by Ingo Molnar:
8 *
9 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <[email protected]>
10 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
11 *
12 * this code maps all the lock dependencies as they occur in a live kernel
13 * and will warn about the following classes of locking bugs:
14 *
15 * - lock inversion scenarios
16 * - circular lock dependencies
17 * - hardirq/softirq safe/unsafe locking bugs
18 *
19 * Bugs are reported even if the current locking scenario does not cause
20 * any deadlock at this point.
21 *
22 * I.e. if anytime in the past two locks were taken in a different order,
23 * even if it happened for another task, even if those were different
24 * locks (but of the same class as this lock), this code will detect it.
25 *
26 * Thanks to Arjan van de Ven for coming up with the initial idea of
27 * mapping lock dependencies runtime.
28 */
29#define DISABLE_BRANCH_PROFILING
30#include <linux/mutex.h>
31#include <linux/sched.h>
32#include <linux/sched/clock.h>
33#include <linux/sched/task.h>
34#include <linux/sched/mm.h>
35#include <linux/delay.h>
36#include <linux/module.h>
37#include <linux/proc_fs.h>
38#include <linux/seq_file.h>
39#include <linux/spinlock.h>
40#include <linux/kallsyms.h>
41#include <linux/interrupt.h>
42#include <linux/stacktrace.h>
43#include <linux/debug_locks.h>
44#include <linux/irqflags.h>
45#include <linux/utsname.h>
46#include <linux/hash.h>
47#include <linux/ftrace.h>
48#include <linux/stringify.h>
49#include <linux/bitmap.h>
50#include <linux/bitops.h>
51#include <linux/gfp.h>
52#include <linux/random.h>
53#include <linux/jhash.h>
54#include <linux/nmi.h>
55#include <linux/rcupdate.h>
56#include <linux/kprobes.h>
57#include <linux/lockdep.h>
58
59#include <asm/sections.h>
60
61#include "lockdep_internals.h"
62
63#include <trace/events/lock.h>
64
65#ifdef CONFIG_PROVE_LOCKING
66static int prove_locking = 1;
67module_param(prove_locking, int, 0644);
68#else
69#define prove_locking 0
70#endif
71
72#ifdef CONFIG_LOCK_STAT
73static int lock_stat = 1;
74module_param(lock_stat, int, 0644);
75#else
76#define lock_stat 0
77#endif
78
79#ifdef CONFIG_SYSCTL
80static struct ctl_table kern_lockdep_table[] = {
81#ifdef CONFIG_PROVE_LOCKING
82 {
83 .procname = "prove_locking",
84 .data = &prove_locking,
85 .maxlen = sizeof(int),
86 .mode = 0644,
87 .proc_handler = proc_dointvec,
88 },
89#endif /* CONFIG_PROVE_LOCKING */
90#ifdef CONFIG_LOCK_STAT
91 {
92 .procname = "lock_stat",
93 .data = &lock_stat,
94 .maxlen = sizeof(int),
95 .mode = 0644,
96 .proc_handler = proc_dointvec,
97 },
98#endif /* CONFIG_LOCK_STAT */
99 { }
100};
101
102static __init int kernel_lockdep_sysctls_init(void)
103{
104 register_sysctl_init("kernel", kern_lockdep_table);
105 return 0;
106}
107late_initcall(kernel_lockdep_sysctls_init);
108#endif /* CONFIG_SYSCTL */
109
110DEFINE_PER_CPU(unsigned int, lockdep_recursion);
111EXPORT_PER_CPU_SYMBOL_GPL(lockdep_recursion);
112
113static __always_inline bool lockdep_enabled(void)
114{
115 if (!debug_locks)
116 return false;
117
118 if (this_cpu_read(lockdep_recursion))
119 return false;
120
121 if (current->lockdep_recursion)
122 return false;
123
124 return true;
125}
126
127/*
128 * lockdep_lock: protects the lockdep graph, the hashes and the
129 * class/list/hash allocators.
130 *
131 * This is one of the rare exceptions where it's justified
132 * to use a raw spinlock - we really dont want the spinlock
133 * code to recurse back into the lockdep code...
134 */
135static arch_spinlock_t __lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
136static struct task_struct *__owner;
137
138static inline void lockdep_lock(void)
139{
140 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
141
142 __this_cpu_inc(lockdep_recursion);
143 arch_spin_lock(&__lock);
144 __owner = current;
145}
146
147static inline void lockdep_unlock(void)
148{
149 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
150
151 if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current))
152 return;
153
154 __owner = NULL;
155 arch_spin_unlock(&__lock);
156 __this_cpu_dec(lockdep_recursion);
157}
158
159static inline bool lockdep_assert_locked(void)
160{
161 return DEBUG_LOCKS_WARN_ON(__owner != current);
162}
163
164static struct task_struct *lockdep_selftest_task_struct;
165
166
167static int graph_lock(void)
168{
169 lockdep_lock();
170 /*
171 * Make sure that if another CPU detected a bug while
172 * walking the graph we dont change it (while the other
173 * CPU is busy printing out stuff with the graph lock
174 * dropped already)
175 */
176 if (!debug_locks) {
177 lockdep_unlock();
178 return 0;
179 }
180 return 1;
181}
182
183static inline void graph_unlock(void)
184{
185 lockdep_unlock();
186}
187
188/*
189 * Turn lock debugging off and return with 0 if it was off already,
190 * and also release the graph lock:
191 */
192static inline int debug_locks_off_graph_unlock(void)
193{
194 int ret = debug_locks_off();
195
196 lockdep_unlock();
197
198 return ret;
199}
200
201unsigned long nr_list_entries;
202static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
203static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES);
204
205/*
206 * All data structures here are protected by the global debug_lock.
207 *
208 * nr_lock_classes is the number of elements of lock_classes[] that is
209 * in use.
210 */
211#define KEYHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
212#define KEYHASH_SIZE (1UL << KEYHASH_BITS)
213static struct hlist_head lock_keys_hash[KEYHASH_SIZE];
214unsigned long nr_lock_classes;
215unsigned long nr_zapped_classes;
216unsigned long max_lock_class_idx;
217struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
218DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS);
219
220static inline struct lock_class *hlock_class(struct held_lock *hlock)
221{
222 unsigned int class_idx = hlock->class_idx;
223
224 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfield */
225 barrier();
226
227 if (!test_bit(class_idx, lock_classes_in_use)) {
228 /*
229 * Someone passed in garbage, we give up.
230 */
231 DEBUG_LOCKS_WARN_ON(1);
232 return NULL;
233 }
234
235 /*
236 * At this point, if the passed hlock->class_idx is still garbage,
237 * we just have to live with it
238 */
239 return lock_classes + class_idx;
240}
241
242#ifdef CONFIG_LOCK_STAT
243static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
244
245static inline u64 lockstat_clock(void)
246{
247 return local_clock();
248}
249
250static int lock_point(unsigned long points[], unsigned long ip)
251{
252 int i;
253
254 for (i = 0; i < LOCKSTAT_POINTS; i++) {
255 if (points[i] == 0) {
256 points[i] = ip;
257 break;
258 }
259 if (points[i] == ip)
260 break;
261 }
262
263 return i;
264}
265
266static void lock_time_inc(struct lock_time *lt, u64 time)
267{
268 if (time > lt->max)
269 lt->max = time;
270
271 if (time < lt->min || !lt->nr)
272 lt->min = time;
273
274 lt->total += time;
275 lt->nr++;
276}
277
278static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
279{
280 if (!src->nr)
281 return;
282
283 if (src->max > dst->max)
284 dst->max = src->max;
285
286 if (src->min < dst->min || !dst->nr)
287 dst->min = src->min;
288
289 dst->total += src->total;
290 dst->nr += src->nr;
291}
292
293struct lock_class_stats lock_stats(struct lock_class *class)
294{
295 struct lock_class_stats stats;
296 int cpu, i;
297
298 memset(&stats, 0, sizeof(struct lock_class_stats));
299 for_each_possible_cpu(cpu) {
300 struct lock_class_stats *pcs =
301 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
302
303 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
304 stats.contention_point[i] += pcs->contention_point[i];
305
306 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
307 stats.contending_point[i] += pcs->contending_point[i];
308
309 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
310 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
311
312 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
313 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
314
315 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
316 stats.bounces[i] += pcs->bounces[i];
317 }
318
319 return stats;
320}
321
322void clear_lock_stats(struct lock_class *class)
323{
324 int cpu;
325
326 for_each_possible_cpu(cpu) {
327 struct lock_class_stats *cpu_stats =
328 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
329
330 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
331 }
332 memset(class->contention_point, 0, sizeof(class->contention_point));
333 memset(class->contending_point, 0, sizeof(class->contending_point));
334}
335
336static struct lock_class_stats *get_lock_stats(struct lock_class *class)
337{
338 return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes];
339}
340
341static void lock_release_holdtime(struct held_lock *hlock)
342{
343 struct lock_class_stats *stats;
344 u64 holdtime;
345
346 if (!lock_stat)
347 return;
348
349 holdtime = lockstat_clock() - hlock->holdtime_stamp;
350
351 stats = get_lock_stats(hlock_class(hlock));
352 if (hlock->read)
353 lock_time_inc(&stats->read_holdtime, holdtime);
354 else
355 lock_time_inc(&stats->write_holdtime, holdtime);
356}
357#else
358static inline void lock_release_holdtime(struct held_lock *hlock)
359{
360}
361#endif
362
363/*
364 * We keep a global list of all lock classes. The list is only accessed with
365 * the lockdep spinlock lock held. free_lock_classes is a list with free
366 * elements. These elements are linked together by the lock_entry member in
367 * struct lock_class.
368 */
369static LIST_HEAD(all_lock_classes);
370static LIST_HEAD(free_lock_classes);
371
372/**
373 * struct pending_free - information about data structures about to be freed
374 * @zapped: Head of a list with struct lock_class elements.
375 * @lock_chains_being_freed: Bitmap that indicates which lock_chains[] elements
376 * are about to be freed.
377 */
378struct pending_free {
379 struct list_head zapped;
380 DECLARE_BITMAP(lock_chains_being_freed, MAX_LOCKDEP_CHAINS);
381};
382
383/**
384 * struct delayed_free - data structures used for delayed freeing
385 *
386 * A data structure for delayed freeing of data structures that may be
387 * accessed by RCU readers at the time these were freed.
388 *
389 * @rcu_head: Used to schedule an RCU callback for freeing data structures.
390 * @index: Index of @pf to which freed data structures are added.
391 * @scheduled: Whether or not an RCU callback has been scheduled.
392 * @pf: Array with information about data structures about to be freed.
393 */
394static struct delayed_free {
395 struct rcu_head rcu_head;
396 int index;
397 int scheduled;
398 struct pending_free pf[2];
399} delayed_free;
400
401/*
402 * The lockdep classes are in a hash-table as well, for fast lookup:
403 */
404#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
405#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
406#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
407#define classhashentry(key) (classhash_table + __classhashfn((key)))
408
409static struct hlist_head classhash_table[CLASSHASH_SIZE];
410
411/*
412 * We put the lock dependency chains into a hash-table as well, to cache
413 * their existence:
414 */
415#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
416#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
417#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
418#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
419
420static struct hlist_head chainhash_table[CHAINHASH_SIZE];
421
422/*
423 * the id of held_lock
424 */
425static inline u16 hlock_id(struct held_lock *hlock)
426{
427 BUILD_BUG_ON(MAX_LOCKDEP_KEYS_BITS + 2 > 16);
428
429 return (hlock->class_idx | (hlock->read << MAX_LOCKDEP_KEYS_BITS));
430}
431
432static inline unsigned int chain_hlock_class_idx(u16 hlock_id)
433{
434 return hlock_id & (MAX_LOCKDEP_KEYS - 1);
435}
436
437/*
438 * The hash key of the lock dependency chains is a hash itself too:
439 * it's a hash of all locks taken up to that lock, including that lock.
440 * It's a 64-bit hash, because it's important for the keys to be
441 * unique.
442 */
443static inline u64 iterate_chain_key(u64 key, u32 idx)
444{
445 u32 k0 = key, k1 = key >> 32;
446
447 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
448
449 return k0 | (u64)k1 << 32;
450}
451
452void lockdep_init_task(struct task_struct *task)
453{
454 task->lockdep_depth = 0; /* no locks held yet */
455 task->curr_chain_key = INITIAL_CHAIN_KEY;
456 task->lockdep_recursion = 0;
457}
458
459static __always_inline void lockdep_recursion_inc(void)
460{
461 __this_cpu_inc(lockdep_recursion);
462}
463
464static __always_inline void lockdep_recursion_finish(void)
465{
466 if (WARN_ON_ONCE(__this_cpu_dec_return(lockdep_recursion)))
467 __this_cpu_write(lockdep_recursion, 0);
468}
469
470void lockdep_set_selftest_task(struct task_struct *task)
471{
472 lockdep_selftest_task_struct = task;
473}
474
475/*
476 * Debugging switches:
477 */
478
479#define VERBOSE 0
480#define VERY_VERBOSE 0
481
482#if VERBOSE
483# define HARDIRQ_VERBOSE 1
484# define SOFTIRQ_VERBOSE 1
485#else
486# define HARDIRQ_VERBOSE 0
487# define SOFTIRQ_VERBOSE 0
488#endif
489
490#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
491/*
492 * Quick filtering for interesting events:
493 */
494static int class_filter(struct lock_class *class)
495{
496#if 0
497 /* Example */
498 if (class->name_version == 1 &&
499 !strcmp(class->name, "lockname"))
500 return 1;
501 if (class->name_version == 1 &&
502 !strcmp(class->name, "&struct->lockfield"))
503 return 1;
504#endif
505 /* Filter everything else. 1 would be to allow everything else */
506 return 0;
507}
508#endif
509
510static int verbose(struct lock_class *class)
511{
512#if VERBOSE
513 return class_filter(class);
514#endif
515 return 0;
516}
517
518static void print_lockdep_off(const char *bug_msg)
519{
520 printk(KERN_DEBUG "%s\n", bug_msg);
521 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
522#ifdef CONFIG_LOCK_STAT
523 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
524#endif
525}
526
527unsigned long nr_stack_trace_entries;
528
529#ifdef CONFIG_PROVE_LOCKING
530/**
531 * struct lock_trace - single stack backtrace
532 * @hash_entry: Entry in a stack_trace_hash[] list.
533 * @hash: jhash() of @entries.
534 * @nr_entries: Number of entries in @entries.
535 * @entries: Actual stack backtrace.
536 */
537struct lock_trace {
538 struct hlist_node hash_entry;
539 u32 hash;
540 u32 nr_entries;
541 unsigned long entries[] __aligned(sizeof(unsigned long));
542};
543#define LOCK_TRACE_SIZE_IN_LONGS \
544 (sizeof(struct lock_trace) / sizeof(unsigned long))
545/*
546 * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock.
547 */
548static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
549static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE];
550
551static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2)
552{
553 return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries &&
554 memcmp(t1->entries, t2->entries,
555 t1->nr_entries * sizeof(t1->entries[0])) == 0;
556}
557
558static struct lock_trace *save_trace(void)
559{
560 struct lock_trace *trace, *t2;
561 struct hlist_head *hash_head;
562 u32 hash;
563 int max_entries;
564
565 BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE);
566 BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES);
567
568 trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries);
569 max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries -
570 LOCK_TRACE_SIZE_IN_LONGS;
571
572 if (max_entries <= 0) {
573 if (!debug_locks_off_graph_unlock())
574 return NULL;
575
576 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
577 dump_stack();
578
579 return NULL;
580 }
581 trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
582
583 hash = jhash(trace->entries, trace->nr_entries *
584 sizeof(trace->entries[0]), 0);
585 trace->hash = hash;
586 hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1));
587 hlist_for_each_entry(t2, hash_head, hash_entry) {
588 if (traces_identical(trace, t2))
589 return t2;
590 }
591 nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries;
592 hlist_add_head(&trace->hash_entry, hash_head);
593
594 return trace;
595}
596
597/* Return the number of stack traces in the stack_trace[] array. */
598u64 lockdep_stack_trace_count(void)
599{
600 struct lock_trace *trace;
601 u64 c = 0;
602 int i;
603
604 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) {
605 hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) {
606 c++;
607 }
608 }
609
610 return c;
611}
612
613/* Return the number of stack hash chains that have at least one stack trace. */
614u64 lockdep_stack_hash_count(void)
615{
616 u64 c = 0;
617 int i;
618
619 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++)
620 if (!hlist_empty(&stack_trace_hash[i]))
621 c++;
622
623 return c;
624}
625#endif
626
627unsigned int nr_hardirq_chains;
628unsigned int nr_softirq_chains;
629unsigned int nr_process_chains;
630unsigned int max_lockdep_depth;
631
632#ifdef CONFIG_DEBUG_LOCKDEP
633/*
634 * Various lockdep statistics:
635 */
636DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
637#endif
638
639#ifdef CONFIG_PROVE_LOCKING
640/*
641 * Locking printouts:
642 */
643
644#define __USAGE(__STATE) \
645 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
646 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
647 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
648 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
649
650static const char *usage_str[] =
651{
652#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
653#include "lockdep_states.h"
654#undef LOCKDEP_STATE
655 [LOCK_USED] = "INITIAL USE",
656 [LOCK_USED_READ] = "INITIAL READ USE",
657 /* abused as string storage for verify_lock_unused() */
658 [LOCK_USAGE_STATES] = "IN-NMI",
659};
660#endif
661
662const char *__get_key_name(const struct lockdep_subclass_key *key, char *str)
663{
664 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
665}
666
667static inline unsigned long lock_flag(enum lock_usage_bit bit)
668{
669 return 1UL << bit;
670}
671
672static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
673{
674 /*
675 * The usage character defaults to '.' (i.e., irqs disabled and not in
676 * irq context), which is the safest usage category.
677 */
678 char c = '.';
679
680 /*
681 * The order of the following usage checks matters, which will
682 * result in the outcome character as follows:
683 *
684 * - '+': irq is enabled and not in irq context
685 * - '-': in irq context and irq is disabled
686 * - '?': in irq context and irq is enabled
687 */
688 if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) {
689 c = '+';
690 if (class->usage_mask & lock_flag(bit))
691 c = '?';
692 } else if (class->usage_mask & lock_flag(bit))
693 c = '-';
694
695 return c;
696}
697
698void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
699{
700 int i = 0;
701
702#define LOCKDEP_STATE(__STATE) \
703 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
704 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
705#include "lockdep_states.h"
706#undef LOCKDEP_STATE
707
708 usage[i] = '\0';
709}
710
711static void __print_lock_name(struct lock_class *class)
712{
713 char str[KSYM_NAME_LEN];
714 const char *name;
715
716 name = class->name;
717 if (!name) {
718 name = __get_key_name(class->key, str);
719 printk(KERN_CONT "%s", name);
720 } else {
721 printk(KERN_CONT "%s", name);
722 if (class->name_version > 1)
723 printk(KERN_CONT "#%d", class->name_version);
724 if (class->subclass)
725 printk(KERN_CONT "/%d", class->subclass);
726 }
727}
728
729static void print_lock_name(struct lock_class *class)
730{
731 char usage[LOCK_USAGE_CHARS];
732
733 get_usage_chars(class, usage);
734
735 printk(KERN_CONT " (");
736 __print_lock_name(class);
737 printk(KERN_CONT "){%s}-{%d:%d}", usage,
738 class->wait_type_outer ?: class->wait_type_inner,
739 class->wait_type_inner);
740}
741
742static void print_lockdep_cache(struct lockdep_map *lock)
743{
744 const char *name;
745 char str[KSYM_NAME_LEN];
746
747 name = lock->name;
748 if (!name)
749 name = __get_key_name(lock->key->subkeys, str);
750
751 printk(KERN_CONT "%s", name);
752}
753
754static void print_lock(struct held_lock *hlock)
755{
756 /*
757 * We can be called locklessly through debug_show_all_locks() so be
758 * extra careful, the hlock might have been released and cleared.
759 *
760 * If this indeed happens, lets pretend it does not hurt to continue
761 * to print the lock unless the hlock class_idx does not point to a
762 * registered class. The rationale here is: since we don't attempt
763 * to distinguish whether we are in this situation, if it just
764 * happened we can't count on class_idx to tell either.
765 */
766 struct lock_class *lock = hlock_class(hlock);
767
768 if (!lock) {
769 printk(KERN_CONT "<RELEASED>\n");
770 return;
771 }
772
773 printk(KERN_CONT "%px", hlock->instance);
774 print_lock_name(lock);
775 printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
776}
777
778static void lockdep_print_held_locks(struct task_struct *p)
779{
780 int i, depth = READ_ONCE(p->lockdep_depth);
781
782 if (!depth)
783 printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p));
784 else
785 printk("%d lock%s held by %s/%d:\n", depth,
786 depth > 1 ? "s" : "", p->comm, task_pid_nr(p));
787 /*
788 * It's not reliable to print a task's held locks if it's not sleeping
789 * and it's not the current task.
790 */
791 if (p != current && task_is_running(p))
792 return;
793 for (i = 0; i < depth; i++) {
794 printk(" #%d: ", i);
795 print_lock(p->held_locks + i);
796 }
797}
798
799static void print_kernel_ident(void)
800{
801 printk("%s %.*s %s\n", init_utsname()->release,
802 (int)strcspn(init_utsname()->version, " "),
803 init_utsname()->version,
804 print_tainted());
805}
806
807static int very_verbose(struct lock_class *class)
808{
809#if VERY_VERBOSE
810 return class_filter(class);
811#endif
812 return 0;
813}
814
815/*
816 * Is this the address of a static object:
817 */
818#ifdef __KERNEL__
819/*
820 * Check if an address is part of freed initmem. After initmem is freed,
821 * memory can be allocated from it, and such allocations would then have
822 * addresses within the range [_stext, _end].
823 */
824#ifndef arch_is_kernel_initmem_freed
825static int arch_is_kernel_initmem_freed(unsigned long addr)
826{
827 if (system_state < SYSTEM_FREEING_INITMEM)
828 return 0;
829
830 return init_section_contains((void *)addr, 1);
831}
832#endif
833
834static int static_obj(const void *obj)
835{
836 unsigned long start = (unsigned long) &_stext,
837 end = (unsigned long) &_end,
838 addr = (unsigned long) obj;
839
840 if (arch_is_kernel_initmem_freed(addr))
841 return 0;
842
843 /*
844 * static variable?
845 */
846 if ((addr >= start) && (addr < end))
847 return 1;
848
849 /*
850 * in-kernel percpu var?
851 */
852 if (is_kernel_percpu_address(addr))
853 return 1;
854
855 /*
856 * module static or percpu var?
857 */
858 return is_module_address(addr) || is_module_percpu_address(addr);
859}
860#endif
861
862/*
863 * To make lock name printouts unique, we calculate a unique
864 * class->name_version generation counter. The caller must hold the graph
865 * lock.
866 */
867static int count_matching_names(struct lock_class *new_class)
868{
869 struct lock_class *class;
870 int count = 0;
871
872 if (!new_class->name)
873 return 0;
874
875 list_for_each_entry(class, &all_lock_classes, lock_entry) {
876 if (new_class->key - new_class->subclass == class->key)
877 return class->name_version;
878 if (class->name && !strcmp(class->name, new_class->name))
879 count = max(count, class->name_version);
880 }
881
882 return count + 1;
883}
884
885/* used from NMI context -- must be lockless */
886static noinstr struct lock_class *
887look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
888{
889 struct lockdep_subclass_key *key;
890 struct hlist_head *hash_head;
891 struct lock_class *class;
892
893 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
894 instrumentation_begin();
895 debug_locks_off();
896 printk(KERN_ERR
897 "BUG: looking up invalid subclass: %u\n", subclass);
898 printk(KERN_ERR
899 "turning off the locking correctness validator.\n");
900 dump_stack();
901 instrumentation_end();
902 return NULL;
903 }
904
905 /*
906 * If it is not initialised then it has never been locked,
907 * so it won't be present in the hash table.
908 */
909 if (unlikely(!lock->key))
910 return NULL;
911
912 /*
913 * NOTE: the class-key must be unique. For dynamic locks, a static
914 * lock_class_key variable is passed in through the mutex_init()
915 * (or spin_lock_init()) call - which acts as the key. For static
916 * locks we use the lock object itself as the key.
917 */
918 BUILD_BUG_ON(sizeof(struct lock_class_key) >
919 sizeof(struct lockdep_map));
920
921 key = lock->key->subkeys + subclass;
922
923 hash_head = classhashentry(key);
924
925 /*
926 * We do an RCU walk of the hash, see lockdep_free_key_range().
927 */
928 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
929 return NULL;
930
931 hlist_for_each_entry_rcu_notrace(class, hash_head, hash_entry) {
932 if (class->key == key) {
933 /*
934 * Huh! same key, different name? Did someone trample
935 * on some memory? We're most confused.
936 */
937 WARN_ONCE(class->name != lock->name &&
938 lock->key != &__lockdep_no_validate__,
939 "Looking for class \"%s\" with key %ps, but found a different class \"%s\" with the same key\n",
940 lock->name, lock->key, class->name);
941 return class;
942 }
943 }
944
945 return NULL;
946}
947
948/*
949 * Static locks do not have their class-keys yet - for them the key is
950 * the lock object itself. If the lock is in the per cpu area, the
951 * canonical address of the lock (per cpu offset removed) is used.
952 */
953static bool assign_lock_key(struct lockdep_map *lock)
954{
955 unsigned long can_addr, addr = (unsigned long)lock;
956
957#ifdef __KERNEL__
958 /*
959 * lockdep_free_key_range() assumes that struct lock_class_key
960 * objects do not overlap. Since we use the address of lock
961 * objects as class key for static objects, check whether the
962 * size of lock_class_key objects does not exceed the size of
963 * the smallest lock object.
964 */
965 BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
966#endif
967
968 if (__is_kernel_percpu_address(addr, &can_addr))
969 lock->key = (void *)can_addr;
970 else if (__is_module_percpu_address(addr, &can_addr))
971 lock->key = (void *)can_addr;
972 else if (static_obj(lock))
973 lock->key = (void *)lock;
974 else {
975 /* Debug-check: all keys must be persistent! */
976 debug_locks_off();
977 pr_err("INFO: trying to register non-static key.\n");
978 pr_err("The code is fine but needs lockdep annotation, or maybe\n");
979 pr_err("you didn't initialize this object before use?\n");
980 pr_err("turning off the locking correctness validator.\n");
981 dump_stack();
982 return false;
983 }
984
985 return true;
986}
987
988#ifdef CONFIG_DEBUG_LOCKDEP
989
990/* Check whether element @e occurs in list @h */
991static bool in_list(struct list_head *e, struct list_head *h)
992{
993 struct list_head *f;
994
995 list_for_each(f, h) {
996 if (e == f)
997 return true;
998 }
999
1000 return false;
1001}
1002
1003/*
1004 * Check whether entry @e occurs in any of the locks_after or locks_before
1005 * lists.
1006 */
1007static bool in_any_class_list(struct list_head *e)
1008{
1009 struct lock_class *class;
1010 int i;
1011
1012 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1013 class = &lock_classes[i];
1014 if (in_list(e, &class->locks_after) ||
1015 in_list(e, &class->locks_before))
1016 return true;
1017 }
1018 return false;
1019}
1020
1021static bool class_lock_list_valid(struct lock_class *c, struct list_head *h)
1022{
1023 struct lock_list *e;
1024
1025 list_for_each_entry(e, h, entry) {
1026 if (e->links_to != c) {
1027 printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s",
1028 c->name ? : "(?)",
1029 (unsigned long)(e - list_entries),
1030 e->links_to && e->links_to->name ?
1031 e->links_to->name : "(?)",
1032 e->class && e->class->name ? e->class->name :
1033 "(?)");
1034 return false;
1035 }
1036 }
1037 return true;
1038}
1039
1040#ifdef CONFIG_PROVE_LOCKING
1041static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1042#endif
1043
1044static bool check_lock_chain_key(struct lock_chain *chain)
1045{
1046#ifdef CONFIG_PROVE_LOCKING
1047 u64 chain_key = INITIAL_CHAIN_KEY;
1048 int i;
1049
1050 for (i = chain->base; i < chain->base + chain->depth; i++)
1051 chain_key = iterate_chain_key(chain_key, chain_hlocks[i]);
1052 /*
1053 * The 'unsigned long long' casts avoid that a compiler warning
1054 * is reported when building tools/lib/lockdep.
1055 */
1056 if (chain->chain_key != chain_key) {
1057 printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n",
1058 (unsigned long long)(chain - lock_chains),
1059 (unsigned long long)chain->chain_key,
1060 (unsigned long long)chain_key);
1061 return false;
1062 }
1063#endif
1064 return true;
1065}
1066
1067static bool in_any_zapped_class_list(struct lock_class *class)
1068{
1069 struct pending_free *pf;
1070 int i;
1071
1072 for (i = 0, pf = delayed_free.pf; i < ARRAY_SIZE(delayed_free.pf); i++, pf++) {
1073 if (in_list(&class->lock_entry, &pf->zapped))
1074 return true;
1075 }
1076
1077 return false;
1078}
1079
1080static bool __check_data_structures(void)
1081{
1082 struct lock_class *class;
1083 struct lock_chain *chain;
1084 struct hlist_head *head;
1085 struct lock_list *e;
1086 int i;
1087
1088 /* Check whether all classes occur in a lock list. */
1089 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1090 class = &lock_classes[i];
1091 if (!in_list(&class->lock_entry, &all_lock_classes) &&
1092 !in_list(&class->lock_entry, &free_lock_classes) &&
1093 !in_any_zapped_class_list(class)) {
1094 printk(KERN_INFO "class %px/%s is not in any class list\n",
1095 class, class->name ? : "(?)");
1096 return false;
1097 }
1098 }
1099
1100 /* Check whether all classes have valid lock lists. */
1101 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1102 class = &lock_classes[i];
1103 if (!class_lock_list_valid(class, &class->locks_before))
1104 return false;
1105 if (!class_lock_list_valid(class, &class->locks_after))
1106 return false;
1107 }
1108
1109 /* Check the chain_key of all lock chains. */
1110 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
1111 head = chainhash_table + i;
1112 hlist_for_each_entry_rcu(chain, head, entry) {
1113 if (!check_lock_chain_key(chain))
1114 return false;
1115 }
1116 }
1117
1118 /*
1119 * Check whether all list entries that are in use occur in a class
1120 * lock list.
1121 */
1122 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1123 e = list_entries + i;
1124 if (!in_any_class_list(&e->entry)) {
1125 printk(KERN_INFO "list entry %d is not in any class list; class %s <> %s\n",
1126 (unsigned int)(e - list_entries),
1127 e->class->name ? : "(?)",
1128 e->links_to->name ? : "(?)");
1129 return false;
1130 }
1131 }
1132
1133 /*
1134 * Check whether all list entries that are not in use do not occur in
1135 * a class lock list.
1136 */
1137 for_each_clear_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1138 e = list_entries + i;
1139 if (in_any_class_list(&e->entry)) {
1140 printk(KERN_INFO "list entry %d occurs in a class list; class %s <> %s\n",
1141 (unsigned int)(e - list_entries),
1142 e->class && e->class->name ? e->class->name :
1143 "(?)",
1144 e->links_to && e->links_to->name ?
1145 e->links_to->name : "(?)");
1146 return false;
1147 }
1148 }
1149
1150 return true;
1151}
1152
1153int check_consistency = 0;
1154module_param(check_consistency, int, 0644);
1155
1156static void check_data_structures(void)
1157{
1158 static bool once = false;
1159
1160 if (check_consistency && !once) {
1161 if (!__check_data_structures()) {
1162 once = true;
1163 WARN_ON(once);
1164 }
1165 }
1166}
1167
1168#else /* CONFIG_DEBUG_LOCKDEP */
1169
1170static inline void check_data_structures(void) { }
1171
1172#endif /* CONFIG_DEBUG_LOCKDEP */
1173
1174static void init_chain_block_buckets(void);
1175
1176/*
1177 * Initialize the lock_classes[] array elements, the free_lock_classes list
1178 * and also the delayed_free structure.
1179 */
1180static void init_data_structures_once(void)
1181{
1182 static bool __read_mostly ds_initialized, rcu_head_initialized;
1183 int i;
1184
1185 if (likely(rcu_head_initialized))
1186 return;
1187
1188 if (system_state >= SYSTEM_SCHEDULING) {
1189 init_rcu_head(&delayed_free.rcu_head);
1190 rcu_head_initialized = true;
1191 }
1192
1193 if (ds_initialized)
1194 return;
1195
1196 ds_initialized = true;
1197
1198 INIT_LIST_HEAD(&delayed_free.pf[0].zapped);
1199 INIT_LIST_HEAD(&delayed_free.pf[1].zapped);
1200
1201 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1202 list_add_tail(&lock_classes[i].lock_entry, &free_lock_classes);
1203 INIT_LIST_HEAD(&lock_classes[i].locks_after);
1204 INIT_LIST_HEAD(&lock_classes[i].locks_before);
1205 }
1206 init_chain_block_buckets();
1207}
1208
1209static inline struct hlist_head *keyhashentry(const struct lock_class_key *key)
1210{
1211 unsigned long hash = hash_long((uintptr_t)key, KEYHASH_BITS);
1212
1213 return lock_keys_hash + hash;
1214}
1215
1216/* Register a dynamically allocated key. */
1217void lockdep_register_key(struct lock_class_key *key)
1218{
1219 struct hlist_head *hash_head;
1220 struct lock_class_key *k;
1221 unsigned long flags;
1222
1223 if (WARN_ON_ONCE(static_obj(key)))
1224 return;
1225 hash_head = keyhashentry(key);
1226
1227 raw_local_irq_save(flags);
1228 if (!graph_lock())
1229 goto restore_irqs;
1230 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1231 if (WARN_ON_ONCE(k == key))
1232 goto out_unlock;
1233 }
1234 hlist_add_head_rcu(&key->hash_entry, hash_head);
1235out_unlock:
1236 graph_unlock();
1237restore_irqs:
1238 raw_local_irq_restore(flags);
1239}
1240EXPORT_SYMBOL_GPL(lockdep_register_key);
1241
1242/* Check whether a key has been registered as a dynamic key. */
1243static bool is_dynamic_key(const struct lock_class_key *key)
1244{
1245 struct hlist_head *hash_head;
1246 struct lock_class_key *k;
1247 bool found = false;
1248
1249 if (WARN_ON_ONCE(static_obj(key)))
1250 return false;
1251
1252 /*
1253 * If lock debugging is disabled lock_keys_hash[] may contain
1254 * pointers to memory that has already been freed. Avoid triggering
1255 * a use-after-free in that case by returning early.
1256 */
1257 if (!debug_locks)
1258 return true;
1259
1260 hash_head = keyhashentry(key);
1261
1262 rcu_read_lock();
1263 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1264 if (k == key) {
1265 found = true;
1266 break;
1267 }
1268 }
1269 rcu_read_unlock();
1270
1271 return found;
1272}
1273
1274/*
1275 * Register a lock's class in the hash-table, if the class is not present
1276 * yet. Otherwise we look it up. We cache the result in the lock object
1277 * itself, so actual lookup of the hash should be once per lock object.
1278 */
1279static struct lock_class *
1280register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
1281{
1282 struct lockdep_subclass_key *key;
1283 struct hlist_head *hash_head;
1284 struct lock_class *class;
1285 int idx;
1286
1287 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1288
1289 class = look_up_lock_class(lock, subclass);
1290 if (likely(class))
1291 goto out_set_class_cache;
1292
1293 if (!lock->key) {
1294 if (!assign_lock_key(lock))
1295 return NULL;
1296 } else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) {
1297 return NULL;
1298 }
1299
1300 key = lock->key->subkeys + subclass;
1301 hash_head = classhashentry(key);
1302
1303 if (!graph_lock()) {
1304 return NULL;
1305 }
1306 /*
1307 * We have to do the hash-walk again, to avoid races
1308 * with another CPU:
1309 */
1310 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
1311 if (class->key == key)
1312 goto out_unlock_set;
1313 }
1314
1315 init_data_structures_once();
1316
1317 /* Allocate a new lock class and add it to the hash. */
1318 class = list_first_entry_or_null(&free_lock_classes, typeof(*class),
1319 lock_entry);
1320 if (!class) {
1321 if (!debug_locks_off_graph_unlock()) {
1322 return NULL;
1323 }
1324
1325 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
1326 dump_stack();
1327 return NULL;
1328 }
1329 nr_lock_classes++;
1330 __set_bit(class - lock_classes, lock_classes_in_use);
1331 debug_atomic_inc(nr_unused_locks);
1332 class->key = key;
1333 class->name = lock->name;
1334 class->subclass = subclass;
1335 WARN_ON_ONCE(!list_empty(&class->locks_before));
1336 WARN_ON_ONCE(!list_empty(&class->locks_after));
1337 class->name_version = count_matching_names(class);
1338 class->wait_type_inner = lock->wait_type_inner;
1339 class->wait_type_outer = lock->wait_type_outer;
1340 class->lock_type = lock->lock_type;
1341 /*
1342 * We use RCU's safe list-add method to make
1343 * parallel walking of the hash-list safe:
1344 */
1345 hlist_add_head_rcu(&class->hash_entry, hash_head);
1346 /*
1347 * Remove the class from the free list and add it to the global list
1348 * of classes.
1349 */
1350 list_move_tail(&class->lock_entry, &all_lock_classes);
1351 idx = class - lock_classes;
1352 if (idx > max_lock_class_idx)
1353 max_lock_class_idx = idx;
1354
1355 if (verbose(class)) {
1356 graph_unlock();
1357
1358 printk("\nnew class %px: %s", class->key, class->name);
1359 if (class->name_version > 1)
1360 printk(KERN_CONT "#%d", class->name_version);
1361 printk(KERN_CONT "\n");
1362 dump_stack();
1363
1364 if (!graph_lock()) {
1365 return NULL;
1366 }
1367 }
1368out_unlock_set:
1369 graph_unlock();
1370
1371out_set_class_cache:
1372 if (!subclass || force)
1373 lock->class_cache[0] = class;
1374 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
1375 lock->class_cache[subclass] = class;
1376
1377 /*
1378 * Hash collision, did we smoke some? We found a class with a matching
1379 * hash but the subclass -- which is hashed in -- didn't match.
1380 */
1381 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
1382 return NULL;
1383
1384 return class;
1385}
1386
1387#ifdef CONFIG_PROVE_LOCKING
1388/*
1389 * Allocate a lockdep entry. (assumes the graph_lock held, returns
1390 * with NULL on failure)
1391 */
1392static struct lock_list *alloc_list_entry(void)
1393{
1394 int idx = find_first_zero_bit(list_entries_in_use,
1395 ARRAY_SIZE(list_entries));
1396
1397 if (idx >= ARRAY_SIZE(list_entries)) {
1398 if (!debug_locks_off_graph_unlock())
1399 return NULL;
1400
1401 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
1402 dump_stack();
1403 return NULL;
1404 }
1405 nr_list_entries++;
1406 __set_bit(idx, list_entries_in_use);
1407 return list_entries + idx;
1408}
1409
1410/*
1411 * Add a new dependency to the head of the list:
1412 */
1413static int add_lock_to_list(struct lock_class *this,
1414 struct lock_class *links_to, struct list_head *head,
1415 u16 distance, u8 dep,
1416 const struct lock_trace *trace)
1417{
1418 struct lock_list *entry;
1419 /*
1420 * Lock not present yet - get a new dependency struct and
1421 * add it to the list:
1422 */
1423 entry = alloc_list_entry();
1424 if (!entry)
1425 return 0;
1426
1427 entry->class = this;
1428 entry->links_to = links_to;
1429 entry->dep = dep;
1430 entry->distance = distance;
1431 entry->trace = trace;
1432 /*
1433 * Both allocation and removal are done under the graph lock; but
1434 * iteration is under RCU-sched; see look_up_lock_class() and
1435 * lockdep_free_key_range().
1436 */
1437 list_add_tail_rcu(&entry->entry, head);
1438
1439 return 1;
1440}
1441
1442/*
1443 * For good efficiency of modular, we use power of 2
1444 */
1445#define MAX_CIRCULAR_QUEUE_SIZE (1UL << CONFIG_LOCKDEP_CIRCULAR_QUEUE_BITS)
1446#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
1447
1448/*
1449 * The circular_queue and helpers are used to implement graph
1450 * breadth-first search (BFS) algorithm, by which we can determine
1451 * whether there is a path from a lock to another. In deadlock checks,
1452 * a path from the next lock to be acquired to a previous held lock
1453 * indicates that adding the <prev> -> <next> lock dependency will
1454 * produce a circle in the graph. Breadth-first search instead of
1455 * depth-first search is used in order to find the shortest (circular)
1456 * path.
1457 */
1458struct circular_queue {
1459 struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE];
1460 unsigned int front, rear;
1461};
1462
1463static struct circular_queue lock_cq;
1464
1465unsigned int max_bfs_queue_depth;
1466
1467static unsigned int lockdep_dependency_gen_id;
1468
1469static inline void __cq_init(struct circular_queue *cq)
1470{
1471 cq->front = cq->rear = 0;
1472 lockdep_dependency_gen_id++;
1473}
1474
1475static inline int __cq_empty(struct circular_queue *cq)
1476{
1477 return (cq->front == cq->rear);
1478}
1479
1480static inline int __cq_full(struct circular_queue *cq)
1481{
1482 return ((cq->rear + 1) & CQ_MASK) == cq->front;
1483}
1484
1485static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem)
1486{
1487 if (__cq_full(cq))
1488 return -1;
1489
1490 cq->element[cq->rear] = elem;
1491 cq->rear = (cq->rear + 1) & CQ_MASK;
1492 return 0;
1493}
1494
1495/*
1496 * Dequeue an element from the circular_queue, return a lock_list if
1497 * the queue is not empty, or NULL if otherwise.
1498 */
1499static inline struct lock_list * __cq_dequeue(struct circular_queue *cq)
1500{
1501 struct lock_list * lock;
1502
1503 if (__cq_empty(cq))
1504 return NULL;
1505
1506 lock = cq->element[cq->front];
1507 cq->front = (cq->front + 1) & CQ_MASK;
1508
1509 return lock;
1510}
1511
1512static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
1513{
1514 return (cq->rear - cq->front) & CQ_MASK;
1515}
1516
1517static inline void mark_lock_accessed(struct lock_list *lock)
1518{
1519 lock->class->dep_gen_id = lockdep_dependency_gen_id;
1520}
1521
1522static inline void visit_lock_entry(struct lock_list *lock,
1523 struct lock_list *parent)
1524{
1525 lock->parent = parent;
1526}
1527
1528static inline unsigned long lock_accessed(struct lock_list *lock)
1529{
1530 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
1531}
1532
1533static inline struct lock_list *get_lock_parent(struct lock_list *child)
1534{
1535 return child->parent;
1536}
1537
1538static inline int get_lock_depth(struct lock_list *child)
1539{
1540 int depth = 0;
1541 struct lock_list *parent;
1542
1543 while ((parent = get_lock_parent(child))) {
1544 child = parent;
1545 depth++;
1546 }
1547 return depth;
1548}
1549
1550/*
1551 * Return the forward or backward dependency list.
1552 *
1553 * @lock: the lock_list to get its class's dependency list
1554 * @offset: the offset to struct lock_class to determine whether it is
1555 * locks_after or locks_before
1556 */
1557static inline struct list_head *get_dep_list(struct lock_list *lock, int offset)
1558{
1559 void *lock_class = lock->class;
1560
1561 return lock_class + offset;
1562}
1563/*
1564 * Return values of a bfs search:
1565 *
1566 * BFS_E* indicates an error
1567 * BFS_R* indicates a result (match or not)
1568 *
1569 * BFS_EINVALIDNODE: Find a invalid node in the graph.
1570 *
1571 * BFS_EQUEUEFULL: The queue is full while doing the bfs.
1572 *
1573 * BFS_RMATCH: Find the matched node in the graph, and put that node into
1574 * *@target_entry.
1575 *
1576 * BFS_RNOMATCH: Haven't found the matched node and keep *@target_entry
1577 * _unchanged_.
1578 */
1579enum bfs_result {
1580 BFS_EINVALIDNODE = -2,
1581 BFS_EQUEUEFULL = -1,
1582 BFS_RMATCH = 0,
1583 BFS_RNOMATCH = 1,
1584};
1585
1586/*
1587 * bfs_result < 0 means error
1588 */
1589static inline bool bfs_error(enum bfs_result res)
1590{
1591 return res < 0;
1592}
1593
1594/*
1595 * DEP_*_BIT in lock_list::dep
1596 *
1597 * For dependency @prev -> @next:
1598 *
1599 * SR: @prev is shared reader (->read != 0) and @next is recursive reader
1600 * (->read == 2)
1601 * ER: @prev is exclusive locker (->read == 0) and @next is recursive reader
1602 * SN: @prev is shared reader and @next is non-recursive locker (->read != 2)
1603 * EN: @prev is exclusive locker and @next is non-recursive locker
1604 *
1605 * Note that we define the value of DEP_*_BITs so that:
1606 * bit0 is prev->read == 0
1607 * bit1 is next->read != 2
1608 */
1609#define DEP_SR_BIT (0 + (0 << 1)) /* 0 */
1610#define DEP_ER_BIT (1 + (0 << 1)) /* 1 */
1611#define DEP_SN_BIT (0 + (1 << 1)) /* 2 */
1612#define DEP_EN_BIT (1 + (1 << 1)) /* 3 */
1613
1614#define DEP_SR_MASK (1U << (DEP_SR_BIT))
1615#define DEP_ER_MASK (1U << (DEP_ER_BIT))
1616#define DEP_SN_MASK (1U << (DEP_SN_BIT))
1617#define DEP_EN_MASK (1U << (DEP_EN_BIT))
1618
1619static inline unsigned int
1620__calc_dep_bit(struct held_lock *prev, struct held_lock *next)
1621{
1622 return (prev->read == 0) + ((next->read != 2) << 1);
1623}
1624
1625static inline u8 calc_dep(struct held_lock *prev, struct held_lock *next)
1626{
1627 return 1U << __calc_dep_bit(prev, next);
1628}
1629
1630/*
1631 * calculate the dep_bit for backwards edges. We care about whether @prev is
1632 * shared and whether @next is recursive.
1633 */
1634static inline unsigned int
1635__calc_dep_bitb(struct held_lock *prev, struct held_lock *next)
1636{
1637 return (next->read != 2) + ((prev->read == 0) << 1);
1638}
1639
1640static inline u8 calc_depb(struct held_lock *prev, struct held_lock *next)
1641{
1642 return 1U << __calc_dep_bitb(prev, next);
1643}
1644
1645/*
1646 * Initialize a lock_list entry @lock belonging to @class as the root for a BFS
1647 * search.
1648 */
1649static inline void __bfs_init_root(struct lock_list *lock,
1650 struct lock_class *class)
1651{
1652 lock->class = class;
1653 lock->parent = NULL;
1654 lock->only_xr = 0;
1655}
1656
1657/*
1658 * Initialize a lock_list entry @lock based on a lock acquisition @hlock as the
1659 * root for a BFS search.
1660 *
1661 * ->only_xr of the initial lock node is set to @hlock->read == 2, to make sure
1662 * that <prev> -> @hlock and @hlock -> <whatever __bfs() found> is not -(*R)->
1663 * and -(S*)->.
1664 */
1665static inline void bfs_init_root(struct lock_list *lock,
1666 struct held_lock *hlock)
1667{
1668 __bfs_init_root(lock, hlock_class(hlock));
1669 lock->only_xr = (hlock->read == 2);
1670}
1671
1672/*
1673 * Similar to bfs_init_root() but initialize the root for backwards BFS.
1674 *
1675 * ->only_xr of the initial lock node is set to @hlock->read != 0, to make sure
1676 * that <next> -> @hlock and @hlock -> <whatever backwards BFS found> is not
1677 * -(*S)-> and -(R*)-> (reverse order of -(*R)-> and -(S*)->).
1678 */
1679static inline void bfs_init_rootb(struct lock_list *lock,
1680 struct held_lock *hlock)
1681{
1682 __bfs_init_root(lock, hlock_class(hlock));
1683 lock->only_xr = (hlock->read != 0);
1684}
1685
1686static inline struct lock_list *__bfs_next(struct lock_list *lock, int offset)
1687{
1688 if (!lock || !lock->parent)
1689 return NULL;
1690
1691 return list_next_or_null_rcu(get_dep_list(lock->parent, offset),
1692 &lock->entry, struct lock_list, entry);
1693}
1694
1695/*
1696 * Breadth-First Search to find a strong path in the dependency graph.
1697 *
1698 * @source_entry: the source of the path we are searching for.
1699 * @data: data used for the second parameter of @match function
1700 * @match: match function for the search
1701 * @target_entry: pointer to the target of a matched path
1702 * @offset: the offset to struct lock_class to determine whether it is
1703 * locks_after or locks_before
1704 *
1705 * We may have multiple edges (considering different kinds of dependencies,
1706 * e.g. ER and SN) between two nodes in the dependency graph. But
1707 * only the strong dependency path in the graph is relevant to deadlocks. A
1708 * strong dependency path is a dependency path that doesn't have two adjacent
1709 * dependencies as -(*R)-> -(S*)->, please see:
1710 *
1711 * Documentation/locking/lockdep-design.rst
1712 *
1713 * for more explanation of the definition of strong dependency paths
1714 *
1715 * In __bfs(), we only traverse in the strong dependency path:
1716 *
1717 * In lock_list::only_xr, we record whether the previous dependency only
1718 * has -(*R)-> in the search, and if it does (prev only has -(*R)->), we
1719 * filter out any -(S*)-> in the current dependency and after that, the
1720 * ->only_xr is set according to whether we only have -(*R)-> left.
1721 */
1722static enum bfs_result __bfs(struct lock_list *source_entry,
1723 void *data,
1724 bool (*match)(struct lock_list *entry, void *data),
1725 bool (*skip)(struct lock_list *entry, void *data),
1726 struct lock_list **target_entry,
1727 int offset)
1728{
1729 struct circular_queue *cq = &lock_cq;
1730 struct lock_list *lock = NULL;
1731 struct lock_list *entry;
1732 struct list_head *head;
1733 unsigned int cq_depth;
1734 bool first;
1735
1736 lockdep_assert_locked();
1737
1738 __cq_init(cq);
1739 __cq_enqueue(cq, source_entry);
1740
1741 while ((lock = __bfs_next(lock, offset)) || (lock = __cq_dequeue(cq))) {
1742 if (!lock->class)
1743 return BFS_EINVALIDNODE;
1744
1745 /*
1746 * Step 1: check whether we already finish on this one.
1747 *
1748 * If we have visited all the dependencies from this @lock to
1749 * others (iow, if we have visited all lock_list entries in
1750 * @lock->class->locks_{after,before}) we skip, otherwise go
1751 * and visit all the dependencies in the list and mark this
1752 * list accessed.
1753 */
1754 if (lock_accessed(lock))
1755 continue;
1756 else
1757 mark_lock_accessed(lock);
1758
1759 /*
1760 * Step 2: check whether prev dependency and this form a strong
1761 * dependency path.
1762 */
1763 if (lock->parent) { /* Parent exists, check prev dependency */
1764 u8 dep = lock->dep;
1765 bool prev_only_xr = lock->parent->only_xr;
1766
1767 /*
1768 * Mask out all -(S*)-> if we only have *R in previous
1769 * step, because -(*R)-> -(S*)-> don't make up a strong
1770 * dependency.
1771 */
1772 if (prev_only_xr)
1773 dep &= ~(DEP_SR_MASK | DEP_SN_MASK);
1774
1775 /* If nothing left, we skip */
1776 if (!dep)
1777 continue;
1778
1779 /* If there are only -(*R)-> left, set that for the next step */
1780 lock->only_xr = !(dep & (DEP_SN_MASK | DEP_EN_MASK));
1781 }
1782
1783 /*
1784 * Step 3: we haven't visited this and there is a strong
1785 * dependency path to this, so check with @match.
1786 * If @skip is provide and returns true, we skip this
1787 * lock (and any path this lock is in).
1788 */
1789 if (skip && skip(lock, data))
1790 continue;
1791
1792 if (match(lock, data)) {
1793 *target_entry = lock;
1794 return BFS_RMATCH;
1795 }
1796
1797 /*
1798 * Step 4: if not match, expand the path by adding the
1799 * forward or backwards dependencies in the search
1800 *
1801 */
1802 first = true;
1803 head = get_dep_list(lock, offset);
1804 list_for_each_entry_rcu(entry, head, entry) {
1805 visit_lock_entry(entry, lock);
1806
1807 /*
1808 * Note we only enqueue the first of the list into the
1809 * queue, because we can always find a sibling
1810 * dependency from one (see __bfs_next()), as a result
1811 * the space of queue is saved.
1812 */
1813 if (!first)
1814 continue;
1815
1816 first = false;
1817
1818 if (__cq_enqueue(cq, entry))
1819 return BFS_EQUEUEFULL;
1820
1821 cq_depth = __cq_get_elem_count(cq);
1822 if (max_bfs_queue_depth < cq_depth)
1823 max_bfs_queue_depth = cq_depth;
1824 }
1825 }
1826
1827 return BFS_RNOMATCH;
1828}
1829
1830static inline enum bfs_result
1831__bfs_forwards(struct lock_list *src_entry,
1832 void *data,
1833 bool (*match)(struct lock_list *entry, void *data),
1834 bool (*skip)(struct lock_list *entry, void *data),
1835 struct lock_list **target_entry)
1836{
1837 return __bfs(src_entry, data, match, skip, target_entry,
1838 offsetof(struct lock_class, locks_after));
1839
1840}
1841
1842static inline enum bfs_result
1843__bfs_backwards(struct lock_list *src_entry,
1844 void *data,
1845 bool (*match)(struct lock_list *entry, void *data),
1846 bool (*skip)(struct lock_list *entry, void *data),
1847 struct lock_list **target_entry)
1848{
1849 return __bfs(src_entry, data, match, skip, target_entry,
1850 offsetof(struct lock_class, locks_before));
1851
1852}
1853
1854static void print_lock_trace(const struct lock_trace *trace,
1855 unsigned int spaces)
1856{
1857 stack_trace_print(trace->entries, trace->nr_entries, spaces);
1858}
1859
1860/*
1861 * Print a dependency chain entry (this is only done when a deadlock
1862 * has been detected):
1863 */
1864static noinline void
1865print_circular_bug_entry(struct lock_list *target, int depth)
1866{
1867 if (debug_locks_silent)
1868 return;
1869 printk("\n-> #%u", depth);
1870 print_lock_name(target->class);
1871 printk(KERN_CONT ":\n");
1872 print_lock_trace(target->trace, 6);
1873}
1874
1875static void
1876print_circular_lock_scenario(struct held_lock *src,
1877 struct held_lock *tgt,
1878 struct lock_list *prt)
1879{
1880 struct lock_class *source = hlock_class(src);
1881 struct lock_class *target = hlock_class(tgt);
1882 struct lock_class *parent = prt->class;
1883
1884 /*
1885 * A direct locking problem where unsafe_class lock is taken
1886 * directly by safe_class lock, then all we need to show
1887 * is the deadlock scenario, as it is obvious that the
1888 * unsafe lock is taken under the safe lock.
1889 *
1890 * But if there is a chain instead, where the safe lock takes
1891 * an intermediate lock (middle_class) where this lock is
1892 * not the same as the safe lock, then the lock chain is
1893 * used to describe the problem. Otherwise we would need
1894 * to show a different CPU case for each link in the chain
1895 * from the safe_class lock to the unsafe_class lock.
1896 */
1897 if (parent != source) {
1898 printk("Chain exists of:\n ");
1899 __print_lock_name(source);
1900 printk(KERN_CONT " --> ");
1901 __print_lock_name(parent);
1902 printk(KERN_CONT " --> ");
1903 __print_lock_name(target);
1904 printk(KERN_CONT "\n\n");
1905 }
1906
1907 printk(" Possible unsafe locking scenario:\n\n");
1908 printk(" CPU0 CPU1\n");
1909 printk(" ---- ----\n");
1910 printk(" lock(");
1911 __print_lock_name(target);
1912 printk(KERN_CONT ");\n");
1913 printk(" lock(");
1914 __print_lock_name(parent);
1915 printk(KERN_CONT ");\n");
1916 printk(" lock(");
1917 __print_lock_name(target);
1918 printk(KERN_CONT ");\n");
1919 printk(" lock(");
1920 __print_lock_name(source);
1921 printk(KERN_CONT ");\n");
1922 printk("\n *** DEADLOCK ***\n\n");
1923}
1924
1925/*
1926 * When a circular dependency is detected, print the
1927 * header first:
1928 */
1929static noinline void
1930print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1931 struct held_lock *check_src,
1932 struct held_lock *check_tgt)
1933{
1934 struct task_struct *curr = current;
1935
1936 if (debug_locks_silent)
1937 return;
1938
1939 pr_warn("\n");
1940 pr_warn("======================================================\n");
1941 pr_warn("WARNING: possible circular locking dependency detected\n");
1942 print_kernel_ident();
1943 pr_warn("------------------------------------------------------\n");
1944 pr_warn("%s/%d is trying to acquire lock:\n",
1945 curr->comm, task_pid_nr(curr));
1946 print_lock(check_src);
1947
1948 pr_warn("\nbut task is already holding lock:\n");
1949
1950 print_lock(check_tgt);
1951 pr_warn("\nwhich lock already depends on the new lock.\n\n");
1952 pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1953
1954 print_circular_bug_entry(entry, depth);
1955}
1956
1957/*
1958 * We are about to add A -> B into the dependency graph, and in __bfs() a
1959 * strong dependency path A -> .. -> B is found: hlock_class equals
1960 * entry->class.
1961 *
1962 * If A -> .. -> B can replace A -> B in any __bfs() search (means the former
1963 * is _stronger_ than or equal to the latter), we consider A -> B as redundant.
1964 * For example if A -> .. -> B is -(EN)-> (i.e. A -(E*)-> .. -(*N)-> B), and A
1965 * -> B is -(ER)-> or -(EN)->, then we don't need to add A -> B into the
1966 * dependency graph, as any strong path ..-> A -> B ->.. we can get with
1967 * having dependency A -> B, we could already get a equivalent path ..-> A ->
1968 * .. -> B -> .. with A -> .. -> B. Therefore A -> B is redundant.
1969 *
1970 * We need to make sure both the start and the end of A -> .. -> B is not
1971 * weaker than A -> B. For the start part, please see the comment in
1972 * check_redundant(). For the end part, we need:
1973 *
1974 * Either
1975 *
1976 * a) A -> B is -(*R)-> (everything is not weaker than that)
1977 *
1978 * or
1979 *
1980 * b) A -> .. -> B is -(*N)-> (nothing is stronger than this)
1981 *
1982 */
1983static inline bool hlock_equal(struct lock_list *entry, void *data)
1984{
1985 struct held_lock *hlock = (struct held_lock *)data;
1986
1987 return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */
1988 (hlock->read == 2 || /* A -> B is -(*R)-> */
1989 !entry->only_xr); /* A -> .. -> B is -(*N)-> */
1990}
1991
1992/*
1993 * We are about to add B -> A into the dependency graph, and in __bfs() a
1994 * strong dependency path A -> .. -> B is found: hlock_class equals
1995 * entry->class.
1996 *
1997 * We will have a deadlock case (conflict) if A -> .. -> B -> A is a strong
1998 * dependency cycle, that means:
1999 *
2000 * Either
2001 *
2002 * a) B -> A is -(E*)->
2003 *
2004 * or
2005 *
2006 * b) A -> .. -> B is -(*N)-> (i.e. A -> .. -(*N)-> B)
2007 *
2008 * as then we don't have -(*R)-> -(S*)-> in the cycle.
2009 */
2010static inline bool hlock_conflict(struct lock_list *entry, void *data)
2011{
2012 struct held_lock *hlock = (struct held_lock *)data;
2013
2014 return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */
2015 (hlock->read == 0 || /* B -> A is -(E*)-> */
2016 !entry->only_xr); /* A -> .. -> B is -(*N)-> */
2017}
2018
2019static noinline void print_circular_bug(struct lock_list *this,
2020 struct lock_list *target,
2021 struct held_lock *check_src,
2022 struct held_lock *check_tgt)
2023{
2024 struct task_struct *curr = current;
2025 struct lock_list *parent;
2026 struct lock_list *first_parent;
2027 int depth;
2028
2029 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2030 return;
2031
2032 this->trace = save_trace();
2033 if (!this->trace)
2034 return;
2035
2036 depth = get_lock_depth(target);
2037
2038 print_circular_bug_header(target, depth, check_src, check_tgt);
2039
2040 parent = get_lock_parent(target);
2041 first_parent = parent;
2042
2043 while (parent) {
2044 print_circular_bug_entry(parent, --depth);
2045 parent = get_lock_parent(parent);
2046 }
2047
2048 printk("\nother info that might help us debug this:\n\n");
2049 print_circular_lock_scenario(check_src, check_tgt,
2050 first_parent);
2051
2052 lockdep_print_held_locks(curr);
2053
2054 printk("\nstack backtrace:\n");
2055 dump_stack();
2056}
2057
2058static noinline void print_bfs_bug(int ret)
2059{
2060 if (!debug_locks_off_graph_unlock())
2061 return;
2062
2063 /*
2064 * Breadth-first-search failed, graph got corrupted?
2065 */
2066 WARN(1, "lockdep bfs error:%d\n", ret);
2067}
2068
2069static bool noop_count(struct lock_list *entry, void *data)
2070{
2071 (*(unsigned long *)data)++;
2072 return false;
2073}
2074
2075static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
2076{
2077 unsigned long count = 0;
2078 struct lock_list *target_entry;
2079
2080 __bfs_forwards(this, (void *)&count, noop_count, NULL, &target_entry);
2081
2082 return count;
2083}
2084unsigned long lockdep_count_forward_deps(struct lock_class *class)
2085{
2086 unsigned long ret, flags;
2087 struct lock_list this;
2088
2089 __bfs_init_root(&this, class);
2090
2091 raw_local_irq_save(flags);
2092 lockdep_lock();
2093 ret = __lockdep_count_forward_deps(&this);
2094 lockdep_unlock();
2095 raw_local_irq_restore(flags);
2096
2097 return ret;
2098}
2099
2100static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
2101{
2102 unsigned long count = 0;
2103 struct lock_list *target_entry;
2104
2105 __bfs_backwards(this, (void *)&count, noop_count, NULL, &target_entry);
2106
2107 return count;
2108}
2109
2110unsigned long lockdep_count_backward_deps(struct lock_class *class)
2111{
2112 unsigned long ret, flags;
2113 struct lock_list this;
2114
2115 __bfs_init_root(&this, class);
2116
2117 raw_local_irq_save(flags);
2118 lockdep_lock();
2119 ret = __lockdep_count_backward_deps(&this);
2120 lockdep_unlock();
2121 raw_local_irq_restore(flags);
2122
2123 return ret;
2124}
2125
2126/*
2127 * Check that the dependency graph starting at <src> can lead to
2128 * <target> or not.
2129 */
2130static noinline enum bfs_result
2131check_path(struct held_lock *target, struct lock_list *src_entry,
2132 bool (*match)(struct lock_list *entry, void *data),
2133 bool (*skip)(struct lock_list *entry, void *data),
2134 struct lock_list **target_entry)
2135{
2136 enum bfs_result ret;
2137
2138 ret = __bfs_forwards(src_entry, target, match, skip, target_entry);
2139
2140 if (unlikely(bfs_error(ret)))
2141 print_bfs_bug(ret);
2142
2143 return ret;
2144}
2145
2146/*
2147 * Prove that the dependency graph starting at <src> can not
2148 * lead to <target>. If it can, there is a circle when adding
2149 * <target> -> <src> dependency.
2150 *
2151 * Print an error and return BFS_RMATCH if it does.
2152 */
2153static noinline enum bfs_result
2154check_noncircular(struct held_lock *src, struct held_lock *target,
2155 struct lock_trace **const trace)
2156{
2157 enum bfs_result ret;
2158 struct lock_list *target_entry;
2159 struct lock_list src_entry;
2160
2161 bfs_init_root(&src_entry, src);
2162
2163 debug_atomic_inc(nr_cyclic_checks);
2164
2165 ret = check_path(target, &src_entry, hlock_conflict, NULL, &target_entry);
2166
2167 if (unlikely(ret == BFS_RMATCH)) {
2168 if (!*trace) {
2169 /*
2170 * If save_trace fails here, the printing might
2171 * trigger a WARN but because of the !nr_entries it
2172 * should not do bad things.
2173 */
2174 *trace = save_trace();
2175 }
2176
2177 print_circular_bug(&src_entry, target_entry, src, target);
2178 }
2179
2180 return ret;
2181}
2182
2183#ifdef CONFIG_TRACE_IRQFLAGS
2184
2185/*
2186 * Forwards and backwards subgraph searching, for the purposes of
2187 * proving that two subgraphs can be connected by a new dependency
2188 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
2189 *
2190 * A irq safe->unsafe deadlock happens with the following conditions:
2191 *
2192 * 1) We have a strong dependency path A -> ... -> B
2193 *
2194 * 2) and we have ENABLED_IRQ usage of B and USED_IN_IRQ usage of A, therefore
2195 * irq can create a new dependency B -> A (consider the case that a holder
2196 * of B gets interrupted by an irq whose handler will try to acquire A).
2197 *
2198 * 3) the dependency circle A -> ... -> B -> A we get from 1) and 2) is a
2199 * strong circle:
2200 *
2201 * For the usage bits of B:
2202 * a) if A -> B is -(*N)->, then B -> A could be any type, so any
2203 * ENABLED_IRQ usage suffices.
2204 * b) if A -> B is -(*R)->, then B -> A must be -(E*)->, so only
2205 * ENABLED_IRQ_*_READ usage suffices.
2206 *
2207 * For the usage bits of A:
2208 * c) if A -> B is -(E*)->, then B -> A could be any type, so any
2209 * USED_IN_IRQ usage suffices.
2210 * d) if A -> B is -(S*)->, then B -> A must be -(*N)->, so only
2211 * USED_IN_IRQ_*_READ usage suffices.
2212 */
2213
2214/*
2215 * There is a strong dependency path in the dependency graph: A -> B, and now
2216 * we need to decide which usage bit of A should be accumulated to detect
2217 * safe->unsafe bugs.
2218 *
2219 * Note that usage_accumulate() is used in backwards search, so ->only_xr
2220 * stands for whether A -> B only has -(S*)-> (in this case ->only_xr is true).
2221 *
2222 * As above, if only_xr is false, which means A -> B has -(E*)-> dependency
2223 * path, any usage of A should be considered. Otherwise, we should only
2224 * consider _READ usage.
2225 */
2226static inline bool usage_accumulate(struct lock_list *entry, void *mask)
2227{
2228 if (!entry->only_xr)
2229 *(unsigned long *)mask |= entry->class->usage_mask;
2230 else /* Mask out _READ usage bits */
2231 *(unsigned long *)mask |= (entry->class->usage_mask & LOCKF_IRQ);
2232
2233 return false;
2234}
2235
2236/*
2237 * There is a strong dependency path in the dependency graph: A -> B, and now
2238 * we need to decide which usage bit of B conflicts with the usage bits of A,
2239 * i.e. which usage bit of B may introduce safe->unsafe deadlocks.
2240 *
2241 * As above, if only_xr is false, which means A -> B has -(*N)-> dependency
2242 * path, any usage of B should be considered. Otherwise, we should only
2243 * consider _READ usage.
2244 */
2245static inline bool usage_match(struct lock_list *entry, void *mask)
2246{
2247 if (!entry->only_xr)
2248 return !!(entry->class->usage_mask & *(unsigned long *)mask);
2249 else /* Mask out _READ usage bits */
2250 return !!((entry->class->usage_mask & LOCKF_IRQ) & *(unsigned long *)mask);
2251}
2252
2253static inline bool usage_skip(struct lock_list *entry, void *mask)
2254{
2255 /*
2256 * Skip local_lock() for irq inversion detection.
2257 *
2258 * For !RT, local_lock() is not a real lock, so it won't carry any
2259 * dependency.
2260 *
2261 * For RT, an irq inversion happens when we have lock A and B, and on
2262 * some CPU we can have:
2263 *
2264 * lock(A);
2265 * <interrupted>
2266 * lock(B);
2267 *
2268 * where lock(B) cannot sleep, and we have a dependency B -> ... -> A.
2269 *
2270 * Now we prove local_lock() cannot exist in that dependency. First we
2271 * have the observation for any lock chain L1 -> ... -> Ln, for any
2272 * 1 <= i <= n, Li.inner_wait_type <= L1.inner_wait_type, otherwise
2273 * wait context check will complain. And since B is not a sleep lock,
2274 * therefore B.inner_wait_type >= 2, and since the inner_wait_type of
2275 * local_lock() is 3, which is greater than 2, therefore there is no
2276 * way the local_lock() exists in the dependency B -> ... -> A.
2277 *
2278 * As a result, we will skip local_lock(), when we search for irq
2279 * inversion bugs.
2280 */
2281 if (entry->class->lock_type == LD_LOCK_PERCPU) {
2282 if (DEBUG_LOCKS_WARN_ON(entry->class->wait_type_inner < LD_WAIT_CONFIG))
2283 return false;
2284
2285 return true;
2286 }
2287
2288 return false;
2289}
2290
2291/*
2292 * Find a node in the forwards-direction dependency sub-graph starting
2293 * at @root->class that matches @bit.
2294 *
2295 * Return BFS_MATCH if such a node exists in the subgraph, and put that node
2296 * into *@target_entry.
2297 */
2298static enum bfs_result
2299find_usage_forwards(struct lock_list *root, unsigned long usage_mask,
2300 struct lock_list **target_entry)
2301{
2302 enum bfs_result result;
2303
2304 debug_atomic_inc(nr_find_usage_forwards_checks);
2305
2306 result = __bfs_forwards(root, &usage_mask, usage_match, usage_skip, target_entry);
2307
2308 return result;
2309}
2310
2311/*
2312 * Find a node in the backwards-direction dependency sub-graph starting
2313 * at @root->class that matches @bit.
2314 */
2315static enum bfs_result
2316find_usage_backwards(struct lock_list *root, unsigned long usage_mask,
2317 struct lock_list **target_entry)
2318{
2319 enum bfs_result result;
2320
2321 debug_atomic_inc(nr_find_usage_backwards_checks);
2322
2323 result = __bfs_backwards(root, &usage_mask, usage_match, usage_skip, target_entry);
2324
2325 return result;
2326}
2327
2328static void print_lock_class_header(struct lock_class *class, int depth)
2329{
2330 int bit;
2331
2332 printk("%*s->", depth, "");
2333 print_lock_name(class);
2334#ifdef CONFIG_DEBUG_LOCKDEP
2335 printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
2336#endif
2337 printk(KERN_CONT " {\n");
2338
2339 for (bit = 0; bit < LOCK_TRACE_STATES; bit++) {
2340 if (class->usage_mask & (1 << bit)) {
2341 int len = depth;
2342
2343 len += printk("%*s %s", depth, "", usage_str[bit]);
2344 len += printk(KERN_CONT " at:\n");
2345 print_lock_trace(class->usage_traces[bit], len);
2346 }
2347 }
2348 printk("%*s }\n", depth, "");
2349
2350 printk("%*s ... key at: [<%px>] %pS\n",
2351 depth, "", class->key, class->key);
2352}
2353
2354/*
2355 * Dependency path printing:
2356 *
2357 * After BFS we get a lock dependency path (linked via ->parent of lock_list),
2358 * printing out each lock in the dependency path will help on understanding how
2359 * the deadlock could happen. Here are some details about dependency path
2360 * printing:
2361 *
2362 * 1) A lock_list can be either forwards or backwards for a lock dependency,
2363 * for a lock dependency A -> B, there are two lock_lists:
2364 *
2365 * a) lock_list in the ->locks_after list of A, whose ->class is B and
2366 * ->links_to is A. In this case, we can say the lock_list is
2367 * "A -> B" (forwards case).
2368 *
2369 * b) lock_list in the ->locks_before list of B, whose ->class is A
2370 * and ->links_to is B. In this case, we can say the lock_list is
2371 * "B <- A" (bacwards case).
2372 *
2373 * The ->trace of both a) and b) point to the call trace where B was
2374 * acquired with A held.
2375 *
2376 * 2) A "helper" lock_list is introduced during BFS, this lock_list doesn't
2377 * represent a certain lock dependency, it only provides an initial entry
2378 * for BFS. For example, BFS may introduce a "helper" lock_list whose
2379 * ->class is A, as a result BFS will search all dependencies starting with
2380 * A, e.g. A -> B or A -> C.
2381 *
2382 * The notation of a forwards helper lock_list is like "-> A", which means
2383 * we should search the forwards dependencies starting with "A", e.g A -> B
2384 * or A -> C.
2385 *
2386 * The notation of a bacwards helper lock_list is like "<- B", which means
2387 * we should search the backwards dependencies ending with "B", e.g.
2388 * B <- A or B <- C.
2389 */
2390
2391/*
2392 * printk the shortest lock dependencies from @root to @leaf in reverse order.
2393 *
2394 * We have a lock dependency path as follow:
2395 *
2396 * @root @leaf
2397 * | |
2398 * V V
2399 * ->parent ->parent
2400 * | lock_list | <--------- | lock_list | ... | lock_list | <--------- | lock_list |
2401 * | -> L1 | | L1 -> L2 | ... |Ln-2 -> Ln-1| | Ln-1 -> Ln|
2402 *
2403 * , so it's natural that we start from @leaf and print every ->class and
2404 * ->trace until we reach the @root.
2405 */
2406static void __used
2407print_shortest_lock_dependencies(struct lock_list *leaf,
2408 struct lock_list *root)
2409{
2410 struct lock_list *entry = leaf;
2411 int depth;
2412
2413 /*compute depth from generated tree by BFS*/
2414 depth = get_lock_depth(leaf);
2415
2416 do {
2417 print_lock_class_header(entry->class, depth);
2418 printk("%*s ... acquired at:\n", depth, "");
2419 print_lock_trace(entry->trace, 2);
2420 printk("\n");
2421
2422 if (depth == 0 && (entry != root)) {
2423 printk("lockdep:%s bad path found in chain graph\n", __func__);
2424 break;
2425 }
2426
2427 entry = get_lock_parent(entry);
2428 depth--;
2429 } while (entry && (depth >= 0));
2430}
2431
2432/*
2433 * printk the shortest lock dependencies from @leaf to @root.
2434 *
2435 * We have a lock dependency path (from a backwards search) as follow:
2436 *
2437 * @leaf @root
2438 * | |
2439 * V V
2440 * ->parent ->parent
2441 * | lock_list | ---------> | lock_list | ... | lock_list | ---------> | lock_list |
2442 * | L2 <- L1 | | L3 <- L2 | ... | Ln <- Ln-1 | | <- Ln |
2443 *
2444 * , so when we iterate from @leaf to @root, we actually print the lock
2445 * dependency path L1 -> L2 -> .. -> Ln in the non-reverse order.
2446 *
2447 * Another thing to notice here is that ->class of L2 <- L1 is L1, while the
2448 * ->trace of L2 <- L1 is the call trace of L2, in fact we don't have the call
2449 * trace of L1 in the dependency path, which is alright, because most of the
2450 * time we can figure out where L1 is held from the call trace of L2.
2451 */
2452static void __used
2453print_shortest_lock_dependencies_backwards(struct lock_list *leaf,
2454 struct lock_list *root)
2455{
2456 struct lock_list *entry = leaf;
2457 const struct lock_trace *trace = NULL;
2458 int depth;
2459
2460 /*compute depth from generated tree by BFS*/
2461 depth = get_lock_depth(leaf);
2462
2463 do {
2464 print_lock_class_header(entry->class, depth);
2465 if (trace) {
2466 printk("%*s ... acquired at:\n", depth, "");
2467 print_lock_trace(trace, 2);
2468 printk("\n");
2469 }
2470
2471 /*
2472 * Record the pointer to the trace for the next lock_list
2473 * entry, see the comments for the function.
2474 */
2475 trace = entry->trace;
2476
2477 if (depth == 0 && (entry != root)) {
2478 printk("lockdep:%s bad path found in chain graph\n", __func__);
2479 break;
2480 }
2481
2482 entry = get_lock_parent(entry);
2483 depth--;
2484 } while (entry && (depth >= 0));
2485}
2486
2487static void
2488print_irq_lock_scenario(struct lock_list *safe_entry,
2489 struct lock_list *unsafe_entry,
2490 struct lock_class *prev_class,
2491 struct lock_class *next_class)
2492{
2493 struct lock_class *safe_class = safe_entry->class;
2494 struct lock_class *unsafe_class = unsafe_entry->class;
2495 struct lock_class *middle_class = prev_class;
2496
2497 if (middle_class == safe_class)
2498 middle_class = next_class;
2499
2500 /*
2501 * A direct locking problem where unsafe_class lock is taken
2502 * directly by safe_class lock, then all we need to show
2503 * is the deadlock scenario, as it is obvious that the
2504 * unsafe lock is taken under the safe lock.
2505 *
2506 * But if there is a chain instead, where the safe lock takes
2507 * an intermediate lock (middle_class) where this lock is
2508 * not the same as the safe lock, then the lock chain is
2509 * used to describe the problem. Otherwise we would need
2510 * to show a different CPU case for each link in the chain
2511 * from the safe_class lock to the unsafe_class lock.
2512 */
2513 if (middle_class != unsafe_class) {
2514 printk("Chain exists of:\n ");
2515 __print_lock_name(safe_class);
2516 printk(KERN_CONT " --> ");
2517 __print_lock_name(middle_class);
2518 printk(KERN_CONT " --> ");
2519 __print_lock_name(unsafe_class);
2520 printk(KERN_CONT "\n\n");
2521 }
2522
2523 printk(" Possible interrupt unsafe locking scenario:\n\n");
2524 printk(" CPU0 CPU1\n");
2525 printk(" ---- ----\n");
2526 printk(" lock(");
2527 __print_lock_name(unsafe_class);
2528 printk(KERN_CONT ");\n");
2529 printk(" local_irq_disable();\n");
2530 printk(" lock(");
2531 __print_lock_name(safe_class);
2532 printk(KERN_CONT ");\n");
2533 printk(" lock(");
2534 __print_lock_name(middle_class);
2535 printk(KERN_CONT ");\n");
2536 printk(" <Interrupt>\n");
2537 printk(" lock(");
2538 __print_lock_name(safe_class);
2539 printk(KERN_CONT ");\n");
2540 printk("\n *** DEADLOCK ***\n\n");
2541}
2542
2543static void
2544print_bad_irq_dependency(struct task_struct *curr,
2545 struct lock_list *prev_root,
2546 struct lock_list *next_root,
2547 struct lock_list *backwards_entry,
2548 struct lock_list *forwards_entry,
2549 struct held_lock *prev,
2550 struct held_lock *next,
2551 enum lock_usage_bit bit1,
2552 enum lock_usage_bit bit2,
2553 const char *irqclass)
2554{
2555 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2556 return;
2557
2558 pr_warn("\n");
2559 pr_warn("=====================================================\n");
2560 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
2561 irqclass, irqclass);
2562 print_kernel_ident();
2563 pr_warn("-----------------------------------------------------\n");
2564 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
2565 curr->comm, task_pid_nr(curr),
2566 lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
2567 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
2568 lockdep_hardirqs_enabled(),
2569 curr->softirqs_enabled);
2570 print_lock(next);
2571
2572 pr_warn("\nand this task is already holding:\n");
2573 print_lock(prev);
2574 pr_warn("which would create a new lock dependency:\n");
2575 print_lock_name(hlock_class(prev));
2576 pr_cont(" ->");
2577 print_lock_name(hlock_class(next));
2578 pr_cont("\n");
2579
2580 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
2581 irqclass);
2582 print_lock_name(backwards_entry->class);
2583 pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
2584
2585 print_lock_trace(backwards_entry->class->usage_traces[bit1], 1);
2586
2587 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
2588 print_lock_name(forwards_entry->class);
2589 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
2590 pr_warn("...");
2591
2592 print_lock_trace(forwards_entry->class->usage_traces[bit2], 1);
2593
2594 pr_warn("\nother info that might help us debug this:\n\n");
2595 print_irq_lock_scenario(backwards_entry, forwards_entry,
2596 hlock_class(prev), hlock_class(next));
2597
2598 lockdep_print_held_locks(curr);
2599
2600 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
2601 print_shortest_lock_dependencies_backwards(backwards_entry, prev_root);
2602
2603 pr_warn("\nthe dependencies between the lock to be acquired");
2604 pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
2605 next_root->trace = save_trace();
2606 if (!next_root->trace)
2607 return;
2608 print_shortest_lock_dependencies(forwards_entry, next_root);
2609
2610 pr_warn("\nstack backtrace:\n");
2611 dump_stack();
2612}
2613
2614static const char *state_names[] = {
2615#define LOCKDEP_STATE(__STATE) \
2616 __stringify(__STATE),
2617#include "lockdep_states.h"
2618#undef LOCKDEP_STATE
2619};
2620
2621static const char *state_rnames[] = {
2622#define LOCKDEP_STATE(__STATE) \
2623 __stringify(__STATE)"-READ",
2624#include "lockdep_states.h"
2625#undef LOCKDEP_STATE
2626};
2627
2628static inline const char *state_name(enum lock_usage_bit bit)
2629{
2630 if (bit & LOCK_USAGE_READ_MASK)
2631 return state_rnames[bit >> LOCK_USAGE_DIR_MASK];
2632 else
2633 return state_names[bit >> LOCK_USAGE_DIR_MASK];
2634}
2635
2636/*
2637 * The bit number is encoded like:
2638 *
2639 * bit0: 0 exclusive, 1 read lock
2640 * bit1: 0 used in irq, 1 irq enabled
2641 * bit2-n: state
2642 */
2643static int exclusive_bit(int new_bit)
2644{
2645 int state = new_bit & LOCK_USAGE_STATE_MASK;
2646 int dir = new_bit & LOCK_USAGE_DIR_MASK;
2647
2648 /*
2649 * keep state, bit flip the direction and strip read.
2650 */
2651 return state | (dir ^ LOCK_USAGE_DIR_MASK);
2652}
2653
2654/*
2655 * Observe that when given a bitmask where each bitnr is encoded as above, a
2656 * right shift of the mask transforms the individual bitnrs as -1 and
2657 * conversely, a left shift transforms into +1 for the individual bitnrs.
2658 *
2659 * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can
2660 * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0)
2661 * instead by subtracting the bit number by 2, or shifting the mask right by 2.
2662 *
2663 * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2.
2664 *
2665 * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is
2666 * all bits set) and recompose with bitnr1 flipped.
2667 */
2668static unsigned long invert_dir_mask(unsigned long mask)
2669{
2670 unsigned long excl = 0;
2671
2672 /* Invert dir */
2673 excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK;
2674 excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK;
2675
2676 return excl;
2677}
2678
2679/*
2680 * Note that a LOCK_ENABLED_IRQ_*_READ usage and a LOCK_USED_IN_IRQ_*_READ
2681 * usage may cause deadlock too, for example:
2682 *
2683 * P1 P2
2684 * <irq disabled>
2685 * write_lock(l1); <irq enabled>
2686 * read_lock(l2);
2687 * write_lock(l2);
2688 * <in irq>
2689 * read_lock(l1);
2690 *
2691 * , in above case, l1 will be marked as LOCK_USED_IN_IRQ_HARDIRQ_READ and l2
2692 * will marked as LOCK_ENABLE_IRQ_HARDIRQ_READ, and this is a possible
2693 * deadlock.
2694 *
2695 * In fact, all of the following cases may cause deadlocks:
2696 *
2697 * LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_*
2698 * LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_*
2699 * LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_*_READ
2700 * LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_*_READ
2701 *
2702 * As a result, to calculate the "exclusive mask", first we invert the
2703 * direction (USED_IN/ENABLED) of the original mask, and 1) for all bits with
2704 * bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*). 2) for all
2705 * bits with bitnr0 cleared (LOCK_*_READ), add those with bitnr0 set (LOCK_*).
2706 */
2707static unsigned long exclusive_mask(unsigned long mask)
2708{
2709 unsigned long excl = invert_dir_mask(mask);
2710
2711 excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
2712 excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
2713
2714 return excl;
2715}
2716
2717/*
2718 * Retrieve the _possible_ original mask to which @mask is
2719 * exclusive. Ie: this is the opposite of exclusive_mask().
2720 * Note that 2 possible original bits can match an exclusive
2721 * bit: one has LOCK_USAGE_READ_MASK set, the other has it
2722 * cleared. So both are returned for each exclusive bit.
2723 */
2724static unsigned long original_mask(unsigned long mask)
2725{
2726 unsigned long excl = invert_dir_mask(mask);
2727
2728 /* Include read in existing usages */
2729 excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
2730 excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
2731
2732 return excl;
2733}
2734
2735/*
2736 * Find the first pair of bit match between an original
2737 * usage mask and an exclusive usage mask.
2738 */
2739static int find_exclusive_match(unsigned long mask,
2740 unsigned long excl_mask,
2741 enum lock_usage_bit *bitp,
2742 enum lock_usage_bit *excl_bitp)
2743{
2744 int bit, excl, excl_read;
2745
2746 for_each_set_bit(bit, &mask, LOCK_USED) {
2747 /*
2748 * exclusive_bit() strips the read bit, however,
2749 * LOCK_ENABLED_IRQ_*_READ may cause deadlocks too, so we need
2750 * to search excl | LOCK_USAGE_READ_MASK as well.
2751 */
2752 excl = exclusive_bit(bit);
2753 excl_read = excl | LOCK_USAGE_READ_MASK;
2754 if (excl_mask & lock_flag(excl)) {
2755 *bitp = bit;
2756 *excl_bitp = excl;
2757 return 0;
2758 } else if (excl_mask & lock_flag(excl_read)) {
2759 *bitp = bit;
2760 *excl_bitp = excl_read;
2761 return 0;
2762 }
2763 }
2764 return -1;
2765}
2766
2767/*
2768 * Prove that the new dependency does not connect a hardirq-safe(-read)
2769 * lock with a hardirq-unsafe lock - to achieve this we search
2770 * the backwards-subgraph starting at <prev>, and the
2771 * forwards-subgraph starting at <next>:
2772 */
2773static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
2774 struct held_lock *next)
2775{
2776 unsigned long usage_mask = 0, forward_mask, backward_mask;
2777 enum lock_usage_bit forward_bit = 0, backward_bit = 0;
2778 struct lock_list *target_entry1;
2779 struct lock_list *target_entry;
2780 struct lock_list this, that;
2781 enum bfs_result ret;
2782
2783 /*
2784 * Step 1: gather all hard/soft IRQs usages backward in an
2785 * accumulated usage mask.
2786 */
2787 bfs_init_rootb(&this, prev);
2788
2789 ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, usage_skip, NULL);
2790 if (bfs_error(ret)) {
2791 print_bfs_bug(ret);
2792 return 0;
2793 }
2794
2795 usage_mask &= LOCKF_USED_IN_IRQ_ALL;
2796 if (!usage_mask)
2797 return 1;
2798
2799 /*
2800 * Step 2: find exclusive uses forward that match the previous
2801 * backward accumulated mask.
2802 */
2803 forward_mask = exclusive_mask(usage_mask);
2804
2805 bfs_init_root(&that, next);
2806
2807 ret = find_usage_forwards(&that, forward_mask, &target_entry1);
2808 if (bfs_error(ret)) {
2809 print_bfs_bug(ret);
2810 return 0;
2811 }
2812 if (ret == BFS_RNOMATCH)
2813 return 1;
2814
2815 /*
2816 * Step 3: we found a bad match! Now retrieve a lock from the backward
2817 * list whose usage mask matches the exclusive usage mask from the
2818 * lock found on the forward list.
2819 *
2820 * Note, we should only keep the LOCKF_ENABLED_IRQ_ALL bits, considering
2821 * the follow case:
2822 *
2823 * When trying to add A -> B to the graph, we find that there is a
2824 * hardirq-safe L, that L -> ... -> A, and another hardirq-unsafe M,
2825 * that B -> ... -> M. However M is **softirq-safe**, if we use exact
2826 * invert bits of M's usage_mask, we will find another lock N that is
2827 * **softirq-unsafe** and N -> ... -> A, however N -> .. -> M will not
2828 * cause a inversion deadlock.
2829 */
2830 backward_mask = original_mask(target_entry1->class->usage_mask & LOCKF_ENABLED_IRQ_ALL);
2831
2832 ret = find_usage_backwards(&this, backward_mask, &target_entry);
2833 if (bfs_error(ret)) {
2834 print_bfs_bug(ret);
2835 return 0;
2836 }
2837 if (DEBUG_LOCKS_WARN_ON(ret == BFS_RNOMATCH))
2838 return 1;
2839
2840 /*
2841 * Step 4: narrow down to a pair of incompatible usage bits
2842 * and report it.
2843 */
2844 ret = find_exclusive_match(target_entry->class->usage_mask,
2845 target_entry1->class->usage_mask,
2846 &backward_bit, &forward_bit);
2847 if (DEBUG_LOCKS_WARN_ON(ret == -1))
2848 return 1;
2849
2850 print_bad_irq_dependency(curr, &this, &that,
2851 target_entry, target_entry1,
2852 prev, next,
2853 backward_bit, forward_bit,
2854 state_name(backward_bit));
2855
2856 return 0;
2857}
2858
2859#else
2860
2861static inline int check_irq_usage(struct task_struct *curr,
2862 struct held_lock *prev, struct held_lock *next)
2863{
2864 return 1;
2865}
2866
2867static inline bool usage_skip(struct lock_list *entry, void *mask)
2868{
2869 return false;
2870}
2871
2872#endif /* CONFIG_TRACE_IRQFLAGS */
2873
2874#ifdef CONFIG_LOCKDEP_SMALL
2875/*
2876 * Check that the dependency graph starting at <src> can lead to
2877 * <target> or not. If it can, <src> -> <target> dependency is already
2878 * in the graph.
2879 *
2880 * Return BFS_RMATCH if it does, or BFS_RNOMATCH if it does not, return BFS_E* if
2881 * any error appears in the bfs search.
2882 */
2883static noinline enum bfs_result
2884check_redundant(struct held_lock *src, struct held_lock *target)
2885{
2886 enum bfs_result ret;
2887 struct lock_list *target_entry;
2888 struct lock_list src_entry;
2889
2890 bfs_init_root(&src_entry, src);
2891 /*
2892 * Special setup for check_redundant().
2893 *
2894 * To report redundant, we need to find a strong dependency path that
2895 * is equal to or stronger than <src> -> <target>. So if <src> is E,
2896 * we need to let __bfs() only search for a path starting at a -(E*)->,
2897 * we achieve this by setting the initial node's ->only_xr to true in
2898 * that case. And if <prev> is S, we set initial ->only_xr to false
2899 * because both -(S*)-> (equal) and -(E*)-> (stronger) are redundant.
2900 */
2901 src_entry.only_xr = src->read == 0;
2902
2903 debug_atomic_inc(nr_redundant_checks);
2904
2905 /*
2906 * Note: we skip local_lock() for redundant check, because as the
2907 * comment in usage_skip(), A -> local_lock() -> B and A -> B are not
2908 * the same.
2909 */
2910 ret = check_path(target, &src_entry, hlock_equal, usage_skip, &target_entry);
2911
2912 if (ret == BFS_RMATCH)
2913 debug_atomic_inc(nr_redundant);
2914
2915 return ret;
2916}
2917
2918#else
2919
2920static inline enum bfs_result
2921check_redundant(struct held_lock *src, struct held_lock *target)
2922{
2923 return BFS_RNOMATCH;
2924}
2925
2926#endif
2927
2928static void inc_chains(int irq_context)
2929{
2930 if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
2931 nr_hardirq_chains++;
2932 else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
2933 nr_softirq_chains++;
2934 else
2935 nr_process_chains++;
2936}
2937
2938static void dec_chains(int irq_context)
2939{
2940 if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
2941 nr_hardirq_chains--;
2942 else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
2943 nr_softirq_chains--;
2944 else
2945 nr_process_chains--;
2946}
2947
2948static void
2949print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
2950{
2951 struct lock_class *next = hlock_class(nxt);
2952 struct lock_class *prev = hlock_class(prv);
2953
2954 printk(" Possible unsafe locking scenario:\n\n");
2955 printk(" CPU0\n");
2956 printk(" ----\n");
2957 printk(" lock(");
2958 __print_lock_name(prev);
2959 printk(KERN_CONT ");\n");
2960 printk(" lock(");
2961 __print_lock_name(next);
2962 printk(KERN_CONT ");\n");
2963 printk("\n *** DEADLOCK ***\n\n");
2964 printk(" May be due to missing lock nesting notation\n\n");
2965}
2966
2967static void
2968print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
2969 struct held_lock *next)
2970{
2971 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2972 return;
2973
2974 pr_warn("\n");
2975 pr_warn("============================================\n");
2976 pr_warn("WARNING: possible recursive locking detected\n");
2977 print_kernel_ident();
2978 pr_warn("--------------------------------------------\n");
2979 pr_warn("%s/%d is trying to acquire lock:\n",
2980 curr->comm, task_pid_nr(curr));
2981 print_lock(next);
2982 pr_warn("\nbut task is already holding lock:\n");
2983 print_lock(prev);
2984
2985 pr_warn("\nother info that might help us debug this:\n");
2986 print_deadlock_scenario(next, prev);
2987 lockdep_print_held_locks(curr);
2988
2989 pr_warn("\nstack backtrace:\n");
2990 dump_stack();
2991}
2992
2993/*
2994 * Check whether we are holding such a class already.
2995 *
2996 * (Note that this has to be done separately, because the graph cannot
2997 * detect such classes of deadlocks.)
2998 *
2999 * Returns: 0 on deadlock detected, 1 on OK, 2 if another lock with the same
3000 * lock class is held but nest_lock is also held, i.e. we rely on the
3001 * nest_lock to avoid the deadlock.
3002 */
3003static int
3004check_deadlock(struct task_struct *curr, struct held_lock *next)
3005{
3006 struct held_lock *prev;
3007 struct held_lock *nest = NULL;
3008 int i;
3009
3010 for (i = 0; i < curr->lockdep_depth; i++) {
3011 prev = curr->held_locks + i;
3012
3013 if (prev->instance == next->nest_lock)
3014 nest = prev;
3015
3016 if (hlock_class(prev) != hlock_class(next))
3017 continue;
3018
3019 /*
3020 * Allow read-after-read recursion of the same
3021 * lock class (i.e. read_lock(lock)+read_lock(lock)):
3022 */
3023 if ((next->read == 2) && prev->read)
3024 continue;
3025
3026 /*
3027 * We're holding the nest_lock, which serializes this lock's
3028 * nesting behaviour.
3029 */
3030 if (nest)
3031 return 2;
3032
3033 print_deadlock_bug(curr, prev, next);
3034 return 0;
3035 }
3036 return 1;
3037}
3038
3039/*
3040 * There was a chain-cache miss, and we are about to add a new dependency
3041 * to a previous lock. We validate the following rules:
3042 *
3043 * - would the adding of the <prev> -> <next> dependency create a
3044 * circular dependency in the graph? [== circular deadlock]
3045 *
3046 * - does the new prev->next dependency connect any hardirq-safe lock
3047 * (in the full backwards-subgraph starting at <prev>) with any
3048 * hardirq-unsafe lock (in the full forwards-subgraph starting at
3049 * <next>)? [== illegal lock inversion with hardirq contexts]
3050 *
3051 * - does the new prev->next dependency connect any softirq-safe lock
3052 * (in the full backwards-subgraph starting at <prev>) with any
3053 * softirq-unsafe lock (in the full forwards-subgraph starting at
3054 * <next>)? [== illegal lock inversion with softirq contexts]
3055 *
3056 * any of these scenarios could lead to a deadlock.
3057 *
3058 * Then if all the validations pass, we add the forwards and backwards
3059 * dependency.
3060 */
3061static int
3062check_prev_add(struct task_struct *curr, struct held_lock *prev,
3063 struct held_lock *next, u16 distance,
3064 struct lock_trace **const trace)
3065{
3066 struct lock_list *entry;
3067 enum bfs_result ret;
3068
3069 if (!hlock_class(prev)->key || !hlock_class(next)->key) {
3070 /*
3071 * The warning statements below may trigger a use-after-free
3072 * of the class name. It is better to trigger a use-after free
3073 * and to have the class name most of the time instead of not
3074 * having the class name available.
3075 */
3076 WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key,
3077 "Detected use-after-free of lock class %px/%s\n",
3078 hlock_class(prev),
3079 hlock_class(prev)->name);
3080 WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key,
3081 "Detected use-after-free of lock class %px/%s\n",
3082 hlock_class(next),
3083 hlock_class(next)->name);
3084 return 2;
3085 }
3086
3087 /*
3088 * Prove that the new <prev> -> <next> dependency would not
3089 * create a circular dependency in the graph. (We do this by
3090 * a breadth-first search into the graph starting at <next>,
3091 * and check whether we can reach <prev>.)
3092 *
3093 * The search is limited by the size of the circular queue (i.e.,
3094 * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes
3095 * in the graph whose neighbours are to be checked.
3096 */
3097 ret = check_noncircular(next, prev, trace);
3098 if (unlikely(bfs_error(ret) || ret == BFS_RMATCH))
3099 return 0;
3100
3101 if (!check_irq_usage(curr, prev, next))
3102 return 0;
3103
3104 /*
3105 * Is the <prev> -> <next> dependency already present?
3106 *
3107 * (this may occur even though this is a new chain: consider
3108 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
3109 * chains - the second one will be new, but L1 already has
3110 * L2 added to its dependency list, due to the first chain.)
3111 */
3112 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
3113 if (entry->class == hlock_class(next)) {
3114 if (distance == 1)
3115 entry->distance = 1;
3116 entry->dep |= calc_dep(prev, next);
3117
3118 /*
3119 * Also, update the reverse dependency in @next's
3120 * ->locks_before list.
3121 *
3122 * Here we reuse @entry as the cursor, which is fine
3123 * because we won't go to the next iteration of the
3124 * outer loop:
3125 *
3126 * For normal cases, we return in the inner loop.
3127 *
3128 * If we fail to return, we have inconsistency, i.e.
3129 * <prev>::locks_after contains <next> while
3130 * <next>::locks_before doesn't contain <prev>. In
3131 * that case, we return after the inner and indicate
3132 * something is wrong.
3133 */
3134 list_for_each_entry(entry, &hlock_class(next)->locks_before, entry) {
3135 if (entry->class == hlock_class(prev)) {
3136 if (distance == 1)
3137 entry->distance = 1;
3138 entry->dep |= calc_depb(prev, next);
3139 return 1;
3140 }
3141 }
3142
3143 /* <prev> is not found in <next>::locks_before */
3144 return 0;
3145 }
3146 }
3147
3148 /*
3149 * Is the <prev> -> <next> link redundant?
3150 */
3151 ret = check_redundant(prev, next);
3152 if (bfs_error(ret))
3153 return 0;
3154 else if (ret == BFS_RMATCH)
3155 return 2;
3156
3157 if (!*trace) {
3158 *trace = save_trace();
3159 if (!*trace)
3160 return 0;
3161 }
3162
3163 /*
3164 * Ok, all validations passed, add the new lock
3165 * to the previous lock's dependency list:
3166 */
3167 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
3168 &hlock_class(prev)->locks_after, distance,
3169 calc_dep(prev, next), *trace);
3170
3171 if (!ret)
3172 return 0;
3173
3174 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
3175 &hlock_class(next)->locks_before, distance,
3176 calc_depb(prev, next), *trace);
3177 if (!ret)
3178 return 0;
3179
3180 return 2;
3181}
3182
3183/*
3184 * Add the dependency to all directly-previous locks that are 'relevant'.
3185 * The ones that are relevant are (in increasing distance from curr):
3186 * all consecutive trylock entries and the final non-trylock entry - or
3187 * the end of this context's lock-chain - whichever comes first.
3188 */
3189static int
3190check_prevs_add(struct task_struct *curr, struct held_lock *next)
3191{
3192 struct lock_trace *trace = NULL;
3193 int depth = curr->lockdep_depth;
3194 struct held_lock *hlock;
3195
3196 /*
3197 * Debugging checks.
3198 *
3199 * Depth must not be zero for a non-head lock:
3200 */
3201 if (!depth)
3202 goto out_bug;
3203 /*
3204 * At least two relevant locks must exist for this
3205 * to be a head:
3206 */
3207 if (curr->held_locks[depth].irq_context !=
3208 curr->held_locks[depth-1].irq_context)
3209 goto out_bug;
3210
3211 for (;;) {
3212 u16 distance = curr->lockdep_depth - depth + 1;
3213 hlock = curr->held_locks + depth - 1;
3214
3215 if (hlock->check) {
3216 int ret = check_prev_add(curr, hlock, next, distance, &trace);
3217 if (!ret)
3218 return 0;
3219
3220 /*
3221 * Stop after the first non-trylock entry,
3222 * as non-trylock entries have added their
3223 * own direct dependencies already, so this
3224 * lock is connected to them indirectly:
3225 */
3226 if (!hlock->trylock)
3227 break;
3228 }
3229
3230 depth--;
3231 /*
3232 * End of lock-stack?
3233 */
3234 if (!depth)
3235 break;
3236 /*
3237 * Stop the search if we cross into another context:
3238 */
3239 if (curr->held_locks[depth].irq_context !=
3240 curr->held_locks[depth-1].irq_context)
3241 break;
3242 }
3243 return 1;
3244out_bug:
3245 if (!debug_locks_off_graph_unlock())
3246 return 0;
3247
3248 /*
3249 * Clearly we all shouldn't be here, but since we made it we
3250 * can reliable say we messed up our state. See the above two
3251 * gotos for reasons why we could possibly end up here.
3252 */
3253 WARN_ON(1);
3254
3255 return 0;
3256}
3257
3258struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
3259static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS);
3260static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
3261unsigned long nr_zapped_lock_chains;
3262unsigned int nr_free_chain_hlocks; /* Free chain_hlocks in buckets */
3263unsigned int nr_lost_chain_hlocks; /* Lost chain_hlocks */
3264unsigned int nr_large_chain_blocks; /* size > MAX_CHAIN_BUCKETS */
3265
3266/*
3267 * The first 2 chain_hlocks entries in the chain block in the bucket
3268 * list contains the following meta data:
3269 *
3270 * entry[0]:
3271 * Bit 15 - always set to 1 (it is not a class index)
3272 * Bits 0-14 - upper 15 bits of the next block index
3273 * entry[1] - lower 16 bits of next block index
3274 *
3275 * A next block index of all 1 bits means it is the end of the list.
3276 *
3277 * On the unsized bucket (bucket-0), the 3rd and 4th entries contain
3278 * the chain block size:
3279 *
3280 * entry[2] - upper 16 bits of the chain block size
3281 * entry[3] - lower 16 bits of the chain block size
3282 */
3283#define MAX_CHAIN_BUCKETS 16
3284#define CHAIN_BLK_FLAG (1U << 15)
3285#define CHAIN_BLK_LIST_END 0xFFFFU
3286
3287static int chain_block_buckets[MAX_CHAIN_BUCKETS];
3288
3289static inline int size_to_bucket(int size)
3290{
3291 if (size > MAX_CHAIN_BUCKETS)
3292 return 0;
3293
3294 return size - 1;
3295}
3296
3297/*
3298 * Iterate all the chain blocks in a bucket.
3299 */
3300#define for_each_chain_block(bucket, prev, curr) \
3301 for ((prev) = -1, (curr) = chain_block_buckets[bucket]; \
3302 (curr) >= 0; \
3303 (prev) = (curr), (curr) = chain_block_next(curr))
3304
3305/*
3306 * next block or -1
3307 */
3308static inline int chain_block_next(int offset)
3309{
3310 int next = chain_hlocks[offset];
3311
3312 WARN_ON_ONCE(!(next & CHAIN_BLK_FLAG));
3313
3314 if (next == CHAIN_BLK_LIST_END)
3315 return -1;
3316
3317 next &= ~CHAIN_BLK_FLAG;
3318 next <<= 16;
3319 next |= chain_hlocks[offset + 1];
3320
3321 return next;
3322}
3323
3324/*
3325 * bucket-0 only
3326 */
3327static inline int chain_block_size(int offset)
3328{
3329 return (chain_hlocks[offset + 2] << 16) | chain_hlocks[offset + 3];
3330}
3331
3332static inline void init_chain_block(int offset, int next, int bucket, int size)
3333{
3334 chain_hlocks[offset] = (next >> 16) | CHAIN_BLK_FLAG;
3335 chain_hlocks[offset + 1] = (u16)next;
3336
3337 if (size && !bucket) {
3338 chain_hlocks[offset + 2] = size >> 16;
3339 chain_hlocks[offset + 3] = (u16)size;
3340 }
3341}
3342
3343static inline void add_chain_block(int offset, int size)
3344{
3345 int bucket = size_to_bucket(size);
3346 int next = chain_block_buckets[bucket];
3347 int prev, curr;
3348
3349 if (unlikely(size < 2)) {
3350 /*
3351 * We can't store single entries on the freelist. Leak them.
3352 *
3353 * One possible way out would be to uniquely mark them, other
3354 * than with CHAIN_BLK_FLAG, such that we can recover them when
3355 * the block before it is re-added.
3356 */
3357 if (size)
3358 nr_lost_chain_hlocks++;
3359 return;
3360 }
3361
3362 nr_free_chain_hlocks += size;
3363 if (!bucket) {
3364 nr_large_chain_blocks++;
3365
3366 /*
3367 * Variable sized, sort large to small.
3368 */
3369 for_each_chain_block(0, prev, curr) {
3370 if (size >= chain_block_size(curr))
3371 break;
3372 }
3373 init_chain_block(offset, curr, 0, size);
3374 if (prev < 0)
3375 chain_block_buckets[0] = offset;
3376 else
3377 init_chain_block(prev, offset, 0, 0);
3378 return;
3379 }
3380 /*
3381 * Fixed size, add to head.
3382 */
3383 init_chain_block(offset, next, bucket, size);
3384 chain_block_buckets[bucket] = offset;
3385}
3386
3387/*
3388 * Only the first block in the list can be deleted.
3389 *
3390 * For the variable size bucket[0], the first block (the largest one) is
3391 * returned, broken up and put back into the pool. So if a chain block of
3392 * length > MAX_CHAIN_BUCKETS is ever used and zapped, it will just be
3393 * queued up after the primordial chain block and never be used until the
3394 * hlock entries in the primordial chain block is almost used up. That
3395 * causes fragmentation and reduce allocation efficiency. That can be
3396 * monitored by looking at the "large chain blocks" number in lockdep_stats.
3397 */
3398static inline void del_chain_block(int bucket, int size, int next)
3399{
3400 nr_free_chain_hlocks -= size;
3401 chain_block_buckets[bucket] = next;
3402
3403 if (!bucket)
3404 nr_large_chain_blocks--;
3405}
3406
3407static void init_chain_block_buckets(void)
3408{
3409 int i;
3410
3411 for (i = 0; i < MAX_CHAIN_BUCKETS; i++)
3412 chain_block_buckets[i] = -1;
3413
3414 add_chain_block(0, ARRAY_SIZE(chain_hlocks));
3415}
3416
3417/*
3418 * Return offset of a chain block of the right size or -1 if not found.
3419 *
3420 * Fairly simple worst-fit allocator with the addition of a number of size
3421 * specific free lists.
3422 */
3423static int alloc_chain_hlocks(int req)
3424{
3425 int bucket, curr, size;
3426
3427 /*
3428 * We rely on the MSB to act as an escape bit to denote freelist
3429 * pointers. Make sure this bit isn't set in 'normal' class_idx usage.
3430 */
3431 BUILD_BUG_ON((MAX_LOCKDEP_KEYS-1) & CHAIN_BLK_FLAG);
3432
3433 init_data_structures_once();
3434
3435 if (nr_free_chain_hlocks < req)
3436 return -1;
3437
3438 /*
3439 * We require a minimum of 2 (u16) entries to encode a freelist
3440 * 'pointer'.
3441 */
3442 req = max(req, 2);
3443 bucket = size_to_bucket(req);
3444 curr = chain_block_buckets[bucket];
3445
3446 if (bucket) {
3447 if (curr >= 0) {
3448 del_chain_block(bucket, req, chain_block_next(curr));
3449 return curr;
3450 }
3451 /* Try bucket 0 */
3452 curr = chain_block_buckets[0];
3453 }
3454
3455 /*
3456 * The variable sized freelist is sorted by size; the first entry is
3457 * the largest. Use it if it fits.
3458 */
3459 if (curr >= 0) {
3460 size = chain_block_size(curr);
3461 if (likely(size >= req)) {
3462 del_chain_block(0, size, chain_block_next(curr));
3463 add_chain_block(curr + req, size - req);
3464 return curr;
3465 }
3466 }
3467
3468 /*
3469 * Last resort, split a block in a larger sized bucket.
3470 */
3471 for (size = MAX_CHAIN_BUCKETS; size > req; size--) {
3472 bucket = size_to_bucket(size);
3473 curr = chain_block_buckets[bucket];
3474 if (curr < 0)
3475 continue;
3476
3477 del_chain_block(bucket, size, chain_block_next(curr));
3478 add_chain_block(curr + req, size - req);
3479 return curr;
3480 }
3481
3482 return -1;
3483}
3484
3485static inline void free_chain_hlocks(int base, int size)
3486{
3487 add_chain_block(base, max(size, 2));
3488}
3489
3490struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
3491{
3492 u16 chain_hlock = chain_hlocks[chain->base + i];
3493 unsigned int class_idx = chain_hlock_class_idx(chain_hlock);
3494
3495 return lock_classes + class_idx;
3496}
3497
3498/*
3499 * Returns the index of the first held_lock of the current chain
3500 */
3501static inline int get_first_held_lock(struct task_struct *curr,
3502 struct held_lock *hlock)
3503{
3504 int i;
3505 struct held_lock *hlock_curr;
3506
3507 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
3508 hlock_curr = curr->held_locks + i;
3509 if (hlock_curr->irq_context != hlock->irq_context)
3510 break;
3511
3512 }
3513
3514 return ++i;
3515}
3516
3517#ifdef CONFIG_DEBUG_LOCKDEP
3518/*
3519 * Returns the next chain_key iteration
3520 */
3521static u64 print_chain_key_iteration(u16 hlock_id, u64 chain_key)
3522{
3523 u64 new_chain_key = iterate_chain_key(chain_key, hlock_id);
3524
3525 printk(" hlock_id:%d -> chain_key:%016Lx",
3526 (unsigned int)hlock_id,
3527 (unsigned long long)new_chain_key);
3528 return new_chain_key;
3529}
3530
3531static void
3532print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
3533{
3534 struct held_lock *hlock;
3535 u64 chain_key = INITIAL_CHAIN_KEY;
3536 int depth = curr->lockdep_depth;
3537 int i = get_first_held_lock(curr, hlock_next);
3538
3539 printk("depth: %u (irq_context %u)\n", depth - i + 1,
3540 hlock_next->irq_context);
3541 for (; i < depth; i++) {
3542 hlock = curr->held_locks + i;
3543 chain_key = print_chain_key_iteration(hlock_id(hlock), chain_key);
3544
3545 print_lock(hlock);
3546 }
3547
3548 print_chain_key_iteration(hlock_id(hlock_next), chain_key);
3549 print_lock(hlock_next);
3550}
3551
3552static void print_chain_keys_chain(struct lock_chain *chain)
3553{
3554 int i;
3555 u64 chain_key = INITIAL_CHAIN_KEY;
3556 u16 hlock_id;
3557
3558 printk("depth: %u\n", chain->depth);
3559 for (i = 0; i < chain->depth; i++) {
3560 hlock_id = chain_hlocks[chain->base + i];
3561 chain_key = print_chain_key_iteration(hlock_id, chain_key);
3562
3563 print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id));
3564 printk("\n");
3565 }
3566}
3567
3568static void print_collision(struct task_struct *curr,
3569 struct held_lock *hlock_next,
3570 struct lock_chain *chain)
3571{
3572 pr_warn("\n");
3573 pr_warn("============================\n");
3574 pr_warn("WARNING: chain_key collision\n");
3575 print_kernel_ident();
3576 pr_warn("----------------------------\n");
3577 pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
3578 pr_warn("Hash chain already cached but the contents don't match!\n");
3579
3580 pr_warn("Held locks:");
3581 print_chain_keys_held_locks(curr, hlock_next);
3582
3583 pr_warn("Locks in cached chain:");
3584 print_chain_keys_chain(chain);
3585
3586 pr_warn("\nstack backtrace:\n");
3587 dump_stack();
3588}
3589#endif
3590
3591/*
3592 * Checks whether the chain and the current held locks are consistent
3593 * in depth and also in content. If they are not it most likely means
3594 * that there was a collision during the calculation of the chain_key.
3595 * Returns: 0 not passed, 1 passed
3596 */
3597static int check_no_collision(struct task_struct *curr,
3598 struct held_lock *hlock,
3599 struct lock_chain *chain)
3600{
3601#ifdef CONFIG_DEBUG_LOCKDEP
3602 int i, j, id;
3603
3604 i = get_first_held_lock(curr, hlock);
3605
3606 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
3607 print_collision(curr, hlock, chain);
3608 return 0;
3609 }
3610
3611 for (j = 0; j < chain->depth - 1; j++, i++) {
3612 id = hlock_id(&curr->held_locks[i]);
3613
3614 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
3615 print_collision(curr, hlock, chain);
3616 return 0;
3617 }
3618 }
3619#endif
3620 return 1;
3621}
3622
3623/*
3624 * Given an index that is >= -1, return the index of the next lock chain.
3625 * Return -2 if there is no next lock chain.
3626 */
3627long lockdep_next_lockchain(long i)
3628{
3629 i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1);
3630 return i < ARRAY_SIZE(lock_chains) ? i : -2;
3631}
3632
3633unsigned long lock_chain_count(void)
3634{
3635 return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains));
3636}
3637
3638/* Must be called with the graph lock held. */
3639static struct lock_chain *alloc_lock_chain(void)
3640{
3641 int idx = find_first_zero_bit(lock_chains_in_use,
3642 ARRAY_SIZE(lock_chains));
3643
3644 if (unlikely(idx >= ARRAY_SIZE(lock_chains)))
3645 return NULL;
3646 __set_bit(idx, lock_chains_in_use);
3647 return lock_chains + idx;
3648}
3649
3650/*
3651 * Adds a dependency chain into chain hashtable. And must be called with
3652 * graph_lock held.
3653 *
3654 * Return 0 if fail, and graph_lock is released.
3655 * Return 1 if succeed, with graph_lock held.
3656 */
3657static inline int add_chain_cache(struct task_struct *curr,
3658 struct held_lock *hlock,
3659 u64 chain_key)
3660{
3661 struct hlist_head *hash_head = chainhashentry(chain_key);
3662 struct lock_chain *chain;
3663 int i, j;
3664
3665 /*
3666 * The caller must hold the graph lock, ensure we've got IRQs
3667 * disabled to make this an IRQ-safe lock.. for recursion reasons
3668 * lockdep won't complain about its own locking errors.
3669 */
3670 if (lockdep_assert_locked())
3671 return 0;
3672
3673 chain = alloc_lock_chain();
3674 if (!chain) {
3675 if (!debug_locks_off_graph_unlock())
3676 return 0;
3677
3678 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
3679 dump_stack();
3680 return 0;
3681 }
3682 chain->chain_key = chain_key;
3683 chain->irq_context = hlock->irq_context;
3684 i = get_first_held_lock(curr, hlock);
3685 chain->depth = curr->lockdep_depth + 1 - i;
3686
3687 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
3688 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
3689 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
3690
3691 j = alloc_chain_hlocks(chain->depth);
3692 if (j < 0) {
3693 if (!debug_locks_off_graph_unlock())
3694 return 0;
3695
3696 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
3697 dump_stack();
3698 return 0;
3699 }
3700
3701 chain->base = j;
3702 for (j = 0; j < chain->depth - 1; j++, i++) {
3703 int lock_id = hlock_id(curr->held_locks + i);
3704
3705 chain_hlocks[chain->base + j] = lock_id;
3706 }
3707 chain_hlocks[chain->base + j] = hlock_id(hlock);
3708 hlist_add_head_rcu(&chain->entry, hash_head);
3709 debug_atomic_inc(chain_lookup_misses);
3710 inc_chains(chain->irq_context);
3711
3712 return 1;
3713}
3714
3715/*
3716 * Look up a dependency chain. Must be called with either the graph lock or
3717 * the RCU read lock held.
3718 */
3719static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
3720{
3721 struct hlist_head *hash_head = chainhashentry(chain_key);
3722 struct lock_chain *chain;
3723
3724 hlist_for_each_entry_rcu(chain, hash_head, entry) {
3725 if (READ_ONCE(chain->chain_key) == chain_key) {
3726 debug_atomic_inc(chain_lookup_hits);
3727 return chain;
3728 }
3729 }
3730 return NULL;
3731}
3732
3733/*
3734 * If the key is not present yet in dependency chain cache then
3735 * add it and return 1 - in this case the new dependency chain is
3736 * validated. If the key is already hashed, return 0.
3737 * (On return with 1 graph_lock is held.)
3738 */
3739static inline int lookup_chain_cache_add(struct task_struct *curr,
3740 struct held_lock *hlock,
3741 u64 chain_key)
3742{
3743 struct lock_class *class = hlock_class(hlock);
3744 struct lock_chain *chain = lookup_chain_cache(chain_key);
3745
3746 if (chain) {
3747cache_hit:
3748 if (!check_no_collision(curr, hlock, chain))
3749 return 0;
3750
3751 if (very_verbose(class)) {
3752 printk("\nhash chain already cached, key: "
3753 "%016Lx tail class: [%px] %s\n",
3754 (unsigned long long)chain_key,
3755 class->key, class->name);
3756 }
3757
3758 return 0;
3759 }
3760
3761 if (very_verbose(class)) {
3762 printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
3763 (unsigned long long)chain_key, class->key, class->name);
3764 }
3765
3766 if (!graph_lock())
3767 return 0;
3768
3769 /*
3770 * We have to walk the chain again locked - to avoid duplicates:
3771 */
3772 chain = lookup_chain_cache(chain_key);
3773 if (chain) {
3774 graph_unlock();
3775 goto cache_hit;
3776 }
3777
3778 if (!add_chain_cache(curr, hlock, chain_key))
3779 return 0;
3780
3781 return 1;
3782}
3783
3784static int validate_chain(struct task_struct *curr,
3785 struct held_lock *hlock,
3786 int chain_head, u64 chain_key)
3787{
3788 /*
3789 * Trylock needs to maintain the stack of held locks, but it
3790 * does not add new dependencies, because trylock can be done
3791 * in any order.
3792 *
3793 * We look up the chain_key and do the O(N^2) check and update of
3794 * the dependencies only if this is a new dependency chain.
3795 * (If lookup_chain_cache_add() return with 1 it acquires
3796 * graph_lock for us)
3797 */
3798 if (!hlock->trylock && hlock->check &&
3799 lookup_chain_cache_add(curr, hlock, chain_key)) {
3800 /*
3801 * Check whether last held lock:
3802 *
3803 * - is irq-safe, if this lock is irq-unsafe
3804 * - is softirq-safe, if this lock is hardirq-unsafe
3805 *
3806 * And check whether the new lock's dependency graph
3807 * could lead back to the previous lock:
3808 *
3809 * - within the current held-lock stack
3810 * - across our accumulated lock dependency records
3811 *
3812 * any of these scenarios could lead to a deadlock.
3813 */
3814 /*
3815 * The simple case: does the current hold the same lock
3816 * already?
3817 */
3818 int ret = check_deadlock(curr, hlock);
3819
3820 if (!ret)
3821 return 0;
3822 /*
3823 * Add dependency only if this lock is not the head
3824 * of the chain, and if the new lock introduces no more
3825 * lock dependency (because we already hold a lock with the
3826 * same lock class) nor deadlock (because the nest_lock
3827 * serializes nesting locks), see the comments for
3828 * check_deadlock().
3829 */
3830 if (!chain_head && ret != 2) {
3831 if (!check_prevs_add(curr, hlock))
3832 return 0;
3833 }
3834
3835 graph_unlock();
3836 } else {
3837 /* after lookup_chain_cache_add(): */
3838 if (unlikely(!debug_locks))
3839 return 0;
3840 }
3841
3842 return 1;
3843}
3844#else
3845static inline int validate_chain(struct task_struct *curr,
3846 struct held_lock *hlock,
3847 int chain_head, u64 chain_key)
3848{
3849 return 1;
3850}
3851
3852static void init_chain_block_buckets(void) { }
3853#endif /* CONFIG_PROVE_LOCKING */
3854
3855/*
3856 * We are building curr_chain_key incrementally, so double-check
3857 * it from scratch, to make sure that it's done correctly:
3858 */
3859static void check_chain_key(struct task_struct *curr)
3860{
3861#ifdef CONFIG_DEBUG_LOCKDEP
3862 struct held_lock *hlock, *prev_hlock = NULL;
3863 unsigned int i;
3864 u64 chain_key = INITIAL_CHAIN_KEY;
3865
3866 for (i = 0; i < curr->lockdep_depth; i++) {
3867 hlock = curr->held_locks + i;
3868 if (chain_key != hlock->prev_chain_key) {
3869 debug_locks_off();
3870 /*
3871 * We got mighty confused, our chain keys don't match
3872 * with what we expect, someone trample on our task state?
3873 */
3874 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
3875 curr->lockdep_depth, i,
3876 (unsigned long long)chain_key,
3877 (unsigned long long)hlock->prev_chain_key);
3878 return;
3879 }
3880
3881 /*
3882 * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is
3883 * it registered lock class index?
3884 */
3885 if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use)))
3886 return;
3887
3888 if (prev_hlock && (prev_hlock->irq_context !=
3889 hlock->irq_context))
3890 chain_key = INITIAL_CHAIN_KEY;
3891 chain_key = iterate_chain_key(chain_key, hlock_id(hlock));
3892 prev_hlock = hlock;
3893 }
3894 if (chain_key != curr->curr_chain_key) {
3895 debug_locks_off();
3896 /*
3897 * More smoking hash instead of calculating it, damn see these
3898 * numbers float.. I bet that a pink elephant stepped on my memory.
3899 */
3900 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
3901 curr->lockdep_depth, i,
3902 (unsigned long long)chain_key,
3903 (unsigned long long)curr->curr_chain_key);
3904 }
3905#endif
3906}
3907
3908#ifdef CONFIG_PROVE_LOCKING
3909static int mark_lock(struct task_struct *curr, struct held_lock *this,
3910 enum lock_usage_bit new_bit);
3911
3912static void print_usage_bug_scenario(struct held_lock *lock)
3913{
3914 struct lock_class *class = hlock_class(lock);
3915
3916 printk(" Possible unsafe locking scenario:\n\n");
3917 printk(" CPU0\n");
3918 printk(" ----\n");
3919 printk(" lock(");
3920 __print_lock_name(class);
3921 printk(KERN_CONT ");\n");
3922 printk(" <Interrupt>\n");
3923 printk(" lock(");
3924 __print_lock_name(class);
3925 printk(KERN_CONT ");\n");
3926 printk("\n *** DEADLOCK ***\n\n");
3927}
3928
3929static void
3930print_usage_bug(struct task_struct *curr, struct held_lock *this,
3931 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
3932{
3933 if (!debug_locks_off() || debug_locks_silent)
3934 return;
3935
3936 pr_warn("\n");
3937 pr_warn("================================\n");
3938 pr_warn("WARNING: inconsistent lock state\n");
3939 print_kernel_ident();
3940 pr_warn("--------------------------------\n");
3941
3942 pr_warn("inconsistent {%s} -> {%s} usage.\n",
3943 usage_str[prev_bit], usage_str[new_bit]);
3944
3945 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
3946 curr->comm, task_pid_nr(curr),
3947 lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
3948 lockdep_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
3949 lockdep_hardirqs_enabled(),
3950 lockdep_softirqs_enabled(curr));
3951 print_lock(this);
3952
3953 pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
3954 print_lock_trace(hlock_class(this)->usage_traces[prev_bit], 1);
3955
3956 print_irqtrace_events(curr);
3957 pr_warn("\nother info that might help us debug this:\n");
3958 print_usage_bug_scenario(this);
3959
3960 lockdep_print_held_locks(curr);
3961
3962 pr_warn("\nstack backtrace:\n");
3963 dump_stack();
3964}
3965
3966/*
3967 * Print out an error if an invalid bit is set:
3968 */
3969static inline int
3970valid_state(struct task_struct *curr, struct held_lock *this,
3971 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
3972{
3973 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) {
3974 graph_unlock();
3975 print_usage_bug(curr, this, bad_bit, new_bit);
3976 return 0;
3977 }
3978 return 1;
3979}
3980
3981
3982/*
3983 * print irq inversion bug:
3984 */
3985static void
3986print_irq_inversion_bug(struct task_struct *curr,
3987 struct lock_list *root, struct lock_list *other,
3988 struct held_lock *this, int forwards,
3989 const char *irqclass)
3990{
3991 struct lock_list *entry = other;
3992 struct lock_list *middle = NULL;
3993 int depth;
3994
3995 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
3996 return;
3997
3998 pr_warn("\n");
3999 pr_warn("========================================================\n");
4000 pr_warn("WARNING: possible irq lock inversion dependency detected\n");
4001 print_kernel_ident();
4002 pr_warn("--------------------------------------------------------\n");
4003 pr_warn("%s/%d just changed the state of lock:\n",
4004 curr->comm, task_pid_nr(curr));
4005 print_lock(this);
4006 if (forwards)
4007 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
4008 else
4009 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
4010 print_lock_name(other->class);
4011 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
4012
4013 pr_warn("\nother info that might help us debug this:\n");
4014
4015 /* Find a middle lock (if one exists) */
4016 depth = get_lock_depth(other);
4017 do {
4018 if (depth == 0 && (entry != root)) {
4019 pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
4020 break;
4021 }
4022 middle = entry;
4023 entry = get_lock_parent(entry);
4024 depth--;
4025 } while (entry && entry != root && (depth >= 0));
4026 if (forwards)
4027 print_irq_lock_scenario(root, other,
4028 middle ? middle->class : root->class, other->class);
4029 else
4030 print_irq_lock_scenario(other, root,
4031 middle ? middle->class : other->class, root->class);
4032
4033 lockdep_print_held_locks(curr);
4034
4035 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
4036 root->trace = save_trace();
4037 if (!root->trace)
4038 return;
4039 print_shortest_lock_dependencies(other, root);
4040
4041 pr_warn("\nstack backtrace:\n");
4042 dump_stack();
4043}
4044
4045/*
4046 * Prove that in the forwards-direction subgraph starting at <this>
4047 * there is no lock matching <mask>:
4048 */
4049static int
4050check_usage_forwards(struct task_struct *curr, struct held_lock *this,
4051 enum lock_usage_bit bit)
4052{
4053 enum bfs_result ret;
4054 struct lock_list root;
4055 struct lock_list *target_entry;
4056 enum lock_usage_bit read_bit = bit + LOCK_USAGE_READ_MASK;
4057 unsigned usage_mask = lock_flag(bit) | lock_flag(read_bit);
4058
4059 bfs_init_root(&root, this);
4060 ret = find_usage_forwards(&root, usage_mask, &target_entry);
4061 if (bfs_error(ret)) {
4062 print_bfs_bug(ret);
4063 return 0;
4064 }
4065 if (ret == BFS_RNOMATCH)
4066 return 1;
4067
4068 /* Check whether write or read usage is the match */
4069 if (target_entry->class->usage_mask & lock_flag(bit)) {
4070 print_irq_inversion_bug(curr, &root, target_entry,
4071 this, 1, state_name(bit));
4072 } else {
4073 print_irq_inversion_bug(curr, &root, target_entry,
4074 this, 1, state_name(read_bit));
4075 }
4076
4077 return 0;
4078}
4079
4080/*
4081 * Prove that in the backwards-direction subgraph starting at <this>
4082 * there is no lock matching <mask>:
4083 */
4084static int
4085check_usage_backwards(struct task_struct *curr, struct held_lock *this,
4086 enum lock_usage_bit bit)
4087{
4088 enum bfs_result ret;
4089 struct lock_list root;
4090 struct lock_list *target_entry;
4091 enum lock_usage_bit read_bit = bit + LOCK_USAGE_READ_MASK;
4092 unsigned usage_mask = lock_flag(bit) | lock_flag(read_bit);
4093
4094 bfs_init_rootb(&root, this);
4095 ret = find_usage_backwards(&root, usage_mask, &target_entry);
4096 if (bfs_error(ret)) {
4097 print_bfs_bug(ret);
4098 return 0;
4099 }
4100 if (ret == BFS_RNOMATCH)
4101 return 1;
4102
4103 /* Check whether write or read usage is the match */
4104 if (target_entry->class->usage_mask & lock_flag(bit)) {
4105 print_irq_inversion_bug(curr, &root, target_entry,
4106 this, 0, state_name(bit));
4107 } else {
4108 print_irq_inversion_bug(curr, &root, target_entry,
4109 this, 0, state_name(read_bit));
4110 }
4111
4112 return 0;
4113}
4114
4115void print_irqtrace_events(struct task_struct *curr)
4116{
4117 const struct irqtrace_events *trace = &curr->irqtrace;
4118
4119 printk("irq event stamp: %u\n", trace->irq_events);
4120 printk("hardirqs last enabled at (%u): [<%px>] %pS\n",
4121 trace->hardirq_enable_event, (void *)trace->hardirq_enable_ip,
4122 (void *)trace->hardirq_enable_ip);
4123 printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
4124 trace->hardirq_disable_event, (void *)trace->hardirq_disable_ip,
4125 (void *)trace->hardirq_disable_ip);
4126 printk("softirqs last enabled at (%u): [<%px>] %pS\n",
4127 trace->softirq_enable_event, (void *)trace->softirq_enable_ip,
4128 (void *)trace->softirq_enable_ip);
4129 printk("softirqs last disabled at (%u): [<%px>] %pS\n",
4130 trace->softirq_disable_event, (void *)trace->softirq_disable_ip,
4131 (void *)trace->softirq_disable_ip);
4132}
4133
4134static int HARDIRQ_verbose(struct lock_class *class)
4135{
4136#if HARDIRQ_VERBOSE
4137 return class_filter(class);
4138#endif
4139 return 0;
4140}
4141
4142static int SOFTIRQ_verbose(struct lock_class *class)
4143{
4144#if SOFTIRQ_VERBOSE
4145 return class_filter(class);
4146#endif
4147 return 0;
4148}
4149
4150static int (*state_verbose_f[])(struct lock_class *class) = {
4151#define LOCKDEP_STATE(__STATE) \
4152 __STATE##_verbose,
4153#include "lockdep_states.h"
4154#undef LOCKDEP_STATE
4155};
4156
4157static inline int state_verbose(enum lock_usage_bit bit,
4158 struct lock_class *class)
4159{
4160 return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class);
4161}
4162
4163typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
4164 enum lock_usage_bit bit, const char *name);
4165
4166static int
4167mark_lock_irq(struct task_struct *curr, struct held_lock *this,
4168 enum lock_usage_bit new_bit)
4169{
4170 int excl_bit = exclusive_bit(new_bit);
4171 int read = new_bit & LOCK_USAGE_READ_MASK;
4172 int dir = new_bit & LOCK_USAGE_DIR_MASK;
4173
4174 /*
4175 * Validate that this particular lock does not have conflicting
4176 * usage states.
4177 */
4178 if (!valid_state(curr, this, new_bit, excl_bit))
4179 return 0;
4180
4181 /*
4182 * Check for read in write conflicts
4183 */
4184 if (!read && !valid_state(curr, this, new_bit,
4185 excl_bit + LOCK_USAGE_READ_MASK))
4186 return 0;
4187
4188
4189 /*
4190 * Validate that the lock dependencies don't have conflicting usage
4191 * states.
4192 */
4193 if (dir) {
4194 /*
4195 * mark ENABLED has to look backwards -- to ensure no dependee
4196 * has USED_IN state, which, again, would allow recursion deadlocks.
4197 */
4198 if (!check_usage_backwards(curr, this, excl_bit))
4199 return 0;
4200 } else {
4201 /*
4202 * mark USED_IN has to look forwards -- to ensure no dependency
4203 * has ENABLED state, which would allow recursion deadlocks.
4204 */
4205 if (!check_usage_forwards(curr, this, excl_bit))
4206 return 0;
4207 }
4208
4209 if (state_verbose(new_bit, hlock_class(this)))
4210 return 2;
4211
4212 return 1;
4213}
4214
4215/*
4216 * Mark all held locks with a usage bit:
4217 */
4218static int
4219mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit)
4220{
4221 struct held_lock *hlock;
4222 int i;
4223
4224 for (i = 0; i < curr->lockdep_depth; i++) {
4225 enum lock_usage_bit hlock_bit = base_bit;
4226 hlock = curr->held_locks + i;
4227
4228 if (hlock->read)
4229 hlock_bit += LOCK_USAGE_READ_MASK;
4230
4231 BUG_ON(hlock_bit >= LOCK_USAGE_STATES);
4232
4233 if (!hlock->check)
4234 continue;
4235
4236 if (!mark_lock(curr, hlock, hlock_bit))
4237 return 0;
4238 }
4239
4240 return 1;
4241}
4242
4243/*
4244 * Hardirqs will be enabled:
4245 */
4246static void __trace_hardirqs_on_caller(void)
4247{
4248 struct task_struct *curr = current;
4249
4250 /*
4251 * We are going to turn hardirqs on, so set the
4252 * usage bit for all held locks:
4253 */
4254 if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ))
4255 return;
4256 /*
4257 * If we have softirqs enabled, then set the usage
4258 * bit for all held locks. (disabled hardirqs prevented
4259 * this bit from being set before)
4260 */
4261 if (curr->softirqs_enabled)
4262 mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
4263}
4264
4265/**
4266 * lockdep_hardirqs_on_prepare - Prepare for enabling interrupts
4267 *
4268 * Invoked before a possible transition to RCU idle from exit to user or
4269 * guest mode. This ensures that all RCU operations are done before RCU
4270 * stops watching. After the RCU transition lockdep_hardirqs_on() has to be
4271 * invoked to set the final state.
4272 */
4273void lockdep_hardirqs_on_prepare(void)
4274{
4275 if (unlikely(!debug_locks))
4276 return;
4277
4278 /*
4279 * NMIs do not (and cannot) track lock dependencies, nothing to do.
4280 */
4281 if (unlikely(in_nmi()))
4282 return;
4283
4284 if (unlikely(this_cpu_read(lockdep_recursion)))
4285 return;
4286
4287 if (unlikely(lockdep_hardirqs_enabled())) {
4288 /*
4289 * Neither irq nor preemption are disabled here
4290 * so this is racy by nature but losing one hit
4291 * in a stat is not a big deal.
4292 */
4293 __debug_atomic_inc(redundant_hardirqs_on);
4294 return;
4295 }
4296
4297 /*
4298 * We're enabling irqs and according to our state above irqs weren't
4299 * already enabled, yet we find the hardware thinks they are in fact
4300 * enabled.. someone messed up their IRQ state tracing.
4301 */
4302 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4303 return;
4304
4305 /*
4306 * See the fine text that goes along with this variable definition.
4307 */
4308 if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled))
4309 return;
4310
4311 /*
4312 * Can't allow enabling interrupts while in an interrupt handler,
4313 * that's general bad form and such. Recursion, limited stack etc..
4314 */
4315 if (DEBUG_LOCKS_WARN_ON(lockdep_hardirq_context()))
4316 return;
4317
4318 current->hardirq_chain_key = current->curr_chain_key;
4319
4320 lockdep_recursion_inc();
4321 __trace_hardirqs_on_caller();
4322 lockdep_recursion_finish();
4323}
4324EXPORT_SYMBOL_GPL(lockdep_hardirqs_on_prepare);
4325
4326void noinstr lockdep_hardirqs_on(unsigned long ip)
4327{
4328 struct irqtrace_events *trace = &current->irqtrace;
4329
4330 if (unlikely(!debug_locks))
4331 return;
4332
4333 /*
4334 * NMIs can happen in the middle of local_irq_{en,dis}able() where the
4335 * tracking state and hardware state are out of sync.
4336 *
4337 * NMIs must save lockdep_hardirqs_enabled() to restore IRQ state from,
4338 * and not rely on hardware state like normal interrupts.
4339 */
4340 if (unlikely(in_nmi())) {
4341 if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
4342 return;
4343
4344 /*
4345 * Skip:
4346 * - recursion check, because NMI can hit lockdep;
4347 * - hardware state check, because above;
4348 * - chain_key check, see lockdep_hardirqs_on_prepare().
4349 */
4350 goto skip_checks;
4351 }
4352
4353 if (unlikely(this_cpu_read(lockdep_recursion)))
4354 return;
4355
4356 if (lockdep_hardirqs_enabled()) {
4357 /*
4358 * Neither irq nor preemption are disabled here
4359 * so this is racy by nature but losing one hit
4360 * in a stat is not a big deal.
4361 */
4362 __debug_atomic_inc(redundant_hardirqs_on);
4363 return;
4364 }
4365
4366 /*
4367 * We're enabling irqs and according to our state above irqs weren't
4368 * already enabled, yet we find the hardware thinks they are in fact
4369 * enabled.. someone messed up their IRQ state tracing.
4370 */
4371 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4372 return;
4373
4374 /*
4375 * Ensure the lock stack remained unchanged between
4376 * lockdep_hardirqs_on_prepare() and lockdep_hardirqs_on().
4377 */
4378 DEBUG_LOCKS_WARN_ON(current->hardirq_chain_key !=
4379 current->curr_chain_key);
4380
4381skip_checks:
4382 /* we'll do an OFF -> ON transition: */
4383 __this_cpu_write(hardirqs_enabled, 1);
4384 trace->hardirq_enable_ip = ip;
4385 trace->hardirq_enable_event = ++trace->irq_events;
4386 debug_atomic_inc(hardirqs_on_events);
4387}
4388EXPORT_SYMBOL_GPL(lockdep_hardirqs_on);
4389
4390/*
4391 * Hardirqs were disabled:
4392 */
4393void noinstr lockdep_hardirqs_off(unsigned long ip)
4394{
4395 if (unlikely(!debug_locks))
4396 return;
4397
4398 /*
4399 * Matching lockdep_hardirqs_on(), allow NMIs in the middle of lockdep;
4400 * they will restore the software state. This ensures the software
4401 * state is consistent inside NMIs as well.
4402 */
4403 if (in_nmi()) {
4404 if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
4405 return;
4406 } else if (__this_cpu_read(lockdep_recursion))
4407 return;
4408
4409 /*
4410 * So we're supposed to get called after you mask local IRQs, but for
4411 * some reason the hardware doesn't quite think you did a proper job.
4412 */
4413 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4414 return;
4415
4416 if (lockdep_hardirqs_enabled()) {
4417 struct irqtrace_events *trace = &current->irqtrace;
4418
4419 /*
4420 * We have done an ON -> OFF transition:
4421 */
4422 __this_cpu_write(hardirqs_enabled, 0);
4423 trace->hardirq_disable_ip = ip;
4424 trace->hardirq_disable_event = ++trace->irq_events;
4425 debug_atomic_inc(hardirqs_off_events);
4426 } else {
4427 debug_atomic_inc(redundant_hardirqs_off);
4428 }
4429}
4430EXPORT_SYMBOL_GPL(lockdep_hardirqs_off);
4431
4432/*
4433 * Softirqs will be enabled:
4434 */
4435void lockdep_softirqs_on(unsigned long ip)
4436{
4437 struct irqtrace_events *trace = &current->irqtrace;
4438
4439 if (unlikely(!lockdep_enabled()))
4440 return;
4441
4442 /*
4443 * We fancy IRQs being disabled here, see softirq.c, avoids
4444 * funny state and nesting things.
4445 */
4446 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4447 return;
4448
4449 if (current->softirqs_enabled) {
4450 debug_atomic_inc(redundant_softirqs_on);
4451 return;
4452 }
4453
4454 lockdep_recursion_inc();
4455 /*
4456 * We'll do an OFF -> ON transition:
4457 */
4458 current->softirqs_enabled = 1;
4459 trace->softirq_enable_ip = ip;
4460 trace->softirq_enable_event = ++trace->irq_events;
4461 debug_atomic_inc(softirqs_on_events);
4462 /*
4463 * We are going to turn softirqs on, so set the
4464 * usage bit for all held locks, if hardirqs are
4465 * enabled too:
4466 */
4467 if (lockdep_hardirqs_enabled())
4468 mark_held_locks(current, LOCK_ENABLED_SOFTIRQ);
4469 lockdep_recursion_finish();
4470}
4471
4472/*
4473 * Softirqs were disabled:
4474 */
4475void lockdep_softirqs_off(unsigned long ip)
4476{
4477 if (unlikely(!lockdep_enabled()))
4478 return;
4479
4480 /*
4481 * We fancy IRQs being disabled here, see softirq.c
4482 */
4483 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4484 return;
4485
4486 if (current->softirqs_enabled) {
4487 struct irqtrace_events *trace = &current->irqtrace;
4488
4489 /*
4490 * We have done an ON -> OFF transition:
4491 */
4492 current->softirqs_enabled = 0;
4493 trace->softirq_disable_ip = ip;
4494 trace->softirq_disable_event = ++trace->irq_events;
4495 debug_atomic_inc(softirqs_off_events);
4496 /*
4497 * Whoops, we wanted softirqs off, so why aren't they?
4498 */
4499 DEBUG_LOCKS_WARN_ON(!softirq_count());
4500 } else
4501 debug_atomic_inc(redundant_softirqs_off);
4502}
4503
4504static int
4505mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
4506{
4507 if (!check)
4508 goto lock_used;
4509
4510 /*
4511 * If non-trylock use in a hardirq or softirq context, then
4512 * mark the lock as used in these contexts:
4513 */
4514 if (!hlock->trylock) {
4515 if (hlock->read) {
4516 if (lockdep_hardirq_context())
4517 if (!mark_lock(curr, hlock,
4518 LOCK_USED_IN_HARDIRQ_READ))
4519 return 0;
4520 if (curr->softirq_context)
4521 if (!mark_lock(curr, hlock,
4522 LOCK_USED_IN_SOFTIRQ_READ))
4523 return 0;
4524 } else {
4525 if (lockdep_hardirq_context())
4526 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
4527 return 0;
4528 if (curr->softirq_context)
4529 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
4530 return 0;
4531 }
4532 }
4533 if (!hlock->hardirqs_off) {
4534 if (hlock->read) {
4535 if (!mark_lock(curr, hlock,
4536 LOCK_ENABLED_HARDIRQ_READ))
4537 return 0;
4538 if (curr->softirqs_enabled)
4539 if (!mark_lock(curr, hlock,
4540 LOCK_ENABLED_SOFTIRQ_READ))
4541 return 0;
4542 } else {
4543 if (!mark_lock(curr, hlock,
4544 LOCK_ENABLED_HARDIRQ))
4545 return 0;
4546 if (curr->softirqs_enabled)
4547 if (!mark_lock(curr, hlock,
4548 LOCK_ENABLED_SOFTIRQ))
4549 return 0;
4550 }
4551 }
4552
4553lock_used:
4554 /* mark it as used: */
4555 if (!mark_lock(curr, hlock, LOCK_USED))
4556 return 0;
4557
4558 return 1;
4559}
4560
4561static inline unsigned int task_irq_context(struct task_struct *task)
4562{
4563 return LOCK_CHAIN_HARDIRQ_CONTEXT * !!lockdep_hardirq_context() +
4564 LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context;
4565}
4566
4567static int separate_irq_context(struct task_struct *curr,
4568 struct held_lock *hlock)
4569{
4570 unsigned int depth = curr->lockdep_depth;
4571
4572 /*
4573 * Keep track of points where we cross into an interrupt context:
4574 */
4575 if (depth) {
4576 struct held_lock *prev_hlock;
4577
4578 prev_hlock = curr->held_locks + depth-1;
4579 /*
4580 * If we cross into another context, reset the
4581 * hash key (this also prevents the checking and the
4582 * adding of the dependency to 'prev'):
4583 */
4584 if (prev_hlock->irq_context != hlock->irq_context)
4585 return 1;
4586 }
4587 return 0;
4588}
4589
4590/*
4591 * Mark a lock with a usage bit, and validate the state transition:
4592 */
4593static int mark_lock(struct task_struct *curr, struct held_lock *this,
4594 enum lock_usage_bit new_bit)
4595{
4596 unsigned int new_mask, ret = 1;
4597
4598 if (new_bit >= LOCK_USAGE_STATES) {
4599 DEBUG_LOCKS_WARN_ON(1);
4600 return 0;
4601 }
4602
4603 if (new_bit == LOCK_USED && this->read)
4604 new_bit = LOCK_USED_READ;
4605
4606 new_mask = 1 << new_bit;
4607
4608 /*
4609 * If already set then do not dirty the cacheline,
4610 * nor do any checks:
4611 */
4612 if (likely(hlock_class(this)->usage_mask & new_mask))
4613 return 1;
4614
4615 if (!graph_lock())
4616 return 0;
4617 /*
4618 * Make sure we didn't race:
4619 */
4620 if (unlikely(hlock_class(this)->usage_mask & new_mask))
4621 goto unlock;
4622
4623 if (!hlock_class(this)->usage_mask)
4624 debug_atomic_dec(nr_unused_locks);
4625
4626 hlock_class(this)->usage_mask |= new_mask;
4627
4628 if (new_bit < LOCK_TRACE_STATES) {
4629 if (!(hlock_class(this)->usage_traces[new_bit] = save_trace()))
4630 return 0;
4631 }
4632
4633 if (new_bit < LOCK_USED) {
4634 ret = mark_lock_irq(curr, this, new_bit);
4635 if (!ret)
4636 return 0;
4637 }
4638
4639unlock:
4640 graph_unlock();
4641
4642 /*
4643 * We must printk outside of the graph_lock:
4644 */
4645 if (ret == 2) {
4646 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
4647 print_lock(this);
4648 print_irqtrace_events(curr);
4649 dump_stack();
4650 }
4651
4652 return ret;
4653}
4654
4655static inline short task_wait_context(struct task_struct *curr)
4656{
4657 /*
4658 * Set appropriate wait type for the context; for IRQs we have to take
4659 * into account force_irqthread as that is implied by PREEMPT_RT.
4660 */
4661 if (lockdep_hardirq_context()) {
4662 /*
4663 * Check if force_irqthreads will run us threaded.
4664 */
4665 if (curr->hardirq_threaded || curr->irq_config)
4666 return LD_WAIT_CONFIG;
4667
4668 return LD_WAIT_SPIN;
4669 } else if (curr->softirq_context) {
4670 /*
4671 * Softirqs are always threaded.
4672 */
4673 return LD_WAIT_CONFIG;
4674 }
4675
4676 return LD_WAIT_MAX;
4677}
4678
4679static int
4680print_lock_invalid_wait_context(struct task_struct *curr,
4681 struct held_lock *hlock)
4682{
4683 short curr_inner;
4684
4685 if (!debug_locks_off())
4686 return 0;
4687 if (debug_locks_silent)
4688 return 0;
4689
4690 pr_warn("\n");
4691 pr_warn("=============================\n");
4692 pr_warn("[ BUG: Invalid wait context ]\n");
4693 print_kernel_ident();
4694 pr_warn("-----------------------------\n");
4695
4696 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
4697 print_lock(hlock);
4698
4699 pr_warn("other info that might help us debug this:\n");
4700
4701 curr_inner = task_wait_context(curr);
4702 pr_warn("context-{%d:%d}\n", curr_inner, curr_inner);
4703
4704 lockdep_print_held_locks(curr);
4705
4706 pr_warn("stack backtrace:\n");
4707 dump_stack();
4708
4709 return 0;
4710}
4711
4712/*
4713 * Verify the wait_type context.
4714 *
4715 * This check validates we take locks in the right wait-type order; that is it
4716 * ensures that we do not take mutexes inside spinlocks and do not attempt to
4717 * acquire spinlocks inside raw_spinlocks and the sort.
4718 *
4719 * The entire thing is slightly more complex because of RCU, RCU is a lock that
4720 * can be taken from (pretty much) any context but also has constraints.
4721 * However when taken in a stricter environment the RCU lock does not loosen
4722 * the constraints.
4723 *
4724 * Therefore we must look for the strictest environment in the lock stack and
4725 * compare that to the lock we're trying to acquire.
4726 */
4727static int check_wait_context(struct task_struct *curr, struct held_lock *next)
4728{
4729 u8 next_inner = hlock_class(next)->wait_type_inner;
4730 u8 next_outer = hlock_class(next)->wait_type_outer;
4731 u8 curr_inner;
4732 int depth;
4733
4734 if (!next_inner || next->trylock)
4735 return 0;
4736
4737 if (!next_outer)
4738 next_outer = next_inner;
4739
4740 /*
4741 * Find start of current irq_context..
4742 */
4743 for (depth = curr->lockdep_depth - 1; depth >= 0; depth--) {
4744 struct held_lock *prev = curr->held_locks + depth;
4745 if (prev->irq_context != next->irq_context)
4746 break;
4747 }
4748 depth++;
4749
4750 curr_inner = task_wait_context(curr);
4751
4752 for (; depth < curr->lockdep_depth; depth++) {
4753 struct held_lock *prev = curr->held_locks + depth;
4754 u8 prev_inner = hlock_class(prev)->wait_type_inner;
4755
4756 if (prev_inner) {
4757 /*
4758 * We can have a bigger inner than a previous one
4759 * when outer is smaller than inner, as with RCU.
4760 *
4761 * Also due to trylocks.
4762 */
4763 curr_inner = min(curr_inner, prev_inner);
4764 }
4765 }
4766
4767 if (next_outer > curr_inner)
4768 return print_lock_invalid_wait_context(curr, next);
4769
4770 return 0;
4771}
4772
4773#else /* CONFIG_PROVE_LOCKING */
4774
4775static inline int
4776mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
4777{
4778 return 1;
4779}
4780
4781static inline unsigned int task_irq_context(struct task_struct *task)
4782{
4783 return 0;
4784}
4785
4786static inline int separate_irq_context(struct task_struct *curr,
4787 struct held_lock *hlock)
4788{
4789 return 0;
4790}
4791
4792static inline int check_wait_context(struct task_struct *curr,
4793 struct held_lock *next)
4794{
4795 return 0;
4796}
4797
4798#endif /* CONFIG_PROVE_LOCKING */
4799
4800/*
4801 * Initialize a lock instance's lock-class mapping info:
4802 */
4803void lockdep_init_map_type(struct lockdep_map *lock, const char *name,
4804 struct lock_class_key *key, int subclass,
4805 u8 inner, u8 outer, u8 lock_type)
4806{
4807 int i;
4808
4809 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
4810 lock->class_cache[i] = NULL;
4811
4812#ifdef CONFIG_LOCK_STAT
4813 lock->cpu = raw_smp_processor_id();
4814#endif
4815
4816 /*
4817 * Can't be having no nameless bastards around this place!
4818 */
4819 if (DEBUG_LOCKS_WARN_ON(!name)) {
4820 lock->name = "NULL";
4821 return;
4822 }
4823
4824 lock->name = name;
4825
4826 lock->wait_type_outer = outer;
4827 lock->wait_type_inner = inner;
4828 lock->lock_type = lock_type;
4829
4830 /*
4831 * No key, no joy, we need to hash something.
4832 */
4833 if (DEBUG_LOCKS_WARN_ON(!key))
4834 return;
4835 /*
4836 * Sanity check, the lock-class key must either have been allocated
4837 * statically or must have been registered as a dynamic key.
4838 */
4839 if (!static_obj(key) && !is_dynamic_key(key)) {
4840 if (debug_locks)
4841 printk(KERN_ERR "BUG: key %px has not been registered!\n", key);
4842 DEBUG_LOCKS_WARN_ON(1);
4843 return;
4844 }
4845 lock->key = key;
4846
4847 if (unlikely(!debug_locks))
4848 return;
4849
4850 if (subclass) {
4851 unsigned long flags;
4852
4853 if (DEBUG_LOCKS_WARN_ON(!lockdep_enabled()))
4854 return;
4855
4856 raw_local_irq_save(flags);
4857 lockdep_recursion_inc();
4858 register_lock_class(lock, subclass, 1);
4859 lockdep_recursion_finish();
4860 raw_local_irq_restore(flags);
4861 }
4862}
4863EXPORT_SYMBOL_GPL(lockdep_init_map_type);
4864
4865struct lock_class_key __lockdep_no_validate__;
4866EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
4867
4868static void
4869print_lock_nested_lock_not_held(struct task_struct *curr,
4870 struct held_lock *hlock)
4871{
4872 if (!debug_locks_off())
4873 return;
4874 if (debug_locks_silent)
4875 return;
4876
4877 pr_warn("\n");
4878 pr_warn("==================================\n");
4879 pr_warn("WARNING: Nested lock was not taken\n");
4880 print_kernel_ident();
4881 pr_warn("----------------------------------\n");
4882
4883 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
4884 print_lock(hlock);
4885
4886 pr_warn("\nbut this task is not holding:\n");
4887 pr_warn("%s\n", hlock->nest_lock->name);
4888
4889 pr_warn("\nstack backtrace:\n");
4890 dump_stack();
4891
4892 pr_warn("\nother info that might help us debug this:\n");
4893 lockdep_print_held_locks(curr);
4894
4895 pr_warn("\nstack backtrace:\n");
4896 dump_stack();
4897}
4898
4899static int __lock_is_held(const struct lockdep_map *lock, int read);
4900
4901/*
4902 * This gets called for every mutex_lock*()/spin_lock*() operation.
4903 * We maintain the dependency maps and validate the locking attempt:
4904 *
4905 * The callers must make sure that IRQs are disabled before calling it,
4906 * otherwise we could get an interrupt which would want to take locks,
4907 * which would end up in lockdep again.
4908 */
4909static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
4910 int trylock, int read, int check, int hardirqs_off,
4911 struct lockdep_map *nest_lock, unsigned long ip,
4912 int references, int pin_count)
4913{
4914 struct task_struct *curr = current;
4915 struct lock_class *class = NULL;
4916 struct held_lock *hlock;
4917 unsigned int depth;
4918 int chain_head = 0;
4919 int class_idx;
4920 u64 chain_key;
4921
4922 if (unlikely(!debug_locks))
4923 return 0;
4924
4925 if (!prove_locking || lock->key == &__lockdep_no_validate__)
4926 check = 0;
4927
4928 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
4929 class = lock->class_cache[subclass];
4930 /*
4931 * Not cached?
4932 */
4933 if (unlikely(!class)) {
4934 class = register_lock_class(lock, subclass, 0);
4935 if (!class)
4936 return 0;
4937 }
4938
4939 debug_class_ops_inc(class);
4940
4941 if (very_verbose(class)) {
4942 printk("\nacquire class [%px] %s", class->key, class->name);
4943 if (class->name_version > 1)
4944 printk(KERN_CONT "#%d", class->name_version);
4945 printk(KERN_CONT "\n");
4946 dump_stack();
4947 }
4948
4949 /*
4950 * Add the lock to the list of currently held locks.
4951 * (we dont increase the depth just yet, up until the
4952 * dependency checks are done)
4953 */
4954 depth = curr->lockdep_depth;
4955 /*
4956 * Ran out of static storage for our per-task lock stack again have we?
4957 */
4958 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
4959 return 0;
4960
4961 class_idx = class - lock_classes;
4962
4963 if (depth) { /* we're holding locks */
4964 hlock = curr->held_locks + depth - 1;
4965 if (hlock->class_idx == class_idx && nest_lock) {
4966 if (!references)
4967 references++;
4968
4969 if (!hlock->references)
4970 hlock->references++;
4971
4972 hlock->references += references;
4973
4974 /* Overflow */
4975 if (DEBUG_LOCKS_WARN_ON(hlock->references < references))
4976 return 0;
4977
4978 return 2;
4979 }
4980 }
4981
4982 hlock = curr->held_locks + depth;
4983 /*
4984 * Plain impossible, we just registered it and checked it weren't no
4985 * NULL like.. I bet this mushroom I ate was good!
4986 */
4987 if (DEBUG_LOCKS_WARN_ON(!class))
4988 return 0;
4989 hlock->class_idx = class_idx;
4990 hlock->acquire_ip = ip;
4991 hlock->instance = lock;
4992 hlock->nest_lock = nest_lock;
4993 hlock->irq_context = task_irq_context(curr);
4994 hlock->trylock = trylock;
4995 hlock->read = read;
4996 hlock->check = check;
4997 hlock->hardirqs_off = !!hardirqs_off;
4998 hlock->references = references;
4999#ifdef CONFIG_LOCK_STAT
5000 hlock->waittime_stamp = 0;
5001 hlock->holdtime_stamp = lockstat_clock();
5002#endif
5003 hlock->pin_count = pin_count;
5004
5005 if (check_wait_context(curr, hlock))
5006 return 0;
5007
5008 /* Initialize the lock usage bit */
5009 if (!mark_usage(curr, hlock, check))
5010 return 0;
5011
5012 /*
5013 * Calculate the chain hash: it's the combined hash of all the
5014 * lock keys along the dependency chain. We save the hash value
5015 * at every step so that we can get the current hash easily
5016 * after unlock. The chain hash is then used to cache dependency
5017 * results.
5018 *
5019 * The 'key ID' is what is the most compact key value to drive
5020 * the hash, not class->key.
5021 */
5022 /*
5023 * Whoops, we did it again.. class_idx is invalid.
5024 */
5025 if (DEBUG_LOCKS_WARN_ON(!test_bit(class_idx, lock_classes_in_use)))
5026 return 0;
5027
5028 chain_key = curr->curr_chain_key;
5029 if (!depth) {
5030 /*
5031 * How can we have a chain hash when we ain't got no keys?!
5032 */
5033 if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY))
5034 return 0;
5035 chain_head = 1;
5036 }
5037
5038 hlock->prev_chain_key = chain_key;
5039 if (separate_irq_context(curr, hlock)) {
5040 chain_key = INITIAL_CHAIN_KEY;
5041 chain_head = 1;
5042 }
5043 chain_key = iterate_chain_key(chain_key, hlock_id(hlock));
5044
5045 if (nest_lock && !__lock_is_held(nest_lock, -1)) {
5046 print_lock_nested_lock_not_held(curr, hlock);
5047 return 0;
5048 }
5049
5050 if (!debug_locks_silent) {
5051 WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key);
5052 WARN_ON_ONCE(!hlock_class(hlock)->key);
5053 }
5054
5055 if (!validate_chain(curr, hlock, chain_head, chain_key))
5056 return 0;
5057
5058 curr->curr_chain_key = chain_key;
5059 curr->lockdep_depth++;
5060 check_chain_key(curr);
5061#ifdef CONFIG_DEBUG_LOCKDEP
5062 if (unlikely(!debug_locks))
5063 return 0;
5064#endif
5065 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
5066 debug_locks_off();
5067 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
5068 printk(KERN_DEBUG "depth: %i max: %lu!\n",
5069 curr->lockdep_depth, MAX_LOCK_DEPTH);
5070
5071 lockdep_print_held_locks(current);
5072 debug_show_all_locks();
5073 dump_stack();
5074
5075 return 0;
5076 }
5077
5078 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
5079 max_lockdep_depth = curr->lockdep_depth;
5080
5081 return 1;
5082}
5083
5084static void print_unlock_imbalance_bug(struct task_struct *curr,
5085 struct lockdep_map *lock,
5086 unsigned long ip)
5087{
5088 if (!debug_locks_off())
5089 return;
5090 if (debug_locks_silent)
5091 return;
5092
5093 pr_warn("\n");
5094 pr_warn("=====================================\n");
5095 pr_warn("WARNING: bad unlock balance detected!\n");
5096 print_kernel_ident();
5097 pr_warn("-------------------------------------\n");
5098 pr_warn("%s/%d is trying to release lock (",
5099 curr->comm, task_pid_nr(curr));
5100 print_lockdep_cache(lock);
5101 pr_cont(") at:\n");
5102 print_ip_sym(KERN_WARNING, ip);
5103 pr_warn("but there are no more locks to release!\n");
5104 pr_warn("\nother info that might help us debug this:\n");
5105 lockdep_print_held_locks(curr);
5106
5107 pr_warn("\nstack backtrace:\n");
5108 dump_stack();
5109}
5110
5111static noinstr int match_held_lock(const struct held_lock *hlock,
5112 const struct lockdep_map *lock)
5113{
5114 if (hlock->instance == lock)
5115 return 1;
5116
5117 if (hlock->references) {
5118 const struct lock_class *class = lock->class_cache[0];
5119
5120 if (!class)
5121 class = look_up_lock_class(lock, 0);
5122
5123 /*
5124 * If look_up_lock_class() failed to find a class, we're trying
5125 * to test if we hold a lock that has never yet been acquired.
5126 * Clearly if the lock hasn't been acquired _ever_, we're not
5127 * holding it either, so report failure.
5128 */
5129 if (!class)
5130 return 0;
5131
5132 /*
5133 * References, but not a lock we're actually ref-counting?
5134 * State got messed up, follow the sites that change ->references
5135 * and try to make sense of it.
5136 */
5137 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
5138 return 0;
5139
5140 if (hlock->class_idx == class - lock_classes)
5141 return 1;
5142 }
5143
5144 return 0;
5145}
5146
5147/* @depth must not be zero */
5148static struct held_lock *find_held_lock(struct task_struct *curr,
5149 struct lockdep_map *lock,
5150 unsigned int depth, int *idx)
5151{
5152 struct held_lock *ret, *hlock, *prev_hlock;
5153 int i;
5154
5155 i = depth - 1;
5156 hlock = curr->held_locks + i;
5157 ret = hlock;
5158 if (match_held_lock(hlock, lock))
5159 goto out;
5160
5161 ret = NULL;
5162 for (i--, prev_hlock = hlock--;
5163 i >= 0;
5164 i--, prev_hlock = hlock--) {
5165 /*
5166 * We must not cross into another context:
5167 */
5168 if (prev_hlock->irq_context != hlock->irq_context) {
5169 ret = NULL;
5170 break;
5171 }
5172 if (match_held_lock(hlock, lock)) {
5173 ret = hlock;
5174 break;
5175 }
5176 }
5177
5178out:
5179 *idx = i;
5180 return ret;
5181}
5182
5183static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
5184 int idx, unsigned int *merged)
5185{
5186 struct held_lock *hlock;
5187 int first_idx = idx;
5188
5189 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
5190 return 0;
5191
5192 for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
5193 switch (__lock_acquire(hlock->instance,
5194 hlock_class(hlock)->subclass,
5195 hlock->trylock,
5196 hlock->read, hlock->check,
5197 hlock->hardirqs_off,
5198 hlock->nest_lock, hlock->acquire_ip,
5199 hlock->references, hlock->pin_count)) {
5200 case 0:
5201 return 1;
5202 case 1:
5203 break;
5204 case 2:
5205 *merged += (idx == first_idx);
5206 break;
5207 default:
5208 WARN_ON(1);
5209 return 0;
5210 }
5211 }
5212 return 0;
5213}
5214
5215static int
5216__lock_set_class(struct lockdep_map *lock, const char *name,
5217 struct lock_class_key *key, unsigned int subclass,
5218 unsigned long ip)
5219{
5220 struct task_struct *curr = current;
5221 unsigned int depth, merged = 0;
5222 struct held_lock *hlock;
5223 struct lock_class *class;
5224 int i;
5225
5226 if (unlikely(!debug_locks))
5227 return 0;
5228
5229 depth = curr->lockdep_depth;
5230 /*
5231 * This function is about (re)setting the class of a held lock,
5232 * yet we're not actually holding any locks. Naughty user!
5233 */
5234 if (DEBUG_LOCKS_WARN_ON(!depth))
5235 return 0;
5236
5237 hlock = find_held_lock(curr, lock, depth, &i);
5238 if (!hlock) {
5239 print_unlock_imbalance_bug(curr, lock, ip);
5240 return 0;
5241 }
5242
5243 lockdep_init_map_type(lock, name, key, 0,
5244 lock->wait_type_inner,
5245 lock->wait_type_outer,
5246 lock->lock_type);
5247 class = register_lock_class(lock, subclass, 0);
5248 hlock->class_idx = class - lock_classes;
5249
5250 curr->lockdep_depth = i;
5251 curr->curr_chain_key = hlock->prev_chain_key;
5252
5253 if (reacquire_held_locks(curr, depth, i, &merged))
5254 return 0;
5255
5256 /*
5257 * I took it apart and put it back together again, except now I have
5258 * these 'spare' parts.. where shall I put them.
5259 */
5260 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged))
5261 return 0;
5262 return 1;
5263}
5264
5265static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
5266{
5267 struct task_struct *curr = current;
5268 unsigned int depth, merged = 0;
5269 struct held_lock *hlock;
5270 int i;
5271
5272 if (unlikely(!debug_locks))
5273 return 0;
5274
5275 depth = curr->lockdep_depth;
5276 /*
5277 * This function is about (re)setting the class of a held lock,
5278 * yet we're not actually holding any locks. Naughty user!
5279 */
5280 if (DEBUG_LOCKS_WARN_ON(!depth))
5281 return 0;
5282
5283 hlock = find_held_lock(curr, lock, depth, &i);
5284 if (!hlock) {
5285 print_unlock_imbalance_bug(curr, lock, ip);
5286 return 0;
5287 }
5288
5289 curr->lockdep_depth = i;
5290 curr->curr_chain_key = hlock->prev_chain_key;
5291
5292 WARN(hlock->read, "downgrading a read lock");
5293 hlock->read = 1;
5294 hlock->acquire_ip = ip;
5295
5296 if (reacquire_held_locks(curr, depth, i, &merged))
5297 return 0;
5298
5299 /* Merging can't happen with unchanged classes.. */
5300 if (DEBUG_LOCKS_WARN_ON(merged))
5301 return 0;
5302
5303 /*
5304 * I took it apart and put it back together again, except now I have
5305 * these 'spare' parts.. where shall I put them.
5306 */
5307 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
5308 return 0;
5309
5310 return 1;
5311}
5312
5313/*
5314 * Remove the lock from the list of currently held locks - this gets
5315 * called on mutex_unlock()/spin_unlock*() (or on a failed
5316 * mutex_lock_interruptible()).
5317 */
5318static int
5319__lock_release(struct lockdep_map *lock, unsigned long ip)
5320{
5321 struct task_struct *curr = current;
5322 unsigned int depth, merged = 1;
5323 struct held_lock *hlock;
5324 int i;
5325
5326 if (unlikely(!debug_locks))
5327 return 0;
5328
5329 depth = curr->lockdep_depth;
5330 /*
5331 * So we're all set to release this lock.. wait what lock? We don't
5332 * own any locks, you've been drinking again?
5333 */
5334 if (depth <= 0) {
5335 print_unlock_imbalance_bug(curr, lock, ip);
5336 return 0;
5337 }
5338
5339 /*
5340 * Check whether the lock exists in the current stack
5341 * of held locks:
5342 */
5343 hlock = find_held_lock(curr, lock, depth, &i);
5344 if (!hlock) {
5345 print_unlock_imbalance_bug(curr, lock, ip);
5346 return 0;
5347 }
5348
5349 if (hlock->instance == lock)
5350 lock_release_holdtime(hlock);
5351
5352 WARN(hlock->pin_count, "releasing a pinned lock\n");
5353
5354 if (hlock->references) {
5355 hlock->references--;
5356 if (hlock->references) {
5357 /*
5358 * We had, and after removing one, still have
5359 * references, the current lock stack is still
5360 * valid. We're done!
5361 */
5362 return 1;
5363 }
5364 }
5365
5366 /*
5367 * We have the right lock to unlock, 'hlock' points to it.
5368 * Now we remove it from the stack, and add back the other
5369 * entries (if any), recalculating the hash along the way:
5370 */
5371
5372 curr->lockdep_depth = i;
5373 curr->curr_chain_key = hlock->prev_chain_key;
5374
5375 /*
5376 * The most likely case is when the unlock is on the innermost
5377 * lock. In this case, we are done!
5378 */
5379 if (i == depth-1)
5380 return 1;
5381
5382 if (reacquire_held_locks(curr, depth, i + 1, &merged))
5383 return 0;
5384
5385 /*
5386 * We had N bottles of beer on the wall, we drank one, but now
5387 * there's not N-1 bottles of beer left on the wall...
5388 * Pouring two of the bottles together is acceptable.
5389 */
5390 DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged);
5391
5392 /*
5393 * Since reacquire_held_locks() would have called check_chain_key()
5394 * indirectly via __lock_acquire(), we don't need to do it again
5395 * on return.
5396 */
5397 return 0;
5398}
5399
5400static __always_inline
5401int __lock_is_held(const struct lockdep_map *lock, int read)
5402{
5403 struct task_struct *curr = current;
5404 int i;
5405
5406 for (i = 0; i < curr->lockdep_depth; i++) {
5407 struct held_lock *hlock = curr->held_locks + i;
5408
5409 if (match_held_lock(hlock, lock)) {
5410 if (read == -1 || !!hlock->read == read)
5411 return LOCK_STATE_HELD;
5412
5413 return LOCK_STATE_NOT_HELD;
5414 }
5415 }
5416
5417 return LOCK_STATE_NOT_HELD;
5418}
5419
5420static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
5421{
5422 struct pin_cookie cookie = NIL_COOKIE;
5423 struct task_struct *curr = current;
5424 int i;
5425
5426 if (unlikely(!debug_locks))
5427 return cookie;
5428
5429 for (i = 0; i < curr->lockdep_depth; i++) {
5430 struct held_lock *hlock = curr->held_locks + i;
5431
5432 if (match_held_lock(hlock, lock)) {
5433 /*
5434 * Grab 16bits of randomness; this is sufficient to not
5435 * be guessable and still allows some pin nesting in
5436 * our u32 pin_count.
5437 */
5438 cookie.val = 1 + (sched_clock() & 0xffff);
5439 hlock->pin_count += cookie.val;
5440 return cookie;
5441 }
5442 }
5443
5444 WARN(1, "pinning an unheld lock\n");
5445 return cookie;
5446}
5447
5448static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5449{
5450 struct task_struct *curr = current;
5451 int i;
5452
5453 if (unlikely(!debug_locks))
5454 return;
5455
5456 for (i = 0; i < curr->lockdep_depth; i++) {
5457 struct held_lock *hlock = curr->held_locks + i;
5458
5459 if (match_held_lock(hlock, lock)) {
5460 hlock->pin_count += cookie.val;
5461 return;
5462 }
5463 }
5464
5465 WARN(1, "pinning an unheld lock\n");
5466}
5467
5468static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5469{
5470 struct task_struct *curr = current;
5471 int i;
5472
5473 if (unlikely(!debug_locks))
5474 return;
5475
5476 for (i = 0; i < curr->lockdep_depth; i++) {
5477 struct held_lock *hlock = curr->held_locks + i;
5478
5479 if (match_held_lock(hlock, lock)) {
5480 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
5481 return;
5482
5483 hlock->pin_count -= cookie.val;
5484
5485 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
5486 hlock->pin_count = 0;
5487
5488 return;
5489 }
5490 }
5491
5492 WARN(1, "unpinning an unheld lock\n");
5493}
5494
5495/*
5496 * Check whether we follow the irq-flags state precisely:
5497 */
5498static noinstr void check_flags(unsigned long flags)
5499{
5500#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP)
5501 if (!debug_locks)
5502 return;
5503
5504 /* Get the warning out.. */
5505 instrumentation_begin();
5506
5507 if (irqs_disabled_flags(flags)) {
5508 if (DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())) {
5509 printk("possible reason: unannotated irqs-off.\n");
5510 }
5511 } else {
5512 if (DEBUG_LOCKS_WARN_ON(!lockdep_hardirqs_enabled())) {
5513 printk("possible reason: unannotated irqs-on.\n");
5514 }
5515 }
5516
5517#ifndef CONFIG_PREEMPT_RT
5518 /*
5519 * We dont accurately track softirq state in e.g.
5520 * hardirq contexts (such as on 4KSTACKS), so only
5521 * check if not in hardirq contexts:
5522 */
5523 if (!hardirq_count()) {
5524 if (softirq_count()) {
5525 /* like the above, but with softirqs */
5526 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
5527 } else {
5528 /* lick the above, does it taste good? */
5529 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
5530 }
5531 }
5532#endif
5533
5534 if (!debug_locks)
5535 print_irqtrace_events(current);
5536
5537 instrumentation_end();
5538#endif
5539}
5540
5541void lock_set_class(struct lockdep_map *lock, const char *name,
5542 struct lock_class_key *key, unsigned int subclass,
5543 unsigned long ip)
5544{
5545 unsigned long flags;
5546
5547 if (unlikely(!lockdep_enabled()))
5548 return;
5549
5550 raw_local_irq_save(flags);
5551 lockdep_recursion_inc();
5552 check_flags(flags);
5553 if (__lock_set_class(lock, name, key, subclass, ip))
5554 check_chain_key(current);
5555 lockdep_recursion_finish();
5556 raw_local_irq_restore(flags);
5557}
5558EXPORT_SYMBOL_GPL(lock_set_class);
5559
5560void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
5561{
5562 unsigned long flags;
5563
5564 if (unlikely(!lockdep_enabled()))
5565 return;
5566
5567 raw_local_irq_save(flags);
5568 lockdep_recursion_inc();
5569 check_flags(flags);
5570 if (__lock_downgrade(lock, ip))
5571 check_chain_key(current);
5572 lockdep_recursion_finish();
5573 raw_local_irq_restore(flags);
5574}
5575EXPORT_SYMBOL_GPL(lock_downgrade);
5576
5577/* NMI context !!! */
5578static void verify_lock_unused(struct lockdep_map *lock, struct held_lock *hlock, int subclass)
5579{
5580#ifdef CONFIG_PROVE_LOCKING
5581 struct lock_class *class = look_up_lock_class(lock, subclass);
5582 unsigned long mask = LOCKF_USED;
5583
5584 /* if it doesn't have a class (yet), it certainly hasn't been used yet */
5585 if (!class)
5586 return;
5587
5588 /*
5589 * READ locks only conflict with USED, such that if we only ever use
5590 * READ locks, there is no deadlock possible -- RCU.
5591 */
5592 if (!hlock->read)
5593 mask |= LOCKF_USED_READ;
5594
5595 if (!(class->usage_mask & mask))
5596 return;
5597
5598 hlock->class_idx = class - lock_classes;
5599
5600 print_usage_bug(current, hlock, LOCK_USED, LOCK_USAGE_STATES);
5601#endif
5602}
5603
5604static bool lockdep_nmi(void)
5605{
5606 if (raw_cpu_read(lockdep_recursion))
5607 return false;
5608
5609 if (!in_nmi())
5610 return false;
5611
5612 return true;
5613}
5614
5615/*
5616 * read_lock() is recursive if:
5617 * 1. We force lockdep think this way in selftests or
5618 * 2. The implementation is not queued read/write lock or
5619 * 3. The locker is at an in_interrupt() context.
5620 */
5621bool read_lock_is_recursive(void)
5622{
5623 return force_read_lock_recursive ||
5624 !IS_ENABLED(CONFIG_QUEUED_RWLOCKS) ||
5625 in_interrupt();
5626}
5627EXPORT_SYMBOL_GPL(read_lock_is_recursive);
5628
5629/*
5630 * We are not always called with irqs disabled - do that here,
5631 * and also avoid lockdep recursion:
5632 */
5633void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
5634 int trylock, int read, int check,
5635 struct lockdep_map *nest_lock, unsigned long ip)
5636{
5637 unsigned long flags;
5638
5639 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
5640
5641 if (!debug_locks)
5642 return;
5643
5644 if (unlikely(!lockdep_enabled())) {
5645 /* XXX allow trylock from NMI ?!? */
5646 if (lockdep_nmi() && !trylock) {
5647 struct held_lock hlock;
5648
5649 hlock.acquire_ip = ip;
5650 hlock.instance = lock;
5651 hlock.nest_lock = nest_lock;
5652 hlock.irq_context = 2; // XXX
5653 hlock.trylock = trylock;
5654 hlock.read = read;
5655 hlock.check = check;
5656 hlock.hardirqs_off = true;
5657 hlock.references = 0;
5658
5659 verify_lock_unused(lock, &hlock, subclass);
5660 }
5661 return;
5662 }
5663
5664 raw_local_irq_save(flags);
5665 check_flags(flags);
5666
5667 lockdep_recursion_inc();
5668 __lock_acquire(lock, subclass, trylock, read, check,
5669 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
5670 lockdep_recursion_finish();
5671 raw_local_irq_restore(flags);
5672}
5673EXPORT_SYMBOL_GPL(lock_acquire);
5674
5675void lock_release(struct lockdep_map *lock, unsigned long ip)
5676{
5677 unsigned long flags;
5678
5679 trace_lock_release(lock, ip);
5680
5681 if (unlikely(!lockdep_enabled()))
5682 return;
5683
5684 raw_local_irq_save(flags);
5685 check_flags(flags);
5686
5687 lockdep_recursion_inc();
5688 if (__lock_release(lock, ip))
5689 check_chain_key(current);
5690 lockdep_recursion_finish();
5691 raw_local_irq_restore(flags);
5692}
5693EXPORT_SYMBOL_GPL(lock_release);
5694
5695noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
5696{
5697 unsigned long flags;
5698 int ret = LOCK_STATE_NOT_HELD;
5699
5700 /*
5701 * Avoid false negative lockdep_assert_held() and
5702 * lockdep_assert_not_held().
5703 */
5704 if (unlikely(!lockdep_enabled()))
5705 return LOCK_STATE_UNKNOWN;
5706
5707 raw_local_irq_save(flags);
5708 check_flags(flags);
5709
5710 lockdep_recursion_inc();
5711 ret = __lock_is_held(lock, read);
5712 lockdep_recursion_finish();
5713 raw_local_irq_restore(flags);
5714
5715 return ret;
5716}
5717EXPORT_SYMBOL_GPL(lock_is_held_type);
5718NOKPROBE_SYMBOL(lock_is_held_type);
5719
5720struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
5721{
5722 struct pin_cookie cookie = NIL_COOKIE;
5723 unsigned long flags;
5724
5725 if (unlikely(!lockdep_enabled()))
5726 return cookie;
5727
5728 raw_local_irq_save(flags);
5729 check_flags(flags);
5730
5731 lockdep_recursion_inc();
5732 cookie = __lock_pin_lock(lock);
5733 lockdep_recursion_finish();
5734 raw_local_irq_restore(flags);
5735
5736 return cookie;
5737}
5738EXPORT_SYMBOL_GPL(lock_pin_lock);
5739
5740void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5741{
5742 unsigned long flags;
5743
5744 if (unlikely(!lockdep_enabled()))
5745 return;
5746
5747 raw_local_irq_save(flags);
5748 check_flags(flags);
5749
5750 lockdep_recursion_inc();
5751 __lock_repin_lock(lock, cookie);
5752 lockdep_recursion_finish();
5753 raw_local_irq_restore(flags);
5754}
5755EXPORT_SYMBOL_GPL(lock_repin_lock);
5756
5757void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5758{
5759 unsigned long flags;
5760
5761 if (unlikely(!lockdep_enabled()))
5762 return;
5763
5764 raw_local_irq_save(flags);
5765 check_flags(flags);
5766
5767 lockdep_recursion_inc();
5768 __lock_unpin_lock(lock, cookie);
5769 lockdep_recursion_finish();
5770 raw_local_irq_restore(flags);
5771}
5772EXPORT_SYMBOL_GPL(lock_unpin_lock);
5773
5774#ifdef CONFIG_LOCK_STAT
5775static void print_lock_contention_bug(struct task_struct *curr,
5776 struct lockdep_map *lock,
5777 unsigned long ip)
5778{
5779 if (!debug_locks_off())
5780 return;
5781 if (debug_locks_silent)
5782 return;
5783
5784 pr_warn("\n");
5785 pr_warn("=================================\n");
5786 pr_warn("WARNING: bad contention detected!\n");
5787 print_kernel_ident();
5788 pr_warn("---------------------------------\n");
5789 pr_warn("%s/%d is trying to contend lock (",
5790 curr->comm, task_pid_nr(curr));
5791 print_lockdep_cache(lock);
5792 pr_cont(") at:\n");
5793 print_ip_sym(KERN_WARNING, ip);
5794 pr_warn("but there are no locks held!\n");
5795 pr_warn("\nother info that might help us debug this:\n");
5796 lockdep_print_held_locks(curr);
5797
5798 pr_warn("\nstack backtrace:\n");
5799 dump_stack();
5800}
5801
5802static void
5803__lock_contended(struct lockdep_map *lock, unsigned long ip)
5804{
5805 struct task_struct *curr = current;
5806 struct held_lock *hlock;
5807 struct lock_class_stats *stats;
5808 unsigned int depth;
5809 int i, contention_point, contending_point;
5810
5811 depth = curr->lockdep_depth;
5812 /*
5813 * Whee, we contended on this lock, except it seems we're not
5814 * actually trying to acquire anything much at all..
5815 */
5816 if (DEBUG_LOCKS_WARN_ON(!depth))
5817 return;
5818
5819 hlock = find_held_lock(curr, lock, depth, &i);
5820 if (!hlock) {
5821 print_lock_contention_bug(curr, lock, ip);
5822 return;
5823 }
5824
5825 if (hlock->instance != lock)
5826 return;
5827
5828 hlock->waittime_stamp = lockstat_clock();
5829
5830 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
5831 contending_point = lock_point(hlock_class(hlock)->contending_point,
5832 lock->ip);
5833
5834 stats = get_lock_stats(hlock_class(hlock));
5835 if (contention_point < LOCKSTAT_POINTS)
5836 stats->contention_point[contention_point]++;
5837 if (contending_point < LOCKSTAT_POINTS)
5838 stats->contending_point[contending_point]++;
5839 if (lock->cpu != smp_processor_id())
5840 stats->bounces[bounce_contended + !!hlock->read]++;
5841}
5842
5843static void
5844__lock_acquired(struct lockdep_map *lock, unsigned long ip)
5845{
5846 struct task_struct *curr = current;
5847 struct held_lock *hlock;
5848 struct lock_class_stats *stats;
5849 unsigned int depth;
5850 u64 now, waittime = 0;
5851 int i, cpu;
5852
5853 depth = curr->lockdep_depth;
5854 /*
5855 * Yay, we acquired ownership of this lock we didn't try to
5856 * acquire, how the heck did that happen?
5857 */
5858 if (DEBUG_LOCKS_WARN_ON(!depth))
5859 return;
5860
5861 hlock = find_held_lock(curr, lock, depth, &i);
5862 if (!hlock) {
5863 print_lock_contention_bug(curr, lock, _RET_IP_);
5864 return;
5865 }
5866
5867 if (hlock->instance != lock)
5868 return;
5869
5870 cpu = smp_processor_id();
5871 if (hlock->waittime_stamp) {
5872 now = lockstat_clock();
5873 waittime = now - hlock->waittime_stamp;
5874 hlock->holdtime_stamp = now;
5875 }
5876
5877 stats = get_lock_stats(hlock_class(hlock));
5878 if (waittime) {
5879 if (hlock->read)
5880 lock_time_inc(&stats->read_waittime, waittime);
5881 else
5882 lock_time_inc(&stats->write_waittime, waittime);
5883 }
5884 if (lock->cpu != cpu)
5885 stats->bounces[bounce_acquired + !!hlock->read]++;
5886
5887 lock->cpu = cpu;
5888 lock->ip = ip;
5889}
5890
5891void lock_contended(struct lockdep_map *lock, unsigned long ip)
5892{
5893 unsigned long flags;
5894
5895 trace_lock_contended(lock, ip);
5896
5897 if (unlikely(!lock_stat || !lockdep_enabled()))
5898 return;
5899
5900 raw_local_irq_save(flags);
5901 check_flags(flags);
5902 lockdep_recursion_inc();
5903 __lock_contended(lock, ip);
5904 lockdep_recursion_finish();
5905 raw_local_irq_restore(flags);
5906}
5907EXPORT_SYMBOL_GPL(lock_contended);
5908
5909void lock_acquired(struct lockdep_map *lock, unsigned long ip)
5910{
5911 unsigned long flags;
5912
5913 trace_lock_acquired(lock, ip);
5914
5915 if (unlikely(!lock_stat || !lockdep_enabled()))
5916 return;
5917
5918 raw_local_irq_save(flags);
5919 check_flags(flags);
5920 lockdep_recursion_inc();
5921 __lock_acquired(lock, ip);
5922 lockdep_recursion_finish();
5923 raw_local_irq_restore(flags);
5924}
5925EXPORT_SYMBOL_GPL(lock_acquired);
5926#endif
5927
5928/*
5929 * Used by the testsuite, sanitize the validator state
5930 * after a simulated failure:
5931 */
5932
5933void lockdep_reset(void)
5934{
5935 unsigned long flags;
5936 int i;
5937
5938 raw_local_irq_save(flags);
5939 lockdep_init_task(current);
5940 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
5941 nr_hardirq_chains = 0;
5942 nr_softirq_chains = 0;
5943 nr_process_chains = 0;
5944 debug_locks = 1;
5945 for (i = 0; i < CHAINHASH_SIZE; i++)
5946 INIT_HLIST_HEAD(chainhash_table + i);
5947 raw_local_irq_restore(flags);
5948}
5949
5950/* Remove a class from a lock chain. Must be called with the graph lock held. */
5951static void remove_class_from_lock_chain(struct pending_free *pf,
5952 struct lock_chain *chain,
5953 struct lock_class *class)
5954{
5955#ifdef CONFIG_PROVE_LOCKING
5956 int i;
5957
5958 for (i = chain->base; i < chain->base + chain->depth; i++) {
5959 if (chain_hlock_class_idx(chain_hlocks[i]) != class - lock_classes)
5960 continue;
5961 /*
5962 * Each lock class occurs at most once in a lock chain so once
5963 * we found a match we can break out of this loop.
5964 */
5965 goto free_lock_chain;
5966 }
5967 /* Since the chain has not been modified, return. */
5968 return;
5969
5970free_lock_chain:
5971 free_chain_hlocks(chain->base, chain->depth);
5972 /* Overwrite the chain key for concurrent RCU readers. */
5973 WRITE_ONCE(chain->chain_key, INITIAL_CHAIN_KEY);
5974 dec_chains(chain->irq_context);
5975
5976 /*
5977 * Note: calling hlist_del_rcu() from inside a
5978 * hlist_for_each_entry_rcu() loop is safe.
5979 */
5980 hlist_del_rcu(&chain->entry);
5981 __set_bit(chain - lock_chains, pf->lock_chains_being_freed);
5982 nr_zapped_lock_chains++;
5983#endif
5984}
5985
5986/* Must be called with the graph lock held. */
5987static void remove_class_from_lock_chains(struct pending_free *pf,
5988 struct lock_class *class)
5989{
5990 struct lock_chain *chain;
5991 struct hlist_head *head;
5992 int i;
5993
5994 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
5995 head = chainhash_table + i;
5996 hlist_for_each_entry_rcu(chain, head, entry) {
5997 remove_class_from_lock_chain(pf, chain, class);
5998 }
5999 }
6000}
6001
6002/*
6003 * Remove all references to a lock class. The caller must hold the graph lock.
6004 */
6005static void zap_class(struct pending_free *pf, struct lock_class *class)
6006{
6007 struct lock_list *entry;
6008 int i;
6009
6010 WARN_ON_ONCE(!class->key);
6011
6012 /*
6013 * Remove all dependencies this lock is
6014 * involved in:
6015 */
6016 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
6017 entry = list_entries + i;
6018 if (entry->class != class && entry->links_to != class)
6019 continue;
6020 __clear_bit(i, list_entries_in_use);
6021 nr_list_entries--;
6022 list_del_rcu(&entry->entry);
6023 }
6024 if (list_empty(&class->locks_after) &&
6025 list_empty(&class->locks_before)) {
6026 list_move_tail(&class->lock_entry, &pf->zapped);
6027 hlist_del_rcu(&class->hash_entry);
6028 WRITE_ONCE(class->key, NULL);
6029 WRITE_ONCE(class->name, NULL);
6030 nr_lock_classes--;
6031 __clear_bit(class - lock_classes, lock_classes_in_use);
6032 if (class - lock_classes == max_lock_class_idx)
6033 max_lock_class_idx--;
6034 } else {
6035 WARN_ONCE(true, "%s() failed for class %s\n", __func__,
6036 class->name);
6037 }
6038
6039 remove_class_from_lock_chains(pf, class);
6040 nr_zapped_classes++;
6041}
6042
6043static void reinit_class(struct lock_class *class)
6044{
6045 WARN_ON_ONCE(!class->lock_entry.next);
6046 WARN_ON_ONCE(!list_empty(&class->locks_after));
6047 WARN_ON_ONCE(!list_empty(&class->locks_before));
6048 memset_startat(class, 0, key);
6049 WARN_ON_ONCE(!class->lock_entry.next);
6050 WARN_ON_ONCE(!list_empty(&class->locks_after));
6051 WARN_ON_ONCE(!list_empty(&class->locks_before));
6052}
6053
6054static inline int within(const void *addr, void *start, unsigned long size)
6055{
6056 return addr >= start && addr < start + size;
6057}
6058
6059static bool inside_selftest(void)
6060{
6061 return current == lockdep_selftest_task_struct;
6062}
6063
6064/* The caller must hold the graph lock. */
6065static struct pending_free *get_pending_free(void)
6066{
6067 return delayed_free.pf + delayed_free.index;
6068}
6069
6070static void free_zapped_rcu(struct rcu_head *cb);
6071
6072/*
6073 * Schedule an RCU callback if no RCU callback is pending. Must be called with
6074 * the graph lock held.
6075 */
6076static void call_rcu_zapped(struct pending_free *pf)
6077{
6078 WARN_ON_ONCE(inside_selftest());
6079
6080 if (list_empty(&pf->zapped))
6081 return;
6082
6083 if (delayed_free.scheduled)
6084 return;
6085
6086 delayed_free.scheduled = true;
6087
6088 WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf);
6089 delayed_free.index ^= 1;
6090
6091 call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
6092}
6093
6094/* The caller must hold the graph lock. May be called from RCU context. */
6095static void __free_zapped_classes(struct pending_free *pf)
6096{
6097 struct lock_class *class;
6098
6099 check_data_structures();
6100
6101 list_for_each_entry(class, &pf->zapped, lock_entry)
6102 reinit_class(class);
6103
6104 list_splice_init(&pf->zapped, &free_lock_classes);
6105
6106#ifdef CONFIG_PROVE_LOCKING
6107 bitmap_andnot(lock_chains_in_use, lock_chains_in_use,
6108 pf->lock_chains_being_freed, ARRAY_SIZE(lock_chains));
6109 bitmap_clear(pf->lock_chains_being_freed, 0, ARRAY_SIZE(lock_chains));
6110#endif
6111}
6112
6113static void free_zapped_rcu(struct rcu_head *ch)
6114{
6115 struct pending_free *pf;
6116 unsigned long flags;
6117
6118 if (WARN_ON_ONCE(ch != &delayed_free.rcu_head))
6119 return;
6120
6121 raw_local_irq_save(flags);
6122 lockdep_lock();
6123
6124 /* closed head */
6125 pf = delayed_free.pf + (delayed_free.index ^ 1);
6126 __free_zapped_classes(pf);
6127 delayed_free.scheduled = false;
6128
6129 /*
6130 * If there's anything on the open list, close and start a new callback.
6131 */
6132 call_rcu_zapped(delayed_free.pf + delayed_free.index);
6133
6134 lockdep_unlock();
6135 raw_local_irq_restore(flags);
6136}
6137
6138/*
6139 * Remove all lock classes from the class hash table and from the
6140 * all_lock_classes list whose key or name is in the address range [start,
6141 * start + size). Move these lock classes to the zapped_classes list. Must
6142 * be called with the graph lock held.
6143 */
6144static void __lockdep_free_key_range(struct pending_free *pf, void *start,
6145 unsigned long size)
6146{
6147 struct lock_class *class;
6148 struct hlist_head *head;
6149 int i;
6150
6151 /* Unhash all classes that were created by a module. */
6152 for (i = 0; i < CLASSHASH_SIZE; i++) {
6153 head = classhash_table + i;
6154 hlist_for_each_entry_rcu(class, head, hash_entry) {
6155 if (!within(class->key, start, size) &&
6156 !within(class->name, start, size))
6157 continue;
6158 zap_class(pf, class);
6159 }
6160 }
6161}
6162
6163/*
6164 * Used in module.c to remove lock classes from memory that is going to be
6165 * freed; and possibly re-used by other modules.
6166 *
6167 * We will have had one synchronize_rcu() before getting here, so we're
6168 * guaranteed nobody will look up these exact classes -- they're properly dead
6169 * but still allocated.
6170 */
6171static void lockdep_free_key_range_reg(void *start, unsigned long size)
6172{
6173 struct pending_free *pf;
6174 unsigned long flags;
6175
6176 init_data_structures_once();
6177
6178 raw_local_irq_save(flags);
6179 lockdep_lock();
6180 pf = get_pending_free();
6181 __lockdep_free_key_range(pf, start, size);
6182 call_rcu_zapped(pf);
6183 lockdep_unlock();
6184 raw_local_irq_restore(flags);
6185
6186 /*
6187 * Wait for any possible iterators from look_up_lock_class() to pass
6188 * before continuing to free the memory they refer to.
6189 */
6190 synchronize_rcu();
6191}
6192
6193/*
6194 * Free all lockdep keys in the range [start, start+size). Does not sleep.
6195 * Ignores debug_locks. Must only be used by the lockdep selftests.
6196 */
6197static void lockdep_free_key_range_imm(void *start, unsigned long size)
6198{
6199 struct pending_free *pf = delayed_free.pf;
6200 unsigned long flags;
6201
6202 init_data_structures_once();
6203
6204 raw_local_irq_save(flags);
6205 lockdep_lock();
6206 __lockdep_free_key_range(pf, start, size);
6207 __free_zapped_classes(pf);
6208 lockdep_unlock();
6209 raw_local_irq_restore(flags);
6210}
6211
6212void lockdep_free_key_range(void *start, unsigned long size)
6213{
6214 init_data_structures_once();
6215
6216 if (inside_selftest())
6217 lockdep_free_key_range_imm(start, size);
6218 else
6219 lockdep_free_key_range_reg(start, size);
6220}
6221
6222/*
6223 * Check whether any element of the @lock->class_cache[] array refers to a
6224 * registered lock class. The caller must hold either the graph lock or the
6225 * RCU read lock.
6226 */
6227static bool lock_class_cache_is_registered(struct lockdep_map *lock)
6228{
6229 struct lock_class *class;
6230 struct hlist_head *head;
6231 int i, j;
6232
6233 for (i = 0; i < CLASSHASH_SIZE; i++) {
6234 head = classhash_table + i;
6235 hlist_for_each_entry_rcu(class, head, hash_entry) {
6236 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
6237 if (lock->class_cache[j] == class)
6238 return true;
6239 }
6240 }
6241 return false;
6242}
6243
6244/* The caller must hold the graph lock. Does not sleep. */
6245static void __lockdep_reset_lock(struct pending_free *pf,
6246 struct lockdep_map *lock)
6247{
6248 struct lock_class *class;
6249 int j;
6250
6251 /*
6252 * Remove all classes this lock might have:
6253 */
6254 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
6255 /*
6256 * If the class exists we look it up and zap it:
6257 */
6258 class = look_up_lock_class(lock, j);
6259 if (class)
6260 zap_class(pf, class);
6261 }
6262 /*
6263 * Debug check: in the end all mapped classes should
6264 * be gone.
6265 */
6266 if (WARN_ON_ONCE(lock_class_cache_is_registered(lock)))
6267 debug_locks_off();
6268}
6269
6270/*
6271 * Remove all information lockdep has about a lock if debug_locks == 1. Free
6272 * released data structures from RCU context.
6273 */
6274static void lockdep_reset_lock_reg(struct lockdep_map *lock)
6275{
6276 struct pending_free *pf;
6277 unsigned long flags;
6278 int locked;
6279
6280 raw_local_irq_save(flags);
6281 locked = graph_lock();
6282 if (!locked)
6283 goto out_irq;
6284
6285 pf = get_pending_free();
6286 __lockdep_reset_lock(pf, lock);
6287 call_rcu_zapped(pf);
6288
6289 graph_unlock();
6290out_irq:
6291 raw_local_irq_restore(flags);
6292}
6293
6294/*
6295 * Reset a lock. Does not sleep. Ignores debug_locks. Must only be used by the
6296 * lockdep selftests.
6297 */
6298static void lockdep_reset_lock_imm(struct lockdep_map *lock)
6299{
6300 struct pending_free *pf = delayed_free.pf;
6301 unsigned long flags;
6302
6303 raw_local_irq_save(flags);
6304 lockdep_lock();
6305 __lockdep_reset_lock(pf, lock);
6306 __free_zapped_classes(pf);
6307 lockdep_unlock();
6308 raw_local_irq_restore(flags);
6309}
6310
6311void lockdep_reset_lock(struct lockdep_map *lock)
6312{
6313 init_data_structures_once();
6314
6315 if (inside_selftest())
6316 lockdep_reset_lock_imm(lock);
6317 else
6318 lockdep_reset_lock_reg(lock);
6319}
6320
6321/*
6322 * Unregister a dynamically allocated key.
6323 *
6324 * Unlike lockdep_register_key(), a search is always done to find a matching
6325 * key irrespective of debug_locks to avoid potential invalid access to freed
6326 * memory in lock_class entry.
6327 */
6328void lockdep_unregister_key(struct lock_class_key *key)
6329{
6330 struct hlist_head *hash_head = keyhashentry(key);
6331 struct lock_class_key *k;
6332 struct pending_free *pf;
6333 unsigned long flags;
6334 bool found = false;
6335
6336 might_sleep();
6337
6338 if (WARN_ON_ONCE(static_obj(key)))
6339 return;
6340
6341 raw_local_irq_save(flags);
6342 lockdep_lock();
6343
6344 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
6345 if (k == key) {
6346 hlist_del_rcu(&k->hash_entry);
6347 found = true;
6348 break;
6349 }
6350 }
6351 WARN_ON_ONCE(!found && debug_locks);
6352 if (found) {
6353 pf = get_pending_free();
6354 __lockdep_free_key_range(pf, key, 1);
6355 call_rcu_zapped(pf);
6356 }
6357 lockdep_unlock();
6358 raw_local_irq_restore(flags);
6359
6360 /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */
6361 synchronize_rcu();
6362}
6363EXPORT_SYMBOL_GPL(lockdep_unregister_key);
6364
6365void __init lockdep_init(void)
6366{
6367 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
6368
6369 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
6370 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
6371 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
6372 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
6373 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
6374 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
6375 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
6376
6377 printk(" memory used by lock dependency info: %zu kB\n",
6378 (sizeof(lock_classes) +
6379 sizeof(lock_classes_in_use) +
6380 sizeof(classhash_table) +
6381 sizeof(list_entries) +
6382 sizeof(list_entries_in_use) +
6383 sizeof(chainhash_table) +
6384 sizeof(delayed_free)
6385#ifdef CONFIG_PROVE_LOCKING
6386 + sizeof(lock_cq)
6387 + sizeof(lock_chains)
6388 + sizeof(lock_chains_in_use)
6389 + sizeof(chain_hlocks)
6390#endif
6391 ) / 1024
6392 );
6393
6394#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
6395 printk(" memory used for stack traces: %zu kB\n",
6396 (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024
6397 );
6398#endif
6399
6400 printk(" per task-struct memory footprint: %zu bytes\n",
6401 sizeof(((struct task_struct *)NULL)->held_locks));
6402}
6403
6404static void
6405print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
6406 const void *mem_to, struct held_lock *hlock)
6407{
6408 if (!debug_locks_off())
6409 return;
6410 if (debug_locks_silent)
6411 return;
6412
6413 pr_warn("\n");
6414 pr_warn("=========================\n");
6415 pr_warn("WARNING: held lock freed!\n");
6416 print_kernel_ident();
6417 pr_warn("-------------------------\n");
6418 pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
6419 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
6420 print_lock(hlock);
6421 lockdep_print_held_locks(curr);
6422
6423 pr_warn("\nstack backtrace:\n");
6424 dump_stack();
6425}
6426
6427static inline int not_in_range(const void* mem_from, unsigned long mem_len,
6428 const void* lock_from, unsigned long lock_len)
6429{
6430 return lock_from + lock_len <= mem_from ||
6431 mem_from + mem_len <= lock_from;
6432}
6433
6434/*
6435 * Called when kernel memory is freed (or unmapped), or if a lock
6436 * is destroyed or reinitialized - this code checks whether there is
6437 * any held lock in the memory range of <from> to <to>:
6438 */
6439void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
6440{
6441 struct task_struct *curr = current;
6442 struct held_lock *hlock;
6443 unsigned long flags;
6444 int i;
6445
6446 if (unlikely(!debug_locks))
6447 return;
6448
6449 raw_local_irq_save(flags);
6450 for (i = 0; i < curr->lockdep_depth; i++) {
6451 hlock = curr->held_locks + i;
6452
6453 if (not_in_range(mem_from, mem_len, hlock->instance,
6454 sizeof(*hlock->instance)))
6455 continue;
6456
6457 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
6458 break;
6459 }
6460 raw_local_irq_restore(flags);
6461}
6462EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
6463
6464static void print_held_locks_bug(void)
6465{
6466 if (!debug_locks_off())
6467 return;
6468 if (debug_locks_silent)
6469 return;
6470
6471 pr_warn("\n");
6472 pr_warn("====================================\n");
6473 pr_warn("WARNING: %s/%d still has locks held!\n",
6474 current->comm, task_pid_nr(current));
6475 print_kernel_ident();
6476 pr_warn("------------------------------------\n");
6477 lockdep_print_held_locks(current);
6478 pr_warn("\nstack backtrace:\n");
6479 dump_stack();
6480}
6481
6482void debug_check_no_locks_held(void)
6483{
6484 if (unlikely(current->lockdep_depth > 0))
6485 print_held_locks_bug();
6486}
6487EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
6488
6489#ifdef __KERNEL__
6490void debug_show_all_locks(void)
6491{
6492 struct task_struct *g, *p;
6493
6494 if (unlikely(!debug_locks)) {
6495 pr_warn("INFO: lockdep is turned off.\n");
6496 return;
6497 }
6498 pr_warn("\nShowing all locks held in the system:\n");
6499
6500 rcu_read_lock();
6501 for_each_process_thread(g, p) {
6502 if (!p->lockdep_depth)
6503 continue;
6504 lockdep_print_held_locks(p);
6505 touch_nmi_watchdog();
6506 touch_all_softlockup_watchdogs();
6507 }
6508 rcu_read_unlock();
6509
6510 pr_warn("\n");
6511 pr_warn("=============================================\n\n");
6512}
6513EXPORT_SYMBOL_GPL(debug_show_all_locks);
6514#endif
6515
6516/*
6517 * Careful: only use this function if you are sure that
6518 * the task cannot run in parallel!
6519 */
6520void debug_show_held_locks(struct task_struct *task)
6521{
6522 if (unlikely(!debug_locks)) {
6523 printk("INFO: lockdep is turned off.\n");
6524 return;
6525 }
6526 lockdep_print_held_locks(task);
6527}
6528EXPORT_SYMBOL_GPL(debug_show_held_locks);
6529
6530asmlinkage __visible void lockdep_sys_exit(void)
6531{
6532 struct task_struct *curr = current;
6533
6534 if (unlikely(curr->lockdep_depth)) {
6535 if (!debug_locks_off())
6536 return;
6537 pr_warn("\n");
6538 pr_warn("================================================\n");
6539 pr_warn("WARNING: lock held when returning to user space!\n");
6540 print_kernel_ident();
6541 pr_warn("------------------------------------------------\n");
6542 pr_warn("%s/%d is leaving the kernel with locks still held!\n",
6543 curr->comm, curr->pid);
6544 lockdep_print_held_locks(curr);
6545 }
6546
6547 /*
6548 * The lock history for each syscall should be independent. So wipe the
6549 * slate clean on return to userspace.
6550 */
6551 lockdep_invariant_state(false);
6552}
6553
6554void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
6555{
6556 struct task_struct *curr = current;
6557 int dl = READ_ONCE(debug_locks);
6558
6559 /* Note: the following can be executed concurrently, so be careful. */
6560 pr_warn("\n");
6561 pr_warn("=============================\n");
6562 pr_warn("WARNING: suspicious RCU usage\n");
6563 print_kernel_ident();
6564 pr_warn("-----------------------------\n");
6565 pr_warn("%s:%d %s!\n", file, line, s);
6566 pr_warn("\nother info that might help us debug this:\n\n");
6567 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n%s",
6568 !rcu_lockdep_current_cpu_online()
6569 ? "RCU used illegally from offline CPU!\n"
6570 : "",
6571 rcu_scheduler_active, dl,
6572 dl ? "" : "Possible false positive due to lockdep disabling via debug_locks = 0\n");
6573
6574 /*
6575 * If a CPU is in the RCU-free window in idle (ie: in the section
6576 * between ct_idle_enter() and ct_idle_exit(), then RCU
6577 * considers that CPU to be in an "extended quiescent state",
6578 * which means that RCU will be completely ignoring that CPU.
6579 * Therefore, rcu_read_lock() and friends have absolutely no
6580 * effect on a CPU running in that state. In other words, even if
6581 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
6582 * delete data structures out from under it. RCU really has no
6583 * choice here: we need to keep an RCU-free window in idle where
6584 * the CPU may possibly enter into low power mode. This way we can
6585 * notice an extended quiescent state to other CPUs that started a grace
6586 * period. Otherwise we would delay any grace period as long as we run
6587 * in the idle task.
6588 *
6589 * So complain bitterly if someone does call rcu_read_lock(),
6590 * rcu_read_lock_bh() and so on from extended quiescent states.
6591 */
6592 if (!rcu_is_watching())
6593 pr_warn("RCU used illegally from extended quiescent state!\n");
6594
6595 lockdep_print_held_locks(curr);
6596 pr_warn("\nstack backtrace:\n");
6597 dump_stack();
6598}
6599EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);