projects/linux·blob v7.2 · refs

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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#include <linux/context_tracking.h>
59#include <linux/console.h>
60#include <linux/kasan.h>
61
62#include <asm/sections.h>
63
64#include "lockdep_internals.h"
65#include "lock_events.h"
66
67#include <trace/events/lock.h>
68
69#ifdef CONFIG_PROVE_LOCKING
70static int prove_locking = 1;
71module_param(prove_locking, int, 0644);
72#else
73#define prove_locking 0
74#endif
75
76#ifdef CONFIG_LOCK_STAT
77static int lock_stat = 1;
78module_param(lock_stat, int, 0644);
79#else
80#define lock_stat 0
81#endif
82
83#ifdef CONFIG_SYSCTL
84static const struct ctl_table kern_lockdep_table[] = {
85#ifdef CONFIG_PROVE_LOCKING
86 {
87 .procname = "prove_locking",
88 .data = &prove_locking,
89 .maxlen = sizeof(int),
90 .mode = 0644,
91 .proc_handler = proc_dointvec,
92 },
93#endif /* CONFIG_PROVE_LOCKING */
94#ifdef CONFIG_LOCK_STAT
95 {
96 .procname = "lock_stat",
97 .data = &lock_stat,
98 .maxlen = sizeof(int),
99 .mode = 0644,
100 .proc_handler = proc_dointvec,
101 },
102#endif /* CONFIG_LOCK_STAT */
103};
104
105static __init int kernel_lockdep_sysctls_init(void)
106{
107 register_sysctl_init("kernel", kern_lockdep_table);
108 return 0;
109}
110late_initcall(kernel_lockdep_sysctls_init);
111#endif /* CONFIG_SYSCTL */
112
113DEFINE_PER_CPU(unsigned int, lockdep_recursion);
114EXPORT_PER_CPU_SYMBOL_GPL(lockdep_recursion);
115
116static __always_inline bool lockdep_enabled(void)
117{
118 if (!debug_locks)
119 return false;
120
121 if (this_cpu_read(lockdep_recursion))
122 return false;
123
124 if (current->lockdep_recursion)
125 return false;
126
127 return true;
128}
129
130/*
131 * lockdep_lock: protects the lockdep graph, the hashes and the
132 * class/list/hash allocators.
133 *
134 * This is one of the rare exceptions where it's justified
135 * to use a raw spinlock - we really dont want the spinlock
136 * code to recurse back into the lockdep code...
137 */
138static arch_spinlock_t __lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
139static struct task_struct *__owner;
140
141static inline void lockdep_lock(void)
142{
143 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
144
145 __this_cpu_inc(lockdep_recursion);
146 arch_spin_lock(&__lock);
147 __owner = current;
148}
149
150static inline void lockdep_unlock(void)
151{
152 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
153
154 if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current))
155 return;
156
157 __owner = NULL;
158 arch_spin_unlock(&__lock);
159 __this_cpu_dec(lockdep_recursion);
160}
161
162#ifdef CONFIG_PROVE_LOCKING
163static inline bool lockdep_assert_locked(void)
164{
165 return DEBUG_LOCKS_WARN_ON(__owner != current);
166}
167#endif
168
169static struct task_struct *lockdep_selftest_task_struct;
170
171
172static int graph_lock(void)
173{
174 lockdep_lock();
175 lockevent_inc(lockdep_lock);
176 /*
177 * Make sure that if another CPU detected a bug while
178 * walking the graph we dont change it (while the other
179 * CPU is busy printing out stuff with the graph lock
180 * dropped already)
181 */
182 if (!debug_locks) {
183 lockdep_unlock();
184 return 0;
185 }
186 return 1;
187}
188
189static inline void graph_unlock(void)
190{
191 lockdep_unlock();
192}
193
194/*
195 * Turn lock debugging off and return with 0 if it was off already,
196 * and also release the graph lock:
197 */
198static inline int debug_locks_off_graph_unlock(void)
199{
200 int ret = debug_locks_off();
201
202 lockdep_unlock();
203
204 return ret;
205}
206
207unsigned long nr_list_entries;
208static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
209static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES);
210
211/*
212 * All data structures here are protected by the global debug_lock.
213 *
214 * nr_lock_classes is the number of elements of lock_classes[] that is
215 * in use.
216 */
217#define KEYHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
218#define KEYHASH_SIZE (1UL << KEYHASH_BITS)
219static struct hlist_head lock_keys_hash[KEYHASH_SIZE];
220unsigned long nr_lock_classes;
221unsigned long nr_zapped_classes;
222unsigned long nr_dynamic_keys;
223unsigned long max_lock_class_idx;
224struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
225DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS);
226
227static inline struct lock_class *hlock_class(struct held_lock *hlock)
228{
229 unsigned int class_idx = hlock->class_idx;
230
231 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfield */
232 barrier();
233
234 if (!test_bit(class_idx, lock_classes_in_use)) {
235 /*
236 * Someone passed in garbage, we give up.
237 */
238 DEBUG_LOCKS_WARN_ON(1);
239 return NULL;
240 }
241
242 /*
243 * At this point, if the passed hlock->class_idx is still garbage,
244 * we just have to live with it
245 */
246 return lock_classes + class_idx;
247}
248
249#ifdef CONFIG_LOCK_STAT
250static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
251
252static inline u64 lockstat_clock(void)
253{
254 return local_clock();
255}
256
257static int lock_point(unsigned long points[], unsigned long ip)
258{
259 int i;
260
261 for (i = 0; i < LOCKSTAT_POINTS; i++) {
262 if (points[i] == 0) {
263 points[i] = ip;
264 break;
265 }
266 if (points[i] == ip)
267 break;
268 }
269
270 return i;
271}
272
273static void lock_time_inc(struct lock_time *lt, u64 time)
274{
275 if (time > lt->max)
276 lt->max = time;
277
278 if (time < lt->min || !lt->nr)
279 lt->min = time;
280
281 lt->total += time;
282 lt->nr++;
283}
284
285static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
286{
287 if (!src->nr)
288 return;
289
290 if (src->max > dst->max)
291 dst->max = src->max;
292
293 if (src->min < dst->min || !dst->nr)
294 dst->min = src->min;
295
296 dst->total += src->total;
297 dst->nr += src->nr;
298}
299
300void lock_stats(struct lock_class *class, struct lock_class_stats *stats)
301{
302 int cpu, i;
303
304 memset(stats, 0, sizeof(struct lock_class_stats));
305 for_each_possible_cpu(cpu) {
306 struct lock_class_stats *pcs =
307 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
308
309 for (i = 0; i < ARRAY_SIZE(stats->contention_point); i++)
310 stats->contention_point[i] += pcs->contention_point[i];
311
312 for (i = 0; i < ARRAY_SIZE(stats->contending_point); i++)
313 stats->contending_point[i] += pcs->contending_point[i];
314
315 lock_time_add(&pcs->read_waittime, &stats->read_waittime);
316 lock_time_add(&pcs->write_waittime, &stats->write_waittime);
317
318 lock_time_add(&pcs->read_holdtime, &stats->read_holdtime);
319 lock_time_add(&pcs->write_holdtime, &stats->write_holdtime);
320
321 for (i = 0; i < ARRAY_SIZE(stats->bounces); i++)
322 stats->bounces[i] += pcs->bounces[i];
323 }
324}
325
326void clear_lock_stats(struct lock_class *class)
327{
328 int cpu;
329
330 for_each_possible_cpu(cpu) {
331 struct lock_class_stats *cpu_stats =
332 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
333
334 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
335 }
336 memset(class->contention_point, 0, sizeof(class->contention_point));
337 memset(class->contending_point, 0, sizeof(class->contending_point));
338}
339
340static struct lock_class_stats *get_lock_stats(struct lock_class *class)
341{
342 return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes];
343}
344
345static void lock_release_holdtime(struct held_lock *hlock)
346{
347 struct lock_class_stats *stats;
348 u64 holdtime;
349
350 if (!lock_stat)
351 return;
352
353 holdtime = lockstat_clock() - hlock->holdtime_stamp;
354
355 stats = get_lock_stats(hlock_class(hlock));
356 if (hlock->read)
357 lock_time_inc(&stats->read_holdtime, holdtime);
358 else
359 lock_time_inc(&stats->write_holdtime, holdtime);
360}
361#else
362static inline void lock_release_holdtime(struct held_lock *hlock)
363{
364}
365#endif
366
367/*
368 * We keep a global list of all lock classes. The list is only accessed with
369 * the lockdep spinlock lock held. free_lock_classes is a list with free
370 * elements. These elements are linked together by the lock_entry member in
371 * struct lock_class.
372 */
373static LIST_HEAD(all_lock_classes);
374static LIST_HEAD(free_lock_classes);
375
376/**
377 * struct pending_free - information about data structures about to be freed
378 * @zapped: Head of a list with struct lock_class elements.
379 * @lock_chains_being_freed: Bitmap that indicates which lock_chains[] elements
380 * are about to be freed.
381 */
382struct pending_free {
383 struct list_head zapped;
384 DECLARE_BITMAP(lock_chains_being_freed, MAX_LOCKDEP_CHAINS);
385};
386
387/**
388 * struct delayed_free - data structures used for delayed freeing
389 *
390 * A data structure for delayed freeing of data structures that may be
391 * accessed by RCU readers at the time these were freed.
392 *
393 * @rcu_head: Used to schedule an RCU callback for freeing data structures.
394 * @index: Index of @pf to which freed data structures are added.
395 * @scheduled: Whether or not an RCU callback has been scheduled.
396 * @pf: Array with information about data structures about to be freed.
397 */
398static struct delayed_free {
399 struct rcu_head rcu_head;
400 int index;
401 int scheduled;
402 struct pending_free pf[2];
403} delayed_free;
404
405/*
406 * The lockdep classes are in a hash-table as well, for fast lookup:
407 */
408#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
409#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
410#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
411#define classhashentry(key) (classhash_table + __classhashfn((key)))
412
413static struct hlist_head classhash_table[CLASSHASH_SIZE];
414
415/*
416 * We put the lock dependency chains into a hash-table as well, to cache
417 * their existence:
418 */
419#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
420#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
421#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
422#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
423
424static struct hlist_head chainhash_table[CHAINHASH_SIZE];
425
426/*
427 * the id of held_lock
428 */
429static inline u16 hlock_id(struct held_lock *hlock)
430{
431 BUILD_BUG_ON(MAX_LOCKDEP_KEYS_BITS + 2 > 16);
432
433 return (hlock->class_idx | (hlock->read << MAX_LOCKDEP_KEYS_BITS));
434}
435
436static inline __maybe_unused unsigned int chain_hlock_class_idx(u16 hlock_id)
437{
438 return hlock_id & (MAX_LOCKDEP_KEYS - 1);
439}
440
441/*
442 * The hash key of the lock dependency chains is a hash itself too:
443 * it's a hash of all locks taken up to that lock, including that lock.
444 * It's a 64-bit hash, because it's important for the keys to be
445 * unique.
446 */
447static inline u64 iterate_chain_key(u64 key, u32 idx)
448{
449 u32 k0 = key, k1 = key >> 32;
450
451 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
452
453 return k0 | (u64)k1 << 32;
454}
455
456void lockdep_init_task(struct task_struct *task)
457{
458 task->lockdep_depth = 0; /* no locks held yet */
459 task->curr_chain_key = INITIAL_CHAIN_KEY;
460 task->lockdep_recursion = 0;
461}
462
463static __always_inline void lockdep_recursion_inc(void)
464{
465 __this_cpu_inc(lockdep_recursion);
466}
467
468static __always_inline void lockdep_recursion_finish(void)
469{
470 if (WARN_ON_ONCE(__this_cpu_dec_return(lockdep_recursion)))
471 __this_cpu_write(lockdep_recursion, 0);
472}
473
474void lockdep_set_selftest_task(struct task_struct *task)
475{
476 lockdep_selftest_task_struct = task;
477}
478
479/*
480 * Debugging switches:
481 */
482
483#define VERBOSE 0
484#define VERY_VERBOSE 0
485
486#if VERBOSE
487# define HARDIRQ_VERBOSE 1
488# define SOFTIRQ_VERBOSE 1
489#else
490# define HARDIRQ_VERBOSE 0
491# define SOFTIRQ_VERBOSE 0
492#endif
493
494#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
495/*
496 * Quick filtering for interesting events:
497 */
498static int class_filter(struct lock_class *class)
499{
500#if 0
501 /* Example */
502 if (class->name_version == 1 &&
503 !strcmp(class->name, "lockname"))
504 return 1;
505 if (class->name_version == 1 &&
506 !strcmp(class->name, "&struct->lockfield"))
507 return 1;
508#endif
509 /* Filter everything else. 1 would be to allow everything else */
510 return 0;
511}
512#endif
513
514static int verbose(struct lock_class *class)
515{
516#if VERBOSE
517 return class_filter(class);
518#endif
519 return 0;
520}
521
522static void print_lockdep_off(const char *bug_msg)
523{
524 printk(KERN_DEBUG "%s\n", bug_msg);
525 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
526#ifdef CONFIG_LOCK_STAT
527 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
528#endif
529}
530
531unsigned long nr_stack_trace_entries;
532
533#ifdef CONFIG_PROVE_LOCKING
534/**
535 * struct lock_trace - single stack backtrace
536 * @hash_entry: Entry in a stack_trace_hash[] list.
537 * @hash: jhash() of @entries.
538 * @nr_entries: Number of entries in @entries.
539 * @entries: Actual stack backtrace.
540 */
541struct lock_trace {
542 struct hlist_node hash_entry;
543 u32 hash;
544 u32 nr_entries;
545 unsigned long entries[] __aligned(sizeof(unsigned long));
546};
547#define LOCK_TRACE_SIZE_IN_LONGS \
548 (sizeof(struct lock_trace) / sizeof(unsigned long))
549/*
550 * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock.
551 */
552static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
553static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE];
554
555static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2)
556{
557 return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries &&
558 memcmp(t1->entries, t2->entries,
559 t1->nr_entries * sizeof(t1->entries[0])) == 0;
560}
561
562static struct lock_trace *save_trace(void)
563{
564 struct lock_trace *trace, *t2;
565 struct hlist_head *hash_head;
566 u32 hash;
567 int max_entries;
568
569 BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE);
570 BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES);
571
572 trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries);
573 max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries -
574 LOCK_TRACE_SIZE_IN_LONGS;
575
576 if (max_entries <= 0) {
577 if (!debug_locks_off_graph_unlock())
578 return NULL;
579
580 nbcon_cpu_emergency_enter();
581 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
582 dump_stack();
583 nbcon_cpu_emergency_exit();
584
585 return NULL;
586 }
587 trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
588
589 hash = jhash(trace->entries, trace->nr_entries *
590 sizeof(trace->entries[0]), 0);
591 trace->hash = hash;
592 hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1));
593 hlist_for_each_entry(t2, hash_head, hash_entry) {
594 if (traces_identical(trace, t2))
595 return t2;
596 }
597 nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries;
598 hlist_add_head(&trace->hash_entry, hash_head);
599
600 return trace;
601}
602
603/* Return the number of stack traces in the stack_trace[] array. */
604u64 lockdep_stack_trace_count(void)
605{
606 struct lock_trace *trace;
607 u64 c = 0;
608 int i;
609
610 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) {
611 hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) {
612 c++;
613 }
614 }
615
616 return c;
617}
618
619/* Return the number of stack hash chains that have at least one stack trace. */
620u64 lockdep_stack_hash_count(void)
621{
622 u64 c = 0;
623 int i;
624
625 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++)
626 if (!hlist_empty(&stack_trace_hash[i]))
627 c++;
628
629 return c;
630}
631#endif
632
633unsigned int nr_hardirq_chains;
634unsigned int nr_softirq_chains;
635unsigned int nr_process_chains;
636unsigned int max_lockdep_depth;
637
638#ifdef CONFIG_DEBUG_LOCKDEP
639/*
640 * Various lockdep statistics:
641 */
642DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
643#endif
644
645#ifdef CONFIG_PROVE_LOCKING
646/*
647 * Locking printouts:
648 */
649
650#define __USAGE(__STATE) \
651 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
652 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
653 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
654 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
655
656static const char *usage_str[] =
657{
658#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
659#include "lockdep_states.h"
660#undef LOCKDEP_STATE
661 [LOCK_USED] = "INITIAL USE",
662 [LOCK_USED_READ] = "INITIAL READ USE",
663 /* abused as string storage for verify_lock_unused() */
664 [LOCK_USAGE_STATES] = "IN-NMI",
665};
666#endif
667
668const char *__get_key_name(const struct lockdep_subclass_key *key, char *str)
669{
670 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
671}
672
673static inline unsigned long lock_flag(enum lock_usage_bit bit)
674{
675 return 1UL << bit;
676}
677
678static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
679{
680 /*
681 * The usage character defaults to '.' (i.e., irqs disabled and not in
682 * irq context), which is the safest usage category.
683 */
684 char c = '.';
685
686 /*
687 * The order of the following usage checks matters, which will
688 * result in the outcome character as follows:
689 *
690 * - '+': irq is enabled and not in irq context
691 * - '-': in irq context and irq is disabled
692 * - '?': in irq context and irq is enabled
693 */
694 if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) {
695 c = '+';
696 if (class->usage_mask & lock_flag(bit))
697 c = '?';
698 } else if (class->usage_mask & lock_flag(bit))
699 c = '-';
700
701 return c;
702}
703
704void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
705{
706 int i = 0;
707
708#define LOCKDEP_STATE(__STATE) \
709 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
710 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
711#include "lockdep_states.h"
712#undef LOCKDEP_STATE
713
714 usage[i] = '\0';
715}
716
717static void __print_lock_name(struct held_lock *hlock, struct lock_class *class)
718{
719 char str[KSYM_NAME_LEN];
720 const char *name;
721
722 name = class->name;
723 if (!name) {
724 name = __get_key_name(class->key, str);
725 printk(KERN_CONT "%s", name);
726 } else {
727 printk(KERN_CONT "%s", name);
728 if (class->name_version > 1)
729 printk(KERN_CONT "#%d", class->name_version);
730 if (class->subclass)
731 printk(KERN_CONT "/%d", class->subclass);
732 if (hlock && class->print_fn)
733 class->print_fn(hlock->instance);
734 }
735}
736
737static void print_lock_name(struct held_lock *hlock, struct lock_class *class)
738{
739 char usage[LOCK_USAGE_CHARS];
740
741 get_usage_chars(class, usage);
742
743 printk(KERN_CONT " (");
744 __print_lock_name(hlock, class);
745 printk(KERN_CONT "){%s}-{%d:%d}", usage,
746 class->wait_type_outer ?: class->wait_type_inner,
747 class->wait_type_inner);
748}
749
750static void print_lockdep_cache(struct lockdep_map *lock)
751{
752 const char *name;
753 char str[KSYM_NAME_LEN];
754
755 name = lock->name;
756 if (!name)
757 name = __get_key_name(lock->key->subkeys, str);
758
759 printk(KERN_CONT "%s", name);
760}
761
762static void print_lock(struct held_lock *hlock)
763{
764 /*
765 * We can be called locklessly through debug_show_all_locks() so be
766 * extra careful, the hlock might have been released and cleared.
767 *
768 * If this indeed happens, lets pretend it does not hurt to continue
769 * to print the lock unless the hlock class_idx does not point to a
770 * registered class. The rationale here is: since we don't attempt
771 * to distinguish whether we are in this situation, if it just
772 * happened we can't count on class_idx to tell either.
773 */
774 struct lock_class *lock = hlock_class(hlock);
775
776 if (!lock) {
777 printk(KERN_CONT "<RELEASED>\n");
778 return;
779 }
780
781 printk(KERN_CONT "%px", hlock->instance);
782 print_lock_name(hlock, lock);
783 printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
784}
785
786static void lockdep_print_held_locks(struct task_struct *p)
787{
788 int i, depth = READ_ONCE(p->lockdep_depth);
789
790 if (!depth)
791 printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p));
792 else
793 printk("%d lock%s held by %s/%d:\n", depth,
794 str_plural(depth), p->comm, task_pid_nr(p));
795 /*
796 * It's not reliable to print a task's held locks if it's not sleeping
797 * and it's not the current task.
798 */
799 if (p != current && task_is_running(p))
800 return;
801 for (i = 0; i < depth; i++) {
802 printk(" #%d: ", i);
803 print_lock(p->held_locks + i);
804 }
805}
806
807static void print_kernel_ident(void)
808{
809 printk("%s %.*s %s\n", init_utsname()->release,
810 (int)strcspn(init_utsname()->version, " "),
811 init_utsname()->version,
812 print_tainted());
813}
814
815static int very_verbose(struct lock_class *class)
816{
817#if VERY_VERBOSE
818 return class_filter(class);
819#endif
820 return 0;
821}
822
823/*
824 * Is this the address of a static object:
825 */
826#ifdef __KERNEL__
827static int static_obj(const void *obj)
828{
829 unsigned long addr = (unsigned long) obj;
830
831 if (is_kernel_core_data(addr))
832 return 1;
833
834 /*
835 * keys are allowed in the __ro_after_init section.
836 */
837 if (is_kernel_rodata(addr))
838 return 1;
839
840 /*
841 * in initdata section and used during bootup only?
842 * NOTE: On some platforms the initdata section is
843 * outside of the _stext ... _end range.
844 */
845 if (system_state < SYSTEM_FREEING_INITMEM &&
846 init_section_contains((void *)addr, 1))
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 nbcon_cpu_emergency_enter();
897 printk(KERN_ERR
898 "BUG: looking up invalid subclass: %u\n", subclass);
899 printk(KERN_ERR
900 "turning off the locking correctness validator.\n");
901 dump_stack();
902 nbcon_cpu_emergency_exit();
903 instrumentation_end();
904 return NULL;
905 }
906
907 /*
908 * If it is not initialised then it has never been locked,
909 * so it won't be present in the hash table.
910 */
911 if (unlikely(!lock->key))
912 return NULL;
913
914 /*
915 * NOTE: the class-key must be unique. For dynamic locks, a static
916 * lock_class_key variable is passed in through the mutex_init()
917 * (or spin_lock_init()) call - which acts as the key. For static
918 * locks we use the lock object itself as the key.
919 */
920 BUILD_BUG_ON(sizeof(struct lock_class_key) >
921 sizeof(struct lockdep_map));
922
923 key = lock->key->subkeys + subclass;
924
925 hash_head = classhashentry(key);
926
927 /*
928 * We do an RCU walk of the hash, see lockdep_free_key_range().
929 */
930 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
931 return NULL;
932
933 hlist_for_each_entry_rcu_notrace(class, hash_head, hash_entry) {
934 if (class->key == key) {
935 /*
936 * Huh! same key, different name? Did someone trample
937 * on some memory? We're most confused.
938 */
939 WARN_ONCE(class->name != lock->name &&
940 lock->key != &__lockdep_no_validate__,
941 "Looking for class \"%s\" with key %ps, but found a different class \"%s\" with the same key\n",
942 lock->name, lock->key, class->name);
943 return class;
944 }
945 }
946
947 return NULL;
948}
949
950/*
951 * Static locks do not have their class-keys yet - for them the key is
952 * the lock object itself. If the lock is in the per cpu area, the
953 * canonical address of the lock (per cpu offset removed) is used.
954 */
955static bool assign_lock_key(struct lockdep_map *lock)
956{
957 unsigned long can_addr, addr = (unsigned long)lock;
958
959#ifdef __KERNEL__
960 /*
961 * lockdep_free_key_range() assumes that struct lock_class_key
962 * objects do not overlap. Since we use the address of lock
963 * objects as class key for static objects, check whether the
964 * size of lock_class_key objects does not exceed the size of
965 * the smallest lock object.
966 */
967 BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
968#endif
969
970 if (__is_kernel_percpu_address(addr, &can_addr))
971 lock->key = (void *)can_addr;
972 else if (__is_module_percpu_address(addr, &can_addr))
973 lock->key = (void *)can_addr;
974 else if (static_obj(lock))
975 lock->key = (void *)lock;
976 else {
977 /* Debug-check: all keys must be persistent! */
978 debug_locks_off();
979 nbcon_cpu_emergency_enter();
980 pr_err("INFO: trying to register non-static key.\n");
981 pr_err("The code is fine but needs lockdep annotation, or maybe\n");
982 pr_err("you didn't initialize this object before use?\n");
983 pr_err("turning off the locking correctness validator.\n");
984 dump_stack();
985 nbcon_cpu_emergency_exit();
986 return false;
987 }
988
989 return true;
990}
991
992#ifdef CONFIG_DEBUG_LOCKDEP
993
994/* Check whether element @e occurs in list @h */
995static bool in_list(struct list_head *e, struct list_head *h)
996{
997 struct list_head *f;
998
999 list_for_each(f, h) {
1000 if (e == f)
1001 return true;
1002 }
1003
1004 return false;
1005}
1006
1007/*
1008 * Check whether entry @e occurs in any of the locks_after or locks_before
1009 * lists.
1010 */
1011static bool in_any_class_list(struct list_head *e)
1012{
1013 struct lock_class *class;
1014 int i;
1015
1016 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1017 class = &lock_classes[i];
1018 if (in_list(e, &class->locks_after) ||
1019 in_list(e, &class->locks_before))
1020 return true;
1021 }
1022 return false;
1023}
1024
1025static bool class_lock_list_valid(struct lock_class *c, struct list_head *h)
1026{
1027 struct lock_list *e;
1028
1029 list_for_each_entry(e, h, entry) {
1030 if (e->links_to != c) {
1031 printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s",
1032 c->name ? : "(?)",
1033 (unsigned long)(e - list_entries),
1034 e->links_to && e->links_to->name ?
1035 e->links_to->name : "(?)",
1036 e->class && e->class->name ? e->class->name :
1037 "(?)");
1038 return false;
1039 }
1040 }
1041 return true;
1042}
1043
1044#ifdef CONFIG_PROVE_LOCKING
1045static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1046#endif
1047
1048static bool check_lock_chain_key(struct lock_chain *chain)
1049{
1050#ifdef CONFIG_PROVE_LOCKING
1051 u64 chain_key = INITIAL_CHAIN_KEY;
1052 int i;
1053
1054 for (i = chain->base; i < chain->base + chain->depth; i++)
1055 chain_key = iterate_chain_key(chain_key, chain_hlocks[i]);
1056 /*
1057 * The 'unsigned long long' casts avoid that a compiler warning
1058 * is reported when building tools/lib/lockdep.
1059 */
1060 if (chain->chain_key != chain_key) {
1061 printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n",
1062 (unsigned long long)(chain - lock_chains),
1063 (unsigned long long)chain->chain_key,
1064 (unsigned long long)chain_key);
1065 return false;
1066 }
1067#endif
1068 return true;
1069}
1070
1071static bool in_any_zapped_class_list(struct lock_class *class)
1072{
1073 struct pending_free *pf;
1074 int i;
1075
1076 for (i = 0, pf = delayed_free.pf; i < ARRAY_SIZE(delayed_free.pf); i++, pf++) {
1077 if (in_list(&class->lock_entry, &pf->zapped))
1078 return true;
1079 }
1080
1081 return false;
1082}
1083
1084static bool __check_data_structures(void)
1085{
1086 struct lock_class *class;
1087 struct lock_chain *chain;
1088 struct hlist_head *head;
1089 struct lock_list *e;
1090 int i;
1091
1092 /* Check whether all classes occur in a lock list. */
1093 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1094 class = &lock_classes[i];
1095 if (!in_list(&class->lock_entry, &all_lock_classes) &&
1096 !in_list(&class->lock_entry, &free_lock_classes) &&
1097 !in_any_zapped_class_list(class)) {
1098 printk(KERN_INFO "class %px/%s is not in any class list\n",
1099 class, class->name ? : "(?)");
1100 return false;
1101 }
1102 }
1103
1104 /* Check whether all classes have valid lock lists. */
1105 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1106 class = &lock_classes[i];
1107 if (!class_lock_list_valid(class, &class->locks_before))
1108 return false;
1109 if (!class_lock_list_valid(class, &class->locks_after))
1110 return false;
1111 }
1112
1113 /* Check the chain_key of all lock chains. */
1114 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
1115 head = chainhash_table + i;
1116 hlist_for_each_entry_rcu(chain, head, entry) {
1117 if (!check_lock_chain_key(chain))
1118 return false;
1119 }
1120 }
1121
1122 /*
1123 * Check whether all list entries that are in use occur in a class
1124 * lock list.
1125 */
1126 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1127 e = list_entries + i;
1128 if (!in_any_class_list(&e->entry)) {
1129 printk(KERN_INFO "list entry %d is not in any class list; class %s <> %s\n",
1130 (unsigned int)(e - list_entries),
1131 e->class->name ? : "(?)",
1132 e->links_to->name ? : "(?)");
1133 return false;
1134 }
1135 }
1136
1137 /*
1138 * Check whether all list entries that are not in use do not occur in
1139 * a class lock list.
1140 */
1141 for_each_clear_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1142 e = list_entries + i;
1143 if (in_any_class_list(&e->entry)) {
1144 printk(KERN_INFO "list entry %d occurs in a class list; class %s <> %s\n",
1145 (unsigned int)(e - list_entries),
1146 e->class && e->class->name ? e->class->name :
1147 "(?)",
1148 e->links_to && e->links_to->name ?
1149 e->links_to->name : "(?)");
1150 return false;
1151 }
1152 }
1153
1154 return true;
1155}
1156
1157int check_consistency = 0;
1158module_param(check_consistency, int, 0644);
1159
1160static void check_data_structures(void)
1161{
1162 static bool once = false;
1163
1164 if (check_consistency && !once) {
1165 if (!__check_data_structures()) {
1166 once = true;
1167 WARN_ON(once);
1168 }
1169 }
1170}
1171
1172#else /* CONFIG_DEBUG_LOCKDEP */
1173
1174static inline void check_data_structures(void) { }
1175
1176#endif /* CONFIG_DEBUG_LOCKDEP */
1177
1178static void init_chain_block_buckets(void);
1179
1180/*
1181 * Initialize the lock_classes[] array elements, the free_lock_classes list
1182 * and also the delayed_free structure.
1183 */
1184static void init_data_structures_once(void)
1185{
1186 static bool __read_mostly ds_initialized, rcu_head_initialized;
1187 int i;
1188
1189 if (likely(rcu_head_initialized))
1190 return;
1191
1192 if (system_state >= SYSTEM_SCHEDULING) {
1193 init_rcu_head(&delayed_free.rcu_head);
1194 rcu_head_initialized = true;
1195 }
1196
1197 if (ds_initialized)
1198 return;
1199
1200 ds_initialized = true;
1201
1202 INIT_LIST_HEAD(&delayed_free.pf[0].zapped);
1203 INIT_LIST_HEAD(&delayed_free.pf[1].zapped);
1204
1205 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1206 list_add_tail(&lock_classes[i].lock_entry, &free_lock_classes);
1207 INIT_LIST_HEAD(&lock_classes[i].locks_after);
1208 INIT_LIST_HEAD(&lock_classes[i].locks_before);
1209 }
1210 init_chain_block_buckets();
1211}
1212
1213static inline struct hlist_head *keyhashentry(const struct lock_class_key *key)
1214{
1215 unsigned long hash = hash_long((uintptr_t)key, KEYHASH_BITS);
1216
1217 return lock_keys_hash + hash;
1218}
1219
1220/* Register a dynamically allocated key. */
1221void lockdep_register_key(struct lock_class_key *key)
1222{
1223 struct hlist_head *hash_head;
1224 struct lock_class_key *k;
1225 unsigned long flags;
1226
1227 if (WARN_ON_ONCE(static_obj(key)))
1228 return;
1229 hash_head = keyhashentry(key);
1230
1231 raw_local_irq_save(flags);
1232 if (!graph_lock())
1233 goto restore_irqs;
1234 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1235 if (WARN_ON_ONCE(k == key))
1236 goto out_unlock;
1237 }
1238 hlist_add_head_rcu(&key->hash_entry, hash_head);
1239 nr_dynamic_keys++;
1240out_unlock:
1241 graph_unlock();
1242restore_irqs:
1243 raw_local_irq_restore(flags);
1244}
1245EXPORT_SYMBOL_GPL(lockdep_register_key);
1246
1247/* Check whether a key has been registered as a dynamic key. */
1248static bool is_dynamic_key(const struct lock_class_key *key)
1249{
1250 struct hlist_head *hash_head;
1251 struct lock_class_key *k;
1252 bool found = false;
1253
1254 if (WARN_ON_ONCE(static_obj(key)))
1255 return false;
1256
1257 /*
1258 * If lock debugging is disabled lock_keys_hash[] may contain
1259 * pointers to memory that has already been freed. Avoid triggering
1260 * a use-after-free in that case by returning early.
1261 */
1262 if (!debug_locks)
1263 return true;
1264
1265 hash_head = keyhashentry(key);
1266
1267 rcu_read_lock();
1268 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1269 if (k == key) {
1270 found = true;
1271 break;
1272 }
1273 }
1274 rcu_read_unlock();
1275
1276 return found;
1277}
1278
1279/*
1280 * Register a lock's class in the hash-table, if the class is not present
1281 * yet. Otherwise we look it up. We cache the result in the lock object
1282 * itself, so actual lookup of the hash should be once per lock object.
1283 */
1284static struct lock_class *
1285register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
1286{
1287 struct lockdep_subclass_key *key;
1288 struct hlist_head *hash_head;
1289 struct lock_class *class;
1290 int idx;
1291
1292 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1293
1294 class = look_up_lock_class(lock, subclass);
1295 if (likely(class))
1296 goto out_set_class_cache;
1297
1298 if (!lock->key) {
1299 if (!assign_lock_key(lock))
1300 return NULL;
1301 } else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) {
1302 return NULL;
1303 }
1304
1305 key = lock->key->subkeys + subclass;
1306 hash_head = classhashentry(key);
1307
1308 if (!graph_lock()) {
1309 return NULL;
1310 }
1311 /*
1312 * We have to do the hash-walk again, to avoid races
1313 * with another CPU:
1314 */
1315 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
1316 if (class->key == key)
1317 goto out_unlock_set;
1318 }
1319
1320 init_data_structures_once();
1321
1322 /* Allocate a new lock class and add it to the hash. */
1323 class = list_first_entry_or_null(&free_lock_classes, typeof(*class),
1324 lock_entry);
1325 if (!class) {
1326 if (!debug_locks_off_graph_unlock()) {
1327 return NULL;
1328 }
1329
1330 nbcon_cpu_emergency_enter();
1331 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
1332 dump_stack();
1333 nbcon_cpu_emergency_exit();
1334 return NULL;
1335 }
1336 nr_lock_classes++;
1337 __set_bit(class - lock_classes, lock_classes_in_use);
1338 debug_atomic_inc(nr_unused_locks);
1339 class->key = key;
1340 class->name = lock->name;
1341 class->subclass = subclass;
1342 WARN_ON_ONCE(!list_empty(&class->locks_before));
1343 WARN_ON_ONCE(!list_empty(&class->locks_after));
1344 class->name_version = count_matching_names(class);
1345 class->wait_type_inner = lock->wait_type_inner;
1346 class->wait_type_outer = lock->wait_type_outer;
1347 class->lock_type = lock->lock_type;
1348 /*
1349 * We use RCU's safe list-add method to make
1350 * parallel walking of the hash-list safe:
1351 */
1352 hlist_add_head_rcu(&class->hash_entry, hash_head);
1353 /*
1354 * Remove the class from the free list and add it to the global list
1355 * of classes.
1356 */
1357 list_move_tail(&class->lock_entry, &all_lock_classes);
1358 idx = class - lock_classes;
1359 if (idx > max_lock_class_idx)
1360 max_lock_class_idx = idx;
1361
1362 if (verbose(class)) {
1363 graph_unlock();
1364
1365 nbcon_cpu_emergency_enter();
1366 printk("\nnew class %px: %s", class->key, class->name);
1367 if (class->name_version > 1)
1368 printk(KERN_CONT "#%d", class->name_version);
1369 printk(KERN_CONT "\n");
1370 dump_stack();
1371 nbcon_cpu_emergency_exit();
1372
1373 if (!graph_lock()) {
1374 return NULL;
1375 }
1376 }
1377out_unlock_set:
1378 graph_unlock();
1379
1380out_set_class_cache:
1381 if (!subclass || force)
1382 lock->class_cache[0] = class;
1383 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
1384 lock->class_cache[subclass] = class;
1385
1386 /*
1387 * Hash collision, did we smoke some? We found a class with a matching
1388 * hash but the subclass -- which is hashed in -- didn't match.
1389 */
1390 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
1391 return NULL;
1392
1393 return class;
1394}
1395
1396#ifdef CONFIG_PROVE_LOCKING
1397/*
1398 * Allocate a lockdep entry. (assumes the graph_lock held, returns
1399 * with NULL on failure)
1400 */
1401static struct lock_list *alloc_list_entry(void)
1402{
1403 int idx = find_first_zero_bit(list_entries_in_use,
1404 ARRAY_SIZE(list_entries));
1405
1406 if (idx >= ARRAY_SIZE(list_entries)) {
1407 if (!debug_locks_off_graph_unlock())
1408 return NULL;
1409
1410 nbcon_cpu_emergency_enter();
1411 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
1412 dump_stack();
1413 nbcon_cpu_emergency_exit();
1414 return NULL;
1415 }
1416 nr_list_entries++;
1417 __set_bit(idx, list_entries_in_use);
1418 return list_entries + idx;
1419}
1420
1421/*
1422 * Add a new dependency to the head of the list:
1423 */
1424static int add_lock_to_list(struct lock_class *this,
1425 struct lock_class *links_to, struct list_head *head,
1426 u16 distance, u8 dep,
1427 const struct lock_trace *trace)
1428{
1429 struct lock_list *entry;
1430 /*
1431 * Lock not present yet - get a new dependency struct and
1432 * add it to the list:
1433 */
1434 entry = alloc_list_entry();
1435 if (!entry)
1436 return 0;
1437
1438 entry->class = this;
1439 entry->links_to = links_to;
1440 entry->dep = dep;
1441 entry->distance = distance;
1442 entry->trace = trace;
1443 /*
1444 * Both allocation and removal are done under the graph lock; but
1445 * iteration is under RCU-sched; see look_up_lock_class() and
1446 * lockdep_free_key_range().
1447 */
1448 list_add_tail_rcu(&entry->entry, head);
1449
1450 return 1;
1451}
1452
1453/*
1454 * For good efficiency of modular, we use power of 2
1455 */
1456#define MAX_CIRCULAR_QUEUE_SIZE (1UL << CONFIG_LOCKDEP_CIRCULAR_QUEUE_BITS)
1457#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
1458
1459/*
1460 * The circular_queue and helpers are used to implement graph
1461 * breadth-first search (BFS) algorithm, by which we can determine
1462 * whether there is a path from a lock to another. In deadlock checks,
1463 * a path from the next lock to be acquired to a previous held lock
1464 * indicates that adding the <prev> -> <next> lock dependency will
1465 * produce a circle in the graph. Breadth-first search instead of
1466 * depth-first search is used in order to find the shortest (circular)
1467 * path.
1468 */
1469struct circular_queue {
1470 struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE];
1471 unsigned int front, rear;
1472};
1473
1474static struct circular_queue lock_cq;
1475
1476unsigned int max_bfs_queue_depth;
1477
1478static unsigned int lockdep_dependency_gen_id;
1479
1480static inline void __cq_init(struct circular_queue *cq)
1481{
1482 cq->front = cq->rear = 0;
1483 lockdep_dependency_gen_id++;
1484}
1485
1486static inline int __cq_empty(struct circular_queue *cq)
1487{
1488 return (cq->front == cq->rear);
1489}
1490
1491static inline int __cq_full(struct circular_queue *cq)
1492{
1493 return ((cq->rear + 1) & CQ_MASK) == cq->front;
1494}
1495
1496static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem)
1497{
1498 if (__cq_full(cq))
1499 return -1;
1500
1501 cq->element[cq->rear] = elem;
1502 cq->rear = (cq->rear + 1) & CQ_MASK;
1503 return 0;
1504}
1505
1506/*
1507 * Dequeue an element from the circular_queue, return a lock_list if
1508 * the queue is not empty, or NULL if otherwise.
1509 */
1510static inline struct lock_list * __cq_dequeue(struct circular_queue *cq)
1511{
1512 struct lock_list * lock;
1513
1514 if (__cq_empty(cq))
1515 return NULL;
1516
1517 lock = cq->element[cq->front];
1518 cq->front = (cq->front + 1) & CQ_MASK;
1519
1520 return lock;
1521}
1522
1523static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
1524{
1525 return (cq->rear - cq->front) & CQ_MASK;
1526}
1527
1528static inline void mark_lock_accessed(struct lock_list *lock)
1529{
1530 lock->class->dep_gen_id = lockdep_dependency_gen_id;
1531}
1532
1533static inline void visit_lock_entry(struct lock_list *lock,
1534 struct lock_list *parent)
1535{
1536 lock->parent = parent;
1537}
1538
1539static inline unsigned long lock_accessed(struct lock_list *lock)
1540{
1541 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
1542}
1543
1544static inline struct lock_list *get_lock_parent(struct lock_list *child)
1545{
1546 return child->parent;
1547}
1548
1549static inline int get_lock_depth(struct lock_list *child)
1550{
1551 int depth = 0;
1552 struct lock_list *parent;
1553
1554 while ((parent = get_lock_parent(child))) {
1555 child = parent;
1556 depth++;
1557 }
1558 return depth;
1559}
1560
1561/*
1562 * Return the forward or backward dependency list.
1563 *
1564 * @lock: the lock_list to get its class's dependency list
1565 * @offset: the offset to struct lock_class to determine whether it is
1566 * locks_after or locks_before
1567 */
1568static inline struct list_head *get_dep_list(struct lock_list *lock, int offset)
1569{
1570 void *lock_class = lock->class;
1571
1572 return lock_class + offset;
1573}
1574/*
1575 * Return values of a bfs search:
1576 *
1577 * BFS_E* indicates an error
1578 * BFS_R* indicates a result (match or not)
1579 *
1580 * BFS_EINVALIDNODE: Find a invalid node in the graph.
1581 *
1582 * BFS_EQUEUEFULL: The queue is full while doing the bfs.
1583 *
1584 * BFS_RMATCH: Find the matched node in the graph, and put that node into
1585 * *@target_entry.
1586 *
1587 * BFS_RNOMATCH: Haven't found the matched node and keep *@target_entry
1588 * _unchanged_.
1589 */
1590enum bfs_result {
1591 BFS_EINVALIDNODE = -2,
1592 BFS_EQUEUEFULL = -1,
1593 BFS_RMATCH = 0,
1594 BFS_RNOMATCH = 1,
1595};
1596
1597/*
1598 * bfs_result < 0 means error
1599 */
1600static inline bool bfs_error(enum bfs_result res)
1601{
1602 return res < 0;
1603}
1604
1605/*
1606 * DEP_*_BIT in lock_list::dep
1607 *
1608 * For dependency @prev -> @next:
1609 *
1610 * SR: @prev is shared reader (->read != 0) and @next is recursive reader
1611 * (->read == 2)
1612 * ER: @prev is exclusive locker (->read == 0) and @next is recursive reader
1613 * SN: @prev is shared reader and @next is non-recursive locker (->read != 2)
1614 * EN: @prev is exclusive locker and @next is non-recursive locker
1615 *
1616 * Note that we define the value of DEP_*_BITs so that:
1617 * bit0 is prev->read == 0
1618 * bit1 is next->read != 2
1619 */
1620#define DEP_SR_BIT (0 + (0 << 1)) /* 0 */
1621#define DEP_ER_BIT (1 + (0 << 1)) /* 1 */
1622#define DEP_SN_BIT (0 + (1 << 1)) /* 2 */
1623#define DEP_EN_BIT (1 + (1 << 1)) /* 3 */
1624
1625#define DEP_SR_MASK (1U << (DEP_SR_BIT))
1626#define DEP_ER_MASK (1U << (DEP_ER_BIT))
1627#define DEP_SN_MASK (1U << (DEP_SN_BIT))
1628#define DEP_EN_MASK (1U << (DEP_EN_BIT))
1629
1630static inline unsigned int
1631__calc_dep_bit(struct held_lock *prev, struct held_lock *next)
1632{
1633 return (prev->read == 0) + ((next->read != 2) << 1);
1634}
1635
1636static inline u8 calc_dep(struct held_lock *prev, struct held_lock *next)
1637{
1638 return 1U << __calc_dep_bit(prev, next);
1639}
1640
1641/*
1642 * calculate the dep_bit for backwards edges. We care about whether @prev is
1643 * shared and whether @next is recursive.
1644 */
1645static inline unsigned int
1646__calc_dep_bitb(struct held_lock *prev, struct held_lock *next)
1647{
1648 return (next->read != 2) + ((prev->read == 0) << 1);
1649}
1650
1651static inline u8 calc_depb(struct held_lock *prev, struct held_lock *next)
1652{
1653 return 1U << __calc_dep_bitb(prev, next);
1654}
1655
1656/*
1657 * Initialize a lock_list entry @lock belonging to @class as the root for a BFS
1658 * search.
1659 */
1660static inline void __bfs_init_root(struct lock_list *lock,
1661 struct lock_class *class)
1662{
1663 lock->class = class;
1664 lock->parent = NULL;
1665 lock->only_xr = 0;
1666}
1667
1668/*
1669 * Initialize a lock_list entry @lock based on a lock acquisition @hlock as the
1670 * root for a BFS search.
1671 *
1672 * ->only_xr of the initial lock node is set to @hlock->read == 2, to make sure
1673 * that <prev> -> @hlock and @hlock -> <whatever __bfs() found> is not -(*R)->
1674 * and -(S*)->.
1675 */
1676static inline void bfs_init_root(struct lock_list *lock,
1677 struct held_lock *hlock)
1678{
1679 __bfs_init_root(lock, hlock_class(hlock));
1680 lock->only_xr = (hlock->read == 2);
1681}
1682
1683/*
1684 * Similar to bfs_init_root() but initialize the root for backwards BFS.
1685 *
1686 * ->only_xr of the initial lock node is set to @hlock->read != 0, to make sure
1687 * that <next> -> @hlock and @hlock -> <whatever backwards BFS found> is not
1688 * -(*S)-> and -(R*)-> (reverse order of -(*R)-> and -(S*)->).
1689 */
1690static inline void bfs_init_rootb(struct lock_list *lock,
1691 struct held_lock *hlock)
1692{
1693 __bfs_init_root(lock, hlock_class(hlock));
1694 lock->only_xr = (hlock->read != 0);
1695}
1696
1697static inline struct lock_list *__bfs_next(struct lock_list *lock, int offset)
1698{
1699 if (!lock || !lock->parent)
1700 return NULL;
1701
1702 return list_next_or_null_rcu(get_dep_list(lock->parent, offset),
1703 &lock->entry, struct lock_list, entry);
1704}
1705
1706/*
1707 * Breadth-First Search to find a strong path in the dependency graph.
1708 *
1709 * @source_entry: the source of the path we are searching for.
1710 * @data: data used for the second parameter of @match function
1711 * @match: match function for the search
1712 * @target_entry: pointer to the target of a matched path
1713 * @offset: the offset to struct lock_class to determine whether it is
1714 * locks_after or locks_before
1715 *
1716 * We may have multiple edges (considering different kinds of dependencies,
1717 * e.g. ER and SN) between two nodes in the dependency graph. But
1718 * only the strong dependency path in the graph is relevant to deadlocks. A
1719 * strong dependency path is a dependency path that doesn't have two adjacent
1720 * dependencies as -(*R)-> -(S*)->, please see:
1721 *
1722 * Documentation/locking/lockdep-design.rst
1723 *
1724 * for more explanation of the definition of strong dependency paths
1725 *
1726 * In __bfs(), we only traverse in the strong dependency path:
1727 *
1728 * In lock_list::only_xr, we record whether the previous dependency only
1729 * has -(*R)-> in the search, and if it does (prev only has -(*R)->), we
1730 * filter out any -(S*)-> in the current dependency and after that, the
1731 * ->only_xr is set according to whether we only have -(*R)-> left.
1732 */
1733static enum bfs_result __bfs(struct lock_list *source_entry,
1734 void *data,
1735 bool (*match)(struct lock_list *entry, void *data),
1736 bool (*skip)(struct lock_list *entry, void *data),
1737 struct lock_list **target_entry,
1738 int offset)
1739{
1740 struct circular_queue *cq = &lock_cq;
1741 struct lock_list *lock = NULL;
1742 struct lock_list *entry;
1743 struct list_head *head;
1744 unsigned int cq_depth;
1745 bool first;
1746
1747 lockdep_assert_locked();
1748
1749 __cq_init(cq);
1750 __cq_enqueue(cq, source_entry);
1751
1752 while ((lock = __bfs_next(lock, offset)) || (lock = __cq_dequeue(cq))) {
1753 if (!lock->class)
1754 return BFS_EINVALIDNODE;
1755
1756 /*
1757 * Step 1: check whether we already finish on this one.
1758 *
1759 * If we have visited all the dependencies from this @lock to
1760 * others (iow, if we have visited all lock_list entries in
1761 * @lock->class->locks_{after,before}) we skip, otherwise go
1762 * and visit all the dependencies in the list and mark this
1763 * list accessed.
1764 */
1765 if (lock_accessed(lock))
1766 continue;
1767 else
1768 mark_lock_accessed(lock);
1769
1770 /*
1771 * Step 2: check whether prev dependency and this form a strong
1772 * dependency path.
1773 */
1774 if (lock->parent) { /* Parent exists, check prev dependency */
1775 u8 dep = lock->dep;
1776 bool prev_only_xr = lock->parent->only_xr;
1777
1778 /*
1779 * Mask out all -(S*)-> if we only have *R in previous
1780 * step, because -(*R)-> -(S*)-> don't make up a strong
1781 * dependency.
1782 */
1783 if (prev_only_xr)
1784 dep &= ~(DEP_SR_MASK | DEP_SN_MASK);
1785
1786 /* If nothing left, we skip */
1787 if (!dep)
1788 continue;
1789
1790 /* If there are only -(*R)-> left, set that for the next step */
1791 lock->only_xr = !(dep & (DEP_SN_MASK | DEP_EN_MASK));
1792 }
1793
1794 /*
1795 * Step 3: we haven't visited this and there is a strong
1796 * dependency path to this, so check with @match.
1797 * If @skip is provide and returns true, we skip this
1798 * lock (and any path this lock is in).
1799 */
1800 if (skip && skip(lock, data))
1801 continue;
1802
1803 if (match(lock, data)) {
1804 *target_entry = lock;
1805 return BFS_RMATCH;
1806 }
1807
1808 /*
1809 * Step 4: if not match, expand the path by adding the
1810 * forward or backwards dependencies in the search
1811 *
1812 */
1813 first = true;
1814 head = get_dep_list(lock, offset);
1815 list_for_each_entry_rcu(entry, head, entry) {
1816 visit_lock_entry(entry, lock);
1817
1818 /*
1819 * Note we only enqueue the first of the list into the
1820 * queue, because we can always find a sibling
1821 * dependency from one (see __bfs_next()), as a result
1822 * the space of queue is saved.
1823 */
1824 if (!first)
1825 continue;
1826
1827 first = false;
1828
1829 if (__cq_enqueue(cq, entry))
1830 return BFS_EQUEUEFULL;
1831
1832 cq_depth = __cq_get_elem_count(cq);
1833 if (max_bfs_queue_depth < cq_depth)
1834 max_bfs_queue_depth = cq_depth;
1835 }
1836 }
1837
1838 return BFS_RNOMATCH;
1839}
1840
1841static inline enum bfs_result
1842__bfs_forwards(struct lock_list *src_entry,
1843 void *data,
1844 bool (*match)(struct lock_list *entry, void *data),
1845 bool (*skip)(struct lock_list *entry, void *data),
1846 struct lock_list **target_entry)
1847{
1848 return __bfs(src_entry, data, match, skip, target_entry,
1849 offsetof(struct lock_class, locks_after));
1850
1851}
1852
1853static inline enum bfs_result
1854__bfs_backwards(struct lock_list *src_entry,
1855 void *data,
1856 bool (*match)(struct lock_list *entry, void *data),
1857 bool (*skip)(struct lock_list *entry, void *data),
1858 struct lock_list **target_entry)
1859{
1860 return __bfs(src_entry, data, match, skip, target_entry,
1861 offsetof(struct lock_class, locks_before));
1862
1863}
1864
1865static void print_lock_trace(const struct lock_trace *trace,
1866 unsigned int spaces)
1867{
1868 stack_trace_print(trace->entries, trace->nr_entries, spaces);
1869}
1870
1871/*
1872 * Print a dependency chain entry (this is only done when a deadlock
1873 * has been detected):
1874 */
1875static noinline void
1876print_circular_bug_entry(struct lock_list *target, int depth)
1877{
1878 if (debug_locks_silent)
1879 return;
1880 printk("\n-> #%u", depth);
1881 print_lock_name(NULL, target->class);
1882 printk(KERN_CONT ":\n");
1883 print_lock_trace(target->trace, 6);
1884}
1885
1886static void
1887print_circular_lock_scenario(struct held_lock *src,
1888 struct held_lock *tgt,
1889 struct lock_list *prt)
1890{
1891 struct lock_class *source = hlock_class(src);
1892 struct lock_class *target = hlock_class(tgt);
1893 struct lock_class *parent = prt->class;
1894 int src_read = src->read;
1895 int tgt_read = tgt->read;
1896
1897 /*
1898 * A direct locking problem where unsafe_class lock is taken
1899 * directly by safe_class lock, then all we need to show
1900 * is the deadlock scenario, as it is obvious that the
1901 * unsafe lock is taken under the safe lock.
1902 *
1903 * But if there is a chain instead, where the safe lock takes
1904 * an intermediate lock (middle_class) where this lock is
1905 * not the same as the safe lock, then the lock chain is
1906 * used to describe the problem. Otherwise we would need
1907 * to show a different CPU case for each link in the chain
1908 * from the safe_class lock to the unsafe_class lock.
1909 */
1910 if (parent != source) {
1911 printk("Chain exists of:\n ");
1912 __print_lock_name(src, source);
1913 printk(KERN_CONT " --> ");
1914 __print_lock_name(NULL, parent);
1915 printk(KERN_CONT " --> ");
1916 __print_lock_name(tgt, target);
1917 printk(KERN_CONT "\n\n");
1918 }
1919
1920 printk(" Possible unsafe locking scenario:\n\n");
1921 printk(" CPU0 CPU1\n");
1922 printk(" ---- ----\n");
1923 if (tgt_read != 0)
1924 printk(" rlock(");
1925 else
1926 printk(" lock(");
1927 __print_lock_name(tgt, target);
1928 printk(KERN_CONT ");\n");
1929 printk(" lock(");
1930 __print_lock_name(NULL, parent);
1931 printk(KERN_CONT ");\n");
1932 printk(" lock(");
1933 __print_lock_name(tgt, target);
1934 printk(KERN_CONT ");\n");
1935 if (src_read != 0)
1936 printk(" rlock(");
1937 else if (src->sync)
1938 printk(" sync(");
1939 else
1940 printk(" lock(");
1941 __print_lock_name(src, source);
1942 printk(KERN_CONT ");\n");
1943 printk("\n *** DEADLOCK ***\n\n");
1944}
1945
1946/*
1947 * When a circular dependency is detected, print the
1948 * header first:
1949 */
1950static noinline void
1951print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1952 struct held_lock *check_src,
1953 struct held_lock *check_tgt)
1954{
1955 struct task_struct *curr = current;
1956
1957 if (debug_locks_silent)
1958 return;
1959
1960 pr_warn("\n");
1961 pr_warn("======================================================\n");
1962 pr_warn("WARNING: possible circular locking dependency detected\n");
1963 print_kernel_ident();
1964 pr_warn("------------------------------------------------------\n");
1965 pr_warn("%s/%d is trying to acquire lock:\n",
1966 curr->comm, task_pid_nr(curr));
1967 print_lock(check_src);
1968
1969 pr_warn("\nbut task is already holding lock:\n");
1970
1971 print_lock(check_tgt);
1972 pr_warn("\nwhich lock already depends on the new lock.\n\n");
1973 pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1974
1975 print_circular_bug_entry(entry, depth);
1976}
1977
1978/*
1979 * We are about to add B -> A into the dependency graph, and in __bfs() a
1980 * strong dependency path A -> .. -> B is found: hlock_class equals
1981 * entry->class.
1982 *
1983 * We will have a deadlock case (conflict) if A -> .. -> B -> A is a strong
1984 * dependency cycle, that means:
1985 *
1986 * Either
1987 *
1988 * a) B -> A is -(E*)->
1989 *
1990 * or
1991 *
1992 * b) A -> .. -> B is -(*N)-> (i.e. A -> .. -(*N)-> B)
1993 *
1994 * as then we don't have -(*R)-> -(S*)-> in the cycle.
1995 */
1996static inline bool hlock_conflict(struct lock_list *entry, void *data)
1997{
1998 struct held_lock *hlock = (struct held_lock *)data;
1999
2000 return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */
2001 (hlock->read == 0 || /* B -> A is -(E*)-> */
2002 !entry->only_xr); /* A -> .. -> B is -(*N)-> */
2003}
2004
2005static noinline void print_circular_bug(struct lock_list *this,
2006 struct lock_list *target,
2007 struct held_lock *check_src,
2008 struct held_lock *check_tgt)
2009{
2010 struct task_struct *curr = current;
2011 struct lock_list *parent;
2012 struct lock_list *first_parent;
2013 int depth;
2014
2015 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2016 return;
2017
2018 this->trace = save_trace();
2019 if (!this->trace)
2020 return;
2021
2022 depth = get_lock_depth(target);
2023
2024 nbcon_cpu_emergency_enter();
2025
2026 print_circular_bug_header(target, depth, check_src, check_tgt);
2027
2028 parent = get_lock_parent(target);
2029 first_parent = parent;
2030
2031 while (parent) {
2032 print_circular_bug_entry(parent, --depth);
2033 parent = get_lock_parent(parent);
2034 }
2035
2036 printk("\nother info that might help us debug this:\n\n");
2037 print_circular_lock_scenario(check_src, check_tgt,
2038 first_parent);
2039
2040 lockdep_print_held_locks(curr);
2041
2042 printk("\nstack backtrace:\n");
2043 dump_stack();
2044
2045 nbcon_cpu_emergency_exit();
2046}
2047
2048static noinline void print_bfs_bug(int ret)
2049{
2050 if (!debug_locks_off_graph_unlock())
2051 return;
2052
2053 /*
2054 * Breadth-first-search failed, graph got corrupted?
2055 */
2056 if (ret == BFS_EQUEUEFULL)
2057 pr_warn("Increase LOCKDEP_CIRCULAR_QUEUE_BITS to avoid this warning:\n");
2058
2059 WARN(1, "lockdep bfs error:%d\n", ret);
2060}
2061
2062static bool noop_count(struct lock_list *entry, void *data)
2063{
2064 (*(unsigned long *)data)++;
2065 return false;
2066}
2067
2068static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
2069{
2070 unsigned long count = 0;
2071 struct lock_list *target_entry;
2072
2073 __bfs_forwards(this, (void *)&count, noop_count, NULL, &target_entry);
2074
2075 return count;
2076}
2077unsigned long lockdep_count_forward_deps(struct lock_class *class)
2078{
2079 unsigned long ret, flags;
2080 struct lock_list this;
2081
2082 __bfs_init_root(&this, class);
2083
2084 raw_local_irq_save(flags);
2085 lockdep_lock();
2086 ret = __lockdep_count_forward_deps(&this);
2087 lockdep_unlock();
2088 raw_local_irq_restore(flags);
2089
2090 return ret;
2091}
2092
2093static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
2094{
2095 unsigned long count = 0;
2096 struct lock_list *target_entry;
2097
2098 __bfs_backwards(this, (void *)&count, noop_count, NULL, &target_entry);
2099
2100 return count;
2101}
2102
2103unsigned long lockdep_count_backward_deps(struct lock_class *class)
2104{
2105 unsigned long ret, flags;
2106 struct lock_list this;
2107
2108 __bfs_init_root(&this, class);
2109
2110 raw_local_irq_save(flags);
2111 lockdep_lock();
2112 ret = __lockdep_count_backward_deps(&this);
2113 lockdep_unlock();
2114 raw_local_irq_restore(flags);
2115
2116 return ret;
2117}
2118
2119/*
2120 * Check that the dependency graph starting at <src> can lead to
2121 * <target> or not.
2122 */
2123static noinline enum bfs_result
2124check_path(struct held_lock *target, struct lock_list *src_entry,
2125 bool (*match)(struct lock_list *entry, void *data),
2126 bool (*skip)(struct lock_list *entry, void *data),
2127 struct lock_list **target_entry)
2128{
2129 enum bfs_result ret;
2130
2131 ret = __bfs_forwards(src_entry, target, match, skip, target_entry);
2132
2133 if (unlikely(bfs_error(ret)))
2134 print_bfs_bug(ret);
2135
2136 return ret;
2137}
2138
2139static void print_deadlock_bug(struct task_struct *, struct held_lock *, struct held_lock *);
2140
2141/*
2142 * Prove that the dependency graph starting at <src> can not
2143 * lead to <target>. If it can, there is a circle when adding
2144 * <target> -> <src> dependency.
2145 *
2146 * Print an error and return BFS_RMATCH if it does.
2147 */
2148static noinline enum bfs_result
2149check_noncircular(struct held_lock *src, struct held_lock *target,
2150 struct lock_trace **const trace)
2151{
2152 enum bfs_result ret;
2153 struct lock_list *target_entry;
2154 struct lock_list src_entry;
2155
2156 bfs_init_root(&src_entry, src);
2157
2158 debug_atomic_inc(nr_cyclic_checks);
2159
2160 ret = check_path(target, &src_entry, hlock_conflict, NULL, &target_entry);
2161
2162 if (unlikely(ret == BFS_RMATCH)) {
2163 if (!*trace) {
2164 /*
2165 * If save_trace fails here, the printing might
2166 * trigger a WARN but because of the !nr_entries it
2167 * should not do bad things.
2168 */
2169 *trace = save_trace();
2170 }
2171
2172 if (src->class_idx == target->class_idx)
2173 print_deadlock_bug(current, src, target);
2174 else
2175 print_circular_bug(&src_entry, target_entry, src, target);
2176 }
2177
2178 return ret;
2179}
2180
2181#ifdef CONFIG_TRACE_IRQFLAGS
2182
2183/*
2184 * Forwards and backwards subgraph searching, for the purposes of
2185 * proving that two subgraphs can be connected by a new dependency
2186 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
2187 *
2188 * A irq safe->unsafe deadlock happens with the following conditions:
2189 *
2190 * 1) We have a strong dependency path A -> ... -> B
2191 *
2192 * 2) and we have ENABLED_IRQ usage of B and USED_IN_IRQ usage of A, therefore
2193 * irq can create a new dependency B -> A (consider the case that a holder
2194 * of B gets interrupted by an irq whose handler will try to acquire A).
2195 *
2196 * 3) the dependency circle A -> ... -> B -> A we get from 1) and 2) is a
2197 * strong circle:
2198 *
2199 * For the usage bits of B:
2200 * a) if A -> B is -(*N)->, then B -> A could be any type, so any
2201 * ENABLED_IRQ usage suffices.
2202 * b) if A -> B is -(*R)->, then B -> A must be -(E*)->, so only
2203 * ENABLED_IRQ_*_READ usage suffices.
2204 *
2205 * For the usage bits of A:
2206 * c) if A -> B is -(E*)->, then B -> A could be any type, so any
2207 * USED_IN_IRQ usage suffices.
2208 * d) if A -> B is -(S*)->, then B -> A must be -(*N)->, so only
2209 * USED_IN_IRQ_*_READ usage suffices.
2210 */
2211
2212/*
2213 * There is a strong dependency path in the dependency graph: A -> B, and now
2214 * we need to decide which usage bit of A should be accumulated to detect
2215 * safe->unsafe bugs.
2216 *
2217 * Note that usage_accumulate() is used in backwards search, so ->only_xr
2218 * stands for whether A -> B only has -(S*)-> (in this case ->only_xr is true).
2219 *
2220 * As above, if only_xr is false, which means A -> B has -(E*)-> dependency
2221 * path, any usage of A should be considered. Otherwise, we should only
2222 * consider _READ usage.
2223 */
2224static inline bool usage_accumulate(struct lock_list *entry, void *mask)
2225{
2226 if (!entry->only_xr)
2227 *(unsigned long *)mask |= entry->class->usage_mask;
2228 else /* Mask out _READ usage bits */
2229 *(unsigned long *)mask |= (entry->class->usage_mask & LOCKF_IRQ);
2230
2231 return false;
2232}
2233
2234/*
2235 * There is a strong dependency path in the dependency graph: A -> B, and now
2236 * we need to decide which usage bit of B conflicts with the usage bits of A,
2237 * i.e. which usage bit of B may introduce safe->unsafe deadlocks.
2238 *
2239 * As above, if only_xr is false, which means A -> B has -(*N)-> dependency
2240 * path, any usage of B should be considered. Otherwise, we should only
2241 * consider _READ usage.
2242 */
2243static inline bool usage_match(struct lock_list *entry, void *mask)
2244{
2245 if (!entry->only_xr)
2246 return !!(entry->class->usage_mask & *(unsigned long *)mask);
2247 else /* Mask out _READ usage bits */
2248 return !!((entry->class->usage_mask & LOCKF_IRQ) & *(unsigned long *)mask);
2249}
2250
2251static inline bool usage_skip(struct lock_list *entry, void *mask)
2252{
2253 if (entry->class->lock_type == LD_LOCK_NORMAL)
2254 return false;
2255
2256 /*
2257 * Skip local_lock() for irq inversion detection.
2258 *
2259 * For !RT, local_lock() is not a real lock, so it won't carry any
2260 * dependency.
2261 *
2262 * For RT, an irq inversion happens when we have lock A and B, and on
2263 * some CPU we can have:
2264 *
2265 * lock(A);
2266 * <interrupted>
2267 * lock(B);
2268 *
2269 * where lock(B) cannot sleep, and we have a dependency B -> ... -> A.
2270 *
2271 * Now we prove local_lock() cannot exist in that dependency. First we
2272 * have the observation for any lock chain L1 -> ... -> Ln, for any
2273 * 1 <= i <= n, Li.inner_wait_type <= L1.inner_wait_type, otherwise
2274 * wait context check will complain. And since B is not a sleep lock,
2275 * therefore B.inner_wait_type >= 2, and since the inner_wait_type of
2276 * local_lock() is 3, which is greater than 2, therefore there is no
2277 * way the local_lock() exists in the dependency B -> ... -> A.
2278 *
2279 * As a result, we will skip local_lock(), when we search for irq
2280 * inversion bugs.
2281 */
2282 if (entry->class->lock_type == LD_LOCK_PERCPU &&
2283 DEBUG_LOCKS_WARN_ON(entry->class->wait_type_inner < LD_WAIT_CONFIG))
2284 return false;
2285
2286 /*
2287 * Skip WAIT_OVERRIDE for irq inversion detection -- it's not actually
2288 * a lock and only used to override the wait_type.
2289 */
2290
2291 return true;
2292}
2293
2294/*
2295 * Find a node in the forwards-direction dependency sub-graph starting
2296 * at @root->class that matches @bit.
2297 *
2298 * Return BFS_MATCH if such a node exists in the subgraph, and put that node
2299 * into *@target_entry.
2300 */
2301static enum bfs_result
2302find_usage_forwards(struct lock_list *root, unsigned long usage_mask,
2303 struct lock_list **target_entry)
2304{
2305 enum bfs_result result;
2306
2307 debug_atomic_inc(nr_find_usage_forwards_checks);
2308
2309 result = __bfs_forwards(root, &usage_mask, usage_match, usage_skip, target_entry);
2310
2311 return result;
2312}
2313
2314/*
2315 * Find a node in the backwards-direction dependency sub-graph starting
2316 * at @root->class that matches @bit.
2317 */
2318static enum bfs_result
2319find_usage_backwards(struct lock_list *root, unsigned long usage_mask,
2320 struct lock_list **target_entry)
2321{
2322 enum bfs_result result;
2323
2324 debug_atomic_inc(nr_find_usage_backwards_checks);
2325
2326 result = __bfs_backwards(root, &usage_mask, usage_match, usage_skip, target_entry);
2327
2328 return result;
2329}
2330
2331static void print_lock_class_header(struct lock_class *class, int depth)
2332{
2333 int bit;
2334
2335 printk("%*s->", depth, "");
2336 print_lock_name(NULL, class);
2337#ifdef CONFIG_DEBUG_LOCKDEP
2338 printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
2339#endif
2340 printk(KERN_CONT " {\n");
2341
2342 for (bit = 0; bit < LOCK_TRACE_STATES; bit++) {
2343 if (class->usage_mask & (1 << bit)) {
2344 int len = depth;
2345
2346 len += printk("%*s %s", depth, "", usage_str[bit]);
2347 len += printk(KERN_CONT " at:\n");
2348 print_lock_trace(class->usage_traces[bit], len);
2349 }
2350 }
2351 printk("%*s }\n", depth, "");
2352
2353 printk("%*s ... key at: [<%px>] %pS\n",
2354 depth, "", class->key, class->key);
2355}
2356
2357/*
2358 * Dependency path printing:
2359 *
2360 * After BFS we get a lock dependency path (linked via ->parent of lock_list),
2361 * printing out each lock in the dependency path will help on understanding how
2362 * the deadlock could happen. Here are some details about dependency path
2363 * printing:
2364 *
2365 * 1) A lock_list can be either forwards or backwards for a lock dependency,
2366 * for a lock dependency A -> B, there are two lock_lists:
2367 *
2368 * a) lock_list in the ->locks_after list of A, whose ->class is B and
2369 * ->links_to is A. In this case, we can say the lock_list is
2370 * "A -> B" (forwards case).
2371 *
2372 * b) lock_list in the ->locks_before list of B, whose ->class is A
2373 * and ->links_to is B. In this case, we can say the lock_list is
2374 * "B <- A" (bacwards case).
2375 *
2376 * The ->trace of both a) and b) point to the call trace where B was
2377 * acquired with A held.
2378 *
2379 * 2) A "helper" lock_list is introduced during BFS, this lock_list doesn't
2380 * represent a certain lock dependency, it only provides an initial entry
2381 * for BFS. For example, BFS may introduce a "helper" lock_list whose
2382 * ->class is A, as a result BFS will search all dependencies starting with
2383 * A, e.g. A -> B or A -> C.
2384 *
2385 * The notation of a forwards helper lock_list is like "-> A", which means
2386 * we should search the forwards dependencies starting with "A", e.g A -> B
2387 * or A -> C.
2388 *
2389 * The notation of a bacwards helper lock_list is like "<- B", which means
2390 * we should search the backwards dependencies ending with "B", e.g.
2391 * B <- A or B <- C.
2392 */
2393
2394/*
2395 * printk the shortest lock dependencies from @root to @leaf in reverse order.
2396 *
2397 * We have a lock dependency path as follow:
2398 *
2399 * @root @leaf
2400 * | |
2401 * V V
2402 * ->parent ->parent
2403 * | lock_list | <--------- | lock_list | ... | lock_list | <--------- | lock_list |
2404 * | -> L1 | | L1 -> L2 | ... |Ln-2 -> Ln-1| | Ln-1 -> Ln|
2405 *
2406 * , so it's natural that we start from @leaf and print every ->class and
2407 * ->trace until we reach the @root.
2408 */
2409static void __used
2410print_shortest_lock_dependencies(struct lock_list *leaf,
2411 struct lock_list *root)
2412{
2413 struct lock_list *entry = leaf;
2414 int depth;
2415
2416 /*compute depth from generated tree by BFS*/
2417 depth = get_lock_depth(leaf);
2418
2419 do {
2420 print_lock_class_header(entry->class, depth);
2421 printk("%*s ... acquired at:\n", depth, "");
2422 print_lock_trace(entry->trace, 2);
2423 printk("\n");
2424
2425 if (depth == 0 && (entry != root)) {
2426 printk("lockdep:%s bad path found in chain graph\n", __func__);
2427 break;
2428 }
2429
2430 entry = get_lock_parent(entry);
2431 depth--;
2432 } while (entry && (depth >= 0));
2433}
2434
2435/*
2436 * printk the shortest lock dependencies from @leaf to @root.
2437 *
2438 * We have a lock dependency path (from a backwards search) as follow:
2439 *
2440 * @leaf @root
2441 * | |
2442 * V V
2443 * ->parent ->parent
2444 * | lock_list | ---------> | lock_list | ... | lock_list | ---------> | lock_list |
2445 * | L2 <- L1 | | L3 <- L2 | ... | Ln <- Ln-1 | | <- Ln |
2446 *
2447 * , so when we iterate from @leaf to @root, we actually print the lock
2448 * dependency path L1 -> L2 -> .. -> Ln in the non-reverse order.
2449 *
2450 * Another thing to notice here is that ->class of L2 <- L1 is L1, while the
2451 * ->trace of L2 <- L1 is the call trace of L2, in fact we don't have the call
2452 * trace of L1 in the dependency path, which is alright, because most of the
2453 * time we can figure out where L1 is held from the call trace of L2.
2454 */
2455static void __used
2456print_shortest_lock_dependencies_backwards(struct lock_list *leaf,
2457 struct lock_list *root)
2458{
2459 struct lock_list *entry = leaf;
2460 const struct lock_trace *trace = NULL;
2461 int depth;
2462
2463 /*compute depth from generated tree by BFS*/
2464 depth = get_lock_depth(leaf);
2465
2466 do {
2467 print_lock_class_header(entry->class, depth);
2468 if (trace) {
2469 printk("%*s ... acquired at:\n", depth, "");
2470 print_lock_trace(trace, 2);
2471 printk("\n");
2472 }
2473
2474 /*
2475 * Record the pointer to the trace for the next lock_list
2476 * entry, see the comments for the function.
2477 */
2478 trace = entry->trace;
2479
2480 if (depth == 0 && (entry != root)) {
2481 printk("lockdep:%s bad path found in chain graph\n", __func__);
2482 break;
2483 }
2484
2485 entry = get_lock_parent(entry);
2486 depth--;
2487 } while (entry && (depth >= 0));
2488}
2489
2490static void
2491print_irq_lock_scenario(struct lock_list *safe_entry,
2492 struct lock_list *unsafe_entry,
2493 struct lock_class *prev_class,
2494 struct lock_class *next_class)
2495{
2496 struct lock_class *safe_class = safe_entry->class;
2497 struct lock_class *unsafe_class = unsafe_entry->class;
2498 struct lock_class *middle_class = prev_class;
2499
2500 if (middle_class == safe_class)
2501 middle_class = next_class;
2502
2503 /*
2504 * A direct locking problem where unsafe_class lock is taken
2505 * directly by safe_class lock, then all we need to show
2506 * is the deadlock scenario, as it is obvious that the
2507 * unsafe lock is taken under the safe lock.
2508 *
2509 * But if there is a chain instead, where the safe lock takes
2510 * an intermediate lock (middle_class) where this lock is
2511 * not the same as the safe lock, then the lock chain is
2512 * used to describe the problem. Otherwise we would need
2513 * to show a different CPU case for each link in the chain
2514 * from the safe_class lock to the unsafe_class lock.
2515 */
2516 if (middle_class != unsafe_class) {
2517 printk("Chain exists of:\n ");
2518 __print_lock_name(NULL, safe_class);
2519 printk(KERN_CONT " --> ");
2520 __print_lock_name(NULL, middle_class);
2521 printk(KERN_CONT " --> ");
2522 __print_lock_name(NULL, unsafe_class);
2523 printk(KERN_CONT "\n\n");
2524 }
2525
2526 printk(" Possible interrupt unsafe locking scenario:\n\n");
2527 printk(" CPU0 CPU1\n");
2528 printk(" ---- ----\n");
2529 printk(" lock(");
2530 __print_lock_name(NULL, unsafe_class);
2531 printk(KERN_CONT ");\n");
2532 printk(" local_irq_disable();\n");
2533 printk(" lock(");
2534 __print_lock_name(NULL, safe_class);
2535 printk(KERN_CONT ");\n");
2536 printk(" lock(");
2537 __print_lock_name(NULL, middle_class);
2538 printk(KERN_CONT ");\n");
2539 printk(" <Interrupt>\n");
2540 printk(" lock(");
2541 __print_lock_name(NULL, safe_class);
2542 printk(KERN_CONT ");\n");
2543 printk("\n *** DEADLOCK ***\n\n");
2544}
2545
2546static void
2547print_bad_irq_dependency(struct task_struct *curr,
2548 struct lock_list *prev_root,
2549 struct lock_list *next_root,
2550 struct lock_list *backwards_entry,
2551 struct lock_list *forwards_entry,
2552 struct held_lock *prev,
2553 struct held_lock *next,
2554 enum lock_usage_bit bit1,
2555 enum lock_usage_bit bit2,
2556 const char *irqclass)
2557{
2558 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2559 return;
2560
2561 nbcon_cpu_emergency_enter();
2562
2563 pr_warn("\n");
2564 pr_warn("=====================================================\n");
2565 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
2566 irqclass, irqclass);
2567 print_kernel_ident();
2568 pr_warn("-----------------------------------------------------\n");
2569 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
2570 curr->comm, task_pid_nr(curr),
2571 lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
2572 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
2573 lockdep_hardirqs_enabled(),
2574 curr->softirqs_enabled);
2575 print_lock(next);
2576
2577 pr_warn("\nand this task is already holding:\n");
2578 print_lock(prev);
2579 pr_warn("which would create a new lock dependency:\n");
2580 print_lock_name(prev, hlock_class(prev));
2581 pr_cont(" ->");
2582 print_lock_name(next, hlock_class(next));
2583 pr_cont("\n");
2584
2585 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
2586 irqclass);
2587 print_lock_name(NULL, backwards_entry->class);
2588 pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
2589
2590 print_lock_trace(backwards_entry->class->usage_traces[bit1], 1);
2591
2592 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
2593 print_lock_name(NULL, forwards_entry->class);
2594 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
2595 pr_warn("...");
2596
2597 print_lock_trace(forwards_entry->class->usage_traces[bit2], 1);
2598
2599 pr_warn("\nother info that might help us debug this:\n\n");
2600 print_irq_lock_scenario(backwards_entry, forwards_entry,
2601 hlock_class(prev), hlock_class(next));
2602
2603 lockdep_print_held_locks(curr);
2604
2605 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
2606 print_shortest_lock_dependencies_backwards(backwards_entry, prev_root);
2607
2608 pr_warn("\nthe dependencies between the lock to be acquired");
2609 pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
2610 next_root->trace = save_trace();
2611 if (!next_root->trace)
2612 goto out;
2613 print_shortest_lock_dependencies(forwards_entry, next_root);
2614
2615 pr_warn("\nstack backtrace:\n");
2616 dump_stack();
2617out:
2618 nbcon_cpu_emergency_exit();
2619}
2620
2621static const char *state_names[] = {
2622#define LOCKDEP_STATE(__STATE) \
2623 __stringify(__STATE),
2624#include "lockdep_states.h"
2625#undef LOCKDEP_STATE
2626};
2627
2628static const char *state_rnames[] = {
2629#define LOCKDEP_STATE(__STATE) \
2630 __stringify(__STATE)"-READ",
2631#include "lockdep_states.h"
2632#undef LOCKDEP_STATE
2633};
2634
2635static inline const char *state_name(enum lock_usage_bit bit)
2636{
2637 if (bit & LOCK_USAGE_READ_MASK)
2638 return state_rnames[bit >> LOCK_USAGE_DIR_MASK];
2639 else
2640 return state_names[bit >> LOCK_USAGE_DIR_MASK];
2641}
2642
2643/*
2644 * The bit number is encoded like:
2645 *
2646 * bit0: 0 exclusive, 1 read lock
2647 * bit1: 0 used in irq, 1 irq enabled
2648 * bit2-n: state
2649 */
2650static int exclusive_bit(int new_bit)
2651{
2652 int state = new_bit & LOCK_USAGE_STATE_MASK;
2653 int dir = new_bit & LOCK_USAGE_DIR_MASK;
2654
2655 /*
2656 * keep state, bit flip the direction and strip read.
2657 */
2658 return state | (dir ^ LOCK_USAGE_DIR_MASK);
2659}
2660
2661/*
2662 * Observe that when given a bitmask where each bitnr is encoded as above, a
2663 * right shift of the mask transforms the individual bitnrs as -1 and
2664 * conversely, a left shift transforms into +1 for the individual bitnrs.
2665 *
2666 * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can
2667 * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0)
2668 * instead by subtracting the bit number by 2, or shifting the mask right by 2.
2669 *
2670 * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2.
2671 *
2672 * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is
2673 * all bits set) and recompose with bitnr1 flipped.
2674 */
2675static unsigned long invert_dir_mask(unsigned long mask)
2676{
2677 unsigned long excl = 0;
2678
2679 /* Invert dir */
2680 excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK;
2681 excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK;
2682
2683 return excl;
2684}
2685
2686/*
2687 * Note that a LOCK_ENABLED_IRQ_*_READ usage and a LOCK_USED_IN_IRQ_*_READ
2688 * usage may cause deadlock too, for example:
2689 *
2690 * P1 P2
2691 * <irq disabled>
2692 * write_lock(l1); <irq enabled>
2693 * read_lock(l2);
2694 * write_lock(l2);
2695 * <in irq>
2696 * read_lock(l1);
2697 *
2698 * , in above case, l1 will be marked as LOCK_USED_IN_IRQ_HARDIRQ_READ and l2
2699 * will marked as LOCK_ENABLE_IRQ_HARDIRQ_READ, and this is a possible
2700 * deadlock.
2701 *
2702 * In fact, all of the following cases may cause deadlocks:
2703 *
2704 * LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_*
2705 * LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_*
2706 * LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_*_READ
2707 * LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_*_READ
2708 *
2709 * As a result, to calculate the "exclusive mask", first we invert the
2710 * direction (USED_IN/ENABLED) of the original mask, and 1) for all bits with
2711 * bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*). 2) for all
2712 * bits with bitnr0 cleared (LOCK_*_READ), add those with bitnr0 set (LOCK_*).
2713 */
2714static unsigned long exclusive_mask(unsigned long mask)
2715{
2716 unsigned long excl = invert_dir_mask(mask);
2717
2718 excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
2719 excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
2720
2721 return excl;
2722}
2723
2724/*
2725 * Retrieve the _possible_ original mask to which @mask is
2726 * exclusive. Ie: this is the opposite of exclusive_mask().
2727 * Note that 2 possible original bits can match an exclusive
2728 * bit: one has LOCK_USAGE_READ_MASK set, the other has it
2729 * cleared. So both are returned for each exclusive bit.
2730 */
2731static unsigned long original_mask(unsigned long mask)
2732{
2733 unsigned long excl = invert_dir_mask(mask);
2734
2735 /* Include read in existing usages */
2736 excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
2737 excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
2738
2739 return excl;
2740}
2741
2742/*
2743 * Find the first pair of bit match between an original
2744 * usage mask and an exclusive usage mask.
2745 */
2746static int find_exclusive_match(unsigned long mask,
2747 unsigned long excl_mask,
2748 enum lock_usage_bit *bitp,
2749 enum lock_usage_bit *excl_bitp)
2750{
2751 int bit, excl, excl_read;
2752
2753 for_each_set_bit(bit, &mask, LOCK_USED) {
2754 /*
2755 * exclusive_bit() strips the read bit, however,
2756 * LOCK_ENABLED_IRQ_*_READ may cause deadlocks too, so we need
2757 * to search excl | LOCK_USAGE_READ_MASK as well.
2758 */
2759 excl = exclusive_bit(bit);
2760 excl_read = excl | LOCK_USAGE_READ_MASK;
2761 if (excl_mask & lock_flag(excl)) {
2762 *bitp = bit;
2763 *excl_bitp = excl;
2764 return 0;
2765 } else if (excl_mask & lock_flag(excl_read)) {
2766 *bitp = bit;
2767 *excl_bitp = excl_read;
2768 return 0;
2769 }
2770 }
2771 return -1;
2772}
2773
2774/*
2775 * Prove that the new dependency does not connect a hardirq-safe(-read)
2776 * lock with a hardirq-unsafe lock - to achieve this we search
2777 * the backwards-subgraph starting at <prev>, and the
2778 * forwards-subgraph starting at <next>:
2779 */
2780static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
2781 struct held_lock *next)
2782{
2783 unsigned long usage_mask = 0, forward_mask, backward_mask;
2784 enum lock_usage_bit forward_bit = 0, backward_bit = 0;
2785 struct lock_list *target_entry1;
2786 struct lock_list *target_entry;
2787 struct lock_list this, that;
2788 enum bfs_result ret;
2789
2790 /*
2791 * Step 1: gather all hard/soft IRQs usages backward in an
2792 * accumulated usage mask.
2793 */
2794 bfs_init_rootb(&this, prev);
2795
2796 ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, usage_skip, NULL);
2797 if (bfs_error(ret)) {
2798 print_bfs_bug(ret);
2799 return 0;
2800 }
2801
2802 usage_mask &= LOCKF_USED_IN_IRQ_ALL;
2803 if (!usage_mask)
2804 return 1;
2805
2806 /*
2807 * Step 2: find exclusive uses forward that match the previous
2808 * backward accumulated mask.
2809 */
2810 forward_mask = exclusive_mask(usage_mask);
2811
2812 bfs_init_root(&that, next);
2813
2814 ret = find_usage_forwards(&that, forward_mask, &target_entry1);
2815 if (bfs_error(ret)) {
2816 print_bfs_bug(ret);
2817 return 0;
2818 }
2819 if (ret == BFS_RNOMATCH)
2820 return 1;
2821
2822 /*
2823 * Step 3: we found a bad match! Now retrieve a lock from the backward
2824 * list whose usage mask matches the exclusive usage mask from the
2825 * lock found on the forward list.
2826 *
2827 * Note, we should only keep the LOCKF_ENABLED_IRQ_ALL bits, considering
2828 * the follow case:
2829 *
2830 * When trying to add A -> B to the graph, we find that there is a
2831 * hardirq-safe L, that L -> ... -> A, and another hardirq-unsafe M,
2832 * that B -> ... -> M. However M is **softirq-safe**, if we use exact
2833 * invert bits of M's usage_mask, we will find another lock N that is
2834 * **softirq-unsafe** and N -> ... -> A, however N -> .. -> M will not
2835 * cause a inversion deadlock.
2836 */
2837 backward_mask = original_mask(target_entry1->class->usage_mask & LOCKF_ENABLED_IRQ_ALL);
2838
2839 ret = find_usage_backwards(&this, backward_mask, &target_entry);
2840 if (bfs_error(ret)) {
2841 print_bfs_bug(ret);
2842 return 0;
2843 }
2844 if (DEBUG_LOCKS_WARN_ON(ret == BFS_RNOMATCH))
2845 return 1;
2846
2847 /*
2848 * Step 4: narrow down to a pair of incompatible usage bits
2849 * and report it.
2850 */
2851 ret = find_exclusive_match(target_entry->class->usage_mask,
2852 target_entry1->class->usage_mask,
2853 &backward_bit, &forward_bit);
2854 if (DEBUG_LOCKS_WARN_ON(ret == -1))
2855 return 1;
2856
2857 print_bad_irq_dependency(curr, &this, &that,
2858 target_entry, target_entry1,
2859 prev, next,
2860 backward_bit, forward_bit,
2861 state_name(backward_bit));
2862
2863 return 0;
2864}
2865
2866#else
2867
2868static inline int check_irq_usage(struct task_struct *curr,
2869 struct held_lock *prev, struct held_lock *next)
2870{
2871 return 1;
2872}
2873
2874static inline bool usage_skip(struct lock_list *entry, void *mask)
2875{
2876 return false;
2877}
2878
2879#endif /* CONFIG_TRACE_IRQFLAGS */
2880
2881#ifdef CONFIG_LOCKDEP_SMALL
2882/*
2883 * We are about to add A -> B into the dependency graph, and in __bfs() a
2884 * strong dependency path A -> .. -> B is found: hlock_class equals
2885 * entry->class.
2886 *
2887 * If A -> .. -> B can replace A -> B in any __bfs() search (means the former
2888 * is _stronger_ than or equal to the latter), we consider A -> B as redundant.
2889 * For example if A -> .. -> B is -(EN)-> (i.e. A -(E*)-> .. -(*N)-> B), and A
2890 * -> B is -(ER)-> or -(EN)->, then we don't need to add A -> B into the
2891 * dependency graph, as any strong path ..-> A -> B ->.. we can get with
2892 * having dependency A -> B, we could already get a equivalent path ..-> A ->
2893 * .. -> B -> .. with A -> .. -> B. Therefore A -> B is redundant.
2894 *
2895 * We need to make sure both the start and the end of A -> .. -> B is not
2896 * weaker than A -> B. For the start part, please see the comment in
2897 * check_redundant(). For the end part, we need:
2898 *
2899 * Either
2900 *
2901 * a) A -> B is -(*R)-> (everything is not weaker than that)
2902 *
2903 * or
2904 *
2905 * b) A -> .. -> B is -(*N)-> (nothing is stronger than this)
2906 *
2907 */
2908static inline bool hlock_equal(struct lock_list *entry, void *data)
2909{
2910 struct held_lock *hlock = (struct held_lock *)data;
2911
2912 return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */
2913 (hlock->read == 2 || /* A -> B is -(*R)-> */
2914 !entry->only_xr); /* A -> .. -> B is -(*N)-> */
2915}
2916
2917/*
2918 * Check that the dependency graph starting at <src> can lead to
2919 * <target> or not. If it can, <src> -> <target> dependency is already
2920 * in the graph.
2921 *
2922 * Return BFS_RMATCH if it does, or BFS_RNOMATCH if it does not, return BFS_E* if
2923 * any error appears in the bfs search.
2924 */
2925static noinline enum bfs_result
2926check_redundant(struct held_lock *src, struct held_lock *target)
2927{
2928 enum bfs_result ret;
2929 struct lock_list *target_entry;
2930 struct lock_list src_entry;
2931
2932 bfs_init_root(&src_entry, src);
2933 /*
2934 * Special setup for check_redundant().
2935 *
2936 * To report redundant, we need to find a strong dependency path that
2937 * is equal to or stronger than <src> -> <target>. So if <src> is E,
2938 * we need to let __bfs() only search for a path starting at a -(E*)->,
2939 * we achieve this by setting the initial node's ->only_xr to true in
2940 * that case. And if <prev> is S, we set initial ->only_xr to false
2941 * because both -(S*)-> (equal) and -(E*)-> (stronger) are redundant.
2942 */
2943 src_entry.only_xr = src->read == 0;
2944
2945 debug_atomic_inc(nr_redundant_checks);
2946
2947 /*
2948 * Note: we skip local_lock() for redundant check, because as the
2949 * comment in usage_skip(), A -> local_lock() -> B and A -> B are not
2950 * the same.
2951 */
2952 ret = check_path(target, &src_entry, hlock_equal, usage_skip, &target_entry);
2953
2954 if (ret == BFS_RMATCH)
2955 debug_atomic_inc(nr_redundant);
2956
2957 return ret;
2958}
2959
2960#else
2961
2962static inline enum bfs_result
2963check_redundant(struct held_lock *src, struct held_lock *target)
2964{
2965 return BFS_RNOMATCH;
2966}
2967
2968#endif
2969
2970static void inc_chains(int irq_context)
2971{
2972 if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
2973 nr_hardirq_chains++;
2974 else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
2975 nr_softirq_chains++;
2976 else
2977 nr_process_chains++;
2978}
2979
2980static void dec_chains(int irq_context)
2981{
2982 if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
2983 nr_hardirq_chains--;
2984 else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
2985 nr_softirq_chains--;
2986 else
2987 nr_process_chains--;
2988}
2989
2990static void
2991print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
2992{
2993 struct lock_class *next = hlock_class(nxt);
2994 struct lock_class *prev = hlock_class(prv);
2995
2996 printk(" Possible unsafe locking scenario:\n\n");
2997 printk(" CPU0\n");
2998 printk(" ----\n");
2999 printk(" lock(");
3000 __print_lock_name(prv, prev);
3001 printk(KERN_CONT ");\n");
3002 printk(" lock(");
3003 __print_lock_name(nxt, next);
3004 printk(KERN_CONT ");\n");
3005 printk("\n *** DEADLOCK ***\n\n");
3006 printk(" May be due to missing lock nesting notation\n\n");
3007}
3008
3009static void
3010print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
3011 struct held_lock *next)
3012{
3013 struct lock_class *class = hlock_class(prev);
3014
3015 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
3016 return;
3017
3018 nbcon_cpu_emergency_enter();
3019
3020 pr_warn("\n");
3021 pr_warn("============================================\n");
3022 pr_warn("WARNING: possible recursive locking detected\n");
3023 print_kernel_ident();
3024 pr_warn("--------------------------------------------\n");
3025 pr_warn("%s/%d is trying to acquire lock:\n",
3026 curr->comm, task_pid_nr(curr));
3027 print_lock(next);
3028 pr_warn("\nbut task is already holding lock:\n");
3029 print_lock(prev);
3030
3031 if (class->cmp_fn) {
3032 pr_warn("and the lock comparison function returns %i:\n",
3033 class->cmp_fn(prev->instance, next->instance));
3034 }
3035
3036 pr_warn("\nother info that might help us debug this:\n");
3037 print_deadlock_scenario(next, prev);
3038 lockdep_print_held_locks(curr);
3039
3040 pr_warn("\nstack backtrace:\n");
3041 dump_stack();
3042
3043 nbcon_cpu_emergency_exit();
3044}
3045
3046/*
3047 * Check whether we are holding such a class already.
3048 *
3049 * (Note that this has to be done separately, because the graph cannot
3050 * detect such classes of deadlocks.)
3051 *
3052 * Returns: 0 on deadlock detected, 1 on OK, 2 if another lock with the same
3053 * lock class is held but nest_lock is also held, i.e. we rely on the
3054 * nest_lock to avoid the deadlock.
3055 */
3056static int
3057check_deadlock(struct task_struct *curr, struct held_lock *next)
3058{
3059 struct lock_class *class;
3060 struct held_lock *prev;
3061 struct held_lock *nest = NULL;
3062 int i;
3063
3064 for (i = 0; i < curr->lockdep_depth; i++) {
3065 prev = curr->held_locks + i;
3066
3067 if (prev->instance == next->nest_lock)
3068 nest = prev;
3069
3070 if (hlock_class(prev) != hlock_class(next))
3071 continue;
3072
3073 /*
3074 * Allow read-after-read recursion of the same
3075 * lock class (i.e. read_lock(lock)+read_lock(lock)):
3076 */
3077 if ((next->read == 2) && prev->read)
3078 continue;
3079
3080 class = hlock_class(prev);
3081
3082 if (class->cmp_fn &&
3083 class->cmp_fn(prev->instance, next->instance) < 0)
3084 continue;
3085
3086 /*
3087 * We're holding the nest_lock, which serializes this lock's
3088 * nesting behaviour.
3089 */
3090 if (nest)
3091 return 2;
3092
3093 print_deadlock_bug(curr, prev, next);
3094 return 0;
3095 }
3096 return 1;
3097}
3098
3099/*
3100 * There was a chain-cache miss, and we are about to add a new dependency
3101 * to a previous lock. We validate the following rules:
3102 *
3103 * - would the adding of the <prev> -> <next> dependency create a
3104 * circular dependency in the graph? [== circular deadlock]
3105 *
3106 * - does the new prev->next dependency connect any hardirq-safe lock
3107 * (in the full backwards-subgraph starting at <prev>) with any
3108 * hardirq-unsafe lock (in the full forwards-subgraph starting at
3109 * <next>)? [== illegal lock inversion with hardirq contexts]
3110 *
3111 * - does the new prev->next dependency connect any softirq-safe lock
3112 * (in the full backwards-subgraph starting at <prev>) with any
3113 * softirq-unsafe lock (in the full forwards-subgraph starting at
3114 * <next>)? [== illegal lock inversion with softirq contexts]
3115 *
3116 * any of these scenarios could lead to a deadlock.
3117 *
3118 * Then if all the validations pass, we add the forwards and backwards
3119 * dependency.
3120 */
3121static int
3122check_prev_add(struct task_struct *curr, struct held_lock *prev,
3123 struct held_lock *next, u16 distance,
3124 struct lock_trace **const trace)
3125{
3126 struct lock_list *entry;
3127 enum bfs_result ret;
3128
3129 if (!hlock_class(prev)->key || !hlock_class(next)->key) {
3130 /*
3131 * The warning statements below may trigger a use-after-free
3132 * of the class name. It is better to trigger a use-after free
3133 * and to have the class name most of the time instead of not
3134 * having the class name available.
3135 */
3136 WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key,
3137 "Detected use-after-free of lock class %px/%s\n",
3138 hlock_class(prev),
3139 hlock_class(prev)->name);
3140 WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key,
3141 "Detected use-after-free of lock class %px/%s\n",
3142 hlock_class(next),
3143 hlock_class(next)->name);
3144 return 2;
3145 }
3146
3147 if (prev->class_idx == next->class_idx) {
3148 struct lock_class *class = hlock_class(prev);
3149
3150 if (class->cmp_fn &&
3151 class->cmp_fn(prev->instance, next->instance) < 0)
3152 return 2;
3153 }
3154
3155 /*
3156 * Prove that the new <prev> -> <next> dependency would not
3157 * create a circular dependency in the graph. (We do this by
3158 * a breadth-first search into the graph starting at <next>,
3159 * and check whether we can reach <prev>.)
3160 *
3161 * The search is limited by the size of the circular queue (i.e.,
3162 * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes
3163 * in the graph whose neighbours are to be checked.
3164 */
3165 ret = check_noncircular(next, prev, trace);
3166 if (unlikely(bfs_error(ret) || ret == BFS_RMATCH))
3167 return 0;
3168
3169 if (!check_irq_usage(curr, prev, next))
3170 return 0;
3171
3172 /*
3173 * Is the <prev> -> <next> dependency already present?
3174 *
3175 * (this may occur even though this is a new chain: consider
3176 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
3177 * chains - the second one will be new, but L1 already has
3178 * L2 added to its dependency list, due to the first chain.)
3179 */
3180 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
3181 if (entry->class == hlock_class(next)) {
3182 if (distance == 1)
3183 entry->distance = 1;
3184 entry->dep |= calc_dep(prev, next);
3185
3186 /*
3187 * Also, update the reverse dependency in @next's
3188 * ->locks_before list.
3189 *
3190 * Here we reuse @entry as the cursor, which is fine
3191 * because we won't go to the next iteration of the
3192 * outer loop:
3193 *
3194 * For normal cases, we return in the inner loop.
3195 *
3196 * If we fail to return, we have inconsistency, i.e.
3197 * <prev>::locks_after contains <next> while
3198 * <next>::locks_before doesn't contain <prev>. In
3199 * that case, we return after the inner and indicate
3200 * something is wrong.
3201 */
3202 list_for_each_entry(entry, &hlock_class(next)->locks_before, entry) {
3203 if (entry->class == hlock_class(prev)) {
3204 if (distance == 1)
3205 entry->distance = 1;
3206 entry->dep |= calc_depb(prev, next);
3207 return 1;
3208 }
3209 }
3210
3211 /* <prev> is not found in <next>::locks_before */
3212 return 0;
3213 }
3214 }
3215
3216 /*
3217 * Is the <prev> -> <next> link redundant?
3218 */
3219 ret = check_redundant(prev, next);
3220 if (bfs_error(ret))
3221 return 0;
3222 else if (ret == BFS_RMATCH)
3223 return 2;
3224
3225 if (!*trace) {
3226 *trace = save_trace();
3227 if (!*trace)
3228 return 0;
3229 }
3230
3231 /*
3232 * Ok, all validations passed, add the new lock
3233 * to the previous lock's dependency list:
3234 */
3235 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
3236 &hlock_class(prev)->locks_after, distance,
3237 calc_dep(prev, next), *trace);
3238
3239 if (!ret)
3240 return 0;
3241
3242 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
3243 &hlock_class(next)->locks_before, distance,
3244 calc_depb(prev, next), *trace);
3245 if (!ret)
3246 return 0;
3247
3248 return 2;
3249}
3250
3251/*
3252 * Add the dependency to all directly-previous locks that are 'relevant'.
3253 * The ones that are relevant are (in increasing distance from curr):
3254 * all consecutive trylock entries and the final non-trylock entry - or
3255 * the end of this context's lock-chain - whichever comes first.
3256 */
3257static int
3258check_prevs_add(struct task_struct *curr, struct held_lock *next)
3259{
3260 struct lock_trace *trace = NULL;
3261 int depth = curr->lockdep_depth;
3262 struct held_lock *hlock;
3263
3264 /*
3265 * Debugging checks.
3266 *
3267 * Depth must not be zero for a non-head lock:
3268 */
3269 if (!depth)
3270 goto out_bug;
3271 /*
3272 * At least two relevant locks must exist for this
3273 * to be a head:
3274 */
3275 if (curr->held_locks[depth].irq_context !=
3276 curr->held_locks[depth-1].irq_context)
3277 goto out_bug;
3278
3279 for (;;) {
3280 u16 distance = curr->lockdep_depth - depth + 1;
3281 hlock = curr->held_locks + depth - 1;
3282
3283 if (hlock->check) {
3284 int ret = check_prev_add(curr, hlock, next, distance, &trace);
3285 if (!ret)
3286 return 0;
3287
3288 /*
3289 * Stop after the first non-trylock entry,
3290 * as non-trylock entries have added their
3291 * own direct dependencies already, so this
3292 * lock is connected to them indirectly:
3293 */
3294 if (!hlock->trylock)
3295 break;
3296 }
3297
3298 depth--;
3299 /*
3300 * End of lock-stack?
3301 */
3302 if (!depth)
3303 break;
3304 /*
3305 * Stop the search if we cross into another context:
3306 */
3307 if (curr->held_locks[depth].irq_context !=
3308 curr->held_locks[depth-1].irq_context)
3309 break;
3310 }
3311 return 1;
3312out_bug:
3313 if (!debug_locks_off_graph_unlock())
3314 return 0;
3315
3316 /*
3317 * Clearly we all shouldn't be here, but since we made it we
3318 * can reliable say we messed up our state. See the above two
3319 * gotos for reasons why we could possibly end up here.
3320 */
3321 WARN_ON(1);
3322
3323 return 0;
3324}
3325
3326struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
3327static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS);
3328static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
3329unsigned long nr_zapped_lock_chains;
3330unsigned int nr_free_chain_hlocks; /* Free chain_hlocks in buckets */
3331unsigned int nr_lost_chain_hlocks; /* Lost chain_hlocks */
3332unsigned int nr_large_chain_blocks; /* size > MAX_CHAIN_BUCKETS */
3333
3334/*
3335 * The first 2 chain_hlocks entries in the chain block in the bucket
3336 * list contains the following meta data:
3337 *
3338 * entry[0]:
3339 * Bit 15 - always set to 1 (it is not a class index)
3340 * Bits 0-14 - upper 15 bits of the next block index
3341 * entry[1] - lower 16 bits of next block index
3342 *
3343 * A next block index of all 1 bits means it is the end of the list.
3344 *
3345 * On the unsized bucket (bucket-0), the 3rd and 4th entries contain
3346 * the chain block size:
3347 *
3348 * entry[2] - upper 16 bits of the chain block size
3349 * entry[3] - lower 16 bits of the chain block size
3350 */
3351#define MAX_CHAIN_BUCKETS 16
3352#define CHAIN_BLK_FLAG (1U << 15)
3353#define CHAIN_BLK_LIST_END 0xFFFFU
3354
3355static int chain_block_buckets[MAX_CHAIN_BUCKETS];
3356
3357static inline int size_to_bucket(int size)
3358{
3359 if (size > MAX_CHAIN_BUCKETS)
3360 return 0;
3361
3362 return size - 1;
3363}
3364
3365/*
3366 * Iterate all the chain blocks in a bucket.
3367 */
3368#define for_each_chain_block(bucket, prev, curr) \
3369 for ((prev) = -1, (curr) = chain_block_buckets[bucket]; \
3370 (curr) >= 0; \
3371 (prev) = (curr), (curr) = chain_block_next(curr))
3372
3373/*
3374 * next block or -1
3375 */
3376static inline int chain_block_next(int offset)
3377{
3378 int next = chain_hlocks[offset];
3379
3380 WARN_ON_ONCE(!(next & CHAIN_BLK_FLAG));
3381
3382 if (next == CHAIN_BLK_LIST_END)
3383 return -1;
3384
3385 next &= ~CHAIN_BLK_FLAG;
3386 next <<= 16;
3387 next |= chain_hlocks[offset + 1];
3388
3389 return next;
3390}
3391
3392/*
3393 * bucket-0 only
3394 */
3395static inline int chain_block_size(int offset)
3396{
3397 return (chain_hlocks[offset + 2] << 16) | chain_hlocks[offset + 3];
3398}
3399
3400static inline void init_chain_block(int offset, int next, int bucket, int size)
3401{
3402 chain_hlocks[offset] = (next >> 16) | CHAIN_BLK_FLAG;
3403 chain_hlocks[offset + 1] = (u16)next;
3404
3405 if (size && !bucket) {
3406 chain_hlocks[offset + 2] = size >> 16;
3407 chain_hlocks[offset + 3] = (u16)size;
3408 }
3409}
3410
3411static inline void add_chain_block(int offset, int size)
3412{
3413 int bucket = size_to_bucket(size);
3414 int next = chain_block_buckets[bucket];
3415 int prev, curr;
3416
3417 if (unlikely(size < 2)) {
3418 /*
3419 * We can't store single entries on the freelist. Leak them.
3420 *
3421 * One possible way out would be to uniquely mark them, other
3422 * than with CHAIN_BLK_FLAG, such that we can recover them when
3423 * the block before it is re-added.
3424 */
3425 if (size)
3426 nr_lost_chain_hlocks++;
3427 return;
3428 }
3429
3430 nr_free_chain_hlocks += size;
3431 if (!bucket) {
3432 nr_large_chain_blocks++;
3433
3434 /*
3435 * Variable sized, sort large to small.
3436 */
3437 for_each_chain_block(0, prev, curr) {
3438 if (size >= chain_block_size(curr))
3439 break;
3440 }
3441 init_chain_block(offset, curr, 0, size);
3442 if (prev < 0)
3443 chain_block_buckets[0] = offset;
3444 else
3445 init_chain_block(prev, offset, 0, 0);
3446 return;
3447 }
3448 /*
3449 * Fixed size, add to head.
3450 */
3451 init_chain_block(offset, next, bucket, size);
3452 chain_block_buckets[bucket] = offset;
3453}
3454
3455/*
3456 * Only the first block in the list can be deleted.
3457 *
3458 * For the variable size bucket[0], the first block (the largest one) is
3459 * returned, broken up and put back into the pool. So if a chain block of
3460 * length > MAX_CHAIN_BUCKETS is ever used and zapped, it will just be
3461 * queued up after the primordial chain block and never be used until the
3462 * hlock entries in the primordial chain block is almost used up. That
3463 * causes fragmentation and reduce allocation efficiency. That can be
3464 * monitored by looking at the "large chain blocks" number in lockdep_stats.
3465 */
3466static inline void del_chain_block(int bucket, int size, int next)
3467{
3468 nr_free_chain_hlocks -= size;
3469 chain_block_buckets[bucket] = next;
3470
3471 if (!bucket)
3472 nr_large_chain_blocks--;
3473}
3474
3475static void init_chain_block_buckets(void)
3476{
3477 int i;
3478
3479 for (i = 0; i < MAX_CHAIN_BUCKETS; i++)
3480 chain_block_buckets[i] = -1;
3481
3482 add_chain_block(0, ARRAY_SIZE(chain_hlocks));
3483}
3484
3485/*
3486 * Return offset of a chain block of the right size or -1 if not found.
3487 *
3488 * Fairly simple worst-fit allocator with the addition of a number of size
3489 * specific free lists.
3490 */
3491static int alloc_chain_hlocks(int req)
3492{
3493 int bucket, curr, size;
3494
3495 /*
3496 * We rely on the MSB to act as an escape bit to denote freelist
3497 * pointers. Make sure this bit isn't set in 'normal' class_idx usage.
3498 */
3499 BUILD_BUG_ON((MAX_LOCKDEP_KEYS-1) & CHAIN_BLK_FLAG);
3500
3501 init_data_structures_once();
3502
3503 if (nr_free_chain_hlocks < req)
3504 return -1;
3505
3506 /*
3507 * We require a minimum of 2 (u16) entries to encode a freelist
3508 * 'pointer'.
3509 */
3510 req = max(req, 2);
3511 bucket = size_to_bucket(req);
3512 curr = chain_block_buckets[bucket];
3513
3514 if (bucket) {
3515 if (curr >= 0) {
3516 del_chain_block(bucket, req, chain_block_next(curr));
3517 return curr;
3518 }
3519 /* Try bucket 0 */
3520 curr = chain_block_buckets[0];
3521 }
3522
3523 /*
3524 * The variable sized freelist is sorted by size; the first entry is
3525 * the largest. Use it if it fits.
3526 */
3527 if (curr >= 0) {
3528 size = chain_block_size(curr);
3529 if (likely(size >= req)) {
3530 del_chain_block(0, size, chain_block_next(curr));
3531 if (size > req)
3532 add_chain_block(curr + req, size - req);
3533 return curr;
3534 }
3535 }
3536
3537 /*
3538 * Last resort, split a block in a larger sized bucket.
3539 */
3540 for (size = MAX_CHAIN_BUCKETS; size > req; size--) {
3541 bucket = size_to_bucket(size);
3542 curr = chain_block_buckets[bucket];
3543 if (curr < 0)
3544 continue;
3545
3546 del_chain_block(bucket, size, chain_block_next(curr));
3547 add_chain_block(curr + req, size - req);
3548 return curr;
3549 }
3550
3551 return -1;
3552}
3553
3554static inline void free_chain_hlocks(int base, int size)
3555{
3556 add_chain_block(base, max(size, 2));
3557}
3558
3559struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
3560{
3561 u16 chain_hlock = chain_hlocks[chain->base + i];
3562 unsigned int class_idx = chain_hlock_class_idx(chain_hlock);
3563
3564 return lock_classes + class_idx;
3565}
3566
3567/*
3568 * Returns the index of the first held_lock of the current chain
3569 */
3570static inline int get_first_held_lock(struct task_struct *curr,
3571 struct held_lock *hlock)
3572{
3573 int i;
3574 struct held_lock *hlock_curr;
3575
3576 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
3577 hlock_curr = curr->held_locks + i;
3578 if (hlock_curr->irq_context != hlock->irq_context)
3579 break;
3580
3581 }
3582
3583 return ++i;
3584}
3585
3586#ifdef CONFIG_DEBUG_LOCKDEP
3587/*
3588 * Returns the next chain_key iteration
3589 */
3590static u64 print_chain_key_iteration(u16 hlock_id, u64 chain_key)
3591{
3592 u64 new_chain_key = iterate_chain_key(chain_key, hlock_id);
3593
3594 printk(" hlock_id:%d -> chain_key:%016Lx",
3595 (unsigned int)hlock_id,
3596 (unsigned long long)new_chain_key);
3597 return new_chain_key;
3598}
3599
3600static void
3601print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
3602{
3603 struct held_lock *hlock;
3604 u64 chain_key = INITIAL_CHAIN_KEY;
3605 int depth = curr->lockdep_depth;
3606 int i = get_first_held_lock(curr, hlock_next);
3607
3608 printk("depth: %u (irq_context %u)\n", depth - i + 1,
3609 hlock_next->irq_context);
3610 for (; i < depth; i++) {
3611 hlock = curr->held_locks + i;
3612 chain_key = print_chain_key_iteration(hlock_id(hlock), chain_key);
3613
3614 print_lock(hlock);
3615 }
3616
3617 print_chain_key_iteration(hlock_id(hlock_next), chain_key);
3618 print_lock(hlock_next);
3619}
3620
3621static void print_chain_keys_chain(struct lock_chain *chain)
3622{
3623 int i;
3624 u64 chain_key = INITIAL_CHAIN_KEY;
3625 u16 hlock_id;
3626
3627 printk("depth: %u\n", chain->depth);
3628 for (i = 0; i < chain->depth; i++) {
3629 hlock_id = chain_hlocks[chain->base + i];
3630 chain_key = print_chain_key_iteration(hlock_id, chain_key);
3631
3632 print_lock_name(NULL, lock_classes + chain_hlock_class_idx(hlock_id));
3633 printk("\n");
3634 }
3635}
3636
3637static void print_collision(struct task_struct *curr,
3638 struct held_lock *hlock_next,
3639 struct lock_chain *chain)
3640{
3641 nbcon_cpu_emergency_enter();
3642
3643 pr_warn("\n");
3644 pr_warn("============================\n");
3645 pr_warn("WARNING: chain_key collision\n");
3646 print_kernel_ident();
3647 pr_warn("----------------------------\n");
3648 pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
3649 pr_warn("Hash chain already cached but the contents don't match!\n");
3650
3651 pr_warn("Held locks:");
3652 print_chain_keys_held_locks(curr, hlock_next);
3653
3654 pr_warn("Locks in cached chain:");
3655 print_chain_keys_chain(chain);
3656
3657 pr_warn("\nstack backtrace:\n");
3658 dump_stack();
3659
3660 nbcon_cpu_emergency_exit();
3661}
3662#endif
3663
3664/*
3665 * Checks whether the chain and the current held locks are consistent
3666 * in depth and also in content. If they are not it most likely means
3667 * that there was a collision during the calculation of the chain_key.
3668 * Returns: 0 not passed, 1 passed
3669 */
3670static int check_no_collision(struct task_struct *curr,
3671 struct held_lock *hlock,
3672 struct lock_chain *chain)
3673{
3674#ifdef CONFIG_DEBUG_LOCKDEP
3675 int i, j, id;
3676
3677 i = get_first_held_lock(curr, hlock);
3678
3679 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
3680 print_collision(curr, hlock, chain);
3681 return 0;
3682 }
3683
3684 for (j = 0; j < chain->depth - 1; j++, i++) {
3685 id = hlock_id(&curr->held_locks[i]);
3686
3687 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
3688 print_collision(curr, hlock, chain);
3689 return 0;
3690 }
3691 }
3692#endif
3693 return 1;
3694}
3695
3696/*
3697 * Given an index that is >= -1, return the index of the next lock chain.
3698 * Return -2 if there is no next lock chain.
3699 */
3700long lockdep_next_lockchain(long i)
3701{
3702 i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1);
3703 return i < ARRAY_SIZE(lock_chains) ? i : -2;
3704}
3705
3706unsigned long lock_chain_count(void)
3707{
3708 return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains));
3709}
3710
3711/* Must be called with the graph lock held. */
3712static struct lock_chain *alloc_lock_chain(void)
3713{
3714 int idx = find_first_zero_bit(lock_chains_in_use,
3715 ARRAY_SIZE(lock_chains));
3716
3717 if (unlikely(idx >= ARRAY_SIZE(lock_chains)))
3718 return NULL;
3719 __set_bit(idx, lock_chains_in_use);
3720 return lock_chains + idx;
3721}
3722
3723/*
3724 * Adds a dependency chain into chain hashtable. And must be called with
3725 * graph_lock held.
3726 *
3727 * Return 0 if fail, and graph_lock is released.
3728 * Return 1 if succeed, with graph_lock held.
3729 */
3730static inline int add_chain_cache(struct task_struct *curr,
3731 struct held_lock *hlock,
3732 u64 chain_key)
3733{
3734 struct hlist_head *hash_head = chainhashentry(chain_key);
3735 struct lock_chain *chain;
3736 int i, j;
3737
3738 /*
3739 * The caller must hold the graph lock, ensure we've got IRQs
3740 * disabled to make this an IRQ-safe lock.. for recursion reasons
3741 * lockdep won't complain about its own locking errors.
3742 */
3743 if (lockdep_assert_locked())
3744 return 0;
3745
3746 chain = alloc_lock_chain();
3747 if (!chain) {
3748 if (!debug_locks_off_graph_unlock())
3749 return 0;
3750
3751 nbcon_cpu_emergency_enter();
3752 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
3753 dump_stack();
3754 nbcon_cpu_emergency_exit();
3755 return 0;
3756 }
3757 chain->chain_key = chain_key;
3758 chain->irq_context = hlock->irq_context;
3759 i = get_first_held_lock(curr, hlock);
3760 chain->depth = curr->lockdep_depth + 1 - i;
3761
3762 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
3763 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
3764 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
3765
3766 j = alloc_chain_hlocks(chain->depth);
3767 if (j < 0) {
3768 if (!debug_locks_off_graph_unlock())
3769 return 0;
3770
3771 nbcon_cpu_emergency_enter();
3772 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
3773 dump_stack();
3774 nbcon_cpu_emergency_exit();
3775 return 0;
3776 }
3777
3778 chain->base = j;
3779 for (j = 0; j < chain->depth - 1; j++, i++) {
3780 int lock_id = hlock_id(curr->held_locks + i);
3781
3782 chain_hlocks[chain->base + j] = lock_id;
3783 }
3784 chain_hlocks[chain->base + j] = hlock_id(hlock);
3785 hlist_add_head_rcu(&chain->entry, hash_head);
3786 debug_atomic_inc(chain_lookup_misses);
3787 inc_chains(chain->irq_context);
3788
3789 return 1;
3790}
3791
3792/*
3793 * Look up a dependency chain. Must be called with either the graph lock or
3794 * the RCU read lock held.
3795 */
3796static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
3797{
3798 struct hlist_head *hash_head = chainhashentry(chain_key);
3799 struct lock_chain *chain;
3800
3801 hlist_for_each_entry_rcu(chain, hash_head, entry) {
3802 if (READ_ONCE(chain->chain_key) == chain_key) {
3803 debug_atomic_inc(chain_lookup_hits);
3804 return chain;
3805 }
3806 }
3807 return NULL;
3808}
3809
3810/*
3811 * If the key is not present yet in dependency chain cache then
3812 * add it and return 1 - in this case the new dependency chain is
3813 * validated. If the key is already hashed, return 0.
3814 * (On return with 1 graph_lock is held.)
3815 */
3816static inline int lookup_chain_cache_add(struct task_struct *curr,
3817 struct held_lock *hlock,
3818 u64 chain_key)
3819{
3820 struct lock_class *class = hlock_class(hlock);
3821 struct lock_chain *chain = lookup_chain_cache(chain_key);
3822
3823 if (chain) {
3824cache_hit:
3825 if (!check_no_collision(curr, hlock, chain))
3826 return 0;
3827
3828 if (very_verbose(class)) {
3829 printk("\nhash chain already cached, key: "
3830 "%016Lx tail class: [%px] %s\n",
3831 (unsigned long long)chain_key,
3832 class->key, class->name);
3833 }
3834
3835 return 0;
3836 }
3837
3838 if (very_verbose(class)) {
3839 printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
3840 (unsigned long long)chain_key, class->key, class->name);
3841 }
3842
3843 if (!graph_lock())
3844 return 0;
3845
3846 /*
3847 * We have to walk the chain again locked - to avoid duplicates:
3848 */
3849 chain = lookup_chain_cache(chain_key);
3850 if (chain) {
3851 graph_unlock();
3852 goto cache_hit;
3853 }
3854
3855 if (!add_chain_cache(curr, hlock, chain_key))
3856 return 0;
3857
3858 return 1;
3859}
3860
3861static int validate_chain(struct task_struct *curr,
3862 struct held_lock *hlock,
3863 int chain_head, u64 chain_key)
3864{
3865 /*
3866 * Trylock needs to maintain the stack of held locks, but it
3867 * does not add new dependencies, because trylock can be done
3868 * in any order.
3869 *
3870 * We look up the chain_key and do the O(N^2) check and update of
3871 * the dependencies only if this is a new dependency chain.
3872 * (If lookup_chain_cache_add() return with 1 it acquires
3873 * graph_lock for us)
3874 */
3875 if (!hlock->trylock && hlock->check &&
3876 lookup_chain_cache_add(curr, hlock, chain_key)) {
3877 /*
3878 * Check whether last held lock:
3879 *
3880 * - is irq-safe, if this lock is irq-unsafe
3881 * - is softirq-safe, if this lock is hardirq-unsafe
3882 *
3883 * And check whether the new lock's dependency graph
3884 * could lead back to the previous lock:
3885 *
3886 * - within the current held-lock stack
3887 * - across our accumulated lock dependency records
3888 *
3889 * any of these scenarios could lead to a deadlock.
3890 */
3891 /*
3892 * The simple case: does the current hold the same lock
3893 * already?
3894 */
3895 int ret = check_deadlock(curr, hlock);
3896
3897 if (!ret)
3898 return 0;
3899 /*
3900 * Add dependency only if this lock is not the head
3901 * of the chain, and if the new lock introduces no more
3902 * lock dependency (because we already hold a lock with the
3903 * same lock class) nor deadlock (because the nest_lock
3904 * serializes nesting locks), see the comments for
3905 * check_deadlock().
3906 */
3907 if (!chain_head && ret != 2) {
3908 if (!check_prevs_add(curr, hlock))
3909 return 0;
3910 }
3911
3912 graph_unlock();
3913 } else {
3914 /* after lookup_chain_cache_add(): */
3915 if (unlikely(!debug_locks))
3916 return 0;
3917 }
3918
3919 return 1;
3920}
3921#else
3922static inline int validate_chain(struct task_struct *curr,
3923 struct held_lock *hlock,
3924 int chain_head, u64 chain_key)
3925{
3926 return 1;
3927}
3928
3929static void init_chain_block_buckets(void) { }
3930#endif /* CONFIG_PROVE_LOCKING */
3931
3932/*
3933 * We are building curr_chain_key incrementally, so double-check
3934 * it from scratch, to make sure that it's done correctly:
3935 */
3936static void check_chain_key(struct task_struct *curr)
3937{
3938#ifdef CONFIG_DEBUG_LOCKDEP
3939 struct held_lock *hlock, *prev_hlock = NULL;
3940 unsigned int i;
3941 u64 chain_key = INITIAL_CHAIN_KEY;
3942
3943 for (i = 0; i < curr->lockdep_depth; i++) {
3944 hlock = curr->held_locks + i;
3945 if (chain_key != hlock->prev_chain_key) {
3946 debug_locks_off();
3947 /*
3948 * We got mighty confused, our chain keys don't match
3949 * with what we expect, someone trample on our task state?
3950 */
3951 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
3952 curr->lockdep_depth, i,
3953 (unsigned long long)chain_key,
3954 (unsigned long long)hlock->prev_chain_key);
3955 return;
3956 }
3957
3958 /*
3959 * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is
3960 * it registered lock class index?
3961 */
3962 if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use)))
3963 return;
3964
3965 if (prev_hlock && (prev_hlock->irq_context !=
3966 hlock->irq_context))
3967 chain_key = INITIAL_CHAIN_KEY;
3968 chain_key = iterate_chain_key(chain_key, hlock_id(hlock));
3969 prev_hlock = hlock;
3970 }
3971 if (chain_key != curr->curr_chain_key) {
3972 debug_locks_off();
3973 /*
3974 * More smoking hash instead of calculating it, damn see these
3975 * numbers float.. I bet that a pink elephant stepped on my memory.
3976 */
3977 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
3978 curr->lockdep_depth, i,
3979 (unsigned long long)chain_key,
3980 (unsigned long long)curr->curr_chain_key);
3981 }
3982#endif
3983}
3984
3985#ifdef CONFIG_PROVE_LOCKING
3986static int mark_lock(struct task_struct *curr, struct held_lock *this,
3987 enum lock_usage_bit new_bit);
3988
3989static void print_usage_bug_scenario(struct held_lock *lock)
3990{
3991 struct lock_class *class = hlock_class(lock);
3992
3993 printk(" Possible unsafe locking scenario:\n\n");
3994 printk(" CPU0\n");
3995 printk(" ----\n");
3996 printk(" lock(");
3997 __print_lock_name(lock, class);
3998 printk(KERN_CONT ");\n");
3999 printk(" <Interrupt>\n");
4000 printk(" lock(");
4001 __print_lock_name(lock, class);
4002 printk(KERN_CONT ");\n");
4003 printk("\n *** DEADLOCK ***\n\n");
4004}
4005
4006static void
4007print_usage_bug(struct task_struct *curr, struct held_lock *this,
4008 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
4009{
4010 if (!debug_locks_off() || debug_locks_silent)
4011 return;
4012
4013 nbcon_cpu_emergency_enter();
4014
4015 pr_warn("\n");
4016 pr_warn("================================\n");
4017 pr_warn("WARNING: inconsistent lock state\n");
4018 print_kernel_ident();
4019 pr_warn("--------------------------------\n");
4020
4021 pr_warn("inconsistent {%s} -> {%s} usage.\n",
4022 usage_str[prev_bit], usage_str[new_bit]);
4023
4024 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
4025 curr->comm, task_pid_nr(curr),
4026 lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
4027 lockdep_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
4028 lockdep_hardirqs_enabled(),
4029 lockdep_softirqs_enabled(curr));
4030 print_lock(this);
4031
4032 pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
4033 print_lock_trace(hlock_class(this)->usage_traces[prev_bit], 1);
4034
4035 print_irqtrace_events(curr);
4036 pr_warn("\nother info that might help us debug this:\n");
4037 print_usage_bug_scenario(this);
4038
4039 lockdep_print_held_locks(curr);
4040
4041 pr_warn("\nstack backtrace:\n");
4042 dump_stack();
4043
4044 nbcon_cpu_emergency_exit();
4045}
4046
4047/*
4048 * Print out an error if an invalid bit is set:
4049 */
4050static inline int
4051valid_state(struct task_struct *curr, struct held_lock *this,
4052 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
4053{
4054 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) {
4055 graph_unlock();
4056 print_usage_bug(curr, this, bad_bit, new_bit);
4057 return 0;
4058 }
4059 return 1;
4060}
4061
4062
4063/*
4064 * print irq inversion bug:
4065 */
4066static void
4067print_irq_inversion_bug(struct task_struct *curr,
4068 struct lock_list *root, struct lock_list *other,
4069 struct held_lock *this, int forwards,
4070 const char *irqclass)
4071{
4072 struct lock_list *entry = other;
4073 struct lock_list *middle = NULL;
4074 int depth;
4075
4076 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
4077 return;
4078
4079 nbcon_cpu_emergency_enter();
4080
4081 pr_warn("\n");
4082 pr_warn("========================================================\n");
4083 pr_warn("WARNING: possible irq lock inversion dependency detected\n");
4084 print_kernel_ident();
4085 pr_warn("--------------------------------------------------------\n");
4086 pr_warn("%s/%d just changed the state of lock:\n",
4087 curr->comm, task_pid_nr(curr));
4088 print_lock(this);
4089 if (forwards)
4090 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
4091 else
4092 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
4093 print_lock_name(NULL, other->class);
4094 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
4095
4096 pr_warn("\nother info that might help us debug this:\n");
4097
4098 /* Find a middle lock (if one exists) */
4099 depth = get_lock_depth(other);
4100 do {
4101 if (depth == 0 && (entry != root)) {
4102 pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
4103 break;
4104 }
4105 middle = entry;
4106 entry = get_lock_parent(entry);
4107 depth--;
4108 } while (entry && entry != root && (depth >= 0));
4109 if (forwards)
4110 print_irq_lock_scenario(root, other,
4111 middle ? middle->class : root->class, other->class);
4112 else
4113 print_irq_lock_scenario(other, root,
4114 middle ? middle->class : other->class, root->class);
4115
4116 lockdep_print_held_locks(curr);
4117
4118 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
4119 root->trace = save_trace();
4120 if (!root->trace)
4121 goto out;
4122 print_shortest_lock_dependencies(other, root);
4123
4124 pr_warn("\nstack backtrace:\n");
4125 dump_stack();
4126out:
4127 nbcon_cpu_emergency_exit();
4128}
4129
4130/*
4131 * Prove that in the forwards-direction subgraph starting at <this>
4132 * there is no lock matching <mask>:
4133 */
4134static int
4135check_usage_forwards(struct task_struct *curr, struct held_lock *this,
4136 enum lock_usage_bit bit)
4137{
4138 enum bfs_result ret;
4139 struct lock_list root;
4140 struct lock_list *target_entry;
4141 enum lock_usage_bit read_bit = bit + LOCK_USAGE_READ_MASK;
4142 unsigned usage_mask = lock_flag(bit) | lock_flag(read_bit);
4143
4144 bfs_init_root(&root, this);
4145 ret = find_usage_forwards(&root, usage_mask, &target_entry);
4146 if (bfs_error(ret)) {
4147 print_bfs_bug(ret);
4148 return 0;
4149 }
4150 if (ret == BFS_RNOMATCH)
4151 return 1;
4152
4153 /* Check whether write or read usage is the match */
4154 if (target_entry->class->usage_mask & lock_flag(bit)) {
4155 print_irq_inversion_bug(curr, &root, target_entry,
4156 this, 1, state_name(bit));
4157 } else {
4158 print_irq_inversion_bug(curr, &root, target_entry,
4159 this, 1, state_name(read_bit));
4160 }
4161
4162 return 0;
4163}
4164
4165/*
4166 * Prove that in the backwards-direction subgraph starting at <this>
4167 * there is no lock matching <mask>:
4168 */
4169static int
4170check_usage_backwards(struct task_struct *curr, struct held_lock *this,
4171 enum lock_usage_bit bit)
4172{
4173 enum bfs_result ret;
4174 struct lock_list root;
4175 struct lock_list *target_entry;
4176 enum lock_usage_bit read_bit = bit + LOCK_USAGE_READ_MASK;
4177 unsigned usage_mask = lock_flag(bit) | lock_flag(read_bit);
4178
4179 bfs_init_rootb(&root, this);
4180 ret = find_usage_backwards(&root, usage_mask, &target_entry);
4181 if (bfs_error(ret)) {
4182 print_bfs_bug(ret);
4183 return 0;
4184 }
4185 if (ret == BFS_RNOMATCH)
4186 return 1;
4187
4188 /* Check whether write or read usage is the match */
4189 if (target_entry->class->usage_mask & lock_flag(bit)) {
4190 print_irq_inversion_bug(curr, &root, target_entry,
4191 this, 0, state_name(bit));
4192 } else {
4193 print_irq_inversion_bug(curr, &root, target_entry,
4194 this, 0, state_name(read_bit));
4195 }
4196
4197 return 0;
4198}
4199
4200void print_irqtrace_events(struct task_struct *curr)
4201{
4202 const struct irqtrace_events *trace = &curr->irqtrace;
4203
4204 nbcon_cpu_emergency_enter();
4205
4206 printk("irq event stamp: %u\n", trace->irq_events);
4207 printk("hardirqs last enabled at (%u): [<%px>] %pS\n",
4208 trace->hardirq_enable_event, (void *)trace->hardirq_enable_ip,
4209 (void *)trace->hardirq_enable_ip);
4210 printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
4211 trace->hardirq_disable_event, (void *)trace->hardirq_disable_ip,
4212 (void *)trace->hardirq_disable_ip);
4213 printk("softirqs last enabled at (%u): [<%px>] %pS\n",
4214 trace->softirq_enable_event, (void *)trace->softirq_enable_ip,
4215 (void *)trace->softirq_enable_ip);
4216 printk("softirqs last disabled at (%u): [<%px>] %pS\n",
4217 trace->softirq_disable_event, (void *)trace->softirq_disable_ip,
4218 (void *)trace->softirq_disable_ip);
4219
4220 nbcon_cpu_emergency_exit();
4221}
4222
4223static int HARDIRQ_verbose(struct lock_class *class)
4224{
4225#if HARDIRQ_VERBOSE
4226 return class_filter(class);
4227#endif
4228 return 0;
4229}
4230
4231static int SOFTIRQ_verbose(struct lock_class *class)
4232{
4233#if SOFTIRQ_VERBOSE
4234 return class_filter(class);
4235#endif
4236 return 0;
4237}
4238
4239static int (*state_verbose_f[])(struct lock_class *class) = {
4240#define LOCKDEP_STATE(__STATE) \
4241 __STATE##_verbose,
4242#include "lockdep_states.h"
4243#undef LOCKDEP_STATE
4244};
4245
4246static inline int state_verbose(enum lock_usage_bit bit,
4247 struct lock_class *class)
4248{
4249 return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class);
4250}
4251
4252typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
4253 enum lock_usage_bit bit, const char *name);
4254
4255static int
4256mark_lock_irq(struct task_struct *curr, struct held_lock *this,
4257 enum lock_usage_bit new_bit)
4258{
4259 int excl_bit = exclusive_bit(new_bit);
4260 int read = new_bit & LOCK_USAGE_READ_MASK;
4261 int dir = new_bit & LOCK_USAGE_DIR_MASK;
4262
4263 /*
4264 * Validate that this particular lock does not have conflicting
4265 * usage states.
4266 */
4267 if (!valid_state(curr, this, new_bit, excl_bit))
4268 return 0;
4269
4270 /*
4271 * Check for read in write conflicts
4272 */
4273 if (!read && !valid_state(curr, this, new_bit,
4274 excl_bit + LOCK_USAGE_READ_MASK))
4275 return 0;
4276
4277
4278 /*
4279 * Validate that the lock dependencies don't have conflicting usage
4280 * states.
4281 */
4282 if (dir) {
4283 /*
4284 * mark ENABLED has to look backwards -- to ensure no dependee
4285 * has USED_IN state, which, again, would allow recursion deadlocks.
4286 */
4287 if (!check_usage_backwards(curr, this, excl_bit))
4288 return 0;
4289 } else {
4290 /*
4291 * mark USED_IN has to look forwards -- to ensure no dependency
4292 * has ENABLED state, which would allow recursion deadlocks.
4293 */
4294 if (!check_usage_forwards(curr, this, excl_bit))
4295 return 0;
4296 }
4297
4298 if (state_verbose(new_bit, hlock_class(this)))
4299 return 2;
4300
4301 return 1;
4302}
4303
4304/*
4305 * Mark all held locks with a usage bit:
4306 */
4307static int
4308mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit)
4309{
4310 struct held_lock *hlock;
4311 int i;
4312
4313 for (i = 0; i < curr->lockdep_depth; i++) {
4314 enum lock_usage_bit hlock_bit = base_bit;
4315 hlock = curr->held_locks + i;
4316
4317 if (hlock->read)
4318 hlock_bit += LOCK_USAGE_READ_MASK;
4319
4320 BUG_ON(hlock_bit >= LOCK_USAGE_STATES);
4321
4322 if (!hlock->check)
4323 continue;
4324
4325 if (!mark_lock(curr, hlock, hlock_bit))
4326 return 0;
4327 }
4328
4329 return 1;
4330}
4331
4332/*
4333 * Hardirqs will be enabled:
4334 */
4335static void __trace_hardirqs_on_caller(void)
4336{
4337 struct task_struct *curr = current;
4338
4339 /*
4340 * We are going to turn hardirqs on, so set the
4341 * usage bit for all held locks:
4342 */
4343 if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ))
4344 return;
4345 /*
4346 * If we have softirqs enabled, then set the usage
4347 * bit for all held locks. (disabled hardirqs prevented
4348 * this bit from being set before)
4349 */
4350 if (curr->softirqs_enabled)
4351 mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
4352}
4353
4354/**
4355 * lockdep_hardirqs_on_prepare - Prepare for enabling interrupts
4356 *
4357 * Invoked before a possible transition to RCU idle from exit to user or
4358 * guest mode. This ensures that all RCU operations are done before RCU
4359 * stops watching. After the RCU transition lockdep_hardirqs_on() has to be
4360 * invoked to set the final state.
4361 */
4362void lockdep_hardirqs_on_prepare(void)
4363{
4364 if (unlikely(!debug_locks))
4365 return;
4366
4367 /*
4368 * NMIs do not (and cannot) track lock dependencies, nothing to do.
4369 */
4370 if (unlikely(in_nmi()))
4371 return;
4372
4373 if (unlikely(this_cpu_read(lockdep_recursion)))
4374 return;
4375
4376 if (unlikely(lockdep_hardirqs_enabled())) {
4377 /*
4378 * Neither irq nor preemption are disabled here
4379 * so this is racy by nature but losing one hit
4380 * in a stat is not a big deal.
4381 */
4382 __debug_atomic_inc(redundant_hardirqs_on);
4383 return;
4384 }
4385
4386 /*
4387 * We're enabling irqs and according to our state above irqs weren't
4388 * already enabled, yet we find the hardware thinks they are in fact
4389 * enabled.. someone messed up their IRQ state tracing.
4390 */
4391 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4392 return;
4393
4394 /*
4395 * See the fine text that goes along with this variable definition.
4396 */
4397 if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled))
4398 return;
4399
4400 /*
4401 * Can't allow enabling interrupts while in an interrupt handler,
4402 * that's general bad form and such. Recursion, limited stack etc..
4403 */
4404 if (DEBUG_LOCKS_WARN_ON(lockdep_hardirq_context()))
4405 return;
4406
4407 current->hardirq_chain_key = current->curr_chain_key;
4408
4409 lockdep_recursion_inc();
4410 __trace_hardirqs_on_caller();
4411 lockdep_recursion_finish();
4412}
4413EXPORT_SYMBOL_GPL(lockdep_hardirqs_on_prepare);
4414
4415void noinstr lockdep_hardirqs_on(unsigned long ip)
4416{
4417 struct irqtrace_events *trace = &current->irqtrace;
4418
4419 if (unlikely(!debug_locks))
4420 return;
4421
4422 /*
4423 * NMIs can happen in the middle of local_irq_{en,dis}able() where the
4424 * tracking state and hardware state are out of sync.
4425 *
4426 * NMIs must save lockdep_hardirqs_enabled() to restore IRQ state from,
4427 * and not rely on hardware state like normal interrupts.
4428 */
4429 if (unlikely(in_nmi())) {
4430 if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
4431 return;
4432
4433 /*
4434 * Skip:
4435 * - recursion check, because NMI can hit lockdep;
4436 * - hardware state check, because above;
4437 * - chain_key check, see lockdep_hardirqs_on_prepare().
4438 */
4439 goto skip_checks;
4440 }
4441
4442 if (unlikely(this_cpu_read(lockdep_recursion)))
4443 return;
4444
4445 if (lockdep_hardirqs_enabled()) {
4446 /*
4447 * Neither irq nor preemption are disabled here
4448 * so this is racy by nature but losing one hit
4449 * in a stat is not a big deal.
4450 */
4451 __debug_atomic_inc(redundant_hardirqs_on);
4452 return;
4453 }
4454
4455 /*
4456 * We're enabling irqs and according to our state above irqs weren't
4457 * already enabled, yet we find the hardware thinks they are in fact
4458 * enabled.. someone messed up their IRQ state tracing.
4459 */
4460 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4461 return;
4462
4463 /*
4464 * Ensure the lock stack remained unchanged between
4465 * lockdep_hardirqs_on_prepare() and lockdep_hardirqs_on().
4466 */
4467 DEBUG_LOCKS_WARN_ON(current->hardirq_chain_key !=
4468 current->curr_chain_key);
4469
4470skip_checks:
4471 /* we'll do an OFF -> ON transition: */
4472 __this_cpu_write(hardirqs_enabled, 1);
4473 trace->hardirq_enable_ip = ip;
4474 trace->hardirq_enable_event = ++trace->irq_events;
4475 debug_atomic_inc(hardirqs_on_events);
4476}
4477EXPORT_SYMBOL_GPL(lockdep_hardirqs_on);
4478
4479/*
4480 * Hardirqs were disabled:
4481 */
4482void noinstr lockdep_hardirqs_off(unsigned long ip)
4483{
4484 if (unlikely(!debug_locks))
4485 return;
4486
4487 /*
4488 * Matching lockdep_hardirqs_on(), allow NMIs in the middle of lockdep;
4489 * they will restore the software state. This ensures the software
4490 * state is consistent inside NMIs as well.
4491 */
4492 if (in_nmi()) {
4493 if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
4494 return;
4495 } else if (__this_cpu_read(lockdep_recursion))
4496 return;
4497
4498 /*
4499 * So we're supposed to get called after you mask local IRQs, but for
4500 * some reason the hardware doesn't quite think you did a proper job.
4501 */
4502 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4503 return;
4504
4505 if (lockdep_hardirqs_enabled()) {
4506 struct irqtrace_events *trace = &current->irqtrace;
4507
4508 /*
4509 * We have done an ON -> OFF transition:
4510 */
4511 __this_cpu_write(hardirqs_enabled, 0);
4512 trace->hardirq_disable_ip = ip;
4513 trace->hardirq_disable_event = ++trace->irq_events;
4514 debug_atomic_inc(hardirqs_off_events);
4515 } else {
4516 debug_atomic_inc(redundant_hardirqs_off);
4517 }
4518}
4519EXPORT_SYMBOL_GPL(lockdep_hardirqs_off);
4520
4521/*
4522 * Softirqs will be enabled:
4523 */
4524void lockdep_softirqs_on(unsigned long ip)
4525{
4526 struct irqtrace_events *trace = &current->irqtrace;
4527
4528 if (unlikely(!lockdep_enabled()))
4529 return;
4530
4531 /*
4532 * We fancy IRQs being disabled here, see softirq.c, avoids
4533 * funny state and nesting things.
4534 */
4535 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4536 return;
4537
4538 if (current->softirqs_enabled) {
4539 debug_atomic_inc(redundant_softirqs_on);
4540 return;
4541 }
4542
4543 lockdep_recursion_inc();
4544 /*
4545 * We'll do an OFF -> ON transition:
4546 */
4547 current->softirqs_enabled = 1;
4548 trace->softirq_enable_ip = ip;
4549 trace->softirq_enable_event = ++trace->irq_events;
4550 debug_atomic_inc(softirqs_on_events);
4551 /*
4552 * We are going to turn softirqs on, so set the
4553 * usage bit for all held locks, if hardirqs are
4554 * enabled too:
4555 */
4556 if (lockdep_hardirqs_enabled())
4557 mark_held_locks(current, LOCK_ENABLED_SOFTIRQ);
4558 lockdep_recursion_finish();
4559}
4560
4561/*
4562 * Softirqs were disabled:
4563 */
4564void lockdep_softirqs_off(unsigned long ip)
4565{
4566 if (unlikely(!lockdep_enabled()))
4567 return;
4568
4569 /*
4570 * We fancy IRQs being disabled here, see softirq.c
4571 */
4572 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4573 return;
4574
4575 if (current->softirqs_enabled) {
4576 struct irqtrace_events *trace = &current->irqtrace;
4577
4578 /*
4579 * We have done an ON -> OFF transition:
4580 */
4581 current->softirqs_enabled = 0;
4582 trace->softirq_disable_ip = ip;
4583 trace->softirq_disable_event = ++trace->irq_events;
4584 debug_atomic_inc(softirqs_off_events);
4585 /*
4586 * Whoops, we wanted softirqs off, so why aren't they?
4587 */
4588 DEBUG_LOCKS_WARN_ON(!softirq_count());
4589 } else
4590 debug_atomic_inc(redundant_softirqs_off);
4591}
4592
4593/**
4594 * lockdep_cleanup_dead_cpu - Ensure CPU lockdep state is cleanly stopped
4595 *
4596 * @cpu: index of offlined CPU
4597 * @idle: task pointer for offlined CPU's idle thread
4598 *
4599 * Invoked after the CPU is dead. Ensures that the tracing infrastructure
4600 * is left in a suitable state for the CPU to be subsequently brought
4601 * online again.
4602 */
4603void lockdep_cleanup_dead_cpu(unsigned int cpu, struct task_struct *idle)
4604{
4605 if (unlikely(!debug_locks))
4606 return;
4607
4608 if (unlikely(per_cpu(hardirqs_enabled, cpu))) {
4609 pr_warn("CPU %u left hardirqs enabled!", cpu);
4610 if (idle)
4611 print_irqtrace_events(idle);
4612 /* Clean it up for when the CPU comes online again. */
4613 per_cpu(hardirqs_enabled, cpu) = 0;
4614 }
4615}
4616
4617static int
4618mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
4619{
4620 if (!check)
4621 goto lock_used;
4622
4623 /*
4624 * If non-trylock use in a hardirq or softirq context, then
4625 * mark the lock as used in these contexts:
4626 */
4627 if (!hlock->trylock) {
4628 if (hlock->read) {
4629 if (lockdep_hardirq_context())
4630 if (!mark_lock(curr, hlock,
4631 LOCK_USED_IN_HARDIRQ_READ))
4632 return 0;
4633 if (curr->softirq_context)
4634 if (!mark_lock(curr, hlock,
4635 LOCK_USED_IN_SOFTIRQ_READ))
4636 return 0;
4637 } else {
4638 if (lockdep_hardirq_context())
4639 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
4640 return 0;
4641 if (curr->softirq_context)
4642 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
4643 return 0;
4644 }
4645 }
4646
4647 /*
4648 * For lock_sync(), don't mark the ENABLED usage, since lock_sync()
4649 * creates no critical section and no extra dependency can be introduced
4650 * by interrupts
4651 */
4652 if (!hlock->hardirqs_off && !hlock->sync) {
4653 if (hlock->read) {
4654 if (!mark_lock(curr, hlock,
4655 LOCK_ENABLED_HARDIRQ_READ))
4656 return 0;
4657 if (curr->softirqs_enabled)
4658 if (!mark_lock(curr, hlock,
4659 LOCK_ENABLED_SOFTIRQ_READ))
4660 return 0;
4661 } else {
4662 if (!mark_lock(curr, hlock,
4663 LOCK_ENABLED_HARDIRQ))
4664 return 0;
4665 if (curr->softirqs_enabled)
4666 if (!mark_lock(curr, hlock,
4667 LOCK_ENABLED_SOFTIRQ))
4668 return 0;
4669 }
4670 }
4671
4672lock_used:
4673 /* mark it as used: */
4674 if (!mark_lock(curr, hlock, LOCK_USED))
4675 return 0;
4676
4677 return 1;
4678}
4679
4680static inline unsigned int task_irq_context(struct task_struct *task)
4681{
4682 return LOCK_CHAIN_HARDIRQ_CONTEXT * !!lockdep_hardirq_context() +
4683 LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context;
4684}
4685
4686static int separate_irq_context(struct task_struct *curr,
4687 struct held_lock *hlock)
4688{
4689 unsigned int depth = curr->lockdep_depth;
4690
4691 /*
4692 * Keep track of points where we cross into an interrupt context:
4693 */
4694 if (depth) {
4695 struct held_lock *prev_hlock;
4696
4697 prev_hlock = curr->held_locks + depth-1;
4698 /*
4699 * If we cross into another context, reset the
4700 * hash key (this also prevents the checking and the
4701 * adding of the dependency to 'prev'):
4702 */
4703 if (prev_hlock->irq_context != hlock->irq_context)
4704 return 1;
4705 }
4706 return 0;
4707}
4708
4709/*
4710 * Mark a lock with a usage bit, and validate the state transition:
4711 */
4712static int mark_lock(struct task_struct *curr, struct held_lock *this,
4713 enum lock_usage_bit new_bit)
4714{
4715 unsigned int new_mask, ret = 1;
4716
4717 if (new_bit >= LOCK_USAGE_STATES) {
4718 DEBUG_LOCKS_WARN_ON(1);
4719 return 0;
4720 }
4721
4722 if (new_bit == LOCK_USED && this->read)
4723 new_bit = LOCK_USED_READ;
4724
4725 new_mask = 1 << new_bit;
4726
4727 /*
4728 * If already set then do not dirty the cacheline,
4729 * nor do any checks:
4730 */
4731 if (likely(hlock_class(this)->usage_mask & new_mask))
4732 return 1;
4733
4734 if (!graph_lock())
4735 return 0;
4736 /*
4737 * Make sure we didn't race:
4738 */
4739 if (unlikely(hlock_class(this)->usage_mask & new_mask))
4740 goto unlock;
4741
4742 if (!hlock_class(this)->usage_mask)
4743 debug_atomic_dec(nr_unused_locks);
4744
4745 hlock_class(this)->usage_mask |= new_mask;
4746
4747 if (new_bit < LOCK_TRACE_STATES) {
4748 if (!(hlock_class(this)->usage_traces[new_bit] = save_trace()))
4749 return 0;
4750 }
4751
4752 if (new_bit < LOCK_USED) {
4753 ret = mark_lock_irq(curr, this, new_bit);
4754 if (!ret)
4755 return 0;
4756 }
4757
4758unlock:
4759 graph_unlock();
4760
4761 /*
4762 * We must printk outside of the graph_lock:
4763 */
4764 if (ret == 2) {
4765 nbcon_cpu_emergency_enter();
4766 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
4767 print_lock(this);
4768 print_irqtrace_events(curr);
4769 dump_stack();
4770 nbcon_cpu_emergency_exit();
4771 }
4772
4773 return ret;
4774}
4775
4776static inline short task_wait_context(struct task_struct *curr)
4777{
4778 /*
4779 * Set appropriate wait type for the context; for IRQs we have to take
4780 * into account force_irqthread as that is implied by PREEMPT_RT.
4781 */
4782 if (lockdep_hardirq_context()) {
4783 /*
4784 * Check if force_irqthreads will run us threaded.
4785 */
4786 if (curr->hardirq_threaded || curr->irq_config)
4787 return LD_WAIT_CONFIG;
4788
4789 return LD_WAIT_SPIN;
4790 } else if (curr->softirq_context) {
4791 /*
4792 * Softirqs are always threaded.
4793 */
4794 return LD_WAIT_CONFIG;
4795 }
4796
4797 return LD_WAIT_MAX;
4798}
4799
4800static int
4801print_lock_invalid_wait_context(struct task_struct *curr,
4802 struct held_lock *hlock)
4803{
4804 short curr_inner;
4805
4806 if (!debug_locks_off())
4807 return 0;
4808 if (debug_locks_silent)
4809 return 0;
4810
4811 nbcon_cpu_emergency_enter();
4812
4813 pr_warn("\n");
4814 pr_warn("=============================\n");
4815 pr_warn("[ BUG: Invalid wait context ]\n");
4816 print_kernel_ident();
4817 pr_warn("-----------------------------\n");
4818
4819 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
4820 print_lock(hlock);
4821
4822 pr_warn("other info that might help us debug this:\n");
4823
4824 curr_inner = task_wait_context(curr);
4825 pr_warn("context-{%d:%d}\n", curr_inner, curr_inner);
4826
4827 lockdep_print_held_locks(curr);
4828
4829 pr_warn("stack backtrace:\n");
4830 dump_stack();
4831
4832 nbcon_cpu_emergency_exit();
4833
4834 return 0;
4835}
4836
4837/*
4838 * Verify the wait_type context.
4839 *
4840 * This check validates we take locks in the right wait-type order; that is it
4841 * ensures that we do not take mutexes inside spinlocks and do not attempt to
4842 * acquire spinlocks inside raw_spinlocks and the sort.
4843 *
4844 * The entire thing is slightly more complex because of RCU, RCU is a lock that
4845 * can be taken from (pretty much) any context but also has constraints.
4846 * However when taken in a stricter environment the RCU lock does not loosen
4847 * the constraints.
4848 *
4849 * Therefore we must look for the strictest environment in the lock stack and
4850 * compare that to the lock we're trying to acquire.
4851 */
4852static int check_wait_context(struct task_struct *curr, struct held_lock *next)
4853{
4854 u8 next_inner = hlock_class(next)->wait_type_inner;
4855 u8 next_outer = hlock_class(next)->wait_type_outer;
4856 u8 curr_inner;
4857 int depth;
4858
4859 if (!next_inner || next->trylock)
4860 return 0;
4861
4862 if (!next_outer)
4863 next_outer = next_inner;
4864
4865 /*
4866 * Find start of current irq_context..
4867 */
4868 for (depth = curr->lockdep_depth - 1; depth >= 0; depth--) {
4869 struct held_lock *prev = curr->held_locks + depth;
4870 if (prev->irq_context != next->irq_context)
4871 break;
4872 }
4873 depth++;
4874
4875 curr_inner = task_wait_context(curr);
4876
4877 for (; depth < curr->lockdep_depth; depth++) {
4878 struct held_lock *prev = curr->held_locks + depth;
4879 struct lock_class *class = hlock_class(prev);
4880 u8 prev_inner = class->wait_type_inner;
4881
4882 if (prev_inner) {
4883 /*
4884 * We can have a bigger inner than a previous one
4885 * when outer is smaller than inner, as with RCU.
4886 *
4887 * Also due to trylocks.
4888 */
4889 curr_inner = min(curr_inner, prev_inner);
4890
4891 /*
4892 * Allow override for annotations -- this is typically
4893 * only valid/needed for code that only exists when
4894 * CONFIG_PREEMPT_RT=n.
4895 */
4896 if (unlikely(class->lock_type == LD_LOCK_WAIT_OVERRIDE))
4897 curr_inner = prev_inner;
4898 }
4899 }
4900
4901 if (next_outer > curr_inner)
4902 return print_lock_invalid_wait_context(curr, next);
4903
4904 return 0;
4905}
4906
4907#else /* CONFIG_PROVE_LOCKING */
4908
4909static inline int
4910mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
4911{
4912 return 1;
4913}
4914
4915static inline unsigned int task_irq_context(struct task_struct *task)
4916{
4917 return 0;
4918}
4919
4920static inline int separate_irq_context(struct task_struct *curr,
4921 struct held_lock *hlock)
4922{
4923 return 0;
4924}
4925
4926static inline int check_wait_context(struct task_struct *curr,
4927 struct held_lock *next)
4928{
4929 return 0;
4930}
4931
4932#endif /* CONFIG_PROVE_LOCKING */
4933
4934/*
4935 * Initialize a lock instance's lock-class mapping info:
4936 */
4937void lockdep_init_map_type(struct lockdep_map *lock, const char *name,
4938 struct lock_class_key *key, int subclass,
4939 u8 inner, u8 outer, u8 lock_type)
4940{
4941 int i;
4942
4943 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
4944 lock->class_cache[i] = NULL;
4945
4946#ifdef CONFIG_LOCK_STAT
4947 lock->cpu = raw_smp_processor_id();
4948#endif
4949
4950 /*
4951 * Can't be having no nameless bastards around this place!
4952 */
4953 if (DEBUG_LOCKS_WARN_ON(!name)) {
4954 lock->name = "NULL";
4955 return;
4956 }
4957
4958 lock->name = name;
4959
4960 lock->wait_type_outer = outer;
4961 lock->wait_type_inner = inner;
4962 lock->lock_type = lock_type;
4963
4964 /*
4965 * No key, no joy, we need to hash something.
4966 */
4967 if (DEBUG_LOCKS_WARN_ON(!key))
4968 return;
4969 /*
4970 * Sanity check, the lock-class key must either have been allocated
4971 * statically or must have been registered as a dynamic key.
4972 */
4973 if (!static_obj(key) && !is_dynamic_key(key)) {
4974 if (debug_locks)
4975 printk(KERN_ERR "BUG: key %px has not been registered!\n", key);
4976 DEBUG_LOCKS_WARN_ON(1);
4977 return;
4978 }
4979 lock->key = key;
4980
4981 if (unlikely(!debug_locks))
4982 return;
4983
4984 if (subclass) {
4985 unsigned long flags;
4986
4987 if (DEBUG_LOCKS_WARN_ON(!lockdep_enabled()))
4988 return;
4989
4990 raw_local_irq_save(flags);
4991 lockdep_recursion_inc();
4992 register_lock_class(lock, subclass, 1);
4993 lockdep_recursion_finish();
4994 raw_local_irq_restore(flags);
4995 }
4996}
4997EXPORT_SYMBOL_GPL(lockdep_init_map_type);
4998
4999struct lock_class_key __lockdep_no_validate__;
5000EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
5001
5002struct lock_class_key __lockdep_no_track__;
5003EXPORT_SYMBOL_GPL(__lockdep_no_track__);
5004
5005#ifdef CONFIG_PROVE_LOCKING
5006void lockdep_set_lock_cmp_fn(struct lockdep_map *lock, lock_cmp_fn cmp_fn,
5007 lock_print_fn print_fn)
5008{
5009 struct lock_class *class = lock->class_cache[0];
5010 unsigned long flags;
5011
5012 raw_local_irq_save(flags);
5013 lockdep_recursion_inc();
5014
5015 if (!class)
5016 class = register_lock_class(lock, 0, 0);
5017
5018 if (class) {
5019 WARN_ON(class->cmp_fn && class->cmp_fn != cmp_fn);
5020 WARN_ON(class->print_fn && class->print_fn != print_fn);
5021
5022 class->cmp_fn = cmp_fn;
5023 class->print_fn = print_fn;
5024 }
5025
5026 lockdep_recursion_finish();
5027 raw_local_irq_restore(flags);
5028}
5029EXPORT_SYMBOL_GPL(lockdep_set_lock_cmp_fn);
5030#endif
5031
5032static void
5033print_lock_nested_lock_not_held(struct task_struct *curr,
5034 struct held_lock *hlock)
5035{
5036 if (!debug_locks_off())
5037 return;
5038 if (debug_locks_silent)
5039 return;
5040
5041 nbcon_cpu_emergency_enter();
5042
5043 pr_warn("\n");
5044 pr_warn("==================================\n");
5045 pr_warn("WARNING: Nested lock was not taken\n");
5046 print_kernel_ident();
5047 pr_warn("----------------------------------\n");
5048
5049 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
5050 print_lock(hlock);
5051
5052 pr_warn("\nbut this task is not holding:\n");
5053 pr_warn("%s\n", hlock->nest_lock->name);
5054
5055 pr_warn("\nstack backtrace:\n");
5056 dump_stack();
5057
5058 pr_warn("\nother info that might help us debug this:\n");
5059 lockdep_print_held_locks(curr);
5060
5061 pr_warn("\nstack backtrace:\n");
5062 dump_stack();
5063
5064 nbcon_cpu_emergency_exit();
5065}
5066
5067static int __lock_is_held(const struct lockdep_map *lock, int read);
5068
5069/*
5070 * This gets called for every mutex_lock*()/spin_lock*() operation.
5071 * We maintain the dependency maps and validate the locking attempt:
5072 *
5073 * The callers must make sure that IRQs are disabled before calling it,
5074 * otherwise we could get an interrupt which would want to take locks,
5075 * which would end up in lockdep again.
5076 */
5077static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
5078 int trylock, int read, int check, int hardirqs_off,
5079 struct lockdep_map *nest_lock, unsigned long ip,
5080 int references, int pin_count, int sync)
5081{
5082 struct task_struct *curr = current;
5083 struct lock_class *class = NULL;
5084 struct held_lock *hlock;
5085 unsigned int depth;
5086 int chain_head = 0;
5087 int class_idx;
5088 u64 chain_key;
5089
5090 if (unlikely(!debug_locks))
5091 return 0;
5092
5093 if (unlikely(lock->key == &__lockdep_no_track__))
5094 return 0;
5095
5096 lockevent_inc(lockdep_acquire);
5097
5098 if (!prove_locking || lock->key == &__lockdep_no_validate__) {
5099 check = 0;
5100 lockevent_inc(lockdep_nocheck);
5101 }
5102
5103 if (DEBUG_LOCKS_WARN_ON(subclass >= MAX_LOCKDEP_SUBCLASSES))
5104 return 0;
5105
5106 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
5107 class = lock->class_cache[subclass];
5108 /*
5109 * Not cached?
5110 */
5111 if (unlikely(!class)) {
5112 class = register_lock_class(lock, subclass, 0);
5113 if (!class)
5114 return 0;
5115 }
5116
5117 debug_class_ops_inc(class);
5118
5119 if (very_verbose(class)) {
5120 nbcon_cpu_emergency_enter();
5121 printk("\nacquire class [%px] %s", class->key, class->name);
5122 if (class->name_version > 1)
5123 printk(KERN_CONT "#%d", class->name_version);
5124 printk(KERN_CONT "\n");
5125 dump_stack();
5126 nbcon_cpu_emergency_exit();
5127 }
5128
5129 /*
5130 * Add the lock to the list of currently held locks.
5131 * (we dont increase the depth just yet, up until the
5132 * dependency checks are done)
5133 */
5134 depth = curr->lockdep_depth;
5135 /*
5136 * Ran out of static storage for our per-task lock stack again have we?
5137 */
5138 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
5139 return 0;
5140
5141 class_idx = class - lock_classes;
5142
5143 if (depth && !sync) {
5144 /* we're holding locks and the new held lock is not a sync */
5145 hlock = curr->held_locks + depth - 1;
5146 if (hlock->class_idx == class_idx && nest_lock) {
5147 if (!references)
5148 references++;
5149
5150 if (!hlock->references)
5151 hlock->references++;
5152
5153 hlock->references += references;
5154
5155 /* Overflow */
5156 if (DEBUG_LOCKS_WARN_ON(hlock->references < references))
5157 return 0;
5158
5159 return 2;
5160 }
5161 }
5162
5163 hlock = curr->held_locks + depth;
5164 /*
5165 * Plain impossible, we just registered it and checked it weren't no
5166 * NULL like.. I bet this mushroom I ate was good!
5167 */
5168 if (DEBUG_LOCKS_WARN_ON(!class))
5169 return 0;
5170 hlock->class_idx = class_idx;
5171 hlock->acquire_ip = ip;
5172 hlock->instance = lock;
5173 hlock->nest_lock = nest_lock;
5174 hlock->irq_context = task_irq_context(curr);
5175 hlock->trylock = trylock;
5176 hlock->read = read;
5177 hlock->check = check;
5178 hlock->sync = !!sync;
5179 hlock->hardirqs_off = !!hardirqs_off;
5180 hlock->references = references;
5181#ifdef CONFIG_LOCK_STAT
5182 hlock->waittime_stamp = 0;
5183 hlock->holdtime_stamp = lockstat_clock();
5184#endif
5185 hlock->pin_count = pin_count;
5186
5187 if (check_wait_context(curr, hlock))
5188 return 0;
5189
5190 /* Initialize the lock usage bit */
5191 if (!mark_usage(curr, hlock, check))
5192 return 0;
5193
5194 /*
5195 * Calculate the chain hash: it's the combined hash of all the
5196 * lock keys along the dependency chain. We save the hash value
5197 * at every step so that we can get the current hash easily
5198 * after unlock. The chain hash is then used to cache dependency
5199 * results.
5200 *
5201 * The 'key ID' is what is the most compact key value to drive
5202 * the hash, not class->key.
5203 */
5204 /*
5205 * Whoops, we did it again.. class_idx is invalid.
5206 */
5207 if (DEBUG_LOCKS_WARN_ON(!test_bit(class_idx, lock_classes_in_use)))
5208 return 0;
5209
5210 chain_key = curr->curr_chain_key;
5211 if (!depth) {
5212 /*
5213 * How can we have a chain hash when we ain't got no keys?!
5214 */
5215 if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY))
5216 return 0;
5217 chain_head = 1;
5218 }
5219
5220 hlock->prev_chain_key = chain_key;
5221 if (separate_irq_context(curr, hlock)) {
5222 chain_key = INITIAL_CHAIN_KEY;
5223 chain_head = 1;
5224 }
5225 chain_key = iterate_chain_key(chain_key, hlock_id(hlock));
5226
5227 if (nest_lock && !__lock_is_held(nest_lock, -1)) {
5228 print_lock_nested_lock_not_held(curr, hlock);
5229 return 0;
5230 }
5231
5232 if (!debug_locks_silent) {
5233 WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key);
5234 WARN_ON_ONCE(!hlock_class(hlock)->key);
5235 }
5236
5237 if (!validate_chain(curr, hlock, chain_head, chain_key))
5238 return 0;
5239
5240 /* For lock_sync(), we are done here since no actual critical section */
5241 if (hlock->sync)
5242 return 1;
5243
5244 curr->curr_chain_key = chain_key;
5245 curr->lockdep_depth++;
5246 check_chain_key(curr);
5247#ifdef CONFIG_DEBUG_LOCKDEP
5248 if (unlikely(!debug_locks))
5249 return 0;
5250#endif
5251 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
5252 debug_locks_off();
5253 nbcon_cpu_emergency_enter();
5254 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
5255 printk(KERN_DEBUG "depth: %i max: %lu!\n",
5256 curr->lockdep_depth, MAX_LOCK_DEPTH);
5257
5258 lockdep_print_held_locks(current);
5259 debug_show_all_locks();
5260 dump_stack();
5261 nbcon_cpu_emergency_exit();
5262
5263 return 0;
5264 }
5265
5266 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
5267 max_lockdep_depth = curr->lockdep_depth;
5268
5269 return 1;
5270}
5271
5272static void print_unlock_imbalance_bug(struct task_struct *curr,
5273 struct lockdep_map *lock,
5274 unsigned long ip)
5275{
5276 if (!debug_locks_off())
5277 return;
5278 if (debug_locks_silent)
5279 return;
5280
5281 nbcon_cpu_emergency_enter();
5282
5283 pr_warn("\n");
5284 pr_warn("=====================================\n");
5285 pr_warn("WARNING: bad unlock balance detected!\n");
5286 print_kernel_ident();
5287 pr_warn("-------------------------------------\n");
5288 pr_warn("%s/%d is trying to release lock (",
5289 curr->comm, task_pid_nr(curr));
5290 print_lockdep_cache(lock);
5291 pr_cont(") at:\n");
5292 print_ip_sym(KERN_WARNING, ip);
5293 pr_warn("but there are no more locks to release!\n");
5294 pr_warn("\nother info that might help us debug this:\n");
5295 lockdep_print_held_locks(curr);
5296
5297 pr_warn("\nstack backtrace:\n");
5298 dump_stack();
5299
5300 nbcon_cpu_emergency_exit();
5301}
5302
5303static noinstr int match_held_lock(const struct held_lock *hlock,
5304 const struct lockdep_map *lock)
5305{
5306 if (hlock->instance == lock)
5307 return 1;
5308
5309 if (hlock->references) {
5310 const struct lock_class *class = lock->class_cache[0];
5311
5312 if (!class)
5313 class = look_up_lock_class(lock, 0);
5314
5315 /*
5316 * If look_up_lock_class() failed to find a class, we're trying
5317 * to test if we hold a lock that has never yet been acquired.
5318 * Clearly if the lock hasn't been acquired _ever_, we're not
5319 * holding it either, so report failure.
5320 */
5321 if (!class)
5322 return 0;
5323
5324 /*
5325 * References, but not a lock we're actually ref-counting?
5326 * State got messed up, follow the sites that change ->references
5327 * and try to make sense of it.
5328 */
5329 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
5330 return 0;
5331
5332 if (hlock->class_idx == class - lock_classes)
5333 return 1;
5334 }
5335
5336 return 0;
5337}
5338
5339/* @depth must not be zero */
5340static struct held_lock *find_held_lock(struct task_struct *curr,
5341 struct lockdep_map *lock,
5342 unsigned int depth, int *idx)
5343{
5344 struct held_lock *ret, *hlock, *prev_hlock;
5345 int i;
5346
5347 i = depth - 1;
5348 hlock = curr->held_locks + i;
5349 ret = hlock;
5350 if (match_held_lock(hlock, lock))
5351 goto out;
5352
5353 ret = NULL;
5354 for (i--, prev_hlock = hlock--;
5355 i >= 0;
5356 i--, prev_hlock = hlock--) {
5357 /*
5358 * We must not cross into another context:
5359 */
5360 if (prev_hlock->irq_context != hlock->irq_context) {
5361 ret = NULL;
5362 break;
5363 }
5364 if (match_held_lock(hlock, lock)) {
5365 ret = hlock;
5366 break;
5367 }
5368 }
5369
5370out:
5371 *idx = i;
5372 return ret;
5373}
5374
5375static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
5376 int idx, unsigned int *merged)
5377{
5378 struct held_lock *hlock;
5379 int first_idx = idx;
5380
5381 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
5382 return 0;
5383
5384 for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
5385 switch (__lock_acquire(hlock->instance,
5386 hlock_class(hlock)->subclass,
5387 hlock->trylock,
5388 hlock->read, hlock->check,
5389 hlock->hardirqs_off,
5390 hlock->nest_lock, hlock->acquire_ip,
5391 hlock->references, hlock->pin_count, 0)) {
5392 case 0:
5393 return 1;
5394 case 1:
5395 break;
5396 case 2:
5397 *merged += (idx == first_idx);
5398 break;
5399 default:
5400 WARN_ON(1);
5401 return 0;
5402 }
5403 }
5404 return 0;
5405}
5406
5407static int
5408__lock_set_class(struct lockdep_map *lock, const char *name,
5409 struct lock_class_key *key, unsigned int subclass,
5410 unsigned long ip)
5411{
5412 struct task_struct *curr = current;
5413 unsigned int depth, merged = 0;
5414 struct held_lock *hlock;
5415 struct lock_class *class;
5416 int i;
5417
5418 if (unlikely(!debug_locks))
5419 return 0;
5420
5421 depth = curr->lockdep_depth;
5422 /*
5423 * This function is about (re)setting the class of a held lock,
5424 * yet we're not actually holding any locks. Naughty user!
5425 */
5426 if (DEBUG_LOCKS_WARN_ON(!depth))
5427 return 0;
5428
5429 hlock = find_held_lock(curr, lock, depth, &i);
5430 if (!hlock) {
5431 print_unlock_imbalance_bug(curr, lock, ip);
5432 return 0;
5433 }
5434
5435 lockdep_init_map_type(lock, name, key, 0,
5436 lock->wait_type_inner,
5437 lock->wait_type_outer,
5438 lock->lock_type);
5439 class = register_lock_class(lock, subclass, 0);
5440 hlock->class_idx = class - lock_classes;
5441
5442 curr->lockdep_depth = i;
5443 curr->curr_chain_key = hlock->prev_chain_key;
5444
5445 if (reacquire_held_locks(curr, depth, i, &merged))
5446 return 0;
5447
5448 /*
5449 * I took it apart and put it back together again, except now I have
5450 * these 'spare' parts.. where shall I put them.
5451 */
5452 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged))
5453 return 0;
5454 return 1;
5455}
5456
5457static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
5458{
5459 struct task_struct *curr = current;
5460 unsigned int depth, merged = 0;
5461 struct held_lock *hlock;
5462 int i;
5463
5464 if (unlikely(!debug_locks))
5465 return 0;
5466
5467 depth = curr->lockdep_depth;
5468 /*
5469 * This function is about (re)setting the class of a held lock,
5470 * yet we're not actually holding any locks. Naughty user!
5471 */
5472 if (DEBUG_LOCKS_WARN_ON(!depth))
5473 return 0;
5474
5475 hlock = find_held_lock(curr, lock, depth, &i);
5476 if (!hlock) {
5477 print_unlock_imbalance_bug(curr, lock, ip);
5478 return 0;
5479 }
5480
5481 curr->lockdep_depth = i;
5482 curr->curr_chain_key = hlock->prev_chain_key;
5483
5484 WARN(hlock->read, "downgrading a read lock");
5485 hlock->read = 1;
5486 hlock->acquire_ip = ip;
5487
5488 if (reacquire_held_locks(curr, depth, i, &merged))
5489 return 0;
5490
5491 /* Merging can't happen with unchanged classes.. */
5492 if (DEBUG_LOCKS_WARN_ON(merged))
5493 return 0;
5494
5495 /*
5496 * I took it apart and put it back together again, except now I have
5497 * these 'spare' parts.. where shall I put them.
5498 */
5499 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
5500 return 0;
5501
5502 return 1;
5503}
5504
5505/*
5506 * Remove the lock from the list of currently held locks - this gets
5507 * called on mutex_unlock()/spin_unlock*() (or on a failed
5508 * mutex_lock_interruptible()).
5509 */
5510static int
5511__lock_release(struct lockdep_map *lock, unsigned long ip)
5512{
5513 struct task_struct *curr = current;
5514 unsigned int depth, merged = 1;
5515 struct held_lock *hlock;
5516 int i;
5517
5518 if (unlikely(!debug_locks))
5519 return 0;
5520
5521 depth = curr->lockdep_depth;
5522 /*
5523 * So we're all set to release this lock.. wait what lock? We don't
5524 * own any locks, you've been drinking again?
5525 */
5526 if (depth <= 0) {
5527 print_unlock_imbalance_bug(curr, lock, ip);
5528 return 0;
5529 }
5530
5531 /*
5532 * Check whether the lock exists in the current stack
5533 * of held locks:
5534 */
5535 hlock = find_held_lock(curr, lock, depth, &i);
5536 if (!hlock) {
5537 print_unlock_imbalance_bug(curr, lock, ip);
5538 return 0;
5539 }
5540
5541 if (hlock->instance == lock)
5542 lock_release_holdtime(hlock);
5543
5544 WARN(hlock->pin_count, "releasing a pinned lock\n");
5545
5546 if (hlock->references) {
5547 hlock->references--;
5548 if (hlock->references) {
5549 /*
5550 * We had, and after removing one, still have
5551 * references, the current lock stack is still
5552 * valid. We're done!
5553 */
5554 return 1;
5555 }
5556 }
5557
5558 /*
5559 * We have the right lock to unlock, 'hlock' points to it.
5560 * Now we remove it from the stack, and add back the other
5561 * entries (if any), recalculating the hash along the way:
5562 */
5563
5564 curr->lockdep_depth = i;
5565 curr->curr_chain_key = hlock->prev_chain_key;
5566
5567 /*
5568 * The most likely case is when the unlock is on the innermost
5569 * lock. In this case, we are done!
5570 */
5571 if (i == depth-1)
5572 return 1;
5573
5574 if (reacquire_held_locks(curr, depth, i + 1, &merged))
5575 return 0;
5576
5577 /*
5578 * We had N bottles of beer on the wall, we drank one, but now
5579 * there's not N-1 bottles of beer left on the wall...
5580 * Pouring two of the bottles together is acceptable.
5581 */
5582 DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged);
5583
5584 /*
5585 * Since reacquire_held_locks() would have called check_chain_key()
5586 * indirectly via __lock_acquire(), we don't need to do it again
5587 * on return.
5588 */
5589 return 0;
5590}
5591
5592static __always_inline
5593int __lock_is_held(const struct lockdep_map *lock, int read)
5594{
5595 struct task_struct *curr = current;
5596 int i;
5597
5598 for (i = 0; i < curr->lockdep_depth; i++) {
5599 struct held_lock *hlock = curr->held_locks + i;
5600
5601 if (match_held_lock(hlock, lock)) {
5602 if (read == -1 || !!hlock->read == read)
5603 return LOCK_STATE_HELD;
5604
5605 return LOCK_STATE_NOT_HELD;
5606 }
5607 }
5608
5609 return LOCK_STATE_NOT_HELD;
5610}
5611
5612static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
5613{
5614 struct pin_cookie cookie = NIL_COOKIE;
5615 struct task_struct *curr = current;
5616 int i;
5617
5618 if (unlikely(!debug_locks))
5619 return cookie;
5620
5621 for (i = 0; i < curr->lockdep_depth; i++) {
5622 struct held_lock *hlock = curr->held_locks + i;
5623
5624 if (match_held_lock(hlock, lock)) {
5625 /*
5626 * Grab 16bits of randomness; this is sufficient to not
5627 * be guessable and still allows some pin nesting in
5628 * our u32 pin_count.
5629 */
5630 cookie.val = 1 + (sched_clock() & 0xffff);
5631 hlock->pin_count += cookie.val;
5632 return cookie;
5633 }
5634 }
5635
5636 WARN(1, "pinning an unheld lock\n");
5637 return cookie;
5638}
5639
5640static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5641{
5642 struct task_struct *curr = current;
5643 int i;
5644
5645 if (unlikely(!debug_locks))
5646 return;
5647
5648 for (i = 0; i < curr->lockdep_depth; i++) {
5649 struct held_lock *hlock = curr->held_locks + i;
5650
5651 if (match_held_lock(hlock, lock)) {
5652 hlock->pin_count += cookie.val;
5653 return;
5654 }
5655 }
5656
5657 WARN(1, "pinning an unheld lock\n");
5658}
5659
5660static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5661{
5662 struct task_struct *curr = current;
5663 int i;
5664
5665 if (unlikely(!debug_locks))
5666 return;
5667
5668 for (i = 0; i < curr->lockdep_depth; i++) {
5669 struct held_lock *hlock = curr->held_locks + i;
5670
5671 if (match_held_lock(hlock, lock)) {
5672 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
5673 return;
5674
5675 hlock->pin_count -= cookie.val;
5676
5677 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
5678 hlock->pin_count = 0;
5679
5680 return;
5681 }
5682 }
5683
5684 WARN(1, "unpinning an unheld lock\n");
5685}
5686
5687/*
5688 * Check whether we follow the irq-flags state precisely:
5689 */
5690static noinstr void check_flags(unsigned long flags)
5691{
5692#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP)
5693 if (!debug_locks)
5694 return;
5695
5696 /* Get the warning out.. */
5697 instrumentation_begin();
5698
5699 if (irqs_disabled_flags(flags)) {
5700 if (DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())) {
5701 printk("possible reason: unannotated irqs-off.\n");
5702 }
5703 } else {
5704 if (DEBUG_LOCKS_WARN_ON(!lockdep_hardirqs_enabled())) {
5705 printk("possible reason: unannotated irqs-on.\n");
5706 }
5707 }
5708
5709#ifndef CONFIG_PREEMPT_RT
5710 /*
5711 * We dont accurately track softirq state in e.g.
5712 * hardirq contexts (such as on 4KSTACKS), so only
5713 * check if not in hardirq contexts:
5714 */
5715 if (!hardirq_count()) {
5716 if (softirq_count()) {
5717 /* like the above, but with softirqs */
5718 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
5719 } else {
5720 /* lick the above, does it taste good? */
5721 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
5722 }
5723 }
5724#endif
5725
5726 if (!debug_locks)
5727 print_irqtrace_events(current);
5728
5729 instrumentation_end();
5730#endif
5731}
5732
5733void lock_set_class(struct lockdep_map *lock, const char *name,
5734 struct lock_class_key *key, unsigned int subclass,
5735 unsigned long ip)
5736{
5737 unsigned long flags;
5738
5739 if (unlikely(!lockdep_enabled()))
5740 return;
5741
5742 raw_local_irq_save(flags);
5743 lockdep_recursion_inc();
5744 check_flags(flags);
5745 if (__lock_set_class(lock, name, key, subclass, ip))
5746 check_chain_key(current);
5747 lockdep_recursion_finish();
5748 raw_local_irq_restore(flags);
5749}
5750EXPORT_SYMBOL_GPL(lock_set_class);
5751
5752void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
5753{
5754 unsigned long flags;
5755
5756 if (unlikely(!lockdep_enabled()))
5757 return;
5758
5759 raw_local_irq_save(flags);
5760 lockdep_recursion_inc();
5761 check_flags(flags);
5762 if (__lock_downgrade(lock, ip))
5763 check_chain_key(current);
5764 lockdep_recursion_finish();
5765 raw_local_irq_restore(flags);
5766}
5767EXPORT_SYMBOL_GPL(lock_downgrade);
5768
5769/* NMI context !!! */
5770static void verify_lock_unused(struct lockdep_map *lock, struct held_lock *hlock, int subclass)
5771{
5772#ifdef CONFIG_PROVE_LOCKING
5773 struct lock_class *class = look_up_lock_class(lock, subclass);
5774 unsigned long mask = LOCKF_USED;
5775
5776 /* if it doesn't have a class (yet), it certainly hasn't been used yet */
5777 if (!class)
5778 return;
5779
5780 /*
5781 * READ locks only conflict with USED, such that if we only ever use
5782 * READ locks, there is no deadlock possible -- RCU.
5783 */
5784 if (!hlock->read)
5785 mask |= LOCKF_USED_READ;
5786
5787 if (!(class->usage_mask & mask))
5788 return;
5789
5790 hlock->class_idx = class - lock_classes;
5791
5792 print_usage_bug(current, hlock, LOCK_USED, LOCK_USAGE_STATES);
5793#endif
5794}
5795
5796static bool lockdep_nmi(void)
5797{
5798 if (raw_cpu_read(lockdep_recursion))
5799 return false;
5800
5801 if (!in_nmi())
5802 return false;
5803
5804 return true;
5805}
5806
5807/*
5808 * read_lock() is recursive if:
5809 * 1. We force lockdep think this way in selftests or
5810 * 2. The implementation is not queued read/write lock or
5811 * 3. The locker is at an in_interrupt() context.
5812 */
5813bool read_lock_is_recursive(void)
5814{
5815 return force_read_lock_recursive ||
5816 !IS_ENABLED(CONFIG_QUEUED_RWLOCKS) ||
5817 in_interrupt();
5818}
5819EXPORT_SYMBOL_GPL(read_lock_is_recursive);
5820
5821/*
5822 * We are not always called with irqs disabled - do that here,
5823 * and also avoid lockdep recursion:
5824 */
5825void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
5826 int trylock, int read, int check,
5827 struct lockdep_map *nest_lock, unsigned long ip)
5828{
5829 unsigned long flags;
5830
5831 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
5832
5833 if (!debug_locks)
5834 return;
5835
5836 /*
5837 * As KASAN instrumentation is disabled and lock_acquire() is usually
5838 * the first lockdep call when a task tries to acquire a lock, add
5839 * kasan_check_byte() here to check for use-after-free and other
5840 * memory errors.
5841 */
5842 kasan_check_byte(lock);
5843
5844 if (unlikely(!lockdep_enabled())) {
5845 /* XXX allow trylock from NMI ?!? */
5846 if (lockdep_nmi() && !trylock) {
5847 struct held_lock hlock;
5848
5849 hlock.acquire_ip = ip;
5850 hlock.instance = lock;
5851 hlock.nest_lock = nest_lock;
5852 hlock.irq_context = 2; // XXX
5853 hlock.trylock = trylock;
5854 hlock.read = read;
5855 hlock.check = check;
5856 hlock.hardirqs_off = true;
5857 hlock.references = 0;
5858
5859 verify_lock_unused(lock, &hlock, subclass);
5860 }
5861 return;
5862 }
5863
5864 raw_local_irq_save(flags);
5865 check_flags(flags);
5866
5867 lockdep_recursion_inc();
5868 __lock_acquire(lock, subclass, trylock, read, check,
5869 irqs_disabled_flags(flags), nest_lock, ip, 0, 0, 0);
5870 lockdep_recursion_finish();
5871 raw_local_irq_restore(flags);
5872}
5873EXPORT_SYMBOL_GPL(lock_acquire);
5874
5875void lock_release(struct lockdep_map *lock, unsigned long ip)
5876{
5877 unsigned long flags;
5878
5879 trace_lock_release(lock, ip);
5880
5881 if (unlikely(!lockdep_enabled() ||
5882 lock->key == &__lockdep_no_track__))
5883 return;
5884
5885 raw_local_irq_save(flags);
5886 check_flags(flags);
5887
5888 lockdep_recursion_inc();
5889 if (__lock_release(lock, ip))
5890 check_chain_key(current);
5891 lockdep_recursion_finish();
5892 raw_local_irq_restore(flags);
5893}
5894EXPORT_SYMBOL_GPL(lock_release);
5895
5896/*
5897 * lock_sync() - A special annotation for synchronize_{s,}rcu()-like API.
5898 *
5899 * No actual critical section is created by the APIs annotated with this: these
5900 * APIs are used to wait for one or multiple critical sections (on other CPUs
5901 * or threads), and it means that calling these APIs inside these critical
5902 * sections is potential deadlock.
5903 */
5904void lock_sync(struct lockdep_map *lock, unsigned subclass, int read,
5905 int check, struct lockdep_map *nest_lock, unsigned long ip)
5906{
5907 unsigned long flags;
5908
5909 if (unlikely(!lockdep_enabled()))
5910 return;
5911
5912 raw_local_irq_save(flags);
5913 check_flags(flags);
5914
5915 lockdep_recursion_inc();
5916 __lock_acquire(lock, subclass, 0, read, check,
5917 irqs_disabled_flags(flags), nest_lock, ip, 0, 0, 1);
5918 check_chain_key(current);
5919 lockdep_recursion_finish();
5920 raw_local_irq_restore(flags);
5921}
5922EXPORT_SYMBOL_GPL(lock_sync);
5923
5924noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
5925{
5926 unsigned long flags;
5927 int ret = LOCK_STATE_NOT_HELD;
5928
5929 /*
5930 * Avoid false negative lockdep_assert_held() and
5931 * lockdep_assert_not_held().
5932 */
5933 if (unlikely(!lockdep_enabled()))
5934 return LOCK_STATE_UNKNOWN;
5935
5936 raw_local_irq_save(flags);
5937 check_flags(flags);
5938
5939 lockdep_recursion_inc();
5940 ret = __lock_is_held(lock, read);
5941 lockdep_recursion_finish();
5942 raw_local_irq_restore(flags);
5943
5944 return ret;
5945}
5946EXPORT_SYMBOL_GPL(lock_is_held_type);
5947NOKPROBE_SYMBOL(lock_is_held_type);
5948
5949struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
5950{
5951 struct pin_cookie cookie = NIL_COOKIE;
5952 unsigned long flags;
5953
5954 if (unlikely(!lockdep_enabled()))
5955 return cookie;
5956
5957 raw_local_irq_save(flags);
5958 check_flags(flags);
5959
5960 lockdep_recursion_inc();
5961 cookie = __lock_pin_lock(lock);
5962 lockdep_recursion_finish();
5963 raw_local_irq_restore(flags);
5964
5965 return cookie;
5966}
5967EXPORT_SYMBOL_GPL(lock_pin_lock);
5968
5969void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5970{
5971 unsigned long flags;
5972
5973 if (unlikely(!lockdep_enabled()))
5974 return;
5975
5976 raw_local_irq_save(flags);
5977 check_flags(flags);
5978
5979 lockdep_recursion_inc();
5980 __lock_repin_lock(lock, cookie);
5981 lockdep_recursion_finish();
5982 raw_local_irq_restore(flags);
5983}
5984EXPORT_SYMBOL_GPL(lock_repin_lock);
5985
5986void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5987{
5988 unsigned long flags;
5989
5990 if (unlikely(!lockdep_enabled()))
5991 return;
5992
5993 raw_local_irq_save(flags);
5994 check_flags(flags);
5995
5996 lockdep_recursion_inc();
5997 __lock_unpin_lock(lock, cookie);
5998 lockdep_recursion_finish();
5999 raw_local_irq_restore(flags);
6000}
6001EXPORT_SYMBOL_GPL(lock_unpin_lock);
6002
6003#ifdef CONFIG_LOCK_STAT
6004static void print_lock_contention_bug(struct task_struct *curr,
6005 struct lockdep_map *lock,
6006 unsigned long ip)
6007{
6008 if (!debug_locks_off())
6009 return;
6010 if (debug_locks_silent)
6011 return;
6012
6013 nbcon_cpu_emergency_enter();
6014
6015 pr_warn("\n");
6016 pr_warn("=================================\n");
6017 pr_warn("WARNING: bad contention detected!\n");
6018 print_kernel_ident();
6019 pr_warn("---------------------------------\n");
6020 pr_warn("%s/%d is trying to contend lock (",
6021 curr->comm, task_pid_nr(curr));
6022 print_lockdep_cache(lock);
6023 pr_cont(") at:\n");
6024 print_ip_sym(KERN_WARNING, ip);
6025 pr_warn("but there are no locks held!\n");
6026 pr_warn("\nother info that might help us debug this:\n");
6027 lockdep_print_held_locks(curr);
6028
6029 pr_warn("\nstack backtrace:\n");
6030 dump_stack();
6031
6032 nbcon_cpu_emergency_exit();
6033}
6034
6035static void
6036__lock_contended(struct lockdep_map *lock, unsigned long ip)
6037{
6038 struct task_struct *curr = current;
6039 struct held_lock *hlock;
6040 struct lock_class_stats *stats;
6041 unsigned int depth;
6042 int i, contention_point, contending_point;
6043
6044 depth = curr->lockdep_depth;
6045 /*
6046 * Whee, we contended on this lock, except it seems we're not
6047 * actually trying to acquire anything much at all..
6048 */
6049 if (DEBUG_LOCKS_WARN_ON(!depth))
6050 return;
6051
6052 if (unlikely(lock->key == &__lockdep_no_track__))
6053 return;
6054
6055 hlock = find_held_lock(curr, lock, depth, &i);
6056 if (!hlock) {
6057 print_lock_contention_bug(curr, lock, ip);
6058 return;
6059 }
6060
6061 if (hlock->instance != lock)
6062 return;
6063
6064 hlock->waittime_stamp = lockstat_clock();
6065
6066 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
6067 contending_point = lock_point(hlock_class(hlock)->contending_point,
6068 lock->ip);
6069
6070 stats = get_lock_stats(hlock_class(hlock));
6071 if (contention_point < LOCKSTAT_POINTS)
6072 stats->contention_point[contention_point]++;
6073 if (contending_point < LOCKSTAT_POINTS)
6074 stats->contending_point[contending_point]++;
6075 if (lock->cpu != smp_processor_id())
6076 stats->bounces[bounce_contended + !!hlock->read]++;
6077}
6078
6079static void
6080__lock_acquired(struct lockdep_map *lock, unsigned long ip)
6081{
6082 struct task_struct *curr = current;
6083 struct held_lock *hlock;
6084 struct lock_class_stats *stats;
6085 unsigned int depth;
6086 u64 now, waittime = 0;
6087 int i, cpu;
6088
6089 depth = curr->lockdep_depth;
6090 /*
6091 * Yay, we acquired ownership of this lock we didn't try to
6092 * acquire, how the heck did that happen?
6093 */
6094 if (DEBUG_LOCKS_WARN_ON(!depth))
6095 return;
6096
6097 if (unlikely(lock->key == &__lockdep_no_track__))
6098 return;
6099
6100 hlock = find_held_lock(curr, lock, depth, &i);
6101 if (!hlock) {
6102 print_lock_contention_bug(curr, lock, _RET_IP_);
6103 return;
6104 }
6105
6106 if (hlock->instance != lock)
6107 return;
6108
6109 cpu = smp_processor_id();
6110 if (hlock->waittime_stamp) {
6111 now = lockstat_clock();
6112 waittime = now - hlock->waittime_stamp;
6113 hlock->holdtime_stamp = now;
6114 }
6115
6116 stats = get_lock_stats(hlock_class(hlock));
6117 if (waittime) {
6118 if (hlock->read)
6119 lock_time_inc(&stats->read_waittime, waittime);
6120 else
6121 lock_time_inc(&stats->write_waittime, waittime);
6122 }
6123 if (lock->cpu != cpu)
6124 stats->bounces[bounce_acquired + !!hlock->read]++;
6125
6126 lock->cpu = cpu;
6127 lock->ip = ip;
6128}
6129
6130void lock_contended(struct lockdep_map *lock, unsigned long ip)
6131{
6132 unsigned long flags;
6133
6134 trace_lock_contended(lock, ip);
6135
6136 if (unlikely(!lock_stat || !lockdep_enabled()))
6137 return;
6138
6139 raw_local_irq_save(flags);
6140 check_flags(flags);
6141 lockdep_recursion_inc();
6142 __lock_contended(lock, ip);
6143 lockdep_recursion_finish();
6144 raw_local_irq_restore(flags);
6145}
6146EXPORT_SYMBOL_GPL(lock_contended);
6147
6148void lock_acquired(struct lockdep_map *lock, unsigned long ip)
6149{
6150 unsigned long flags;
6151
6152 trace_lock_acquired(lock, ip);
6153
6154 if (unlikely(!lock_stat || !lockdep_enabled()))
6155 return;
6156
6157 raw_local_irq_save(flags);
6158 check_flags(flags);
6159 lockdep_recursion_inc();
6160 __lock_acquired(lock, ip);
6161 lockdep_recursion_finish();
6162 raw_local_irq_restore(flags);
6163}
6164EXPORT_SYMBOL_GPL(lock_acquired);
6165#endif
6166
6167/*
6168 * Used by the testsuite, sanitize the validator state
6169 * after a simulated failure:
6170 */
6171
6172void lockdep_reset(void)
6173{
6174 unsigned long flags;
6175 int i;
6176
6177 raw_local_irq_save(flags);
6178 lockdep_init_task(current);
6179 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
6180 nr_hardirq_chains = 0;
6181 nr_softirq_chains = 0;
6182 nr_process_chains = 0;
6183 debug_locks = 1;
6184 for (i = 0; i < CHAINHASH_SIZE; i++)
6185 INIT_HLIST_HEAD(chainhash_table + i);
6186 raw_local_irq_restore(flags);
6187}
6188
6189/* Remove a class from a lock chain. Must be called with the graph lock held. */
6190static void remove_class_from_lock_chain(struct pending_free *pf,
6191 struct lock_chain *chain,
6192 struct lock_class *class)
6193{
6194#ifdef CONFIG_PROVE_LOCKING
6195 int i;
6196
6197 for (i = chain->base; i < chain->base + chain->depth; i++) {
6198 if (chain_hlock_class_idx(chain_hlocks[i]) != class - lock_classes)
6199 continue;
6200 /*
6201 * Each lock class occurs at most once in a lock chain so once
6202 * we found a match we can break out of this loop.
6203 */
6204 goto free_lock_chain;
6205 }
6206 /* Since the chain has not been modified, return. */
6207 return;
6208
6209free_lock_chain:
6210 free_chain_hlocks(chain->base, chain->depth);
6211 /* Overwrite the chain key for concurrent RCU readers. */
6212 WRITE_ONCE(chain->chain_key, INITIAL_CHAIN_KEY);
6213 dec_chains(chain->irq_context);
6214
6215 /*
6216 * Note: calling hlist_del_rcu() from inside a
6217 * hlist_for_each_entry_rcu() loop is safe.
6218 */
6219 hlist_del_rcu(&chain->entry);
6220 __set_bit(chain - lock_chains, pf->lock_chains_being_freed);
6221 nr_zapped_lock_chains++;
6222#endif
6223}
6224
6225/* Must be called with the graph lock held. */
6226static void remove_class_from_lock_chains(struct pending_free *pf,
6227 struct lock_class *class)
6228{
6229 struct lock_chain *chain;
6230 struct hlist_head *head;
6231 int i;
6232
6233 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
6234 head = chainhash_table + i;
6235 hlist_for_each_entry_rcu(chain, head, entry) {
6236 remove_class_from_lock_chain(pf, chain, class);
6237 }
6238 }
6239}
6240
6241/*
6242 * Remove all references to a lock class. The caller must hold the graph lock.
6243 */
6244static void zap_class(struct pending_free *pf, struct lock_class *class)
6245{
6246 struct lock_list *entry;
6247 int i;
6248
6249 WARN_ON_ONCE(!class->key);
6250
6251 /*
6252 * Remove all dependencies this lock is
6253 * involved in:
6254 */
6255 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
6256 entry = list_entries + i;
6257 if (entry->class != class && entry->links_to != class)
6258 continue;
6259 __clear_bit(i, list_entries_in_use);
6260 nr_list_entries--;
6261 list_del_rcu(&entry->entry);
6262 }
6263 if (list_empty(&class->locks_after) &&
6264 list_empty(&class->locks_before)) {
6265 list_move_tail(&class->lock_entry, &pf->zapped);
6266 hlist_del_rcu(&class->hash_entry);
6267 WRITE_ONCE(class->key, NULL);
6268 WRITE_ONCE(class->name, NULL);
6269 /* Class allocated but not used, -1 in nr_unused_locks */
6270 if (class->usage_mask == 0)
6271 debug_atomic_dec(nr_unused_locks);
6272 nr_lock_classes--;
6273 __clear_bit(class - lock_classes, lock_classes_in_use);
6274 if (class - lock_classes == max_lock_class_idx)
6275 max_lock_class_idx--;
6276 } else {
6277 WARN_ONCE(true, "%s() failed for class %s\n", __func__,
6278 class->name);
6279 }
6280
6281 remove_class_from_lock_chains(pf, class);
6282 nr_zapped_classes++;
6283}
6284
6285static void reinit_class(struct lock_class *class)
6286{
6287 WARN_ON_ONCE(!class->lock_entry.next);
6288 WARN_ON_ONCE(!list_empty(&class->locks_after));
6289 WARN_ON_ONCE(!list_empty(&class->locks_before));
6290 memset_startat(class, 0, key);
6291 WARN_ON_ONCE(!class->lock_entry.next);
6292 WARN_ON_ONCE(!list_empty(&class->locks_after));
6293 WARN_ON_ONCE(!list_empty(&class->locks_before));
6294}
6295
6296static inline int within(const void *addr, void *start, unsigned long size)
6297{
6298 return addr >= start && addr < start + size;
6299}
6300
6301static bool inside_selftest(void)
6302{
6303 return current == lockdep_selftest_task_struct;
6304}
6305
6306/* The caller must hold the graph lock. */
6307static struct pending_free *get_pending_free(void)
6308{
6309 return delayed_free.pf + delayed_free.index;
6310}
6311
6312static void free_zapped_rcu(struct rcu_head *cb);
6313
6314/*
6315* See if we need to queue an RCU callback, must called with
6316* the lockdep lock held, returns false if either we don't have
6317* any pending free or the callback is already scheduled.
6318* Otherwise, a call_rcu() must follow this function call.
6319*/
6320static bool prepare_call_rcu_zapped(struct pending_free *pf)
6321{
6322 WARN_ON_ONCE(inside_selftest());
6323
6324 if (list_empty(&pf->zapped))
6325 return false;
6326
6327 if (delayed_free.scheduled)
6328 return false;
6329
6330 delayed_free.scheduled = true;
6331
6332 WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf);
6333 delayed_free.index ^= 1;
6334
6335 return true;
6336}
6337
6338/* The caller must hold the graph lock. May be called from RCU context. */
6339static void __free_zapped_classes(struct pending_free *pf)
6340{
6341 struct lock_class *class;
6342
6343 check_data_structures();
6344
6345 list_for_each_entry(class, &pf->zapped, lock_entry)
6346 reinit_class(class);
6347
6348 list_splice_init(&pf->zapped, &free_lock_classes);
6349
6350#ifdef CONFIG_PROVE_LOCKING
6351 bitmap_andnot(lock_chains_in_use, lock_chains_in_use,
6352 pf->lock_chains_being_freed, ARRAY_SIZE(lock_chains));
6353 bitmap_clear(pf->lock_chains_being_freed, 0, ARRAY_SIZE(lock_chains));
6354#endif
6355}
6356
6357static void free_zapped_rcu(struct rcu_head *ch)
6358{
6359 struct pending_free *pf;
6360 unsigned long flags;
6361 bool need_callback;
6362
6363 if (WARN_ON_ONCE(ch != &delayed_free.rcu_head))
6364 return;
6365
6366 raw_local_irq_save(flags);
6367 lockdep_lock();
6368
6369 /* closed head */
6370 pf = delayed_free.pf + (delayed_free.index ^ 1);
6371 __free_zapped_classes(pf);
6372 delayed_free.scheduled = false;
6373 need_callback =
6374 prepare_call_rcu_zapped(delayed_free.pf + delayed_free.index);
6375 lockdep_unlock();
6376 raw_local_irq_restore(flags);
6377
6378 /*
6379 * If there's pending free and its callback has not been scheduled,
6380 * queue an RCU callback.
6381 */
6382 if (need_callback)
6383 call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
6384
6385}
6386
6387/*
6388 * Remove all lock classes from the class hash table and from the
6389 * all_lock_classes list whose key or name is in the address range [start,
6390 * start + size). Move these lock classes to the zapped_classes list. Must
6391 * be called with the graph lock held.
6392 */
6393static void __lockdep_free_key_range(struct pending_free *pf, void *start,
6394 unsigned long size)
6395{
6396 struct lock_class *class;
6397 struct hlist_head *head;
6398 int i;
6399
6400 /* Unhash all classes that were created by a module. */
6401 for (i = 0; i < CLASSHASH_SIZE; i++) {
6402 head = classhash_table + i;
6403 hlist_for_each_entry_rcu(class, head, hash_entry) {
6404 if (!within(class->key, start, size) &&
6405 !within(class->name, start, size))
6406 continue;
6407 zap_class(pf, class);
6408 }
6409 }
6410}
6411
6412/*
6413 * Used in module.c to remove lock classes from memory that is going to be
6414 * freed; and possibly re-used by other modules.
6415 *
6416 * We will have had one synchronize_rcu() before getting here, so we're
6417 * guaranteed nobody will look up these exact classes -- they're properly dead
6418 * but still allocated.
6419 */
6420static void lockdep_free_key_range_reg(void *start, unsigned long size)
6421{
6422 struct pending_free *pf;
6423 unsigned long flags;
6424 bool need_callback;
6425
6426 init_data_structures_once();
6427
6428 raw_local_irq_save(flags);
6429 lockdep_lock();
6430 pf = get_pending_free();
6431 __lockdep_free_key_range(pf, start, size);
6432 need_callback = prepare_call_rcu_zapped(pf);
6433 lockdep_unlock();
6434 raw_local_irq_restore(flags);
6435 if (need_callback)
6436 call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
6437 /*
6438 * Wait for any possible iterators from look_up_lock_class() to pass
6439 * before continuing to free the memory they refer to.
6440 */
6441 synchronize_rcu();
6442}
6443
6444/*
6445 * Free all lockdep keys in the range [start, start+size). Does not sleep.
6446 * Ignores debug_locks. Must only be used by the lockdep selftests.
6447 */
6448static void lockdep_free_key_range_imm(void *start, unsigned long size)
6449{
6450 struct pending_free *pf = delayed_free.pf;
6451 unsigned long flags;
6452
6453 init_data_structures_once();
6454
6455 raw_local_irq_save(flags);
6456 lockdep_lock();
6457 __lockdep_free_key_range(pf, start, size);
6458 __free_zapped_classes(pf);
6459 lockdep_unlock();
6460 raw_local_irq_restore(flags);
6461}
6462
6463void lockdep_free_key_range(void *start, unsigned long size)
6464{
6465 init_data_structures_once();
6466
6467 if (inside_selftest())
6468 lockdep_free_key_range_imm(start, size);
6469 else
6470 lockdep_free_key_range_reg(start, size);
6471}
6472
6473/*
6474 * Check whether any element of the @lock->class_cache[] array refers to a
6475 * registered lock class. The caller must hold either the graph lock or the
6476 * RCU read lock.
6477 */
6478static bool lock_class_cache_is_registered(struct lockdep_map *lock)
6479{
6480 struct lock_class *class;
6481 struct hlist_head *head;
6482 int i, j;
6483
6484 for (i = 0; i < CLASSHASH_SIZE; i++) {
6485 head = classhash_table + i;
6486 hlist_for_each_entry_rcu(class, head, hash_entry) {
6487 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
6488 if (lock->class_cache[j] == class)
6489 return true;
6490 }
6491 }
6492 return false;
6493}
6494
6495/* The caller must hold the graph lock. Does not sleep. */
6496static void __lockdep_reset_lock(struct pending_free *pf,
6497 struct lockdep_map *lock)
6498{
6499 struct lock_class *class;
6500 int j;
6501
6502 /*
6503 * Remove all classes this lock might have:
6504 */
6505 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
6506 /*
6507 * If the class exists we look it up and zap it:
6508 */
6509 class = look_up_lock_class(lock, j);
6510 if (class)
6511 zap_class(pf, class);
6512 }
6513 /*
6514 * Debug check: in the end all mapped classes should
6515 * be gone.
6516 */
6517 if (WARN_ON_ONCE(lock_class_cache_is_registered(lock)))
6518 debug_locks_off();
6519}
6520
6521/*
6522 * Remove all information lockdep has about a lock if debug_locks == 1. Free
6523 * released data structures from RCU context.
6524 */
6525static void lockdep_reset_lock_reg(struct lockdep_map *lock)
6526{
6527 struct pending_free *pf;
6528 unsigned long flags;
6529 int locked;
6530 bool need_callback = false;
6531
6532 raw_local_irq_save(flags);
6533 locked = graph_lock();
6534 if (!locked)
6535 goto out_irq;
6536
6537 pf = get_pending_free();
6538 __lockdep_reset_lock(pf, lock);
6539 need_callback = prepare_call_rcu_zapped(pf);
6540
6541 graph_unlock();
6542out_irq:
6543 raw_local_irq_restore(flags);
6544 if (need_callback)
6545 call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
6546}
6547
6548/*
6549 * Reset a lock. Does not sleep. Ignores debug_locks. Must only be used by the
6550 * lockdep selftests.
6551 */
6552static void lockdep_reset_lock_imm(struct lockdep_map *lock)
6553{
6554 struct pending_free *pf = delayed_free.pf;
6555 unsigned long flags;
6556
6557 raw_local_irq_save(flags);
6558 lockdep_lock();
6559 __lockdep_reset_lock(pf, lock);
6560 __free_zapped_classes(pf);
6561 lockdep_unlock();
6562 raw_local_irq_restore(flags);
6563}
6564
6565void lockdep_reset_lock(struct lockdep_map *lock)
6566{
6567 init_data_structures_once();
6568
6569 if (inside_selftest())
6570 lockdep_reset_lock_imm(lock);
6571 else
6572 lockdep_reset_lock_reg(lock);
6573}
6574
6575/*
6576 * Unregister a dynamically allocated key.
6577 *
6578 * Unlike lockdep_register_key(), a search is always done to find a matching
6579 * key irrespective of debug_locks to avoid potential invalid access to freed
6580 * memory in lock_class entry.
6581 */
6582void lockdep_unregister_key(struct lock_class_key *key)
6583{
6584 struct hlist_head *hash_head = keyhashentry(key);
6585 struct lock_class_key *k;
6586 struct pending_free *pf;
6587 unsigned long flags;
6588 bool found = false;
6589 bool need_callback = false;
6590
6591 might_sleep();
6592
6593 if (WARN_ON_ONCE(static_obj(key)))
6594 return;
6595
6596 raw_local_irq_save(flags);
6597 lockdep_lock();
6598
6599 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
6600 if (k == key) {
6601 hlist_del_rcu(&k->hash_entry);
6602 found = true;
6603 break;
6604 }
6605 }
6606 WARN_ON_ONCE(!found && debug_locks);
6607 if (found) {
6608 pf = get_pending_free();
6609 __lockdep_free_key_range(pf, key, 1);
6610 need_callback = prepare_call_rcu_zapped(pf);
6611 nr_dynamic_keys--;
6612 }
6613 lockdep_unlock();
6614 raw_local_irq_restore(flags);
6615
6616 if (need_callback)
6617 call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
6618
6619 /*
6620 * Wait until is_dynamic_key() has finished accessing k->hash_entry.
6621 *
6622 * Some operations like __qdisc_destroy() will call this in a debug
6623 * kernel, and the network traffic is disabled while waiting, hence
6624 * the delay of the wait matters in debugging cases. Currently use a
6625 * synchronize_rcu_expedited() to speed up the wait at the cost of
6626 * system IPIs. TODO: Replace RCU with hazptr for this.
6627 */
6628 synchronize_rcu_expedited();
6629}
6630EXPORT_SYMBOL_GPL(lockdep_unregister_key);
6631
6632void __init lockdep_init(void)
6633{
6634 pr_info("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
6635
6636 pr_info("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
6637 pr_info("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
6638 pr_info("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
6639 pr_info("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
6640 pr_info("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
6641 pr_info("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
6642 pr_info("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
6643
6644 pr_info(" memory used by lock dependency info: %zu kB\n",
6645 (sizeof(lock_classes) +
6646 sizeof(lock_classes_in_use) +
6647 sizeof(classhash_table) +
6648 sizeof(list_entries) +
6649 sizeof(list_entries_in_use) +
6650 sizeof(chainhash_table) +
6651 sizeof(delayed_free)
6652#ifdef CONFIG_PROVE_LOCKING
6653 + sizeof(lock_cq)
6654 + sizeof(lock_chains)
6655 + sizeof(lock_chains_in_use)
6656 + sizeof(chain_hlocks)
6657#endif
6658 ) / 1024
6659 );
6660
6661#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
6662 pr_info(" memory used for stack traces: %zu kB\n",
6663 (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024
6664 );
6665#endif
6666
6667 pr_info(" per task-struct memory footprint: %zu bytes\n",
6668 sizeof(((struct task_struct *)NULL)->held_locks));
6669}
6670
6671static void
6672print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
6673 const void *mem_to, struct held_lock *hlock)
6674{
6675 if (!debug_locks_off())
6676 return;
6677 if (debug_locks_silent)
6678 return;
6679
6680 nbcon_cpu_emergency_enter();
6681
6682 pr_warn("\n");
6683 pr_warn("=========================\n");
6684 pr_warn("WARNING: held lock freed!\n");
6685 print_kernel_ident();
6686 pr_warn("-------------------------\n");
6687 pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
6688 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
6689 print_lock(hlock);
6690 lockdep_print_held_locks(curr);
6691
6692 pr_warn("\nstack backtrace:\n");
6693 dump_stack();
6694
6695 nbcon_cpu_emergency_exit();
6696}
6697
6698static inline int not_in_range(const void* mem_from, unsigned long mem_len,
6699 const void* lock_from, unsigned long lock_len)
6700{
6701 return lock_from + lock_len <= mem_from ||
6702 mem_from + mem_len <= lock_from;
6703}
6704
6705/*
6706 * Called when kernel memory is freed (or unmapped), or if a lock
6707 * is destroyed or reinitialized - this code checks whether there is
6708 * any held lock in the memory range of <from> to <to>:
6709 */
6710void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
6711{
6712 struct task_struct *curr = current;
6713 struct held_lock *hlock;
6714 unsigned long flags;
6715 int i;
6716
6717 if (unlikely(!debug_locks))
6718 return;
6719
6720 raw_local_irq_save(flags);
6721 for (i = 0; i < curr->lockdep_depth; i++) {
6722 hlock = curr->held_locks + i;
6723
6724 if (not_in_range(mem_from, mem_len, hlock->instance,
6725 sizeof(*hlock->instance)))
6726 continue;
6727
6728 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
6729 break;
6730 }
6731 raw_local_irq_restore(flags);
6732}
6733EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
6734
6735static void print_held_locks_bug(void)
6736{
6737 if (!debug_locks_off())
6738 return;
6739 if (debug_locks_silent)
6740 return;
6741
6742 nbcon_cpu_emergency_enter();
6743
6744 pr_warn("\n");
6745 pr_warn("====================================\n");
6746 pr_warn("WARNING: %s/%d still has locks held!\n",
6747 current->comm, task_pid_nr(current));
6748 print_kernel_ident();
6749 pr_warn("------------------------------------\n");
6750 lockdep_print_held_locks(current);
6751 pr_warn("\nstack backtrace:\n");
6752 dump_stack();
6753
6754 nbcon_cpu_emergency_exit();
6755}
6756
6757void debug_check_no_locks_held(void)
6758{
6759 if (unlikely(current->lockdep_depth > 0))
6760 print_held_locks_bug();
6761}
6762EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
6763
6764#ifdef __KERNEL__
6765void debug_show_all_locks(void)
6766{
6767 struct task_struct *g, *p;
6768
6769 if (unlikely(!debug_locks)) {
6770 pr_warn("INFO: lockdep is turned off.\n");
6771 return;
6772 }
6773 pr_warn("\nShowing all locks held in the system:\n");
6774
6775 rcu_read_lock();
6776 for_each_process_thread(g, p) {
6777 if (!p->lockdep_depth)
6778 continue;
6779 lockdep_print_held_locks(p);
6780 touch_nmi_watchdog();
6781 touch_all_softlockup_watchdogs();
6782 }
6783 rcu_read_unlock();
6784
6785 pr_warn("\n");
6786 pr_warn("=============================================\n\n");
6787}
6788EXPORT_SYMBOL_GPL(debug_show_all_locks);
6789#endif
6790
6791/*
6792 * Careful: only use this function if you are sure that
6793 * the task cannot run in parallel!
6794 */
6795void debug_show_held_locks(struct task_struct *task)
6796{
6797 if (unlikely(!debug_locks)) {
6798 printk("INFO: lockdep is turned off.\n");
6799 return;
6800 }
6801 lockdep_print_held_locks(task);
6802}
6803EXPORT_SYMBOL_GPL(debug_show_held_locks);
6804
6805asmlinkage __visible void lockdep_sys_exit(void)
6806{
6807 struct task_struct *curr = current;
6808
6809 if (unlikely(curr->lockdep_depth)) {
6810 if (!debug_locks_off())
6811 return;
6812 nbcon_cpu_emergency_enter();
6813 pr_warn("\n");
6814 pr_warn("================================================\n");
6815 pr_warn("WARNING: lock held when returning to user space!\n");
6816 print_kernel_ident();
6817 pr_warn("------------------------------------------------\n");
6818 pr_warn("%s/%d is leaving the kernel with locks still held!\n",
6819 curr->comm, curr->pid);
6820 lockdep_print_held_locks(curr);
6821 nbcon_cpu_emergency_exit();
6822 }
6823
6824 /*
6825 * The lock history for each syscall should be independent. So wipe the
6826 * slate clean on return to userspace.
6827 */
6828 lockdep_invariant_state(false);
6829}
6830
6831void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
6832{
6833 struct task_struct *curr = current;
6834 int dl = READ_ONCE(debug_locks);
6835 bool rcu = warn_rcu_enter();
6836
6837 /* Note: the following can be executed concurrently, so be careful. */
6838 nbcon_cpu_emergency_enter();
6839 pr_warn("\n");
6840 pr_warn("=============================\n");
6841 pr_warn("WARNING: suspicious RCU usage\n");
6842 print_kernel_ident();
6843 pr_warn("-----------------------------\n");
6844 pr_warn("%s:%d %s!\n", file, line, s);
6845 pr_warn("\nother info that might help us debug this:\n\n");
6846 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n%s",
6847 !rcu_lockdep_current_cpu_online()
6848 ? "RCU used illegally from offline CPU!\n"
6849 : "",
6850 rcu_scheduler_active, dl,
6851 dl ? "" : "Possible false positive due to lockdep disabling via debug_locks = 0\n");
6852
6853 /*
6854 * If a CPU is in the RCU-free window in idle (ie: in the section
6855 * between ct_idle_enter() and ct_idle_exit(), then RCU
6856 * considers that CPU to be in an "extended quiescent state",
6857 * which means that RCU will be completely ignoring that CPU.
6858 * Therefore, rcu_read_lock() and friends have absolutely no
6859 * effect on a CPU running in that state. In other words, even if
6860 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
6861 * delete data structures out from under it. RCU really has no
6862 * choice here: we need to keep an RCU-free window in idle where
6863 * the CPU may possibly enter into low power mode. This way we can
6864 * notice an extended quiescent state to other CPUs that started a grace
6865 * period. Otherwise we would delay any grace period as long as we run
6866 * in the idle task.
6867 *
6868 * So complain bitterly if someone does call rcu_read_lock(),
6869 * rcu_read_lock_bh() and so on from extended quiescent states.
6870 */
6871 if (!rcu_is_watching())
6872 pr_warn("RCU used illegally from extended quiescent state!\n");
6873
6874 lockdep_print_held_locks(curr);
6875 pr_warn("\nstack backtrace:\n");
6876 dump_stack();
6877 nbcon_cpu_emergency_exit();
6878 warn_rcu_exit(rcu);
6879}
6880EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);