1 // SPDX-License-Identifier: GPL-2.0-only
5 * Runtime locking correctness validator
7 * Started by Ingo Molnar:
9 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
10 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
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:
15 * - lock inversion scenarios
16 * - circular lock dependencies
17 * - hardirq/softirq safe/unsafe locking bugs
19 * Bugs are reported even if the current locking scenario does not cause
20 * any deadlock at this point.
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.
26 * Thanks to Arjan van de Ven for coming up with the initial idea of
27 * mapping lock dependencies runtime.
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>
58 #include <asm/sections.h>
60 #include "lockdep_internals.h"
62 #define CREATE_TRACE_POINTS
63 #include <trace/events/lock.h>
65 #ifdef CONFIG_PROVE_LOCKING
66 int prove_locking = 1;
67 module_param(prove_locking, int, 0644);
69 #define prove_locking 0
72 #ifdef CONFIG_LOCK_STAT
74 module_param(lock_stat, int, 0644);
80 * lockdep_lock: protects the lockdep graph, the hashes and the
81 * class/list/hash allocators.
83 * This is one of the rare exceptions where it's justified
84 * to use a raw spinlock - we really dont want the spinlock
85 * code to recurse back into the lockdep code...
87 static arch_spinlock_t __lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
88 static struct task_struct *__owner;
90 static inline void lockdep_lock(void)
92 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
94 arch_spin_lock(&__lock);
96 current->lockdep_recursion++;
99 static inline void lockdep_unlock(void)
101 if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current))
104 current->lockdep_recursion--;
106 arch_spin_unlock(&__lock);
109 static inline bool lockdep_assert_locked(void)
111 return DEBUG_LOCKS_WARN_ON(__owner != current);
114 static struct task_struct *lockdep_selftest_task_struct;
117 static int graph_lock(void)
121 * Make sure that if another CPU detected a bug while
122 * walking the graph we dont change it (while the other
123 * CPU is busy printing out stuff with the graph lock
133 static inline void graph_unlock(void)
139 * Turn lock debugging off and return with 0 if it was off already,
140 * and also release the graph lock:
142 static inline int debug_locks_off_graph_unlock(void)
144 int ret = debug_locks_off();
151 unsigned long nr_list_entries;
152 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
153 static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES);
156 * All data structures here are protected by the global debug_lock.
158 * nr_lock_classes is the number of elements of lock_classes[] that is
161 #define KEYHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
162 #define KEYHASH_SIZE (1UL << KEYHASH_BITS)
163 static struct hlist_head lock_keys_hash[KEYHASH_SIZE];
164 unsigned long nr_lock_classes;
165 unsigned long nr_zapped_classes;
166 #ifndef CONFIG_DEBUG_LOCKDEP
169 struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
170 static DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS);
172 static inline struct lock_class *hlock_class(struct held_lock *hlock)
174 unsigned int class_idx = hlock->class_idx;
176 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfield */
179 if (!test_bit(class_idx, lock_classes_in_use)) {
181 * Someone passed in garbage, we give up.
183 DEBUG_LOCKS_WARN_ON(1);
188 * At this point, if the passed hlock->class_idx is still garbage,
189 * we just have to live with it
191 return lock_classes + class_idx;
194 #ifdef CONFIG_LOCK_STAT
195 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
197 static inline u64 lockstat_clock(void)
199 return local_clock();
202 static int lock_point(unsigned long points[], unsigned long ip)
206 for (i = 0; i < LOCKSTAT_POINTS; i++) {
207 if (points[i] == 0) {
218 static void lock_time_inc(struct lock_time *lt, u64 time)
223 if (time < lt->min || !lt->nr)
230 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
235 if (src->max > dst->max)
238 if (src->min < dst->min || !dst->nr)
241 dst->total += src->total;
245 struct lock_class_stats lock_stats(struct lock_class *class)
247 struct lock_class_stats stats;
250 memset(&stats, 0, sizeof(struct lock_class_stats));
251 for_each_possible_cpu(cpu) {
252 struct lock_class_stats *pcs =
253 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
255 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
256 stats.contention_point[i] += pcs->contention_point[i];
258 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
259 stats.contending_point[i] += pcs->contending_point[i];
261 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
262 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
264 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
265 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
267 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
268 stats.bounces[i] += pcs->bounces[i];
274 void clear_lock_stats(struct lock_class *class)
278 for_each_possible_cpu(cpu) {
279 struct lock_class_stats *cpu_stats =
280 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
282 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
284 memset(class->contention_point, 0, sizeof(class->contention_point));
285 memset(class->contending_point, 0, sizeof(class->contending_point));
288 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
290 return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes];
293 static void lock_release_holdtime(struct held_lock *hlock)
295 struct lock_class_stats *stats;
301 holdtime = lockstat_clock() - hlock->holdtime_stamp;
303 stats = get_lock_stats(hlock_class(hlock));
305 lock_time_inc(&stats->read_holdtime, holdtime);
307 lock_time_inc(&stats->write_holdtime, holdtime);
310 static inline void lock_release_holdtime(struct held_lock *hlock)
316 * We keep a global list of all lock classes. The list is only accessed with
317 * the lockdep spinlock lock held. free_lock_classes is a list with free
318 * elements. These elements are linked together by the lock_entry member in
321 LIST_HEAD(all_lock_classes);
322 static LIST_HEAD(free_lock_classes);
325 * struct pending_free - information about data structures about to be freed
326 * @zapped: Head of a list with struct lock_class elements.
327 * @lock_chains_being_freed: Bitmap that indicates which lock_chains[] elements
328 * are about to be freed.
330 struct pending_free {
331 struct list_head zapped;
332 DECLARE_BITMAP(lock_chains_being_freed, MAX_LOCKDEP_CHAINS);
336 * struct delayed_free - data structures used for delayed freeing
338 * A data structure for delayed freeing of data structures that may be
339 * accessed by RCU readers at the time these were freed.
341 * @rcu_head: Used to schedule an RCU callback for freeing data structures.
342 * @index: Index of @pf to which freed data structures are added.
343 * @scheduled: Whether or not an RCU callback has been scheduled.
344 * @pf: Array with information about data structures about to be freed.
346 static struct delayed_free {
347 struct rcu_head rcu_head;
350 struct pending_free pf[2];
354 * The lockdep classes are in a hash-table as well, for fast lookup:
356 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
357 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
358 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
359 #define classhashentry(key) (classhash_table + __classhashfn((key)))
361 static struct hlist_head classhash_table[CLASSHASH_SIZE];
364 * We put the lock dependency chains into a hash-table as well, to cache
367 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
368 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
369 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
370 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
372 static struct hlist_head chainhash_table[CHAINHASH_SIZE];
375 * The hash key of the lock dependency chains is a hash itself too:
376 * it's a hash of all locks taken up to that lock, including that lock.
377 * It's a 64-bit hash, because it's important for the keys to be
380 static inline u64 iterate_chain_key(u64 key, u32 idx)
382 u32 k0 = key, k1 = key >> 32;
384 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
386 return k0 | (u64)k1 << 32;
389 void lockdep_init_task(struct task_struct *task)
391 task->lockdep_depth = 0; /* no locks held yet */
392 task->curr_chain_key = INITIAL_CHAIN_KEY;
393 task->lockdep_recursion = 0;
396 static __always_inline void lockdep_recursion_finish(void)
398 if (WARN_ON_ONCE((--current->lockdep_recursion) & LOCKDEP_RECURSION_MASK))
399 current->lockdep_recursion = 0;
402 void lockdep_set_selftest_task(struct task_struct *task)
404 lockdep_selftest_task_struct = task;
408 * Debugging switches:
412 #define VERY_VERBOSE 0
415 # define HARDIRQ_VERBOSE 1
416 # define SOFTIRQ_VERBOSE 1
418 # define HARDIRQ_VERBOSE 0
419 # define SOFTIRQ_VERBOSE 0
422 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
424 * Quick filtering for interesting events:
426 static int class_filter(struct lock_class *class)
430 if (class->name_version == 1 &&
431 !strcmp(class->name, "lockname"))
433 if (class->name_version == 1 &&
434 !strcmp(class->name, "&struct->lockfield"))
437 /* Filter everything else. 1 would be to allow everything else */
442 static int verbose(struct lock_class *class)
445 return class_filter(class);
450 static void print_lockdep_off(const char *bug_msg)
452 printk(KERN_DEBUG "%s\n", bug_msg);
453 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
454 #ifdef CONFIG_LOCK_STAT
455 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
459 unsigned long nr_stack_trace_entries;
461 #ifdef CONFIG_PROVE_LOCKING
463 * struct lock_trace - single stack backtrace
464 * @hash_entry: Entry in a stack_trace_hash[] list.
465 * @hash: jhash() of @entries.
466 * @nr_entries: Number of entries in @entries.
467 * @entries: Actual stack backtrace.
470 struct hlist_node hash_entry;
473 unsigned long entries[] __aligned(sizeof(unsigned long));
475 #define LOCK_TRACE_SIZE_IN_LONGS \
476 (sizeof(struct lock_trace) / sizeof(unsigned long))
478 * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock.
480 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
481 static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE];
483 static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2)
485 return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries &&
486 memcmp(t1->entries, t2->entries,
487 t1->nr_entries * sizeof(t1->entries[0])) == 0;
490 static struct lock_trace *save_trace(void)
492 struct lock_trace *trace, *t2;
493 struct hlist_head *hash_head;
497 BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE);
498 BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES);
500 trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries);
501 max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries -
502 LOCK_TRACE_SIZE_IN_LONGS;
504 if (max_entries <= 0) {
505 if (!debug_locks_off_graph_unlock())
508 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
513 trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
515 hash = jhash(trace->entries, trace->nr_entries *
516 sizeof(trace->entries[0]), 0);
518 hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1));
519 hlist_for_each_entry(t2, hash_head, hash_entry) {
520 if (traces_identical(trace, t2))
523 nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries;
524 hlist_add_head(&trace->hash_entry, hash_head);
529 /* Return the number of stack traces in the stack_trace[] array. */
530 u64 lockdep_stack_trace_count(void)
532 struct lock_trace *trace;
536 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) {
537 hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) {
545 /* Return the number of stack hash chains that have at least one stack trace. */
546 u64 lockdep_stack_hash_count(void)
551 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++)
552 if (!hlist_empty(&stack_trace_hash[i]))
559 unsigned int nr_hardirq_chains;
560 unsigned int nr_softirq_chains;
561 unsigned int nr_process_chains;
562 unsigned int max_lockdep_depth;
564 #ifdef CONFIG_DEBUG_LOCKDEP
566 * Various lockdep statistics:
568 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
571 #ifdef CONFIG_PROVE_LOCKING
576 #define __USAGE(__STATE) \
577 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
578 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
579 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
580 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
582 static const char *usage_str[] =
584 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
585 #include "lockdep_states.h"
587 [LOCK_USED] = "INITIAL USE",
588 [LOCK_USAGE_STATES] = "IN-NMI",
592 const char *__get_key_name(const struct lockdep_subclass_key *key, char *str)
594 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
597 static inline unsigned long lock_flag(enum lock_usage_bit bit)
602 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
605 * The usage character defaults to '.' (i.e., irqs disabled and not in
606 * irq context), which is the safest usage category.
611 * The order of the following usage checks matters, which will
612 * result in the outcome character as follows:
614 * - '+': irq is enabled and not in irq context
615 * - '-': in irq context and irq is disabled
616 * - '?': in irq context and irq is enabled
618 if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) {
620 if (class->usage_mask & lock_flag(bit))
622 } else if (class->usage_mask & lock_flag(bit))
628 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
632 #define LOCKDEP_STATE(__STATE) \
633 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
634 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
635 #include "lockdep_states.h"
641 static void __print_lock_name(struct lock_class *class)
643 char str[KSYM_NAME_LEN];
648 name = __get_key_name(class->key, str);
649 printk(KERN_CONT "%s", name);
651 printk(KERN_CONT "%s", name);
652 if (class->name_version > 1)
653 printk(KERN_CONT "#%d", class->name_version);
655 printk(KERN_CONT "/%d", class->subclass);
659 static void print_lock_name(struct lock_class *class)
661 char usage[LOCK_USAGE_CHARS];
663 get_usage_chars(class, usage);
665 printk(KERN_CONT " (");
666 __print_lock_name(class);
667 printk(KERN_CONT "){%s}-{%hd:%hd}", usage,
668 class->wait_type_outer ?: class->wait_type_inner,
669 class->wait_type_inner);
672 static void print_lockdep_cache(struct lockdep_map *lock)
675 char str[KSYM_NAME_LEN];
679 name = __get_key_name(lock->key->subkeys, str);
681 printk(KERN_CONT "%s", name);
684 static void print_lock(struct held_lock *hlock)
687 * We can be called locklessly through debug_show_all_locks() so be
688 * extra careful, the hlock might have been released and cleared.
690 * If this indeed happens, lets pretend it does not hurt to continue
691 * to print the lock unless the hlock class_idx does not point to a
692 * registered class. The rationale here is: since we don't attempt
693 * to distinguish whether we are in this situation, if it just
694 * happened we can't count on class_idx to tell either.
696 struct lock_class *lock = hlock_class(hlock);
699 printk(KERN_CONT "<RELEASED>\n");
703 printk(KERN_CONT "%px", hlock->instance);
704 print_lock_name(lock);
705 printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
708 static void lockdep_print_held_locks(struct task_struct *p)
710 int i, depth = READ_ONCE(p->lockdep_depth);
713 printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p));
715 printk("%d lock%s held by %s/%d:\n", depth,
716 depth > 1 ? "s" : "", p->comm, task_pid_nr(p));
718 * It's not reliable to print a task's held locks if it's not sleeping
719 * and it's not the current task.
721 if (p->state == TASK_RUNNING && p != current)
723 for (i = 0; i < depth; i++) {
725 print_lock(p->held_locks + i);
729 static void print_kernel_ident(void)
731 printk("%s %.*s %s\n", init_utsname()->release,
732 (int)strcspn(init_utsname()->version, " "),
733 init_utsname()->version,
737 static int very_verbose(struct lock_class *class)
740 return class_filter(class);
746 * Is this the address of a static object:
749 static int static_obj(const void *obj)
751 unsigned long start = (unsigned long) &_stext,
752 end = (unsigned long) &_end,
753 addr = (unsigned long) obj;
755 if (arch_is_kernel_initmem_freed(addr))
761 if ((addr >= start) && (addr < end))
764 if (arch_is_kernel_data(addr))
768 * in-kernel percpu var?
770 if (is_kernel_percpu_address(addr))
774 * module static or percpu var?
776 return is_module_address(addr) || is_module_percpu_address(addr);
781 * To make lock name printouts unique, we calculate a unique
782 * class->name_version generation counter. The caller must hold the graph
785 static int count_matching_names(struct lock_class *new_class)
787 struct lock_class *class;
790 if (!new_class->name)
793 list_for_each_entry(class, &all_lock_classes, lock_entry) {
794 if (new_class->key - new_class->subclass == class->key)
795 return class->name_version;
796 if (class->name && !strcmp(class->name, new_class->name))
797 count = max(count, class->name_version);
803 /* used from NMI context -- must be lockless */
804 static __always_inline struct lock_class *
805 look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
807 struct lockdep_subclass_key *key;
808 struct hlist_head *hash_head;
809 struct lock_class *class;
811 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
814 "BUG: looking up invalid subclass: %u\n", subclass);
816 "turning off the locking correctness validator.\n");
822 * If it is not initialised then it has never been locked,
823 * so it won't be present in the hash table.
825 if (unlikely(!lock->key))
829 * NOTE: the class-key must be unique. For dynamic locks, a static
830 * lock_class_key variable is passed in through the mutex_init()
831 * (or spin_lock_init()) call - which acts as the key. For static
832 * locks we use the lock object itself as the key.
834 BUILD_BUG_ON(sizeof(struct lock_class_key) >
835 sizeof(struct lockdep_map));
837 key = lock->key->subkeys + subclass;
839 hash_head = classhashentry(key);
842 * We do an RCU walk of the hash, see lockdep_free_key_range().
844 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
847 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
848 if (class->key == key) {
850 * Huh! same key, different name? Did someone trample
851 * on some memory? We're most confused.
853 WARN_ON_ONCE(class->name != lock->name &&
854 lock->key != &__lockdep_no_validate__);
863 * Static locks do not have their class-keys yet - for them the key is
864 * the lock object itself. If the lock is in the per cpu area, the
865 * canonical address of the lock (per cpu offset removed) is used.
867 static bool assign_lock_key(struct lockdep_map *lock)
869 unsigned long can_addr, addr = (unsigned long)lock;
873 * lockdep_free_key_range() assumes that struct lock_class_key
874 * objects do not overlap. Since we use the address of lock
875 * objects as class key for static objects, check whether the
876 * size of lock_class_key objects does not exceed the size of
877 * the smallest lock object.
879 BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
882 if (__is_kernel_percpu_address(addr, &can_addr))
883 lock->key = (void *)can_addr;
884 else if (__is_module_percpu_address(addr, &can_addr))
885 lock->key = (void *)can_addr;
886 else if (static_obj(lock))
887 lock->key = (void *)lock;
889 /* Debug-check: all keys must be persistent! */
891 pr_err("INFO: trying to register non-static key.\n");
892 pr_err("the code is fine but needs lockdep annotation.\n");
893 pr_err("turning off the locking correctness validator.\n");
901 #ifdef CONFIG_DEBUG_LOCKDEP
903 /* Check whether element @e occurs in list @h */
904 static bool in_list(struct list_head *e, struct list_head *h)
908 list_for_each(f, h) {
917 * Check whether entry @e occurs in any of the locks_after or locks_before
920 static bool in_any_class_list(struct list_head *e)
922 struct lock_class *class;
925 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
926 class = &lock_classes[i];
927 if (in_list(e, &class->locks_after) ||
928 in_list(e, &class->locks_before))
934 static bool class_lock_list_valid(struct lock_class *c, struct list_head *h)
938 list_for_each_entry(e, h, entry) {
939 if (e->links_to != c) {
940 printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s",
942 (unsigned long)(e - list_entries),
943 e->links_to && e->links_to->name ?
944 e->links_to->name : "(?)",
945 e->class && e->class->name ? e->class->name :
953 #ifdef CONFIG_PROVE_LOCKING
954 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
957 static bool check_lock_chain_key(struct lock_chain *chain)
959 #ifdef CONFIG_PROVE_LOCKING
960 u64 chain_key = INITIAL_CHAIN_KEY;
963 for (i = chain->base; i < chain->base + chain->depth; i++)
964 chain_key = iterate_chain_key(chain_key, chain_hlocks[i]);
966 * The 'unsigned long long' casts avoid that a compiler warning
967 * is reported when building tools/lib/lockdep.
969 if (chain->chain_key != chain_key) {
970 printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n",
971 (unsigned long long)(chain - lock_chains),
972 (unsigned long long)chain->chain_key,
973 (unsigned long long)chain_key);
980 static bool in_any_zapped_class_list(struct lock_class *class)
982 struct pending_free *pf;
985 for (i = 0, pf = delayed_free.pf; i < ARRAY_SIZE(delayed_free.pf); i++, pf++) {
986 if (in_list(&class->lock_entry, &pf->zapped))
993 static bool __check_data_structures(void)
995 struct lock_class *class;
996 struct lock_chain *chain;
997 struct hlist_head *head;
1001 /* Check whether all classes occur in a lock list. */
1002 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1003 class = &lock_classes[i];
1004 if (!in_list(&class->lock_entry, &all_lock_classes) &&
1005 !in_list(&class->lock_entry, &free_lock_classes) &&
1006 !in_any_zapped_class_list(class)) {
1007 printk(KERN_INFO "class %px/%s is not in any class list\n",
1008 class, class->name ? : "(?)");
1013 /* Check whether all classes have valid lock lists. */
1014 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1015 class = &lock_classes[i];
1016 if (!class_lock_list_valid(class, &class->locks_before))
1018 if (!class_lock_list_valid(class, &class->locks_after))
1022 /* Check the chain_key of all lock chains. */
1023 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
1024 head = chainhash_table + i;
1025 hlist_for_each_entry_rcu(chain, head, entry) {
1026 if (!check_lock_chain_key(chain))
1032 * Check whether all list entries that are in use occur in a class
1035 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1036 e = list_entries + i;
1037 if (!in_any_class_list(&e->entry)) {
1038 printk(KERN_INFO "list entry %d is not in any class list; class %s <> %s\n",
1039 (unsigned int)(e - list_entries),
1040 e->class->name ? : "(?)",
1041 e->links_to->name ? : "(?)");
1047 * Check whether all list entries that are not in use do not occur in
1048 * a class lock list.
1050 for_each_clear_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1051 e = list_entries + i;
1052 if (in_any_class_list(&e->entry)) {
1053 printk(KERN_INFO "list entry %d occurs in a class list; class %s <> %s\n",
1054 (unsigned int)(e - list_entries),
1055 e->class && e->class->name ? e->class->name :
1057 e->links_to && e->links_to->name ?
1058 e->links_to->name : "(?)");
1066 int check_consistency = 0;
1067 module_param(check_consistency, int, 0644);
1069 static void check_data_structures(void)
1071 static bool once = false;
1073 if (check_consistency && !once) {
1074 if (!__check_data_structures()) {
1081 #else /* CONFIG_DEBUG_LOCKDEP */
1083 static inline void check_data_structures(void) { }
1085 #endif /* CONFIG_DEBUG_LOCKDEP */
1087 static void init_chain_block_buckets(void);
1090 * Initialize the lock_classes[] array elements, the free_lock_classes list
1091 * and also the delayed_free structure.
1093 static void init_data_structures_once(void)
1095 static bool __read_mostly ds_initialized, rcu_head_initialized;
1098 if (likely(rcu_head_initialized))
1101 if (system_state >= SYSTEM_SCHEDULING) {
1102 init_rcu_head(&delayed_free.rcu_head);
1103 rcu_head_initialized = true;
1109 ds_initialized = true;
1111 INIT_LIST_HEAD(&delayed_free.pf[0].zapped);
1112 INIT_LIST_HEAD(&delayed_free.pf[1].zapped);
1114 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1115 list_add_tail(&lock_classes[i].lock_entry, &free_lock_classes);
1116 INIT_LIST_HEAD(&lock_classes[i].locks_after);
1117 INIT_LIST_HEAD(&lock_classes[i].locks_before);
1119 init_chain_block_buckets();
1122 static inline struct hlist_head *keyhashentry(const struct lock_class_key *key)
1124 unsigned long hash = hash_long((uintptr_t)key, KEYHASH_BITS);
1126 return lock_keys_hash + hash;
1129 /* Register a dynamically allocated key. */
1130 void lockdep_register_key(struct lock_class_key *key)
1132 struct hlist_head *hash_head;
1133 struct lock_class_key *k;
1134 unsigned long flags;
1136 if (WARN_ON_ONCE(static_obj(key)))
1138 hash_head = keyhashentry(key);
1140 raw_local_irq_save(flags);
1143 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1144 if (WARN_ON_ONCE(k == key))
1147 hlist_add_head_rcu(&key->hash_entry, hash_head);
1151 raw_local_irq_restore(flags);
1153 EXPORT_SYMBOL_GPL(lockdep_register_key);
1155 /* Check whether a key has been registered as a dynamic key. */
1156 static bool is_dynamic_key(const struct lock_class_key *key)
1158 struct hlist_head *hash_head;
1159 struct lock_class_key *k;
1162 if (WARN_ON_ONCE(static_obj(key)))
1166 * If lock debugging is disabled lock_keys_hash[] may contain
1167 * pointers to memory that has already been freed. Avoid triggering
1168 * a use-after-free in that case by returning early.
1173 hash_head = keyhashentry(key);
1176 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1188 * Register a lock's class in the hash-table, if the class is not present
1189 * yet. Otherwise we look it up. We cache the result in the lock object
1190 * itself, so actual lookup of the hash should be once per lock object.
1192 static struct lock_class *
1193 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
1195 struct lockdep_subclass_key *key;
1196 struct hlist_head *hash_head;
1197 struct lock_class *class;
1199 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1201 class = look_up_lock_class(lock, subclass);
1203 goto out_set_class_cache;
1206 if (!assign_lock_key(lock))
1208 } else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) {
1212 key = lock->key->subkeys + subclass;
1213 hash_head = classhashentry(key);
1215 if (!graph_lock()) {
1219 * We have to do the hash-walk again, to avoid races
1222 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
1223 if (class->key == key)
1224 goto out_unlock_set;
1227 init_data_structures_once();
1229 /* Allocate a new lock class and add it to the hash. */
1230 class = list_first_entry_or_null(&free_lock_classes, typeof(*class),
1233 if (!debug_locks_off_graph_unlock()) {
1237 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
1242 __set_bit(class - lock_classes, lock_classes_in_use);
1243 debug_atomic_inc(nr_unused_locks);
1245 class->name = lock->name;
1246 class->subclass = subclass;
1247 WARN_ON_ONCE(!list_empty(&class->locks_before));
1248 WARN_ON_ONCE(!list_empty(&class->locks_after));
1249 class->name_version = count_matching_names(class);
1250 class->wait_type_inner = lock->wait_type_inner;
1251 class->wait_type_outer = lock->wait_type_outer;
1253 * We use RCU's safe list-add method to make
1254 * parallel walking of the hash-list safe:
1256 hlist_add_head_rcu(&class->hash_entry, hash_head);
1258 * Remove the class from the free list and add it to the global list
1261 list_move_tail(&class->lock_entry, &all_lock_classes);
1263 if (verbose(class)) {
1266 printk("\nnew class %px: %s", class->key, class->name);
1267 if (class->name_version > 1)
1268 printk(KERN_CONT "#%d", class->name_version);
1269 printk(KERN_CONT "\n");
1272 if (!graph_lock()) {
1279 out_set_class_cache:
1280 if (!subclass || force)
1281 lock->class_cache[0] = class;
1282 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
1283 lock->class_cache[subclass] = class;
1286 * Hash collision, did we smoke some? We found a class with a matching
1287 * hash but the subclass -- which is hashed in -- didn't match.
1289 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
1295 #ifdef CONFIG_PROVE_LOCKING
1297 * Allocate a lockdep entry. (assumes the graph_lock held, returns
1298 * with NULL on failure)
1300 static struct lock_list *alloc_list_entry(void)
1302 int idx = find_first_zero_bit(list_entries_in_use,
1303 ARRAY_SIZE(list_entries));
1305 if (idx >= ARRAY_SIZE(list_entries)) {
1306 if (!debug_locks_off_graph_unlock())
1309 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
1314 __set_bit(idx, list_entries_in_use);
1315 return list_entries + idx;
1319 * Add a new dependency to the head of the list:
1321 static int add_lock_to_list(struct lock_class *this,
1322 struct lock_class *links_to, struct list_head *head,
1323 unsigned long ip, int distance,
1324 const struct lock_trace *trace)
1326 struct lock_list *entry;
1328 * Lock not present yet - get a new dependency struct and
1329 * add it to the list:
1331 entry = alloc_list_entry();
1335 entry->class = this;
1336 entry->links_to = links_to;
1337 entry->distance = distance;
1338 entry->trace = trace;
1340 * Both allocation and removal are done under the graph lock; but
1341 * iteration is under RCU-sched; see look_up_lock_class() and
1342 * lockdep_free_key_range().
1344 list_add_tail_rcu(&entry->entry, head);
1350 * For good efficiency of modular, we use power of 2
1352 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
1353 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
1356 * The circular_queue and helpers are used to implement graph
1357 * breadth-first search (BFS) algorithm, by which we can determine
1358 * whether there is a path from a lock to another. In deadlock checks,
1359 * a path from the next lock to be acquired to a previous held lock
1360 * indicates that adding the <prev> -> <next> lock dependency will
1361 * produce a circle in the graph. Breadth-first search instead of
1362 * depth-first search is used in order to find the shortest (circular)
1365 struct circular_queue {
1366 struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE];
1367 unsigned int front, rear;
1370 static struct circular_queue lock_cq;
1372 unsigned int max_bfs_queue_depth;
1374 static unsigned int lockdep_dependency_gen_id;
1376 static inline void __cq_init(struct circular_queue *cq)
1378 cq->front = cq->rear = 0;
1379 lockdep_dependency_gen_id++;
1382 static inline int __cq_empty(struct circular_queue *cq)
1384 return (cq->front == cq->rear);
1387 static inline int __cq_full(struct circular_queue *cq)
1389 return ((cq->rear + 1) & CQ_MASK) == cq->front;
1392 static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem)
1397 cq->element[cq->rear] = elem;
1398 cq->rear = (cq->rear + 1) & CQ_MASK;
1403 * Dequeue an element from the circular_queue, return a lock_list if
1404 * the queue is not empty, or NULL if otherwise.
1406 static inline struct lock_list * __cq_dequeue(struct circular_queue *cq)
1408 struct lock_list * lock;
1413 lock = cq->element[cq->front];
1414 cq->front = (cq->front + 1) & CQ_MASK;
1419 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
1421 return (cq->rear - cq->front) & CQ_MASK;
1424 static inline void mark_lock_accessed(struct lock_list *lock,
1425 struct lock_list *parent)
1429 nr = lock - list_entries;
1430 WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */
1431 lock->parent = parent;
1432 lock->class->dep_gen_id = lockdep_dependency_gen_id;
1435 static inline unsigned long lock_accessed(struct lock_list *lock)
1439 nr = lock - list_entries;
1440 WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */
1441 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
1444 static inline struct lock_list *get_lock_parent(struct lock_list *child)
1446 return child->parent;
1449 static inline int get_lock_depth(struct lock_list *child)
1452 struct lock_list *parent;
1454 while ((parent = get_lock_parent(child))) {
1462 * Return the forward or backward dependency list.
1464 * @lock: the lock_list to get its class's dependency list
1465 * @offset: the offset to struct lock_class to determine whether it is
1466 * locks_after or locks_before
1468 static inline struct list_head *get_dep_list(struct lock_list *lock, int offset)
1470 void *lock_class = lock->class;
1472 return lock_class + offset;
1476 * Forward- or backward-dependency search, used for both circular dependency
1477 * checking and hardirq-unsafe/softirq-unsafe checking.
1479 static int __bfs(struct lock_list *source_entry,
1481 int (*match)(struct lock_list *entry, void *data),
1482 struct lock_list **target_entry,
1485 struct lock_list *entry;
1486 struct lock_list *lock;
1487 struct list_head *head;
1488 struct circular_queue *cq = &lock_cq;
1491 lockdep_assert_locked();
1493 if (match(source_entry, data)) {
1494 *target_entry = source_entry;
1499 head = get_dep_list(source_entry, offset);
1500 if (list_empty(head))
1504 __cq_enqueue(cq, source_entry);
1506 while ((lock = __cq_dequeue(cq))) {
1513 head = get_dep_list(lock, offset);
1515 list_for_each_entry_rcu(entry, head, entry) {
1516 if (!lock_accessed(entry)) {
1517 unsigned int cq_depth;
1518 mark_lock_accessed(entry, lock);
1519 if (match(entry, data)) {
1520 *target_entry = entry;
1525 if (__cq_enqueue(cq, entry)) {
1529 cq_depth = __cq_get_elem_count(cq);
1530 if (max_bfs_queue_depth < cq_depth)
1531 max_bfs_queue_depth = cq_depth;
1539 static inline int __bfs_forwards(struct lock_list *src_entry,
1541 int (*match)(struct lock_list *entry, void *data),
1542 struct lock_list **target_entry)
1544 return __bfs(src_entry, data, match, target_entry,
1545 offsetof(struct lock_class, locks_after));
1549 static inline int __bfs_backwards(struct lock_list *src_entry,
1551 int (*match)(struct lock_list *entry, void *data),
1552 struct lock_list **target_entry)
1554 return __bfs(src_entry, data, match, target_entry,
1555 offsetof(struct lock_class, locks_before));
1559 static void print_lock_trace(const struct lock_trace *trace,
1560 unsigned int spaces)
1562 stack_trace_print(trace->entries, trace->nr_entries, spaces);
1566 * Print a dependency chain entry (this is only done when a deadlock
1567 * has been detected):
1569 static noinline void
1570 print_circular_bug_entry(struct lock_list *target, int depth)
1572 if (debug_locks_silent)
1574 printk("\n-> #%u", depth);
1575 print_lock_name(target->class);
1576 printk(KERN_CONT ":\n");
1577 print_lock_trace(target->trace, 6);
1581 print_circular_lock_scenario(struct held_lock *src,
1582 struct held_lock *tgt,
1583 struct lock_list *prt)
1585 struct lock_class *source = hlock_class(src);
1586 struct lock_class *target = hlock_class(tgt);
1587 struct lock_class *parent = prt->class;
1590 * A direct locking problem where unsafe_class lock is taken
1591 * directly by safe_class lock, then all we need to show
1592 * is the deadlock scenario, as it is obvious that the
1593 * unsafe lock is taken under the safe lock.
1595 * But if there is a chain instead, where the safe lock takes
1596 * an intermediate lock (middle_class) where this lock is
1597 * not the same as the safe lock, then the lock chain is
1598 * used to describe the problem. Otherwise we would need
1599 * to show a different CPU case for each link in the chain
1600 * from the safe_class lock to the unsafe_class lock.
1602 if (parent != source) {
1603 printk("Chain exists of:\n ");
1604 __print_lock_name(source);
1605 printk(KERN_CONT " --> ");
1606 __print_lock_name(parent);
1607 printk(KERN_CONT " --> ");
1608 __print_lock_name(target);
1609 printk(KERN_CONT "\n\n");
1612 printk(" Possible unsafe locking scenario:\n\n");
1613 printk(" CPU0 CPU1\n");
1614 printk(" ---- ----\n");
1616 __print_lock_name(target);
1617 printk(KERN_CONT ");\n");
1619 __print_lock_name(parent);
1620 printk(KERN_CONT ");\n");
1622 __print_lock_name(target);
1623 printk(KERN_CONT ");\n");
1625 __print_lock_name(source);
1626 printk(KERN_CONT ");\n");
1627 printk("\n *** DEADLOCK ***\n\n");
1631 * When a circular dependency is detected, print the
1634 static noinline void
1635 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1636 struct held_lock *check_src,
1637 struct held_lock *check_tgt)
1639 struct task_struct *curr = current;
1641 if (debug_locks_silent)
1645 pr_warn("======================================================\n");
1646 pr_warn("WARNING: possible circular locking dependency detected\n");
1647 print_kernel_ident();
1648 pr_warn("------------------------------------------------------\n");
1649 pr_warn("%s/%d is trying to acquire lock:\n",
1650 curr->comm, task_pid_nr(curr));
1651 print_lock(check_src);
1653 pr_warn("\nbut task is already holding lock:\n");
1655 print_lock(check_tgt);
1656 pr_warn("\nwhich lock already depends on the new lock.\n\n");
1657 pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1659 print_circular_bug_entry(entry, depth);
1662 static inline int class_equal(struct lock_list *entry, void *data)
1664 return entry->class == data;
1667 static noinline void print_circular_bug(struct lock_list *this,
1668 struct lock_list *target,
1669 struct held_lock *check_src,
1670 struct held_lock *check_tgt)
1672 struct task_struct *curr = current;
1673 struct lock_list *parent;
1674 struct lock_list *first_parent;
1677 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1680 this->trace = save_trace();
1684 depth = get_lock_depth(target);
1686 print_circular_bug_header(target, depth, check_src, check_tgt);
1688 parent = get_lock_parent(target);
1689 first_parent = parent;
1692 print_circular_bug_entry(parent, --depth);
1693 parent = get_lock_parent(parent);
1696 printk("\nother info that might help us debug this:\n\n");
1697 print_circular_lock_scenario(check_src, check_tgt,
1700 lockdep_print_held_locks(curr);
1702 printk("\nstack backtrace:\n");
1706 static noinline void print_bfs_bug(int ret)
1708 if (!debug_locks_off_graph_unlock())
1712 * Breadth-first-search failed, graph got corrupted?
1714 WARN(1, "lockdep bfs error:%d\n", ret);
1717 static int noop_count(struct lock_list *entry, void *data)
1719 (*(unsigned long *)data)++;
1723 static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1725 unsigned long count = 0;
1726 struct lock_list *target_entry;
1728 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1732 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1734 unsigned long ret, flags;
1735 struct lock_list this;
1740 raw_local_irq_save(flags);
1742 ret = __lockdep_count_forward_deps(&this);
1744 raw_local_irq_restore(flags);
1749 static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1751 unsigned long count = 0;
1752 struct lock_list *target_entry;
1754 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1759 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1761 unsigned long ret, flags;
1762 struct lock_list this;
1767 raw_local_irq_save(flags);
1769 ret = __lockdep_count_backward_deps(&this);
1771 raw_local_irq_restore(flags);
1777 * Check that the dependency graph starting at <src> can lead to
1778 * <target> or not. Print an error and return 0 if it does.
1781 check_path(struct lock_class *target, struct lock_list *src_entry,
1782 struct lock_list **target_entry)
1786 ret = __bfs_forwards(src_entry, (void *)target, class_equal,
1789 if (unlikely(ret < 0))
1796 * Prove that the dependency graph starting at <src> can not
1797 * lead to <target>. If it can, there is a circle when adding
1798 * <target> -> <src> dependency.
1800 * Print an error and return 0 if it does.
1803 check_noncircular(struct held_lock *src, struct held_lock *target,
1804 struct lock_trace **const trace)
1807 struct lock_list *target_entry;
1808 struct lock_list src_entry = {
1809 .class = hlock_class(src),
1813 debug_atomic_inc(nr_cyclic_checks);
1815 ret = check_path(hlock_class(target), &src_entry, &target_entry);
1817 if (unlikely(!ret)) {
1820 * If save_trace fails here, the printing might
1821 * trigger a WARN but because of the !nr_entries it
1822 * should not do bad things.
1824 *trace = save_trace();
1827 print_circular_bug(&src_entry, target_entry, src, target);
1833 #ifdef CONFIG_LOCKDEP_SMALL
1835 * Check that the dependency graph starting at <src> can lead to
1836 * <target> or not. If it can, <src> -> <target> dependency is already
1839 * Print an error and return 2 if it does or 1 if it does not.
1842 check_redundant(struct held_lock *src, struct held_lock *target)
1845 struct lock_list *target_entry;
1846 struct lock_list src_entry = {
1847 .class = hlock_class(src),
1851 debug_atomic_inc(nr_redundant_checks);
1853 ret = check_path(hlock_class(target), &src_entry, &target_entry);
1856 debug_atomic_inc(nr_redundant);
1865 #ifdef CONFIG_TRACE_IRQFLAGS
1867 static inline int usage_accumulate(struct lock_list *entry, void *mask)
1869 *(unsigned long *)mask |= entry->class->usage_mask;
1875 * Forwards and backwards subgraph searching, for the purposes of
1876 * proving that two subgraphs can be connected by a new dependency
1877 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1880 static inline int usage_match(struct lock_list *entry, void *mask)
1882 return entry->class->usage_mask & *(unsigned long *)mask;
1886 * Find a node in the forwards-direction dependency sub-graph starting
1887 * at @root->class that matches @bit.
1889 * Return 0 if such a node exists in the subgraph, and put that node
1890 * into *@target_entry.
1892 * Return 1 otherwise and keep *@target_entry unchanged.
1893 * Return <0 on error.
1896 find_usage_forwards(struct lock_list *root, unsigned long usage_mask,
1897 struct lock_list **target_entry)
1901 debug_atomic_inc(nr_find_usage_forwards_checks);
1903 result = __bfs_forwards(root, &usage_mask, usage_match, target_entry);
1909 * Find a node in the backwards-direction dependency sub-graph starting
1910 * at @root->class that matches @bit.
1912 * Return 0 if such a node exists in the subgraph, and put that node
1913 * into *@target_entry.
1915 * Return 1 otherwise and keep *@target_entry unchanged.
1916 * Return <0 on error.
1919 find_usage_backwards(struct lock_list *root, unsigned long usage_mask,
1920 struct lock_list **target_entry)
1924 debug_atomic_inc(nr_find_usage_backwards_checks);
1926 result = __bfs_backwards(root, &usage_mask, usage_match, target_entry);
1931 static void print_lock_class_header(struct lock_class *class, int depth)
1935 printk("%*s->", depth, "");
1936 print_lock_name(class);
1937 #ifdef CONFIG_DEBUG_LOCKDEP
1938 printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
1940 printk(KERN_CONT " {\n");
1942 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1943 if (class->usage_mask & (1 << bit)) {
1946 len += printk("%*s %s", depth, "", usage_str[bit]);
1947 len += printk(KERN_CONT " at:\n");
1948 print_lock_trace(class->usage_traces[bit], len);
1951 printk("%*s }\n", depth, "");
1953 printk("%*s ... key at: [<%px>] %pS\n",
1954 depth, "", class->key, class->key);
1958 * printk the shortest lock dependencies from @start to @end in reverse order:
1961 print_shortest_lock_dependencies(struct lock_list *leaf,
1962 struct lock_list *root)
1964 struct lock_list *entry = leaf;
1967 /*compute depth from generated tree by BFS*/
1968 depth = get_lock_depth(leaf);
1971 print_lock_class_header(entry->class, depth);
1972 printk("%*s ... acquired at:\n", depth, "");
1973 print_lock_trace(entry->trace, 2);
1976 if (depth == 0 && (entry != root)) {
1977 printk("lockdep:%s bad path found in chain graph\n", __func__);
1981 entry = get_lock_parent(entry);
1983 } while (entry && (depth >= 0));
1987 print_irq_lock_scenario(struct lock_list *safe_entry,
1988 struct lock_list *unsafe_entry,
1989 struct lock_class *prev_class,
1990 struct lock_class *next_class)
1992 struct lock_class *safe_class = safe_entry->class;
1993 struct lock_class *unsafe_class = unsafe_entry->class;
1994 struct lock_class *middle_class = prev_class;
1996 if (middle_class == safe_class)
1997 middle_class = next_class;
2000 * A direct locking problem where unsafe_class lock is taken
2001 * directly by safe_class lock, then all we need to show
2002 * is the deadlock scenario, as it is obvious that the
2003 * unsafe lock is taken under the safe lock.
2005 * But if there is a chain instead, where the safe lock takes
2006 * an intermediate lock (middle_class) where this lock is
2007 * not the same as the safe lock, then the lock chain is
2008 * used to describe the problem. Otherwise we would need
2009 * to show a different CPU case for each link in the chain
2010 * from the safe_class lock to the unsafe_class lock.
2012 if (middle_class != unsafe_class) {
2013 printk("Chain exists of:\n ");
2014 __print_lock_name(safe_class);
2015 printk(KERN_CONT " --> ");
2016 __print_lock_name(middle_class);
2017 printk(KERN_CONT " --> ");
2018 __print_lock_name(unsafe_class);
2019 printk(KERN_CONT "\n\n");
2022 printk(" Possible interrupt unsafe locking scenario:\n\n");
2023 printk(" CPU0 CPU1\n");
2024 printk(" ---- ----\n");
2026 __print_lock_name(unsafe_class);
2027 printk(KERN_CONT ");\n");
2028 printk(" local_irq_disable();\n");
2030 __print_lock_name(safe_class);
2031 printk(KERN_CONT ");\n");
2033 __print_lock_name(middle_class);
2034 printk(KERN_CONT ");\n");
2035 printk(" <Interrupt>\n");
2037 __print_lock_name(safe_class);
2038 printk(KERN_CONT ");\n");
2039 printk("\n *** DEADLOCK ***\n\n");
2043 print_bad_irq_dependency(struct task_struct *curr,
2044 struct lock_list *prev_root,
2045 struct lock_list *next_root,
2046 struct lock_list *backwards_entry,
2047 struct lock_list *forwards_entry,
2048 struct held_lock *prev,
2049 struct held_lock *next,
2050 enum lock_usage_bit bit1,
2051 enum lock_usage_bit bit2,
2052 const char *irqclass)
2054 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2058 pr_warn("=====================================================\n");
2059 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
2060 irqclass, irqclass);
2061 print_kernel_ident();
2062 pr_warn("-----------------------------------------------------\n");
2063 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
2064 curr->comm, task_pid_nr(curr),
2065 lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
2066 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
2067 lockdep_hardirqs_enabled(),
2068 curr->softirqs_enabled);
2071 pr_warn("\nand this task is already holding:\n");
2073 pr_warn("which would create a new lock dependency:\n");
2074 print_lock_name(hlock_class(prev));
2076 print_lock_name(hlock_class(next));
2079 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
2081 print_lock_name(backwards_entry->class);
2082 pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
2084 print_lock_trace(backwards_entry->class->usage_traces[bit1], 1);
2086 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
2087 print_lock_name(forwards_entry->class);
2088 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
2091 print_lock_trace(forwards_entry->class->usage_traces[bit2], 1);
2093 pr_warn("\nother info that might help us debug this:\n\n");
2094 print_irq_lock_scenario(backwards_entry, forwards_entry,
2095 hlock_class(prev), hlock_class(next));
2097 lockdep_print_held_locks(curr);
2099 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
2100 prev_root->trace = save_trace();
2101 if (!prev_root->trace)
2103 print_shortest_lock_dependencies(backwards_entry, prev_root);
2105 pr_warn("\nthe dependencies between the lock to be acquired");
2106 pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
2107 next_root->trace = save_trace();
2108 if (!next_root->trace)
2110 print_shortest_lock_dependencies(forwards_entry, next_root);
2112 pr_warn("\nstack backtrace:\n");
2116 static const char *state_names[] = {
2117 #define LOCKDEP_STATE(__STATE) \
2118 __stringify(__STATE),
2119 #include "lockdep_states.h"
2120 #undef LOCKDEP_STATE
2123 static const char *state_rnames[] = {
2124 #define LOCKDEP_STATE(__STATE) \
2125 __stringify(__STATE)"-READ",
2126 #include "lockdep_states.h"
2127 #undef LOCKDEP_STATE
2130 static inline const char *state_name(enum lock_usage_bit bit)
2132 if (bit & LOCK_USAGE_READ_MASK)
2133 return state_rnames[bit >> LOCK_USAGE_DIR_MASK];
2135 return state_names[bit >> LOCK_USAGE_DIR_MASK];
2139 * The bit number is encoded like:
2141 * bit0: 0 exclusive, 1 read lock
2142 * bit1: 0 used in irq, 1 irq enabled
2145 static int exclusive_bit(int new_bit)
2147 int state = new_bit & LOCK_USAGE_STATE_MASK;
2148 int dir = new_bit & LOCK_USAGE_DIR_MASK;
2151 * keep state, bit flip the direction and strip read.
2153 return state | (dir ^ LOCK_USAGE_DIR_MASK);
2157 * Observe that when given a bitmask where each bitnr is encoded as above, a
2158 * right shift of the mask transforms the individual bitnrs as -1 and
2159 * conversely, a left shift transforms into +1 for the individual bitnrs.
2161 * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can
2162 * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0)
2163 * instead by subtracting the bit number by 2, or shifting the mask right by 2.
2165 * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2.
2167 * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is
2168 * all bits set) and recompose with bitnr1 flipped.
2170 static unsigned long invert_dir_mask(unsigned long mask)
2172 unsigned long excl = 0;
2175 excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK;
2176 excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK;
2182 * As above, we clear bitnr0 (LOCK_*_READ off) with bitmask ops. First, for all
2183 * bits with bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*).
2184 * And then mask out all bitnr0.
2186 static unsigned long exclusive_mask(unsigned long mask)
2188 unsigned long excl = invert_dir_mask(mask);
2191 excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
2192 excl &= ~LOCKF_IRQ_READ;
2198 * Retrieve the _possible_ original mask to which @mask is
2199 * exclusive. Ie: this is the opposite of exclusive_mask().
2200 * Note that 2 possible original bits can match an exclusive
2201 * bit: one has LOCK_USAGE_READ_MASK set, the other has it
2202 * cleared. So both are returned for each exclusive bit.
2204 static unsigned long original_mask(unsigned long mask)
2206 unsigned long excl = invert_dir_mask(mask);
2208 /* Include read in existing usages */
2209 excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
2215 * Find the first pair of bit match between an original
2216 * usage mask and an exclusive usage mask.
2218 static int find_exclusive_match(unsigned long mask,
2219 unsigned long excl_mask,
2220 enum lock_usage_bit *bitp,
2221 enum lock_usage_bit *excl_bitp)
2225 for_each_set_bit(bit, &mask, LOCK_USED) {
2226 excl = exclusive_bit(bit);
2227 if (excl_mask & lock_flag(excl)) {
2237 * Prove that the new dependency does not connect a hardirq-safe(-read)
2238 * lock with a hardirq-unsafe lock - to achieve this we search
2239 * the backwards-subgraph starting at <prev>, and the
2240 * forwards-subgraph starting at <next>:
2242 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
2243 struct held_lock *next)
2245 unsigned long usage_mask = 0, forward_mask, backward_mask;
2246 enum lock_usage_bit forward_bit = 0, backward_bit = 0;
2247 struct lock_list *target_entry1;
2248 struct lock_list *target_entry;
2249 struct lock_list this, that;
2253 * Step 1: gather all hard/soft IRQs usages backward in an
2254 * accumulated usage mask.
2257 this.class = hlock_class(prev);
2259 ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL);
2265 usage_mask &= LOCKF_USED_IN_IRQ_ALL;
2270 * Step 2: find exclusive uses forward that match the previous
2271 * backward accumulated mask.
2273 forward_mask = exclusive_mask(usage_mask);
2276 that.class = hlock_class(next);
2278 ret = find_usage_forwards(&that, forward_mask, &target_entry1);
2287 * Step 3: we found a bad match! Now retrieve a lock from the backward
2288 * list whose usage mask matches the exclusive usage mask from the
2289 * lock found on the forward list.
2291 backward_mask = original_mask(target_entry1->class->usage_mask);
2293 ret = find_usage_backwards(&this, backward_mask, &target_entry);
2298 if (DEBUG_LOCKS_WARN_ON(ret == 1))
2302 * Step 4: narrow down to a pair of incompatible usage bits
2305 ret = find_exclusive_match(target_entry->class->usage_mask,
2306 target_entry1->class->usage_mask,
2307 &backward_bit, &forward_bit);
2308 if (DEBUG_LOCKS_WARN_ON(ret == -1))
2311 print_bad_irq_dependency(curr, &this, &that,
2312 target_entry, target_entry1,
2314 backward_bit, forward_bit,
2315 state_name(backward_bit));
2322 static inline int check_irq_usage(struct task_struct *curr,
2323 struct held_lock *prev, struct held_lock *next)
2327 #endif /* CONFIG_TRACE_IRQFLAGS */
2329 static void inc_chains(int irq_context)
2331 if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
2332 nr_hardirq_chains++;
2333 else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
2334 nr_softirq_chains++;
2336 nr_process_chains++;
2339 static void dec_chains(int irq_context)
2341 if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
2342 nr_hardirq_chains--;
2343 else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
2344 nr_softirq_chains--;
2346 nr_process_chains--;
2350 print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
2352 struct lock_class *next = hlock_class(nxt);
2353 struct lock_class *prev = hlock_class(prv);
2355 printk(" Possible unsafe locking scenario:\n\n");
2359 __print_lock_name(prev);
2360 printk(KERN_CONT ");\n");
2362 __print_lock_name(next);
2363 printk(KERN_CONT ");\n");
2364 printk("\n *** DEADLOCK ***\n\n");
2365 printk(" May be due to missing lock nesting notation\n\n");
2369 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
2370 struct held_lock *next)
2372 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2376 pr_warn("============================================\n");
2377 pr_warn("WARNING: possible recursive locking detected\n");
2378 print_kernel_ident();
2379 pr_warn("--------------------------------------------\n");
2380 pr_warn("%s/%d is trying to acquire lock:\n",
2381 curr->comm, task_pid_nr(curr));
2383 pr_warn("\nbut task is already holding lock:\n");
2386 pr_warn("\nother info that might help us debug this:\n");
2387 print_deadlock_scenario(next, prev);
2388 lockdep_print_held_locks(curr);
2390 pr_warn("\nstack backtrace:\n");
2395 * Check whether we are holding such a class already.
2397 * (Note that this has to be done separately, because the graph cannot
2398 * detect such classes of deadlocks.)
2400 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
2403 check_deadlock(struct task_struct *curr, struct held_lock *next)
2405 struct held_lock *prev;
2406 struct held_lock *nest = NULL;
2409 for (i = 0; i < curr->lockdep_depth; i++) {
2410 prev = curr->held_locks + i;
2412 if (prev->instance == next->nest_lock)
2415 if (hlock_class(prev) != hlock_class(next))
2419 * Allow read-after-read recursion of the same
2420 * lock class (i.e. read_lock(lock)+read_lock(lock)):
2422 if ((next->read == 2) && prev->read)
2426 * We're holding the nest_lock, which serializes this lock's
2427 * nesting behaviour.
2432 print_deadlock_bug(curr, prev, next);
2439 * There was a chain-cache miss, and we are about to add a new dependency
2440 * to a previous lock. We validate the following rules:
2442 * - would the adding of the <prev> -> <next> dependency create a
2443 * circular dependency in the graph? [== circular deadlock]
2445 * - does the new prev->next dependency connect any hardirq-safe lock
2446 * (in the full backwards-subgraph starting at <prev>) with any
2447 * hardirq-unsafe lock (in the full forwards-subgraph starting at
2448 * <next>)? [== illegal lock inversion with hardirq contexts]
2450 * - does the new prev->next dependency connect any softirq-safe lock
2451 * (in the full backwards-subgraph starting at <prev>) with any
2452 * softirq-unsafe lock (in the full forwards-subgraph starting at
2453 * <next>)? [== illegal lock inversion with softirq contexts]
2455 * any of these scenarios could lead to a deadlock.
2457 * Then if all the validations pass, we add the forwards and backwards
2461 check_prev_add(struct task_struct *curr, struct held_lock *prev,
2462 struct held_lock *next, int distance,
2463 struct lock_trace **const trace)
2465 struct lock_list *entry;
2468 if (!hlock_class(prev)->key || !hlock_class(next)->key) {
2470 * The warning statements below may trigger a use-after-free
2471 * of the class name. It is better to trigger a use-after free
2472 * and to have the class name most of the time instead of not
2473 * having the class name available.
2475 WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key,
2476 "Detected use-after-free of lock class %px/%s\n",
2478 hlock_class(prev)->name);
2479 WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key,
2480 "Detected use-after-free of lock class %px/%s\n",
2482 hlock_class(next)->name);
2487 * Prove that the new <prev> -> <next> dependency would not
2488 * create a circular dependency in the graph. (We do this by
2489 * a breadth-first search into the graph starting at <next>,
2490 * and check whether we can reach <prev>.)
2492 * The search is limited by the size of the circular queue (i.e.,
2493 * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes
2494 * in the graph whose neighbours are to be checked.
2496 ret = check_noncircular(next, prev, trace);
2497 if (unlikely(ret <= 0))
2500 if (!check_irq_usage(curr, prev, next))
2504 * For recursive read-locks we do all the dependency checks,
2505 * but we dont store read-triggered dependencies (only
2506 * write-triggered dependencies). This ensures that only the
2507 * write-side dependencies matter, and that if for example a
2508 * write-lock never takes any other locks, then the reads are
2509 * equivalent to a NOP.
2511 if (next->read == 2 || prev->read == 2)
2514 * Is the <prev> -> <next> dependency already present?
2516 * (this may occur even though this is a new chain: consider
2517 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
2518 * chains - the second one will be new, but L1 already has
2519 * L2 added to its dependency list, due to the first chain.)
2521 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
2522 if (entry->class == hlock_class(next)) {
2524 entry->distance = 1;
2529 #ifdef CONFIG_LOCKDEP_SMALL
2531 * Is the <prev> -> <next> link redundant?
2533 ret = check_redundant(prev, next);
2539 *trace = save_trace();
2545 * Ok, all validations passed, add the new lock
2546 * to the previous lock's dependency list:
2548 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
2549 &hlock_class(prev)->locks_after,
2550 next->acquire_ip, distance, *trace);
2555 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
2556 &hlock_class(next)->locks_before,
2557 next->acquire_ip, distance, *trace);
2565 * Add the dependency to all directly-previous locks that are 'relevant'.
2566 * The ones that are relevant are (in increasing distance from curr):
2567 * all consecutive trylock entries and the final non-trylock entry - or
2568 * the end of this context's lock-chain - whichever comes first.
2571 check_prevs_add(struct task_struct *curr, struct held_lock *next)
2573 struct lock_trace *trace = NULL;
2574 int depth = curr->lockdep_depth;
2575 struct held_lock *hlock;
2580 * Depth must not be zero for a non-head lock:
2585 * At least two relevant locks must exist for this
2588 if (curr->held_locks[depth].irq_context !=
2589 curr->held_locks[depth-1].irq_context)
2593 int distance = curr->lockdep_depth - depth + 1;
2594 hlock = curr->held_locks + depth - 1;
2597 * Only non-recursive-read entries get new dependencies
2600 if (hlock->read != 2 && hlock->check) {
2601 int ret = check_prev_add(curr, hlock, next, distance,
2607 * Stop after the first non-trylock entry,
2608 * as non-trylock entries have added their
2609 * own direct dependencies already, so this
2610 * lock is connected to them indirectly:
2612 if (!hlock->trylock)
2618 * End of lock-stack?
2623 * Stop the search if we cross into another context:
2625 if (curr->held_locks[depth].irq_context !=
2626 curr->held_locks[depth-1].irq_context)
2631 if (!debug_locks_off_graph_unlock())
2635 * Clearly we all shouldn't be here, but since we made it we
2636 * can reliable say we messed up our state. See the above two
2637 * gotos for reasons why we could possibly end up here.
2644 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
2645 static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS);
2646 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
2647 unsigned long nr_zapped_lock_chains;
2648 unsigned int nr_free_chain_hlocks; /* Free chain_hlocks in buckets */
2649 unsigned int nr_lost_chain_hlocks; /* Lost chain_hlocks */
2650 unsigned int nr_large_chain_blocks; /* size > MAX_CHAIN_BUCKETS */
2653 * The first 2 chain_hlocks entries in the chain block in the bucket
2654 * list contains the following meta data:
2657 * Bit 15 - always set to 1 (it is not a class index)
2658 * Bits 0-14 - upper 15 bits of the next block index
2659 * entry[1] - lower 16 bits of next block index
2661 * A next block index of all 1 bits means it is the end of the list.
2663 * On the unsized bucket (bucket-0), the 3rd and 4th entries contain
2664 * the chain block size:
2666 * entry[2] - upper 16 bits of the chain block size
2667 * entry[3] - lower 16 bits of the chain block size
2669 #define MAX_CHAIN_BUCKETS 16
2670 #define CHAIN_BLK_FLAG (1U << 15)
2671 #define CHAIN_BLK_LIST_END 0xFFFFU
2673 static int chain_block_buckets[MAX_CHAIN_BUCKETS];
2675 static inline int size_to_bucket(int size)
2677 if (size > MAX_CHAIN_BUCKETS)
2684 * Iterate all the chain blocks in a bucket.
2686 #define for_each_chain_block(bucket, prev, curr) \
2687 for ((prev) = -1, (curr) = chain_block_buckets[bucket]; \
2689 (prev) = (curr), (curr) = chain_block_next(curr))
2694 static inline int chain_block_next(int offset)
2696 int next = chain_hlocks[offset];
2698 WARN_ON_ONCE(!(next & CHAIN_BLK_FLAG));
2700 if (next == CHAIN_BLK_LIST_END)
2703 next &= ~CHAIN_BLK_FLAG;
2705 next |= chain_hlocks[offset + 1];
2713 static inline int chain_block_size(int offset)
2715 return (chain_hlocks[offset + 2] << 16) | chain_hlocks[offset + 3];
2718 static inline void init_chain_block(int offset, int next, int bucket, int size)
2720 chain_hlocks[offset] = (next >> 16) | CHAIN_BLK_FLAG;
2721 chain_hlocks[offset + 1] = (u16)next;
2723 if (size && !bucket) {
2724 chain_hlocks[offset + 2] = size >> 16;
2725 chain_hlocks[offset + 3] = (u16)size;
2729 static inline void add_chain_block(int offset, int size)
2731 int bucket = size_to_bucket(size);
2732 int next = chain_block_buckets[bucket];
2735 if (unlikely(size < 2)) {
2737 * We can't store single entries on the freelist. Leak them.
2739 * One possible way out would be to uniquely mark them, other
2740 * than with CHAIN_BLK_FLAG, such that we can recover them when
2741 * the block before it is re-added.
2744 nr_lost_chain_hlocks++;
2748 nr_free_chain_hlocks += size;
2750 nr_large_chain_blocks++;
2753 * Variable sized, sort large to small.
2755 for_each_chain_block(0, prev, curr) {
2756 if (size >= chain_block_size(curr))
2759 init_chain_block(offset, curr, 0, size);
2761 chain_block_buckets[0] = offset;
2763 init_chain_block(prev, offset, 0, 0);
2767 * Fixed size, add to head.
2769 init_chain_block(offset, next, bucket, size);
2770 chain_block_buckets[bucket] = offset;
2774 * Only the first block in the list can be deleted.
2776 * For the variable size bucket[0], the first block (the largest one) is
2777 * returned, broken up and put back into the pool. So if a chain block of
2778 * length > MAX_CHAIN_BUCKETS is ever used and zapped, it will just be
2779 * queued up after the primordial chain block and never be used until the
2780 * hlock entries in the primordial chain block is almost used up. That
2781 * causes fragmentation and reduce allocation efficiency. That can be
2782 * monitored by looking at the "large chain blocks" number in lockdep_stats.
2784 static inline void del_chain_block(int bucket, int size, int next)
2786 nr_free_chain_hlocks -= size;
2787 chain_block_buckets[bucket] = next;
2790 nr_large_chain_blocks--;
2793 static void init_chain_block_buckets(void)
2797 for (i = 0; i < MAX_CHAIN_BUCKETS; i++)
2798 chain_block_buckets[i] = -1;
2800 add_chain_block(0, ARRAY_SIZE(chain_hlocks));
2804 * Return offset of a chain block of the right size or -1 if not found.
2806 * Fairly simple worst-fit allocator with the addition of a number of size
2807 * specific free lists.
2809 static int alloc_chain_hlocks(int req)
2811 int bucket, curr, size;
2814 * We rely on the MSB to act as an escape bit to denote freelist
2815 * pointers. Make sure this bit isn't set in 'normal' class_idx usage.
2817 BUILD_BUG_ON((MAX_LOCKDEP_KEYS-1) & CHAIN_BLK_FLAG);
2819 init_data_structures_once();
2821 if (nr_free_chain_hlocks < req)
2825 * We require a minimum of 2 (u16) entries to encode a freelist
2829 bucket = size_to_bucket(req);
2830 curr = chain_block_buckets[bucket];
2834 del_chain_block(bucket, req, chain_block_next(curr));
2838 curr = chain_block_buckets[0];
2842 * The variable sized freelist is sorted by size; the first entry is
2843 * the largest. Use it if it fits.
2846 size = chain_block_size(curr);
2847 if (likely(size >= req)) {
2848 del_chain_block(0, size, chain_block_next(curr));
2849 add_chain_block(curr + req, size - req);
2855 * Last resort, split a block in a larger sized bucket.
2857 for (size = MAX_CHAIN_BUCKETS; size > req; size--) {
2858 bucket = size_to_bucket(size);
2859 curr = chain_block_buckets[bucket];
2863 del_chain_block(bucket, size, chain_block_next(curr));
2864 add_chain_block(curr + req, size - req);
2871 static inline void free_chain_hlocks(int base, int size)
2873 add_chain_block(base, max(size, 2));
2876 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
2878 return lock_classes + chain_hlocks[chain->base + i];
2882 * Returns the index of the first held_lock of the current chain
2884 static inline int get_first_held_lock(struct task_struct *curr,
2885 struct held_lock *hlock)
2888 struct held_lock *hlock_curr;
2890 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2891 hlock_curr = curr->held_locks + i;
2892 if (hlock_curr->irq_context != hlock->irq_context)
2900 #ifdef CONFIG_DEBUG_LOCKDEP
2902 * Returns the next chain_key iteration
2904 static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2906 u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2908 printk(" class_idx:%d -> chain_key:%016Lx",
2910 (unsigned long long)new_chain_key);
2911 return new_chain_key;
2915 print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2917 struct held_lock *hlock;
2918 u64 chain_key = INITIAL_CHAIN_KEY;
2919 int depth = curr->lockdep_depth;
2920 int i = get_first_held_lock(curr, hlock_next);
2922 printk("depth: %u (irq_context %u)\n", depth - i + 1,
2923 hlock_next->irq_context);
2924 for (; i < depth; i++) {
2925 hlock = curr->held_locks + i;
2926 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2931 print_chain_key_iteration(hlock_next->class_idx, chain_key);
2932 print_lock(hlock_next);
2935 static void print_chain_keys_chain(struct lock_chain *chain)
2938 u64 chain_key = INITIAL_CHAIN_KEY;
2941 printk("depth: %u\n", chain->depth);
2942 for (i = 0; i < chain->depth; i++) {
2943 class_id = chain_hlocks[chain->base + i];
2944 chain_key = print_chain_key_iteration(class_id, chain_key);
2946 print_lock_name(lock_classes + class_id);
2951 static void print_collision(struct task_struct *curr,
2952 struct held_lock *hlock_next,
2953 struct lock_chain *chain)
2956 pr_warn("============================\n");
2957 pr_warn("WARNING: chain_key collision\n");
2958 print_kernel_ident();
2959 pr_warn("----------------------------\n");
2960 pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
2961 pr_warn("Hash chain already cached but the contents don't match!\n");
2963 pr_warn("Held locks:");
2964 print_chain_keys_held_locks(curr, hlock_next);
2966 pr_warn("Locks in cached chain:");
2967 print_chain_keys_chain(chain);
2969 pr_warn("\nstack backtrace:\n");
2975 * Checks whether the chain and the current held locks are consistent
2976 * in depth and also in content. If they are not it most likely means
2977 * that there was a collision during the calculation of the chain_key.
2978 * Returns: 0 not passed, 1 passed
2980 static int check_no_collision(struct task_struct *curr,
2981 struct held_lock *hlock,
2982 struct lock_chain *chain)
2984 #ifdef CONFIG_DEBUG_LOCKDEP
2987 i = get_first_held_lock(curr, hlock);
2989 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2990 print_collision(curr, hlock, chain);
2994 for (j = 0; j < chain->depth - 1; j++, i++) {
2995 id = curr->held_locks[i].class_idx;
2997 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2998 print_collision(curr, hlock, chain);
3007 * Given an index that is >= -1, return the index of the next lock chain.
3008 * Return -2 if there is no next lock chain.
3010 long lockdep_next_lockchain(long i)
3012 i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1);
3013 return i < ARRAY_SIZE(lock_chains) ? i : -2;
3016 unsigned long lock_chain_count(void)
3018 return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains));
3021 /* Must be called with the graph lock held. */
3022 static struct lock_chain *alloc_lock_chain(void)
3024 int idx = find_first_zero_bit(lock_chains_in_use,
3025 ARRAY_SIZE(lock_chains));
3027 if (unlikely(idx >= ARRAY_SIZE(lock_chains)))
3029 __set_bit(idx, lock_chains_in_use);
3030 return lock_chains + idx;
3034 * Adds a dependency chain into chain hashtable. And must be called with
3037 * Return 0 if fail, and graph_lock is released.
3038 * Return 1 if succeed, with graph_lock held.
3040 static inline int add_chain_cache(struct task_struct *curr,
3041 struct held_lock *hlock,
3044 struct lock_class *class = hlock_class(hlock);
3045 struct hlist_head *hash_head = chainhashentry(chain_key);
3046 struct lock_chain *chain;
3050 * The caller must hold the graph lock, ensure we've got IRQs
3051 * disabled to make this an IRQ-safe lock.. for recursion reasons
3052 * lockdep won't complain about its own locking errors.
3054 if (lockdep_assert_locked())
3057 chain = alloc_lock_chain();
3059 if (!debug_locks_off_graph_unlock())
3062 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
3066 chain->chain_key = chain_key;
3067 chain->irq_context = hlock->irq_context;
3068 i = get_first_held_lock(curr, hlock);
3069 chain->depth = curr->lockdep_depth + 1 - i;
3071 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
3072 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
3073 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
3075 j = alloc_chain_hlocks(chain->depth);
3077 if (!debug_locks_off_graph_unlock())
3080 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
3086 for (j = 0; j < chain->depth - 1; j++, i++) {
3087 int lock_id = curr->held_locks[i].class_idx;
3089 chain_hlocks[chain->base + j] = lock_id;
3091 chain_hlocks[chain->base + j] = class - lock_classes;
3092 hlist_add_head_rcu(&chain->entry, hash_head);
3093 debug_atomic_inc(chain_lookup_misses);
3094 inc_chains(chain->irq_context);
3100 * Look up a dependency chain. Must be called with either the graph lock or
3101 * the RCU read lock held.
3103 static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
3105 struct hlist_head *hash_head = chainhashentry(chain_key);
3106 struct lock_chain *chain;
3108 hlist_for_each_entry_rcu(chain, hash_head, entry) {
3109 if (READ_ONCE(chain->chain_key) == chain_key) {
3110 debug_atomic_inc(chain_lookup_hits);
3118 * If the key is not present yet in dependency chain cache then
3119 * add it and return 1 - in this case the new dependency chain is
3120 * validated. If the key is already hashed, return 0.
3121 * (On return with 1 graph_lock is held.)
3123 static inline int lookup_chain_cache_add(struct task_struct *curr,
3124 struct held_lock *hlock,
3127 struct lock_class *class = hlock_class(hlock);
3128 struct lock_chain *chain = lookup_chain_cache(chain_key);
3132 if (!check_no_collision(curr, hlock, chain))
3135 if (very_verbose(class)) {
3136 printk("\nhash chain already cached, key: "
3137 "%016Lx tail class: [%px] %s\n",
3138 (unsigned long long)chain_key,
3139 class->key, class->name);
3145 if (very_verbose(class)) {
3146 printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
3147 (unsigned long long)chain_key, class->key, class->name);
3154 * We have to walk the chain again locked - to avoid duplicates:
3156 chain = lookup_chain_cache(chain_key);
3162 if (!add_chain_cache(curr, hlock, chain_key))
3168 static int validate_chain(struct task_struct *curr,
3169 struct held_lock *hlock,
3170 int chain_head, u64 chain_key)
3173 * Trylock needs to maintain the stack of held locks, but it
3174 * does not add new dependencies, because trylock can be done
3177 * We look up the chain_key and do the O(N^2) check and update of
3178 * the dependencies only if this is a new dependency chain.
3179 * (If lookup_chain_cache_add() return with 1 it acquires
3180 * graph_lock for us)
3182 if (!hlock->trylock && hlock->check &&
3183 lookup_chain_cache_add(curr, hlock, chain_key)) {
3185 * Check whether last held lock:
3187 * - is irq-safe, if this lock is irq-unsafe
3188 * - is softirq-safe, if this lock is hardirq-unsafe
3190 * And check whether the new lock's dependency graph
3191 * could lead back to the previous lock:
3193 * - within the current held-lock stack
3194 * - across our accumulated lock dependency records
3196 * any of these scenarios could lead to a deadlock.
3199 * The simple case: does the current hold the same lock
3202 int ret = check_deadlock(curr, hlock);
3207 * Mark recursive read, as we jump over it when
3208 * building dependencies (just like we jump over
3214 * Add dependency only if this lock is not the head
3215 * of the chain, and if it's not a secondary read-lock:
3217 if (!chain_head && ret != 2) {
3218 if (!check_prevs_add(curr, hlock))
3224 /* after lookup_chain_cache_add(): */
3225 if (unlikely(!debug_locks))
3232 static inline int validate_chain(struct task_struct *curr,
3233 struct held_lock *hlock,
3234 int chain_head, u64 chain_key)
3239 static void init_chain_block_buckets(void) { }
3240 #endif /* CONFIG_PROVE_LOCKING */
3243 * We are building curr_chain_key incrementally, so double-check
3244 * it from scratch, to make sure that it's done correctly:
3246 static void check_chain_key(struct task_struct *curr)
3248 #ifdef CONFIG_DEBUG_LOCKDEP
3249 struct held_lock *hlock, *prev_hlock = NULL;
3251 u64 chain_key = INITIAL_CHAIN_KEY;
3253 for (i = 0; i < curr->lockdep_depth; i++) {
3254 hlock = curr->held_locks + i;
3255 if (chain_key != hlock->prev_chain_key) {
3258 * We got mighty confused, our chain keys don't match
3259 * with what we expect, someone trample on our task state?
3261 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
3262 curr->lockdep_depth, i,
3263 (unsigned long long)chain_key,
3264 (unsigned long long)hlock->prev_chain_key);
3269 * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is
3270 * it registered lock class index?
3272 if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use)))
3275 if (prev_hlock && (prev_hlock->irq_context !=
3276 hlock->irq_context))
3277 chain_key = INITIAL_CHAIN_KEY;
3278 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
3281 if (chain_key != curr->curr_chain_key) {
3284 * More smoking hash instead of calculating it, damn see these
3285 * numbers float.. I bet that a pink elephant stepped on my memory.
3287 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
3288 curr->lockdep_depth, i,
3289 (unsigned long long)chain_key,
3290 (unsigned long long)curr->curr_chain_key);
3295 #ifdef CONFIG_PROVE_LOCKING
3296 static int mark_lock(struct task_struct *curr, struct held_lock *this,
3297 enum lock_usage_bit new_bit);
3299 static void print_usage_bug_scenario(struct held_lock *lock)
3301 struct lock_class *class = hlock_class(lock);
3303 printk(" Possible unsafe locking scenario:\n\n");
3307 __print_lock_name(class);
3308 printk(KERN_CONT ");\n");
3309 printk(" <Interrupt>\n");
3311 __print_lock_name(class);
3312 printk(KERN_CONT ");\n");
3313 printk("\n *** DEADLOCK ***\n\n");
3317 print_usage_bug(struct task_struct *curr, struct held_lock *this,
3318 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
3320 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
3324 pr_warn("================================\n");
3325 pr_warn("WARNING: inconsistent lock state\n");
3326 print_kernel_ident();
3327 pr_warn("--------------------------------\n");
3329 pr_warn("inconsistent {%s} -> {%s} usage.\n",
3330 usage_str[prev_bit], usage_str[new_bit]);
3332 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
3333 curr->comm, task_pid_nr(curr),
3334 lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
3335 lockdep_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
3336 lockdep_hardirqs_enabled(),
3337 lockdep_softirqs_enabled(curr));
3340 pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
3341 print_lock_trace(hlock_class(this)->usage_traces[prev_bit], 1);
3343 print_irqtrace_events(curr);
3344 pr_warn("\nother info that might help us debug this:\n");
3345 print_usage_bug_scenario(this);
3347 lockdep_print_held_locks(curr);
3349 pr_warn("\nstack backtrace:\n");
3354 * Print out an error if an invalid bit is set:
3357 valid_state(struct task_struct *curr, struct held_lock *this,
3358 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
3360 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) {
3361 print_usage_bug(curr, this, bad_bit, new_bit);
3369 * print irq inversion bug:
3372 print_irq_inversion_bug(struct task_struct *curr,
3373 struct lock_list *root, struct lock_list *other,
3374 struct held_lock *this, int forwards,
3375 const char *irqclass)
3377 struct lock_list *entry = other;
3378 struct lock_list *middle = NULL;
3381 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
3385 pr_warn("========================================================\n");
3386 pr_warn("WARNING: possible irq lock inversion dependency detected\n");
3387 print_kernel_ident();
3388 pr_warn("--------------------------------------------------------\n");
3389 pr_warn("%s/%d just changed the state of lock:\n",
3390 curr->comm, task_pid_nr(curr));
3393 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
3395 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
3396 print_lock_name(other->class);
3397 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
3399 pr_warn("\nother info that might help us debug this:\n");
3401 /* Find a middle lock (if one exists) */
3402 depth = get_lock_depth(other);
3404 if (depth == 0 && (entry != root)) {
3405 pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
3409 entry = get_lock_parent(entry);
3411 } while (entry && entry != root && (depth >= 0));
3413 print_irq_lock_scenario(root, other,
3414 middle ? middle->class : root->class, other->class);
3416 print_irq_lock_scenario(other, root,
3417 middle ? middle->class : other->class, root->class);
3419 lockdep_print_held_locks(curr);
3421 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
3422 root->trace = save_trace();
3425 print_shortest_lock_dependencies(other, root);
3427 pr_warn("\nstack backtrace:\n");
3432 * Prove that in the forwards-direction subgraph starting at <this>
3433 * there is no lock matching <mask>:
3436 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
3437 enum lock_usage_bit bit, const char *irqclass)
3440 struct lock_list root;
3441 struct lock_list *target_entry;
3444 root.class = hlock_class(this);
3445 ret = find_usage_forwards(&root, lock_flag(bit), &target_entry);
3453 print_irq_inversion_bug(curr, &root, target_entry,
3459 * Prove that in the backwards-direction subgraph starting at <this>
3460 * there is no lock matching <mask>:
3463 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
3464 enum lock_usage_bit bit, const char *irqclass)
3467 struct lock_list root;
3468 struct lock_list *target_entry;
3471 root.class = hlock_class(this);
3472 ret = find_usage_backwards(&root, lock_flag(bit), &target_entry);
3480 print_irq_inversion_bug(curr, &root, target_entry,
3485 void print_irqtrace_events(struct task_struct *curr)
3487 const struct irqtrace_events *trace = &curr->irqtrace;
3489 printk("irq event stamp: %u\n", trace->irq_events);
3490 printk("hardirqs last enabled at (%u): [<%px>] %pS\n",
3491 trace->hardirq_enable_event, (void *)trace->hardirq_enable_ip,
3492 (void *)trace->hardirq_enable_ip);
3493 printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
3494 trace->hardirq_disable_event, (void *)trace->hardirq_disable_ip,
3495 (void *)trace->hardirq_disable_ip);
3496 printk("softirqs last enabled at (%u): [<%px>] %pS\n",
3497 trace->softirq_enable_event, (void *)trace->softirq_enable_ip,
3498 (void *)trace->softirq_enable_ip);
3499 printk("softirqs last disabled at (%u): [<%px>] %pS\n",
3500 trace->softirq_disable_event, (void *)trace->softirq_disable_ip,
3501 (void *)trace->softirq_disable_ip);
3504 static int HARDIRQ_verbose(struct lock_class *class)
3507 return class_filter(class);
3512 static int SOFTIRQ_verbose(struct lock_class *class)
3515 return class_filter(class);
3520 #define STRICT_READ_CHECKS 1
3522 static int (*state_verbose_f[])(struct lock_class *class) = {
3523 #define LOCKDEP_STATE(__STATE) \
3525 #include "lockdep_states.h"
3526 #undef LOCKDEP_STATE
3529 static inline int state_verbose(enum lock_usage_bit bit,
3530 struct lock_class *class)
3532 return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class);
3535 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
3536 enum lock_usage_bit bit, const char *name);
3539 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
3540 enum lock_usage_bit new_bit)
3542 int excl_bit = exclusive_bit(new_bit);
3543 int read = new_bit & LOCK_USAGE_READ_MASK;
3544 int dir = new_bit & LOCK_USAGE_DIR_MASK;
3547 * mark USED_IN has to look forwards -- to ensure no dependency
3548 * has ENABLED state, which would allow recursion deadlocks.
3550 * mark ENABLED has to look backwards -- to ensure no dependee
3551 * has USED_IN state, which, again, would allow recursion deadlocks.
3553 check_usage_f usage = dir ?
3554 check_usage_backwards : check_usage_forwards;
3557 * Validate that this particular lock does not have conflicting
3560 if (!valid_state(curr, this, new_bit, excl_bit))
3564 * Validate that the lock dependencies don't have conflicting usage
3567 if ((!read || STRICT_READ_CHECKS) &&
3568 !usage(curr, this, excl_bit, state_name(new_bit & ~LOCK_USAGE_READ_MASK)))
3572 * Check for read in write conflicts
3575 if (!valid_state(curr, this, new_bit, excl_bit + LOCK_USAGE_READ_MASK))
3578 if (STRICT_READ_CHECKS &&
3579 !usage(curr, this, excl_bit + LOCK_USAGE_READ_MASK,
3580 state_name(new_bit + LOCK_USAGE_READ_MASK)))
3584 if (state_verbose(new_bit, hlock_class(this)))
3591 * Mark all held locks with a usage bit:
3594 mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit)
3596 struct held_lock *hlock;
3599 for (i = 0; i < curr->lockdep_depth; i++) {
3600 enum lock_usage_bit hlock_bit = base_bit;
3601 hlock = curr->held_locks + i;
3604 hlock_bit += LOCK_USAGE_READ_MASK;
3606 BUG_ON(hlock_bit >= LOCK_USAGE_STATES);
3611 if (!mark_lock(curr, hlock, hlock_bit))
3619 * Hardirqs will be enabled:
3621 static void __trace_hardirqs_on_caller(void)
3623 struct task_struct *curr = current;
3626 * We are going to turn hardirqs on, so set the
3627 * usage bit for all held locks:
3629 if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ))
3632 * If we have softirqs enabled, then set the usage
3633 * bit for all held locks. (disabled hardirqs prevented
3634 * this bit from being set before)
3636 if (curr->softirqs_enabled)
3637 mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
3641 * lockdep_hardirqs_on_prepare - Prepare for enabling interrupts
3642 * @ip: Caller address
3644 * Invoked before a possible transition to RCU idle from exit to user or
3645 * guest mode. This ensures that all RCU operations are done before RCU
3646 * stops watching. After the RCU transition lockdep_hardirqs_on() has to be
3647 * invoked to set the final state.
3649 void lockdep_hardirqs_on_prepare(unsigned long ip)
3651 if (unlikely(!debug_locks))
3655 * NMIs do not (and cannot) track lock dependencies, nothing to do.
3657 if (unlikely(in_nmi()))
3660 if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
3663 if (unlikely(lockdep_hardirqs_enabled())) {
3665 * Neither irq nor preemption are disabled here
3666 * so this is racy by nature but losing one hit
3667 * in a stat is not a big deal.
3669 __debug_atomic_inc(redundant_hardirqs_on);
3674 * We're enabling irqs and according to our state above irqs weren't
3675 * already enabled, yet we find the hardware thinks they are in fact
3676 * enabled.. someone messed up their IRQ state tracing.
3678 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3682 * See the fine text that goes along with this variable definition.
3684 if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled))
3688 * Can't allow enabling interrupts while in an interrupt handler,
3689 * that's general bad form and such. Recursion, limited stack etc..
3691 if (DEBUG_LOCKS_WARN_ON(lockdep_hardirq_context()))
3694 current->hardirq_chain_key = current->curr_chain_key;
3696 current->lockdep_recursion++;
3697 __trace_hardirqs_on_caller();
3698 lockdep_recursion_finish();
3700 EXPORT_SYMBOL_GPL(lockdep_hardirqs_on_prepare);
3702 void noinstr lockdep_hardirqs_on(unsigned long ip)
3704 struct irqtrace_events *trace = ¤t->irqtrace;
3706 if (unlikely(!debug_locks))
3710 * NMIs can happen in the middle of local_irq_{en,dis}able() where the
3711 * tracking state and hardware state are out of sync.
3713 * NMIs must save lockdep_hardirqs_enabled() to restore IRQ state from,
3714 * and not rely on hardware state like normal interrupts.
3716 if (unlikely(in_nmi())) {
3717 if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
3722 * - recursion check, because NMI can hit lockdep;
3723 * - hardware state check, because above;
3724 * - chain_key check, see lockdep_hardirqs_on_prepare().
3729 if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
3732 if (lockdep_hardirqs_enabled()) {
3734 * Neither irq nor preemption are disabled here
3735 * so this is racy by nature but losing one hit
3736 * in a stat is not a big deal.
3738 __debug_atomic_inc(redundant_hardirqs_on);
3743 * We're enabling irqs and according to our state above irqs weren't
3744 * already enabled, yet we find the hardware thinks they are in fact
3745 * enabled.. someone messed up their IRQ state tracing.
3747 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3751 * Ensure the lock stack remained unchanged between
3752 * lockdep_hardirqs_on_prepare() and lockdep_hardirqs_on().
3754 DEBUG_LOCKS_WARN_ON(current->hardirq_chain_key !=
3755 current->curr_chain_key);
3758 /* we'll do an OFF -> ON transition: */
3759 this_cpu_write(hardirqs_enabled, 1);
3760 trace->hardirq_enable_ip = ip;
3761 trace->hardirq_enable_event = ++trace->irq_events;
3762 debug_atomic_inc(hardirqs_on_events);
3764 EXPORT_SYMBOL_GPL(lockdep_hardirqs_on);
3767 * Hardirqs were disabled:
3769 void noinstr lockdep_hardirqs_off(unsigned long ip)
3771 if (unlikely(!debug_locks))
3775 * Matching lockdep_hardirqs_on(), allow NMIs in the middle of lockdep;
3776 * they will restore the software state. This ensures the software
3777 * state is consistent inside NMIs as well.
3780 if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
3782 } else if (current->lockdep_recursion & LOCKDEP_RECURSION_MASK)
3786 * So we're supposed to get called after you mask local IRQs, but for
3787 * some reason the hardware doesn't quite think you did a proper job.
3789 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3792 if (lockdep_hardirqs_enabled()) {
3793 struct irqtrace_events *trace = ¤t->irqtrace;
3796 * We have done an ON -> OFF transition:
3798 this_cpu_write(hardirqs_enabled, 0);
3799 trace->hardirq_disable_ip = ip;
3800 trace->hardirq_disable_event = ++trace->irq_events;
3801 debug_atomic_inc(hardirqs_off_events);
3803 debug_atomic_inc(redundant_hardirqs_off);
3806 EXPORT_SYMBOL_GPL(lockdep_hardirqs_off);
3809 * Softirqs will be enabled:
3811 void lockdep_softirqs_on(unsigned long ip)
3813 struct irqtrace_events *trace = ¤t->irqtrace;
3815 if (unlikely(!debug_locks || current->lockdep_recursion))
3819 * We fancy IRQs being disabled here, see softirq.c, avoids
3820 * funny state and nesting things.
3822 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3825 if (current->softirqs_enabled) {
3826 debug_atomic_inc(redundant_softirqs_on);
3830 current->lockdep_recursion++;
3832 * We'll do an OFF -> ON transition:
3834 current->softirqs_enabled = 1;
3835 trace->softirq_enable_ip = ip;
3836 trace->softirq_enable_event = ++trace->irq_events;
3837 debug_atomic_inc(softirqs_on_events);
3839 * We are going to turn softirqs on, so set the
3840 * usage bit for all held locks, if hardirqs are
3843 if (lockdep_hardirqs_enabled())
3844 mark_held_locks(current, LOCK_ENABLED_SOFTIRQ);
3845 lockdep_recursion_finish();
3849 * Softirqs were disabled:
3851 void lockdep_softirqs_off(unsigned long ip)
3853 if (unlikely(!debug_locks || current->lockdep_recursion))
3857 * We fancy IRQs being disabled here, see softirq.c
3859 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3862 if (current->softirqs_enabled) {
3863 struct irqtrace_events *trace = ¤t->irqtrace;
3866 * We have done an ON -> OFF transition:
3868 current->softirqs_enabled = 0;
3869 trace->softirq_disable_ip = ip;
3870 trace->softirq_disable_event = ++trace->irq_events;
3871 debug_atomic_inc(softirqs_off_events);
3873 * Whoops, we wanted softirqs off, so why aren't they?
3875 DEBUG_LOCKS_WARN_ON(!softirq_count());
3877 debug_atomic_inc(redundant_softirqs_off);
3881 mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
3887 * If non-trylock use in a hardirq or softirq context, then
3888 * mark the lock as used in these contexts:
3890 if (!hlock->trylock) {
3892 if (lockdep_hardirq_context())
3893 if (!mark_lock(curr, hlock,
3894 LOCK_USED_IN_HARDIRQ_READ))
3896 if (curr->softirq_context)
3897 if (!mark_lock(curr, hlock,
3898 LOCK_USED_IN_SOFTIRQ_READ))
3901 if (lockdep_hardirq_context())
3902 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
3904 if (curr->softirq_context)
3905 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
3909 if (!hlock->hardirqs_off) {
3911 if (!mark_lock(curr, hlock,
3912 LOCK_ENABLED_HARDIRQ_READ))
3914 if (curr->softirqs_enabled)
3915 if (!mark_lock(curr, hlock,
3916 LOCK_ENABLED_SOFTIRQ_READ))
3919 if (!mark_lock(curr, hlock,
3920 LOCK_ENABLED_HARDIRQ))
3922 if (curr->softirqs_enabled)
3923 if (!mark_lock(curr, hlock,
3924 LOCK_ENABLED_SOFTIRQ))
3930 /* mark it as used: */
3931 if (!mark_lock(curr, hlock, LOCK_USED))
3937 static inline unsigned int task_irq_context(struct task_struct *task)
3939 return LOCK_CHAIN_HARDIRQ_CONTEXT * !!lockdep_hardirq_context() +
3940 LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context;
3943 static int separate_irq_context(struct task_struct *curr,
3944 struct held_lock *hlock)
3946 unsigned int depth = curr->lockdep_depth;
3949 * Keep track of points where we cross into an interrupt context:
3952 struct held_lock *prev_hlock;
3954 prev_hlock = curr->held_locks + depth-1;
3956 * If we cross into another context, reset the
3957 * hash key (this also prevents the checking and the
3958 * adding of the dependency to 'prev'):
3960 if (prev_hlock->irq_context != hlock->irq_context)
3967 * Mark a lock with a usage bit, and validate the state transition:
3969 static int mark_lock(struct task_struct *curr, struct held_lock *this,
3970 enum lock_usage_bit new_bit)
3972 unsigned int new_mask = 1 << new_bit, ret = 1;
3974 if (new_bit >= LOCK_USAGE_STATES) {
3975 DEBUG_LOCKS_WARN_ON(1);
3980 * If already set then do not dirty the cacheline,
3981 * nor do any checks:
3983 if (likely(hlock_class(this)->usage_mask & new_mask))
3989 * Make sure we didn't race:
3991 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3996 hlock_class(this)->usage_mask |= new_mask;
3998 if (!(hlock_class(this)->usage_traces[new_bit] = save_trace()))
4003 debug_atomic_dec(nr_unused_locks);
4006 ret = mark_lock_irq(curr, this, new_bit);
4014 * We must printk outside of the graph_lock:
4017 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
4019 print_irqtrace_events(curr);
4026 static inline short task_wait_context(struct task_struct *curr)
4029 * Set appropriate wait type for the context; for IRQs we have to take
4030 * into account force_irqthread as that is implied by PREEMPT_RT.
4032 if (lockdep_hardirq_context()) {
4034 * Check if force_irqthreads will run us threaded.
4036 if (curr->hardirq_threaded || curr->irq_config)
4037 return LD_WAIT_CONFIG;
4039 return LD_WAIT_SPIN;
4040 } else if (curr->softirq_context) {
4042 * Softirqs are always threaded.
4044 return LD_WAIT_CONFIG;
4051 print_lock_invalid_wait_context(struct task_struct *curr,
4052 struct held_lock *hlock)
4056 if (!debug_locks_off())
4058 if (debug_locks_silent)
4062 pr_warn("=============================\n");
4063 pr_warn("[ BUG: Invalid wait context ]\n");
4064 print_kernel_ident();
4065 pr_warn("-----------------------------\n");
4067 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
4070 pr_warn("other info that might help us debug this:\n");
4072 curr_inner = task_wait_context(curr);
4073 pr_warn("context-{%d:%d}\n", curr_inner, curr_inner);
4075 lockdep_print_held_locks(curr);
4077 pr_warn("stack backtrace:\n");
4084 * Verify the wait_type context.
4086 * This check validates we takes locks in the right wait-type order; that is it
4087 * ensures that we do not take mutexes inside spinlocks and do not attempt to
4088 * acquire spinlocks inside raw_spinlocks and the sort.
4090 * The entire thing is slightly more complex because of RCU, RCU is a lock that
4091 * can be taken from (pretty much) any context but also has constraints.
4092 * However when taken in a stricter environment the RCU lock does not loosen
4095 * Therefore we must look for the strictest environment in the lock stack and
4096 * compare that to the lock we're trying to acquire.
4098 static int check_wait_context(struct task_struct *curr, struct held_lock *next)
4100 short next_inner = hlock_class(next)->wait_type_inner;
4101 short next_outer = hlock_class(next)->wait_type_outer;
4105 if (!curr->lockdep_depth || !next_inner || next->trylock)
4109 next_outer = next_inner;
4112 * Find start of current irq_context..
4114 for (depth = curr->lockdep_depth - 1; depth >= 0; depth--) {
4115 struct held_lock *prev = curr->held_locks + depth;
4116 if (prev->irq_context != next->irq_context)
4121 curr_inner = task_wait_context(curr);
4123 for (; depth < curr->lockdep_depth; depth++) {
4124 struct held_lock *prev = curr->held_locks + depth;
4125 short prev_inner = hlock_class(prev)->wait_type_inner;
4129 * We can have a bigger inner than a previous one
4130 * when outer is smaller than inner, as with RCU.
4132 * Also due to trylocks.
4134 curr_inner = min(curr_inner, prev_inner);
4138 if (next_outer > curr_inner)
4139 return print_lock_invalid_wait_context(curr, next);
4144 #else /* CONFIG_PROVE_LOCKING */
4147 mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
4152 static inline unsigned int task_irq_context(struct task_struct *task)
4157 static inline int separate_irq_context(struct task_struct *curr,
4158 struct held_lock *hlock)
4163 static inline int check_wait_context(struct task_struct *curr,
4164 struct held_lock *next)
4169 #endif /* CONFIG_PROVE_LOCKING */
4172 * Initialize a lock instance's lock-class mapping info:
4174 void lockdep_init_map_waits(struct lockdep_map *lock, const char *name,
4175 struct lock_class_key *key, int subclass,
4176 short inner, short outer)
4180 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
4181 lock->class_cache[i] = NULL;
4183 #ifdef CONFIG_LOCK_STAT
4184 lock->cpu = raw_smp_processor_id();
4188 * Can't be having no nameless bastards around this place!
4190 if (DEBUG_LOCKS_WARN_ON(!name)) {
4191 lock->name = "NULL";
4197 lock->wait_type_outer = outer;
4198 lock->wait_type_inner = inner;
4201 * No key, no joy, we need to hash something.
4203 if (DEBUG_LOCKS_WARN_ON(!key))
4206 * Sanity check, the lock-class key must either have been allocated
4207 * statically or must have been registered as a dynamic key.
4209 if (!static_obj(key) && !is_dynamic_key(key)) {
4211 printk(KERN_ERR "BUG: key %px has not been registered!\n", key);
4212 DEBUG_LOCKS_WARN_ON(1);
4217 if (unlikely(!debug_locks))
4221 unsigned long flags;
4223 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
4226 raw_local_irq_save(flags);
4227 current->lockdep_recursion++;
4228 register_lock_class(lock, subclass, 1);
4229 lockdep_recursion_finish();
4230 raw_local_irq_restore(flags);
4233 EXPORT_SYMBOL_GPL(lockdep_init_map_waits);
4235 struct lock_class_key __lockdep_no_validate__;
4236 EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
4239 print_lock_nested_lock_not_held(struct task_struct *curr,
4240 struct held_lock *hlock,
4243 if (!debug_locks_off())
4245 if (debug_locks_silent)
4249 pr_warn("==================================\n");
4250 pr_warn("WARNING: Nested lock was not taken\n");
4251 print_kernel_ident();
4252 pr_warn("----------------------------------\n");
4254 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
4257 pr_warn("\nbut this task is not holding:\n");
4258 pr_warn("%s\n", hlock->nest_lock->name);
4260 pr_warn("\nstack backtrace:\n");
4263 pr_warn("\nother info that might help us debug this:\n");
4264 lockdep_print_held_locks(curr);
4266 pr_warn("\nstack backtrace:\n");
4270 static int __lock_is_held(const struct lockdep_map *lock, int read);
4273 * This gets called for every mutex_lock*()/spin_lock*() operation.
4274 * We maintain the dependency maps and validate the locking attempt:
4276 * The callers must make sure that IRQs are disabled before calling it,
4277 * otherwise we could get an interrupt which would want to take locks,
4278 * which would end up in lockdep again.
4280 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
4281 int trylock, int read, int check, int hardirqs_off,
4282 struct lockdep_map *nest_lock, unsigned long ip,
4283 int references, int pin_count)
4285 struct task_struct *curr = current;
4286 struct lock_class *class = NULL;
4287 struct held_lock *hlock;
4293 if (unlikely(!debug_locks))
4296 if (!prove_locking || lock->key == &__lockdep_no_validate__)
4299 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
4300 class = lock->class_cache[subclass];
4304 if (unlikely(!class)) {
4305 class = register_lock_class(lock, subclass, 0);
4310 debug_class_ops_inc(class);
4312 if (very_verbose(class)) {
4313 printk("\nacquire class [%px] %s", class->key, class->name);
4314 if (class->name_version > 1)
4315 printk(KERN_CONT "#%d", class->name_version);
4316 printk(KERN_CONT "\n");
4321 * Add the lock to the list of currently held locks.
4322 * (we dont increase the depth just yet, up until the
4323 * dependency checks are done)
4325 depth = curr->lockdep_depth;
4327 * Ran out of static storage for our per-task lock stack again have we?
4329 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
4332 class_idx = class - lock_classes;
4334 if (depth) { /* we're holding locks */
4335 hlock = curr->held_locks + depth - 1;
4336 if (hlock->class_idx == class_idx && nest_lock) {
4340 if (!hlock->references)
4341 hlock->references++;
4343 hlock->references += references;
4346 if (DEBUG_LOCKS_WARN_ON(hlock->references < references))
4353 hlock = curr->held_locks + depth;
4355 * Plain impossible, we just registered it and checked it weren't no
4356 * NULL like.. I bet this mushroom I ate was good!
4358 if (DEBUG_LOCKS_WARN_ON(!class))
4360 hlock->class_idx = class_idx;
4361 hlock->acquire_ip = ip;
4362 hlock->instance = lock;
4363 hlock->nest_lock = nest_lock;
4364 hlock->irq_context = task_irq_context(curr);
4365 hlock->trylock = trylock;
4367 hlock->check = check;
4368 hlock->hardirqs_off = !!hardirqs_off;
4369 hlock->references = references;
4370 #ifdef CONFIG_LOCK_STAT
4371 hlock->waittime_stamp = 0;
4372 hlock->holdtime_stamp = lockstat_clock();
4374 hlock->pin_count = pin_count;
4376 if (check_wait_context(curr, hlock))
4379 /* Initialize the lock usage bit */
4380 if (!mark_usage(curr, hlock, check))
4384 * Calculate the chain hash: it's the combined hash of all the
4385 * lock keys along the dependency chain. We save the hash value
4386 * at every step so that we can get the current hash easily
4387 * after unlock. The chain hash is then used to cache dependency
4390 * The 'key ID' is what is the most compact key value to drive
4391 * the hash, not class->key.
4394 * Whoops, we did it again.. class_idx is invalid.
4396 if (DEBUG_LOCKS_WARN_ON(!test_bit(class_idx, lock_classes_in_use)))
4399 chain_key = curr->curr_chain_key;
4402 * How can we have a chain hash when we ain't got no keys?!
4404 if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY))
4409 hlock->prev_chain_key = chain_key;
4410 if (separate_irq_context(curr, hlock)) {
4411 chain_key = INITIAL_CHAIN_KEY;
4414 chain_key = iterate_chain_key(chain_key, class_idx);
4416 if (nest_lock && !__lock_is_held(nest_lock, -1)) {
4417 print_lock_nested_lock_not_held(curr, hlock, ip);
4421 if (!debug_locks_silent) {
4422 WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key);
4423 WARN_ON_ONCE(!hlock_class(hlock)->key);
4426 if (!validate_chain(curr, hlock, chain_head, chain_key))
4429 curr->curr_chain_key = chain_key;
4430 curr->lockdep_depth++;
4431 check_chain_key(curr);
4432 #ifdef CONFIG_DEBUG_LOCKDEP
4433 if (unlikely(!debug_locks))
4436 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
4438 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
4439 printk(KERN_DEBUG "depth: %i max: %lu!\n",
4440 curr->lockdep_depth, MAX_LOCK_DEPTH);
4442 lockdep_print_held_locks(current);
4443 debug_show_all_locks();
4449 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
4450 max_lockdep_depth = curr->lockdep_depth;
4455 static void print_unlock_imbalance_bug(struct task_struct *curr,
4456 struct lockdep_map *lock,
4459 if (!debug_locks_off())
4461 if (debug_locks_silent)
4465 pr_warn("=====================================\n");
4466 pr_warn("WARNING: bad unlock balance detected!\n");
4467 print_kernel_ident();
4468 pr_warn("-------------------------------------\n");
4469 pr_warn("%s/%d is trying to release lock (",
4470 curr->comm, task_pid_nr(curr));
4471 print_lockdep_cache(lock);
4473 print_ip_sym(KERN_WARNING, ip);
4474 pr_warn("but there are no more locks to release!\n");
4475 pr_warn("\nother info that might help us debug this:\n");
4476 lockdep_print_held_locks(curr);
4478 pr_warn("\nstack backtrace:\n");
4482 static noinstr int match_held_lock(const struct held_lock *hlock,
4483 const struct lockdep_map *lock)
4485 if (hlock->instance == lock)
4488 if (hlock->references) {
4489 const struct lock_class *class = lock->class_cache[0];
4492 class = look_up_lock_class(lock, 0);
4495 * If look_up_lock_class() failed to find a class, we're trying
4496 * to test if we hold a lock that has never yet been acquired.
4497 * Clearly if the lock hasn't been acquired _ever_, we're not
4498 * holding it either, so report failure.
4504 * References, but not a lock we're actually ref-counting?
4505 * State got messed up, follow the sites that change ->references
4506 * and try to make sense of it.
4508 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
4511 if (hlock->class_idx == class - lock_classes)
4518 /* @depth must not be zero */
4519 static struct held_lock *find_held_lock(struct task_struct *curr,
4520 struct lockdep_map *lock,
4521 unsigned int depth, int *idx)
4523 struct held_lock *ret, *hlock, *prev_hlock;
4527 hlock = curr->held_locks + i;
4529 if (match_held_lock(hlock, lock))
4533 for (i--, prev_hlock = hlock--;
4535 i--, prev_hlock = hlock--) {
4537 * We must not cross into another context:
4539 if (prev_hlock->irq_context != hlock->irq_context) {
4543 if (match_held_lock(hlock, lock)) {
4554 static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
4555 int idx, unsigned int *merged)
4557 struct held_lock *hlock;
4558 int first_idx = idx;
4560 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4563 for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
4564 switch (__lock_acquire(hlock->instance,
4565 hlock_class(hlock)->subclass,
4567 hlock->read, hlock->check,
4568 hlock->hardirqs_off,
4569 hlock->nest_lock, hlock->acquire_ip,
4570 hlock->references, hlock->pin_count)) {
4576 *merged += (idx == first_idx);
4587 __lock_set_class(struct lockdep_map *lock, const char *name,
4588 struct lock_class_key *key, unsigned int subclass,
4591 struct task_struct *curr = current;
4592 unsigned int depth, merged = 0;
4593 struct held_lock *hlock;
4594 struct lock_class *class;
4597 if (unlikely(!debug_locks))
4600 depth = curr->lockdep_depth;
4602 * This function is about (re)setting the class of a held lock,
4603 * yet we're not actually holding any locks. Naughty user!
4605 if (DEBUG_LOCKS_WARN_ON(!depth))
4608 hlock = find_held_lock(curr, lock, depth, &i);
4610 print_unlock_imbalance_bug(curr, lock, ip);
4614 lockdep_init_map_waits(lock, name, key, 0,
4615 lock->wait_type_inner,
4616 lock->wait_type_outer);
4617 class = register_lock_class(lock, subclass, 0);
4618 hlock->class_idx = class - lock_classes;
4620 curr->lockdep_depth = i;
4621 curr->curr_chain_key = hlock->prev_chain_key;
4623 if (reacquire_held_locks(curr, depth, i, &merged))
4627 * I took it apart and put it back together again, except now I have
4628 * these 'spare' parts.. where shall I put them.
4630 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged))
4635 static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
4637 struct task_struct *curr = current;
4638 unsigned int depth, merged = 0;
4639 struct held_lock *hlock;
4642 if (unlikely(!debug_locks))
4645 depth = curr->lockdep_depth;
4647 * This function is about (re)setting the class of a held lock,
4648 * yet we're not actually holding any locks. Naughty user!
4650 if (DEBUG_LOCKS_WARN_ON(!depth))
4653 hlock = find_held_lock(curr, lock, depth, &i);
4655 print_unlock_imbalance_bug(curr, lock, ip);
4659 curr->lockdep_depth = i;
4660 curr->curr_chain_key = hlock->prev_chain_key;
4662 WARN(hlock->read, "downgrading a read lock");
4664 hlock->acquire_ip = ip;
4666 if (reacquire_held_locks(curr, depth, i, &merged))
4669 /* Merging can't happen with unchanged classes.. */
4670 if (DEBUG_LOCKS_WARN_ON(merged))
4674 * I took it apart and put it back together again, except now I have
4675 * these 'spare' parts.. where shall I put them.
4677 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
4684 * Remove the lock from the list of currently held locks - this gets
4685 * called on mutex_unlock()/spin_unlock*() (or on a failed
4686 * mutex_lock_interruptible()).
4689 __lock_release(struct lockdep_map *lock, unsigned long ip)
4691 struct task_struct *curr = current;
4692 unsigned int depth, merged = 1;
4693 struct held_lock *hlock;
4696 if (unlikely(!debug_locks))
4699 depth = curr->lockdep_depth;
4701 * So we're all set to release this lock.. wait what lock? We don't
4702 * own any locks, you've been drinking again?
4705 print_unlock_imbalance_bug(curr, lock, ip);
4710 * Check whether the lock exists in the current stack
4713 hlock = find_held_lock(curr, lock, depth, &i);
4715 print_unlock_imbalance_bug(curr, lock, ip);
4719 if (hlock->instance == lock)
4720 lock_release_holdtime(hlock);
4722 WARN(hlock->pin_count, "releasing a pinned lock\n");
4724 if (hlock->references) {
4725 hlock->references--;
4726 if (hlock->references) {
4728 * We had, and after removing one, still have
4729 * references, the current lock stack is still
4730 * valid. We're done!
4737 * We have the right lock to unlock, 'hlock' points to it.
4738 * Now we remove it from the stack, and add back the other
4739 * entries (if any), recalculating the hash along the way:
4742 curr->lockdep_depth = i;
4743 curr->curr_chain_key = hlock->prev_chain_key;
4746 * The most likely case is when the unlock is on the innermost
4747 * lock. In this case, we are done!
4752 if (reacquire_held_locks(curr, depth, i + 1, &merged))
4756 * We had N bottles of beer on the wall, we drank one, but now
4757 * there's not N-1 bottles of beer left on the wall...
4758 * Pouring two of the bottles together is acceptable.
4760 DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged);
4763 * Since reacquire_held_locks() would have called check_chain_key()
4764 * indirectly via __lock_acquire(), we don't need to do it again
4770 static __always_inline
4771 int __lock_is_held(const struct lockdep_map *lock, int read)
4773 struct task_struct *curr = current;
4776 for (i = 0; i < curr->lockdep_depth; i++) {
4777 struct held_lock *hlock = curr->held_locks + i;
4779 if (match_held_lock(hlock, lock)) {
4780 if (read == -1 || hlock->read == read)
4790 static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
4792 struct pin_cookie cookie = NIL_COOKIE;
4793 struct task_struct *curr = current;
4796 if (unlikely(!debug_locks))
4799 for (i = 0; i < curr->lockdep_depth; i++) {
4800 struct held_lock *hlock = curr->held_locks + i;
4802 if (match_held_lock(hlock, lock)) {
4804 * Grab 16bits of randomness; this is sufficient to not
4805 * be guessable and still allows some pin nesting in
4806 * our u32 pin_count.
4808 cookie.val = 1 + (prandom_u32() >> 16);
4809 hlock->pin_count += cookie.val;
4814 WARN(1, "pinning an unheld lock\n");
4818 static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4820 struct task_struct *curr = current;
4823 if (unlikely(!debug_locks))
4826 for (i = 0; i < curr->lockdep_depth; i++) {
4827 struct held_lock *hlock = curr->held_locks + i;
4829 if (match_held_lock(hlock, lock)) {
4830 hlock->pin_count += cookie.val;
4835 WARN(1, "pinning an unheld lock\n");
4838 static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4840 struct task_struct *curr = current;
4843 if (unlikely(!debug_locks))
4846 for (i = 0; i < curr->lockdep_depth; i++) {
4847 struct held_lock *hlock = curr->held_locks + i;
4849 if (match_held_lock(hlock, lock)) {
4850 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
4853 hlock->pin_count -= cookie.val;
4855 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
4856 hlock->pin_count = 0;
4862 WARN(1, "unpinning an unheld lock\n");
4866 * Check whether we follow the irq-flags state precisely:
4868 static void check_flags(unsigned long flags)
4870 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP)
4874 if (irqs_disabled_flags(flags)) {
4875 if (DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())) {
4876 printk("possible reason: unannotated irqs-off.\n");
4879 if (DEBUG_LOCKS_WARN_ON(!lockdep_hardirqs_enabled())) {
4880 printk("possible reason: unannotated irqs-on.\n");
4885 * We dont accurately track softirq state in e.g.
4886 * hardirq contexts (such as on 4KSTACKS), so only
4887 * check if not in hardirq contexts:
4889 if (!hardirq_count()) {
4890 if (softirq_count()) {
4891 /* like the above, but with softirqs */
4892 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
4894 /* lick the above, does it taste good? */
4895 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
4900 print_irqtrace_events(current);
4904 void lock_set_class(struct lockdep_map *lock, const char *name,
4905 struct lock_class_key *key, unsigned int subclass,
4908 unsigned long flags;
4910 if (unlikely(current->lockdep_recursion))
4913 raw_local_irq_save(flags);
4914 current->lockdep_recursion++;
4916 if (__lock_set_class(lock, name, key, subclass, ip))
4917 check_chain_key(current);
4918 lockdep_recursion_finish();
4919 raw_local_irq_restore(flags);
4921 EXPORT_SYMBOL_GPL(lock_set_class);
4923 void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
4925 unsigned long flags;
4927 if (unlikely(current->lockdep_recursion))
4930 raw_local_irq_save(flags);
4931 current->lockdep_recursion++;
4933 if (__lock_downgrade(lock, ip))
4934 check_chain_key(current);
4935 lockdep_recursion_finish();
4936 raw_local_irq_restore(flags);
4938 EXPORT_SYMBOL_GPL(lock_downgrade);
4940 /* NMI context !!! */
4941 static void verify_lock_unused(struct lockdep_map *lock, struct held_lock *hlock, int subclass)
4943 #ifdef CONFIG_PROVE_LOCKING
4944 struct lock_class *class = look_up_lock_class(lock, subclass);
4946 /* if it doesn't have a class (yet), it certainly hasn't been used yet */
4950 if (!(class->usage_mask & LOCK_USED))
4953 hlock->class_idx = class - lock_classes;
4955 print_usage_bug(current, hlock, LOCK_USED, LOCK_USAGE_STATES);
4959 static bool lockdep_nmi(void)
4961 if (current->lockdep_recursion & LOCKDEP_RECURSION_MASK)
4971 * We are not always called with irqs disabled - do that here,
4972 * and also avoid lockdep recursion:
4974 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
4975 int trylock, int read, int check,
4976 struct lockdep_map *nest_lock, unsigned long ip)
4978 unsigned long flags;
4980 if (unlikely(current->lockdep_recursion)) {
4981 /* XXX allow trylock from NMI ?!? */
4982 if (lockdep_nmi() && !trylock) {
4983 struct held_lock hlock;
4985 hlock.acquire_ip = ip;
4986 hlock.instance = lock;
4987 hlock.nest_lock = nest_lock;
4988 hlock.irq_context = 2; // XXX
4989 hlock.trylock = trylock;
4991 hlock.check = check;
4992 hlock.hardirqs_off = true;
4993 hlock.references = 0;
4995 verify_lock_unused(lock, &hlock, subclass);
5000 raw_local_irq_save(flags);
5003 current->lockdep_recursion++;
5004 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
5005 __lock_acquire(lock, subclass, trylock, read, check,
5006 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
5007 lockdep_recursion_finish();
5008 raw_local_irq_restore(flags);
5010 EXPORT_SYMBOL_GPL(lock_acquire);
5012 void lock_release(struct lockdep_map *lock, unsigned long ip)
5014 unsigned long flags;
5016 if (unlikely(current->lockdep_recursion))
5019 raw_local_irq_save(flags);
5021 current->lockdep_recursion++;
5022 trace_lock_release(lock, ip);
5023 if (__lock_release(lock, ip))
5024 check_chain_key(current);
5025 lockdep_recursion_finish();
5026 raw_local_irq_restore(flags);
5028 EXPORT_SYMBOL_GPL(lock_release);
5030 noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
5032 unsigned long flags;
5035 if (unlikely(current->lockdep_recursion))
5036 return 1; /* avoid false negative lockdep_assert_held() */
5038 raw_local_irq_save(flags);
5041 current->lockdep_recursion++;
5042 ret = __lock_is_held(lock, read);
5043 lockdep_recursion_finish();
5044 raw_local_irq_restore(flags);
5048 EXPORT_SYMBOL_GPL(lock_is_held_type);
5049 NOKPROBE_SYMBOL(lock_is_held_type);
5051 struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
5053 struct pin_cookie cookie = NIL_COOKIE;
5054 unsigned long flags;
5056 if (unlikely(current->lockdep_recursion))
5059 raw_local_irq_save(flags);
5062 current->lockdep_recursion++;
5063 cookie = __lock_pin_lock(lock);
5064 lockdep_recursion_finish();
5065 raw_local_irq_restore(flags);
5069 EXPORT_SYMBOL_GPL(lock_pin_lock);
5071 void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5073 unsigned long flags;
5075 if (unlikely(current->lockdep_recursion))
5078 raw_local_irq_save(flags);
5081 current->lockdep_recursion++;
5082 __lock_repin_lock(lock, cookie);
5083 lockdep_recursion_finish();
5084 raw_local_irq_restore(flags);
5086 EXPORT_SYMBOL_GPL(lock_repin_lock);
5088 void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5090 unsigned long flags;
5092 if (unlikely(current->lockdep_recursion))
5095 raw_local_irq_save(flags);
5098 current->lockdep_recursion++;
5099 __lock_unpin_lock(lock, cookie);
5100 lockdep_recursion_finish();
5101 raw_local_irq_restore(flags);
5103 EXPORT_SYMBOL_GPL(lock_unpin_lock);
5105 #ifdef CONFIG_LOCK_STAT
5106 static void print_lock_contention_bug(struct task_struct *curr,
5107 struct lockdep_map *lock,
5110 if (!debug_locks_off())
5112 if (debug_locks_silent)
5116 pr_warn("=================================\n");
5117 pr_warn("WARNING: bad contention detected!\n");
5118 print_kernel_ident();
5119 pr_warn("---------------------------------\n");
5120 pr_warn("%s/%d is trying to contend lock (",
5121 curr->comm, task_pid_nr(curr));
5122 print_lockdep_cache(lock);
5124 print_ip_sym(KERN_WARNING, ip);
5125 pr_warn("but there are no locks held!\n");
5126 pr_warn("\nother info that might help us debug this:\n");
5127 lockdep_print_held_locks(curr);
5129 pr_warn("\nstack backtrace:\n");
5134 __lock_contended(struct lockdep_map *lock, unsigned long ip)
5136 struct task_struct *curr = current;
5137 struct held_lock *hlock;
5138 struct lock_class_stats *stats;
5140 int i, contention_point, contending_point;
5142 depth = curr->lockdep_depth;
5144 * Whee, we contended on this lock, except it seems we're not
5145 * actually trying to acquire anything much at all..
5147 if (DEBUG_LOCKS_WARN_ON(!depth))
5150 hlock = find_held_lock(curr, lock, depth, &i);
5152 print_lock_contention_bug(curr, lock, ip);
5156 if (hlock->instance != lock)
5159 hlock->waittime_stamp = lockstat_clock();
5161 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
5162 contending_point = lock_point(hlock_class(hlock)->contending_point,
5165 stats = get_lock_stats(hlock_class(hlock));
5166 if (contention_point < LOCKSTAT_POINTS)
5167 stats->contention_point[contention_point]++;
5168 if (contending_point < LOCKSTAT_POINTS)
5169 stats->contending_point[contending_point]++;
5170 if (lock->cpu != smp_processor_id())
5171 stats->bounces[bounce_contended + !!hlock->read]++;
5175 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
5177 struct task_struct *curr = current;
5178 struct held_lock *hlock;
5179 struct lock_class_stats *stats;
5181 u64 now, waittime = 0;
5184 depth = curr->lockdep_depth;
5186 * Yay, we acquired ownership of this lock we didn't try to
5187 * acquire, how the heck did that happen?
5189 if (DEBUG_LOCKS_WARN_ON(!depth))
5192 hlock = find_held_lock(curr, lock, depth, &i);
5194 print_lock_contention_bug(curr, lock, _RET_IP_);
5198 if (hlock->instance != lock)
5201 cpu = smp_processor_id();
5202 if (hlock->waittime_stamp) {
5203 now = lockstat_clock();
5204 waittime = now - hlock->waittime_stamp;
5205 hlock->holdtime_stamp = now;
5208 trace_lock_acquired(lock, ip);
5210 stats = get_lock_stats(hlock_class(hlock));
5213 lock_time_inc(&stats->read_waittime, waittime);
5215 lock_time_inc(&stats->write_waittime, waittime);
5217 if (lock->cpu != cpu)
5218 stats->bounces[bounce_acquired + !!hlock->read]++;
5224 void lock_contended(struct lockdep_map *lock, unsigned long ip)
5226 unsigned long flags;
5228 if (unlikely(!lock_stat || !debug_locks))
5231 if (unlikely(current->lockdep_recursion))
5234 raw_local_irq_save(flags);
5236 current->lockdep_recursion++;
5237 trace_lock_contended(lock, ip);
5238 __lock_contended(lock, ip);
5239 lockdep_recursion_finish();
5240 raw_local_irq_restore(flags);
5242 EXPORT_SYMBOL_GPL(lock_contended);
5244 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
5246 unsigned long flags;
5248 if (unlikely(!lock_stat || !debug_locks))
5251 if (unlikely(current->lockdep_recursion))
5254 raw_local_irq_save(flags);
5256 current->lockdep_recursion++;
5257 __lock_acquired(lock, ip);
5258 lockdep_recursion_finish();
5259 raw_local_irq_restore(flags);
5261 EXPORT_SYMBOL_GPL(lock_acquired);
5265 * Used by the testsuite, sanitize the validator state
5266 * after a simulated failure:
5269 void lockdep_reset(void)
5271 unsigned long flags;
5274 raw_local_irq_save(flags);
5275 lockdep_init_task(current);
5276 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
5277 nr_hardirq_chains = 0;
5278 nr_softirq_chains = 0;
5279 nr_process_chains = 0;
5281 for (i = 0; i < CHAINHASH_SIZE; i++)
5282 INIT_HLIST_HEAD(chainhash_table + i);
5283 raw_local_irq_restore(flags);
5286 /* Remove a class from a lock chain. Must be called with the graph lock held. */
5287 static void remove_class_from_lock_chain(struct pending_free *pf,
5288 struct lock_chain *chain,
5289 struct lock_class *class)
5291 #ifdef CONFIG_PROVE_LOCKING
5294 for (i = chain->base; i < chain->base + chain->depth; i++) {
5295 if (chain_hlocks[i] != class - lock_classes)
5298 * Each lock class occurs at most once in a lock chain so once
5299 * we found a match we can break out of this loop.
5301 goto free_lock_chain;
5303 /* Since the chain has not been modified, return. */
5307 free_chain_hlocks(chain->base, chain->depth);
5308 /* Overwrite the chain key for concurrent RCU readers. */
5309 WRITE_ONCE(chain->chain_key, INITIAL_CHAIN_KEY);
5310 dec_chains(chain->irq_context);
5313 * Note: calling hlist_del_rcu() from inside a
5314 * hlist_for_each_entry_rcu() loop is safe.
5316 hlist_del_rcu(&chain->entry);
5317 __set_bit(chain - lock_chains, pf->lock_chains_being_freed);
5318 nr_zapped_lock_chains++;
5322 /* Must be called with the graph lock held. */
5323 static void remove_class_from_lock_chains(struct pending_free *pf,
5324 struct lock_class *class)
5326 struct lock_chain *chain;
5327 struct hlist_head *head;
5330 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
5331 head = chainhash_table + i;
5332 hlist_for_each_entry_rcu(chain, head, entry) {
5333 remove_class_from_lock_chain(pf, chain, class);
5339 * Remove all references to a lock class. The caller must hold the graph lock.
5341 static void zap_class(struct pending_free *pf, struct lock_class *class)
5343 struct lock_list *entry;
5346 WARN_ON_ONCE(!class->key);
5349 * Remove all dependencies this lock is
5352 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
5353 entry = list_entries + i;
5354 if (entry->class != class && entry->links_to != class)
5356 __clear_bit(i, list_entries_in_use);
5358 list_del_rcu(&entry->entry);
5360 if (list_empty(&class->locks_after) &&
5361 list_empty(&class->locks_before)) {
5362 list_move_tail(&class->lock_entry, &pf->zapped);
5363 hlist_del_rcu(&class->hash_entry);
5364 WRITE_ONCE(class->key, NULL);
5365 WRITE_ONCE(class->name, NULL);
5367 __clear_bit(class - lock_classes, lock_classes_in_use);
5369 WARN_ONCE(true, "%s() failed for class %s\n", __func__,
5373 remove_class_from_lock_chains(pf, class);
5374 nr_zapped_classes++;
5377 static void reinit_class(struct lock_class *class)
5379 void *const p = class;
5380 const unsigned int offset = offsetof(struct lock_class, key);
5382 WARN_ON_ONCE(!class->lock_entry.next);
5383 WARN_ON_ONCE(!list_empty(&class->locks_after));
5384 WARN_ON_ONCE(!list_empty(&class->locks_before));
5385 memset(p + offset, 0, sizeof(*class) - offset);
5386 WARN_ON_ONCE(!class->lock_entry.next);
5387 WARN_ON_ONCE(!list_empty(&class->locks_after));
5388 WARN_ON_ONCE(!list_empty(&class->locks_before));
5391 static inline int within(const void *addr, void *start, unsigned long size)
5393 return addr >= start && addr < start + size;
5396 static bool inside_selftest(void)
5398 return current == lockdep_selftest_task_struct;
5401 /* The caller must hold the graph lock. */
5402 static struct pending_free *get_pending_free(void)
5404 return delayed_free.pf + delayed_free.index;
5407 static void free_zapped_rcu(struct rcu_head *cb);
5410 * Schedule an RCU callback if no RCU callback is pending. Must be called with
5411 * the graph lock held.
5413 static void call_rcu_zapped(struct pending_free *pf)
5415 WARN_ON_ONCE(inside_selftest());
5417 if (list_empty(&pf->zapped))
5420 if (delayed_free.scheduled)
5423 delayed_free.scheduled = true;
5425 WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf);
5426 delayed_free.index ^= 1;
5428 call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
5431 /* The caller must hold the graph lock. May be called from RCU context. */
5432 static void __free_zapped_classes(struct pending_free *pf)
5434 struct lock_class *class;
5436 check_data_structures();
5438 list_for_each_entry(class, &pf->zapped, lock_entry)
5439 reinit_class(class);
5441 list_splice_init(&pf->zapped, &free_lock_classes);
5443 #ifdef CONFIG_PROVE_LOCKING
5444 bitmap_andnot(lock_chains_in_use, lock_chains_in_use,
5445 pf->lock_chains_being_freed, ARRAY_SIZE(lock_chains));
5446 bitmap_clear(pf->lock_chains_being_freed, 0, ARRAY_SIZE(lock_chains));
5450 static void free_zapped_rcu(struct rcu_head *ch)
5452 struct pending_free *pf;
5453 unsigned long flags;
5455 if (WARN_ON_ONCE(ch != &delayed_free.rcu_head))
5458 raw_local_irq_save(flags);
5462 pf = delayed_free.pf + (delayed_free.index ^ 1);
5463 __free_zapped_classes(pf);
5464 delayed_free.scheduled = false;
5467 * If there's anything on the open list, close and start a new callback.
5469 call_rcu_zapped(delayed_free.pf + delayed_free.index);
5472 raw_local_irq_restore(flags);
5476 * Remove all lock classes from the class hash table and from the
5477 * all_lock_classes list whose key or name is in the address range [start,
5478 * start + size). Move these lock classes to the zapped_classes list. Must
5479 * be called with the graph lock held.
5481 static void __lockdep_free_key_range(struct pending_free *pf, void *start,
5484 struct lock_class *class;
5485 struct hlist_head *head;
5488 /* Unhash all classes that were created by a module. */
5489 for (i = 0; i < CLASSHASH_SIZE; i++) {
5490 head = classhash_table + i;
5491 hlist_for_each_entry_rcu(class, head, hash_entry) {
5492 if (!within(class->key, start, size) &&
5493 !within(class->name, start, size))
5495 zap_class(pf, class);
5501 * Used in module.c to remove lock classes from memory that is going to be
5502 * freed; and possibly re-used by other modules.
5504 * We will have had one synchronize_rcu() before getting here, so we're
5505 * guaranteed nobody will look up these exact classes -- they're properly dead
5506 * but still allocated.
5508 static void lockdep_free_key_range_reg(void *start, unsigned long size)
5510 struct pending_free *pf;
5511 unsigned long flags;
5513 init_data_structures_once();
5515 raw_local_irq_save(flags);
5517 pf = get_pending_free();
5518 __lockdep_free_key_range(pf, start, size);
5519 call_rcu_zapped(pf);
5521 raw_local_irq_restore(flags);
5524 * Wait for any possible iterators from look_up_lock_class() to pass
5525 * before continuing to free the memory they refer to.
5531 * Free all lockdep keys in the range [start, start+size). Does not sleep.
5532 * Ignores debug_locks. Must only be used by the lockdep selftests.
5534 static void lockdep_free_key_range_imm(void *start, unsigned long size)
5536 struct pending_free *pf = delayed_free.pf;
5537 unsigned long flags;
5539 init_data_structures_once();
5541 raw_local_irq_save(flags);
5543 __lockdep_free_key_range(pf, start, size);
5544 __free_zapped_classes(pf);
5546 raw_local_irq_restore(flags);
5549 void lockdep_free_key_range(void *start, unsigned long size)
5551 init_data_structures_once();
5553 if (inside_selftest())
5554 lockdep_free_key_range_imm(start, size);
5556 lockdep_free_key_range_reg(start, size);
5560 * Check whether any element of the @lock->class_cache[] array refers to a
5561 * registered lock class. The caller must hold either the graph lock or the
5564 static bool lock_class_cache_is_registered(struct lockdep_map *lock)
5566 struct lock_class *class;
5567 struct hlist_head *head;
5570 for (i = 0; i < CLASSHASH_SIZE; i++) {
5571 head = classhash_table + i;
5572 hlist_for_each_entry_rcu(class, head, hash_entry) {
5573 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
5574 if (lock->class_cache[j] == class)
5581 /* The caller must hold the graph lock. Does not sleep. */
5582 static void __lockdep_reset_lock(struct pending_free *pf,
5583 struct lockdep_map *lock)
5585 struct lock_class *class;
5589 * Remove all classes this lock might have:
5591 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
5593 * If the class exists we look it up and zap it:
5595 class = look_up_lock_class(lock, j);
5597 zap_class(pf, class);
5600 * Debug check: in the end all mapped classes should
5603 if (WARN_ON_ONCE(lock_class_cache_is_registered(lock)))
5608 * Remove all information lockdep has about a lock if debug_locks == 1. Free
5609 * released data structures from RCU context.
5611 static void lockdep_reset_lock_reg(struct lockdep_map *lock)
5613 struct pending_free *pf;
5614 unsigned long flags;
5617 raw_local_irq_save(flags);
5618 locked = graph_lock();
5622 pf = get_pending_free();
5623 __lockdep_reset_lock(pf, lock);
5624 call_rcu_zapped(pf);
5628 raw_local_irq_restore(flags);
5632 * Reset a lock. Does not sleep. Ignores debug_locks. Must only be used by the
5633 * lockdep selftests.
5635 static void lockdep_reset_lock_imm(struct lockdep_map *lock)
5637 struct pending_free *pf = delayed_free.pf;
5638 unsigned long flags;
5640 raw_local_irq_save(flags);
5642 __lockdep_reset_lock(pf, lock);
5643 __free_zapped_classes(pf);
5645 raw_local_irq_restore(flags);
5648 void lockdep_reset_lock(struct lockdep_map *lock)
5650 init_data_structures_once();
5652 if (inside_selftest())
5653 lockdep_reset_lock_imm(lock);
5655 lockdep_reset_lock_reg(lock);
5658 /* Unregister a dynamically allocated key. */
5659 void lockdep_unregister_key(struct lock_class_key *key)
5661 struct hlist_head *hash_head = keyhashentry(key);
5662 struct lock_class_key *k;
5663 struct pending_free *pf;
5664 unsigned long flags;
5669 if (WARN_ON_ONCE(static_obj(key)))
5672 raw_local_irq_save(flags);
5676 pf = get_pending_free();
5677 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
5679 hlist_del_rcu(&k->hash_entry);
5684 WARN_ON_ONCE(!found);
5685 __lockdep_free_key_range(pf, key, 1);
5686 call_rcu_zapped(pf);
5689 raw_local_irq_restore(flags);
5691 /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */
5694 EXPORT_SYMBOL_GPL(lockdep_unregister_key);
5696 void __init lockdep_init(void)
5698 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
5700 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
5701 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
5702 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
5703 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
5704 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
5705 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
5706 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
5708 printk(" memory used by lock dependency info: %zu kB\n",
5709 (sizeof(lock_classes) +
5710 sizeof(lock_classes_in_use) +
5711 sizeof(classhash_table) +
5712 sizeof(list_entries) +
5713 sizeof(list_entries_in_use) +
5714 sizeof(chainhash_table) +
5715 sizeof(delayed_free)
5716 #ifdef CONFIG_PROVE_LOCKING
5718 + sizeof(lock_chains)
5719 + sizeof(lock_chains_in_use)
5720 + sizeof(chain_hlocks)
5725 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
5726 printk(" memory used for stack traces: %zu kB\n",
5727 (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024
5731 printk(" per task-struct memory footprint: %zu bytes\n",
5732 sizeof(((struct task_struct *)NULL)->held_locks));
5736 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
5737 const void *mem_to, struct held_lock *hlock)
5739 if (!debug_locks_off())
5741 if (debug_locks_silent)
5745 pr_warn("=========================\n");
5746 pr_warn("WARNING: held lock freed!\n");
5747 print_kernel_ident();
5748 pr_warn("-------------------------\n");
5749 pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
5750 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
5752 lockdep_print_held_locks(curr);
5754 pr_warn("\nstack backtrace:\n");
5758 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
5759 const void* lock_from, unsigned long lock_len)
5761 return lock_from + lock_len <= mem_from ||
5762 mem_from + mem_len <= lock_from;
5766 * Called when kernel memory is freed (or unmapped), or if a lock
5767 * is destroyed or reinitialized - this code checks whether there is
5768 * any held lock in the memory range of <from> to <to>:
5770 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
5772 struct task_struct *curr = current;
5773 struct held_lock *hlock;
5774 unsigned long flags;
5777 if (unlikely(!debug_locks))
5780 raw_local_irq_save(flags);
5781 for (i = 0; i < curr->lockdep_depth; i++) {
5782 hlock = curr->held_locks + i;
5784 if (not_in_range(mem_from, mem_len, hlock->instance,
5785 sizeof(*hlock->instance)))
5788 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
5791 raw_local_irq_restore(flags);
5793 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
5795 static void print_held_locks_bug(void)
5797 if (!debug_locks_off())
5799 if (debug_locks_silent)
5803 pr_warn("====================================\n");
5804 pr_warn("WARNING: %s/%d still has locks held!\n",
5805 current->comm, task_pid_nr(current));
5806 print_kernel_ident();
5807 pr_warn("------------------------------------\n");
5808 lockdep_print_held_locks(current);
5809 pr_warn("\nstack backtrace:\n");
5813 void debug_check_no_locks_held(void)
5815 if (unlikely(current->lockdep_depth > 0))
5816 print_held_locks_bug();
5818 EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
5821 void debug_show_all_locks(void)
5823 struct task_struct *g, *p;
5825 if (unlikely(!debug_locks)) {
5826 pr_warn("INFO: lockdep is turned off.\n");
5829 pr_warn("\nShowing all locks held in the system:\n");
5832 for_each_process_thread(g, p) {
5833 if (!p->lockdep_depth)
5835 lockdep_print_held_locks(p);
5836 touch_nmi_watchdog();
5837 touch_all_softlockup_watchdogs();
5842 pr_warn("=============================================\n\n");
5844 EXPORT_SYMBOL_GPL(debug_show_all_locks);
5848 * Careful: only use this function if you are sure that
5849 * the task cannot run in parallel!
5851 void debug_show_held_locks(struct task_struct *task)
5853 if (unlikely(!debug_locks)) {
5854 printk("INFO: lockdep is turned off.\n");
5857 lockdep_print_held_locks(task);
5859 EXPORT_SYMBOL_GPL(debug_show_held_locks);
5861 asmlinkage __visible void lockdep_sys_exit(void)
5863 struct task_struct *curr = current;
5865 if (unlikely(curr->lockdep_depth)) {
5866 if (!debug_locks_off())
5869 pr_warn("================================================\n");
5870 pr_warn("WARNING: lock held when returning to user space!\n");
5871 print_kernel_ident();
5872 pr_warn("------------------------------------------------\n");
5873 pr_warn("%s/%d is leaving the kernel with locks still held!\n",
5874 curr->comm, curr->pid);
5875 lockdep_print_held_locks(curr);
5879 * The lock history for each syscall should be independent. So wipe the
5880 * slate clean on return to userspace.
5882 lockdep_invariant_state(false);
5885 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
5887 struct task_struct *curr = current;
5889 /* Note: the following can be executed concurrently, so be careful. */
5891 pr_warn("=============================\n");
5892 pr_warn("WARNING: suspicious RCU usage\n");
5893 print_kernel_ident();
5894 pr_warn("-----------------------------\n");
5895 pr_warn("%s:%d %s!\n", file, line, s);
5896 pr_warn("\nother info that might help us debug this:\n\n");
5897 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
5898 !rcu_lockdep_current_cpu_online()
5899 ? "RCU used illegally from offline CPU!\n"
5901 rcu_scheduler_active, debug_locks);
5904 * If a CPU is in the RCU-free window in idle (ie: in the section
5905 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
5906 * considers that CPU to be in an "extended quiescent state",
5907 * which means that RCU will be completely ignoring that CPU.
5908 * Therefore, rcu_read_lock() and friends have absolutely no
5909 * effect on a CPU running in that state. In other words, even if
5910 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
5911 * delete data structures out from under it. RCU really has no
5912 * choice here: we need to keep an RCU-free window in idle where
5913 * the CPU may possibly enter into low power mode. This way we can
5914 * notice an extended quiescent state to other CPUs that started a grace
5915 * period. Otherwise we would delay any grace period as long as we run
5918 * So complain bitterly if someone does call rcu_read_lock(),
5919 * rcu_read_lock_bh() and so on from extended quiescent states.
5921 if (!rcu_is_watching())
5922 pr_warn("RCU used illegally from extended quiescent state!\n");
5924 lockdep_print_held_locks(curr);
5925 pr_warn("\nstack backtrace:\n");
5928 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);