4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <asm/sections.h>
48 #include "lockdep_internals.h"
50 #define CREATE_TRACE_POINTS
51 #include <trace/events/lockdep.h>
53 #ifdef CONFIG_PROVE_LOCKING
54 int prove_locking = 1;
55 module_param(prove_locking, int, 0644);
57 #define prove_locking 0
60 #ifdef CONFIG_LOCK_STAT
62 module_param(lock_stat, int, 0644);
68 * lockdep_lock: protects the lockdep graph, the hashes and the
69 * class/list/hash allocators.
71 * This is one of the rare exceptions where it's justified
72 * to use a raw spinlock - we really dont want the spinlock
73 * code to recurse back into the lockdep code...
75 static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
77 static int graph_lock(void)
79 __raw_spin_lock(&lockdep_lock);
81 * Make sure that if another CPU detected a bug while
82 * walking the graph we dont change it (while the other
83 * CPU is busy printing out stuff with the graph lock
87 __raw_spin_unlock(&lockdep_lock);
90 /* prevent any recursions within lockdep from causing deadlocks */
91 current->lockdep_recursion++;
95 static inline int graph_unlock(void)
97 if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
98 return DEBUG_LOCKS_WARN_ON(1);
100 current->lockdep_recursion--;
101 __raw_spin_unlock(&lockdep_lock);
106 * Turn lock debugging off and return with 0 if it was off already,
107 * and also release the graph lock:
109 static inline int debug_locks_off_graph_unlock(void)
111 int ret = debug_locks_off();
113 __raw_spin_unlock(&lockdep_lock);
118 static int lockdep_initialized;
120 unsigned long nr_list_entries;
121 struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
124 * All data structures here are protected by the global debug_lock.
126 * Mutex key structs only get allocated, once during bootup, and never
127 * get freed - this significantly simplifies the debugging code.
129 unsigned long nr_lock_classes;
130 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
132 static inline struct lock_class *hlock_class(struct held_lock *hlock)
134 if (!hlock->class_idx) {
135 DEBUG_LOCKS_WARN_ON(1);
138 return lock_classes + hlock->class_idx - 1;
141 #ifdef CONFIG_LOCK_STAT
142 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
144 static int lock_point(unsigned long points[], unsigned long ip)
148 for (i = 0; i < LOCKSTAT_POINTS; i++) {
149 if (points[i] == 0) {
160 static void lock_time_inc(struct lock_time *lt, s64 time)
165 if (time < lt->min || !lt->min)
172 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
174 dst->min += src->min;
175 dst->max += src->max;
176 dst->total += src->total;
180 struct lock_class_stats lock_stats(struct lock_class *class)
182 struct lock_class_stats stats;
185 memset(&stats, 0, sizeof(struct lock_class_stats));
186 for_each_possible_cpu(cpu) {
187 struct lock_class_stats *pcs =
188 &per_cpu(lock_stats, cpu)[class - lock_classes];
190 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
191 stats.contention_point[i] += pcs->contention_point[i];
193 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
194 stats.contending_point[i] += pcs->contending_point[i];
196 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
197 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
199 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
200 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
202 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
203 stats.bounces[i] += pcs->bounces[i];
209 void clear_lock_stats(struct lock_class *class)
213 for_each_possible_cpu(cpu) {
214 struct lock_class_stats *cpu_stats =
215 &per_cpu(lock_stats, cpu)[class - lock_classes];
217 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
219 memset(class->contention_point, 0, sizeof(class->contention_point));
220 memset(class->contending_point, 0, sizeof(class->contending_point));
223 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
225 return &get_cpu_var(lock_stats)[class - lock_classes];
228 static void put_lock_stats(struct lock_class_stats *stats)
230 put_cpu_var(lock_stats);
233 static void lock_release_holdtime(struct held_lock *hlock)
235 struct lock_class_stats *stats;
241 holdtime = sched_clock() - hlock->holdtime_stamp;
243 stats = get_lock_stats(hlock_class(hlock));
245 lock_time_inc(&stats->read_holdtime, holdtime);
247 lock_time_inc(&stats->write_holdtime, holdtime);
248 put_lock_stats(stats);
251 static inline void lock_release_holdtime(struct held_lock *hlock)
257 * We keep a global list of all lock classes. The list only grows,
258 * never shrinks. The list is only accessed with the lockdep
259 * spinlock lock held.
261 LIST_HEAD(all_lock_classes);
264 * The lockdep classes are in a hash-table as well, for fast lookup:
266 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
267 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
268 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
269 #define classhashentry(key) (classhash_table + __classhashfn((key)))
271 static struct list_head classhash_table[CLASSHASH_SIZE];
274 * We put the lock dependency chains into a hash-table as well, to cache
277 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
278 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
279 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
280 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
282 static struct list_head chainhash_table[CHAINHASH_SIZE];
285 * The hash key of the lock dependency chains is a hash itself too:
286 * it's a hash of all locks taken up to that lock, including that lock.
287 * It's a 64-bit hash, because it's important for the keys to be
290 #define iterate_chain_key(key1, key2) \
291 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
292 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
295 void lockdep_off(void)
297 current->lockdep_recursion++;
299 EXPORT_SYMBOL(lockdep_off);
301 void lockdep_on(void)
303 current->lockdep_recursion--;
305 EXPORT_SYMBOL(lockdep_on);
308 * Debugging switches:
312 #define VERY_VERBOSE 0
315 # define HARDIRQ_VERBOSE 1
316 # define SOFTIRQ_VERBOSE 1
317 # define RECLAIM_VERBOSE 1
319 # define HARDIRQ_VERBOSE 0
320 # define SOFTIRQ_VERBOSE 0
321 # define RECLAIM_VERBOSE 0
324 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
326 * Quick filtering for interesting events:
328 static int class_filter(struct lock_class *class)
332 if (class->name_version == 1 &&
333 !strcmp(class->name, "lockname"))
335 if (class->name_version == 1 &&
336 !strcmp(class->name, "&struct->lockfield"))
339 /* Filter everything else. 1 would be to allow everything else */
344 static int verbose(struct lock_class *class)
347 return class_filter(class);
353 * Stack-trace: tightly packed array of stack backtrace
354 * addresses. Protected by the graph_lock.
356 unsigned long nr_stack_trace_entries;
357 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
359 static int save_trace(struct stack_trace *trace)
361 trace->nr_entries = 0;
362 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
363 trace->entries = stack_trace + nr_stack_trace_entries;
367 save_stack_trace(trace);
369 trace->max_entries = trace->nr_entries;
371 nr_stack_trace_entries += trace->nr_entries;
373 if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
374 if (!debug_locks_off_graph_unlock())
377 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
378 printk("turning off the locking correctness validator.\n");
387 unsigned int nr_hardirq_chains;
388 unsigned int nr_softirq_chains;
389 unsigned int nr_process_chains;
390 unsigned int max_lockdep_depth;
391 unsigned int max_recursion_depth;
393 static unsigned int lockdep_dependency_gen_id;
395 static bool lockdep_dependency_visit(struct lock_class *source,
399 lockdep_dependency_gen_id++;
400 if (source->dep_gen_id == lockdep_dependency_gen_id)
402 source->dep_gen_id = lockdep_dependency_gen_id;
406 #ifdef CONFIG_DEBUG_LOCKDEP
408 * We cannot printk in early bootup code. Not even early_printk()
409 * might work. So we mark any initialization errors and printk
410 * about it later on, in lockdep_info().
412 static int lockdep_init_error;
413 static unsigned long lockdep_init_trace_data[20];
414 static struct stack_trace lockdep_init_trace = {
415 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
416 .entries = lockdep_init_trace_data,
420 * Various lockdep statistics:
422 atomic_t chain_lookup_hits;
423 atomic_t chain_lookup_misses;
424 atomic_t hardirqs_on_events;
425 atomic_t hardirqs_off_events;
426 atomic_t redundant_hardirqs_on;
427 atomic_t redundant_hardirqs_off;
428 atomic_t softirqs_on_events;
429 atomic_t softirqs_off_events;
430 atomic_t redundant_softirqs_on;
431 atomic_t redundant_softirqs_off;
432 atomic_t nr_unused_locks;
433 atomic_t nr_cyclic_checks;
434 atomic_t nr_cyclic_check_recursions;
435 atomic_t nr_find_usage_forwards_checks;
436 atomic_t nr_find_usage_forwards_recursions;
437 atomic_t nr_find_usage_backwards_checks;
438 atomic_t nr_find_usage_backwards_recursions;
445 #define __USAGE(__STATE) \
446 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
447 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
448 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
449 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
451 static const char *usage_str[] =
453 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
454 #include "lockdep_states.h"
456 [LOCK_USED] = "INITIAL USE",
459 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
461 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
464 static inline unsigned long lock_flag(enum lock_usage_bit bit)
469 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
473 if (class->usage_mask & lock_flag(bit + 2))
475 if (class->usage_mask & lock_flag(bit)) {
477 if (class->usage_mask & lock_flag(bit + 2))
484 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
488 #define LOCKDEP_STATE(__STATE) \
489 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
490 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
491 #include "lockdep_states.h"
497 static void print_lock_name(struct lock_class *class)
499 char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
502 get_usage_chars(class, usage);
506 name = __get_key_name(class->key, str);
507 printk(" (%s", name);
509 printk(" (%s", name);
510 if (class->name_version > 1)
511 printk("#%d", class->name_version);
513 printk("/%d", class->subclass);
515 printk("){%s}", usage);
518 static void print_lockdep_cache(struct lockdep_map *lock)
521 char str[KSYM_NAME_LEN];
525 name = __get_key_name(lock->key->subkeys, str);
530 static void print_lock(struct held_lock *hlock)
532 print_lock_name(hlock_class(hlock));
534 print_ip_sym(hlock->acquire_ip);
537 static void lockdep_print_held_locks(struct task_struct *curr)
539 int i, depth = curr->lockdep_depth;
542 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
545 printk("%d lock%s held by %s/%d:\n",
546 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
548 for (i = 0; i < depth; i++) {
550 print_lock(curr->held_locks + i);
554 static void print_lock_class_header(struct lock_class *class, int depth)
558 printk("%*s->", depth, "");
559 print_lock_name(class);
560 printk(" ops: %lu", class->ops);
563 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
564 if (class->usage_mask & (1 << bit)) {
567 len += printk("%*s %s", depth, "", usage_str[bit]);
568 len += printk(" at:\n");
569 print_stack_trace(class->usage_traces + bit, len);
572 printk("%*s }\n", depth, "");
574 printk("%*s ... key at: ",depth,"");
575 print_ip_sym((unsigned long)class->key);
579 * printk all lock dependencies starting at <entry>:
582 print_lock_dependencies(struct lock_class *class, int depth)
584 struct lock_list *entry;
586 if (lockdep_dependency_visit(class, depth))
589 if (DEBUG_LOCKS_WARN_ON(depth >= 20))
592 print_lock_class_header(class, depth);
594 list_for_each_entry(entry, &class->locks_after, entry) {
595 if (DEBUG_LOCKS_WARN_ON(!entry->class))
598 print_lock_dependencies(entry->class, depth + 1);
600 printk("%*s ... acquired at:\n",depth,"");
601 print_stack_trace(&entry->trace, 2);
606 static void print_kernel_version(void)
608 printk("%s %.*s\n", init_utsname()->release,
609 (int)strcspn(init_utsname()->version, " "),
610 init_utsname()->version);
613 static int very_verbose(struct lock_class *class)
616 return class_filter(class);
622 * Is this the address of a static object:
624 static int static_obj(void *obj)
626 unsigned long start = (unsigned long) &_stext,
627 end = (unsigned long) &_end,
628 addr = (unsigned long) obj;
636 if ((addr >= start) && (addr < end))
643 for_each_possible_cpu(i) {
644 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
645 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
648 if ((addr >= start) && (addr < end))
656 return is_module_address(addr);
660 * To make lock name printouts unique, we calculate a unique
661 * class->name_version generation counter:
663 static int count_matching_names(struct lock_class *new_class)
665 struct lock_class *class;
668 if (!new_class->name)
671 list_for_each_entry(class, &all_lock_classes, lock_entry) {
672 if (new_class->key - new_class->subclass == class->key)
673 return class->name_version;
674 if (class->name && !strcmp(class->name, new_class->name))
675 count = max(count, class->name_version);
682 * Register a lock's class in the hash-table, if the class is not present
683 * yet. Otherwise we look it up. We cache the result in the lock object
684 * itself, so actual lookup of the hash should be once per lock object.
686 static inline struct lock_class *
687 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
689 struct lockdep_subclass_key *key;
690 struct list_head *hash_head;
691 struct lock_class *class;
693 #ifdef CONFIG_DEBUG_LOCKDEP
695 * If the architecture calls into lockdep before initializing
696 * the hashes then we'll warn about it later. (we cannot printk
699 if (unlikely(!lockdep_initialized)) {
701 lockdep_init_error = 1;
702 save_stack_trace(&lockdep_init_trace);
707 * Static locks do not have their class-keys yet - for them the key
708 * is the lock object itself:
710 if (unlikely(!lock->key))
711 lock->key = (void *)lock;
714 * NOTE: the class-key must be unique. For dynamic locks, a static
715 * lock_class_key variable is passed in through the mutex_init()
716 * (or spin_lock_init()) call - which acts as the key. For static
717 * locks we use the lock object itself as the key.
719 BUILD_BUG_ON(sizeof(struct lock_class_key) >
720 sizeof(struct lockdep_map));
722 key = lock->key->subkeys + subclass;
724 hash_head = classhashentry(key);
727 * We can walk the hash lockfree, because the hash only
728 * grows, and we are careful when adding entries to the end:
730 list_for_each_entry(class, hash_head, hash_entry) {
731 if (class->key == key) {
732 WARN_ON_ONCE(class->name != lock->name);
741 * Register a lock's class in the hash-table, if the class is not present
742 * yet. Otherwise we look it up. We cache the result in the lock object
743 * itself, so actual lookup of the hash should be once per lock object.
745 static inline struct lock_class *
746 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
748 struct lockdep_subclass_key *key;
749 struct list_head *hash_head;
750 struct lock_class *class;
753 class = look_up_lock_class(lock, subclass);
758 * Debug-check: all keys must be persistent!
760 if (!static_obj(lock->key)) {
762 printk("INFO: trying to register non-static key.\n");
763 printk("the code is fine but needs lockdep annotation.\n");
764 printk("turning off the locking correctness validator.\n");
770 key = lock->key->subkeys + subclass;
771 hash_head = classhashentry(key);
773 raw_local_irq_save(flags);
775 raw_local_irq_restore(flags);
779 * We have to do the hash-walk again, to avoid races
782 list_for_each_entry(class, hash_head, hash_entry)
783 if (class->key == key)
786 * Allocate a new key from the static array, and add it to
789 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
790 if (!debug_locks_off_graph_unlock()) {
791 raw_local_irq_restore(flags);
794 raw_local_irq_restore(flags);
796 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
797 printk("turning off the locking correctness validator.\n");
801 class = lock_classes + nr_lock_classes++;
802 debug_atomic_inc(&nr_unused_locks);
804 class->name = lock->name;
805 class->subclass = subclass;
806 INIT_LIST_HEAD(&class->lock_entry);
807 INIT_LIST_HEAD(&class->locks_before);
808 INIT_LIST_HEAD(&class->locks_after);
809 class->name_version = count_matching_names(class);
811 * We use RCU's safe list-add method to make
812 * parallel walking of the hash-list safe:
814 list_add_tail_rcu(&class->hash_entry, hash_head);
816 * Add it to the global list of classes:
818 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
820 if (verbose(class)) {
822 raw_local_irq_restore(flags);
824 printk("\nnew class %p: %s", class->key, class->name);
825 if (class->name_version > 1)
826 printk("#%d", class->name_version);
830 raw_local_irq_save(flags);
832 raw_local_irq_restore(flags);
838 raw_local_irq_restore(flags);
840 if (!subclass || force)
841 lock->class_cache = class;
843 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
849 #ifdef CONFIG_PROVE_LOCKING
851 * Allocate a lockdep entry. (assumes the graph_lock held, returns
852 * with NULL on failure)
854 static struct lock_list *alloc_list_entry(void)
856 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
857 if (!debug_locks_off_graph_unlock())
860 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
861 printk("turning off the locking correctness validator.\n");
865 return list_entries + nr_list_entries++;
869 * Add a new dependency to the head of the list:
871 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
872 struct list_head *head, unsigned long ip, int distance)
874 struct lock_list *entry;
876 * Lock not present yet - get a new dependency struct and
877 * add it to the list:
879 entry = alloc_list_entry();
883 if (!save_trace(&entry->trace))
887 entry->distance = distance;
889 * Since we never remove from the dependency list, the list can
890 * be walked lockless by other CPUs, it's only allocation
891 * that must be protected by the spinlock. But this also means
892 * we must make new entries visible only once writes to the
893 * entry become visible - hence the RCU op:
895 list_add_tail_rcu(&entry->entry, head);
900 unsigned long bfs_accessed[BITS_TO_LONGS(MAX_LOCKDEP_ENTRIES)];
901 static struct circular_queue lock_cq;
903 static int __bfs(struct lock_list *source_entry,
905 int (*match)(struct lock_list *entry, void *data),
906 struct lock_list **target_entry,
909 struct lock_list *entry;
910 struct list_head *head;
911 struct circular_queue *cq = &lock_cq;
914 if (match(source_entry, data)) {
915 *target_entry = source_entry;
921 head = &source_entry->class->locks_after;
923 head = &source_entry->class->locks_before;
925 if (list_empty(head))
929 __cq_enqueue(cq, (unsigned long)source_entry);
931 while (!__cq_empty(cq)) {
932 struct lock_list *lock;
934 __cq_dequeue(cq, (unsigned long *)&lock);
942 head = &lock->class->locks_after;
944 head = &lock->class->locks_before;
946 list_for_each_entry(entry, head, entry) {
947 if (!lock_accessed(entry)) {
948 mark_lock_accessed(entry, lock);
949 if (match(entry, data)) {
950 *target_entry = entry;
955 if (__cq_enqueue(cq, (unsigned long)entry)) {
966 static inline int __bfs_forwards(struct lock_list *src_entry,
968 int (*match)(struct lock_list *entry, void *data),
969 struct lock_list **target_entry)
971 return __bfs(src_entry, data, match, target_entry, 1);
975 static inline int __bfs_backwards(struct lock_list *src_entry,
977 int (*match)(struct lock_list *entry, void *data),
978 struct lock_list **target_entry)
980 return __bfs(src_entry, data, match, target_entry, 0);
985 * Recursive, forwards-direction lock-dependency checking, used for
986 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
991 * Print a dependency chain entry (this is only done when a deadlock
992 * has been detected):
995 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
997 if (debug_locks_silent)
999 printk("\n-> #%u", depth);
1000 print_lock_name(target->class);
1002 print_stack_trace(&target->trace, 6);
1008 * When a circular dependency is detected, print the
1012 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1013 struct held_lock *check_src,
1014 struct held_lock *check_tgt)
1016 struct task_struct *curr = current;
1018 if (debug_locks_silent)
1021 printk("\n=======================================================\n");
1022 printk( "[ INFO: possible circular locking dependency detected ]\n");
1023 print_kernel_version();
1024 printk( "-------------------------------------------------------\n");
1025 printk("%s/%d is trying to acquire lock:\n",
1026 curr->comm, task_pid_nr(curr));
1027 print_lock(check_src);
1028 printk("\nbut task is already holding lock:\n");
1029 print_lock(check_tgt);
1030 printk("\nwhich lock already depends on the new lock.\n\n");
1031 printk("\nthe existing dependency chain (in reverse order) is:\n");
1033 print_circular_bug_entry(entry, depth);
1038 static inline int class_equal(struct lock_list *entry, void *data)
1040 return entry->class == data;
1043 static noinline int print_circular_bug(struct lock_list *this,
1044 struct lock_list *target,
1045 struct held_lock *check_src,
1046 struct held_lock *check_tgt)
1048 struct task_struct *curr = current;
1049 struct lock_list *parent;
1050 unsigned long depth;
1052 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1055 if (!save_trace(&this->trace))
1058 depth = get_lock_depth(target);
1060 print_circular_bug_header(target, depth, check_src, check_tgt);
1062 parent = get_lock_parent(target);
1065 print_circular_bug_entry(parent, --depth);
1066 parent = get_lock_parent(parent);
1069 printk("\nother info that might help us debug this:\n\n");
1070 lockdep_print_held_locks(curr);
1072 printk("\nstack backtrace:\n");
1078 static noinline int print_bfs_bug(int ret)
1080 if (!debug_locks_off_graph_unlock())
1083 WARN(1, "lockdep bfs error:%d\n", ret);
1088 unsigned long __lockdep_count_forward_deps(struct lock_class *class,
1091 struct lock_list *entry;
1092 unsigned long ret = 1;
1094 if (lockdep_dependency_visit(class, depth))
1098 * Recurse this class's dependency list:
1100 list_for_each_entry(entry, &class->locks_after, entry)
1101 ret += __lockdep_count_forward_deps(entry->class, depth + 1);
1106 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1108 unsigned long ret, flags;
1110 local_irq_save(flags);
1111 __raw_spin_lock(&lockdep_lock);
1112 ret = __lockdep_count_forward_deps(class, 0);
1113 __raw_spin_unlock(&lockdep_lock);
1114 local_irq_restore(flags);
1119 unsigned long __lockdep_count_backward_deps(struct lock_class *class,
1122 struct lock_list *entry;
1123 unsigned long ret = 1;
1125 if (lockdep_dependency_visit(class, depth))
1128 * Recurse this class's dependency list:
1130 list_for_each_entry(entry, &class->locks_before, entry)
1131 ret += __lockdep_count_backward_deps(entry->class, depth + 1);
1136 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1138 unsigned long ret, flags;
1140 local_irq_save(flags);
1141 __raw_spin_lock(&lockdep_lock);
1142 ret = __lockdep_count_backward_deps(class, 0);
1143 __raw_spin_unlock(&lockdep_lock);
1144 local_irq_restore(flags);
1150 * Prove that the dependency graph starting at <entry> can not
1151 * lead to <target>. Print an error and return 0 if it does.
1154 check_noncircular(struct lock_list *root, struct lock_class *target,
1155 struct lock_list **target_entry)
1159 debug_atomic_inc(&nr_cyclic_checks);
1161 result = __bfs_forwards(root, target, class_equal, target_entry);
1166 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1168 * Forwards and backwards subgraph searching, for the purposes of
1169 * proving that two subgraphs can be connected by a new dependency
1170 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1172 static struct lock_class *forwards_match, *backwards_match;
1175 #define BFS_PROCESS_RET(ret) do { \
1177 return print_bfs_bug(ret); \
1182 static inline int usage_match(struct lock_list *entry, void *bit)
1184 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1190 * Find a node in the forwards-direction dependency sub-graph starting
1191 * at @root->class that matches @bit.
1193 * Return 0 if such a node exists in the subgraph, and put that node
1194 * into *@target_entry.
1196 * Return 1 otherwise and keep *@target_entry unchanged.
1197 * Return <0 on error.
1200 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1201 struct lock_list **target_entry)
1205 debug_atomic_inc(&nr_find_usage_forwards_checks);
1207 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1213 * Find a node in the backwards-direction dependency sub-graph starting
1214 * at @root->class that matches @bit.
1216 * Return 0 if such a node exists in the subgraph, and put that node
1217 * into *@target_entry.
1219 * Return 1 otherwise and keep *@target_entry unchanged.
1220 * Return <0 on error.
1223 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1224 struct lock_list **target_entry)
1228 debug_atomic_inc(&nr_find_usage_backwards_checks);
1230 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1237 print_bad_irq_dependency(struct task_struct *curr,
1238 struct held_lock *prev,
1239 struct held_lock *next,
1240 enum lock_usage_bit bit1,
1241 enum lock_usage_bit bit2,
1242 const char *irqclass)
1244 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1247 printk("\n======================================================\n");
1248 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1249 irqclass, irqclass);
1250 print_kernel_version();
1251 printk( "------------------------------------------------------\n");
1252 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1253 curr->comm, task_pid_nr(curr),
1254 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1255 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1256 curr->hardirqs_enabled,
1257 curr->softirqs_enabled);
1260 printk("\nand this task is already holding:\n");
1262 printk("which would create a new lock dependency:\n");
1263 print_lock_name(hlock_class(prev));
1265 print_lock_name(hlock_class(next));
1268 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1270 print_lock_name(backwards_match);
1271 printk("\n... which became %s-irq-safe at:\n", irqclass);
1273 print_stack_trace(backwards_match->usage_traces + bit1, 1);
1275 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1276 print_lock_name(forwards_match);
1277 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1280 print_stack_trace(forwards_match->usage_traces + bit2, 1);
1282 printk("\nother info that might help us debug this:\n\n");
1283 lockdep_print_held_locks(curr);
1285 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1286 print_lock_dependencies(backwards_match, 0);
1288 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1289 print_lock_dependencies(forwards_match, 0);
1291 printk("\nstack backtrace:\n");
1298 check_usage(struct task_struct *curr, struct held_lock *prev,
1299 struct held_lock *next, enum lock_usage_bit bit_backwards,
1300 enum lock_usage_bit bit_forwards, const char *irqclass)
1303 struct lock_list this;
1304 struct lock_list *uninitialized_var(target_entry);
1308 this.class = hlock_class(prev);
1309 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1310 BFS_PROCESS_RET(ret);
1311 backwards_match = target_entry->class;
1313 this.class = hlock_class(next);
1314 ret = find_usage_forwards(&this, bit_forwards, &target_entry);
1315 BFS_PROCESS_RET(ret);
1316 forwards_match = target_entry->class;
1318 return print_bad_irq_dependency(curr, prev, next,
1319 bit_backwards, bit_forwards, irqclass);
1322 static const char *state_names[] = {
1323 #define LOCKDEP_STATE(__STATE) \
1324 __stringify(__STATE),
1325 #include "lockdep_states.h"
1326 #undef LOCKDEP_STATE
1329 static const char *state_rnames[] = {
1330 #define LOCKDEP_STATE(__STATE) \
1331 __stringify(__STATE)"-READ",
1332 #include "lockdep_states.h"
1333 #undef LOCKDEP_STATE
1336 static inline const char *state_name(enum lock_usage_bit bit)
1338 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1341 static int exclusive_bit(int new_bit)
1349 * bit 0 - write/read
1350 * bit 1 - used_in/enabled
1354 int state = new_bit & ~3;
1355 int dir = new_bit & 2;
1358 * keep state, bit flip the direction and strip read.
1360 return state | (dir ^ 2);
1363 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1364 struct held_lock *next, enum lock_usage_bit bit)
1367 * Prove that the new dependency does not connect a hardirq-safe
1368 * lock with a hardirq-unsafe lock - to achieve this we search
1369 * the backwards-subgraph starting at <prev>, and the
1370 * forwards-subgraph starting at <next>:
1372 if (!check_usage(curr, prev, next, bit,
1373 exclusive_bit(bit), state_name(bit)))
1379 * Prove that the new dependency does not connect a hardirq-safe-read
1380 * lock with a hardirq-unsafe lock - to achieve this we search
1381 * the backwards-subgraph starting at <prev>, and the
1382 * forwards-subgraph starting at <next>:
1384 if (!check_usage(curr, prev, next, bit,
1385 exclusive_bit(bit), state_name(bit)))
1392 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1393 struct held_lock *next)
1395 #define LOCKDEP_STATE(__STATE) \
1396 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1398 #include "lockdep_states.h"
1399 #undef LOCKDEP_STATE
1404 static void inc_chains(void)
1406 if (current->hardirq_context)
1407 nr_hardirq_chains++;
1409 if (current->softirq_context)
1410 nr_softirq_chains++;
1412 nr_process_chains++;
1419 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1420 struct held_lock *next)
1425 static inline void inc_chains(void)
1427 nr_process_chains++;
1433 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1434 struct held_lock *next)
1436 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1439 printk("\n=============================================\n");
1440 printk( "[ INFO: possible recursive locking detected ]\n");
1441 print_kernel_version();
1442 printk( "---------------------------------------------\n");
1443 printk("%s/%d is trying to acquire lock:\n",
1444 curr->comm, task_pid_nr(curr));
1446 printk("\nbut task is already holding lock:\n");
1449 printk("\nother info that might help us debug this:\n");
1450 lockdep_print_held_locks(curr);
1452 printk("\nstack backtrace:\n");
1459 * Check whether we are holding such a class already.
1461 * (Note that this has to be done separately, because the graph cannot
1462 * detect such classes of deadlocks.)
1464 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1467 check_deadlock(struct task_struct *curr, struct held_lock *next,
1468 struct lockdep_map *next_instance, int read)
1470 struct held_lock *prev;
1471 struct held_lock *nest = NULL;
1474 for (i = 0; i < curr->lockdep_depth; i++) {
1475 prev = curr->held_locks + i;
1477 if (prev->instance == next->nest_lock)
1480 if (hlock_class(prev) != hlock_class(next))
1484 * Allow read-after-read recursion of the same
1485 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1487 if ((read == 2) && prev->read)
1491 * We're holding the nest_lock, which serializes this lock's
1492 * nesting behaviour.
1497 return print_deadlock_bug(curr, prev, next);
1503 * There was a chain-cache miss, and we are about to add a new dependency
1504 * to a previous lock. We recursively validate the following rules:
1506 * - would the adding of the <prev> -> <next> dependency create a
1507 * circular dependency in the graph? [== circular deadlock]
1509 * - does the new prev->next dependency connect any hardirq-safe lock
1510 * (in the full backwards-subgraph starting at <prev>) with any
1511 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1512 * <next>)? [== illegal lock inversion with hardirq contexts]
1514 * - does the new prev->next dependency connect any softirq-safe lock
1515 * (in the full backwards-subgraph starting at <prev>) with any
1516 * softirq-unsafe lock (in the full forwards-subgraph starting at
1517 * <next>)? [== illegal lock inversion with softirq contexts]
1519 * any of these scenarios could lead to a deadlock.
1521 * Then if all the validations pass, we add the forwards and backwards
1525 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1526 struct held_lock *next, int distance)
1528 struct lock_list *entry;
1530 struct lock_list this;
1531 struct lock_list *uninitialized_var(target_entry);
1534 * Prove that the new <prev> -> <next> dependency would not
1535 * create a circular dependency in the graph. (We do this by
1536 * forward-recursing into the graph starting at <next>, and
1537 * checking whether we can reach <prev>.)
1539 * We are using global variables to control the recursion, to
1540 * keep the stackframe size of the recursive functions low:
1542 this.class = hlock_class(next);
1544 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1546 return print_circular_bug(&this, target_entry, next, prev);
1547 else if (unlikely(ret < 0))
1548 return print_bfs_bug(ret);
1550 if (!check_prev_add_irq(curr, prev, next))
1554 * For recursive read-locks we do all the dependency checks,
1555 * but we dont store read-triggered dependencies (only
1556 * write-triggered dependencies). This ensures that only the
1557 * write-side dependencies matter, and that if for example a
1558 * write-lock never takes any other locks, then the reads are
1559 * equivalent to a NOP.
1561 if (next->read == 2 || prev->read == 2)
1564 * Is the <prev> -> <next> dependency already present?
1566 * (this may occur even though this is a new chain: consider
1567 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1568 * chains - the second one will be new, but L1 already has
1569 * L2 added to its dependency list, due to the first chain.)
1571 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1572 if (entry->class == hlock_class(next)) {
1574 entry->distance = 1;
1580 * Ok, all validations passed, add the new lock
1581 * to the previous lock's dependency list:
1583 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1584 &hlock_class(prev)->locks_after,
1585 next->acquire_ip, distance);
1590 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1591 &hlock_class(next)->locks_before,
1592 next->acquire_ip, distance);
1597 * Debugging printouts:
1599 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1601 printk("\n new dependency: ");
1602 print_lock_name(hlock_class(prev));
1604 print_lock_name(hlock_class(next));
1607 return graph_lock();
1613 * Add the dependency to all directly-previous locks that are 'relevant'.
1614 * The ones that are relevant are (in increasing distance from curr):
1615 * all consecutive trylock entries and the final non-trylock entry - or
1616 * the end of this context's lock-chain - whichever comes first.
1619 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1621 int depth = curr->lockdep_depth;
1622 struct held_lock *hlock;
1627 * Depth must not be zero for a non-head lock:
1632 * At least two relevant locks must exist for this
1635 if (curr->held_locks[depth].irq_context !=
1636 curr->held_locks[depth-1].irq_context)
1640 int distance = curr->lockdep_depth - depth + 1;
1641 hlock = curr->held_locks + depth-1;
1643 * Only non-recursive-read entries get new dependencies
1646 if (hlock->read != 2) {
1647 if (!check_prev_add(curr, hlock, next, distance))
1650 * Stop after the first non-trylock entry,
1651 * as non-trylock entries have added their
1652 * own direct dependencies already, so this
1653 * lock is connected to them indirectly:
1655 if (!hlock->trylock)
1660 * End of lock-stack?
1665 * Stop the search if we cross into another context:
1667 if (curr->held_locks[depth].irq_context !=
1668 curr->held_locks[depth-1].irq_context)
1673 if (!debug_locks_off_graph_unlock())
1681 unsigned long nr_lock_chains;
1682 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1683 int nr_chain_hlocks;
1684 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1686 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1688 return lock_classes + chain_hlocks[chain->base + i];
1692 * Look up a dependency chain. If the key is not present yet then
1693 * add it and return 1 - in this case the new dependency chain is
1694 * validated. If the key is already hashed, return 0.
1695 * (On return with 1 graph_lock is held.)
1697 static inline int lookup_chain_cache(struct task_struct *curr,
1698 struct held_lock *hlock,
1701 struct lock_class *class = hlock_class(hlock);
1702 struct list_head *hash_head = chainhashentry(chain_key);
1703 struct lock_chain *chain;
1704 struct held_lock *hlock_curr, *hlock_next;
1707 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1710 * We can walk it lock-free, because entries only get added
1713 list_for_each_entry(chain, hash_head, entry) {
1714 if (chain->chain_key == chain_key) {
1716 debug_atomic_inc(&chain_lookup_hits);
1717 if (very_verbose(class))
1718 printk("\nhash chain already cached, key: "
1719 "%016Lx tail class: [%p] %s\n",
1720 (unsigned long long)chain_key,
1721 class->key, class->name);
1725 if (very_verbose(class))
1726 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1727 (unsigned long long)chain_key, class->key, class->name);
1729 * Allocate a new chain entry from the static array, and add
1735 * We have to walk the chain again locked - to avoid duplicates:
1737 list_for_each_entry(chain, hash_head, entry) {
1738 if (chain->chain_key == chain_key) {
1743 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1744 if (!debug_locks_off_graph_unlock())
1747 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1748 printk("turning off the locking correctness validator.\n");
1752 chain = lock_chains + nr_lock_chains++;
1753 chain->chain_key = chain_key;
1754 chain->irq_context = hlock->irq_context;
1755 /* Find the first held_lock of current chain */
1757 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1758 hlock_curr = curr->held_locks + i;
1759 if (hlock_curr->irq_context != hlock_next->irq_context)
1764 chain->depth = curr->lockdep_depth + 1 - i;
1765 cn = nr_chain_hlocks;
1766 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1767 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1772 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1774 for (j = 0; j < chain->depth - 1; j++, i++) {
1775 int lock_id = curr->held_locks[i].class_idx - 1;
1776 chain_hlocks[chain->base + j] = lock_id;
1778 chain_hlocks[chain->base + j] = class - lock_classes;
1780 list_add_tail_rcu(&chain->entry, hash_head);
1781 debug_atomic_inc(&chain_lookup_misses);
1787 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1788 struct held_lock *hlock, int chain_head, u64 chain_key)
1791 * Trylock needs to maintain the stack of held locks, but it
1792 * does not add new dependencies, because trylock can be done
1795 * We look up the chain_key and do the O(N^2) check and update of
1796 * the dependencies only if this is a new dependency chain.
1797 * (If lookup_chain_cache() returns with 1 it acquires
1798 * graph_lock for us)
1800 if (!hlock->trylock && (hlock->check == 2) &&
1801 lookup_chain_cache(curr, hlock, chain_key)) {
1803 * Check whether last held lock:
1805 * - is irq-safe, if this lock is irq-unsafe
1806 * - is softirq-safe, if this lock is hardirq-unsafe
1808 * And check whether the new lock's dependency graph
1809 * could lead back to the previous lock.
1811 * any of these scenarios could lead to a deadlock. If
1814 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1819 * Mark recursive read, as we jump over it when
1820 * building dependencies (just like we jump over
1826 * Add dependency only if this lock is not the head
1827 * of the chain, and if it's not a secondary read-lock:
1829 if (!chain_head && ret != 2)
1830 if (!check_prevs_add(curr, hlock))
1834 /* after lookup_chain_cache(): */
1835 if (unlikely(!debug_locks))
1841 static inline int validate_chain(struct task_struct *curr,
1842 struct lockdep_map *lock, struct held_lock *hlock,
1843 int chain_head, u64 chain_key)
1850 * We are building curr_chain_key incrementally, so double-check
1851 * it from scratch, to make sure that it's done correctly:
1853 static void check_chain_key(struct task_struct *curr)
1855 #ifdef CONFIG_DEBUG_LOCKDEP
1856 struct held_lock *hlock, *prev_hlock = NULL;
1860 for (i = 0; i < curr->lockdep_depth; i++) {
1861 hlock = curr->held_locks + i;
1862 if (chain_key != hlock->prev_chain_key) {
1864 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1865 curr->lockdep_depth, i,
1866 (unsigned long long)chain_key,
1867 (unsigned long long)hlock->prev_chain_key);
1870 id = hlock->class_idx - 1;
1871 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1874 if (prev_hlock && (prev_hlock->irq_context !=
1875 hlock->irq_context))
1877 chain_key = iterate_chain_key(chain_key, id);
1880 if (chain_key != curr->curr_chain_key) {
1882 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1883 curr->lockdep_depth, i,
1884 (unsigned long long)chain_key,
1885 (unsigned long long)curr->curr_chain_key);
1891 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1892 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1894 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1897 printk("\n=================================\n");
1898 printk( "[ INFO: inconsistent lock state ]\n");
1899 print_kernel_version();
1900 printk( "---------------------------------\n");
1902 printk("inconsistent {%s} -> {%s} usage.\n",
1903 usage_str[prev_bit], usage_str[new_bit]);
1905 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1906 curr->comm, task_pid_nr(curr),
1907 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1908 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1909 trace_hardirqs_enabled(curr),
1910 trace_softirqs_enabled(curr));
1913 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1914 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
1916 print_irqtrace_events(curr);
1917 printk("\nother info that might help us debug this:\n");
1918 lockdep_print_held_locks(curr);
1920 printk("\nstack backtrace:\n");
1927 * Print out an error if an invalid bit is set:
1930 valid_state(struct task_struct *curr, struct held_lock *this,
1931 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1933 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
1934 return print_usage_bug(curr, this, bad_bit, new_bit);
1938 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1939 enum lock_usage_bit new_bit);
1941 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1944 * print irq inversion bug:
1947 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1948 struct held_lock *this, int forwards,
1949 const char *irqclass)
1951 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1954 printk("\n=========================================================\n");
1955 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1956 print_kernel_version();
1957 printk( "---------------------------------------------------------\n");
1958 printk("%s/%d just changed the state of lock:\n",
1959 curr->comm, task_pid_nr(curr));
1962 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
1964 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
1965 print_lock_name(other);
1966 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1968 printk("\nother info that might help us debug this:\n");
1969 lockdep_print_held_locks(curr);
1971 printk("\nthe first lock's dependencies:\n");
1972 print_lock_dependencies(hlock_class(this), 0);
1974 printk("\nthe second lock's dependencies:\n");
1975 print_lock_dependencies(other, 0);
1977 printk("\nstack backtrace:\n");
1984 * Prove that in the forwards-direction subgraph starting at <this>
1985 * there is no lock matching <mask>:
1988 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1989 enum lock_usage_bit bit, const char *irqclass)
1992 struct lock_list root;
1993 struct lock_list *uninitialized_var(target_entry);
1996 root.class = hlock_class(this);
1997 ret = find_usage_forwards(&root, bit, &target_entry);
1998 BFS_PROCESS_RET(ret);
2000 return print_irq_inversion_bug(curr, target_entry->class,
2005 * Prove that in the backwards-direction subgraph starting at <this>
2006 * there is no lock matching <mask>:
2009 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2010 enum lock_usage_bit bit, const char *irqclass)
2013 struct lock_list root;
2014 struct lock_list *uninitialized_var(target_entry);
2017 root.class = hlock_class(this);
2018 ret = find_usage_backwards(&root, bit, &target_entry);
2019 BFS_PROCESS_RET(ret);
2021 return print_irq_inversion_bug(curr, target_entry->class,
2025 void print_irqtrace_events(struct task_struct *curr)
2027 printk("irq event stamp: %u\n", curr->irq_events);
2028 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2029 print_ip_sym(curr->hardirq_enable_ip);
2030 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2031 print_ip_sym(curr->hardirq_disable_ip);
2032 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2033 print_ip_sym(curr->softirq_enable_ip);
2034 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2035 print_ip_sym(curr->softirq_disable_ip);
2038 static int HARDIRQ_verbose(struct lock_class *class)
2041 return class_filter(class);
2046 static int SOFTIRQ_verbose(struct lock_class *class)
2049 return class_filter(class);
2054 static int RECLAIM_FS_verbose(struct lock_class *class)
2057 return class_filter(class);
2062 #define STRICT_READ_CHECKS 1
2064 static int (*state_verbose_f[])(struct lock_class *class) = {
2065 #define LOCKDEP_STATE(__STATE) \
2067 #include "lockdep_states.h"
2068 #undef LOCKDEP_STATE
2071 static inline int state_verbose(enum lock_usage_bit bit,
2072 struct lock_class *class)
2074 return state_verbose_f[bit >> 2](class);
2077 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2078 enum lock_usage_bit bit, const char *name);
2081 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2082 enum lock_usage_bit new_bit)
2084 int excl_bit = exclusive_bit(new_bit);
2085 int read = new_bit & 1;
2086 int dir = new_bit & 2;
2089 * mark USED_IN has to look forwards -- to ensure no dependency
2090 * has ENABLED state, which would allow recursion deadlocks.
2092 * mark ENABLED has to look backwards -- to ensure no dependee
2093 * has USED_IN state, which, again, would allow recursion deadlocks.
2095 check_usage_f usage = dir ?
2096 check_usage_backwards : check_usage_forwards;
2099 * Validate that this particular lock does not have conflicting
2102 if (!valid_state(curr, this, new_bit, excl_bit))
2106 * Validate that the lock dependencies don't have conflicting usage
2109 if ((!read || !dir || STRICT_READ_CHECKS) &&
2110 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2114 * Check for read in write conflicts
2117 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2120 if (STRICT_READ_CHECKS &&
2121 !usage(curr, this, excl_bit + 1,
2122 state_name(new_bit + 1)))
2126 if (state_verbose(new_bit, hlock_class(this)))
2133 #define LOCKDEP_STATE(__STATE) __STATE,
2134 #include "lockdep_states.h"
2135 #undef LOCKDEP_STATE
2139 * Mark all held locks with a usage bit:
2142 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2144 enum lock_usage_bit usage_bit;
2145 struct held_lock *hlock;
2148 for (i = 0; i < curr->lockdep_depth; i++) {
2149 hlock = curr->held_locks + i;
2151 usage_bit = 2 + (mark << 2); /* ENABLED */
2153 usage_bit += 1; /* READ */
2155 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2157 if (!mark_lock(curr, hlock, usage_bit))
2165 * Debugging helper: via this flag we know that we are in
2166 * 'early bootup code', and will warn about any invalid irqs-on event:
2168 static int early_boot_irqs_enabled;
2170 void early_boot_irqs_off(void)
2172 early_boot_irqs_enabled = 0;
2175 void early_boot_irqs_on(void)
2177 early_boot_irqs_enabled = 1;
2181 * Hardirqs will be enabled:
2183 void trace_hardirqs_on_caller(unsigned long ip)
2185 struct task_struct *curr = current;
2187 time_hardirqs_on(CALLER_ADDR0, ip);
2189 if (unlikely(!debug_locks || current->lockdep_recursion))
2192 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2195 if (unlikely(curr->hardirqs_enabled)) {
2196 debug_atomic_inc(&redundant_hardirqs_on);
2199 /* we'll do an OFF -> ON transition: */
2200 curr->hardirqs_enabled = 1;
2202 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2204 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2207 * We are going to turn hardirqs on, so set the
2208 * usage bit for all held locks:
2210 if (!mark_held_locks(curr, HARDIRQ))
2213 * If we have softirqs enabled, then set the usage
2214 * bit for all held locks. (disabled hardirqs prevented
2215 * this bit from being set before)
2217 if (curr->softirqs_enabled)
2218 if (!mark_held_locks(curr, SOFTIRQ))
2221 curr->hardirq_enable_ip = ip;
2222 curr->hardirq_enable_event = ++curr->irq_events;
2223 debug_atomic_inc(&hardirqs_on_events);
2225 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2227 void trace_hardirqs_on(void)
2229 trace_hardirqs_on_caller(CALLER_ADDR0);
2231 EXPORT_SYMBOL(trace_hardirqs_on);
2234 * Hardirqs were disabled:
2236 void trace_hardirqs_off_caller(unsigned long ip)
2238 struct task_struct *curr = current;
2240 time_hardirqs_off(CALLER_ADDR0, ip);
2242 if (unlikely(!debug_locks || current->lockdep_recursion))
2245 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2248 if (curr->hardirqs_enabled) {
2250 * We have done an ON -> OFF transition:
2252 curr->hardirqs_enabled = 0;
2253 curr->hardirq_disable_ip = ip;
2254 curr->hardirq_disable_event = ++curr->irq_events;
2255 debug_atomic_inc(&hardirqs_off_events);
2257 debug_atomic_inc(&redundant_hardirqs_off);
2259 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2261 void trace_hardirqs_off(void)
2263 trace_hardirqs_off_caller(CALLER_ADDR0);
2265 EXPORT_SYMBOL(trace_hardirqs_off);
2268 * Softirqs will be enabled:
2270 void trace_softirqs_on(unsigned long ip)
2272 struct task_struct *curr = current;
2274 if (unlikely(!debug_locks))
2277 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2280 if (curr->softirqs_enabled) {
2281 debug_atomic_inc(&redundant_softirqs_on);
2286 * We'll do an OFF -> ON transition:
2288 curr->softirqs_enabled = 1;
2289 curr->softirq_enable_ip = ip;
2290 curr->softirq_enable_event = ++curr->irq_events;
2291 debug_atomic_inc(&softirqs_on_events);
2293 * We are going to turn softirqs on, so set the
2294 * usage bit for all held locks, if hardirqs are
2297 if (curr->hardirqs_enabled)
2298 mark_held_locks(curr, SOFTIRQ);
2302 * Softirqs were disabled:
2304 void trace_softirqs_off(unsigned long ip)
2306 struct task_struct *curr = current;
2308 if (unlikely(!debug_locks))
2311 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2314 if (curr->softirqs_enabled) {
2316 * We have done an ON -> OFF transition:
2318 curr->softirqs_enabled = 0;
2319 curr->softirq_disable_ip = ip;
2320 curr->softirq_disable_event = ++curr->irq_events;
2321 debug_atomic_inc(&softirqs_off_events);
2322 DEBUG_LOCKS_WARN_ON(!softirq_count());
2324 debug_atomic_inc(&redundant_softirqs_off);
2327 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2329 struct task_struct *curr = current;
2331 if (unlikely(!debug_locks))
2334 /* no reclaim without waiting on it */
2335 if (!(gfp_mask & __GFP_WAIT))
2338 /* this guy won't enter reclaim */
2339 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2342 /* We're only interested __GFP_FS allocations for now */
2343 if (!(gfp_mask & __GFP_FS))
2346 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2349 mark_held_locks(curr, RECLAIM_FS);
2352 static void check_flags(unsigned long flags);
2354 void lockdep_trace_alloc(gfp_t gfp_mask)
2356 unsigned long flags;
2358 if (unlikely(current->lockdep_recursion))
2361 raw_local_irq_save(flags);
2363 current->lockdep_recursion = 1;
2364 __lockdep_trace_alloc(gfp_mask, flags);
2365 current->lockdep_recursion = 0;
2366 raw_local_irq_restore(flags);
2369 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2372 * If non-trylock use in a hardirq or softirq context, then
2373 * mark the lock as used in these contexts:
2375 if (!hlock->trylock) {
2377 if (curr->hardirq_context)
2378 if (!mark_lock(curr, hlock,
2379 LOCK_USED_IN_HARDIRQ_READ))
2381 if (curr->softirq_context)
2382 if (!mark_lock(curr, hlock,
2383 LOCK_USED_IN_SOFTIRQ_READ))
2386 if (curr->hardirq_context)
2387 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2389 if (curr->softirq_context)
2390 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2394 if (!hlock->hardirqs_off) {
2396 if (!mark_lock(curr, hlock,
2397 LOCK_ENABLED_HARDIRQ_READ))
2399 if (curr->softirqs_enabled)
2400 if (!mark_lock(curr, hlock,
2401 LOCK_ENABLED_SOFTIRQ_READ))
2404 if (!mark_lock(curr, hlock,
2405 LOCK_ENABLED_HARDIRQ))
2407 if (curr->softirqs_enabled)
2408 if (!mark_lock(curr, hlock,
2409 LOCK_ENABLED_SOFTIRQ))
2415 * We reuse the irq context infrastructure more broadly as a general
2416 * context checking code. This tests GFP_FS recursion (a lock taken
2417 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2420 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2422 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2425 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2433 static int separate_irq_context(struct task_struct *curr,
2434 struct held_lock *hlock)
2436 unsigned int depth = curr->lockdep_depth;
2439 * Keep track of points where we cross into an interrupt context:
2441 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2442 curr->softirq_context;
2444 struct held_lock *prev_hlock;
2446 prev_hlock = curr->held_locks + depth-1;
2448 * If we cross into another context, reset the
2449 * hash key (this also prevents the checking and the
2450 * adding of the dependency to 'prev'):
2452 if (prev_hlock->irq_context != hlock->irq_context)
2461 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2462 enum lock_usage_bit new_bit)
2468 static inline int mark_irqflags(struct task_struct *curr,
2469 struct held_lock *hlock)
2474 static inline int separate_irq_context(struct task_struct *curr,
2475 struct held_lock *hlock)
2480 void lockdep_trace_alloc(gfp_t gfp_mask)
2487 * Mark a lock with a usage bit, and validate the state transition:
2489 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2490 enum lock_usage_bit new_bit)
2492 unsigned int new_mask = 1 << new_bit, ret = 1;
2495 * If already set then do not dirty the cacheline,
2496 * nor do any checks:
2498 if (likely(hlock_class(this)->usage_mask & new_mask))
2504 * Make sure we didnt race:
2506 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2511 hlock_class(this)->usage_mask |= new_mask;
2513 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2517 #define LOCKDEP_STATE(__STATE) \
2518 case LOCK_USED_IN_##__STATE: \
2519 case LOCK_USED_IN_##__STATE##_READ: \
2520 case LOCK_ENABLED_##__STATE: \
2521 case LOCK_ENABLED_##__STATE##_READ:
2522 #include "lockdep_states.h"
2523 #undef LOCKDEP_STATE
2524 ret = mark_lock_irq(curr, this, new_bit);
2529 debug_atomic_dec(&nr_unused_locks);
2532 if (!debug_locks_off_graph_unlock())
2541 * We must printk outside of the graph_lock:
2544 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2546 print_irqtrace_events(curr);
2554 * Initialize a lock instance's lock-class mapping info:
2556 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2557 struct lock_class_key *key, int subclass)
2559 lock->class_cache = NULL;
2560 #ifdef CONFIG_LOCK_STAT
2561 lock->cpu = raw_smp_processor_id();
2564 if (DEBUG_LOCKS_WARN_ON(!name)) {
2565 lock->name = "NULL";
2571 if (DEBUG_LOCKS_WARN_ON(!key))
2574 * Sanity check, the lock-class key must be persistent:
2576 if (!static_obj(key)) {
2577 printk("BUG: key %p not in .data!\n", key);
2578 DEBUG_LOCKS_WARN_ON(1);
2583 if (unlikely(!debug_locks))
2587 register_lock_class(lock, subclass, 1);
2589 EXPORT_SYMBOL_GPL(lockdep_init_map);
2592 * This gets called for every mutex_lock*()/spin_lock*() operation.
2593 * We maintain the dependency maps and validate the locking attempt:
2595 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2596 int trylock, int read, int check, int hardirqs_off,
2597 struct lockdep_map *nest_lock, unsigned long ip)
2599 struct task_struct *curr = current;
2600 struct lock_class *class = NULL;
2601 struct held_lock *hlock;
2602 unsigned int depth, id;
2609 if (unlikely(!debug_locks))
2612 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2615 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2617 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2618 printk("turning off the locking correctness validator.\n");
2624 class = lock->class_cache;
2626 * Not cached yet or subclass?
2628 if (unlikely(!class)) {
2629 class = register_lock_class(lock, subclass, 0);
2633 debug_atomic_inc((atomic_t *)&class->ops);
2634 if (very_verbose(class)) {
2635 printk("\nacquire class [%p] %s", class->key, class->name);
2636 if (class->name_version > 1)
2637 printk("#%d", class->name_version);
2643 * Add the lock to the list of currently held locks.
2644 * (we dont increase the depth just yet, up until the
2645 * dependency checks are done)
2647 depth = curr->lockdep_depth;
2648 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2651 hlock = curr->held_locks + depth;
2652 if (DEBUG_LOCKS_WARN_ON(!class))
2654 hlock->class_idx = class - lock_classes + 1;
2655 hlock->acquire_ip = ip;
2656 hlock->instance = lock;
2657 hlock->nest_lock = nest_lock;
2658 hlock->trylock = trylock;
2660 hlock->check = check;
2661 hlock->hardirqs_off = !!hardirqs_off;
2662 #ifdef CONFIG_LOCK_STAT
2663 hlock->waittime_stamp = 0;
2664 hlock->holdtime_stamp = sched_clock();
2667 if (check == 2 && !mark_irqflags(curr, hlock))
2670 /* mark it as used: */
2671 if (!mark_lock(curr, hlock, LOCK_USED))
2675 * Calculate the chain hash: it's the combined hash of all the
2676 * lock keys along the dependency chain. We save the hash value
2677 * at every step so that we can get the current hash easily
2678 * after unlock. The chain hash is then used to cache dependency
2681 * The 'key ID' is what is the most compact key value to drive
2682 * the hash, not class->key.
2684 id = class - lock_classes;
2685 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2688 chain_key = curr->curr_chain_key;
2690 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2695 hlock->prev_chain_key = chain_key;
2696 if (separate_irq_context(curr, hlock)) {
2700 chain_key = iterate_chain_key(chain_key, id);
2702 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2705 curr->curr_chain_key = chain_key;
2706 curr->lockdep_depth++;
2707 check_chain_key(curr);
2708 #ifdef CONFIG_DEBUG_LOCKDEP
2709 if (unlikely(!debug_locks))
2712 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2714 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2715 printk("turning off the locking correctness validator.\n");
2720 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2721 max_lockdep_depth = curr->lockdep_depth;
2727 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2730 if (!debug_locks_off())
2732 if (debug_locks_silent)
2735 printk("\n=====================================\n");
2736 printk( "[ BUG: bad unlock balance detected! ]\n");
2737 printk( "-------------------------------------\n");
2738 printk("%s/%d is trying to release lock (",
2739 curr->comm, task_pid_nr(curr));
2740 print_lockdep_cache(lock);
2743 printk("but there are no more locks to release!\n");
2744 printk("\nother info that might help us debug this:\n");
2745 lockdep_print_held_locks(curr);
2747 printk("\nstack backtrace:\n");
2754 * Common debugging checks for both nested and non-nested unlock:
2756 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2759 if (unlikely(!debug_locks))
2761 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2764 if (curr->lockdep_depth <= 0)
2765 return print_unlock_inbalance_bug(curr, lock, ip);
2771 __lock_set_class(struct lockdep_map *lock, const char *name,
2772 struct lock_class_key *key, unsigned int subclass,
2775 struct task_struct *curr = current;
2776 struct held_lock *hlock, *prev_hlock;
2777 struct lock_class *class;
2781 depth = curr->lockdep_depth;
2782 if (DEBUG_LOCKS_WARN_ON(!depth))
2786 for (i = depth-1; i >= 0; i--) {
2787 hlock = curr->held_locks + i;
2789 * We must not cross into another context:
2791 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2793 if (hlock->instance == lock)
2797 return print_unlock_inbalance_bug(curr, lock, ip);
2800 lockdep_init_map(lock, name, key, 0);
2801 class = register_lock_class(lock, subclass, 0);
2802 hlock->class_idx = class - lock_classes + 1;
2804 curr->lockdep_depth = i;
2805 curr->curr_chain_key = hlock->prev_chain_key;
2807 for (; i < depth; i++) {
2808 hlock = curr->held_locks + i;
2809 if (!__lock_acquire(hlock->instance,
2810 hlock_class(hlock)->subclass, hlock->trylock,
2811 hlock->read, hlock->check, hlock->hardirqs_off,
2812 hlock->nest_lock, hlock->acquire_ip))
2816 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2822 * Remove the lock to the list of currently held locks in a
2823 * potentially non-nested (out of order) manner. This is a
2824 * relatively rare operation, as all the unlock APIs default
2825 * to nested mode (which uses lock_release()):
2828 lock_release_non_nested(struct task_struct *curr,
2829 struct lockdep_map *lock, unsigned long ip)
2831 struct held_lock *hlock, *prev_hlock;
2836 * Check whether the lock exists in the current stack
2839 depth = curr->lockdep_depth;
2840 if (DEBUG_LOCKS_WARN_ON(!depth))
2844 for (i = depth-1; i >= 0; i--) {
2845 hlock = curr->held_locks + i;
2847 * We must not cross into another context:
2849 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2851 if (hlock->instance == lock)
2855 return print_unlock_inbalance_bug(curr, lock, ip);
2858 lock_release_holdtime(hlock);
2861 * We have the right lock to unlock, 'hlock' points to it.
2862 * Now we remove it from the stack, and add back the other
2863 * entries (if any), recalculating the hash along the way:
2865 curr->lockdep_depth = i;
2866 curr->curr_chain_key = hlock->prev_chain_key;
2868 for (i++; i < depth; i++) {
2869 hlock = curr->held_locks + i;
2870 if (!__lock_acquire(hlock->instance,
2871 hlock_class(hlock)->subclass, hlock->trylock,
2872 hlock->read, hlock->check, hlock->hardirqs_off,
2873 hlock->nest_lock, hlock->acquire_ip))
2877 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2883 * Remove the lock to the list of currently held locks - this gets
2884 * called on mutex_unlock()/spin_unlock*() (or on a failed
2885 * mutex_lock_interruptible()). This is done for unlocks that nest
2886 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2888 static int lock_release_nested(struct task_struct *curr,
2889 struct lockdep_map *lock, unsigned long ip)
2891 struct held_lock *hlock;
2895 * Pop off the top of the lock stack:
2897 depth = curr->lockdep_depth - 1;
2898 hlock = curr->held_locks + depth;
2901 * Is the unlock non-nested:
2903 if (hlock->instance != lock)
2904 return lock_release_non_nested(curr, lock, ip);
2905 curr->lockdep_depth--;
2907 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2910 curr->curr_chain_key = hlock->prev_chain_key;
2912 lock_release_holdtime(hlock);
2914 #ifdef CONFIG_DEBUG_LOCKDEP
2915 hlock->prev_chain_key = 0;
2916 hlock->class_idx = 0;
2917 hlock->acquire_ip = 0;
2918 hlock->irq_context = 0;
2924 * Remove the lock to the list of currently held locks - this gets
2925 * called on mutex_unlock()/spin_unlock*() (or on a failed
2926 * mutex_lock_interruptible()). This is done for unlocks that nest
2927 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2930 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2932 struct task_struct *curr = current;
2934 if (!check_unlock(curr, lock, ip))
2938 if (!lock_release_nested(curr, lock, ip))
2941 if (!lock_release_non_nested(curr, lock, ip))
2945 check_chain_key(curr);
2949 * Check whether we follow the irq-flags state precisely:
2951 static void check_flags(unsigned long flags)
2953 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2954 defined(CONFIG_TRACE_IRQFLAGS)
2958 if (irqs_disabled_flags(flags)) {
2959 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
2960 printk("possible reason: unannotated irqs-off.\n");
2963 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
2964 printk("possible reason: unannotated irqs-on.\n");
2969 * We dont accurately track softirq state in e.g.
2970 * hardirq contexts (such as on 4KSTACKS), so only
2971 * check if not in hardirq contexts:
2973 if (!hardirq_count()) {
2974 if (softirq_count())
2975 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2977 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2981 print_irqtrace_events(current);
2985 void lock_set_class(struct lockdep_map *lock, const char *name,
2986 struct lock_class_key *key, unsigned int subclass,
2989 unsigned long flags;
2991 if (unlikely(current->lockdep_recursion))
2994 raw_local_irq_save(flags);
2995 current->lockdep_recursion = 1;
2997 if (__lock_set_class(lock, name, key, subclass, ip))
2998 check_chain_key(current);
2999 current->lockdep_recursion = 0;
3000 raw_local_irq_restore(flags);
3002 EXPORT_SYMBOL_GPL(lock_set_class);
3005 * We are not always called with irqs disabled - do that here,
3006 * and also avoid lockdep recursion:
3008 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3009 int trylock, int read, int check,
3010 struct lockdep_map *nest_lock, unsigned long ip)
3012 unsigned long flags;
3014 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3016 if (unlikely(current->lockdep_recursion))
3019 raw_local_irq_save(flags);
3022 current->lockdep_recursion = 1;
3023 __lock_acquire(lock, subclass, trylock, read, check,
3024 irqs_disabled_flags(flags), nest_lock, ip);
3025 current->lockdep_recursion = 0;
3026 raw_local_irq_restore(flags);
3028 EXPORT_SYMBOL_GPL(lock_acquire);
3030 void lock_release(struct lockdep_map *lock, int nested,
3033 unsigned long flags;
3035 trace_lock_release(lock, nested, ip);
3037 if (unlikely(current->lockdep_recursion))
3040 raw_local_irq_save(flags);
3042 current->lockdep_recursion = 1;
3043 __lock_release(lock, nested, ip);
3044 current->lockdep_recursion = 0;
3045 raw_local_irq_restore(flags);
3047 EXPORT_SYMBOL_GPL(lock_release);
3049 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3051 current->lockdep_reclaim_gfp = gfp_mask;
3054 void lockdep_clear_current_reclaim_state(void)
3056 current->lockdep_reclaim_gfp = 0;
3059 #ifdef CONFIG_LOCK_STAT
3061 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3064 if (!debug_locks_off())
3066 if (debug_locks_silent)
3069 printk("\n=================================\n");
3070 printk( "[ BUG: bad contention detected! ]\n");
3071 printk( "---------------------------------\n");
3072 printk("%s/%d is trying to contend lock (",
3073 curr->comm, task_pid_nr(curr));
3074 print_lockdep_cache(lock);
3077 printk("but there are no locks held!\n");
3078 printk("\nother info that might help us debug this:\n");
3079 lockdep_print_held_locks(curr);
3081 printk("\nstack backtrace:\n");
3088 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3090 struct task_struct *curr = current;
3091 struct held_lock *hlock, *prev_hlock;
3092 struct lock_class_stats *stats;
3094 int i, contention_point, contending_point;
3096 depth = curr->lockdep_depth;
3097 if (DEBUG_LOCKS_WARN_ON(!depth))
3101 for (i = depth-1; i >= 0; i--) {
3102 hlock = curr->held_locks + i;
3104 * We must not cross into another context:
3106 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3108 if (hlock->instance == lock)
3112 print_lock_contention_bug(curr, lock, ip);
3116 hlock->waittime_stamp = sched_clock();
3118 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3119 contending_point = lock_point(hlock_class(hlock)->contending_point,
3122 stats = get_lock_stats(hlock_class(hlock));
3123 if (contention_point < LOCKSTAT_POINTS)
3124 stats->contention_point[contention_point]++;
3125 if (contending_point < LOCKSTAT_POINTS)
3126 stats->contending_point[contending_point]++;
3127 if (lock->cpu != smp_processor_id())
3128 stats->bounces[bounce_contended + !!hlock->read]++;
3129 put_lock_stats(stats);
3133 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3135 struct task_struct *curr = current;
3136 struct held_lock *hlock, *prev_hlock;
3137 struct lock_class_stats *stats;
3143 depth = curr->lockdep_depth;
3144 if (DEBUG_LOCKS_WARN_ON(!depth))
3148 for (i = depth-1; i >= 0; i--) {
3149 hlock = curr->held_locks + i;
3151 * We must not cross into another context:
3153 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3155 if (hlock->instance == lock)
3159 print_lock_contention_bug(curr, lock, _RET_IP_);
3163 cpu = smp_processor_id();
3164 if (hlock->waittime_stamp) {
3165 now = sched_clock();
3166 waittime = now - hlock->waittime_stamp;
3167 hlock->holdtime_stamp = now;
3170 trace_lock_acquired(lock, ip, waittime);
3172 stats = get_lock_stats(hlock_class(hlock));
3175 lock_time_inc(&stats->read_waittime, waittime);
3177 lock_time_inc(&stats->write_waittime, waittime);
3179 if (lock->cpu != cpu)
3180 stats->bounces[bounce_acquired + !!hlock->read]++;
3181 put_lock_stats(stats);
3187 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3189 unsigned long flags;
3191 trace_lock_contended(lock, ip);
3193 if (unlikely(!lock_stat))
3196 if (unlikely(current->lockdep_recursion))
3199 raw_local_irq_save(flags);
3201 current->lockdep_recursion = 1;
3202 __lock_contended(lock, ip);
3203 current->lockdep_recursion = 0;
3204 raw_local_irq_restore(flags);
3206 EXPORT_SYMBOL_GPL(lock_contended);
3208 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3210 unsigned long flags;
3212 if (unlikely(!lock_stat))
3215 if (unlikely(current->lockdep_recursion))
3218 raw_local_irq_save(flags);
3220 current->lockdep_recursion = 1;
3221 __lock_acquired(lock, ip);
3222 current->lockdep_recursion = 0;
3223 raw_local_irq_restore(flags);
3225 EXPORT_SYMBOL_GPL(lock_acquired);
3229 * Used by the testsuite, sanitize the validator state
3230 * after a simulated failure:
3233 void lockdep_reset(void)
3235 unsigned long flags;
3238 raw_local_irq_save(flags);
3239 current->curr_chain_key = 0;
3240 current->lockdep_depth = 0;
3241 current->lockdep_recursion = 0;
3242 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3243 nr_hardirq_chains = 0;
3244 nr_softirq_chains = 0;
3245 nr_process_chains = 0;
3247 for (i = 0; i < CHAINHASH_SIZE; i++)
3248 INIT_LIST_HEAD(chainhash_table + i);
3249 raw_local_irq_restore(flags);
3252 static void zap_class(struct lock_class *class)
3257 * Remove all dependencies this lock is
3260 for (i = 0; i < nr_list_entries; i++) {
3261 if (list_entries[i].class == class)
3262 list_del_rcu(&list_entries[i].entry);
3265 * Unhash the class and remove it from the all_lock_classes list:
3267 list_del_rcu(&class->hash_entry);
3268 list_del_rcu(&class->lock_entry);
3273 static inline int within(const void *addr, void *start, unsigned long size)
3275 return addr >= start && addr < start + size;
3278 void lockdep_free_key_range(void *start, unsigned long size)
3280 struct lock_class *class, *next;
3281 struct list_head *head;
3282 unsigned long flags;
3286 raw_local_irq_save(flags);
3287 locked = graph_lock();
3290 * Unhash all classes that were created by this module:
3292 for (i = 0; i < CLASSHASH_SIZE; i++) {
3293 head = classhash_table + i;
3294 if (list_empty(head))
3296 list_for_each_entry_safe(class, next, head, hash_entry) {
3297 if (within(class->key, start, size))
3299 else if (within(class->name, start, size))
3306 raw_local_irq_restore(flags);
3309 void lockdep_reset_lock(struct lockdep_map *lock)
3311 struct lock_class *class, *next;
3312 struct list_head *head;
3313 unsigned long flags;
3317 raw_local_irq_save(flags);
3320 * Remove all classes this lock might have:
3322 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3324 * If the class exists we look it up and zap it:
3326 class = look_up_lock_class(lock, j);
3331 * Debug check: in the end all mapped classes should
3334 locked = graph_lock();
3335 for (i = 0; i < CLASSHASH_SIZE; i++) {
3336 head = classhash_table + i;
3337 if (list_empty(head))
3339 list_for_each_entry_safe(class, next, head, hash_entry) {
3340 if (unlikely(class == lock->class_cache)) {
3341 if (debug_locks_off_graph_unlock())
3351 raw_local_irq_restore(flags);
3354 void lockdep_init(void)
3359 * Some architectures have their own start_kernel()
3360 * code which calls lockdep_init(), while we also
3361 * call lockdep_init() from the start_kernel() itself,
3362 * and we want to initialize the hashes only once:
3364 if (lockdep_initialized)
3367 for (i = 0; i < CLASSHASH_SIZE; i++)
3368 INIT_LIST_HEAD(classhash_table + i);
3370 for (i = 0; i < CHAINHASH_SIZE; i++)
3371 INIT_LIST_HEAD(chainhash_table + i);
3373 lockdep_initialized = 1;
3376 void __init lockdep_info(void)
3378 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3380 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3381 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3382 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3383 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3384 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3385 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3386 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3388 printk(" memory used by lock dependency info: %lu kB\n",
3389 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3390 sizeof(struct list_head) * CLASSHASH_SIZE +
3391 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3392 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3393 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
3395 printk(" per task-struct memory footprint: %lu bytes\n",
3396 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3398 #ifdef CONFIG_DEBUG_LOCKDEP
3399 if (lockdep_init_error) {
3400 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3401 printk("Call stack leading to lockdep invocation was:\n");
3402 print_stack_trace(&lockdep_init_trace, 0);
3408 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3409 const void *mem_to, struct held_lock *hlock)
3411 if (!debug_locks_off())
3413 if (debug_locks_silent)
3416 printk("\n=========================\n");
3417 printk( "[ BUG: held lock freed! ]\n");
3418 printk( "-------------------------\n");
3419 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3420 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3422 lockdep_print_held_locks(curr);
3424 printk("\nstack backtrace:\n");
3428 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3429 const void* lock_from, unsigned long lock_len)
3431 return lock_from + lock_len <= mem_from ||
3432 mem_from + mem_len <= lock_from;
3436 * Called when kernel memory is freed (or unmapped), or if a lock
3437 * is destroyed or reinitialized - this code checks whether there is
3438 * any held lock in the memory range of <from> to <to>:
3440 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3442 struct task_struct *curr = current;
3443 struct held_lock *hlock;
3444 unsigned long flags;
3447 if (unlikely(!debug_locks))
3450 local_irq_save(flags);
3451 for (i = 0; i < curr->lockdep_depth; i++) {
3452 hlock = curr->held_locks + i;
3454 if (not_in_range(mem_from, mem_len, hlock->instance,
3455 sizeof(*hlock->instance)))
3458 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3461 local_irq_restore(flags);
3463 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3465 static void print_held_locks_bug(struct task_struct *curr)
3467 if (!debug_locks_off())
3469 if (debug_locks_silent)
3472 printk("\n=====================================\n");
3473 printk( "[ BUG: lock held at task exit time! ]\n");
3474 printk( "-------------------------------------\n");
3475 printk("%s/%d is exiting with locks still held!\n",
3476 curr->comm, task_pid_nr(curr));
3477 lockdep_print_held_locks(curr);
3479 printk("\nstack backtrace:\n");
3483 void debug_check_no_locks_held(struct task_struct *task)
3485 if (unlikely(task->lockdep_depth > 0))
3486 print_held_locks_bug(task);
3489 void debug_show_all_locks(void)
3491 struct task_struct *g, *p;
3495 if (unlikely(!debug_locks)) {
3496 printk("INFO: lockdep is turned off.\n");
3499 printk("\nShowing all locks held in the system:\n");
3502 * Here we try to get the tasklist_lock as hard as possible,
3503 * if not successful after 2 seconds we ignore it (but keep
3504 * trying). This is to enable a debug printout even if a
3505 * tasklist_lock-holding task deadlocks or crashes.
3508 if (!read_trylock(&tasklist_lock)) {
3510 printk("hm, tasklist_lock locked, retrying... ");
3513 printk(" #%d", 10-count);
3517 printk(" ignoring it.\n");
3521 printk(KERN_CONT " locked it.\n");
3524 do_each_thread(g, p) {
3526 * It's not reliable to print a task's held locks
3527 * if it's not sleeping (or if it's not the current
3530 if (p->state == TASK_RUNNING && p != current)
3532 if (p->lockdep_depth)
3533 lockdep_print_held_locks(p);
3535 if (read_trylock(&tasklist_lock))
3537 } while_each_thread(g, p);
3540 printk("=============================================\n\n");
3543 read_unlock(&tasklist_lock);
3545 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3548 * Careful: only use this function if you are sure that
3549 * the task cannot run in parallel!
3551 void __debug_show_held_locks(struct task_struct *task)
3553 if (unlikely(!debug_locks)) {
3554 printk("INFO: lockdep is turned off.\n");
3557 lockdep_print_held_locks(task);
3559 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3561 void debug_show_held_locks(struct task_struct *task)
3563 __debug_show_held_locks(task);
3565 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3567 void lockdep_sys_exit(void)
3569 struct task_struct *curr = current;
3571 if (unlikely(curr->lockdep_depth)) {
3572 if (!debug_locks_off())
3574 printk("\n================================================\n");
3575 printk( "[ BUG: lock held when returning to user space! ]\n");
3576 printk( "------------------------------------------------\n");
3577 printk("%s/%d is leaving the kernel with locks still held!\n",
3578 curr->comm, curr->pid);
3579 lockdep_print_held_locks(curr);