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 the shortest lock dependencies from @start to @end in reverse order:
582 print_shortest_lock_dependencies(struct lock_list *leaf,
583 struct lock_list *root)
585 struct lock_list *entry = leaf;
588 /*compute depth from generated tree by BFS*/
589 depth = get_lock_depth(leaf);
592 print_lock_class_header(entry->class, depth);
593 printk("%*s ... acquired at:\n", depth, "");
594 print_stack_trace(&entry->trace, 2);
597 if (depth == 0 && (entry != root)) {
598 printk("lockdep:%s bad BFS generated tree\n", __func__);
602 entry = get_lock_parent(entry);
604 } while (entry && (depth >= 0));
609 * printk all lock dependencies starting at <entry>:
612 print_lock_dependencies(struct lock_class *class, int depth)
614 struct lock_list *entry;
616 if (lockdep_dependency_visit(class, depth))
619 if (DEBUG_LOCKS_WARN_ON(depth >= 20))
622 print_lock_class_header(class, depth);
624 list_for_each_entry(entry, &class->locks_after, entry) {
625 if (DEBUG_LOCKS_WARN_ON(!entry->class))
628 print_lock_dependencies(entry->class, depth + 1);
630 printk("%*s ... acquired at:\n",depth,"");
631 print_stack_trace(&entry->trace, 2);
636 static void print_kernel_version(void)
638 printk("%s %.*s\n", init_utsname()->release,
639 (int)strcspn(init_utsname()->version, " "),
640 init_utsname()->version);
643 static int very_verbose(struct lock_class *class)
646 return class_filter(class);
652 * Is this the address of a static object:
654 static int static_obj(void *obj)
656 unsigned long start = (unsigned long) &_stext,
657 end = (unsigned long) &_end,
658 addr = (unsigned long) obj;
666 if ((addr >= start) && (addr < end))
673 for_each_possible_cpu(i) {
674 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
675 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
678 if ((addr >= start) && (addr < end))
686 return is_module_address(addr);
690 * To make lock name printouts unique, we calculate a unique
691 * class->name_version generation counter:
693 static int count_matching_names(struct lock_class *new_class)
695 struct lock_class *class;
698 if (!new_class->name)
701 list_for_each_entry(class, &all_lock_classes, lock_entry) {
702 if (new_class->key - new_class->subclass == class->key)
703 return class->name_version;
704 if (class->name && !strcmp(class->name, new_class->name))
705 count = max(count, class->name_version);
712 * Register a lock's class in the hash-table, if the class is not present
713 * yet. Otherwise we look it up. We cache the result in the lock object
714 * itself, so actual lookup of the hash should be once per lock object.
716 static inline struct lock_class *
717 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
719 struct lockdep_subclass_key *key;
720 struct list_head *hash_head;
721 struct lock_class *class;
723 #ifdef CONFIG_DEBUG_LOCKDEP
725 * If the architecture calls into lockdep before initializing
726 * the hashes then we'll warn about it later. (we cannot printk
729 if (unlikely(!lockdep_initialized)) {
731 lockdep_init_error = 1;
732 save_stack_trace(&lockdep_init_trace);
737 * Static locks do not have their class-keys yet - for them the key
738 * is the lock object itself:
740 if (unlikely(!lock->key))
741 lock->key = (void *)lock;
744 * NOTE: the class-key must be unique. For dynamic locks, a static
745 * lock_class_key variable is passed in through the mutex_init()
746 * (or spin_lock_init()) call - which acts as the key. For static
747 * locks we use the lock object itself as the key.
749 BUILD_BUG_ON(sizeof(struct lock_class_key) >
750 sizeof(struct lockdep_map));
752 key = lock->key->subkeys + subclass;
754 hash_head = classhashentry(key);
757 * We can walk the hash lockfree, because the hash only
758 * grows, and we are careful when adding entries to the end:
760 list_for_each_entry(class, hash_head, hash_entry) {
761 if (class->key == key) {
762 WARN_ON_ONCE(class->name != lock->name);
771 * Register a lock's class in the hash-table, if the class is not present
772 * yet. Otherwise we look it up. We cache the result in the lock object
773 * itself, so actual lookup of the hash should be once per lock object.
775 static inline struct lock_class *
776 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
778 struct lockdep_subclass_key *key;
779 struct list_head *hash_head;
780 struct lock_class *class;
783 class = look_up_lock_class(lock, subclass);
788 * Debug-check: all keys must be persistent!
790 if (!static_obj(lock->key)) {
792 printk("INFO: trying to register non-static key.\n");
793 printk("the code is fine but needs lockdep annotation.\n");
794 printk("turning off the locking correctness validator.\n");
800 key = lock->key->subkeys + subclass;
801 hash_head = classhashentry(key);
803 raw_local_irq_save(flags);
805 raw_local_irq_restore(flags);
809 * We have to do the hash-walk again, to avoid races
812 list_for_each_entry(class, hash_head, hash_entry)
813 if (class->key == key)
816 * Allocate a new key from the static array, and add it to
819 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
820 if (!debug_locks_off_graph_unlock()) {
821 raw_local_irq_restore(flags);
824 raw_local_irq_restore(flags);
826 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
827 printk("turning off the locking correctness validator.\n");
831 class = lock_classes + nr_lock_classes++;
832 debug_atomic_inc(&nr_unused_locks);
834 class->name = lock->name;
835 class->subclass = subclass;
836 INIT_LIST_HEAD(&class->lock_entry);
837 INIT_LIST_HEAD(&class->locks_before);
838 INIT_LIST_HEAD(&class->locks_after);
839 class->name_version = count_matching_names(class);
841 * We use RCU's safe list-add method to make
842 * parallel walking of the hash-list safe:
844 list_add_tail_rcu(&class->hash_entry, hash_head);
846 * Add it to the global list of classes:
848 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
850 if (verbose(class)) {
852 raw_local_irq_restore(flags);
854 printk("\nnew class %p: %s", class->key, class->name);
855 if (class->name_version > 1)
856 printk("#%d", class->name_version);
860 raw_local_irq_save(flags);
862 raw_local_irq_restore(flags);
868 raw_local_irq_restore(flags);
870 if (!subclass || force)
871 lock->class_cache = class;
873 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
879 #ifdef CONFIG_PROVE_LOCKING
881 * Allocate a lockdep entry. (assumes the graph_lock held, returns
882 * with NULL on failure)
884 static struct lock_list *alloc_list_entry(void)
886 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
887 if (!debug_locks_off_graph_unlock())
890 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
891 printk("turning off the locking correctness validator.\n");
895 return list_entries + nr_list_entries++;
899 * Add a new dependency to the head of the list:
901 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
902 struct list_head *head, unsigned long ip, int distance)
904 struct lock_list *entry;
906 * Lock not present yet - get a new dependency struct and
907 * add it to the list:
909 entry = alloc_list_entry();
913 if (!save_trace(&entry->trace))
917 entry->distance = distance;
919 * Since we never remove from the dependency list, the list can
920 * be walked lockless by other CPUs, it's only allocation
921 * that must be protected by the spinlock. But this also means
922 * we must make new entries visible only once writes to the
923 * entry become visible - hence the RCU op:
925 list_add_tail_rcu(&entry->entry, head);
930 unsigned long bfs_accessed[BITS_TO_LONGS(MAX_LOCKDEP_ENTRIES)];
931 static struct circular_queue lock_cq;
933 static int __bfs(struct lock_list *source_entry,
935 int (*match)(struct lock_list *entry, void *data),
936 struct lock_list **target_entry,
939 struct lock_list *entry;
940 struct list_head *head;
941 struct circular_queue *cq = &lock_cq;
944 if (match(source_entry, data)) {
945 *target_entry = source_entry;
951 head = &source_entry->class->locks_after;
953 head = &source_entry->class->locks_before;
955 if (list_empty(head))
959 __cq_enqueue(cq, (unsigned long)source_entry);
961 while (!__cq_empty(cq)) {
962 struct lock_list *lock;
964 __cq_dequeue(cq, (unsigned long *)&lock);
972 head = &lock->class->locks_after;
974 head = &lock->class->locks_before;
976 list_for_each_entry(entry, head, entry) {
977 if (!lock_accessed(entry)) {
978 mark_lock_accessed(entry, lock);
979 if (match(entry, data)) {
980 *target_entry = entry;
985 if (__cq_enqueue(cq, (unsigned long)entry)) {
996 static inline int __bfs_forwards(struct lock_list *src_entry,
998 int (*match)(struct lock_list *entry, void *data),
999 struct lock_list **target_entry)
1001 return __bfs(src_entry, data, match, target_entry, 1);
1005 static inline int __bfs_backwards(struct lock_list *src_entry,
1007 int (*match)(struct lock_list *entry, void *data),
1008 struct lock_list **target_entry)
1010 return __bfs(src_entry, data, match, target_entry, 0);
1015 * Recursive, forwards-direction lock-dependency checking, used for
1016 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1021 * Print a dependency chain entry (this is only done when a deadlock
1022 * has been detected):
1025 print_circular_bug_entry(struct lock_list *target, int depth)
1027 if (debug_locks_silent)
1029 printk("\n-> #%u", depth);
1030 print_lock_name(target->class);
1032 print_stack_trace(&target->trace, 6);
1038 * When a circular dependency is detected, print the
1042 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1043 struct held_lock *check_src,
1044 struct held_lock *check_tgt)
1046 struct task_struct *curr = current;
1048 if (debug_locks_silent)
1051 printk("\n=======================================================\n");
1052 printk( "[ INFO: possible circular locking dependency detected ]\n");
1053 print_kernel_version();
1054 printk( "-------------------------------------------------------\n");
1055 printk("%s/%d is trying to acquire lock:\n",
1056 curr->comm, task_pid_nr(curr));
1057 print_lock(check_src);
1058 printk("\nbut task is already holding lock:\n");
1059 print_lock(check_tgt);
1060 printk("\nwhich lock already depends on the new lock.\n\n");
1061 printk("\nthe existing dependency chain (in reverse order) is:\n");
1063 print_circular_bug_entry(entry, depth);
1068 static inline int class_equal(struct lock_list *entry, void *data)
1070 return entry->class == data;
1073 static noinline int print_circular_bug(struct lock_list *this,
1074 struct lock_list *target,
1075 struct held_lock *check_src,
1076 struct held_lock *check_tgt)
1078 struct task_struct *curr = current;
1079 struct lock_list *parent;
1082 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1085 if (!save_trace(&this->trace))
1088 depth = get_lock_depth(target);
1090 print_circular_bug_header(target, depth, check_src, check_tgt);
1092 parent = get_lock_parent(target);
1095 print_circular_bug_entry(parent, --depth);
1096 parent = get_lock_parent(parent);
1099 printk("\nother info that might help us debug this:\n\n");
1100 lockdep_print_held_locks(curr);
1102 printk("\nstack backtrace:\n");
1108 static noinline int print_bfs_bug(int ret)
1110 if (!debug_locks_off_graph_unlock())
1113 WARN(1, "lockdep bfs error:%d\n", ret);
1118 static int noop_count(struct lock_list *entry, void *data)
1120 (*(unsigned long *)data)++;
1124 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1126 unsigned long count = 0;
1127 struct lock_list *uninitialized_var(target_entry);
1129 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1133 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1135 unsigned long ret, flags;
1136 struct lock_list this;
1141 local_irq_save(flags);
1142 __raw_spin_lock(&lockdep_lock);
1143 ret = __lockdep_count_forward_deps(&this);
1144 __raw_spin_unlock(&lockdep_lock);
1145 local_irq_restore(flags);
1150 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1152 unsigned long count = 0;
1153 struct lock_list *uninitialized_var(target_entry);
1155 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1160 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1162 unsigned long ret, flags;
1163 struct lock_list this;
1168 local_irq_save(flags);
1169 __raw_spin_lock(&lockdep_lock);
1170 ret = __lockdep_count_backward_deps(&this);
1171 __raw_spin_unlock(&lockdep_lock);
1172 local_irq_restore(flags);
1178 * Prove that the dependency graph starting at <entry> can not
1179 * lead to <target>. Print an error and return 0 if it does.
1182 check_noncircular(struct lock_list *root, struct lock_class *target,
1183 struct lock_list **target_entry)
1187 debug_atomic_inc(&nr_cyclic_checks);
1189 result = __bfs_forwards(root, target, class_equal, target_entry);
1194 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1196 * Forwards and backwards subgraph searching, for the purposes of
1197 * proving that two subgraphs can be connected by a new dependency
1198 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1202 #define BFS_PROCESS_RET(ret) do { \
1204 return print_bfs_bug(ret); \
1209 static inline int usage_match(struct lock_list *entry, void *bit)
1211 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1217 * Find a node in the forwards-direction dependency sub-graph starting
1218 * at @root->class that matches @bit.
1220 * Return 0 if such a node exists in the subgraph, and put that node
1221 * into *@target_entry.
1223 * Return 1 otherwise and keep *@target_entry unchanged.
1224 * Return <0 on error.
1227 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1228 struct lock_list **target_entry)
1232 debug_atomic_inc(&nr_find_usage_forwards_checks);
1234 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1240 * Find a node in the backwards-direction dependency sub-graph starting
1241 * at @root->class that matches @bit.
1243 * Return 0 if such a node exists in the subgraph, and put that node
1244 * into *@target_entry.
1246 * Return 1 otherwise and keep *@target_entry unchanged.
1247 * Return <0 on error.
1250 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1251 struct lock_list **target_entry)
1255 debug_atomic_inc(&nr_find_usage_backwards_checks);
1257 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1264 print_bad_irq_dependency(struct task_struct *curr,
1265 struct lock_list *prev_root,
1266 struct lock_list *next_root,
1267 struct lock_list *backwards_entry,
1268 struct lock_list *forwards_entry,
1269 struct held_lock *prev,
1270 struct held_lock *next,
1271 enum lock_usage_bit bit1,
1272 enum lock_usage_bit bit2,
1273 const char *irqclass)
1275 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1278 printk("\n======================================================\n");
1279 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1280 irqclass, irqclass);
1281 print_kernel_version();
1282 printk( "------------------------------------------------------\n");
1283 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1284 curr->comm, task_pid_nr(curr),
1285 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1286 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1287 curr->hardirqs_enabled,
1288 curr->softirqs_enabled);
1291 printk("\nand this task is already holding:\n");
1293 printk("which would create a new lock dependency:\n");
1294 print_lock_name(hlock_class(prev));
1296 print_lock_name(hlock_class(next));
1299 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1301 print_lock_name(backwards_entry->class);
1302 printk("\n... which became %s-irq-safe at:\n", irqclass);
1304 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1306 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1307 print_lock_name(forwards_entry->class);
1308 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1311 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1313 printk("\nother info that might help us debug this:\n\n");
1314 lockdep_print_held_locks(curr);
1316 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1317 printk(" and the holding lock:\n");
1318 if (!save_trace(&prev_root->trace))
1320 print_shortest_lock_dependencies(backwards_entry, prev_root);
1322 printk("\nthe dependencies between the lock to be acquired");
1323 printk(" and %s-irq-unsafe lock:\n", irqclass);
1324 if (!save_trace(&next_root->trace))
1326 print_shortest_lock_dependencies(forwards_entry, next_root);
1328 printk("\nstack backtrace:\n");
1335 check_usage(struct task_struct *curr, struct held_lock *prev,
1336 struct held_lock *next, enum lock_usage_bit bit_backwards,
1337 enum lock_usage_bit bit_forwards, const char *irqclass)
1340 struct lock_list this, that;
1341 struct lock_list *uninitialized_var(target_entry);
1342 struct lock_list *uninitialized_var(target_entry1);
1346 this.class = hlock_class(prev);
1347 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1348 BFS_PROCESS_RET(ret);
1351 that.class = hlock_class(next);
1352 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1353 BFS_PROCESS_RET(ret);
1355 return print_bad_irq_dependency(curr, &this, &that,
1356 target_entry, target_entry1,
1358 bit_backwards, bit_forwards, irqclass);
1361 static const char *state_names[] = {
1362 #define LOCKDEP_STATE(__STATE) \
1363 __stringify(__STATE),
1364 #include "lockdep_states.h"
1365 #undef LOCKDEP_STATE
1368 static const char *state_rnames[] = {
1369 #define LOCKDEP_STATE(__STATE) \
1370 __stringify(__STATE)"-READ",
1371 #include "lockdep_states.h"
1372 #undef LOCKDEP_STATE
1375 static inline const char *state_name(enum lock_usage_bit bit)
1377 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1380 static int exclusive_bit(int new_bit)
1388 * bit 0 - write/read
1389 * bit 1 - used_in/enabled
1393 int state = new_bit & ~3;
1394 int dir = new_bit & 2;
1397 * keep state, bit flip the direction and strip read.
1399 return state | (dir ^ 2);
1402 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1403 struct held_lock *next, enum lock_usage_bit bit)
1406 * Prove that the new dependency does not connect a hardirq-safe
1407 * lock with a hardirq-unsafe lock - to achieve this we search
1408 * the backwards-subgraph starting at <prev>, and the
1409 * forwards-subgraph starting at <next>:
1411 if (!check_usage(curr, prev, next, bit,
1412 exclusive_bit(bit), state_name(bit)))
1418 * Prove that the new dependency does not connect a hardirq-safe-read
1419 * lock with a hardirq-unsafe lock - to achieve this we search
1420 * the backwards-subgraph starting at <prev>, and the
1421 * forwards-subgraph starting at <next>:
1423 if (!check_usage(curr, prev, next, bit,
1424 exclusive_bit(bit), state_name(bit)))
1431 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1432 struct held_lock *next)
1434 #define LOCKDEP_STATE(__STATE) \
1435 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1437 #include "lockdep_states.h"
1438 #undef LOCKDEP_STATE
1443 static void inc_chains(void)
1445 if (current->hardirq_context)
1446 nr_hardirq_chains++;
1448 if (current->softirq_context)
1449 nr_softirq_chains++;
1451 nr_process_chains++;
1458 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1459 struct held_lock *next)
1464 static inline void inc_chains(void)
1466 nr_process_chains++;
1472 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1473 struct held_lock *next)
1475 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1478 printk("\n=============================================\n");
1479 printk( "[ INFO: possible recursive locking detected ]\n");
1480 print_kernel_version();
1481 printk( "---------------------------------------------\n");
1482 printk("%s/%d is trying to acquire lock:\n",
1483 curr->comm, task_pid_nr(curr));
1485 printk("\nbut task is already holding lock:\n");
1488 printk("\nother info that might help us debug this:\n");
1489 lockdep_print_held_locks(curr);
1491 printk("\nstack backtrace:\n");
1498 * Check whether we are holding such a class already.
1500 * (Note that this has to be done separately, because the graph cannot
1501 * detect such classes of deadlocks.)
1503 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1506 check_deadlock(struct task_struct *curr, struct held_lock *next,
1507 struct lockdep_map *next_instance, int read)
1509 struct held_lock *prev;
1510 struct held_lock *nest = NULL;
1513 for (i = 0; i < curr->lockdep_depth; i++) {
1514 prev = curr->held_locks + i;
1516 if (prev->instance == next->nest_lock)
1519 if (hlock_class(prev) != hlock_class(next))
1523 * Allow read-after-read recursion of the same
1524 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1526 if ((read == 2) && prev->read)
1530 * We're holding the nest_lock, which serializes this lock's
1531 * nesting behaviour.
1536 return print_deadlock_bug(curr, prev, next);
1542 * There was a chain-cache miss, and we are about to add a new dependency
1543 * to a previous lock. We recursively validate the following rules:
1545 * - would the adding of the <prev> -> <next> dependency create a
1546 * circular dependency in the graph? [== circular deadlock]
1548 * - does the new prev->next dependency connect any hardirq-safe lock
1549 * (in the full backwards-subgraph starting at <prev>) with any
1550 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1551 * <next>)? [== illegal lock inversion with hardirq contexts]
1553 * - does the new prev->next dependency connect any softirq-safe lock
1554 * (in the full backwards-subgraph starting at <prev>) with any
1555 * softirq-unsafe lock (in the full forwards-subgraph starting at
1556 * <next>)? [== illegal lock inversion with softirq contexts]
1558 * any of these scenarios could lead to a deadlock.
1560 * Then if all the validations pass, we add the forwards and backwards
1564 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1565 struct held_lock *next, int distance)
1567 struct lock_list *entry;
1569 struct lock_list this;
1570 struct lock_list *uninitialized_var(target_entry);
1573 * Prove that the new <prev> -> <next> dependency would not
1574 * create a circular dependency in the graph. (We do this by
1575 * forward-recursing into the graph starting at <next>, and
1576 * checking whether we can reach <prev>.)
1578 * We are using global variables to control the recursion, to
1579 * keep the stackframe size of the recursive functions low:
1581 this.class = hlock_class(next);
1583 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1585 return print_circular_bug(&this, target_entry, next, prev);
1586 else if (unlikely(ret < 0))
1587 return print_bfs_bug(ret);
1589 if (!check_prev_add_irq(curr, prev, next))
1593 * For recursive read-locks we do all the dependency checks,
1594 * but we dont store read-triggered dependencies (only
1595 * write-triggered dependencies). This ensures that only the
1596 * write-side dependencies matter, and that if for example a
1597 * write-lock never takes any other locks, then the reads are
1598 * equivalent to a NOP.
1600 if (next->read == 2 || prev->read == 2)
1603 * Is the <prev> -> <next> dependency already present?
1605 * (this may occur even though this is a new chain: consider
1606 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1607 * chains - the second one will be new, but L1 already has
1608 * L2 added to its dependency list, due to the first chain.)
1610 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1611 if (entry->class == hlock_class(next)) {
1613 entry->distance = 1;
1619 * Ok, all validations passed, add the new lock
1620 * to the previous lock's dependency list:
1622 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1623 &hlock_class(prev)->locks_after,
1624 next->acquire_ip, distance);
1629 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1630 &hlock_class(next)->locks_before,
1631 next->acquire_ip, distance);
1636 * Debugging printouts:
1638 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1640 printk("\n new dependency: ");
1641 print_lock_name(hlock_class(prev));
1643 print_lock_name(hlock_class(next));
1646 return graph_lock();
1652 * Add the dependency to all directly-previous locks that are 'relevant'.
1653 * The ones that are relevant are (in increasing distance from curr):
1654 * all consecutive trylock entries and the final non-trylock entry - or
1655 * the end of this context's lock-chain - whichever comes first.
1658 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1660 int depth = curr->lockdep_depth;
1661 struct held_lock *hlock;
1666 * Depth must not be zero for a non-head lock:
1671 * At least two relevant locks must exist for this
1674 if (curr->held_locks[depth].irq_context !=
1675 curr->held_locks[depth-1].irq_context)
1679 int distance = curr->lockdep_depth - depth + 1;
1680 hlock = curr->held_locks + depth-1;
1682 * Only non-recursive-read entries get new dependencies
1685 if (hlock->read != 2) {
1686 if (!check_prev_add(curr, hlock, next, distance))
1689 * Stop after the first non-trylock entry,
1690 * as non-trylock entries have added their
1691 * own direct dependencies already, so this
1692 * lock is connected to them indirectly:
1694 if (!hlock->trylock)
1699 * End of lock-stack?
1704 * Stop the search if we cross into another context:
1706 if (curr->held_locks[depth].irq_context !=
1707 curr->held_locks[depth-1].irq_context)
1712 if (!debug_locks_off_graph_unlock())
1720 unsigned long nr_lock_chains;
1721 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1722 int nr_chain_hlocks;
1723 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1725 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1727 return lock_classes + chain_hlocks[chain->base + i];
1731 * Look up a dependency chain. If the key is not present yet then
1732 * add it and return 1 - in this case the new dependency chain is
1733 * validated. If the key is already hashed, return 0.
1734 * (On return with 1 graph_lock is held.)
1736 static inline int lookup_chain_cache(struct task_struct *curr,
1737 struct held_lock *hlock,
1740 struct lock_class *class = hlock_class(hlock);
1741 struct list_head *hash_head = chainhashentry(chain_key);
1742 struct lock_chain *chain;
1743 struct held_lock *hlock_curr, *hlock_next;
1746 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1749 * We can walk it lock-free, because entries only get added
1752 list_for_each_entry(chain, hash_head, entry) {
1753 if (chain->chain_key == chain_key) {
1755 debug_atomic_inc(&chain_lookup_hits);
1756 if (very_verbose(class))
1757 printk("\nhash chain already cached, key: "
1758 "%016Lx tail class: [%p] %s\n",
1759 (unsigned long long)chain_key,
1760 class->key, class->name);
1764 if (very_verbose(class))
1765 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1766 (unsigned long long)chain_key, class->key, class->name);
1768 * Allocate a new chain entry from the static array, and add
1774 * We have to walk the chain again locked - to avoid duplicates:
1776 list_for_each_entry(chain, hash_head, entry) {
1777 if (chain->chain_key == chain_key) {
1782 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1783 if (!debug_locks_off_graph_unlock())
1786 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1787 printk("turning off the locking correctness validator.\n");
1791 chain = lock_chains + nr_lock_chains++;
1792 chain->chain_key = chain_key;
1793 chain->irq_context = hlock->irq_context;
1794 /* Find the first held_lock of current chain */
1796 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1797 hlock_curr = curr->held_locks + i;
1798 if (hlock_curr->irq_context != hlock_next->irq_context)
1803 chain->depth = curr->lockdep_depth + 1 - i;
1804 cn = nr_chain_hlocks;
1805 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1806 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1811 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1813 for (j = 0; j < chain->depth - 1; j++, i++) {
1814 int lock_id = curr->held_locks[i].class_idx - 1;
1815 chain_hlocks[chain->base + j] = lock_id;
1817 chain_hlocks[chain->base + j] = class - lock_classes;
1819 list_add_tail_rcu(&chain->entry, hash_head);
1820 debug_atomic_inc(&chain_lookup_misses);
1826 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1827 struct held_lock *hlock, int chain_head, u64 chain_key)
1830 * Trylock needs to maintain the stack of held locks, but it
1831 * does not add new dependencies, because trylock can be done
1834 * We look up the chain_key and do the O(N^2) check and update of
1835 * the dependencies only if this is a new dependency chain.
1836 * (If lookup_chain_cache() returns with 1 it acquires
1837 * graph_lock for us)
1839 if (!hlock->trylock && (hlock->check == 2) &&
1840 lookup_chain_cache(curr, hlock, chain_key)) {
1842 * Check whether last held lock:
1844 * - is irq-safe, if this lock is irq-unsafe
1845 * - is softirq-safe, if this lock is hardirq-unsafe
1847 * And check whether the new lock's dependency graph
1848 * could lead back to the previous lock.
1850 * any of these scenarios could lead to a deadlock. If
1853 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1858 * Mark recursive read, as we jump over it when
1859 * building dependencies (just like we jump over
1865 * Add dependency only if this lock is not the head
1866 * of the chain, and if it's not a secondary read-lock:
1868 if (!chain_head && ret != 2)
1869 if (!check_prevs_add(curr, hlock))
1873 /* after lookup_chain_cache(): */
1874 if (unlikely(!debug_locks))
1880 static inline int validate_chain(struct task_struct *curr,
1881 struct lockdep_map *lock, struct held_lock *hlock,
1882 int chain_head, u64 chain_key)
1889 * We are building curr_chain_key incrementally, so double-check
1890 * it from scratch, to make sure that it's done correctly:
1892 static void check_chain_key(struct task_struct *curr)
1894 #ifdef CONFIG_DEBUG_LOCKDEP
1895 struct held_lock *hlock, *prev_hlock = NULL;
1899 for (i = 0; i < curr->lockdep_depth; i++) {
1900 hlock = curr->held_locks + i;
1901 if (chain_key != hlock->prev_chain_key) {
1903 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1904 curr->lockdep_depth, i,
1905 (unsigned long long)chain_key,
1906 (unsigned long long)hlock->prev_chain_key);
1909 id = hlock->class_idx - 1;
1910 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1913 if (prev_hlock && (prev_hlock->irq_context !=
1914 hlock->irq_context))
1916 chain_key = iterate_chain_key(chain_key, id);
1919 if (chain_key != curr->curr_chain_key) {
1921 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1922 curr->lockdep_depth, i,
1923 (unsigned long long)chain_key,
1924 (unsigned long long)curr->curr_chain_key);
1930 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1931 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1933 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1936 printk("\n=================================\n");
1937 printk( "[ INFO: inconsistent lock state ]\n");
1938 print_kernel_version();
1939 printk( "---------------------------------\n");
1941 printk("inconsistent {%s} -> {%s} usage.\n",
1942 usage_str[prev_bit], usage_str[new_bit]);
1944 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1945 curr->comm, task_pid_nr(curr),
1946 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1947 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1948 trace_hardirqs_enabled(curr),
1949 trace_softirqs_enabled(curr));
1952 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1953 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
1955 print_irqtrace_events(curr);
1956 printk("\nother info that might help us debug this:\n");
1957 lockdep_print_held_locks(curr);
1959 printk("\nstack backtrace:\n");
1966 * Print out an error if an invalid bit is set:
1969 valid_state(struct task_struct *curr, struct held_lock *this,
1970 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1972 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
1973 return print_usage_bug(curr, this, bad_bit, new_bit);
1977 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1978 enum lock_usage_bit new_bit);
1980 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1983 * print irq inversion bug:
1986 print_irq_inversion_bug(struct task_struct *curr,
1987 struct lock_list *root, struct lock_list *other,
1988 struct held_lock *this, int forwards,
1989 const char *irqclass)
1991 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1994 printk("\n=========================================================\n");
1995 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1996 print_kernel_version();
1997 printk( "---------------------------------------------------------\n");
1998 printk("%s/%d just changed the state of lock:\n",
1999 curr->comm, task_pid_nr(curr));
2002 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2004 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2005 print_lock_name(other->class);
2006 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2008 printk("\nother info that might help us debug this:\n");
2009 lockdep_print_held_locks(curr);
2011 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2012 if (!save_trace(&root->trace))
2014 print_shortest_lock_dependencies(other, root);
2016 printk("\nstack backtrace:\n");
2023 * Prove that in the forwards-direction subgraph starting at <this>
2024 * there is no lock matching <mask>:
2027 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2028 enum lock_usage_bit bit, const char *irqclass)
2031 struct lock_list root;
2032 struct lock_list *uninitialized_var(target_entry);
2035 root.class = hlock_class(this);
2036 ret = find_usage_forwards(&root, bit, &target_entry);
2037 BFS_PROCESS_RET(ret);
2039 return print_irq_inversion_bug(curr, &root, target_entry,
2044 * Prove that in the backwards-direction subgraph starting at <this>
2045 * there is no lock matching <mask>:
2048 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2049 enum lock_usage_bit bit, const char *irqclass)
2052 struct lock_list root;
2053 struct lock_list *uninitialized_var(target_entry);
2056 root.class = hlock_class(this);
2057 ret = find_usage_backwards(&root, bit, &target_entry);
2058 BFS_PROCESS_RET(ret);
2060 return print_irq_inversion_bug(curr, &root, target_entry,
2064 void print_irqtrace_events(struct task_struct *curr)
2066 printk("irq event stamp: %u\n", curr->irq_events);
2067 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2068 print_ip_sym(curr->hardirq_enable_ip);
2069 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2070 print_ip_sym(curr->hardirq_disable_ip);
2071 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2072 print_ip_sym(curr->softirq_enable_ip);
2073 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2074 print_ip_sym(curr->softirq_disable_ip);
2077 static int HARDIRQ_verbose(struct lock_class *class)
2080 return class_filter(class);
2085 static int SOFTIRQ_verbose(struct lock_class *class)
2088 return class_filter(class);
2093 static int RECLAIM_FS_verbose(struct lock_class *class)
2096 return class_filter(class);
2101 #define STRICT_READ_CHECKS 1
2103 static int (*state_verbose_f[])(struct lock_class *class) = {
2104 #define LOCKDEP_STATE(__STATE) \
2106 #include "lockdep_states.h"
2107 #undef LOCKDEP_STATE
2110 static inline int state_verbose(enum lock_usage_bit bit,
2111 struct lock_class *class)
2113 return state_verbose_f[bit >> 2](class);
2116 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2117 enum lock_usage_bit bit, const char *name);
2120 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2121 enum lock_usage_bit new_bit)
2123 int excl_bit = exclusive_bit(new_bit);
2124 int read = new_bit & 1;
2125 int dir = new_bit & 2;
2128 * mark USED_IN has to look forwards -- to ensure no dependency
2129 * has ENABLED state, which would allow recursion deadlocks.
2131 * mark ENABLED has to look backwards -- to ensure no dependee
2132 * has USED_IN state, which, again, would allow recursion deadlocks.
2134 check_usage_f usage = dir ?
2135 check_usage_backwards : check_usage_forwards;
2138 * Validate that this particular lock does not have conflicting
2141 if (!valid_state(curr, this, new_bit, excl_bit))
2145 * Validate that the lock dependencies don't have conflicting usage
2148 if ((!read || !dir || STRICT_READ_CHECKS) &&
2149 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2153 * Check for read in write conflicts
2156 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2159 if (STRICT_READ_CHECKS &&
2160 !usage(curr, this, excl_bit + 1,
2161 state_name(new_bit + 1)))
2165 if (state_verbose(new_bit, hlock_class(this)))
2172 #define LOCKDEP_STATE(__STATE) __STATE,
2173 #include "lockdep_states.h"
2174 #undef LOCKDEP_STATE
2178 * Mark all held locks with a usage bit:
2181 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2183 enum lock_usage_bit usage_bit;
2184 struct held_lock *hlock;
2187 for (i = 0; i < curr->lockdep_depth; i++) {
2188 hlock = curr->held_locks + i;
2190 usage_bit = 2 + (mark << 2); /* ENABLED */
2192 usage_bit += 1; /* READ */
2194 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2196 if (!mark_lock(curr, hlock, usage_bit))
2204 * Debugging helper: via this flag we know that we are in
2205 * 'early bootup code', and will warn about any invalid irqs-on event:
2207 static int early_boot_irqs_enabled;
2209 void early_boot_irqs_off(void)
2211 early_boot_irqs_enabled = 0;
2214 void early_boot_irqs_on(void)
2216 early_boot_irqs_enabled = 1;
2220 * Hardirqs will be enabled:
2222 void trace_hardirqs_on_caller(unsigned long ip)
2224 struct task_struct *curr = current;
2226 time_hardirqs_on(CALLER_ADDR0, ip);
2228 if (unlikely(!debug_locks || current->lockdep_recursion))
2231 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2234 if (unlikely(curr->hardirqs_enabled)) {
2235 debug_atomic_inc(&redundant_hardirqs_on);
2238 /* we'll do an OFF -> ON transition: */
2239 curr->hardirqs_enabled = 1;
2241 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2243 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2246 * We are going to turn hardirqs on, so set the
2247 * usage bit for all held locks:
2249 if (!mark_held_locks(curr, HARDIRQ))
2252 * If we have softirqs enabled, then set the usage
2253 * bit for all held locks. (disabled hardirqs prevented
2254 * this bit from being set before)
2256 if (curr->softirqs_enabled)
2257 if (!mark_held_locks(curr, SOFTIRQ))
2260 curr->hardirq_enable_ip = ip;
2261 curr->hardirq_enable_event = ++curr->irq_events;
2262 debug_atomic_inc(&hardirqs_on_events);
2264 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2266 void trace_hardirqs_on(void)
2268 trace_hardirqs_on_caller(CALLER_ADDR0);
2270 EXPORT_SYMBOL(trace_hardirqs_on);
2273 * Hardirqs were disabled:
2275 void trace_hardirqs_off_caller(unsigned long ip)
2277 struct task_struct *curr = current;
2279 time_hardirqs_off(CALLER_ADDR0, ip);
2281 if (unlikely(!debug_locks || current->lockdep_recursion))
2284 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2287 if (curr->hardirqs_enabled) {
2289 * We have done an ON -> OFF transition:
2291 curr->hardirqs_enabled = 0;
2292 curr->hardirq_disable_ip = ip;
2293 curr->hardirq_disable_event = ++curr->irq_events;
2294 debug_atomic_inc(&hardirqs_off_events);
2296 debug_atomic_inc(&redundant_hardirqs_off);
2298 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2300 void trace_hardirqs_off(void)
2302 trace_hardirqs_off_caller(CALLER_ADDR0);
2304 EXPORT_SYMBOL(trace_hardirqs_off);
2307 * Softirqs will be enabled:
2309 void trace_softirqs_on(unsigned long ip)
2311 struct task_struct *curr = current;
2313 if (unlikely(!debug_locks))
2316 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2319 if (curr->softirqs_enabled) {
2320 debug_atomic_inc(&redundant_softirqs_on);
2325 * We'll do an OFF -> ON transition:
2327 curr->softirqs_enabled = 1;
2328 curr->softirq_enable_ip = ip;
2329 curr->softirq_enable_event = ++curr->irq_events;
2330 debug_atomic_inc(&softirqs_on_events);
2332 * We are going to turn softirqs on, so set the
2333 * usage bit for all held locks, if hardirqs are
2336 if (curr->hardirqs_enabled)
2337 mark_held_locks(curr, SOFTIRQ);
2341 * Softirqs were disabled:
2343 void trace_softirqs_off(unsigned long ip)
2345 struct task_struct *curr = current;
2347 if (unlikely(!debug_locks))
2350 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2353 if (curr->softirqs_enabled) {
2355 * We have done an ON -> OFF transition:
2357 curr->softirqs_enabled = 0;
2358 curr->softirq_disable_ip = ip;
2359 curr->softirq_disable_event = ++curr->irq_events;
2360 debug_atomic_inc(&softirqs_off_events);
2361 DEBUG_LOCKS_WARN_ON(!softirq_count());
2363 debug_atomic_inc(&redundant_softirqs_off);
2366 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2368 struct task_struct *curr = current;
2370 if (unlikely(!debug_locks))
2373 /* no reclaim without waiting on it */
2374 if (!(gfp_mask & __GFP_WAIT))
2377 /* this guy won't enter reclaim */
2378 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2381 /* We're only interested __GFP_FS allocations for now */
2382 if (!(gfp_mask & __GFP_FS))
2385 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2388 mark_held_locks(curr, RECLAIM_FS);
2391 static void check_flags(unsigned long flags);
2393 void lockdep_trace_alloc(gfp_t gfp_mask)
2395 unsigned long flags;
2397 if (unlikely(current->lockdep_recursion))
2400 raw_local_irq_save(flags);
2402 current->lockdep_recursion = 1;
2403 __lockdep_trace_alloc(gfp_mask, flags);
2404 current->lockdep_recursion = 0;
2405 raw_local_irq_restore(flags);
2408 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2411 * If non-trylock use in a hardirq or softirq context, then
2412 * mark the lock as used in these contexts:
2414 if (!hlock->trylock) {
2416 if (curr->hardirq_context)
2417 if (!mark_lock(curr, hlock,
2418 LOCK_USED_IN_HARDIRQ_READ))
2420 if (curr->softirq_context)
2421 if (!mark_lock(curr, hlock,
2422 LOCK_USED_IN_SOFTIRQ_READ))
2425 if (curr->hardirq_context)
2426 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2428 if (curr->softirq_context)
2429 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2433 if (!hlock->hardirqs_off) {
2435 if (!mark_lock(curr, hlock,
2436 LOCK_ENABLED_HARDIRQ_READ))
2438 if (curr->softirqs_enabled)
2439 if (!mark_lock(curr, hlock,
2440 LOCK_ENABLED_SOFTIRQ_READ))
2443 if (!mark_lock(curr, hlock,
2444 LOCK_ENABLED_HARDIRQ))
2446 if (curr->softirqs_enabled)
2447 if (!mark_lock(curr, hlock,
2448 LOCK_ENABLED_SOFTIRQ))
2454 * We reuse the irq context infrastructure more broadly as a general
2455 * context checking code. This tests GFP_FS recursion (a lock taken
2456 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2459 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2461 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2464 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2472 static int separate_irq_context(struct task_struct *curr,
2473 struct held_lock *hlock)
2475 unsigned int depth = curr->lockdep_depth;
2478 * Keep track of points where we cross into an interrupt context:
2480 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2481 curr->softirq_context;
2483 struct held_lock *prev_hlock;
2485 prev_hlock = curr->held_locks + depth-1;
2487 * If we cross into another context, reset the
2488 * hash key (this also prevents the checking and the
2489 * adding of the dependency to 'prev'):
2491 if (prev_hlock->irq_context != hlock->irq_context)
2500 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2501 enum lock_usage_bit new_bit)
2507 static inline int mark_irqflags(struct task_struct *curr,
2508 struct held_lock *hlock)
2513 static inline int separate_irq_context(struct task_struct *curr,
2514 struct held_lock *hlock)
2519 void lockdep_trace_alloc(gfp_t gfp_mask)
2526 * Mark a lock with a usage bit, and validate the state transition:
2528 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2529 enum lock_usage_bit new_bit)
2531 unsigned int new_mask = 1 << new_bit, ret = 1;
2534 * If already set then do not dirty the cacheline,
2535 * nor do any checks:
2537 if (likely(hlock_class(this)->usage_mask & new_mask))
2543 * Make sure we didnt race:
2545 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2550 hlock_class(this)->usage_mask |= new_mask;
2552 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2556 #define LOCKDEP_STATE(__STATE) \
2557 case LOCK_USED_IN_##__STATE: \
2558 case LOCK_USED_IN_##__STATE##_READ: \
2559 case LOCK_ENABLED_##__STATE: \
2560 case LOCK_ENABLED_##__STATE##_READ:
2561 #include "lockdep_states.h"
2562 #undef LOCKDEP_STATE
2563 ret = mark_lock_irq(curr, this, new_bit);
2568 debug_atomic_dec(&nr_unused_locks);
2571 if (!debug_locks_off_graph_unlock())
2580 * We must printk outside of the graph_lock:
2583 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2585 print_irqtrace_events(curr);
2593 * Initialize a lock instance's lock-class mapping info:
2595 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2596 struct lock_class_key *key, int subclass)
2598 lock->class_cache = NULL;
2599 #ifdef CONFIG_LOCK_STAT
2600 lock->cpu = raw_smp_processor_id();
2603 if (DEBUG_LOCKS_WARN_ON(!name)) {
2604 lock->name = "NULL";
2610 if (DEBUG_LOCKS_WARN_ON(!key))
2613 * Sanity check, the lock-class key must be persistent:
2615 if (!static_obj(key)) {
2616 printk("BUG: key %p not in .data!\n", key);
2617 DEBUG_LOCKS_WARN_ON(1);
2622 if (unlikely(!debug_locks))
2626 register_lock_class(lock, subclass, 1);
2628 EXPORT_SYMBOL_GPL(lockdep_init_map);
2631 * This gets called for every mutex_lock*()/spin_lock*() operation.
2632 * We maintain the dependency maps and validate the locking attempt:
2634 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2635 int trylock, int read, int check, int hardirqs_off,
2636 struct lockdep_map *nest_lock, unsigned long ip)
2638 struct task_struct *curr = current;
2639 struct lock_class *class = NULL;
2640 struct held_lock *hlock;
2641 unsigned int depth, id;
2648 if (unlikely(!debug_locks))
2651 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2654 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2656 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2657 printk("turning off the locking correctness validator.\n");
2663 class = lock->class_cache;
2665 * Not cached yet or subclass?
2667 if (unlikely(!class)) {
2668 class = register_lock_class(lock, subclass, 0);
2672 debug_atomic_inc((atomic_t *)&class->ops);
2673 if (very_verbose(class)) {
2674 printk("\nacquire class [%p] %s", class->key, class->name);
2675 if (class->name_version > 1)
2676 printk("#%d", class->name_version);
2682 * Add the lock to the list of currently held locks.
2683 * (we dont increase the depth just yet, up until the
2684 * dependency checks are done)
2686 depth = curr->lockdep_depth;
2687 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2690 hlock = curr->held_locks + depth;
2691 if (DEBUG_LOCKS_WARN_ON(!class))
2693 hlock->class_idx = class - lock_classes + 1;
2694 hlock->acquire_ip = ip;
2695 hlock->instance = lock;
2696 hlock->nest_lock = nest_lock;
2697 hlock->trylock = trylock;
2699 hlock->check = check;
2700 hlock->hardirqs_off = !!hardirqs_off;
2701 #ifdef CONFIG_LOCK_STAT
2702 hlock->waittime_stamp = 0;
2703 hlock->holdtime_stamp = sched_clock();
2706 if (check == 2 && !mark_irqflags(curr, hlock))
2709 /* mark it as used: */
2710 if (!mark_lock(curr, hlock, LOCK_USED))
2714 * Calculate the chain hash: it's the combined hash of all the
2715 * lock keys along the dependency chain. We save the hash value
2716 * at every step so that we can get the current hash easily
2717 * after unlock. The chain hash is then used to cache dependency
2720 * The 'key ID' is what is the most compact key value to drive
2721 * the hash, not class->key.
2723 id = class - lock_classes;
2724 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2727 chain_key = curr->curr_chain_key;
2729 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2734 hlock->prev_chain_key = chain_key;
2735 if (separate_irq_context(curr, hlock)) {
2739 chain_key = iterate_chain_key(chain_key, id);
2741 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2744 curr->curr_chain_key = chain_key;
2745 curr->lockdep_depth++;
2746 check_chain_key(curr);
2747 #ifdef CONFIG_DEBUG_LOCKDEP
2748 if (unlikely(!debug_locks))
2751 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2753 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2754 printk("turning off the locking correctness validator.\n");
2759 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2760 max_lockdep_depth = curr->lockdep_depth;
2766 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2769 if (!debug_locks_off())
2771 if (debug_locks_silent)
2774 printk("\n=====================================\n");
2775 printk( "[ BUG: bad unlock balance detected! ]\n");
2776 printk( "-------------------------------------\n");
2777 printk("%s/%d is trying to release lock (",
2778 curr->comm, task_pid_nr(curr));
2779 print_lockdep_cache(lock);
2782 printk("but there are no more locks to release!\n");
2783 printk("\nother info that might help us debug this:\n");
2784 lockdep_print_held_locks(curr);
2786 printk("\nstack backtrace:\n");
2793 * Common debugging checks for both nested and non-nested unlock:
2795 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2798 if (unlikely(!debug_locks))
2800 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2803 if (curr->lockdep_depth <= 0)
2804 return print_unlock_inbalance_bug(curr, lock, ip);
2810 __lock_set_class(struct lockdep_map *lock, const char *name,
2811 struct lock_class_key *key, unsigned int subclass,
2814 struct task_struct *curr = current;
2815 struct held_lock *hlock, *prev_hlock;
2816 struct lock_class *class;
2820 depth = curr->lockdep_depth;
2821 if (DEBUG_LOCKS_WARN_ON(!depth))
2825 for (i = depth-1; i >= 0; i--) {
2826 hlock = curr->held_locks + i;
2828 * We must not cross into another context:
2830 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2832 if (hlock->instance == lock)
2836 return print_unlock_inbalance_bug(curr, lock, ip);
2839 lockdep_init_map(lock, name, key, 0);
2840 class = register_lock_class(lock, subclass, 0);
2841 hlock->class_idx = class - lock_classes + 1;
2843 curr->lockdep_depth = i;
2844 curr->curr_chain_key = hlock->prev_chain_key;
2846 for (; i < depth; i++) {
2847 hlock = curr->held_locks + i;
2848 if (!__lock_acquire(hlock->instance,
2849 hlock_class(hlock)->subclass, hlock->trylock,
2850 hlock->read, hlock->check, hlock->hardirqs_off,
2851 hlock->nest_lock, hlock->acquire_ip))
2855 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2861 * Remove the lock to the list of currently held locks in a
2862 * potentially non-nested (out of order) manner. This is a
2863 * relatively rare operation, as all the unlock APIs default
2864 * to nested mode (which uses lock_release()):
2867 lock_release_non_nested(struct task_struct *curr,
2868 struct lockdep_map *lock, unsigned long ip)
2870 struct held_lock *hlock, *prev_hlock;
2875 * Check whether the lock exists in the current stack
2878 depth = curr->lockdep_depth;
2879 if (DEBUG_LOCKS_WARN_ON(!depth))
2883 for (i = depth-1; i >= 0; i--) {
2884 hlock = curr->held_locks + i;
2886 * We must not cross into another context:
2888 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2890 if (hlock->instance == lock)
2894 return print_unlock_inbalance_bug(curr, lock, ip);
2897 lock_release_holdtime(hlock);
2900 * We have the right lock to unlock, 'hlock' points to it.
2901 * Now we remove it from the stack, and add back the other
2902 * entries (if any), recalculating the hash along the way:
2904 curr->lockdep_depth = i;
2905 curr->curr_chain_key = hlock->prev_chain_key;
2907 for (i++; i < depth; i++) {
2908 hlock = curr->held_locks + i;
2909 if (!__lock_acquire(hlock->instance,
2910 hlock_class(hlock)->subclass, hlock->trylock,
2911 hlock->read, hlock->check, hlock->hardirqs_off,
2912 hlock->nest_lock, hlock->acquire_ip))
2916 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2922 * Remove the lock to the list of currently held locks - this gets
2923 * called on mutex_unlock()/spin_unlock*() (or on a failed
2924 * mutex_lock_interruptible()). This is done for unlocks that nest
2925 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2927 static int lock_release_nested(struct task_struct *curr,
2928 struct lockdep_map *lock, unsigned long ip)
2930 struct held_lock *hlock;
2934 * Pop off the top of the lock stack:
2936 depth = curr->lockdep_depth - 1;
2937 hlock = curr->held_locks + depth;
2940 * Is the unlock non-nested:
2942 if (hlock->instance != lock)
2943 return lock_release_non_nested(curr, lock, ip);
2944 curr->lockdep_depth--;
2946 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2949 curr->curr_chain_key = hlock->prev_chain_key;
2951 lock_release_holdtime(hlock);
2953 #ifdef CONFIG_DEBUG_LOCKDEP
2954 hlock->prev_chain_key = 0;
2955 hlock->class_idx = 0;
2956 hlock->acquire_ip = 0;
2957 hlock->irq_context = 0;
2963 * Remove the lock to the list of currently held locks - this gets
2964 * called on mutex_unlock()/spin_unlock*() (or on a failed
2965 * mutex_lock_interruptible()). This is done for unlocks that nest
2966 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2969 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2971 struct task_struct *curr = current;
2973 if (!check_unlock(curr, lock, ip))
2977 if (!lock_release_nested(curr, lock, ip))
2980 if (!lock_release_non_nested(curr, lock, ip))
2984 check_chain_key(curr);
2988 * Check whether we follow the irq-flags state precisely:
2990 static void check_flags(unsigned long flags)
2992 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2993 defined(CONFIG_TRACE_IRQFLAGS)
2997 if (irqs_disabled_flags(flags)) {
2998 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
2999 printk("possible reason: unannotated irqs-off.\n");
3002 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3003 printk("possible reason: unannotated irqs-on.\n");
3008 * We dont accurately track softirq state in e.g.
3009 * hardirq contexts (such as on 4KSTACKS), so only
3010 * check if not in hardirq contexts:
3012 if (!hardirq_count()) {
3013 if (softirq_count())
3014 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3016 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3020 print_irqtrace_events(current);
3024 void lock_set_class(struct lockdep_map *lock, const char *name,
3025 struct lock_class_key *key, unsigned int subclass,
3028 unsigned long flags;
3030 if (unlikely(current->lockdep_recursion))
3033 raw_local_irq_save(flags);
3034 current->lockdep_recursion = 1;
3036 if (__lock_set_class(lock, name, key, subclass, ip))
3037 check_chain_key(current);
3038 current->lockdep_recursion = 0;
3039 raw_local_irq_restore(flags);
3041 EXPORT_SYMBOL_GPL(lock_set_class);
3044 * We are not always called with irqs disabled - do that here,
3045 * and also avoid lockdep recursion:
3047 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3048 int trylock, int read, int check,
3049 struct lockdep_map *nest_lock, unsigned long ip)
3051 unsigned long flags;
3053 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3055 if (unlikely(current->lockdep_recursion))
3058 raw_local_irq_save(flags);
3061 current->lockdep_recursion = 1;
3062 __lock_acquire(lock, subclass, trylock, read, check,
3063 irqs_disabled_flags(flags), nest_lock, ip);
3064 current->lockdep_recursion = 0;
3065 raw_local_irq_restore(flags);
3067 EXPORT_SYMBOL_GPL(lock_acquire);
3069 void lock_release(struct lockdep_map *lock, int nested,
3072 unsigned long flags;
3074 trace_lock_release(lock, nested, ip);
3076 if (unlikely(current->lockdep_recursion))
3079 raw_local_irq_save(flags);
3081 current->lockdep_recursion = 1;
3082 __lock_release(lock, nested, ip);
3083 current->lockdep_recursion = 0;
3084 raw_local_irq_restore(flags);
3086 EXPORT_SYMBOL_GPL(lock_release);
3088 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3090 current->lockdep_reclaim_gfp = gfp_mask;
3093 void lockdep_clear_current_reclaim_state(void)
3095 current->lockdep_reclaim_gfp = 0;
3098 #ifdef CONFIG_LOCK_STAT
3100 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3103 if (!debug_locks_off())
3105 if (debug_locks_silent)
3108 printk("\n=================================\n");
3109 printk( "[ BUG: bad contention detected! ]\n");
3110 printk( "---------------------------------\n");
3111 printk("%s/%d is trying to contend lock (",
3112 curr->comm, task_pid_nr(curr));
3113 print_lockdep_cache(lock);
3116 printk("but there are no locks held!\n");
3117 printk("\nother info that might help us debug this:\n");
3118 lockdep_print_held_locks(curr);
3120 printk("\nstack backtrace:\n");
3127 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3129 struct task_struct *curr = current;
3130 struct held_lock *hlock, *prev_hlock;
3131 struct lock_class_stats *stats;
3133 int i, contention_point, contending_point;
3135 depth = curr->lockdep_depth;
3136 if (DEBUG_LOCKS_WARN_ON(!depth))
3140 for (i = depth-1; i >= 0; i--) {
3141 hlock = curr->held_locks + i;
3143 * We must not cross into another context:
3145 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3147 if (hlock->instance == lock)
3151 print_lock_contention_bug(curr, lock, ip);
3155 hlock->waittime_stamp = sched_clock();
3157 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3158 contending_point = lock_point(hlock_class(hlock)->contending_point,
3161 stats = get_lock_stats(hlock_class(hlock));
3162 if (contention_point < LOCKSTAT_POINTS)
3163 stats->contention_point[contention_point]++;
3164 if (contending_point < LOCKSTAT_POINTS)
3165 stats->contending_point[contending_point]++;
3166 if (lock->cpu != smp_processor_id())
3167 stats->bounces[bounce_contended + !!hlock->read]++;
3168 put_lock_stats(stats);
3172 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3174 struct task_struct *curr = current;
3175 struct held_lock *hlock, *prev_hlock;
3176 struct lock_class_stats *stats;
3182 depth = curr->lockdep_depth;
3183 if (DEBUG_LOCKS_WARN_ON(!depth))
3187 for (i = depth-1; i >= 0; i--) {
3188 hlock = curr->held_locks + i;
3190 * We must not cross into another context:
3192 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3194 if (hlock->instance == lock)
3198 print_lock_contention_bug(curr, lock, _RET_IP_);
3202 cpu = smp_processor_id();
3203 if (hlock->waittime_stamp) {
3204 now = sched_clock();
3205 waittime = now - hlock->waittime_stamp;
3206 hlock->holdtime_stamp = now;
3209 trace_lock_acquired(lock, ip, waittime);
3211 stats = get_lock_stats(hlock_class(hlock));
3214 lock_time_inc(&stats->read_waittime, waittime);
3216 lock_time_inc(&stats->write_waittime, waittime);
3218 if (lock->cpu != cpu)
3219 stats->bounces[bounce_acquired + !!hlock->read]++;
3220 put_lock_stats(stats);
3226 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3228 unsigned long flags;
3230 trace_lock_contended(lock, ip);
3232 if (unlikely(!lock_stat))
3235 if (unlikely(current->lockdep_recursion))
3238 raw_local_irq_save(flags);
3240 current->lockdep_recursion = 1;
3241 __lock_contended(lock, ip);
3242 current->lockdep_recursion = 0;
3243 raw_local_irq_restore(flags);
3245 EXPORT_SYMBOL_GPL(lock_contended);
3247 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3249 unsigned long flags;
3251 if (unlikely(!lock_stat))
3254 if (unlikely(current->lockdep_recursion))
3257 raw_local_irq_save(flags);
3259 current->lockdep_recursion = 1;
3260 __lock_acquired(lock, ip);
3261 current->lockdep_recursion = 0;
3262 raw_local_irq_restore(flags);
3264 EXPORT_SYMBOL_GPL(lock_acquired);
3268 * Used by the testsuite, sanitize the validator state
3269 * after a simulated failure:
3272 void lockdep_reset(void)
3274 unsigned long flags;
3277 raw_local_irq_save(flags);
3278 current->curr_chain_key = 0;
3279 current->lockdep_depth = 0;
3280 current->lockdep_recursion = 0;
3281 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3282 nr_hardirq_chains = 0;
3283 nr_softirq_chains = 0;
3284 nr_process_chains = 0;
3286 for (i = 0; i < CHAINHASH_SIZE; i++)
3287 INIT_LIST_HEAD(chainhash_table + i);
3288 raw_local_irq_restore(flags);
3291 static void zap_class(struct lock_class *class)
3296 * Remove all dependencies this lock is
3299 for (i = 0; i < nr_list_entries; i++) {
3300 if (list_entries[i].class == class)
3301 list_del_rcu(&list_entries[i].entry);
3304 * Unhash the class and remove it from the all_lock_classes list:
3306 list_del_rcu(&class->hash_entry);
3307 list_del_rcu(&class->lock_entry);
3312 static inline int within(const void *addr, void *start, unsigned long size)
3314 return addr >= start && addr < start + size;
3317 void lockdep_free_key_range(void *start, unsigned long size)
3319 struct lock_class *class, *next;
3320 struct list_head *head;
3321 unsigned long flags;
3325 raw_local_irq_save(flags);
3326 locked = graph_lock();
3329 * Unhash all classes that were created by this module:
3331 for (i = 0; i < CLASSHASH_SIZE; i++) {
3332 head = classhash_table + i;
3333 if (list_empty(head))
3335 list_for_each_entry_safe(class, next, head, hash_entry) {
3336 if (within(class->key, start, size))
3338 else if (within(class->name, start, size))
3345 raw_local_irq_restore(flags);
3348 void lockdep_reset_lock(struct lockdep_map *lock)
3350 struct lock_class *class, *next;
3351 struct list_head *head;
3352 unsigned long flags;
3356 raw_local_irq_save(flags);
3359 * Remove all classes this lock might have:
3361 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3363 * If the class exists we look it up and zap it:
3365 class = look_up_lock_class(lock, j);
3370 * Debug check: in the end all mapped classes should
3373 locked = graph_lock();
3374 for (i = 0; i < CLASSHASH_SIZE; i++) {
3375 head = classhash_table + i;
3376 if (list_empty(head))
3378 list_for_each_entry_safe(class, next, head, hash_entry) {
3379 if (unlikely(class == lock->class_cache)) {
3380 if (debug_locks_off_graph_unlock())
3390 raw_local_irq_restore(flags);
3393 void lockdep_init(void)
3398 * Some architectures have their own start_kernel()
3399 * code which calls lockdep_init(), while we also
3400 * call lockdep_init() from the start_kernel() itself,
3401 * and we want to initialize the hashes only once:
3403 if (lockdep_initialized)
3406 for (i = 0; i < CLASSHASH_SIZE; i++)
3407 INIT_LIST_HEAD(classhash_table + i);
3409 for (i = 0; i < CHAINHASH_SIZE; i++)
3410 INIT_LIST_HEAD(chainhash_table + i);
3412 lockdep_initialized = 1;
3415 void __init lockdep_info(void)
3417 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3419 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3420 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3421 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3422 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3423 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3424 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3425 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3427 printk(" memory used by lock dependency info: %lu kB\n",
3428 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3429 sizeof(struct list_head) * CLASSHASH_SIZE +
3430 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3431 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3432 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024
3433 #ifdef CONFIG_PROVE_LOCKING
3434 + sizeof(struct circular_queue) + sizeof(bfs_accessed)
3438 printk(" per task-struct memory footprint: %lu bytes\n",
3439 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3441 #ifdef CONFIG_DEBUG_LOCKDEP
3442 if (lockdep_init_error) {
3443 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3444 printk("Call stack leading to lockdep invocation was:\n");
3445 print_stack_trace(&lockdep_init_trace, 0);
3451 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3452 const void *mem_to, struct held_lock *hlock)
3454 if (!debug_locks_off())
3456 if (debug_locks_silent)
3459 printk("\n=========================\n");
3460 printk( "[ BUG: held lock freed! ]\n");
3461 printk( "-------------------------\n");
3462 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3463 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3465 lockdep_print_held_locks(curr);
3467 printk("\nstack backtrace:\n");
3471 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3472 const void* lock_from, unsigned long lock_len)
3474 return lock_from + lock_len <= mem_from ||
3475 mem_from + mem_len <= lock_from;
3479 * Called when kernel memory is freed (or unmapped), or if a lock
3480 * is destroyed or reinitialized - this code checks whether there is
3481 * any held lock in the memory range of <from> to <to>:
3483 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3485 struct task_struct *curr = current;
3486 struct held_lock *hlock;
3487 unsigned long flags;
3490 if (unlikely(!debug_locks))
3493 local_irq_save(flags);
3494 for (i = 0; i < curr->lockdep_depth; i++) {
3495 hlock = curr->held_locks + i;
3497 if (not_in_range(mem_from, mem_len, hlock->instance,
3498 sizeof(*hlock->instance)))
3501 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3504 local_irq_restore(flags);
3506 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3508 static void print_held_locks_bug(struct task_struct *curr)
3510 if (!debug_locks_off())
3512 if (debug_locks_silent)
3515 printk("\n=====================================\n");
3516 printk( "[ BUG: lock held at task exit time! ]\n");
3517 printk( "-------------------------------------\n");
3518 printk("%s/%d is exiting with locks still held!\n",
3519 curr->comm, task_pid_nr(curr));
3520 lockdep_print_held_locks(curr);
3522 printk("\nstack backtrace:\n");
3526 void debug_check_no_locks_held(struct task_struct *task)
3528 if (unlikely(task->lockdep_depth > 0))
3529 print_held_locks_bug(task);
3532 void debug_show_all_locks(void)
3534 struct task_struct *g, *p;
3538 if (unlikely(!debug_locks)) {
3539 printk("INFO: lockdep is turned off.\n");
3542 printk("\nShowing all locks held in the system:\n");
3545 * Here we try to get the tasklist_lock as hard as possible,
3546 * if not successful after 2 seconds we ignore it (but keep
3547 * trying). This is to enable a debug printout even if a
3548 * tasklist_lock-holding task deadlocks or crashes.
3551 if (!read_trylock(&tasklist_lock)) {
3553 printk("hm, tasklist_lock locked, retrying... ");
3556 printk(" #%d", 10-count);
3560 printk(" ignoring it.\n");
3564 printk(KERN_CONT " locked it.\n");
3567 do_each_thread(g, p) {
3569 * It's not reliable to print a task's held locks
3570 * if it's not sleeping (or if it's not the current
3573 if (p->state == TASK_RUNNING && p != current)
3575 if (p->lockdep_depth)
3576 lockdep_print_held_locks(p);
3578 if (read_trylock(&tasklist_lock))
3580 } while_each_thread(g, p);
3583 printk("=============================================\n\n");
3586 read_unlock(&tasklist_lock);
3588 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3591 * Careful: only use this function if you are sure that
3592 * the task cannot run in parallel!
3594 void __debug_show_held_locks(struct task_struct *task)
3596 if (unlikely(!debug_locks)) {
3597 printk("INFO: lockdep is turned off.\n");
3600 lockdep_print_held_locks(task);
3602 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3604 void debug_show_held_locks(struct task_struct *task)
3606 __debug_show_held_locks(task);
3608 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3610 void lockdep_sys_exit(void)
3612 struct task_struct *curr = current;
3614 if (unlikely(curr->lockdep_depth)) {
3615 if (!debug_locks_off())
3617 printk("\n================================================\n");
3618 printk( "[ BUG: lock held when returning to user space! ]\n");
3619 printk( "------------------------------------------------\n");
3620 printk("%s/%d is leaving the kernel with locks still held!\n",
3621 curr->comm, curr->pid);
3622 lockdep_print_held_locks(curr);