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>
47 #include <asm/sections.h>
49 #include "lockdep_internals.h"
51 #define CREATE_TRACE_POINTS
52 #include <trace/events/lock.h>
54 #ifdef CONFIG_PROVE_LOCKING
55 int prove_locking = 1;
56 module_param(prove_locking, int, 0644);
58 #define prove_locking 0
61 #ifdef CONFIG_LOCK_STAT
63 module_param(lock_stat, int, 0644);
69 * lockdep_lock: protects the lockdep graph, the hashes and the
70 * class/list/hash allocators.
72 * This is one of the rare exceptions where it's justified
73 * to use a raw spinlock - we really dont want the spinlock
74 * code to recurse back into the lockdep code...
76 static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
78 static int graph_lock(void)
80 __raw_spin_lock(&lockdep_lock);
82 * Make sure that if another CPU detected a bug while
83 * walking the graph we dont change it (while the other
84 * CPU is busy printing out stuff with the graph lock
88 __raw_spin_unlock(&lockdep_lock);
91 /* prevent any recursions within lockdep from causing deadlocks */
92 current->lockdep_recursion++;
96 static inline int graph_unlock(void)
98 if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
99 return DEBUG_LOCKS_WARN_ON(1);
101 current->lockdep_recursion--;
102 __raw_spin_unlock(&lockdep_lock);
107 * Turn lock debugging off and return with 0 if it was off already,
108 * and also release the graph lock:
110 static inline int debug_locks_off_graph_unlock(void)
112 int ret = debug_locks_off();
114 __raw_spin_unlock(&lockdep_lock);
119 static int lockdep_initialized;
121 unsigned long nr_list_entries;
122 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
125 * All data structures here are protected by the global debug_lock.
127 * Mutex key structs only get allocated, once during bootup, and never
128 * get freed - this significantly simplifies the debugging code.
130 unsigned long nr_lock_classes;
131 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
133 static inline struct lock_class *hlock_class(struct held_lock *hlock)
135 if (!hlock->class_idx) {
136 DEBUG_LOCKS_WARN_ON(1);
139 return lock_classes + hlock->class_idx - 1;
142 #ifdef CONFIG_LOCK_STAT
143 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
145 static inline u64 lockstat_clock(void)
147 return cpu_clock(smp_processor_id());
150 static int lock_point(unsigned long points[], unsigned long ip)
154 for (i = 0; i < LOCKSTAT_POINTS; i++) {
155 if (points[i] == 0) {
166 static void lock_time_inc(struct lock_time *lt, u64 time)
171 if (time < lt->min || !lt->nr)
178 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
183 if (src->max > dst->max)
186 if (src->min < dst->min || !dst->nr)
189 dst->total += src->total;
193 struct lock_class_stats lock_stats(struct lock_class *class)
195 struct lock_class_stats stats;
198 memset(&stats, 0, sizeof(struct lock_class_stats));
199 for_each_possible_cpu(cpu) {
200 struct lock_class_stats *pcs =
201 &per_cpu(lock_stats, cpu)[class - lock_classes];
203 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
204 stats.contention_point[i] += pcs->contention_point[i];
206 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
207 stats.contending_point[i] += pcs->contending_point[i];
209 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
210 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
212 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
213 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
215 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
216 stats.bounces[i] += pcs->bounces[i];
222 void clear_lock_stats(struct lock_class *class)
226 for_each_possible_cpu(cpu) {
227 struct lock_class_stats *cpu_stats =
228 &per_cpu(lock_stats, cpu)[class - lock_classes];
230 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
232 memset(class->contention_point, 0, sizeof(class->contention_point));
233 memset(class->contending_point, 0, sizeof(class->contending_point));
236 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
238 return &get_cpu_var(lock_stats)[class - lock_classes];
241 static void put_lock_stats(struct lock_class_stats *stats)
243 put_cpu_var(lock_stats);
246 static void lock_release_holdtime(struct held_lock *hlock)
248 struct lock_class_stats *stats;
254 holdtime = lockstat_clock() - hlock->holdtime_stamp;
256 stats = get_lock_stats(hlock_class(hlock));
258 lock_time_inc(&stats->read_holdtime, holdtime);
260 lock_time_inc(&stats->write_holdtime, holdtime);
261 put_lock_stats(stats);
264 static inline void lock_release_holdtime(struct held_lock *hlock)
270 * We keep a global list of all lock classes. The list only grows,
271 * never shrinks. The list is only accessed with the lockdep
272 * spinlock lock held.
274 LIST_HEAD(all_lock_classes);
277 * The lockdep classes are in a hash-table as well, for fast lookup:
279 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
280 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
281 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
282 #define classhashentry(key) (classhash_table + __classhashfn((key)))
284 static struct list_head classhash_table[CLASSHASH_SIZE];
287 * We put the lock dependency chains into a hash-table as well, to cache
290 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
291 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
292 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
293 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
295 static struct list_head chainhash_table[CHAINHASH_SIZE];
298 * The hash key of the lock dependency chains is a hash itself too:
299 * it's a hash of all locks taken up to that lock, including that lock.
300 * It's a 64-bit hash, because it's important for the keys to be
303 #define iterate_chain_key(key1, key2) \
304 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
305 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
308 void lockdep_off(void)
310 current->lockdep_recursion++;
312 EXPORT_SYMBOL(lockdep_off);
314 void lockdep_on(void)
316 current->lockdep_recursion--;
318 EXPORT_SYMBOL(lockdep_on);
321 * Debugging switches:
325 #define VERY_VERBOSE 0
328 # define HARDIRQ_VERBOSE 1
329 # define SOFTIRQ_VERBOSE 1
330 # define RECLAIM_VERBOSE 1
332 # define HARDIRQ_VERBOSE 0
333 # define SOFTIRQ_VERBOSE 0
334 # define RECLAIM_VERBOSE 0
337 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
339 * Quick filtering for interesting events:
341 static int class_filter(struct lock_class *class)
345 if (class->name_version == 1 &&
346 !strcmp(class->name, "lockname"))
348 if (class->name_version == 1 &&
349 !strcmp(class->name, "&struct->lockfield"))
352 /* Filter everything else. 1 would be to allow everything else */
357 static int verbose(struct lock_class *class)
360 return class_filter(class);
366 * Stack-trace: tightly packed array of stack backtrace
367 * addresses. Protected by the graph_lock.
369 unsigned long nr_stack_trace_entries;
370 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
372 static int save_trace(struct stack_trace *trace)
374 trace->nr_entries = 0;
375 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
376 trace->entries = stack_trace + nr_stack_trace_entries;
380 save_stack_trace(trace);
383 * Some daft arches put -1 at the end to indicate its a full trace.
385 * <rant> this is buggy anyway, since it takes a whole extra entry so a
386 * complete trace that maxes out the entries provided will be reported
387 * as incomplete, friggin useless </rant>
389 if (trace->entries[trace->nr_entries-1] == ULONG_MAX)
392 trace->max_entries = trace->nr_entries;
394 nr_stack_trace_entries += trace->nr_entries;
396 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
397 if (!debug_locks_off_graph_unlock())
400 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
401 printk("turning off the locking correctness validator.\n");
410 unsigned int nr_hardirq_chains;
411 unsigned int nr_softirq_chains;
412 unsigned int nr_process_chains;
413 unsigned int max_lockdep_depth;
415 #ifdef CONFIG_DEBUG_LOCKDEP
417 * We cannot printk in early bootup code. Not even early_printk()
418 * might work. So we mark any initialization errors and printk
419 * about it later on, in lockdep_info().
421 static int lockdep_init_error;
422 static unsigned long lockdep_init_trace_data[20];
423 static struct stack_trace lockdep_init_trace = {
424 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
425 .entries = lockdep_init_trace_data,
429 * Various lockdep statistics:
431 atomic_t chain_lookup_hits;
432 atomic_t chain_lookup_misses;
433 atomic_t hardirqs_on_events;
434 atomic_t hardirqs_off_events;
435 atomic_t redundant_hardirqs_on;
436 atomic_t redundant_hardirqs_off;
437 atomic_t softirqs_on_events;
438 atomic_t softirqs_off_events;
439 atomic_t redundant_softirqs_on;
440 atomic_t redundant_softirqs_off;
441 atomic_t nr_unused_locks;
442 atomic_t nr_cyclic_checks;
443 atomic_t nr_find_usage_forwards_checks;
444 atomic_t nr_find_usage_backwards_checks;
451 #define __USAGE(__STATE) \
452 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
453 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
454 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
455 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
457 static const char *usage_str[] =
459 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
460 #include "lockdep_states.h"
462 [LOCK_USED] = "INITIAL USE",
465 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
467 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
470 static inline unsigned long lock_flag(enum lock_usage_bit bit)
475 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
479 if (class->usage_mask & lock_flag(bit + 2))
481 if (class->usage_mask & lock_flag(bit)) {
483 if (class->usage_mask & lock_flag(bit + 2))
490 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
494 #define LOCKDEP_STATE(__STATE) \
495 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
496 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
497 #include "lockdep_states.h"
503 static void print_lock_name(struct lock_class *class)
505 char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
508 get_usage_chars(class, usage);
512 name = __get_key_name(class->key, str);
513 printk(" (%s", name);
515 printk(" (%s", name);
516 if (class->name_version > 1)
517 printk("#%d", class->name_version);
519 printk("/%d", class->subclass);
521 printk("){%s}", usage);
524 static void print_lockdep_cache(struct lockdep_map *lock)
527 char str[KSYM_NAME_LEN];
531 name = __get_key_name(lock->key->subkeys, str);
536 static void print_lock(struct held_lock *hlock)
538 print_lock_name(hlock_class(hlock));
540 print_ip_sym(hlock->acquire_ip);
543 static void lockdep_print_held_locks(struct task_struct *curr)
545 int i, depth = curr->lockdep_depth;
548 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
551 printk("%d lock%s held by %s/%d:\n",
552 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
554 for (i = 0; i < depth; i++) {
556 print_lock(curr->held_locks + i);
560 static void print_kernel_version(void)
562 printk("%s %.*s\n", init_utsname()->release,
563 (int)strcspn(init_utsname()->version, " "),
564 init_utsname()->version);
567 static int very_verbose(struct lock_class *class)
570 return class_filter(class);
576 * Is this the address of a static object:
578 static int static_obj(void *obj)
580 unsigned long start = (unsigned long) &_stext,
581 end = (unsigned long) &_end,
582 addr = (unsigned long) obj;
590 if ((addr >= start) && (addr < end))
593 if (arch_is_kernel_data(addr))
600 for_each_possible_cpu(i) {
601 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
602 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
605 if ((addr >= start) && (addr < end))
613 return is_module_address(addr);
617 * To make lock name printouts unique, we calculate a unique
618 * class->name_version generation counter:
620 static int count_matching_names(struct lock_class *new_class)
622 struct lock_class *class;
625 if (!new_class->name)
628 list_for_each_entry(class, &all_lock_classes, lock_entry) {
629 if (new_class->key - new_class->subclass == class->key)
630 return class->name_version;
631 if (class->name && !strcmp(class->name, new_class->name))
632 count = max(count, class->name_version);
639 * Register a lock's class in the hash-table, if the class is not present
640 * yet. Otherwise we look it up. We cache the result in the lock object
641 * itself, so actual lookup of the hash should be once per lock object.
643 static inline struct lock_class *
644 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
646 struct lockdep_subclass_key *key;
647 struct list_head *hash_head;
648 struct lock_class *class;
650 #ifdef CONFIG_DEBUG_LOCKDEP
652 * If the architecture calls into lockdep before initializing
653 * the hashes then we'll warn about it later. (we cannot printk
656 if (unlikely(!lockdep_initialized)) {
658 lockdep_init_error = 1;
659 save_stack_trace(&lockdep_init_trace);
664 * Static locks do not have their class-keys yet - for them the key
665 * is the lock object itself:
667 if (unlikely(!lock->key))
668 lock->key = (void *)lock;
671 * NOTE: the class-key must be unique. For dynamic locks, a static
672 * lock_class_key variable is passed in through the mutex_init()
673 * (or spin_lock_init()) call - which acts as the key. For static
674 * locks we use the lock object itself as the key.
676 BUILD_BUG_ON(sizeof(struct lock_class_key) >
677 sizeof(struct lockdep_map));
679 key = lock->key->subkeys + subclass;
681 hash_head = classhashentry(key);
684 * We can walk the hash lockfree, because the hash only
685 * grows, and we are careful when adding entries to the end:
687 list_for_each_entry(class, hash_head, hash_entry) {
688 if (class->key == key) {
689 WARN_ON_ONCE(class->name != lock->name);
698 * Register a lock's class in the hash-table, if the class is not present
699 * yet. Otherwise we look it up. We cache the result in the lock object
700 * itself, so actual lookup of the hash should be once per lock object.
702 static inline struct lock_class *
703 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
705 struct lockdep_subclass_key *key;
706 struct list_head *hash_head;
707 struct lock_class *class;
710 class = look_up_lock_class(lock, subclass);
715 * Debug-check: all keys must be persistent!
717 if (!static_obj(lock->key)) {
719 printk("INFO: trying to register non-static key.\n");
720 printk("the code is fine but needs lockdep annotation.\n");
721 printk("turning off the locking correctness validator.\n");
727 key = lock->key->subkeys + subclass;
728 hash_head = classhashentry(key);
730 raw_local_irq_save(flags);
732 raw_local_irq_restore(flags);
736 * We have to do the hash-walk again, to avoid races
739 list_for_each_entry(class, hash_head, hash_entry)
740 if (class->key == key)
743 * Allocate a new key from the static array, and add it to
746 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
747 if (!debug_locks_off_graph_unlock()) {
748 raw_local_irq_restore(flags);
751 raw_local_irq_restore(flags);
753 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
754 printk("turning off the locking correctness validator.\n");
758 class = lock_classes + nr_lock_classes++;
759 debug_atomic_inc(&nr_unused_locks);
761 class->name = lock->name;
762 class->subclass = subclass;
763 INIT_LIST_HEAD(&class->lock_entry);
764 INIT_LIST_HEAD(&class->locks_before);
765 INIT_LIST_HEAD(&class->locks_after);
766 class->name_version = count_matching_names(class);
768 * We use RCU's safe list-add method to make
769 * parallel walking of the hash-list safe:
771 list_add_tail_rcu(&class->hash_entry, hash_head);
773 * Add it to the global list of classes:
775 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
777 if (verbose(class)) {
779 raw_local_irq_restore(flags);
781 printk("\nnew class %p: %s", class->key, class->name);
782 if (class->name_version > 1)
783 printk("#%d", class->name_version);
787 raw_local_irq_save(flags);
789 raw_local_irq_restore(flags);
795 raw_local_irq_restore(flags);
797 if (!subclass || force)
798 lock->class_cache = class;
800 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
806 #ifdef CONFIG_PROVE_LOCKING
808 * Allocate a lockdep entry. (assumes the graph_lock held, returns
809 * with NULL on failure)
811 static struct lock_list *alloc_list_entry(void)
813 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
814 if (!debug_locks_off_graph_unlock())
817 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
818 printk("turning off the locking correctness validator.\n");
822 return list_entries + nr_list_entries++;
826 * Add a new dependency to the head of the list:
828 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
829 struct list_head *head, unsigned long ip, int distance)
831 struct lock_list *entry;
833 * Lock not present yet - get a new dependency struct and
834 * add it to the list:
836 entry = alloc_list_entry();
840 if (!save_trace(&entry->trace))
844 entry->distance = distance;
846 * Since we never remove from the dependency list, the list can
847 * be walked lockless by other CPUs, it's only allocation
848 * that must be protected by the spinlock. But this also means
849 * we must make new entries visible only once writes to the
850 * entry become visible - hence the RCU op:
852 list_add_tail_rcu(&entry->entry, head);
858 * For good efficiency of modular, we use power of 2
860 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
861 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
864 * The circular_queue and helpers is used to implement the
865 * breadth-first search(BFS)algorithem, by which we can build
866 * the shortest path from the next lock to be acquired to the
867 * previous held lock if there is a circular between them.
869 struct circular_queue {
870 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
871 unsigned int front, rear;
874 static struct circular_queue lock_cq;
876 unsigned int max_bfs_queue_depth;
878 static unsigned int lockdep_dependency_gen_id;
880 static inline void __cq_init(struct circular_queue *cq)
882 cq->front = cq->rear = 0;
883 lockdep_dependency_gen_id++;
886 static inline int __cq_empty(struct circular_queue *cq)
888 return (cq->front == cq->rear);
891 static inline int __cq_full(struct circular_queue *cq)
893 return ((cq->rear + 1) & CQ_MASK) == cq->front;
896 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
901 cq->element[cq->rear] = elem;
902 cq->rear = (cq->rear + 1) & CQ_MASK;
906 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
911 *elem = cq->element[cq->front];
912 cq->front = (cq->front + 1) & CQ_MASK;
916 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
918 return (cq->rear - cq->front) & CQ_MASK;
921 static inline void mark_lock_accessed(struct lock_list *lock,
922 struct lock_list *parent)
926 nr = lock - list_entries;
927 WARN_ON(nr >= nr_list_entries);
928 lock->parent = parent;
929 lock->class->dep_gen_id = lockdep_dependency_gen_id;
932 static inline unsigned long lock_accessed(struct lock_list *lock)
936 nr = lock - list_entries;
937 WARN_ON(nr >= nr_list_entries);
938 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
941 static inline struct lock_list *get_lock_parent(struct lock_list *child)
943 return child->parent;
946 static inline int get_lock_depth(struct lock_list *child)
949 struct lock_list *parent;
951 while ((parent = get_lock_parent(child))) {
958 static int __bfs(struct lock_list *source_entry,
960 int (*match)(struct lock_list *entry, void *data),
961 struct lock_list **target_entry,
964 struct lock_list *entry;
965 struct list_head *head;
966 struct circular_queue *cq = &lock_cq;
969 if (match(source_entry, data)) {
970 *target_entry = source_entry;
976 head = &source_entry->class->locks_after;
978 head = &source_entry->class->locks_before;
980 if (list_empty(head))
984 __cq_enqueue(cq, (unsigned long)source_entry);
986 while (!__cq_empty(cq)) {
987 struct lock_list *lock;
989 __cq_dequeue(cq, (unsigned long *)&lock);
997 head = &lock->class->locks_after;
999 head = &lock->class->locks_before;
1001 list_for_each_entry(entry, head, entry) {
1002 if (!lock_accessed(entry)) {
1003 unsigned int cq_depth;
1004 mark_lock_accessed(entry, lock);
1005 if (match(entry, data)) {
1006 *target_entry = entry;
1011 if (__cq_enqueue(cq, (unsigned long)entry)) {
1015 cq_depth = __cq_get_elem_count(cq);
1016 if (max_bfs_queue_depth < cq_depth)
1017 max_bfs_queue_depth = cq_depth;
1025 static inline int __bfs_forwards(struct lock_list *src_entry,
1027 int (*match)(struct lock_list *entry, void *data),
1028 struct lock_list **target_entry)
1030 return __bfs(src_entry, data, match, target_entry, 1);
1034 static inline int __bfs_backwards(struct lock_list *src_entry,
1036 int (*match)(struct lock_list *entry, void *data),
1037 struct lock_list **target_entry)
1039 return __bfs(src_entry, data, match, target_entry, 0);
1044 * Recursive, forwards-direction lock-dependency checking, used for
1045 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1050 * Print a dependency chain entry (this is only done when a deadlock
1051 * has been detected):
1054 print_circular_bug_entry(struct lock_list *target, int depth)
1056 if (debug_locks_silent)
1058 printk("\n-> #%u", depth);
1059 print_lock_name(target->class);
1061 print_stack_trace(&target->trace, 6);
1067 * When a circular dependency is detected, print the
1071 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1072 struct held_lock *check_src,
1073 struct held_lock *check_tgt)
1075 struct task_struct *curr = current;
1077 if (debug_locks_silent)
1080 printk("\n=======================================================\n");
1081 printk( "[ INFO: possible circular locking dependency detected ]\n");
1082 print_kernel_version();
1083 printk( "-------------------------------------------------------\n");
1084 printk("%s/%d is trying to acquire lock:\n",
1085 curr->comm, task_pid_nr(curr));
1086 print_lock(check_src);
1087 printk("\nbut task is already holding lock:\n");
1088 print_lock(check_tgt);
1089 printk("\nwhich lock already depends on the new lock.\n\n");
1090 printk("\nthe existing dependency chain (in reverse order) is:\n");
1092 print_circular_bug_entry(entry, depth);
1097 static inline int class_equal(struct lock_list *entry, void *data)
1099 return entry->class == data;
1102 static noinline int print_circular_bug(struct lock_list *this,
1103 struct lock_list *target,
1104 struct held_lock *check_src,
1105 struct held_lock *check_tgt)
1107 struct task_struct *curr = current;
1108 struct lock_list *parent;
1111 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1114 if (!save_trace(&this->trace))
1117 depth = get_lock_depth(target);
1119 print_circular_bug_header(target, depth, check_src, check_tgt);
1121 parent = get_lock_parent(target);
1124 print_circular_bug_entry(parent, --depth);
1125 parent = get_lock_parent(parent);
1128 printk("\nother info that might help us debug this:\n\n");
1129 lockdep_print_held_locks(curr);
1131 printk("\nstack backtrace:\n");
1137 static noinline int print_bfs_bug(int ret)
1139 if (!debug_locks_off_graph_unlock())
1142 WARN(1, "lockdep bfs error:%d\n", ret);
1147 static int noop_count(struct lock_list *entry, void *data)
1149 (*(unsigned long *)data)++;
1153 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1155 unsigned long count = 0;
1156 struct lock_list *uninitialized_var(target_entry);
1158 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1162 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1164 unsigned long ret, flags;
1165 struct lock_list this;
1170 local_irq_save(flags);
1171 __raw_spin_lock(&lockdep_lock);
1172 ret = __lockdep_count_forward_deps(&this);
1173 __raw_spin_unlock(&lockdep_lock);
1174 local_irq_restore(flags);
1179 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1181 unsigned long count = 0;
1182 struct lock_list *uninitialized_var(target_entry);
1184 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1189 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1191 unsigned long ret, flags;
1192 struct lock_list this;
1197 local_irq_save(flags);
1198 __raw_spin_lock(&lockdep_lock);
1199 ret = __lockdep_count_backward_deps(&this);
1200 __raw_spin_unlock(&lockdep_lock);
1201 local_irq_restore(flags);
1207 * Prove that the dependency graph starting at <entry> can not
1208 * lead to <target>. Print an error and return 0 if it does.
1211 check_noncircular(struct lock_list *root, struct lock_class *target,
1212 struct lock_list **target_entry)
1216 debug_atomic_inc(&nr_cyclic_checks);
1218 result = __bfs_forwards(root, target, class_equal, target_entry);
1223 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1225 * Forwards and backwards subgraph searching, for the purposes of
1226 * proving that two subgraphs can be connected by a new dependency
1227 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1230 static inline int usage_match(struct lock_list *entry, void *bit)
1232 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1238 * Find a node in the forwards-direction dependency sub-graph starting
1239 * at @root->class that matches @bit.
1241 * Return 0 if such a node exists in the subgraph, and put that node
1242 * into *@target_entry.
1244 * Return 1 otherwise and keep *@target_entry unchanged.
1245 * Return <0 on error.
1248 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1249 struct lock_list **target_entry)
1253 debug_atomic_inc(&nr_find_usage_forwards_checks);
1255 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1261 * Find a node in the backwards-direction dependency sub-graph starting
1262 * at @root->class that matches @bit.
1264 * Return 0 if such a node exists in the subgraph, and put that node
1265 * into *@target_entry.
1267 * Return 1 otherwise and keep *@target_entry unchanged.
1268 * Return <0 on error.
1271 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1272 struct lock_list **target_entry)
1276 debug_atomic_inc(&nr_find_usage_backwards_checks);
1278 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1283 static void print_lock_class_header(struct lock_class *class, int depth)
1287 printk("%*s->", depth, "");
1288 print_lock_name(class);
1289 printk(" ops: %lu", class->ops);
1292 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1293 if (class->usage_mask & (1 << bit)) {
1296 len += printk("%*s %s", depth, "", usage_str[bit]);
1297 len += printk(" at:\n");
1298 print_stack_trace(class->usage_traces + bit, len);
1301 printk("%*s }\n", depth, "");
1303 printk("%*s ... key at: ",depth,"");
1304 print_ip_sym((unsigned long)class->key);
1308 * printk the shortest lock dependencies from @start to @end in reverse order:
1311 print_shortest_lock_dependencies(struct lock_list *leaf,
1312 struct lock_list *root)
1314 struct lock_list *entry = leaf;
1317 /*compute depth from generated tree by BFS*/
1318 depth = get_lock_depth(leaf);
1321 print_lock_class_header(entry->class, depth);
1322 printk("%*s ... acquired at:\n", depth, "");
1323 print_stack_trace(&entry->trace, 2);
1326 if (depth == 0 && (entry != root)) {
1327 printk("lockdep:%s bad BFS generated tree\n", __func__);
1331 entry = get_lock_parent(entry);
1333 } while (entry && (depth >= 0));
1339 print_bad_irq_dependency(struct task_struct *curr,
1340 struct lock_list *prev_root,
1341 struct lock_list *next_root,
1342 struct lock_list *backwards_entry,
1343 struct lock_list *forwards_entry,
1344 struct held_lock *prev,
1345 struct held_lock *next,
1346 enum lock_usage_bit bit1,
1347 enum lock_usage_bit bit2,
1348 const char *irqclass)
1350 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1353 printk("\n======================================================\n");
1354 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1355 irqclass, irqclass);
1356 print_kernel_version();
1357 printk( "------------------------------------------------------\n");
1358 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1359 curr->comm, task_pid_nr(curr),
1360 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1361 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1362 curr->hardirqs_enabled,
1363 curr->softirqs_enabled);
1366 printk("\nand this task is already holding:\n");
1368 printk("which would create a new lock dependency:\n");
1369 print_lock_name(hlock_class(prev));
1371 print_lock_name(hlock_class(next));
1374 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1376 print_lock_name(backwards_entry->class);
1377 printk("\n... which became %s-irq-safe at:\n", irqclass);
1379 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1381 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1382 print_lock_name(forwards_entry->class);
1383 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1386 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1388 printk("\nother info that might help us debug this:\n\n");
1389 lockdep_print_held_locks(curr);
1391 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1392 printk(" and the holding lock:\n");
1393 if (!save_trace(&prev_root->trace))
1395 print_shortest_lock_dependencies(backwards_entry, prev_root);
1397 printk("\nthe dependencies between the lock to be acquired");
1398 printk(" and %s-irq-unsafe lock:\n", irqclass);
1399 if (!save_trace(&next_root->trace))
1401 print_shortest_lock_dependencies(forwards_entry, next_root);
1403 printk("\nstack backtrace:\n");
1410 check_usage(struct task_struct *curr, struct held_lock *prev,
1411 struct held_lock *next, enum lock_usage_bit bit_backwards,
1412 enum lock_usage_bit bit_forwards, const char *irqclass)
1415 struct lock_list this, that;
1416 struct lock_list *uninitialized_var(target_entry);
1417 struct lock_list *uninitialized_var(target_entry1);
1421 this.class = hlock_class(prev);
1422 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1424 return print_bfs_bug(ret);
1429 that.class = hlock_class(next);
1430 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1432 return print_bfs_bug(ret);
1436 return print_bad_irq_dependency(curr, &this, &that,
1437 target_entry, target_entry1,
1439 bit_backwards, bit_forwards, irqclass);
1442 static const char *state_names[] = {
1443 #define LOCKDEP_STATE(__STATE) \
1444 __stringify(__STATE),
1445 #include "lockdep_states.h"
1446 #undef LOCKDEP_STATE
1449 static const char *state_rnames[] = {
1450 #define LOCKDEP_STATE(__STATE) \
1451 __stringify(__STATE)"-READ",
1452 #include "lockdep_states.h"
1453 #undef LOCKDEP_STATE
1456 static inline const char *state_name(enum lock_usage_bit bit)
1458 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1461 static int exclusive_bit(int new_bit)
1469 * bit 0 - write/read
1470 * bit 1 - used_in/enabled
1474 int state = new_bit & ~3;
1475 int dir = new_bit & 2;
1478 * keep state, bit flip the direction and strip read.
1480 return state | (dir ^ 2);
1483 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1484 struct held_lock *next, enum lock_usage_bit bit)
1487 * Prove that the new dependency does not connect a hardirq-safe
1488 * lock with a hardirq-unsafe lock - to achieve this we search
1489 * the backwards-subgraph starting at <prev>, and the
1490 * forwards-subgraph starting at <next>:
1492 if (!check_usage(curr, prev, next, bit,
1493 exclusive_bit(bit), state_name(bit)))
1499 * Prove that the new dependency does not connect a hardirq-safe-read
1500 * lock with a hardirq-unsafe lock - to achieve this we search
1501 * the backwards-subgraph starting at <prev>, and the
1502 * forwards-subgraph starting at <next>:
1504 if (!check_usage(curr, prev, next, bit,
1505 exclusive_bit(bit), state_name(bit)))
1512 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1513 struct held_lock *next)
1515 #define LOCKDEP_STATE(__STATE) \
1516 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1518 #include "lockdep_states.h"
1519 #undef LOCKDEP_STATE
1524 static void inc_chains(void)
1526 if (current->hardirq_context)
1527 nr_hardirq_chains++;
1529 if (current->softirq_context)
1530 nr_softirq_chains++;
1532 nr_process_chains++;
1539 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1540 struct held_lock *next)
1545 static inline void inc_chains(void)
1547 nr_process_chains++;
1553 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1554 struct held_lock *next)
1556 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1559 printk("\n=============================================\n");
1560 printk( "[ INFO: possible recursive locking detected ]\n");
1561 print_kernel_version();
1562 printk( "---------------------------------------------\n");
1563 printk("%s/%d is trying to acquire lock:\n",
1564 curr->comm, task_pid_nr(curr));
1566 printk("\nbut task is already holding lock:\n");
1569 printk("\nother info that might help us debug this:\n");
1570 lockdep_print_held_locks(curr);
1572 printk("\nstack backtrace:\n");
1579 * Check whether we are holding such a class already.
1581 * (Note that this has to be done separately, because the graph cannot
1582 * detect such classes of deadlocks.)
1584 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1587 check_deadlock(struct task_struct *curr, struct held_lock *next,
1588 struct lockdep_map *next_instance, int read)
1590 struct held_lock *prev;
1591 struct held_lock *nest = NULL;
1594 for (i = 0; i < curr->lockdep_depth; i++) {
1595 prev = curr->held_locks + i;
1597 if (prev->instance == next->nest_lock)
1600 if (hlock_class(prev) != hlock_class(next))
1604 * Allow read-after-read recursion of the same
1605 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1607 if ((read == 2) && prev->read)
1611 * We're holding the nest_lock, which serializes this lock's
1612 * nesting behaviour.
1617 return print_deadlock_bug(curr, prev, next);
1623 * There was a chain-cache miss, and we are about to add a new dependency
1624 * to a previous lock. We recursively validate the following rules:
1626 * - would the adding of the <prev> -> <next> dependency create a
1627 * circular dependency in the graph? [== circular deadlock]
1629 * - does the new prev->next dependency connect any hardirq-safe lock
1630 * (in the full backwards-subgraph starting at <prev>) with any
1631 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1632 * <next>)? [== illegal lock inversion with hardirq contexts]
1634 * - does the new prev->next dependency connect any softirq-safe lock
1635 * (in the full backwards-subgraph starting at <prev>) with any
1636 * softirq-unsafe lock (in the full forwards-subgraph starting at
1637 * <next>)? [== illegal lock inversion with softirq contexts]
1639 * any of these scenarios could lead to a deadlock.
1641 * Then if all the validations pass, we add the forwards and backwards
1645 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1646 struct held_lock *next, int distance)
1648 struct lock_list *entry;
1650 struct lock_list this;
1651 struct lock_list *uninitialized_var(target_entry);
1654 * Prove that the new <prev> -> <next> dependency would not
1655 * create a circular dependency in the graph. (We do this by
1656 * forward-recursing into the graph starting at <next>, and
1657 * checking whether we can reach <prev>.)
1659 * We are using global variables to control the recursion, to
1660 * keep the stackframe size of the recursive functions low:
1662 this.class = hlock_class(next);
1664 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1666 return print_circular_bug(&this, target_entry, next, prev);
1667 else if (unlikely(ret < 0))
1668 return print_bfs_bug(ret);
1670 if (!check_prev_add_irq(curr, prev, next))
1674 * For recursive read-locks we do all the dependency checks,
1675 * but we dont store read-triggered dependencies (only
1676 * write-triggered dependencies). This ensures that only the
1677 * write-side dependencies matter, and that if for example a
1678 * write-lock never takes any other locks, then the reads are
1679 * equivalent to a NOP.
1681 if (next->read == 2 || prev->read == 2)
1684 * Is the <prev> -> <next> dependency already present?
1686 * (this may occur even though this is a new chain: consider
1687 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1688 * chains - the second one will be new, but L1 already has
1689 * L2 added to its dependency list, due to the first chain.)
1691 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1692 if (entry->class == hlock_class(next)) {
1694 entry->distance = 1;
1700 * Ok, all validations passed, add the new lock
1701 * to the previous lock's dependency list:
1703 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1704 &hlock_class(prev)->locks_after,
1705 next->acquire_ip, distance);
1710 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1711 &hlock_class(next)->locks_before,
1712 next->acquire_ip, distance);
1717 * Debugging printouts:
1719 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1721 printk("\n new dependency: ");
1722 print_lock_name(hlock_class(prev));
1724 print_lock_name(hlock_class(next));
1727 return graph_lock();
1733 * Add the dependency to all directly-previous locks that are 'relevant'.
1734 * The ones that are relevant are (in increasing distance from curr):
1735 * all consecutive trylock entries and the final non-trylock entry - or
1736 * the end of this context's lock-chain - whichever comes first.
1739 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1741 int depth = curr->lockdep_depth;
1742 struct held_lock *hlock;
1747 * Depth must not be zero for a non-head lock:
1752 * At least two relevant locks must exist for this
1755 if (curr->held_locks[depth].irq_context !=
1756 curr->held_locks[depth-1].irq_context)
1760 int distance = curr->lockdep_depth - depth + 1;
1761 hlock = curr->held_locks + depth-1;
1763 * Only non-recursive-read entries get new dependencies
1766 if (hlock->read != 2) {
1767 if (!check_prev_add(curr, hlock, next, distance))
1770 * Stop after the first non-trylock entry,
1771 * as non-trylock entries have added their
1772 * own direct dependencies already, so this
1773 * lock is connected to them indirectly:
1775 if (!hlock->trylock)
1780 * End of lock-stack?
1785 * Stop the search if we cross into another context:
1787 if (curr->held_locks[depth].irq_context !=
1788 curr->held_locks[depth-1].irq_context)
1793 if (!debug_locks_off_graph_unlock())
1801 unsigned long nr_lock_chains;
1802 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1803 int nr_chain_hlocks;
1804 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1806 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1808 return lock_classes + chain_hlocks[chain->base + i];
1812 * Look up a dependency chain. If the key is not present yet then
1813 * add it and return 1 - in this case the new dependency chain is
1814 * validated. If the key is already hashed, return 0.
1815 * (On return with 1 graph_lock is held.)
1817 static inline int lookup_chain_cache(struct task_struct *curr,
1818 struct held_lock *hlock,
1821 struct lock_class *class = hlock_class(hlock);
1822 struct list_head *hash_head = chainhashentry(chain_key);
1823 struct lock_chain *chain;
1824 struct held_lock *hlock_curr, *hlock_next;
1827 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1830 * We can walk it lock-free, because entries only get added
1833 list_for_each_entry(chain, hash_head, entry) {
1834 if (chain->chain_key == chain_key) {
1836 debug_atomic_inc(&chain_lookup_hits);
1837 if (very_verbose(class))
1838 printk("\nhash chain already cached, key: "
1839 "%016Lx tail class: [%p] %s\n",
1840 (unsigned long long)chain_key,
1841 class->key, class->name);
1845 if (very_verbose(class))
1846 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1847 (unsigned long long)chain_key, class->key, class->name);
1849 * Allocate a new chain entry from the static array, and add
1855 * We have to walk the chain again locked - to avoid duplicates:
1857 list_for_each_entry(chain, hash_head, entry) {
1858 if (chain->chain_key == chain_key) {
1863 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1864 if (!debug_locks_off_graph_unlock())
1867 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1868 printk("turning off the locking correctness validator.\n");
1872 chain = lock_chains + nr_lock_chains++;
1873 chain->chain_key = chain_key;
1874 chain->irq_context = hlock->irq_context;
1875 /* Find the first held_lock of current chain */
1877 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1878 hlock_curr = curr->held_locks + i;
1879 if (hlock_curr->irq_context != hlock_next->irq_context)
1884 chain->depth = curr->lockdep_depth + 1 - i;
1885 cn = nr_chain_hlocks;
1886 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1887 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1892 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1894 for (j = 0; j < chain->depth - 1; j++, i++) {
1895 int lock_id = curr->held_locks[i].class_idx - 1;
1896 chain_hlocks[chain->base + j] = lock_id;
1898 chain_hlocks[chain->base + j] = class - lock_classes;
1900 list_add_tail_rcu(&chain->entry, hash_head);
1901 debug_atomic_inc(&chain_lookup_misses);
1907 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1908 struct held_lock *hlock, int chain_head, u64 chain_key)
1911 * Trylock needs to maintain the stack of held locks, but it
1912 * does not add new dependencies, because trylock can be done
1915 * We look up the chain_key and do the O(N^2) check and update of
1916 * the dependencies only if this is a new dependency chain.
1917 * (If lookup_chain_cache() returns with 1 it acquires
1918 * graph_lock for us)
1920 if (!hlock->trylock && (hlock->check == 2) &&
1921 lookup_chain_cache(curr, hlock, chain_key)) {
1923 * Check whether last held lock:
1925 * - is irq-safe, if this lock is irq-unsafe
1926 * - is softirq-safe, if this lock is hardirq-unsafe
1928 * And check whether the new lock's dependency graph
1929 * could lead back to the previous lock.
1931 * any of these scenarios could lead to a deadlock. If
1934 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1939 * Mark recursive read, as we jump over it when
1940 * building dependencies (just like we jump over
1946 * Add dependency only if this lock is not the head
1947 * of the chain, and if it's not a secondary read-lock:
1949 if (!chain_head && ret != 2)
1950 if (!check_prevs_add(curr, hlock))
1954 /* after lookup_chain_cache(): */
1955 if (unlikely(!debug_locks))
1961 static inline int validate_chain(struct task_struct *curr,
1962 struct lockdep_map *lock, struct held_lock *hlock,
1963 int chain_head, u64 chain_key)
1970 * We are building curr_chain_key incrementally, so double-check
1971 * it from scratch, to make sure that it's done correctly:
1973 static void check_chain_key(struct task_struct *curr)
1975 #ifdef CONFIG_DEBUG_LOCKDEP
1976 struct held_lock *hlock, *prev_hlock = NULL;
1980 for (i = 0; i < curr->lockdep_depth; i++) {
1981 hlock = curr->held_locks + i;
1982 if (chain_key != hlock->prev_chain_key) {
1984 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1985 curr->lockdep_depth, i,
1986 (unsigned long long)chain_key,
1987 (unsigned long long)hlock->prev_chain_key);
1990 id = hlock->class_idx - 1;
1991 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1994 if (prev_hlock && (prev_hlock->irq_context !=
1995 hlock->irq_context))
1997 chain_key = iterate_chain_key(chain_key, id);
2000 if (chain_key != curr->curr_chain_key) {
2002 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2003 curr->lockdep_depth, i,
2004 (unsigned long long)chain_key,
2005 (unsigned long long)curr->curr_chain_key);
2011 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2012 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2014 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2017 printk("\n=================================\n");
2018 printk( "[ INFO: inconsistent lock state ]\n");
2019 print_kernel_version();
2020 printk( "---------------------------------\n");
2022 printk("inconsistent {%s} -> {%s} usage.\n",
2023 usage_str[prev_bit], usage_str[new_bit]);
2025 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2026 curr->comm, task_pid_nr(curr),
2027 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2028 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2029 trace_hardirqs_enabled(curr),
2030 trace_softirqs_enabled(curr));
2033 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2034 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2036 print_irqtrace_events(curr);
2037 printk("\nother info that might help us debug this:\n");
2038 lockdep_print_held_locks(curr);
2040 printk("\nstack backtrace:\n");
2047 * Print out an error if an invalid bit is set:
2050 valid_state(struct task_struct *curr, struct held_lock *this,
2051 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2053 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2054 return print_usage_bug(curr, this, bad_bit, new_bit);
2058 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2059 enum lock_usage_bit new_bit);
2061 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2064 * print irq inversion bug:
2067 print_irq_inversion_bug(struct task_struct *curr,
2068 struct lock_list *root, struct lock_list *other,
2069 struct held_lock *this, int forwards,
2070 const char *irqclass)
2072 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2075 printk("\n=========================================================\n");
2076 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
2077 print_kernel_version();
2078 printk( "---------------------------------------------------------\n");
2079 printk("%s/%d just changed the state of lock:\n",
2080 curr->comm, task_pid_nr(curr));
2083 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2085 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2086 print_lock_name(other->class);
2087 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2089 printk("\nother info that might help us debug this:\n");
2090 lockdep_print_held_locks(curr);
2092 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2093 if (!save_trace(&root->trace))
2095 print_shortest_lock_dependencies(other, root);
2097 printk("\nstack backtrace:\n");
2104 * Prove that in the forwards-direction subgraph starting at <this>
2105 * there is no lock matching <mask>:
2108 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2109 enum lock_usage_bit bit, const char *irqclass)
2112 struct lock_list root;
2113 struct lock_list *uninitialized_var(target_entry);
2116 root.class = hlock_class(this);
2117 ret = find_usage_forwards(&root, bit, &target_entry);
2119 return print_bfs_bug(ret);
2123 return print_irq_inversion_bug(curr, &root, target_entry,
2128 * Prove that in the backwards-direction subgraph starting at <this>
2129 * there is no lock matching <mask>:
2132 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2133 enum lock_usage_bit bit, const char *irqclass)
2136 struct lock_list root;
2137 struct lock_list *uninitialized_var(target_entry);
2140 root.class = hlock_class(this);
2141 ret = find_usage_backwards(&root, bit, &target_entry);
2143 return print_bfs_bug(ret);
2147 return print_irq_inversion_bug(curr, &root, target_entry,
2151 void print_irqtrace_events(struct task_struct *curr)
2153 printk("irq event stamp: %u\n", curr->irq_events);
2154 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2155 print_ip_sym(curr->hardirq_enable_ip);
2156 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2157 print_ip_sym(curr->hardirq_disable_ip);
2158 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2159 print_ip_sym(curr->softirq_enable_ip);
2160 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2161 print_ip_sym(curr->softirq_disable_ip);
2164 static int HARDIRQ_verbose(struct lock_class *class)
2167 return class_filter(class);
2172 static int SOFTIRQ_verbose(struct lock_class *class)
2175 return class_filter(class);
2180 static int RECLAIM_FS_verbose(struct lock_class *class)
2183 return class_filter(class);
2188 #define STRICT_READ_CHECKS 1
2190 static int (*state_verbose_f[])(struct lock_class *class) = {
2191 #define LOCKDEP_STATE(__STATE) \
2193 #include "lockdep_states.h"
2194 #undef LOCKDEP_STATE
2197 static inline int state_verbose(enum lock_usage_bit bit,
2198 struct lock_class *class)
2200 return state_verbose_f[bit >> 2](class);
2203 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2204 enum lock_usage_bit bit, const char *name);
2207 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2208 enum lock_usage_bit new_bit)
2210 int excl_bit = exclusive_bit(new_bit);
2211 int read = new_bit & 1;
2212 int dir = new_bit & 2;
2215 * mark USED_IN has to look forwards -- to ensure no dependency
2216 * has ENABLED state, which would allow recursion deadlocks.
2218 * mark ENABLED has to look backwards -- to ensure no dependee
2219 * has USED_IN state, which, again, would allow recursion deadlocks.
2221 check_usage_f usage = dir ?
2222 check_usage_backwards : check_usage_forwards;
2225 * Validate that this particular lock does not have conflicting
2228 if (!valid_state(curr, this, new_bit, excl_bit))
2232 * Validate that the lock dependencies don't have conflicting usage
2235 if ((!read || !dir || STRICT_READ_CHECKS) &&
2236 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2240 * Check for read in write conflicts
2243 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2246 if (STRICT_READ_CHECKS &&
2247 !usage(curr, this, excl_bit + 1,
2248 state_name(new_bit + 1)))
2252 if (state_verbose(new_bit, hlock_class(this)))
2259 #define LOCKDEP_STATE(__STATE) __STATE,
2260 #include "lockdep_states.h"
2261 #undef LOCKDEP_STATE
2265 * Mark all held locks with a usage bit:
2268 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2270 enum lock_usage_bit usage_bit;
2271 struct held_lock *hlock;
2274 for (i = 0; i < curr->lockdep_depth; i++) {
2275 hlock = curr->held_locks + i;
2277 usage_bit = 2 + (mark << 2); /* ENABLED */
2279 usage_bit += 1; /* READ */
2281 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2283 if (!mark_lock(curr, hlock, usage_bit))
2291 * Debugging helper: via this flag we know that we are in
2292 * 'early bootup code', and will warn about any invalid irqs-on event:
2294 static int early_boot_irqs_enabled;
2296 void early_boot_irqs_off(void)
2298 early_boot_irqs_enabled = 0;
2301 void early_boot_irqs_on(void)
2303 early_boot_irqs_enabled = 1;
2307 * Hardirqs will be enabled:
2309 void trace_hardirqs_on_caller(unsigned long ip)
2311 struct task_struct *curr = current;
2313 time_hardirqs_on(CALLER_ADDR0, ip);
2315 if (unlikely(!debug_locks || current->lockdep_recursion))
2318 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2321 if (unlikely(curr->hardirqs_enabled)) {
2322 debug_atomic_inc(&redundant_hardirqs_on);
2325 /* we'll do an OFF -> ON transition: */
2326 curr->hardirqs_enabled = 1;
2328 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2330 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2333 * We are going to turn hardirqs on, so set the
2334 * usage bit for all held locks:
2336 if (!mark_held_locks(curr, HARDIRQ))
2339 * If we have softirqs enabled, then set the usage
2340 * bit for all held locks. (disabled hardirqs prevented
2341 * this bit from being set before)
2343 if (curr->softirqs_enabled)
2344 if (!mark_held_locks(curr, SOFTIRQ))
2347 curr->hardirq_enable_ip = ip;
2348 curr->hardirq_enable_event = ++curr->irq_events;
2349 debug_atomic_inc(&hardirqs_on_events);
2351 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2353 void trace_hardirqs_on(void)
2355 trace_hardirqs_on_caller(CALLER_ADDR0);
2357 EXPORT_SYMBOL(trace_hardirqs_on);
2360 * Hardirqs were disabled:
2362 void trace_hardirqs_off_caller(unsigned long ip)
2364 struct task_struct *curr = current;
2366 time_hardirqs_off(CALLER_ADDR0, ip);
2368 if (unlikely(!debug_locks || current->lockdep_recursion))
2371 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2374 if (curr->hardirqs_enabled) {
2376 * We have done an ON -> OFF transition:
2378 curr->hardirqs_enabled = 0;
2379 curr->hardirq_disable_ip = ip;
2380 curr->hardirq_disable_event = ++curr->irq_events;
2381 debug_atomic_inc(&hardirqs_off_events);
2383 debug_atomic_inc(&redundant_hardirqs_off);
2385 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2387 void trace_hardirqs_off(void)
2389 trace_hardirqs_off_caller(CALLER_ADDR0);
2391 EXPORT_SYMBOL(trace_hardirqs_off);
2394 * Softirqs will be enabled:
2396 void trace_softirqs_on(unsigned long ip)
2398 struct task_struct *curr = current;
2400 if (unlikely(!debug_locks))
2403 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2406 if (curr->softirqs_enabled) {
2407 debug_atomic_inc(&redundant_softirqs_on);
2412 * We'll do an OFF -> ON transition:
2414 curr->softirqs_enabled = 1;
2415 curr->softirq_enable_ip = ip;
2416 curr->softirq_enable_event = ++curr->irq_events;
2417 debug_atomic_inc(&softirqs_on_events);
2419 * We are going to turn softirqs on, so set the
2420 * usage bit for all held locks, if hardirqs are
2423 if (curr->hardirqs_enabled)
2424 mark_held_locks(curr, SOFTIRQ);
2428 * Softirqs were disabled:
2430 void trace_softirqs_off(unsigned long ip)
2432 struct task_struct *curr = current;
2434 if (unlikely(!debug_locks))
2437 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2440 if (curr->softirqs_enabled) {
2442 * We have done an ON -> OFF transition:
2444 curr->softirqs_enabled = 0;
2445 curr->softirq_disable_ip = ip;
2446 curr->softirq_disable_event = ++curr->irq_events;
2447 debug_atomic_inc(&softirqs_off_events);
2448 DEBUG_LOCKS_WARN_ON(!softirq_count());
2450 debug_atomic_inc(&redundant_softirqs_off);
2453 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2455 struct task_struct *curr = current;
2457 if (unlikely(!debug_locks))
2460 /* no reclaim without waiting on it */
2461 if (!(gfp_mask & __GFP_WAIT))
2464 /* this guy won't enter reclaim */
2465 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2468 /* We're only interested __GFP_FS allocations for now */
2469 if (!(gfp_mask & __GFP_FS))
2472 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2475 mark_held_locks(curr, RECLAIM_FS);
2478 static void check_flags(unsigned long flags);
2480 void lockdep_trace_alloc(gfp_t gfp_mask)
2482 unsigned long flags;
2484 if (unlikely(current->lockdep_recursion))
2487 raw_local_irq_save(flags);
2489 current->lockdep_recursion = 1;
2490 __lockdep_trace_alloc(gfp_mask, flags);
2491 current->lockdep_recursion = 0;
2492 raw_local_irq_restore(flags);
2495 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2498 * If non-trylock use in a hardirq or softirq context, then
2499 * mark the lock as used in these contexts:
2501 if (!hlock->trylock) {
2503 if (curr->hardirq_context)
2504 if (!mark_lock(curr, hlock,
2505 LOCK_USED_IN_HARDIRQ_READ))
2507 if (curr->softirq_context)
2508 if (!mark_lock(curr, hlock,
2509 LOCK_USED_IN_SOFTIRQ_READ))
2512 if (curr->hardirq_context)
2513 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2515 if (curr->softirq_context)
2516 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2520 if (!hlock->hardirqs_off) {
2522 if (!mark_lock(curr, hlock,
2523 LOCK_ENABLED_HARDIRQ_READ))
2525 if (curr->softirqs_enabled)
2526 if (!mark_lock(curr, hlock,
2527 LOCK_ENABLED_SOFTIRQ_READ))
2530 if (!mark_lock(curr, hlock,
2531 LOCK_ENABLED_HARDIRQ))
2533 if (curr->softirqs_enabled)
2534 if (!mark_lock(curr, hlock,
2535 LOCK_ENABLED_SOFTIRQ))
2541 * We reuse the irq context infrastructure more broadly as a general
2542 * context checking code. This tests GFP_FS recursion (a lock taken
2543 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2546 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2548 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2551 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2559 static int separate_irq_context(struct task_struct *curr,
2560 struct held_lock *hlock)
2562 unsigned int depth = curr->lockdep_depth;
2565 * Keep track of points where we cross into an interrupt context:
2567 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2568 curr->softirq_context;
2570 struct held_lock *prev_hlock;
2572 prev_hlock = curr->held_locks + depth-1;
2574 * If we cross into another context, reset the
2575 * hash key (this also prevents the checking and the
2576 * adding of the dependency to 'prev'):
2578 if (prev_hlock->irq_context != hlock->irq_context)
2587 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2588 enum lock_usage_bit new_bit)
2594 static inline int mark_irqflags(struct task_struct *curr,
2595 struct held_lock *hlock)
2600 static inline int separate_irq_context(struct task_struct *curr,
2601 struct held_lock *hlock)
2606 void lockdep_trace_alloc(gfp_t gfp_mask)
2613 * Mark a lock with a usage bit, and validate the state transition:
2615 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2616 enum lock_usage_bit new_bit)
2618 unsigned int new_mask = 1 << new_bit, ret = 1;
2621 * If already set then do not dirty the cacheline,
2622 * nor do any checks:
2624 if (likely(hlock_class(this)->usage_mask & new_mask))
2630 * Make sure we didnt race:
2632 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2637 hlock_class(this)->usage_mask |= new_mask;
2639 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2643 #define LOCKDEP_STATE(__STATE) \
2644 case LOCK_USED_IN_##__STATE: \
2645 case LOCK_USED_IN_##__STATE##_READ: \
2646 case LOCK_ENABLED_##__STATE: \
2647 case LOCK_ENABLED_##__STATE##_READ:
2648 #include "lockdep_states.h"
2649 #undef LOCKDEP_STATE
2650 ret = mark_lock_irq(curr, this, new_bit);
2655 debug_atomic_dec(&nr_unused_locks);
2658 if (!debug_locks_off_graph_unlock())
2667 * We must printk outside of the graph_lock:
2670 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2672 print_irqtrace_events(curr);
2680 * Initialize a lock instance's lock-class mapping info:
2682 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2683 struct lock_class_key *key, int subclass)
2685 lock->class_cache = NULL;
2686 #ifdef CONFIG_LOCK_STAT
2687 lock->cpu = raw_smp_processor_id();
2690 if (DEBUG_LOCKS_WARN_ON(!name)) {
2691 lock->name = "NULL";
2697 if (DEBUG_LOCKS_WARN_ON(!key))
2700 * Sanity check, the lock-class key must be persistent:
2702 if (!static_obj(key)) {
2703 printk("BUG: key %p not in .data!\n", key);
2704 DEBUG_LOCKS_WARN_ON(1);
2709 if (unlikely(!debug_locks))
2713 register_lock_class(lock, subclass, 1);
2715 EXPORT_SYMBOL_GPL(lockdep_init_map);
2718 * This gets called for every mutex_lock*()/spin_lock*() operation.
2719 * We maintain the dependency maps and validate the locking attempt:
2721 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2722 int trylock, int read, int check, int hardirqs_off,
2723 struct lockdep_map *nest_lock, unsigned long ip,
2726 struct task_struct *curr = current;
2727 struct lock_class *class = NULL;
2728 struct held_lock *hlock;
2729 unsigned int depth, id;
2737 if (unlikely(!debug_locks))
2740 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2743 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2745 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2746 printk("turning off the locking correctness validator.\n");
2752 class = lock->class_cache;
2754 * Not cached yet or subclass?
2756 if (unlikely(!class)) {
2757 class = register_lock_class(lock, subclass, 0);
2761 debug_atomic_inc((atomic_t *)&class->ops);
2762 if (very_verbose(class)) {
2763 printk("\nacquire class [%p] %s", class->key, class->name);
2764 if (class->name_version > 1)
2765 printk("#%d", class->name_version);
2771 * Add the lock to the list of currently held locks.
2772 * (we dont increase the depth just yet, up until the
2773 * dependency checks are done)
2775 depth = curr->lockdep_depth;
2776 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2779 class_idx = class - lock_classes + 1;
2782 hlock = curr->held_locks + depth - 1;
2783 if (hlock->class_idx == class_idx && nest_lock) {
2784 if (hlock->references)
2785 hlock->references++;
2787 hlock->references = 2;
2793 hlock = curr->held_locks + depth;
2794 if (DEBUG_LOCKS_WARN_ON(!class))
2796 hlock->class_idx = class_idx;
2797 hlock->acquire_ip = ip;
2798 hlock->instance = lock;
2799 hlock->nest_lock = nest_lock;
2800 hlock->trylock = trylock;
2802 hlock->check = check;
2803 hlock->hardirqs_off = !!hardirqs_off;
2804 hlock->references = references;
2805 #ifdef CONFIG_LOCK_STAT
2806 hlock->waittime_stamp = 0;
2807 hlock->holdtime_stamp = lockstat_clock();
2810 if (check == 2 && !mark_irqflags(curr, hlock))
2813 /* mark it as used: */
2814 if (!mark_lock(curr, hlock, LOCK_USED))
2818 * Calculate the chain hash: it's the combined hash of all the
2819 * lock keys along the dependency chain. We save the hash value
2820 * at every step so that we can get the current hash easily
2821 * after unlock. The chain hash is then used to cache dependency
2824 * The 'key ID' is what is the most compact key value to drive
2825 * the hash, not class->key.
2827 id = class - lock_classes;
2828 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2831 chain_key = curr->curr_chain_key;
2833 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2838 hlock->prev_chain_key = chain_key;
2839 if (separate_irq_context(curr, hlock)) {
2843 chain_key = iterate_chain_key(chain_key, id);
2845 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2848 curr->curr_chain_key = chain_key;
2849 curr->lockdep_depth++;
2850 check_chain_key(curr);
2851 #ifdef CONFIG_DEBUG_LOCKDEP
2852 if (unlikely(!debug_locks))
2855 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2857 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2858 printk("turning off the locking correctness validator.\n");
2863 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2864 max_lockdep_depth = curr->lockdep_depth;
2870 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2873 if (!debug_locks_off())
2875 if (debug_locks_silent)
2878 printk("\n=====================================\n");
2879 printk( "[ BUG: bad unlock balance detected! ]\n");
2880 printk( "-------------------------------------\n");
2881 printk("%s/%d is trying to release lock (",
2882 curr->comm, task_pid_nr(curr));
2883 print_lockdep_cache(lock);
2886 printk("but there are no more locks to release!\n");
2887 printk("\nother info that might help us debug this:\n");
2888 lockdep_print_held_locks(curr);
2890 printk("\nstack backtrace:\n");
2897 * Common debugging checks for both nested and non-nested unlock:
2899 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2902 if (unlikely(!debug_locks))
2904 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2907 if (curr->lockdep_depth <= 0)
2908 return print_unlock_inbalance_bug(curr, lock, ip);
2913 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
2915 if (hlock->instance == lock)
2918 if (hlock->references) {
2919 struct lock_class *class = lock->class_cache;
2922 class = look_up_lock_class(lock, 0);
2924 if (DEBUG_LOCKS_WARN_ON(!class))
2927 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
2930 if (hlock->class_idx == class - lock_classes + 1)
2938 __lock_set_class(struct lockdep_map *lock, const char *name,
2939 struct lock_class_key *key, unsigned int subclass,
2942 struct task_struct *curr = current;
2943 struct held_lock *hlock, *prev_hlock;
2944 struct lock_class *class;
2948 depth = curr->lockdep_depth;
2949 if (DEBUG_LOCKS_WARN_ON(!depth))
2953 for (i = depth-1; i >= 0; i--) {
2954 hlock = curr->held_locks + i;
2956 * We must not cross into another context:
2958 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2960 if (match_held_lock(hlock, lock))
2964 return print_unlock_inbalance_bug(curr, lock, ip);
2967 lockdep_init_map(lock, name, key, 0);
2968 class = register_lock_class(lock, subclass, 0);
2969 hlock->class_idx = class - lock_classes + 1;
2971 curr->lockdep_depth = i;
2972 curr->curr_chain_key = hlock->prev_chain_key;
2974 for (; i < depth; i++) {
2975 hlock = curr->held_locks + i;
2976 if (!__lock_acquire(hlock->instance,
2977 hlock_class(hlock)->subclass, hlock->trylock,
2978 hlock->read, hlock->check, hlock->hardirqs_off,
2979 hlock->nest_lock, hlock->acquire_ip,
2984 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2990 * Remove the lock to the list of currently held locks in a
2991 * potentially non-nested (out of order) manner. This is a
2992 * relatively rare operation, as all the unlock APIs default
2993 * to nested mode (which uses lock_release()):
2996 lock_release_non_nested(struct task_struct *curr,
2997 struct lockdep_map *lock, unsigned long ip)
2999 struct held_lock *hlock, *prev_hlock;
3004 * Check whether the lock exists in the current stack
3007 depth = curr->lockdep_depth;
3008 if (DEBUG_LOCKS_WARN_ON(!depth))
3012 for (i = depth-1; i >= 0; i--) {
3013 hlock = curr->held_locks + i;
3015 * We must not cross into another context:
3017 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3019 if (match_held_lock(hlock, lock))
3023 return print_unlock_inbalance_bug(curr, lock, ip);
3026 if (hlock->instance == lock)
3027 lock_release_holdtime(hlock);
3029 if (hlock->references) {
3030 hlock->references--;
3031 if (hlock->references) {
3033 * We had, and after removing one, still have
3034 * references, the current lock stack is still
3035 * valid. We're done!
3042 * We have the right lock to unlock, 'hlock' points to it.
3043 * Now we remove it from the stack, and add back the other
3044 * entries (if any), recalculating the hash along the way:
3047 curr->lockdep_depth = i;
3048 curr->curr_chain_key = hlock->prev_chain_key;
3050 for (i++; i < depth; i++) {
3051 hlock = curr->held_locks + i;
3052 if (!__lock_acquire(hlock->instance,
3053 hlock_class(hlock)->subclass, hlock->trylock,
3054 hlock->read, hlock->check, hlock->hardirqs_off,
3055 hlock->nest_lock, hlock->acquire_ip,
3060 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3066 * Remove the lock to the list of currently held locks - this gets
3067 * called on mutex_unlock()/spin_unlock*() (or on a failed
3068 * mutex_lock_interruptible()). This is done for unlocks that nest
3069 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3071 static int lock_release_nested(struct task_struct *curr,
3072 struct lockdep_map *lock, unsigned long ip)
3074 struct held_lock *hlock;
3078 * Pop off the top of the lock stack:
3080 depth = curr->lockdep_depth - 1;
3081 hlock = curr->held_locks + depth;
3084 * Is the unlock non-nested:
3086 if (hlock->instance != lock || hlock->references)
3087 return lock_release_non_nested(curr, lock, ip);
3088 curr->lockdep_depth--;
3090 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3093 curr->curr_chain_key = hlock->prev_chain_key;
3095 lock_release_holdtime(hlock);
3097 #ifdef CONFIG_DEBUG_LOCKDEP
3098 hlock->prev_chain_key = 0;
3099 hlock->class_idx = 0;
3100 hlock->acquire_ip = 0;
3101 hlock->irq_context = 0;
3107 * Remove the lock to the list of currently held locks - this gets
3108 * called on mutex_unlock()/spin_unlock*() (or on a failed
3109 * mutex_lock_interruptible()). This is done for unlocks that nest
3110 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3113 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3115 struct task_struct *curr = current;
3117 if (!check_unlock(curr, lock, ip))
3121 if (!lock_release_nested(curr, lock, ip))
3124 if (!lock_release_non_nested(curr, lock, ip))
3128 check_chain_key(curr);
3131 static int __lock_is_held(struct lockdep_map *lock)
3133 struct task_struct *curr = current;
3136 for (i = 0; i < curr->lockdep_depth; i++) {
3137 struct held_lock *hlock = curr->held_locks + i;
3139 if (match_held_lock(hlock, lock))
3147 * Check whether we follow the irq-flags state precisely:
3149 static void check_flags(unsigned long flags)
3151 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3152 defined(CONFIG_TRACE_IRQFLAGS)
3156 if (irqs_disabled_flags(flags)) {
3157 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3158 printk("possible reason: unannotated irqs-off.\n");
3161 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3162 printk("possible reason: unannotated irqs-on.\n");
3167 * We dont accurately track softirq state in e.g.
3168 * hardirq contexts (such as on 4KSTACKS), so only
3169 * check if not in hardirq contexts:
3171 if (!hardirq_count()) {
3172 if (softirq_count())
3173 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3175 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3179 print_irqtrace_events(current);
3183 void lock_set_class(struct lockdep_map *lock, const char *name,
3184 struct lock_class_key *key, unsigned int subclass,
3187 unsigned long flags;
3189 if (unlikely(current->lockdep_recursion))
3192 raw_local_irq_save(flags);
3193 current->lockdep_recursion = 1;
3195 if (__lock_set_class(lock, name, key, subclass, ip))
3196 check_chain_key(current);
3197 current->lockdep_recursion = 0;
3198 raw_local_irq_restore(flags);
3200 EXPORT_SYMBOL_GPL(lock_set_class);
3203 * We are not always called with irqs disabled - do that here,
3204 * and also avoid lockdep recursion:
3206 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3207 int trylock, int read, int check,
3208 struct lockdep_map *nest_lock, unsigned long ip)
3210 unsigned long flags;
3212 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3214 if (unlikely(current->lockdep_recursion))
3217 raw_local_irq_save(flags);
3220 current->lockdep_recursion = 1;
3221 __lock_acquire(lock, subclass, trylock, read, check,
3222 irqs_disabled_flags(flags), nest_lock, ip, 0);
3223 current->lockdep_recursion = 0;
3224 raw_local_irq_restore(flags);
3226 EXPORT_SYMBOL_GPL(lock_acquire);
3228 void lock_release(struct lockdep_map *lock, int nested,
3231 unsigned long flags;
3233 trace_lock_release(lock, nested, ip);
3235 if (unlikely(current->lockdep_recursion))
3238 raw_local_irq_save(flags);
3240 current->lockdep_recursion = 1;
3241 __lock_release(lock, nested, ip);
3242 current->lockdep_recursion = 0;
3243 raw_local_irq_restore(flags);
3245 EXPORT_SYMBOL_GPL(lock_release);
3247 int lock_is_held(struct lockdep_map *lock)
3249 unsigned long flags;
3252 if (unlikely(current->lockdep_recursion))
3255 raw_local_irq_save(flags);
3258 current->lockdep_recursion = 1;
3259 ret = __lock_is_held(lock);
3260 current->lockdep_recursion = 0;
3261 raw_local_irq_restore(flags);
3265 EXPORT_SYMBOL_GPL(lock_is_held);
3267 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3269 current->lockdep_reclaim_gfp = gfp_mask;
3272 void lockdep_clear_current_reclaim_state(void)
3274 current->lockdep_reclaim_gfp = 0;
3277 #ifdef CONFIG_LOCK_STAT
3279 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3282 if (!debug_locks_off())
3284 if (debug_locks_silent)
3287 printk("\n=================================\n");
3288 printk( "[ BUG: bad contention detected! ]\n");
3289 printk( "---------------------------------\n");
3290 printk("%s/%d is trying to contend lock (",
3291 curr->comm, task_pid_nr(curr));
3292 print_lockdep_cache(lock);
3295 printk("but there are no locks held!\n");
3296 printk("\nother info that might help us debug this:\n");
3297 lockdep_print_held_locks(curr);
3299 printk("\nstack backtrace:\n");
3306 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3308 struct task_struct *curr = current;
3309 struct held_lock *hlock, *prev_hlock;
3310 struct lock_class_stats *stats;
3312 int i, contention_point, contending_point;
3314 depth = curr->lockdep_depth;
3315 if (DEBUG_LOCKS_WARN_ON(!depth))
3319 for (i = depth-1; i >= 0; i--) {
3320 hlock = curr->held_locks + i;
3322 * We must not cross into another context:
3324 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3326 if (match_held_lock(hlock, lock))
3330 print_lock_contention_bug(curr, lock, ip);
3334 if (hlock->instance != lock)
3337 hlock->waittime_stamp = lockstat_clock();
3339 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3340 contending_point = lock_point(hlock_class(hlock)->contending_point,
3343 stats = get_lock_stats(hlock_class(hlock));
3344 if (contention_point < LOCKSTAT_POINTS)
3345 stats->contention_point[contention_point]++;
3346 if (contending_point < LOCKSTAT_POINTS)
3347 stats->contending_point[contending_point]++;
3348 if (lock->cpu != smp_processor_id())
3349 stats->bounces[bounce_contended + !!hlock->read]++;
3350 put_lock_stats(stats);
3354 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3356 struct task_struct *curr = current;
3357 struct held_lock *hlock, *prev_hlock;
3358 struct lock_class_stats *stats;
3360 u64 now, waittime = 0;
3363 depth = curr->lockdep_depth;
3364 if (DEBUG_LOCKS_WARN_ON(!depth))
3368 for (i = depth-1; i >= 0; i--) {
3369 hlock = curr->held_locks + i;
3371 * We must not cross into another context:
3373 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3375 if (match_held_lock(hlock, lock))
3379 print_lock_contention_bug(curr, lock, _RET_IP_);
3383 if (hlock->instance != lock)
3386 cpu = smp_processor_id();
3387 if (hlock->waittime_stamp) {
3388 now = lockstat_clock();
3389 waittime = now - hlock->waittime_stamp;
3390 hlock->holdtime_stamp = now;
3393 trace_lock_acquired(lock, ip, waittime);
3395 stats = get_lock_stats(hlock_class(hlock));
3398 lock_time_inc(&stats->read_waittime, waittime);
3400 lock_time_inc(&stats->write_waittime, waittime);
3402 if (lock->cpu != cpu)
3403 stats->bounces[bounce_acquired + !!hlock->read]++;
3404 put_lock_stats(stats);
3410 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3412 unsigned long flags;
3414 trace_lock_contended(lock, ip);
3416 if (unlikely(!lock_stat))
3419 if (unlikely(current->lockdep_recursion))
3422 raw_local_irq_save(flags);
3424 current->lockdep_recursion = 1;
3425 __lock_contended(lock, ip);
3426 current->lockdep_recursion = 0;
3427 raw_local_irq_restore(flags);
3429 EXPORT_SYMBOL_GPL(lock_contended);
3431 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3433 unsigned long flags;
3435 if (unlikely(!lock_stat))
3438 if (unlikely(current->lockdep_recursion))
3441 raw_local_irq_save(flags);
3443 current->lockdep_recursion = 1;
3444 __lock_acquired(lock, ip);
3445 current->lockdep_recursion = 0;
3446 raw_local_irq_restore(flags);
3448 EXPORT_SYMBOL_GPL(lock_acquired);
3452 * Used by the testsuite, sanitize the validator state
3453 * after a simulated failure:
3456 void lockdep_reset(void)
3458 unsigned long flags;
3461 raw_local_irq_save(flags);
3462 current->curr_chain_key = 0;
3463 current->lockdep_depth = 0;
3464 current->lockdep_recursion = 0;
3465 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3466 nr_hardirq_chains = 0;
3467 nr_softirq_chains = 0;
3468 nr_process_chains = 0;
3470 for (i = 0; i < CHAINHASH_SIZE; i++)
3471 INIT_LIST_HEAD(chainhash_table + i);
3472 raw_local_irq_restore(flags);
3475 static void zap_class(struct lock_class *class)
3480 * Remove all dependencies this lock is
3483 for (i = 0; i < nr_list_entries; i++) {
3484 if (list_entries[i].class == class)
3485 list_del_rcu(&list_entries[i].entry);
3488 * Unhash the class and remove it from the all_lock_classes list:
3490 list_del_rcu(&class->hash_entry);
3491 list_del_rcu(&class->lock_entry);
3496 static inline int within(const void *addr, void *start, unsigned long size)
3498 return addr >= start && addr < start + size;
3501 void lockdep_free_key_range(void *start, unsigned long size)
3503 struct lock_class *class, *next;
3504 struct list_head *head;
3505 unsigned long flags;
3509 raw_local_irq_save(flags);
3510 locked = graph_lock();
3513 * Unhash all classes that were created by this module:
3515 for (i = 0; i < CLASSHASH_SIZE; i++) {
3516 head = classhash_table + i;
3517 if (list_empty(head))
3519 list_for_each_entry_safe(class, next, head, hash_entry) {
3520 if (within(class->key, start, size))
3522 else if (within(class->name, start, size))
3529 raw_local_irq_restore(flags);
3532 void lockdep_reset_lock(struct lockdep_map *lock)
3534 struct lock_class *class, *next;
3535 struct list_head *head;
3536 unsigned long flags;
3540 raw_local_irq_save(flags);
3543 * Remove all classes this lock might have:
3545 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3547 * If the class exists we look it up and zap it:
3549 class = look_up_lock_class(lock, j);
3554 * Debug check: in the end all mapped classes should
3557 locked = graph_lock();
3558 for (i = 0; i < CLASSHASH_SIZE; i++) {
3559 head = classhash_table + i;
3560 if (list_empty(head))
3562 list_for_each_entry_safe(class, next, head, hash_entry) {
3563 if (unlikely(class == lock->class_cache)) {
3564 if (debug_locks_off_graph_unlock())
3574 raw_local_irq_restore(flags);
3577 void lockdep_init(void)
3582 * Some architectures have their own start_kernel()
3583 * code which calls lockdep_init(), while we also
3584 * call lockdep_init() from the start_kernel() itself,
3585 * and we want to initialize the hashes only once:
3587 if (lockdep_initialized)
3590 for (i = 0; i < CLASSHASH_SIZE; i++)
3591 INIT_LIST_HEAD(classhash_table + i);
3593 for (i = 0; i < CHAINHASH_SIZE; i++)
3594 INIT_LIST_HEAD(chainhash_table + i);
3596 lockdep_initialized = 1;
3599 void __init lockdep_info(void)
3601 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3603 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3604 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3605 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3606 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3607 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3608 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3609 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3611 printk(" memory used by lock dependency info: %lu kB\n",
3612 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3613 sizeof(struct list_head) * CLASSHASH_SIZE +
3614 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3615 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3616 sizeof(struct list_head) * CHAINHASH_SIZE
3617 #ifdef CONFIG_PROVE_LOCKING
3618 + sizeof(struct circular_queue)
3623 printk(" per task-struct memory footprint: %lu bytes\n",
3624 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3626 #ifdef CONFIG_DEBUG_LOCKDEP
3627 if (lockdep_init_error) {
3628 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3629 printk("Call stack leading to lockdep invocation was:\n");
3630 print_stack_trace(&lockdep_init_trace, 0);
3636 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3637 const void *mem_to, struct held_lock *hlock)
3639 if (!debug_locks_off())
3641 if (debug_locks_silent)
3644 printk("\n=========================\n");
3645 printk( "[ BUG: held lock freed! ]\n");
3646 printk( "-------------------------\n");
3647 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3648 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3650 lockdep_print_held_locks(curr);
3652 printk("\nstack backtrace:\n");
3656 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3657 const void* lock_from, unsigned long lock_len)
3659 return lock_from + lock_len <= mem_from ||
3660 mem_from + mem_len <= lock_from;
3664 * Called when kernel memory is freed (or unmapped), or if a lock
3665 * is destroyed or reinitialized - this code checks whether there is
3666 * any held lock in the memory range of <from> to <to>:
3668 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3670 struct task_struct *curr = current;
3671 struct held_lock *hlock;
3672 unsigned long flags;
3675 if (unlikely(!debug_locks))
3678 local_irq_save(flags);
3679 for (i = 0; i < curr->lockdep_depth; i++) {
3680 hlock = curr->held_locks + i;
3682 if (not_in_range(mem_from, mem_len, hlock->instance,
3683 sizeof(*hlock->instance)))
3686 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3689 local_irq_restore(flags);
3691 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3693 static void print_held_locks_bug(struct task_struct *curr)
3695 if (!debug_locks_off())
3697 if (debug_locks_silent)
3700 printk("\n=====================================\n");
3701 printk( "[ BUG: lock held at task exit time! ]\n");
3702 printk( "-------------------------------------\n");
3703 printk("%s/%d is exiting with locks still held!\n",
3704 curr->comm, task_pid_nr(curr));
3705 lockdep_print_held_locks(curr);
3707 printk("\nstack backtrace:\n");
3711 void debug_check_no_locks_held(struct task_struct *task)
3713 if (unlikely(task->lockdep_depth > 0))
3714 print_held_locks_bug(task);
3717 void debug_show_all_locks(void)
3719 struct task_struct *g, *p;
3723 if (unlikely(!debug_locks)) {
3724 printk("INFO: lockdep is turned off.\n");
3727 printk("\nShowing all locks held in the system:\n");
3730 * Here we try to get the tasklist_lock as hard as possible,
3731 * if not successful after 2 seconds we ignore it (but keep
3732 * trying). This is to enable a debug printout even if a
3733 * tasklist_lock-holding task deadlocks or crashes.
3736 if (!read_trylock(&tasklist_lock)) {
3738 printk("hm, tasklist_lock locked, retrying... ");
3741 printk(" #%d", 10-count);
3745 printk(" ignoring it.\n");
3749 printk(KERN_CONT " locked it.\n");
3752 do_each_thread(g, p) {
3754 * It's not reliable to print a task's held locks
3755 * if it's not sleeping (or if it's not the current
3758 if (p->state == TASK_RUNNING && p != current)
3760 if (p->lockdep_depth)
3761 lockdep_print_held_locks(p);
3763 if (read_trylock(&tasklist_lock))
3765 } while_each_thread(g, p);
3768 printk("=============================================\n\n");
3771 read_unlock(&tasklist_lock);
3773 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3776 * Careful: only use this function if you are sure that
3777 * the task cannot run in parallel!
3779 void __debug_show_held_locks(struct task_struct *task)
3781 if (unlikely(!debug_locks)) {
3782 printk("INFO: lockdep is turned off.\n");
3785 lockdep_print_held_locks(task);
3787 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3789 void debug_show_held_locks(struct task_struct *task)
3791 __debug_show_held_locks(task);
3793 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3795 void lockdep_sys_exit(void)
3797 struct task_struct *curr = current;
3799 if (unlikely(curr->lockdep_depth)) {
3800 if (!debug_locks_off())
3802 printk("\n================================================\n");
3803 printk( "[ BUG: lock held when returning to user space! ]\n");
3804 printk( "------------------------------------------------\n");
3805 printk("%s/%d is leaving the kernel with locks still held!\n",
3806 curr->comm, curr->pid);
3807 lockdep_print_held_locks(curr);