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/lockdep.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 int lock_point(unsigned long points[], unsigned long ip)
149 for (i = 0; i < LOCKSTAT_POINTS; i++) {
150 if (points[i] == 0) {
161 static void lock_time_inc(struct lock_time *lt, s64 time)
166 if (time < lt->min || !lt->min)
173 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
175 dst->min += src->min;
176 dst->max += src->max;
177 dst->total += src->total;
181 struct lock_class_stats lock_stats(struct lock_class *class)
183 struct lock_class_stats stats;
186 memset(&stats, 0, sizeof(struct lock_class_stats));
187 for_each_possible_cpu(cpu) {
188 struct lock_class_stats *pcs =
189 &per_cpu(lock_stats, cpu)[class - lock_classes];
191 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
192 stats.contention_point[i] += pcs->contention_point[i];
194 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
195 stats.contending_point[i] += pcs->contending_point[i];
197 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
198 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
200 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
201 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
203 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
204 stats.bounces[i] += pcs->bounces[i];
210 void clear_lock_stats(struct lock_class *class)
214 for_each_possible_cpu(cpu) {
215 struct lock_class_stats *cpu_stats =
216 &per_cpu(lock_stats, cpu)[class - lock_classes];
218 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
220 memset(class->contention_point, 0, sizeof(class->contention_point));
221 memset(class->contending_point, 0, sizeof(class->contending_point));
224 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
226 return &get_cpu_var(lock_stats)[class - lock_classes];
229 static void put_lock_stats(struct lock_class_stats *stats)
231 put_cpu_var(lock_stats);
234 static void lock_release_holdtime(struct held_lock *hlock)
236 struct lock_class_stats *stats;
242 holdtime = sched_clock() - hlock->holdtime_stamp;
244 stats = get_lock_stats(hlock_class(hlock));
246 lock_time_inc(&stats->read_holdtime, holdtime);
248 lock_time_inc(&stats->write_holdtime, holdtime);
249 put_lock_stats(stats);
252 static inline void lock_release_holdtime(struct held_lock *hlock)
258 * We keep a global list of all lock classes. The list only grows,
259 * never shrinks. The list is only accessed with the lockdep
260 * spinlock lock held.
262 LIST_HEAD(all_lock_classes);
265 * The lockdep classes are in a hash-table as well, for fast lookup:
267 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
268 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
269 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
270 #define classhashentry(key) (classhash_table + __classhashfn((key)))
272 static struct list_head classhash_table[CLASSHASH_SIZE];
275 * We put the lock dependency chains into a hash-table as well, to cache
278 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
279 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
280 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
281 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
283 static struct list_head chainhash_table[CHAINHASH_SIZE];
286 * The hash key of the lock dependency chains is a hash itself too:
287 * it's a hash of all locks taken up to that lock, including that lock.
288 * It's a 64-bit hash, because it's important for the keys to be
291 #define iterate_chain_key(key1, key2) \
292 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
293 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
296 void lockdep_off(void)
298 current->lockdep_recursion++;
300 EXPORT_SYMBOL(lockdep_off);
302 void lockdep_on(void)
304 current->lockdep_recursion--;
306 EXPORT_SYMBOL(lockdep_on);
309 * Debugging switches:
313 #define VERY_VERBOSE 0
316 # define HARDIRQ_VERBOSE 1
317 # define SOFTIRQ_VERBOSE 1
318 # define RECLAIM_VERBOSE 1
320 # define HARDIRQ_VERBOSE 0
321 # define SOFTIRQ_VERBOSE 0
322 # define RECLAIM_VERBOSE 0
325 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
327 * Quick filtering for interesting events:
329 static int class_filter(struct lock_class *class)
333 if (class->name_version == 1 &&
334 !strcmp(class->name, "lockname"))
336 if (class->name_version == 1 &&
337 !strcmp(class->name, "&struct->lockfield"))
340 /* Filter everything else. 1 would be to allow everything else */
345 static int verbose(struct lock_class *class)
348 return class_filter(class);
354 * Stack-trace: tightly packed array of stack backtrace
355 * addresses. Protected by the graph_lock.
357 unsigned long nr_stack_trace_entries;
358 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
360 static int save_trace(struct stack_trace *trace)
362 trace->nr_entries = 0;
363 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
364 trace->entries = stack_trace + nr_stack_trace_entries;
368 save_stack_trace(trace);
371 * Some daft arches put -1 at the end to indicate its a full trace.
373 * <rant> this is buggy anyway, since it takes a whole extra entry so a
374 * complete trace that maxes out the entries provided will be reported
375 * as incomplete, friggin useless </rant>
377 if (trace->entries[trace->nr_entries-1] == ULONG_MAX)
380 trace->max_entries = trace->nr_entries;
382 nr_stack_trace_entries += trace->nr_entries;
384 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
385 if (!debug_locks_off_graph_unlock())
388 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
389 printk("turning off the locking correctness validator.\n");
398 unsigned int nr_hardirq_chains;
399 unsigned int nr_softirq_chains;
400 unsigned int nr_process_chains;
401 unsigned int max_lockdep_depth;
402 unsigned int max_recursion_depth;
404 #ifdef CONFIG_DEBUG_LOCKDEP
406 * We cannot printk in early bootup code. Not even early_printk()
407 * might work. So we mark any initialization errors and printk
408 * about it later on, in lockdep_info().
410 static int lockdep_init_error;
411 static unsigned long lockdep_init_trace_data[20];
412 static struct stack_trace lockdep_init_trace = {
413 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
414 .entries = lockdep_init_trace_data,
418 * Various lockdep statistics:
420 atomic_t chain_lookup_hits;
421 atomic_t chain_lookup_misses;
422 atomic_t hardirqs_on_events;
423 atomic_t hardirqs_off_events;
424 atomic_t redundant_hardirqs_on;
425 atomic_t redundant_hardirqs_off;
426 atomic_t softirqs_on_events;
427 atomic_t softirqs_off_events;
428 atomic_t redundant_softirqs_on;
429 atomic_t redundant_softirqs_off;
430 atomic_t nr_unused_locks;
431 atomic_t nr_cyclic_checks;
432 atomic_t nr_cyclic_check_recursions;
433 atomic_t nr_find_usage_forwards_checks;
434 atomic_t nr_find_usage_forwards_recursions;
435 atomic_t nr_find_usage_backwards_checks;
436 atomic_t nr_find_usage_backwards_recursions;
443 #define __USAGE(__STATE) \
444 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
445 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
446 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
447 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
449 static const char *usage_str[] =
451 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
452 #include "lockdep_states.h"
454 [LOCK_USED] = "INITIAL USE",
457 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
459 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
462 static inline unsigned long lock_flag(enum lock_usage_bit bit)
467 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
471 if (class->usage_mask & lock_flag(bit + 2))
473 if (class->usage_mask & lock_flag(bit)) {
475 if (class->usage_mask & lock_flag(bit + 2))
482 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
486 #define LOCKDEP_STATE(__STATE) \
487 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
488 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
489 #include "lockdep_states.h"
495 static void print_lock_name(struct lock_class *class)
497 char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
500 get_usage_chars(class, usage);
504 name = __get_key_name(class->key, str);
505 printk(" (%s", name);
507 printk(" (%s", name);
508 if (class->name_version > 1)
509 printk("#%d", class->name_version);
511 printk("/%d", class->subclass);
513 printk("){%s}", usage);
516 static void print_lockdep_cache(struct lockdep_map *lock)
519 char str[KSYM_NAME_LEN];
523 name = __get_key_name(lock->key->subkeys, str);
528 static void print_lock(struct held_lock *hlock)
530 print_lock_name(hlock_class(hlock));
532 print_ip_sym(hlock->acquire_ip);
535 static void lockdep_print_held_locks(struct task_struct *curr)
537 int i, depth = curr->lockdep_depth;
540 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
543 printk("%d lock%s held by %s/%d:\n",
544 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
546 for (i = 0; i < depth; i++) {
548 print_lock(curr->held_locks + i);
552 static void print_kernel_version(void)
554 printk("%s %.*s\n", init_utsname()->release,
555 (int)strcspn(init_utsname()->version, " "),
556 init_utsname()->version);
559 static int very_verbose(struct lock_class *class)
562 return class_filter(class);
568 * Is this the address of a static object:
570 static int static_obj(void *obj)
572 unsigned long start = (unsigned long) &_stext,
573 end = (unsigned long) &_end,
574 addr = (unsigned long) obj;
582 if ((addr >= start) && (addr < end))
589 for_each_possible_cpu(i) {
590 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
591 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
594 if ((addr >= start) && (addr < end))
602 return is_module_address(addr);
606 * To make lock name printouts unique, we calculate a unique
607 * class->name_version generation counter:
609 static int count_matching_names(struct lock_class *new_class)
611 struct lock_class *class;
614 if (!new_class->name)
617 list_for_each_entry(class, &all_lock_classes, lock_entry) {
618 if (new_class->key - new_class->subclass == class->key)
619 return class->name_version;
620 if (class->name && !strcmp(class->name, new_class->name))
621 count = max(count, class->name_version);
628 * Register a lock's class in the hash-table, if the class is not present
629 * yet. Otherwise we look it up. We cache the result in the lock object
630 * itself, so actual lookup of the hash should be once per lock object.
632 static inline struct lock_class *
633 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
635 struct lockdep_subclass_key *key;
636 struct list_head *hash_head;
637 struct lock_class *class;
639 #ifdef CONFIG_DEBUG_LOCKDEP
641 * If the architecture calls into lockdep before initializing
642 * the hashes then we'll warn about it later. (we cannot printk
645 if (unlikely(!lockdep_initialized)) {
647 lockdep_init_error = 1;
648 save_stack_trace(&lockdep_init_trace);
653 * Static locks do not have their class-keys yet - for them the key
654 * is the lock object itself:
656 if (unlikely(!lock->key))
657 lock->key = (void *)lock;
660 * NOTE: the class-key must be unique. For dynamic locks, a static
661 * lock_class_key variable is passed in through the mutex_init()
662 * (or spin_lock_init()) call - which acts as the key. For static
663 * locks we use the lock object itself as the key.
665 BUILD_BUG_ON(sizeof(struct lock_class_key) >
666 sizeof(struct lockdep_map));
668 key = lock->key->subkeys + subclass;
670 hash_head = classhashentry(key);
673 * We can walk the hash lockfree, because the hash only
674 * grows, and we are careful when adding entries to the end:
676 list_for_each_entry(class, hash_head, hash_entry) {
677 if (class->key == key) {
678 WARN_ON_ONCE(class->name != lock->name);
687 * Register a lock's class in the hash-table, if the class is not present
688 * yet. Otherwise we look it up. We cache the result in the lock object
689 * itself, so actual lookup of the hash should be once per lock object.
691 static inline struct lock_class *
692 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
694 struct lockdep_subclass_key *key;
695 struct list_head *hash_head;
696 struct lock_class *class;
699 class = look_up_lock_class(lock, subclass);
704 * Debug-check: all keys must be persistent!
706 if (!static_obj(lock->key)) {
708 printk("INFO: trying to register non-static key.\n");
709 printk("the code is fine but needs lockdep annotation.\n");
710 printk("turning off the locking correctness validator.\n");
716 key = lock->key->subkeys + subclass;
717 hash_head = classhashentry(key);
719 raw_local_irq_save(flags);
721 raw_local_irq_restore(flags);
725 * We have to do the hash-walk again, to avoid races
728 list_for_each_entry(class, hash_head, hash_entry)
729 if (class->key == key)
732 * Allocate a new key from the static array, and add it to
735 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
736 if (!debug_locks_off_graph_unlock()) {
737 raw_local_irq_restore(flags);
740 raw_local_irq_restore(flags);
742 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
743 printk("turning off the locking correctness validator.\n");
747 class = lock_classes + nr_lock_classes++;
748 debug_atomic_inc(&nr_unused_locks);
750 class->name = lock->name;
751 class->subclass = subclass;
752 INIT_LIST_HEAD(&class->lock_entry);
753 INIT_LIST_HEAD(&class->locks_before);
754 INIT_LIST_HEAD(&class->locks_after);
755 class->name_version = count_matching_names(class);
757 * We use RCU's safe list-add method to make
758 * parallel walking of the hash-list safe:
760 list_add_tail_rcu(&class->hash_entry, hash_head);
762 * Add it to the global list of classes:
764 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
766 if (verbose(class)) {
768 raw_local_irq_restore(flags);
770 printk("\nnew class %p: %s", class->key, class->name);
771 if (class->name_version > 1)
772 printk("#%d", class->name_version);
776 raw_local_irq_save(flags);
778 raw_local_irq_restore(flags);
784 raw_local_irq_restore(flags);
786 if (!subclass || force)
787 lock->class_cache = class;
789 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
795 #ifdef CONFIG_PROVE_LOCKING
797 * Allocate a lockdep entry. (assumes the graph_lock held, returns
798 * with NULL on failure)
800 static struct lock_list *alloc_list_entry(void)
802 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
803 if (!debug_locks_off_graph_unlock())
806 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
807 printk("turning off the locking correctness validator.\n");
811 return list_entries + nr_list_entries++;
815 * Add a new dependency to the head of the list:
817 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
818 struct list_head *head, unsigned long ip, int distance)
820 struct lock_list *entry;
822 * Lock not present yet - get a new dependency struct and
823 * add it to the list:
825 entry = alloc_list_entry();
829 if (!save_trace(&entry->trace))
833 entry->distance = distance;
835 * Since we never remove from the dependency list, the list can
836 * be walked lockless by other CPUs, it's only allocation
837 * that must be protected by the spinlock. But this also means
838 * we must make new entries visible only once writes to the
839 * entry become visible - hence the RCU op:
841 list_add_tail_rcu(&entry->entry, head);
846 /*For good efficiency of modular, we use power of 2*/
847 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
848 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
850 /* The circular_queue and helpers is used to implement the
851 * breadth-first search(BFS)algorithem, by which we can build
852 * the shortest path from the next lock to be acquired to the
853 * previous held lock if there is a circular between them.
855 struct circular_queue {
856 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
857 unsigned int front, rear;
860 static struct circular_queue lock_cq;
861 static unsigned long bfs_accessed[BITS_TO_LONGS(MAX_LOCKDEP_ENTRIES)];
863 unsigned int max_bfs_queue_depth;
865 static inline void __cq_init(struct circular_queue *cq)
867 cq->front = cq->rear = 0;
868 bitmap_zero(bfs_accessed, MAX_LOCKDEP_ENTRIES);
871 static inline int __cq_empty(struct circular_queue *cq)
873 return (cq->front == cq->rear);
876 static inline int __cq_full(struct circular_queue *cq)
878 return ((cq->rear + 1) & CQ_MASK) == cq->front;
881 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
886 cq->element[cq->rear] = elem;
887 cq->rear = (cq->rear + 1) & CQ_MASK;
891 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
896 *elem = cq->element[cq->front];
897 cq->front = (cq->front + 1) & CQ_MASK;
901 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
903 return (cq->rear - cq->front) & CQ_MASK;
906 static inline void mark_lock_accessed(struct lock_list *lock,
907 struct lock_list *parent)
910 nr = lock - list_entries;
911 WARN_ON(nr >= nr_list_entries);
912 lock->parent = parent;
913 set_bit(nr, bfs_accessed);
916 static inline unsigned long lock_accessed(struct lock_list *lock)
919 nr = lock - list_entries;
920 WARN_ON(nr >= nr_list_entries);
921 return test_bit(nr, bfs_accessed);
924 static inline struct lock_list *get_lock_parent(struct lock_list *child)
926 return child->parent;
929 static inline int get_lock_depth(struct lock_list *child)
932 struct lock_list *parent;
934 while ((parent = get_lock_parent(child))) {
941 static int __bfs(struct lock_list *source_entry,
943 int (*match)(struct lock_list *entry, void *data),
944 struct lock_list **target_entry,
947 struct lock_list *entry;
948 struct list_head *head;
949 struct circular_queue *cq = &lock_cq;
952 if (match(source_entry, data)) {
953 *target_entry = source_entry;
959 head = &source_entry->class->locks_after;
961 head = &source_entry->class->locks_before;
963 if (list_empty(head))
967 __cq_enqueue(cq, (unsigned long)source_entry);
969 while (!__cq_empty(cq)) {
970 struct lock_list *lock;
972 __cq_dequeue(cq, (unsigned long *)&lock);
980 head = &lock->class->locks_after;
982 head = &lock->class->locks_before;
984 list_for_each_entry(entry, head, entry) {
985 if (!lock_accessed(entry)) {
986 unsigned int cq_depth;
987 mark_lock_accessed(entry, lock);
988 if (match(entry, data)) {
989 *target_entry = entry;
994 if (__cq_enqueue(cq, (unsigned long)entry)) {
998 cq_depth = __cq_get_elem_count(cq);
999 if (max_bfs_queue_depth < cq_depth)
1000 max_bfs_queue_depth = cq_depth;
1008 static inline int __bfs_forwards(struct lock_list *src_entry,
1010 int (*match)(struct lock_list *entry, void *data),
1011 struct lock_list **target_entry)
1013 return __bfs(src_entry, data, match, target_entry, 1);
1017 static inline int __bfs_backwards(struct lock_list *src_entry,
1019 int (*match)(struct lock_list *entry, void *data),
1020 struct lock_list **target_entry)
1022 return __bfs(src_entry, data, match, target_entry, 0);
1027 * Recursive, forwards-direction lock-dependency checking, used for
1028 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1033 * Print a dependency chain entry (this is only done when a deadlock
1034 * has been detected):
1037 print_circular_bug_entry(struct lock_list *target, int depth)
1039 if (debug_locks_silent)
1041 printk("\n-> #%u", depth);
1042 print_lock_name(target->class);
1044 print_stack_trace(&target->trace, 6);
1050 * When a circular dependency is detected, print the
1054 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1055 struct held_lock *check_src,
1056 struct held_lock *check_tgt)
1058 struct task_struct *curr = current;
1060 if (debug_locks_silent)
1063 printk("\n=======================================================\n");
1064 printk( "[ INFO: possible circular locking dependency detected ]\n");
1065 print_kernel_version();
1066 printk( "-------------------------------------------------------\n");
1067 printk("%s/%d is trying to acquire lock:\n",
1068 curr->comm, task_pid_nr(curr));
1069 print_lock(check_src);
1070 printk("\nbut task is already holding lock:\n");
1071 print_lock(check_tgt);
1072 printk("\nwhich lock already depends on the new lock.\n\n");
1073 printk("\nthe existing dependency chain (in reverse order) is:\n");
1075 print_circular_bug_entry(entry, depth);
1080 static inline int class_equal(struct lock_list *entry, void *data)
1082 return entry->class == data;
1085 static noinline int print_circular_bug(struct lock_list *this,
1086 struct lock_list *target,
1087 struct held_lock *check_src,
1088 struct held_lock *check_tgt)
1090 struct task_struct *curr = current;
1091 struct lock_list *parent;
1094 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1097 if (!save_trace(&this->trace))
1100 depth = get_lock_depth(target);
1102 print_circular_bug_header(target, depth, check_src, check_tgt);
1104 parent = get_lock_parent(target);
1107 print_circular_bug_entry(parent, --depth);
1108 parent = get_lock_parent(parent);
1111 printk("\nother info that might help us debug this:\n\n");
1112 lockdep_print_held_locks(curr);
1114 printk("\nstack backtrace:\n");
1120 static noinline int print_bfs_bug(int ret)
1122 if (!debug_locks_off_graph_unlock())
1125 WARN(1, "lockdep bfs error:%d\n", ret);
1130 static int noop_count(struct lock_list *entry, void *data)
1132 (*(unsigned long *)data)++;
1136 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1138 unsigned long count = 0;
1139 struct lock_list *uninitialized_var(target_entry);
1141 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1145 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1147 unsigned long ret, flags;
1148 struct lock_list this;
1153 local_irq_save(flags);
1154 __raw_spin_lock(&lockdep_lock);
1155 ret = __lockdep_count_forward_deps(&this);
1156 __raw_spin_unlock(&lockdep_lock);
1157 local_irq_restore(flags);
1162 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1164 unsigned long count = 0;
1165 struct lock_list *uninitialized_var(target_entry);
1167 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1172 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1174 unsigned long ret, flags;
1175 struct lock_list this;
1180 local_irq_save(flags);
1181 __raw_spin_lock(&lockdep_lock);
1182 ret = __lockdep_count_backward_deps(&this);
1183 __raw_spin_unlock(&lockdep_lock);
1184 local_irq_restore(flags);
1190 * Prove that the dependency graph starting at <entry> can not
1191 * lead to <target>. Print an error and return 0 if it does.
1194 check_noncircular(struct lock_list *root, struct lock_class *target,
1195 struct lock_list **target_entry)
1199 debug_atomic_inc(&nr_cyclic_checks);
1201 result = __bfs_forwards(root, target, class_equal, target_entry);
1206 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1208 * Forwards and backwards subgraph searching, for the purposes of
1209 * proving that two subgraphs can be connected by a new dependency
1210 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1213 static inline int usage_match(struct lock_list *entry, void *bit)
1215 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1221 * Find a node in the forwards-direction dependency sub-graph starting
1222 * at @root->class that matches @bit.
1224 * Return 0 if such a node exists in the subgraph, and put that node
1225 * into *@target_entry.
1227 * Return 1 otherwise and keep *@target_entry unchanged.
1228 * Return <0 on error.
1231 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1232 struct lock_list **target_entry)
1236 debug_atomic_inc(&nr_find_usage_forwards_checks);
1238 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1244 * Find a node in the backwards-direction dependency sub-graph starting
1245 * at @root->class that matches @bit.
1247 * Return 0 if such a node exists in the subgraph, and put that node
1248 * into *@target_entry.
1250 * Return 1 otherwise and keep *@target_entry unchanged.
1251 * Return <0 on error.
1254 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1255 struct lock_list **target_entry)
1259 debug_atomic_inc(&nr_find_usage_backwards_checks);
1261 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1266 static void print_lock_class_header(struct lock_class *class, int depth)
1270 printk("%*s->", depth, "");
1271 print_lock_name(class);
1272 printk(" ops: %lu", class->ops);
1275 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1276 if (class->usage_mask & (1 << bit)) {
1279 len += printk("%*s %s", depth, "", usage_str[bit]);
1280 len += printk(" at:\n");
1281 print_stack_trace(class->usage_traces + bit, len);
1284 printk("%*s }\n", depth, "");
1286 printk("%*s ... key at: ",depth,"");
1287 print_ip_sym((unsigned long)class->key);
1291 * printk the shortest lock dependencies from @start to @end in reverse order:
1294 print_shortest_lock_dependencies(struct lock_list *leaf,
1295 struct lock_list *root)
1297 struct lock_list *entry = leaf;
1300 /*compute depth from generated tree by BFS*/
1301 depth = get_lock_depth(leaf);
1304 print_lock_class_header(entry->class, depth);
1305 printk("%*s ... acquired at:\n", depth, "");
1306 print_stack_trace(&entry->trace, 2);
1309 if (depth == 0 && (entry != root)) {
1310 printk("lockdep:%s bad BFS generated tree\n", __func__);
1314 entry = get_lock_parent(entry);
1316 } while (entry && (depth >= 0));
1322 print_bad_irq_dependency(struct task_struct *curr,
1323 struct lock_list *prev_root,
1324 struct lock_list *next_root,
1325 struct lock_list *backwards_entry,
1326 struct lock_list *forwards_entry,
1327 struct held_lock *prev,
1328 struct held_lock *next,
1329 enum lock_usage_bit bit1,
1330 enum lock_usage_bit bit2,
1331 const char *irqclass)
1333 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1336 printk("\n======================================================\n");
1337 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1338 irqclass, irqclass);
1339 print_kernel_version();
1340 printk( "------------------------------------------------------\n");
1341 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1342 curr->comm, task_pid_nr(curr),
1343 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1344 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1345 curr->hardirqs_enabled,
1346 curr->softirqs_enabled);
1349 printk("\nand this task is already holding:\n");
1351 printk("which would create a new lock dependency:\n");
1352 print_lock_name(hlock_class(prev));
1354 print_lock_name(hlock_class(next));
1357 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1359 print_lock_name(backwards_entry->class);
1360 printk("\n... which became %s-irq-safe at:\n", irqclass);
1362 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1364 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1365 print_lock_name(forwards_entry->class);
1366 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1369 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1371 printk("\nother info that might help us debug this:\n\n");
1372 lockdep_print_held_locks(curr);
1374 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1375 printk(" and the holding lock:\n");
1376 if (!save_trace(&prev_root->trace))
1378 print_shortest_lock_dependencies(backwards_entry, prev_root);
1380 printk("\nthe dependencies between the lock to be acquired");
1381 printk(" and %s-irq-unsafe lock:\n", irqclass);
1382 if (!save_trace(&next_root->trace))
1384 print_shortest_lock_dependencies(forwards_entry, next_root);
1386 printk("\nstack backtrace:\n");
1393 check_usage(struct task_struct *curr, struct held_lock *prev,
1394 struct held_lock *next, enum lock_usage_bit bit_backwards,
1395 enum lock_usage_bit bit_forwards, const char *irqclass)
1398 struct lock_list this, that;
1399 struct lock_list *uninitialized_var(target_entry);
1400 struct lock_list *uninitialized_var(target_entry1);
1404 this.class = hlock_class(prev);
1405 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1407 return print_bfs_bug(ret);
1412 that.class = hlock_class(next);
1413 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1415 return print_bfs_bug(ret);
1419 return print_bad_irq_dependency(curr, &this, &that,
1420 target_entry, target_entry1,
1422 bit_backwards, bit_forwards, irqclass);
1425 static const char *state_names[] = {
1426 #define LOCKDEP_STATE(__STATE) \
1427 __stringify(__STATE),
1428 #include "lockdep_states.h"
1429 #undef LOCKDEP_STATE
1432 static const char *state_rnames[] = {
1433 #define LOCKDEP_STATE(__STATE) \
1434 __stringify(__STATE)"-READ",
1435 #include "lockdep_states.h"
1436 #undef LOCKDEP_STATE
1439 static inline const char *state_name(enum lock_usage_bit bit)
1441 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1444 static int exclusive_bit(int new_bit)
1452 * bit 0 - write/read
1453 * bit 1 - used_in/enabled
1457 int state = new_bit & ~3;
1458 int dir = new_bit & 2;
1461 * keep state, bit flip the direction and strip read.
1463 return state | (dir ^ 2);
1466 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1467 struct held_lock *next, enum lock_usage_bit bit)
1470 * Prove that the new dependency does not connect a hardirq-safe
1471 * lock with a hardirq-unsafe lock - to achieve this we search
1472 * the backwards-subgraph starting at <prev>, and the
1473 * forwards-subgraph starting at <next>:
1475 if (!check_usage(curr, prev, next, bit,
1476 exclusive_bit(bit), state_name(bit)))
1482 * Prove that the new dependency does not connect a hardirq-safe-read
1483 * lock with a hardirq-unsafe lock - to achieve this we search
1484 * the backwards-subgraph starting at <prev>, and the
1485 * forwards-subgraph starting at <next>:
1487 if (!check_usage(curr, prev, next, bit,
1488 exclusive_bit(bit), state_name(bit)))
1495 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1496 struct held_lock *next)
1498 #define LOCKDEP_STATE(__STATE) \
1499 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1501 #include "lockdep_states.h"
1502 #undef LOCKDEP_STATE
1507 static void inc_chains(void)
1509 if (current->hardirq_context)
1510 nr_hardirq_chains++;
1512 if (current->softirq_context)
1513 nr_softirq_chains++;
1515 nr_process_chains++;
1522 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1523 struct held_lock *next)
1528 static inline void inc_chains(void)
1530 nr_process_chains++;
1536 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1537 struct held_lock *next)
1539 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1542 printk("\n=============================================\n");
1543 printk( "[ INFO: possible recursive locking detected ]\n");
1544 print_kernel_version();
1545 printk( "---------------------------------------------\n");
1546 printk("%s/%d is trying to acquire lock:\n",
1547 curr->comm, task_pid_nr(curr));
1549 printk("\nbut task is already holding lock:\n");
1552 printk("\nother info that might help us debug this:\n");
1553 lockdep_print_held_locks(curr);
1555 printk("\nstack backtrace:\n");
1562 * Check whether we are holding such a class already.
1564 * (Note that this has to be done separately, because the graph cannot
1565 * detect such classes of deadlocks.)
1567 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1570 check_deadlock(struct task_struct *curr, struct held_lock *next,
1571 struct lockdep_map *next_instance, int read)
1573 struct held_lock *prev;
1574 struct held_lock *nest = NULL;
1577 for (i = 0; i < curr->lockdep_depth; i++) {
1578 prev = curr->held_locks + i;
1580 if (prev->instance == next->nest_lock)
1583 if (hlock_class(prev) != hlock_class(next))
1587 * Allow read-after-read recursion of the same
1588 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1590 if ((read == 2) && prev->read)
1594 * We're holding the nest_lock, which serializes this lock's
1595 * nesting behaviour.
1600 return print_deadlock_bug(curr, prev, next);
1606 * There was a chain-cache miss, and we are about to add a new dependency
1607 * to a previous lock. We recursively validate the following rules:
1609 * - would the adding of the <prev> -> <next> dependency create a
1610 * circular dependency in the graph? [== circular deadlock]
1612 * - does the new prev->next dependency connect any hardirq-safe lock
1613 * (in the full backwards-subgraph starting at <prev>) with any
1614 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1615 * <next>)? [== illegal lock inversion with hardirq contexts]
1617 * - does the new prev->next dependency connect any softirq-safe lock
1618 * (in the full backwards-subgraph starting at <prev>) with any
1619 * softirq-unsafe lock (in the full forwards-subgraph starting at
1620 * <next>)? [== illegal lock inversion with softirq contexts]
1622 * any of these scenarios could lead to a deadlock.
1624 * Then if all the validations pass, we add the forwards and backwards
1628 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1629 struct held_lock *next, int distance)
1631 struct lock_list *entry;
1633 struct lock_list this;
1634 struct lock_list *uninitialized_var(target_entry);
1637 * Prove that the new <prev> -> <next> dependency would not
1638 * create a circular dependency in the graph. (We do this by
1639 * forward-recursing into the graph starting at <next>, and
1640 * checking whether we can reach <prev>.)
1642 * We are using global variables to control the recursion, to
1643 * keep the stackframe size of the recursive functions low:
1645 this.class = hlock_class(next);
1647 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1649 return print_circular_bug(&this, target_entry, next, prev);
1650 else if (unlikely(ret < 0))
1651 return print_bfs_bug(ret);
1653 if (!check_prev_add_irq(curr, prev, next))
1657 * For recursive read-locks we do all the dependency checks,
1658 * but we dont store read-triggered dependencies (only
1659 * write-triggered dependencies). This ensures that only the
1660 * write-side dependencies matter, and that if for example a
1661 * write-lock never takes any other locks, then the reads are
1662 * equivalent to a NOP.
1664 if (next->read == 2 || prev->read == 2)
1667 * Is the <prev> -> <next> dependency already present?
1669 * (this may occur even though this is a new chain: consider
1670 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1671 * chains - the second one will be new, but L1 already has
1672 * L2 added to its dependency list, due to the first chain.)
1674 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1675 if (entry->class == hlock_class(next)) {
1677 entry->distance = 1;
1683 * Ok, all validations passed, add the new lock
1684 * to the previous lock's dependency list:
1686 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1687 &hlock_class(prev)->locks_after,
1688 next->acquire_ip, distance);
1693 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1694 &hlock_class(next)->locks_before,
1695 next->acquire_ip, distance);
1700 * Debugging printouts:
1702 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1704 printk("\n new dependency: ");
1705 print_lock_name(hlock_class(prev));
1707 print_lock_name(hlock_class(next));
1710 return graph_lock();
1716 * Add the dependency to all directly-previous locks that are 'relevant'.
1717 * The ones that are relevant are (in increasing distance from curr):
1718 * all consecutive trylock entries and the final non-trylock entry - or
1719 * the end of this context's lock-chain - whichever comes first.
1722 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1724 int depth = curr->lockdep_depth;
1725 struct held_lock *hlock;
1730 * Depth must not be zero for a non-head lock:
1735 * At least two relevant locks must exist for this
1738 if (curr->held_locks[depth].irq_context !=
1739 curr->held_locks[depth-1].irq_context)
1743 int distance = curr->lockdep_depth - depth + 1;
1744 hlock = curr->held_locks + depth-1;
1746 * Only non-recursive-read entries get new dependencies
1749 if (hlock->read != 2) {
1750 if (!check_prev_add(curr, hlock, next, distance))
1753 * Stop after the first non-trylock entry,
1754 * as non-trylock entries have added their
1755 * own direct dependencies already, so this
1756 * lock is connected to them indirectly:
1758 if (!hlock->trylock)
1763 * End of lock-stack?
1768 * Stop the search if we cross into another context:
1770 if (curr->held_locks[depth].irq_context !=
1771 curr->held_locks[depth-1].irq_context)
1776 if (!debug_locks_off_graph_unlock())
1784 unsigned long nr_lock_chains;
1785 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1786 int nr_chain_hlocks;
1787 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1789 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1791 return lock_classes + chain_hlocks[chain->base + i];
1795 * Look up a dependency chain. If the key is not present yet then
1796 * add it and return 1 - in this case the new dependency chain is
1797 * validated. If the key is already hashed, return 0.
1798 * (On return with 1 graph_lock is held.)
1800 static inline int lookup_chain_cache(struct task_struct *curr,
1801 struct held_lock *hlock,
1804 struct lock_class *class = hlock_class(hlock);
1805 struct list_head *hash_head = chainhashentry(chain_key);
1806 struct lock_chain *chain;
1807 struct held_lock *hlock_curr, *hlock_next;
1810 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1813 * We can walk it lock-free, because entries only get added
1816 list_for_each_entry(chain, hash_head, entry) {
1817 if (chain->chain_key == chain_key) {
1819 debug_atomic_inc(&chain_lookup_hits);
1820 if (very_verbose(class))
1821 printk("\nhash chain already cached, key: "
1822 "%016Lx tail class: [%p] %s\n",
1823 (unsigned long long)chain_key,
1824 class->key, class->name);
1828 if (very_verbose(class))
1829 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1830 (unsigned long long)chain_key, class->key, class->name);
1832 * Allocate a new chain entry from the static array, and add
1838 * We have to walk the chain again locked - to avoid duplicates:
1840 list_for_each_entry(chain, hash_head, entry) {
1841 if (chain->chain_key == chain_key) {
1846 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1847 if (!debug_locks_off_graph_unlock())
1850 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1851 printk("turning off the locking correctness validator.\n");
1855 chain = lock_chains + nr_lock_chains++;
1856 chain->chain_key = chain_key;
1857 chain->irq_context = hlock->irq_context;
1858 /* Find the first held_lock of current chain */
1860 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1861 hlock_curr = curr->held_locks + i;
1862 if (hlock_curr->irq_context != hlock_next->irq_context)
1867 chain->depth = curr->lockdep_depth + 1 - i;
1868 cn = nr_chain_hlocks;
1869 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1870 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1875 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1877 for (j = 0; j < chain->depth - 1; j++, i++) {
1878 int lock_id = curr->held_locks[i].class_idx - 1;
1879 chain_hlocks[chain->base + j] = lock_id;
1881 chain_hlocks[chain->base + j] = class - lock_classes;
1883 list_add_tail_rcu(&chain->entry, hash_head);
1884 debug_atomic_inc(&chain_lookup_misses);
1890 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1891 struct held_lock *hlock, int chain_head, u64 chain_key)
1894 * Trylock needs to maintain the stack of held locks, but it
1895 * does not add new dependencies, because trylock can be done
1898 * We look up the chain_key and do the O(N^2) check and update of
1899 * the dependencies only if this is a new dependency chain.
1900 * (If lookup_chain_cache() returns with 1 it acquires
1901 * graph_lock for us)
1903 if (!hlock->trylock && (hlock->check == 2) &&
1904 lookup_chain_cache(curr, hlock, chain_key)) {
1906 * Check whether last held lock:
1908 * - is irq-safe, if this lock is irq-unsafe
1909 * - is softirq-safe, if this lock is hardirq-unsafe
1911 * And check whether the new lock's dependency graph
1912 * could lead back to the previous lock.
1914 * any of these scenarios could lead to a deadlock. If
1917 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1922 * Mark recursive read, as we jump over it when
1923 * building dependencies (just like we jump over
1929 * Add dependency only if this lock is not the head
1930 * of the chain, and if it's not a secondary read-lock:
1932 if (!chain_head && ret != 2)
1933 if (!check_prevs_add(curr, hlock))
1937 /* after lookup_chain_cache(): */
1938 if (unlikely(!debug_locks))
1944 static inline int validate_chain(struct task_struct *curr,
1945 struct lockdep_map *lock, struct held_lock *hlock,
1946 int chain_head, u64 chain_key)
1953 * We are building curr_chain_key incrementally, so double-check
1954 * it from scratch, to make sure that it's done correctly:
1956 static void check_chain_key(struct task_struct *curr)
1958 #ifdef CONFIG_DEBUG_LOCKDEP
1959 struct held_lock *hlock, *prev_hlock = NULL;
1963 for (i = 0; i < curr->lockdep_depth; i++) {
1964 hlock = curr->held_locks + i;
1965 if (chain_key != hlock->prev_chain_key) {
1967 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1968 curr->lockdep_depth, i,
1969 (unsigned long long)chain_key,
1970 (unsigned long long)hlock->prev_chain_key);
1973 id = hlock->class_idx - 1;
1974 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1977 if (prev_hlock && (prev_hlock->irq_context !=
1978 hlock->irq_context))
1980 chain_key = iterate_chain_key(chain_key, id);
1983 if (chain_key != curr->curr_chain_key) {
1985 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1986 curr->lockdep_depth, i,
1987 (unsigned long long)chain_key,
1988 (unsigned long long)curr->curr_chain_key);
1994 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1995 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1997 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2000 printk("\n=================================\n");
2001 printk( "[ INFO: inconsistent lock state ]\n");
2002 print_kernel_version();
2003 printk( "---------------------------------\n");
2005 printk("inconsistent {%s} -> {%s} usage.\n",
2006 usage_str[prev_bit], usage_str[new_bit]);
2008 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2009 curr->comm, task_pid_nr(curr),
2010 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2011 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2012 trace_hardirqs_enabled(curr),
2013 trace_softirqs_enabled(curr));
2016 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2017 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2019 print_irqtrace_events(curr);
2020 printk("\nother info that might help us debug this:\n");
2021 lockdep_print_held_locks(curr);
2023 printk("\nstack backtrace:\n");
2030 * Print out an error if an invalid bit is set:
2033 valid_state(struct task_struct *curr, struct held_lock *this,
2034 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2036 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2037 return print_usage_bug(curr, this, bad_bit, new_bit);
2041 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2042 enum lock_usage_bit new_bit);
2044 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2047 * print irq inversion bug:
2050 print_irq_inversion_bug(struct task_struct *curr,
2051 struct lock_list *root, struct lock_list *other,
2052 struct held_lock *this, int forwards,
2053 const char *irqclass)
2055 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2058 printk("\n=========================================================\n");
2059 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
2060 print_kernel_version();
2061 printk( "---------------------------------------------------------\n");
2062 printk("%s/%d just changed the state of lock:\n",
2063 curr->comm, task_pid_nr(curr));
2066 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2068 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2069 print_lock_name(other->class);
2070 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2072 printk("\nother info that might help us debug this:\n");
2073 lockdep_print_held_locks(curr);
2075 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2076 if (!save_trace(&root->trace))
2078 print_shortest_lock_dependencies(other, root);
2080 printk("\nstack backtrace:\n");
2087 * Prove that in the forwards-direction subgraph starting at <this>
2088 * there is no lock matching <mask>:
2091 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2092 enum lock_usage_bit bit, const char *irqclass)
2095 struct lock_list root;
2096 struct lock_list *uninitialized_var(target_entry);
2099 root.class = hlock_class(this);
2100 ret = find_usage_forwards(&root, bit, &target_entry);
2102 return print_bfs_bug(ret);
2106 return print_irq_inversion_bug(curr, &root, target_entry,
2111 * Prove that in the backwards-direction subgraph starting at <this>
2112 * there is no lock matching <mask>:
2115 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2116 enum lock_usage_bit bit, const char *irqclass)
2119 struct lock_list root;
2120 struct lock_list *uninitialized_var(target_entry);
2123 root.class = hlock_class(this);
2124 ret = find_usage_backwards(&root, bit, &target_entry);
2126 return print_bfs_bug(ret);
2130 return print_irq_inversion_bug(curr, &root, target_entry,
2134 void print_irqtrace_events(struct task_struct *curr)
2136 printk("irq event stamp: %u\n", curr->irq_events);
2137 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2138 print_ip_sym(curr->hardirq_enable_ip);
2139 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2140 print_ip_sym(curr->hardirq_disable_ip);
2141 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2142 print_ip_sym(curr->softirq_enable_ip);
2143 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2144 print_ip_sym(curr->softirq_disable_ip);
2147 static int HARDIRQ_verbose(struct lock_class *class)
2150 return class_filter(class);
2155 static int SOFTIRQ_verbose(struct lock_class *class)
2158 return class_filter(class);
2163 static int RECLAIM_FS_verbose(struct lock_class *class)
2166 return class_filter(class);
2171 #define STRICT_READ_CHECKS 1
2173 static int (*state_verbose_f[])(struct lock_class *class) = {
2174 #define LOCKDEP_STATE(__STATE) \
2176 #include "lockdep_states.h"
2177 #undef LOCKDEP_STATE
2180 static inline int state_verbose(enum lock_usage_bit bit,
2181 struct lock_class *class)
2183 return state_verbose_f[bit >> 2](class);
2186 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2187 enum lock_usage_bit bit, const char *name);
2190 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2191 enum lock_usage_bit new_bit)
2193 int excl_bit = exclusive_bit(new_bit);
2194 int read = new_bit & 1;
2195 int dir = new_bit & 2;
2198 * mark USED_IN has to look forwards -- to ensure no dependency
2199 * has ENABLED state, which would allow recursion deadlocks.
2201 * mark ENABLED has to look backwards -- to ensure no dependee
2202 * has USED_IN state, which, again, would allow recursion deadlocks.
2204 check_usage_f usage = dir ?
2205 check_usage_backwards : check_usage_forwards;
2208 * Validate that this particular lock does not have conflicting
2211 if (!valid_state(curr, this, new_bit, excl_bit))
2215 * Validate that the lock dependencies don't have conflicting usage
2218 if ((!read || !dir || STRICT_READ_CHECKS) &&
2219 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2223 * Check for read in write conflicts
2226 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2229 if (STRICT_READ_CHECKS &&
2230 !usage(curr, this, excl_bit + 1,
2231 state_name(new_bit + 1)))
2235 if (state_verbose(new_bit, hlock_class(this)))
2242 #define LOCKDEP_STATE(__STATE) __STATE,
2243 #include "lockdep_states.h"
2244 #undef LOCKDEP_STATE
2248 * Mark all held locks with a usage bit:
2251 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2253 enum lock_usage_bit usage_bit;
2254 struct held_lock *hlock;
2257 for (i = 0; i < curr->lockdep_depth; i++) {
2258 hlock = curr->held_locks + i;
2260 usage_bit = 2 + (mark << 2); /* ENABLED */
2262 usage_bit += 1; /* READ */
2264 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2266 if (!mark_lock(curr, hlock, usage_bit))
2274 * Debugging helper: via this flag we know that we are in
2275 * 'early bootup code', and will warn about any invalid irqs-on event:
2277 static int early_boot_irqs_enabled;
2279 void early_boot_irqs_off(void)
2281 early_boot_irqs_enabled = 0;
2284 void early_boot_irqs_on(void)
2286 early_boot_irqs_enabled = 1;
2290 * Hardirqs will be enabled:
2292 void trace_hardirqs_on_caller(unsigned long ip)
2294 struct task_struct *curr = current;
2296 time_hardirqs_on(CALLER_ADDR0, ip);
2298 if (unlikely(!debug_locks || current->lockdep_recursion))
2301 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2304 if (unlikely(curr->hardirqs_enabled)) {
2305 debug_atomic_inc(&redundant_hardirqs_on);
2308 /* we'll do an OFF -> ON transition: */
2309 curr->hardirqs_enabled = 1;
2311 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2313 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2316 * We are going to turn hardirqs on, so set the
2317 * usage bit for all held locks:
2319 if (!mark_held_locks(curr, HARDIRQ))
2322 * If we have softirqs enabled, then set the usage
2323 * bit for all held locks. (disabled hardirqs prevented
2324 * this bit from being set before)
2326 if (curr->softirqs_enabled)
2327 if (!mark_held_locks(curr, SOFTIRQ))
2330 curr->hardirq_enable_ip = ip;
2331 curr->hardirq_enable_event = ++curr->irq_events;
2332 debug_atomic_inc(&hardirqs_on_events);
2334 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2336 void trace_hardirqs_on(void)
2338 trace_hardirqs_on_caller(CALLER_ADDR0);
2340 EXPORT_SYMBOL(trace_hardirqs_on);
2343 * Hardirqs were disabled:
2345 void trace_hardirqs_off_caller(unsigned long ip)
2347 struct task_struct *curr = current;
2349 time_hardirqs_off(CALLER_ADDR0, ip);
2351 if (unlikely(!debug_locks || current->lockdep_recursion))
2354 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2357 if (curr->hardirqs_enabled) {
2359 * We have done an ON -> OFF transition:
2361 curr->hardirqs_enabled = 0;
2362 curr->hardirq_disable_ip = ip;
2363 curr->hardirq_disable_event = ++curr->irq_events;
2364 debug_atomic_inc(&hardirqs_off_events);
2366 debug_atomic_inc(&redundant_hardirqs_off);
2368 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2370 void trace_hardirqs_off(void)
2372 trace_hardirqs_off_caller(CALLER_ADDR0);
2374 EXPORT_SYMBOL(trace_hardirqs_off);
2377 * Softirqs will be enabled:
2379 void trace_softirqs_on(unsigned long ip)
2381 struct task_struct *curr = current;
2383 if (unlikely(!debug_locks))
2386 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2389 if (curr->softirqs_enabled) {
2390 debug_atomic_inc(&redundant_softirqs_on);
2395 * We'll do an OFF -> ON transition:
2397 curr->softirqs_enabled = 1;
2398 curr->softirq_enable_ip = ip;
2399 curr->softirq_enable_event = ++curr->irq_events;
2400 debug_atomic_inc(&softirqs_on_events);
2402 * We are going to turn softirqs on, so set the
2403 * usage bit for all held locks, if hardirqs are
2406 if (curr->hardirqs_enabled)
2407 mark_held_locks(curr, SOFTIRQ);
2411 * Softirqs were disabled:
2413 void trace_softirqs_off(unsigned long ip)
2415 struct task_struct *curr = current;
2417 if (unlikely(!debug_locks))
2420 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2423 if (curr->softirqs_enabled) {
2425 * We have done an ON -> OFF transition:
2427 curr->softirqs_enabled = 0;
2428 curr->softirq_disable_ip = ip;
2429 curr->softirq_disable_event = ++curr->irq_events;
2430 debug_atomic_inc(&softirqs_off_events);
2431 DEBUG_LOCKS_WARN_ON(!softirq_count());
2433 debug_atomic_inc(&redundant_softirqs_off);
2436 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2438 struct task_struct *curr = current;
2440 if (unlikely(!debug_locks))
2443 /* no reclaim without waiting on it */
2444 if (!(gfp_mask & __GFP_WAIT))
2447 /* this guy won't enter reclaim */
2448 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2451 /* We're only interested __GFP_FS allocations for now */
2452 if (!(gfp_mask & __GFP_FS))
2455 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2458 mark_held_locks(curr, RECLAIM_FS);
2461 static void check_flags(unsigned long flags);
2463 void lockdep_trace_alloc(gfp_t gfp_mask)
2465 unsigned long flags;
2467 if (unlikely(current->lockdep_recursion))
2470 raw_local_irq_save(flags);
2472 current->lockdep_recursion = 1;
2473 __lockdep_trace_alloc(gfp_mask, flags);
2474 current->lockdep_recursion = 0;
2475 raw_local_irq_restore(flags);
2478 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2481 * If non-trylock use in a hardirq or softirq context, then
2482 * mark the lock as used in these contexts:
2484 if (!hlock->trylock) {
2486 if (curr->hardirq_context)
2487 if (!mark_lock(curr, hlock,
2488 LOCK_USED_IN_HARDIRQ_READ))
2490 if (curr->softirq_context)
2491 if (!mark_lock(curr, hlock,
2492 LOCK_USED_IN_SOFTIRQ_READ))
2495 if (curr->hardirq_context)
2496 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2498 if (curr->softirq_context)
2499 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2503 if (!hlock->hardirqs_off) {
2505 if (!mark_lock(curr, hlock,
2506 LOCK_ENABLED_HARDIRQ_READ))
2508 if (curr->softirqs_enabled)
2509 if (!mark_lock(curr, hlock,
2510 LOCK_ENABLED_SOFTIRQ_READ))
2513 if (!mark_lock(curr, hlock,
2514 LOCK_ENABLED_HARDIRQ))
2516 if (curr->softirqs_enabled)
2517 if (!mark_lock(curr, hlock,
2518 LOCK_ENABLED_SOFTIRQ))
2524 * We reuse the irq context infrastructure more broadly as a general
2525 * context checking code. This tests GFP_FS recursion (a lock taken
2526 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2529 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2531 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2534 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2542 static int separate_irq_context(struct task_struct *curr,
2543 struct held_lock *hlock)
2545 unsigned int depth = curr->lockdep_depth;
2548 * Keep track of points where we cross into an interrupt context:
2550 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2551 curr->softirq_context;
2553 struct held_lock *prev_hlock;
2555 prev_hlock = curr->held_locks + depth-1;
2557 * If we cross into another context, reset the
2558 * hash key (this also prevents the checking and the
2559 * adding of the dependency to 'prev'):
2561 if (prev_hlock->irq_context != hlock->irq_context)
2570 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2571 enum lock_usage_bit new_bit)
2577 static inline int mark_irqflags(struct task_struct *curr,
2578 struct held_lock *hlock)
2583 static inline int separate_irq_context(struct task_struct *curr,
2584 struct held_lock *hlock)
2589 void lockdep_trace_alloc(gfp_t gfp_mask)
2596 * Mark a lock with a usage bit, and validate the state transition:
2598 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2599 enum lock_usage_bit new_bit)
2601 unsigned int new_mask = 1 << new_bit, ret = 1;
2604 * If already set then do not dirty the cacheline,
2605 * nor do any checks:
2607 if (likely(hlock_class(this)->usage_mask & new_mask))
2613 * Make sure we didnt race:
2615 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2620 hlock_class(this)->usage_mask |= new_mask;
2622 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2626 #define LOCKDEP_STATE(__STATE) \
2627 case LOCK_USED_IN_##__STATE: \
2628 case LOCK_USED_IN_##__STATE##_READ: \
2629 case LOCK_ENABLED_##__STATE: \
2630 case LOCK_ENABLED_##__STATE##_READ:
2631 #include "lockdep_states.h"
2632 #undef LOCKDEP_STATE
2633 ret = mark_lock_irq(curr, this, new_bit);
2638 debug_atomic_dec(&nr_unused_locks);
2641 if (!debug_locks_off_graph_unlock())
2650 * We must printk outside of the graph_lock:
2653 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2655 print_irqtrace_events(curr);
2663 * Initialize a lock instance's lock-class mapping info:
2665 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2666 struct lock_class_key *key, int subclass)
2668 lock->class_cache = NULL;
2669 #ifdef CONFIG_LOCK_STAT
2670 lock->cpu = raw_smp_processor_id();
2673 if (DEBUG_LOCKS_WARN_ON(!name)) {
2674 lock->name = "NULL";
2680 if (DEBUG_LOCKS_WARN_ON(!key))
2683 * Sanity check, the lock-class key must be persistent:
2685 if (!static_obj(key)) {
2686 printk("BUG: key %p not in .data!\n", key);
2687 DEBUG_LOCKS_WARN_ON(1);
2692 if (unlikely(!debug_locks))
2696 register_lock_class(lock, subclass, 1);
2698 EXPORT_SYMBOL_GPL(lockdep_init_map);
2701 * This gets called for every mutex_lock*()/spin_lock*() operation.
2702 * We maintain the dependency maps and validate the locking attempt:
2704 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2705 int trylock, int read, int check, int hardirqs_off,
2706 struct lockdep_map *nest_lock, unsigned long ip)
2708 struct task_struct *curr = current;
2709 struct lock_class *class = NULL;
2710 struct held_lock *hlock;
2711 unsigned int depth, id;
2718 if (unlikely(!debug_locks))
2721 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2724 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2726 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2727 printk("turning off the locking correctness validator.\n");
2733 class = lock->class_cache;
2735 * Not cached yet or subclass?
2737 if (unlikely(!class)) {
2738 class = register_lock_class(lock, subclass, 0);
2742 debug_atomic_inc((atomic_t *)&class->ops);
2743 if (very_verbose(class)) {
2744 printk("\nacquire class [%p] %s", class->key, class->name);
2745 if (class->name_version > 1)
2746 printk("#%d", class->name_version);
2752 * Add the lock to the list of currently held locks.
2753 * (we dont increase the depth just yet, up until the
2754 * dependency checks are done)
2756 depth = curr->lockdep_depth;
2757 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2760 hlock = curr->held_locks + depth;
2761 if (DEBUG_LOCKS_WARN_ON(!class))
2763 hlock->class_idx = class - lock_classes + 1;
2764 hlock->acquire_ip = ip;
2765 hlock->instance = lock;
2766 hlock->nest_lock = nest_lock;
2767 hlock->trylock = trylock;
2769 hlock->check = check;
2770 hlock->hardirqs_off = !!hardirqs_off;
2771 #ifdef CONFIG_LOCK_STAT
2772 hlock->waittime_stamp = 0;
2773 hlock->holdtime_stamp = sched_clock();
2776 if (check == 2 && !mark_irqflags(curr, hlock))
2779 /* mark it as used: */
2780 if (!mark_lock(curr, hlock, LOCK_USED))
2784 * Calculate the chain hash: it's the combined hash of all the
2785 * lock keys along the dependency chain. We save the hash value
2786 * at every step so that we can get the current hash easily
2787 * after unlock. The chain hash is then used to cache dependency
2790 * The 'key ID' is what is the most compact key value to drive
2791 * the hash, not class->key.
2793 id = class - lock_classes;
2794 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2797 chain_key = curr->curr_chain_key;
2799 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2804 hlock->prev_chain_key = chain_key;
2805 if (separate_irq_context(curr, hlock)) {
2809 chain_key = iterate_chain_key(chain_key, id);
2811 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2814 curr->curr_chain_key = chain_key;
2815 curr->lockdep_depth++;
2816 check_chain_key(curr);
2817 #ifdef CONFIG_DEBUG_LOCKDEP
2818 if (unlikely(!debug_locks))
2821 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2823 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2824 printk("turning off the locking correctness validator.\n");
2829 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2830 max_lockdep_depth = curr->lockdep_depth;
2836 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2839 if (!debug_locks_off())
2841 if (debug_locks_silent)
2844 printk("\n=====================================\n");
2845 printk( "[ BUG: bad unlock balance detected! ]\n");
2846 printk( "-------------------------------------\n");
2847 printk("%s/%d is trying to release lock (",
2848 curr->comm, task_pid_nr(curr));
2849 print_lockdep_cache(lock);
2852 printk("but there are no more locks to release!\n");
2853 printk("\nother info that might help us debug this:\n");
2854 lockdep_print_held_locks(curr);
2856 printk("\nstack backtrace:\n");
2863 * Common debugging checks for both nested and non-nested unlock:
2865 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2868 if (unlikely(!debug_locks))
2870 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2873 if (curr->lockdep_depth <= 0)
2874 return print_unlock_inbalance_bug(curr, lock, ip);
2880 __lock_set_class(struct lockdep_map *lock, const char *name,
2881 struct lock_class_key *key, unsigned int subclass,
2884 struct task_struct *curr = current;
2885 struct held_lock *hlock, *prev_hlock;
2886 struct lock_class *class;
2890 depth = curr->lockdep_depth;
2891 if (DEBUG_LOCKS_WARN_ON(!depth))
2895 for (i = depth-1; i >= 0; i--) {
2896 hlock = curr->held_locks + i;
2898 * We must not cross into another context:
2900 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2902 if (hlock->instance == lock)
2906 return print_unlock_inbalance_bug(curr, lock, ip);
2909 lockdep_init_map(lock, name, key, 0);
2910 class = register_lock_class(lock, subclass, 0);
2911 hlock->class_idx = class - lock_classes + 1;
2913 curr->lockdep_depth = i;
2914 curr->curr_chain_key = hlock->prev_chain_key;
2916 for (; i < depth; i++) {
2917 hlock = curr->held_locks + i;
2918 if (!__lock_acquire(hlock->instance,
2919 hlock_class(hlock)->subclass, hlock->trylock,
2920 hlock->read, hlock->check, hlock->hardirqs_off,
2921 hlock->nest_lock, hlock->acquire_ip))
2925 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2931 * Remove the lock to the list of currently held locks in a
2932 * potentially non-nested (out of order) manner. This is a
2933 * relatively rare operation, as all the unlock APIs default
2934 * to nested mode (which uses lock_release()):
2937 lock_release_non_nested(struct task_struct *curr,
2938 struct lockdep_map *lock, unsigned long ip)
2940 struct held_lock *hlock, *prev_hlock;
2945 * Check whether the lock exists in the current stack
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 (hlock->instance == lock)
2964 return print_unlock_inbalance_bug(curr, lock, ip);
2967 lock_release_holdtime(hlock);
2970 * We have the right lock to unlock, 'hlock' points to it.
2971 * Now we remove it from the stack, and add back the other
2972 * entries (if any), recalculating the hash along the way:
2974 curr->lockdep_depth = i;
2975 curr->curr_chain_key = hlock->prev_chain_key;
2977 for (i++; i < depth; i++) {
2978 hlock = curr->held_locks + i;
2979 if (!__lock_acquire(hlock->instance,
2980 hlock_class(hlock)->subclass, hlock->trylock,
2981 hlock->read, hlock->check, hlock->hardirqs_off,
2982 hlock->nest_lock, hlock->acquire_ip))
2986 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2992 * Remove the lock to the list of currently held locks - this gets
2993 * called on mutex_unlock()/spin_unlock*() (or on a failed
2994 * mutex_lock_interruptible()). This is done for unlocks that nest
2995 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2997 static int lock_release_nested(struct task_struct *curr,
2998 struct lockdep_map *lock, unsigned long ip)
3000 struct held_lock *hlock;
3004 * Pop off the top of the lock stack:
3006 depth = curr->lockdep_depth - 1;
3007 hlock = curr->held_locks + depth;
3010 * Is the unlock non-nested:
3012 if (hlock->instance != lock)
3013 return lock_release_non_nested(curr, lock, ip);
3014 curr->lockdep_depth--;
3016 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3019 curr->curr_chain_key = hlock->prev_chain_key;
3021 lock_release_holdtime(hlock);
3023 #ifdef CONFIG_DEBUG_LOCKDEP
3024 hlock->prev_chain_key = 0;
3025 hlock->class_idx = 0;
3026 hlock->acquire_ip = 0;
3027 hlock->irq_context = 0;
3033 * Remove the lock to the list of currently held locks - this gets
3034 * called on mutex_unlock()/spin_unlock*() (or on a failed
3035 * mutex_lock_interruptible()). This is done for unlocks that nest
3036 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3039 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3041 struct task_struct *curr = current;
3043 if (!check_unlock(curr, lock, ip))
3047 if (!lock_release_nested(curr, lock, ip))
3050 if (!lock_release_non_nested(curr, lock, ip))
3054 check_chain_key(curr);
3058 * Check whether we follow the irq-flags state precisely:
3060 static void check_flags(unsigned long flags)
3062 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3063 defined(CONFIG_TRACE_IRQFLAGS)
3067 if (irqs_disabled_flags(flags)) {
3068 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3069 printk("possible reason: unannotated irqs-off.\n");
3072 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3073 printk("possible reason: unannotated irqs-on.\n");
3078 * We dont accurately track softirq state in e.g.
3079 * hardirq contexts (such as on 4KSTACKS), so only
3080 * check if not in hardirq contexts:
3082 if (!hardirq_count()) {
3083 if (softirq_count())
3084 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3086 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3090 print_irqtrace_events(current);
3094 void lock_set_class(struct lockdep_map *lock, const char *name,
3095 struct lock_class_key *key, unsigned int subclass,
3098 unsigned long flags;
3100 if (unlikely(current->lockdep_recursion))
3103 raw_local_irq_save(flags);
3104 current->lockdep_recursion = 1;
3106 if (__lock_set_class(lock, name, key, subclass, ip))
3107 check_chain_key(current);
3108 current->lockdep_recursion = 0;
3109 raw_local_irq_restore(flags);
3111 EXPORT_SYMBOL_GPL(lock_set_class);
3114 * We are not always called with irqs disabled - do that here,
3115 * and also avoid lockdep recursion:
3117 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3118 int trylock, int read, int check,
3119 struct lockdep_map *nest_lock, unsigned long ip)
3121 unsigned long flags;
3123 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3125 if (unlikely(current->lockdep_recursion))
3128 raw_local_irq_save(flags);
3131 current->lockdep_recursion = 1;
3132 __lock_acquire(lock, subclass, trylock, read, check,
3133 irqs_disabled_flags(flags), nest_lock, ip);
3134 current->lockdep_recursion = 0;
3135 raw_local_irq_restore(flags);
3137 EXPORT_SYMBOL_GPL(lock_acquire);
3139 void lock_release(struct lockdep_map *lock, int nested,
3142 unsigned long flags;
3144 trace_lock_release(lock, nested, ip);
3146 if (unlikely(current->lockdep_recursion))
3149 raw_local_irq_save(flags);
3151 current->lockdep_recursion = 1;
3152 __lock_release(lock, nested, ip);
3153 current->lockdep_recursion = 0;
3154 raw_local_irq_restore(flags);
3156 EXPORT_SYMBOL_GPL(lock_release);
3158 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3160 current->lockdep_reclaim_gfp = gfp_mask;
3163 void lockdep_clear_current_reclaim_state(void)
3165 current->lockdep_reclaim_gfp = 0;
3168 #ifdef CONFIG_LOCK_STAT
3170 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3173 if (!debug_locks_off())
3175 if (debug_locks_silent)
3178 printk("\n=================================\n");
3179 printk( "[ BUG: bad contention detected! ]\n");
3180 printk( "---------------------------------\n");
3181 printk("%s/%d is trying to contend lock (",
3182 curr->comm, task_pid_nr(curr));
3183 print_lockdep_cache(lock);
3186 printk("but there are no locks held!\n");
3187 printk("\nother info that might help us debug this:\n");
3188 lockdep_print_held_locks(curr);
3190 printk("\nstack backtrace:\n");
3197 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3199 struct task_struct *curr = current;
3200 struct held_lock *hlock, *prev_hlock;
3201 struct lock_class_stats *stats;
3203 int i, contention_point, contending_point;
3205 depth = curr->lockdep_depth;
3206 if (DEBUG_LOCKS_WARN_ON(!depth))
3210 for (i = depth-1; i >= 0; i--) {
3211 hlock = curr->held_locks + i;
3213 * We must not cross into another context:
3215 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3217 if (hlock->instance == lock)
3221 print_lock_contention_bug(curr, lock, ip);
3225 hlock->waittime_stamp = sched_clock();
3227 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3228 contending_point = lock_point(hlock_class(hlock)->contending_point,
3231 stats = get_lock_stats(hlock_class(hlock));
3232 if (contention_point < LOCKSTAT_POINTS)
3233 stats->contention_point[contention_point]++;
3234 if (contending_point < LOCKSTAT_POINTS)
3235 stats->contending_point[contending_point]++;
3236 if (lock->cpu != smp_processor_id())
3237 stats->bounces[bounce_contended + !!hlock->read]++;
3238 put_lock_stats(stats);
3242 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3244 struct task_struct *curr = current;
3245 struct held_lock *hlock, *prev_hlock;
3246 struct lock_class_stats *stats;
3252 depth = curr->lockdep_depth;
3253 if (DEBUG_LOCKS_WARN_ON(!depth))
3257 for (i = depth-1; i >= 0; i--) {
3258 hlock = curr->held_locks + i;
3260 * We must not cross into another context:
3262 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3264 if (hlock->instance == lock)
3268 print_lock_contention_bug(curr, lock, _RET_IP_);
3272 cpu = smp_processor_id();
3273 if (hlock->waittime_stamp) {
3274 now = sched_clock();
3275 waittime = now - hlock->waittime_stamp;
3276 hlock->holdtime_stamp = now;
3279 trace_lock_acquired(lock, ip, waittime);
3281 stats = get_lock_stats(hlock_class(hlock));
3284 lock_time_inc(&stats->read_waittime, waittime);
3286 lock_time_inc(&stats->write_waittime, waittime);
3288 if (lock->cpu != cpu)
3289 stats->bounces[bounce_acquired + !!hlock->read]++;
3290 put_lock_stats(stats);
3296 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3298 unsigned long flags;
3300 trace_lock_contended(lock, ip);
3302 if (unlikely(!lock_stat))
3305 if (unlikely(current->lockdep_recursion))
3308 raw_local_irq_save(flags);
3310 current->lockdep_recursion = 1;
3311 __lock_contended(lock, ip);
3312 current->lockdep_recursion = 0;
3313 raw_local_irq_restore(flags);
3315 EXPORT_SYMBOL_GPL(lock_contended);
3317 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3319 unsigned long flags;
3321 if (unlikely(!lock_stat))
3324 if (unlikely(current->lockdep_recursion))
3327 raw_local_irq_save(flags);
3329 current->lockdep_recursion = 1;
3330 __lock_acquired(lock, ip);
3331 current->lockdep_recursion = 0;
3332 raw_local_irq_restore(flags);
3334 EXPORT_SYMBOL_GPL(lock_acquired);
3338 * Used by the testsuite, sanitize the validator state
3339 * after a simulated failure:
3342 void lockdep_reset(void)
3344 unsigned long flags;
3347 raw_local_irq_save(flags);
3348 current->curr_chain_key = 0;
3349 current->lockdep_depth = 0;
3350 current->lockdep_recursion = 0;
3351 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3352 nr_hardirq_chains = 0;
3353 nr_softirq_chains = 0;
3354 nr_process_chains = 0;
3356 for (i = 0; i < CHAINHASH_SIZE; i++)
3357 INIT_LIST_HEAD(chainhash_table + i);
3358 raw_local_irq_restore(flags);
3361 static void zap_class(struct lock_class *class)
3366 * Remove all dependencies this lock is
3369 for (i = 0; i < nr_list_entries; i++) {
3370 if (list_entries[i].class == class)
3371 list_del_rcu(&list_entries[i].entry);
3374 * Unhash the class and remove it from the all_lock_classes list:
3376 list_del_rcu(&class->hash_entry);
3377 list_del_rcu(&class->lock_entry);
3382 static inline int within(const void *addr, void *start, unsigned long size)
3384 return addr >= start && addr < start + size;
3387 void lockdep_free_key_range(void *start, unsigned long size)
3389 struct lock_class *class, *next;
3390 struct list_head *head;
3391 unsigned long flags;
3395 raw_local_irq_save(flags);
3396 locked = graph_lock();
3399 * Unhash all classes that were created by this module:
3401 for (i = 0; i < CLASSHASH_SIZE; i++) {
3402 head = classhash_table + i;
3403 if (list_empty(head))
3405 list_for_each_entry_safe(class, next, head, hash_entry) {
3406 if (within(class->key, start, size))
3408 else if (within(class->name, start, size))
3415 raw_local_irq_restore(flags);
3418 void lockdep_reset_lock(struct lockdep_map *lock)
3420 struct lock_class *class, *next;
3421 struct list_head *head;
3422 unsigned long flags;
3426 raw_local_irq_save(flags);
3429 * Remove all classes this lock might have:
3431 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3433 * If the class exists we look it up and zap it:
3435 class = look_up_lock_class(lock, j);
3440 * Debug check: in the end all mapped classes should
3443 locked = graph_lock();
3444 for (i = 0; i < CLASSHASH_SIZE; i++) {
3445 head = classhash_table + i;
3446 if (list_empty(head))
3448 list_for_each_entry_safe(class, next, head, hash_entry) {
3449 if (unlikely(class == lock->class_cache)) {
3450 if (debug_locks_off_graph_unlock())
3460 raw_local_irq_restore(flags);
3463 void lockdep_init(void)
3468 * Some architectures have their own start_kernel()
3469 * code which calls lockdep_init(), while we also
3470 * call lockdep_init() from the start_kernel() itself,
3471 * and we want to initialize the hashes only once:
3473 if (lockdep_initialized)
3476 for (i = 0; i < CLASSHASH_SIZE; i++)
3477 INIT_LIST_HEAD(classhash_table + i);
3479 for (i = 0; i < CHAINHASH_SIZE; i++)
3480 INIT_LIST_HEAD(chainhash_table + i);
3482 lockdep_initialized = 1;
3485 void __init lockdep_info(void)
3487 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3489 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3490 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3491 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3492 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3493 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3494 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3495 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3497 printk(" memory used by lock dependency info: %lu kB\n",
3498 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3499 sizeof(struct list_head) * CLASSHASH_SIZE +
3500 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3501 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3502 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024
3503 #ifdef CONFIG_PROVE_LOCKING
3504 + sizeof(struct circular_queue) + sizeof(bfs_accessed)
3508 printk(" per task-struct memory footprint: %lu bytes\n",
3509 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3511 #ifdef CONFIG_DEBUG_LOCKDEP
3512 if (lockdep_init_error) {
3513 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3514 printk("Call stack leading to lockdep invocation was:\n");
3515 print_stack_trace(&lockdep_init_trace, 0);
3521 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3522 const void *mem_to, struct held_lock *hlock)
3524 if (!debug_locks_off())
3526 if (debug_locks_silent)
3529 printk("\n=========================\n");
3530 printk( "[ BUG: held lock freed! ]\n");
3531 printk( "-------------------------\n");
3532 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3533 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3535 lockdep_print_held_locks(curr);
3537 printk("\nstack backtrace:\n");
3541 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3542 const void* lock_from, unsigned long lock_len)
3544 return lock_from + lock_len <= mem_from ||
3545 mem_from + mem_len <= lock_from;
3549 * Called when kernel memory is freed (or unmapped), or if a lock
3550 * is destroyed or reinitialized - this code checks whether there is
3551 * any held lock in the memory range of <from> to <to>:
3553 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3555 struct task_struct *curr = current;
3556 struct held_lock *hlock;
3557 unsigned long flags;
3560 if (unlikely(!debug_locks))
3563 local_irq_save(flags);
3564 for (i = 0; i < curr->lockdep_depth; i++) {
3565 hlock = curr->held_locks + i;
3567 if (not_in_range(mem_from, mem_len, hlock->instance,
3568 sizeof(*hlock->instance)))
3571 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3574 local_irq_restore(flags);
3576 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3578 static void print_held_locks_bug(struct task_struct *curr)
3580 if (!debug_locks_off())
3582 if (debug_locks_silent)
3585 printk("\n=====================================\n");
3586 printk( "[ BUG: lock held at task exit time! ]\n");
3587 printk( "-------------------------------------\n");
3588 printk("%s/%d is exiting with locks still held!\n",
3589 curr->comm, task_pid_nr(curr));
3590 lockdep_print_held_locks(curr);
3592 printk("\nstack backtrace:\n");
3596 void debug_check_no_locks_held(struct task_struct *task)
3598 if (unlikely(task->lockdep_depth > 0))
3599 print_held_locks_bug(task);
3602 void debug_show_all_locks(void)
3604 struct task_struct *g, *p;
3608 if (unlikely(!debug_locks)) {
3609 printk("INFO: lockdep is turned off.\n");
3612 printk("\nShowing all locks held in the system:\n");
3615 * Here we try to get the tasklist_lock as hard as possible,
3616 * if not successful after 2 seconds we ignore it (but keep
3617 * trying). This is to enable a debug printout even if a
3618 * tasklist_lock-holding task deadlocks or crashes.
3621 if (!read_trylock(&tasklist_lock)) {
3623 printk("hm, tasklist_lock locked, retrying... ");
3626 printk(" #%d", 10-count);
3630 printk(" ignoring it.\n");
3634 printk(KERN_CONT " locked it.\n");
3637 do_each_thread(g, p) {
3639 * It's not reliable to print a task's held locks
3640 * if it's not sleeping (or if it's not the current
3643 if (p->state == TASK_RUNNING && p != current)
3645 if (p->lockdep_depth)
3646 lockdep_print_held_locks(p);
3648 if (read_trylock(&tasklist_lock))
3650 } while_each_thread(g, p);
3653 printk("=============================================\n\n");
3656 read_unlock(&tasklist_lock);
3658 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3661 * Careful: only use this function if you are sure that
3662 * the task cannot run in parallel!
3664 void __debug_show_held_locks(struct task_struct *task)
3666 if (unlikely(!debug_locks)) {
3667 printk("INFO: lockdep is turned off.\n");
3670 lockdep_print_held_locks(task);
3672 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3674 void debug_show_held_locks(struct task_struct *task)
3676 __debug_show_held_locks(task);
3678 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3680 void lockdep_sys_exit(void)
3682 struct task_struct *curr = current;
3684 if (unlikely(curr->lockdep_depth)) {
3685 if (!debug_locks_off())
3687 printk("\n================================================\n");
3688 printk( "[ BUG: lock held when returning to user space! ]\n");
3689 printk( "------------------------------------------------\n");
3690 printk("%s/%d is leaving the kernel with locks still held!\n",
3691 curr->comm, curr->pid);
3692 lockdep_print_held_locks(curr);