4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
48 #include <asm/sections.h>
50 #include "lockdep_internals.h"
52 #define CREATE_TRACE_POINTS
53 #include <trace/events/lock.h>
55 #ifdef CONFIG_PROVE_LOCKING
56 int prove_locking = 1;
57 module_param(prove_locking, int, 0644);
59 #define prove_locking 0
62 #ifdef CONFIG_LOCK_STAT
64 module_param(lock_stat, int, 0644);
70 * lockdep_lock: protects the lockdep graph, the hashes and the
71 * class/list/hash allocators.
73 * This is one of the rare exceptions where it's justified
74 * to use a raw spinlock - we really dont want the spinlock
75 * code to recurse back into the lockdep code...
77 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
79 static int graph_lock(void)
81 arch_spin_lock(&lockdep_lock);
83 * Make sure that if another CPU detected a bug while
84 * walking the graph we dont change it (while the other
85 * CPU is busy printing out stuff with the graph lock
89 arch_spin_unlock(&lockdep_lock);
92 /* prevent any recursions within lockdep from causing deadlocks */
93 current->lockdep_recursion++;
97 static inline int graph_unlock(void)
99 if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
100 return DEBUG_LOCKS_WARN_ON(1);
102 current->lockdep_recursion--;
103 arch_spin_unlock(&lockdep_lock);
108 * Turn lock debugging off and return with 0 if it was off already,
109 * and also release the graph lock:
111 static inline int debug_locks_off_graph_unlock(void)
113 int ret = debug_locks_off();
115 arch_spin_unlock(&lockdep_lock);
120 static int lockdep_initialized;
122 unsigned long nr_list_entries;
123 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
126 * All data structures here are protected by the global debug_lock.
128 * Mutex key structs only get allocated, once during bootup, and never
129 * get freed - this significantly simplifies the debugging code.
131 unsigned long nr_lock_classes;
132 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
134 static inline struct lock_class *hlock_class(struct held_lock *hlock)
136 if (!hlock->class_idx) {
137 DEBUG_LOCKS_WARN_ON(1);
140 return lock_classes + hlock->class_idx - 1;
143 #ifdef CONFIG_LOCK_STAT
144 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
147 static inline u64 lockstat_clock(void)
149 return local_clock();
152 static int lock_point(unsigned long points[], unsigned long ip)
156 for (i = 0; i < LOCKSTAT_POINTS; i++) {
157 if (points[i] == 0) {
168 static void lock_time_inc(struct lock_time *lt, u64 time)
173 if (time < lt->min || !lt->nr)
180 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
185 if (src->max > dst->max)
188 if (src->min < dst->min || !dst->nr)
191 dst->total += src->total;
195 struct lock_class_stats lock_stats(struct lock_class *class)
197 struct lock_class_stats stats;
200 memset(&stats, 0, sizeof(struct lock_class_stats));
201 for_each_possible_cpu(cpu) {
202 struct lock_class_stats *pcs =
203 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
205 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
206 stats.contention_point[i] += pcs->contention_point[i];
208 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
209 stats.contending_point[i] += pcs->contending_point[i];
211 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
212 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
214 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
215 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
217 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
218 stats.bounces[i] += pcs->bounces[i];
224 void clear_lock_stats(struct lock_class *class)
228 for_each_possible_cpu(cpu) {
229 struct lock_class_stats *cpu_stats =
230 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
232 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
234 memset(class->contention_point, 0, sizeof(class->contention_point));
235 memset(class->contending_point, 0, sizeof(class->contending_point));
238 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
240 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
243 static void put_lock_stats(struct lock_class_stats *stats)
245 put_cpu_var(cpu_lock_stats);
248 static void lock_release_holdtime(struct held_lock *hlock)
250 struct lock_class_stats *stats;
256 holdtime = lockstat_clock() - hlock->holdtime_stamp;
258 stats = get_lock_stats(hlock_class(hlock));
260 lock_time_inc(&stats->read_holdtime, holdtime);
262 lock_time_inc(&stats->write_holdtime, holdtime);
263 put_lock_stats(stats);
266 static inline void lock_release_holdtime(struct held_lock *hlock)
272 * We keep a global list of all lock classes. The list only grows,
273 * never shrinks. The list is only accessed with the lockdep
274 * spinlock lock held.
276 LIST_HEAD(all_lock_classes);
279 * The lockdep classes are in a hash-table as well, for fast lookup:
281 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
282 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
283 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
284 #define classhashentry(key) (classhash_table + __classhashfn((key)))
286 static struct list_head classhash_table[CLASSHASH_SIZE];
289 * We put the lock dependency chains into a hash-table as well, to cache
292 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
293 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
294 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
295 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
297 static struct list_head chainhash_table[CHAINHASH_SIZE];
300 * The hash key of the lock dependency chains is a hash itself too:
301 * it's a hash of all locks taken up to that lock, including that lock.
302 * It's a 64-bit hash, because it's important for the keys to be
305 #define iterate_chain_key(key1, key2) \
306 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
307 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
310 void lockdep_off(void)
312 current->lockdep_recursion++;
314 EXPORT_SYMBOL(lockdep_off);
316 void lockdep_on(void)
318 current->lockdep_recursion--;
320 EXPORT_SYMBOL(lockdep_on);
323 * Debugging switches:
327 #define VERY_VERBOSE 0
330 # define HARDIRQ_VERBOSE 1
331 # define SOFTIRQ_VERBOSE 1
332 # define RECLAIM_VERBOSE 1
334 # define HARDIRQ_VERBOSE 0
335 # define SOFTIRQ_VERBOSE 0
336 # define RECLAIM_VERBOSE 0
339 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
341 * Quick filtering for interesting events:
343 static int class_filter(struct lock_class *class)
347 if (class->name_version == 1 &&
348 !strcmp(class->name, "lockname"))
350 if (class->name_version == 1 &&
351 !strcmp(class->name, "&struct->lockfield"))
354 /* Filter everything else. 1 would be to allow everything else */
359 static int verbose(struct lock_class *class)
362 return class_filter(class);
368 * Stack-trace: tightly packed array of stack backtrace
369 * addresses. Protected by the graph_lock.
371 unsigned long nr_stack_trace_entries;
372 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
374 static int save_trace(struct stack_trace *trace)
376 trace->nr_entries = 0;
377 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
378 trace->entries = stack_trace + nr_stack_trace_entries;
382 save_stack_trace(trace);
385 * Some daft arches put -1 at the end to indicate its a full trace.
387 * <rant> this is buggy anyway, since it takes a whole extra entry so a
388 * complete trace that maxes out the entries provided will be reported
389 * as incomplete, friggin useless </rant>
391 if (trace->nr_entries != 0 &&
392 trace->entries[trace->nr_entries-1] == ULONG_MAX)
395 trace->max_entries = trace->nr_entries;
397 nr_stack_trace_entries += trace->nr_entries;
399 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
400 if (!debug_locks_off_graph_unlock())
403 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
404 printk("turning off the locking correctness validator.\n");
413 unsigned int nr_hardirq_chains;
414 unsigned int nr_softirq_chains;
415 unsigned int nr_process_chains;
416 unsigned int max_lockdep_depth;
418 #ifdef CONFIG_DEBUG_LOCKDEP
420 * We cannot printk in early bootup code. Not even early_printk()
421 * might work. So we mark any initialization errors and printk
422 * about it later on, in lockdep_info().
424 static int lockdep_init_error;
425 static unsigned long lockdep_init_trace_data[20];
426 static struct stack_trace lockdep_init_trace = {
427 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
428 .entries = lockdep_init_trace_data,
432 * Various lockdep statistics:
434 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
441 #define __USAGE(__STATE) \
442 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
443 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
444 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
445 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
447 static const char *usage_str[] =
449 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
450 #include "lockdep_states.h"
452 [LOCK_USED] = "INITIAL USE",
455 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
457 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
460 static inline unsigned long lock_flag(enum lock_usage_bit bit)
465 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
469 if (class->usage_mask & lock_flag(bit + 2))
471 if (class->usage_mask & lock_flag(bit)) {
473 if (class->usage_mask & lock_flag(bit + 2))
480 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
484 #define LOCKDEP_STATE(__STATE) \
485 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
486 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
487 #include "lockdep_states.h"
493 static int __print_lock_name(struct lock_class *class)
495 char str[KSYM_NAME_LEN];
500 name = __get_key_name(class->key, str);
502 return printk("%s", name);
505 static void print_lock_name(struct lock_class *class)
507 char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
510 get_usage_chars(class, usage);
514 name = __get_key_name(class->key, str);
515 printk(" (%s", name);
517 printk(" (%s", name);
518 if (class->name_version > 1)
519 printk("#%d", class->name_version);
521 printk("/%d", class->subclass);
523 printk("){%s}", usage);
526 static void print_lockdep_cache(struct lockdep_map *lock)
529 char str[KSYM_NAME_LEN];
533 name = __get_key_name(lock->key->subkeys, str);
538 static void print_lock(struct held_lock *hlock)
540 print_lock_name(hlock_class(hlock));
542 print_ip_sym(hlock->acquire_ip);
545 static void lockdep_print_held_locks(struct task_struct *curr)
547 int i, depth = curr->lockdep_depth;
550 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
553 printk("%d lock%s held by %s/%d:\n",
554 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
556 for (i = 0; i < depth; i++) {
558 print_lock(curr->held_locks + i);
562 static void print_kernel_version(void)
564 printk("%s %.*s\n", init_utsname()->release,
565 (int)strcspn(init_utsname()->version, " "),
566 init_utsname()->version);
569 static int very_verbose(struct lock_class *class)
572 return class_filter(class);
578 * Is this the address of a static object:
580 static int static_obj(void *obj)
582 unsigned long start = (unsigned long) &_stext,
583 end = (unsigned long) &_end,
584 addr = (unsigned long) obj;
589 if ((addr >= start) && (addr < end))
592 if (arch_is_kernel_data(addr))
596 * in-kernel percpu var?
598 if (is_kernel_percpu_address(addr))
602 * module static or percpu var?
604 return is_module_address(addr) || is_module_percpu_address(addr);
608 * To make lock name printouts unique, we calculate a unique
609 * class->name_version generation counter:
611 static int count_matching_names(struct lock_class *new_class)
613 struct lock_class *class;
616 if (!new_class->name)
619 list_for_each_entry(class, &all_lock_classes, lock_entry) {
620 if (new_class->key - new_class->subclass == class->key)
621 return class->name_version;
622 if (class->name && !strcmp(class->name, new_class->name))
623 count = max(count, class->name_version);
630 * Register a lock's class in the hash-table, if the class is not present
631 * yet. Otherwise we look it up. We cache the result in the lock object
632 * itself, so actual lookup of the hash should be once per lock object.
634 static inline struct lock_class *
635 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
637 struct lockdep_subclass_key *key;
638 struct list_head *hash_head;
639 struct lock_class *class;
641 #ifdef CONFIG_DEBUG_LOCKDEP
643 * If the architecture calls into lockdep before initializing
644 * the hashes then we'll warn about it later. (we cannot printk
647 if (unlikely(!lockdep_initialized)) {
649 lockdep_init_error = 1;
650 save_stack_trace(&lockdep_init_trace);
654 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
657 "BUG: looking up invalid subclass: %u\n", subclass);
659 "turning off the locking correctness validator.\n");
665 * Static locks do not have their class-keys yet - for them the key
666 * is the lock object itself:
668 if (unlikely(!lock->key))
669 lock->key = (void *)lock;
672 * NOTE: the class-key must be unique. For dynamic locks, a static
673 * lock_class_key variable is passed in through the mutex_init()
674 * (or spin_lock_init()) call - which acts as the key. For static
675 * locks we use the lock object itself as the key.
677 BUILD_BUG_ON(sizeof(struct lock_class_key) >
678 sizeof(struct lockdep_map));
680 key = lock->key->subkeys + subclass;
682 hash_head = classhashentry(key);
685 * We can walk the hash lockfree, because the hash only
686 * grows, and we are careful when adding entries to the end:
688 list_for_each_entry(class, hash_head, hash_entry) {
689 if (class->key == key) {
690 WARN_ON_ONCE(class->name != lock->name);
699 * Register a lock's class in the hash-table, if the class is not present
700 * yet. Otherwise we look it up. We cache the result in the lock object
701 * itself, so actual lookup of the hash should be once per lock object.
703 static inline struct lock_class *
704 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
706 struct lockdep_subclass_key *key;
707 struct list_head *hash_head;
708 struct lock_class *class;
711 class = look_up_lock_class(lock, subclass);
716 * Debug-check: all keys must be persistent!
718 if (!static_obj(lock->key)) {
720 printk("INFO: trying to register non-static key.\n");
721 printk("the code is fine but needs lockdep annotation.\n");
722 printk("turning off the locking correctness validator.\n");
728 key = lock->key->subkeys + subclass;
729 hash_head = classhashentry(key);
731 raw_local_irq_save(flags);
733 raw_local_irq_restore(flags);
737 * We have to do the hash-walk again, to avoid races
740 list_for_each_entry(class, hash_head, hash_entry)
741 if (class->key == key)
744 * Allocate a new key from the static array, and add it to
747 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
748 if (!debug_locks_off_graph_unlock()) {
749 raw_local_irq_restore(flags);
752 raw_local_irq_restore(flags);
754 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
755 printk("turning off the locking correctness validator.\n");
759 class = lock_classes + nr_lock_classes++;
760 debug_atomic_inc(nr_unused_locks);
762 class->name = lock->name;
763 class->subclass = subclass;
764 INIT_LIST_HEAD(&class->lock_entry);
765 INIT_LIST_HEAD(&class->locks_before);
766 INIT_LIST_HEAD(&class->locks_after);
767 class->name_version = count_matching_names(class);
769 * We use RCU's safe list-add method to make
770 * parallel walking of the hash-list safe:
772 list_add_tail_rcu(&class->hash_entry, hash_head);
774 * Add it to the global list of classes:
776 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
778 if (verbose(class)) {
780 raw_local_irq_restore(flags);
782 printk("\nnew class %p: %s", class->key, class->name);
783 if (class->name_version > 1)
784 printk("#%d", class->name_version);
788 raw_local_irq_save(flags);
790 raw_local_irq_restore(flags);
796 raw_local_irq_restore(flags);
798 if (!subclass || force)
799 lock->class_cache[0] = class;
800 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
801 lock->class_cache[subclass] = class;
803 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
809 #ifdef CONFIG_PROVE_LOCKING
811 * Allocate a lockdep entry. (assumes the graph_lock held, returns
812 * with NULL on failure)
814 static struct lock_list *alloc_list_entry(void)
816 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
817 if (!debug_locks_off_graph_unlock())
820 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
821 printk("turning off the locking correctness validator.\n");
825 return list_entries + nr_list_entries++;
829 * Add a new dependency to the head of the list:
831 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
832 struct list_head *head, unsigned long ip,
833 int distance, struct stack_trace *trace)
835 struct lock_list *entry;
837 * Lock not present yet - get a new dependency struct and
838 * add it to the list:
840 entry = alloc_list_entry();
845 entry->distance = distance;
846 entry->trace = *trace;
848 * Since we never remove from the dependency list, the list can
849 * be walked lockless by other CPUs, it's only allocation
850 * that must be protected by the spinlock. But this also means
851 * we must make new entries visible only once writes to the
852 * entry become visible - hence the RCU op:
854 list_add_tail_rcu(&entry->entry, head);
860 * For good efficiency of modular, we use power of 2
862 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
863 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
866 * The circular_queue and helpers is used to implement the
867 * breadth-first search(BFS)algorithem, by which we can build
868 * the shortest path from the next lock to be acquired to the
869 * previous held lock if there is a circular between them.
871 struct circular_queue {
872 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
873 unsigned int front, rear;
876 static struct circular_queue lock_cq;
878 unsigned int max_bfs_queue_depth;
880 static unsigned int lockdep_dependency_gen_id;
882 static inline void __cq_init(struct circular_queue *cq)
884 cq->front = cq->rear = 0;
885 lockdep_dependency_gen_id++;
888 static inline int __cq_empty(struct circular_queue *cq)
890 return (cq->front == cq->rear);
893 static inline int __cq_full(struct circular_queue *cq)
895 return ((cq->rear + 1) & CQ_MASK) == cq->front;
898 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
903 cq->element[cq->rear] = elem;
904 cq->rear = (cq->rear + 1) & CQ_MASK;
908 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
913 *elem = cq->element[cq->front];
914 cq->front = (cq->front + 1) & CQ_MASK;
918 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
920 return (cq->rear - cq->front) & CQ_MASK;
923 static inline void mark_lock_accessed(struct lock_list *lock,
924 struct lock_list *parent)
928 nr = lock - list_entries;
929 WARN_ON(nr >= nr_list_entries);
930 lock->parent = parent;
931 lock->class->dep_gen_id = lockdep_dependency_gen_id;
934 static inline unsigned long lock_accessed(struct lock_list *lock)
938 nr = lock - list_entries;
939 WARN_ON(nr >= nr_list_entries);
940 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
943 static inline struct lock_list *get_lock_parent(struct lock_list *child)
945 return child->parent;
948 static inline int get_lock_depth(struct lock_list *child)
951 struct lock_list *parent;
953 while ((parent = get_lock_parent(child))) {
960 static int __bfs(struct lock_list *source_entry,
962 int (*match)(struct lock_list *entry, void *data),
963 struct lock_list **target_entry,
966 struct lock_list *entry;
967 struct list_head *head;
968 struct circular_queue *cq = &lock_cq;
971 if (match(source_entry, data)) {
972 *target_entry = source_entry;
978 head = &source_entry->class->locks_after;
980 head = &source_entry->class->locks_before;
982 if (list_empty(head))
986 __cq_enqueue(cq, (unsigned long)source_entry);
988 while (!__cq_empty(cq)) {
989 struct lock_list *lock;
991 __cq_dequeue(cq, (unsigned long *)&lock);
999 head = &lock->class->locks_after;
1001 head = &lock->class->locks_before;
1003 list_for_each_entry(entry, head, entry) {
1004 if (!lock_accessed(entry)) {
1005 unsigned int cq_depth;
1006 mark_lock_accessed(entry, lock);
1007 if (match(entry, data)) {
1008 *target_entry = entry;
1013 if (__cq_enqueue(cq, (unsigned long)entry)) {
1017 cq_depth = __cq_get_elem_count(cq);
1018 if (max_bfs_queue_depth < cq_depth)
1019 max_bfs_queue_depth = cq_depth;
1027 static inline int __bfs_forwards(struct lock_list *src_entry,
1029 int (*match)(struct lock_list *entry, void *data),
1030 struct lock_list **target_entry)
1032 return __bfs(src_entry, data, match, target_entry, 1);
1036 static inline int __bfs_backwards(struct lock_list *src_entry,
1038 int (*match)(struct lock_list *entry, void *data),
1039 struct lock_list **target_entry)
1041 return __bfs(src_entry, data, match, target_entry, 0);
1046 * Recursive, forwards-direction lock-dependency checking, used for
1047 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1052 * Print a dependency chain entry (this is only done when a deadlock
1053 * has been detected):
1056 print_circular_bug_entry(struct lock_list *target, int depth)
1058 if (debug_locks_silent)
1060 printk("\n-> #%u", depth);
1061 print_lock_name(target->class);
1063 print_stack_trace(&target->trace, 6);
1069 * When a circular dependency is detected, print the
1073 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1074 struct held_lock *check_src,
1075 struct held_lock *check_tgt)
1077 struct task_struct *curr = current;
1079 if (debug_locks_silent)
1082 printk("\n=======================================================\n");
1083 printk( "[ INFO: possible circular locking dependency detected ]\n");
1084 print_kernel_version();
1085 printk( "-------------------------------------------------------\n");
1086 printk("%s/%d is trying to acquire lock:\n",
1087 curr->comm, task_pid_nr(curr));
1088 print_lock(check_src);
1089 printk("\nbut task is already holding lock:\n");
1090 print_lock(check_tgt);
1091 printk("\nwhich lock already depends on the new lock.\n\n");
1092 printk("\nthe existing dependency chain (in reverse order) is:\n");
1094 print_circular_bug_entry(entry, depth);
1099 static inline int class_equal(struct lock_list *entry, void *data)
1101 return entry->class == data;
1104 static noinline int print_circular_bug(struct lock_list *this,
1105 struct lock_list *target,
1106 struct held_lock *check_src,
1107 struct held_lock *check_tgt)
1109 struct task_struct *curr = current;
1110 struct lock_list *parent;
1113 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1116 if (!save_trace(&this->trace))
1119 depth = get_lock_depth(target);
1121 print_circular_bug_header(target, depth, check_src, check_tgt);
1123 parent = get_lock_parent(target);
1126 print_circular_bug_entry(parent, --depth);
1127 parent = get_lock_parent(parent);
1130 printk("\nother info that might help us debug this:\n\n");
1131 lockdep_print_held_locks(curr);
1133 printk("\nstack backtrace:\n");
1139 static noinline int print_bfs_bug(int ret)
1141 if (!debug_locks_off_graph_unlock())
1144 WARN(1, "lockdep bfs error:%d\n", ret);
1149 static int noop_count(struct lock_list *entry, void *data)
1151 (*(unsigned long *)data)++;
1155 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1157 unsigned long count = 0;
1158 struct lock_list *uninitialized_var(target_entry);
1160 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1164 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1166 unsigned long ret, flags;
1167 struct lock_list this;
1172 local_irq_save(flags);
1173 arch_spin_lock(&lockdep_lock);
1174 ret = __lockdep_count_forward_deps(&this);
1175 arch_spin_unlock(&lockdep_lock);
1176 local_irq_restore(flags);
1181 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1183 unsigned long count = 0;
1184 struct lock_list *uninitialized_var(target_entry);
1186 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1191 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1193 unsigned long ret, flags;
1194 struct lock_list this;
1199 local_irq_save(flags);
1200 arch_spin_lock(&lockdep_lock);
1201 ret = __lockdep_count_backward_deps(&this);
1202 arch_spin_unlock(&lockdep_lock);
1203 local_irq_restore(flags);
1209 * Prove that the dependency graph starting at <entry> can not
1210 * lead to <target>. Print an error and return 0 if it does.
1213 check_noncircular(struct lock_list *root, struct lock_class *target,
1214 struct lock_list **target_entry)
1218 debug_atomic_inc(nr_cyclic_checks);
1220 result = __bfs_forwards(root, target, class_equal, target_entry);
1225 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1227 * Forwards and backwards subgraph searching, for the purposes of
1228 * proving that two subgraphs can be connected by a new dependency
1229 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1232 static inline int usage_match(struct lock_list *entry, void *bit)
1234 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1240 * Find a node in the forwards-direction dependency sub-graph starting
1241 * at @root->class that matches @bit.
1243 * Return 0 if such a node exists in the subgraph, and put that node
1244 * into *@target_entry.
1246 * Return 1 otherwise and keep *@target_entry unchanged.
1247 * Return <0 on error.
1250 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1251 struct lock_list **target_entry)
1255 debug_atomic_inc(nr_find_usage_forwards_checks);
1257 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1263 * Find a node in the backwards-direction dependency sub-graph starting
1264 * at @root->class that matches @bit.
1266 * Return 0 if such a node exists in the subgraph, and put that node
1267 * into *@target_entry.
1269 * Return 1 otherwise and keep *@target_entry unchanged.
1270 * Return <0 on error.
1273 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1274 struct lock_list **target_entry)
1278 debug_atomic_inc(nr_find_usage_backwards_checks);
1280 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1285 static void print_lock_class_header(struct lock_class *class, int depth)
1289 printk("%*s->", depth, "");
1290 print_lock_name(class);
1291 printk(" ops: %lu", class->ops);
1294 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1295 if (class->usage_mask & (1 << bit)) {
1298 len += printk("%*s %s", depth, "", usage_str[bit]);
1299 len += printk(" at:\n");
1300 print_stack_trace(class->usage_traces + bit, len);
1303 printk("%*s }\n", depth, "");
1305 printk("%*s ... key at: ",depth,"");
1306 print_ip_sym((unsigned long)class->key);
1310 * printk the shortest lock dependencies from @start to @end in reverse order:
1313 print_shortest_lock_dependencies(struct lock_list *leaf,
1314 struct lock_list *root)
1316 struct lock_list *entry = leaf;
1319 /*compute depth from generated tree by BFS*/
1320 depth = get_lock_depth(leaf);
1323 print_lock_class_header(entry->class, depth);
1324 printk("%*s ... acquired at:\n", depth, "");
1325 print_stack_trace(&entry->trace, 2);
1328 if (depth == 0 && (entry != root)) {
1329 printk("lockdep:%s bad BFS generated tree\n", __func__);
1333 entry = get_lock_parent(entry);
1335 } while (entry && (depth >= 0));
1341 print_irq_lock_scenario(struct lock_list *safe_entry,
1342 struct lock_list *unsafe_entry,
1343 struct held_lock *prev,
1344 struct held_lock *next)
1346 struct lock_class *safe_class = safe_entry->class;
1347 struct lock_class *unsafe_class = unsafe_entry->class;
1348 struct lock_class *middle_class = hlock_class(prev);
1350 if (middle_class == safe_class)
1351 middle_class = hlock_class(next);
1354 * A direct locking problem where unsafe_class lock is taken
1355 * directly by safe_class lock, then all we need to show
1356 * is the deadlock scenario, as it is obvious that the
1357 * unsafe lock is taken under the safe lock.
1359 * But if there is a chain instead, where the safe lock takes
1360 * an intermediate lock (middle_class) where this lock is
1361 * not the same as the safe lock, then the lock chain is
1362 * used to describe the problem. Otherwise we would need
1363 * to show a different CPU case for each link in the chain
1364 * from the safe_class lock to the unsafe_class lock.
1366 if (middle_class != unsafe_class) {
1367 printk("Chain exists of:\n ");
1368 __print_lock_name(safe_class);
1370 __print_lock_name(middle_class);
1372 __print_lock_name(unsafe_class);
1376 printk(" Possible interrupt unsafe locking scenario:\n\n");
1377 printk(" CPU0 CPU1\n");
1378 printk(" ---- ----\n");
1380 __print_lock_name(unsafe_class);
1382 printk(" local_irq_disable();\n");
1384 __print_lock_name(safe_class);
1387 __print_lock_name(middle_class);
1389 printk(" <Interrupt>\n");
1391 __print_lock_name(safe_class);
1393 printk("\n *** DEADLOCK ***\n\n");
1397 print_bad_irq_dependency(struct task_struct *curr,
1398 struct lock_list *prev_root,
1399 struct lock_list *next_root,
1400 struct lock_list *backwards_entry,
1401 struct lock_list *forwards_entry,
1402 struct held_lock *prev,
1403 struct held_lock *next,
1404 enum lock_usage_bit bit1,
1405 enum lock_usage_bit bit2,
1406 const char *irqclass)
1408 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1411 printk("\n======================================================\n");
1412 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1413 irqclass, irqclass);
1414 print_kernel_version();
1415 printk( "------------------------------------------------------\n");
1416 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1417 curr->comm, task_pid_nr(curr),
1418 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1419 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1420 curr->hardirqs_enabled,
1421 curr->softirqs_enabled);
1424 printk("\nand this task is already holding:\n");
1426 printk("which would create a new lock dependency:\n");
1427 print_lock_name(hlock_class(prev));
1429 print_lock_name(hlock_class(next));
1432 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1434 print_lock_name(backwards_entry->class);
1435 printk("\n... which became %s-irq-safe at:\n", irqclass);
1437 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1439 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1440 print_lock_name(forwards_entry->class);
1441 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1444 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1446 printk("\nother info that might help us debug this:\n\n");
1447 print_irq_lock_scenario(backwards_entry, forwards_entry, prev, next);
1449 lockdep_print_held_locks(curr);
1451 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1452 printk(" and the holding lock:\n");
1453 if (!save_trace(&prev_root->trace))
1455 print_shortest_lock_dependencies(backwards_entry, prev_root);
1457 printk("\nthe dependencies between the lock to be acquired");
1458 printk(" and %s-irq-unsafe lock:\n", irqclass);
1459 if (!save_trace(&next_root->trace))
1461 print_shortest_lock_dependencies(forwards_entry, next_root);
1463 printk("\nstack backtrace:\n");
1470 check_usage(struct task_struct *curr, struct held_lock *prev,
1471 struct held_lock *next, enum lock_usage_bit bit_backwards,
1472 enum lock_usage_bit bit_forwards, const char *irqclass)
1475 struct lock_list this, that;
1476 struct lock_list *uninitialized_var(target_entry);
1477 struct lock_list *uninitialized_var(target_entry1);
1481 this.class = hlock_class(prev);
1482 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1484 return print_bfs_bug(ret);
1489 that.class = hlock_class(next);
1490 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1492 return print_bfs_bug(ret);
1496 return print_bad_irq_dependency(curr, &this, &that,
1497 target_entry, target_entry1,
1499 bit_backwards, bit_forwards, irqclass);
1502 static const char *state_names[] = {
1503 #define LOCKDEP_STATE(__STATE) \
1504 __stringify(__STATE),
1505 #include "lockdep_states.h"
1506 #undef LOCKDEP_STATE
1509 static const char *state_rnames[] = {
1510 #define LOCKDEP_STATE(__STATE) \
1511 __stringify(__STATE)"-READ",
1512 #include "lockdep_states.h"
1513 #undef LOCKDEP_STATE
1516 static inline const char *state_name(enum lock_usage_bit bit)
1518 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1521 static int exclusive_bit(int new_bit)
1529 * bit 0 - write/read
1530 * bit 1 - used_in/enabled
1534 int state = new_bit & ~3;
1535 int dir = new_bit & 2;
1538 * keep state, bit flip the direction and strip read.
1540 return state | (dir ^ 2);
1543 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1544 struct held_lock *next, enum lock_usage_bit bit)
1547 * Prove that the new dependency does not connect a hardirq-safe
1548 * lock with a hardirq-unsafe lock - to achieve this we search
1549 * the backwards-subgraph starting at <prev>, and the
1550 * forwards-subgraph starting at <next>:
1552 if (!check_usage(curr, prev, next, bit,
1553 exclusive_bit(bit), state_name(bit)))
1559 * Prove that the new dependency does not connect a hardirq-safe-read
1560 * lock with a hardirq-unsafe lock - to achieve this we search
1561 * the backwards-subgraph starting at <prev>, and the
1562 * forwards-subgraph starting at <next>:
1564 if (!check_usage(curr, prev, next, bit,
1565 exclusive_bit(bit), state_name(bit)))
1572 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1573 struct held_lock *next)
1575 #define LOCKDEP_STATE(__STATE) \
1576 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1578 #include "lockdep_states.h"
1579 #undef LOCKDEP_STATE
1584 static void inc_chains(void)
1586 if (current->hardirq_context)
1587 nr_hardirq_chains++;
1589 if (current->softirq_context)
1590 nr_softirq_chains++;
1592 nr_process_chains++;
1599 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1600 struct held_lock *next)
1605 static inline void inc_chains(void)
1607 nr_process_chains++;
1613 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1614 struct held_lock *next)
1616 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1619 printk("\n=============================================\n");
1620 printk( "[ INFO: possible recursive locking detected ]\n");
1621 print_kernel_version();
1622 printk( "---------------------------------------------\n");
1623 printk("%s/%d is trying to acquire lock:\n",
1624 curr->comm, task_pid_nr(curr));
1626 printk("\nbut task is already holding lock:\n");
1629 printk("\nother info that might help us debug this:\n");
1630 lockdep_print_held_locks(curr);
1632 printk("\nstack backtrace:\n");
1639 * Check whether we are holding such a class already.
1641 * (Note that this has to be done separately, because the graph cannot
1642 * detect such classes of deadlocks.)
1644 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1647 check_deadlock(struct task_struct *curr, struct held_lock *next,
1648 struct lockdep_map *next_instance, int read)
1650 struct held_lock *prev;
1651 struct held_lock *nest = NULL;
1654 for (i = 0; i < curr->lockdep_depth; i++) {
1655 prev = curr->held_locks + i;
1657 if (prev->instance == next->nest_lock)
1660 if (hlock_class(prev) != hlock_class(next))
1664 * Allow read-after-read recursion of the same
1665 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1667 if ((read == 2) && prev->read)
1671 * We're holding the nest_lock, which serializes this lock's
1672 * nesting behaviour.
1677 return print_deadlock_bug(curr, prev, next);
1683 * There was a chain-cache miss, and we are about to add a new dependency
1684 * to a previous lock. We recursively validate the following rules:
1686 * - would the adding of the <prev> -> <next> dependency create a
1687 * circular dependency in the graph? [== circular deadlock]
1689 * - does the new prev->next dependency connect any hardirq-safe lock
1690 * (in the full backwards-subgraph starting at <prev>) with any
1691 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1692 * <next>)? [== illegal lock inversion with hardirq contexts]
1694 * - does the new prev->next dependency connect any softirq-safe lock
1695 * (in the full backwards-subgraph starting at <prev>) with any
1696 * softirq-unsafe lock (in the full forwards-subgraph starting at
1697 * <next>)? [== illegal lock inversion with softirq contexts]
1699 * any of these scenarios could lead to a deadlock.
1701 * Then if all the validations pass, we add the forwards and backwards
1705 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1706 struct held_lock *next, int distance, int trylock_loop)
1708 struct lock_list *entry;
1710 struct lock_list this;
1711 struct lock_list *uninitialized_var(target_entry);
1713 * Static variable, serialized by the graph_lock().
1715 * We use this static variable to save the stack trace in case
1716 * we call into this function multiple times due to encountering
1717 * trylocks in the held lock stack.
1719 static struct stack_trace trace;
1722 * Prove that the new <prev> -> <next> dependency would not
1723 * create a circular dependency in the graph. (We do this by
1724 * forward-recursing into the graph starting at <next>, and
1725 * checking whether we can reach <prev>.)
1727 * We are using global variables to control the recursion, to
1728 * keep the stackframe size of the recursive functions low:
1730 this.class = hlock_class(next);
1732 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1734 return print_circular_bug(&this, target_entry, next, prev);
1735 else if (unlikely(ret < 0))
1736 return print_bfs_bug(ret);
1738 if (!check_prev_add_irq(curr, prev, next))
1742 * For recursive read-locks we do all the dependency checks,
1743 * but we dont store read-triggered dependencies (only
1744 * write-triggered dependencies). This ensures that only the
1745 * write-side dependencies matter, and that if for example a
1746 * write-lock never takes any other locks, then the reads are
1747 * equivalent to a NOP.
1749 if (next->read == 2 || prev->read == 2)
1752 * Is the <prev> -> <next> dependency already present?
1754 * (this may occur even though this is a new chain: consider
1755 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1756 * chains - the second one will be new, but L1 already has
1757 * L2 added to its dependency list, due to the first chain.)
1759 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1760 if (entry->class == hlock_class(next)) {
1762 entry->distance = 1;
1767 if (!trylock_loop && !save_trace(&trace))
1771 * Ok, all validations passed, add the new lock
1772 * to the previous lock's dependency list:
1774 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1775 &hlock_class(prev)->locks_after,
1776 next->acquire_ip, distance, &trace);
1781 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1782 &hlock_class(next)->locks_before,
1783 next->acquire_ip, distance, &trace);
1788 * Debugging printouts:
1790 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1792 printk("\n new dependency: ");
1793 print_lock_name(hlock_class(prev));
1795 print_lock_name(hlock_class(next));
1798 return graph_lock();
1804 * Add the dependency to all directly-previous locks that are 'relevant'.
1805 * The ones that are relevant are (in increasing distance from curr):
1806 * all consecutive trylock entries and the final non-trylock entry - or
1807 * the end of this context's lock-chain - whichever comes first.
1810 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1812 int depth = curr->lockdep_depth;
1813 int trylock_loop = 0;
1814 struct held_lock *hlock;
1819 * Depth must not be zero for a non-head lock:
1824 * At least two relevant locks must exist for this
1827 if (curr->held_locks[depth].irq_context !=
1828 curr->held_locks[depth-1].irq_context)
1832 int distance = curr->lockdep_depth - depth + 1;
1833 hlock = curr->held_locks + depth-1;
1835 * Only non-recursive-read entries get new dependencies
1838 if (hlock->read != 2) {
1839 if (!check_prev_add(curr, hlock, next,
1840 distance, trylock_loop))
1843 * Stop after the first non-trylock entry,
1844 * as non-trylock entries have added their
1845 * own direct dependencies already, so this
1846 * lock is connected to them indirectly:
1848 if (!hlock->trylock)
1853 * End of lock-stack?
1858 * Stop the search if we cross into another context:
1860 if (curr->held_locks[depth].irq_context !=
1861 curr->held_locks[depth-1].irq_context)
1867 if (!debug_locks_off_graph_unlock())
1875 unsigned long nr_lock_chains;
1876 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1877 int nr_chain_hlocks;
1878 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1880 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1882 return lock_classes + chain_hlocks[chain->base + i];
1886 * Look up a dependency chain. If the key is not present yet then
1887 * add it and return 1 - in this case the new dependency chain is
1888 * validated. If the key is already hashed, return 0.
1889 * (On return with 1 graph_lock is held.)
1891 static inline int lookup_chain_cache(struct task_struct *curr,
1892 struct held_lock *hlock,
1895 struct lock_class *class = hlock_class(hlock);
1896 struct list_head *hash_head = chainhashentry(chain_key);
1897 struct lock_chain *chain;
1898 struct held_lock *hlock_curr, *hlock_next;
1901 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1904 * We can walk it lock-free, because entries only get added
1907 list_for_each_entry(chain, hash_head, entry) {
1908 if (chain->chain_key == chain_key) {
1910 debug_atomic_inc(chain_lookup_hits);
1911 if (very_verbose(class))
1912 printk("\nhash chain already cached, key: "
1913 "%016Lx tail class: [%p] %s\n",
1914 (unsigned long long)chain_key,
1915 class->key, class->name);
1919 if (very_verbose(class))
1920 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1921 (unsigned long long)chain_key, class->key, class->name);
1923 * Allocate a new chain entry from the static array, and add
1929 * We have to walk the chain again locked - to avoid duplicates:
1931 list_for_each_entry(chain, hash_head, entry) {
1932 if (chain->chain_key == chain_key) {
1937 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1938 if (!debug_locks_off_graph_unlock())
1941 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1942 printk("turning off the locking correctness validator.\n");
1946 chain = lock_chains + nr_lock_chains++;
1947 chain->chain_key = chain_key;
1948 chain->irq_context = hlock->irq_context;
1949 /* Find the first held_lock of current chain */
1951 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1952 hlock_curr = curr->held_locks + i;
1953 if (hlock_curr->irq_context != hlock_next->irq_context)
1958 chain->depth = curr->lockdep_depth + 1 - i;
1959 cn = nr_chain_hlocks;
1960 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1961 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1966 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1968 for (j = 0; j < chain->depth - 1; j++, i++) {
1969 int lock_id = curr->held_locks[i].class_idx - 1;
1970 chain_hlocks[chain->base + j] = lock_id;
1972 chain_hlocks[chain->base + j] = class - lock_classes;
1974 list_add_tail_rcu(&chain->entry, hash_head);
1975 debug_atomic_inc(chain_lookup_misses);
1981 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1982 struct held_lock *hlock, int chain_head, u64 chain_key)
1985 * Trylock needs to maintain the stack of held locks, but it
1986 * does not add new dependencies, because trylock can be done
1989 * We look up the chain_key and do the O(N^2) check and update of
1990 * the dependencies only if this is a new dependency chain.
1991 * (If lookup_chain_cache() returns with 1 it acquires
1992 * graph_lock for us)
1994 if (!hlock->trylock && (hlock->check == 2) &&
1995 lookup_chain_cache(curr, hlock, chain_key)) {
1997 * Check whether last held lock:
1999 * - is irq-safe, if this lock is irq-unsafe
2000 * - is softirq-safe, if this lock is hardirq-unsafe
2002 * And check whether the new lock's dependency graph
2003 * could lead back to the previous lock.
2005 * any of these scenarios could lead to a deadlock. If
2008 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2013 * Mark recursive read, as we jump over it when
2014 * building dependencies (just like we jump over
2020 * Add dependency only if this lock is not the head
2021 * of the chain, and if it's not a secondary read-lock:
2023 if (!chain_head && ret != 2)
2024 if (!check_prevs_add(curr, hlock))
2028 /* after lookup_chain_cache(): */
2029 if (unlikely(!debug_locks))
2035 static inline int validate_chain(struct task_struct *curr,
2036 struct lockdep_map *lock, struct held_lock *hlock,
2037 int chain_head, u64 chain_key)
2044 * We are building curr_chain_key incrementally, so double-check
2045 * it from scratch, to make sure that it's done correctly:
2047 static void check_chain_key(struct task_struct *curr)
2049 #ifdef CONFIG_DEBUG_LOCKDEP
2050 struct held_lock *hlock, *prev_hlock = NULL;
2054 for (i = 0; i < curr->lockdep_depth; i++) {
2055 hlock = curr->held_locks + i;
2056 if (chain_key != hlock->prev_chain_key) {
2058 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2059 curr->lockdep_depth, i,
2060 (unsigned long long)chain_key,
2061 (unsigned long long)hlock->prev_chain_key);
2064 id = hlock->class_idx - 1;
2065 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2068 if (prev_hlock && (prev_hlock->irq_context !=
2069 hlock->irq_context))
2071 chain_key = iterate_chain_key(chain_key, id);
2074 if (chain_key != curr->curr_chain_key) {
2076 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2077 curr->lockdep_depth, i,
2078 (unsigned long long)chain_key,
2079 (unsigned long long)curr->curr_chain_key);
2085 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2086 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2088 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2091 printk("\n=================================\n");
2092 printk( "[ INFO: inconsistent lock state ]\n");
2093 print_kernel_version();
2094 printk( "---------------------------------\n");
2096 printk("inconsistent {%s} -> {%s} usage.\n",
2097 usage_str[prev_bit], usage_str[new_bit]);
2099 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2100 curr->comm, task_pid_nr(curr),
2101 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2102 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2103 trace_hardirqs_enabled(curr),
2104 trace_softirqs_enabled(curr));
2107 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2108 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2110 print_irqtrace_events(curr);
2111 printk("\nother info that might help us debug this:\n");
2112 lockdep_print_held_locks(curr);
2114 printk("\nstack backtrace:\n");
2121 * Print out an error if an invalid bit is set:
2124 valid_state(struct task_struct *curr, struct held_lock *this,
2125 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2127 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2128 return print_usage_bug(curr, this, bad_bit, new_bit);
2132 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2133 enum lock_usage_bit new_bit);
2135 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2138 * print irq inversion bug:
2141 print_irq_inversion_bug(struct task_struct *curr,
2142 struct lock_list *root, struct lock_list *other,
2143 struct held_lock *this, int forwards,
2144 const char *irqclass)
2146 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2149 printk("\n=========================================================\n");
2150 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
2151 print_kernel_version();
2152 printk( "---------------------------------------------------------\n");
2153 printk("%s/%d just changed the state of lock:\n",
2154 curr->comm, task_pid_nr(curr));
2157 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2159 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2160 print_lock_name(other->class);
2161 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2163 printk("\nother info that might help us debug this:\n");
2164 lockdep_print_held_locks(curr);
2166 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2167 if (!save_trace(&root->trace))
2169 print_shortest_lock_dependencies(other, root);
2171 printk("\nstack backtrace:\n");
2178 * Prove that in the forwards-direction subgraph starting at <this>
2179 * there is no lock matching <mask>:
2182 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2183 enum lock_usage_bit bit, const char *irqclass)
2186 struct lock_list root;
2187 struct lock_list *uninitialized_var(target_entry);
2190 root.class = hlock_class(this);
2191 ret = find_usage_forwards(&root, bit, &target_entry);
2193 return print_bfs_bug(ret);
2197 return print_irq_inversion_bug(curr, &root, target_entry,
2202 * Prove that in the backwards-direction subgraph starting at <this>
2203 * there is no lock matching <mask>:
2206 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2207 enum lock_usage_bit bit, const char *irqclass)
2210 struct lock_list root;
2211 struct lock_list *uninitialized_var(target_entry);
2214 root.class = hlock_class(this);
2215 ret = find_usage_backwards(&root, bit, &target_entry);
2217 return print_bfs_bug(ret);
2221 return print_irq_inversion_bug(curr, &root, target_entry,
2225 void print_irqtrace_events(struct task_struct *curr)
2227 printk("irq event stamp: %u\n", curr->irq_events);
2228 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2229 print_ip_sym(curr->hardirq_enable_ip);
2230 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2231 print_ip_sym(curr->hardirq_disable_ip);
2232 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2233 print_ip_sym(curr->softirq_enable_ip);
2234 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2235 print_ip_sym(curr->softirq_disable_ip);
2238 static int HARDIRQ_verbose(struct lock_class *class)
2241 return class_filter(class);
2246 static int SOFTIRQ_verbose(struct lock_class *class)
2249 return class_filter(class);
2254 static int RECLAIM_FS_verbose(struct lock_class *class)
2257 return class_filter(class);
2262 #define STRICT_READ_CHECKS 1
2264 static int (*state_verbose_f[])(struct lock_class *class) = {
2265 #define LOCKDEP_STATE(__STATE) \
2267 #include "lockdep_states.h"
2268 #undef LOCKDEP_STATE
2271 static inline int state_verbose(enum lock_usage_bit bit,
2272 struct lock_class *class)
2274 return state_verbose_f[bit >> 2](class);
2277 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2278 enum lock_usage_bit bit, const char *name);
2281 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2282 enum lock_usage_bit new_bit)
2284 int excl_bit = exclusive_bit(new_bit);
2285 int read = new_bit & 1;
2286 int dir = new_bit & 2;
2289 * mark USED_IN has to look forwards -- to ensure no dependency
2290 * has ENABLED state, which would allow recursion deadlocks.
2292 * mark ENABLED has to look backwards -- to ensure no dependee
2293 * has USED_IN state, which, again, would allow recursion deadlocks.
2295 check_usage_f usage = dir ?
2296 check_usage_backwards : check_usage_forwards;
2299 * Validate that this particular lock does not have conflicting
2302 if (!valid_state(curr, this, new_bit, excl_bit))
2306 * Validate that the lock dependencies don't have conflicting usage
2309 if ((!read || !dir || STRICT_READ_CHECKS) &&
2310 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2314 * Check for read in write conflicts
2317 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2320 if (STRICT_READ_CHECKS &&
2321 !usage(curr, this, excl_bit + 1,
2322 state_name(new_bit + 1)))
2326 if (state_verbose(new_bit, hlock_class(this)))
2333 #define LOCKDEP_STATE(__STATE) __STATE,
2334 #include "lockdep_states.h"
2335 #undef LOCKDEP_STATE
2339 * Mark all held locks with a usage bit:
2342 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2344 enum lock_usage_bit usage_bit;
2345 struct held_lock *hlock;
2348 for (i = 0; i < curr->lockdep_depth; i++) {
2349 hlock = curr->held_locks + i;
2351 usage_bit = 2 + (mark << 2); /* ENABLED */
2353 usage_bit += 1; /* READ */
2355 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2357 if (!mark_lock(curr, hlock, usage_bit))
2365 * Hardirqs will be enabled:
2367 void trace_hardirqs_on_caller(unsigned long ip)
2369 struct task_struct *curr = current;
2371 time_hardirqs_on(CALLER_ADDR0, ip);
2373 if (unlikely(!debug_locks || current->lockdep_recursion))
2376 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2379 if (unlikely(curr->hardirqs_enabled)) {
2381 * Neither irq nor preemption are disabled here
2382 * so this is racy by nature but losing one hit
2383 * in a stat is not a big deal.
2385 __debug_atomic_inc(redundant_hardirqs_on);
2388 /* we'll do an OFF -> ON transition: */
2389 curr->hardirqs_enabled = 1;
2391 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2393 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2396 * We are going to turn hardirqs on, so set the
2397 * usage bit for all held locks:
2399 if (!mark_held_locks(curr, HARDIRQ))
2402 * If we have softirqs enabled, then set the usage
2403 * bit for all held locks. (disabled hardirqs prevented
2404 * this bit from being set before)
2406 if (curr->softirqs_enabled)
2407 if (!mark_held_locks(curr, SOFTIRQ))
2410 curr->hardirq_enable_ip = ip;
2411 curr->hardirq_enable_event = ++curr->irq_events;
2412 debug_atomic_inc(hardirqs_on_events);
2414 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2416 void trace_hardirqs_on(void)
2418 trace_hardirqs_on_caller(CALLER_ADDR0);
2420 EXPORT_SYMBOL(trace_hardirqs_on);
2423 * Hardirqs were disabled:
2425 void trace_hardirqs_off_caller(unsigned long ip)
2427 struct task_struct *curr = current;
2429 time_hardirqs_off(CALLER_ADDR0, ip);
2431 if (unlikely(!debug_locks || current->lockdep_recursion))
2434 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2437 if (curr->hardirqs_enabled) {
2439 * We have done an ON -> OFF transition:
2441 curr->hardirqs_enabled = 0;
2442 curr->hardirq_disable_ip = ip;
2443 curr->hardirq_disable_event = ++curr->irq_events;
2444 debug_atomic_inc(hardirqs_off_events);
2446 debug_atomic_inc(redundant_hardirqs_off);
2448 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2450 void trace_hardirqs_off(void)
2452 trace_hardirqs_off_caller(CALLER_ADDR0);
2454 EXPORT_SYMBOL(trace_hardirqs_off);
2457 * Softirqs will be enabled:
2459 void trace_softirqs_on(unsigned long ip)
2461 struct task_struct *curr = current;
2463 if (unlikely(!debug_locks))
2466 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2469 if (curr->softirqs_enabled) {
2470 debug_atomic_inc(redundant_softirqs_on);
2475 * We'll do an OFF -> ON transition:
2477 curr->softirqs_enabled = 1;
2478 curr->softirq_enable_ip = ip;
2479 curr->softirq_enable_event = ++curr->irq_events;
2480 debug_atomic_inc(softirqs_on_events);
2482 * We are going to turn softirqs on, so set the
2483 * usage bit for all held locks, if hardirqs are
2486 if (curr->hardirqs_enabled)
2487 mark_held_locks(curr, SOFTIRQ);
2491 * Softirqs were disabled:
2493 void trace_softirqs_off(unsigned long ip)
2495 struct task_struct *curr = current;
2497 if (unlikely(!debug_locks))
2500 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2503 if (curr->softirqs_enabled) {
2505 * We have done an ON -> OFF transition:
2507 curr->softirqs_enabled = 0;
2508 curr->softirq_disable_ip = ip;
2509 curr->softirq_disable_event = ++curr->irq_events;
2510 debug_atomic_inc(softirqs_off_events);
2511 DEBUG_LOCKS_WARN_ON(!softirq_count());
2513 debug_atomic_inc(redundant_softirqs_off);
2516 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2518 struct task_struct *curr = current;
2520 if (unlikely(!debug_locks))
2523 /* no reclaim without waiting on it */
2524 if (!(gfp_mask & __GFP_WAIT))
2527 /* this guy won't enter reclaim */
2528 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2531 /* We're only interested __GFP_FS allocations for now */
2532 if (!(gfp_mask & __GFP_FS))
2535 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2538 mark_held_locks(curr, RECLAIM_FS);
2541 static void check_flags(unsigned long flags);
2543 void lockdep_trace_alloc(gfp_t gfp_mask)
2545 unsigned long flags;
2547 if (unlikely(current->lockdep_recursion))
2550 raw_local_irq_save(flags);
2552 current->lockdep_recursion = 1;
2553 __lockdep_trace_alloc(gfp_mask, flags);
2554 current->lockdep_recursion = 0;
2555 raw_local_irq_restore(flags);
2558 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2561 * If non-trylock use in a hardirq or softirq context, then
2562 * mark the lock as used in these contexts:
2564 if (!hlock->trylock) {
2566 if (curr->hardirq_context)
2567 if (!mark_lock(curr, hlock,
2568 LOCK_USED_IN_HARDIRQ_READ))
2570 if (curr->softirq_context)
2571 if (!mark_lock(curr, hlock,
2572 LOCK_USED_IN_SOFTIRQ_READ))
2575 if (curr->hardirq_context)
2576 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2578 if (curr->softirq_context)
2579 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2583 if (!hlock->hardirqs_off) {
2585 if (!mark_lock(curr, hlock,
2586 LOCK_ENABLED_HARDIRQ_READ))
2588 if (curr->softirqs_enabled)
2589 if (!mark_lock(curr, hlock,
2590 LOCK_ENABLED_SOFTIRQ_READ))
2593 if (!mark_lock(curr, hlock,
2594 LOCK_ENABLED_HARDIRQ))
2596 if (curr->softirqs_enabled)
2597 if (!mark_lock(curr, hlock,
2598 LOCK_ENABLED_SOFTIRQ))
2604 * We reuse the irq context infrastructure more broadly as a general
2605 * context checking code. This tests GFP_FS recursion (a lock taken
2606 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2609 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2611 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2614 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2622 static int separate_irq_context(struct task_struct *curr,
2623 struct held_lock *hlock)
2625 unsigned int depth = curr->lockdep_depth;
2628 * Keep track of points where we cross into an interrupt context:
2630 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2631 curr->softirq_context;
2633 struct held_lock *prev_hlock;
2635 prev_hlock = curr->held_locks + depth-1;
2637 * If we cross into another context, reset the
2638 * hash key (this also prevents the checking and the
2639 * adding of the dependency to 'prev'):
2641 if (prev_hlock->irq_context != hlock->irq_context)
2650 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2651 enum lock_usage_bit new_bit)
2657 static inline int mark_irqflags(struct task_struct *curr,
2658 struct held_lock *hlock)
2663 static inline int separate_irq_context(struct task_struct *curr,
2664 struct held_lock *hlock)
2669 void lockdep_trace_alloc(gfp_t gfp_mask)
2676 * Mark a lock with a usage bit, and validate the state transition:
2678 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2679 enum lock_usage_bit new_bit)
2681 unsigned int new_mask = 1 << new_bit, ret = 1;
2684 * If already set then do not dirty the cacheline,
2685 * nor do any checks:
2687 if (likely(hlock_class(this)->usage_mask & new_mask))
2693 * Make sure we didn't race:
2695 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2700 hlock_class(this)->usage_mask |= new_mask;
2702 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2706 #define LOCKDEP_STATE(__STATE) \
2707 case LOCK_USED_IN_##__STATE: \
2708 case LOCK_USED_IN_##__STATE##_READ: \
2709 case LOCK_ENABLED_##__STATE: \
2710 case LOCK_ENABLED_##__STATE##_READ:
2711 #include "lockdep_states.h"
2712 #undef LOCKDEP_STATE
2713 ret = mark_lock_irq(curr, this, new_bit);
2718 debug_atomic_dec(nr_unused_locks);
2721 if (!debug_locks_off_graph_unlock())
2730 * We must printk outside of the graph_lock:
2733 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2735 print_irqtrace_events(curr);
2743 * Initialize a lock instance's lock-class mapping info:
2745 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2746 struct lock_class_key *key, int subclass)
2750 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2751 lock->class_cache[i] = NULL;
2753 #ifdef CONFIG_LOCK_STAT
2754 lock->cpu = raw_smp_processor_id();
2757 if (DEBUG_LOCKS_WARN_ON(!name)) {
2758 lock->name = "NULL";
2764 if (DEBUG_LOCKS_WARN_ON(!key))
2767 * Sanity check, the lock-class key must be persistent:
2769 if (!static_obj(key)) {
2770 printk("BUG: key %p not in .data!\n", key);
2771 DEBUG_LOCKS_WARN_ON(1);
2776 if (unlikely(!debug_locks))
2780 register_lock_class(lock, subclass, 1);
2782 EXPORT_SYMBOL_GPL(lockdep_init_map);
2784 struct lock_class_key __lockdep_no_validate__;
2787 * This gets called for every mutex_lock*()/spin_lock*() operation.
2788 * We maintain the dependency maps and validate the locking attempt:
2790 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2791 int trylock, int read, int check, int hardirqs_off,
2792 struct lockdep_map *nest_lock, unsigned long ip,
2795 struct task_struct *curr = current;
2796 struct lock_class *class = NULL;
2797 struct held_lock *hlock;
2798 unsigned int depth, id;
2806 if (unlikely(!debug_locks))
2809 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2812 if (lock->key == &__lockdep_no_validate__)
2815 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
2816 class = lock->class_cache[subclass];
2820 if (unlikely(!class)) {
2821 class = register_lock_class(lock, subclass, 0);
2825 atomic_inc((atomic_t *)&class->ops);
2826 if (very_verbose(class)) {
2827 printk("\nacquire class [%p] %s", class->key, class->name);
2828 if (class->name_version > 1)
2829 printk("#%d", class->name_version);
2835 * Add the lock to the list of currently held locks.
2836 * (we dont increase the depth just yet, up until the
2837 * dependency checks are done)
2839 depth = curr->lockdep_depth;
2840 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2843 class_idx = class - lock_classes + 1;
2846 hlock = curr->held_locks + depth - 1;
2847 if (hlock->class_idx == class_idx && nest_lock) {
2848 if (hlock->references)
2849 hlock->references++;
2851 hlock->references = 2;
2857 hlock = curr->held_locks + depth;
2858 if (DEBUG_LOCKS_WARN_ON(!class))
2860 hlock->class_idx = class_idx;
2861 hlock->acquire_ip = ip;
2862 hlock->instance = lock;
2863 hlock->nest_lock = nest_lock;
2864 hlock->trylock = trylock;
2866 hlock->check = check;
2867 hlock->hardirqs_off = !!hardirqs_off;
2868 hlock->references = references;
2869 #ifdef CONFIG_LOCK_STAT
2870 hlock->waittime_stamp = 0;
2871 hlock->holdtime_stamp = lockstat_clock();
2874 if (check == 2 && !mark_irqflags(curr, hlock))
2877 /* mark it as used: */
2878 if (!mark_lock(curr, hlock, LOCK_USED))
2882 * Calculate the chain hash: it's the combined hash of all the
2883 * lock keys along the dependency chain. We save the hash value
2884 * at every step so that we can get the current hash easily
2885 * after unlock. The chain hash is then used to cache dependency
2888 * The 'key ID' is what is the most compact key value to drive
2889 * the hash, not class->key.
2891 id = class - lock_classes;
2892 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2895 chain_key = curr->curr_chain_key;
2897 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2902 hlock->prev_chain_key = chain_key;
2903 if (separate_irq_context(curr, hlock)) {
2907 chain_key = iterate_chain_key(chain_key, id);
2909 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2912 curr->curr_chain_key = chain_key;
2913 curr->lockdep_depth++;
2914 check_chain_key(curr);
2915 #ifdef CONFIG_DEBUG_LOCKDEP
2916 if (unlikely(!debug_locks))
2919 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2921 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2922 printk("turning off the locking correctness validator.\n");
2927 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2928 max_lockdep_depth = curr->lockdep_depth;
2934 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2937 if (!debug_locks_off())
2939 if (debug_locks_silent)
2942 printk("\n=====================================\n");
2943 printk( "[ BUG: bad unlock balance detected! ]\n");
2944 printk( "-------------------------------------\n");
2945 printk("%s/%d is trying to release lock (",
2946 curr->comm, task_pid_nr(curr));
2947 print_lockdep_cache(lock);
2950 printk("but there are no more locks to release!\n");
2951 printk("\nother info that might help us debug this:\n");
2952 lockdep_print_held_locks(curr);
2954 printk("\nstack backtrace:\n");
2961 * Common debugging checks for both nested and non-nested unlock:
2963 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2966 if (unlikely(!debug_locks))
2968 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2971 if (curr->lockdep_depth <= 0)
2972 return print_unlock_inbalance_bug(curr, lock, ip);
2977 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
2979 if (hlock->instance == lock)
2982 if (hlock->references) {
2983 struct lock_class *class = lock->class_cache[0];
2986 class = look_up_lock_class(lock, 0);
2988 if (DEBUG_LOCKS_WARN_ON(!class))
2991 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
2994 if (hlock->class_idx == class - lock_classes + 1)
3002 __lock_set_class(struct lockdep_map *lock, const char *name,
3003 struct lock_class_key *key, unsigned int subclass,
3006 struct task_struct *curr = current;
3007 struct held_lock *hlock, *prev_hlock;
3008 struct lock_class *class;
3012 depth = curr->lockdep_depth;
3013 if (DEBUG_LOCKS_WARN_ON(!depth))
3017 for (i = depth-1; i >= 0; i--) {
3018 hlock = curr->held_locks + i;
3020 * We must not cross into another context:
3022 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3024 if (match_held_lock(hlock, lock))
3028 return print_unlock_inbalance_bug(curr, lock, ip);
3031 lockdep_init_map(lock, name, key, 0);
3032 class = register_lock_class(lock, subclass, 0);
3033 hlock->class_idx = class - lock_classes + 1;
3035 curr->lockdep_depth = i;
3036 curr->curr_chain_key = hlock->prev_chain_key;
3038 for (; i < depth; i++) {
3039 hlock = curr->held_locks + i;
3040 if (!__lock_acquire(hlock->instance,
3041 hlock_class(hlock)->subclass, hlock->trylock,
3042 hlock->read, hlock->check, hlock->hardirqs_off,
3043 hlock->nest_lock, hlock->acquire_ip,
3048 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3054 * Remove the lock to the list of currently held locks in a
3055 * potentially non-nested (out of order) manner. This is a
3056 * relatively rare operation, as all the unlock APIs default
3057 * to nested mode (which uses lock_release()):
3060 lock_release_non_nested(struct task_struct *curr,
3061 struct lockdep_map *lock, unsigned long ip)
3063 struct held_lock *hlock, *prev_hlock;
3068 * Check whether the lock exists in the current stack
3071 depth = curr->lockdep_depth;
3072 if (DEBUG_LOCKS_WARN_ON(!depth))
3076 for (i = depth-1; i >= 0; i--) {
3077 hlock = curr->held_locks + i;
3079 * We must not cross into another context:
3081 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3083 if (match_held_lock(hlock, lock))
3087 return print_unlock_inbalance_bug(curr, lock, ip);
3090 if (hlock->instance == lock)
3091 lock_release_holdtime(hlock);
3093 if (hlock->references) {
3094 hlock->references--;
3095 if (hlock->references) {
3097 * We had, and after removing one, still have
3098 * references, the current lock stack is still
3099 * valid. We're done!
3106 * We have the right lock to unlock, 'hlock' points to it.
3107 * Now we remove it from the stack, and add back the other
3108 * entries (if any), recalculating the hash along the way:
3111 curr->lockdep_depth = i;
3112 curr->curr_chain_key = hlock->prev_chain_key;
3114 for (i++; i < depth; i++) {
3115 hlock = curr->held_locks + i;
3116 if (!__lock_acquire(hlock->instance,
3117 hlock_class(hlock)->subclass, hlock->trylock,
3118 hlock->read, hlock->check, hlock->hardirqs_off,
3119 hlock->nest_lock, hlock->acquire_ip,
3124 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3130 * Remove the lock to the list of currently held locks - this gets
3131 * called on mutex_unlock()/spin_unlock*() (or on a failed
3132 * mutex_lock_interruptible()). This is done for unlocks that nest
3133 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3135 static int lock_release_nested(struct task_struct *curr,
3136 struct lockdep_map *lock, unsigned long ip)
3138 struct held_lock *hlock;
3142 * Pop off the top of the lock stack:
3144 depth = curr->lockdep_depth - 1;
3145 hlock = curr->held_locks + depth;
3148 * Is the unlock non-nested:
3150 if (hlock->instance != lock || hlock->references)
3151 return lock_release_non_nested(curr, lock, ip);
3152 curr->lockdep_depth--;
3154 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3157 curr->curr_chain_key = hlock->prev_chain_key;
3159 lock_release_holdtime(hlock);
3161 #ifdef CONFIG_DEBUG_LOCKDEP
3162 hlock->prev_chain_key = 0;
3163 hlock->class_idx = 0;
3164 hlock->acquire_ip = 0;
3165 hlock->irq_context = 0;
3171 * Remove the lock to the list of currently held locks - this gets
3172 * called on mutex_unlock()/spin_unlock*() (or on a failed
3173 * mutex_lock_interruptible()). This is done for unlocks that nest
3174 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3177 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3179 struct task_struct *curr = current;
3181 if (!check_unlock(curr, lock, ip))
3185 if (!lock_release_nested(curr, lock, ip))
3188 if (!lock_release_non_nested(curr, lock, ip))
3192 check_chain_key(curr);
3195 static int __lock_is_held(struct lockdep_map *lock)
3197 struct task_struct *curr = current;
3200 for (i = 0; i < curr->lockdep_depth; i++) {
3201 struct held_lock *hlock = curr->held_locks + i;
3203 if (match_held_lock(hlock, lock))
3211 * Check whether we follow the irq-flags state precisely:
3213 static void check_flags(unsigned long flags)
3215 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3216 defined(CONFIG_TRACE_IRQFLAGS)
3220 if (irqs_disabled_flags(flags)) {
3221 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3222 printk("possible reason: unannotated irqs-off.\n");
3225 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3226 printk("possible reason: unannotated irqs-on.\n");
3231 * We dont accurately track softirq state in e.g.
3232 * hardirq contexts (such as on 4KSTACKS), so only
3233 * check if not in hardirq contexts:
3235 if (!hardirq_count()) {
3236 if (softirq_count())
3237 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3239 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3243 print_irqtrace_events(current);
3247 void lock_set_class(struct lockdep_map *lock, const char *name,
3248 struct lock_class_key *key, unsigned int subclass,
3251 unsigned long flags;
3253 if (unlikely(current->lockdep_recursion))
3256 raw_local_irq_save(flags);
3257 current->lockdep_recursion = 1;
3259 if (__lock_set_class(lock, name, key, subclass, ip))
3260 check_chain_key(current);
3261 current->lockdep_recursion = 0;
3262 raw_local_irq_restore(flags);
3264 EXPORT_SYMBOL_GPL(lock_set_class);
3267 * We are not always called with irqs disabled - do that here,
3268 * and also avoid lockdep recursion:
3270 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3271 int trylock, int read, int check,
3272 struct lockdep_map *nest_lock, unsigned long ip)
3274 unsigned long flags;
3276 if (unlikely(current->lockdep_recursion))
3279 raw_local_irq_save(flags);
3282 current->lockdep_recursion = 1;
3283 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3284 __lock_acquire(lock, subclass, trylock, read, check,
3285 irqs_disabled_flags(flags), nest_lock, ip, 0);
3286 current->lockdep_recursion = 0;
3287 raw_local_irq_restore(flags);
3289 EXPORT_SYMBOL_GPL(lock_acquire);
3291 void lock_release(struct lockdep_map *lock, int nested,
3294 unsigned long flags;
3296 if (unlikely(current->lockdep_recursion))
3299 raw_local_irq_save(flags);
3301 current->lockdep_recursion = 1;
3302 trace_lock_release(lock, ip);
3303 __lock_release(lock, nested, ip);
3304 current->lockdep_recursion = 0;
3305 raw_local_irq_restore(flags);
3307 EXPORT_SYMBOL_GPL(lock_release);
3309 int lock_is_held(struct lockdep_map *lock)
3311 unsigned long flags;
3314 if (unlikely(current->lockdep_recursion))
3317 raw_local_irq_save(flags);
3320 current->lockdep_recursion = 1;
3321 ret = __lock_is_held(lock);
3322 current->lockdep_recursion = 0;
3323 raw_local_irq_restore(flags);
3327 EXPORT_SYMBOL_GPL(lock_is_held);
3329 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3331 current->lockdep_reclaim_gfp = gfp_mask;
3334 void lockdep_clear_current_reclaim_state(void)
3336 current->lockdep_reclaim_gfp = 0;
3339 #ifdef CONFIG_LOCK_STAT
3341 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3344 if (!debug_locks_off())
3346 if (debug_locks_silent)
3349 printk("\n=================================\n");
3350 printk( "[ BUG: bad contention detected! ]\n");
3351 printk( "---------------------------------\n");
3352 printk("%s/%d is trying to contend lock (",
3353 curr->comm, task_pid_nr(curr));
3354 print_lockdep_cache(lock);
3357 printk("but there are no locks held!\n");
3358 printk("\nother info that might help us debug this:\n");
3359 lockdep_print_held_locks(curr);
3361 printk("\nstack backtrace:\n");
3368 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3370 struct task_struct *curr = current;
3371 struct held_lock *hlock, *prev_hlock;
3372 struct lock_class_stats *stats;
3374 int i, contention_point, contending_point;
3376 depth = curr->lockdep_depth;
3377 if (DEBUG_LOCKS_WARN_ON(!depth))
3381 for (i = depth-1; i >= 0; i--) {
3382 hlock = curr->held_locks + i;
3384 * We must not cross into another context:
3386 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3388 if (match_held_lock(hlock, lock))
3392 print_lock_contention_bug(curr, lock, ip);
3396 if (hlock->instance != lock)
3399 hlock->waittime_stamp = lockstat_clock();
3401 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3402 contending_point = lock_point(hlock_class(hlock)->contending_point,
3405 stats = get_lock_stats(hlock_class(hlock));
3406 if (contention_point < LOCKSTAT_POINTS)
3407 stats->contention_point[contention_point]++;
3408 if (contending_point < LOCKSTAT_POINTS)
3409 stats->contending_point[contending_point]++;
3410 if (lock->cpu != smp_processor_id())
3411 stats->bounces[bounce_contended + !!hlock->read]++;
3412 put_lock_stats(stats);
3416 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3418 struct task_struct *curr = current;
3419 struct held_lock *hlock, *prev_hlock;
3420 struct lock_class_stats *stats;
3422 u64 now, waittime = 0;
3425 depth = curr->lockdep_depth;
3426 if (DEBUG_LOCKS_WARN_ON(!depth))
3430 for (i = depth-1; i >= 0; i--) {
3431 hlock = curr->held_locks + i;
3433 * We must not cross into another context:
3435 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3437 if (match_held_lock(hlock, lock))
3441 print_lock_contention_bug(curr, lock, _RET_IP_);
3445 if (hlock->instance != lock)
3448 cpu = smp_processor_id();
3449 if (hlock->waittime_stamp) {
3450 now = lockstat_clock();
3451 waittime = now - hlock->waittime_stamp;
3452 hlock->holdtime_stamp = now;
3455 trace_lock_acquired(lock, ip);
3457 stats = get_lock_stats(hlock_class(hlock));
3460 lock_time_inc(&stats->read_waittime, waittime);
3462 lock_time_inc(&stats->write_waittime, waittime);
3464 if (lock->cpu != cpu)
3465 stats->bounces[bounce_acquired + !!hlock->read]++;
3466 put_lock_stats(stats);
3472 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3474 unsigned long flags;
3476 if (unlikely(!lock_stat))
3479 if (unlikely(current->lockdep_recursion))
3482 raw_local_irq_save(flags);
3484 current->lockdep_recursion = 1;
3485 trace_lock_contended(lock, ip);
3486 __lock_contended(lock, ip);
3487 current->lockdep_recursion = 0;
3488 raw_local_irq_restore(flags);
3490 EXPORT_SYMBOL_GPL(lock_contended);
3492 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3494 unsigned long flags;
3496 if (unlikely(!lock_stat))
3499 if (unlikely(current->lockdep_recursion))
3502 raw_local_irq_save(flags);
3504 current->lockdep_recursion = 1;
3505 __lock_acquired(lock, ip);
3506 current->lockdep_recursion = 0;
3507 raw_local_irq_restore(flags);
3509 EXPORT_SYMBOL_GPL(lock_acquired);
3513 * Used by the testsuite, sanitize the validator state
3514 * after a simulated failure:
3517 void lockdep_reset(void)
3519 unsigned long flags;
3522 raw_local_irq_save(flags);
3523 current->curr_chain_key = 0;
3524 current->lockdep_depth = 0;
3525 current->lockdep_recursion = 0;
3526 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3527 nr_hardirq_chains = 0;
3528 nr_softirq_chains = 0;
3529 nr_process_chains = 0;
3531 for (i = 0; i < CHAINHASH_SIZE; i++)
3532 INIT_LIST_HEAD(chainhash_table + i);
3533 raw_local_irq_restore(flags);
3536 static void zap_class(struct lock_class *class)
3541 * Remove all dependencies this lock is
3544 for (i = 0; i < nr_list_entries; i++) {
3545 if (list_entries[i].class == class)
3546 list_del_rcu(&list_entries[i].entry);
3549 * Unhash the class and remove it from the all_lock_classes list:
3551 list_del_rcu(&class->hash_entry);
3552 list_del_rcu(&class->lock_entry);
3557 static inline int within(const void *addr, void *start, unsigned long size)
3559 return addr >= start && addr < start + size;
3562 void lockdep_free_key_range(void *start, unsigned long size)
3564 struct lock_class *class, *next;
3565 struct list_head *head;
3566 unsigned long flags;
3570 raw_local_irq_save(flags);
3571 locked = graph_lock();
3574 * Unhash all classes that were created by this module:
3576 for (i = 0; i < CLASSHASH_SIZE; i++) {
3577 head = classhash_table + i;
3578 if (list_empty(head))
3580 list_for_each_entry_safe(class, next, head, hash_entry) {
3581 if (within(class->key, start, size))
3583 else if (within(class->name, start, size))
3590 raw_local_irq_restore(flags);
3593 void lockdep_reset_lock(struct lockdep_map *lock)
3595 struct lock_class *class, *next;
3596 struct list_head *head;
3597 unsigned long flags;
3601 raw_local_irq_save(flags);
3604 * Remove all classes this lock might have:
3606 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3608 * If the class exists we look it up and zap it:
3610 class = look_up_lock_class(lock, j);
3615 * Debug check: in the end all mapped classes should
3618 locked = graph_lock();
3619 for (i = 0; i < CLASSHASH_SIZE; i++) {
3620 head = classhash_table + i;
3621 if (list_empty(head))
3623 list_for_each_entry_safe(class, next, head, hash_entry) {
3626 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3627 match |= class == lock->class_cache[j];
3629 if (unlikely(match)) {
3630 if (debug_locks_off_graph_unlock())
3640 raw_local_irq_restore(flags);
3643 void lockdep_init(void)
3648 * Some architectures have their own start_kernel()
3649 * code which calls lockdep_init(), while we also
3650 * call lockdep_init() from the start_kernel() itself,
3651 * and we want to initialize the hashes only once:
3653 if (lockdep_initialized)
3656 for (i = 0; i < CLASSHASH_SIZE; i++)
3657 INIT_LIST_HEAD(classhash_table + i);
3659 for (i = 0; i < CHAINHASH_SIZE; i++)
3660 INIT_LIST_HEAD(chainhash_table + i);
3662 lockdep_initialized = 1;
3665 void __init lockdep_info(void)
3667 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3669 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3670 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3671 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3672 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3673 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3674 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3675 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3677 printk(" memory used by lock dependency info: %lu kB\n",
3678 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3679 sizeof(struct list_head) * CLASSHASH_SIZE +
3680 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3681 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3682 sizeof(struct list_head) * CHAINHASH_SIZE
3683 #ifdef CONFIG_PROVE_LOCKING
3684 + sizeof(struct circular_queue)
3689 printk(" per task-struct memory footprint: %lu bytes\n",
3690 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3692 #ifdef CONFIG_DEBUG_LOCKDEP
3693 if (lockdep_init_error) {
3694 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3695 printk("Call stack leading to lockdep invocation was:\n");
3696 print_stack_trace(&lockdep_init_trace, 0);
3702 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3703 const void *mem_to, struct held_lock *hlock)
3705 if (!debug_locks_off())
3707 if (debug_locks_silent)
3710 printk("\n=========================\n");
3711 printk( "[ BUG: held lock freed! ]\n");
3712 printk( "-------------------------\n");
3713 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3714 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3716 lockdep_print_held_locks(curr);
3718 printk("\nstack backtrace:\n");
3722 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3723 const void* lock_from, unsigned long lock_len)
3725 return lock_from + lock_len <= mem_from ||
3726 mem_from + mem_len <= lock_from;
3730 * Called when kernel memory is freed (or unmapped), or if a lock
3731 * is destroyed or reinitialized - this code checks whether there is
3732 * any held lock in the memory range of <from> to <to>:
3734 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3736 struct task_struct *curr = current;
3737 struct held_lock *hlock;
3738 unsigned long flags;
3741 if (unlikely(!debug_locks))
3744 local_irq_save(flags);
3745 for (i = 0; i < curr->lockdep_depth; i++) {
3746 hlock = curr->held_locks + i;
3748 if (not_in_range(mem_from, mem_len, hlock->instance,
3749 sizeof(*hlock->instance)))
3752 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3755 local_irq_restore(flags);
3757 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3759 static void print_held_locks_bug(struct task_struct *curr)
3761 if (!debug_locks_off())
3763 if (debug_locks_silent)
3766 printk("\n=====================================\n");
3767 printk( "[ BUG: lock held at task exit time! ]\n");
3768 printk( "-------------------------------------\n");
3769 printk("%s/%d is exiting with locks still held!\n",
3770 curr->comm, task_pid_nr(curr));
3771 lockdep_print_held_locks(curr);
3773 printk("\nstack backtrace:\n");
3777 void debug_check_no_locks_held(struct task_struct *task)
3779 if (unlikely(task->lockdep_depth > 0))
3780 print_held_locks_bug(task);
3783 void debug_show_all_locks(void)
3785 struct task_struct *g, *p;
3789 if (unlikely(!debug_locks)) {
3790 printk("INFO: lockdep is turned off.\n");
3793 printk("\nShowing all locks held in the system:\n");
3796 * Here we try to get the tasklist_lock as hard as possible,
3797 * if not successful after 2 seconds we ignore it (but keep
3798 * trying). This is to enable a debug printout even if a
3799 * tasklist_lock-holding task deadlocks or crashes.
3802 if (!read_trylock(&tasklist_lock)) {
3804 printk("hm, tasklist_lock locked, retrying... ");
3807 printk(" #%d", 10-count);
3811 printk(" ignoring it.\n");
3815 printk(KERN_CONT " locked it.\n");
3818 do_each_thread(g, p) {
3820 * It's not reliable to print a task's held locks
3821 * if it's not sleeping (or if it's not the current
3824 if (p->state == TASK_RUNNING && p != current)
3826 if (p->lockdep_depth)
3827 lockdep_print_held_locks(p);
3829 if (read_trylock(&tasklist_lock))
3831 } while_each_thread(g, p);
3834 printk("=============================================\n\n");
3837 read_unlock(&tasklist_lock);
3839 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3842 * Careful: only use this function if you are sure that
3843 * the task cannot run in parallel!
3845 void debug_show_held_locks(struct task_struct *task)
3847 if (unlikely(!debug_locks)) {
3848 printk("INFO: lockdep is turned off.\n");
3851 lockdep_print_held_locks(task);
3853 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3855 void lockdep_sys_exit(void)
3857 struct task_struct *curr = current;
3859 if (unlikely(curr->lockdep_depth)) {
3860 if (!debug_locks_off())
3862 printk("\n================================================\n");
3863 printk( "[ BUG: lock held when returning to user space! ]\n");
3864 printk( "------------------------------------------------\n");
3865 printk("%s/%d is leaving the kernel with locks still held!\n",
3866 curr->comm, curr->pid);
3867 lockdep_print_held_locks(curr);
3871 void lockdep_rcu_dereference(const char *file, const int line)
3873 struct task_struct *curr = current;
3875 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
3876 if (!debug_locks_off())
3878 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
3879 /* Note: the following can be executed concurrently, so be careful. */
3880 printk("\n===================================================\n");
3881 printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3882 printk( "---------------------------------------------------\n");
3883 printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3885 printk("\nother info that might help us debug this:\n\n");
3886 printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
3887 lockdep_print_held_locks(curr);
3888 printk("\nstack backtrace:\n");
3891 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);