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 print_circular_lock_scenario(struct held_lock *src,
1070 struct held_lock *tgt,
1071 struct lock_list *prt)
1073 struct lock_class *source = hlock_class(src);
1074 struct lock_class *target = hlock_class(tgt);
1075 struct lock_class *parent = prt->class;
1078 * A direct locking problem where unsafe_class lock is taken
1079 * directly by safe_class lock, then all we need to show
1080 * is the deadlock scenario, as it is obvious that the
1081 * unsafe lock is taken under the safe lock.
1083 * But if there is a chain instead, where the safe lock takes
1084 * an intermediate lock (middle_class) where this lock is
1085 * not the same as the safe lock, then the lock chain is
1086 * used to describe the problem. Otherwise we would need
1087 * to show a different CPU case for each link in the chain
1088 * from the safe_class lock to the unsafe_class lock.
1090 if (parent != source) {
1091 printk("Chain exists of:\n ");
1092 __print_lock_name(source);
1094 __print_lock_name(parent);
1096 __print_lock_name(target);
1100 printk(" Possible unsafe locking scenario:\n\n");
1101 printk(" CPU0 CPU1\n");
1102 printk(" ---- ----\n");
1104 __print_lock_name(target);
1107 __print_lock_name(parent);
1110 __print_lock_name(target);
1113 __print_lock_name(source);
1115 printk("\n *** DEADLOCK ***\n\n");
1119 * When a circular dependency is detected, print the
1123 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1124 struct held_lock *check_src,
1125 struct held_lock *check_tgt)
1127 struct task_struct *curr = current;
1129 if (debug_locks_silent)
1132 printk("\n=======================================================\n");
1133 printk( "[ INFO: possible circular locking dependency detected ]\n");
1134 print_kernel_version();
1135 printk( "-------------------------------------------------------\n");
1136 printk("%s/%d is trying to acquire lock:\n",
1137 curr->comm, task_pid_nr(curr));
1138 print_lock(check_src);
1139 printk("\nbut task is already holding lock:\n");
1140 print_lock(check_tgt);
1141 printk("\nwhich lock already depends on the new lock.\n\n");
1142 printk("\nthe existing dependency chain (in reverse order) is:\n");
1144 print_circular_bug_entry(entry, depth);
1149 static inline int class_equal(struct lock_list *entry, void *data)
1151 return entry->class == data;
1154 static noinline int print_circular_bug(struct lock_list *this,
1155 struct lock_list *target,
1156 struct held_lock *check_src,
1157 struct held_lock *check_tgt)
1159 struct task_struct *curr = current;
1160 struct lock_list *parent;
1161 struct lock_list *first_parent;
1164 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1167 if (!save_trace(&this->trace))
1170 depth = get_lock_depth(target);
1172 print_circular_bug_header(target, depth, check_src, check_tgt);
1174 parent = get_lock_parent(target);
1175 first_parent = parent;
1178 print_circular_bug_entry(parent, --depth);
1179 parent = get_lock_parent(parent);
1182 printk("\nother info that might help us debug this:\n\n");
1183 print_circular_lock_scenario(check_src, check_tgt,
1186 lockdep_print_held_locks(curr);
1188 printk("\nstack backtrace:\n");
1194 static noinline int print_bfs_bug(int ret)
1196 if (!debug_locks_off_graph_unlock())
1199 WARN(1, "lockdep bfs error:%d\n", ret);
1204 static int noop_count(struct lock_list *entry, void *data)
1206 (*(unsigned long *)data)++;
1210 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1212 unsigned long count = 0;
1213 struct lock_list *uninitialized_var(target_entry);
1215 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1219 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1221 unsigned long ret, flags;
1222 struct lock_list this;
1227 local_irq_save(flags);
1228 arch_spin_lock(&lockdep_lock);
1229 ret = __lockdep_count_forward_deps(&this);
1230 arch_spin_unlock(&lockdep_lock);
1231 local_irq_restore(flags);
1236 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1238 unsigned long count = 0;
1239 struct lock_list *uninitialized_var(target_entry);
1241 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1246 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1248 unsigned long ret, flags;
1249 struct lock_list this;
1254 local_irq_save(flags);
1255 arch_spin_lock(&lockdep_lock);
1256 ret = __lockdep_count_backward_deps(&this);
1257 arch_spin_unlock(&lockdep_lock);
1258 local_irq_restore(flags);
1264 * Prove that the dependency graph starting at <entry> can not
1265 * lead to <target>. Print an error and return 0 if it does.
1268 check_noncircular(struct lock_list *root, struct lock_class *target,
1269 struct lock_list **target_entry)
1273 debug_atomic_inc(nr_cyclic_checks);
1275 result = __bfs_forwards(root, target, class_equal, target_entry);
1280 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1282 * Forwards and backwards subgraph searching, for the purposes of
1283 * proving that two subgraphs can be connected by a new dependency
1284 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1287 static inline int usage_match(struct lock_list *entry, void *bit)
1289 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1295 * Find a node in the forwards-direction dependency sub-graph starting
1296 * at @root->class that matches @bit.
1298 * Return 0 if such a node exists in the subgraph, and put that node
1299 * into *@target_entry.
1301 * Return 1 otherwise and keep *@target_entry unchanged.
1302 * Return <0 on error.
1305 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1306 struct lock_list **target_entry)
1310 debug_atomic_inc(nr_find_usage_forwards_checks);
1312 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1318 * Find a node in the backwards-direction dependency sub-graph starting
1319 * at @root->class that matches @bit.
1321 * Return 0 if such a node exists in the subgraph, and put that node
1322 * into *@target_entry.
1324 * Return 1 otherwise and keep *@target_entry unchanged.
1325 * Return <0 on error.
1328 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1329 struct lock_list **target_entry)
1333 debug_atomic_inc(nr_find_usage_backwards_checks);
1335 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1340 static void print_lock_class_header(struct lock_class *class, int depth)
1344 printk("%*s->", depth, "");
1345 print_lock_name(class);
1346 printk(" ops: %lu", class->ops);
1349 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1350 if (class->usage_mask & (1 << bit)) {
1353 len += printk("%*s %s", depth, "", usage_str[bit]);
1354 len += printk(" at:\n");
1355 print_stack_trace(class->usage_traces + bit, len);
1358 printk("%*s }\n", depth, "");
1360 printk("%*s ... key at: ",depth,"");
1361 print_ip_sym((unsigned long)class->key);
1365 * printk the shortest lock dependencies from @start to @end in reverse order:
1368 print_shortest_lock_dependencies(struct lock_list *leaf,
1369 struct lock_list *root)
1371 struct lock_list *entry = leaf;
1374 /*compute depth from generated tree by BFS*/
1375 depth = get_lock_depth(leaf);
1378 print_lock_class_header(entry->class, depth);
1379 printk("%*s ... acquired at:\n", depth, "");
1380 print_stack_trace(&entry->trace, 2);
1383 if (depth == 0 && (entry != root)) {
1384 printk("lockdep:%s bad BFS generated tree\n", __func__);
1388 entry = get_lock_parent(entry);
1390 } while (entry && (depth >= 0));
1396 print_irq_lock_scenario(struct lock_list *safe_entry,
1397 struct lock_list *unsafe_entry,
1398 struct held_lock *prev,
1399 struct held_lock *next)
1401 struct lock_class *safe_class = safe_entry->class;
1402 struct lock_class *unsafe_class = unsafe_entry->class;
1403 struct lock_class *middle_class = hlock_class(prev);
1405 if (middle_class == safe_class)
1406 middle_class = hlock_class(next);
1409 * A direct locking problem where unsafe_class lock is taken
1410 * directly by safe_class lock, then all we need to show
1411 * is the deadlock scenario, as it is obvious that the
1412 * unsafe lock is taken under the safe lock.
1414 * But if there is a chain instead, where the safe lock takes
1415 * an intermediate lock (middle_class) where this lock is
1416 * not the same as the safe lock, then the lock chain is
1417 * used to describe the problem. Otherwise we would need
1418 * to show a different CPU case for each link in the chain
1419 * from the safe_class lock to the unsafe_class lock.
1421 if (middle_class != unsafe_class) {
1422 printk("Chain exists of:\n ");
1423 __print_lock_name(safe_class);
1425 __print_lock_name(middle_class);
1427 __print_lock_name(unsafe_class);
1431 printk(" Possible interrupt unsafe locking scenario:\n\n");
1432 printk(" CPU0 CPU1\n");
1433 printk(" ---- ----\n");
1435 __print_lock_name(unsafe_class);
1437 printk(" local_irq_disable();\n");
1439 __print_lock_name(safe_class);
1442 __print_lock_name(middle_class);
1444 printk(" <Interrupt>\n");
1446 __print_lock_name(safe_class);
1448 printk("\n *** DEADLOCK ***\n\n");
1452 print_bad_irq_dependency(struct task_struct *curr,
1453 struct lock_list *prev_root,
1454 struct lock_list *next_root,
1455 struct lock_list *backwards_entry,
1456 struct lock_list *forwards_entry,
1457 struct held_lock *prev,
1458 struct held_lock *next,
1459 enum lock_usage_bit bit1,
1460 enum lock_usage_bit bit2,
1461 const char *irqclass)
1463 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1466 printk("\n======================================================\n");
1467 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1468 irqclass, irqclass);
1469 print_kernel_version();
1470 printk( "------------------------------------------------------\n");
1471 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1472 curr->comm, task_pid_nr(curr),
1473 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1474 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1475 curr->hardirqs_enabled,
1476 curr->softirqs_enabled);
1479 printk("\nand this task is already holding:\n");
1481 printk("which would create a new lock dependency:\n");
1482 print_lock_name(hlock_class(prev));
1484 print_lock_name(hlock_class(next));
1487 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1489 print_lock_name(backwards_entry->class);
1490 printk("\n... which became %s-irq-safe at:\n", irqclass);
1492 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1494 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1495 print_lock_name(forwards_entry->class);
1496 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1499 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1501 printk("\nother info that might help us debug this:\n\n");
1502 print_irq_lock_scenario(backwards_entry, forwards_entry, prev, next);
1504 lockdep_print_held_locks(curr);
1506 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1507 printk(" and the holding lock:\n");
1508 if (!save_trace(&prev_root->trace))
1510 print_shortest_lock_dependencies(backwards_entry, prev_root);
1512 printk("\nthe dependencies between the lock to be acquired");
1513 printk(" and %s-irq-unsafe lock:\n", irqclass);
1514 if (!save_trace(&next_root->trace))
1516 print_shortest_lock_dependencies(forwards_entry, next_root);
1518 printk("\nstack backtrace:\n");
1525 check_usage(struct task_struct *curr, struct held_lock *prev,
1526 struct held_lock *next, enum lock_usage_bit bit_backwards,
1527 enum lock_usage_bit bit_forwards, const char *irqclass)
1530 struct lock_list this, that;
1531 struct lock_list *uninitialized_var(target_entry);
1532 struct lock_list *uninitialized_var(target_entry1);
1536 this.class = hlock_class(prev);
1537 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1539 return print_bfs_bug(ret);
1544 that.class = hlock_class(next);
1545 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1547 return print_bfs_bug(ret);
1551 return print_bad_irq_dependency(curr, &this, &that,
1552 target_entry, target_entry1,
1554 bit_backwards, bit_forwards, irqclass);
1557 static const char *state_names[] = {
1558 #define LOCKDEP_STATE(__STATE) \
1559 __stringify(__STATE),
1560 #include "lockdep_states.h"
1561 #undef LOCKDEP_STATE
1564 static const char *state_rnames[] = {
1565 #define LOCKDEP_STATE(__STATE) \
1566 __stringify(__STATE)"-READ",
1567 #include "lockdep_states.h"
1568 #undef LOCKDEP_STATE
1571 static inline const char *state_name(enum lock_usage_bit bit)
1573 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1576 static int exclusive_bit(int new_bit)
1584 * bit 0 - write/read
1585 * bit 1 - used_in/enabled
1589 int state = new_bit & ~3;
1590 int dir = new_bit & 2;
1593 * keep state, bit flip the direction and strip read.
1595 return state | (dir ^ 2);
1598 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1599 struct held_lock *next, enum lock_usage_bit bit)
1602 * Prove that the new dependency does not connect a hardirq-safe
1603 * lock with a hardirq-unsafe lock - to achieve this we search
1604 * the backwards-subgraph starting at <prev>, and the
1605 * forwards-subgraph starting at <next>:
1607 if (!check_usage(curr, prev, next, bit,
1608 exclusive_bit(bit), state_name(bit)))
1614 * Prove that the new dependency does not connect a hardirq-safe-read
1615 * lock with a hardirq-unsafe lock - to achieve this we search
1616 * the backwards-subgraph starting at <prev>, and the
1617 * forwards-subgraph starting at <next>:
1619 if (!check_usage(curr, prev, next, bit,
1620 exclusive_bit(bit), state_name(bit)))
1627 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1628 struct held_lock *next)
1630 #define LOCKDEP_STATE(__STATE) \
1631 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1633 #include "lockdep_states.h"
1634 #undef LOCKDEP_STATE
1639 static void inc_chains(void)
1641 if (current->hardirq_context)
1642 nr_hardirq_chains++;
1644 if (current->softirq_context)
1645 nr_softirq_chains++;
1647 nr_process_chains++;
1654 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1655 struct held_lock *next)
1660 static inline void inc_chains(void)
1662 nr_process_chains++;
1668 print_deadlock_scenario(struct held_lock *nxt,
1669 struct held_lock *prv)
1671 struct lock_class *next = hlock_class(nxt);
1672 struct lock_class *prev = hlock_class(prv);
1674 printk(" Possible unsafe locking scenario:\n\n");
1678 __print_lock_name(prev);
1681 __print_lock_name(next);
1683 printk("\n *** DEADLOCK ***\n\n");
1684 printk(" May be due to missing lock nesting notation\n\n");
1688 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1689 struct held_lock *next)
1691 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1694 printk("\n=============================================\n");
1695 printk( "[ INFO: possible recursive locking detected ]\n");
1696 print_kernel_version();
1697 printk( "---------------------------------------------\n");
1698 printk("%s/%d is trying to acquire lock:\n",
1699 curr->comm, task_pid_nr(curr));
1701 printk("\nbut task is already holding lock:\n");
1704 printk("\nother info that might help us debug this:\n");
1705 print_deadlock_scenario(next, prev);
1706 lockdep_print_held_locks(curr);
1708 printk("\nstack backtrace:\n");
1715 * Check whether we are holding such a class already.
1717 * (Note that this has to be done separately, because the graph cannot
1718 * detect such classes of deadlocks.)
1720 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1723 check_deadlock(struct task_struct *curr, struct held_lock *next,
1724 struct lockdep_map *next_instance, int read)
1726 struct held_lock *prev;
1727 struct held_lock *nest = NULL;
1730 for (i = 0; i < curr->lockdep_depth; i++) {
1731 prev = curr->held_locks + i;
1733 if (prev->instance == next->nest_lock)
1736 if (hlock_class(prev) != hlock_class(next))
1740 * Allow read-after-read recursion of the same
1741 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1743 if ((read == 2) && prev->read)
1747 * We're holding the nest_lock, which serializes this lock's
1748 * nesting behaviour.
1753 return print_deadlock_bug(curr, prev, next);
1759 * There was a chain-cache miss, and we are about to add a new dependency
1760 * to a previous lock. We recursively validate the following rules:
1762 * - would the adding of the <prev> -> <next> dependency create a
1763 * circular dependency in the graph? [== circular deadlock]
1765 * - does the new prev->next dependency connect any hardirq-safe lock
1766 * (in the full backwards-subgraph starting at <prev>) with any
1767 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1768 * <next>)? [== illegal lock inversion with hardirq contexts]
1770 * - does the new prev->next dependency connect any softirq-safe lock
1771 * (in the full backwards-subgraph starting at <prev>) with any
1772 * softirq-unsafe lock (in the full forwards-subgraph starting at
1773 * <next>)? [== illegal lock inversion with softirq contexts]
1775 * any of these scenarios could lead to a deadlock.
1777 * Then if all the validations pass, we add the forwards and backwards
1781 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1782 struct held_lock *next, int distance, int trylock_loop)
1784 struct lock_list *entry;
1786 struct lock_list this;
1787 struct lock_list *uninitialized_var(target_entry);
1789 * Static variable, serialized by the graph_lock().
1791 * We use this static variable to save the stack trace in case
1792 * we call into this function multiple times due to encountering
1793 * trylocks in the held lock stack.
1795 static struct stack_trace trace;
1798 * Prove that the new <prev> -> <next> dependency would not
1799 * create a circular dependency in the graph. (We do this by
1800 * forward-recursing into the graph starting at <next>, and
1801 * checking whether we can reach <prev>.)
1803 * We are using global variables to control the recursion, to
1804 * keep the stackframe size of the recursive functions low:
1806 this.class = hlock_class(next);
1808 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1810 return print_circular_bug(&this, target_entry, next, prev);
1811 else if (unlikely(ret < 0))
1812 return print_bfs_bug(ret);
1814 if (!check_prev_add_irq(curr, prev, next))
1818 * For recursive read-locks we do all the dependency checks,
1819 * but we dont store read-triggered dependencies (only
1820 * write-triggered dependencies). This ensures that only the
1821 * write-side dependencies matter, and that if for example a
1822 * write-lock never takes any other locks, then the reads are
1823 * equivalent to a NOP.
1825 if (next->read == 2 || prev->read == 2)
1828 * Is the <prev> -> <next> dependency already present?
1830 * (this may occur even though this is a new chain: consider
1831 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1832 * chains - the second one will be new, but L1 already has
1833 * L2 added to its dependency list, due to the first chain.)
1835 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1836 if (entry->class == hlock_class(next)) {
1838 entry->distance = 1;
1843 if (!trylock_loop && !save_trace(&trace))
1847 * Ok, all validations passed, add the new lock
1848 * to the previous lock's dependency list:
1850 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1851 &hlock_class(prev)->locks_after,
1852 next->acquire_ip, distance, &trace);
1857 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1858 &hlock_class(next)->locks_before,
1859 next->acquire_ip, distance, &trace);
1864 * Debugging printouts:
1866 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1868 printk("\n new dependency: ");
1869 print_lock_name(hlock_class(prev));
1871 print_lock_name(hlock_class(next));
1874 return graph_lock();
1880 * Add the dependency to all directly-previous locks that are 'relevant'.
1881 * The ones that are relevant are (in increasing distance from curr):
1882 * all consecutive trylock entries and the final non-trylock entry - or
1883 * the end of this context's lock-chain - whichever comes first.
1886 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1888 int depth = curr->lockdep_depth;
1889 int trylock_loop = 0;
1890 struct held_lock *hlock;
1895 * Depth must not be zero for a non-head lock:
1900 * At least two relevant locks must exist for this
1903 if (curr->held_locks[depth].irq_context !=
1904 curr->held_locks[depth-1].irq_context)
1908 int distance = curr->lockdep_depth - depth + 1;
1909 hlock = curr->held_locks + depth-1;
1911 * Only non-recursive-read entries get new dependencies
1914 if (hlock->read != 2) {
1915 if (!check_prev_add(curr, hlock, next,
1916 distance, trylock_loop))
1919 * Stop after the first non-trylock entry,
1920 * as non-trylock entries have added their
1921 * own direct dependencies already, so this
1922 * lock is connected to them indirectly:
1924 if (!hlock->trylock)
1929 * End of lock-stack?
1934 * Stop the search if we cross into another context:
1936 if (curr->held_locks[depth].irq_context !=
1937 curr->held_locks[depth-1].irq_context)
1943 if (!debug_locks_off_graph_unlock())
1951 unsigned long nr_lock_chains;
1952 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1953 int nr_chain_hlocks;
1954 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1956 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1958 return lock_classes + chain_hlocks[chain->base + i];
1962 * Look up a dependency chain. If the key is not present yet then
1963 * add it and return 1 - in this case the new dependency chain is
1964 * validated. If the key is already hashed, return 0.
1965 * (On return with 1 graph_lock is held.)
1967 static inline int lookup_chain_cache(struct task_struct *curr,
1968 struct held_lock *hlock,
1971 struct lock_class *class = hlock_class(hlock);
1972 struct list_head *hash_head = chainhashentry(chain_key);
1973 struct lock_chain *chain;
1974 struct held_lock *hlock_curr, *hlock_next;
1977 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1980 * We can walk it lock-free, because entries only get added
1983 list_for_each_entry(chain, hash_head, entry) {
1984 if (chain->chain_key == chain_key) {
1986 debug_atomic_inc(chain_lookup_hits);
1987 if (very_verbose(class))
1988 printk("\nhash chain already cached, key: "
1989 "%016Lx tail class: [%p] %s\n",
1990 (unsigned long long)chain_key,
1991 class->key, class->name);
1995 if (very_verbose(class))
1996 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1997 (unsigned long long)chain_key, class->key, class->name);
1999 * Allocate a new chain entry from the static array, and add
2005 * We have to walk the chain again locked - to avoid duplicates:
2007 list_for_each_entry(chain, hash_head, entry) {
2008 if (chain->chain_key == chain_key) {
2013 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2014 if (!debug_locks_off_graph_unlock())
2017 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2018 printk("turning off the locking correctness validator.\n");
2022 chain = lock_chains + nr_lock_chains++;
2023 chain->chain_key = chain_key;
2024 chain->irq_context = hlock->irq_context;
2025 /* Find the first held_lock of current chain */
2027 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2028 hlock_curr = curr->held_locks + i;
2029 if (hlock_curr->irq_context != hlock_next->irq_context)
2034 chain->depth = curr->lockdep_depth + 1 - i;
2035 cn = nr_chain_hlocks;
2036 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
2037 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
2042 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2044 for (j = 0; j < chain->depth - 1; j++, i++) {
2045 int lock_id = curr->held_locks[i].class_idx - 1;
2046 chain_hlocks[chain->base + j] = lock_id;
2048 chain_hlocks[chain->base + j] = class - lock_classes;
2050 list_add_tail_rcu(&chain->entry, hash_head);
2051 debug_atomic_inc(chain_lookup_misses);
2057 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2058 struct held_lock *hlock, int chain_head, u64 chain_key)
2061 * Trylock needs to maintain the stack of held locks, but it
2062 * does not add new dependencies, because trylock can be done
2065 * We look up the chain_key and do the O(N^2) check and update of
2066 * the dependencies only if this is a new dependency chain.
2067 * (If lookup_chain_cache() returns with 1 it acquires
2068 * graph_lock for us)
2070 if (!hlock->trylock && (hlock->check == 2) &&
2071 lookup_chain_cache(curr, hlock, chain_key)) {
2073 * Check whether last held lock:
2075 * - is irq-safe, if this lock is irq-unsafe
2076 * - is softirq-safe, if this lock is hardirq-unsafe
2078 * And check whether the new lock's dependency graph
2079 * could lead back to the previous lock.
2081 * any of these scenarios could lead to a deadlock. If
2084 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2089 * Mark recursive read, as we jump over it when
2090 * building dependencies (just like we jump over
2096 * Add dependency only if this lock is not the head
2097 * of the chain, and if it's not a secondary read-lock:
2099 if (!chain_head && ret != 2)
2100 if (!check_prevs_add(curr, hlock))
2104 /* after lookup_chain_cache(): */
2105 if (unlikely(!debug_locks))
2111 static inline int validate_chain(struct task_struct *curr,
2112 struct lockdep_map *lock, struct held_lock *hlock,
2113 int chain_head, u64 chain_key)
2120 * We are building curr_chain_key incrementally, so double-check
2121 * it from scratch, to make sure that it's done correctly:
2123 static void check_chain_key(struct task_struct *curr)
2125 #ifdef CONFIG_DEBUG_LOCKDEP
2126 struct held_lock *hlock, *prev_hlock = NULL;
2130 for (i = 0; i < curr->lockdep_depth; i++) {
2131 hlock = curr->held_locks + i;
2132 if (chain_key != hlock->prev_chain_key) {
2134 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2135 curr->lockdep_depth, i,
2136 (unsigned long long)chain_key,
2137 (unsigned long long)hlock->prev_chain_key);
2140 id = hlock->class_idx - 1;
2141 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2144 if (prev_hlock && (prev_hlock->irq_context !=
2145 hlock->irq_context))
2147 chain_key = iterate_chain_key(chain_key, id);
2150 if (chain_key != curr->curr_chain_key) {
2152 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2153 curr->lockdep_depth, i,
2154 (unsigned long long)chain_key,
2155 (unsigned long long)curr->curr_chain_key);
2161 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2162 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2164 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2167 printk("\n=================================\n");
2168 printk( "[ INFO: inconsistent lock state ]\n");
2169 print_kernel_version();
2170 printk( "---------------------------------\n");
2172 printk("inconsistent {%s} -> {%s} usage.\n",
2173 usage_str[prev_bit], usage_str[new_bit]);
2175 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2176 curr->comm, task_pid_nr(curr),
2177 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2178 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2179 trace_hardirqs_enabled(curr),
2180 trace_softirqs_enabled(curr));
2183 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2184 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2186 print_irqtrace_events(curr);
2187 printk("\nother info that might help us debug this:\n");
2188 lockdep_print_held_locks(curr);
2190 printk("\nstack backtrace:\n");
2197 * Print out an error if an invalid bit is set:
2200 valid_state(struct task_struct *curr, struct held_lock *this,
2201 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2203 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2204 return print_usage_bug(curr, this, bad_bit, new_bit);
2208 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2209 enum lock_usage_bit new_bit);
2211 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2214 * print irq inversion bug:
2217 print_irq_inversion_bug(struct task_struct *curr,
2218 struct lock_list *root, struct lock_list *other,
2219 struct held_lock *this, int forwards,
2220 const char *irqclass)
2222 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2225 printk("\n=========================================================\n");
2226 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
2227 print_kernel_version();
2228 printk( "---------------------------------------------------------\n");
2229 printk("%s/%d just changed the state of lock:\n",
2230 curr->comm, task_pid_nr(curr));
2233 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2235 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2236 print_lock_name(other->class);
2237 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2239 printk("\nother info that might help us debug this:\n");
2240 lockdep_print_held_locks(curr);
2242 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2243 if (!save_trace(&root->trace))
2245 print_shortest_lock_dependencies(other, root);
2247 printk("\nstack backtrace:\n");
2254 * Prove that in the forwards-direction subgraph starting at <this>
2255 * there is no lock matching <mask>:
2258 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2259 enum lock_usage_bit bit, const char *irqclass)
2262 struct lock_list root;
2263 struct lock_list *uninitialized_var(target_entry);
2266 root.class = hlock_class(this);
2267 ret = find_usage_forwards(&root, bit, &target_entry);
2269 return print_bfs_bug(ret);
2273 return print_irq_inversion_bug(curr, &root, target_entry,
2278 * Prove that in the backwards-direction subgraph starting at <this>
2279 * there is no lock matching <mask>:
2282 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2283 enum lock_usage_bit bit, const char *irqclass)
2286 struct lock_list root;
2287 struct lock_list *uninitialized_var(target_entry);
2290 root.class = hlock_class(this);
2291 ret = find_usage_backwards(&root, bit, &target_entry);
2293 return print_bfs_bug(ret);
2297 return print_irq_inversion_bug(curr, &root, target_entry,
2301 void print_irqtrace_events(struct task_struct *curr)
2303 printk("irq event stamp: %u\n", curr->irq_events);
2304 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2305 print_ip_sym(curr->hardirq_enable_ip);
2306 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2307 print_ip_sym(curr->hardirq_disable_ip);
2308 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2309 print_ip_sym(curr->softirq_enable_ip);
2310 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2311 print_ip_sym(curr->softirq_disable_ip);
2314 static int HARDIRQ_verbose(struct lock_class *class)
2317 return class_filter(class);
2322 static int SOFTIRQ_verbose(struct lock_class *class)
2325 return class_filter(class);
2330 static int RECLAIM_FS_verbose(struct lock_class *class)
2333 return class_filter(class);
2338 #define STRICT_READ_CHECKS 1
2340 static int (*state_verbose_f[])(struct lock_class *class) = {
2341 #define LOCKDEP_STATE(__STATE) \
2343 #include "lockdep_states.h"
2344 #undef LOCKDEP_STATE
2347 static inline int state_verbose(enum lock_usage_bit bit,
2348 struct lock_class *class)
2350 return state_verbose_f[bit >> 2](class);
2353 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2354 enum lock_usage_bit bit, const char *name);
2357 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2358 enum lock_usage_bit new_bit)
2360 int excl_bit = exclusive_bit(new_bit);
2361 int read = new_bit & 1;
2362 int dir = new_bit & 2;
2365 * mark USED_IN has to look forwards -- to ensure no dependency
2366 * has ENABLED state, which would allow recursion deadlocks.
2368 * mark ENABLED has to look backwards -- to ensure no dependee
2369 * has USED_IN state, which, again, would allow recursion deadlocks.
2371 check_usage_f usage = dir ?
2372 check_usage_backwards : check_usage_forwards;
2375 * Validate that this particular lock does not have conflicting
2378 if (!valid_state(curr, this, new_bit, excl_bit))
2382 * Validate that the lock dependencies don't have conflicting usage
2385 if ((!read || !dir || STRICT_READ_CHECKS) &&
2386 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2390 * Check for read in write conflicts
2393 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2396 if (STRICT_READ_CHECKS &&
2397 !usage(curr, this, excl_bit + 1,
2398 state_name(new_bit + 1)))
2402 if (state_verbose(new_bit, hlock_class(this)))
2409 #define LOCKDEP_STATE(__STATE) __STATE,
2410 #include "lockdep_states.h"
2411 #undef LOCKDEP_STATE
2415 * Mark all held locks with a usage bit:
2418 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2420 enum lock_usage_bit usage_bit;
2421 struct held_lock *hlock;
2424 for (i = 0; i < curr->lockdep_depth; i++) {
2425 hlock = curr->held_locks + i;
2427 usage_bit = 2 + (mark << 2); /* ENABLED */
2429 usage_bit += 1; /* READ */
2431 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2433 if (!mark_lock(curr, hlock, usage_bit))
2441 * Hardirqs will be enabled:
2443 void trace_hardirqs_on_caller(unsigned long ip)
2445 struct task_struct *curr = current;
2447 time_hardirqs_on(CALLER_ADDR0, ip);
2449 if (unlikely(!debug_locks || current->lockdep_recursion))
2452 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2455 if (unlikely(curr->hardirqs_enabled)) {
2457 * Neither irq nor preemption are disabled here
2458 * so this is racy by nature but losing one hit
2459 * in a stat is not a big deal.
2461 __debug_atomic_inc(redundant_hardirqs_on);
2464 /* we'll do an OFF -> ON transition: */
2465 curr->hardirqs_enabled = 1;
2467 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2469 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2472 * We are going to turn hardirqs on, so set the
2473 * usage bit for all held locks:
2475 if (!mark_held_locks(curr, HARDIRQ))
2478 * If we have softirqs enabled, then set the usage
2479 * bit for all held locks. (disabled hardirqs prevented
2480 * this bit from being set before)
2482 if (curr->softirqs_enabled)
2483 if (!mark_held_locks(curr, SOFTIRQ))
2486 curr->hardirq_enable_ip = ip;
2487 curr->hardirq_enable_event = ++curr->irq_events;
2488 debug_atomic_inc(hardirqs_on_events);
2490 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2492 void trace_hardirqs_on(void)
2494 trace_hardirqs_on_caller(CALLER_ADDR0);
2496 EXPORT_SYMBOL(trace_hardirqs_on);
2499 * Hardirqs were disabled:
2501 void trace_hardirqs_off_caller(unsigned long ip)
2503 struct task_struct *curr = current;
2505 time_hardirqs_off(CALLER_ADDR0, ip);
2507 if (unlikely(!debug_locks || current->lockdep_recursion))
2510 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2513 if (curr->hardirqs_enabled) {
2515 * We have done an ON -> OFF transition:
2517 curr->hardirqs_enabled = 0;
2518 curr->hardirq_disable_ip = ip;
2519 curr->hardirq_disable_event = ++curr->irq_events;
2520 debug_atomic_inc(hardirqs_off_events);
2522 debug_atomic_inc(redundant_hardirqs_off);
2524 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2526 void trace_hardirqs_off(void)
2528 trace_hardirqs_off_caller(CALLER_ADDR0);
2530 EXPORT_SYMBOL(trace_hardirqs_off);
2533 * Softirqs will be enabled:
2535 void trace_softirqs_on(unsigned long ip)
2537 struct task_struct *curr = current;
2539 if (unlikely(!debug_locks))
2542 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2545 if (curr->softirqs_enabled) {
2546 debug_atomic_inc(redundant_softirqs_on);
2551 * We'll do an OFF -> ON transition:
2553 curr->softirqs_enabled = 1;
2554 curr->softirq_enable_ip = ip;
2555 curr->softirq_enable_event = ++curr->irq_events;
2556 debug_atomic_inc(softirqs_on_events);
2558 * We are going to turn softirqs on, so set the
2559 * usage bit for all held locks, if hardirqs are
2562 if (curr->hardirqs_enabled)
2563 mark_held_locks(curr, SOFTIRQ);
2567 * Softirqs were disabled:
2569 void trace_softirqs_off(unsigned long ip)
2571 struct task_struct *curr = current;
2573 if (unlikely(!debug_locks))
2576 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2579 if (curr->softirqs_enabled) {
2581 * We have done an ON -> OFF transition:
2583 curr->softirqs_enabled = 0;
2584 curr->softirq_disable_ip = ip;
2585 curr->softirq_disable_event = ++curr->irq_events;
2586 debug_atomic_inc(softirqs_off_events);
2587 DEBUG_LOCKS_WARN_ON(!softirq_count());
2589 debug_atomic_inc(redundant_softirqs_off);
2592 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2594 struct task_struct *curr = current;
2596 if (unlikely(!debug_locks))
2599 /* no reclaim without waiting on it */
2600 if (!(gfp_mask & __GFP_WAIT))
2603 /* this guy won't enter reclaim */
2604 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2607 /* We're only interested __GFP_FS allocations for now */
2608 if (!(gfp_mask & __GFP_FS))
2611 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2614 mark_held_locks(curr, RECLAIM_FS);
2617 static void check_flags(unsigned long flags);
2619 void lockdep_trace_alloc(gfp_t gfp_mask)
2621 unsigned long flags;
2623 if (unlikely(current->lockdep_recursion))
2626 raw_local_irq_save(flags);
2628 current->lockdep_recursion = 1;
2629 __lockdep_trace_alloc(gfp_mask, flags);
2630 current->lockdep_recursion = 0;
2631 raw_local_irq_restore(flags);
2634 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2637 * If non-trylock use in a hardirq or softirq context, then
2638 * mark the lock as used in these contexts:
2640 if (!hlock->trylock) {
2642 if (curr->hardirq_context)
2643 if (!mark_lock(curr, hlock,
2644 LOCK_USED_IN_HARDIRQ_READ))
2646 if (curr->softirq_context)
2647 if (!mark_lock(curr, hlock,
2648 LOCK_USED_IN_SOFTIRQ_READ))
2651 if (curr->hardirq_context)
2652 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2654 if (curr->softirq_context)
2655 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2659 if (!hlock->hardirqs_off) {
2661 if (!mark_lock(curr, hlock,
2662 LOCK_ENABLED_HARDIRQ_READ))
2664 if (curr->softirqs_enabled)
2665 if (!mark_lock(curr, hlock,
2666 LOCK_ENABLED_SOFTIRQ_READ))
2669 if (!mark_lock(curr, hlock,
2670 LOCK_ENABLED_HARDIRQ))
2672 if (curr->softirqs_enabled)
2673 if (!mark_lock(curr, hlock,
2674 LOCK_ENABLED_SOFTIRQ))
2680 * We reuse the irq context infrastructure more broadly as a general
2681 * context checking code. This tests GFP_FS recursion (a lock taken
2682 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2685 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2687 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2690 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2698 static int separate_irq_context(struct task_struct *curr,
2699 struct held_lock *hlock)
2701 unsigned int depth = curr->lockdep_depth;
2704 * Keep track of points where we cross into an interrupt context:
2706 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2707 curr->softirq_context;
2709 struct held_lock *prev_hlock;
2711 prev_hlock = curr->held_locks + depth-1;
2713 * If we cross into another context, reset the
2714 * hash key (this also prevents the checking and the
2715 * adding of the dependency to 'prev'):
2717 if (prev_hlock->irq_context != hlock->irq_context)
2726 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2727 enum lock_usage_bit new_bit)
2733 static inline int mark_irqflags(struct task_struct *curr,
2734 struct held_lock *hlock)
2739 static inline int separate_irq_context(struct task_struct *curr,
2740 struct held_lock *hlock)
2745 void lockdep_trace_alloc(gfp_t gfp_mask)
2752 * Mark a lock with a usage bit, and validate the state transition:
2754 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2755 enum lock_usage_bit new_bit)
2757 unsigned int new_mask = 1 << new_bit, ret = 1;
2760 * If already set then do not dirty the cacheline,
2761 * nor do any checks:
2763 if (likely(hlock_class(this)->usage_mask & new_mask))
2769 * Make sure we didn't race:
2771 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2776 hlock_class(this)->usage_mask |= new_mask;
2778 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2782 #define LOCKDEP_STATE(__STATE) \
2783 case LOCK_USED_IN_##__STATE: \
2784 case LOCK_USED_IN_##__STATE##_READ: \
2785 case LOCK_ENABLED_##__STATE: \
2786 case LOCK_ENABLED_##__STATE##_READ:
2787 #include "lockdep_states.h"
2788 #undef LOCKDEP_STATE
2789 ret = mark_lock_irq(curr, this, new_bit);
2794 debug_atomic_dec(nr_unused_locks);
2797 if (!debug_locks_off_graph_unlock())
2806 * We must printk outside of the graph_lock:
2809 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2811 print_irqtrace_events(curr);
2819 * Initialize a lock instance's lock-class mapping info:
2821 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2822 struct lock_class_key *key, int subclass)
2826 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2827 lock->class_cache[i] = NULL;
2829 #ifdef CONFIG_LOCK_STAT
2830 lock->cpu = raw_smp_processor_id();
2833 if (DEBUG_LOCKS_WARN_ON(!name)) {
2834 lock->name = "NULL";
2840 if (DEBUG_LOCKS_WARN_ON(!key))
2843 * Sanity check, the lock-class key must be persistent:
2845 if (!static_obj(key)) {
2846 printk("BUG: key %p not in .data!\n", key);
2847 DEBUG_LOCKS_WARN_ON(1);
2852 if (unlikely(!debug_locks))
2856 register_lock_class(lock, subclass, 1);
2858 EXPORT_SYMBOL_GPL(lockdep_init_map);
2860 struct lock_class_key __lockdep_no_validate__;
2863 * This gets called for every mutex_lock*()/spin_lock*() operation.
2864 * We maintain the dependency maps and validate the locking attempt:
2866 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2867 int trylock, int read, int check, int hardirqs_off,
2868 struct lockdep_map *nest_lock, unsigned long ip,
2871 struct task_struct *curr = current;
2872 struct lock_class *class = NULL;
2873 struct held_lock *hlock;
2874 unsigned int depth, id;
2882 if (unlikely(!debug_locks))
2885 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2888 if (lock->key == &__lockdep_no_validate__)
2891 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
2892 class = lock->class_cache[subclass];
2896 if (unlikely(!class)) {
2897 class = register_lock_class(lock, subclass, 0);
2901 atomic_inc((atomic_t *)&class->ops);
2902 if (very_verbose(class)) {
2903 printk("\nacquire class [%p] %s", class->key, class->name);
2904 if (class->name_version > 1)
2905 printk("#%d", class->name_version);
2911 * Add the lock to the list of currently held locks.
2912 * (we dont increase the depth just yet, up until the
2913 * dependency checks are done)
2915 depth = curr->lockdep_depth;
2916 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2919 class_idx = class - lock_classes + 1;
2922 hlock = curr->held_locks + depth - 1;
2923 if (hlock->class_idx == class_idx && nest_lock) {
2924 if (hlock->references)
2925 hlock->references++;
2927 hlock->references = 2;
2933 hlock = curr->held_locks + depth;
2934 if (DEBUG_LOCKS_WARN_ON(!class))
2936 hlock->class_idx = class_idx;
2937 hlock->acquire_ip = ip;
2938 hlock->instance = lock;
2939 hlock->nest_lock = nest_lock;
2940 hlock->trylock = trylock;
2942 hlock->check = check;
2943 hlock->hardirqs_off = !!hardirqs_off;
2944 hlock->references = references;
2945 #ifdef CONFIG_LOCK_STAT
2946 hlock->waittime_stamp = 0;
2947 hlock->holdtime_stamp = lockstat_clock();
2950 if (check == 2 && !mark_irqflags(curr, hlock))
2953 /* mark it as used: */
2954 if (!mark_lock(curr, hlock, LOCK_USED))
2958 * Calculate the chain hash: it's the combined hash of all the
2959 * lock keys along the dependency chain. We save the hash value
2960 * at every step so that we can get the current hash easily
2961 * after unlock. The chain hash is then used to cache dependency
2964 * The 'key ID' is what is the most compact key value to drive
2965 * the hash, not class->key.
2967 id = class - lock_classes;
2968 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2971 chain_key = curr->curr_chain_key;
2973 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2978 hlock->prev_chain_key = chain_key;
2979 if (separate_irq_context(curr, hlock)) {
2983 chain_key = iterate_chain_key(chain_key, id);
2985 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2988 curr->curr_chain_key = chain_key;
2989 curr->lockdep_depth++;
2990 check_chain_key(curr);
2991 #ifdef CONFIG_DEBUG_LOCKDEP
2992 if (unlikely(!debug_locks))
2995 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2997 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2998 printk("turning off the locking correctness validator.\n");
3003 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3004 max_lockdep_depth = curr->lockdep_depth;
3010 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3013 if (!debug_locks_off())
3015 if (debug_locks_silent)
3018 printk("\n=====================================\n");
3019 printk( "[ BUG: bad unlock balance detected! ]\n");
3020 printk( "-------------------------------------\n");
3021 printk("%s/%d is trying to release lock (",
3022 curr->comm, task_pid_nr(curr));
3023 print_lockdep_cache(lock);
3026 printk("but there are no more locks to release!\n");
3027 printk("\nother info that might help us debug this:\n");
3028 lockdep_print_held_locks(curr);
3030 printk("\nstack backtrace:\n");
3037 * Common debugging checks for both nested and non-nested unlock:
3039 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3042 if (unlikely(!debug_locks))
3044 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3047 if (curr->lockdep_depth <= 0)
3048 return print_unlock_inbalance_bug(curr, lock, ip);
3053 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3055 if (hlock->instance == lock)
3058 if (hlock->references) {
3059 struct lock_class *class = lock->class_cache[0];
3062 class = look_up_lock_class(lock, 0);
3064 if (DEBUG_LOCKS_WARN_ON(!class))
3067 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3070 if (hlock->class_idx == class - lock_classes + 1)
3078 __lock_set_class(struct lockdep_map *lock, const char *name,
3079 struct lock_class_key *key, unsigned int subclass,
3082 struct task_struct *curr = current;
3083 struct held_lock *hlock, *prev_hlock;
3084 struct lock_class *class;
3088 depth = curr->lockdep_depth;
3089 if (DEBUG_LOCKS_WARN_ON(!depth))
3093 for (i = depth-1; i >= 0; i--) {
3094 hlock = curr->held_locks + i;
3096 * We must not cross into another context:
3098 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3100 if (match_held_lock(hlock, lock))
3104 return print_unlock_inbalance_bug(curr, lock, ip);
3107 lockdep_init_map(lock, name, key, 0);
3108 class = register_lock_class(lock, subclass, 0);
3109 hlock->class_idx = class - lock_classes + 1;
3111 curr->lockdep_depth = i;
3112 curr->curr_chain_key = hlock->prev_chain_key;
3114 for (; 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))
3130 * Remove the lock to the list of currently held locks in a
3131 * potentially non-nested (out of order) manner. This is a
3132 * relatively rare operation, as all the unlock APIs default
3133 * to nested mode (which uses lock_release()):
3136 lock_release_non_nested(struct task_struct *curr,
3137 struct lockdep_map *lock, unsigned long ip)
3139 struct held_lock *hlock, *prev_hlock;
3144 * Check whether the lock exists in the current stack
3147 depth = curr->lockdep_depth;
3148 if (DEBUG_LOCKS_WARN_ON(!depth))
3152 for (i = depth-1; i >= 0; i--) {
3153 hlock = curr->held_locks + i;
3155 * We must not cross into another context:
3157 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3159 if (match_held_lock(hlock, lock))
3163 return print_unlock_inbalance_bug(curr, lock, ip);
3166 if (hlock->instance == lock)
3167 lock_release_holdtime(hlock);
3169 if (hlock->references) {
3170 hlock->references--;
3171 if (hlock->references) {
3173 * We had, and after removing one, still have
3174 * references, the current lock stack is still
3175 * valid. We're done!
3182 * We have the right lock to unlock, 'hlock' points to it.
3183 * Now we remove it from the stack, and add back the other
3184 * entries (if any), recalculating the hash along the way:
3187 curr->lockdep_depth = i;
3188 curr->curr_chain_key = hlock->prev_chain_key;
3190 for (i++; i < depth; i++) {
3191 hlock = curr->held_locks + i;
3192 if (!__lock_acquire(hlock->instance,
3193 hlock_class(hlock)->subclass, hlock->trylock,
3194 hlock->read, hlock->check, hlock->hardirqs_off,
3195 hlock->nest_lock, hlock->acquire_ip,
3200 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3206 * Remove the lock to the list of currently held locks - this gets
3207 * called on mutex_unlock()/spin_unlock*() (or on a failed
3208 * mutex_lock_interruptible()). This is done for unlocks that nest
3209 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3211 static int lock_release_nested(struct task_struct *curr,
3212 struct lockdep_map *lock, unsigned long ip)
3214 struct held_lock *hlock;
3218 * Pop off the top of the lock stack:
3220 depth = curr->lockdep_depth - 1;
3221 hlock = curr->held_locks + depth;
3224 * Is the unlock non-nested:
3226 if (hlock->instance != lock || hlock->references)
3227 return lock_release_non_nested(curr, lock, ip);
3228 curr->lockdep_depth--;
3230 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3233 curr->curr_chain_key = hlock->prev_chain_key;
3235 lock_release_holdtime(hlock);
3237 #ifdef CONFIG_DEBUG_LOCKDEP
3238 hlock->prev_chain_key = 0;
3239 hlock->class_idx = 0;
3240 hlock->acquire_ip = 0;
3241 hlock->irq_context = 0;
3247 * Remove the lock to the list of currently held locks - this gets
3248 * called on mutex_unlock()/spin_unlock*() (or on a failed
3249 * mutex_lock_interruptible()). This is done for unlocks that nest
3250 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3253 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3255 struct task_struct *curr = current;
3257 if (!check_unlock(curr, lock, ip))
3261 if (!lock_release_nested(curr, lock, ip))
3264 if (!lock_release_non_nested(curr, lock, ip))
3268 check_chain_key(curr);
3271 static int __lock_is_held(struct lockdep_map *lock)
3273 struct task_struct *curr = current;
3276 for (i = 0; i < curr->lockdep_depth; i++) {
3277 struct held_lock *hlock = curr->held_locks + i;
3279 if (match_held_lock(hlock, lock))
3287 * Check whether we follow the irq-flags state precisely:
3289 static void check_flags(unsigned long flags)
3291 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3292 defined(CONFIG_TRACE_IRQFLAGS)
3296 if (irqs_disabled_flags(flags)) {
3297 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3298 printk("possible reason: unannotated irqs-off.\n");
3301 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3302 printk("possible reason: unannotated irqs-on.\n");
3307 * We dont accurately track softirq state in e.g.
3308 * hardirq contexts (such as on 4KSTACKS), so only
3309 * check if not in hardirq contexts:
3311 if (!hardirq_count()) {
3312 if (softirq_count())
3313 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3315 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3319 print_irqtrace_events(current);
3323 void lock_set_class(struct lockdep_map *lock, const char *name,
3324 struct lock_class_key *key, unsigned int subclass,
3327 unsigned long flags;
3329 if (unlikely(current->lockdep_recursion))
3332 raw_local_irq_save(flags);
3333 current->lockdep_recursion = 1;
3335 if (__lock_set_class(lock, name, key, subclass, ip))
3336 check_chain_key(current);
3337 current->lockdep_recursion = 0;
3338 raw_local_irq_restore(flags);
3340 EXPORT_SYMBOL_GPL(lock_set_class);
3343 * We are not always called with irqs disabled - do that here,
3344 * and also avoid lockdep recursion:
3346 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3347 int trylock, int read, int check,
3348 struct lockdep_map *nest_lock, unsigned long ip)
3350 unsigned long flags;
3352 if (unlikely(current->lockdep_recursion))
3355 raw_local_irq_save(flags);
3358 current->lockdep_recursion = 1;
3359 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3360 __lock_acquire(lock, subclass, trylock, read, check,
3361 irqs_disabled_flags(flags), nest_lock, ip, 0);
3362 current->lockdep_recursion = 0;
3363 raw_local_irq_restore(flags);
3365 EXPORT_SYMBOL_GPL(lock_acquire);
3367 void lock_release(struct lockdep_map *lock, int nested,
3370 unsigned long flags;
3372 if (unlikely(current->lockdep_recursion))
3375 raw_local_irq_save(flags);
3377 current->lockdep_recursion = 1;
3378 trace_lock_release(lock, ip);
3379 __lock_release(lock, nested, ip);
3380 current->lockdep_recursion = 0;
3381 raw_local_irq_restore(flags);
3383 EXPORT_SYMBOL_GPL(lock_release);
3385 int lock_is_held(struct lockdep_map *lock)
3387 unsigned long flags;
3390 if (unlikely(current->lockdep_recursion))
3393 raw_local_irq_save(flags);
3396 current->lockdep_recursion = 1;
3397 ret = __lock_is_held(lock);
3398 current->lockdep_recursion = 0;
3399 raw_local_irq_restore(flags);
3403 EXPORT_SYMBOL_GPL(lock_is_held);
3405 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3407 current->lockdep_reclaim_gfp = gfp_mask;
3410 void lockdep_clear_current_reclaim_state(void)
3412 current->lockdep_reclaim_gfp = 0;
3415 #ifdef CONFIG_LOCK_STAT
3417 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3420 if (!debug_locks_off())
3422 if (debug_locks_silent)
3425 printk("\n=================================\n");
3426 printk( "[ BUG: bad contention detected! ]\n");
3427 printk( "---------------------------------\n");
3428 printk("%s/%d is trying to contend lock (",
3429 curr->comm, task_pid_nr(curr));
3430 print_lockdep_cache(lock);
3433 printk("but there are no locks held!\n");
3434 printk("\nother info that might help us debug this:\n");
3435 lockdep_print_held_locks(curr);
3437 printk("\nstack backtrace:\n");
3444 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3446 struct task_struct *curr = current;
3447 struct held_lock *hlock, *prev_hlock;
3448 struct lock_class_stats *stats;
3450 int i, contention_point, contending_point;
3452 depth = curr->lockdep_depth;
3453 if (DEBUG_LOCKS_WARN_ON(!depth))
3457 for (i = depth-1; i >= 0; i--) {
3458 hlock = curr->held_locks + i;
3460 * We must not cross into another context:
3462 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3464 if (match_held_lock(hlock, lock))
3468 print_lock_contention_bug(curr, lock, ip);
3472 if (hlock->instance != lock)
3475 hlock->waittime_stamp = lockstat_clock();
3477 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3478 contending_point = lock_point(hlock_class(hlock)->contending_point,
3481 stats = get_lock_stats(hlock_class(hlock));
3482 if (contention_point < LOCKSTAT_POINTS)
3483 stats->contention_point[contention_point]++;
3484 if (contending_point < LOCKSTAT_POINTS)
3485 stats->contending_point[contending_point]++;
3486 if (lock->cpu != smp_processor_id())
3487 stats->bounces[bounce_contended + !!hlock->read]++;
3488 put_lock_stats(stats);
3492 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3494 struct task_struct *curr = current;
3495 struct held_lock *hlock, *prev_hlock;
3496 struct lock_class_stats *stats;
3498 u64 now, waittime = 0;
3501 depth = curr->lockdep_depth;
3502 if (DEBUG_LOCKS_WARN_ON(!depth))
3506 for (i = depth-1; i >= 0; i--) {
3507 hlock = curr->held_locks + i;
3509 * We must not cross into another context:
3511 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3513 if (match_held_lock(hlock, lock))
3517 print_lock_contention_bug(curr, lock, _RET_IP_);
3521 if (hlock->instance != lock)
3524 cpu = smp_processor_id();
3525 if (hlock->waittime_stamp) {
3526 now = lockstat_clock();
3527 waittime = now - hlock->waittime_stamp;
3528 hlock->holdtime_stamp = now;
3531 trace_lock_acquired(lock, ip);
3533 stats = get_lock_stats(hlock_class(hlock));
3536 lock_time_inc(&stats->read_waittime, waittime);
3538 lock_time_inc(&stats->write_waittime, waittime);
3540 if (lock->cpu != cpu)
3541 stats->bounces[bounce_acquired + !!hlock->read]++;
3542 put_lock_stats(stats);
3548 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3550 unsigned long flags;
3552 if (unlikely(!lock_stat))
3555 if (unlikely(current->lockdep_recursion))
3558 raw_local_irq_save(flags);
3560 current->lockdep_recursion = 1;
3561 trace_lock_contended(lock, ip);
3562 __lock_contended(lock, ip);
3563 current->lockdep_recursion = 0;
3564 raw_local_irq_restore(flags);
3566 EXPORT_SYMBOL_GPL(lock_contended);
3568 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3570 unsigned long flags;
3572 if (unlikely(!lock_stat))
3575 if (unlikely(current->lockdep_recursion))
3578 raw_local_irq_save(flags);
3580 current->lockdep_recursion = 1;
3581 __lock_acquired(lock, ip);
3582 current->lockdep_recursion = 0;
3583 raw_local_irq_restore(flags);
3585 EXPORT_SYMBOL_GPL(lock_acquired);
3589 * Used by the testsuite, sanitize the validator state
3590 * after a simulated failure:
3593 void lockdep_reset(void)
3595 unsigned long flags;
3598 raw_local_irq_save(flags);
3599 current->curr_chain_key = 0;
3600 current->lockdep_depth = 0;
3601 current->lockdep_recursion = 0;
3602 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3603 nr_hardirq_chains = 0;
3604 nr_softirq_chains = 0;
3605 nr_process_chains = 0;
3607 for (i = 0; i < CHAINHASH_SIZE; i++)
3608 INIT_LIST_HEAD(chainhash_table + i);
3609 raw_local_irq_restore(flags);
3612 static void zap_class(struct lock_class *class)
3617 * Remove all dependencies this lock is
3620 for (i = 0; i < nr_list_entries; i++) {
3621 if (list_entries[i].class == class)
3622 list_del_rcu(&list_entries[i].entry);
3625 * Unhash the class and remove it from the all_lock_classes list:
3627 list_del_rcu(&class->hash_entry);
3628 list_del_rcu(&class->lock_entry);
3633 static inline int within(const void *addr, void *start, unsigned long size)
3635 return addr >= start && addr < start + size;
3638 void lockdep_free_key_range(void *start, unsigned long size)
3640 struct lock_class *class, *next;
3641 struct list_head *head;
3642 unsigned long flags;
3646 raw_local_irq_save(flags);
3647 locked = graph_lock();
3650 * Unhash all classes that were created by this module:
3652 for (i = 0; i < CLASSHASH_SIZE; i++) {
3653 head = classhash_table + i;
3654 if (list_empty(head))
3656 list_for_each_entry_safe(class, next, head, hash_entry) {
3657 if (within(class->key, start, size))
3659 else if (within(class->name, start, size))
3666 raw_local_irq_restore(flags);
3669 void lockdep_reset_lock(struct lockdep_map *lock)
3671 struct lock_class *class, *next;
3672 struct list_head *head;
3673 unsigned long flags;
3677 raw_local_irq_save(flags);
3680 * Remove all classes this lock might have:
3682 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3684 * If the class exists we look it up and zap it:
3686 class = look_up_lock_class(lock, j);
3691 * Debug check: in the end all mapped classes should
3694 locked = graph_lock();
3695 for (i = 0; i < CLASSHASH_SIZE; i++) {
3696 head = classhash_table + i;
3697 if (list_empty(head))
3699 list_for_each_entry_safe(class, next, head, hash_entry) {
3702 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3703 match |= class == lock->class_cache[j];
3705 if (unlikely(match)) {
3706 if (debug_locks_off_graph_unlock())
3716 raw_local_irq_restore(flags);
3719 void lockdep_init(void)
3724 * Some architectures have their own start_kernel()
3725 * code which calls lockdep_init(), while we also
3726 * call lockdep_init() from the start_kernel() itself,
3727 * and we want to initialize the hashes only once:
3729 if (lockdep_initialized)
3732 for (i = 0; i < CLASSHASH_SIZE; i++)
3733 INIT_LIST_HEAD(classhash_table + i);
3735 for (i = 0; i < CHAINHASH_SIZE; i++)
3736 INIT_LIST_HEAD(chainhash_table + i);
3738 lockdep_initialized = 1;
3741 void __init lockdep_info(void)
3743 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3745 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3746 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3747 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3748 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3749 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3750 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3751 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3753 printk(" memory used by lock dependency info: %lu kB\n",
3754 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3755 sizeof(struct list_head) * CLASSHASH_SIZE +
3756 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3757 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3758 sizeof(struct list_head) * CHAINHASH_SIZE
3759 #ifdef CONFIG_PROVE_LOCKING
3760 + sizeof(struct circular_queue)
3765 printk(" per task-struct memory footprint: %lu bytes\n",
3766 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3768 #ifdef CONFIG_DEBUG_LOCKDEP
3769 if (lockdep_init_error) {
3770 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3771 printk("Call stack leading to lockdep invocation was:\n");
3772 print_stack_trace(&lockdep_init_trace, 0);
3778 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3779 const void *mem_to, struct held_lock *hlock)
3781 if (!debug_locks_off())
3783 if (debug_locks_silent)
3786 printk("\n=========================\n");
3787 printk( "[ BUG: held lock freed! ]\n");
3788 printk( "-------------------------\n");
3789 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3790 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3792 lockdep_print_held_locks(curr);
3794 printk("\nstack backtrace:\n");
3798 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3799 const void* lock_from, unsigned long lock_len)
3801 return lock_from + lock_len <= mem_from ||
3802 mem_from + mem_len <= lock_from;
3806 * Called when kernel memory is freed (or unmapped), or if a lock
3807 * is destroyed or reinitialized - this code checks whether there is
3808 * any held lock in the memory range of <from> to <to>:
3810 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3812 struct task_struct *curr = current;
3813 struct held_lock *hlock;
3814 unsigned long flags;
3817 if (unlikely(!debug_locks))
3820 local_irq_save(flags);
3821 for (i = 0; i < curr->lockdep_depth; i++) {
3822 hlock = curr->held_locks + i;
3824 if (not_in_range(mem_from, mem_len, hlock->instance,
3825 sizeof(*hlock->instance)))
3828 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3831 local_irq_restore(flags);
3833 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3835 static void print_held_locks_bug(struct task_struct *curr)
3837 if (!debug_locks_off())
3839 if (debug_locks_silent)
3842 printk("\n=====================================\n");
3843 printk( "[ BUG: lock held at task exit time! ]\n");
3844 printk( "-------------------------------------\n");
3845 printk("%s/%d is exiting with locks still held!\n",
3846 curr->comm, task_pid_nr(curr));
3847 lockdep_print_held_locks(curr);
3849 printk("\nstack backtrace:\n");
3853 void debug_check_no_locks_held(struct task_struct *task)
3855 if (unlikely(task->lockdep_depth > 0))
3856 print_held_locks_bug(task);
3859 void debug_show_all_locks(void)
3861 struct task_struct *g, *p;
3865 if (unlikely(!debug_locks)) {
3866 printk("INFO: lockdep is turned off.\n");
3869 printk("\nShowing all locks held in the system:\n");
3872 * Here we try to get the tasklist_lock as hard as possible,
3873 * if not successful after 2 seconds we ignore it (but keep
3874 * trying). This is to enable a debug printout even if a
3875 * tasklist_lock-holding task deadlocks or crashes.
3878 if (!read_trylock(&tasklist_lock)) {
3880 printk("hm, tasklist_lock locked, retrying... ");
3883 printk(" #%d", 10-count);
3887 printk(" ignoring it.\n");
3891 printk(KERN_CONT " locked it.\n");
3894 do_each_thread(g, p) {
3896 * It's not reliable to print a task's held locks
3897 * if it's not sleeping (or if it's not the current
3900 if (p->state == TASK_RUNNING && p != current)
3902 if (p->lockdep_depth)
3903 lockdep_print_held_locks(p);
3905 if (read_trylock(&tasklist_lock))
3907 } while_each_thread(g, p);
3910 printk("=============================================\n\n");
3913 read_unlock(&tasklist_lock);
3915 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3918 * Careful: only use this function if you are sure that
3919 * the task cannot run in parallel!
3921 void debug_show_held_locks(struct task_struct *task)
3923 if (unlikely(!debug_locks)) {
3924 printk("INFO: lockdep is turned off.\n");
3927 lockdep_print_held_locks(task);
3929 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3931 void lockdep_sys_exit(void)
3933 struct task_struct *curr = current;
3935 if (unlikely(curr->lockdep_depth)) {
3936 if (!debug_locks_off())
3938 printk("\n================================================\n");
3939 printk( "[ BUG: lock held when returning to user space! ]\n");
3940 printk( "------------------------------------------------\n");
3941 printk("%s/%d is leaving the kernel with locks still held!\n",
3942 curr->comm, curr->pid);
3943 lockdep_print_held_locks(curr);
3947 void lockdep_rcu_dereference(const char *file, const int line)
3949 struct task_struct *curr = current;
3951 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
3952 if (!debug_locks_off())
3954 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
3955 /* Note: the following can be executed concurrently, so be careful. */
3956 printk("\n===================================================\n");
3957 printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3958 printk( "---------------------------------------------------\n");
3959 printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3961 printk("\nother info that might help us debug this:\n\n");
3962 printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
3963 lockdep_print_held_locks(curr);
3964 printk("\nstack backtrace:\n");
3967 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);