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)
1133 printk("======================================================\n");
1134 printk("[ INFO: possible circular locking dependency detected ]\n");
1135 print_kernel_version();
1136 printk("-------------------------------------------------------\n");
1137 printk("%s/%d is trying to acquire lock:\n",
1138 curr->comm, task_pid_nr(curr));
1139 print_lock(check_src);
1140 printk("\nbut task is already holding lock:\n");
1141 print_lock(check_tgt);
1142 printk("\nwhich lock already depends on the new lock.\n\n");
1143 printk("\nthe existing dependency chain (in reverse order) is:\n");
1145 print_circular_bug_entry(entry, depth);
1150 static inline int class_equal(struct lock_list *entry, void *data)
1152 return entry->class == data;
1155 static noinline int print_circular_bug(struct lock_list *this,
1156 struct lock_list *target,
1157 struct held_lock *check_src,
1158 struct held_lock *check_tgt)
1160 struct task_struct *curr = current;
1161 struct lock_list *parent;
1162 struct lock_list *first_parent;
1165 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1168 if (!save_trace(&this->trace))
1171 depth = get_lock_depth(target);
1173 print_circular_bug_header(target, depth, check_src, check_tgt);
1175 parent = get_lock_parent(target);
1176 first_parent = parent;
1179 print_circular_bug_entry(parent, --depth);
1180 parent = get_lock_parent(parent);
1183 printk("\nother info that might help us debug this:\n\n");
1184 print_circular_lock_scenario(check_src, check_tgt,
1187 lockdep_print_held_locks(curr);
1189 printk("\nstack backtrace:\n");
1195 static noinline int print_bfs_bug(int ret)
1197 if (!debug_locks_off_graph_unlock())
1200 WARN(1, "lockdep bfs error:%d\n", ret);
1205 static int noop_count(struct lock_list *entry, void *data)
1207 (*(unsigned long *)data)++;
1211 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1213 unsigned long count = 0;
1214 struct lock_list *uninitialized_var(target_entry);
1216 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1220 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1222 unsigned long ret, flags;
1223 struct lock_list this;
1228 local_irq_save(flags);
1229 arch_spin_lock(&lockdep_lock);
1230 ret = __lockdep_count_forward_deps(&this);
1231 arch_spin_unlock(&lockdep_lock);
1232 local_irq_restore(flags);
1237 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1239 unsigned long count = 0;
1240 struct lock_list *uninitialized_var(target_entry);
1242 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1247 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1249 unsigned long ret, flags;
1250 struct lock_list this;
1255 local_irq_save(flags);
1256 arch_spin_lock(&lockdep_lock);
1257 ret = __lockdep_count_backward_deps(&this);
1258 arch_spin_unlock(&lockdep_lock);
1259 local_irq_restore(flags);
1265 * Prove that the dependency graph starting at <entry> can not
1266 * lead to <target>. Print an error and return 0 if it does.
1269 check_noncircular(struct lock_list *root, struct lock_class *target,
1270 struct lock_list **target_entry)
1274 debug_atomic_inc(nr_cyclic_checks);
1276 result = __bfs_forwards(root, target, class_equal, target_entry);
1281 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1283 * Forwards and backwards subgraph searching, for the purposes of
1284 * proving that two subgraphs can be connected by a new dependency
1285 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1288 static inline int usage_match(struct lock_list *entry, void *bit)
1290 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1296 * Find a node in the forwards-direction dependency sub-graph starting
1297 * at @root->class that matches @bit.
1299 * Return 0 if such a node exists in the subgraph, and put that node
1300 * into *@target_entry.
1302 * Return 1 otherwise and keep *@target_entry unchanged.
1303 * Return <0 on error.
1306 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1307 struct lock_list **target_entry)
1311 debug_atomic_inc(nr_find_usage_forwards_checks);
1313 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1319 * Find a node in the backwards-direction dependency sub-graph starting
1320 * at @root->class that matches @bit.
1322 * Return 0 if such a node exists in the subgraph, and put that node
1323 * into *@target_entry.
1325 * Return 1 otherwise and keep *@target_entry unchanged.
1326 * Return <0 on error.
1329 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1330 struct lock_list **target_entry)
1334 debug_atomic_inc(nr_find_usage_backwards_checks);
1336 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1341 static void print_lock_class_header(struct lock_class *class, int depth)
1345 printk("%*s->", depth, "");
1346 print_lock_name(class);
1347 printk(" ops: %lu", class->ops);
1350 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1351 if (class->usage_mask & (1 << bit)) {
1354 len += printk("%*s %s", depth, "", usage_str[bit]);
1355 len += printk(" at:\n");
1356 print_stack_trace(class->usage_traces + bit, len);
1359 printk("%*s }\n", depth, "");
1361 printk("%*s ... key at: ",depth,"");
1362 print_ip_sym((unsigned long)class->key);
1366 * printk the shortest lock dependencies from @start to @end in reverse order:
1369 print_shortest_lock_dependencies(struct lock_list *leaf,
1370 struct lock_list *root)
1372 struct lock_list *entry = leaf;
1375 /*compute depth from generated tree by BFS*/
1376 depth = get_lock_depth(leaf);
1379 print_lock_class_header(entry->class, depth);
1380 printk("%*s ... acquired at:\n", depth, "");
1381 print_stack_trace(&entry->trace, 2);
1384 if (depth == 0 && (entry != root)) {
1385 printk("lockdep:%s bad path found in chain graph\n", __func__);
1389 entry = get_lock_parent(entry);
1391 } while (entry && (depth >= 0));
1397 print_irq_lock_scenario(struct lock_list *safe_entry,
1398 struct lock_list *unsafe_entry,
1399 struct lock_class *prev_class,
1400 struct lock_class *next_class)
1402 struct lock_class *safe_class = safe_entry->class;
1403 struct lock_class *unsafe_class = unsafe_entry->class;
1404 struct lock_class *middle_class = prev_class;
1406 if (middle_class == safe_class)
1407 middle_class = next_class;
1410 * A direct locking problem where unsafe_class lock is taken
1411 * directly by safe_class lock, then all we need to show
1412 * is the deadlock scenario, as it is obvious that the
1413 * unsafe lock is taken under the safe lock.
1415 * But if there is a chain instead, where the safe lock takes
1416 * an intermediate lock (middle_class) where this lock is
1417 * not the same as the safe lock, then the lock chain is
1418 * used to describe the problem. Otherwise we would need
1419 * to show a different CPU case for each link in the chain
1420 * from the safe_class lock to the unsafe_class lock.
1422 if (middle_class != unsafe_class) {
1423 printk("Chain exists of:\n ");
1424 __print_lock_name(safe_class);
1426 __print_lock_name(middle_class);
1428 __print_lock_name(unsafe_class);
1432 printk(" Possible interrupt unsafe locking scenario:\n\n");
1433 printk(" CPU0 CPU1\n");
1434 printk(" ---- ----\n");
1436 __print_lock_name(unsafe_class);
1438 printk(" local_irq_disable();\n");
1440 __print_lock_name(safe_class);
1443 __print_lock_name(middle_class);
1445 printk(" <Interrupt>\n");
1447 __print_lock_name(safe_class);
1449 printk("\n *** DEADLOCK ***\n\n");
1453 print_bad_irq_dependency(struct task_struct *curr,
1454 struct lock_list *prev_root,
1455 struct lock_list *next_root,
1456 struct lock_list *backwards_entry,
1457 struct lock_list *forwards_entry,
1458 struct held_lock *prev,
1459 struct held_lock *next,
1460 enum lock_usage_bit bit1,
1461 enum lock_usage_bit bit2,
1462 const char *irqclass)
1464 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1468 printk("======================================================\n");
1469 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1470 irqclass, irqclass);
1471 print_kernel_version();
1472 printk("------------------------------------------------------\n");
1473 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1474 curr->comm, task_pid_nr(curr),
1475 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1476 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1477 curr->hardirqs_enabled,
1478 curr->softirqs_enabled);
1481 printk("\nand this task is already holding:\n");
1483 printk("which would create a new lock dependency:\n");
1484 print_lock_name(hlock_class(prev));
1486 print_lock_name(hlock_class(next));
1489 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1491 print_lock_name(backwards_entry->class);
1492 printk("\n... which became %s-irq-safe at:\n", irqclass);
1494 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1496 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1497 print_lock_name(forwards_entry->class);
1498 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1501 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1503 printk("\nother info that might help us debug this:\n\n");
1504 print_irq_lock_scenario(backwards_entry, forwards_entry,
1505 hlock_class(prev), hlock_class(next));
1507 lockdep_print_held_locks(curr);
1509 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1510 printk(" and the holding lock:\n");
1511 if (!save_trace(&prev_root->trace))
1513 print_shortest_lock_dependencies(backwards_entry, prev_root);
1515 printk("\nthe dependencies between the lock to be acquired");
1516 printk(" and %s-irq-unsafe lock:\n", irqclass);
1517 if (!save_trace(&next_root->trace))
1519 print_shortest_lock_dependencies(forwards_entry, next_root);
1521 printk("\nstack backtrace:\n");
1528 check_usage(struct task_struct *curr, struct held_lock *prev,
1529 struct held_lock *next, enum lock_usage_bit bit_backwards,
1530 enum lock_usage_bit bit_forwards, const char *irqclass)
1533 struct lock_list this, that;
1534 struct lock_list *uninitialized_var(target_entry);
1535 struct lock_list *uninitialized_var(target_entry1);
1539 this.class = hlock_class(prev);
1540 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1542 return print_bfs_bug(ret);
1547 that.class = hlock_class(next);
1548 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1550 return print_bfs_bug(ret);
1554 return print_bad_irq_dependency(curr, &this, &that,
1555 target_entry, target_entry1,
1557 bit_backwards, bit_forwards, irqclass);
1560 static const char *state_names[] = {
1561 #define LOCKDEP_STATE(__STATE) \
1562 __stringify(__STATE),
1563 #include "lockdep_states.h"
1564 #undef LOCKDEP_STATE
1567 static const char *state_rnames[] = {
1568 #define LOCKDEP_STATE(__STATE) \
1569 __stringify(__STATE)"-READ",
1570 #include "lockdep_states.h"
1571 #undef LOCKDEP_STATE
1574 static inline const char *state_name(enum lock_usage_bit bit)
1576 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1579 static int exclusive_bit(int new_bit)
1587 * bit 0 - write/read
1588 * bit 1 - used_in/enabled
1592 int state = new_bit & ~3;
1593 int dir = new_bit & 2;
1596 * keep state, bit flip the direction and strip read.
1598 return state | (dir ^ 2);
1601 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1602 struct held_lock *next, enum lock_usage_bit bit)
1605 * Prove that the new dependency does not connect a hardirq-safe
1606 * lock with a hardirq-unsafe lock - to achieve this we search
1607 * the backwards-subgraph starting at <prev>, and the
1608 * forwards-subgraph starting at <next>:
1610 if (!check_usage(curr, prev, next, bit,
1611 exclusive_bit(bit), state_name(bit)))
1617 * Prove that the new dependency does not connect a hardirq-safe-read
1618 * lock with a hardirq-unsafe lock - to achieve this we search
1619 * the backwards-subgraph starting at <prev>, and the
1620 * forwards-subgraph starting at <next>:
1622 if (!check_usage(curr, prev, next, bit,
1623 exclusive_bit(bit), state_name(bit)))
1630 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1631 struct held_lock *next)
1633 #define LOCKDEP_STATE(__STATE) \
1634 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1636 #include "lockdep_states.h"
1637 #undef LOCKDEP_STATE
1642 static void inc_chains(void)
1644 if (current->hardirq_context)
1645 nr_hardirq_chains++;
1647 if (current->softirq_context)
1648 nr_softirq_chains++;
1650 nr_process_chains++;
1657 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1658 struct held_lock *next)
1663 static inline void inc_chains(void)
1665 nr_process_chains++;
1671 print_deadlock_scenario(struct held_lock *nxt,
1672 struct held_lock *prv)
1674 struct lock_class *next = hlock_class(nxt);
1675 struct lock_class *prev = hlock_class(prv);
1677 printk(" Possible unsafe locking scenario:\n\n");
1681 __print_lock_name(prev);
1684 __print_lock_name(next);
1686 printk("\n *** DEADLOCK ***\n\n");
1687 printk(" May be due to missing lock nesting notation\n\n");
1691 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1692 struct held_lock *next)
1694 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1698 printk("=============================================\n");
1699 printk("[ INFO: possible recursive locking detected ]\n");
1700 print_kernel_version();
1701 printk("---------------------------------------------\n");
1702 printk("%s/%d is trying to acquire lock:\n",
1703 curr->comm, task_pid_nr(curr));
1705 printk("\nbut task is already holding lock:\n");
1708 printk("\nother info that might help us debug this:\n");
1709 print_deadlock_scenario(next, prev);
1710 lockdep_print_held_locks(curr);
1712 printk("\nstack backtrace:\n");
1719 * Check whether we are holding such a class already.
1721 * (Note that this has to be done separately, because the graph cannot
1722 * detect such classes of deadlocks.)
1724 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1727 check_deadlock(struct task_struct *curr, struct held_lock *next,
1728 struct lockdep_map *next_instance, int read)
1730 struct held_lock *prev;
1731 struct held_lock *nest = NULL;
1734 for (i = 0; i < curr->lockdep_depth; i++) {
1735 prev = curr->held_locks + i;
1737 if (prev->instance == next->nest_lock)
1740 if (hlock_class(prev) != hlock_class(next))
1744 * Allow read-after-read recursion of the same
1745 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1747 if ((read == 2) && prev->read)
1751 * We're holding the nest_lock, which serializes this lock's
1752 * nesting behaviour.
1757 return print_deadlock_bug(curr, prev, next);
1763 * There was a chain-cache miss, and we are about to add a new dependency
1764 * to a previous lock. We recursively validate the following rules:
1766 * - would the adding of the <prev> -> <next> dependency create a
1767 * circular dependency in the graph? [== circular deadlock]
1769 * - does the new prev->next dependency connect any hardirq-safe lock
1770 * (in the full backwards-subgraph starting at <prev>) with any
1771 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1772 * <next>)? [== illegal lock inversion with hardirq contexts]
1774 * - does the new prev->next dependency connect any softirq-safe lock
1775 * (in the full backwards-subgraph starting at <prev>) with any
1776 * softirq-unsafe lock (in the full forwards-subgraph starting at
1777 * <next>)? [== illegal lock inversion with softirq contexts]
1779 * any of these scenarios could lead to a deadlock.
1781 * Then if all the validations pass, we add the forwards and backwards
1785 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1786 struct held_lock *next, int distance, int trylock_loop)
1788 struct lock_list *entry;
1790 struct lock_list this;
1791 struct lock_list *uninitialized_var(target_entry);
1793 * Static variable, serialized by the graph_lock().
1795 * We use this static variable to save the stack trace in case
1796 * we call into this function multiple times due to encountering
1797 * trylocks in the held lock stack.
1799 static struct stack_trace trace;
1802 * Prove that the new <prev> -> <next> dependency would not
1803 * create a circular dependency in the graph. (We do this by
1804 * forward-recursing into the graph starting at <next>, and
1805 * checking whether we can reach <prev>.)
1807 * We are using global variables to control the recursion, to
1808 * keep the stackframe size of the recursive functions low:
1810 this.class = hlock_class(next);
1812 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1814 return print_circular_bug(&this, target_entry, next, prev);
1815 else if (unlikely(ret < 0))
1816 return print_bfs_bug(ret);
1818 if (!check_prev_add_irq(curr, prev, next))
1822 * For recursive read-locks we do all the dependency checks,
1823 * but we dont store read-triggered dependencies (only
1824 * write-triggered dependencies). This ensures that only the
1825 * write-side dependencies matter, and that if for example a
1826 * write-lock never takes any other locks, then the reads are
1827 * equivalent to a NOP.
1829 if (next->read == 2 || prev->read == 2)
1832 * Is the <prev> -> <next> dependency already present?
1834 * (this may occur even though this is a new chain: consider
1835 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1836 * chains - the second one will be new, but L1 already has
1837 * L2 added to its dependency list, due to the first chain.)
1839 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1840 if (entry->class == hlock_class(next)) {
1842 entry->distance = 1;
1847 if (!trylock_loop && !save_trace(&trace))
1851 * Ok, all validations passed, add the new lock
1852 * to the previous lock's dependency list:
1854 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1855 &hlock_class(prev)->locks_after,
1856 next->acquire_ip, distance, &trace);
1861 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1862 &hlock_class(next)->locks_before,
1863 next->acquire_ip, distance, &trace);
1868 * Debugging printouts:
1870 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1872 printk("\n new dependency: ");
1873 print_lock_name(hlock_class(prev));
1875 print_lock_name(hlock_class(next));
1878 return graph_lock();
1884 * Add the dependency to all directly-previous locks that are 'relevant'.
1885 * The ones that are relevant are (in increasing distance from curr):
1886 * all consecutive trylock entries and the final non-trylock entry - or
1887 * the end of this context's lock-chain - whichever comes first.
1890 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1892 int depth = curr->lockdep_depth;
1893 int trylock_loop = 0;
1894 struct held_lock *hlock;
1899 * Depth must not be zero for a non-head lock:
1904 * At least two relevant locks must exist for this
1907 if (curr->held_locks[depth].irq_context !=
1908 curr->held_locks[depth-1].irq_context)
1912 int distance = curr->lockdep_depth - depth + 1;
1913 hlock = curr->held_locks + depth-1;
1915 * Only non-recursive-read entries get new dependencies
1918 if (hlock->read != 2) {
1919 if (!check_prev_add(curr, hlock, next,
1920 distance, trylock_loop))
1923 * Stop after the first non-trylock entry,
1924 * as non-trylock entries have added their
1925 * own direct dependencies already, so this
1926 * lock is connected to them indirectly:
1928 if (!hlock->trylock)
1933 * End of lock-stack?
1938 * Stop the search if we cross into another context:
1940 if (curr->held_locks[depth].irq_context !=
1941 curr->held_locks[depth-1].irq_context)
1947 if (!debug_locks_off_graph_unlock())
1955 unsigned long nr_lock_chains;
1956 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1957 int nr_chain_hlocks;
1958 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1960 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1962 return lock_classes + chain_hlocks[chain->base + i];
1966 * Look up a dependency chain. If the key is not present yet then
1967 * add it and return 1 - in this case the new dependency chain is
1968 * validated. If the key is already hashed, return 0.
1969 * (On return with 1 graph_lock is held.)
1971 static inline int lookup_chain_cache(struct task_struct *curr,
1972 struct held_lock *hlock,
1975 struct lock_class *class = hlock_class(hlock);
1976 struct list_head *hash_head = chainhashentry(chain_key);
1977 struct lock_chain *chain;
1978 struct held_lock *hlock_curr, *hlock_next;
1981 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1984 * We can walk it lock-free, because entries only get added
1987 list_for_each_entry(chain, hash_head, entry) {
1988 if (chain->chain_key == chain_key) {
1990 debug_atomic_inc(chain_lookup_hits);
1991 if (very_verbose(class))
1992 printk("\nhash chain already cached, key: "
1993 "%016Lx tail class: [%p] %s\n",
1994 (unsigned long long)chain_key,
1995 class->key, class->name);
1999 if (very_verbose(class))
2000 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2001 (unsigned long long)chain_key, class->key, class->name);
2003 * Allocate a new chain entry from the static array, and add
2009 * We have to walk the chain again locked - to avoid duplicates:
2011 list_for_each_entry(chain, hash_head, entry) {
2012 if (chain->chain_key == chain_key) {
2017 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2018 if (!debug_locks_off_graph_unlock())
2021 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2022 printk("turning off the locking correctness validator.\n");
2026 chain = lock_chains + nr_lock_chains++;
2027 chain->chain_key = chain_key;
2028 chain->irq_context = hlock->irq_context;
2029 /* Find the first held_lock of current chain */
2031 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2032 hlock_curr = curr->held_locks + i;
2033 if (hlock_curr->irq_context != hlock_next->irq_context)
2038 chain->depth = curr->lockdep_depth + 1 - i;
2039 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2040 chain->base = nr_chain_hlocks;
2041 nr_chain_hlocks += chain->depth;
2042 for (j = 0; j < chain->depth - 1; j++, i++) {
2043 int lock_id = curr->held_locks[i].class_idx - 1;
2044 chain_hlocks[chain->base + j] = lock_id;
2046 chain_hlocks[chain->base + j] = class - lock_classes;
2048 list_add_tail_rcu(&chain->entry, hash_head);
2049 debug_atomic_inc(chain_lookup_misses);
2055 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2056 struct held_lock *hlock, int chain_head, u64 chain_key)
2059 * Trylock needs to maintain the stack of held locks, but it
2060 * does not add new dependencies, because trylock can be done
2063 * We look up the chain_key and do the O(N^2) check and update of
2064 * the dependencies only if this is a new dependency chain.
2065 * (If lookup_chain_cache() returns with 1 it acquires
2066 * graph_lock for us)
2068 if (!hlock->trylock && (hlock->check == 2) &&
2069 lookup_chain_cache(curr, hlock, chain_key)) {
2071 * Check whether last held lock:
2073 * - is irq-safe, if this lock is irq-unsafe
2074 * - is softirq-safe, if this lock is hardirq-unsafe
2076 * And check whether the new lock's dependency graph
2077 * could lead back to the previous lock.
2079 * any of these scenarios could lead to a deadlock. If
2082 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2087 * Mark recursive read, as we jump over it when
2088 * building dependencies (just like we jump over
2094 * Add dependency only if this lock is not the head
2095 * of the chain, and if it's not a secondary read-lock:
2097 if (!chain_head && ret != 2)
2098 if (!check_prevs_add(curr, hlock))
2102 /* after lookup_chain_cache(): */
2103 if (unlikely(!debug_locks))
2109 static inline int validate_chain(struct task_struct *curr,
2110 struct lockdep_map *lock, struct held_lock *hlock,
2111 int chain_head, u64 chain_key)
2118 * We are building curr_chain_key incrementally, so double-check
2119 * it from scratch, to make sure that it's done correctly:
2121 static void check_chain_key(struct task_struct *curr)
2123 #ifdef CONFIG_DEBUG_LOCKDEP
2124 struct held_lock *hlock, *prev_hlock = NULL;
2128 for (i = 0; i < curr->lockdep_depth; i++) {
2129 hlock = curr->held_locks + i;
2130 if (chain_key != hlock->prev_chain_key) {
2132 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2133 curr->lockdep_depth, i,
2134 (unsigned long long)chain_key,
2135 (unsigned long long)hlock->prev_chain_key);
2138 id = hlock->class_idx - 1;
2139 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2142 if (prev_hlock && (prev_hlock->irq_context !=
2143 hlock->irq_context))
2145 chain_key = iterate_chain_key(chain_key, id);
2148 if (chain_key != curr->curr_chain_key) {
2150 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2151 curr->lockdep_depth, i,
2152 (unsigned long long)chain_key,
2153 (unsigned long long)curr->curr_chain_key);
2159 print_usage_bug_scenario(struct held_lock *lock)
2161 struct lock_class *class = hlock_class(lock);
2163 printk(" Possible unsafe locking scenario:\n\n");
2167 __print_lock_name(class);
2169 printk(" <Interrupt>\n");
2171 __print_lock_name(class);
2173 printk("\n *** DEADLOCK ***\n\n");
2177 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2178 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2180 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2184 printk("=================================\n");
2185 printk("[ INFO: inconsistent lock state ]\n");
2186 print_kernel_version();
2187 printk("---------------------------------\n");
2189 printk("inconsistent {%s} -> {%s} usage.\n",
2190 usage_str[prev_bit], usage_str[new_bit]);
2192 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2193 curr->comm, task_pid_nr(curr),
2194 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2195 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2196 trace_hardirqs_enabled(curr),
2197 trace_softirqs_enabled(curr));
2200 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2201 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2203 print_irqtrace_events(curr);
2204 printk("\nother info that might help us debug this:\n");
2205 print_usage_bug_scenario(this);
2207 lockdep_print_held_locks(curr);
2209 printk("\nstack backtrace:\n");
2216 * Print out an error if an invalid bit is set:
2219 valid_state(struct task_struct *curr, struct held_lock *this,
2220 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2222 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2223 return print_usage_bug(curr, this, bad_bit, new_bit);
2227 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2228 enum lock_usage_bit new_bit);
2230 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2233 * print irq inversion bug:
2236 print_irq_inversion_bug(struct task_struct *curr,
2237 struct lock_list *root, struct lock_list *other,
2238 struct held_lock *this, int forwards,
2239 const char *irqclass)
2241 struct lock_list *entry = other;
2242 struct lock_list *middle = NULL;
2245 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2249 printk("=========================================================\n");
2250 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2251 print_kernel_version();
2252 printk("---------------------------------------------------------\n");
2253 printk("%s/%d just changed the state of lock:\n",
2254 curr->comm, task_pid_nr(curr));
2257 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2259 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2260 print_lock_name(other->class);
2261 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2263 printk("\nother info that might help us debug this:\n");
2265 /* Find a middle lock (if one exists) */
2266 depth = get_lock_depth(other);
2268 if (depth == 0 && (entry != root)) {
2269 printk("lockdep:%s bad path found in chain graph\n", __func__);
2273 entry = get_lock_parent(entry);
2275 } while (entry && entry != root && (depth >= 0));
2277 print_irq_lock_scenario(root, other,
2278 middle ? middle->class : root->class, other->class);
2280 print_irq_lock_scenario(other, root,
2281 middle ? middle->class : other->class, root->class);
2283 lockdep_print_held_locks(curr);
2285 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2286 if (!save_trace(&root->trace))
2288 print_shortest_lock_dependencies(other, root);
2290 printk("\nstack backtrace:\n");
2297 * Prove that in the forwards-direction subgraph starting at <this>
2298 * there is no lock matching <mask>:
2301 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2302 enum lock_usage_bit bit, const char *irqclass)
2305 struct lock_list root;
2306 struct lock_list *uninitialized_var(target_entry);
2309 root.class = hlock_class(this);
2310 ret = find_usage_forwards(&root, bit, &target_entry);
2312 return print_bfs_bug(ret);
2316 return print_irq_inversion_bug(curr, &root, target_entry,
2321 * Prove that in the backwards-direction subgraph starting at <this>
2322 * there is no lock matching <mask>:
2325 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2326 enum lock_usage_bit bit, const char *irqclass)
2329 struct lock_list root;
2330 struct lock_list *uninitialized_var(target_entry);
2333 root.class = hlock_class(this);
2334 ret = find_usage_backwards(&root, bit, &target_entry);
2336 return print_bfs_bug(ret);
2340 return print_irq_inversion_bug(curr, &root, target_entry,
2344 void print_irqtrace_events(struct task_struct *curr)
2346 printk("irq event stamp: %u\n", curr->irq_events);
2347 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2348 print_ip_sym(curr->hardirq_enable_ip);
2349 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2350 print_ip_sym(curr->hardirq_disable_ip);
2351 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2352 print_ip_sym(curr->softirq_enable_ip);
2353 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2354 print_ip_sym(curr->softirq_disable_ip);
2357 static int HARDIRQ_verbose(struct lock_class *class)
2360 return class_filter(class);
2365 static int SOFTIRQ_verbose(struct lock_class *class)
2368 return class_filter(class);
2373 static int RECLAIM_FS_verbose(struct lock_class *class)
2376 return class_filter(class);
2381 #define STRICT_READ_CHECKS 1
2383 static int (*state_verbose_f[])(struct lock_class *class) = {
2384 #define LOCKDEP_STATE(__STATE) \
2386 #include "lockdep_states.h"
2387 #undef LOCKDEP_STATE
2390 static inline int state_verbose(enum lock_usage_bit bit,
2391 struct lock_class *class)
2393 return state_verbose_f[bit >> 2](class);
2396 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2397 enum lock_usage_bit bit, const char *name);
2400 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2401 enum lock_usage_bit new_bit)
2403 int excl_bit = exclusive_bit(new_bit);
2404 int read = new_bit & 1;
2405 int dir = new_bit & 2;
2408 * mark USED_IN has to look forwards -- to ensure no dependency
2409 * has ENABLED state, which would allow recursion deadlocks.
2411 * mark ENABLED has to look backwards -- to ensure no dependee
2412 * has USED_IN state, which, again, would allow recursion deadlocks.
2414 check_usage_f usage = dir ?
2415 check_usage_backwards : check_usage_forwards;
2418 * Validate that this particular lock does not have conflicting
2421 if (!valid_state(curr, this, new_bit, excl_bit))
2425 * Validate that the lock dependencies don't have conflicting usage
2428 if ((!read || !dir || STRICT_READ_CHECKS) &&
2429 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2433 * Check for read in write conflicts
2436 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2439 if (STRICT_READ_CHECKS &&
2440 !usage(curr, this, excl_bit + 1,
2441 state_name(new_bit + 1)))
2445 if (state_verbose(new_bit, hlock_class(this)))
2452 #define LOCKDEP_STATE(__STATE) __STATE,
2453 #include "lockdep_states.h"
2454 #undef LOCKDEP_STATE
2458 * Mark all held locks with a usage bit:
2461 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2463 enum lock_usage_bit usage_bit;
2464 struct held_lock *hlock;
2467 for (i = 0; i < curr->lockdep_depth; i++) {
2468 hlock = curr->held_locks + i;
2470 usage_bit = 2 + (mark << 2); /* ENABLED */
2472 usage_bit += 1; /* READ */
2474 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2476 if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
2479 if (!mark_lock(curr, hlock, usage_bit))
2487 * Hardirqs will be enabled:
2489 static void __trace_hardirqs_on_caller(unsigned long ip)
2491 struct task_struct *curr = current;
2493 /* we'll do an OFF -> ON transition: */
2494 curr->hardirqs_enabled = 1;
2497 * We are going to turn hardirqs on, so set the
2498 * usage bit for all held locks:
2500 if (!mark_held_locks(curr, HARDIRQ))
2503 * If we have softirqs enabled, then set the usage
2504 * bit for all held locks. (disabled hardirqs prevented
2505 * this bit from being set before)
2507 if (curr->softirqs_enabled)
2508 if (!mark_held_locks(curr, SOFTIRQ))
2511 curr->hardirq_enable_ip = ip;
2512 curr->hardirq_enable_event = ++curr->irq_events;
2513 debug_atomic_inc(hardirqs_on_events);
2516 void trace_hardirqs_on_caller(unsigned long ip)
2518 time_hardirqs_on(CALLER_ADDR0, ip);
2520 if (unlikely(!debug_locks || current->lockdep_recursion))
2523 if (unlikely(current->hardirqs_enabled)) {
2525 * Neither irq nor preemption are disabled here
2526 * so this is racy by nature but losing one hit
2527 * in a stat is not a big deal.
2529 __debug_atomic_inc(redundant_hardirqs_on);
2533 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2536 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2539 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2542 current->lockdep_recursion = 1;
2543 __trace_hardirqs_on_caller(ip);
2544 current->lockdep_recursion = 0;
2546 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2548 void trace_hardirqs_on(void)
2550 trace_hardirqs_on_caller(CALLER_ADDR0);
2552 EXPORT_SYMBOL(trace_hardirqs_on);
2555 * Hardirqs were disabled:
2557 void trace_hardirqs_off_caller(unsigned long ip)
2559 struct task_struct *curr = current;
2561 time_hardirqs_off(CALLER_ADDR0, ip);
2563 if (unlikely(!debug_locks || current->lockdep_recursion))
2566 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2569 if (curr->hardirqs_enabled) {
2571 * We have done an ON -> OFF transition:
2573 curr->hardirqs_enabled = 0;
2574 curr->hardirq_disable_ip = ip;
2575 curr->hardirq_disable_event = ++curr->irq_events;
2576 debug_atomic_inc(hardirqs_off_events);
2578 debug_atomic_inc(redundant_hardirqs_off);
2580 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2582 void trace_hardirqs_off(void)
2584 trace_hardirqs_off_caller(CALLER_ADDR0);
2586 EXPORT_SYMBOL(trace_hardirqs_off);
2589 * Softirqs will be enabled:
2591 void trace_softirqs_on(unsigned long ip)
2593 struct task_struct *curr = current;
2595 if (unlikely(!debug_locks || current->lockdep_recursion))
2598 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2601 if (curr->softirqs_enabled) {
2602 debug_atomic_inc(redundant_softirqs_on);
2606 current->lockdep_recursion = 1;
2608 * We'll do an OFF -> ON transition:
2610 curr->softirqs_enabled = 1;
2611 curr->softirq_enable_ip = ip;
2612 curr->softirq_enable_event = ++curr->irq_events;
2613 debug_atomic_inc(softirqs_on_events);
2615 * We are going to turn softirqs on, so set the
2616 * usage bit for all held locks, if hardirqs are
2619 if (curr->hardirqs_enabled)
2620 mark_held_locks(curr, SOFTIRQ);
2621 current->lockdep_recursion = 0;
2625 * Softirqs were disabled:
2627 void trace_softirqs_off(unsigned long ip)
2629 struct task_struct *curr = current;
2631 if (unlikely(!debug_locks || current->lockdep_recursion))
2634 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2637 if (curr->softirqs_enabled) {
2639 * We have done an ON -> OFF transition:
2641 curr->softirqs_enabled = 0;
2642 curr->softirq_disable_ip = ip;
2643 curr->softirq_disable_event = ++curr->irq_events;
2644 debug_atomic_inc(softirqs_off_events);
2645 DEBUG_LOCKS_WARN_ON(!softirq_count());
2647 debug_atomic_inc(redundant_softirqs_off);
2650 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2652 struct task_struct *curr = current;
2654 if (unlikely(!debug_locks))
2657 /* no reclaim without waiting on it */
2658 if (!(gfp_mask & __GFP_WAIT))
2661 /* this guy won't enter reclaim */
2662 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2665 /* We're only interested __GFP_FS allocations for now */
2666 if (!(gfp_mask & __GFP_FS))
2669 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2672 mark_held_locks(curr, RECLAIM_FS);
2675 static void check_flags(unsigned long flags);
2677 void lockdep_trace_alloc(gfp_t gfp_mask)
2679 unsigned long flags;
2681 if (unlikely(current->lockdep_recursion))
2684 raw_local_irq_save(flags);
2686 current->lockdep_recursion = 1;
2687 __lockdep_trace_alloc(gfp_mask, flags);
2688 current->lockdep_recursion = 0;
2689 raw_local_irq_restore(flags);
2692 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2695 * If non-trylock use in a hardirq or softirq context, then
2696 * mark the lock as used in these contexts:
2698 if (!hlock->trylock) {
2700 if (curr->hardirq_context)
2701 if (!mark_lock(curr, hlock,
2702 LOCK_USED_IN_HARDIRQ_READ))
2704 if (curr->softirq_context)
2705 if (!mark_lock(curr, hlock,
2706 LOCK_USED_IN_SOFTIRQ_READ))
2709 if (curr->hardirq_context)
2710 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2712 if (curr->softirq_context)
2713 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2717 if (!hlock->hardirqs_off) {
2719 if (!mark_lock(curr, hlock,
2720 LOCK_ENABLED_HARDIRQ_READ))
2722 if (curr->softirqs_enabled)
2723 if (!mark_lock(curr, hlock,
2724 LOCK_ENABLED_SOFTIRQ_READ))
2727 if (!mark_lock(curr, hlock,
2728 LOCK_ENABLED_HARDIRQ))
2730 if (curr->softirqs_enabled)
2731 if (!mark_lock(curr, hlock,
2732 LOCK_ENABLED_SOFTIRQ))
2738 * We reuse the irq context infrastructure more broadly as a general
2739 * context checking code. This tests GFP_FS recursion (a lock taken
2740 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2743 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2745 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2748 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2756 static int separate_irq_context(struct task_struct *curr,
2757 struct held_lock *hlock)
2759 unsigned int depth = curr->lockdep_depth;
2762 * Keep track of points where we cross into an interrupt context:
2764 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2765 curr->softirq_context;
2767 struct held_lock *prev_hlock;
2769 prev_hlock = curr->held_locks + depth-1;
2771 * If we cross into another context, reset the
2772 * hash key (this also prevents the checking and the
2773 * adding of the dependency to 'prev'):
2775 if (prev_hlock->irq_context != hlock->irq_context)
2784 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2785 enum lock_usage_bit new_bit)
2791 static inline int mark_irqflags(struct task_struct *curr,
2792 struct held_lock *hlock)
2797 static inline int separate_irq_context(struct task_struct *curr,
2798 struct held_lock *hlock)
2803 void lockdep_trace_alloc(gfp_t gfp_mask)
2810 * Mark a lock with a usage bit, and validate the state transition:
2812 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2813 enum lock_usage_bit new_bit)
2815 unsigned int new_mask = 1 << new_bit, ret = 1;
2818 * If already set then do not dirty the cacheline,
2819 * nor do any checks:
2821 if (likely(hlock_class(this)->usage_mask & new_mask))
2827 * Make sure we didn't race:
2829 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2834 hlock_class(this)->usage_mask |= new_mask;
2836 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2840 #define LOCKDEP_STATE(__STATE) \
2841 case LOCK_USED_IN_##__STATE: \
2842 case LOCK_USED_IN_##__STATE##_READ: \
2843 case LOCK_ENABLED_##__STATE: \
2844 case LOCK_ENABLED_##__STATE##_READ:
2845 #include "lockdep_states.h"
2846 #undef LOCKDEP_STATE
2847 ret = mark_lock_irq(curr, this, new_bit);
2852 debug_atomic_dec(nr_unused_locks);
2855 if (!debug_locks_off_graph_unlock())
2864 * We must printk outside of the graph_lock:
2867 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2869 print_irqtrace_events(curr);
2877 * Initialize a lock instance's lock-class mapping info:
2879 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2880 struct lock_class_key *key, int subclass)
2882 memset(lock, 0, sizeof(*lock));
2884 #ifdef CONFIG_LOCK_STAT
2885 lock->cpu = raw_smp_processor_id();
2888 if (DEBUG_LOCKS_WARN_ON(!name)) {
2889 lock->name = "NULL";
2895 if (DEBUG_LOCKS_WARN_ON(!key))
2898 * Sanity check, the lock-class key must be persistent:
2900 if (!static_obj(key)) {
2901 printk("BUG: key %p not in .data!\n", key);
2902 DEBUG_LOCKS_WARN_ON(1);
2907 if (unlikely(!debug_locks))
2911 register_lock_class(lock, subclass, 1);
2913 EXPORT_SYMBOL_GPL(lockdep_init_map);
2915 struct lock_class_key __lockdep_no_validate__;
2918 * This gets called for every mutex_lock*()/spin_lock*() operation.
2919 * We maintain the dependency maps and validate the locking attempt:
2921 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2922 int trylock, int read, int check, int hardirqs_off,
2923 struct lockdep_map *nest_lock, unsigned long ip,
2926 struct task_struct *curr = current;
2927 struct lock_class *class = NULL;
2928 struct held_lock *hlock;
2929 unsigned int depth, id;
2937 if (unlikely(!debug_locks))
2940 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2943 if (lock->key == &__lockdep_no_validate__)
2946 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
2947 class = lock->class_cache[subclass];
2951 if (unlikely(!class)) {
2952 class = register_lock_class(lock, subclass, 0);
2956 atomic_inc((atomic_t *)&class->ops);
2957 if (very_verbose(class)) {
2958 printk("\nacquire class [%p] %s", class->key, class->name);
2959 if (class->name_version > 1)
2960 printk("#%d", class->name_version);
2966 * Add the lock to the list of currently held locks.
2967 * (we dont increase the depth just yet, up until the
2968 * dependency checks are done)
2970 depth = curr->lockdep_depth;
2971 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2974 class_idx = class - lock_classes + 1;
2977 hlock = curr->held_locks + depth - 1;
2978 if (hlock->class_idx == class_idx && nest_lock) {
2979 if (hlock->references)
2980 hlock->references++;
2982 hlock->references = 2;
2988 hlock = curr->held_locks + depth;
2989 if (DEBUG_LOCKS_WARN_ON(!class))
2991 hlock->class_idx = class_idx;
2992 hlock->acquire_ip = ip;
2993 hlock->instance = lock;
2994 hlock->nest_lock = nest_lock;
2995 hlock->trylock = trylock;
2997 hlock->check = check;
2998 hlock->hardirqs_off = !!hardirqs_off;
2999 hlock->references = references;
3000 #ifdef CONFIG_LOCK_STAT
3001 hlock->waittime_stamp = 0;
3002 hlock->holdtime_stamp = lockstat_clock();
3005 if (check == 2 && !mark_irqflags(curr, hlock))
3008 /* mark it as used: */
3009 if (!mark_lock(curr, hlock, LOCK_USED))
3013 * Calculate the chain hash: it's the combined hash of all the
3014 * lock keys along the dependency chain. We save the hash value
3015 * at every step so that we can get the current hash easily
3016 * after unlock. The chain hash is then used to cache dependency
3019 * The 'key ID' is what is the most compact key value to drive
3020 * the hash, not class->key.
3022 id = class - lock_classes;
3023 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3026 chain_key = curr->curr_chain_key;
3028 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3033 hlock->prev_chain_key = chain_key;
3034 if (separate_irq_context(curr, hlock)) {
3038 chain_key = iterate_chain_key(chain_key, id);
3040 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3043 curr->curr_chain_key = chain_key;
3044 curr->lockdep_depth++;
3045 check_chain_key(curr);
3046 #ifdef CONFIG_DEBUG_LOCKDEP
3047 if (unlikely(!debug_locks))
3050 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3052 printk("BUG: MAX_LOCK_DEPTH too low!\n");
3053 printk("turning off the locking correctness validator.\n");
3058 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3059 max_lockdep_depth = curr->lockdep_depth;
3065 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3068 if (!debug_locks_off())
3070 if (debug_locks_silent)
3074 printk("=====================================\n");
3075 printk("[ BUG: bad unlock balance detected! ]\n");
3076 printk("-------------------------------------\n");
3077 printk("%s/%d is trying to release lock (",
3078 curr->comm, task_pid_nr(curr));
3079 print_lockdep_cache(lock);
3082 printk("but there are no more locks to release!\n");
3083 printk("\nother info that might help us debug this:\n");
3084 lockdep_print_held_locks(curr);
3086 printk("\nstack backtrace:\n");
3093 * Common debugging checks for both nested and non-nested unlock:
3095 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3098 if (unlikely(!debug_locks))
3100 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3103 if (curr->lockdep_depth <= 0)
3104 return print_unlock_inbalance_bug(curr, lock, ip);
3109 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3111 if (hlock->instance == lock)
3114 if (hlock->references) {
3115 struct lock_class *class = lock->class_cache[0];
3118 class = look_up_lock_class(lock, 0);
3121 * If look_up_lock_class() failed to find a class, we're trying
3122 * to test if we hold a lock that has never yet been acquired.
3123 * Clearly if the lock hasn't been acquired _ever_, we're not
3124 * holding it either, so report failure.
3129 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3132 if (hlock->class_idx == class - lock_classes + 1)
3140 __lock_set_class(struct lockdep_map *lock, const char *name,
3141 struct lock_class_key *key, unsigned int subclass,
3144 struct task_struct *curr = current;
3145 struct held_lock *hlock, *prev_hlock;
3146 struct lock_class *class;
3150 depth = curr->lockdep_depth;
3151 if (DEBUG_LOCKS_WARN_ON(!depth))
3155 for (i = depth-1; i >= 0; i--) {
3156 hlock = curr->held_locks + i;
3158 * We must not cross into another context:
3160 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3162 if (match_held_lock(hlock, lock))
3166 return print_unlock_inbalance_bug(curr, lock, ip);
3169 lockdep_init_map(lock, name, key, 0);
3170 class = register_lock_class(lock, subclass, 0);
3171 hlock->class_idx = class - lock_classes + 1;
3173 curr->lockdep_depth = i;
3174 curr->curr_chain_key = hlock->prev_chain_key;
3176 for (; i < depth; i++) {
3177 hlock = curr->held_locks + i;
3178 if (!__lock_acquire(hlock->instance,
3179 hlock_class(hlock)->subclass, hlock->trylock,
3180 hlock->read, hlock->check, hlock->hardirqs_off,
3181 hlock->nest_lock, hlock->acquire_ip,
3186 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3192 * Remove the lock to the list of currently held locks in a
3193 * potentially non-nested (out of order) manner. This is a
3194 * relatively rare operation, as all the unlock APIs default
3195 * to nested mode (which uses lock_release()):
3198 lock_release_non_nested(struct task_struct *curr,
3199 struct lockdep_map *lock, unsigned long ip)
3201 struct held_lock *hlock, *prev_hlock;
3206 * Check whether the lock exists in the current stack
3209 depth = curr->lockdep_depth;
3210 if (DEBUG_LOCKS_WARN_ON(!depth))
3214 for (i = depth-1; i >= 0; i--) {
3215 hlock = curr->held_locks + i;
3217 * We must not cross into another context:
3219 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3221 if (match_held_lock(hlock, lock))
3225 return print_unlock_inbalance_bug(curr, lock, ip);
3228 if (hlock->instance == lock)
3229 lock_release_holdtime(hlock);
3231 if (hlock->references) {
3232 hlock->references--;
3233 if (hlock->references) {
3235 * We had, and after removing one, still have
3236 * references, the current lock stack is still
3237 * valid. We're done!
3244 * We have the right lock to unlock, 'hlock' points to it.
3245 * Now we remove it from the stack, and add back the other
3246 * entries (if any), recalculating the hash along the way:
3249 curr->lockdep_depth = i;
3250 curr->curr_chain_key = hlock->prev_chain_key;
3252 for (i++; i < depth; i++) {
3253 hlock = curr->held_locks + i;
3254 if (!__lock_acquire(hlock->instance,
3255 hlock_class(hlock)->subclass, hlock->trylock,
3256 hlock->read, hlock->check, hlock->hardirqs_off,
3257 hlock->nest_lock, hlock->acquire_ip,
3262 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3268 * Remove the lock to the list of currently held locks - this gets
3269 * called on mutex_unlock()/spin_unlock*() (or on a failed
3270 * mutex_lock_interruptible()). This is done for unlocks that nest
3271 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3273 static int lock_release_nested(struct task_struct *curr,
3274 struct lockdep_map *lock, unsigned long ip)
3276 struct held_lock *hlock;
3280 * Pop off the top of the lock stack:
3282 depth = curr->lockdep_depth - 1;
3283 hlock = curr->held_locks + depth;
3286 * Is the unlock non-nested:
3288 if (hlock->instance != lock || hlock->references)
3289 return lock_release_non_nested(curr, lock, ip);
3290 curr->lockdep_depth--;
3292 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3295 curr->curr_chain_key = hlock->prev_chain_key;
3297 lock_release_holdtime(hlock);
3299 #ifdef CONFIG_DEBUG_LOCKDEP
3300 hlock->prev_chain_key = 0;
3301 hlock->class_idx = 0;
3302 hlock->acquire_ip = 0;
3303 hlock->irq_context = 0;
3309 * Remove the lock to the list of currently held locks - this gets
3310 * called on mutex_unlock()/spin_unlock*() (or on a failed
3311 * mutex_lock_interruptible()). This is done for unlocks that nest
3312 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3315 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3317 struct task_struct *curr = current;
3319 if (!check_unlock(curr, lock, ip))
3323 if (!lock_release_nested(curr, lock, ip))
3326 if (!lock_release_non_nested(curr, lock, ip))
3330 check_chain_key(curr);
3333 static int __lock_is_held(struct lockdep_map *lock)
3335 struct task_struct *curr = current;
3338 for (i = 0; i < curr->lockdep_depth; i++) {
3339 struct held_lock *hlock = curr->held_locks + i;
3341 if (match_held_lock(hlock, lock))
3349 * Check whether we follow the irq-flags state precisely:
3351 static void check_flags(unsigned long flags)
3353 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3354 defined(CONFIG_TRACE_IRQFLAGS)
3358 if (irqs_disabled_flags(flags)) {
3359 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3360 printk("possible reason: unannotated irqs-off.\n");
3363 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3364 printk("possible reason: unannotated irqs-on.\n");
3369 * We dont accurately track softirq state in e.g.
3370 * hardirq contexts (such as on 4KSTACKS), so only
3371 * check if not in hardirq contexts:
3373 if (!hardirq_count()) {
3374 if (softirq_count())
3375 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3377 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3381 print_irqtrace_events(current);
3385 void lock_set_class(struct lockdep_map *lock, const char *name,
3386 struct lock_class_key *key, unsigned int subclass,
3389 unsigned long flags;
3391 if (unlikely(current->lockdep_recursion))
3394 raw_local_irq_save(flags);
3395 current->lockdep_recursion = 1;
3397 if (__lock_set_class(lock, name, key, subclass, ip))
3398 check_chain_key(current);
3399 current->lockdep_recursion = 0;
3400 raw_local_irq_restore(flags);
3402 EXPORT_SYMBOL_GPL(lock_set_class);
3405 * We are not always called with irqs disabled - do that here,
3406 * and also avoid lockdep recursion:
3408 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3409 int trylock, int read, int check,
3410 struct lockdep_map *nest_lock, unsigned long ip)
3412 unsigned long flags;
3414 if (unlikely(current->lockdep_recursion))
3417 raw_local_irq_save(flags);
3420 current->lockdep_recursion = 1;
3421 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3422 __lock_acquire(lock, subclass, trylock, read, check,
3423 irqs_disabled_flags(flags), nest_lock, ip, 0);
3424 current->lockdep_recursion = 0;
3425 raw_local_irq_restore(flags);
3427 EXPORT_SYMBOL_GPL(lock_acquire);
3429 void lock_release(struct lockdep_map *lock, int nested,
3432 unsigned long flags;
3434 if (unlikely(current->lockdep_recursion))
3437 raw_local_irq_save(flags);
3439 current->lockdep_recursion = 1;
3440 trace_lock_release(lock, ip);
3441 __lock_release(lock, nested, ip);
3442 current->lockdep_recursion = 0;
3443 raw_local_irq_restore(flags);
3445 EXPORT_SYMBOL_GPL(lock_release);
3447 int lock_is_held(struct lockdep_map *lock)
3449 unsigned long flags;
3452 if (unlikely(current->lockdep_recursion))
3453 return 1; /* avoid false negative lockdep_assert_held() */
3455 raw_local_irq_save(flags);
3458 current->lockdep_recursion = 1;
3459 ret = __lock_is_held(lock);
3460 current->lockdep_recursion = 0;
3461 raw_local_irq_restore(flags);
3465 EXPORT_SYMBOL_GPL(lock_is_held);
3467 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3469 current->lockdep_reclaim_gfp = gfp_mask;
3472 void lockdep_clear_current_reclaim_state(void)
3474 current->lockdep_reclaim_gfp = 0;
3477 #ifdef CONFIG_LOCK_STAT
3479 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3482 if (!debug_locks_off())
3484 if (debug_locks_silent)
3488 printk("=================================\n");
3489 printk("[ BUG: bad contention detected! ]\n");
3490 printk("---------------------------------\n");
3491 printk("%s/%d is trying to contend lock (",
3492 curr->comm, task_pid_nr(curr));
3493 print_lockdep_cache(lock);
3496 printk("but there are no locks held!\n");
3497 printk("\nother info that might help us debug this:\n");
3498 lockdep_print_held_locks(curr);
3500 printk("\nstack backtrace:\n");
3507 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3509 struct task_struct *curr = current;
3510 struct held_lock *hlock, *prev_hlock;
3511 struct lock_class_stats *stats;
3513 int i, contention_point, contending_point;
3515 depth = curr->lockdep_depth;
3516 if (DEBUG_LOCKS_WARN_ON(!depth))
3520 for (i = depth-1; i >= 0; i--) {
3521 hlock = curr->held_locks + i;
3523 * We must not cross into another context:
3525 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3527 if (match_held_lock(hlock, lock))
3531 print_lock_contention_bug(curr, lock, ip);
3535 if (hlock->instance != lock)
3538 hlock->waittime_stamp = lockstat_clock();
3540 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3541 contending_point = lock_point(hlock_class(hlock)->contending_point,
3544 stats = get_lock_stats(hlock_class(hlock));
3545 if (contention_point < LOCKSTAT_POINTS)
3546 stats->contention_point[contention_point]++;
3547 if (contending_point < LOCKSTAT_POINTS)
3548 stats->contending_point[contending_point]++;
3549 if (lock->cpu != smp_processor_id())
3550 stats->bounces[bounce_contended + !!hlock->read]++;
3551 put_lock_stats(stats);
3555 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3557 struct task_struct *curr = current;
3558 struct held_lock *hlock, *prev_hlock;
3559 struct lock_class_stats *stats;
3561 u64 now, waittime = 0;
3564 depth = curr->lockdep_depth;
3565 if (DEBUG_LOCKS_WARN_ON(!depth))
3569 for (i = depth-1; i >= 0; i--) {
3570 hlock = curr->held_locks + i;
3572 * We must not cross into another context:
3574 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3576 if (match_held_lock(hlock, lock))
3580 print_lock_contention_bug(curr, lock, _RET_IP_);
3584 if (hlock->instance != lock)
3587 cpu = smp_processor_id();
3588 if (hlock->waittime_stamp) {
3589 now = lockstat_clock();
3590 waittime = now - hlock->waittime_stamp;
3591 hlock->holdtime_stamp = now;
3594 trace_lock_acquired(lock, ip);
3596 stats = get_lock_stats(hlock_class(hlock));
3599 lock_time_inc(&stats->read_waittime, waittime);
3601 lock_time_inc(&stats->write_waittime, waittime);
3603 if (lock->cpu != cpu)
3604 stats->bounces[bounce_acquired + !!hlock->read]++;
3605 put_lock_stats(stats);
3611 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3613 unsigned long flags;
3615 if (unlikely(!lock_stat))
3618 if (unlikely(current->lockdep_recursion))
3621 raw_local_irq_save(flags);
3623 current->lockdep_recursion = 1;
3624 trace_lock_contended(lock, ip);
3625 __lock_contended(lock, ip);
3626 current->lockdep_recursion = 0;
3627 raw_local_irq_restore(flags);
3629 EXPORT_SYMBOL_GPL(lock_contended);
3631 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3633 unsigned long flags;
3635 if (unlikely(!lock_stat))
3638 if (unlikely(current->lockdep_recursion))
3641 raw_local_irq_save(flags);
3643 current->lockdep_recursion = 1;
3644 __lock_acquired(lock, ip);
3645 current->lockdep_recursion = 0;
3646 raw_local_irq_restore(flags);
3648 EXPORT_SYMBOL_GPL(lock_acquired);
3652 * Used by the testsuite, sanitize the validator state
3653 * after a simulated failure:
3656 void lockdep_reset(void)
3658 unsigned long flags;
3661 raw_local_irq_save(flags);
3662 current->curr_chain_key = 0;
3663 current->lockdep_depth = 0;
3664 current->lockdep_recursion = 0;
3665 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3666 nr_hardirq_chains = 0;
3667 nr_softirq_chains = 0;
3668 nr_process_chains = 0;
3670 for (i = 0; i < CHAINHASH_SIZE; i++)
3671 INIT_LIST_HEAD(chainhash_table + i);
3672 raw_local_irq_restore(flags);
3675 static void zap_class(struct lock_class *class)
3680 * Remove all dependencies this lock is
3683 for (i = 0; i < nr_list_entries; i++) {
3684 if (list_entries[i].class == class)
3685 list_del_rcu(&list_entries[i].entry);
3688 * Unhash the class and remove it from the all_lock_classes list:
3690 list_del_rcu(&class->hash_entry);
3691 list_del_rcu(&class->lock_entry);
3696 static inline int within(const void *addr, void *start, unsigned long size)
3698 return addr >= start && addr < start + size;
3701 void lockdep_free_key_range(void *start, unsigned long size)
3703 struct lock_class *class, *next;
3704 struct list_head *head;
3705 unsigned long flags;
3709 raw_local_irq_save(flags);
3710 locked = graph_lock();
3713 * Unhash all classes that were created by this module:
3715 for (i = 0; i < CLASSHASH_SIZE; i++) {
3716 head = classhash_table + i;
3717 if (list_empty(head))
3719 list_for_each_entry_safe(class, next, head, hash_entry) {
3720 if (within(class->key, start, size))
3722 else if (within(class->name, start, size))
3729 raw_local_irq_restore(flags);
3732 void lockdep_reset_lock(struct lockdep_map *lock)
3734 struct lock_class *class, *next;
3735 struct list_head *head;
3736 unsigned long flags;
3740 raw_local_irq_save(flags);
3743 * Remove all classes this lock might have:
3745 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3747 * If the class exists we look it up and zap it:
3749 class = look_up_lock_class(lock, j);
3754 * Debug check: in the end all mapped classes should
3757 locked = graph_lock();
3758 for (i = 0; i < CLASSHASH_SIZE; i++) {
3759 head = classhash_table + i;
3760 if (list_empty(head))
3762 list_for_each_entry_safe(class, next, head, hash_entry) {
3765 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3766 match |= class == lock->class_cache[j];
3768 if (unlikely(match)) {
3769 if (debug_locks_off_graph_unlock())
3779 raw_local_irq_restore(flags);
3782 void lockdep_init(void)
3787 * Some architectures have their own start_kernel()
3788 * code which calls lockdep_init(), while we also
3789 * call lockdep_init() from the start_kernel() itself,
3790 * and we want to initialize the hashes only once:
3792 if (lockdep_initialized)
3795 for (i = 0; i < CLASSHASH_SIZE; i++)
3796 INIT_LIST_HEAD(classhash_table + i);
3798 for (i = 0; i < CHAINHASH_SIZE; i++)
3799 INIT_LIST_HEAD(chainhash_table + i);
3801 lockdep_initialized = 1;
3804 void __init lockdep_info(void)
3806 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3808 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3809 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3810 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3811 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3812 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3813 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3814 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3816 printk(" memory used by lock dependency info: %lu kB\n",
3817 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3818 sizeof(struct list_head) * CLASSHASH_SIZE +
3819 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3820 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3821 sizeof(struct list_head) * CHAINHASH_SIZE
3822 #ifdef CONFIG_PROVE_LOCKING
3823 + sizeof(struct circular_queue)
3828 printk(" per task-struct memory footprint: %lu bytes\n",
3829 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3831 #ifdef CONFIG_DEBUG_LOCKDEP
3832 if (lockdep_init_error) {
3833 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3834 printk("Call stack leading to lockdep invocation was:\n");
3835 print_stack_trace(&lockdep_init_trace, 0);
3841 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3842 const void *mem_to, struct held_lock *hlock)
3844 if (!debug_locks_off())
3846 if (debug_locks_silent)
3850 printk("=========================\n");
3851 printk("[ BUG: held lock freed! ]\n");
3852 printk("-------------------------\n");
3853 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3854 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3856 lockdep_print_held_locks(curr);
3858 printk("\nstack backtrace:\n");
3862 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3863 const void* lock_from, unsigned long lock_len)
3865 return lock_from + lock_len <= mem_from ||
3866 mem_from + mem_len <= lock_from;
3870 * Called when kernel memory is freed (or unmapped), or if a lock
3871 * is destroyed or reinitialized - this code checks whether there is
3872 * any held lock in the memory range of <from> to <to>:
3874 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3876 struct task_struct *curr = current;
3877 struct held_lock *hlock;
3878 unsigned long flags;
3881 if (unlikely(!debug_locks))
3884 local_irq_save(flags);
3885 for (i = 0; i < curr->lockdep_depth; i++) {
3886 hlock = curr->held_locks + i;
3888 if (not_in_range(mem_from, mem_len, hlock->instance,
3889 sizeof(*hlock->instance)))
3892 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3895 local_irq_restore(flags);
3897 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3899 static void print_held_locks_bug(struct task_struct *curr)
3901 if (!debug_locks_off())
3903 if (debug_locks_silent)
3907 printk("=====================================\n");
3908 printk("[ BUG: lock held at task exit time! ]\n");
3909 printk("-------------------------------------\n");
3910 printk("%s/%d is exiting with locks still held!\n",
3911 curr->comm, task_pid_nr(curr));
3912 lockdep_print_held_locks(curr);
3914 printk("\nstack backtrace:\n");
3918 void debug_check_no_locks_held(struct task_struct *task)
3920 if (unlikely(task->lockdep_depth > 0))
3921 print_held_locks_bug(task);
3924 void debug_show_all_locks(void)
3926 struct task_struct *g, *p;
3930 if (unlikely(!debug_locks)) {
3931 printk("INFO: lockdep is turned off.\n");
3934 printk("\nShowing all locks held in the system:\n");
3937 * Here we try to get the tasklist_lock as hard as possible,
3938 * if not successful after 2 seconds we ignore it (but keep
3939 * trying). This is to enable a debug printout even if a
3940 * tasklist_lock-holding task deadlocks or crashes.
3943 if (!read_trylock(&tasklist_lock)) {
3945 printk("hm, tasklist_lock locked, retrying... ");
3948 printk(" #%d", 10-count);
3952 printk(" ignoring it.\n");
3956 printk(KERN_CONT " locked it.\n");
3959 do_each_thread(g, p) {
3961 * It's not reliable to print a task's held locks
3962 * if it's not sleeping (or if it's not the current
3965 if (p->state == TASK_RUNNING && p != current)
3967 if (p->lockdep_depth)
3968 lockdep_print_held_locks(p);
3970 if (read_trylock(&tasklist_lock))
3972 } while_each_thread(g, p);
3975 printk("=============================================\n\n");
3978 read_unlock(&tasklist_lock);
3980 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3983 * Careful: only use this function if you are sure that
3984 * the task cannot run in parallel!
3986 void debug_show_held_locks(struct task_struct *task)
3988 if (unlikely(!debug_locks)) {
3989 printk("INFO: lockdep is turned off.\n");
3992 lockdep_print_held_locks(task);
3994 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3996 void lockdep_sys_exit(void)
3998 struct task_struct *curr = current;
4000 if (unlikely(curr->lockdep_depth)) {
4001 if (!debug_locks_off())
4004 printk("================================================\n");
4005 printk("[ BUG: lock held when returning to user space! ]\n");
4006 printk("------------------------------------------------\n");
4007 printk("%s/%d is leaving the kernel with locks still held!\n",
4008 curr->comm, curr->pid);
4009 lockdep_print_held_locks(curr);
4013 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4015 struct task_struct *curr = current;
4017 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4018 if (!debug_locks_off())
4020 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4021 /* Note: the following can be executed concurrently, so be careful. */
4023 printk("===============================\n");
4024 printk("[ INFO: suspicious RCU usage. ]\n");
4025 printk("-------------------------------\n");
4026 printk("%s:%d %s!\n", file, line, s);
4027 printk("\nother info that might help us debug this:\n\n");
4028 printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
4029 lockdep_print_held_locks(curr);
4030 printk("\nstack backtrace:\n");
4033 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);