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 cpu_clock(smp_processor_id());
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 void print_lock_name(struct lock_class *class)
495 char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
498 get_usage_chars(class, usage);
502 name = __get_key_name(class->key, str);
503 printk(" (%s", name);
505 printk(" (%s", name);
506 if (class->name_version > 1)
507 printk("#%d", class->name_version);
509 printk("/%d", class->subclass);
511 printk("){%s}", usage);
514 static void print_lockdep_cache(struct lockdep_map *lock)
517 char str[KSYM_NAME_LEN];
521 name = __get_key_name(lock->key->subkeys, str);
526 static void print_lock(struct held_lock *hlock)
528 print_lock_name(hlock_class(hlock));
530 print_ip_sym(hlock->acquire_ip);
533 static void lockdep_print_held_locks(struct task_struct *curr)
535 int i, depth = curr->lockdep_depth;
538 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
541 printk("%d lock%s held by %s/%d:\n",
542 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
544 for (i = 0; i < depth; i++) {
546 print_lock(curr->held_locks + i);
550 static void print_kernel_version(void)
552 printk("%s %.*s\n", init_utsname()->release,
553 (int)strcspn(init_utsname()->version, " "),
554 init_utsname()->version);
557 static int very_verbose(struct lock_class *class)
560 return class_filter(class);
566 * Is this the address of a static object:
568 static int static_obj(void *obj)
570 unsigned long start = (unsigned long) &_stext,
571 end = (unsigned long) &_end,
572 addr = (unsigned long) obj;
577 if ((addr >= start) && (addr < end))
580 if (arch_is_kernel_data(addr))
584 * in-kernel percpu var?
586 if (is_kernel_percpu_address(addr))
590 * module static or percpu var?
592 return is_module_address(addr) || is_module_percpu_address(addr);
596 * To make lock name printouts unique, we calculate a unique
597 * class->name_version generation counter:
599 static int count_matching_names(struct lock_class *new_class)
601 struct lock_class *class;
604 if (!new_class->name)
607 list_for_each_entry(class, &all_lock_classes, lock_entry) {
608 if (new_class->key - new_class->subclass == class->key)
609 return class->name_version;
610 if (class->name && !strcmp(class->name, new_class->name))
611 count = max(count, class->name_version);
618 * Register a lock's class in the hash-table, if the class is not present
619 * yet. Otherwise we look it up. We cache the result in the lock object
620 * itself, so actual lookup of the hash should be once per lock object.
622 static inline struct lock_class *
623 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
625 struct lockdep_subclass_key *key;
626 struct list_head *hash_head;
627 struct lock_class *class;
629 #ifdef CONFIG_DEBUG_LOCKDEP
631 * If the architecture calls into lockdep before initializing
632 * the hashes then we'll warn about it later. (we cannot printk
635 if (unlikely(!lockdep_initialized)) {
637 lockdep_init_error = 1;
638 save_stack_trace(&lockdep_init_trace);
643 * Static locks do not have their class-keys yet - for them the key
644 * is the lock object itself:
646 if (unlikely(!lock->key))
647 lock->key = (void *)lock;
650 * NOTE: the class-key must be unique. For dynamic locks, a static
651 * lock_class_key variable is passed in through the mutex_init()
652 * (or spin_lock_init()) call - which acts as the key. For static
653 * locks we use the lock object itself as the key.
655 BUILD_BUG_ON(sizeof(struct lock_class_key) >
656 sizeof(struct lockdep_map));
658 key = lock->key->subkeys + subclass;
660 hash_head = classhashentry(key);
663 * We can walk the hash lockfree, because the hash only
664 * grows, and we are careful when adding entries to the end:
666 list_for_each_entry(class, hash_head, hash_entry) {
667 if (class->key == key) {
668 WARN_ON_ONCE(class->name != lock->name);
677 * Register a lock's class in the hash-table, if the class is not present
678 * yet. Otherwise we look it up. We cache the result in the lock object
679 * itself, so actual lookup of the hash should be once per lock object.
681 static inline struct lock_class *
682 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
684 struct lockdep_subclass_key *key;
685 struct list_head *hash_head;
686 struct lock_class *class;
689 class = look_up_lock_class(lock, subclass);
694 * Debug-check: all keys must be persistent!
696 if (!static_obj(lock->key)) {
698 printk("INFO: trying to register non-static key.\n");
699 printk("the code is fine but needs lockdep annotation.\n");
700 printk("turning off the locking correctness validator.\n");
706 key = lock->key->subkeys + subclass;
707 hash_head = classhashentry(key);
709 raw_local_irq_save(flags);
711 raw_local_irq_restore(flags);
715 * We have to do the hash-walk again, to avoid races
718 list_for_each_entry(class, hash_head, hash_entry)
719 if (class->key == key)
722 * Allocate a new key from the static array, and add it to
725 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
726 if (!debug_locks_off_graph_unlock()) {
727 raw_local_irq_restore(flags);
730 raw_local_irq_restore(flags);
732 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
733 printk("turning off the locking correctness validator.\n");
737 class = lock_classes + nr_lock_classes++;
738 debug_atomic_inc(nr_unused_locks);
740 class->name = lock->name;
741 class->subclass = subclass;
742 INIT_LIST_HEAD(&class->lock_entry);
743 INIT_LIST_HEAD(&class->locks_before);
744 INIT_LIST_HEAD(&class->locks_after);
745 class->name_version = count_matching_names(class);
747 * We use RCU's safe list-add method to make
748 * parallel walking of the hash-list safe:
750 list_add_tail_rcu(&class->hash_entry, hash_head);
752 * Add it to the global list of classes:
754 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
756 if (verbose(class)) {
758 raw_local_irq_restore(flags);
760 printk("\nnew class %p: %s", class->key, class->name);
761 if (class->name_version > 1)
762 printk("#%d", class->name_version);
766 raw_local_irq_save(flags);
768 raw_local_irq_restore(flags);
774 raw_local_irq_restore(flags);
776 if (!subclass || force)
777 lock->class_cache = class;
779 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
785 #ifdef CONFIG_PROVE_LOCKING
787 * Allocate a lockdep entry. (assumes the graph_lock held, returns
788 * with NULL on failure)
790 static struct lock_list *alloc_list_entry(void)
792 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
793 if (!debug_locks_off_graph_unlock())
796 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
797 printk("turning off the locking correctness validator.\n");
801 return list_entries + nr_list_entries++;
805 * Add a new dependency to the head of the list:
807 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
808 struct list_head *head, unsigned long ip, int distance)
810 struct lock_list *entry;
812 * Lock not present yet - get a new dependency struct and
813 * add it to the list:
815 entry = alloc_list_entry();
819 if (!save_trace(&entry->trace))
823 entry->distance = distance;
825 * Since we never remove from the dependency list, the list can
826 * be walked lockless by other CPUs, it's only allocation
827 * that must be protected by the spinlock. But this also means
828 * we must make new entries visible only once writes to the
829 * entry become visible - hence the RCU op:
831 list_add_tail_rcu(&entry->entry, head);
837 * For good efficiency of modular, we use power of 2
839 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
840 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
843 * The circular_queue and helpers is used to implement the
844 * breadth-first search(BFS)algorithem, by which we can build
845 * the shortest path from the next lock to be acquired to the
846 * previous held lock if there is a circular between them.
848 struct circular_queue {
849 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
850 unsigned int front, rear;
853 static struct circular_queue lock_cq;
855 unsigned int max_bfs_queue_depth;
857 static unsigned int lockdep_dependency_gen_id;
859 static inline void __cq_init(struct circular_queue *cq)
861 cq->front = cq->rear = 0;
862 lockdep_dependency_gen_id++;
865 static inline int __cq_empty(struct circular_queue *cq)
867 return (cq->front == cq->rear);
870 static inline int __cq_full(struct circular_queue *cq)
872 return ((cq->rear + 1) & CQ_MASK) == cq->front;
875 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
880 cq->element[cq->rear] = elem;
881 cq->rear = (cq->rear + 1) & CQ_MASK;
885 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
890 *elem = cq->element[cq->front];
891 cq->front = (cq->front + 1) & CQ_MASK;
895 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
897 return (cq->rear - cq->front) & CQ_MASK;
900 static inline void mark_lock_accessed(struct lock_list *lock,
901 struct lock_list *parent)
905 nr = lock - list_entries;
906 WARN_ON(nr >= nr_list_entries);
907 lock->parent = parent;
908 lock->class->dep_gen_id = lockdep_dependency_gen_id;
911 static inline unsigned long lock_accessed(struct lock_list *lock)
915 nr = lock - list_entries;
916 WARN_ON(nr >= nr_list_entries);
917 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
920 static inline struct lock_list *get_lock_parent(struct lock_list *child)
922 return child->parent;
925 static inline int get_lock_depth(struct lock_list *child)
928 struct lock_list *parent;
930 while ((parent = get_lock_parent(child))) {
937 static int __bfs(struct lock_list *source_entry,
939 int (*match)(struct lock_list *entry, void *data),
940 struct lock_list **target_entry,
943 struct lock_list *entry;
944 struct list_head *head;
945 struct circular_queue *cq = &lock_cq;
948 if (match(source_entry, data)) {
949 *target_entry = source_entry;
955 head = &source_entry->class->locks_after;
957 head = &source_entry->class->locks_before;
959 if (list_empty(head))
963 __cq_enqueue(cq, (unsigned long)source_entry);
965 while (!__cq_empty(cq)) {
966 struct lock_list *lock;
968 __cq_dequeue(cq, (unsigned long *)&lock);
976 head = &lock->class->locks_after;
978 head = &lock->class->locks_before;
980 list_for_each_entry(entry, head, entry) {
981 if (!lock_accessed(entry)) {
982 unsigned int cq_depth;
983 mark_lock_accessed(entry, lock);
984 if (match(entry, data)) {
985 *target_entry = entry;
990 if (__cq_enqueue(cq, (unsigned long)entry)) {
994 cq_depth = __cq_get_elem_count(cq);
995 if (max_bfs_queue_depth < cq_depth)
996 max_bfs_queue_depth = cq_depth;
1004 static inline int __bfs_forwards(struct lock_list *src_entry,
1006 int (*match)(struct lock_list *entry, void *data),
1007 struct lock_list **target_entry)
1009 return __bfs(src_entry, data, match, target_entry, 1);
1013 static inline int __bfs_backwards(struct lock_list *src_entry,
1015 int (*match)(struct lock_list *entry, void *data),
1016 struct lock_list **target_entry)
1018 return __bfs(src_entry, data, match, target_entry, 0);
1023 * Recursive, forwards-direction lock-dependency checking, used for
1024 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1029 * Print a dependency chain entry (this is only done when a deadlock
1030 * has been detected):
1033 print_circular_bug_entry(struct lock_list *target, int depth)
1035 if (debug_locks_silent)
1037 printk("\n-> #%u", depth);
1038 print_lock_name(target->class);
1040 print_stack_trace(&target->trace, 6);
1046 * When a circular dependency is detected, print the
1050 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1051 struct held_lock *check_src,
1052 struct held_lock *check_tgt)
1054 struct task_struct *curr = current;
1056 if (debug_locks_silent)
1059 printk("\n=======================================================\n");
1060 printk( "[ INFO: possible circular locking dependency detected ]\n");
1061 print_kernel_version();
1062 printk( "-------------------------------------------------------\n");
1063 printk("%s/%d is trying to acquire lock:\n",
1064 curr->comm, task_pid_nr(curr));
1065 print_lock(check_src);
1066 printk("\nbut task is already holding lock:\n");
1067 print_lock(check_tgt);
1068 printk("\nwhich lock already depends on the new lock.\n\n");
1069 printk("\nthe existing dependency chain (in reverse order) is:\n");
1071 print_circular_bug_entry(entry, depth);
1076 static inline int class_equal(struct lock_list *entry, void *data)
1078 return entry->class == data;
1081 static noinline int print_circular_bug(struct lock_list *this,
1082 struct lock_list *target,
1083 struct held_lock *check_src,
1084 struct held_lock *check_tgt)
1086 struct task_struct *curr = current;
1087 struct lock_list *parent;
1090 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1093 if (!save_trace(&this->trace))
1096 depth = get_lock_depth(target);
1098 print_circular_bug_header(target, depth, check_src, check_tgt);
1100 parent = get_lock_parent(target);
1103 print_circular_bug_entry(parent, --depth);
1104 parent = get_lock_parent(parent);
1107 printk("\nother info that might help us debug this:\n\n");
1108 lockdep_print_held_locks(curr);
1110 printk("\nstack backtrace:\n");
1116 static noinline int print_bfs_bug(int ret)
1118 if (!debug_locks_off_graph_unlock())
1121 WARN(1, "lockdep bfs error:%d\n", ret);
1126 static int noop_count(struct lock_list *entry, void *data)
1128 (*(unsigned long *)data)++;
1132 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1134 unsigned long count = 0;
1135 struct lock_list *uninitialized_var(target_entry);
1137 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1141 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1143 unsigned long ret, flags;
1144 struct lock_list this;
1149 local_irq_save(flags);
1150 arch_spin_lock(&lockdep_lock);
1151 ret = __lockdep_count_forward_deps(&this);
1152 arch_spin_unlock(&lockdep_lock);
1153 local_irq_restore(flags);
1158 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1160 unsigned long count = 0;
1161 struct lock_list *uninitialized_var(target_entry);
1163 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1168 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1170 unsigned long ret, flags;
1171 struct lock_list this;
1176 local_irq_save(flags);
1177 arch_spin_lock(&lockdep_lock);
1178 ret = __lockdep_count_backward_deps(&this);
1179 arch_spin_unlock(&lockdep_lock);
1180 local_irq_restore(flags);
1186 * Prove that the dependency graph starting at <entry> can not
1187 * lead to <target>. Print an error and return 0 if it does.
1190 check_noncircular(struct lock_list *root, struct lock_class *target,
1191 struct lock_list **target_entry)
1195 debug_atomic_inc(nr_cyclic_checks);
1197 result = __bfs_forwards(root, target, class_equal, target_entry);
1202 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1204 * Forwards and backwards subgraph searching, for the purposes of
1205 * proving that two subgraphs can be connected by a new dependency
1206 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1209 static inline int usage_match(struct lock_list *entry, void *bit)
1211 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1217 * Find a node in the forwards-direction dependency sub-graph starting
1218 * at @root->class that matches @bit.
1220 * Return 0 if such a node exists in the subgraph, and put that node
1221 * into *@target_entry.
1223 * Return 1 otherwise and keep *@target_entry unchanged.
1224 * Return <0 on error.
1227 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1228 struct lock_list **target_entry)
1232 debug_atomic_inc(nr_find_usage_forwards_checks);
1234 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1240 * Find a node in the backwards-direction dependency sub-graph starting
1241 * at @root->class that matches @bit.
1243 * Return 0 if such a node exists in the subgraph, and put that node
1244 * into *@target_entry.
1246 * Return 1 otherwise and keep *@target_entry unchanged.
1247 * Return <0 on error.
1250 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1251 struct lock_list **target_entry)
1255 debug_atomic_inc(nr_find_usage_backwards_checks);
1257 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1262 static void print_lock_class_header(struct lock_class *class, int depth)
1266 printk("%*s->", depth, "");
1267 print_lock_name(class);
1268 printk(" ops: %lu", class->ops);
1271 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1272 if (class->usage_mask & (1 << bit)) {
1275 len += printk("%*s %s", depth, "", usage_str[bit]);
1276 len += printk(" at:\n");
1277 print_stack_trace(class->usage_traces + bit, len);
1280 printk("%*s }\n", depth, "");
1282 printk("%*s ... key at: ",depth,"");
1283 print_ip_sym((unsigned long)class->key);
1287 * printk the shortest lock dependencies from @start to @end in reverse order:
1290 print_shortest_lock_dependencies(struct lock_list *leaf,
1291 struct lock_list *root)
1293 struct lock_list *entry = leaf;
1296 /*compute depth from generated tree by BFS*/
1297 depth = get_lock_depth(leaf);
1300 print_lock_class_header(entry->class, depth);
1301 printk("%*s ... acquired at:\n", depth, "");
1302 print_stack_trace(&entry->trace, 2);
1305 if (depth == 0 && (entry != root)) {
1306 printk("lockdep:%s bad BFS generated tree\n", __func__);
1310 entry = get_lock_parent(entry);
1312 } while (entry && (depth >= 0));
1318 print_bad_irq_dependency(struct task_struct *curr,
1319 struct lock_list *prev_root,
1320 struct lock_list *next_root,
1321 struct lock_list *backwards_entry,
1322 struct lock_list *forwards_entry,
1323 struct held_lock *prev,
1324 struct held_lock *next,
1325 enum lock_usage_bit bit1,
1326 enum lock_usage_bit bit2,
1327 const char *irqclass)
1329 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1332 printk("\n======================================================\n");
1333 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1334 irqclass, irqclass);
1335 print_kernel_version();
1336 printk( "------------------------------------------------------\n");
1337 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1338 curr->comm, task_pid_nr(curr),
1339 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1340 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1341 curr->hardirqs_enabled,
1342 curr->softirqs_enabled);
1345 printk("\nand this task is already holding:\n");
1347 printk("which would create a new lock dependency:\n");
1348 print_lock_name(hlock_class(prev));
1350 print_lock_name(hlock_class(next));
1353 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1355 print_lock_name(backwards_entry->class);
1356 printk("\n... which became %s-irq-safe at:\n", irqclass);
1358 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1360 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1361 print_lock_name(forwards_entry->class);
1362 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1365 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1367 printk("\nother info that might help us debug this:\n\n");
1368 lockdep_print_held_locks(curr);
1370 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1371 printk(" and the holding lock:\n");
1372 if (!save_trace(&prev_root->trace))
1374 print_shortest_lock_dependencies(backwards_entry, prev_root);
1376 printk("\nthe dependencies between the lock to be acquired");
1377 printk(" and %s-irq-unsafe lock:\n", irqclass);
1378 if (!save_trace(&next_root->trace))
1380 print_shortest_lock_dependencies(forwards_entry, next_root);
1382 printk("\nstack backtrace:\n");
1389 check_usage(struct task_struct *curr, struct held_lock *prev,
1390 struct held_lock *next, enum lock_usage_bit bit_backwards,
1391 enum lock_usage_bit bit_forwards, const char *irqclass)
1394 struct lock_list this, that;
1395 struct lock_list *uninitialized_var(target_entry);
1396 struct lock_list *uninitialized_var(target_entry1);
1400 this.class = hlock_class(prev);
1401 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1403 return print_bfs_bug(ret);
1408 that.class = hlock_class(next);
1409 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1411 return print_bfs_bug(ret);
1415 return print_bad_irq_dependency(curr, &this, &that,
1416 target_entry, target_entry1,
1418 bit_backwards, bit_forwards, irqclass);
1421 static const char *state_names[] = {
1422 #define LOCKDEP_STATE(__STATE) \
1423 __stringify(__STATE),
1424 #include "lockdep_states.h"
1425 #undef LOCKDEP_STATE
1428 static const char *state_rnames[] = {
1429 #define LOCKDEP_STATE(__STATE) \
1430 __stringify(__STATE)"-READ",
1431 #include "lockdep_states.h"
1432 #undef LOCKDEP_STATE
1435 static inline const char *state_name(enum lock_usage_bit bit)
1437 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1440 static int exclusive_bit(int new_bit)
1448 * bit 0 - write/read
1449 * bit 1 - used_in/enabled
1453 int state = new_bit & ~3;
1454 int dir = new_bit & 2;
1457 * keep state, bit flip the direction and strip read.
1459 return state | (dir ^ 2);
1462 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1463 struct held_lock *next, enum lock_usage_bit bit)
1466 * Prove that the new dependency does not connect a hardirq-safe
1467 * lock with a hardirq-unsafe lock - to achieve this we search
1468 * the backwards-subgraph starting at <prev>, and the
1469 * forwards-subgraph starting at <next>:
1471 if (!check_usage(curr, prev, next, bit,
1472 exclusive_bit(bit), state_name(bit)))
1478 * Prove that the new dependency does not connect a hardirq-safe-read
1479 * lock with a hardirq-unsafe lock - to achieve this we search
1480 * the backwards-subgraph starting at <prev>, and the
1481 * forwards-subgraph starting at <next>:
1483 if (!check_usage(curr, prev, next, bit,
1484 exclusive_bit(bit), state_name(bit)))
1491 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1492 struct held_lock *next)
1494 #define LOCKDEP_STATE(__STATE) \
1495 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1497 #include "lockdep_states.h"
1498 #undef LOCKDEP_STATE
1503 static void inc_chains(void)
1505 if (current->hardirq_context)
1506 nr_hardirq_chains++;
1508 if (current->softirq_context)
1509 nr_softirq_chains++;
1511 nr_process_chains++;
1518 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1519 struct held_lock *next)
1524 static inline void inc_chains(void)
1526 nr_process_chains++;
1532 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1533 struct held_lock *next)
1535 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1538 printk("\n=============================================\n");
1539 printk( "[ INFO: possible recursive locking detected ]\n");
1540 print_kernel_version();
1541 printk( "---------------------------------------------\n");
1542 printk("%s/%d is trying to acquire lock:\n",
1543 curr->comm, task_pid_nr(curr));
1545 printk("\nbut task is already holding lock:\n");
1548 printk("\nother info that might help us debug this:\n");
1549 lockdep_print_held_locks(curr);
1551 printk("\nstack backtrace:\n");
1558 * Check whether we are holding such a class already.
1560 * (Note that this has to be done separately, because the graph cannot
1561 * detect such classes of deadlocks.)
1563 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1566 check_deadlock(struct task_struct *curr, struct held_lock *next,
1567 struct lockdep_map *next_instance, int read)
1569 struct held_lock *prev;
1570 struct held_lock *nest = NULL;
1573 for (i = 0; i < curr->lockdep_depth; i++) {
1574 prev = curr->held_locks + i;
1576 if (prev->instance == next->nest_lock)
1579 if (hlock_class(prev) != hlock_class(next))
1583 * Allow read-after-read recursion of the same
1584 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1586 if ((read == 2) && prev->read)
1590 * We're holding the nest_lock, which serializes this lock's
1591 * nesting behaviour.
1596 return print_deadlock_bug(curr, prev, next);
1602 * There was a chain-cache miss, and we are about to add a new dependency
1603 * to a previous lock. We recursively validate the following rules:
1605 * - would the adding of the <prev> -> <next> dependency create a
1606 * circular dependency in the graph? [== circular deadlock]
1608 * - does the new prev->next dependency connect any hardirq-safe lock
1609 * (in the full backwards-subgraph starting at <prev>) with any
1610 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1611 * <next>)? [== illegal lock inversion with hardirq contexts]
1613 * - does the new prev->next dependency connect any softirq-safe lock
1614 * (in the full backwards-subgraph starting at <prev>) with any
1615 * softirq-unsafe lock (in the full forwards-subgraph starting at
1616 * <next>)? [== illegal lock inversion with softirq contexts]
1618 * any of these scenarios could lead to a deadlock.
1620 * Then if all the validations pass, we add the forwards and backwards
1624 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1625 struct held_lock *next, int distance)
1627 struct lock_list *entry;
1629 struct lock_list this;
1630 struct lock_list *uninitialized_var(target_entry);
1633 * Prove that the new <prev> -> <next> dependency would not
1634 * create a circular dependency in the graph. (We do this by
1635 * forward-recursing into the graph starting at <next>, and
1636 * checking whether we can reach <prev>.)
1638 * We are using global variables to control the recursion, to
1639 * keep the stackframe size of the recursive functions low:
1641 this.class = hlock_class(next);
1643 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1645 return print_circular_bug(&this, target_entry, next, prev);
1646 else if (unlikely(ret < 0))
1647 return print_bfs_bug(ret);
1649 if (!check_prev_add_irq(curr, prev, next))
1653 * For recursive read-locks we do all the dependency checks,
1654 * but we dont store read-triggered dependencies (only
1655 * write-triggered dependencies). This ensures that only the
1656 * write-side dependencies matter, and that if for example a
1657 * write-lock never takes any other locks, then the reads are
1658 * equivalent to a NOP.
1660 if (next->read == 2 || prev->read == 2)
1663 * Is the <prev> -> <next> dependency already present?
1665 * (this may occur even though this is a new chain: consider
1666 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1667 * chains - the second one will be new, but L1 already has
1668 * L2 added to its dependency list, due to the first chain.)
1670 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1671 if (entry->class == hlock_class(next)) {
1673 entry->distance = 1;
1679 * Ok, all validations passed, add the new lock
1680 * to the previous lock's dependency list:
1682 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1683 &hlock_class(prev)->locks_after,
1684 next->acquire_ip, distance);
1689 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1690 &hlock_class(next)->locks_before,
1691 next->acquire_ip, distance);
1696 * Debugging printouts:
1698 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1700 printk("\n new dependency: ");
1701 print_lock_name(hlock_class(prev));
1703 print_lock_name(hlock_class(next));
1706 return graph_lock();
1712 * Add the dependency to all directly-previous locks that are 'relevant'.
1713 * The ones that are relevant are (in increasing distance from curr):
1714 * all consecutive trylock entries and the final non-trylock entry - or
1715 * the end of this context's lock-chain - whichever comes first.
1718 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1720 int depth = curr->lockdep_depth;
1721 struct held_lock *hlock;
1726 * Depth must not be zero for a non-head lock:
1731 * At least two relevant locks must exist for this
1734 if (curr->held_locks[depth].irq_context !=
1735 curr->held_locks[depth-1].irq_context)
1739 int distance = curr->lockdep_depth - depth + 1;
1740 hlock = curr->held_locks + depth-1;
1742 * Only non-recursive-read entries get new dependencies
1745 if (hlock->read != 2) {
1746 if (!check_prev_add(curr, hlock, next, distance))
1749 * Stop after the first non-trylock entry,
1750 * as non-trylock entries have added their
1751 * own direct dependencies already, so this
1752 * lock is connected to them indirectly:
1754 if (!hlock->trylock)
1759 * End of lock-stack?
1764 * Stop the search if we cross into another context:
1766 if (curr->held_locks[depth].irq_context !=
1767 curr->held_locks[depth-1].irq_context)
1772 if (!debug_locks_off_graph_unlock())
1780 unsigned long nr_lock_chains;
1781 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1782 int nr_chain_hlocks;
1783 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1785 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1787 return lock_classes + chain_hlocks[chain->base + i];
1791 * Look up a dependency chain. If the key is not present yet then
1792 * add it and return 1 - in this case the new dependency chain is
1793 * validated. If the key is already hashed, return 0.
1794 * (On return with 1 graph_lock is held.)
1796 static inline int lookup_chain_cache(struct task_struct *curr,
1797 struct held_lock *hlock,
1800 struct lock_class *class = hlock_class(hlock);
1801 struct list_head *hash_head = chainhashentry(chain_key);
1802 struct lock_chain *chain;
1803 struct held_lock *hlock_curr, *hlock_next;
1806 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1809 * We can walk it lock-free, because entries only get added
1812 list_for_each_entry(chain, hash_head, entry) {
1813 if (chain->chain_key == chain_key) {
1815 debug_atomic_inc(chain_lookup_hits);
1816 if (very_verbose(class))
1817 printk("\nhash chain already cached, key: "
1818 "%016Lx tail class: [%p] %s\n",
1819 (unsigned long long)chain_key,
1820 class->key, class->name);
1824 if (very_verbose(class))
1825 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1826 (unsigned long long)chain_key, class->key, class->name);
1828 * Allocate a new chain entry from the static array, and add
1834 * We have to walk the chain again locked - to avoid duplicates:
1836 list_for_each_entry(chain, hash_head, entry) {
1837 if (chain->chain_key == chain_key) {
1842 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1843 if (!debug_locks_off_graph_unlock())
1846 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1847 printk("turning off the locking correctness validator.\n");
1851 chain = lock_chains + nr_lock_chains++;
1852 chain->chain_key = chain_key;
1853 chain->irq_context = hlock->irq_context;
1854 /* Find the first held_lock of current chain */
1856 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1857 hlock_curr = curr->held_locks + i;
1858 if (hlock_curr->irq_context != hlock_next->irq_context)
1863 chain->depth = curr->lockdep_depth + 1 - i;
1864 cn = nr_chain_hlocks;
1865 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1866 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1871 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1873 for (j = 0; j < chain->depth - 1; j++, i++) {
1874 int lock_id = curr->held_locks[i].class_idx - 1;
1875 chain_hlocks[chain->base + j] = lock_id;
1877 chain_hlocks[chain->base + j] = class - lock_classes;
1879 list_add_tail_rcu(&chain->entry, hash_head);
1880 debug_atomic_inc(chain_lookup_misses);
1886 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1887 struct held_lock *hlock, int chain_head, u64 chain_key)
1890 * Trylock needs to maintain the stack of held locks, but it
1891 * does not add new dependencies, because trylock can be done
1894 * We look up the chain_key and do the O(N^2) check and update of
1895 * the dependencies only if this is a new dependency chain.
1896 * (If lookup_chain_cache() returns with 1 it acquires
1897 * graph_lock for us)
1899 if (!hlock->trylock && (hlock->check == 2) &&
1900 lookup_chain_cache(curr, hlock, chain_key)) {
1902 * Check whether last held lock:
1904 * - is irq-safe, if this lock is irq-unsafe
1905 * - is softirq-safe, if this lock is hardirq-unsafe
1907 * And check whether the new lock's dependency graph
1908 * could lead back to the previous lock.
1910 * any of these scenarios could lead to a deadlock. If
1913 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1918 * Mark recursive read, as we jump over it when
1919 * building dependencies (just like we jump over
1925 * Add dependency only if this lock is not the head
1926 * of the chain, and if it's not a secondary read-lock:
1928 if (!chain_head && ret != 2)
1929 if (!check_prevs_add(curr, hlock))
1933 /* after lookup_chain_cache(): */
1934 if (unlikely(!debug_locks))
1940 static inline int validate_chain(struct task_struct *curr,
1941 struct lockdep_map *lock, struct held_lock *hlock,
1942 int chain_head, u64 chain_key)
1949 * We are building curr_chain_key incrementally, so double-check
1950 * it from scratch, to make sure that it's done correctly:
1952 static void check_chain_key(struct task_struct *curr)
1954 #ifdef CONFIG_DEBUG_LOCKDEP
1955 struct held_lock *hlock, *prev_hlock = NULL;
1959 for (i = 0; i < curr->lockdep_depth; i++) {
1960 hlock = curr->held_locks + i;
1961 if (chain_key != hlock->prev_chain_key) {
1963 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1964 curr->lockdep_depth, i,
1965 (unsigned long long)chain_key,
1966 (unsigned long long)hlock->prev_chain_key);
1969 id = hlock->class_idx - 1;
1970 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1973 if (prev_hlock && (prev_hlock->irq_context !=
1974 hlock->irq_context))
1976 chain_key = iterate_chain_key(chain_key, id);
1979 if (chain_key != curr->curr_chain_key) {
1981 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1982 curr->lockdep_depth, i,
1983 (unsigned long long)chain_key,
1984 (unsigned long long)curr->curr_chain_key);
1990 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1991 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1993 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1996 printk("\n=================================\n");
1997 printk( "[ INFO: inconsistent lock state ]\n");
1998 print_kernel_version();
1999 printk( "---------------------------------\n");
2001 printk("inconsistent {%s} -> {%s} usage.\n",
2002 usage_str[prev_bit], usage_str[new_bit]);
2004 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2005 curr->comm, task_pid_nr(curr),
2006 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2007 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2008 trace_hardirqs_enabled(curr),
2009 trace_softirqs_enabled(curr));
2012 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2013 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2015 print_irqtrace_events(curr);
2016 printk("\nother info that might help us debug this:\n");
2017 lockdep_print_held_locks(curr);
2019 printk("\nstack backtrace:\n");
2026 * Print out an error if an invalid bit is set:
2029 valid_state(struct task_struct *curr, struct held_lock *this,
2030 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2032 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2033 return print_usage_bug(curr, this, bad_bit, new_bit);
2037 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2038 enum lock_usage_bit new_bit);
2040 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2043 * print irq inversion bug:
2046 print_irq_inversion_bug(struct task_struct *curr,
2047 struct lock_list *root, struct lock_list *other,
2048 struct held_lock *this, int forwards,
2049 const char *irqclass)
2051 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2054 printk("\n=========================================================\n");
2055 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
2056 print_kernel_version();
2057 printk( "---------------------------------------------------------\n");
2058 printk("%s/%d just changed the state of lock:\n",
2059 curr->comm, task_pid_nr(curr));
2062 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2064 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2065 print_lock_name(other->class);
2066 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2068 printk("\nother info that might help us debug this:\n");
2069 lockdep_print_held_locks(curr);
2071 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2072 if (!save_trace(&root->trace))
2074 print_shortest_lock_dependencies(other, root);
2076 printk("\nstack backtrace:\n");
2083 * Prove that in the forwards-direction subgraph starting at <this>
2084 * there is no lock matching <mask>:
2087 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2088 enum lock_usage_bit bit, const char *irqclass)
2091 struct lock_list root;
2092 struct lock_list *uninitialized_var(target_entry);
2095 root.class = hlock_class(this);
2096 ret = find_usage_forwards(&root, bit, &target_entry);
2098 return print_bfs_bug(ret);
2102 return print_irq_inversion_bug(curr, &root, target_entry,
2107 * Prove that in the backwards-direction subgraph starting at <this>
2108 * there is no lock matching <mask>:
2111 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2112 enum lock_usage_bit bit, const char *irqclass)
2115 struct lock_list root;
2116 struct lock_list *uninitialized_var(target_entry);
2119 root.class = hlock_class(this);
2120 ret = find_usage_backwards(&root, bit, &target_entry);
2122 return print_bfs_bug(ret);
2126 return print_irq_inversion_bug(curr, &root, target_entry,
2130 void print_irqtrace_events(struct task_struct *curr)
2132 printk("irq event stamp: %u\n", curr->irq_events);
2133 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2134 print_ip_sym(curr->hardirq_enable_ip);
2135 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2136 print_ip_sym(curr->hardirq_disable_ip);
2137 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2138 print_ip_sym(curr->softirq_enable_ip);
2139 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2140 print_ip_sym(curr->softirq_disable_ip);
2143 static int HARDIRQ_verbose(struct lock_class *class)
2146 return class_filter(class);
2151 static int SOFTIRQ_verbose(struct lock_class *class)
2154 return class_filter(class);
2159 static int RECLAIM_FS_verbose(struct lock_class *class)
2162 return class_filter(class);
2167 #define STRICT_READ_CHECKS 1
2169 static int (*state_verbose_f[])(struct lock_class *class) = {
2170 #define LOCKDEP_STATE(__STATE) \
2172 #include "lockdep_states.h"
2173 #undef LOCKDEP_STATE
2176 static inline int state_verbose(enum lock_usage_bit bit,
2177 struct lock_class *class)
2179 return state_verbose_f[bit >> 2](class);
2182 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2183 enum lock_usage_bit bit, const char *name);
2186 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2187 enum lock_usage_bit new_bit)
2189 int excl_bit = exclusive_bit(new_bit);
2190 int read = new_bit & 1;
2191 int dir = new_bit & 2;
2194 * mark USED_IN has to look forwards -- to ensure no dependency
2195 * has ENABLED state, which would allow recursion deadlocks.
2197 * mark ENABLED has to look backwards -- to ensure no dependee
2198 * has USED_IN state, which, again, would allow recursion deadlocks.
2200 check_usage_f usage = dir ?
2201 check_usage_backwards : check_usage_forwards;
2204 * Validate that this particular lock does not have conflicting
2207 if (!valid_state(curr, this, new_bit, excl_bit))
2211 * Validate that the lock dependencies don't have conflicting usage
2214 if ((!read || !dir || STRICT_READ_CHECKS) &&
2215 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2219 * Check for read in write conflicts
2222 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2225 if (STRICT_READ_CHECKS &&
2226 !usage(curr, this, excl_bit + 1,
2227 state_name(new_bit + 1)))
2231 if (state_verbose(new_bit, hlock_class(this)))
2238 #define LOCKDEP_STATE(__STATE) __STATE,
2239 #include "lockdep_states.h"
2240 #undef LOCKDEP_STATE
2244 * Mark all held locks with a usage bit:
2247 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2249 enum lock_usage_bit usage_bit;
2250 struct held_lock *hlock;
2253 for (i = 0; i < curr->lockdep_depth; i++) {
2254 hlock = curr->held_locks + i;
2256 usage_bit = 2 + (mark << 2); /* ENABLED */
2258 usage_bit += 1; /* READ */
2260 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2262 if (!mark_lock(curr, hlock, usage_bit))
2270 * Debugging helper: via this flag we know that we are in
2271 * 'early bootup code', and will warn about any invalid irqs-on event:
2273 static int early_boot_irqs_enabled;
2275 void early_boot_irqs_off(void)
2277 early_boot_irqs_enabled = 0;
2280 void early_boot_irqs_on(void)
2282 early_boot_irqs_enabled = 1;
2286 * Hardirqs will be enabled:
2288 void trace_hardirqs_on_caller(unsigned long ip)
2290 struct task_struct *curr = current;
2292 time_hardirqs_on(CALLER_ADDR0, ip);
2294 if (unlikely(!debug_locks || current->lockdep_recursion))
2297 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2300 if (unlikely(curr->hardirqs_enabled)) {
2301 debug_atomic_inc(redundant_hardirqs_on);
2304 /* we'll do an OFF -> ON transition: */
2305 curr->hardirqs_enabled = 1;
2307 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2309 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2312 * We are going to turn hardirqs on, so set the
2313 * usage bit for all held locks:
2315 if (!mark_held_locks(curr, HARDIRQ))
2318 * If we have softirqs enabled, then set the usage
2319 * bit for all held locks. (disabled hardirqs prevented
2320 * this bit from being set before)
2322 if (curr->softirqs_enabled)
2323 if (!mark_held_locks(curr, SOFTIRQ))
2326 curr->hardirq_enable_ip = ip;
2327 curr->hardirq_enable_event = ++curr->irq_events;
2328 debug_atomic_inc(hardirqs_on_events);
2330 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2332 void trace_hardirqs_on(void)
2334 trace_hardirqs_on_caller(CALLER_ADDR0);
2336 EXPORT_SYMBOL(trace_hardirqs_on);
2339 * Hardirqs were disabled:
2341 void trace_hardirqs_off_caller(unsigned long ip)
2343 struct task_struct *curr = current;
2345 time_hardirqs_off(CALLER_ADDR0, ip);
2347 if (unlikely(!debug_locks || current->lockdep_recursion))
2350 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2353 if (curr->hardirqs_enabled) {
2355 * We have done an ON -> OFF transition:
2357 curr->hardirqs_enabled = 0;
2358 curr->hardirq_disable_ip = ip;
2359 curr->hardirq_disable_event = ++curr->irq_events;
2360 debug_atomic_inc(hardirqs_off_events);
2362 debug_atomic_inc(redundant_hardirqs_off);
2364 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2366 void trace_hardirqs_off(void)
2368 trace_hardirqs_off_caller(CALLER_ADDR0);
2370 EXPORT_SYMBOL(trace_hardirqs_off);
2373 * Softirqs will be enabled:
2375 void trace_softirqs_on(unsigned long ip)
2377 struct task_struct *curr = current;
2379 if (unlikely(!debug_locks))
2382 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2385 if (curr->softirqs_enabled) {
2386 debug_atomic_inc(redundant_softirqs_on);
2391 * We'll do an OFF -> ON transition:
2393 curr->softirqs_enabled = 1;
2394 curr->softirq_enable_ip = ip;
2395 curr->softirq_enable_event = ++curr->irq_events;
2396 debug_atomic_inc(softirqs_on_events);
2398 * We are going to turn softirqs on, so set the
2399 * usage bit for all held locks, if hardirqs are
2402 if (curr->hardirqs_enabled)
2403 mark_held_locks(curr, SOFTIRQ);
2407 * Softirqs were disabled:
2409 void trace_softirqs_off(unsigned long ip)
2411 struct task_struct *curr = current;
2413 if (unlikely(!debug_locks))
2416 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2419 if (curr->softirqs_enabled) {
2421 * We have done an ON -> OFF transition:
2423 curr->softirqs_enabled = 0;
2424 curr->softirq_disable_ip = ip;
2425 curr->softirq_disable_event = ++curr->irq_events;
2426 debug_atomic_inc(softirqs_off_events);
2427 DEBUG_LOCKS_WARN_ON(!softirq_count());
2429 debug_atomic_inc(redundant_softirqs_off);
2432 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2434 struct task_struct *curr = current;
2436 if (unlikely(!debug_locks))
2439 /* no reclaim without waiting on it */
2440 if (!(gfp_mask & __GFP_WAIT))
2443 /* this guy won't enter reclaim */
2444 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2447 /* We're only interested __GFP_FS allocations for now */
2448 if (!(gfp_mask & __GFP_FS))
2451 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2454 mark_held_locks(curr, RECLAIM_FS);
2457 static void check_flags(unsigned long flags);
2459 void lockdep_trace_alloc(gfp_t gfp_mask)
2461 unsigned long flags;
2463 if (unlikely(current->lockdep_recursion))
2466 raw_local_irq_save(flags);
2468 current->lockdep_recursion = 1;
2469 __lockdep_trace_alloc(gfp_mask, flags);
2470 current->lockdep_recursion = 0;
2471 raw_local_irq_restore(flags);
2474 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2477 * If non-trylock use in a hardirq or softirq context, then
2478 * mark the lock as used in these contexts:
2480 if (!hlock->trylock) {
2482 if (curr->hardirq_context)
2483 if (!mark_lock(curr, hlock,
2484 LOCK_USED_IN_HARDIRQ_READ))
2486 if (curr->softirq_context)
2487 if (!mark_lock(curr, hlock,
2488 LOCK_USED_IN_SOFTIRQ_READ))
2491 if (curr->hardirq_context)
2492 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2494 if (curr->softirq_context)
2495 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2499 if (!hlock->hardirqs_off) {
2501 if (!mark_lock(curr, hlock,
2502 LOCK_ENABLED_HARDIRQ_READ))
2504 if (curr->softirqs_enabled)
2505 if (!mark_lock(curr, hlock,
2506 LOCK_ENABLED_SOFTIRQ_READ))
2509 if (!mark_lock(curr, hlock,
2510 LOCK_ENABLED_HARDIRQ))
2512 if (curr->softirqs_enabled)
2513 if (!mark_lock(curr, hlock,
2514 LOCK_ENABLED_SOFTIRQ))
2520 * We reuse the irq context infrastructure more broadly as a general
2521 * context checking code. This tests GFP_FS recursion (a lock taken
2522 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2525 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2527 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2530 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2538 static int separate_irq_context(struct task_struct *curr,
2539 struct held_lock *hlock)
2541 unsigned int depth = curr->lockdep_depth;
2544 * Keep track of points where we cross into an interrupt context:
2546 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2547 curr->softirq_context;
2549 struct held_lock *prev_hlock;
2551 prev_hlock = curr->held_locks + depth-1;
2553 * If we cross into another context, reset the
2554 * hash key (this also prevents the checking and the
2555 * adding of the dependency to 'prev'):
2557 if (prev_hlock->irq_context != hlock->irq_context)
2566 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2567 enum lock_usage_bit new_bit)
2573 static inline int mark_irqflags(struct task_struct *curr,
2574 struct held_lock *hlock)
2579 static inline int separate_irq_context(struct task_struct *curr,
2580 struct held_lock *hlock)
2585 void lockdep_trace_alloc(gfp_t gfp_mask)
2592 * Mark a lock with a usage bit, and validate the state transition:
2594 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2595 enum lock_usage_bit new_bit)
2597 unsigned int new_mask = 1 << new_bit, ret = 1;
2600 * If already set then do not dirty the cacheline,
2601 * nor do any checks:
2603 if (likely(hlock_class(this)->usage_mask & new_mask))
2609 * Make sure we didnt race:
2611 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2616 hlock_class(this)->usage_mask |= new_mask;
2618 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2622 #define LOCKDEP_STATE(__STATE) \
2623 case LOCK_USED_IN_##__STATE: \
2624 case LOCK_USED_IN_##__STATE##_READ: \
2625 case LOCK_ENABLED_##__STATE: \
2626 case LOCK_ENABLED_##__STATE##_READ:
2627 #include "lockdep_states.h"
2628 #undef LOCKDEP_STATE
2629 ret = mark_lock_irq(curr, this, new_bit);
2634 debug_atomic_dec(nr_unused_locks);
2637 if (!debug_locks_off_graph_unlock())
2646 * We must printk outside of the graph_lock:
2649 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2651 print_irqtrace_events(curr);
2659 * Initialize a lock instance's lock-class mapping info:
2661 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2662 struct lock_class_key *key, int subclass)
2664 lock->class_cache = NULL;
2665 #ifdef CONFIG_LOCK_STAT
2666 lock->cpu = raw_smp_processor_id();
2669 if (DEBUG_LOCKS_WARN_ON(!name)) {
2670 lock->name = "NULL";
2676 if (DEBUG_LOCKS_WARN_ON(!key))
2679 * Sanity check, the lock-class key must be persistent:
2681 if (!static_obj(key)) {
2682 printk("BUG: key %p not in .data!\n", key);
2683 DEBUG_LOCKS_WARN_ON(1);
2688 if (unlikely(!debug_locks))
2692 register_lock_class(lock, subclass, 1);
2694 EXPORT_SYMBOL_GPL(lockdep_init_map);
2697 * This gets called for every mutex_lock*()/spin_lock*() operation.
2698 * We maintain the dependency maps and validate the locking attempt:
2700 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2701 int trylock, int read, int check, int hardirqs_off,
2702 struct lockdep_map *nest_lock, unsigned long ip,
2705 struct task_struct *curr = current;
2706 struct lock_class *class = NULL;
2707 struct held_lock *hlock;
2708 unsigned int depth, id;
2716 if (unlikely(!debug_locks))
2719 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2722 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2724 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2725 printk("turning off the locking correctness validator.\n");
2731 class = lock->class_cache;
2733 * Not cached yet or subclass?
2735 if (unlikely(!class)) {
2736 class = register_lock_class(lock, subclass, 0);
2740 atomic_inc((atomic_t *)&class->ops);
2741 if (very_verbose(class)) {
2742 printk("\nacquire class [%p] %s", class->key, class->name);
2743 if (class->name_version > 1)
2744 printk("#%d", class->name_version);
2750 * Add the lock to the list of currently held locks.
2751 * (we dont increase the depth just yet, up until the
2752 * dependency checks are done)
2754 depth = curr->lockdep_depth;
2755 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2758 class_idx = class - lock_classes + 1;
2761 hlock = curr->held_locks + depth - 1;
2762 if (hlock->class_idx == class_idx && nest_lock) {
2763 if (hlock->references)
2764 hlock->references++;
2766 hlock->references = 2;
2772 hlock = curr->held_locks + depth;
2773 if (DEBUG_LOCKS_WARN_ON(!class))
2775 hlock->class_idx = class_idx;
2776 hlock->acquire_ip = ip;
2777 hlock->instance = lock;
2778 hlock->nest_lock = nest_lock;
2779 hlock->trylock = trylock;
2781 hlock->check = check;
2782 hlock->hardirqs_off = !!hardirqs_off;
2783 hlock->references = references;
2784 #ifdef CONFIG_LOCK_STAT
2785 hlock->waittime_stamp = 0;
2786 hlock->holdtime_stamp = lockstat_clock();
2789 if (check == 2 && !mark_irqflags(curr, hlock))
2792 /* mark it as used: */
2793 if (!mark_lock(curr, hlock, LOCK_USED))
2797 * Calculate the chain hash: it's the combined hash of all the
2798 * lock keys along the dependency chain. We save the hash value
2799 * at every step so that we can get the current hash easily
2800 * after unlock. The chain hash is then used to cache dependency
2803 * The 'key ID' is what is the most compact key value to drive
2804 * the hash, not class->key.
2806 id = class - lock_classes;
2807 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2810 chain_key = curr->curr_chain_key;
2812 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2817 hlock->prev_chain_key = chain_key;
2818 if (separate_irq_context(curr, hlock)) {
2822 chain_key = iterate_chain_key(chain_key, id);
2824 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2827 curr->curr_chain_key = chain_key;
2828 curr->lockdep_depth++;
2829 check_chain_key(curr);
2830 #ifdef CONFIG_DEBUG_LOCKDEP
2831 if (unlikely(!debug_locks))
2834 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2836 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2837 printk("turning off the locking correctness validator.\n");
2842 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2843 max_lockdep_depth = curr->lockdep_depth;
2849 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2852 if (!debug_locks_off())
2854 if (debug_locks_silent)
2857 printk("\n=====================================\n");
2858 printk( "[ BUG: bad unlock balance detected! ]\n");
2859 printk( "-------------------------------------\n");
2860 printk("%s/%d is trying to release lock (",
2861 curr->comm, task_pid_nr(curr));
2862 print_lockdep_cache(lock);
2865 printk("but there are no more locks to release!\n");
2866 printk("\nother info that might help us debug this:\n");
2867 lockdep_print_held_locks(curr);
2869 printk("\nstack backtrace:\n");
2876 * Common debugging checks for both nested and non-nested unlock:
2878 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2881 if (unlikely(!debug_locks))
2883 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2886 if (curr->lockdep_depth <= 0)
2887 return print_unlock_inbalance_bug(curr, lock, ip);
2892 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
2894 if (hlock->instance == lock)
2897 if (hlock->references) {
2898 struct lock_class *class = lock->class_cache;
2901 class = look_up_lock_class(lock, 0);
2903 if (DEBUG_LOCKS_WARN_ON(!class))
2906 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
2909 if (hlock->class_idx == class - lock_classes + 1)
2917 __lock_set_class(struct lockdep_map *lock, const char *name,
2918 struct lock_class_key *key, unsigned int subclass,
2921 struct task_struct *curr = current;
2922 struct held_lock *hlock, *prev_hlock;
2923 struct lock_class *class;
2927 depth = curr->lockdep_depth;
2928 if (DEBUG_LOCKS_WARN_ON(!depth))
2932 for (i = depth-1; i >= 0; i--) {
2933 hlock = curr->held_locks + i;
2935 * We must not cross into another context:
2937 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2939 if (match_held_lock(hlock, lock))
2943 return print_unlock_inbalance_bug(curr, lock, ip);
2946 lockdep_init_map(lock, name, key, 0);
2947 class = register_lock_class(lock, subclass, 0);
2948 hlock->class_idx = class - lock_classes + 1;
2950 curr->lockdep_depth = i;
2951 curr->curr_chain_key = hlock->prev_chain_key;
2953 for (; i < depth; i++) {
2954 hlock = curr->held_locks + i;
2955 if (!__lock_acquire(hlock->instance,
2956 hlock_class(hlock)->subclass, hlock->trylock,
2957 hlock->read, hlock->check, hlock->hardirqs_off,
2958 hlock->nest_lock, hlock->acquire_ip,
2963 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2969 * Remove the lock to the list of currently held locks in a
2970 * potentially non-nested (out of order) manner. This is a
2971 * relatively rare operation, as all the unlock APIs default
2972 * to nested mode (which uses lock_release()):
2975 lock_release_non_nested(struct task_struct *curr,
2976 struct lockdep_map *lock, unsigned long ip)
2978 struct held_lock *hlock, *prev_hlock;
2983 * Check whether the lock exists in the current stack
2986 depth = curr->lockdep_depth;
2987 if (DEBUG_LOCKS_WARN_ON(!depth))
2991 for (i = depth-1; i >= 0; i--) {
2992 hlock = curr->held_locks + i;
2994 * We must not cross into another context:
2996 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2998 if (match_held_lock(hlock, lock))
3002 return print_unlock_inbalance_bug(curr, lock, ip);
3005 if (hlock->instance == lock)
3006 lock_release_holdtime(hlock);
3008 if (hlock->references) {
3009 hlock->references--;
3010 if (hlock->references) {
3012 * We had, and after removing one, still have
3013 * references, the current lock stack is still
3014 * valid. We're done!
3021 * We have the right lock to unlock, 'hlock' points to it.
3022 * Now we remove it from the stack, and add back the other
3023 * entries (if any), recalculating the hash along the way:
3026 curr->lockdep_depth = i;
3027 curr->curr_chain_key = hlock->prev_chain_key;
3029 for (i++; i < depth; i++) {
3030 hlock = curr->held_locks + i;
3031 if (!__lock_acquire(hlock->instance,
3032 hlock_class(hlock)->subclass, hlock->trylock,
3033 hlock->read, hlock->check, hlock->hardirqs_off,
3034 hlock->nest_lock, hlock->acquire_ip,
3039 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3045 * Remove the lock to the list of currently held locks - this gets
3046 * called on mutex_unlock()/spin_unlock*() (or on a failed
3047 * mutex_lock_interruptible()). This is done for unlocks that nest
3048 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3050 static int lock_release_nested(struct task_struct *curr,
3051 struct lockdep_map *lock, unsigned long ip)
3053 struct held_lock *hlock;
3057 * Pop off the top of the lock stack:
3059 depth = curr->lockdep_depth - 1;
3060 hlock = curr->held_locks + depth;
3063 * Is the unlock non-nested:
3065 if (hlock->instance != lock || hlock->references)
3066 return lock_release_non_nested(curr, lock, ip);
3067 curr->lockdep_depth--;
3069 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3072 curr->curr_chain_key = hlock->prev_chain_key;
3074 lock_release_holdtime(hlock);
3076 #ifdef CONFIG_DEBUG_LOCKDEP
3077 hlock->prev_chain_key = 0;
3078 hlock->class_idx = 0;
3079 hlock->acquire_ip = 0;
3080 hlock->irq_context = 0;
3086 * Remove the lock to the list of currently held locks - this gets
3087 * called on mutex_unlock()/spin_unlock*() (or on a failed
3088 * mutex_lock_interruptible()). This is done for unlocks that nest
3089 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3092 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3094 struct task_struct *curr = current;
3096 if (!check_unlock(curr, lock, ip))
3100 if (!lock_release_nested(curr, lock, ip))
3103 if (!lock_release_non_nested(curr, lock, ip))
3107 check_chain_key(curr);
3110 static int __lock_is_held(struct lockdep_map *lock)
3112 struct task_struct *curr = current;
3115 for (i = 0; i < curr->lockdep_depth; i++) {
3116 struct held_lock *hlock = curr->held_locks + i;
3118 if (match_held_lock(hlock, lock))
3126 * Check whether we follow the irq-flags state precisely:
3128 static void check_flags(unsigned long flags)
3130 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3131 defined(CONFIG_TRACE_IRQFLAGS)
3135 if (irqs_disabled_flags(flags)) {
3136 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3137 printk("possible reason: unannotated irqs-off.\n");
3140 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3141 printk("possible reason: unannotated irqs-on.\n");
3146 * We dont accurately track softirq state in e.g.
3147 * hardirq contexts (such as on 4KSTACKS), so only
3148 * check if not in hardirq contexts:
3150 if (!hardirq_count()) {
3151 if (softirq_count())
3152 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3154 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3158 print_irqtrace_events(current);
3162 void lock_set_class(struct lockdep_map *lock, const char *name,
3163 struct lock_class_key *key, unsigned int subclass,
3166 unsigned long flags;
3168 if (unlikely(current->lockdep_recursion))
3171 raw_local_irq_save(flags);
3172 current->lockdep_recursion = 1;
3174 if (__lock_set_class(lock, name, key, subclass, ip))
3175 check_chain_key(current);
3176 current->lockdep_recursion = 0;
3177 raw_local_irq_restore(flags);
3179 EXPORT_SYMBOL_GPL(lock_set_class);
3182 * We are not always called with irqs disabled - do that here,
3183 * and also avoid lockdep recursion:
3185 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3186 int trylock, int read, int check,
3187 struct lockdep_map *nest_lock, unsigned long ip)
3189 unsigned long flags;
3191 if (unlikely(current->lockdep_recursion))
3194 raw_local_irq_save(flags);
3197 current->lockdep_recursion = 1;
3198 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3199 __lock_acquire(lock, subclass, trylock, read, check,
3200 irqs_disabled_flags(flags), nest_lock, ip, 0);
3201 current->lockdep_recursion = 0;
3202 raw_local_irq_restore(flags);
3204 EXPORT_SYMBOL_GPL(lock_acquire);
3206 void lock_release(struct lockdep_map *lock, int nested,
3209 unsigned long flags;
3211 if (unlikely(current->lockdep_recursion))
3214 raw_local_irq_save(flags);
3216 current->lockdep_recursion = 1;
3217 trace_lock_release(lock, nested, ip);
3218 __lock_release(lock, nested, ip);
3219 current->lockdep_recursion = 0;
3220 raw_local_irq_restore(flags);
3222 EXPORT_SYMBOL_GPL(lock_release);
3224 int lock_is_held(struct lockdep_map *lock)
3226 unsigned long flags;
3229 if (unlikely(current->lockdep_recursion))
3232 raw_local_irq_save(flags);
3235 current->lockdep_recursion = 1;
3236 ret = __lock_is_held(lock);
3237 current->lockdep_recursion = 0;
3238 raw_local_irq_restore(flags);
3242 EXPORT_SYMBOL_GPL(lock_is_held);
3244 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3246 current->lockdep_reclaim_gfp = gfp_mask;
3249 void lockdep_clear_current_reclaim_state(void)
3251 current->lockdep_reclaim_gfp = 0;
3254 #ifdef CONFIG_LOCK_STAT
3256 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3259 if (!debug_locks_off())
3261 if (debug_locks_silent)
3264 printk("\n=================================\n");
3265 printk( "[ BUG: bad contention detected! ]\n");
3266 printk( "---------------------------------\n");
3267 printk("%s/%d is trying to contend lock (",
3268 curr->comm, task_pid_nr(curr));
3269 print_lockdep_cache(lock);
3272 printk("but there are no locks held!\n");
3273 printk("\nother info that might help us debug this:\n");
3274 lockdep_print_held_locks(curr);
3276 printk("\nstack backtrace:\n");
3283 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3285 struct task_struct *curr = current;
3286 struct held_lock *hlock, *prev_hlock;
3287 struct lock_class_stats *stats;
3289 int i, contention_point, contending_point;
3291 depth = curr->lockdep_depth;
3292 if (DEBUG_LOCKS_WARN_ON(!depth))
3296 for (i = depth-1; i >= 0; i--) {
3297 hlock = curr->held_locks + i;
3299 * We must not cross into another context:
3301 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3303 if (match_held_lock(hlock, lock))
3307 print_lock_contention_bug(curr, lock, ip);
3311 if (hlock->instance != lock)
3314 hlock->waittime_stamp = lockstat_clock();
3316 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3317 contending_point = lock_point(hlock_class(hlock)->contending_point,
3320 stats = get_lock_stats(hlock_class(hlock));
3321 if (contention_point < LOCKSTAT_POINTS)
3322 stats->contention_point[contention_point]++;
3323 if (contending_point < LOCKSTAT_POINTS)
3324 stats->contending_point[contending_point]++;
3325 if (lock->cpu != smp_processor_id())
3326 stats->bounces[bounce_contended + !!hlock->read]++;
3327 put_lock_stats(stats);
3331 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3333 struct task_struct *curr = current;
3334 struct held_lock *hlock, *prev_hlock;
3335 struct lock_class_stats *stats;
3337 u64 now, waittime = 0;
3340 depth = curr->lockdep_depth;
3341 if (DEBUG_LOCKS_WARN_ON(!depth))
3345 for (i = depth-1; i >= 0; i--) {
3346 hlock = curr->held_locks + i;
3348 * We must not cross into another context:
3350 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3352 if (match_held_lock(hlock, lock))
3356 print_lock_contention_bug(curr, lock, _RET_IP_);
3360 if (hlock->instance != lock)
3363 cpu = smp_processor_id();
3364 if (hlock->waittime_stamp) {
3365 now = lockstat_clock();
3366 waittime = now - hlock->waittime_stamp;
3367 hlock->holdtime_stamp = now;
3370 trace_lock_acquired(lock, ip, waittime);
3372 stats = get_lock_stats(hlock_class(hlock));
3375 lock_time_inc(&stats->read_waittime, waittime);
3377 lock_time_inc(&stats->write_waittime, waittime);
3379 if (lock->cpu != cpu)
3380 stats->bounces[bounce_acquired + !!hlock->read]++;
3381 put_lock_stats(stats);
3387 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3389 unsigned long flags;
3391 if (unlikely(!lock_stat))
3394 if (unlikely(current->lockdep_recursion))
3397 raw_local_irq_save(flags);
3399 current->lockdep_recursion = 1;
3400 trace_lock_contended(lock, ip);
3401 __lock_contended(lock, ip);
3402 current->lockdep_recursion = 0;
3403 raw_local_irq_restore(flags);
3405 EXPORT_SYMBOL_GPL(lock_contended);
3407 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3409 unsigned long flags;
3411 if (unlikely(!lock_stat))
3414 if (unlikely(current->lockdep_recursion))
3417 raw_local_irq_save(flags);
3419 current->lockdep_recursion = 1;
3420 __lock_acquired(lock, ip);
3421 current->lockdep_recursion = 0;
3422 raw_local_irq_restore(flags);
3424 EXPORT_SYMBOL_GPL(lock_acquired);
3428 * Used by the testsuite, sanitize the validator state
3429 * after a simulated failure:
3432 void lockdep_reset(void)
3434 unsigned long flags;
3437 raw_local_irq_save(flags);
3438 current->curr_chain_key = 0;
3439 current->lockdep_depth = 0;
3440 current->lockdep_recursion = 0;
3441 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3442 nr_hardirq_chains = 0;
3443 nr_softirq_chains = 0;
3444 nr_process_chains = 0;
3446 for (i = 0; i < CHAINHASH_SIZE; i++)
3447 INIT_LIST_HEAD(chainhash_table + i);
3448 raw_local_irq_restore(flags);
3451 static void zap_class(struct lock_class *class)
3456 * Remove all dependencies this lock is
3459 for (i = 0; i < nr_list_entries; i++) {
3460 if (list_entries[i].class == class)
3461 list_del_rcu(&list_entries[i].entry);
3464 * Unhash the class and remove it from the all_lock_classes list:
3466 list_del_rcu(&class->hash_entry);
3467 list_del_rcu(&class->lock_entry);
3472 static inline int within(const void *addr, void *start, unsigned long size)
3474 return addr >= start && addr < start + size;
3477 void lockdep_free_key_range(void *start, unsigned long size)
3479 struct lock_class *class, *next;
3480 struct list_head *head;
3481 unsigned long flags;
3485 raw_local_irq_save(flags);
3486 locked = graph_lock();
3489 * Unhash all classes that were created by this module:
3491 for (i = 0; i < CLASSHASH_SIZE; i++) {
3492 head = classhash_table + i;
3493 if (list_empty(head))
3495 list_for_each_entry_safe(class, next, head, hash_entry) {
3496 if (within(class->key, start, size))
3498 else if (within(class->name, start, size))
3505 raw_local_irq_restore(flags);
3508 void lockdep_reset_lock(struct lockdep_map *lock)
3510 struct lock_class *class, *next;
3511 struct list_head *head;
3512 unsigned long flags;
3516 raw_local_irq_save(flags);
3519 * Remove all classes this lock might have:
3521 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3523 * If the class exists we look it up and zap it:
3525 class = look_up_lock_class(lock, j);
3530 * Debug check: in the end all mapped classes should
3533 locked = graph_lock();
3534 for (i = 0; i < CLASSHASH_SIZE; i++) {
3535 head = classhash_table + i;
3536 if (list_empty(head))
3538 list_for_each_entry_safe(class, next, head, hash_entry) {
3539 if (unlikely(class == lock->class_cache)) {
3540 if (debug_locks_off_graph_unlock())
3550 raw_local_irq_restore(flags);
3553 void lockdep_init(void)
3558 * Some architectures have their own start_kernel()
3559 * code which calls lockdep_init(), while we also
3560 * call lockdep_init() from the start_kernel() itself,
3561 * and we want to initialize the hashes only once:
3563 if (lockdep_initialized)
3566 for (i = 0; i < CLASSHASH_SIZE; i++)
3567 INIT_LIST_HEAD(classhash_table + i);
3569 for (i = 0; i < CHAINHASH_SIZE; i++)
3570 INIT_LIST_HEAD(chainhash_table + i);
3572 lockdep_initialized = 1;
3575 void __init lockdep_info(void)
3577 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3579 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3580 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3581 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3582 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3583 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3584 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3585 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3587 printk(" memory used by lock dependency info: %lu kB\n",
3588 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3589 sizeof(struct list_head) * CLASSHASH_SIZE +
3590 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3591 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3592 sizeof(struct list_head) * CHAINHASH_SIZE
3593 #ifdef CONFIG_PROVE_LOCKING
3594 + sizeof(struct circular_queue)
3599 printk(" per task-struct memory footprint: %lu bytes\n",
3600 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3602 #ifdef CONFIG_DEBUG_LOCKDEP
3603 if (lockdep_init_error) {
3604 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3605 printk("Call stack leading to lockdep invocation was:\n");
3606 print_stack_trace(&lockdep_init_trace, 0);
3612 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3613 const void *mem_to, struct held_lock *hlock)
3615 if (!debug_locks_off())
3617 if (debug_locks_silent)
3620 printk("\n=========================\n");
3621 printk( "[ BUG: held lock freed! ]\n");
3622 printk( "-------------------------\n");
3623 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3624 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3626 lockdep_print_held_locks(curr);
3628 printk("\nstack backtrace:\n");
3632 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3633 const void* lock_from, unsigned long lock_len)
3635 return lock_from + lock_len <= mem_from ||
3636 mem_from + mem_len <= lock_from;
3640 * Called when kernel memory is freed (or unmapped), or if a lock
3641 * is destroyed or reinitialized - this code checks whether there is
3642 * any held lock in the memory range of <from> to <to>:
3644 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3646 struct task_struct *curr = current;
3647 struct held_lock *hlock;
3648 unsigned long flags;
3651 if (unlikely(!debug_locks))
3654 local_irq_save(flags);
3655 for (i = 0; i < curr->lockdep_depth; i++) {
3656 hlock = curr->held_locks + i;
3658 if (not_in_range(mem_from, mem_len, hlock->instance,
3659 sizeof(*hlock->instance)))
3662 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3665 local_irq_restore(flags);
3667 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3669 static void print_held_locks_bug(struct task_struct *curr)
3671 if (!debug_locks_off())
3673 if (debug_locks_silent)
3676 printk("\n=====================================\n");
3677 printk( "[ BUG: lock held at task exit time! ]\n");
3678 printk( "-------------------------------------\n");
3679 printk("%s/%d is exiting with locks still held!\n",
3680 curr->comm, task_pid_nr(curr));
3681 lockdep_print_held_locks(curr);
3683 printk("\nstack backtrace:\n");
3687 void debug_check_no_locks_held(struct task_struct *task)
3689 if (unlikely(task->lockdep_depth > 0))
3690 print_held_locks_bug(task);
3693 void debug_show_all_locks(void)
3695 struct task_struct *g, *p;
3699 if (unlikely(!debug_locks)) {
3700 printk("INFO: lockdep is turned off.\n");
3703 printk("\nShowing all locks held in the system:\n");
3706 * Here we try to get the tasklist_lock as hard as possible,
3707 * if not successful after 2 seconds we ignore it (but keep
3708 * trying). This is to enable a debug printout even if a
3709 * tasklist_lock-holding task deadlocks or crashes.
3712 if (!read_trylock(&tasklist_lock)) {
3714 printk("hm, tasklist_lock locked, retrying... ");
3717 printk(" #%d", 10-count);
3721 printk(" ignoring it.\n");
3725 printk(KERN_CONT " locked it.\n");
3728 do_each_thread(g, p) {
3730 * It's not reliable to print a task's held locks
3731 * if it's not sleeping (or if it's not the current
3734 if (p->state == TASK_RUNNING && p != current)
3736 if (p->lockdep_depth)
3737 lockdep_print_held_locks(p);
3739 if (read_trylock(&tasklist_lock))
3741 } while_each_thread(g, p);
3744 printk("=============================================\n\n");
3747 read_unlock(&tasklist_lock);
3749 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3752 * Careful: only use this function if you are sure that
3753 * the task cannot run in parallel!
3755 void __debug_show_held_locks(struct task_struct *task)
3757 if (unlikely(!debug_locks)) {
3758 printk("INFO: lockdep is turned off.\n");
3761 lockdep_print_held_locks(task);
3763 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3765 void debug_show_held_locks(struct task_struct *task)
3767 __debug_show_held_locks(task);
3769 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3771 void lockdep_sys_exit(void)
3773 struct task_struct *curr = current;
3775 if (unlikely(curr->lockdep_depth)) {
3776 if (!debug_locks_off())
3778 printk("\n================================================\n");
3779 printk( "[ BUG: lock held when returning to user space! ]\n");
3780 printk( "------------------------------------------------\n");
3781 printk("%s/%d is leaving the kernel with locks still held!\n",
3782 curr->comm, curr->pid);
3783 lockdep_print_held_locks(curr);
3787 void lockdep_rcu_dereference(const char *file, const int line)
3789 struct task_struct *curr = current;
3791 if (!debug_locks_off())
3793 printk("\n===================================================\n");
3794 printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3795 printk( "---------------------------------------------------\n");
3796 printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3798 printk("\nother info that might help us debug this:\n\n");
3799 printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
3800 lockdep_print_held_locks(curr);
3801 printk("\nstack backtrace:\n");
3804 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);