4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
47 #include <asm/sections.h>
49 #include "lockdep_internals.h"
51 #define CREATE_TRACE_POINTS
52 #include <trace/events/lock.h>
54 #ifdef CONFIG_PROVE_LOCKING
55 int prove_locking = 1;
56 module_param(prove_locking, int, 0644);
58 #define prove_locking 0
61 #ifdef CONFIG_LOCK_STAT
63 module_param(lock_stat, int, 0644);
69 * lockdep_lock: protects the lockdep graph, the hashes and the
70 * class/list/hash allocators.
72 * This is one of the rare exceptions where it's justified
73 * to use a raw spinlock - we really dont want the spinlock
74 * code to recurse back into the lockdep code...
76 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
78 static int graph_lock(void)
80 arch_spin_lock(&lockdep_lock);
82 * Make sure that if another CPU detected a bug while
83 * walking the graph we dont change it (while the other
84 * CPU is busy printing out stuff with the graph lock
88 arch_spin_unlock(&lockdep_lock);
91 /* prevent any recursions within lockdep from causing deadlocks */
92 current->lockdep_recursion++;
96 static inline int graph_unlock(void)
98 if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
99 return DEBUG_LOCKS_WARN_ON(1);
101 current->lockdep_recursion--;
102 arch_spin_unlock(&lockdep_lock);
107 * Turn lock debugging off and return with 0 if it was off already,
108 * and also release the graph lock:
110 static inline int debug_locks_off_graph_unlock(void)
112 int ret = debug_locks_off();
114 arch_spin_unlock(&lockdep_lock);
119 static int lockdep_initialized;
121 unsigned long nr_list_entries;
122 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
125 * All data structures here are protected by the global debug_lock.
127 * Mutex key structs only get allocated, once during bootup, and never
128 * get freed - this significantly simplifies the debugging code.
130 unsigned long nr_lock_classes;
131 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
133 static inline struct lock_class *hlock_class(struct held_lock *hlock)
135 if (!hlock->class_idx) {
136 DEBUG_LOCKS_WARN_ON(1);
139 return lock_classes + hlock->class_idx - 1;
142 #ifdef CONFIG_LOCK_STAT
143 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
146 static inline u64 lockstat_clock(void)
148 return cpu_clock(smp_processor_id());
151 static int lock_point(unsigned long points[], unsigned long ip)
155 for (i = 0; i < LOCKSTAT_POINTS; i++) {
156 if (points[i] == 0) {
167 static void lock_time_inc(struct lock_time *lt, u64 time)
172 if (time < lt->min || !lt->nr)
179 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
184 if (src->max > dst->max)
187 if (src->min < dst->min || !dst->nr)
190 dst->total += src->total;
194 struct lock_class_stats lock_stats(struct lock_class *class)
196 struct lock_class_stats stats;
199 memset(&stats, 0, sizeof(struct lock_class_stats));
200 for_each_possible_cpu(cpu) {
201 struct lock_class_stats *pcs =
202 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
204 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
205 stats.contention_point[i] += pcs->contention_point[i];
207 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
208 stats.contending_point[i] += pcs->contending_point[i];
210 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
211 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
213 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
214 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
216 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
217 stats.bounces[i] += pcs->bounces[i];
223 void clear_lock_stats(struct lock_class *class)
227 for_each_possible_cpu(cpu) {
228 struct lock_class_stats *cpu_stats =
229 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
231 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
233 memset(class->contention_point, 0, sizeof(class->contention_point));
234 memset(class->contending_point, 0, sizeof(class->contending_point));
237 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
239 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
242 static void put_lock_stats(struct lock_class_stats *stats)
244 put_cpu_var(cpu_lock_stats);
247 static void lock_release_holdtime(struct held_lock *hlock)
249 struct lock_class_stats *stats;
255 holdtime = lockstat_clock() - hlock->holdtime_stamp;
257 stats = get_lock_stats(hlock_class(hlock));
259 lock_time_inc(&stats->read_holdtime, holdtime);
261 lock_time_inc(&stats->write_holdtime, holdtime);
262 put_lock_stats(stats);
265 static inline void lock_release_holdtime(struct held_lock *hlock)
271 * We keep a global list of all lock classes. The list only grows,
272 * never shrinks. The list is only accessed with the lockdep
273 * spinlock lock held.
275 LIST_HEAD(all_lock_classes);
278 * The lockdep classes are in a hash-table as well, for fast lookup:
280 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
281 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
282 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
283 #define classhashentry(key) (classhash_table + __classhashfn((key)))
285 static struct list_head classhash_table[CLASSHASH_SIZE];
288 * We put the lock dependency chains into a hash-table as well, to cache
291 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
292 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
293 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
294 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
296 static struct list_head chainhash_table[CHAINHASH_SIZE];
299 * The hash key of the lock dependency chains is a hash itself too:
300 * it's a hash of all locks taken up to that lock, including that lock.
301 * It's a 64-bit hash, because it's important for the keys to be
304 #define iterate_chain_key(key1, key2) \
305 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
306 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
309 void lockdep_off(void)
311 current->lockdep_recursion++;
313 EXPORT_SYMBOL(lockdep_off);
315 void lockdep_on(void)
317 current->lockdep_recursion--;
319 EXPORT_SYMBOL(lockdep_on);
322 * Debugging switches:
326 #define VERY_VERBOSE 0
329 # define HARDIRQ_VERBOSE 1
330 # define SOFTIRQ_VERBOSE 1
331 # define RECLAIM_VERBOSE 1
333 # define HARDIRQ_VERBOSE 0
334 # define SOFTIRQ_VERBOSE 0
335 # define RECLAIM_VERBOSE 0
338 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
340 * Quick filtering for interesting events:
342 static int class_filter(struct lock_class *class)
346 if (class->name_version == 1 &&
347 !strcmp(class->name, "lockname"))
349 if (class->name_version == 1 &&
350 !strcmp(class->name, "&struct->lockfield"))
353 /* Filter everything else. 1 would be to allow everything else */
358 static int verbose(struct lock_class *class)
361 return class_filter(class);
367 * Stack-trace: tightly packed array of stack backtrace
368 * addresses. Protected by the graph_lock.
370 unsigned long nr_stack_trace_entries;
371 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
373 static int save_trace(struct stack_trace *trace)
375 trace->nr_entries = 0;
376 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
377 trace->entries = stack_trace + nr_stack_trace_entries;
381 save_stack_trace(trace);
384 * Some daft arches put -1 at the end to indicate its a full trace.
386 * <rant> this is buggy anyway, since it takes a whole extra entry so a
387 * complete trace that maxes out the entries provided will be reported
388 * as incomplete, friggin useless </rant>
390 if (trace->nr_entries != 0 &&
391 trace->entries[trace->nr_entries-1] == ULONG_MAX)
394 trace->max_entries = trace->nr_entries;
396 nr_stack_trace_entries += trace->nr_entries;
398 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
399 if (!debug_locks_off_graph_unlock())
402 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
403 printk("turning off the locking correctness validator.\n");
412 unsigned int nr_hardirq_chains;
413 unsigned int nr_softirq_chains;
414 unsigned int nr_process_chains;
415 unsigned int max_lockdep_depth;
417 #ifdef CONFIG_DEBUG_LOCKDEP
419 * We cannot printk in early bootup code. Not even early_printk()
420 * might work. So we mark any initialization errors and printk
421 * about it later on, in lockdep_info().
423 static int lockdep_init_error;
424 static unsigned long lockdep_init_trace_data[20];
425 static struct stack_trace lockdep_init_trace = {
426 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
427 .entries = lockdep_init_trace_data,
431 * Various lockdep statistics:
433 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
440 #define __USAGE(__STATE) \
441 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
442 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
443 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
444 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
446 static const char *usage_str[] =
448 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
449 #include "lockdep_states.h"
451 [LOCK_USED] = "INITIAL USE",
454 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
456 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
459 static inline unsigned long lock_flag(enum lock_usage_bit bit)
464 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
468 if (class->usage_mask & lock_flag(bit + 2))
470 if (class->usage_mask & lock_flag(bit)) {
472 if (class->usage_mask & lock_flag(bit + 2))
479 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
483 #define LOCKDEP_STATE(__STATE) \
484 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
485 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
486 #include "lockdep_states.h"
492 static void print_lock_name(struct lock_class *class)
494 char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
497 get_usage_chars(class, usage);
501 name = __get_key_name(class->key, str);
502 printk(" (%s", name);
504 printk(" (%s", name);
505 if (class->name_version > 1)
506 printk("#%d", class->name_version);
508 printk("/%d", class->subclass);
510 printk("){%s}", usage);
513 static void print_lockdep_cache(struct lockdep_map *lock)
516 char str[KSYM_NAME_LEN];
520 name = __get_key_name(lock->key->subkeys, str);
525 static void print_lock(struct held_lock *hlock)
527 print_lock_name(hlock_class(hlock));
529 print_ip_sym(hlock->acquire_ip);
532 static void lockdep_print_held_locks(struct task_struct *curr)
534 int i, depth = curr->lockdep_depth;
537 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
540 printk("%d lock%s held by %s/%d:\n",
541 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
543 for (i = 0; i < depth; i++) {
545 print_lock(curr->held_locks + i);
549 static void print_kernel_version(void)
551 printk("%s %.*s\n", init_utsname()->release,
552 (int)strcspn(init_utsname()->version, " "),
553 init_utsname()->version);
556 static int very_verbose(struct lock_class *class)
559 return class_filter(class);
565 * Is this the address of a static object:
567 static int static_obj(void *obj)
569 unsigned long start = (unsigned long) &_stext,
570 end = (unsigned long) &_end,
571 addr = (unsigned long) obj;
579 if ((addr >= start) && (addr < end))
582 if (arch_is_kernel_data(addr))
589 for_each_possible_cpu(i) {
590 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
591 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
594 if ((addr >= start) && (addr < end))
602 return is_module_address(addr);
606 * To make lock name printouts unique, we calculate a unique
607 * class->name_version generation counter:
609 static int count_matching_names(struct lock_class *new_class)
611 struct lock_class *class;
614 if (!new_class->name)
617 list_for_each_entry(class, &all_lock_classes, lock_entry) {
618 if (new_class->key - new_class->subclass == class->key)
619 return class->name_version;
620 if (class->name && !strcmp(class->name, new_class->name))
621 count = max(count, class->name_version);
628 * Register a lock's class in the hash-table, if the class is not present
629 * yet. Otherwise we look it up. We cache the result in the lock object
630 * itself, so actual lookup of the hash should be once per lock object.
632 static inline struct lock_class *
633 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
635 struct lockdep_subclass_key *key;
636 struct list_head *hash_head;
637 struct lock_class *class;
639 #ifdef CONFIG_DEBUG_LOCKDEP
641 * If the architecture calls into lockdep before initializing
642 * the hashes then we'll warn about it later. (we cannot printk
645 if (unlikely(!lockdep_initialized)) {
647 lockdep_init_error = 1;
648 save_stack_trace(&lockdep_init_trace);
653 * Static locks do not have their class-keys yet - for them the key
654 * is the lock object itself:
656 if (unlikely(!lock->key))
657 lock->key = (void *)lock;
660 * NOTE: the class-key must be unique. For dynamic locks, a static
661 * lock_class_key variable is passed in through the mutex_init()
662 * (or spin_lock_init()) call - which acts as the key. For static
663 * locks we use the lock object itself as the key.
665 BUILD_BUG_ON(sizeof(struct lock_class_key) >
666 sizeof(struct lockdep_map));
668 key = lock->key->subkeys + subclass;
670 hash_head = classhashentry(key);
673 * We can walk the hash lockfree, because the hash only
674 * grows, and we are careful when adding entries to the end:
676 list_for_each_entry(class, hash_head, hash_entry) {
677 if (class->key == key) {
678 WARN_ON_ONCE(class->name != lock->name);
687 * Register a lock's class in the hash-table, if the class is not present
688 * yet. Otherwise we look it up. We cache the result in the lock object
689 * itself, so actual lookup of the hash should be once per lock object.
691 static inline struct lock_class *
692 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
694 struct lockdep_subclass_key *key;
695 struct list_head *hash_head;
696 struct lock_class *class;
699 class = look_up_lock_class(lock, subclass);
704 * Debug-check: all keys must be persistent!
706 if (!static_obj(lock->key)) {
708 printk("INFO: trying to register non-static key.\n");
709 printk("the code is fine but needs lockdep annotation.\n");
710 printk("turning off the locking correctness validator.\n");
716 key = lock->key->subkeys + subclass;
717 hash_head = classhashentry(key);
719 raw_local_irq_save(flags);
721 raw_local_irq_restore(flags);
725 * We have to do the hash-walk again, to avoid races
728 list_for_each_entry(class, hash_head, hash_entry)
729 if (class->key == key)
732 * Allocate a new key from the static array, and add it to
735 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
736 if (!debug_locks_off_graph_unlock()) {
737 raw_local_irq_restore(flags);
740 raw_local_irq_restore(flags);
742 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
743 printk("turning off the locking correctness validator.\n");
747 class = lock_classes + nr_lock_classes++;
748 debug_atomic_inc(nr_unused_locks);
750 class->name = lock->name;
751 class->subclass = subclass;
752 INIT_LIST_HEAD(&class->lock_entry);
753 INIT_LIST_HEAD(&class->locks_before);
754 INIT_LIST_HEAD(&class->locks_after);
755 class->name_version = count_matching_names(class);
757 * We use RCU's safe list-add method to make
758 * parallel walking of the hash-list safe:
760 list_add_tail_rcu(&class->hash_entry, hash_head);
762 * Add it to the global list of classes:
764 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
766 if (verbose(class)) {
768 raw_local_irq_restore(flags);
770 printk("\nnew class %p: %s", class->key, class->name);
771 if (class->name_version > 1)
772 printk("#%d", class->name_version);
776 raw_local_irq_save(flags);
778 raw_local_irq_restore(flags);
784 raw_local_irq_restore(flags);
786 if (!subclass || force)
787 lock->class_cache = class;
789 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
795 #ifdef CONFIG_PROVE_LOCKING
797 * Allocate a lockdep entry. (assumes the graph_lock held, returns
798 * with NULL on failure)
800 static struct lock_list *alloc_list_entry(void)
802 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
803 if (!debug_locks_off_graph_unlock())
806 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
807 printk("turning off the locking correctness validator.\n");
811 return list_entries + nr_list_entries++;
815 * Add a new dependency to the head of the list:
817 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
818 struct list_head *head, unsigned long ip, int distance)
820 struct lock_list *entry;
822 * Lock not present yet - get a new dependency struct and
823 * add it to the list:
825 entry = alloc_list_entry();
829 if (!save_trace(&entry->trace))
833 entry->distance = distance;
835 * Since we never remove from the dependency list, the list can
836 * be walked lockless by other CPUs, it's only allocation
837 * that must be protected by the spinlock. But this also means
838 * we must make new entries visible only once writes to the
839 * entry become visible - hence the RCU op:
841 list_add_tail_rcu(&entry->entry, head);
847 * For good efficiency of modular, we use power of 2
849 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
850 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
853 * The circular_queue and helpers is used to implement the
854 * breadth-first search(BFS)algorithem, by which we can build
855 * the shortest path from the next lock to be acquired to the
856 * previous held lock if there is a circular between them.
858 struct circular_queue {
859 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
860 unsigned int front, rear;
863 static struct circular_queue lock_cq;
865 unsigned int max_bfs_queue_depth;
867 static unsigned int lockdep_dependency_gen_id;
869 static inline void __cq_init(struct circular_queue *cq)
871 cq->front = cq->rear = 0;
872 lockdep_dependency_gen_id++;
875 static inline int __cq_empty(struct circular_queue *cq)
877 return (cq->front == cq->rear);
880 static inline int __cq_full(struct circular_queue *cq)
882 return ((cq->rear + 1) & CQ_MASK) == cq->front;
885 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
890 cq->element[cq->rear] = elem;
891 cq->rear = (cq->rear + 1) & CQ_MASK;
895 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
900 *elem = cq->element[cq->front];
901 cq->front = (cq->front + 1) & CQ_MASK;
905 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
907 return (cq->rear - cq->front) & CQ_MASK;
910 static inline void mark_lock_accessed(struct lock_list *lock,
911 struct lock_list *parent)
915 nr = lock - list_entries;
916 WARN_ON(nr >= nr_list_entries);
917 lock->parent = parent;
918 lock->class->dep_gen_id = lockdep_dependency_gen_id;
921 static inline unsigned long lock_accessed(struct lock_list *lock)
925 nr = lock - list_entries;
926 WARN_ON(nr >= nr_list_entries);
927 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
930 static inline struct lock_list *get_lock_parent(struct lock_list *child)
932 return child->parent;
935 static inline int get_lock_depth(struct lock_list *child)
938 struct lock_list *parent;
940 while ((parent = get_lock_parent(child))) {
947 static int __bfs(struct lock_list *source_entry,
949 int (*match)(struct lock_list *entry, void *data),
950 struct lock_list **target_entry,
953 struct lock_list *entry;
954 struct list_head *head;
955 struct circular_queue *cq = &lock_cq;
958 if (match(source_entry, data)) {
959 *target_entry = source_entry;
965 head = &source_entry->class->locks_after;
967 head = &source_entry->class->locks_before;
969 if (list_empty(head))
973 __cq_enqueue(cq, (unsigned long)source_entry);
975 while (!__cq_empty(cq)) {
976 struct lock_list *lock;
978 __cq_dequeue(cq, (unsigned long *)&lock);
986 head = &lock->class->locks_after;
988 head = &lock->class->locks_before;
990 list_for_each_entry(entry, head, entry) {
991 if (!lock_accessed(entry)) {
992 unsigned int cq_depth;
993 mark_lock_accessed(entry, lock);
994 if (match(entry, data)) {
995 *target_entry = entry;
1000 if (__cq_enqueue(cq, (unsigned long)entry)) {
1004 cq_depth = __cq_get_elem_count(cq);
1005 if (max_bfs_queue_depth < cq_depth)
1006 max_bfs_queue_depth = cq_depth;
1014 static inline int __bfs_forwards(struct lock_list *src_entry,
1016 int (*match)(struct lock_list *entry, void *data),
1017 struct lock_list **target_entry)
1019 return __bfs(src_entry, data, match, target_entry, 1);
1023 static inline int __bfs_backwards(struct lock_list *src_entry,
1025 int (*match)(struct lock_list *entry, void *data),
1026 struct lock_list **target_entry)
1028 return __bfs(src_entry, data, match, target_entry, 0);
1033 * Recursive, forwards-direction lock-dependency checking, used for
1034 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1039 * Print a dependency chain entry (this is only done when a deadlock
1040 * has been detected):
1043 print_circular_bug_entry(struct lock_list *target, int depth)
1045 if (debug_locks_silent)
1047 printk("\n-> #%u", depth);
1048 print_lock_name(target->class);
1050 print_stack_trace(&target->trace, 6);
1056 * When a circular dependency is detected, print the
1060 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1061 struct held_lock *check_src,
1062 struct held_lock *check_tgt)
1064 struct task_struct *curr = current;
1066 if (debug_locks_silent)
1069 printk("\n=======================================================\n");
1070 printk( "[ INFO: possible circular locking dependency detected ]\n");
1071 print_kernel_version();
1072 printk( "-------------------------------------------------------\n");
1073 printk("%s/%d is trying to acquire lock:\n",
1074 curr->comm, task_pid_nr(curr));
1075 print_lock(check_src);
1076 printk("\nbut task is already holding lock:\n");
1077 print_lock(check_tgt);
1078 printk("\nwhich lock already depends on the new lock.\n\n");
1079 printk("\nthe existing dependency chain (in reverse order) is:\n");
1081 print_circular_bug_entry(entry, depth);
1086 static inline int class_equal(struct lock_list *entry, void *data)
1088 return entry->class == data;
1091 static noinline int print_circular_bug(struct lock_list *this,
1092 struct lock_list *target,
1093 struct held_lock *check_src,
1094 struct held_lock *check_tgt)
1096 struct task_struct *curr = current;
1097 struct lock_list *parent;
1100 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1103 if (!save_trace(&this->trace))
1106 depth = get_lock_depth(target);
1108 print_circular_bug_header(target, depth, check_src, check_tgt);
1110 parent = get_lock_parent(target);
1113 print_circular_bug_entry(parent, --depth);
1114 parent = get_lock_parent(parent);
1117 printk("\nother info that might help us debug this:\n\n");
1118 lockdep_print_held_locks(curr);
1120 printk("\nstack backtrace:\n");
1126 static noinline int print_bfs_bug(int ret)
1128 if (!debug_locks_off_graph_unlock())
1131 WARN(1, "lockdep bfs error:%d\n", ret);
1136 static int noop_count(struct lock_list *entry, void *data)
1138 (*(unsigned long *)data)++;
1142 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1144 unsigned long count = 0;
1145 struct lock_list *uninitialized_var(target_entry);
1147 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1151 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1153 unsigned long ret, flags;
1154 struct lock_list this;
1159 local_irq_save(flags);
1160 arch_spin_lock(&lockdep_lock);
1161 ret = __lockdep_count_forward_deps(&this);
1162 arch_spin_unlock(&lockdep_lock);
1163 local_irq_restore(flags);
1168 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1170 unsigned long count = 0;
1171 struct lock_list *uninitialized_var(target_entry);
1173 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1178 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1180 unsigned long ret, flags;
1181 struct lock_list this;
1186 local_irq_save(flags);
1187 arch_spin_lock(&lockdep_lock);
1188 ret = __lockdep_count_backward_deps(&this);
1189 arch_spin_unlock(&lockdep_lock);
1190 local_irq_restore(flags);
1196 * Prove that the dependency graph starting at <entry> can not
1197 * lead to <target>. Print an error and return 0 if it does.
1200 check_noncircular(struct lock_list *root, struct lock_class *target,
1201 struct lock_list **target_entry)
1205 debug_atomic_inc(nr_cyclic_checks);
1207 result = __bfs_forwards(root, target, class_equal, target_entry);
1212 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1214 * Forwards and backwards subgraph searching, for the purposes of
1215 * proving that two subgraphs can be connected by a new dependency
1216 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1219 static inline int usage_match(struct lock_list *entry, void *bit)
1221 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1227 * Find a node in the forwards-direction dependency sub-graph starting
1228 * at @root->class that matches @bit.
1230 * Return 0 if such a node exists in the subgraph, and put that node
1231 * into *@target_entry.
1233 * Return 1 otherwise and keep *@target_entry unchanged.
1234 * Return <0 on error.
1237 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1238 struct lock_list **target_entry)
1242 debug_atomic_inc(nr_find_usage_forwards_checks);
1244 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1250 * Find a node in the backwards-direction dependency sub-graph starting
1251 * at @root->class that matches @bit.
1253 * Return 0 if such a node exists in the subgraph, and put that node
1254 * into *@target_entry.
1256 * Return 1 otherwise and keep *@target_entry unchanged.
1257 * Return <0 on error.
1260 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1261 struct lock_list **target_entry)
1265 debug_atomic_inc(nr_find_usage_backwards_checks);
1267 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1272 static void print_lock_class_header(struct lock_class *class, int depth)
1276 printk("%*s->", depth, "");
1277 print_lock_name(class);
1278 printk(" ops: %lu", class->ops);
1281 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1282 if (class->usage_mask & (1 << bit)) {
1285 len += printk("%*s %s", depth, "", usage_str[bit]);
1286 len += printk(" at:\n");
1287 print_stack_trace(class->usage_traces + bit, len);
1290 printk("%*s }\n", depth, "");
1292 printk("%*s ... key at: ",depth,"");
1293 print_ip_sym((unsigned long)class->key);
1297 * printk the shortest lock dependencies from @start to @end in reverse order:
1300 print_shortest_lock_dependencies(struct lock_list *leaf,
1301 struct lock_list *root)
1303 struct lock_list *entry = leaf;
1306 /*compute depth from generated tree by BFS*/
1307 depth = get_lock_depth(leaf);
1310 print_lock_class_header(entry->class, depth);
1311 printk("%*s ... acquired at:\n", depth, "");
1312 print_stack_trace(&entry->trace, 2);
1315 if (depth == 0 && (entry != root)) {
1316 printk("lockdep:%s bad BFS generated tree\n", __func__);
1320 entry = get_lock_parent(entry);
1322 } while (entry && (depth >= 0));
1328 print_bad_irq_dependency(struct task_struct *curr,
1329 struct lock_list *prev_root,
1330 struct lock_list *next_root,
1331 struct lock_list *backwards_entry,
1332 struct lock_list *forwards_entry,
1333 struct held_lock *prev,
1334 struct held_lock *next,
1335 enum lock_usage_bit bit1,
1336 enum lock_usage_bit bit2,
1337 const char *irqclass)
1339 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1342 printk("\n======================================================\n");
1343 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1344 irqclass, irqclass);
1345 print_kernel_version();
1346 printk( "------------------------------------------------------\n");
1347 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1348 curr->comm, task_pid_nr(curr),
1349 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1350 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1351 curr->hardirqs_enabled,
1352 curr->softirqs_enabled);
1355 printk("\nand this task is already holding:\n");
1357 printk("which would create a new lock dependency:\n");
1358 print_lock_name(hlock_class(prev));
1360 print_lock_name(hlock_class(next));
1363 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1365 print_lock_name(backwards_entry->class);
1366 printk("\n... which became %s-irq-safe at:\n", irqclass);
1368 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1370 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1371 print_lock_name(forwards_entry->class);
1372 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1375 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1377 printk("\nother info that might help us debug this:\n\n");
1378 lockdep_print_held_locks(curr);
1380 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1381 printk(" and the holding lock:\n");
1382 if (!save_trace(&prev_root->trace))
1384 print_shortest_lock_dependencies(backwards_entry, prev_root);
1386 printk("\nthe dependencies between the lock to be acquired");
1387 printk(" and %s-irq-unsafe lock:\n", irqclass);
1388 if (!save_trace(&next_root->trace))
1390 print_shortest_lock_dependencies(forwards_entry, next_root);
1392 printk("\nstack backtrace:\n");
1399 check_usage(struct task_struct *curr, struct held_lock *prev,
1400 struct held_lock *next, enum lock_usage_bit bit_backwards,
1401 enum lock_usage_bit bit_forwards, const char *irqclass)
1404 struct lock_list this, that;
1405 struct lock_list *uninitialized_var(target_entry);
1406 struct lock_list *uninitialized_var(target_entry1);
1410 this.class = hlock_class(prev);
1411 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1413 return print_bfs_bug(ret);
1418 that.class = hlock_class(next);
1419 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1421 return print_bfs_bug(ret);
1425 return print_bad_irq_dependency(curr, &this, &that,
1426 target_entry, target_entry1,
1428 bit_backwards, bit_forwards, irqclass);
1431 static const char *state_names[] = {
1432 #define LOCKDEP_STATE(__STATE) \
1433 __stringify(__STATE),
1434 #include "lockdep_states.h"
1435 #undef LOCKDEP_STATE
1438 static const char *state_rnames[] = {
1439 #define LOCKDEP_STATE(__STATE) \
1440 __stringify(__STATE)"-READ",
1441 #include "lockdep_states.h"
1442 #undef LOCKDEP_STATE
1445 static inline const char *state_name(enum lock_usage_bit bit)
1447 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1450 static int exclusive_bit(int new_bit)
1458 * bit 0 - write/read
1459 * bit 1 - used_in/enabled
1463 int state = new_bit & ~3;
1464 int dir = new_bit & 2;
1467 * keep state, bit flip the direction and strip read.
1469 return state | (dir ^ 2);
1472 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1473 struct held_lock *next, enum lock_usage_bit bit)
1476 * Prove that the new dependency does not connect a hardirq-safe
1477 * lock with a hardirq-unsafe lock - to achieve this we search
1478 * the backwards-subgraph starting at <prev>, and the
1479 * forwards-subgraph starting at <next>:
1481 if (!check_usage(curr, prev, next, bit,
1482 exclusive_bit(bit), state_name(bit)))
1488 * Prove that the new dependency does not connect a hardirq-safe-read
1489 * lock with a hardirq-unsafe lock - to achieve this we search
1490 * the backwards-subgraph starting at <prev>, and the
1491 * forwards-subgraph starting at <next>:
1493 if (!check_usage(curr, prev, next, bit,
1494 exclusive_bit(bit), state_name(bit)))
1501 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1502 struct held_lock *next)
1504 #define LOCKDEP_STATE(__STATE) \
1505 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1507 #include "lockdep_states.h"
1508 #undef LOCKDEP_STATE
1513 static void inc_chains(void)
1515 if (current->hardirq_context)
1516 nr_hardirq_chains++;
1518 if (current->softirq_context)
1519 nr_softirq_chains++;
1521 nr_process_chains++;
1528 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1529 struct held_lock *next)
1534 static inline void inc_chains(void)
1536 nr_process_chains++;
1542 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1543 struct held_lock *next)
1545 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1548 printk("\n=============================================\n");
1549 printk( "[ INFO: possible recursive locking detected ]\n");
1550 print_kernel_version();
1551 printk( "---------------------------------------------\n");
1552 printk("%s/%d is trying to acquire lock:\n",
1553 curr->comm, task_pid_nr(curr));
1555 printk("\nbut task is already holding lock:\n");
1558 printk("\nother info that might help us debug this:\n");
1559 lockdep_print_held_locks(curr);
1561 printk("\nstack backtrace:\n");
1568 * Check whether we are holding such a class already.
1570 * (Note that this has to be done separately, because the graph cannot
1571 * detect such classes of deadlocks.)
1573 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1576 check_deadlock(struct task_struct *curr, struct held_lock *next,
1577 struct lockdep_map *next_instance, int read)
1579 struct held_lock *prev;
1580 struct held_lock *nest = NULL;
1583 for (i = 0; i < curr->lockdep_depth; i++) {
1584 prev = curr->held_locks + i;
1586 if (prev->instance == next->nest_lock)
1589 if (hlock_class(prev) != hlock_class(next))
1593 * Allow read-after-read recursion of the same
1594 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1596 if ((read == 2) && prev->read)
1600 * We're holding the nest_lock, which serializes this lock's
1601 * nesting behaviour.
1606 return print_deadlock_bug(curr, prev, next);
1612 * There was a chain-cache miss, and we are about to add a new dependency
1613 * to a previous lock. We recursively validate the following rules:
1615 * - would the adding of the <prev> -> <next> dependency create a
1616 * circular dependency in the graph? [== circular deadlock]
1618 * - does the new prev->next dependency connect any hardirq-safe lock
1619 * (in the full backwards-subgraph starting at <prev>) with any
1620 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1621 * <next>)? [== illegal lock inversion with hardirq contexts]
1623 * - does the new prev->next dependency connect any softirq-safe lock
1624 * (in the full backwards-subgraph starting at <prev>) with any
1625 * softirq-unsafe lock (in the full forwards-subgraph starting at
1626 * <next>)? [== illegal lock inversion with softirq contexts]
1628 * any of these scenarios could lead to a deadlock.
1630 * Then if all the validations pass, we add the forwards and backwards
1634 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1635 struct held_lock *next, int distance)
1637 struct lock_list *entry;
1639 struct lock_list this;
1640 struct lock_list *uninitialized_var(target_entry);
1643 * Prove that the new <prev> -> <next> dependency would not
1644 * create a circular dependency in the graph. (We do this by
1645 * forward-recursing into the graph starting at <next>, and
1646 * checking whether we can reach <prev>.)
1648 * We are using global variables to control the recursion, to
1649 * keep the stackframe size of the recursive functions low:
1651 this.class = hlock_class(next);
1653 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1655 return print_circular_bug(&this, target_entry, next, prev);
1656 else if (unlikely(ret < 0))
1657 return print_bfs_bug(ret);
1659 if (!check_prev_add_irq(curr, prev, next))
1663 * For recursive read-locks we do all the dependency checks,
1664 * but we dont store read-triggered dependencies (only
1665 * write-triggered dependencies). This ensures that only the
1666 * write-side dependencies matter, and that if for example a
1667 * write-lock never takes any other locks, then the reads are
1668 * equivalent to a NOP.
1670 if (next->read == 2 || prev->read == 2)
1673 * Is the <prev> -> <next> dependency already present?
1675 * (this may occur even though this is a new chain: consider
1676 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1677 * chains - the second one will be new, but L1 already has
1678 * L2 added to its dependency list, due to the first chain.)
1680 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1681 if (entry->class == hlock_class(next)) {
1683 entry->distance = 1;
1689 * Ok, all validations passed, add the new lock
1690 * to the previous lock's dependency list:
1692 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1693 &hlock_class(prev)->locks_after,
1694 next->acquire_ip, distance);
1699 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1700 &hlock_class(next)->locks_before,
1701 next->acquire_ip, distance);
1706 * Debugging printouts:
1708 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1710 printk("\n new dependency: ");
1711 print_lock_name(hlock_class(prev));
1713 print_lock_name(hlock_class(next));
1716 return graph_lock();
1722 * Add the dependency to all directly-previous locks that are 'relevant'.
1723 * The ones that are relevant are (in increasing distance from curr):
1724 * all consecutive trylock entries and the final non-trylock entry - or
1725 * the end of this context's lock-chain - whichever comes first.
1728 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1730 int depth = curr->lockdep_depth;
1731 struct held_lock *hlock;
1736 * Depth must not be zero for a non-head lock:
1741 * At least two relevant locks must exist for this
1744 if (curr->held_locks[depth].irq_context !=
1745 curr->held_locks[depth-1].irq_context)
1749 int distance = curr->lockdep_depth - depth + 1;
1750 hlock = curr->held_locks + depth-1;
1752 * Only non-recursive-read entries get new dependencies
1755 if (hlock->read != 2) {
1756 if (!check_prev_add(curr, hlock, next, distance))
1759 * Stop after the first non-trylock entry,
1760 * as non-trylock entries have added their
1761 * own direct dependencies already, so this
1762 * lock is connected to them indirectly:
1764 if (!hlock->trylock)
1769 * End of lock-stack?
1774 * Stop the search if we cross into another context:
1776 if (curr->held_locks[depth].irq_context !=
1777 curr->held_locks[depth-1].irq_context)
1782 if (!debug_locks_off_graph_unlock())
1790 unsigned long nr_lock_chains;
1791 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1792 int nr_chain_hlocks;
1793 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1795 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1797 return lock_classes + chain_hlocks[chain->base + i];
1801 * Look up a dependency chain. If the key is not present yet then
1802 * add it and return 1 - in this case the new dependency chain is
1803 * validated. If the key is already hashed, return 0.
1804 * (On return with 1 graph_lock is held.)
1806 static inline int lookup_chain_cache(struct task_struct *curr,
1807 struct held_lock *hlock,
1810 struct lock_class *class = hlock_class(hlock);
1811 struct list_head *hash_head = chainhashentry(chain_key);
1812 struct lock_chain *chain;
1813 struct held_lock *hlock_curr, *hlock_next;
1816 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1819 * We can walk it lock-free, because entries only get added
1822 list_for_each_entry(chain, hash_head, entry) {
1823 if (chain->chain_key == chain_key) {
1825 debug_atomic_inc(chain_lookup_hits);
1826 if (very_verbose(class))
1827 printk("\nhash chain already cached, key: "
1828 "%016Lx tail class: [%p] %s\n",
1829 (unsigned long long)chain_key,
1830 class->key, class->name);
1834 if (very_verbose(class))
1835 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1836 (unsigned long long)chain_key, class->key, class->name);
1838 * Allocate a new chain entry from the static array, and add
1844 * We have to walk the chain again locked - to avoid duplicates:
1846 list_for_each_entry(chain, hash_head, entry) {
1847 if (chain->chain_key == chain_key) {
1852 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1853 if (!debug_locks_off_graph_unlock())
1856 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1857 printk("turning off the locking correctness validator.\n");
1861 chain = lock_chains + nr_lock_chains++;
1862 chain->chain_key = chain_key;
1863 chain->irq_context = hlock->irq_context;
1864 /* Find the first held_lock of current chain */
1866 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1867 hlock_curr = curr->held_locks + i;
1868 if (hlock_curr->irq_context != hlock_next->irq_context)
1873 chain->depth = curr->lockdep_depth + 1 - i;
1874 cn = nr_chain_hlocks;
1875 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1876 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1881 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1883 for (j = 0; j < chain->depth - 1; j++, i++) {
1884 int lock_id = curr->held_locks[i].class_idx - 1;
1885 chain_hlocks[chain->base + j] = lock_id;
1887 chain_hlocks[chain->base + j] = class - lock_classes;
1889 list_add_tail_rcu(&chain->entry, hash_head);
1890 debug_atomic_inc(chain_lookup_misses);
1896 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1897 struct held_lock *hlock, int chain_head, u64 chain_key)
1900 * Trylock needs to maintain the stack of held locks, but it
1901 * does not add new dependencies, because trylock can be done
1904 * We look up the chain_key and do the O(N^2) check and update of
1905 * the dependencies only if this is a new dependency chain.
1906 * (If lookup_chain_cache() returns with 1 it acquires
1907 * graph_lock for us)
1909 if (!hlock->trylock && (hlock->check == 2) &&
1910 lookup_chain_cache(curr, hlock, chain_key)) {
1912 * Check whether last held lock:
1914 * - is irq-safe, if this lock is irq-unsafe
1915 * - is softirq-safe, if this lock is hardirq-unsafe
1917 * And check whether the new lock's dependency graph
1918 * could lead back to the previous lock.
1920 * any of these scenarios could lead to a deadlock. If
1923 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1928 * Mark recursive read, as we jump over it when
1929 * building dependencies (just like we jump over
1935 * Add dependency only if this lock is not the head
1936 * of the chain, and if it's not a secondary read-lock:
1938 if (!chain_head && ret != 2)
1939 if (!check_prevs_add(curr, hlock))
1943 /* after lookup_chain_cache(): */
1944 if (unlikely(!debug_locks))
1950 static inline int validate_chain(struct task_struct *curr,
1951 struct lockdep_map *lock, struct held_lock *hlock,
1952 int chain_head, u64 chain_key)
1959 * We are building curr_chain_key incrementally, so double-check
1960 * it from scratch, to make sure that it's done correctly:
1962 static void check_chain_key(struct task_struct *curr)
1964 #ifdef CONFIG_DEBUG_LOCKDEP
1965 struct held_lock *hlock, *prev_hlock = NULL;
1969 for (i = 0; i < curr->lockdep_depth; i++) {
1970 hlock = curr->held_locks + i;
1971 if (chain_key != hlock->prev_chain_key) {
1973 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1974 curr->lockdep_depth, i,
1975 (unsigned long long)chain_key,
1976 (unsigned long long)hlock->prev_chain_key);
1979 id = hlock->class_idx - 1;
1980 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1983 if (prev_hlock && (prev_hlock->irq_context !=
1984 hlock->irq_context))
1986 chain_key = iterate_chain_key(chain_key, id);
1989 if (chain_key != curr->curr_chain_key) {
1991 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1992 curr->lockdep_depth, i,
1993 (unsigned long long)chain_key,
1994 (unsigned long long)curr->curr_chain_key);
2000 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2001 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2003 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2006 printk("\n=================================\n");
2007 printk( "[ INFO: inconsistent lock state ]\n");
2008 print_kernel_version();
2009 printk( "---------------------------------\n");
2011 printk("inconsistent {%s} -> {%s} usage.\n",
2012 usage_str[prev_bit], usage_str[new_bit]);
2014 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2015 curr->comm, task_pid_nr(curr),
2016 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2017 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2018 trace_hardirqs_enabled(curr),
2019 trace_softirqs_enabled(curr));
2022 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2023 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2025 print_irqtrace_events(curr);
2026 printk("\nother info that might help us debug this:\n");
2027 lockdep_print_held_locks(curr);
2029 printk("\nstack backtrace:\n");
2036 * Print out an error if an invalid bit is set:
2039 valid_state(struct task_struct *curr, struct held_lock *this,
2040 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2042 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2043 return print_usage_bug(curr, this, bad_bit, new_bit);
2047 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2048 enum lock_usage_bit new_bit);
2050 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2053 * print irq inversion bug:
2056 print_irq_inversion_bug(struct task_struct *curr,
2057 struct lock_list *root, struct lock_list *other,
2058 struct held_lock *this, int forwards,
2059 const char *irqclass)
2061 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2064 printk("\n=========================================================\n");
2065 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
2066 print_kernel_version();
2067 printk( "---------------------------------------------------------\n");
2068 printk("%s/%d just changed the state of lock:\n",
2069 curr->comm, task_pid_nr(curr));
2072 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2074 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2075 print_lock_name(other->class);
2076 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2078 printk("\nother info that might help us debug this:\n");
2079 lockdep_print_held_locks(curr);
2081 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2082 if (!save_trace(&root->trace))
2084 print_shortest_lock_dependencies(other, root);
2086 printk("\nstack backtrace:\n");
2093 * Prove that in the forwards-direction subgraph starting at <this>
2094 * there is no lock matching <mask>:
2097 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2098 enum lock_usage_bit bit, const char *irqclass)
2101 struct lock_list root;
2102 struct lock_list *uninitialized_var(target_entry);
2105 root.class = hlock_class(this);
2106 ret = find_usage_forwards(&root, bit, &target_entry);
2108 return print_bfs_bug(ret);
2112 return print_irq_inversion_bug(curr, &root, target_entry,
2117 * Prove that in the backwards-direction subgraph starting at <this>
2118 * there is no lock matching <mask>:
2121 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2122 enum lock_usage_bit bit, const char *irqclass)
2125 struct lock_list root;
2126 struct lock_list *uninitialized_var(target_entry);
2129 root.class = hlock_class(this);
2130 ret = find_usage_backwards(&root, bit, &target_entry);
2132 return print_bfs_bug(ret);
2136 return print_irq_inversion_bug(curr, &root, target_entry,
2140 void print_irqtrace_events(struct task_struct *curr)
2142 printk("irq event stamp: %u\n", curr->irq_events);
2143 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2144 print_ip_sym(curr->hardirq_enable_ip);
2145 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2146 print_ip_sym(curr->hardirq_disable_ip);
2147 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2148 print_ip_sym(curr->softirq_enable_ip);
2149 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2150 print_ip_sym(curr->softirq_disable_ip);
2153 static int HARDIRQ_verbose(struct lock_class *class)
2156 return class_filter(class);
2161 static int SOFTIRQ_verbose(struct lock_class *class)
2164 return class_filter(class);
2169 static int RECLAIM_FS_verbose(struct lock_class *class)
2172 return class_filter(class);
2177 #define STRICT_READ_CHECKS 1
2179 static int (*state_verbose_f[])(struct lock_class *class) = {
2180 #define LOCKDEP_STATE(__STATE) \
2182 #include "lockdep_states.h"
2183 #undef LOCKDEP_STATE
2186 static inline int state_verbose(enum lock_usage_bit bit,
2187 struct lock_class *class)
2189 return state_verbose_f[bit >> 2](class);
2192 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2193 enum lock_usage_bit bit, const char *name);
2196 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2197 enum lock_usage_bit new_bit)
2199 int excl_bit = exclusive_bit(new_bit);
2200 int read = new_bit & 1;
2201 int dir = new_bit & 2;
2204 * mark USED_IN has to look forwards -- to ensure no dependency
2205 * has ENABLED state, which would allow recursion deadlocks.
2207 * mark ENABLED has to look backwards -- to ensure no dependee
2208 * has USED_IN state, which, again, would allow recursion deadlocks.
2210 check_usage_f usage = dir ?
2211 check_usage_backwards : check_usage_forwards;
2214 * Validate that this particular lock does not have conflicting
2217 if (!valid_state(curr, this, new_bit, excl_bit))
2221 * Validate that the lock dependencies don't have conflicting usage
2224 if ((!read || !dir || STRICT_READ_CHECKS) &&
2225 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2229 * Check for read in write conflicts
2232 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2235 if (STRICT_READ_CHECKS &&
2236 !usage(curr, this, excl_bit + 1,
2237 state_name(new_bit + 1)))
2241 if (state_verbose(new_bit, hlock_class(this)))
2248 #define LOCKDEP_STATE(__STATE) __STATE,
2249 #include "lockdep_states.h"
2250 #undef LOCKDEP_STATE
2254 * Mark all held locks with a usage bit:
2257 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2259 enum lock_usage_bit usage_bit;
2260 struct held_lock *hlock;
2263 for (i = 0; i < curr->lockdep_depth; i++) {
2264 hlock = curr->held_locks + i;
2266 usage_bit = 2 + (mark << 2); /* ENABLED */
2268 usage_bit += 1; /* READ */
2270 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2272 if (!mark_lock(curr, hlock, usage_bit))
2280 * Debugging helper: via this flag we know that we are in
2281 * 'early bootup code', and will warn about any invalid irqs-on event:
2283 static int early_boot_irqs_enabled;
2285 void early_boot_irqs_off(void)
2287 early_boot_irqs_enabled = 0;
2290 void early_boot_irqs_on(void)
2292 early_boot_irqs_enabled = 1;
2296 * Hardirqs will be enabled:
2298 void trace_hardirqs_on_caller(unsigned long ip)
2300 struct task_struct *curr = current;
2302 time_hardirqs_on(CALLER_ADDR0, ip);
2304 if (unlikely(!debug_locks || current->lockdep_recursion))
2307 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2310 if (unlikely(curr->hardirqs_enabled)) {
2311 debug_atomic_inc(redundant_hardirqs_on);
2314 /* we'll do an OFF -> ON transition: */
2315 curr->hardirqs_enabled = 1;
2317 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2319 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2322 * We are going to turn hardirqs on, so set the
2323 * usage bit for all held locks:
2325 if (!mark_held_locks(curr, HARDIRQ))
2328 * If we have softirqs enabled, then set the usage
2329 * bit for all held locks. (disabled hardirqs prevented
2330 * this bit from being set before)
2332 if (curr->softirqs_enabled)
2333 if (!mark_held_locks(curr, SOFTIRQ))
2336 curr->hardirq_enable_ip = ip;
2337 curr->hardirq_enable_event = ++curr->irq_events;
2338 debug_atomic_inc(hardirqs_on_events);
2340 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2342 void trace_hardirqs_on(void)
2344 trace_hardirqs_on_caller(CALLER_ADDR0);
2346 EXPORT_SYMBOL(trace_hardirqs_on);
2349 * Hardirqs were disabled:
2351 void trace_hardirqs_off_caller(unsigned long ip)
2353 struct task_struct *curr = current;
2355 time_hardirqs_off(CALLER_ADDR0, ip);
2357 if (unlikely(!debug_locks || current->lockdep_recursion))
2360 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2363 if (curr->hardirqs_enabled) {
2365 * We have done an ON -> OFF transition:
2367 curr->hardirqs_enabled = 0;
2368 curr->hardirq_disable_ip = ip;
2369 curr->hardirq_disable_event = ++curr->irq_events;
2370 debug_atomic_inc(hardirqs_off_events);
2372 debug_atomic_inc(redundant_hardirqs_off);
2374 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2376 void trace_hardirqs_off(void)
2378 trace_hardirqs_off_caller(CALLER_ADDR0);
2380 EXPORT_SYMBOL(trace_hardirqs_off);
2383 * Softirqs will be enabled:
2385 void trace_softirqs_on(unsigned long ip)
2387 struct task_struct *curr = current;
2389 if (unlikely(!debug_locks))
2392 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2395 if (curr->softirqs_enabled) {
2396 debug_atomic_inc(redundant_softirqs_on);
2401 * We'll do an OFF -> ON transition:
2403 curr->softirqs_enabled = 1;
2404 curr->softirq_enable_ip = ip;
2405 curr->softirq_enable_event = ++curr->irq_events;
2406 debug_atomic_inc(softirqs_on_events);
2408 * We are going to turn softirqs on, so set the
2409 * usage bit for all held locks, if hardirqs are
2412 if (curr->hardirqs_enabled)
2413 mark_held_locks(curr, SOFTIRQ);
2417 * Softirqs were disabled:
2419 void trace_softirqs_off(unsigned long ip)
2421 struct task_struct *curr = current;
2423 if (unlikely(!debug_locks))
2426 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2429 if (curr->softirqs_enabled) {
2431 * We have done an ON -> OFF transition:
2433 curr->softirqs_enabled = 0;
2434 curr->softirq_disable_ip = ip;
2435 curr->softirq_disable_event = ++curr->irq_events;
2436 debug_atomic_inc(softirqs_off_events);
2437 DEBUG_LOCKS_WARN_ON(!softirq_count());
2439 debug_atomic_inc(redundant_softirqs_off);
2442 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2444 struct task_struct *curr = current;
2446 if (unlikely(!debug_locks))
2449 /* no reclaim without waiting on it */
2450 if (!(gfp_mask & __GFP_WAIT))
2453 /* this guy won't enter reclaim */
2454 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2457 /* We're only interested __GFP_FS allocations for now */
2458 if (!(gfp_mask & __GFP_FS))
2461 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2464 mark_held_locks(curr, RECLAIM_FS);
2467 static void check_flags(unsigned long flags);
2469 void lockdep_trace_alloc(gfp_t gfp_mask)
2471 unsigned long flags;
2473 if (unlikely(current->lockdep_recursion))
2476 raw_local_irq_save(flags);
2478 current->lockdep_recursion = 1;
2479 __lockdep_trace_alloc(gfp_mask, flags);
2480 current->lockdep_recursion = 0;
2481 raw_local_irq_restore(flags);
2484 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2487 * If non-trylock use in a hardirq or softirq context, then
2488 * mark the lock as used in these contexts:
2490 if (!hlock->trylock) {
2492 if (curr->hardirq_context)
2493 if (!mark_lock(curr, hlock,
2494 LOCK_USED_IN_HARDIRQ_READ))
2496 if (curr->softirq_context)
2497 if (!mark_lock(curr, hlock,
2498 LOCK_USED_IN_SOFTIRQ_READ))
2501 if (curr->hardirq_context)
2502 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2504 if (curr->softirq_context)
2505 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2509 if (!hlock->hardirqs_off) {
2511 if (!mark_lock(curr, hlock,
2512 LOCK_ENABLED_HARDIRQ_READ))
2514 if (curr->softirqs_enabled)
2515 if (!mark_lock(curr, hlock,
2516 LOCK_ENABLED_SOFTIRQ_READ))
2519 if (!mark_lock(curr, hlock,
2520 LOCK_ENABLED_HARDIRQ))
2522 if (curr->softirqs_enabled)
2523 if (!mark_lock(curr, hlock,
2524 LOCK_ENABLED_SOFTIRQ))
2530 * We reuse the irq context infrastructure more broadly as a general
2531 * context checking code. This tests GFP_FS recursion (a lock taken
2532 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2535 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2537 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2540 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2548 static int separate_irq_context(struct task_struct *curr,
2549 struct held_lock *hlock)
2551 unsigned int depth = curr->lockdep_depth;
2554 * Keep track of points where we cross into an interrupt context:
2556 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2557 curr->softirq_context;
2559 struct held_lock *prev_hlock;
2561 prev_hlock = curr->held_locks + depth-1;
2563 * If we cross into another context, reset the
2564 * hash key (this also prevents the checking and the
2565 * adding of the dependency to 'prev'):
2567 if (prev_hlock->irq_context != hlock->irq_context)
2576 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2577 enum lock_usage_bit new_bit)
2583 static inline int mark_irqflags(struct task_struct *curr,
2584 struct held_lock *hlock)
2589 static inline int separate_irq_context(struct task_struct *curr,
2590 struct held_lock *hlock)
2595 void lockdep_trace_alloc(gfp_t gfp_mask)
2602 * Mark a lock with a usage bit, and validate the state transition:
2604 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2605 enum lock_usage_bit new_bit)
2607 unsigned int new_mask = 1 << new_bit, ret = 1;
2610 * If already set then do not dirty the cacheline,
2611 * nor do any checks:
2613 if (likely(hlock_class(this)->usage_mask & new_mask))
2619 * Make sure we didnt race:
2621 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2626 hlock_class(this)->usage_mask |= new_mask;
2628 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2632 #define LOCKDEP_STATE(__STATE) \
2633 case LOCK_USED_IN_##__STATE: \
2634 case LOCK_USED_IN_##__STATE##_READ: \
2635 case LOCK_ENABLED_##__STATE: \
2636 case LOCK_ENABLED_##__STATE##_READ:
2637 #include "lockdep_states.h"
2638 #undef LOCKDEP_STATE
2639 ret = mark_lock_irq(curr, this, new_bit);
2644 debug_atomic_dec(nr_unused_locks);
2647 if (!debug_locks_off_graph_unlock())
2656 * We must printk outside of the graph_lock:
2659 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2661 print_irqtrace_events(curr);
2669 * Initialize a lock instance's lock-class mapping info:
2671 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2672 struct lock_class_key *key, int subclass)
2674 lock->class_cache = NULL;
2675 #ifdef CONFIG_LOCK_STAT
2676 lock->cpu = raw_smp_processor_id();
2679 if (DEBUG_LOCKS_WARN_ON(!name)) {
2680 lock->name = "NULL";
2686 if (DEBUG_LOCKS_WARN_ON(!key))
2689 * Sanity check, the lock-class key must be persistent:
2691 if (!static_obj(key)) {
2692 printk("BUG: key %p not in .data!\n", key);
2693 DEBUG_LOCKS_WARN_ON(1);
2698 if (unlikely(!debug_locks))
2702 register_lock_class(lock, subclass, 1);
2704 EXPORT_SYMBOL_GPL(lockdep_init_map);
2707 * This gets called for every mutex_lock*()/spin_lock*() operation.
2708 * We maintain the dependency maps and validate the locking attempt:
2710 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2711 int trylock, int read, int check, int hardirqs_off,
2712 struct lockdep_map *nest_lock, unsigned long ip,
2715 struct task_struct *curr = current;
2716 struct lock_class *class = NULL;
2717 struct held_lock *hlock;
2718 unsigned int depth, id;
2726 if (unlikely(!debug_locks))
2729 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2732 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2734 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2735 printk("turning off the locking correctness validator.\n");
2741 class = lock->class_cache;
2743 * Not cached yet or subclass?
2745 if (unlikely(!class)) {
2746 class = register_lock_class(lock, subclass, 0);
2750 atomic_inc((atomic_t *)&class->ops);
2751 if (very_verbose(class)) {
2752 printk("\nacquire class [%p] %s", class->key, class->name);
2753 if (class->name_version > 1)
2754 printk("#%d", class->name_version);
2760 * Add the lock to the list of currently held locks.
2761 * (we dont increase the depth just yet, up until the
2762 * dependency checks are done)
2764 depth = curr->lockdep_depth;
2765 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2768 class_idx = class - lock_classes + 1;
2771 hlock = curr->held_locks + depth - 1;
2772 if (hlock->class_idx == class_idx && nest_lock) {
2773 if (hlock->references)
2774 hlock->references++;
2776 hlock->references = 2;
2782 hlock = curr->held_locks + depth;
2783 if (DEBUG_LOCKS_WARN_ON(!class))
2785 hlock->class_idx = class_idx;
2786 hlock->acquire_ip = ip;
2787 hlock->instance = lock;
2788 hlock->nest_lock = nest_lock;
2789 hlock->trylock = trylock;
2791 hlock->check = check;
2792 hlock->hardirqs_off = !!hardirqs_off;
2793 hlock->references = references;
2794 #ifdef CONFIG_LOCK_STAT
2795 hlock->waittime_stamp = 0;
2796 hlock->holdtime_stamp = lockstat_clock();
2799 if (check == 2 && !mark_irqflags(curr, hlock))
2802 /* mark it as used: */
2803 if (!mark_lock(curr, hlock, LOCK_USED))
2807 * Calculate the chain hash: it's the combined hash of all the
2808 * lock keys along the dependency chain. We save the hash value
2809 * at every step so that we can get the current hash easily
2810 * after unlock. The chain hash is then used to cache dependency
2813 * The 'key ID' is what is the most compact key value to drive
2814 * the hash, not class->key.
2816 id = class - lock_classes;
2817 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2820 chain_key = curr->curr_chain_key;
2822 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2827 hlock->prev_chain_key = chain_key;
2828 if (separate_irq_context(curr, hlock)) {
2832 chain_key = iterate_chain_key(chain_key, id);
2834 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2837 curr->curr_chain_key = chain_key;
2838 curr->lockdep_depth++;
2839 check_chain_key(curr);
2840 #ifdef CONFIG_DEBUG_LOCKDEP
2841 if (unlikely(!debug_locks))
2844 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2846 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2847 printk("turning off the locking correctness validator.\n");
2852 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2853 max_lockdep_depth = curr->lockdep_depth;
2859 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2862 if (!debug_locks_off())
2864 if (debug_locks_silent)
2867 printk("\n=====================================\n");
2868 printk( "[ BUG: bad unlock balance detected! ]\n");
2869 printk( "-------------------------------------\n");
2870 printk("%s/%d is trying to release lock (",
2871 curr->comm, task_pid_nr(curr));
2872 print_lockdep_cache(lock);
2875 printk("but there are no more locks to release!\n");
2876 printk("\nother info that might help us debug this:\n");
2877 lockdep_print_held_locks(curr);
2879 printk("\nstack backtrace:\n");
2886 * Common debugging checks for both nested and non-nested unlock:
2888 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2891 if (unlikely(!debug_locks))
2893 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2896 if (curr->lockdep_depth <= 0)
2897 return print_unlock_inbalance_bug(curr, lock, ip);
2902 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
2904 if (hlock->instance == lock)
2907 if (hlock->references) {
2908 struct lock_class *class = lock->class_cache;
2911 class = look_up_lock_class(lock, 0);
2913 if (DEBUG_LOCKS_WARN_ON(!class))
2916 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
2919 if (hlock->class_idx == class - lock_classes + 1)
2927 __lock_set_class(struct lockdep_map *lock, const char *name,
2928 struct lock_class_key *key, unsigned int subclass,
2931 struct task_struct *curr = current;
2932 struct held_lock *hlock, *prev_hlock;
2933 struct lock_class *class;
2937 depth = curr->lockdep_depth;
2938 if (DEBUG_LOCKS_WARN_ON(!depth))
2942 for (i = depth-1; i >= 0; i--) {
2943 hlock = curr->held_locks + i;
2945 * We must not cross into another context:
2947 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2949 if (match_held_lock(hlock, lock))
2953 return print_unlock_inbalance_bug(curr, lock, ip);
2956 lockdep_init_map(lock, name, key, 0);
2957 class = register_lock_class(lock, subclass, 0);
2958 hlock->class_idx = class - lock_classes + 1;
2960 curr->lockdep_depth = i;
2961 curr->curr_chain_key = hlock->prev_chain_key;
2963 for (; i < depth; i++) {
2964 hlock = curr->held_locks + i;
2965 if (!__lock_acquire(hlock->instance,
2966 hlock_class(hlock)->subclass, hlock->trylock,
2967 hlock->read, hlock->check, hlock->hardirqs_off,
2968 hlock->nest_lock, hlock->acquire_ip,
2973 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2979 * Remove the lock to the list of currently held locks in a
2980 * potentially non-nested (out of order) manner. This is a
2981 * relatively rare operation, as all the unlock APIs default
2982 * to nested mode (which uses lock_release()):
2985 lock_release_non_nested(struct task_struct *curr,
2986 struct lockdep_map *lock, unsigned long ip)
2988 struct held_lock *hlock, *prev_hlock;
2993 * Check whether the lock exists in the current stack
2996 depth = curr->lockdep_depth;
2997 if (DEBUG_LOCKS_WARN_ON(!depth))
3001 for (i = depth-1; i >= 0; i--) {
3002 hlock = curr->held_locks + i;
3004 * We must not cross into another context:
3006 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3008 if (match_held_lock(hlock, lock))
3012 return print_unlock_inbalance_bug(curr, lock, ip);
3015 if (hlock->instance == lock)
3016 lock_release_holdtime(hlock);
3018 if (hlock->references) {
3019 hlock->references--;
3020 if (hlock->references) {
3022 * We had, and after removing one, still have
3023 * references, the current lock stack is still
3024 * valid. We're done!
3031 * We have the right lock to unlock, 'hlock' points to it.
3032 * Now we remove it from the stack, and add back the other
3033 * entries (if any), recalculating the hash along the way:
3036 curr->lockdep_depth = i;
3037 curr->curr_chain_key = hlock->prev_chain_key;
3039 for (i++; i < depth; i++) {
3040 hlock = curr->held_locks + i;
3041 if (!__lock_acquire(hlock->instance,
3042 hlock_class(hlock)->subclass, hlock->trylock,
3043 hlock->read, hlock->check, hlock->hardirqs_off,
3044 hlock->nest_lock, hlock->acquire_ip,
3049 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3055 * Remove the lock to the list of currently held locks - this gets
3056 * called on mutex_unlock()/spin_unlock*() (or on a failed
3057 * mutex_lock_interruptible()). This is done for unlocks that nest
3058 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3060 static int lock_release_nested(struct task_struct *curr,
3061 struct lockdep_map *lock, unsigned long ip)
3063 struct held_lock *hlock;
3067 * Pop off the top of the lock stack:
3069 depth = curr->lockdep_depth - 1;
3070 hlock = curr->held_locks + depth;
3073 * Is the unlock non-nested:
3075 if (hlock->instance != lock || hlock->references)
3076 return lock_release_non_nested(curr, lock, ip);
3077 curr->lockdep_depth--;
3079 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3082 curr->curr_chain_key = hlock->prev_chain_key;
3084 lock_release_holdtime(hlock);
3086 #ifdef CONFIG_DEBUG_LOCKDEP
3087 hlock->prev_chain_key = 0;
3088 hlock->class_idx = 0;
3089 hlock->acquire_ip = 0;
3090 hlock->irq_context = 0;
3096 * Remove the lock to the list of currently held locks - this gets
3097 * called on mutex_unlock()/spin_unlock*() (or on a failed
3098 * mutex_lock_interruptible()). This is done for unlocks that nest
3099 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3102 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3104 struct task_struct *curr = current;
3106 if (!check_unlock(curr, lock, ip))
3110 if (!lock_release_nested(curr, lock, ip))
3113 if (!lock_release_non_nested(curr, lock, ip))
3117 check_chain_key(curr);
3120 static int __lock_is_held(struct lockdep_map *lock)
3122 struct task_struct *curr = current;
3125 for (i = 0; i < curr->lockdep_depth; i++) {
3126 struct held_lock *hlock = curr->held_locks + i;
3128 if (match_held_lock(hlock, lock))
3136 * Check whether we follow the irq-flags state precisely:
3138 static void check_flags(unsigned long flags)
3140 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3141 defined(CONFIG_TRACE_IRQFLAGS)
3145 if (irqs_disabled_flags(flags)) {
3146 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3147 printk("possible reason: unannotated irqs-off.\n");
3150 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3151 printk("possible reason: unannotated irqs-on.\n");
3156 * We dont accurately track softirq state in e.g.
3157 * hardirq contexts (such as on 4KSTACKS), so only
3158 * check if not in hardirq contexts:
3160 if (!hardirq_count()) {
3161 if (softirq_count())
3162 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3164 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3168 print_irqtrace_events(current);
3172 void lock_set_class(struct lockdep_map *lock, const char *name,
3173 struct lock_class_key *key, unsigned int subclass,
3176 unsigned long flags;
3178 if (unlikely(current->lockdep_recursion))
3181 raw_local_irq_save(flags);
3182 current->lockdep_recursion = 1;
3184 if (__lock_set_class(lock, name, key, subclass, ip))
3185 check_chain_key(current);
3186 current->lockdep_recursion = 0;
3187 raw_local_irq_restore(flags);
3189 EXPORT_SYMBOL_GPL(lock_set_class);
3192 * We are not always called with irqs disabled - do that here,
3193 * and also avoid lockdep recursion:
3195 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3196 int trylock, int read, int check,
3197 struct lockdep_map *nest_lock, unsigned long ip)
3199 unsigned long flags;
3201 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3203 if (unlikely(current->lockdep_recursion))
3206 raw_local_irq_save(flags);
3209 current->lockdep_recursion = 1;
3210 __lock_acquire(lock, subclass, trylock, read, check,
3211 irqs_disabled_flags(flags), nest_lock, ip, 0);
3212 current->lockdep_recursion = 0;
3213 raw_local_irq_restore(flags);
3215 EXPORT_SYMBOL_GPL(lock_acquire);
3217 void lock_release(struct lockdep_map *lock, int nested,
3220 unsigned long flags;
3222 trace_lock_release(lock, nested, ip);
3224 if (unlikely(current->lockdep_recursion))
3227 raw_local_irq_save(flags);
3229 current->lockdep_recursion = 1;
3230 __lock_release(lock, nested, ip);
3231 current->lockdep_recursion = 0;
3232 raw_local_irq_restore(flags);
3234 EXPORT_SYMBOL_GPL(lock_release);
3236 int lock_is_held(struct lockdep_map *lock)
3238 unsigned long flags;
3241 if (unlikely(current->lockdep_recursion))
3244 raw_local_irq_save(flags);
3247 current->lockdep_recursion = 1;
3248 ret = __lock_is_held(lock);
3249 current->lockdep_recursion = 0;
3250 raw_local_irq_restore(flags);
3254 EXPORT_SYMBOL_GPL(lock_is_held);
3256 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3258 current->lockdep_reclaim_gfp = gfp_mask;
3261 void lockdep_clear_current_reclaim_state(void)
3263 current->lockdep_reclaim_gfp = 0;
3266 #ifdef CONFIG_LOCK_STAT
3268 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3271 if (!debug_locks_off())
3273 if (debug_locks_silent)
3276 printk("\n=================================\n");
3277 printk( "[ BUG: bad contention detected! ]\n");
3278 printk( "---------------------------------\n");
3279 printk("%s/%d is trying to contend lock (",
3280 curr->comm, task_pid_nr(curr));
3281 print_lockdep_cache(lock);
3284 printk("but there are no locks held!\n");
3285 printk("\nother info that might help us debug this:\n");
3286 lockdep_print_held_locks(curr);
3288 printk("\nstack backtrace:\n");
3295 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3297 struct task_struct *curr = current;
3298 struct held_lock *hlock, *prev_hlock;
3299 struct lock_class_stats *stats;
3301 int i, contention_point, contending_point;
3303 depth = curr->lockdep_depth;
3304 if (DEBUG_LOCKS_WARN_ON(!depth))
3308 for (i = depth-1; i >= 0; i--) {
3309 hlock = curr->held_locks + i;
3311 * We must not cross into another context:
3313 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3315 if (match_held_lock(hlock, lock))
3319 print_lock_contention_bug(curr, lock, ip);
3323 if (hlock->instance != lock)
3326 hlock->waittime_stamp = lockstat_clock();
3328 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3329 contending_point = lock_point(hlock_class(hlock)->contending_point,
3332 stats = get_lock_stats(hlock_class(hlock));
3333 if (contention_point < LOCKSTAT_POINTS)
3334 stats->contention_point[contention_point]++;
3335 if (contending_point < LOCKSTAT_POINTS)
3336 stats->contending_point[contending_point]++;
3337 if (lock->cpu != smp_processor_id())
3338 stats->bounces[bounce_contended + !!hlock->read]++;
3339 put_lock_stats(stats);
3343 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3345 struct task_struct *curr = current;
3346 struct held_lock *hlock, *prev_hlock;
3347 struct lock_class_stats *stats;
3349 u64 now, waittime = 0;
3352 depth = curr->lockdep_depth;
3353 if (DEBUG_LOCKS_WARN_ON(!depth))
3357 for (i = depth-1; i >= 0; i--) {
3358 hlock = curr->held_locks + i;
3360 * We must not cross into another context:
3362 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3364 if (match_held_lock(hlock, lock))
3368 print_lock_contention_bug(curr, lock, _RET_IP_);
3372 if (hlock->instance != lock)
3375 cpu = smp_processor_id();
3376 if (hlock->waittime_stamp) {
3377 now = lockstat_clock();
3378 waittime = now - hlock->waittime_stamp;
3379 hlock->holdtime_stamp = now;
3382 trace_lock_acquired(lock, ip, waittime);
3384 stats = get_lock_stats(hlock_class(hlock));
3387 lock_time_inc(&stats->read_waittime, waittime);
3389 lock_time_inc(&stats->write_waittime, waittime);
3391 if (lock->cpu != cpu)
3392 stats->bounces[bounce_acquired + !!hlock->read]++;
3393 put_lock_stats(stats);
3399 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3401 unsigned long flags;
3403 trace_lock_contended(lock, ip);
3405 if (unlikely(!lock_stat))
3408 if (unlikely(current->lockdep_recursion))
3411 raw_local_irq_save(flags);
3413 current->lockdep_recursion = 1;
3414 __lock_contended(lock, ip);
3415 current->lockdep_recursion = 0;
3416 raw_local_irq_restore(flags);
3418 EXPORT_SYMBOL_GPL(lock_contended);
3420 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3422 unsigned long flags;
3424 if (unlikely(!lock_stat))
3427 if (unlikely(current->lockdep_recursion))
3430 raw_local_irq_save(flags);
3432 current->lockdep_recursion = 1;
3433 __lock_acquired(lock, ip);
3434 current->lockdep_recursion = 0;
3435 raw_local_irq_restore(flags);
3437 EXPORT_SYMBOL_GPL(lock_acquired);
3441 * Used by the testsuite, sanitize the validator state
3442 * after a simulated failure:
3445 void lockdep_reset(void)
3447 unsigned long flags;
3450 raw_local_irq_save(flags);
3451 current->curr_chain_key = 0;
3452 current->lockdep_depth = 0;
3453 current->lockdep_recursion = 0;
3454 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3455 nr_hardirq_chains = 0;
3456 nr_softirq_chains = 0;
3457 nr_process_chains = 0;
3459 for (i = 0; i < CHAINHASH_SIZE; i++)
3460 INIT_LIST_HEAD(chainhash_table + i);
3461 raw_local_irq_restore(flags);
3464 static void zap_class(struct lock_class *class)
3469 * Remove all dependencies this lock is
3472 for (i = 0; i < nr_list_entries; i++) {
3473 if (list_entries[i].class == class)
3474 list_del_rcu(&list_entries[i].entry);
3477 * Unhash the class and remove it from the all_lock_classes list:
3479 list_del_rcu(&class->hash_entry);
3480 list_del_rcu(&class->lock_entry);
3485 static inline int within(const void *addr, void *start, unsigned long size)
3487 return addr >= start && addr < start + size;
3490 void lockdep_free_key_range(void *start, unsigned long size)
3492 struct lock_class *class, *next;
3493 struct list_head *head;
3494 unsigned long flags;
3498 raw_local_irq_save(flags);
3499 locked = graph_lock();
3502 * Unhash all classes that were created by this module:
3504 for (i = 0; i < CLASSHASH_SIZE; i++) {
3505 head = classhash_table + i;
3506 if (list_empty(head))
3508 list_for_each_entry_safe(class, next, head, hash_entry) {
3509 if (within(class->key, start, size))
3511 else if (within(class->name, start, size))
3518 raw_local_irq_restore(flags);
3521 void lockdep_reset_lock(struct lockdep_map *lock)
3523 struct lock_class *class, *next;
3524 struct list_head *head;
3525 unsigned long flags;
3529 raw_local_irq_save(flags);
3532 * Remove all classes this lock might have:
3534 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3536 * If the class exists we look it up and zap it:
3538 class = look_up_lock_class(lock, j);
3543 * Debug check: in the end all mapped classes should
3546 locked = graph_lock();
3547 for (i = 0; i < CLASSHASH_SIZE; i++) {
3548 head = classhash_table + i;
3549 if (list_empty(head))
3551 list_for_each_entry_safe(class, next, head, hash_entry) {
3552 if (unlikely(class == lock->class_cache)) {
3553 if (debug_locks_off_graph_unlock())
3563 raw_local_irq_restore(flags);
3566 void lockdep_init(void)
3571 * Some architectures have their own start_kernel()
3572 * code which calls lockdep_init(), while we also
3573 * call lockdep_init() from the start_kernel() itself,
3574 * and we want to initialize the hashes only once:
3576 if (lockdep_initialized)
3579 for (i = 0; i < CLASSHASH_SIZE; i++)
3580 INIT_LIST_HEAD(classhash_table + i);
3582 for (i = 0; i < CHAINHASH_SIZE; i++)
3583 INIT_LIST_HEAD(chainhash_table + i);
3585 lockdep_initialized = 1;
3588 void __init lockdep_info(void)
3590 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3592 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3593 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3594 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3595 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3596 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3597 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3598 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3600 printk(" memory used by lock dependency info: %lu kB\n",
3601 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3602 sizeof(struct list_head) * CLASSHASH_SIZE +
3603 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3604 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3605 sizeof(struct list_head) * CHAINHASH_SIZE
3606 #ifdef CONFIG_PROVE_LOCKING
3607 + sizeof(struct circular_queue)
3612 printk(" per task-struct memory footprint: %lu bytes\n",
3613 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3615 #ifdef CONFIG_DEBUG_LOCKDEP
3616 if (lockdep_init_error) {
3617 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3618 printk("Call stack leading to lockdep invocation was:\n");
3619 print_stack_trace(&lockdep_init_trace, 0);
3625 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3626 const void *mem_to, struct held_lock *hlock)
3628 if (!debug_locks_off())
3630 if (debug_locks_silent)
3633 printk("\n=========================\n");
3634 printk( "[ BUG: held lock freed! ]\n");
3635 printk( "-------------------------\n");
3636 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3637 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3639 lockdep_print_held_locks(curr);
3641 printk("\nstack backtrace:\n");
3645 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3646 const void* lock_from, unsigned long lock_len)
3648 return lock_from + lock_len <= mem_from ||
3649 mem_from + mem_len <= lock_from;
3653 * Called when kernel memory is freed (or unmapped), or if a lock
3654 * is destroyed or reinitialized - this code checks whether there is
3655 * any held lock in the memory range of <from> to <to>:
3657 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3659 struct task_struct *curr = current;
3660 struct held_lock *hlock;
3661 unsigned long flags;
3664 if (unlikely(!debug_locks))
3667 local_irq_save(flags);
3668 for (i = 0; i < curr->lockdep_depth; i++) {
3669 hlock = curr->held_locks + i;
3671 if (not_in_range(mem_from, mem_len, hlock->instance,
3672 sizeof(*hlock->instance)))
3675 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3678 local_irq_restore(flags);
3680 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3682 static void print_held_locks_bug(struct task_struct *curr)
3684 if (!debug_locks_off())
3686 if (debug_locks_silent)
3689 printk("\n=====================================\n");
3690 printk( "[ BUG: lock held at task exit time! ]\n");
3691 printk( "-------------------------------------\n");
3692 printk("%s/%d is exiting with locks still held!\n",
3693 curr->comm, task_pid_nr(curr));
3694 lockdep_print_held_locks(curr);
3696 printk("\nstack backtrace:\n");
3700 void debug_check_no_locks_held(struct task_struct *task)
3702 if (unlikely(task->lockdep_depth > 0))
3703 print_held_locks_bug(task);
3706 void debug_show_all_locks(void)
3708 struct task_struct *g, *p;
3712 if (unlikely(!debug_locks)) {
3713 printk("INFO: lockdep is turned off.\n");
3716 printk("\nShowing all locks held in the system:\n");
3719 * Here we try to get the tasklist_lock as hard as possible,
3720 * if not successful after 2 seconds we ignore it (but keep
3721 * trying). This is to enable a debug printout even if a
3722 * tasklist_lock-holding task deadlocks or crashes.
3725 if (!read_trylock(&tasklist_lock)) {
3727 printk("hm, tasklist_lock locked, retrying... ");
3730 printk(" #%d", 10-count);
3734 printk(" ignoring it.\n");
3738 printk(KERN_CONT " locked it.\n");
3741 do_each_thread(g, p) {
3743 * It's not reliable to print a task's held locks
3744 * if it's not sleeping (or if it's not the current
3747 if (p->state == TASK_RUNNING && p != current)
3749 if (p->lockdep_depth)
3750 lockdep_print_held_locks(p);
3752 if (read_trylock(&tasklist_lock))
3754 } while_each_thread(g, p);
3757 printk("=============================================\n\n");
3760 read_unlock(&tasklist_lock);
3762 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3765 * Careful: only use this function if you are sure that
3766 * the task cannot run in parallel!
3768 void __debug_show_held_locks(struct task_struct *task)
3770 if (unlikely(!debug_locks)) {
3771 printk("INFO: lockdep is turned off.\n");
3774 lockdep_print_held_locks(task);
3776 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3778 void debug_show_held_locks(struct task_struct *task)
3780 __debug_show_held_locks(task);
3782 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3784 void lockdep_sys_exit(void)
3786 struct task_struct *curr = current;
3788 if (unlikely(curr->lockdep_depth)) {
3789 if (!debug_locks_off())
3791 printk("\n================================================\n");
3792 printk( "[ BUG: lock held when returning to user space! ]\n");
3793 printk( "------------------------------------------------\n");
3794 printk("%s/%d is leaving the kernel with locks still held!\n",
3795 curr->comm, curr->pid);
3796 lockdep_print_held_locks(curr);
3800 void lockdep_rcu_dereference(const char *file, const int line)
3802 struct task_struct *curr = current;
3804 if (!debug_locks_off())
3806 printk("\n===================================================\n");
3807 printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3808 printk( "---------------------------------------------------\n");
3809 printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3811 printk("\nother info that might help us debug this:\n\n");
3812 lockdep_print_held_locks(curr);
3813 printk("\nstack backtrace:\n");
3816 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);