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
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/sched/clock.h>
32 #include <linux/delay.h>
33 #include <linux/module.h>
34 #include <linux/proc_fs.h>
35 #include <linux/seq_file.h>
36 #include <linux/spinlock.h>
37 #include <linux/kallsyms.h>
38 #include <linux/interrupt.h>
39 #include <linux/stacktrace.h>
40 #include <linux/debug_locks.h>
41 #include <linux/irqflags.h>
42 #include <linux/utsname.h>
43 #include <linux/hash.h>
44 #include <linux/ftrace.h>
45 #include <linux/stringify.h>
46 #include <linux/bitops.h>
47 #include <linux/gfp.h>
48 #include <linux/kmemcheck.h>
49 #include <linux/random.h>
50 #include <linux/jhash.h>
52 #include <asm/sections.h>
54 #include "lockdep_internals.h"
56 #define CREATE_TRACE_POINTS
57 #include <trace/events/lock.h>
59 #ifdef CONFIG_PROVE_LOCKING
60 int prove_locking = 1;
61 module_param(prove_locking, int, 0644);
63 #define prove_locking 0
66 #ifdef CONFIG_LOCK_STAT
68 module_param(lock_stat, int, 0644);
74 * lockdep_lock: protects the lockdep graph, the hashes and the
75 * class/list/hash allocators.
77 * This is one of the rare exceptions where it's justified
78 * to use a raw spinlock - we really dont want the spinlock
79 * code to recurse back into the lockdep code...
81 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
83 static int graph_lock(void)
85 arch_spin_lock(&lockdep_lock);
87 * Make sure that if another CPU detected a bug while
88 * walking the graph we dont change it (while the other
89 * CPU is busy printing out stuff with the graph lock
93 arch_spin_unlock(&lockdep_lock);
96 /* prevent any recursions within lockdep from causing deadlocks */
97 current->lockdep_recursion++;
101 static inline int graph_unlock(void)
103 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
105 * The lockdep graph lock isn't locked while we expect it to
106 * be, we're confused now, bye!
108 return DEBUG_LOCKS_WARN_ON(1);
111 current->lockdep_recursion--;
112 arch_spin_unlock(&lockdep_lock);
117 * Turn lock debugging off and return with 0 if it was off already,
118 * and also release the graph lock:
120 static inline int debug_locks_off_graph_unlock(void)
122 int ret = debug_locks_off();
124 arch_spin_unlock(&lockdep_lock);
129 unsigned long nr_list_entries;
130 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
133 * All data structures here are protected by the global debug_lock.
135 * Mutex key structs only get allocated, once during bootup, and never
136 * get freed - this significantly simplifies the debugging code.
138 unsigned long nr_lock_classes;
139 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
141 static inline struct lock_class *hlock_class(struct held_lock *hlock)
143 if (!hlock->class_idx) {
145 * Someone passed in garbage, we give up.
147 DEBUG_LOCKS_WARN_ON(1);
150 return lock_classes + hlock->class_idx - 1;
153 #ifdef CONFIG_LOCK_STAT
154 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
156 static inline u64 lockstat_clock(void)
158 return local_clock();
161 static int lock_point(unsigned long points[], unsigned long ip)
165 for (i = 0; i < LOCKSTAT_POINTS; i++) {
166 if (points[i] == 0) {
177 static void lock_time_inc(struct lock_time *lt, u64 time)
182 if (time < lt->min || !lt->nr)
189 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
194 if (src->max > dst->max)
197 if (src->min < dst->min || !dst->nr)
200 dst->total += src->total;
204 struct lock_class_stats lock_stats(struct lock_class *class)
206 struct lock_class_stats stats;
209 memset(&stats, 0, sizeof(struct lock_class_stats));
210 for_each_possible_cpu(cpu) {
211 struct lock_class_stats *pcs =
212 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
214 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
215 stats.contention_point[i] += pcs->contention_point[i];
217 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
218 stats.contending_point[i] += pcs->contending_point[i];
220 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
221 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
223 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
224 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
226 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
227 stats.bounces[i] += pcs->bounces[i];
233 void clear_lock_stats(struct lock_class *class)
237 for_each_possible_cpu(cpu) {
238 struct lock_class_stats *cpu_stats =
239 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
241 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
243 memset(class->contention_point, 0, sizeof(class->contention_point));
244 memset(class->contending_point, 0, sizeof(class->contending_point));
247 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
249 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
252 static void put_lock_stats(struct lock_class_stats *stats)
254 put_cpu_var(cpu_lock_stats);
257 static void lock_release_holdtime(struct held_lock *hlock)
259 struct lock_class_stats *stats;
265 holdtime = lockstat_clock() - hlock->holdtime_stamp;
267 stats = get_lock_stats(hlock_class(hlock));
269 lock_time_inc(&stats->read_holdtime, holdtime);
271 lock_time_inc(&stats->write_holdtime, holdtime);
272 put_lock_stats(stats);
275 static inline void lock_release_holdtime(struct held_lock *hlock)
281 * We keep a global list of all lock classes. The list only grows,
282 * never shrinks. The list is only accessed with the lockdep
283 * spinlock lock held.
285 LIST_HEAD(all_lock_classes);
288 * The lockdep classes are in a hash-table as well, for fast lookup:
290 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
291 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
292 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
293 #define classhashentry(key) (classhash_table + __classhashfn((key)))
295 static struct hlist_head classhash_table[CLASSHASH_SIZE];
298 * We put the lock dependency chains into a hash-table as well, to cache
301 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
302 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
303 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
304 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
306 static struct hlist_head chainhash_table[CHAINHASH_SIZE];
309 * The hash key of the lock dependency chains is a hash itself too:
310 * it's a hash of all locks taken up to that lock, including that lock.
311 * It's a 64-bit hash, because it's important for the keys to be
314 static inline u64 iterate_chain_key(u64 key, u32 idx)
316 u32 k0 = key, k1 = key >> 32;
318 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
320 return k0 | (u64)k1 << 32;
323 void lockdep_off(void)
325 current->lockdep_recursion++;
327 EXPORT_SYMBOL(lockdep_off);
329 void lockdep_on(void)
331 current->lockdep_recursion--;
333 EXPORT_SYMBOL(lockdep_on);
336 * Debugging switches:
340 #define VERY_VERBOSE 0
343 # define HARDIRQ_VERBOSE 1
344 # define SOFTIRQ_VERBOSE 1
345 # define RECLAIM_VERBOSE 1
347 # define HARDIRQ_VERBOSE 0
348 # define SOFTIRQ_VERBOSE 0
349 # define RECLAIM_VERBOSE 0
352 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
354 * Quick filtering for interesting events:
356 static int class_filter(struct lock_class *class)
360 if (class->name_version == 1 &&
361 !strcmp(class->name, "lockname"))
363 if (class->name_version == 1 &&
364 !strcmp(class->name, "&struct->lockfield"))
367 /* Filter everything else. 1 would be to allow everything else */
372 static int verbose(struct lock_class *class)
375 return class_filter(class);
381 * Stack-trace: tightly packed array of stack backtrace
382 * addresses. Protected by the graph_lock.
384 unsigned long nr_stack_trace_entries;
385 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
387 static void print_lockdep_off(const char *bug_msg)
389 printk(KERN_DEBUG "%s\n", bug_msg);
390 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
391 #ifdef CONFIG_LOCK_STAT
392 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
396 static int save_trace(struct stack_trace *trace)
398 trace->nr_entries = 0;
399 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
400 trace->entries = stack_trace + nr_stack_trace_entries;
404 save_stack_trace(trace);
407 * Some daft arches put -1 at the end to indicate its a full trace.
409 * <rant> this is buggy anyway, since it takes a whole extra entry so a
410 * complete trace that maxes out the entries provided will be reported
411 * as incomplete, friggin useless </rant>
413 if (trace->nr_entries != 0 &&
414 trace->entries[trace->nr_entries-1] == ULONG_MAX)
417 trace->max_entries = trace->nr_entries;
419 nr_stack_trace_entries += trace->nr_entries;
421 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
422 if (!debug_locks_off_graph_unlock())
425 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
434 unsigned int nr_hardirq_chains;
435 unsigned int nr_softirq_chains;
436 unsigned int nr_process_chains;
437 unsigned int max_lockdep_depth;
439 #ifdef CONFIG_DEBUG_LOCKDEP
441 * Various lockdep statistics:
443 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
450 #define __USAGE(__STATE) \
451 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
452 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
453 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
454 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
456 static const char *usage_str[] =
458 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
459 #include "lockdep_states.h"
461 [LOCK_USED] = "INITIAL USE",
464 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
466 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
469 static inline unsigned long lock_flag(enum lock_usage_bit bit)
474 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
478 if (class->usage_mask & lock_flag(bit + 2))
480 if (class->usage_mask & lock_flag(bit)) {
482 if (class->usage_mask & lock_flag(bit + 2))
489 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
493 #define LOCKDEP_STATE(__STATE) \
494 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
495 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
496 #include "lockdep_states.h"
502 static void __print_lock_name(struct lock_class *class)
504 char str[KSYM_NAME_LEN];
509 name = __get_key_name(class->key, str);
510 printk(KERN_CONT "%s", name);
512 printk(KERN_CONT "%s", name);
513 if (class->name_version > 1)
514 printk(KERN_CONT "#%d", class->name_version);
516 printk(KERN_CONT "/%d", class->subclass);
520 static void print_lock_name(struct lock_class *class)
522 char usage[LOCK_USAGE_CHARS];
524 get_usage_chars(class, usage);
526 printk(KERN_CONT " (");
527 __print_lock_name(class);
528 printk(KERN_CONT "){%s}", usage);
531 static void print_lockdep_cache(struct lockdep_map *lock)
534 char str[KSYM_NAME_LEN];
538 name = __get_key_name(lock->key->subkeys, str);
540 printk(KERN_CONT "%s", name);
543 static void print_lock(struct held_lock *hlock)
546 * We can be called locklessly through debug_show_all_locks() so be
547 * extra careful, the hlock might have been released and cleared.
549 unsigned int class_idx = hlock->class_idx;
551 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
554 if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
555 printk(KERN_CONT "<RELEASED>\n");
559 print_lock_name(lock_classes + class_idx - 1);
560 printk(KERN_CONT ", at: [<%p>] %pS\n",
561 (void *)hlock->acquire_ip, (void *)hlock->acquire_ip);
564 static void lockdep_print_held_locks(struct task_struct *curr)
566 int i, depth = curr->lockdep_depth;
569 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
572 printk("%d lock%s held by %s/%d:\n",
573 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
575 for (i = 0; i < depth; i++) {
577 print_lock(curr->held_locks + i);
581 static void print_kernel_ident(void)
583 printk("%s %.*s %s\n", init_utsname()->release,
584 (int)strcspn(init_utsname()->version, " "),
585 init_utsname()->version,
589 static int very_verbose(struct lock_class *class)
592 return class_filter(class);
598 * Is this the address of a static object:
601 static int static_obj(void *obj)
603 unsigned long start = (unsigned long) &_stext,
604 end = (unsigned long) &_end,
605 addr = (unsigned long) obj;
610 if ((addr >= start) && (addr < end))
613 if (arch_is_kernel_data(addr))
617 * in-kernel percpu var?
619 if (is_kernel_percpu_address(addr))
623 * module static or percpu var?
625 return is_module_address(addr) || is_module_percpu_address(addr);
630 * To make lock name printouts unique, we calculate a unique
631 * class->name_version generation counter:
633 static int count_matching_names(struct lock_class *new_class)
635 struct lock_class *class;
638 if (!new_class->name)
641 list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
642 if (new_class->key - new_class->subclass == class->key)
643 return class->name_version;
644 if (class->name && !strcmp(class->name, new_class->name))
645 count = max(count, class->name_version);
652 * Register a lock's class in the hash-table, if the class is not present
653 * yet. Otherwise we look it up. We cache the result in the lock object
654 * itself, so actual lookup of the hash should be once per lock object.
656 static inline struct lock_class *
657 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
659 struct lockdep_subclass_key *key;
660 struct hlist_head *hash_head;
661 struct lock_class *class;
663 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
666 "BUG: looking up invalid subclass: %u\n", subclass);
668 "turning off the locking correctness validator.\n");
674 * Static locks do not have their class-keys yet - for them the key
675 * is the lock object itself:
677 if (unlikely(!lock->key))
678 lock->key = (void *)lock;
681 * NOTE: the class-key must be unique. For dynamic locks, a static
682 * lock_class_key variable is passed in through the mutex_init()
683 * (or spin_lock_init()) call - which acts as the key. For static
684 * locks we use the lock object itself as the key.
686 BUILD_BUG_ON(sizeof(struct lock_class_key) >
687 sizeof(struct lockdep_map));
689 key = lock->key->subkeys + subclass;
691 hash_head = classhashentry(key);
694 * We do an RCU walk of the hash, see lockdep_free_key_range().
696 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
699 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
700 if (class->key == key) {
702 * Huh! same key, different name? Did someone trample
703 * on some memory? We're most confused.
705 WARN_ON_ONCE(class->name != lock->name);
714 * Register a lock's class in the hash-table, if the class is not present
715 * yet. Otherwise we look it up. We cache the result in the lock object
716 * itself, so actual lookup of the hash should be once per lock object.
718 static struct lock_class *
719 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
721 struct lockdep_subclass_key *key;
722 struct hlist_head *hash_head;
723 struct lock_class *class;
725 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
727 class = look_up_lock_class(lock, subclass);
729 goto out_set_class_cache;
732 * Debug-check: all keys must be persistent!
734 if (!static_obj(lock->key)) {
736 printk("INFO: trying to register non-static key.\n");
737 printk("the code is fine but needs lockdep annotation.\n");
738 printk("turning off the locking correctness validator.\n");
744 key = lock->key->subkeys + subclass;
745 hash_head = classhashentry(key);
751 * We have to do the hash-walk again, to avoid races
754 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
755 if (class->key == key)
760 * Allocate a new key from the static array, and add it to
763 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
764 if (!debug_locks_off_graph_unlock()) {
768 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
772 class = lock_classes + nr_lock_classes++;
773 debug_atomic_inc(nr_unused_locks);
775 class->name = lock->name;
776 class->subclass = subclass;
777 INIT_LIST_HEAD(&class->lock_entry);
778 INIT_LIST_HEAD(&class->locks_before);
779 INIT_LIST_HEAD(&class->locks_after);
780 class->name_version = count_matching_names(class);
782 * We use RCU's safe list-add method to make
783 * parallel walking of the hash-list safe:
785 hlist_add_head_rcu(&class->hash_entry, hash_head);
787 * Add it to the global list of classes:
789 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
791 if (verbose(class)) {
794 printk("\nnew class %p: %s", class->key, class->name);
795 if (class->name_version > 1)
796 printk(KERN_CONT "#%d", class->name_version);
797 printk(KERN_CONT "\n");
808 if (!subclass || force)
809 lock->class_cache[0] = class;
810 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
811 lock->class_cache[subclass] = class;
814 * Hash collision, did we smoke some? We found a class with a matching
815 * hash but the subclass -- which is hashed in -- didn't match.
817 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
823 #ifdef CONFIG_PROVE_LOCKING
825 * Allocate a lockdep entry. (assumes the graph_lock held, returns
826 * with NULL on failure)
828 static struct lock_list *alloc_list_entry(void)
830 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
831 if (!debug_locks_off_graph_unlock())
834 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
838 return list_entries + nr_list_entries++;
842 * Add a new dependency to the head of the list:
844 static int add_lock_to_list(struct lock_class *this, struct list_head *head,
845 unsigned long ip, int distance,
846 struct stack_trace *trace)
848 struct lock_list *entry;
850 * Lock not present yet - get a new dependency struct and
851 * add it to the list:
853 entry = alloc_list_entry();
858 entry->distance = distance;
859 entry->trace = *trace;
861 * Both allocation and removal are done under the graph lock; but
862 * iteration is under RCU-sched; see look_up_lock_class() and
863 * lockdep_free_key_range().
865 list_add_tail_rcu(&entry->entry, head);
871 * For good efficiency of modular, we use power of 2
873 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
874 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
877 * The circular_queue and helpers is used to implement the
878 * breadth-first search(BFS)algorithem, by which we can build
879 * the shortest path from the next lock to be acquired to the
880 * previous held lock if there is a circular between them.
882 struct circular_queue {
883 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
884 unsigned int front, rear;
887 static struct circular_queue lock_cq;
889 unsigned int max_bfs_queue_depth;
891 static unsigned int lockdep_dependency_gen_id;
893 static inline void __cq_init(struct circular_queue *cq)
895 cq->front = cq->rear = 0;
896 lockdep_dependency_gen_id++;
899 static inline int __cq_empty(struct circular_queue *cq)
901 return (cq->front == cq->rear);
904 static inline int __cq_full(struct circular_queue *cq)
906 return ((cq->rear + 1) & CQ_MASK) == cq->front;
909 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
914 cq->element[cq->rear] = elem;
915 cq->rear = (cq->rear + 1) & CQ_MASK;
919 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
924 *elem = cq->element[cq->front];
925 cq->front = (cq->front + 1) & CQ_MASK;
929 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
931 return (cq->rear - cq->front) & CQ_MASK;
934 static inline void mark_lock_accessed(struct lock_list *lock,
935 struct lock_list *parent)
939 nr = lock - list_entries;
940 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
941 lock->parent = parent;
942 lock->class->dep_gen_id = lockdep_dependency_gen_id;
945 static inline unsigned long lock_accessed(struct lock_list *lock)
949 nr = lock - list_entries;
950 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
951 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
954 static inline struct lock_list *get_lock_parent(struct lock_list *child)
956 return child->parent;
959 static inline int get_lock_depth(struct lock_list *child)
962 struct lock_list *parent;
964 while ((parent = get_lock_parent(child))) {
971 static int __bfs(struct lock_list *source_entry,
973 int (*match)(struct lock_list *entry, void *data),
974 struct lock_list **target_entry,
977 struct lock_list *entry;
978 struct list_head *head;
979 struct circular_queue *cq = &lock_cq;
982 if (match(source_entry, data)) {
983 *target_entry = source_entry;
989 head = &source_entry->class->locks_after;
991 head = &source_entry->class->locks_before;
993 if (list_empty(head))
997 __cq_enqueue(cq, (unsigned long)source_entry);
999 while (!__cq_empty(cq)) {
1000 struct lock_list *lock;
1002 __cq_dequeue(cq, (unsigned long *)&lock);
1010 head = &lock->class->locks_after;
1012 head = &lock->class->locks_before;
1014 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1016 list_for_each_entry_rcu(entry, head, entry) {
1017 if (!lock_accessed(entry)) {
1018 unsigned int cq_depth;
1019 mark_lock_accessed(entry, lock);
1020 if (match(entry, data)) {
1021 *target_entry = entry;
1026 if (__cq_enqueue(cq, (unsigned long)entry)) {
1030 cq_depth = __cq_get_elem_count(cq);
1031 if (max_bfs_queue_depth < cq_depth)
1032 max_bfs_queue_depth = cq_depth;
1040 static inline int __bfs_forwards(struct lock_list *src_entry,
1042 int (*match)(struct lock_list *entry, void *data),
1043 struct lock_list **target_entry)
1045 return __bfs(src_entry, data, match, target_entry, 1);
1049 static inline int __bfs_backwards(struct lock_list *src_entry,
1051 int (*match)(struct lock_list *entry, void *data),
1052 struct lock_list **target_entry)
1054 return __bfs(src_entry, data, match, target_entry, 0);
1059 * Recursive, forwards-direction lock-dependency checking, used for
1060 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1065 * Print a dependency chain entry (this is only done when a deadlock
1066 * has been detected):
1069 print_circular_bug_entry(struct lock_list *target, int depth)
1071 if (debug_locks_silent)
1073 printk("\n-> #%u", depth);
1074 print_lock_name(target->class);
1075 printk(KERN_CONT ":\n");
1076 print_stack_trace(&target->trace, 6);
1082 print_circular_lock_scenario(struct held_lock *src,
1083 struct held_lock *tgt,
1084 struct lock_list *prt)
1086 struct lock_class *source = hlock_class(src);
1087 struct lock_class *target = hlock_class(tgt);
1088 struct lock_class *parent = prt->class;
1091 * A direct locking problem where unsafe_class lock is taken
1092 * directly by safe_class lock, then all we need to show
1093 * is the deadlock scenario, as it is obvious that the
1094 * unsafe lock is taken under the safe lock.
1096 * But if there is a chain instead, where the safe lock takes
1097 * an intermediate lock (middle_class) where this lock is
1098 * not the same as the safe lock, then the lock chain is
1099 * used to describe the problem. Otherwise we would need
1100 * to show a different CPU case for each link in the chain
1101 * from the safe_class lock to the unsafe_class lock.
1103 if (parent != source) {
1104 printk("Chain exists of:\n ");
1105 __print_lock_name(source);
1106 printk(KERN_CONT " --> ");
1107 __print_lock_name(parent);
1108 printk(KERN_CONT " --> ");
1109 __print_lock_name(target);
1110 printk(KERN_CONT "\n\n");
1113 printk(" Possible unsafe locking scenario:\n\n");
1114 printk(" CPU0 CPU1\n");
1115 printk(" ---- ----\n");
1117 __print_lock_name(target);
1118 printk(KERN_CONT ");\n");
1120 __print_lock_name(parent);
1121 printk(KERN_CONT ");\n");
1123 __print_lock_name(target);
1124 printk(KERN_CONT ");\n");
1126 __print_lock_name(source);
1127 printk(KERN_CONT ");\n");
1128 printk("\n *** DEADLOCK ***\n\n");
1132 * When a circular dependency is detected, print the
1136 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1137 struct held_lock *check_src,
1138 struct held_lock *check_tgt)
1140 struct task_struct *curr = current;
1142 if (debug_locks_silent)
1146 printk("======================================================\n");
1147 printk("[ INFO: possible circular locking dependency detected ]\n");
1148 print_kernel_ident();
1149 printk("-------------------------------------------------------\n");
1150 printk("%s/%d is trying to acquire lock:\n",
1151 curr->comm, task_pid_nr(curr));
1152 print_lock(check_src);
1153 printk("\nbut task is already holding lock:\n");
1154 print_lock(check_tgt);
1155 printk("\nwhich lock already depends on the new lock.\n\n");
1156 printk("\nthe existing dependency chain (in reverse order) is:\n");
1158 print_circular_bug_entry(entry, depth);
1163 static inline int class_equal(struct lock_list *entry, void *data)
1165 return entry->class == data;
1168 static noinline int print_circular_bug(struct lock_list *this,
1169 struct lock_list *target,
1170 struct held_lock *check_src,
1171 struct held_lock *check_tgt)
1173 struct task_struct *curr = current;
1174 struct lock_list *parent;
1175 struct lock_list *first_parent;
1178 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1181 if (!save_trace(&this->trace))
1184 depth = get_lock_depth(target);
1186 print_circular_bug_header(target, depth, check_src, check_tgt);
1188 parent = get_lock_parent(target);
1189 first_parent = parent;
1192 print_circular_bug_entry(parent, --depth);
1193 parent = get_lock_parent(parent);
1196 printk("\nother info that might help us debug this:\n\n");
1197 print_circular_lock_scenario(check_src, check_tgt,
1200 lockdep_print_held_locks(curr);
1202 printk("\nstack backtrace:\n");
1208 static noinline int print_bfs_bug(int ret)
1210 if (!debug_locks_off_graph_unlock())
1214 * Breadth-first-search failed, graph got corrupted?
1216 WARN(1, "lockdep bfs error:%d\n", ret);
1221 static int noop_count(struct lock_list *entry, void *data)
1223 (*(unsigned long *)data)++;
1227 static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1229 unsigned long count = 0;
1230 struct lock_list *uninitialized_var(target_entry);
1232 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1236 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1238 unsigned long ret, flags;
1239 struct lock_list this;
1244 local_irq_save(flags);
1245 arch_spin_lock(&lockdep_lock);
1246 ret = __lockdep_count_forward_deps(&this);
1247 arch_spin_unlock(&lockdep_lock);
1248 local_irq_restore(flags);
1253 static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1255 unsigned long count = 0;
1256 struct lock_list *uninitialized_var(target_entry);
1258 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1263 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1265 unsigned long ret, flags;
1266 struct lock_list this;
1271 local_irq_save(flags);
1272 arch_spin_lock(&lockdep_lock);
1273 ret = __lockdep_count_backward_deps(&this);
1274 arch_spin_unlock(&lockdep_lock);
1275 local_irq_restore(flags);
1281 * Prove that the dependency graph starting at <entry> can not
1282 * lead to <target>. Print an error and return 0 if it does.
1285 check_noncircular(struct lock_list *root, struct lock_class *target,
1286 struct lock_list **target_entry)
1290 debug_atomic_inc(nr_cyclic_checks);
1292 result = __bfs_forwards(root, target, class_equal, target_entry);
1297 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1299 * Forwards and backwards subgraph searching, for the purposes of
1300 * proving that two subgraphs can be connected by a new dependency
1301 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1304 static inline int usage_match(struct lock_list *entry, void *bit)
1306 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1312 * Find a node in the forwards-direction dependency sub-graph starting
1313 * at @root->class that matches @bit.
1315 * Return 0 if such a node exists in the subgraph, and put that node
1316 * into *@target_entry.
1318 * Return 1 otherwise and keep *@target_entry unchanged.
1319 * Return <0 on error.
1322 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1323 struct lock_list **target_entry)
1327 debug_atomic_inc(nr_find_usage_forwards_checks);
1329 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1335 * Find a node in the backwards-direction dependency sub-graph starting
1336 * at @root->class that matches @bit.
1338 * Return 0 if such a node exists in the subgraph, and put that node
1339 * into *@target_entry.
1341 * Return 1 otherwise and keep *@target_entry unchanged.
1342 * Return <0 on error.
1345 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1346 struct lock_list **target_entry)
1350 debug_atomic_inc(nr_find_usage_backwards_checks);
1352 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1357 static void print_lock_class_header(struct lock_class *class, int depth)
1361 printk("%*s->", depth, "");
1362 print_lock_name(class);
1363 printk(KERN_CONT " ops: %lu", class->ops);
1364 printk(KERN_CONT " {\n");
1366 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1367 if (class->usage_mask & (1 << bit)) {
1370 len += printk("%*s %s", depth, "", usage_str[bit]);
1371 len += printk(KERN_CONT " at:\n");
1372 print_stack_trace(class->usage_traces + bit, len);
1375 printk("%*s }\n", depth, "");
1377 printk("%*s ... key at: [<%p>] %pS\n",
1378 depth, "", class->key, class->key);
1382 * printk the shortest lock dependencies from @start to @end in reverse order:
1385 print_shortest_lock_dependencies(struct lock_list *leaf,
1386 struct lock_list *root)
1388 struct lock_list *entry = leaf;
1391 /*compute depth from generated tree by BFS*/
1392 depth = get_lock_depth(leaf);
1395 print_lock_class_header(entry->class, depth);
1396 printk("%*s ... acquired at:\n", depth, "");
1397 print_stack_trace(&entry->trace, 2);
1400 if (depth == 0 && (entry != root)) {
1401 printk("lockdep:%s bad path found in chain graph\n", __func__);
1405 entry = get_lock_parent(entry);
1407 } while (entry && (depth >= 0));
1413 print_irq_lock_scenario(struct lock_list *safe_entry,
1414 struct lock_list *unsafe_entry,
1415 struct lock_class *prev_class,
1416 struct lock_class *next_class)
1418 struct lock_class *safe_class = safe_entry->class;
1419 struct lock_class *unsafe_class = unsafe_entry->class;
1420 struct lock_class *middle_class = prev_class;
1422 if (middle_class == safe_class)
1423 middle_class = next_class;
1426 * A direct locking problem where unsafe_class lock is taken
1427 * directly by safe_class lock, then all we need to show
1428 * is the deadlock scenario, as it is obvious that the
1429 * unsafe lock is taken under the safe lock.
1431 * But if there is a chain instead, where the safe lock takes
1432 * an intermediate lock (middle_class) where this lock is
1433 * not the same as the safe lock, then the lock chain is
1434 * used to describe the problem. Otherwise we would need
1435 * to show a different CPU case for each link in the chain
1436 * from the safe_class lock to the unsafe_class lock.
1438 if (middle_class != unsafe_class) {
1439 printk("Chain exists of:\n ");
1440 __print_lock_name(safe_class);
1441 printk(KERN_CONT " --> ");
1442 __print_lock_name(middle_class);
1443 printk(KERN_CONT " --> ");
1444 __print_lock_name(unsafe_class);
1445 printk(KERN_CONT "\n\n");
1448 printk(" Possible interrupt unsafe locking scenario:\n\n");
1449 printk(" CPU0 CPU1\n");
1450 printk(" ---- ----\n");
1452 __print_lock_name(unsafe_class);
1453 printk(KERN_CONT ");\n");
1454 printk(" local_irq_disable();\n");
1456 __print_lock_name(safe_class);
1457 printk(KERN_CONT ");\n");
1459 __print_lock_name(middle_class);
1460 printk(KERN_CONT ");\n");
1461 printk(" <Interrupt>\n");
1463 __print_lock_name(safe_class);
1464 printk(KERN_CONT ");\n");
1465 printk("\n *** DEADLOCK ***\n\n");
1469 print_bad_irq_dependency(struct task_struct *curr,
1470 struct lock_list *prev_root,
1471 struct lock_list *next_root,
1472 struct lock_list *backwards_entry,
1473 struct lock_list *forwards_entry,
1474 struct held_lock *prev,
1475 struct held_lock *next,
1476 enum lock_usage_bit bit1,
1477 enum lock_usage_bit bit2,
1478 const char *irqclass)
1480 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1484 printk("======================================================\n");
1485 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1486 irqclass, irqclass);
1487 print_kernel_ident();
1488 printk("------------------------------------------------------\n");
1489 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1490 curr->comm, task_pid_nr(curr),
1491 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1492 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1493 curr->hardirqs_enabled,
1494 curr->softirqs_enabled);
1497 printk("\nand this task is already holding:\n");
1499 printk("which would create a new lock dependency:\n");
1500 print_lock_name(hlock_class(prev));
1501 printk(KERN_CONT " ->");
1502 print_lock_name(hlock_class(next));
1503 printk(KERN_CONT "\n");
1505 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1507 print_lock_name(backwards_entry->class);
1508 printk("\n... which became %s-irq-safe at:\n", irqclass);
1510 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1512 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1513 print_lock_name(forwards_entry->class);
1514 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1517 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1519 printk("\nother info that might help us debug this:\n\n");
1520 print_irq_lock_scenario(backwards_entry, forwards_entry,
1521 hlock_class(prev), hlock_class(next));
1523 lockdep_print_held_locks(curr);
1525 printk("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
1526 if (!save_trace(&prev_root->trace))
1528 print_shortest_lock_dependencies(backwards_entry, prev_root);
1530 printk("\nthe dependencies between the lock to be acquired");
1531 printk(" and %s-irq-unsafe lock:\n", irqclass);
1532 if (!save_trace(&next_root->trace))
1534 print_shortest_lock_dependencies(forwards_entry, next_root);
1536 printk("\nstack backtrace:\n");
1543 check_usage(struct task_struct *curr, struct held_lock *prev,
1544 struct held_lock *next, enum lock_usage_bit bit_backwards,
1545 enum lock_usage_bit bit_forwards, const char *irqclass)
1548 struct lock_list this, that;
1549 struct lock_list *uninitialized_var(target_entry);
1550 struct lock_list *uninitialized_var(target_entry1);
1554 this.class = hlock_class(prev);
1555 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1557 return print_bfs_bug(ret);
1562 that.class = hlock_class(next);
1563 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1565 return print_bfs_bug(ret);
1569 return print_bad_irq_dependency(curr, &this, &that,
1570 target_entry, target_entry1,
1572 bit_backwards, bit_forwards, irqclass);
1575 static const char *state_names[] = {
1576 #define LOCKDEP_STATE(__STATE) \
1577 __stringify(__STATE),
1578 #include "lockdep_states.h"
1579 #undef LOCKDEP_STATE
1582 static const char *state_rnames[] = {
1583 #define LOCKDEP_STATE(__STATE) \
1584 __stringify(__STATE)"-READ",
1585 #include "lockdep_states.h"
1586 #undef LOCKDEP_STATE
1589 static inline const char *state_name(enum lock_usage_bit bit)
1591 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1594 static int exclusive_bit(int new_bit)
1602 * bit 0 - write/read
1603 * bit 1 - used_in/enabled
1607 int state = new_bit & ~3;
1608 int dir = new_bit & 2;
1611 * keep state, bit flip the direction and strip read.
1613 return state | (dir ^ 2);
1616 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1617 struct held_lock *next, enum lock_usage_bit bit)
1620 * Prove that the new dependency does not connect a hardirq-safe
1621 * lock with a hardirq-unsafe lock - to achieve this we search
1622 * the backwards-subgraph starting at <prev>, and the
1623 * forwards-subgraph starting at <next>:
1625 if (!check_usage(curr, prev, next, bit,
1626 exclusive_bit(bit), state_name(bit)))
1632 * Prove that the new dependency does not connect a hardirq-safe-read
1633 * lock with a hardirq-unsafe lock - to achieve this we search
1634 * the backwards-subgraph starting at <prev>, and the
1635 * forwards-subgraph starting at <next>:
1637 if (!check_usage(curr, prev, next, bit,
1638 exclusive_bit(bit), state_name(bit)))
1645 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1646 struct held_lock *next)
1648 #define LOCKDEP_STATE(__STATE) \
1649 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1651 #include "lockdep_states.h"
1652 #undef LOCKDEP_STATE
1657 static void inc_chains(void)
1659 if (current->hardirq_context)
1660 nr_hardirq_chains++;
1662 if (current->softirq_context)
1663 nr_softirq_chains++;
1665 nr_process_chains++;
1672 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1673 struct held_lock *next)
1678 static inline void inc_chains(void)
1680 nr_process_chains++;
1686 print_deadlock_scenario(struct held_lock *nxt,
1687 struct held_lock *prv)
1689 struct lock_class *next = hlock_class(nxt);
1690 struct lock_class *prev = hlock_class(prv);
1692 printk(" Possible unsafe locking scenario:\n\n");
1696 __print_lock_name(prev);
1697 printk(KERN_CONT ");\n");
1699 __print_lock_name(next);
1700 printk(KERN_CONT ");\n");
1701 printk("\n *** DEADLOCK ***\n\n");
1702 printk(" May be due to missing lock nesting notation\n\n");
1706 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1707 struct held_lock *next)
1709 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1713 printk("=============================================\n");
1714 printk("[ INFO: possible recursive locking detected ]\n");
1715 print_kernel_ident();
1716 printk("---------------------------------------------\n");
1717 printk("%s/%d is trying to acquire lock:\n",
1718 curr->comm, task_pid_nr(curr));
1720 printk("\nbut task is already holding lock:\n");
1723 printk("\nother info that might help us debug this:\n");
1724 print_deadlock_scenario(next, prev);
1725 lockdep_print_held_locks(curr);
1727 printk("\nstack backtrace:\n");
1734 * Check whether we are holding such a class already.
1736 * (Note that this has to be done separately, because the graph cannot
1737 * detect such classes of deadlocks.)
1739 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1742 check_deadlock(struct task_struct *curr, struct held_lock *next,
1743 struct lockdep_map *next_instance, int read)
1745 struct held_lock *prev;
1746 struct held_lock *nest = NULL;
1749 for (i = 0; i < curr->lockdep_depth; i++) {
1750 prev = curr->held_locks + i;
1752 if (prev->instance == next->nest_lock)
1755 if (hlock_class(prev) != hlock_class(next))
1759 * Allow read-after-read recursion of the same
1760 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1762 if ((read == 2) && prev->read)
1766 * We're holding the nest_lock, which serializes this lock's
1767 * nesting behaviour.
1772 return print_deadlock_bug(curr, prev, next);
1778 * There was a chain-cache miss, and we are about to add a new dependency
1779 * to a previous lock. We recursively validate the following rules:
1781 * - would the adding of the <prev> -> <next> dependency create a
1782 * circular dependency in the graph? [== circular deadlock]
1784 * - does the new prev->next dependency connect any hardirq-safe lock
1785 * (in the full backwards-subgraph starting at <prev>) with any
1786 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1787 * <next>)? [== illegal lock inversion with hardirq contexts]
1789 * - does the new prev->next dependency connect any softirq-safe lock
1790 * (in the full backwards-subgraph starting at <prev>) with any
1791 * softirq-unsafe lock (in the full forwards-subgraph starting at
1792 * <next>)? [== illegal lock inversion with softirq contexts]
1794 * any of these scenarios could lead to a deadlock.
1796 * Then if all the validations pass, we add the forwards and backwards
1800 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1801 struct held_lock *next, int distance, int *stack_saved)
1803 struct lock_list *entry;
1805 struct lock_list this;
1806 struct lock_list *uninitialized_var(target_entry);
1808 * Static variable, serialized by the graph_lock().
1810 * We use this static variable to save the stack trace in case
1811 * we call into this function multiple times due to encountering
1812 * trylocks in the held lock stack.
1814 static struct stack_trace trace;
1817 * Prove that the new <prev> -> <next> dependency would not
1818 * create a circular dependency in the graph. (We do this by
1819 * forward-recursing into the graph starting at <next>, and
1820 * checking whether we can reach <prev>.)
1822 * We are using global variables to control the recursion, to
1823 * keep the stackframe size of the recursive functions low:
1825 this.class = hlock_class(next);
1827 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1829 return print_circular_bug(&this, target_entry, next, prev);
1830 else if (unlikely(ret < 0))
1831 return print_bfs_bug(ret);
1833 if (!check_prev_add_irq(curr, prev, next))
1837 * For recursive read-locks we do all the dependency checks,
1838 * but we dont store read-triggered dependencies (only
1839 * write-triggered dependencies). This ensures that only the
1840 * write-side dependencies matter, and that if for example a
1841 * write-lock never takes any other locks, then the reads are
1842 * equivalent to a NOP.
1844 if (next->read == 2 || prev->read == 2)
1847 * Is the <prev> -> <next> dependency already present?
1849 * (this may occur even though this is a new chain: consider
1850 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1851 * chains - the second one will be new, but L1 already has
1852 * L2 added to its dependency list, due to the first chain.)
1854 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1855 if (entry->class == hlock_class(next)) {
1857 entry->distance = 1;
1862 if (!*stack_saved) {
1863 if (!save_trace(&trace))
1869 * Ok, all validations passed, add the new lock
1870 * to the previous lock's dependency list:
1872 ret = add_lock_to_list(hlock_class(next),
1873 &hlock_class(prev)->locks_after,
1874 next->acquire_ip, distance, &trace);
1879 ret = add_lock_to_list(hlock_class(prev),
1880 &hlock_class(next)->locks_before,
1881 next->acquire_ip, distance, &trace);
1886 * Debugging printouts:
1888 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1889 /* We drop graph lock, so another thread can overwrite trace. */
1892 printk("\n new dependency: ");
1893 print_lock_name(hlock_class(prev));
1894 printk(KERN_CONT " => ");
1895 print_lock_name(hlock_class(next));
1896 printk(KERN_CONT "\n");
1898 return graph_lock();
1904 * Add the dependency to all directly-previous locks that are 'relevant'.
1905 * The ones that are relevant are (in increasing distance from curr):
1906 * all consecutive trylock entries and the final non-trylock entry - or
1907 * the end of this context's lock-chain - whichever comes first.
1910 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1912 int depth = curr->lockdep_depth;
1913 int stack_saved = 0;
1914 struct held_lock *hlock;
1919 * Depth must not be zero for a non-head lock:
1924 * At least two relevant locks must exist for this
1927 if (curr->held_locks[depth].irq_context !=
1928 curr->held_locks[depth-1].irq_context)
1932 int distance = curr->lockdep_depth - depth + 1;
1933 hlock = curr->held_locks + depth - 1;
1935 * Only non-recursive-read entries get new dependencies
1938 if (hlock->read != 2 && hlock->check) {
1939 if (!check_prev_add(curr, hlock, next,
1940 distance, &stack_saved))
1943 * Stop after the first non-trylock entry,
1944 * as non-trylock entries have added their
1945 * own direct dependencies already, so this
1946 * lock is connected to them indirectly:
1948 if (!hlock->trylock)
1953 * End of lock-stack?
1958 * Stop the search if we cross into another context:
1960 if (curr->held_locks[depth].irq_context !=
1961 curr->held_locks[depth-1].irq_context)
1966 if (!debug_locks_off_graph_unlock())
1970 * Clearly we all shouldn't be here, but since we made it we
1971 * can reliable say we messed up our state. See the above two
1972 * gotos for reasons why we could possibly end up here.
1979 unsigned long nr_lock_chains;
1980 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1981 int nr_chain_hlocks;
1982 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1984 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1986 return lock_classes + chain_hlocks[chain->base + i];
1990 * Returns the index of the first held_lock of the current chain
1992 static inline int get_first_held_lock(struct task_struct *curr,
1993 struct held_lock *hlock)
1996 struct held_lock *hlock_curr;
1998 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1999 hlock_curr = curr->held_locks + i;
2000 if (hlock_curr->irq_context != hlock->irq_context)
2008 #ifdef CONFIG_DEBUG_LOCKDEP
2010 * Returns the next chain_key iteration
2012 static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2014 u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2016 printk(" class_idx:%d -> chain_key:%016Lx",
2018 (unsigned long long)new_chain_key);
2019 return new_chain_key;
2023 print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2025 struct held_lock *hlock;
2027 int depth = curr->lockdep_depth;
2030 printk("depth: %u\n", depth + 1);
2031 for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
2032 hlock = curr->held_locks + i;
2033 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2038 print_chain_key_iteration(hlock_next->class_idx, chain_key);
2039 print_lock(hlock_next);
2042 static void print_chain_keys_chain(struct lock_chain *chain)
2048 printk("depth: %u\n", chain->depth);
2049 for (i = 0; i < chain->depth; i++) {
2050 class_id = chain_hlocks[chain->base + i];
2051 chain_key = print_chain_key_iteration(class_id + 1, chain_key);
2053 print_lock_name(lock_classes + class_id);
2058 static void print_collision(struct task_struct *curr,
2059 struct held_lock *hlock_next,
2060 struct lock_chain *chain)
2063 printk("======================\n");
2064 printk("[chain_key collision ]\n");
2065 print_kernel_ident();
2066 printk("----------------------\n");
2067 printk("%s/%d: ", current->comm, task_pid_nr(current));
2068 printk("Hash chain already cached but the contents don't match!\n");
2070 printk("Held locks:");
2071 print_chain_keys_held_locks(curr, hlock_next);
2073 printk("Locks in cached chain:");
2074 print_chain_keys_chain(chain);
2076 printk("\nstack backtrace:\n");
2082 * Checks whether the chain and the current held locks are consistent
2083 * in depth and also in content. If they are not it most likely means
2084 * that there was a collision during the calculation of the chain_key.
2085 * Returns: 0 not passed, 1 passed
2087 static int check_no_collision(struct task_struct *curr,
2088 struct held_lock *hlock,
2089 struct lock_chain *chain)
2091 #ifdef CONFIG_DEBUG_LOCKDEP
2094 i = get_first_held_lock(curr, hlock);
2096 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2097 print_collision(curr, hlock, chain);
2101 for (j = 0; j < chain->depth - 1; j++, i++) {
2102 id = curr->held_locks[i].class_idx - 1;
2104 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2105 print_collision(curr, hlock, chain);
2114 * Look up a dependency chain. If the key is not present yet then
2115 * add it and return 1 - in this case the new dependency chain is
2116 * validated. If the key is already hashed, return 0.
2117 * (On return with 1 graph_lock is held.)
2119 static inline int lookup_chain_cache(struct task_struct *curr,
2120 struct held_lock *hlock,
2123 struct lock_class *class = hlock_class(hlock);
2124 struct hlist_head *hash_head = chainhashentry(chain_key);
2125 struct lock_chain *chain;
2129 * We might need to take the graph lock, ensure we've got IRQs
2130 * disabled to make this an IRQ-safe lock.. for recursion reasons
2131 * lockdep won't complain about its own locking errors.
2133 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2136 * We can walk it lock-free, because entries only get added
2139 hlist_for_each_entry_rcu(chain, hash_head, entry) {
2140 if (chain->chain_key == chain_key) {
2142 debug_atomic_inc(chain_lookup_hits);
2143 if (!check_no_collision(curr, hlock, chain))
2146 if (very_verbose(class))
2147 printk("\nhash chain already cached, key: "
2148 "%016Lx tail class: [%p] %s\n",
2149 (unsigned long long)chain_key,
2150 class->key, class->name);
2154 if (very_verbose(class))
2155 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2156 (unsigned long long)chain_key, class->key, class->name);
2158 * Allocate a new chain entry from the static array, and add
2164 * We have to walk the chain again locked - to avoid duplicates:
2166 hlist_for_each_entry(chain, hash_head, entry) {
2167 if (chain->chain_key == chain_key) {
2172 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2173 if (!debug_locks_off_graph_unlock())
2176 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2180 chain = lock_chains + nr_lock_chains++;
2181 chain->chain_key = chain_key;
2182 chain->irq_context = hlock->irq_context;
2183 i = get_first_held_lock(curr, hlock);
2184 chain->depth = curr->lockdep_depth + 1 - i;
2186 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2187 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
2188 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2190 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2191 chain->base = nr_chain_hlocks;
2192 for (j = 0; j < chain->depth - 1; j++, i++) {
2193 int lock_id = curr->held_locks[i].class_idx - 1;
2194 chain_hlocks[chain->base + j] = lock_id;
2196 chain_hlocks[chain->base + j] = class - lock_classes;
2199 if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
2200 nr_chain_hlocks += chain->depth;
2202 #ifdef CONFIG_DEBUG_LOCKDEP
2204 * Important for check_no_collision().
2206 if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
2207 if (!debug_locks_off_graph_unlock())
2210 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2216 hlist_add_head_rcu(&chain->entry, hash_head);
2217 debug_atomic_inc(chain_lookup_misses);
2223 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2224 struct held_lock *hlock, int chain_head, u64 chain_key)
2227 * Trylock needs to maintain the stack of held locks, but it
2228 * does not add new dependencies, because trylock can be done
2231 * We look up the chain_key and do the O(N^2) check and update of
2232 * the dependencies only if this is a new dependency chain.
2233 * (If lookup_chain_cache() returns with 1 it acquires
2234 * graph_lock for us)
2236 if (!hlock->trylock && hlock->check &&
2237 lookup_chain_cache(curr, hlock, chain_key)) {
2239 * Check whether last held lock:
2241 * - is irq-safe, if this lock is irq-unsafe
2242 * - is softirq-safe, if this lock is hardirq-unsafe
2244 * And check whether the new lock's dependency graph
2245 * could lead back to the previous lock.
2247 * any of these scenarios could lead to a deadlock. If
2250 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2255 * Mark recursive read, as we jump over it when
2256 * building dependencies (just like we jump over
2262 * Add dependency only if this lock is not the head
2263 * of the chain, and if it's not a secondary read-lock:
2265 if (!chain_head && ret != 2)
2266 if (!check_prevs_add(curr, hlock))
2270 /* after lookup_chain_cache(): */
2271 if (unlikely(!debug_locks))
2277 static inline int validate_chain(struct task_struct *curr,
2278 struct lockdep_map *lock, struct held_lock *hlock,
2279 int chain_head, u64 chain_key)
2286 * We are building curr_chain_key incrementally, so double-check
2287 * it from scratch, to make sure that it's done correctly:
2289 static void check_chain_key(struct task_struct *curr)
2291 #ifdef CONFIG_DEBUG_LOCKDEP
2292 struct held_lock *hlock, *prev_hlock = NULL;
2296 for (i = 0; i < curr->lockdep_depth; i++) {
2297 hlock = curr->held_locks + i;
2298 if (chain_key != hlock->prev_chain_key) {
2301 * We got mighty confused, our chain keys don't match
2302 * with what we expect, someone trample on our task state?
2304 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2305 curr->lockdep_depth, i,
2306 (unsigned long long)chain_key,
2307 (unsigned long long)hlock->prev_chain_key);
2311 * Whoops ran out of static storage again?
2313 if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
2316 if (prev_hlock && (prev_hlock->irq_context !=
2317 hlock->irq_context))
2319 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
2322 if (chain_key != curr->curr_chain_key) {
2325 * More smoking hash instead of calculating it, damn see these
2326 * numbers float.. I bet that a pink elephant stepped on my memory.
2328 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2329 curr->lockdep_depth, i,
2330 (unsigned long long)chain_key,
2331 (unsigned long long)curr->curr_chain_key);
2337 print_usage_bug_scenario(struct held_lock *lock)
2339 struct lock_class *class = hlock_class(lock);
2341 printk(" Possible unsafe locking scenario:\n\n");
2345 __print_lock_name(class);
2346 printk(KERN_CONT ");\n");
2347 printk(" <Interrupt>\n");
2349 __print_lock_name(class);
2350 printk(KERN_CONT ");\n");
2351 printk("\n *** DEADLOCK ***\n\n");
2355 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2356 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2358 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2362 printk("=================================\n");
2363 printk("[ INFO: inconsistent lock state ]\n");
2364 print_kernel_ident();
2365 printk("---------------------------------\n");
2367 printk("inconsistent {%s} -> {%s} usage.\n",
2368 usage_str[prev_bit], usage_str[new_bit]);
2370 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2371 curr->comm, task_pid_nr(curr),
2372 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2373 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2374 trace_hardirqs_enabled(curr),
2375 trace_softirqs_enabled(curr));
2378 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2379 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2381 print_irqtrace_events(curr);
2382 printk("\nother info that might help us debug this:\n");
2383 print_usage_bug_scenario(this);
2385 lockdep_print_held_locks(curr);
2387 printk("\nstack backtrace:\n");
2394 * Print out an error if an invalid bit is set:
2397 valid_state(struct task_struct *curr, struct held_lock *this,
2398 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2400 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2401 return print_usage_bug(curr, this, bad_bit, new_bit);
2405 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2406 enum lock_usage_bit new_bit);
2408 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2411 * print irq inversion bug:
2414 print_irq_inversion_bug(struct task_struct *curr,
2415 struct lock_list *root, struct lock_list *other,
2416 struct held_lock *this, int forwards,
2417 const char *irqclass)
2419 struct lock_list *entry = other;
2420 struct lock_list *middle = NULL;
2423 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2427 printk("=========================================================\n");
2428 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2429 print_kernel_ident();
2430 printk("---------------------------------------------------------\n");
2431 printk("%s/%d just changed the state of lock:\n",
2432 curr->comm, task_pid_nr(curr));
2435 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2437 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2438 print_lock_name(other->class);
2439 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2441 printk("\nother info that might help us debug this:\n");
2443 /* Find a middle lock (if one exists) */
2444 depth = get_lock_depth(other);
2446 if (depth == 0 && (entry != root)) {
2447 printk("lockdep:%s bad path found in chain graph\n", __func__);
2451 entry = get_lock_parent(entry);
2453 } while (entry && entry != root && (depth >= 0));
2455 print_irq_lock_scenario(root, other,
2456 middle ? middle->class : root->class, other->class);
2458 print_irq_lock_scenario(other, root,
2459 middle ? middle->class : other->class, root->class);
2461 lockdep_print_held_locks(curr);
2463 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2464 if (!save_trace(&root->trace))
2466 print_shortest_lock_dependencies(other, root);
2468 printk("\nstack backtrace:\n");
2475 * Prove that in the forwards-direction subgraph starting at <this>
2476 * there is no lock matching <mask>:
2479 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2480 enum lock_usage_bit bit, const char *irqclass)
2483 struct lock_list root;
2484 struct lock_list *uninitialized_var(target_entry);
2487 root.class = hlock_class(this);
2488 ret = find_usage_forwards(&root, bit, &target_entry);
2490 return print_bfs_bug(ret);
2494 return print_irq_inversion_bug(curr, &root, target_entry,
2499 * Prove that in the backwards-direction subgraph starting at <this>
2500 * there is no lock matching <mask>:
2503 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2504 enum lock_usage_bit bit, const char *irqclass)
2507 struct lock_list root;
2508 struct lock_list *uninitialized_var(target_entry);
2511 root.class = hlock_class(this);
2512 ret = find_usage_backwards(&root, bit, &target_entry);
2514 return print_bfs_bug(ret);
2518 return print_irq_inversion_bug(curr, &root, target_entry,
2522 void print_irqtrace_events(struct task_struct *curr)
2524 printk("irq event stamp: %u\n", curr->irq_events);
2525 printk("hardirqs last enabled at (%u): [<%p>] %pS\n",
2526 curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
2527 (void *)curr->hardirq_enable_ip);
2528 printk("hardirqs last disabled at (%u): [<%p>] %pS\n",
2529 curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
2530 (void *)curr->hardirq_disable_ip);
2531 printk("softirqs last enabled at (%u): [<%p>] %pS\n",
2532 curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
2533 (void *)curr->softirq_enable_ip);
2534 printk("softirqs last disabled at (%u): [<%p>] %pS\n",
2535 curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
2536 (void *)curr->softirq_disable_ip);
2539 static int HARDIRQ_verbose(struct lock_class *class)
2542 return class_filter(class);
2547 static int SOFTIRQ_verbose(struct lock_class *class)
2550 return class_filter(class);
2555 static int RECLAIM_FS_verbose(struct lock_class *class)
2558 return class_filter(class);
2563 #define STRICT_READ_CHECKS 1
2565 static int (*state_verbose_f[])(struct lock_class *class) = {
2566 #define LOCKDEP_STATE(__STATE) \
2568 #include "lockdep_states.h"
2569 #undef LOCKDEP_STATE
2572 static inline int state_verbose(enum lock_usage_bit bit,
2573 struct lock_class *class)
2575 return state_verbose_f[bit >> 2](class);
2578 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2579 enum lock_usage_bit bit, const char *name);
2582 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2583 enum lock_usage_bit new_bit)
2585 int excl_bit = exclusive_bit(new_bit);
2586 int read = new_bit & 1;
2587 int dir = new_bit & 2;
2590 * mark USED_IN has to look forwards -- to ensure no dependency
2591 * has ENABLED state, which would allow recursion deadlocks.
2593 * mark ENABLED has to look backwards -- to ensure no dependee
2594 * has USED_IN state, which, again, would allow recursion deadlocks.
2596 check_usage_f usage = dir ?
2597 check_usage_backwards : check_usage_forwards;
2600 * Validate that this particular lock does not have conflicting
2603 if (!valid_state(curr, this, new_bit, excl_bit))
2607 * Validate that the lock dependencies don't have conflicting usage
2610 if ((!read || !dir || STRICT_READ_CHECKS) &&
2611 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2615 * Check for read in write conflicts
2618 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2621 if (STRICT_READ_CHECKS &&
2622 !usage(curr, this, excl_bit + 1,
2623 state_name(new_bit + 1)))
2627 if (state_verbose(new_bit, hlock_class(this)))
2634 #define LOCKDEP_STATE(__STATE) __STATE,
2635 #include "lockdep_states.h"
2636 #undef LOCKDEP_STATE
2640 * Mark all held locks with a usage bit:
2643 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2645 enum lock_usage_bit usage_bit;
2646 struct held_lock *hlock;
2649 for (i = 0; i < curr->lockdep_depth; i++) {
2650 hlock = curr->held_locks + i;
2652 usage_bit = 2 + (mark << 2); /* ENABLED */
2654 usage_bit += 1; /* READ */
2656 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2661 if (!mark_lock(curr, hlock, usage_bit))
2669 * Hardirqs will be enabled:
2671 static void __trace_hardirqs_on_caller(unsigned long ip)
2673 struct task_struct *curr = current;
2675 /* we'll do an OFF -> ON transition: */
2676 curr->hardirqs_enabled = 1;
2679 * We are going to turn hardirqs on, so set the
2680 * usage bit for all held locks:
2682 if (!mark_held_locks(curr, HARDIRQ))
2685 * If we have softirqs enabled, then set the usage
2686 * bit for all held locks. (disabled hardirqs prevented
2687 * this bit from being set before)
2689 if (curr->softirqs_enabled)
2690 if (!mark_held_locks(curr, SOFTIRQ))
2693 curr->hardirq_enable_ip = ip;
2694 curr->hardirq_enable_event = ++curr->irq_events;
2695 debug_atomic_inc(hardirqs_on_events);
2698 __visible void trace_hardirqs_on_caller(unsigned long ip)
2700 time_hardirqs_on(CALLER_ADDR0, ip);
2702 if (unlikely(!debug_locks || current->lockdep_recursion))
2705 if (unlikely(current->hardirqs_enabled)) {
2707 * Neither irq nor preemption are disabled here
2708 * so this is racy by nature but losing one hit
2709 * in a stat is not a big deal.
2711 __debug_atomic_inc(redundant_hardirqs_on);
2716 * We're enabling irqs and according to our state above irqs weren't
2717 * already enabled, yet we find the hardware thinks they are in fact
2718 * enabled.. someone messed up their IRQ state tracing.
2720 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2724 * See the fine text that goes along with this variable definition.
2726 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2730 * Can't allow enabling interrupts while in an interrupt handler,
2731 * that's general bad form and such. Recursion, limited stack etc..
2733 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2736 current->lockdep_recursion = 1;
2737 __trace_hardirqs_on_caller(ip);
2738 current->lockdep_recursion = 0;
2740 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2742 void trace_hardirqs_on(void)
2744 trace_hardirqs_on_caller(CALLER_ADDR0);
2746 EXPORT_SYMBOL(trace_hardirqs_on);
2749 * Hardirqs were disabled:
2751 __visible void trace_hardirqs_off_caller(unsigned long ip)
2753 struct task_struct *curr = current;
2755 time_hardirqs_off(CALLER_ADDR0, ip);
2757 if (unlikely(!debug_locks || current->lockdep_recursion))
2761 * So we're supposed to get called after you mask local IRQs, but for
2762 * some reason the hardware doesn't quite think you did a proper job.
2764 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2767 if (curr->hardirqs_enabled) {
2769 * We have done an ON -> OFF transition:
2771 curr->hardirqs_enabled = 0;
2772 curr->hardirq_disable_ip = ip;
2773 curr->hardirq_disable_event = ++curr->irq_events;
2774 debug_atomic_inc(hardirqs_off_events);
2776 debug_atomic_inc(redundant_hardirqs_off);
2778 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2780 void trace_hardirqs_off(void)
2782 trace_hardirqs_off_caller(CALLER_ADDR0);
2784 EXPORT_SYMBOL(trace_hardirqs_off);
2787 * Softirqs will be enabled:
2789 void trace_softirqs_on(unsigned long ip)
2791 struct task_struct *curr = current;
2793 if (unlikely(!debug_locks || current->lockdep_recursion))
2797 * We fancy IRQs being disabled here, see softirq.c, avoids
2798 * funny state and nesting things.
2800 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2803 if (curr->softirqs_enabled) {
2804 debug_atomic_inc(redundant_softirqs_on);
2808 current->lockdep_recursion = 1;
2810 * We'll do an OFF -> ON transition:
2812 curr->softirqs_enabled = 1;
2813 curr->softirq_enable_ip = ip;
2814 curr->softirq_enable_event = ++curr->irq_events;
2815 debug_atomic_inc(softirqs_on_events);
2817 * We are going to turn softirqs on, so set the
2818 * usage bit for all held locks, if hardirqs are
2821 if (curr->hardirqs_enabled)
2822 mark_held_locks(curr, SOFTIRQ);
2823 current->lockdep_recursion = 0;
2827 * Softirqs were disabled:
2829 void trace_softirqs_off(unsigned long ip)
2831 struct task_struct *curr = current;
2833 if (unlikely(!debug_locks || current->lockdep_recursion))
2837 * We fancy IRQs being disabled here, see softirq.c
2839 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2842 if (curr->softirqs_enabled) {
2844 * We have done an ON -> OFF transition:
2846 curr->softirqs_enabled = 0;
2847 curr->softirq_disable_ip = ip;
2848 curr->softirq_disable_event = ++curr->irq_events;
2849 debug_atomic_inc(softirqs_off_events);
2851 * Whoops, we wanted softirqs off, so why aren't they?
2853 DEBUG_LOCKS_WARN_ON(!softirq_count());
2855 debug_atomic_inc(redundant_softirqs_off);
2858 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2860 struct task_struct *curr = current;
2862 if (unlikely(!debug_locks))
2865 /* no reclaim without waiting on it */
2866 if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
2869 /* this guy won't enter reclaim */
2870 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2873 /* We're only interested __GFP_FS allocations for now */
2874 if (!(gfp_mask & __GFP_FS))
2878 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2880 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2883 mark_held_locks(curr, RECLAIM_FS);
2886 static void check_flags(unsigned long flags);
2888 void lockdep_trace_alloc(gfp_t gfp_mask)
2890 unsigned long flags;
2892 if (unlikely(current->lockdep_recursion))
2895 raw_local_irq_save(flags);
2897 current->lockdep_recursion = 1;
2898 __lockdep_trace_alloc(gfp_mask, flags);
2899 current->lockdep_recursion = 0;
2900 raw_local_irq_restore(flags);
2903 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2906 * If non-trylock use in a hardirq or softirq context, then
2907 * mark the lock as used in these contexts:
2909 if (!hlock->trylock) {
2911 if (curr->hardirq_context)
2912 if (!mark_lock(curr, hlock,
2913 LOCK_USED_IN_HARDIRQ_READ))
2915 if (curr->softirq_context)
2916 if (!mark_lock(curr, hlock,
2917 LOCK_USED_IN_SOFTIRQ_READ))
2920 if (curr->hardirq_context)
2921 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2923 if (curr->softirq_context)
2924 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2928 if (!hlock->hardirqs_off) {
2930 if (!mark_lock(curr, hlock,
2931 LOCK_ENABLED_HARDIRQ_READ))
2933 if (curr->softirqs_enabled)
2934 if (!mark_lock(curr, hlock,
2935 LOCK_ENABLED_SOFTIRQ_READ))
2938 if (!mark_lock(curr, hlock,
2939 LOCK_ENABLED_HARDIRQ))
2941 if (curr->softirqs_enabled)
2942 if (!mark_lock(curr, hlock,
2943 LOCK_ENABLED_SOFTIRQ))
2949 * We reuse the irq context infrastructure more broadly as a general
2950 * context checking code. This tests GFP_FS recursion (a lock taken
2951 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2954 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2956 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2959 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2967 static inline unsigned int task_irq_context(struct task_struct *task)
2969 return 2 * !!task->hardirq_context + !!task->softirq_context;
2972 static int separate_irq_context(struct task_struct *curr,
2973 struct held_lock *hlock)
2975 unsigned int depth = curr->lockdep_depth;
2978 * Keep track of points where we cross into an interrupt context:
2981 struct held_lock *prev_hlock;
2983 prev_hlock = curr->held_locks + depth-1;
2985 * If we cross into another context, reset the
2986 * hash key (this also prevents the checking and the
2987 * adding of the dependency to 'prev'):
2989 if (prev_hlock->irq_context != hlock->irq_context)
2995 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2998 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2999 enum lock_usage_bit new_bit)
3001 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
3005 static inline int mark_irqflags(struct task_struct *curr,
3006 struct held_lock *hlock)
3011 static inline unsigned int task_irq_context(struct task_struct *task)
3016 static inline int separate_irq_context(struct task_struct *curr,
3017 struct held_lock *hlock)
3022 void lockdep_trace_alloc(gfp_t gfp_mask)
3026 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3029 * Mark a lock with a usage bit, and validate the state transition:
3031 static int mark_lock(struct task_struct *curr, struct held_lock *this,
3032 enum lock_usage_bit new_bit)
3034 unsigned int new_mask = 1 << new_bit, ret = 1;
3037 * If already set then do not dirty the cacheline,
3038 * nor do any checks:
3040 if (likely(hlock_class(this)->usage_mask & new_mask))
3046 * Make sure we didn't race:
3048 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3053 hlock_class(this)->usage_mask |= new_mask;
3055 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
3059 #define LOCKDEP_STATE(__STATE) \
3060 case LOCK_USED_IN_##__STATE: \
3061 case LOCK_USED_IN_##__STATE##_READ: \
3062 case LOCK_ENABLED_##__STATE: \
3063 case LOCK_ENABLED_##__STATE##_READ:
3064 #include "lockdep_states.h"
3065 #undef LOCKDEP_STATE
3066 ret = mark_lock_irq(curr, this, new_bit);
3071 debug_atomic_dec(nr_unused_locks);
3074 if (!debug_locks_off_graph_unlock())
3083 * We must printk outside of the graph_lock:
3086 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3088 print_irqtrace_events(curr);
3096 * Initialize a lock instance's lock-class mapping info:
3098 void lockdep_init_map(struct lockdep_map *lock, const char *name,
3099 struct lock_class_key *key, int subclass)
3103 kmemcheck_mark_initialized(lock, sizeof(*lock));
3105 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3106 lock->class_cache[i] = NULL;
3108 #ifdef CONFIG_LOCK_STAT
3109 lock->cpu = raw_smp_processor_id();
3113 * Can't be having no nameless bastards around this place!
3115 if (DEBUG_LOCKS_WARN_ON(!name)) {
3116 lock->name = "NULL";
3123 * No key, no joy, we need to hash something.
3125 if (DEBUG_LOCKS_WARN_ON(!key))
3128 * Sanity check, the lock-class key must be persistent:
3130 if (!static_obj(key)) {
3131 printk("BUG: key %p not in .data!\n", key);
3133 * What it says above ^^^^^, I suggest you read it.
3135 DEBUG_LOCKS_WARN_ON(1);
3140 if (unlikely(!debug_locks))
3144 unsigned long flags;
3146 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3149 raw_local_irq_save(flags);
3150 current->lockdep_recursion = 1;
3151 register_lock_class(lock, subclass, 1);
3152 current->lockdep_recursion = 0;
3153 raw_local_irq_restore(flags);
3156 EXPORT_SYMBOL_GPL(lockdep_init_map);
3158 struct lock_class_key __lockdep_no_validate__;
3159 EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3162 print_lock_nested_lock_not_held(struct task_struct *curr,
3163 struct held_lock *hlock,
3166 if (!debug_locks_off())
3168 if (debug_locks_silent)
3172 printk("==================================\n");
3173 printk("[ BUG: Nested lock was not taken ]\n");
3174 print_kernel_ident();
3175 printk("----------------------------------\n");
3177 printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3180 printk("\nbut this task is not holding:\n");
3181 printk("%s\n", hlock->nest_lock->name);
3183 printk("\nstack backtrace:\n");
3186 printk("\nother info that might help us debug this:\n");
3187 lockdep_print_held_locks(curr);
3189 printk("\nstack backtrace:\n");
3195 static int __lock_is_held(struct lockdep_map *lock, int read);
3198 * This gets called for every mutex_lock*()/spin_lock*() operation.
3199 * We maintain the dependency maps and validate the locking attempt:
3201 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3202 int trylock, int read, int check, int hardirqs_off,
3203 struct lockdep_map *nest_lock, unsigned long ip,
3204 int references, int pin_count)
3206 struct task_struct *curr = current;
3207 struct lock_class *class = NULL;
3208 struct held_lock *hlock;
3214 if (unlikely(!debug_locks))
3218 * Lockdep should run with IRQs disabled, otherwise we could
3219 * get an interrupt which would want to take locks, which would
3220 * end up in lockdep and have you got a head-ache already?
3222 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3225 if (!prove_locking || lock->key == &__lockdep_no_validate__)
3228 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3229 class = lock->class_cache[subclass];
3233 if (unlikely(!class)) {
3234 class = register_lock_class(lock, subclass, 0);
3238 atomic_inc((atomic_t *)&class->ops);
3239 if (very_verbose(class)) {
3240 printk("\nacquire class [%p] %s", class->key, class->name);
3241 if (class->name_version > 1)
3242 printk(KERN_CONT "#%d", class->name_version);
3243 printk(KERN_CONT "\n");
3248 * Add the lock to the list of currently held locks.
3249 * (we dont increase the depth just yet, up until the
3250 * dependency checks are done)
3252 depth = curr->lockdep_depth;
3254 * Ran out of static storage for our per-task lock stack again have we?
3256 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3259 class_idx = class - lock_classes + 1;
3262 hlock = curr->held_locks + depth - 1;
3263 if (hlock->class_idx == class_idx && nest_lock) {
3264 if (hlock->references)
3265 hlock->references++;
3267 hlock->references = 2;
3273 hlock = curr->held_locks + depth;
3275 * Plain impossible, we just registered it and checked it weren't no
3276 * NULL like.. I bet this mushroom I ate was good!
3278 if (DEBUG_LOCKS_WARN_ON(!class))
3280 hlock->class_idx = class_idx;
3281 hlock->acquire_ip = ip;
3282 hlock->instance = lock;
3283 hlock->nest_lock = nest_lock;
3284 hlock->irq_context = task_irq_context(curr);
3285 hlock->trylock = trylock;
3287 hlock->check = check;
3288 hlock->hardirqs_off = !!hardirqs_off;
3289 hlock->references = references;
3290 #ifdef CONFIG_LOCK_STAT
3291 hlock->waittime_stamp = 0;
3292 hlock->holdtime_stamp = lockstat_clock();
3294 hlock->pin_count = pin_count;
3296 if (check && !mark_irqflags(curr, hlock))
3299 /* mark it as used: */
3300 if (!mark_lock(curr, hlock, LOCK_USED))
3304 * Calculate the chain hash: it's the combined hash of all the
3305 * lock keys along the dependency chain. We save the hash value
3306 * at every step so that we can get the current hash easily
3307 * after unlock. The chain hash is then used to cache dependency
3310 * The 'key ID' is what is the most compact key value to drive
3311 * the hash, not class->key.
3314 * Whoops, we did it again.. ran straight out of our static allocation.
3316 if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
3319 chain_key = curr->curr_chain_key;
3322 * How can we have a chain hash when we ain't got no keys?!
3324 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3329 hlock->prev_chain_key = chain_key;
3330 if (separate_irq_context(curr, hlock)) {
3334 chain_key = iterate_chain_key(chain_key, class_idx);
3336 if (nest_lock && !__lock_is_held(nest_lock, -1))
3337 return print_lock_nested_lock_not_held(curr, hlock, ip);
3339 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3342 curr->curr_chain_key = chain_key;
3343 curr->lockdep_depth++;
3344 check_chain_key(curr);
3345 #ifdef CONFIG_DEBUG_LOCKDEP
3346 if (unlikely(!debug_locks))
3349 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3351 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3352 printk(KERN_DEBUG "depth: %i max: %lu!\n",
3353 curr->lockdep_depth, MAX_LOCK_DEPTH);
3355 lockdep_print_held_locks(current);
3356 debug_show_all_locks();
3362 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3363 max_lockdep_depth = curr->lockdep_depth;
3369 print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3372 if (!debug_locks_off())
3374 if (debug_locks_silent)
3378 printk("=====================================\n");
3379 printk("[ BUG: bad unlock balance detected! ]\n");
3380 print_kernel_ident();
3381 printk("-------------------------------------\n");
3382 printk("%s/%d is trying to release lock (",
3383 curr->comm, task_pid_nr(curr));
3384 print_lockdep_cache(lock);
3385 printk(KERN_CONT ") at:\n");
3387 printk("but there are no more locks to release!\n");
3388 printk("\nother info that might help us debug this:\n");
3389 lockdep_print_held_locks(curr);
3391 printk("\nstack backtrace:\n");
3397 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3399 if (hlock->instance == lock)
3402 if (hlock->references) {
3403 struct lock_class *class = lock->class_cache[0];
3406 class = look_up_lock_class(lock, 0);
3409 * If look_up_lock_class() failed to find a class, we're trying
3410 * to test if we hold a lock that has never yet been acquired.
3411 * Clearly if the lock hasn't been acquired _ever_, we're not
3412 * holding it either, so report failure.
3418 * References, but not a lock we're actually ref-counting?
3419 * State got messed up, follow the sites that change ->references
3420 * and try to make sense of it.
3422 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3425 if (hlock->class_idx == class - lock_classes + 1)
3433 __lock_set_class(struct lockdep_map *lock, const char *name,
3434 struct lock_class_key *key, unsigned int subclass,
3437 struct task_struct *curr = current;
3438 struct held_lock *hlock, *prev_hlock;
3439 struct lock_class *class;
3443 depth = curr->lockdep_depth;
3445 * This function is about (re)setting the class of a held lock,
3446 * yet we're not actually holding any locks. Naughty user!
3448 if (DEBUG_LOCKS_WARN_ON(!depth))
3452 for (i = depth-1; i >= 0; i--) {
3453 hlock = curr->held_locks + i;
3455 * We must not cross into another context:
3457 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3459 if (match_held_lock(hlock, lock))
3463 return print_unlock_imbalance_bug(curr, lock, ip);
3466 lockdep_init_map(lock, name, key, 0);
3467 class = register_lock_class(lock, subclass, 0);
3468 hlock->class_idx = class - lock_classes + 1;
3470 curr->lockdep_depth = i;
3471 curr->curr_chain_key = hlock->prev_chain_key;
3473 for (; i < depth; i++) {
3474 hlock = curr->held_locks + i;
3475 if (!__lock_acquire(hlock->instance,
3476 hlock_class(hlock)->subclass, hlock->trylock,
3477 hlock->read, hlock->check, hlock->hardirqs_off,
3478 hlock->nest_lock, hlock->acquire_ip,
3479 hlock->references, hlock->pin_count))
3484 * I took it apart and put it back together again, except now I have
3485 * these 'spare' parts.. where shall I put them.
3487 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3493 * Remove the lock to the list of currently held locks - this gets
3494 * called on mutex_unlock()/spin_unlock*() (or on a failed
3495 * mutex_lock_interruptible()).
3497 * @nested is an hysterical artifact, needs a tree wide cleanup.
3500 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3502 struct task_struct *curr = current;
3503 struct held_lock *hlock, *prev_hlock;
3507 if (unlikely(!debug_locks))
3510 depth = curr->lockdep_depth;
3512 * So we're all set to release this lock.. wait what lock? We don't
3513 * own any locks, you've been drinking again?
3515 if (DEBUG_LOCKS_WARN_ON(depth <= 0))
3516 return print_unlock_imbalance_bug(curr, lock, ip);
3519 * Check whether the lock exists in the current stack
3523 for (i = depth-1; i >= 0; i--) {
3524 hlock = curr->held_locks + i;
3526 * We must not cross into another context:
3528 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3530 if (match_held_lock(hlock, lock))
3534 return print_unlock_imbalance_bug(curr, lock, ip);
3537 if (hlock->instance == lock)
3538 lock_release_holdtime(hlock);
3540 WARN(hlock->pin_count, "releasing a pinned lock\n");
3542 if (hlock->references) {
3543 hlock->references--;
3544 if (hlock->references) {
3546 * We had, and after removing one, still have
3547 * references, the current lock stack is still
3548 * valid. We're done!
3555 * We have the right lock to unlock, 'hlock' points to it.
3556 * Now we remove it from the stack, and add back the other
3557 * entries (if any), recalculating the hash along the way:
3560 curr->lockdep_depth = i;
3561 curr->curr_chain_key = hlock->prev_chain_key;
3563 for (i++; i < depth; i++) {
3564 hlock = curr->held_locks + i;
3565 if (!__lock_acquire(hlock->instance,
3566 hlock_class(hlock)->subclass, hlock->trylock,
3567 hlock->read, hlock->check, hlock->hardirqs_off,
3568 hlock->nest_lock, hlock->acquire_ip,
3569 hlock->references, hlock->pin_count))
3574 * We had N bottles of beer on the wall, we drank one, but now
3575 * there's not N-1 bottles of beer left on the wall...
3577 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3583 static int __lock_is_held(struct lockdep_map *lock, int read)
3585 struct task_struct *curr = current;
3588 for (i = 0; i < curr->lockdep_depth; i++) {
3589 struct held_lock *hlock = curr->held_locks + i;
3591 if (match_held_lock(hlock, lock)) {
3592 if (read == -1 || hlock->read == read)
3602 static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
3604 struct pin_cookie cookie = NIL_COOKIE;
3605 struct task_struct *curr = current;
3608 if (unlikely(!debug_locks))
3611 for (i = 0; i < curr->lockdep_depth; i++) {
3612 struct held_lock *hlock = curr->held_locks + i;
3614 if (match_held_lock(hlock, lock)) {
3616 * Grab 16bits of randomness; this is sufficient to not
3617 * be guessable and still allows some pin nesting in
3618 * our u32 pin_count.
3620 cookie.val = 1 + (prandom_u32() >> 16);
3621 hlock->pin_count += cookie.val;
3626 WARN(1, "pinning an unheld lock\n");
3630 static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3632 struct task_struct *curr = current;
3635 if (unlikely(!debug_locks))
3638 for (i = 0; i < curr->lockdep_depth; i++) {
3639 struct held_lock *hlock = curr->held_locks + i;
3641 if (match_held_lock(hlock, lock)) {
3642 hlock->pin_count += cookie.val;
3647 WARN(1, "pinning an unheld lock\n");
3650 static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3652 struct task_struct *curr = current;
3655 if (unlikely(!debug_locks))
3658 for (i = 0; i < curr->lockdep_depth; i++) {
3659 struct held_lock *hlock = curr->held_locks + i;
3661 if (match_held_lock(hlock, lock)) {
3662 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
3665 hlock->pin_count -= cookie.val;
3667 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
3668 hlock->pin_count = 0;
3674 WARN(1, "unpinning an unheld lock\n");
3678 * Check whether we follow the irq-flags state precisely:
3680 static void check_flags(unsigned long flags)
3682 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3683 defined(CONFIG_TRACE_IRQFLAGS)
3687 if (irqs_disabled_flags(flags)) {
3688 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3689 printk("possible reason: unannotated irqs-off.\n");
3692 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3693 printk("possible reason: unannotated irqs-on.\n");
3698 * We dont accurately track softirq state in e.g.
3699 * hardirq contexts (such as on 4KSTACKS), so only
3700 * check if not in hardirq contexts:
3702 if (!hardirq_count()) {
3703 if (softirq_count()) {
3704 /* like the above, but with softirqs */
3705 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3707 /* lick the above, does it taste good? */
3708 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3713 print_irqtrace_events(current);
3717 void lock_set_class(struct lockdep_map *lock, const char *name,
3718 struct lock_class_key *key, unsigned int subclass,
3721 unsigned long flags;
3723 if (unlikely(current->lockdep_recursion))
3726 raw_local_irq_save(flags);
3727 current->lockdep_recursion = 1;
3729 if (__lock_set_class(lock, name, key, subclass, ip))
3730 check_chain_key(current);
3731 current->lockdep_recursion = 0;
3732 raw_local_irq_restore(flags);
3734 EXPORT_SYMBOL_GPL(lock_set_class);
3737 * We are not always called with irqs disabled - do that here,
3738 * and also avoid lockdep recursion:
3740 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3741 int trylock, int read, int check,
3742 struct lockdep_map *nest_lock, unsigned long ip)
3744 unsigned long flags;
3746 if (unlikely(current->lockdep_recursion))
3749 raw_local_irq_save(flags);
3752 current->lockdep_recursion = 1;
3753 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3754 __lock_acquire(lock, subclass, trylock, read, check,
3755 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
3756 current->lockdep_recursion = 0;
3757 raw_local_irq_restore(flags);
3759 EXPORT_SYMBOL_GPL(lock_acquire);
3761 void lock_release(struct lockdep_map *lock, int nested,
3764 unsigned long flags;
3766 if (unlikely(current->lockdep_recursion))
3769 raw_local_irq_save(flags);
3771 current->lockdep_recursion = 1;
3772 trace_lock_release(lock, ip);
3773 if (__lock_release(lock, nested, ip))
3774 check_chain_key(current);
3775 current->lockdep_recursion = 0;
3776 raw_local_irq_restore(flags);
3778 EXPORT_SYMBOL_GPL(lock_release);
3780 int lock_is_held_type(struct lockdep_map *lock, int read)
3782 unsigned long flags;
3785 if (unlikely(current->lockdep_recursion))
3786 return 1; /* avoid false negative lockdep_assert_held() */
3788 raw_local_irq_save(flags);
3791 current->lockdep_recursion = 1;
3792 ret = __lock_is_held(lock, read);
3793 current->lockdep_recursion = 0;
3794 raw_local_irq_restore(flags);
3798 EXPORT_SYMBOL_GPL(lock_is_held_type);
3800 struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
3802 struct pin_cookie cookie = NIL_COOKIE;
3803 unsigned long flags;
3805 if (unlikely(current->lockdep_recursion))
3808 raw_local_irq_save(flags);
3811 current->lockdep_recursion = 1;
3812 cookie = __lock_pin_lock(lock);
3813 current->lockdep_recursion = 0;
3814 raw_local_irq_restore(flags);
3818 EXPORT_SYMBOL_GPL(lock_pin_lock);
3820 void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3822 unsigned long flags;
3824 if (unlikely(current->lockdep_recursion))
3827 raw_local_irq_save(flags);
3830 current->lockdep_recursion = 1;
3831 __lock_repin_lock(lock, cookie);
3832 current->lockdep_recursion = 0;
3833 raw_local_irq_restore(flags);
3835 EXPORT_SYMBOL_GPL(lock_repin_lock);
3837 void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3839 unsigned long flags;
3841 if (unlikely(current->lockdep_recursion))
3844 raw_local_irq_save(flags);
3847 current->lockdep_recursion = 1;
3848 __lock_unpin_lock(lock, cookie);
3849 current->lockdep_recursion = 0;
3850 raw_local_irq_restore(flags);
3852 EXPORT_SYMBOL_GPL(lock_unpin_lock);
3854 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3856 current->lockdep_reclaim_gfp = gfp_mask;
3859 void lockdep_clear_current_reclaim_state(void)
3861 current->lockdep_reclaim_gfp = 0;
3864 #ifdef CONFIG_LOCK_STAT
3866 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3869 if (!debug_locks_off())
3871 if (debug_locks_silent)
3875 printk("=================================\n");
3876 printk("[ BUG: bad contention detected! ]\n");
3877 print_kernel_ident();
3878 printk("---------------------------------\n");
3879 printk("%s/%d is trying to contend lock (",
3880 curr->comm, task_pid_nr(curr));
3881 print_lockdep_cache(lock);
3882 printk(KERN_CONT ") at:\n");
3884 printk("but there are no locks held!\n");
3885 printk("\nother info that might help us debug this:\n");
3886 lockdep_print_held_locks(curr);
3888 printk("\nstack backtrace:\n");
3895 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3897 struct task_struct *curr = current;
3898 struct held_lock *hlock, *prev_hlock;
3899 struct lock_class_stats *stats;
3901 int i, contention_point, contending_point;
3903 depth = curr->lockdep_depth;
3905 * Whee, we contended on this lock, except it seems we're not
3906 * actually trying to acquire anything much at all..
3908 if (DEBUG_LOCKS_WARN_ON(!depth))
3912 for (i = depth-1; i >= 0; i--) {
3913 hlock = curr->held_locks + i;
3915 * We must not cross into another context:
3917 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3919 if (match_held_lock(hlock, lock))
3923 print_lock_contention_bug(curr, lock, ip);
3927 if (hlock->instance != lock)
3930 hlock->waittime_stamp = lockstat_clock();
3932 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3933 contending_point = lock_point(hlock_class(hlock)->contending_point,
3936 stats = get_lock_stats(hlock_class(hlock));
3937 if (contention_point < LOCKSTAT_POINTS)
3938 stats->contention_point[contention_point]++;
3939 if (contending_point < LOCKSTAT_POINTS)
3940 stats->contending_point[contending_point]++;
3941 if (lock->cpu != smp_processor_id())
3942 stats->bounces[bounce_contended + !!hlock->read]++;
3943 put_lock_stats(stats);
3947 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3949 struct task_struct *curr = current;
3950 struct held_lock *hlock, *prev_hlock;
3951 struct lock_class_stats *stats;
3953 u64 now, waittime = 0;
3956 depth = curr->lockdep_depth;
3958 * Yay, we acquired ownership of this lock we didn't try to
3959 * acquire, how the heck did that happen?
3961 if (DEBUG_LOCKS_WARN_ON(!depth))
3965 for (i = depth-1; i >= 0; i--) {
3966 hlock = curr->held_locks + i;
3968 * We must not cross into another context:
3970 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3972 if (match_held_lock(hlock, lock))
3976 print_lock_contention_bug(curr, lock, _RET_IP_);
3980 if (hlock->instance != lock)
3983 cpu = smp_processor_id();
3984 if (hlock->waittime_stamp) {
3985 now = lockstat_clock();
3986 waittime = now - hlock->waittime_stamp;
3987 hlock->holdtime_stamp = now;
3990 trace_lock_acquired(lock, ip);
3992 stats = get_lock_stats(hlock_class(hlock));
3995 lock_time_inc(&stats->read_waittime, waittime);
3997 lock_time_inc(&stats->write_waittime, waittime);
3999 if (lock->cpu != cpu)
4000 stats->bounces[bounce_acquired + !!hlock->read]++;
4001 put_lock_stats(stats);
4007 void lock_contended(struct lockdep_map *lock, unsigned long ip)
4009 unsigned long flags;
4011 if (unlikely(!lock_stat))
4014 if (unlikely(current->lockdep_recursion))
4017 raw_local_irq_save(flags);
4019 current->lockdep_recursion = 1;
4020 trace_lock_contended(lock, ip);
4021 __lock_contended(lock, ip);
4022 current->lockdep_recursion = 0;
4023 raw_local_irq_restore(flags);
4025 EXPORT_SYMBOL_GPL(lock_contended);
4027 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
4029 unsigned long flags;
4031 if (unlikely(!lock_stat))
4034 if (unlikely(current->lockdep_recursion))
4037 raw_local_irq_save(flags);
4039 current->lockdep_recursion = 1;
4040 __lock_acquired(lock, ip);
4041 current->lockdep_recursion = 0;
4042 raw_local_irq_restore(flags);
4044 EXPORT_SYMBOL_GPL(lock_acquired);
4048 * Used by the testsuite, sanitize the validator state
4049 * after a simulated failure:
4052 void lockdep_reset(void)
4054 unsigned long flags;
4057 raw_local_irq_save(flags);
4058 current->curr_chain_key = 0;
4059 current->lockdep_depth = 0;
4060 current->lockdep_recursion = 0;
4061 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
4062 nr_hardirq_chains = 0;
4063 nr_softirq_chains = 0;
4064 nr_process_chains = 0;
4066 for (i = 0; i < CHAINHASH_SIZE; i++)
4067 INIT_HLIST_HEAD(chainhash_table + i);
4068 raw_local_irq_restore(flags);
4071 static void zap_class(struct lock_class *class)
4076 * Remove all dependencies this lock is
4079 for (i = 0; i < nr_list_entries; i++) {
4080 if (list_entries[i].class == class)
4081 list_del_rcu(&list_entries[i].entry);
4084 * Unhash the class and remove it from the all_lock_classes list:
4086 hlist_del_rcu(&class->hash_entry);
4087 list_del_rcu(&class->lock_entry);
4089 RCU_INIT_POINTER(class->key, NULL);
4090 RCU_INIT_POINTER(class->name, NULL);
4093 static inline int within(const void *addr, void *start, unsigned long size)
4095 return addr >= start && addr < start + size;
4099 * Used in module.c to remove lock classes from memory that is going to be
4100 * freed; and possibly re-used by other modules.
4102 * We will have had one sync_sched() before getting here, so we're guaranteed
4103 * nobody will look up these exact classes -- they're properly dead but still
4106 void lockdep_free_key_range(void *start, unsigned long size)
4108 struct lock_class *class;
4109 struct hlist_head *head;
4110 unsigned long flags;
4114 raw_local_irq_save(flags);
4115 locked = graph_lock();
4118 * Unhash all classes that were created by this module:
4120 for (i = 0; i < CLASSHASH_SIZE; i++) {
4121 head = classhash_table + i;
4122 hlist_for_each_entry_rcu(class, head, hash_entry) {
4123 if (within(class->key, start, size))
4125 else if (within(class->name, start, size))
4132 raw_local_irq_restore(flags);
4135 * Wait for any possible iterators from look_up_lock_class() to pass
4136 * before continuing to free the memory they refer to.
4138 * sync_sched() is sufficient because the read-side is IRQ disable.
4140 synchronize_sched();
4143 * XXX at this point we could return the resources to the pool;
4144 * instead we leak them. We would need to change to bitmap allocators
4145 * instead of the linear allocators we have now.
4149 void lockdep_reset_lock(struct lockdep_map *lock)
4151 struct lock_class *class;
4152 struct hlist_head *head;
4153 unsigned long flags;
4157 raw_local_irq_save(flags);
4160 * Remove all classes this lock might have:
4162 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
4164 * If the class exists we look it up and zap it:
4166 class = look_up_lock_class(lock, j);
4171 * Debug check: in the end all mapped classes should
4174 locked = graph_lock();
4175 for (i = 0; i < CLASSHASH_SIZE; i++) {
4176 head = classhash_table + i;
4177 hlist_for_each_entry_rcu(class, head, hash_entry) {
4180 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
4181 match |= class == lock->class_cache[j];
4183 if (unlikely(match)) {
4184 if (debug_locks_off_graph_unlock()) {
4186 * We all just reset everything, how did it match?
4198 raw_local_irq_restore(flags);
4201 void __init lockdep_info(void)
4203 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4205 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
4206 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
4207 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
4208 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
4209 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
4210 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
4211 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
4213 printk(" memory used by lock dependency info: %lu kB\n",
4214 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4215 sizeof(struct list_head) * CLASSHASH_SIZE +
4216 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4217 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4218 sizeof(struct list_head) * CHAINHASH_SIZE
4219 #ifdef CONFIG_PROVE_LOCKING
4220 + sizeof(struct circular_queue)
4225 printk(" per task-struct memory footprint: %lu bytes\n",
4226 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4230 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4231 const void *mem_to, struct held_lock *hlock)
4233 if (!debug_locks_off())
4235 if (debug_locks_silent)
4239 printk("=========================\n");
4240 printk("[ BUG: held lock freed! ]\n");
4241 print_kernel_ident();
4242 printk("-------------------------\n");
4243 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4244 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4246 lockdep_print_held_locks(curr);
4248 printk("\nstack backtrace:\n");
4252 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4253 const void* lock_from, unsigned long lock_len)
4255 return lock_from + lock_len <= mem_from ||
4256 mem_from + mem_len <= lock_from;
4260 * Called when kernel memory is freed (or unmapped), or if a lock
4261 * is destroyed or reinitialized - this code checks whether there is
4262 * any held lock in the memory range of <from> to <to>:
4264 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4266 struct task_struct *curr = current;
4267 struct held_lock *hlock;
4268 unsigned long flags;
4271 if (unlikely(!debug_locks))
4274 local_irq_save(flags);
4275 for (i = 0; i < curr->lockdep_depth; i++) {
4276 hlock = curr->held_locks + i;
4278 if (not_in_range(mem_from, mem_len, hlock->instance,
4279 sizeof(*hlock->instance)))
4282 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4285 local_irq_restore(flags);
4287 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4289 static void print_held_locks_bug(void)
4291 if (!debug_locks_off())
4293 if (debug_locks_silent)
4297 printk("=====================================\n");
4298 printk("[ BUG: %s/%d still has locks held! ]\n",
4299 current->comm, task_pid_nr(current));
4300 print_kernel_ident();
4301 printk("-------------------------------------\n");
4302 lockdep_print_held_locks(current);
4303 printk("\nstack backtrace:\n");
4307 void debug_check_no_locks_held(void)
4309 if (unlikely(current->lockdep_depth > 0))
4310 print_held_locks_bug();
4312 EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
4315 void debug_show_all_locks(void)
4317 struct task_struct *g, *p;
4321 if (unlikely(!debug_locks)) {
4322 printk("INFO: lockdep is turned off.\n");
4325 printk("\nShowing all locks held in the system:\n");
4328 * Here we try to get the tasklist_lock as hard as possible,
4329 * if not successful after 2 seconds we ignore it (but keep
4330 * trying). This is to enable a debug printout even if a
4331 * tasklist_lock-holding task deadlocks or crashes.
4334 if (!read_trylock(&tasklist_lock)) {
4336 printk("hm, tasklist_lock locked, retrying... ");
4339 printk(" #%d", 10-count);
4343 printk(" ignoring it.\n");
4347 printk(KERN_CONT " locked it.\n");
4350 do_each_thread(g, p) {
4352 * It's not reliable to print a task's held locks
4353 * if it's not sleeping (or if it's not the current
4356 if (p->state == TASK_RUNNING && p != current)
4358 if (p->lockdep_depth)
4359 lockdep_print_held_locks(p);
4361 if (read_trylock(&tasklist_lock))
4363 } while_each_thread(g, p);
4366 printk("=============================================\n\n");
4369 read_unlock(&tasklist_lock);
4371 EXPORT_SYMBOL_GPL(debug_show_all_locks);
4375 * Careful: only use this function if you are sure that
4376 * the task cannot run in parallel!
4378 void debug_show_held_locks(struct task_struct *task)
4380 if (unlikely(!debug_locks)) {
4381 printk("INFO: lockdep is turned off.\n");
4384 lockdep_print_held_locks(task);
4386 EXPORT_SYMBOL_GPL(debug_show_held_locks);
4388 asmlinkage __visible void lockdep_sys_exit(void)
4390 struct task_struct *curr = current;
4392 if (unlikely(curr->lockdep_depth)) {
4393 if (!debug_locks_off())
4396 printk("================================================\n");
4397 printk("[ BUG: lock held when returning to user space! ]\n");
4398 print_kernel_ident();
4399 printk("------------------------------------------------\n");
4400 printk("%s/%d is leaving the kernel with locks still held!\n",
4401 curr->comm, curr->pid);
4402 lockdep_print_held_locks(curr);
4406 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4408 struct task_struct *curr = current;
4410 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4411 if (!debug_locks_off())
4413 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4414 /* Note: the following can be executed concurrently, so be careful. */
4416 pr_err("===============================\n");
4417 pr_err("[ ERR: suspicious RCU usage. ]\n");
4418 print_kernel_ident();
4419 pr_err("-------------------------------\n");
4420 pr_err("%s:%d %s!\n", file, line, s);
4421 pr_err("\nother info that might help us debug this:\n\n");
4422 pr_err("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4423 !rcu_lockdep_current_cpu_online()
4424 ? "RCU used illegally from offline CPU!\n"
4425 : !rcu_is_watching()
4426 ? "RCU used illegally from idle CPU!\n"
4428 rcu_scheduler_active, debug_locks);
4431 * If a CPU is in the RCU-free window in idle (ie: in the section
4432 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4433 * considers that CPU to be in an "extended quiescent state",
4434 * which means that RCU will be completely ignoring that CPU.
4435 * Therefore, rcu_read_lock() and friends have absolutely no
4436 * effect on a CPU running in that state. In other words, even if
4437 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4438 * delete data structures out from under it. RCU really has no
4439 * choice here: we need to keep an RCU-free window in idle where
4440 * the CPU may possibly enter into low power mode. This way we can
4441 * notice an extended quiescent state to other CPUs that started a grace
4442 * period. Otherwise we would delay any grace period as long as we run
4445 * So complain bitterly if someone does call rcu_read_lock(),
4446 * rcu_read_lock_bh() and so on from extended quiescent states.
4448 if (!rcu_is_watching())
4449 printk("RCU used illegally from extended quiescent state!\n");
4451 lockdep_print_held_locks(curr);
4452 printk("\nstack backtrace:\n");
4455 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);