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/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
47 #include <linux/kmemcheck.h>
48 #include <linux/random.h>
49 #include <linux/jhash.h>
51 #include <asm/sections.h>
53 #include "lockdep_internals.h"
55 #define CREATE_TRACE_POINTS
56 #include <trace/events/lock.h>
58 #ifdef CONFIG_PROVE_LOCKING
59 int prove_locking = 1;
60 module_param(prove_locking, int, 0644);
62 #define prove_locking 0
65 #ifdef CONFIG_LOCK_STAT
67 module_param(lock_stat, int, 0644);
73 * lockdep_lock: protects the lockdep graph, the hashes and the
74 * class/list/hash allocators.
76 * This is one of the rare exceptions where it's justified
77 * to use a raw spinlock - we really dont want the spinlock
78 * code to recurse back into the lockdep code...
80 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
82 static int graph_lock(void)
84 arch_spin_lock(&lockdep_lock);
86 * Make sure that if another CPU detected a bug while
87 * walking the graph we dont change it (while the other
88 * CPU is busy printing out stuff with the graph lock
92 arch_spin_unlock(&lockdep_lock);
95 /* prevent any recursions within lockdep from causing deadlocks */
96 current->lockdep_recursion++;
100 static inline int graph_unlock(void)
102 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
104 * The lockdep graph lock isn't locked while we expect it to
105 * be, we're confused now, bye!
107 return DEBUG_LOCKS_WARN_ON(1);
110 current->lockdep_recursion--;
111 arch_spin_unlock(&lockdep_lock);
116 * Turn lock debugging off and return with 0 if it was off already,
117 * and also release the graph lock:
119 static inline int debug_locks_off_graph_unlock(void)
121 int ret = debug_locks_off();
123 arch_spin_unlock(&lockdep_lock);
128 unsigned long nr_list_entries;
129 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
132 * All data structures here are protected by the global debug_lock.
134 * Mutex key structs only get allocated, once during bootup, and never
135 * get freed - this significantly simplifies the debugging code.
137 unsigned long nr_lock_classes;
138 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
140 static inline struct lock_class *hlock_class(struct held_lock *hlock)
142 if (!hlock->class_idx) {
144 * Someone passed in garbage, we give up.
146 DEBUG_LOCKS_WARN_ON(1);
149 return lock_classes + hlock->class_idx - 1;
152 #ifdef CONFIG_LOCK_STAT
153 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
155 static inline u64 lockstat_clock(void)
157 return local_clock();
160 static int lock_point(unsigned long points[], unsigned long ip)
164 for (i = 0; i < LOCKSTAT_POINTS; i++) {
165 if (points[i] == 0) {
176 static void lock_time_inc(struct lock_time *lt, u64 time)
181 if (time < lt->min || !lt->nr)
188 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
193 if (src->max > dst->max)
196 if (src->min < dst->min || !dst->nr)
199 dst->total += src->total;
203 struct lock_class_stats lock_stats(struct lock_class *class)
205 struct lock_class_stats stats;
208 memset(&stats, 0, sizeof(struct lock_class_stats));
209 for_each_possible_cpu(cpu) {
210 struct lock_class_stats *pcs =
211 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
213 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
214 stats.contention_point[i] += pcs->contention_point[i];
216 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
217 stats.contending_point[i] += pcs->contending_point[i];
219 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
220 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
222 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
223 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
225 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
226 stats.bounces[i] += pcs->bounces[i];
232 void clear_lock_stats(struct lock_class *class)
236 for_each_possible_cpu(cpu) {
237 struct lock_class_stats *cpu_stats =
238 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
240 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
242 memset(class->contention_point, 0, sizeof(class->contention_point));
243 memset(class->contending_point, 0, sizeof(class->contending_point));
246 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
248 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
251 static void put_lock_stats(struct lock_class_stats *stats)
253 put_cpu_var(cpu_lock_stats);
256 static void lock_release_holdtime(struct held_lock *hlock)
258 struct lock_class_stats *stats;
264 holdtime = lockstat_clock() - hlock->holdtime_stamp;
266 stats = get_lock_stats(hlock_class(hlock));
268 lock_time_inc(&stats->read_holdtime, holdtime);
270 lock_time_inc(&stats->write_holdtime, holdtime);
271 put_lock_stats(stats);
274 static inline void lock_release_holdtime(struct held_lock *hlock)
280 * We keep a global list of all lock classes. The list only grows,
281 * never shrinks. The list is only accessed with the lockdep
282 * spinlock lock held.
284 LIST_HEAD(all_lock_classes);
287 * The lockdep classes are in a hash-table as well, for fast lookup:
289 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
290 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
291 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
292 #define classhashentry(key) (classhash_table + __classhashfn((key)))
294 static struct hlist_head classhash_table[CLASSHASH_SIZE];
297 * We put the lock dependency chains into a hash-table as well, to cache
300 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
301 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
302 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
303 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
305 static struct hlist_head chainhash_table[CHAINHASH_SIZE];
308 * The hash key of the lock dependency chains is a hash itself too:
309 * it's a hash of all locks taken up to that lock, including that lock.
310 * It's a 64-bit hash, because it's important for the keys to be
313 static inline u64 iterate_chain_key(u64 key, u32 idx)
315 u32 k0 = key, k1 = key >> 32;
317 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
319 return k0 | (u64)k1 << 32;
322 void lockdep_off(void)
324 current->lockdep_recursion++;
326 EXPORT_SYMBOL(lockdep_off);
328 void lockdep_on(void)
330 current->lockdep_recursion--;
332 EXPORT_SYMBOL(lockdep_on);
335 * Debugging switches:
339 #define VERY_VERBOSE 0
342 # define HARDIRQ_VERBOSE 1
343 # define SOFTIRQ_VERBOSE 1
344 # define RECLAIM_VERBOSE 1
346 # define HARDIRQ_VERBOSE 0
347 # define SOFTIRQ_VERBOSE 0
348 # define RECLAIM_VERBOSE 0
351 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
353 * Quick filtering for interesting events:
355 static int class_filter(struct lock_class *class)
359 if (class->name_version == 1 &&
360 !strcmp(class->name, "lockname"))
362 if (class->name_version == 1 &&
363 !strcmp(class->name, "&struct->lockfield"))
366 /* Filter everything else. 1 would be to allow everything else */
371 static int verbose(struct lock_class *class)
374 return class_filter(class);
380 * Stack-trace: tightly packed array of stack backtrace
381 * addresses. Protected by the graph_lock.
383 unsigned long nr_stack_trace_entries;
384 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
386 static void print_lockdep_off(const char *bug_msg)
388 printk(KERN_DEBUG "%s\n", bug_msg);
389 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
390 #ifdef CONFIG_LOCK_STAT
391 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
395 static int save_trace(struct stack_trace *trace)
397 trace->nr_entries = 0;
398 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
399 trace->entries = stack_trace + nr_stack_trace_entries;
403 save_stack_trace(trace);
406 * Some daft arches put -1 at the end to indicate its a full trace.
408 * <rant> this is buggy anyway, since it takes a whole extra entry so a
409 * complete trace that maxes out the entries provided will be reported
410 * as incomplete, friggin useless </rant>
412 if (trace->nr_entries != 0 &&
413 trace->entries[trace->nr_entries-1] == ULONG_MAX)
416 trace->max_entries = trace->nr_entries;
418 nr_stack_trace_entries += trace->nr_entries;
420 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
421 if (!debug_locks_off_graph_unlock())
424 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
433 unsigned int nr_hardirq_chains;
434 unsigned int nr_softirq_chains;
435 unsigned int nr_process_chains;
436 unsigned int max_lockdep_depth;
438 #ifdef CONFIG_DEBUG_LOCKDEP
440 * Various lockdep statistics:
442 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
449 #define __USAGE(__STATE) \
450 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
451 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
452 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
453 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
455 static const char *usage_str[] =
457 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
458 #include "lockdep_states.h"
460 [LOCK_USED] = "INITIAL USE",
463 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
465 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
468 static inline unsigned long lock_flag(enum lock_usage_bit bit)
473 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
477 if (class->usage_mask & lock_flag(bit + 2))
479 if (class->usage_mask & lock_flag(bit)) {
481 if (class->usage_mask & lock_flag(bit + 2))
488 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
492 #define LOCKDEP_STATE(__STATE) \
493 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
494 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
495 #include "lockdep_states.h"
501 static void __print_lock_name(struct lock_class *class)
503 char str[KSYM_NAME_LEN];
508 name = __get_key_name(class->key, str);
509 printk(KERN_CONT "%s", name);
511 printk(KERN_CONT "%s", name);
512 if (class->name_version > 1)
513 printk(KERN_CONT "#%d", class->name_version);
515 printk(KERN_CONT "/%d", class->subclass);
519 static void print_lock_name(struct lock_class *class)
521 char usage[LOCK_USAGE_CHARS];
523 get_usage_chars(class, usage);
525 printk(KERN_CONT " (");
526 __print_lock_name(class);
527 printk(KERN_CONT "){%s}", usage);
530 static void print_lockdep_cache(struct lockdep_map *lock)
533 char str[KSYM_NAME_LEN];
537 name = __get_key_name(lock->key->subkeys, str);
539 printk(KERN_CONT "%s", name);
542 static void print_lock(struct held_lock *hlock)
545 * We can be called locklessly through debug_show_all_locks() so be
546 * extra careful, the hlock might have been released and cleared.
548 unsigned int class_idx = hlock->class_idx;
550 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
553 if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
554 printk(KERN_CONT "<RELEASED>\n");
558 print_lock_name(lock_classes + class_idx - 1);
559 printk(KERN_CONT ", at: [<%p>] %pS\n",
560 (void *)hlock->acquire_ip, (void *)hlock->acquire_ip);
563 static void lockdep_print_held_locks(struct task_struct *curr)
565 int i, depth = curr->lockdep_depth;
568 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
571 printk("%d lock%s held by %s/%d:\n",
572 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
574 for (i = 0; i < depth; i++) {
576 print_lock(curr->held_locks + i);
580 static void print_kernel_ident(void)
582 printk("%s %.*s %s\n", init_utsname()->release,
583 (int)strcspn(init_utsname()->version, " "),
584 init_utsname()->version,
588 static int very_verbose(struct lock_class *class)
591 return class_filter(class);
597 * Is this the address of a static object:
600 static int static_obj(void *obj)
602 unsigned long start = (unsigned long) &_stext,
603 end = (unsigned long) &_end,
604 addr = (unsigned long) obj;
609 if ((addr >= start) && (addr < end))
612 if (arch_is_kernel_data(addr))
616 * in-kernel percpu var?
618 if (is_kernel_percpu_address(addr))
622 * module static or percpu var?
624 return is_module_address(addr) || is_module_percpu_address(addr);
629 * To make lock name printouts unique, we calculate a unique
630 * class->name_version generation counter:
632 static int count_matching_names(struct lock_class *new_class)
634 struct lock_class *class;
637 if (!new_class->name)
640 list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
641 if (new_class->key - new_class->subclass == class->key)
642 return class->name_version;
643 if (class->name && !strcmp(class->name, new_class->name))
644 count = max(count, class->name_version);
651 * Register a lock's class in the hash-table, if the class is not present
652 * yet. Otherwise we look it up. We cache the result in the lock object
653 * itself, so actual lookup of the hash should be once per lock object.
655 static inline struct lock_class *
656 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
658 struct lockdep_subclass_key *key;
659 struct hlist_head *hash_head;
660 struct lock_class *class;
662 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
665 "BUG: looking up invalid subclass: %u\n", subclass);
667 "turning off the locking correctness validator.\n");
673 * Static locks do not have their class-keys yet - for them the key
674 * is the lock object itself:
676 if (unlikely(!lock->key))
677 lock->key = (void *)lock;
680 * NOTE: the class-key must be unique. For dynamic locks, a static
681 * lock_class_key variable is passed in through the mutex_init()
682 * (or spin_lock_init()) call - which acts as the key. For static
683 * locks we use the lock object itself as the key.
685 BUILD_BUG_ON(sizeof(struct lock_class_key) >
686 sizeof(struct lockdep_map));
688 key = lock->key->subkeys + subclass;
690 hash_head = classhashentry(key);
693 * We do an RCU walk of the hash, see lockdep_free_key_range().
695 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
698 hlist_for_each_entry_rcu_notrace(class, hash_head, hash_entry) {
699 if (class->key == key) {
701 * Huh! same key, different name? Did someone trample
702 * on some memory? We're most confused.
704 WARN_ON_ONCE(class->name != lock->name);
713 * Register a lock's class in the hash-table, if the class is not present
714 * yet. Otherwise we look it up. We cache the result in the lock object
715 * itself, so actual lookup of the hash should be once per lock object.
717 static struct lock_class *
718 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
720 struct lockdep_subclass_key *key;
721 struct hlist_head *hash_head;
722 struct lock_class *class;
724 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
726 class = look_up_lock_class(lock, subclass);
728 goto out_set_class_cache;
731 * Debug-check: all keys must be persistent!
733 if (!static_obj(lock->key)) {
735 printk("INFO: trying to register non-static key.\n");
736 printk("the code is fine but needs lockdep annotation.\n");
737 printk("turning off the locking correctness validator.\n");
743 key = lock->key->subkeys + subclass;
744 hash_head = classhashentry(key);
750 * We have to do the hash-walk again, to avoid races
753 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
754 if (class->key == key)
759 * Allocate a new key from the static array, and add it to
762 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
763 if (!debug_locks_off_graph_unlock()) {
767 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
771 class = lock_classes + nr_lock_classes++;
772 debug_atomic_inc(nr_unused_locks);
774 class->name = lock->name;
775 class->subclass = subclass;
776 INIT_LIST_HEAD(&class->lock_entry);
777 INIT_LIST_HEAD(&class->locks_before);
778 INIT_LIST_HEAD(&class->locks_after);
779 class->name_version = count_matching_names(class);
781 * We use RCU's safe list-add method to make
782 * parallel walking of the hash-list safe:
784 hlist_add_head_rcu(&class->hash_entry, hash_head);
786 * Add it to the global list of classes:
788 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
790 if (verbose(class)) {
793 printk("\nnew class %p: %s", class->key, class->name);
794 if (class->name_version > 1)
795 printk(KERN_CONT "#%d", class->name_version);
796 printk(KERN_CONT "\n");
807 if (!subclass || force)
808 lock->class_cache[0] = class;
809 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
810 lock->class_cache[subclass] = class;
813 * Hash collision, did we smoke some? We found a class with a matching
814 * hash but the subclass -- which is hashed in -- didn't match.
816 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
822 #ifdef CONFIG_PROVE_LOCKING
824 * Allocate a lockdep entry. (assumes the graph_lock held, returns
825 * with NULL on failure)
827 static struct lock_list *alloc_list_entry(void)
829 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
830 if (!debug_locks_off_graph_unlock())
833 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
837 return list_entries + nr_list_entries++;
841 * Add a new dependency to the head of the list:
843 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
844 struct list_head *head, unsigned long ip,
845 int distance, struct stack_trace *trace)
847 struct lock_list *entry;
849 * Lock not present yet - get a new dependency struct and
850 * add it to the list:
852 entry = alloc_list_entry();
857 entry->distance = distance;
858 entry->trace = *trace;
860 * Both allocation and removal are done under the graph lock; but
861 * iteration is under RCU-sched; see look_up_lock_class() and
862 * lockdep_free_key_range().
864 list_add_tail_rcu(&entry->entry, head);
870 * For good efficiency of modular, we use power of 2
872 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
873 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
876 * The circular_queue and helpers is used to implement the
877 * breadth-first search(BFS)algorithem, by which we can build
878 * the shortest path from the next lock to be acquired to the
879 * previous held lock if there is a circular between them.
881 struct circular_queue {
882 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
883 unsigned int front, rear;
886 static struct circular_queue lock_cq;
888 unsigned int max_bfs_queue_depth;
890 static unsigned int lockdep_dependency_gen_id;
892 static inline void __cq_init(struct circular_queue *cq)
894 cq->front = cq->rear = 0;
895 lockdep_dependency_gen_id++;
898 static inline int __cq_empty(struct circular_queue *cq)
900 return (cq->front == cq->rear);
903 static inline int __cq_full(struct circular_queue *cq)
905 return ((cq->rear + 1) & CQ_MASK) == cq->front;
908 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
913 cq->element[cq->rear] = elem;
914 cq->rear = (cq->rear + 1) & CQ_MASK;
918 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
923 *elem = cq->element[cq->front];
924 cq->front = (cq->front + 1) & CQ_MASK;
928 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
930 return (cq->rear - cq->front) & CQ_MASK;
933 static inline void mark_lock_accessed(struct lock_list *lock,
934 struct lock_list *parent)
938 nr = lock - list_entries;
939 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
940 lock->parent = parent;
941 lock->class->dep_gen_id = lockdep_dependency_gen_id;
944 static inline unsigned long lock_accessed(struct lock_list *lock)
948 nr = lock - list_entries;
949 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
950 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
953 static inline struct lock_list *get_lock_parent(struct lock_list *child)
955 return child->parent;
958 static inline int get_lock_depth(struct lock_list *child)
961 struct lock_list *parent;
963 while ((parent = get_lock_parent(child))) {
970 static int __bfs(struct lock_list *source_entry,
972 int (*match)(struct lock_list *entry, void *data),
973 struct lock_list **target_entry,
976 struct lock_list *entry;
977 struct list_head *head;
978 struct circular_queue *cq = &lock_cq;
981 if (match(source_entry, data)) {
982 *target_entry = source_entry;
988 head = &source_entry->class->locks_after;
990 head = &source_entry->class->locks_before;
992 if (list_empty(head))
996 __cq_enqueue(cq, (unsigned long)source_entry);
998 while (!__cq_empty(cq)) {
999 struct lock_list *lock;
1001 __cq_dequeue(cq, (unsigned long *)&lock);
1009 head = &lock->class->locks_after;
1011 head = &lock->class->locks_before;
1013 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1015 list_for_each_entry_rcu(entry, head, entry) {
1016 if (!lock_accessed(entry)) {
1017 unsigned int cq_depth;
1018 mark_lock_accessed(entry, lock);
1019 if (match(entry, data)) {
1020 *target_entry = entry;
1025 if (__cq_enqueue(cq, (unsigned long)entry)) {
1029 cq_depth = __cq_get_elem_count(cq);
1030 if (max_bfs_queue_depth < cq_depth)
1031 max_bfs_queue_depth = cq_depth;
1039 static inline int __bfs_forwards(struct lock_list *src_entry,
1041 int (*match)(struct lock_list *entry, void *data),
1042 struct lock_list **target_entry)
1044 return __bfs(src_entry, data, match, target_entry, 1);
1048 static inline int __bfs_backwards(struct lock_list *src_entry,
1050 int (*match)(struct lock_list *entry, void *data),
1051 struct lock_list **target_entry)
1053 return __bfs(src_entry, data, match, target_entry, 0);
1058 * Recursive, forwards-direction lock-dependency checking, used for
1059 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1064 * Print a dependency chain entry (this is only done when a deadlock
1065 * has been detected):
1068 print_circular_bug_entry(struct lock_list *target, int depth)
1070 if (debug_locks_silent)
1072 printk("\n-> #%u", depth);
1073 print_lock_name(target->class);
1074 printk(KERN_CONT ":\n");
1075 print_stack_trace(&target->trace, 6);
1081 print_circular_lock_scenario(struct held_lock *src,
1082 struct held_lock *tgt,
1083 struct lock_list *prt)
1085 struct lock_class *source = hlock_class(src);
1086 struct lock_class *target = hlock_class(tgt);
1087 struct lock_class *parent = prt->class;
1090 * A direct locking problem where unsafe_class lock is taken
1091 * directly by safe_class lock, then all we need to show
1092 * is the deadlock scenario, as it is obvious that the
1093 * unsafe lock is taken under the safe lock.
1095 * But if there is a chain instead, where the safe lock takes
1096 * an intermediate lock (middle_class) where this lock is
1097 * not the same as the safe lock, then the lock chain is
1098 * used to describe the problem. Otherwise we would need
1099 * to show a different CPU case for each link in the chain
1100 * from the safe_class lock to the unsafe_class lock.
1102 if (parent != source) {
1103 printk("Chain exists of:\n ");
1104 __print_lock_name(source);
1105 printk(KERN_CONT " --> ");
1106 __print_lock_name(parent);
1107 printk(KERN_CONT " --> ");
1108 __print_lock_name(target);
1109 printk(KERN_CONT "\n\n");
1112 printk(" Possible unsafe locking scenario:\n\n");
1113 printk(" CPU0 CPU1\n");
1114 printk(" ---- ----\n");
1116 __print_lock_name(target);
1117 printk(KERN_CONT ");\n");
1119 __print_lock_name(parent);
1120 printk(KERN_CONT ");\n");
1122 __print_lock_name(target);
1123 printk(KERN_CONT ");\n");
1125 __print_lock_name(source);
1126 printk(KERN_CONT ");\n");
1127 printk("\n *** DEADLOCK ***\n\n");
1131 * When a circular dependency is detected, print the
1135 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1136 struct held_lock *check_src,
1137 struct held_lock *check_tgt)
1139 struct task_struct *curr = current;
1141 if (debug_locks_silent)
1145 printk("======================================================\n");
1146 printk("[ INFO: possible circular locking dependency detected ]\n");
1147 print_kernel_ident();
1148 printk("-------------------------------------------------------\n");
1149 printk("%s/%d is trying to acquire lock:\n",
1150 curr->comm, task_pid_nr(curr));
1151 print_lock(check_src);
1152 printk("\nbut task is already holding lock:\n");
1153 print_lock(check_tgt);
1154 printk("\nwhich lock already depends on the new lock.\n\n");
1155 printk("\nthe existing dependency chain (in reverse order) is:\n");
1157 print_circular_bug_entry(entry, depth);
1162 static inline int class_equal(struct lock_list *entry, void *data)
1164 return entry->class == data;
1167 static noinline int print_circular_bug(struct lock_list *this,
1168 struct lock_list *target,
1169 struct held_lock *check_src,
1170 struct held_lock *check_tgt)
1172 struct task_struct *curr = current;
1173 struct lock_list *parent;
1174 struct lock_list *first_parent;
1177 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1180 if (!save_trace(&this->trace))
1183 depth = get_lock_depth(target);
1185 print_circular_bug_header(target, depth, check_src, check_tgt);
1187 parent = get_lock_parent(target);
1188 first_parent = parent;
1191 print_circular_bug_entry(parent, --depth);
1192 parent = get_lock_parent(parent);
1195 printk("\nother info that might help us debug this:\n\n");
1196 print_circular_lock_scenario(check_src, check_tgt,
1199 lockdep_print_held_locks(curr);
1201 printk("\nstack backtrace:\n");
1207 static noinline int print_bfs_bug(int ret)
1209 if (!debug_locks_off_graph_unlock())
1213 * Breadth-first-search failed, graph got corrupted?
1215 WARN(1, "lockdep bfs error:%d\n", ret);
1220 static int noop_count(struct lock_list *entry, void *data)
1222 (*(unsigned long *)data)++;
1226 static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1228 unsigned long count = 0;
1229 struct lock_list *uninitialized_var(target_entry);
1231 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1235 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1237 unsigned long ret, flags;
1238 struct lock_list this;
1243 raw_local_irq_save(flags);
1244 current->lockdep_recursion = 1;
1245 arch_spin_lock(&lockdep_lock);
1246 ret = __lockdep_count_forward_deps(&this);
1247 arch_spin_unlock(&lockdep_lock);
1248 current->lockdep_recursion = 0;
1249 raw_local_irq_restore(flags);
1254 static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1256 unsigned long count = 0;
1257 struct lock_list *uninitialized_var(target_entry);
1259 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1264 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1266 unsigned long ret, flags;
1267 struct lock_list this;
1272 raw_local_irq_save(flags);
1273 current->lockdep_recursion = 1;
1274 arch_spin_lock(&lockdep_lock);
1275 ret = __lockdep_count_backward_deps(&this);
1276 arch_spin_unlock(&lockdep_lock);
1277 current->lockdep_recursion = 0;
1278 raw_local_irq_restore(flags);
1284 * Prove that the dependency graph starting at <entry> can not
1285 * lead to <target>. Print an error and return 0 if it does.
1288 check_noncircular(struct lock_list *root, struct lock_class *target,
1289 struct lock_list **target_entry)
1293 debug_atomic_inc(nr_cyclic_checks);
1295 result = __bfs_forwards(root, target, class_equal, target_entry);
1300 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1302 * Forwards and backwards subgraph searching, for the purposes of
1303 * proving that two subgraphs can be connected by a new dependency
1304 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1307 static inline int usage_match(struct lock_list *entry, void *bit)
1309 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1315 * Find a node in the forwards-direction dependency sub-graph starting
1316 * at @root->class that matches @bit.
1318 * Return 0 if such a node exists in the subgraph, and put that node
1319 * into *@target_entry.
1321 * Return 1 otherwise and keep *@target_entry unchanged.
1322 * Return <0 on error.
1325 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1326 struct lock_list **target_entry)
1330 debug_atomic_inc(nr_find_usage_forwards_checks);
1332 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1338 * Find a node in the backwards-direction dependency sub-graph starting
1339 * at @root->class that matches @bit.
1341 * Return 0 if such a node exists in the subgraph, and put that node
1342 * into *@target_entry.
1344 * Return 1 otherwise and keep *@target_entry unchanged.
1345 * Return <0 on error.
1348 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1349 struct lock_list **target_entry)
1353 debug_atomic_inc(nr_find_usage_backwards_checks);
1355 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1360 static void print_lock_class_header(struct lock_class *class, int depth)
1364 printk("%*s->", depth, "");
1365 print_lock_name(class);
1366 printk(KERN_CONT " ops: %lu", class->ops);
1367 printk(KERN_CONT " {\n");
1369 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1370 if (class->usage_mask & (1 << bit)) {
1373 len += printk("%*s %s", depth, "", usage_str[bit]);
1374 len += printk(KERN_CONT " at:\n");
1375 print_stack_trace(class->usage_traces + bit, len);
1378 printk("%*s }\n", depth, "");
1380 printk("%*s ... key at: [<%p>] %pS\n",
1381 depth, "", class->key, class->key);
1385 * printk the shortest lock dependencies from @start to @end in reverse order:
1388 print_shortest_lock_dependencies(struct lock_list *leaf,
1389 struct lock_list *root)
1391 struct lock_list *entry = leaf;
1394 /*compute depth from generated tree by BFS*/
1395 depth = get_lock_depth(leaf);
1398 print_lock_class_header(entry->class, depth);
1399 printk("%*s ... acquired at:\n", depth, "");
1400 print_stack_trace(&entry->trace, 2);
1403 if (depth == 0 && (entry != root)) {
1404 printk("lockdep:%s bad path found in chain graph\n", __func__);
1408 entry = get_lock_parent(entry);
1410 } while (entry && (depth >= 0));
1416 print_irq_lock_scenario(struct lock_list *safe_entry,
1417 struct lock_list *unsafe_entry,
1418 struct lock_class *prev_class,
1419 struct lock_class *next_class)
1421 struct lock_class *safe_class = safe_entry->class;
1422 struct lock_class *unsafe_class = unsafe_entry->class;
1423 struct lock_class *middle_class = prev_class;
1425 if (middle_class == safe_class)
1426 middle_class = next_class;
1429 * A direct locking problem where unsafe_class lock is taken
1430 * directly by safe_class lock, then all we need to show
1431 * is the deadlock scenario, as it is obvious that the
1432 * unsafe lock is taken under the safe lock.
1434 * But if there is a chain instead, where the safe lock takes
1435 * an intermediate lock (middle_class) where this lock is
1436 * not the same as the safe lock, then the lock chain is
1437 * used to describe the problem. Otherwise we would need
1438 * to show a different CPU case for each link in the chain
1439 * from the safe_class lock to the unsafe_class lock.
1441 if (middle_class != unsafe_class) {
1442 printk("Chain exists of:\n ");
1443 __print_lock_name(safe_class);
1444 printk(KERN_CONT " --> ");
1445 __print_lock_name(middle_class);
1446 printk(KERN_CONT " --> ");
1447 __print_lock_name(unsafe_class);
1448 printk(KERN_CONT "\n\n");
1451 printk(" Possible interrupt unsafe locking scenario:\n\n");
1452 printk(" CPU0 CPU1\n");
1453 printk(" ---- ----\n");
1455 __print_lock_name(unsafe_class);
1456 printk(KERN_CONT ");\n");
1457 printk(" local_irq_disable();\n");
1459 __print_lock_name(safe_class);
1460 printk(KERN_CONT ");\n");
1462 __print_lock_name(middle_class);
1463 printk(KERN_CONT ");\n");
1464 printk(" <Interrupt>\n");
1466 __print_lock_name(safe_class);
1467 printk(KERN_CONT ");\n");
1468 printk("\n *** DEADLOCK ***\n\n");
1472 print_bad_irq_dependency(struct task_struct *curr,
1473 struct lock_list *prev_root,
1474 struct lock_list *next_root,
1475 struct lock_list *backwards_entry,
1476 struct lock_list *forwards_entry,
1477 struct held_lock *prev,
1478 struct held_lock *next,
1479 enum lock_usage_bit bit1,
1480 enum lock_usage_bit bit2,
1481 const char *irqclass)
1483 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1487 printk("======================================================\n");
1488 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1489 irqclass, irqclass);
1490 print_kernel_ident();
1491 printk("------------------------------------------------------\n");
1492 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1493 curr->comm, task_pid_nr(curr),
1494 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1495 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1496 curr->hardirqs_enabled,
1497 curr->softirqs_enabled);
1500 printk("\nand this task is already holding:\n");
1502 printk("which would create a new lock dependency:\n");
1503 print_lock_name(hlock_class(prev));
1504 printk(KERN_CONT " ->");
1505 print_lock_name(hlock_class(next));
1506 printk(KERN_CONT "\n");
1508 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1510 print_lock_name(backwards_entry->class);
1511 printk("\n... which became %s-irq-safe at:\n", irqclass);
1513 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1515 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1516 print_lock_name(forwards_entry->class);
1517 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1520 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1522 printk("\nother info that might help us debug this:\n\n");
1523 print_irq_lock_scenario(backwards_entry, forwards_entry,
1524 hlock_class(prev), hlock_class(next));
1526 lockdep_print_held_locks(curr);
1528 printk("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
1529 if (!save_trace(&prev_root->trace))
1531 print_shortest_lock_dependencies(backwards_entry, prev_root);
1533 printk("\nthe dependencies between the lock to be acquired");
1534 printk(" and %s-irq-unsafe lock:\n", irqclass);
1535 if (!save_trace(&next_root->trace))
1537 print_shortest_lock_dependencies(forwards_entry, next_root);
1539 printk("\nstack backtrace:\n");
1546 check_usage(struct task_struct *curr, struct held_lock *prev,
1547 struct held_lock *next, enum lock_usage_bit bit_backwards,
1548 enum lock_usage_bit bit_forwards, const char *irqclass)
1551 struct lock_list this, that;
1552 struct lock_list *uninitialized_var(target_entry);
1553 struct lock_list *uninitialized_var(target_entry1);
1557 this.class = hlock_class(prev);
1558 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1560 return print_bfs_bug(ret);
1565 that.class = hlock_class(next);
1566 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1568 return print_bfs_bug(ret);
1572 return print_bad_irq_dependency(curr, &this, &that,
1573 target_entry, target_entry1,
1575 bit_backwards, bit_forwards, irqclass);
1578 static const char *state_names[] = {
1579 #define LOCKDEP_STATE(__STATE) \
1580 __stringify(__STATE),
1581 #include "lockdep_states.h"
1582 #undef LOCKDEP_STATE
1585 static const char *state_rnames[] = {
1586 #define LOCKDEP_STATE(__STATE) \
1587 __stringify(__STATE)"-READ",
1588 #include "lockdep_states.h"
1589 #undef LOCKDEP_STATE
1592 static inline const char *state_name(enum lock_usage_bit bit)
1594 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1597 static int exclusive_bit(int new_bit)
1605 * bit 0 - write/read
1606 * bit 1 - used_in/enabled
1610 int state = new_bit & ~3;
1611 int dir = new_bit & 2;
1614 * keep state, bit flip the direction and strip read.
1616 return state | (dir ^ 2);
1619 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1620 struct held_lock *next, enum lock_usage_bit bit)
1623 * Prove that the new dependency does not connect a hardirq-safe
1624 * lock with a hardirq-unsafe lock - to achieve this we search
1625 * the backwards-subgraph starting at <prev>, and the
1626 * forwards-subgraph starting at <next>:
1628 if (!check_usage(curr, prev, next, bit,
1629 exclusive_bit(bit), state_name(bit)))
1635 * Prove that the new dependency does not connect a hardirq-safe-read
1636 * lock with a hardirq-unsafe lock - to achieve this we search
1637 * the backwards-subgraph starting at <prev>, and the
1638 * forwards-subgraph starting at <next>:
1640 if (!check_usage(curr, prev, next, bit,
1641 exclusive_bit(bit), state_name(bit)))
1648 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1649 struct held_lock *next)
1651 #define LOCKDEP_STATE(__STATE) \
1652 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1654 #include "lockdep_states.h"
1655 #undef LOCKDEP_STATE
1660 static void inc_chains(void)
1662 if (current->hardirq_context)
1663 nr_hardirq_chains++;
1665 if (current->softirq_context)
1666 nr_softirq_chains++;
1668 nr_process_chains++;
1675 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1676 struct held_lock *next)
1681 static inline void inc_chains(void)
1683 nr_process_chains++;
1689 print_deadlock_scenario(struct held_lock *nxt,
1690 struct held_lock *prv)
1692 struct lock_class *next = hlock_class(nxt);
1693 struct lock_class *prev = hlock_class(prv);
1695 printk(" Possible unsafe locking scenario:\n\n");
1699 __print_lock_name(prev);
1700 printk(KERN_CONT ");\n");
1702 __print_lock_name(next);
1703 printk(KERN_CONT ");\n");
1704 printk("\n *** DEADLOCK ***\n\n");
1705 printk(" May be due to missing lock nesting notation\n\n");
1709 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1710 struct held_lock *next)
1712 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1716 printk("=============================================\n");
1717 printk("[ INFO: possible recursive locking detected ]\n");
1718 print_kernel_ident();
1719 printk("---------------------------------------------\n");
1720 printk("%s/%d is trying to acquire lock:\n",
1721 curr->comm, task_pid_nr(curr));
1723 printk("\nbut task is already holding lock:\n");
1726 printk("\nother info that might help us debug this:\n");
1727 print_deadlock_scenario(next, prev);
1728 lockdep_print_held_locks(curr);
1730 printk("\nstack backtrace:\n");
1737 * Check whether we are holding such a class already.
1739 * (Note that this has to be done separately, because the graph cannot
1740 * detect such classes of deadlocks.)
1742 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1745 check_deadlock(struct task_struct *curr, struct held_lock *next,
1746 struct lockdep_map *next_instance, int read)
1748 struct held_lock *prev;
1749 struct held_lock *nest = NULL;
1752 for (i = 0; i < curr->lockdep_depth; i++) {
1753 prev = curr->held_locks + i;
1755 if (prev->instance == next->nest_lock)
1758 if (hlock_class(prev) != hlock_class(next))
1762 * Allow read-after-read recursion of the same
1763 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1765 if ((read == 2) && prev->read)
1769 * We're holding the nest_lock, which serializes this lock's
1770 * nesting behaviour.
1775 return print_deadlock_bug(curr, prev, next);
1781 * There was a chain-cache miss, and we are about to add a new dependency
1782 * to a previous lock. We recursively validate the following rules:
1784 * - would the adding of the <prev> -> <next> dependency create a
1785 * circular dependency in the graph? [== circular deadlock]
1787 * - does the new prev->next dependency connect any hardirq-safe lock
1788 * (in the full backwards-subgraph starting at <prev>) with any
1789 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1790 * <next>)? [== illegal lock inversion with hardirq contexts]
1792 * - does the new prev->next dependency connect any softirq-safe lock
1793 * (in the full backwards-subgraph starting at <prev>) with any
1794 * softirq-unsafe lock (in the full forwards-subgraph starting at
1795 * <next>)? [== illegal lock inversion with softirq contexts]
1797 * any of these scenarios could lead to a deadlock.
1799 * Then if all the validations pass, we add the forwards and backwards
1803 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1804 struct held_lock *next, int distance, int *stack_saved)
1806 struct lock_list *entry;
1808 struct lock_list this;
1809 struct lock_list *uninitialized_var(target_entry);
1811 * Static variable, serialized by the graph_lock().
1813 * We use this static variable to save the stack trace in case
1814 * we call into this function multiple times due to encountering
1815 * trylocks in the held lock stack.
1817 static struct stack_trace trace;
1820 * Prove that the new <prev> -> <next> dependency would not
1821 * create a circular dependency in the graph. (We do this by
1822 * forward-recursing into the graph starting at <next>, and
1823 * checking whether we can reach <prev>.)
1825 * We are using global variables to control the recursion, to
1826 * keep the stackframe size of the recursive functions low:
1828 this.class = hlock_class(next);
1830 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1832 return print_circular_bug(&this, target_entry, next, prev);
1833 else if (unlikely(ret < 0))
1834 return print_bfs_bug(ret);
1836 if (!check_prev_add_irq(curr, prev, next))
1840 * For recursive read-locks we do all the dependency checks,
1841 * but we dont store read-triggered dependencies (only
1842 * write-triggered dependencies). This ensures that only the
1843 * write-side dependencies matter, and that if for example a
1844 * write-lock never takes any other locks, then the reads are
1845 * equivalent to a NOP.
1847 if (next->read == 2 || prev->read == 2)
1850 * Is the <prev> -> <next> dependency already present?
1852 * (this may occur even though this is a new chain: consider
1853 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1854 * chains - the second one will be new, but L1 already has
1855 * L2 added to its dependency list, due to the first chain.)
1857 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1858 if (entry->class == hlock_class(next)) {
1860 entry->distance = 1;
1865 if (!*stack_saved) {
1866 if (!save_trace(&trace))
1872 * Ok, all validations passed, add the new lock
1873 * to the previous lock's dependency list:
1875 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1876 &hlock_class(prev)->locks_after,
1877 next->acquire_ip, distance, &trace);
1882 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1883 &hlock_class(next)->locks_before,
1884 next->acquire_ip, distance, &trace);
1889 * Debugging printouts:
1891 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1892 /* We drop graph lock, so another thread can overwrite trace. */
1895 printk("\n new dependency: ");
1896 print_lock_name(hlock_class(prev));
1897 printk(KERN_CONT " => ");
1898 print_lock_name(hlock_class(next));
1899 printk(KERN_CONT "\n");
1901 return graph_lock();
1907 * Add the dependency to all directly-previous locks that are 'relevant'.
1908 * The ones that are relevant are (in increasing distance from curr):
1909 * all consecutive trylock entries and the final non-trylock entry - or
1910 * the end of this context's lock-chain - whichever comes first.
1913 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1915 int depth = curr->lockdep_depth;
1916 int stack_saved = 0;
1917 struct held_lock *hlock;
1922 * Depth must not be zero for a non-head lock:
1927 * At least two relevant locks must exist for this
1930 if (curr->held_locks[depth].irq_context !=
1931 curr->held_locks[depth-1].irq_context)
1935 int distance = curr->lockdep_depth - depth + 1;
1936 hlock = curr->held_locks + depth - 1;
1938 * Only non-recursive-read entries get new dependencies
1941 if (hlock->read != 2 && hlock->check) {
1942 if (!check_prev_add(curr, hlock, next,
1943 distance, &stack_saved))
1946 * Stop after the first non-trylock entry,
1947 * as non-trylock entries have added their
1948 * own direct dependencies already, so this
1949 * lock is connected to them indirectly:
1951 if (!hlock->trylock)
1956 * End of lock-stack?
1961 * Stop the search if we cross into another context:
1963 if (curr->held_locks[depth].irq_context !=
1964 curr->held_locks[depth-1].irq_context)
1969 if (!debug_locks_off_graph_unlock())
1973 * Clearly we all shouldn't be here, but since we made it we
1974 * can reliable say we messed up our state. See the above two
1975 * gotos for reasons why we could possibly end up here.
1982 unsigned long nr_lock_chains;
1983 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1984 int nr_chain_hlocks;
1985 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1987 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1989 return lock_classes + chain_hlocks[chain->base + i];
1993 * Returns the index of the first held_lock of the current chain
1995 static inline int get_first_held_lock(struct task_struct *curr,
1996 struct held_lock *hlock)
1999 struct held_lock *hlock_curr;
2001 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2002 hlock_curr = curr->held_locks + i;
2003 if (hlock_curr->irq_context != hlock->irq_context)
2011 #ifdef CONFIG_DEBUG_LOCKDEP
2013 * Returns the next chain_key iteration
2015 static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2017 u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2019 printk(" class_idx:%d -> chain_key:%016Lx",
2021 (unsigned long long)new_chain_key);
2022 return new_chain_key;
2026 print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2028 struct held_lock *hlock;
2030 int depth = curr->lockdep_depth;
2033 printk("depth: %u\n", depth + 1);
2034 for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
2035 hlock = curr->held_locks + i;
2036 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2041 print_chain_key_iteration(hlock_next->class_idx, chain_key);
2042 print_lock(hlock_next);
2045 static void print_chain_keys_chain(struct lock_chain *chain)
2051 printk("depth: %u\n", chain->depth);
2052 for (i = 0; i < chain->depth; i++) {
2053 class_id = chain_hlocks[chain->base + i];
2054 chain_key = print_chain_key_iteration(class_id + 1, chain_key);
2056 print_lock_name(lock_classes + class_id);
2061 static void print_collision(struct task_struct *curr,
2062 struct held_lock *hlock_next,
2063 struct lock_chain *chain)
2066 printk("======================\n");
2067 printk("[chain_key collision ]\n");
2068 print_kernel_ident();
2069 printk("----------------------\n");
2070 printk("%s/%d: ", current->comm, task_pid_nr(current));
2071 printk("Hash chain already cached but the contents don't match!\n");
2073 printk("Held locks:");
2074 print_chain_keys_held_locks(curr, hlock_next);
2076 printk("Locks in cached chain:");
2077 print_chain_keys_chain(chain);
2079 printk("\nstack backtrace:\n");
2085 * Checks whether the chain and the current held locks are consistent
2086 * in depth and also in content. If they are not it most likely means
2087 * that there was a collision during the calculation of the chain_key.
2088 * Returns: 0 not passed, 1 passed
2090 static int check_no_collision(struct task_struct *curr,
2091 struct held_lock *hlock,
2092 struct lock_chain *chain)
2094 #ifdef CONFIG_DEBUG_LOCKDEP
2097 i = get_first_held_lock(curr, hlock);
2099 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2100 print_collision(curr, hlock, chain);
2104 for (j = 0; j < chain->depth - 1; j++, i++) {
2105 id = curr->held_locks[i].class_idx - 1;
2107 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2108 print_collision(curr, hlock, chain);
2117 * Look up a dependency chain. If the key is not present yet then
2118 * add it and return 1 - in this case the new dependency chain is
2119 * validated. If the key is already hashed, return 0.
2120 * (On return with 1 graph_lock is held.)
2122 static inline int lookup_chain_cache(struct task_struct *curr,
2123 struct held_lock *hlock,
2126 struct lock_class *class = hlock_class(hlock);
2127 struct hlist_head *hash_head = chainhashentry(chain_key);
2128 struct lock_chain *chain;
2132 * We might need to take the graph lock, ensure we've got IRQs
2133 * disabled to make this an IRQ-safe lock.. for recursion reasons
2134 * lockdep won't complain about its own locking errors.
2136 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2139 * We can walk it lock-free, because entries only get added
2142 hlist_for_each_entry_rcu(chain, hash_head, entry) {
2143 if (chain->chain_key == chain_key) {
2145 debug_atomic_inc(chain_lookup_hits);
2146 if (!check_no_collision(curr, hlock, chain))
2149 if (very_verbose(class))
2150 printk("\nhash chain already cached, key: "
2151 "%016Lx tail class: [%p] %s\n",
2152 (unsigned long long)chain_key,
2153 class->key, class->name);
2157 if (very_verbose(class))
2158 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2159 (unsigned long long)chain_key, class->key, class->name);
2161 * Allocate a new chain entry from the static array, and add
2167 * We have to walk the chain again locked - to avoid duplicates:
2169 hlist_for_each_entry(chain, hash_head, entry) {
2170 if (chain->chain_key == chain_key) {
2175 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2176 if (!debug_locks_off_graph_unlock())
2179 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2183 chain = lock_chains + nr_lock_chains++;
2184 chain->chain_key = chain_key;
2185 chain->irq_context = hlock->irq_context;
2186 i = get_first_held_lock(curr, hlock);
2187 chain->depth = curr->lockdep_depth + 1 - i;
2189 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2190 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
2191 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2193 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2194 chain->base = nr_chain_hlocks;
2195 for (j = 0; j < chain->depth - 1; j++, i++) {
2196 int lock_id = curr->held_locks[i].class_idx - 1;
2197 chain_hlocks[chain->base + j] = lock_id;
2199 chain_hlocks[chain->base + j] = class - lock_classes;
2202 if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
2203 nr_chain_hlocks += chain->depth;
2205 #ifdef CONFIG_DEBUG_LOCKDEP
2207 * Important for check_no_collision().
2209 if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
2210 if (debug_locks_off_graph_unlock())
2213 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2219 hlist_add_head_rcu(&chain->entry, hash_head);
2220 debug_atomic_inc(chain_lookup_misses);
2226 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2227 struct held_lock *hlock, int chain_head, u64 chain_key)
2230 * Trylock needs to maintain the stack of held locks, but it
2231 * does not add new dependencies, because trylock can be done
2234 * We look up the chain_key and do the O(N^2) check and update of
2235 * the dependencies only if this is a new dependency chain.
2236 * (If lookup_chain_cache() returns with 1 it acquires
2237 * graph_lock for us)
2239 if (!hlock->trylock && hlock->check &&
2240 lookup_chain_cache(curr, hlock, chain_key)) {
2242 * Check whether last held lock:
2244 * - is irq-safe, if this lock is irq-unsafe
2245 * - is softirq-safe, if this lock is hardirq-unsafe
2247 * And check whether the new lock's dependency graph
2248 * could lead back to the previous lock.
2250 * any of these scenarios could lead to a deadlock. If
2253 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2258 * Mark recursive read, as we jump over it when
2259 * building dependencies (just like we jump over
2265 * Add dependency only if this lock is not the head
2266 * of the chain, and if it's not a secondary read-lock:
2268 if (!chain_head && ret != 2)
2269 if (!check_prevs_add(curr, hlock))
2273 /* after lookup_chain_cache(): */
2274 if (unlikely(!debug_locks))
2280 static inline int validate_chain(struct task_struct *curr,
2281 struct lockdep_map *lock, struct held_lock *hlock,
2282 int chain_head, u64 chain_key)
2289 * We are building curr_chain_key incrementally, so double-check
2290 * it from scratch, to make sure that it's done correctly:
2292 static void check_chain_key(struct task_struct *curr)
2294 #ifdef CONFIG_DEBUG_LOCKDEP
2295 struct held_lock *hlock, *prev_hlock = NULL;
2299 for (i = 0; i < curr->lockdep_depth; i++) {
2300 hlock = curr->held_locks + i;
2301 if (chain_key != hlock->prev_chain_key) {
2304 * We got mighty confused, our chain keys don't match
2305 * with what we expect, someone trample on our task state?
2307 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2308 curr->lockdep_depth, i,
2309 (unsigned long long)chain_key,
2310 (unsigned long long)hlock->prev_chain_key);
2314 * Whoops ran out of static storage again?
2316 if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
2319 if (prev_hlock && (prev_hlock->irq_context !=
2320 hlock->irq_context))
2322 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
2325 if (chain_key != curr->curr_chain_key) {
2328 * More smoking hash instead of calculating it, damn see these
2329 * numbers float.. I bet that a pink elephant stepped on my memory.
2331 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2332 curr->lockdep_depth, i,
2333 (unsigned long long)chain_key,
2334 (unsigned long long)curr->curr_chain_key);
2340 print_usage_bug_scenario(struct held_lock *lock)
2342 struct lock_class *class = hlock_class(lock);
2344 printk(" Possible unsafe locking scenario:\n\n");
2348 __print_lock_name(class);
2349 printk(KERN_CONT ");\n");
2350 printk(" <Interrupt>\n");
2352 __print_lock_name(class);
2353 printk(KERN_CONT ");\n");
2354 printk("\n *** DEADLOCK ***\n\n");
2358 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2359 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2361 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2365 printk("=================================\n");
2366 printk("[ INFO: inconsistent lock state ]\n");
2367 print_kernel_ident();
2368 printk("---------------------------------\n");
2370 printk("inconsistent {%s} -> {%s} usage.\n",
2371 usage_str[prev_bit], usage_str[new_bit]);
2373 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2374 curr->comm, task_pid_nr(curr),
2375 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2376 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2377 trace_hardirqs_enabled(curr),
2378 trace_softirqs_enabled(curr));
2381 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2382 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2384 print_irqtrace_events(curr);
2385 printk("\nother info that might help us debug this:\n");
2386 print_usage_bug_scenario(this);
2388 lockdep_print_held_locks(curr);
2390 printk("\nstack backtrace:\n");
2397 * Print out an error if an invalid bit is set:
2400 valid_state(struct task_struct *curr, struct held_lock *this,
2401 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2403 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2404 return print_usage_bug(curr, this, bad_bit, new_bit);
2408 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2409 enum lock_usage_bit new_bit);
2411 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2414 * print irq inversion bug:
2417 print_irq_inversion_bug(struct task_struct *curr,
2418 struct lock_list *root, struct lock_list *other,
2419 struct held_lock *this, int forwards,
2420 const char *irqclass)
2422 struct lock_list *entry = other;
2423 struct lock_list *middle = NULL;
2426 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2430 printk("=========================================================\n");
2431 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2432 print_kernel_ident();
2433 printk("---------------------------------------------------------\n");
2434 printk("%s/%d just changed the state of lock:\n",
2435 curr->comm, task_pid_nr(curr));
2438 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2440 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2441 print_lock_name(other->class);
2442 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2444 printk("\nother info that might help us debug this:\n");
2446 /* Find a middle lock (if one exists) */
2447 depth = get_lock_depth(other);
2449 if (depth == 0 && (entry != root)) {
2450 printk("lockdep:%s bad path found in chain graph\n", __func__);
2454 entry = get_lock_parent(entry);
2456 } while (entry && entry != root && (depth >= 0));
2458 print_irq_lock_scenario(root, other,
2459 middle ? middle->class : root->class, other->class);
2461 print_irq_lock_scenario(other, root,
2462 middle ? middle->class : other->class, root->class);
2464 lockdep_print_held_locks(curr);
2466 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2467 if (!save_trace(&root->trace))
2469 print_shortest_lock_dependencies(other, root);
2471 printk("\nstack backtrace:\n");
2478 * Prove that in the forwards-direction subgraph starting at <this>
2479 * there is no lock matching <mask>:
2482 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2483 enum lock_usage_bit bit, const char *irqclass)
2486 struct lock_list root;
2487 struct lock_list *uninitialized_var(target_entry);
2490 root.class = hlock_class(this);
2491 ret = find_usage_forwards(&root, bit, &target_entry);
2493 return print_bfs_bug(ret);
2497 return print_irq_inversion_bug(curr, &root, target_entry,
2502 * Prove that in the backwards-direction subgraph starting at <this>
2503 * there is no lock matching <mask>:
2506 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2507 enum lock_usage_bit bit, const char *irqclass)
2510 struct lock_list root;
2511 struct lock_list *uninitialized_var(target_entry);
2514 root.class = hlock_class(this);
2515 ret = find_usage_backwards(&root, bit, &target_entry);
2517 return print_bfs_bug(ret);
2521 return print_irq_inversion_bug(curr, &root, target_entry,
2525 void print_irqtrace_events(struct task_struct *curr)
2527 printk("irq event stamp: %u\n", curr->irq_events);
2528 printk("hardirqs last enabled at (%u): [<%p>] %pS\n",
2529 curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
2530 (void *)curr->hardirq_enable_ip);
2531 printk("hardirqs last disabled at (%u): [<%p>] %pS\n",
2532 curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
2533 (void *)curr->hardirq_disable_ip);
2534 printk("softirqs last enabled at (%u): [<%p>] %pS\n",
2535 curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
2536 (void *)curr->softirq_enable_ip);
2537 printk("softirqs last disabled at (%u): [<%p>] %pS\n",
2538 curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
2539 (void *)curr->softirq_disable_ip);
2542 static int HARDIRQ_verbose(struct lock_class *class)
2545 return class_filter(class);
2550 static int SOFTIRQ_verbose(struct lock_class *class)
2553 return class_filter(class);
2558 static int RECLAIM_FS_verbose(struct lock_class *class)
2561 return class_filter(class);
2566 #define STRICT_READ_CHECKS 1
2568 static int (*state_verbose_f[])(struct lock_class *class) = {
2569 #define LOCKDEP_STATE(__STATE) \
2571 #include "lockdep_states.h"
2572 #undef LOCKDEP_STATE
2575 static inline int state_verbose(enum lock_usage_bit bit,
2576 struct lock_class *class)
2578 return state_verbose_f[bit >> 2](class);
2581 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2582 enum lock_usage_bit bit, const char *name);
2585 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2586 enum lock_usage_bit new_bit)
2588 int excl_bit = exclusive_bit(new_bit);
2589 int read = new_bit & 1;
2590 int dir = new_bit & 2;
2593 * mark USED_IN has to look forwards -- to ensure no dependency
2594 * has ENABLED state, which would allow recursion deadlocks.
2596 * mark ENABLED has to look backwards -- to ensure no dependee
2597 * has USED_IN state, which, again, would allow recursion deadlocks.
2599 check_usage_f usage = dir ?
2600 check_usage_backwards : check_usage_forwards;
2603 * Validate that this particular lock does not have conflicting
2606 if (!valid_state(curr, this, new_bit, excl_bit))
2610 * Validate that the lock dependencies don't have conflicting usage
2613 if ((!read || !dir || STRICT_READ_CHECKS) &&
2614 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2618 * Check for read in write conflicts
2621 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2624 if (STRICT_READ_CHECKS &&
2625 !usage(curr, this, excl_bit + 1,
2626 state_name(new_bit + 1)))
2630 if (state_verbose(new_bit, hlock_class(this)))
2637 #define LOCKDEP_STATE(__STATE) __STATE,
2638 #include "lockdep_states.h"
2639 #undef LOCKDEP_STATE
2643 * Mark all held locks with a usage bit:
2646 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2648 enum lock_usage_bit usage_bit;
2649 struct held_lock *hlock;
2652 for (i = 0; i < curr->lockdep_depth; i++) {
2653 hlock = curr->held_locks + i;
2655 usage_bit = 2 + (mark << 2); /* ENABLED */
2657 usage_bit += 1; /* READ */
2659 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2664 if (!mark_lock(curr, hlock, usage_bit))
2672 * Hardirqs will be enabled:
2674 static void __trace_hardirqs_on_caller(unsigned long ip)
2676 struct task_struct *curr = current;
2678 /* we'll do an OFF -> ON transition: */
2679 curr->hardirqs_enabled = 1;
2682 * We are going to turn hardirqs on, so set the
2683 * usage bit for all held locks:
2685 if (!mark_held_locks(curr, HARDIRQ))
2688 * If we have softirqs enabled, then set the usage
2689 * bit for all held locks. (disabled hardirqs prevented
2690 * this bit from being set before)
2692 if (curr->softirqs_enabled)
2693 if (!mark_held_locks(curr, SOFTIRQ))
2696 curr->hardirq_enable_ip = ip;
2697 curr->hardirq_enable_event = ++curr->irq_events;
2698 debug_atomic_inc(hardirqs_on_events);
2701 __visible void trace_hardirqs_on_caller(unsigned long ip)
2703 time_hardirqs_on(CALLER_ADDR0, ip);
2705 if (unlikely(!debug_locks || current->lockdep_recursion))
2708 if (unlikely(current->hardirqs_enabled)) {
2710 * Neither irq nor preemption are disabled here
2711 * so this is racy by nature but losing one hit
2712 * in a stat is not a big deal.
2714 __debug_atomic_inc(redundant_hardirqs_on);
2719 * We're enabling irqs and according to our state above irqs weren't
2720 * already enabled, yet we find the hardware thinks they are in fact
2721 * enabled.. someone messed up their IRQ state tracing.
2723 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2727 * See the fine text that goes along with this variable definition.
2729 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2733 * Can't allow enabling interrupts while in an interrupt handler,
2734 * that's general bad form and such. Recursion, limited stack etc..
2736 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2739 current->lockdep_recursion = 1;
2740 __trace_hardirqs_on_caller(ip);
2741 current->lockdep_recursion = 0;
2743 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2745 void trace_hardirqs_on(void)
2747 trace_hardirqs_on_caller(CALLER_ADDR0);
2749 EXPORT_SYMBOL(trace_hardirqs_on);
2752 * Hardirqs were disabled:
2754 __visible void trace_hardirqs_off_caller(unsigned long ip)
2756 struct task_struct *curr = current;
2758 time_hardirqs_off(CALLER_ADDR0, ip);
2760 if (unlikely(!debug_locks || current->lockdep_recursion))
2764 * So we're supposed to get called after you mask local IRQs, but for
2765 * some reason the hardware doesn't quite think you did a proper job.
2767 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2770 if (curr->hardirqs_enabled) {
2772 * We have done an ON -> OFF transition:
2774 curr->hardirqs_enabled = 0;
2775 curr->hardirq_disable_ip = ip;
2776 curr->hardirq_disable_event = ++curr->irq_events;
2777 debug_atomic_inc(hardirqs_off_events);
2779 debug_atomic_inc(redundant_hardirqs_off);
2781 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2783 void trace_hardirqs_off(void)
2785 trace_hardirqs_off_caller(CALLER_ADDR0);
2787 EXPORT_SYMBOL(trace_hardirqs_off);
2790 * Softirqs will be enabled:
2792 void trace_softirqs_on(unsigned long ip)
2794 struct task_struct *curr = current;
2796 if (unlikely(!debug_locks || current->lockdep_recursion))
2800 * We fancy IRQs being disabled here, see softirq.c, avoids
2801 * funny state and nesting things.
2803 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2806 if (curr->softirqs_enabled) {
2807 debug_atomic_inc(redundant_softirqs_on);
2811 current->lockdep_recursion = 1;
2813 * We'll do an OFF -> ON transition:
2815 curr->softirqs_enabled = 1;
2816 curr->softirq_enable_ip = ip;
2817 curr->softirq_enable_event = ++curr->irq_events;
2818 debug_atomic_inc(softirqs_on_events);
2820 * We are going to turn softirqs on, so set the
2821 * usage bit for all held locks, if hardirqs are
2824 if (curr->hardirqs_enabled)
2825 mark_held_locks(curr, SOFTIRQ);
2826 current->lockdep_recursion = 0;
2830 * Softirqs were disabled:
2832 void trace_softirqs_off(unsigned long ip)
2834 struct task_struct *curr = current;
2836 if (unlikely(!debug_locks || current->lockdep_recursion))
2840 * We fancy IRQs being disabled here, see softirq.c
2842 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2845 if (curr->softirqs_enabled) {
2847 * We have done an ON -> OFF transition:
2849 curr->softirqs_enabled = 0;
2850 curr->softirq_disable_ip = ip;
2851 curr->softirq_disable_event = ++curr->irq_events;
2852 debug_atomic_inc(softirqs_off_events);
2854 * Whoops, we wanted softirqs off, so why aren't they?
2856 DEBUG_LOCKS_WARN_ON(!softirq_count());
2858 debug_atomic_inc(redundant_softirqs_off);
2861 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2863 struct task_struct *curr = current;
2865 if (unlikely(!debug_locks))
2868 /* no reclaim without waiting on it */
2869 if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
2872 /* this guy won't enter reclaim */
2873 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2876 /* We're only interested __GFP_FS allocations for now */
2877 if (!(gfp_mask & __GFP_FS))
2881 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2883 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2886 mark_held_locks(curr, RECLAIM_FS);
2889 static void check_flags(unsigned long flags);
2891 void lockdep_trace_alloc(gfp_t gfp_mask)
2893 unsigned long flags;
2895 if (unlikely(current->lockdep_recursion))
2898 raw_local_irq_save(flags);
2900 current->lockdep_recursion = 1;
2901 __lockdep_trace_alloc(gfp_mask, flags);
2902 current->lockdep_recursion = 0;
2903 raw_local_irq_restore(flags);
2906 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2909 * If non-trylock use in a hardirq or softirq context, then
2910 * mark the lock as used in these contexts:
2912 if (!hlock->trylock) {
2914 if (curr->hardirq_context)
2915 if (!mark_lock(curr, hlock,
2916 LOCK_USED_IN_HARDIRQ_READ))
2918 if (curr->softirq_context)
2919 if (!mark_lock(curr, hlock,
2920 LOCK_USED_IN_SOFTIRQ_READ))
2923 if (curr->hardirq_context)
2924 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2926 if (curr->softirq_context)
2927 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2931 if (!hlock->hardirqs_off) {
2933 if (!mark_lock(curr, hlock,
2934 LOCK_ENABLED_HARDIRQ_READ))
2936 if (curr->softirqs_enabled)
2937 if (!mark_lock(curr, hlock,
2938 LOCK_ENABLED_SOFTIRQ_READ))
2941 if (!mark_lock(curr, hlock,
2942 LOCK_ENABLED_HARDIRQ))
2944 if (curr->softirqs_enabled)
2945 if (!mark_lock(curr, hlock,
2946 LOCK_ENABLED_SOFTIRQ))
2952 * We reuse the irq context infrastructure more broadly as a general
2953 * context checking code. This tests GFP_FS recursion (a lock taken
2954 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2957 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2959 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2962 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2970 static inline unsigned int task_irq_context(struct task_struct *task)
2972 return 2 * !!task->hardirq_context + !!task->softirq_context;
2975 static int separate_irq_context(struct task_struct *curr,
2976 struct held_lock *hlock)
2978 unsigned int depth = curr->lockdep_depth;
2981 * Keep track of points where we cross into an interrupt context:
2984 struct held_lock *prev_hlock;
2986 prev_hlock = curr->held_locks + depth-1;
2988 * If we cross into another context, reset the
2989 * hash key (this also prevents the checking and the
2990 * adding of the dependency to 'prev'):
2992 if (prev_hlock->irq_context != hlock->irq_context)
2998 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3001 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
3002 enum lock_usage_bit new_bit)
3004 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
3008 static inline int mark_irqflags(struct task_struct *curr,
3009 struct held_lock *hlock)
3014 static inline unsigned int task_irq_context(struct task_struct *task)
3019 static inline int separate_irq_context(struct task_struct *curr,
3020 struct held_lock *hlock)
3025 void lockdep_trace_alloc(gfp_t gfp_mask)
3029 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3032 * Mark a lock with a usage bit, and validate the state transition:
3034 static int mark_lock(struct task_struct *curr, struct held_lock *this,
3035 enum lock_usage_bit new_bit)
3037 unsigned int new_mask = 1 << new_bit, ret = 1;
3040 * If already set then do not dirty the cacheline,
3041 * nor do any checks:
3043 if (likely(hlock_class(this)->usage_mask & new_mask))
3049 * Make sure we didn't race:
3051 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3056 hlock_class(this)->usage_mask |= new_mask;
3058 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
3062 #define LOCKDEP_STATE(__STATE) \
3063 case LOCK_USED_IN_##__STATE: \
3064 case LOCK_USED_IN_##__STATE##_READ: \
3065 case LOCK_ENABLED_##__STATE: \
3066 case LOCK_ENABLED_##__STATE##_READ:
3067 #include "lockdep_states.h"
3068 #undef LOCKDEP_STATE
3069 ret = mark_lock_irq(curr, this, new_bit);
3074 debug_atomic_dec(nr_unused_locks);
3077 if (!debug_locks_off_graph_unlock())
3086 * We must printk outside of the graph_lock:
3089 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3091 print_irqtrace_events(curr);
3099 * Initialize a lock instance's lock-class mapping info:
3101 void lockdep_init_map(struct lockdep_map *lock, const char *name,
3102 struct lock_class_key *key, int subclass)
3106 kmemcheck_mark_initialized(lock, sizeof(*lock));
3108 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3109 lock->class_cache[i] = NULL;
3111 #ifdef CONFIG_LOCK_STAT
3112 lock->cpu = raw_smp_processor_id();
3116 * Can't be having no nameless bastards around this place!
3118 if (DEBUG_LOCKS_WARN_ON(!name)) {
3119 lock->name = "NULL";
3126 * No key, no joy, we need to hash something.
3128 if (DEBUG_LOCKS_WARN_ON(!key))
3131 * Sanity check, the lock-class key must be persistent:
3133 if (!static_obj(key)) {
3134 printk("BUG: key %p not in .data!\n", key);
3136 * What it says above ^^^^^, I suggest you read it.
3138 DEBUG_LOCKS_WARN_ON(1);
3143 if (unlikely(!debug_locks))
3147 unsigned long flags;
3149 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3152 raw_local_irq_save(flags);
3153 current->lockdep_recursion = 1;
3154 register_lock_class(lock, subclass, 1);
3155 current->lockdep_recursion = 0;
3156 raw_local_irq_restore(flags);
3159 EXPORT_SYMBOL_GPL(lockdep_init_map);
3161 struct lock_class_key __lockdep_no_validate__;
3162 EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3165 print_lock_nested_lock_not_held(struct task_struct *curr,
3166 struct held_lock *hlock,
3169 if (!debug_locks_off())
3171 if (debug_locks_silent)
3175 printk("==================================\n");
3176 printk("[ BUG: Nested lock was not taken ]\n");
3177 print_kernel_ident();
3178 printk("----------------------------------\n");
3180 printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3183 printk("\nbut this task is not holding:\n");
3184 printk("%s\n", hlock->nest_lock->name);
3186 printk("\nstack backtrace:\n");
3189 printk("\nother info that might help us debug this:\n");
3190 lockdep_print_held_locks(curr);
3192 printk("\nstack backtrace:\n");
3198 static int __lock_is_held(struct lockdep_map *lock);
3201 * This gets called for every mutex_lock*()/spin_lock*() operation.
3202 * We maintain the dependency maps and validate the locking attempt:
3204 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3205 int trylock, int read, int check, int hardirqs_off,
3206 struct lockdep_map *nest_lock, unsigned long ip,
3207 int references, int pin_count)
3209 struct task_struct *curr = current;
3210 struct lock_class *class = NULL;
3211 struct held_lock *hlock;
3217 if (unlikely(!debug_locks))
3221 * Lockdep should run with IRQs disabled, otherwise we could
3222 * get an interrupt which would want to take locks, which would
3223 * end up in lockdep and have you got a head-ache already?
3225 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3228 if (!prove_locking || lock->key == &__lockdep_no_validate__)
3231 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3232 class = lock->class_cache[subclass];
3236 if (unlikely(!class)) {
3237 class = register_lock_class(lock, subclass, 0);
3241 atomic_inc((atomic_t *)&class->ops);
3242 if (very_verbose(class)) {
3243 printk("\nacquire class [%p] %s", class->key, class->name);
3244 if (class->name_version > 1)
3245 printk(KERN_CONT "#%d", class->name_version);
3246 printk(KERN_CONT "\n");
3251 * Add the lock to the list of currently held locks.
3252 * (we dont increase the depth just yet, up until the
3253 * dependency checks are done)
3255 depth = curr->lockdep_depth;
3257 * Ran out of static storage for our per-task lock stack again have we?
3259 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3262 class_idx = class - lock_classes + 1;
3265 hlock = curr->held_locks + depth - 1;
3266 if (hlock->class_idx == class_idx && nest_lock) {
3270 if (!hlock->references)
3271 hlock->references++;
3273 hlock->references += references;
3276 if (DEBUG_LOCKS_WARN_ON(hlock->references < references))
3283 hlock = curr->held_locks + depth;
3285 * Plain impossible, we just registered it and checked it weren't no
3286 * NULL like.. I bet this mushroom I ate was good!
3288 if (DEBUG_LOCKS_WARN_ON(!class))
3290 hlock->class_idx = class_idx;
3291 hlock->acquire_ip = ip;
3292 hlock->instance = lock;
3293 hlock->nest_lock = nest_lock;
3294 hlock->irq_context = task_irq_context(curr);
3295 hlock->trylock = trylock;
3297 hlock->check = check;
3298 hlock->hardirqs_off = !!hardirqs_off;
3299 hlock->references = references;
3300 #ifdef CONFIG_LOCK_STAT
3301 hlock->waittime_stamp = 0;
3302 hlock->holdtime_stamp = lockstat_clock();
3304 hlock->pin_count = pin_count;
3306 if (check && !mark_irqflags(curr, hlock))
3309 /* mark it as used: */
3310 if (!mark_lock(curr, hlock, LOCK_USED))
3314 * Calculate the chain hash: it's the combined hash of all the
3315 * lock keys along the dependency chain. We save the hash value
3316 * at every step so that we can get the current hash easily
3317 * after unlock. The chain hash is then used to cache dependency
3320 * The 'key ID' is what is the most compact key value to drive
3321 * the hash, not class->key.
3324 * Whoops, we did it again.. ran straight out of our static allocation.
3326 if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
3329 chain_key = curr->curr_chain_key;
3332 * How can we have a chain hash when we ain't got no keys?!
3334 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3339 hlock->prev_chain_key = chain_key;
3340 if (separate_irq_context(curr, hlock)) {
3344 chain_key = iterate_chain_key(chain_key, class_idx);
3346 if (nest_lock && !__lock_is_held(nest_lock))
3347 return print_lock_nested_lock_not_held(curr, hlock, ip);
3349 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3352 curr->curr_chain_key = chain_key;
3353 curr->lockdep_depth++;
3354 check_chain_key(curr);
3355 #ifdef CONFIG_DEBUG_LOCKDEP
3356 if (unlikely(!debug_locks))
3359 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3361 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3362 printk(KERN_DEBUG "depth: %i max: %lu!\n",
3363 curr->lockdep_depth, MAX_LOCK_DEPTH);
3365 lockdep_print_held_locks(current);
3366 debug_show_all_locks();
3372 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3373 max_lockdep_depth = curr->lockdep_depth;
3379 print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3382 if (!debug_locks_off())
3384 if (debug_locks_silent)
3388 printk("=====================================\n");
3389 printk("[ BUG: bad unlock balance detected! ]\n");
3390 print_kernel_ident();
3391 printk("-------------------------------------\n");
3392 printk("%s/%d is trying to release lock (",
3393 curr->comm, task_pid_nr(curr));
3394 print_lockdep_cache(lock);
3395 printk(KERN_CONT ") at:\n");
3397 printk("but there are no more locks to release!\n");
3398 printk("\nother info that might help us debug this:\n");
3399 lockdep_print_held_locks(curr);
3401 printk("\nstack backtrace:\n");
3407 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3409 if (hlock->instance == lock)
3412 if (hlock->references) {
3413 struct lock_class *class = lock->class_cache[0];
3416 class = look_up_lock_class(lock, 0);
3419 * If look_up_lock_class() failed to find a class, we're trying
3420 * to test if we hold a lock that has never yet been acquired.
3421 * Clearly if the lock hasn't been acquired _ever_, we're not
3422 * holding it either, so report failure.
3428 * References, but not a lock we're actually ref-counting?
3429 * State got messed up, follow the sites that change ->references
3430 * and try to make sense of it.
3432 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3435 if (hlock->class_idx == class - lock_classes + 1)
3443 __lock_set_class(struct lockdep_map *lock, const char *name,
3444 struct lock_class_key *key, unsigned int subclass,
3447 struct task_struct *curr = current;
3448 struct held_lock *hlock, *prev_hlock;
3449 struct lock_class *class;
3453 if (unlikely(!debug_locks))
3456 depth = curr->lockdep_depth;
3458 * This function is about (re)setting the class of a held lock,
3459 * yet we're not actually holding any locks. Naughty user!
3461 if (DEBUG_LOCKS_WARN_ON(!depth))
3465 for (i = depth-1; i >= 0; i--) {
3466 hlock = curr->held_locks + i;
3468 * We must not cross into another context:
3470 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3472 if (match_held_lock(hlock, lock))
3476 return print_unlock_imbalance_bug(curr, lock, ip);
3479 lockdep_init_map(lock, name, key, 0);
3480 class = register_lock_class(lock, subclass, 0);
3481 hlock->class_idx = class - lock_classes + 1;
3483 curr->lockdep_depth = i;
3484 curr->curr_chain_key = hlock->prev_chain_key;
3486 for (; i < depth; i++) {
3487 hlock = curr->held_locks + i;
3488 if (!__lock_acquire(hlock->instance,
3489 hlock_class(hlock)->subclass, hlock->trylock,
3490 hlock->read, hlock->check, hlock->hardirqs_off,
3491 hlock->nest_lock, hlock->acquire_ip,
3492 hlock->references, hlock->pin_count))
3497 * I took it apart and put it back together again, except now I have
3498 * these 'spare' parts.. where shall I put them.
3500 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3506 * Remove the lock to the list of currently held locks - this gets
3507 * called on mutex_unlock()/spin_unlock*() (or on a failed
3508 * mutex_lock_interruptible()).
3510 * @nested is an hysterical artifact, needs a tree wide cleanup.
3513 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3515 struct task_struct *curr = current;
3516 struct held_lock *hlock, *prev_hlock;
3520 if (unlikely(!debug_locks))
3523 depth = curr->lockdep_depth;
3525 * So we're all set to release this lock.. wait what lock? We don't
3526 * own any locks, you've been drinking again?
3528 if (DEBUG_LOCKS_WARN_ON(depth <= 0))
3529 return print_unlock_imbalance_bug(curr, lock, ip);
3532 * Check whether the lock exists in the current stack
3536 for (i = depth-1; i >= 0; i--) {
3537 hlock = curr->held_locks + i;
3539 * We must not cross into another context:
3541 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3543 if (match_held_lock(hlock, lock))
3547 return print_unlock_imbalance_bug(curr, lock, ip);
3550 if (hlock->instance == lock)
3551 lock_release_holdtime(hlock);
3553 WARN(hlock->pin_count, "releasing a pinned lock\n");
3555 if (hlock->references) {
3556 hlock->references--;
3557 if (hlock->references) {
3559 * We had, and after removing one, still have
3560 * references, the current lock stack is still
3561 * valid. We're done!
3568 * We have the right lock to unlock, 'hlock' points to it.
3569 * Now we remove it from the stack, and add back the other
3570 * entries (if any), recalculating the hash along the way:
3573 curr->lockdep_depth = i;
3574 curr->curr_chain_key = hlock->prev_chain_key;
3576 for (i++; i < depth; i++) {
3577 hlock = curr->held_locks + i;
3578 if (!__lock_acquire(hlock->instance,
3579 hlock_class(hlock)->subclass, hlock->trylock,
3580 hlock->read, hlock->check, hlock->hardirqs_off,
3581 hlock->nest_lock, hlock->acquire_ip,
3582 hlock->references, hlock->pin_count))
3587 * We had N bottles of beer on the wall, we drank one, but now
3588 * there's not N-1 bottles of beer left on the wall...
3590 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3596 static int __lock_is_held(struct lockdep_map *lock)
3598 struct task_struct *curr = current;
3601 for (i = 0; i < curr->lockdep_depth; i++) {
3602 struct held_lock *hlock = curr->held_locks + i;
3604 if (match_held_lock(hlock, lock))
3611 static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
3613 struct pin_cookie cookie = NIL_COOKIE;
3614 struct task_struct *curr = current;
3617 if (unlikely(!debug_locks))
3620 for (i = 0; i < curr->lockdep_depth; i++) {
3621 struct held_lock *hlock = curr->held_locks + i;
3623 if (match_held_lock(hlock, lock)) {
3625 * Grab 16bits of randomness; this is sufficient to not
3626 * be guessable and still allows some pin nesting in
3627 * our u32 pin_count.
3629 cookie.val = 1 + (prandom_u32() >> 16);
3630 hlock->pin_count += cookie.val;
3635 WARN(1, "pinning an unheld lock\n");
3639 static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3641 struct task_struct *curr = current;
3644 if (unlikely(!debug_locks))
3647 for (i = 0; i < curr->lockdep_depth; i++) {
3648 struct held_lock *hlock = curr->held_locks + i;
3650 if (match_held_lock(hlock, lock)) {
3651 hlock->pin_count += cookie.val;
3656 WARN(1, "pinning an unheld lock\n");
3659 static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3661 struct task_struct *curr = current;
3664 if (unlikely(!debug_locks))
3667 for (i = 0; i < curr->lockdep_depth; i++) {
3668 struct held_lock *hlock = curr->held_locks + i;
3670 if (match_held_lock(hlock, lock)) {
3671 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
3674 hlock->pin_count -= cookie.val;
3676 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
3677 hlock->pin_count = 0;
3683 WARN(1, "unpinning an unheld lock\n");
3687 * Check whether we follow the irq-flags state precisely:
3689 static void check_flags(unsigned long flags)
3691 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3692 defined(CONFIG_TRACE_IRQFLAGS)
3696 if (irqs_disabled_flags(flags)) {
3697 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3698 printk("possible reason: unannotated irqs-off.\n");
3701 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3702 printk("possible reason: unannotated irqs-on.\n");
3707 * We dont accurately track softirq state in e.g.
3708 * hardirq contexts (such as on 4KSTACKS), so only
3709 * check if not in hardirq contexts:
3711 if (!hardirq_count()) {
3712 if (softirq_count()) {
3713 /* like the above, but with softirqs */
3714 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3716 /* lick the above, does it taste good? */
3717 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3722 print_irqtrace_events(current);
3726 void lock_set_class(struct lockdep_map *lock, const char *name,
3727 struct lock_class_key *key, unsigned int subclass,
3730 unsigned long flags;
3732 if (unlikely(current->lockdep_recursion))
3735 raw_local_irq_save(flags);
3736 current->lockdep_recursion = 1;
3738 if (__lock_set_class(lock, name, key, subclass, ip))
3739 check_chain_key(current);
3740 current->lockdep_recursion = 0;
3741 raw_local_irq_restore(flags);
3743 EXPORT_SYMBOL_GPL(lock_set_class);
3746 * We are not always called with irqs disabled - do that here,
3747 * and also avoid lockdep recursion:
3749 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3750 int trylock, int read, int check,
3751 struct lockdep_map *nest_lock, unsigned long ip)
3753 unsigned long flags;
3755 if (unlikely(current->lockdep_recursion))
3758 raw_local_irq_save(flags);
3761 current->lockdep_recursion = 1;
3762 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3763 __lock_acquire(lock, subclass, trylock, read, check,
3764 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
3765 current->lockdep_recursion = 0;
3766 raw_local_irq_restore(flags);
3768 EXPORT_SYMBOL_GPL(lock_acquire);
3770 void lock_release(struct lockdep_map *lock, int nested,
3773 unsigned long flags;
3775 if (unlikely(current->lockdep_recursion))
3778 raw_local_irq_save(flags);
3780 current->lockdep_recursion = 1;
3781 trace_lock_release(lock, ip);
3782 if (__lock_release(lock, nested, ip))
3783 check_chain_key(current);
3784 current->lockdep_recursion = 0;
3785 raw_local_irq_restore(flags);
3787 EXPORT_SYMBOL_GPL(lock_release);
3789 int lock_is_held(struct lockdep_map *lock)
3791 unsigned long flags;
3794 if (unlikely(current->lockdep_recursion))
3795 return 1; /* avoid false negative lockdep_assert_held() */
3797 raw_local_irq_save(flags);
3800 current->lockdep_recursion = 1;
3801 ret = __lock_is_held(lock);
3802 current->lockdep_recursion = 0;
3803 raw_local_irq_restore(flags);
3807 EXPORT_SYMBOL_GPL(lock_is_held);
3809 struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
3811 struct pin_cookie cookie = NIL_COOKIE;
3812 unsigned long flags;
3814 if (unlikely(current->lockdep_recursion))
3817 raw_local_irq_save(flags);
3820 current->lockdep_recursion = 1;
3821 cookie = __lock_pin_lock(lock);
3822 current->lockdep_recursion = 0;
3823 raw_local_irq_restore(flags);
3827 EXPORT_SYMBOL_GPL(lock_pin_lock);
3829 void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3831 unsigned long flags;
3833 if (unlikely(current->lockdep_recursion))
3836 raw_local_irq_save(flags);
3839 current->lockdep_recursion = 1;
3840 __lock_repin_lock(lock, cookie);
3841 current->lockdep_recursion = 0;
3842 raw_local_irq_restore(flags);
3844 EXPORT_SYMBOL_GPL(lock_repin_lock);
3846 void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3848 unsigned long flags;
3850 if (unlikely(current->lockdep_recursion))
3853 raw_local_irq_save(flags);
3856 current->lockdep_recursion = 1;
3857 __lock_unpin_lock(lock, cookie);
3858 current->lockdep_recursion = 0;
3859 raw_local_irq_restore(flags);
3861 EXPORT_SYMBOL_GPL(lock_unpin_lock);
3863 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3865 current->lockdep_reclaim_gfp = gfp_mask;
3868 void lockdep_clear_current_reclaim_state(void)
3870 current->lockdep_reclaim_gfp = 0;
3873 #ifdef CONFIG_LOCK_STAT
3875 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3878 if (!debug_locks_off())
3880 if (debug_locks_silent)
3884 printk("=================================\n");
3885 printk("[ BUG: bad contention detected! ]\n");
3886 print_kernel_ident();
3887 printk("---------------------------------\n");
3888 printk("%s/%d is trying to contend lock (",
3889 curr->comm, task_pid_nr(curr));
3890 print_lockdep_cache(lock);
3891 printk(KERN_CONT ") at:\n");
3893 printk("but there are no locks held!\n");
3894 printk("\nother info that might help us debug this:\n");
3895 lockdep_print_held_locks(curr);
3897 printk("\nstack backtrace:\n");
3904 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3906 struct task_struct *curr = current;
3907 struct held_lock *hlock, *prev_hlock;
3908 struct lock_class_stats *stats;
3910 int i, contention_point, contending_point;
3912 depth = curr->lockdep_depth;
3914 * Whee, we contended on this lock, except it seems we're not
3915 * actually trying to acquire anything much at all..
3917 if (DEBUG_LOCKS_WARN_ON(!depth))
3921 for (i = depth-1; i >= 0; i--) {
3922 hlock = curr->held_locks + i;
3924 * We must not cross into another context:
3926 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3928 if (match_held_lock(hlock, lock))
3932 print_lock_contention_bug(curr, lock, ip);
3936 if (hlock->instance != lock)
3939 hlock->waittime_stamp = lockstat_clock();
3941 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3942 contending_point = lock_point(hlock_class(hlock)->contending_point,
3945 stats = get_lock_stats(hlock_class(hlock));
3946 if (contention_point < LOCKSTAT_POINTS)
3947 stats->contention_point[contention_point]++;
3948 if (contending_point < LOCKSTAT_POINTS)
3949 stats->contending_point[contending_point]++;
3950 if (lock->cpu != smp_processor_id())
3951 stats->bounces[bounce_contended + !!hlock->read]++;
3952 put_lock_stats(stats);
3956 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3958 struct task_struct *curr = current;
3959 struct held_lock *hlock, *prev_hlock;
3960 struct lock_class_stats *stats;
3962 u64 now, waittime = 0;
3965 depth = curr->lockdep_depth;
3967 * Yay, we acquired ownership of this lock we didn't try to
3968 * acquire, how the heck did that happen?
3970 if (DEBUG_LOCKS_WARN_ON(!depth))
3974 for (i = depth-1; i >= 0; i--) {
3975 hlock = curr->held_locks + i;
3977 * We must not cross into another context:
3979 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3981 if (match_held_lock(hlock, lock))
3985 print_lock_contention_bug(curr, lock, _RET_IP_);
3989 if (hlock->instance != lock)
3992 cpu = smp_processor_id();
3993 if (hlock->waittime_stamp) {
3994 now = lockstat_clock();
3995 waittime = now - hlock->waittime_stamp;
3996 hlock->holdtime_stamp = now;
3999 trace_lock_acquired(lock, ip);
4001 stats = get_lock_stats(hlock_class(hlock));
4004 lock_time_inc(&stats->read_waittime, waittime);
4006 lock_time_inc(&stats->write_waittime, waittime);
4008 if (lock->cpu != cpu)
4009 stats->bounces[bounce_acquired + !!hlock->read]++;
4010 put_lock_stats(stats);
4016 void lock_contended(struct lockdep_map *lock, unsigned long ip)
4018 unsigned long flags;
4020 if (unlikely(!lock_stat || !debug_locks))
4023 if (unlikely(current->lockdep_recursion))
4026 raw_local_irq_save(flags);
4028 current->lockdep_recursion = 1;
4029 trace_lock_contended(lock, ip);
4030 __lock_contended(lock, ip);
4031 current->lockdep_recursion = 0;
4032 raw_local_irq_restore(flags);
4034 EXPORT_SYMBOL_GPL(lock_contended);
4036 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
4038 unsigned long flags;
4040 if (unlikely(!lock_stat || !debug_locks))
4043 if (unlikely(current->lockdep_recursion))
4046 raw_local_irq_save(flags);
4048 current->lockdep_recursion = 1;
4049 __lock_acquired(lock, ip);
4050 current->lockdep_recursion = 0;
4051 raw_local_irq_restore(flags);
4053 EXPORT_SYMBOL_GPL(lock_acquired);
4057 * Used by the testsuite, sanitize the validator state
4058 * after a simulated failure:
4061 void lockdep_reset(void)
4063 unsigned long flags;
4066 raw_local_irq_save(flags);
4067 current->curr_chain_key = 0;
4068 current->lockdep_depth = 0;
4069 current->lockdep_recursion = 0;
4070 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
4071 nr_hardirq_chains = 0;
4072 nr_softirq_chains = 0;
4073 nr_process_chains = 0;
4075 for (i = 0; i < CHAINHASH_SIZE; i++)
4076 INIT_HLIST_HEAD(chainhash_table + i);
4077 raw_local_irq_restore(flags);
4080 static void zap_class(struct lock_class *class)
4085 * Remove all dependencies this lock is
4088 for (i = 0; i < nr_list_entries; i++) {
4089 if (list_entries[i].class == class)
4090 list_del_rcu(&list_entries[i].entry);
4093 * Unhash the class and remove it from the all_lock_classes list:
4095 hlist_del_rcu(&class->hash_entry);
4096 list_del_rcu(&class->lock_entry);
4098 RCU_INIT_POINTER(class->key, NULL);
4099 RCU_INIT_POINTER(class->name, NULL);
4102 static inline int within(const void *addr, void *start, unsigned long size)
4104 return addr >= start && addr < start + size;
4108 * Used in module.c to remove lock classes from memory that is going to be
4109 * freed; and possibly re-used by other modules.
4111 * We will have had one sync_sched() before getting here, so we're guaranteed
4112 * nobody will look up these exact classes -- they're properly dead but still
4115 void lockdep_free_key_range(void *start, unsigned long size)
4117 struct lock_class *class;
4118 struct hlist_head *head;
4119 unsigned long flags;
4123 raw_local_irq_save(flags);
4124 locked = graph_lock();
4127 * Unhash all classes that were created by this module:
4129 for (i = 0; i < CLASSHASH_SIZE; i++) {
4130 head = classhash_table + i;
4131 hlist_for_each_entry_rcu(class, head, hash_entry) {
4132 if (within(class->key, start, size))
4134 else if (within(class->name, start, size))
4141 raw_local_irq_restore(flags);
4144 * Wait for any possible iterators from look_up_lock_class() to pass
4145 * before continuing to free the memory they refer to.
4147 * sync_sched() is sufficient because the read-side is IRQ disable.
4149 synchronize_sched();
4152 * XXX at this point we could return the resources to the pool;
4153 * instead we leak them. We would need to change to bitmap allocators
4154 * instead of the linear allocators we have now.
4158 void lockdep_reset_lock(struct lockdep_map *lock)
4160 struct lock_class *class;
4161 struct hlist_head *head;
4162 unsigned long flags;
4166 raw_local_irq_save(flags);
4169 * Remove all classes this lock might have:
4171 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
4173 * If the class exists we look it up and zap it:
4175 class = look_up_lock_class(lock, j);
4180 * Debug check: in the end all mapped classes should
4183 locked = graph_lock();
4184 for (i = 0; i < CLASSHASH_SIZE; i++) {
4185 head = classhash_table + i;
4186 hlist_for_each_entry_rcu(class, head, hash_entry) {
4189 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
4190 match |= class == lock->class_cache[j];
4192 if (unlikely(match)) {
4193 if (debug_locks_off_graph_unlock()) {
4195 * We all just reset everything, how did it match?
4207 raw_local_irq_restore(flags);
4210 void __init lockdep_info(void)
4212 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4214 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
4215 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
4216 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
4217 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
4218 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
4219 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
4220 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
4222 printk(" memory used by lock dependency info: %lu kB\n",
4223 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4224 sizeof(struct list_head) * CLASSHASH_SIZE +
4225 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4226 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4227 sizeof(struct list_head) * CHAINHASH_SIZE
4228 #ifdef CONFIG_PROVE_LOCKING
4229 + sizeof(struct circular_queue)
4234 printk(" per task-struct memory footprint: %lu bytes\n",
4235 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4239 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4240 const void *mem_to, struct held_lock *hlock)
4242 if (!debug_locks_off())
4244 if (debug_locks_silent)
4248 printk("=========================\n");
4249 printk("[ BUG: held lock freed! ]\n");
4250 print_kernel_ident();
4251 printk("-------------------------\n");
4252 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4253 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4255 lockdep_print_held_locks(curr);
4257 printk("\nstack backtrace:\n");
4261 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4262 const void* lock_from, unsigned long lock_len)
4264 return lock_from + lock_len <= mem_from ||
4265 mem_from + mem_len <= lock_from;
4269 * Called when kernel memory is freed (or unmapped), or if a lock
4270 * is destroyed or reinitialized - this code checks whether there is
4271 * any held lock in the memory range of <from> to <to>:
4273 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4275 struct task_struct *curr = current;
4276 struct held_lock *hlock;
4277 unsigned long flags;
4280 if (unlikely(!debug_locks))
4283 raw_local_irq_save(flags);
4284 for (i = 0; i < curr->lockdep_depth; i++) {
4285 hlock = curr->held_locks + i;
4287 if (not_in_range(mem_from, mem_len, hlock->instance,
4288 sizeof(*hlock->instance)))
4291 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4294 raw_local_irq_restore(flags);
4296 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4298 static void print_held_locks_bug(void)
4300 if (!debug_locks_off())
4302 if (debug_locks_silent)
4306 printk("=====================================\n");
4307 printk("[ BUG: %s/%d still has locks held! ]\n",
4308 current->comm, task_pid_nr(current));
4309 print_kernel_ident();
4310 printk("-------------------------------------\n");
4311 lockdep_print_held_locks(current);
4312 printk("\nstack backtrace:\n");
4316 void debug_check_no_locks_held(void)
4318 if (unlikely(current->lockdep_depth > 0))
4319 print_held_locks_bug();
4321 EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
4324 void debug_show_all_locks(void)
4326 struct task_struct *g, *p;
4330 if (unlikely(!debug_locks)) {
4331 printk("INFO: lockdep is turned off.\n");
4334 printk("\nShowing all locks held in the system:\n");
4337 * Here we try to get the tasklist_lock as hard as possible,
4338 * if not successful after 2 seconds we ignore it (but keep
4339 * trying). This is to enable a debug printout even if a
4340 * tasklist_lock-holding task deadlocks or crashes.
4343 if (!read_trylock(&tasklist_lock)) {
4345 printk("hm, tasklist_lock locked, retrying... ");
4348 printk(" #%d", 10-count);
4352 printk(" ignoring it.\n");
4356 printk(KERN_CONT " locked it.\n");
4359 do_each_thread(g, p) {
4361 * It's not reliable to print a task's held locks
4362 * if it's not sleeping (or if it's not the current
4365 if (p->state == TASK_RUNNING && p != current)
4367 if (p->lockdep_depth)
4368 lockdep_print_held_locks(p);
4370 if (read_trylock(&tasklist_lock))
4372 } while_each_thread(g, p);
4375 printk("=============================================\n\n");
4378 read_unlock(&tasklist_lock);
4380 EXPORT_SYMBOL_GPL(debug_show_all_locks);
4384 * Careful: only use this function if you are sure that
4385 * the task cannot run in parallel!
4387 void debug_show_held_locks(struct task_struct *task)
4389 if (unlikely(!debug_locks)) {
4390 printk("INFO: lockdep is turned off.\n");
4393 lockdep_print_held_locks(task);
4395 EXPORT_SYMBOL_GPL(debug_show_held_locks);
4397 asmlinkage __visible void lockdep_sys_exit(void)
4399 struct task_struct *curr = current;
4401 if (unlikely(curr->lockdep_depth)) {
4402 if (!debug_locks_off())
4405 printk("================================================\n");
4406 printk("[ BUG: lock held when returning to user space! ]\n");
4407 print_kernel_ident();
4408 printk("------------------------------------------------\n");
4409 printk("%s/%d is leaving the kernel with locks still held!\n",
4410 curr->comm, curr->pid);
4411 lockdep_print_held_locks(curr);
4415 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4417 struct task_struct *curr = current;
4419 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4420 if (!debug_locks_off())
4422 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4423 /* Note: the following can be executed concurrently, so be careful. */
4425 printk("===============================\n");
4426 printk("[ INFO: suspicious RCU usage. ]\n");
4427 print_kernel_ident();
4428 printk("-------------------------------\n");
4429 printk("%s:%d %s!\n", file, line, s);
4430 printk("\nother info that might help us debug this:\n\n");
4431 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4432 !rcu_lockdep_current_cpu_online()
4433 ? "RCU used illegally from offline CPU!\n"
4434 : !rcu_is_watching()
4435 ? "RCU used illegally from idle CPU!\n"
4437 rcu_scheduler_active, debug_locks);
4440 * If a CPU is in the RCU-free window in idle (ie: in the section
4441 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4442 * considers that CPU to be in an "extended quiescent state",
4443 * which means that RCU will be completely ignoring that CPU.
4444 * Therefore, rcu_read_lock() and friends have absolutely no
4445 * effect on a CPU running in that state. In other words, even if
4446 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4447 * delete data structures out from under it. RCU really has no
4448 * choice here: we need to keep an RCU-free window in idle where
4449 * the CPU may possibly enter into low power mode. This way we can
4450 * notice an extended quiescent state to other CPUs that started a grace
4451 * period. Otherwise we would delay any grace period as long as we run
4454 * So complain bitterly if someone does call rcu_read_lock(),
4455 * rcu_read_lock_bh() and so on from extended quiescent states.
4457 if (!rcu_is_watching())
4458 printk("RCU used illegally from extended quiescent state!\n");
4460 lockdep_print_held_locks(curr);
4461 printk("\nstack backtrace:\n");
4464 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);