4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/sched/clock.h>
32 #include <linux/sched/task.h>
33 #include <linux/sched/mm.h>
34 #include <linux/delay.h>
35 #include <linux/module.h>
36 #include <linux/proc_fs.h>
37 #include <linux/seq_file.h>
38 #include <linux/spinlock.h>
39 #include <linux/kallsyms.h>
40 #include <linux/interrupt.h>
41 #include <linux/stacktrace.h>
42 #include <linux/debug_locks.h>
43 #include <linux/irqflags.h>
44 #include <linux/utsname.h>
45 #include <linux/hash.h>
46 #include <linux/ftrace.h>
47 #include <linux/stringify.h>
48 #include <linux/bitops.h>
49 #include <linux/gfp.h>
50 #include <linux/random.h>
51 #include <linux/jhash.h>
52 #include <linux/nmi.h>
54 #include <asm/sections.h>
56 #include "lockdep_internals.h"
58 #define CREATE_TRACE_POINTS
59 #include <trace/events/lock.h>
61 #ifdef CONFIG_PROVE_LOCKING
62 int prove_locking = 1;
63 module_param(prove_locking, int, 0644);
65 #define prove_locking 0
68 #ifdef CONFIG_LOCK_STAT
70 module_param(lock_stat, int, 0644);
76 * lockdep_lock: protects the lockdep graph, the hashes and the
77 * class/list/hash allocators.
79 * This is one of the rare exceptions where it's justified
80 * to use a raw spinlock - we really dont want the spinlock
81 * code to recurse back into the lockdep code...
83 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
85 static int graph_lock(void)
87 arch_spin_lock(&lockdep_lock);
89 * Make sure that if another CPU detected a bug while
90 * walking the graph we dont change it (while the other
91 * CPU is busy printing out stuff with the graph lock
95 arch_spin_unlock(&lockdep_lock);
98 /* prevent any recursions within lockdep from causing deadlocks */
99 current->lockdep_recursion++;
103 static inline int graph_unlock(void)
105 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
107 * The lockdep graph lock isn't locked while we expect it to
108 * be, we're confused now, bye!
110 return DEBUG_LOCKS_WARN_ON(1);
113 current->lockdep_recursion--;
114 arch_spin_unlock(&lockdep_lock);
119 * Turn lock debugging off and return with 0 if it was off already,
120 * and also release the graph lock:
122 static inline int debug_locks_off_graph_unlock(void)
124 int ret = debug_locks_off();
126 arch_spin_unlock(&lockdep_lock);
131 unsigned long nr_list_entries;
132 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
135 * All data structures here are protected by the global debug_lock.
137 * Mutex key structs only get allocated, once during bootup, and never
138 * get freed - this significantly simplifies the debugging code.
140 unsigned long nr_lock_classes;
141 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
143 static inline struct lock_class *hlock_class(struct held_lock *hlock)
145 if (!hlock->class_idx) {
147 * Someone passed in garbage, we give up.
149 DEBUG_LOCKS_WARN_ON(1);
152 return lock_classes + hlock->class_idx - 1;
155 #ifdef CONFIG_LOCK_STAT
156 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
158 static inline u64 lockstat_clock(void)
160 return local_clock();
163 static int lock_point(unsigned long points[], unsigned long ip)
167 for (i = 0; i < LOCKSTAT_POINTS; i++) {
168 if (points[i] == 0) {
179 static void lock_time_inc(struct lock_time *lt, u64 time)
184 if (time < lt->min || !lt->nr)
191 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
196 if (src->max > dst->max)
199 if (src->min < dst->min || !dst->nr)
202 dst->total += src->total;
206 struct lock_class_stats lock_stats(struct lock_class *class)
208 struct lock_class_stats stats;
211 memset(&stats, 0, sizeof(struct lock_class_stats));
212 for_each_possible_cpu(cpu) {
213 struct lock_class_stats *pcs =
214 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
216 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
217 stats.contention_point[i] += pcs->contention_point[i];
219 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
220 stats.contending_point[i] += pcs->contending_point[i];
222 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
223 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
225 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
226 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
228 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
229 stats.bounces[i] += pcs->bounces[i];
235 void clear_lock_stats(struct lock_class *class)
239 for_each_possible_cpu(cpu) {
240 struct lock_class_stats *cpu_stats =
241 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
243 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
245 memset(class->contention_point, 0, sizeof(class->contention_point));
246 memset(class->contending_point, 0, sizeof(class->contending_point));
249 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
251 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
254 static void put_lock_stats(struct lock_class_stats *stats)
256 put_cpu_var(cpu_lock_stats);
259 static void lock_release_holdtime(struct held_lock *hlock)
261 struct lock_class_stats *stats;
267 holdtime = lockstat_clock() - hlock->holdtime_stamp;
269 stats = get_lock_stats(hlock_class(hlock));
271 lock_time_inc(&stats->read_holdtime, holdtime);
273 lock_time_inc(&stats->write_holdtime, holdtime);
274 put_lock_stats(stats);
277 static inline void lock_release_holdtime(struct held_lock *hlock)
283 * We keep a global list of all lock classes. The list only grows,
284 * never shrinks. The list is only accessed with the lockdep
285 * spinlock lock held.
287 LIST_HEAD(all_lock_classes);
290 * The lockdep classes are in a hash-table as well, for fast lookup:
292 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
293 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
294 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
295 #define classhashentry(key) (classhash_table + __classhashfn((key)))
297 static struct hlist_head classhash_table[CLASSHASH_SIZE];
300 * We put the lock dependency chains into a hash-table as well, to cache
303 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
304 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
305 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
306 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
308 static struct hlist_head chainhash_table[CHAINHASH_SIZE];
311 * The hash key of the lock dependency chains is a hash itself too:
312 * it's a hash of all locks taken up to that lock, including that lock.
313 * It's a 64-bit hash, because it's important for the keys to be
316 static inline u64 iterate_chain_key(u64 key, u32 idx)
318 u32 k0 = key, k1 = key >> 32;
320 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
322 return k0 | (u64)k1 << 32;
325 void lockdep_off(void)
327 current->lockdep_recursion++;
329 EXPORT_SYMBOL(lockdep_off);
331 void lockdep_on(void)
333 current->lockdep_recursion--;
335 EXPORT_SYMBOL(lockdep_on);
338 * Debugging switches:
342 #define VERY_VERBOSE 0
345 # define HARDIRQ_VERBOSE 1
346 # define SOFTIRQ_VERBOSE 1
348 # define HARDIRQ_VERBOSE 0
349 # define SOFTIRQ_VERBOSE 0
352 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
354 * Quick filtering for interesting events:
356 static int class_filter(struct lock_class *class)
360 if (class->name_version == 1 &&
361 !strcmp(class->name, "lockname"))
363 if (class->name_version == 1 &&
364 !strcmp(class->name, "&struct->lockfield"))
367 /* Filter everything else. 1 would be to allow everything else */
372 static int verbose(struct lock_class *class)
375 return class_filter(class);
381 * Stack-trace: tightly packed array of stack backtrace
382 * addresses. Protected by the graph_lock.
384 unsigned long nr_stack_trace_entries;
385 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
387 static void print_lockdep_off(const char *bug_msg)
389 printk(KERN_DEBUG "%s\n", bug_msg);
390 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
391 #ifdef CONFIG_LOCK_STAT
392 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
396 static int save_trace(struct stack_trace *trace)
398 trace->nr_entries = 0;
399 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
400 trace->entries = stack_trace + nr_stack_trace_entries;
404 save_stack_trace(trace);
407 * Some daft arches put -1 at the end to indicate its a full trace.
409 * <rant> this is buggy anyway, since it takes a whole extra entry so a
410 * complete trace that maxes out the entries provided will be reported
411 * as incomplete, friggin useless </rant>
413 if (trace->nr_entries != 0 &&
414 trace->entries[trace->nr_entries-1] == ULONG_MAX)
417 trace->max_entries = trace->nr_entries;
419 nr_stack_trace_entries += trace->nr_entries;
421 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
422 if (!debug_locks_off_graph_unlock())
425 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
434 unsigned int nr_hardirq_chains;
435 unsigned int nr_softirq_chains;
436 unsigned int nr_process_chains;
437 unsigned int max_lockdep_depth;
439 #ifdef CONFIG_DEBUG_LOCKDEP
441 * Various lockdep statistics:
443 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
450 #define __USAGE(__STATE) \
451 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
452 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
453 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
454 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
456 static const char *usage_str[] =
458 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
459 #include "lockdep_states.h"
461 [LOCK_USED] = "INITIAL USE",
464 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
466 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
469 static inline unsigned long lock_flag(enum lock_usage_bit bit)
474 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
478 if (class->usage_mask & lock_flag(bit + 2))
480 if (class->usage_mask & lock_flag(bit)) {
482 if (class->usage_mask & lock_flag(bit + 2))
489 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
493 #define LOCKDEP_STATE(__STATE) \
494 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
495 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
496 #include "lockdep_states.h"
502 static void __print_lock_name(struct lock_class *class)
504 char str[KSYM_NAME_LEN];
509 name = __get_key_name(class->key, str);
510 printk(KERN_CONT "%s", name);
512 printk(KERN_CONT "%s", name);
513 if (class->name_version > 1)
514 printk(KERN_CONT "#%d", class->name_version);
516 printk(KERN_CONT "/%d", class->subclass);
520 static void print_lock_name(struct lock_class *class)
522 char usage[LOCK_USAGE_CHARS];
524 get_usage_chars(class, usage);
526 printk(KERN_CONT " (");
527 __print_lock_name(class);
528 printk(KERN_CONT "){%s}", usage);
531 static void print_lockdep_cache(struct lockdep_map *lock)
534 char str[KSYM_NAME_LEN];
538 name = __get_key_name(lock->key->subkeys, str);
540 printk(KERN_CONT "%s", name);
543 static void print_lock(struct held_lock *hlock)
546 * We can be called locklessly through debug_show_all_locks() so be
547 * extra careful, the hlock might have been released and cleared.
549 unsigned int class_idx = hlock->class_idx;
551 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
554 if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
555 printk(KERN_CONT "<RELEASED>\n");
559 printk(KERN_CONT "%p", hlock->instance);
560 print_lock_name(lock_classes + class_idx - 1);
561 printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
564 static void lockdep_print_held_locks(struct task_struct *p)
566 int i, depth = READ_ONCE(p->lockdep_depth);
569 printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p));
571 printk("%d lock%s held by %s/%d:\n", depth,
572 depth > 1 ? "s" : "", p->comm, task_pid_nr(p));
574 * It's not reliable to print a task's held locks if it's not sleeping
575 * and it's not the current task.
577 if (p->state == TASK_RUNNING && p != current)
579 for (i = 0; i < depth; i++) {
581 print_lock(p->held_locks + i);
585 static void print_kernel_ident(void)
587 printk("%s %.*s %s\n", init_utsname()->release,
588 (int)strcspn(init_utsname()->version, " "),
589 init_utsname()->version,
593 static int very_verbose(struct lock_class *class)
596 return class_filter(class);
602 * Is this the address of a static object:
605 static int static_obj(void *obj)
607 unsigned long start = (unsigned long) &_stext,
608 end = (unsigned long) &_end,
609 addr = (unsigned long) obj;
614 if ((addr >= start) && (addr < end))
617 if (arch_is_kernel_data(addr))
621 * in-kernel percpu var?
623 if (is_kernel_percpu_address(addr))
627 * module static or percpu var?
629 return is_module_address(addr) || is_module_percpu_address(addr);
634 * To make lock name printouts unique, we calculate a unique
635 * class->name_version generation counter:
637 static int count_matching_names(struct lock_class *new_class)
639 struct lock_class *class;
642 if (!new_class->name)
645 list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
646 if (new_class->key - new_class->subclass == class->key)
647 return class->name_version;
648 if (class->name && !strcmp(class->name, new_class->name))
649 count = max(count, class->name_version);
655 static inline struct lock_class *
656 look_up_lock_class(const 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 * If it is not initialised then it has never been locked,
674 * so it won't be present in the hash table.
676 if (unlikely(!lock->key))
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(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 * Static locks do not have their class-keys yet - for them the key is
714 * the lock object itself. If the lock is in the per cpu area, the
715 * canonical address of the lock (per cpu offset removed) is used.
717 static bool assign_lock_key(struct lockdep_map *lock)
719 unsigned long can_addr, addr = (unsigned long)lock;
721 if (__is_kernel_percpu_address(addr, &can_addr))
722 lock->key = (void *)can_addr;
723 else if (__is_module_percpu_address(addr, &can_addr))
724 lock->key = (void *)can_addr;
725 else if (static_obj(lock))
726 lock->key = (void *)lock;
728 /* Debug-check: all keys must be persistent! */
730 pr_err("INFO: trying to register non-static key.\n");
731 pr_err("the code is fine but needs lockdep annotation.\n");
732 pr_err("turning off the locking correctness validator.\n");
741 * Register a lock's class in the hash-table, if the class is not present
742 * yet. Otherwise we look it up. We cache the result in the lock object
743 * itself, so actual lookup of the hash should be once per lock object.
745 static struct lock_class *
746 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
748 struct lockdep_subclass_key *key;
749 struct hlist_head *hash_head;
750 struct lock_class *class;
752 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
754 class = look_up_lock_class(lock, subclass);
756 goto out_set_class_cache;
759 if (!assign_lock_key(lock))
761 } else if (!static_obj(lock->key)) {
765 key = lock->key->subkeys + subclass;
766 hash_head = classhashentry(key);
772 * We have to do the hash-walk again, to avoid races
775 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
776 if (class->key == key)
781 * Allocate a new key from the static array, and add it to
784 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
785 if (!debug_locks_off_graph_unlock()) {
789 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
793 class = lock_classes + nr_lock_classes++;
794 debug_atomic_inc(nr_unused_locks);
796 class->name = lock->name;
797 class->subclass = subclass;
798 INIT_LIST_HEAD(&class->lock_entry);
799 INIT_LIST_HEAD(&class->locks_before);
800 INIT_LIST_HEAD(&class->locks_after);
801 class->name_version = count_matching_names(class);
803 * We use RCU's safe list-add method to make
804 * parallel walking of the hash-list safe:
806 hlist_add_head_rcu(&class->hash_entry, hash_head);
808 * Add it to the global list of classes:
810 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
812 if (verbose(class)) {
815 printk("\nnew class %px: %s", class->key, class->name);
816 if (class->name_version > 1)
817 printk(KERN_CONT "#%d", class->name_version);
818 printk(KERN_CONT "\n");
829 if (!subclass || force)
830 lock->class_cache[0] = class;
831 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
832 lock->class_cache[subclass] = class;
835 * Hash collision, did we smoke some? We found a class with a matching
836 * hash but the subclass -- which is hashed in -- didn't match.
838 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
844 #ifdef CONFIG_PROVE_LOCKING
846 * Allocate a lockdep entry. (assumes the graph_lock held, returns
847 * with NULL on failure)
849 static struct lock_list *alloc_list_entry(void)
851 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
852 if (!debug_locks_off_graph_unlock())
855 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
859 return list_entries + nr_list_entries++;
863 * Add a new dependency to the head of the list:
865 static int add_lock_to_list(struct lock_class *this, struct list_head *head,
866 unsigned long ip, int distance,
867 struct stack_trace *trace)
869 struct lock_list *entry;
871 * Lock not present yet - get a new dependency struct and
872 * add it to the list:
874 entry = alloc_list_entry();
879 entry->distance = distance;
880 entry->trace = *trace;
882 * Both allocation and removal are done under the graph lock; but
883 * iteration is under RCU-sched; see look_up_lock_class() and
884 * lockdep_free_key_range().
886 list_add_tail_rcu(&entry->entry, head);
892 * For good efficiency of modular, we use power of 2
894 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
895 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
898 * The circular_queue and helpers is used to implement the
899 * breadth-first search(BFS)algorithem, by which we can build
900 * the shortest path from the next lock to be acquired to the
901 * previous held lock if there is a circular between them.
903 struct circular_queue {
904 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
905 unsigned int front, rear;
908 static struct circular_queue lock_cq;
910 unsigned int max_bfs_queue_depth;
912 static unsigned int lockdep_dependency_gen_id;
914 static inline void __cq_init(struct circular_queue *cq)
916 cq->front = cq->rear = 0;
917 lockdep_dependency_gen_id++;
920 static inline int __cq_empty(struct circular_queue *cq)
922 return (cq->front == cq->rear);
925 static inline int __cq_full(struct circular_queue *cq)
927 return ((cq->rear + 1) & CQ_MASK) == cq->front;
930 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
935 cq->element[cq->rear] = elem;
936 cq->rear = (cq->rear + 1) & CQ_MASK;
940 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
945 *elem = cq->element[cq->front];
946 cq->front = (cq->front + 1) & CQ_MASK;
950 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
952 return (cq->rear - cq->front) & CQ_MASK;
955 static inline void mark_lock_accessed(struct lock_list *lock,
956 struct lock_list *parent)
960 nr = lock - list_entries;
961 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
962 lock->parent = parent;
963 lock->class->dep_gen_id = lockdep_dependency_gen_id;
966 static inline unsigned long lock_accessed(struct lock_list *lock)
970 nr = lock - list_entries;
971 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
972 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
975 static inline struct lock_list *get_lock_parent(struct lock_list *child)
977 return child->parent;
980 static inline int get_lock_depth(struct lock_list *child)
983 struct lock_list *parent;
985 while ((parent = get_lock_parent(child))) {
992 static int __bfs(struct lock_list *source_entry,
994 int (*match)(struct lock_list *entry, void *data),
995 struct lock_list **target_entry,
998 struct lock_list *entry;
999 struct list_head *head;
1000 struct circular_queue *cq = &lock_cq;
1003 if (match(source_entry, data)) {
1004 *target_entry = source_entry;
1010 head = &source_entry->class->locks_after;
1012 head = &source_entry->class->locks_before;
1014 if (list_empty(head))
1018 __cq_enqueue(cq, (unsigned long)source_entry);
1020 while (!__cq_empty(cq)) {
1021 struct lock_list *lock;
1023 __cq_dequeue(cq, (unsigned long *)&lock);
1031 head = &lock->class->locks_after;
1033 head = &lock->class->locks_before;
1035 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1037 list_for_each_entry_rcu(entry, head, entry) {
1038 if (!lock_accessed(entry)) {
1039 unsigned int cq_depth;
1040 mark_lock_accessed(entry, lock);
1041 if (match(entry, data)) {
1042 *target_entry = entry;
1047 if (__cq_enqueue(cq, (unsigned long)entry)) {
1051 cq_depth = __cq_get_elem_count(cq);
1052 if (max_bfs_queue_depth < cq_depth)
1053 max_bfs_queue_depth = cq_depth;
1061 static inline int __bfs_forwards(struct lock_list *src_entry,
1063 int (*match)(struct lock_list *entry, void *data),
1064 struct lock_list **target_entry)
1066 return __bfs(src_entry, data, match, target_entry, 1);
1070 static inline int __bfs_backwards(struct lock_list *src_entry,
1072 int (*match)(struct lock_list *entry, void *data),
1073 struct lock_list **target_entry)
1075 return __bfs(src_entry, data, match, target_entry, 0);
1080 * Recursive, forwards-direction lock-dependency checking, used for
1081 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1086 * Print a dependency chain entry (this is only done when a deadlock
1087 * has been detected):
1090 print_circular_bug_entry(struct lock_list *target, int depth)
1092 if (debug_locks_silent)
1094 printk("\n-> #%u", depth);
1095 print_lock_name(target->class);
1096 printk(KERN_CONT ":\n");
1097 print_stack_trace(&target->trace, 6);
1103 print_circular_lock_scenario(struct held_lock *src,
1104 struct held_lock *tgt,
1105 struct lock_list *prt)
1107 struct lock_class *source = hlock_class(src);
1108 struct lock_class *target = hlock_class(tgt);
1109 struct lock_class *parent = prt->class;
1112 * A direct locking problem where unsafe_class lock is taken
1113 * directly by safe_class lock, then all we need to show
1114 * is the deadlock scenario, as it is obvious that the
1115 * unsafe lock is taken under the safe lock.
1117 * But if there is a chain instead, where the safe lock takes
1118 * an intermediate lock (middle_class) where this lock is
1119 * not the same as the safe lock, then the lock chain is
1120 * used to describe the problem. Otherwise we would need
1121 * to show a different CPU case for each link in the chain
1122 * from the safe_class lock to the unsafe_class lock.
1124 if (parent != source) {
1125 printk("Chain exists of:\n ");
1126 __print_lock_name(source);
1127 printk(KERN_CONT " --> ");
1128 __print_lock_name(parent);
1129 printk(KERN_CONT " --> ");
1130 __print_lock_name(target);
1131 printk(KERN_CONT "\n\n");
1134 printk(" Possible unsafe locking scenario:\n\n");
1135 printk(" CPU0 CPU1\n");
1136 printk(" ---- ----\n");
1138 __print_lock_name(target);
1139 printk(KERN_CONT ");\n");
1141 __print_lock_name(parent);
1142 printk(KERN_CONT ");\n");
1144 __print_lock_name(target);
1145 printk(KERN_CONT ");\n");
1147 __print_lock_name(source);
1148 printk(KERN_CONT ");\n");
1149 printk("\n *** DEADLOCK ***\n\n");
1153 * When a circular dependency is detected, print the
1157 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1158 struct held_lock *check_src,
1159 struct held_lock *check_tgt)
1161 struct task_struct *curr = current;
1163 if (debug_locks_silent)
1167 pr_warn("======================================================\n");
1168 pr_warn("WARNING: possible circular locking dependency detected\n");
1169 print_kernel_ident();
1170 pr_warn("------------------------------------------------------\n");
1171 pr_warn("%s/%d is trying to acquire lock:\n",
1172 curr->comm, task_pid_nr(curr));
1173 print_lock(check_src);
1175 pr_warn("\nbut task is already holding lock:\n");
1177 print_lock(check_tgt);
1178 pr_warn("\nwhich lock already depends on the new lock.\n\n");
1179 pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1181 print_circular_bug_entry(entry, depth);
1186 static inline int class_equal(struct lock_list *entry, void *data)
1188 return entry->class == data;
1191 static noinline int print_circular_bug(struct lock_list *this,
1192 struct lock_list *target,
1193 struct held_lock *check_src,
1194 struct held_lock *check_tgt,
1195 struct stack_trace *trace)
1197 struct task_struct *curr = current;
1198 struct lock_list *parent;
1199 struct lock_list *first_parent;
1202 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1205 if (!save_trace(&this->trace))
1208 depth = get_lock_depth(target);
1210 print_circular_bug_header(target, depth, check_src, check_tgt);
1212 parent = get_lock_parent(target);
1213 first_parent = parent;
1216 print_circular_bug_entry(parent, --depth);
1217 parent = get_lock_parent(parent);
1220 printk("\nother info that might help us debug this:\n\n");
1221 print_circular_lock_scenario(check_src, check_tgt,
1224 lockdep_print_held_locks(curr);
1226 printk("\nstack backtrace:\n");
1232 static noinline int print_bfs_bug(int ret)
1234 if (!debug_locks_off_graph_unlock())
1238 * Breadth-first-search failed, graph got corrupted?
1240 WARN(1, "lockdep bfs error:%d\n", ret);
1245 static int noop_count(struct lock_list *entry, void *data)
1247 (*(unsigned long *)data)++;
1251 static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1253 unsigned long count = 0;
1254 struct lock_list *uninitialized_var(target_entry);
1256 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1260 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1262 unsigned long ret, flags;
1263 struct lock_list this;
1268 raw_local_irq_save(flags);
1269 arch_spin_lock(&lockdep_lock);
1270 ret = __lockdep_count_forward_deps(&this);
1271 arch_spin_unlock(&lockdep_lock);
1272 raw_local_irq_restore(flags);
1277 static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1279 unsigned long count = 0;
1280 struct lock_list *uninitialized_var(target_entry);
1282 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1287 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1289 unsigned long ret, flags;
1290 struct lock_list this;
1295 raw_local_irq_save(flags);
1296 arch_spin_lock(&lockdep_lock);
1297 ret = __lockdep_count_backward_deps(&this);
1298 arch_spin_unlock(&lockdep_lock);
1299 raw_local_irq_restore(flags);
1305 * Prove that the dependency graph starting at <entry> can not
1306 * lead to <target>. Print an error and return 0 if it does.
1309 check_noncircular(struct lock_list *root, struct lock_class *target,
1310 struct lock_list **target_entry)
1314 debug_atomic_inc(nr_cyclic_checks);
1316 result = __bfs_forwards(root, target, class_equal, target_entry);
1322 check_redundant(struct lock_list *root, struct lock_class *target,
1323 struct lock_list **target_entry)
1327 debug_atomic_inc(nr_redundant_checks);
1329 result = __bfs_forwards(root, target, class_equal, target_entry);
1334 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1336 * Forwards and backwards subgraph searching, for the purposes of
1337 * proving that two subgraphs can be connected by a new dependency
1338 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1341 static inline int usage_match(struct lock_list *entry, void *bit)
1343 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1349 * Find a node in the forwards-direction dependency sub-graph starting
1350 * at @root->class that matches @bit.
1352 * Return 0 if such a node exists in the subgraph, and put that node
1353 * into *@target_entry.
1355 * Return 1 otherwise and keep *@target_entry unchanged.
1356 * Return <0 on error.
1359 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1360 struct lock_list **target_entry)
1364 debug_atomic_inc(nr_find_usage_forwards_checks);
1366 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1372 * Find a node in the backwards-direction dependency sub-graph starting
1373 * at @root->class that matches @bit.
1375 * Return 0 if such a node exists in the subgraph, and put that node
1376 * into *@target_entry.
1378 * Return 1 otherwise and keep *@target_entry unchanged.
1379 * Return <0 on error.
1382 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1383 struct lock_list **target_entry)
1387 debug_atomic_inc(nr_find_usage_backwards_checks);
1389 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1394 static void print_lock_class_header(struct lock_class *class, int depth)
1398 printk("%*s->", depth, "");
1399 print_lock_name(class);
1400 printk(KERN_CONT " ops: %lu", class->ops);
1401 printk(KERN_CONT " {\n");
1403 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1404 if (class->usage_mask & (1 << bit)) {
1407 len += printk("%*s %s", depth, "", usage_str[bit]);
1408 len += printk(KERN_CONT " at:\n");
1409 print_stack_trace(class->usage_traces + bit, len);
1412 printk("%*s }\n", depth, "");
1414 printk("%*s ... key at: [<%px>] %pS\n",
1415 depth, "", class->key, class->key);
1419 * printk the shortest lock dependencies from @start to @end in reverse order:
1422 print_shortest_lock_dependencies(struct lock_list *leaf,
1423 struct lock_list *root)
1425 struct lock_list *entry = leaf;
1428 /*compute depth from generated tree by BFS*/
1429 depth = get_lock_depth(leaf);
1432 print_lock_class_header(entry->class, depth);
1433 printk("%*s ... acquired at:\n", depth, "");
1434 print_stack_trace(&entry->trace, 2);
1437 if (depth == 0 && (entry != root)) {
1438 printk("lockdep:%s bad path found in chain graph\n", __func__);
1442 entry = get_lock_parent(entry);
1444 } while (entry && (depth >= 0));
1450 print_irq_lock_scenario(struct lock_list *safe_entry,
1451 struct lock_list *unsafe_entry,
1452 struct lock_class *prev_class,
1453 struct lock_class *next_class)
1455 struct lock_class *safe_class = safe_entry->class;
1456 struct lock_class *unsafe_class = unsafe_entry->class;
1457 struct lock_class *middle_class = prev_class;
1459 if (middle_class == safe_class)
1460 middle_class = next_class;
1463 * A direct locking problem where unsafe_class lock is taken
1464 * directly by safe_class lock, then all we need to show
1465 * is the deadlock scenario, as it is obvious that the
1466 * unsafe lock is taken under the safe lock.
1468 * But if there is a chain instead, where the safe lock takes
1469 * an intermediate lock (middle_class) where this lock is
1470 * not the same as the safe lock, then the lock chain is
1471 * used to describe the problem. Otherwise we would need
1472 * to show a different CPU case for each link in the chain
1473 * from the safe_class lock to the unsafe_class lock.
1475 if (middle_class != unsafe_class) {
1476 printk("Chain exists of:\n ");
1477 __print_lock_name(safe_class);
1478 printk(KERN_CONT " --> ");
1479 __print_lock_name(middle_class);
1480 printk(KERN_CONT " --> ");
1481 __print_lock_name(unsafe_class);
1482 printk(KERN_CONT "\n\n");
1485 printk(" Possible interrupt unsafe locking scenario:\n\n");
1486 printk(" CPU0 CPU1\n");
1487 printk(" ---- ----\n");
1489 __print_lock_name(unsafe_class);
1490 printk(KERN_CONT ");\n");
1491 printk(" local_irq_disable();\n");
1493 __print_lock_name(safe_class);
1494 printk(KERN_CONT ");\n");
1496 __print_lock_name(middle_class);
1497 printk(KERN_CONT ");\n");
1498 printk(" <Interrupt>\n");
1500 __print_lock_name(safe_class);
1501 printk(KERN_CONT ");\n");
1502 printk("\n *** DEADLOCK ***\n\n");
1506 print_bad_irq_dependency(struct task_struct *curr,
1507 struct lock_list *prev_root,
1508 struct lock_list *next_root,
1509 struct lock_list *backwards_entry,
1510 struct lock_list *forwards_entry,
1511 struct held_lock *prev,
1512 struct held_lock *next,
1513 enum lock_usage_bit bit1,
1514 enum lock_usage_bit bit2,
1515 const char *irqclass)
1517 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1521 pr_warn("=====================================================\n");
1522 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
1523 irqclass, irqclass);
1524 print_kernel_ident();
1525 pr_warn("-----------------------------------------------------\n");
1526 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1527 curr->comm, task_pid_nr(curr),
1528 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1529 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1530 curr->hardirqs_enabled,
1531 curr->softirqs_enabled);
1534 pr_warn("\nand this task is already holding:\n");
1536 pr_warn("which would create a new lock dependency:\n");
1537 print_lock_name(hlock_class(prev));
1539 print_lock_name(hlock_class(next));
1542 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
1544 print_lock_name(backwards_entry->class);
1545 pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
1547 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1549 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
1550 print_lock_name(forwards_entry->class);
1551 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
1554 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1556 pr_warn("\nother info that might help us debug this:\n\n");
1557 print_irq_lock_scenario(backwards_entry, forwards_entry,
1558 hlock_class(prev), hlock_class(next));
1560 lockdep_print_held_locks(curr);
1562 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
1563 if (!save_trace(&prev_root->trace))
1565 print_shortest_lock_dependencies(backwards_entry, prev_root);
1567 pr_warn("\nthe dependencies between the lock to be acquired");
1568 pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
1569 if (!save_trace(&next_root->trace))
1571 print_shortest_lock_dependencies(forwards_entry, next_root);
1573 pr_warn("\nstack backtrace:\n");
1580 check_usage(struct task_struct *curr, struct held_lock *prev,
1581 struct held_lock *next, enum lock_usage_bit bit_backwards,
1582 enum lock_usage_bit bit_forwards, const char *irqclass)
1585 struct lock_list this, that;
1586 struct lock_list *uninitialized_var(target_entry);
1587 struct lock_list *uninitialized_var(target_entry1);
1591 this.class = hlock_class(prev);
1592 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1594 return print_bfs_bug(ret);
1599 that.class = hlock_class(next);
1600 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1602 return print_bfs_bug(ret);
1606 return print_bad_irq_dependency(curr, &this, &that,
1607 target_entry, target_entry1,
1609 bit_backwards, bit_forwards, irqclass);
1612 static const char *state_names[] = {
1613 #define LOCKDEP_STATE(__STATE) \
1614 __stringify(__STATE),
1615 #include "lockdep_states.h"
1616 #undef LOCKDEP_STATE
1619 static const char *state_rnames[] = {
1620 #define LOCKDEP_STATE(__STATE) \
1621 __stringify(__STATE)"-READ",
1622 #include "lockdep_states.h"
1623 #undef LOCKDEP_STATE
1626 static inline const char *state_name(enum lock_usage_bit bit)
1628 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1631 static int exclusive_bit(int new_bit)
1639 * bit 0 - write/read
1640 * bit 1 - used_in/enabled
1644 int state = new_bit & ~3;
1645 int dir = new_bit & 2;
1648 * keep state, bit flip the direction and strip read.
1650 return state | (dir ^ 2);
1653 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1654 struct held_lock *next, enum lock_usage_bit bit)
1657 * Prove that the new dependency does not connect a hardirq-safe
1658 * lock with a hardirq-unsafe lock - to achieve this we search
1659 * the backwards-subgraph starting at <prev>, and the
1660 * forwards-subgraph starting at <next>:
1662 if (!check_usage(curr, prev, next, bit,
1663 exclusive_bit(bit), state_name(bit)))
1669 * Prove that the new dependency does not connect a hardirq-safe-read
1670 * lock with a hardirq-unsafe lock - to achieve this we search
1671 * the backwards-subgraph starting at <prev>, and the
1672 * forwards-subgraph starting at <next>:
1674 if (!check_usage(curr, prev, next, bit,
1675 exclusive_bit(bit), state_name(bit)))
1682 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1683 struct held_lock *next)
1685 #define LOCKDEP_STATE(__STATE) \
1686 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1688 #include "lockdep_states.h"
1689 #undef LOCKDEP_STATE
1694 static void inc_chains(void)
1696 if (current->hardirq_context)
1697 nr_hardirq_chains++;
1699 if (current->softirq_context)
1700 nr_softirq_chains++;
1702 nr_process_chains++;
1709 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1710 struct held_lock *next)
1715 static inline void inc_chains(void)
1717 nr_process_chains++;
1723 print_deadlock_scenario(struct held_lock *nxt,
1724 struct held_lock *prv)
1726 struct lock_class *next = hlock_class(nxt);
1727 struct lock_class *prev = hlock_class(prv);
1729 printk(" Possible unsafe locking scenario:\n\n");
1733 __print_lock_name(prev);
1734 printk(KERN_CONT ");\n");
1736 __print_lock_name(next);
1737 printk(KERN_CONT ");\n");
1738 printk("\n *** DEADLOCK ***\n\n");
1739 printk(" May be due to missing lock nesting notation\n\n");
1743 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1744 struct held_lock *next)
1746 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1750 pr_warn("============================================\n");
1751 pr_warn("WARNING: possible recursive locking detected\n");
1752 print_kernel_ident();
1753 pr_warn("--------------------------------------------\n");
1754 pr_warn("%s/%d is trying to acquire lock:\n",
1755 curr->comm, task_pid_nr(curr));
1757 pr_warn("\nbut task is already holding lock:\n");
1760 pr_warn("\nother info that might help us debug this:\n");
1761 print_deadlock_scenario(next, prev);
1762 lockdep_print_held_locks(curr);
1764 pr_warn("\nstack backtrace:\n");
1771 * Check whether we are holding such a class already.
1773 * (Note that this has to be done separately, because the graph cannot
1774 * detect such classes of deadlocks.)
1776 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1779 check_deadlock(struct task_struct *curr, struct held_lock *next,
1780 struct lockdep_map *next_instance, int read)
1782 struct held_lock *prev;
1783 struct held_lock *nest = NULL;
1786 for (i = 0; i < curr->lockdep_depth; i++) {
1787 prev = curr->held_locks + i;
1789 if (prev->instance == next->nest_lock)
1792 if (hlock_class(prev) != hlock_class(next))
1796 * Allow read-after-read recursion of the same
1797 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1799 if ((read == 2) && prev->read)
1803 * We're holding the nest_lock, which serializes this lock's
1804 * nesting behaviour.
1809 return print_deadlock_bug(curr, prev, next);
1815 * There was a chain-cache miss, and we are about to add a new dependency
1816 * to a previous lock. We recursively validate the following rules:
1818 * - would the adding of the <prev> -> <next> dependency create a
1819 * circular dependency in the graph? [== circular deadlock]
1821 * - does the new prev->next dependency connect any hardirq-safe lock
1822 * (in the full backwards-subgraph starting at <prev>) with any
1823 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1824 * <next>)? [== illegal lock inversion with hardirq contexts]
1826 * - does the new prev->next dependency connect any softirq-safe lock
1827 * (in the full backwards-subgraph starting at <prev>) with any
1828 * softirq-unsafe lock (in the full forwards-subgraph starting at
1829 * <next>)? [== illegal lock inversion with softirq contexts]
1831 * any of these scenarios could lead to a deadlock.
1833 * Then if all the validations pass, we add the forwards and backwards
1837 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1838 struct held_lock *next, int distance, struct stack_trace *trace,
1839 int (*save)(struct stack_trace *trace))
1841 struct lock_list *uninitialized_var(target_entry);
1842 struct lock_list *entry;
1843 struct lock_list this;
1847 * Prove that the new <prev> -> <next> dependency would not
1848 * create a circular dependency in the graph. (We do this by
1849 * forward-recursing into the graph starting at <next>, and
1850 * checking whether we can reach <prev>.)
1852 * We are using global variables to control the recursion, to
1853 * keep the stackframe size of the recursive functions low:
1855 this.class = hlock_class(next);
1857 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1858 if (unlikely(!ret)) {
1859 if (!trace->entries) {
1861 * If @save fails here, the printing might trigger
1862 * a WARN but because of the !nr_entries it should
1863 * not do bad things.
1867 return print_circular_bug(&this, target_entry, next, prev, trace);
1869 else if (unlikely(ret < 0))
1870 return print_bfs_bug(ret);
1872 if (!check_prev_add_irq(curr, prev, next))
1876 * For recursive read-locks we do all the dependency checks,
1877 * but we dont store read-triggered dependencies (only
1878 * write-triggered dependencies). This ensures that only the
1879 * write-side dependencies matter, and that if for example a
1880 * write-lock never takes any other locks, then the reads are
1881 * equivalent to a NOP.
1883 if (next->read == 2 || prev->read == 2)
1886 * Is the <prev> -> <next> dependency already present?
1888 * (this may occur even though this is a new chain: consider
1889 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1890 * chains - the second one will be new, but L1 already has
1891 * L2 added to its dependency list, due to the first chain.)
1893 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1894 if (entry->class == hlock_class(next)) {
1896 entry->distance = 1;
1902 * Is the <prev> -> <next> link redundant?
1904 this.class = hlock_class(prev);
1906 ret = check_redundant(&this, hlock_class(next), &target_entry);
1908 debug_atomic_inc(nr_redundant);
1912 return print_bfs_bug(ret);
1915 if (!trace->entries && !save(trace))
1919 * Ok, all validations passed, add the new lock
1920 * to the previous lock's dependency list:
1922 ret = add_lock_to_list(hlock_class(next),
1923 &hlock_class(prev)->locks_after,
1924 next->acquire_ip, distance, trace);
1929 ret = add_lock_to_list(hlock_class(prev),
1930 &hlock_class(next)->locks_before,
1931 next->acquire_ip, distance, trace);
1939 * Add the dependency to all directly-previous locks that are 'relevant'.
1940 * The ones that are relevant are (in increasing distance from curr):
1941 * all consecutive trylock entries and the final non-trylock entry - or
1942 * the end of this context's lock-chain - whichever comes first.
1945 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1947 int depth = curr->lockdep_depth;
1948 struct held_lock *hlock;
1949 struct stack_trace trace = {
1959 * Depth must not be zero for a non-head lock:
1964 * At least two relevant locks must exist for this
1967 if (curr->held_locks[depth].irq_context !=
1968 curr->held_locks[depth-1].irq_context)
1972 int distance = curr->lockdep_depth - depth + 1;
1973 hlock = curr->held_locks + depth - 1;
1976 * Only non-recursive-read entries get new dependencies
1979 if (hlock->read != 2 && hlock->check) {
1980 int ret = check_prev_add(curr, hlock, next, distance, &trace, save_trace);
1985 * Stop after the first non-trylock entry,
1986 * as non-trylock entries have added their
1987 * own direct dependencies already, so this
1988 * lock is connected to them indirectly:
1990 if (!hlock->trylock)
1996 * End of lock-stack?
2001 * Stop the search if we cross into another context:
2003 if (curr->held_locks[depth].irq_context !=
2004 curr->held_locks[depth-1].irq_context)
2009 if (!debug_locks_off_graph_unlock())
2013 * Clearly we all shouldn't be here, but since we made it we
2014 * can reliable say we messed up our state. See the above two
2015 * gotos for reasons why we could possibly end up here.
2022 unsigned long nr_lock_chains;
2023 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
2024 int nr_chain_hlocks;
2025 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
2027 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
2029 return lock_classes + chain_hlocks[chain->base + i];
2033 * Returns the index of the first held_lock of the current chain
2035 static inline int get_first_held_lock(struct task_struct *curr,
2036 struct held_lock *hlock)
2039 struct held_lock *hlock_curr;
2041 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2042 hlock_curr = curr->held_locks + i;
2043 if (hlock_curr->irq_context != hlock->irq_context)
2051 #ifdef CONFIG_DEBUG_LOCKDEP
2053 * Returns the next chain_key iteration
2055 static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2057 u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2059 printk(" class_idx:%d -> chain_key:%016Lx",
2061 (unsigned long long)new_chain_key);
2062 return new_chain_key;
2066 print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2068 struct held_lock *hlock;
2070 int depth = curr->lockdep_depth;
2073 printk("depth: %u\n", depth + 1);
2074 for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
2075 hlock = curr->held_locks + i;
2076 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2081 print_chain_key_iteration(hlock_next->class_idx, chain_key);
2082 print_lock(hlock_next);
2085 static void print_chain_keys_chain(struct lock_chain *chain)
2091 printk("depth: %u\n", chain->depth);
2092 for (i = 0; i < chain->depth; i++) {
2093 class_id = chain_hlocks[chain->base + i];
2094 chain_key = print_chain_key_iteration(class_id + 1, chain_key);
2096 print_lock_name(lock_classes + class_id);
2101 static void print_collision(struct task_struct *curr,
2102 struct held_lock *hlock_next,
2103 struct lock_chain *chain)
2106 pr_warn("============================\n");
2107 pr_warn("WARNING: chain_key collision\n");
2108 print_kernel_ident();
2109 pr_warn("----------------------------\n");
2110 pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
2111 pr_warn("Hash chain already cached but the contents don't match!\n");
2113 pr_warn("Held locks:");
2114 print_chain_keys_held_locks(curr, hlock_next);
2116 pr_warn("Locks in cached chain:");
2117 print_chain_keys_chain(chain);
2119 pr_warn("\nstack backtrace:\n");
2125 * Checks whether the chain and the current held locks are consistent
2126 * in depth and also in content. If they are not it most likely means
2127 * that there was a collision during the calculation of the chain_key.
2128 * Returns: 0 not passed, 1 passed
2130 static int check_no_collision(struct task_struct *curr,
2131 struct held_lock *hlock,
2132 struct lock_chain *chain)
2134 #ifdef CONFIG_DEBUG_LOCKDEP
2137 i = get_first_held_lock(curr, hlock);
2139 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2140 print_collision(curr, hlock, chain);
2144 for (j = 0; j < chain->depth - 1; j++, i++) {
2145 id = curr->held_locks[i].class_idx - 1;
2147 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2148 print_collision(curr, hlock, chain);
2157 * This is for building a chain between just two different classes,
2158 * instead of adding a new hlock upon current, which is done by
2159 * add_chain_cache().
2161 * This can be called in any context with two classes, while
2162 * add_chain_cache() must be done within the lock owener's context
2163 * since it uses hlock which might be racy in another context.
2165 static inline int add_chain_cache_classes(unsigned int prev,
2167 unsigned int irq_context,
2170 struct hlist_head *hash_head = chainhashentry(chain_key);
2171 struct lock_chain *chain;
2174 * Allocate a new chain entry from the static array, and add
2179 * We might need to take the graph lock, ensure we've got IRQs
2180 * disabled to make this an IRQ-safe lock.. for recursion reasons
2181 * lockdep won't complain about its own locking errors.
2183 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2186 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2187 if (!debug_locks_off_graph_unlock())
2190 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2195 chain = lock_chains + nr_lock_chains++;
2196 chain->chain_key = chain_key;
2197 chain->irq_context = irq_context;
2199 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2200 chain->base = nr_chain_hlocks;
2201 nr_chain_hlocks += chain->depth;
2202 chain_hlocks[chain->base] = prev - 1;
2203 chain_hlocks[chain->base + 1] = next -1;
2205 #ifdef CONFIG_DEBUG_LOCKDEP
2207 * Important for check_no_collision().
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);
2227 * Adds a dependency chain into chain hashtable. And must be called with
2230 * Return 0 if fail, and graph_lock is released.
2231 * Return 1 if succeed, with graph_lock held.
2233 static inline int add_chain_cache(struct task_struct *curr,
2234 struct held_lock *hlock,
2237 struct lock_class *class = hlock_class(hlock);
2238 struct hlist_head *hash_head = chainhashentry(chain_key);
2239 struct lock_chain *chain;
2243 * Allocate a new chain entry from the static array, and add
2248 * We might need to take the graph lock, ensure we've got IRQs
2249 * disabled to make this an IRQ-safe lock.. for recursion reasons
2250 * lockdep won't complain about its own locking errors.
2252 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2255 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2256 if (!debug_locks_off_graph_unlock())
2259 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2263 chain = lock_chains + nr_lock_chains++;
2264 chain->chain_key = chain_key;
2265 chain->irq_context = hlock->irq_context;
2266 i = get_first_held_lock(curr, hlock);
2267 chain->depth = curr->lockdep_depth + 1 - i;
2269 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2270 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
2271 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2273 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2274 chain->base = nr_chain_hlocks;
2275 for (j = 0; j < chain->depth - 1; j++, i++) {
2276 int lock_id = curr->held_locks[i].class_idx - 1;
2277 chain_hlocks[chain->base + j] = lock_id;
2279 chain_hlocks[chain->base + j] = class - lock_classes;
2282 if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
2283 nr_chain_hlocks += chain->depth;
2285 #ifdef CONFIG_DEBUG_LOCKDEP
2287 * Important for check_no_collision().
2289 if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
2290 if (!debug_locks_off_graph_unlock())
2293 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2299 hlist_add_head_rcu(&chain->entry, hash_head);
2300 debug_atomic_inc(chain_lookup_misses);
2307 * Look up a dependency chain.
2309 static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
2311 struct hlist_head *hash_head = chainhashentry(chain_key);
2312 struct lock_chain *chain;
2315 * We can walk it lock-free, because entries only get added
2318 hlist_for_each_entry_rcu(chain, hash_head, entry) {
2319 if (chain->chain_key == chain_key) {
2320 debug_atomic_inc(chain_lookup_hits);
2328 * If the key is not present yet in dependency chain cache then
2329 * add it and return 1 - in this case the new dependency chain is
2330 * validated. If the key is already hashed, return 0.
2331 * (On return with 1 graph_lock is held.)
2333 static inline int lookup_chain_cache_add(struct task_struct *curr,
2334 struct held_lock *hlock,
2337 struct lock_class *class = hlock_class(hlock);
2338 struct lock_chain *chain = lookup_chain_cache(chain_key);
2342 if (!check_no_collision(curr, hlock, chain))
2345 if (very_verbose(class)) {
2346 printk("\nhash chain already cached, key: "
2347 "%016Lx tail class: [%px] %s\n",
2348 (unsigned long long)chain_key,
2349 class->key, class->name);
2355 if (very_verbose(class)) {
2356 printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
2357 (unsigned long long)chain_key, class->key, class->name);
2364 * We have to walk the chain again locked - to avoid duplicates:
2366 chain = lookup_chain_cache(chain_key);
2372 if (!add_chain_cache(curr, hlock, chain_key))
2378 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2379 struct held_lock *hlock, int chain_head, u64 chain_key)
2382 * Trylock needs to maintain the stack of held locks, but it
2383 * does not add new dependencies, because trylock can be done
2386 * We look up the chain_key and do the O(N^2) check and update of
2387 * the dependencies only if this is a new dependency chain.
2388 * (If lookup_chain_cache_add() return with 1 it acquires
2389 * graph_lock for us)
2391 if (!hlock->trylock && hlock->check &&
2392 lookup_chain_cache_add(curr, hlock, chain_key)) {
2394 * Check whether last held lock:
2396 * - is irq-safe, if this lock is irq-unsafe
2397 * - is softirq-safe, if this lock is hardirq-unsafe
2399 * And check whether the new lock's dependency graph
2400 * could lead back to the previous lock.
2402 * any of these scenarios could lead to a deadlock. If
2405 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2410 * Mark recursive read, as we jump over it when
2411 * building dependencies (just like we jump over
2417 * Add dependency only if this lock is not the head
2418 * of the chain, and if it's not a secondary read-lock:
2420 if (!chain_head && ret != 2) {
2421 if (!check_prevs_add(curr, hlock))
2427 /* after lookup_chain_cache_add(): */
2428 if (unlikely(!debug_locks))
2435 static inline int validate_chain(struct task_struct *curr,
2436 struct lockdep_map *lock, struct held_lock *hlock,
2437 int chain_head, u64 chain_key)
2444 * We are building curr_chain_key incrementally, so double-check
2445 * it from scratch, to make sure that it's done correctly:
2447 static void check_chain_key(struct task_struct *curr)
2449 #ifdef CONFIG_DEBUG_LOCKDEP
2450 struct held_lock *hlock, *prev_hlock = NULL;
2454 for (i = 0; i < curr->lockdep_depth; i++) {
2455 hlock = curr->held_locks + i;
2456 if (chain_key != hlock->prev_chain_key) {
2459 * We got mighty confused, our chain keys don't match
2460 * with what we expect, someone trample on our task state?
2462 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2463 curr->lockdep_depth, i,
2464 (unsigned long long)chain_key,
2465 (unsigned long long)hlock->prev_chain_key);
2469 * Whoops ran out of static storage again?
2471 if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
2474 if (prev_hlock && (prev_hlock->irq_context !=
2475 hlock->irq_context))
2477 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
2480 if (chain_key != curr->curr_chain_key) {
2483 * More smoking hash instead of calculating it, damn see these
2484 * numbers float.. I bet that a pink elephant stepped on my memory.
2486 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2487 curr->lockdep_depth, i,
2488 (unsigned long long)chain_key,
2489 (unsigned long long)curr->curr_chain_key);
2495 print_usage_bug_scenario(struct held_lock *lock)
2497 struct lock_class *class = hlock_class(lock);
2499 printk(" Possible unsafe locking scenario:\n\n");
2503 __print_lock_name(class);
2504 printk(KERN_CONT ");\n");
2505 printk(" <Interrupt>\n");
2507 __print_lock_name(class);
2508 printk(KERN_CONT ");\n");
2509 printk("\n *** DEADLOCK ***\n\n");
2513 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2514 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2516 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2520 pr_warn("================================\n");
2521 pr_warn("WARNING: inconsistent lock state\n");
2522 print_kernel_ident();
2523 pr_warn("--------------------------------\n");
2525 pr_warn("inconsistent {%s} -> {%s} usage.\n",
2526 usage_str[prev_bit], usage_str[new_bit]);
2528 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2529 curr->comm, task_pid_nr(curr),
2530 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2531 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2532 trace_hardirqs_enabled(curr),
2533 trace_softirqs_enabled(curr));
2536 pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
2537 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2539 print_irqtrace_events(curr);
2540 pr_warn("\nother info that might help us debug this:\n");
2541 print_usage_bug_scenario(this);
2543 lockdep_print_held_locks(curr);
2545 pr_warn("\nstack backtrace:\n");
2552 * Print out an error if an invalid bit is set:
2555 valid_state(struct task_struct *curr, struct held_lock *this,
2556 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2558 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2559 return print_usage_bug(curr, this, bad_bit, new_bit);
2563 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2564 enum lock_usage_bit new_bit);
2566 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2569 * print irq inversion bug:
2572 print_irq_inversion_bug(struct task_struct *curr,
2573 struct lock_list *root, struct lock_list *other,
2574 struct held_lock *this, int forwards,
2575 const char *irqclass)
2577 struct lock_list *entry = other;
2578 struct lock_list *middle = NULL;
2581 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2585 pr_warn("========================================================\n");
2586 pr_warn("WARNING: possible irq lock inversion dependency detected\n");
2587 print_kernel_ident();
2588 pr_warn("--------------------------------------------------------\n");
2589 pr_warn("%s/%d just changed the state of lock:\n",
2590 curr->comm, task_pid_nr(curr));
2593 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2595 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2596 print_lock_name(other->class);
2597 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2599 pr_warn("\nother info that might help us debug this:\n");
2601 /* Find a middle lock (if one exists) */
2602 depth = get_lock_depth(other);
2604 if (depth == 0 && (entry != root)) {
2605 pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
2609 entry = get_lock_parent(entry);
2611 } while (entry && entry != root && (depth >= 0));
2613 print_irq_lock_scenario(root, other,
2614 middle ? middle->class : root->class, other->class);
2616 print_irq_lock_scenario(other, root,
2617 middle ? middle->class : other->class, root->class);
2619 lockdep_print_held_locks(curr);
2621 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2622 if (!save_trace(&root->trace))
2624 print_shortest_lock_dependencies(other, root);
2626 pr_warn("\nstack backtrace:\n");
2633 * Prove that in the forwards-direction subgraph starting at <this>
2634 * there is no lock matching <mask>:
2637 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2638 enum lock_usage_bit bit, const char *irqclass)
2641 struct lock_list root;
2642 struct lock_list *uninitialized_var(target_entry);
2645 root.class = hlock_class(this);
2646 ret = find_usage_forwards(&root, bit, &target_entry);
2648 return print_bfs_bug(ret);
2652 return print_irq_inversion_bug(curr, &root, target_entry,
2657 * Prove that in the backwards-direction subgraph starting at <this>
2658 * there is no lock matching <mask>:
2661 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2662 enum lock_usage_bit bit, const char *irqclass)
2665 struct lock_list root;
2666 struct lock_list *uninitialized_var(target_entry);
2669 root.class = hlock_class(this);
2670 ret = find_usage_backwards(&root, bit, &target_entry);
2672 return print_bfs_bug(ret);
2676 return print_irq_inversion_bug(curr, &root, target_entry,
2680 void print_irqtrace_events(struct task_struct *curr)
2682 printk("irq event stamp: %u\n", curr->irq_events);
2683 printk("hardirqs last enabled at (%u): [<%px>] %pS\n",
2684 curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
2685 (void *)curr->hardirq_enable_ip);
2686 printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
2687 curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
2688 (void *)curr->hardirq_disable_ip);
2689 printk("softirqs last enabled at (%u): [<%px>] %pS\n",
2690 curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
2691 (void *)curr->softirq_enable_ip);
2692 printk("softirqs last disabled at (%u): [<%px>] %pS\n",
2693 curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
2694 (void *)curr->softirq_disable_ip);
2697 static int HARDIRQ_verbose(struct lock_class *class)
2700 return class_filter(class);
2705 static int SOFTIRQ_verbose(struct lock_class *class)
2708 return class_filter(class);
2713 #define STRICT_READ_CHECKS 1
2715 static int (*state_verbose_f[])(struct lock_class *class) = {
2716 #define LOCKDEP_STATE(__STATE) \
2718 #include "lockdep_states.h"
2719 #undef LOCKDEP_STATE
2722 static inline int state_verbose(enum lock_usage_bit bit,
2723 struct lock_class *class)
2725 return state_verbose_f[bit >> 2](class);
2728 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2729 enum lock_usage_bit bit, const char *name);
2732 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2733 enum lock_usage_bit new_bit)
2735 int excl_bit = exclusive_bit(new_bit);
2736 int read = new_bit & 1;
2737 int dir = new_bit & 2;
2740 * mark USED_IN has to look forwards -- to ensure no dependency
2741 * has ENABLED state, which would allow recursion deadlocks.
2743 * mark ENABLED has to look backwards -- to ensure no dependee
2744 * has USED_IN state, which, again, would allow recursion deadlocks.
2746 check_usage_f usage = dir ?
2747 check_usage_backwards : check_usage_forwards;
2750 * Validate that this particular lock does not have conflicting
2753 if (!valid_state(curr, this, new_bit, excl_bit))
2757 * Validate that the lock dependencies don't have conflicting usage
2760 if ((!read || !dir || STRICT_READ_CHECKS) &&
2761 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2765 * Check for read in write conflicts
2768 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2771 if (STRICT_READ_CHECKS &&
2772 !usage(curr, this, excl_bit + 1,
2773 state_name(new_bit + 1)))
2777 if (state_verbose(new_bit, hlock_class(this)))
2784 #define LOCKDEP_STATE(__STATE) __STATE,
2785 #include "lockdep_states.h"
2786 #undef LOCKDEP_STATE
2790 * Mark all held locks with a usage bit:
2793 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2795 enum lock_usage_bit usage_bit;
2796 struct held_lock *hlock;
2799 for (i = 0; i < curr->lockdep_depth; i++) {
2800 hlock = curr->held_locks + i;
2802 usage_bit = 2 + (mark << 2); /* ENABLED */
2804 usage_bit += 1; /* READ */
2806 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2811 if (!mark_lock(curr, hlock, usage_bit))
2819 * Hardirqs will be enabled:
2821 static void __trace_hardirqs_on_caller(unsigned long ip)
2823 struct task_struct *curr = current;
2825 /* we'll do an OFF -> ON transition: */
2826 curr->hardirqs_enabled = 1;
2829 * We are going to turn hardirqs on, so set the
2830 * usage bit for all held locks:
2832 if (!mark_held_locks(curr, HARDIRQ))
2835 * If we have softirqs enabled, then set the usage
2836 * bit for all held locks. (disabled hardirqs prevented
2837 * this bit from being set before)
2839 if (curr->softirqs_enabled)
2840 if (!mark_held_locks(curr, SOFTIRQ))
2843 curr->hardirq_enable_ip = ip;
2844 curr->hardirq_enable_event = ++curr->irq_events;
2845 debug_atomic_inc(hardirqs_on_events);
2848 __visible void trace_hardirqs_on_caller(unsigned long ip)
2850 time_hardirqs_on(CALLER_ADDR0, ip);
2852 if (unlikely(!debug_locks || current->lockdep_recursion))
2855 if (unlikely(current->hardirqs_enabled)) {
2857 * Neither irq nor preemption are disabled here
2858 * so this is racy by nature but losing one hit
2859 * in a stat is not a big deal.
2861 __debug_atomic_inc(redundant_hardirqs_on);
2866 * We're enabling irqs and according to our state above irqs weren't
2867 * already enabled, yet we find the hardware thinks they are in fact
2868 * enabled.. someone messed up their IRQ state tracing.
2870 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2874 * See the fine text that goes along with this variable definition.
2876 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2880 * Can't allow enabling interrupts while in an interrupt handler,
2881 * that's general bad form and such. Recursion, limited stack etc..
2883 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2886 current->lockdep_recursion = 1;
2887 __trace_hardirqs_on_caller(ip);
2888 current->lockdep_recursion = 0;
2890 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2892 void trace_hardirqs_on(void)
2894 trace_hardirqs_on_caller(CALLER_ADDR0);
2896 EXPORT_SYMBOL(trace_hardirqs_on);
2899 * Hardirqs were disabled:
2901 __visible void trace_hardirqs_off_caller(unsigned long ip)
2903 struct task_struct *curr = current;
2905 time_hardirqs_off(CALLER_ADDR0, ip);
2907 if (unlikely(!debug_locks || current->lockdep_recursion))
2911 * So we're supposed to get called after you mask local IRQs, but for
2912 * some reason the hardware doesn't quite think you did a proper job.
2914 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2917 if (curr->hardirqs_enabled) {
2919 * We have done an ON -> OFF transition:
2921 curr->hardirqs_enabled = 0;
2922 curr->hardirq_disable_ip = ip;
2923 curr->hardirq_disable_event = ++curr->irq_events;
2924 debug_atomic_inc(hardirqs_off_events);
2926 debug_atomic_inc(redundant_hardirqs_off);
2928 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2930 void trace_hardirqs_off(void)
2932 trace_hardirqs_off_caller(CALLER_ADDR0);
2934 EXPORT_SYMBOL(trace_hardirqs_off);
2937 * Softirqs will be enabled:
2939 void trace_softirqs_on(unsigned long ip)
2941 struct task_struct *curr = current;
2943 if (unlikely(!debug_locks || current->lockdep_recursion))
2947 * We fancy IRQs being disabled here, see softirq.c, avoids
2948 * funny state and nesting things.
2950 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2953 if (curr->softirqs_enabled) {
2954 debug_atomic_inc(redundant_softirqs_on);
2958 current->lockdep_recursion = 1;
2960 * We'll do an OFF -> ON transition:
2962 curr->softirqs_enabled = 1;
2963 curr->softirq_enable_ip = ip;
2964 curr->softirq_enable_event = ++curr->irq_events;
2965 debug_atomic_inc(softirqs_on_events);
2967 * We are going to turn softirqs on, so set the
2968 * usage bit for all held locks, if hardirqs are
2971 if (curr->hardirqs_enabled)
2972 mark_held_locks(curr, SOFTIRQ);
2973 current->lockdep_recursion = 0;
2977 * Softirqs were disabled:
2979 void trace_softirqs_off(unsigned long ip)
2981 struct task_struct *curr = current;
2983 if (unlikely(!debug_locks || current->lockdep_recursion))
2987 * We fancy IRQs being disabled here, see softirq.c
2989 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2992 if (curr->softirqs_enabled) {
2994 * We have done an ON -> OFF transition:
2996 curr->softirqs_enabled = 0;
2997 curr->softirq_disable_ip = ip;
2998 curr->softirq_disable_event = ++curr->irq_events;
2999 debug_atomic_inc(softirqs_off_events);
3001 * Whoops, we wanted softirqs off, so why aren't they?
3003 DEBUG_LOCKS_WARN_ON(!softirq_count());
3005 debug_atomic_inc(redundant_softirqs_off);
3008 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
3011 * If non-trylock use in a hardirq or softirq context, then
3012 * mark the lock as used in these contexts:
3014 if (!hlock->trylock) {
3016 if (curr->hardirq_context)
3017 if (!mark_lock(curr, hlock,
3018 LOCK_USED_IN_HARDIRQ_READ))
3020 if (curr->softirq_context)
3021 if (!mark_lock(curr, hlock,
3022 LOCK_USED_IN_SOFTIRQ_READ))
3025 if (curr->hardirq_context)
3026 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
3028 if (curr->softirq_context)
3029 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
3033 if (!hlock->hardirqs_off) {
3035 if (!mark_lock(curr, hlock,
3036 LOCK_ENABLED_HARDIRQ_READ))
3038 if (curr->softirqs_enabled)
3039 if (!mark_lock(curr, hlock,
3040 LOCK_ENABLED_SOFTIRQ_READ))
3043 if (!mark_lock(curr, hlock,
3044 LOCK_ENABLED_HARDIRQ))
3046 if (curr->softirqs_enabled)
3047 if (!mark_lock(curr, hlock,
3048 LOCK_ENABLED_SOFTIRQ))
3056 static inline unsigned int task_irq_context(struct task_struct *task)
3058 return 2 * !!task->hardirq_context + !!task->softirq_context;
3061 static int separate_irq_context(struct task_struct *curr,
3062 struct held_lock *hlock)
3064 unsigned int depth = curr->lockdep_depth;
3067 * Keep track of points where we cross into an interrupt context:
3070 struct held_lock *prev_hlock;
3072 prev_hlock = curr->held_locks + depth-1;
3074 * If we cross into another context, reset the
3075 * hash key (this also prevents the checking and the
3076 * adding of the dependency to 'prev'):
3078 if (prev_hlock->irq_context != hlock->irq_context)
3084 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3087 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
3088 enum lock_usage_bit new_bit)
3090 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
3094 static inline int mark_irqflags(struct task_struct *curr,
3095 struct held_lock *hlock)
3100 static inline unsigned int task_irq_context(struct task_struct *task)
3105 static inline int separate_irq_context(struct task_struct *curr,
3106 struct held_lock *hlock)
3111 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3114 * Mark a lock with a usage bit, and validate the state transition:
3116 static int mark_lock(struct task_struct *curr, struct held_lock *this,
3117 enum lock_usage_bit new_bit)
3119 unsigned int new_mask = 1 << new_bit, ret = 1;
3122 * If already set then do not dirty the cacheline,
3123 * nor do any checks:
3125 if (likely(hlock_class(this)->usage_mask & new_mask))
3131 * Make sure we didn't race:
3133 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3138 hlock_class(this)->usage_mask |= new_mask;
3140 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
3144 #define LOCKDEP_STATE(__STATE) \
3145 case LOCK_USED_IN_##__STATE: \
3146 case LOCK_USED_IN_##__STATE##_READ: \
3147 case LOCK_ENABLED_##__STATE: \
3148 case LOCK_ENABLED_##__STATE##_READ:
3149 #include "lockdep_states.h"
3150 #undef LOCKDEP_STATE
3151 ret = mark_lock_irq(curr, this, new_bit);
3156 debug_atomic_dec(nr_unused_locks);
3159 if (!debug_locks_off_graph_unlock())
3168 * We must printk outside of the graph_lock:
3171 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3173 print_irqtrace_events(curr);
3181 * Initialize a lock instance's lock-class mapping info:
3183 static void __lockdep_init_map(struct lockdep_map *lock, const char *name,
3184 struct lock_class_key *key, int subclass)
3188 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3189 lock->class_cache[i] = NULL;
3191 #ifdef CONFIG_LOCK_STAT
3192 lock->cpu = raw_smp_processor_id();
3196 * Can't be having no nameless bastards around this place!
3198 if (DEBUG_LOCKS_WARN_ON(!name)) {
3199 lock->name = "NULL";
3206 * No key, no joy, we need to hash something.
3208 if (DEBUG_LOCKS_WARN_ON(!key))
3211 * Sanity check, the lock-class key must be persistent:
3213 if (!static_obj(key)) {
3214 printk("BUG: key %px not in .data!\n", key);
3216 * What it says above ^^^^^, I suggest you read it.
3218 DEBUG_LOCKS_WARN_ON(1);
3223 if (unlikely(!debug_locks))
3227 unsigned long flags;
3229 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3232 raw_local_irq_save(flags);
3233 current->lockdep_recursion = 1;
3234 register_lock_class(lock, subclass, 1);
3235 current->lockdep_recursion = 0;
3236 raw_local_irq_restore(flags);
3240 void lockdep_init_map(struct lockdep_map *lock, const char *name,
3241 struct lock_class_key *key, int subclass)
3243 __lockdep_init_map(lock, name, key, subclass);
3245 EXPORT_SYMBOL_GPL(lockdep_init_map);
3247 struct lock_class_key __lockdep_no_validate__;
3248 EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3251 print_lock_nested_lock_not_held(struct task_struct *curr,
3252 struct held_lock *hlock,
3255 if (!debug_locks_off())
3257 if (debug_locks_silent)
3261 pr_warn("==================================\n");
3262 pr_warn("WARNING: Nested lock was not taken\n");
3263 print_kernel_ident();
3264 pr_warn("----------------------------------\n");
3266 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3269 pr_warn("\nbut this task is not holding:\n");
3270 pr_warn("%s\n", hlock->nest_lock->name);
3272 pr_warn("\nstack backtrace:\n");
3275 pr_warn("\nother info that might help us debug this:\n");
3276 lockdep_print_held_locks(curr);
3278 pr_warn("\nstack backtrace:\n");
3284 static int __lock_is_held(const struct lockdep_map *lock, int read);
3287 * This gets called for every mutex_lock*()/spin_lock*() operation.
3288 * We maintain the dependency maps and validate the locking attempt:
3290 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3291 int trylock, int read, int check, int hardirqs_off,
3292 struct lockdep_map *nest_lock, unsigned long ip,
3293 int references, int pin_count)
3295 struct task_struct *curr = current;
3296 struct lock_class *class = NULL;
3297 struct held_lock *hlock;
3303 if (unlikely(!debug_locks))
3307 * Lockdep should run with IRQs disabled, otherwise we could
3308 * get an interrupt which would want to take locks, which would
3309 * end up in lockdep and have you got a head-ache already?
3311 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3314 if (!prove_locking || lock->key == &__lockdep_no_validate__)
3317 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3318 class = lock->class_cache[subclass];
3322 if (unlikely(!class)) {
3323 class = register_lock_class(lock, subclass, 0);
3327 atomic_inc((atomic_t *)&class->ops);
3328 if (very_verbose(class)) {
3329 printk("\nacquire class [%px] %s", class->key, class->name);
3330 if (class->name_version > 1)
3331 printk(KERN_CONT "#%d", class->name_version);
3332 printk(KERN_CONT "\n");
3337 * Add the lock to the list of currently held locks.
3338 * (we dont increase the depth just yet, up until the
3339 * dependency checks are done)
3341 depth = curr->lockdep_depth;
3343 * Ran out of static storage for our per-task lock stack again have we?
3345 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3348 class_idx = class - lock_classes + 1;
3351 hlock = curr->held_locks + depth - 1;
3352 if (hlock->class_idx == class_idx && nest_lock) {
3353 if (hlock->references) {
3355 * Check: unsigned int references:12, overflow.
3357 if (DEBUG_LOCKS_WARN_ON(hlock->references == (1 << 12)-1))
3360 hlock->references++;
3362 hlock->references = 2;
3369 hlock = curr->held_locks + depth;
3371 * Plain impossible, we just registered it and checked it weren't no
3372 * NULL like.. I bet this mushroom I ate was good!
3374 if (DEBUG_LOCKS_WARN_ON(!class))
3376 hlock->class_idx = class_idx;
3377 hlock->acquire_ip = ip;
3378 hlock->instance = lock;
3379 hlock->nest_lock = nest_lock;
3380 hlock->irq_context = task_irq_context(curr);
3381 hlock->trylock = trylock;
3383 hlock->check = check;
3384 hlock->hardirqs_off = !!hardirqs_off;
3385 hlock->references = references;
3386 #ifdef CONFIG_LOCK_STAT
3387 hlock->waittime_stamp = 0;
3388 hlock->holdtime_stamp = lockstat_clock();
3390 hlock->pin_count = pin_count;
3392 if (check && !mark_irqflags(curr, hlock))
3395 /* mark it as used: */
3396 if (!mark_lock(curr, hlock, LOCK_USED))
3400 * Calculate the chain hash: it's the combined hash of all the
3401 * lock keys along the dependency chain. We save the hash value
3402 * at every step so that we can get the current hash easily
3403 * after unlock. The chain hash is then used to cache dependency
3406 * The 'key ID' is what is the most compact key value to drive
3407 * the hash, not class->key.
3410 * Whoops, we did it again.. ran straight out of our static allocation.
3412 if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
3415 chain_key = curr->curr_chain_key;
3418 * How can we have a chain hash when we ain't got no keys?!
3420 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3425 hlock->prev_chain_key = chain_key;
3426 if (separate_irq_context(curr, hlock)) {
3430 chain_key = iterate_chain_key(chain_key, class_idx);
3432 if (nest_lock && !__lock_is_held(nest_lock, -1))
3433 return print_lock_nested_lock_not_held(curr, hlock, ip);
3435 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3438 curr->curr_chain_key = chain_key;
3439 curr->lockdep_depth++;
3440 check_chain_key(curr);
3441 #ifdef CONFIG_DEBUG_LOCKDEP
3442 if (unlikely(!debug_locks))
3445 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3447 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3448 printk(KERN_DEBUG "depth: %i max: %lu!\n",
3449 curr->lockdep_depth, MAX_LOCK_DEPTH);
3451 lockdep_print_held_locks(current);
3452 debug_show_all_locks();
3458 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3459 max_lockdep_depth = curr->lockdep_depth;
3465 print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3468 if (!debug_locks_off())
3470 if (debug_locks_silent)
3474 pr_warn("=====================================\n");
3475 pr_warn("WARNING: bad unlock balance detected!\n");
3476 print_kernel_ident();
3477 pr_warn("-------------------------------------\n");
3478 pr_warn("%s/%d is trying to release lock (",
3479 curr->comm, task_pid_nr(curr));
3480 print_lockdep_cache(lock);
3483 pr_warn("but there are no more locks to release!\n");
3484 pr_warn("\nother info that might help us debug this:\n");
3485 lockdep_print_held_locks(curr);
3487 pr_warn("\nstack backtrace:\n");
3493 static int match_held_lock(const struct held_lock *hlock,
3494 const struct lockdep_map *lock)
3496 if (hlock->instance == lock)
3499 if (hlock->references) {
3500 const struct lock_class *class = lock->class_cache[0];
3503 class = look_up_lock_class(lock, 0);
3506 * If look_up_lock_class() failed to find a class, we're trying
3507 * to test if we hold a lock that has never yet been acquired.
3508 * Clearly if the lock hasn't been acquired _ever_, we're not
3509 * holding it either, so report failure.
3515 * References, but not a lock we're actually ref-counting?
3516 * State got messed up, follow the sites that change ->references
3517 * and try to make sense of it.
3519 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3522 if (hlock->class_idx == class - lock_classes + 1)
3529 /* @depth must not be zero */
3530 static struct held_lock *find_held_lock(struct task_struct *curr,
3531 struct lockdep_map *lock,
3532 unsigned int depth, int *idx)
3534 struct held_lock *ret, *hlock, *prev_hlock;
3538 hlock = curr->held_locks + i;
3540 if (match_held_lock(hlock, lock))
3544 for (i--, prev_hlock = hlock--;
3546 i--, prev_hlock = hlock--) {
3548 * We must not cross into another context:
3550 if (prev_hlock->irq_context != hlock->irq_context) {
3554 if (match_held_lock(hlock, lock)) {
3565 static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
3568 struct held_lock *hlock;
3570 for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
3571 if (!__lock_acquire(hlock->instance,
3572 hlock_class(hlock)->subclass,
3574 hlock->read, hlock->check,
3575 hlock->hardirqs_off,
3576 hlock->nest_lock, hlock->acquire_ip,
3577 hlock->references, hlock->pin_count))
3584 __lock_set_class(struct lockdep_map *lock, const char *name,
3585 struct lock_class_key *key, unsigned int subclass,
3588 struct task_struct *curr = current;
3589 struct held_lock *hlock;
3590 struct lock_class *class;
3594 depth = curr->lockdep_depth;
3596 * This function is about (re)setting the class of a held lock,
3597 * yet we're not actually holding any locks. Naughty user!
3599 if (DEBUG_LOCKS_WARN_ON(!depth))
3602 hlock = find_held_lock(curr, lock, depth, &i);
3604 return print_unlock_imbalance_bug(curr, lock, ip);
3606 lockdep_init_map(lock, name, key, 0);
3607 class = register_lock_class(lock, subclass, 0);
3608 hlock->class_idx = class - lock_classes + 1;
3610 curr->lockdep_depth = i;
3611 curr->curr_chain_key = hlock->prev_chain_key;
3613 if (reacquire_held_locks(curr, depth, i))
3617 * I took it apart and put it back together again, except now I have
3618 * these 'spare' parts.. where shall I put them.
3620 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3625 static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
3627 struct task_struct *curr = current;
3628 struct held_lock *hlock;
3632 depth = curr->lockdep_depth;
3634 * This function is about (re)setting the class of a held lock,
3635 * yet we're not actually holding any locks. Naughty user!
3637 if (DEBUG_LOCKS_WARN_ON(!depth))
3640 hlock = find_held_lock(curr, lock, depth, &i);
3642 return print_unlock_imbalance_bug(curr, lock, ip);
3644 curr->lockdep_depth = i;
3645 curr->curr_chain_key = hlock->prev_chain_key;
3647 WARN(hlock->read, "downgrading a read lock");
3649 hlock->acquire_ip = ip;
3651 if (reacquire_held_locks(curr, depth, i))
3655 * I took it apart and put it back together again, except now I have
3656 * these 'spare' parts.. where shall I put them.
3658 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3664 * Remove the lock to the list of currently held locks - this gets
3665 * called on mutex_unlock()/spin_unlock*() (or on a failed
3666 * mutex_lock_interruptible()).
3668 * @nested is an hysterical artifact, needs a tree wide cleanup.
3671 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3673 struct task_struct *curr = current;
3674 struct held_lock *hlock;
3678 if (unlikely(!debug_locks))
3681 depth = curr->lockdep_depth;
3683 * So we're all set to release this lock.. wait what lock? We don't
3684 * own any locks, you've been drinking again?
3686 if (DEBUG_LOCKS_WARN_ON(depth <= 0))
3687 return print_unlock_imbalance_bug(curr, lock, ip);
3690 * Check whether the lock exists in the current stack
3693 hlock = find_held_lock(curr, lock, depth, &i);
3695 return print_unlock_imbalance_bug(curr, lock, ip);
3697 if (hlock->instance == lock)
3698 lock_release_holdtime(hlock);
3700 WARN(hlock->pin_count, "releasing a pinned lock\n");
3702 if (hlock->references) {
3703 hlock->references--;
3704 if (hlock->references) {
3706 * We had, and after removing one, still have
3707 * references, the current lock stack is still
3708 * valid. We're done!
3715 * We have the right lock to unlock, 'hlock' points to it.
3716 * Now we remove it from the stack, and add back the other
3717 * entries (if any), recalculating the hash along the way:
3720 curr->lockdep_depth = i;
3721 curr->curr_chain_key = hlock->prev_chain_key;
3723 if (reacquire_held_locks(curr, depth, i + 1))
3727 * We had N bottles of beer on the wall, we drank one, but now
3728 * there's not N-1 bottles of beer left on the wall...
3730 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3736 static int __lock_is_held(const struct lockdep_map *lock, int read)
3738 struct task_struct *curr = current;
3741 for (i = 0; i < curr->lockdep_depth; i++) {
3742 struct held_lock *hlock = curr->held_locks + i;
3744 if (match_held_lock(hlock, lock)) {
3745 if (read == -1 || hlock->read == read)
3755 static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
3757 struct pin_cookie cookie = NIL_COOKIE;
3758 struct task_struct *curr = current;
3761 if (unlikely(!debug_locks))
3764 for (i = 0; i < curr->lockdep_depth; i++) {
3765 struct held_lock *hlock = curr->held_locks + i;
3767 if (match_held_lock(hlock, lock)) {
3769 * Grab 16bits of randomness; this is sufficient to not
3770 * be guessable and still allows some pin nesting in
3771 * our u32 pin_count.
3773 cookie.val = 1 + (prandom_u32() >> 16);
3774 hlock->pin_count += cookie.val;
3779 WARN(1, "pinning an unheld lock\n");
3783 static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3785 struct task_struct *curr = current;
3788 if (unlikely(!debug_locks))
3791 for (i = 0; i < curr->lockdep_depth; i++) {
3792 struct held_lock *hlock = curr->held_locks + i;
3794 if (match_held_lock(hlock, lock)) {
3795 hlock->pin_count += cookie.val;
3800 WARN(1, "pinning an unheld lock\n");
3803 static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3805 struct task_struct *curr = current;
3808 if (unlikely(!debug_locks))
3811 for (i = 0; i < curr->lockdep_depth; i++) {
3812 struct held_lock *hlock = curr->held_locks + i;
3814 if (match_held_lock(hlock, lock)) {
3815 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
3818 hlock->pin_count -= cookie.val;
3820 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
3821 hlock->pin_count = 0;
3827 WARN(1, "unpinning an unheld lock\n");
3831 * Check whether we follow the irq-flags state precisely:
3833 static void check_flags(unsigned long flags)
3835 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3836 defined(CONFIG_TRACE_IRQFLAGS)
3840 if (irqs_disabled_flags(flags)) {
3841 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3842 printk("possible reason: unannotated irqs-off.\n");
3845 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3846 printk("possible reason: unannotated irqs-on.\n");
3851 * We dont accurately track softirq state in e.g.
3852 * hardirq contexts (such as on 4KSTACKS), so only
3853 * check if not in hardirq contexts:
3855 if (!hardirq_count()) {
3856 if (softirq_count()) {
3857 /* like the above, but with softirqs */
3858 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3860 /* lick the above, does it taste good? */
3861 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3866 print_irqtrace_events(current);
3870 void lock_set_class(struct lockdep_map *lock, const char *name,
3871 struct lock_class_key *key, unsigned int subclass,
3874 unsigned long flags;
3876 if (unlikely(current->lockdep_recursion))
3879 raw_local_irq_save(flags);
3880 current->lockdep_recursion = 1;
3882 if (__lock_set_class(lock, name, key, subclass, ip))
3883 check_chain_key(current);
3884 current->lockdep_recursion = 0;
3885 raw_local_irq_restore(flags);
3887 EXPORT_SYMBOL_GPL(lock_set_class);
3889 void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
3891 unsigned long flags;
3893 if (unlikely(current->lockdep_recursion))
3896 raw_local_irq_save(flags);
3897 current->lockdep_recursion = 1;
3899 if (__lock_downgrade(lock, ip))
3900 check_chain_key(current);
3901 current->lockdep_recursion = 0;
3902 raw_local_irq_restore(flags);
3904 EXPORT_SYMBOL_GPL(lock_downgrade);
3907 * We are not always called with irqs disabled - do that here,
3908 * and also avoid lockdep recursion:
3910 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3911 int trylock, int read, int check,
3912 struct lockdep_map *nest_lock, unsigned long ip)
3914 unsigned long flags;
3916 if (unlikely(current->lockdep_recursion))
3919 raw_local_irq_save(flags);
3922 current->lockdep_recursion = 1;
3923 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3924 __lock_acquire(lock, subclass, trylock, read, check,
3925 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
3926 current->lockdep_recursion = 0;
3927 raw_local_irq_restore(flags);
3929 EXPORT_SYMBOL_GPL(lock_acquire);
3931 void lock_release(struct lockdep_map *lock, int nested,
3934 unsigned long flags;
3936 if (unlikely(current->lockdep_recursion))
3939 raw_local_irq_save(flags);
3941 current->lockdep_recursion = 1;
3942 trace_lock_release(lock, ip);
3943 if (__lock_release(lock, nested, ip))
3944 check_chain_key(current);
3945 current->lockdep_recursion = 0;
3946 raw_local_irq_restore(flags);
3948 EXPORT_SYMBOL_GPL(lock_release);
3950 int lock_is_held_type(const struct lockdep_map *lock, int read)
3952 unsigned long flags;
3955 if (unlikely(current->lockdep_recursion))
3956 return 1; /* avoid false negative lockdep_assert_held() */
3958 raw_local_irq_save(flags);
3961 current->lockdep_recursion = 1;
3962 ret = __lock_is_held(lock, read);
3963 current->lockdep_recursion = 0;
3964 raw_local_irq_restore(flags);
3968 EXPORT_SYMBOL_GPL(lock_is_held_type);
3970 struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
3972 struct pin_cookie cookie = NIL_COOKIE;
3973 unsigned long flags;
3975 if (unlikely(current->lockdep_recursion))
3978 raw_local_irq_save(flags);
3981 current->lockdep_recursion = 1;
3982 cookie = __lock_pin_lock(lock);
3983 current->lockdep_recursion = 0;
3984 raw_local_irq_restore(flags);
3988 EXPORT_SYMBOL_GPL(lock_pin_lock);
3990 void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3992 unsigned long flags;
3994 if (unlikely(current->lockdep_recursion))
3997 raw_local_irq_save(flags);
4000 current->lockdep_recursion = 1;
4001 __lock_repin_lock(lock, cookie);
4002 current->lockdep_recursion = 0;
4003 raw_local_irq_restore(flags);
4005 EXPORT_SYMBOL_GPL(lock_repin_lock);
4007 void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
4009 unsigned long flags;
4011 if (unlikely(current->lockdep_recursion))
4014 raw_local_irq_save(flags);
4017 current->lockdep_recursion = 1;
4018 __lock_unpin_lock(lock, cookie);
4019 current->lockdep_recursion = 0;
4020 raw_local_irq_restore(flags);
4022 EXPORT_SYMBOL_GPL(lock_unpin_lock);
4024 #ifdef CONFIG_LOCK_STAT
4026 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
4029 if (!debug_locks_off())
4031 if (debug_locks_silent)
4035 pr_warn("=================================\n");
4036 pr_warn("WARNING: bad contention detected!\n");
4037 print_kernel_ident();
4038 pr_warn("---------------------------------\n");
4039 pr_warn("%s/%d is trying to contend lock (",
4040 curr->comm, task_pid_nr(curr));
4041 print_lockdep_cache(lock);
4044 pr_warn("but there are no locks held!\n");
4045 pr_warn("\nother info that might help us debug this:\n");
4046 lockdep_print_held_locks(curr);
4048 pr_warn("\nstack backtrace:\n");
4055 __lock_contended(struct lockdep_map *lock, unsigned long ip)
4057 struct task_struct *curr = current;
4058 struct held_lock *hlock;
4059 struct lock_class_stats *stats;
4061 int i, contention_point, contending_point;
4063 depth = curr->lockdep_depth;
4065 * Whee, we contended on this lock, except it seems we're not
4066 * actually trying to acquire anything much at all..
4068 if (DEBUG_LOCKS_WARN_ON(!depth))
4071 hlock = find_held_lock(curr, lock, depth, &i);
4073 print_lock_contention_bug(curr, lock, ip);
4077 if (hlock->instance != lock)
4080 hlock->waittime_stamp = lockstat_clock();
4082 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
4083 contending_point = lock_point(hlock_class(hlock)->contending_point,
4086 stats = get_lock_stats(hlock_class(hlock));
4087 if (contention_point < LOCKSTAT_POINTS)
4088 stats->contention_point[contention_point]++;
4089 if (contending_point < LOCKSTAT_POINTS)
4090 stats->contending_point[contending_point]++;
4091 if (lock->cpu != smp_processor_id())
4092 stats->bounces[bounce_contended + !!hlock->read]++;
4093 put_lock_stats(stats);
4097 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
4099 struct task_struct *curr = current;
4100 struct held_lock *hlock;
4101 struct lock_class_stats *stats;
4103 u64 now, waittime = 0;
4106 depth = curr->lockdep_depth;
4108 * Yay, we acquired ownership of this lock we didn't try to
4109 * acquire, how the heck did that happen?
4111 if (DEBUG_LOCKS_WARN_ON(!depth))
4114 hlock = find_held_lock(curr, lock, depth, &i);
4116 print_lock_contention_bug(curr, lock, _RET_IP_);
4120 if (hlock->instance != lock)
4123 cpu = smp_processor_id();
4124 if (hlock->waittime_stamp) {
4125 now = lockstat_clock();
4126 waittime = now - hlock->waittime_stamp;
4127 hlock->holdtime_stamp = now;
4130 trace_lock_acquired(lock, ip);
4132 stats = get_lock_stats(hlock_class(hlock));
4135 lock_time_inc(&stats->read_waittime, waittime);
4137 lock_time_inc(&stats->write_waittime, waittime);
4139 if (lock->cpu != cpu)
4140 stats->bounces[bounce_acquired + !!hlock->read]++;
4141 put_lock_stats(stats);
4147 void lock_contended(struct lockdep_map *lock, unsigned long ip)
4149 unsigned long flags;
4151 if (unlikely(!lock_stat))
4154 if (unlikely(current->lockdep_recursion))
4157 raw_local_irq_save(flags);
4159 current->lockdep_recursion = 1;
4160 trace_lock_contended(lock, ip);
4161 __lock_contended(lock, ip);
4162 current->lockdep_recursion = 0;
4163 raw_local_irq_restore(flags);
4165 EXPORT_SYMBOL_GPL(lock_contended);
4167 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
4169 unsigned long flags;
4171 if (unlikely(!lock_stat))
4174 if (unlikely(current->lockdep_recursion))
4177 raw_local_irq_save(flags);
4179 current->lockdep_recursion = 1;
4180 __lock_acquired(lock, ip);
4181 current->lockdep_recursion = 0;
4182 raw_local_irq_restore(flags);
4184 EXPORT_SYMBOL_GPL(lock_acquired);
4188 * Used by the testsuite, sanitize the validator state
4189 * after a simulated failure:
4192 void lockdep_reset(void)
4194 unsigned long flags;
4197 raw_local_irq_save(flags);
4198 current->curr_chain_key = 0;
4199 current->lockdep_depth = 0;
4200 current->lockdep_recursion = 0;
4201 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
4202 nr_hardirq_chains = 0;
4203 nr_softirq_chains = 0;
4204 nr_process_chains = 0;
4206 for (i = 0; i < CHAINHASH_SIZE; i++)
4207 INIT_HLIST_HEAD(chainhash_table + i);
4208 raw_local_irq_restore(flags);
4211 static void zap_class(struct lock_class *class)
4216 * Remove all dependencies this lock is
4219 for (i = 0; i < nr_list_entries; i++) {
4220 if (list_entries[i].class == class)
4221 list_del_rcu(&list_entries[i].entry);
4224 * Unhash the class and remove it from the all_lock_classes list:
4226 hlist_del_rcu(&class->hash_entry);
4227 list_del_rcu(&class->lock_entry);
4229 RCU_INIT_POINTER(class->key, NULL);
4230 RCU_INIT_POINTER(class->name, NULL);
4233 static inline int within(const void *addr, void *start, unsigned long size)
4235 return addr >= start && addr < start + size;
4239 * Used in module.c to remove lock classes from memory that is going to be
4240 * freed; and possibly re-used by other modules.
4242 * We will have had one sync_sched() before getting here, so we're guaranteed
4243 * nobody will look up these exact classes -- they're properly dead but still
4246 void lockdep_free_key_range(void *start, unsigned long size)
4248 struct lock_class *class;
4249 struct hlist_head *head;
4250 unsigned long flags;
4254 raw_local_irq_save(flags);
4255 locked = graph_lock();
4258 * Unhash all classes that were created by this module:
4260 for (i = 0; i < CLASSHASH_SIZE; i++) {
4261 head = classhash_table + i;
4262 hlist_for_each_entry_rcu(class, head, hash_entry) {
4263 if (within(class->key, start, size))
4265 else if (within(class->name, start, size))
4272 raw_local_irq_restore(flags);
4275 * Wait for any possible iterators from look_up_lock_class() to pass
4276 * before continuing to free the memory they refer to.
4278 * sync_sched() is sufficient because the read-side is IRQ disable.
4280 synchronize_sched();
4283 * XXX at this point we could return the resources to the pool;
4284 * instead we leak them. We would need to change to bitmap allocators
4285 * instead of the linear allocators we have now.
4289 void lockdep_reset_lock(struct lockdep_map *lock)
4291 struct lock_class *class;
4292 struct hlist_head *head;
4293 unsigned long flags;
4297 raw_local_irq_save(flags);
4300 * Remove all classes this lock might have:
4302 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
4304 * If the class exists we look it up and zap it:
4306 class = look_up_lock_class(lock, j);
4311 * Debug check: in the end all mapped classes should
4314 locked = graph_lock();
4315 for (i = 0; i < CLASSHASH_SIZE; i++) {
4316 head = classhash_table + i;
4317 hlist_for_each_entry_rcu(class, head, hash_entry) {
4320 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
4321 match |= class == lock->class_cache[j];
4323 if (unlikely(match)) {
4324 if (debug_locks_off_graph_unlock()) {
4326 * We all just reset everything, how did it match?
4338 raw_local_irq_restore(flags);
4341 void __init lockdep_info(void)
4343 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4345 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
4346 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
4347 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
4348 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
4349 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
4350 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
4351 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
4353 printk(" memory used by lock dependency info: %lu kB\n",
4354 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4355 sizeof(struct list_head) * CLASSHASH_SIZE +
4356 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4357 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4358 sizeof(struct list_head) * CHAINHASH_SIZE
4359 #ifdef CONFIG_PROVE_LOCKING
4360 + sizeof(struct circular_queue)
4365 printk(" per task-struct memory footprint: %lu bytes\n",
4366 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4370 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4371 const void *mem_to, struct held_lock *hlock)
4373 if (!debug_locks_off())
4375 if (debug_locks_silent)
4379 pr_warn("=========================\n");
4380 pr_warn("WARNING: held lock freed!\n");
4381 print_kernel_ident();
4382 pr_warn("-------------------------\n");
4383 pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
4384 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4386 lockdep_print_held_locks(curr);
4388 pr_warn("\nstack backtrace:\n");
4392 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4393 const void* lock_from, unsigned long lock_len)
4395 return lock_from + lock_len <= mem_from ||
4396 mem_from + mem_len <= lock_from;
4400 * Called when kernel memory is freed (or unmapped), or if a lock
4401 * is destroyed or reinitialized - this code checks whether there is
4402 * any held lock in the memory range of <from> to <to>:
4404 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4406 struct task_struct *curr = current;
4407 struct held_lock *hlock;
4408 unsigned long flags;
4411 if (unlikely(!debug_locks))
4414 raw_local_irq_save(flags);
4415 for (i = 0; i < curr->lockdep_depth; i++) {
4416 hlock = curr->held_locks + i;
4418 if (not_in_range(mem_from, mem_len, hlock->instance,
4419 sizeof(*hlock->instance)))
4422 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4425 raw_local_irq_restore(flags);
4427 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4429 static void print_held_locks_bug(void)
4431 if (!debug_locks_off())
4433 if (debug_locks_silent)
4437 pr_warn("====================================\n");
4438 pr_warn("WARNING: %s/%d still has locks held!\n",
4439 current->comm, task_pid_nr(current));
4440 print_kernel_ident();
4441 pr_warn("------------------------------------\n");
4442 lockdep_print_held_locks(current);
4443 pr_warn("\nstack backtrace:\n");
4447 void debug_check_no_locks_held(void)
4449 if (unlikely(current->lockdep_depth > 0))
4450 print_held_locks_bug();
4452 EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
4455 void debug_show_all_locks(void)
4457 struct task_struct *g, *p;
4459 if (unlikely(!debug_locks)) {
4460 pr_warn("INFO: lockdep is turned off.\n");
4463 pr_warn("\nShowing all locks held in the system:\n");
4466 for_each_process_thread(g, p) {
4467 if (!p->lockdep_depth)
4469 lockdep_print_held_locks(p);
4470 touch_nmi_watchdog();
4471 touch_all_softlockup_watchdogs();
4476 pr_warn("=============================================\n\n");
4478 EXPORT_SYMBOL_GPL(debug_show_all_locks);
4482 * Careful: only use this function if you are sure that
4483 * the task cannot run in parallel!
4485 void debug_show_held_locks(struct task_struct *task)
4487 if (unlikely(!debug_locks)) {
4488 printk("INFO: lockdep is turned off.\n");
4491 lockdep_print_held_locks(task);
4493 EXPORT_SYMBOL_GPL(debug_show_held_locks);
4495 asmlinkage __visible void lockdep_sys_exit(void)
4497 struct task_struct *curr = current;
4499 if (unlikely(curr->lockdep_depth)) {
4500 if (!debug_locks_off())
4503 pr_warn("================================================\n");
4504 pr_warn("WARNING: lock held when returning to user space!\n");
4505 print_kernel_ident();
4506 pr_warn("------------------------------------------------\n");
4507 pr_warn("%s/%d is leaving the kernel with locks still held!\n",
4508 curr->comm, curr->pid);
4509 lockdep_print_held_locks(curr);
4513 * The lock history for each syscall should be independent. So wipe the
4514 * slate clean on return to userspace.
4516 lockdep_invariant_state(false);
4519 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4521 struct task_struct *curr = current;
4523 /* Note: the following can be executed concurrently, so be careful. */
4525 pr_warn("=============================\n");
4526 pr_warn("WARNING: suspicious RCU usage\n");
4527 print_kernel_ident();
4528 pr_warn("-----------------------------\n");
4529 pr_warn("%s:%d %s!\n", file, line, s);
4530 pr_warn("\nother info that might help us debug this:\n\n");
4531 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4532 !rcu_lockdep_current_cpu_online()
4533 ? "RCU used illegally from offline CPU!\n"
4534 : !rcu_is_watching()
4535 ? "RCU used illegally from idle CPU!\n"
4537 rcu_scheduler_active, debug_locks);
4540 * If a CPU is in the RCU-free window in idle (ie: in the section
4541 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4542 * considers that CPU to be in an "extended quiescent state",
4543 * which means that RCU will be completely ignoring that CPU.
4544 * Therefore, rcu_read_lock() and friends have absolutely no
4545 * effect on a CPU running in that state. In other words, even if
4546 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4547 * delete data structures out from under it. RCU really has no
4548 * choice here: we need to keep an RCU-free window in idle where
4549 * the CPU may possibly enter into low power mode. This way we can
4550 * notice an extended quiescent state to other CPUs that started a grace
4551 * period. Otherwise we would delay any grace period as long as we run
4554 * So complain bitterly if someone does call rcu_read_lock(),
4555 * rcu_read_lock_bh() and so on from extended quiescent states.
4557 if (!rcu_is_watching())
4558 pr_warn("RCU used illegally from extended quiescent state!\n");
4560 lockdep_print_held_locks(curr);
4561 pr_warn("\nstack backtrace:\n");
4564 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);