4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
47 #include <linux/kmemcheck.h>
49 #include <asm/sections.h>
51 #include "lockdep_internals.h"
53 #define CREATE_TRACE_POINTS
54 #include <trace/events/lock.h>
56 #ifdef CONFIG_PROVE_LOCKING
57 int prove_locking = 1;
58 module_param(prove_locking, int, 0644);
60 #define prove_locking 0
63 #ifdef CONFIG_LOCK_STAT
65 module_param(lock_stat, int, 0644);
71 * lockdep_lock: protects the lockdep graph, the hashes and the
72 * class/list/hash allocators.
74 * This is one of the rare exceptions where it's justified
75 * to use a raw spinlock - we really dont want the spinlock
76 * code to recurse back into the lockdep code...
78 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
80 static int graph_lock(void)
82 arch_spin_lock(&lockdep_lock);
84 * Make sure that if another CPU detected a bug while
85 * walking the graph we dont change it (while the other
86 * CPU is busy printing out stuff with the graph lock
90 arch_spin_unlock(&lockdep_lock);
93 /* prevent any recursions within lockdep from causing deadlocks */
94 current->lockdep_recursion++;
98 static inline int graph_unlock(void)
100 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
102 * The lockdep graph lock isn't locked while we expect it to
103 * be, we're confused now, bye!
105 return DEBUG_LOCKS_WARN_ON(1);
108 current->lockdep_recursion--;
109 arch_spin_unlock(&lockdep_lock);
114 * Turn lock debugging off and return with 0 if it was off already,
115 * and also release the graph lock:
117 static inline int debug_locks_off_graph_unlock(void)
119 int ret = debug_locks_off();
121 arch_spin_unlock(&lockdep_lock);
126 static int lockdep_initialized;
128 unsigned long nr_list_entries;
129 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
132 * All data structures here are protected by the global debug_lock.
134 * Mutex key structs only get allocated, once during bootup, and never
135 * get freed - this significantly simplifies the debugging code.
137 unsigned long nr_lock_classes;
138 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
140 static inline struct lock_class *hlock_class(struct held_lock *hlock)
142 if (!hlock->class_idx) {
144 * Someone passed in garbage, we give up.
146 DEBUG_LOCKS_WARN_ON(1);
149 return lock_classes + hlock->class_idx - 1;
152 #ifdef CONFIG_LOCK_STAT
153 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
156 static inline u64 lockstat_clock(void)
158 return local_clock();
161 static int lock_point(unsigned long points[], unsigned long ip)
165 for (i = 0; i < LOCKSTAT_POINTS; i++) {
166 if (points[i] == 0) {
177 static void lock_time_inc(struct lock_time *lt, u64 time)
182 if (time < lt->min || !lt->nr)
189 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
194 if (src->max > dst->max)
197 if (src->min < dst->min || !dst->nr)
200 dst->total += src->total;
204 struct lock_class_stats lock_stats(struct lock_class *class)
206 struct lock_class_stats stats;
209 memset(&stats, 0, sizeof(struct lock_class_stats));
210 for_each_possible_cpu(cpu) {
211 struct lock_class_stats *pcs =
212 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
214 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
215 stats.contention_point[i] += pcs->contention_point[i];
217 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
218 stats.contending_point[i] += pcs->contending_point[i];
220 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
221 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
223 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
224 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
226 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
227 stats.bounces[i] += pcs->bounces[i];
233 void clear_lock_stats(struct lock_class *class)
237 for_each_possible_cpu(cpu) {
238 struct lock_class_stats *cpu_stats =
239 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
241 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
243 memset(class->contention_point, 0, sizeof(class->contention_point));
244 memset(class->contending_point, 0, sizeof(class->contending_point));
247 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
249 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
252 static void put_lock_stats(struct lock_class_stats *stats)
254 put_cpu_var(cpu_lock_stats);
257 static void lock_release_holdtime(struct held_lock *hlock)
259 struct lock_class_stats *stats;
265 holdtime = lockstat_clock() - hlock->holdtime_stamp;
267 stats = get_lock_stats(hlock_class(hlock));
269 lock_time_inc(&stats->read_holdtime, holdtime);
271 lock_time_inc(&stats->write_holdtime, holdtime);
272 put_lock_stats(stats);
275 static inline void lock_release_holdtime(struct held_lock *hlock)
281 * We keep a global list of all lock classes. The list only grows,
282 * never shrinks. The list is only accessed with the lockdep
283 * spinlock lock held.
285 LIST_HEAD(all_lock_classes);
288 * The lockdep classes are in a hash-table as well, for fast lookup:
290 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
291 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
292 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
293 #define classhashentry(key) (classhash_table + __classhashfn((key)))
295 static struct list_head classhash_table[CLASSHASH_SIZE];
298 * We put the lock dependency chains into a hash-table as well, to cache
301 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
302 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
303 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
304 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
306 static struct list_head chainhash_table[CHAINHASH_SIZE];
309 * The hash key of the lock dependency chains is a hash itself too:
310 * it's a hash of all locks taken up to that lock, including that lock.
311 * It's a 64-bit hash, because it's important for the keys to be
314 #define iterate_chain_key(key1, key2) \
315 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
316 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
319 void lockdep_off(void)
321 current->lockdep_recursion++;
323 EXPORT_SYMBOL(lockdep_off);
325 void lockdep_on(void)
327 current->lockdep_recursion--;
329 EXPORT_SYMBOL(lockdep_on);
332 * Debugging switches:
336 #define VERY_VERBOSE 0
339 # define HARDIRQ_VERBOSE 1
340 # define SOFTIRQ_VERBOSE 1
341 # define RECLAIM_VERBOSE 1
343 # define HARDIRQ_VERBOSE 0
344 # define SOFTIRQ_VERBOSE 0
345 # define RECLAIM_VERBOSE 0
348 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
350 * Quick filtering for interesting events:
352 static int class_filter(struct lock_class *class)
356 if (class->name_version == 1 &&
357 !strcmp(class->name, "lockname"))
359 if (class->name_version == 1 &&
360 !strcmp(class->name, "&struct->lockfield"))
363 /* Filter everything else. 1 would be to allow everything else */
368 static int verbose(struct lock_class *class)
371 return class_filter(class);
377 * Stack-trace: tightly packed array of stack backtrace
378 * addresses. Protected by the graph_lock.
380 unsigned long nr_stack_trace_entries;
381 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
383 static void print_lockdep_off(const char *bug_msg)
385 printk(KERN_DEBUG "%s\n", bug_msg);
386 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
387 #ifdef CONFIG_LOCK_STAT
388 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
392 static int save_trace(struct stack_trace *trace)
394 trace->nr_entries = 0;
395 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
396 trace->entries = stack_trace + nr_stack_trace_entries;
400 save_stack_trace(trace);
403 * Some daft arches put -1 at the end to indicate its a full trace.
405 * <rant> this is buggy anyway, since it takes a whole extra entry so a
406 * complete trace that maxes out the entries provided will be reported
407 * as incomplete, friggin useless </rant>
409 if (trace->nr_entries != 0 &&
410 trace->entries[trace->nr_entries-1] == ULONG_MAX)
413 trace->max_entries = trace->nr_entries;
415 nr_stack_trace_entries += trace->nr_entries;
417 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
418 if (!debug_locks_off_graph_unlock())
421 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
430 unsigned int nr_hardirq_chains;
431 unsigned int nr_softirq_chains;
432 unsigned int nr_process_chains;
433 unsigned int max_lockdep_depth;
435 #ifdef CONFIG_DEBUG_LOCKDEP
437 * We cannot printk in early bootup code. Not even early_printk()
438 * might work. So we mark any initialization errors and printk
439 * about it later on, in lockdep_info().
441 static int lockdep_init_error;
442 static const char *lock_init_error;
443 static unsigned long lockdep_init_trace_data[20];
444 static struct stack_trace lockdep_init_trace = {
445 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
446 .entries = lockdep_init_trace_data,
450 * Various lockdep statistics:
452 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
459 #define __USAGE(__STATE) \
460 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
461 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
462 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
463 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
465 static const char *usage_str[] =
467 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
468 #include "lockdep_states.h"
470 [LOCK_USED] = "INITIAL USE",
473 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
475 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
478 static inline unsigned long lock_flag(enum lock_usage_bit bit)
483 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
487 if (class->usage_mask & lock_flag(bit + 2))
489 if (class->usage_mask & lock_flag(bit)) {
491 if (class->usage_mask & lock_flag(bit + 2))
498 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
502 #define LOCKDEP_STATE(__STATE) \
503 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
504 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
505 #include "lockdep_states.h"
511 static void __print_lock_name(struct lock_class *class)
513 char str[KSYM_NAME_LEN];
518 name = __get_key_name(class->key, str);
522 if (class->name_version > 1)
523 printk("#%d", class->name_version);
525 printk("/%d", class->subclass);
529 static void print_lock_name(struct lock_class *class)
531 char usage[LOCK_USAGE_CHARS];
533 get_usage_chars(class, usage);
536 __print_lock_name(class);
537 printk("){%s}", usage);
540 static void print_lockdep_cache(struct lockdep_map *lock)
543 char str[KSYM_NAME_LEN];
547 name = __get_key_name(lock->key->subkeys, str);
552 static void print_lock(struct held_lock *hlock)
554 print_lock_name(hlock_class(hlock));
556 print_ip_sym(hlock->acquire_ip);
559 static void lockdep_print_held_locks(struct task_struct *curr)
561 int i, depth = curr->lockdep_depth;
564 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
567 printk("%d lock%s held by %s/%d:\n",
568 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
570 for (i = 0; i < depth; i++) {
572 print_lock(curr->held_locks + i);
576 static void print_kernel_ident(void)
578 printk("%s %.*s %s\n", init_utsname()->release,
579 (int)strcspn(init_utsname()->version, " "),
580 init_utsname()->version,
584 static int very_verbose(struct lock_class *class)
587 return class_filter(class);
593 * Is this the address of a static object:
596 static int static_obj(void *obj)
598 unsigned long start = (unsigned long) &_stext,
599 end = (unsigned long) &_end,
600 addr = (unsigned long) obj;
605 if ((addr >= start) && (addr < end))
608 if (arch_is_kernel_data(addr))
612 * in-kernel percpu var?
614 if (is_kernel_percpu_address(addr))
618 * module static or percpu var?
620 return is_module_address(addr) || is_module_percpu_address(addr);
625 * To make lock name printouts unique, we calculate a unique
626 * class->name_version generation counter:
628 static int count_matching_names(struct lock_class *new_class)
630 struct lock_class *class;
633 if (!new_class->name)
636 list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
637 if (new_class->key - new_class->subclass == class->key)
638 return class->name_version;
639 if (class->name && !strcmp(class->name, new_class->name))
640 count = max(count, class->name_version);
647 * Register a lock's class in the hash-table, if the class is not present
648 * yet. Otherwise we look it up. We cache the result in the lock object
649 * itself, so actual lookup of the hash should be once per lock object.
651 static inline struct lock_class *
652 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
654 struct lockdep_subclass_key *key;
655 struct list_head *hash_head;
656 struct lock_class *class;
658 #ifdef CONFIG_DEBUG_LOCKDEP
660 * If the architecture calls into lockdep before initializing
661 * the hashes then we'll warn about it later. (we cannot printk
664 if (unlikely(!lockdep_initialized)) {
666 lockdep_init_error = 1;
667 lock_init_error = lock->name;
668 save_stack_trace(&lockdep_init_trace);
672 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
675 "BUG: looking up invalid subclass: %u\n", subclass);
677 "turning off the locking correctness validator.\n");
683 * Static locks do not have their class-keys yet - for them the key
684 * is the lock object itself:
686 if (unlikely(!lock->key))
687 lock->key = (void *)lock;
690 * NOTE: the class-key must be unique. For dynamic locks, a static
691 * lock_class_key variable is passed in through the mutex_init()
692 * (or spin_lock_init()) call - which acts as the key. For static
693 * locks we use the lock object itself as the key.
695 BUILD_BUG_ON(sizeof(struct lock_class_key) >
696 sizeof(struct lockdep_map));
698 key = lock->key->subkeys + subclass;
700 hash_head = classhashentry(key);
703 * We do an RCU walk of the hash, see lockdep_free_key_range().
705 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
708 list_for_each_entry_rcu(class, hash_head, hash_entry) {
709 if (class->key == key) {
711 * Huh! same key, different name? Did someone trample
712 * on some memory? We're most confused.
714 WARN_ON_ONCE(class->name != lock->name);
723 * Register a lock's class in the hash-table, if the class is not present
724 * yet. Otherwise we look it up. We cache the result in the lock object
725 * itself, so actual lookup of the hash should be once per lock object.
727 static inline struct lock_class *
728 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
730 struct lockdep_subclass_key *key;
731 struct list_head *hash_head;
732 struct lock_class *class;
734 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
736 class = look_up_lock_class(lock, subclass);
738 goto out_set_class_cache;
741 * Debug-check: all keys must be persistent!
743 if (!static_obj(lock->key)) {
745 printk("INFO: trying to register non-static key.\n");
746 printk("the code is fine but needs lockdep annotation.\n");
747 printk("turning off the locking correctness validator.\n");
753 key = lock->key->subkeys + subclass;
754 hash_head = classhashentry(key);
760 * We have to do the hash-walk again, to avoid races
763 list_for_each_entry_rcu(class, hash_head, hash_entry) {
764 if (class->key == key)
769 * Allocate a new key from the static array, and add it to
772 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
773 if (!debug_locks_off_graph_unlock()) {
777 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
781 class = lock_classes + nr_lock_classes++;
782 debug_atomic_inc(nr_unused_locks);
784 class->name = lock->name;
785 class->subclass = subclass;
786 INIT_LIST_HEAD(&class->lock_entry);
787 INIT_LIST_HEAD(&class->locks_before);
788 INIT_LIST_HEAD(&class->locks_after);
789 class->name_version = count_matching_names(class);
791 * We use RCU's safe list-add method to make
792 * parallel walking of the hash-list safe:
794 list_add_tail_rcu(&class->hash_entry, hash_head);
796 * Add it to the global list of classes:
798 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
800 if (verbose(class)) {
803 printk("\nnew class %p: %s", class->key, class->name);
804 if (class->name_version > 1)
805 printk("#%d", class->name_version);
817 if (!subclass || force)
818 lock->class_cache[0] = class;
819 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
820 lock->class_cache[subclass] = class;
823 * Hash collision, did we smoke some? We found a class with a matching
824 * hash but the subclass -- which is hashed in -- didn't match.
826 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
832 #ifdef CONFIG_PROVE_LOCKING
834 * Allocate a lockdep entry. (assumes the graph_lock held, returns
835 * with NULL on failure)
837 static struct lock_list *alloc_list_entry(void)
839 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
840 if (!debug_locks_off_graph_unlock())
843 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
847 return list_entries + nr_list_entries++;
851 * Add a new dependency to the head of the list:
853 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
854 struct list_head *head, unsigned long ip,
855 int distance, struct stack_trace *trace)
857 struct lock_list *entry;
859 * Lock not present yet - get a new dependency struct and
860 * add it to the list:
862 entry = alloc_list_entry();
867 entry->distance = distance;
868 entry->trace = *trace;
870 * Both allocation and removal are done under the graph lock; but
871 * iteration is under RCU-sched; see look_up_lock_class() and
872 * lockdep_free_key_range().
874 list_add_tail_rcu(&entry->entry, head);
880 * For good efficiency of modular, we use power of 2
882 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
883 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
886 * The circular_queue and helpers is used to implement the
887 * breadth-first search(BFS)algorithem, by which we can build
888 * the shortest path from the next lock to be acquired to the
889 * previous held lock if there is a circular between them.
891 struct circular_queue {
892 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
893 unsigned int front, rear;
896 static struct circular_queue lock_cq;
898 unsigned int max_bfs_queue_depth;
900 static unsigned int lockdep_dependency_gen_id;
902 static inline void __cq_init(struct circular_queue *cq)
904 cq->front = cq->rear = 0;
905 lockdep_dependency_gen_id++;
908 static inline int __cq_empty(struct circular_queue *cq)
910 return (cq->front == cq->rear);
913 static inline int __cq_full(struct circular_queue *cq)
915 return ((cq->rear + 1) & CQ_MASK) == cq->front;
918 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
923 cq->element[cq->rear] = elem;
924 cq->rear = (cq->rear + 1) & CQ_MASK;
928 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
933 *elem = cq->element[cq->front];
934 cq->front = (cq->front + 1) & CQ_MASK;
938 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
940 return (cq->rear - cq->front) & CQ_MASK;
943 static inline void mark_lock_accessed(struct lock_list *lock,
944 struct lock_list *parent)
948 nr = lock - list_entries;
949 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
950 lock->parent = parent;
951 lock->class->dep_gen_id = lockdep_dependency_gen_id;
954 static inline unsigned long lock_accessed(struct lock_list *lock)
958 nr = lock - list_entries;
959 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
960 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
963 static inline struct lock_list *get_lock_parent(struct lock_list *child)
965 return child->parent;
968 static inline int get_lock_depth(struct lock_list *child)
971 struct lock_list *parent;
973 while ((parent = get_lock_parent(child))) {
980 static int __bfs(struct lock_list *source_entry,
982 int (*match)(struct lock_list *entry, void *data),
983 struct lock_list **target_entry,
986 struct lock_list *entry;
987 struct list_head *head;
988 struct circular_queue *cq = &lock_cq;
991 if (match(source_entry, data)) {
992 *target_entry = source_entry;
998 head = &source_entry->class->locks_after;
1000 head = &source_entry->class->locks_before;
1002 if (list_empty(head))
1006 __cq_enqueue(cq, (unsigned long)source_entry);
1008 while (!__cq_empty(cq)) {
1009 struct lock_list *lock;
1011 __cq_dequeue(cq, (unsigned long *)&lock);
1019 head = &lock->class->locks_after;
1021 head = &lock->class->locks_before;
1023 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1025 list_for_each_entry_rcu(entry, head, entry) {
1026 if (!lock_accessed(entry)) {
1027 unsigned int cq_depth;
1028 mark_lock_accessed(entry, lock);
1029 if (match(entry, data)) {
1030 *target_entry = entry;
1035 if (__cq_enqueue(cq, (unsigned long)entry)) {
1039 cq_depth = __cq_get_elem_count(cq);
1040 if (max_bfs_queue_depth < cq_depth)
1041 max_bfs_queue_depth = cq_depth;
1049 static inline int __bfs_forwards(struct lock_list *src_entry,
1051 int (*match)(struct lock_list *entry, void *data),
1052 struct lock_list **target_entry)
1054 return __bfs(src_entry, data, match, target_entry, 1);
1058 static inline int __bfs_backwards(struct lock_list *src_entry,
1060 int (*match)(struct lock_list *entry, void *data),
1061 struct lock_list **target_entry)
1063 return __bfs(src_entry, data, match, target_entry, 0);
1068 * Recursive, forwards-direction lock-dependency checking, used for
1069 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1074 * Print a dependency chain entry (this is only done when a deadlock
1075 * has been detected):
1078 print_circular_bug_entry(struct lock_list *target, int depth)
1080 if (debug_locks_silent)
1082 printk("\n-> #%u", depth);
1083 print_lock_name(target->class);
1085 print_stack_trace(&target->trace, 6);
1091 print_circular_lock_scenario(struct held_lock *src,
1092 struct held_lock *tgt,
1093 struct lock_list *prt)
1095 struct lock_class *source = hlock_class(src);
1096 struct lock_class *target = hlock_class(tgt);
1097 struct lock_class *parent = prt->class;
1100 * A direct locking problem where unsafe_class lock is taken
1101 * directly by safe_class lock, then all we need to show
1102 * is the deadlock scenario, as it is obvious that the
1103 * unsafe lock is taken under the safe lock.
1105 * But if there is a chain instead, where the safe lock takes
1106 * an intermediate lock (middle_class) where this lock is
1107 * not the same as the safe lock, then the lock chain is
1108 * used to describe the problem. Otherwise we would need
1109 * to show a different CPU case for each link in the chain
1110 * from the safe_class lock to the unsafe_class lock.
1112 if (parent != source) {
1113 printk("Chain exists of:\n ");
1114 __print_lock_name(source);
1116 __print_lock_name(parent);
1118 __print_lock_name(target);
1122 printk(" Possible unsafe locking scenario:\n\n");
1123 printk(" CPU0 CPU1\n");
1124 printk(" ---- ----\n");
1126 __print_lock_name(target);
1129 __print_lock_name(parent);
1132 __print_lock_name(target);
1135 __print_lock_name(source);
1137 printk("\n *** DEADLOCK ***\n\n");
1141 * When a circular dependency is detected, print the
1145 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1146 struct held_lock *check_src,
1147 struct held_lock *check_tgt)
1149 struct task_struct *curr = current;
1151 if (debug_locks_silent)
1155 printk("======================================================\n");
1156 printk("[ INFO: possible circular locking dependency detected ]\n");
1157 print_kernel_ident();
1158 printk("-------------------------------------------------------\n");
1159 printk("%s/%d is trying to acquire lock:\n",
1160 curr->comm, task_pid_nr(curr));
1161 print_lock(check_src);
1162 printk("\nbut task is already holding lock:\n");
1163 print_lock(check_tgt);
1164 printk("\nwhich lock already depends on the new lock.\n\n");
1165 printk("\nthe existing dependency chain (in reverse order) is:\n");
1167 print_circular_bug_entry(entry, depth);
1172 static inline int class_equal(struct lock_list *entry, void *data)
1174 return entry->class == data;
1177 static noinline int print_circular_bug(struct lock_list *this,
1178 struct lock_list *target,
1179 struct held_lock *check_src,
1180 struct held_lock *check_tgt)
1182 struct task_struct *curr = current;
1183 struct lock_list *parent;
1184 struct lock_list *first_parent;
1187 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1190 if (!save_trace(&this->trace))
1193 depth = get_lock_depth(target);
1195 print_circular_bug_header(target, depth, check_src, check_tgt);
1197 parent = get_lock_parent(target);
1198 first_parent = parent;
1201 print_circular_bug_entry(parent, --depth);
1202 parent = get_lock_parent(parent);
1205 printk("\nother info that might help us debug this:\n\n");
1206 print_circular_lock_scenario(check_src, check_tgt,
1209 lockdep_print_held_locks(curr);
1211 printk("\nstack backtrace:\n");
1217 static noinline int print_bfs_bug(int ret)
1219 if (!debug_locks_off_graph_unlock())
1223 * Breadth-first-search failed, graph got corrupted?
1225 WARN(1, "lockdep bfs error:%d\n", ret);
1230 static int noop_count(struct lock_list *entry, void *data)
1232 (*(unsigned long *)data)++;
1236 static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1238 unsigned long count = 0;
1239 struct lock_list *uninitialized_var(target_entry);
1241 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1245 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1247 unsigned long ret, flags;
1248 struct lock_list this;
1253 local_irq_save(flags);
1254 arch_spin_lock(&lockdep_lock);
1255 ret = __lockdep_count_forward_deps(&this);
1256 arch_spin_unlock(&lockdep_lock);
1257 local_irq_restore(flags);
1262 static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1264 unsigned long count = 0;
1265 struct lock_list *uninitialized_var(target_entry);
1267 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1272 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1274 unsigned long ret, flags;
1275 struct lock_list this;
1280 local_irq_save(flags);
1281 arch_spin_lock(&lockdep_lock);
1282 ret = __lockdep_count_backward_deps(&this);
1283 arch_spin_unlock(&lockdep_lock);
1284 local_irq_restore(flags);
1290 * Prove that the dependency graph starting at <entry> can not
1291 * lead to <target>. Print an error and return 0 if it does.
1294 check_noncircular(struct lock_list *root, struct lock_class *target,
1295 struct lock_list **target_entry)
1299 debug_atomic_inc(nr_cyclic_checks);
1301 result = __bfs_forwards(root, target, class_equal, target_entry);
1306 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1308 * Forwards and backwards subgraph searching, for the purposes of
1309 * proving that two subgraphs can be connected by a new dependency
1310 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1313 static inline int usage_match(struct lock_list *entry, void *bit)
1315 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1321 * Find a node in the forwards-direction dependency sub-graph starting
1322 * at @root->class that matches @bit.
1324 * Return 0 if such a node exists in the subgraph, and put that node
1325 * into *@target_entry.
1327 * Return 1 otherwise and keep *@target_entry unchanged.
1328 * Return <0 on error.
1331 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1332 struct lock_list **target_entry)
1336 debug_atomic_inc(nr_find_usage_forwards_checks);
1338 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1344 * Find a node in the backwards-direction dependency sub-graph starting
1345 * at @root->class that matches @bit.
1347 * Return 0 if such a node exists in the subgraph, and put that node
1348 * into *@target_entry.
1350 * Return 1 otherwise and keep *@target_entry unchanged.
1351 * Return <0 on error.
1354 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1355 struct lock_list **target_entry)
1359 debug_atomic_inc(nr_find_usage_backwards_checks);
1361 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1366 static void print_lock_class_header(struct lock_class *class, int depth)
1370 printk("%*s->", depth, "");
1371 print_lock_name(class);
1372 printk(" ops: %lu", class->ops);
1375 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1376 if (class->usage_mask & (1 << bit)) {
1379 len += printk("%*s %s", depth, "", usage_str[bit]);
1380 len += printk(" at:\n");
1381 print_stack_trace(class->usage_traces + bit, len);
1384 printk("%*s }\n", depth, "");
1386 printk("%*s ... key at: ",depth,"");
1387 print_ip_sym((unsigned long)class->key);
1391 * printk the shortest lock dependencies from @start to @end in reverse order:
1394 print_shortest_lock_dependencies(struct lock_list *leaf,
1395 struct lock_list *root)
1397 struct lock_list *entry = leaf;
1400 /*compute depth from generated tree by BFS*/
1401 depth = get_lock_depth(leaf);
1404 print_lock_class_header(entry->class, depth);
1405 printk("%*s ... acquired at:\n", depth, "");
1406 print_stack_trace(&entry->trace, 2);
1409 if (depth == 0 && (entry != root)) {
1410 printk("lockdep:%s bad path found in chain graph\n", __func__);
1414 entry = get_lock_parent(entry);
1416 } while (entry && (depth >= 0));
1422 print_irq_lock_scenario(struct lock_list *safe_entry,
1423 struct lock_list *unsafe_entry,
1424 struct lock_class *prev_class,
1425 struct lock_class *next_class)
1427 struct lock_class *safe_class = safe_entry->class;
1428 struct lock_class *unsafe_class = unsafe_entry->class;
1429 struct lock_class *middle_class = prev_class;
1431 if (middle_class == safe_class)
1432 middle_class = next_class;
1435 * A direct locking problem where unsafe_class lock is taken
1436 * directly by safe_class lock, then all we need to show
1437 * is the deadlock scenario, as it is obvious that the
1438 * unsafe lock is taken under the safe lock.
1440 * But if there is a chain instead, where the safe lock takes
1441 * an intermediate lock (middle_class) where this lock is
1442 * not the same as the safe lock, then the lock chain is
1443 * used to describe the problem. Otherwise we would need
1444 * to show a different CPU case for each link in the chain
1445 * from the safe_class lock to the unsafe_class lock.
1447 if (middle_class != unsafe_class) {
1448 printk("Chain exists of:\n ");
1449 __print_lock_name(safe_class);
1451 __print_lock_name(middle_class);
1453 __print_lock_name(unsafe_class);
1457 printk(" Possible interrupt unsafe locking scenario:\n\n");
1458 printk(" CPU0 CPU1\n");
1459 printk(" ---- ----\n");
1461 __print_lock_name(unsafe_class);
1463 printk(" local_irq_disable();\n");
1465 __print_lock_name(safe_class);
1468 __print_lock_name(middle_class);
1470 printk(" <Interrupt>\n");
1472 __print_lock_name(safe_class);
1474 printk("\n *** DEADLOCK ***\n\n");
1478 print_bad_irq_dependency(struct task_struct *curr,
1479 struct lock_list *prev_root,
1480 struct lock_list *next_root,
1481 struct lock_list *backwards_entry,
1482 struct lock_list *forwards_entry,
1483 struct held_lock *prev,
1484 struct held_lock *next,
1485 enum lock_usage_bit bit1,
1486 enum lock_usage_bit bit2,
1487 const char *irqclass)
1489 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1493 printk("======================================================\n");
1494 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1495 irqclass, irqclass);
1496 print_kernel_ident();
1497 printk("------------------------------------------------------\n");
1498 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1499 curr->comm, task_pid_nr(curr),
1500 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1501 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1502 curr->hardirqs_enabled,
1503 curr->softirqs_enabled);
1506 printk("\nand this task is already holding:\n");
1508 printk("which would create a new lock dependency:\n");
1509 print_lock_name(hlock_class(prev));
1511 print_lock_name(hlock_class(next));
1514 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1516 print_lock_name(backwards_entry->class);
1517 printk("\n... which became %s-irq-safe at:\n", irqclass);
1519 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1521 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1522 print_lock_name(forwards_entry->class);
1523 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1526 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1528 printk("\nother info that might help us debug this:\n\n");
1529 print_irq_lock_scenario(backwards_entry, forwards_entry,
1530 hlock_class(prev), hlock_class(next));
1532 lockdep_print_held_locks(curr);
1534 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1535 printk(" and the holding lock:\n");
1536 if (!save_trace(&prev_root->trace))
1538 print_shortest_lock_dependencies(backwards_entry, prev_root);
1540 printk("\nthe dependencies between the lock to be acquired");
1541 printk(" and %s-irq-unsafe lock:\n", irqclass);
1542 if (!save_trace(&next_root->trace))
1544 print_shortest_lock_dependencies(forwards_entry, next_root);
1546 printk("\nstack backtrace:\n");
1553 check_usage(struct task_struct *curr, struct held_lock *prev,
1554 struct held_lock *next, enum lock_usage_bit bit_backwards,
1555 enum lock_usage_bit bit_forwards, const char *irqclass)
1558 struct lock_list this, that;
1559 struct lock_list *uninitialized_var(target_entry);
1560 struct lock_list *uninitialized_var(target_entry1);
1564 this.class = hlock_class(prev);
1565 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1567 return print_bfs_bug(ret);
1572 that.class = hlock_class(next);
1573 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1575 return print_bfs_bug(ret);
1579 return print_bad_irq_dependency(curr, &this, &that,
1580 target_entry, target_entry1,
1582 bit_backwards, bit_forwards, irqclass);
1585 static const char *state_names[] = {
1586 #define LOCKDEP_STATE(__STATE) \
1587 __stringify(__STATE),
1588 #include "lockdep_states.h"
1589 #undef LOCKDEP_STATE
1592 static const char *state_rnames[] = {
1593 #define LOCKDEP_STATE(__STATE) \
1594 __stringify(__STATE)"-READ",
1595 #include "lockdep_states.h"
1596 #undef LOCKDEP_STATE
1599 static inline const char *state_name(enum lock_usage_bit bit)
1601 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1604 static int exclusive_bit(int new_bit)
1612 * bit 0 - write/read
1613 * bit 1 - used_in/enabled
1617 int state = new_bit & ~3;
1618 int dir = new_bit & 2;
1621 * keep state, bit flip the direction and strip read.
1623 return state | (dir ^ 2);
1626 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1627 struct held_lock *next, enum lock_usage_bit bit)
1630 * Prove that the new dependency does not connect a hardirq-safe
1631 * lock with a hardirq-unsafe lock - to achieve this we search
1632 * the backwards-subgraph starting at <prev>, and the
1633 * forwards-subgraph starting at <next>:
1635 if (!check_usage(curr, prev, next, bit,
1636 exclusive_bit(bit), state_name(bit)))
1642 * Prove that the new dependency does not connect a hardirq-safe-read
1643 * lock with a hardirq-unsafe lock - to achieve this we search
1644 * the backwards-subgraph starting at <prev>, and the
1645 * forwards-subgraph starting at <next>:
1647 if (!check_usage(curr, prev, next, bit,
1648 exclusive_bit(bit), state_name(bit)))
1655 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1656 struct held_lock *next)
1658 #define LOCKDEP_STATE(__STATE) \
1659 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1661 #include "lockdep_states.h"
1662 #undef LOCKDEP_STATE
1667 static void inc_chains(void)
1669 if (current->hardirq_context)
1670 nr_hardirq_chains++;
1672 if (current->softirq_context)
1673 nr_softirq_chains++;
1675 nr_process_chains++;
1682 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1683 struct held_lock *next)
1688 static inline void inc_chains(void)
1690 nr_process_chains++;
1696 print_deadlock_scenario(struct held_lock *nxt,
1697 struct held_lock *prv)
1699 struct lock_class *next = hlock_class(nxt);
1700 struct lock_class *prev = hlock_class(prv);
1702 printk(" Possible unsafe locking scenario:\n\n");
1706 __print_lock_name(prev);
1709 __print_lock_name(next);
1711 printk("\n *** DEADLOCK ***\n\n");
1712 printk(" May be due to missing lock nesting notation\n\n");
1716 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1717 struct held_lock *next)
1719 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1723 printk("=============================================\n");
1724 printk("[ INFO: possible recursive locking detected ]\n");
1725 print_kernel_ident();
1726 printk("---------------------------------------------\n");
1727 printk("%s/%d is trying to acquire lock:\n",
1728 curr->comm, task_pid_nr(curr));
1730 printk("\nbut task is already holding lock:\n");
1733 printk("\nother info that might help us debug this:\n");
1734 print_deadlock_scenario(next, prev);
1735 lockdep_print_held_locks(curr);
1737 printk("\nstack backtrace:\n");
1744 * Check whether we are holding such a class already.
1746 * (Note that this has to be done separately, because the graph cannot
1747 * detect such classes of deadlocks.)
1749 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1752 check_deadlock(struct task_struct *curr, struct held_lock *next,
1753 struct lockdep_map *next_instance, int read)
1755 struct held_lock *prev;
1756 struct held_lock *nest = NULL;
1759 for (i = 0; i < curr->lockdep_depth; i++) {
1760 prev = curr->held_locks + i;
1762 if (prev->instance == next->nest_lock)
1765 if (hlock_class(prev) != hlock_class(next))
1769 * Allow read-after-read recursion of the same
1770 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1772 if ((read == 2) && prev->read)
1776 * We're holding the nest_lock, which serializes this lock's
1777 * nesting behaviour.
1782 return print_deadlock_bug(curr, prev, next);
1788 * There was a chain-cache miss, and we are about to add a new dependency
1789 * to a previous lock. We recursively validate the following rules:
1791 * - would the adding of the <prev> -> <next> dependency create a
1792 * circular dependency in the graph? [== circular deadlock]
1794 * - does the new prev->next dependency connect any hardirq-safe lock
1795 * (in the full backwards-subgraph starting at <prev>) with any
1796 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1797 * <next>)? [== illegal lock inversion with hardirq contexts]
1799 * - does the new prev->next dependency connect any softirq-safe lock
1800 * (in the full backwards-subgraph starting at <prev>) with any
1801 * softirq-unsafe lock (in the full forwards-subgraph starting at
1802 * <next>)? [== illegal lock inversion with softirq contexts]
1804 * any of these scenarios could lead to a deadlock.
1806 * Then if all the validations pass, we add the forwards and backwards
1810 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1811 struct held_lock *next, int distance, int trylock_loop)
1813 struct lock_list *entry;
1815 struct lock_list this;
1816 struct lock_list *uninitialized_var(target_entry);
1818 * Static variable, serialized by the graph_lock().
1820 * We use this static variable to save the stack trace in case
1821 * we call into this function multiple times due to encountering
1822 * trylocks in the held lock stack.
1824 static struct stack_trace trace;
1827 * Prove that the new <prev> -> <next> dependency would not
1828 * create a circular dependency in the graph. (We do this by
1829 * forward-recursing into the graph starting at <next>, and
1830 * checking whether we can reach <prev>.)
1832 * We are using global variables to control the recursion, to
1833 * keep the stackframe size of the recursive functions low:
1835 this.class = hlock_class(next);
1837 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1839 return print_circular_bug(&this, target_entry, next, prev);
1840 else if (unlikely(ret < 0))
1841 return print_bfs_bug(ret);
1843 if (!check_prev_add_irq(curr, prev, next))
1847 * For recursive read-locks we do all the dependency checks,
1848 * but we dont store read-triggered dependencies (only
1849 * write-triggered dependencies). This ensures that only the
1850 * write-side dependencies matter, and that if for example a
1851 * write-lock never takes any other locks, then the reads are
1852 * equivalent to a NOP.
1854 if (next->read == 2 || prev->read == 2)
1857 * Is the <prev> -> <next> dependency already present?
1859 * (this may occur even though this is a new chain: consider
1860 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1861 * chains - the second one will be new, but L1 already has
1862 * L2 added to its dependency list, due to the first chain.)
1864 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1865 if (entry->class == hlock_class(next)) {
1867 entry->distance = 1;
1872 if (!trylock_loop && !save_trace(&trace))
1876 * Ok, all validations passed, add the new lock
1877 * to the previous lock's dependency list:
1879 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1880 &hlock_class(prev)->locks_after,
1881 next->acquire_ip, distance, &trace);
1886 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1887 &hlock_class(next)->locks_before,
1888 next->acquire_ip, distance, &trace);
1893 * Debugging printouts:
1895 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1897 printk("\n new dependency: ");
1898 print_lock_name(hlock_class(prev));
1900 print_lock_name(hlock_class(next));
1903 return graph_lock();
1909 * Add the dependency to all directly-previous locks that are 'relevant'.
1910 * The ones that are relevant are (in increasing distance from curr):
1911 * all consecutive trylock entries and the final non-trylock entry - or
1912 * the end of this context's lock-chain - whichever comes first.
1915 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1917 int depth = curr->lockdep_depth;
1918 int trylock_loop = 0;
1919 struct held_lock *hlock;
1924 * Depth must not be zero for a non-head lock:
1929 * At least two relevant locks must exist for this
1932 if (curr->held_locks[depth].irq_context !=
1933 curr->held_locks[depth-1].irq_context)
1937 int distance = curr->lockdep_depth - depth + 1;
1938 hlock = curr->held_locks + depth - 1;
1940 * Only non-recursive-read entries get new dependencies
1943 if (hlock->read != 2 && hlock->check) {
1944 if (!check_prev_add(curr, hlock, next,
1945 distance, trylock_loop))
1948 * Stop after the first non-trylock entry,
1949 * as non-trylock entries have added their
1950 * own direct dependencies already, so this
1951 * lock is connected to them indirectly:
1953 if (!hlock->trylock)
1958 * End of lock-stack?
1963 * Stop the search if we cross into another context:
1965 if (curr->held_locks[depth].irq_context !=
1966 curr->held_locks[depth-1].irq_context)
1972 if (!debug_locks_off_graph_unlock())
1976 * Clearly we all shouldn't be here, but since we made it we
1977 * can reliable say we messed up our state. See the above two
1978 * gotos for reasons why we could possibly end up here.
1985 unsigned long nr_lock_chains;
1986 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1987 int nr_chain_hlocks;
1988 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1990 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1992 return lock_classes + chain_hlocks[chain->base + i];
1996 * Look up a dependency chain. If the key is not present yet then
1997 * add it and return 1 - in this case the new dependency chain is
1998 * validated. If the key is already hashed, return 0.
1999 * (On return with 1 graph_lock is held.)
2001 static inline int lookup_chain_cache(struct task_struct *curr,
2002 struct held_lock *hlock,
2005 struct lock_class *class = hlock_class(hlock);
2006 struct list_head *hash_head = chainhashentry(chain_key);
2007 struct lock_chain *chain;
2008 struct held_lock *hlock_curr;
2012 * We might need to take the graph lock, ensure we've got IRQs
2013 * disabled to make this an IRQ-safe lock.. for recursion reasons
2014 * lockdep won't complain about its own locking errors.
2016 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2019 * We can walk it lock-free, because entries only get added
2022 list_for_each_entry_rcu(chain, hash_head, entry) {
2023 if (chain->chain_key == chain_key) {
2025 debug_atomic_inc(chain_lookup_hits);
2026 if (very_verbose(class))
2027 printk("\nhash chain already cached, key: "
2028 "%016Lx tail class: [%p] %s\n",
2029 (unsigned long long)chain_key,
2030 class->key, class->name);
2034 if (very_verbose(class))
2035 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2036 (unsigned long long)chain_key, class->key, class->name);
2038 * Allocate a new chain entry from the static array, and add
2044 * We have to walk the chain again locked - to avoid duplicates:
2046 list_for_each_entry(chain, hash_head, entry) {
2047 if (chain->chain_key == chain_key) {
2052 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2053 if (!debug_locks_off_graph_unlock())
2056 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2060 chain = lock_chains + nr_lock_chains++;
2061 chain->chain_key = chain_key;
2062 chain->irq_context = hlock->irq_context;
2063 /* Find the first held_lock of current chain */
2064 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2065 hlock_curr = curr->held_locks + i;
2066 if (hlock_curr->irq_context != hlock->irq_context)
2070 chain->depth = curr->lockdep_depth + 1 - i;
2071 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2072 chain->base = nr_chain_hlocks;
2073 nr_chain_hlocks += chain->depth;
2074 for (j = 0; j < chain->depth - 1; j++, i++) {
2075 int lock_id = curr->held_locks[i].class_idx - 1;
2076 chain_hlocks[chain->base + j] = lock_id;
2078 chain_hlocks[chain->base + j] = class - lock_classes;
2080 list_add_tail_rcu(&chain->entry, hash_head);
2081 debug_atomic_inc(chain_lookup_misses);
2087 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2088 struct held_lock *hlock, int chain_head, u64 chain_key)
2091 * Trylock needs to maintain the stack of held locks, but it
2092 * does not add new dependencies, because trylock can be done
2095 * We look up the chain_key and do the O(N^2) check and update of
2096 * the dependencies only if this is a new dependency chain.
2097 * (If lookup_chain_cache() returns with 1 it acquires
2098 * graph_lock for us)
2100 if (!hlock->trylock && hlock->check &&
2101 lookup_chain_cache(curr, hlock, chain_key)) {
2103 * Check whether last held lock:
2105 * - is irq-safe, if this lock is irq-unsafe
2106 * - is softirq-safe, if this lock is hardirq-unsafe
2108 * And check whether the new lock's dependency graph
2109 * could lead back to the previous lock.
2111 * any of these scenarios could lead to a deadlock. If
2114 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2119 * Mark recursive read, as we jump over it when
2120 * building dependencies (just like we jump over
2126 * Add dependency only if this lock is not the head
2127 * of the chain, and if it's not a secondary read-lock:
2129 if (!chain_head && ret != 2)
2130 if (!check_prevs_add(curr, hlock))
2134 /* after lookup_chain_cache(): */
2135 if (unlikely(!debug_locks))
2141 static inline int validate_chain(struct task_struct *curr,
2142 struct lockdep_map *lock, struct held_lock *hlock,
2143 int chain_head, u64 chain_key)
2150 * We are building curr_chain_key incrementally, so double-check
2151 * it from scratch, to make sure that it's done correctly:
2153 static void check_chain_key(struct task_struct *curr)
2155 #ifdef CONFIG_DEBUG_LOCKDEP
2156 struct held_lock *hlock, *prev_hlock = NULL;
2160 for (i = 0; i < curr->lockdep_depth; i++) {
2161 hlock = curr->held_locks + i;
2162 if (chain_key != hlock->prev_chain_key) {
2165 * We got mighty confused, our chain keys don't match
2166 * with what we expect, someone trample on our task state?
2168 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2169 curr->lockdep_depth, i,
2170 (unsigned long long)chain_key,
2171 (unsigned long long)hlock->prev_chain_key);
2174 id = hlock->class_idx - 1;
2176 * Whoops ran out of static storage again?
2178 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2181 if (prev_hlock && (prev_hlock->irq_context !=
2182 hlock->irq_context))
2184 chain_key = iterate_chain_key(chain_key, id);
2187 if (chain_key != curr->curr_chain_key) {
2190 * More smoking hash instead of calculating it, damn see these
2191 * numbers float.. I bet that a pink elephant stepped on my memory.
2193 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2194 curr->lockdep_depth, i,
2195 (unsigned long long)chain_key,
2196 (unsigned long long)curr->curr_chain_key);
2202 print_usage_bug_scenario(struct held_lock *lock)
2204 struct lock_class *class = hlock_class(lock);
2206 printk(" Possible unsafe locking scenario:\n\n");
2210 __print_lock_name(class);
2212 printk(" <Interrupt>\n");
2214 __print_lock_name(class);
2216 printk("\n *** DEADLOCK ***\n\n");
2220 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2221 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2223 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2227 printk("=================================\n");
2228 printk("[ INFO: inconsistent lock state ]\n");
2229 print_kernel_ident();
2230 printk("---------------------------------\n");
2232 printk("inconsistent {%s} -> {%s} usage.\n",
2233 usage_str[prev_bit], usage_str[new_bit]);
2235 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2236 curr->comm, task_pid_nr(curr),
2237 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2238 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2239 trace_hardirqs_enabled(curr),
2240 trace_softirqs_enabled(curr));
2243 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2244 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2246 print_irqtrace_events(curr);
2247 printk("\nother info that might help us debug this:\n");
2248 print_usage_bug_scenario(this);
2250 lockdep_print_held_locks(curr);
2252 printk("\nstack backtrace:\n");
2259 * Print out an error if an invalid bit is set:
2262 valid_state(struct task_struct *curr, struct held_lock *this,
2263 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2265 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2266 return print_usage_bug(curr, this, bad_bit, new_bit);
2270 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2271 enum lock_usage_bit new_bit);
2273 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2276 * print irq inversion bug:
2279 print_irq_inversion_bug(struct task_struct *curr,
2280 struct lock_list *root, struct lock_list *other,
2281 struct held_lock *this, int forwards,
2282 const char *irqclass)
2284 struct lock_list *entry = other;
2285 struct lock_list *middle = NULL;
2288 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2292 printk("=========================================================\n");
2293 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2294 print_kernel_ident();
2295 printk("---------------------------------------------------------\n");
2296 printk("%s/%d just changed the state of lock:\n",
2297 curr->comm, task_pid_nr(curr));
2300 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2302 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2303 print_lock_name(other->class);
2304 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2306 printk("\nother info that might help us debug this:\n");
2308 /* Find a middle lock (if one exists) */
2309 depth = get_lock_depth(other);
2311 if (depth == 0 && (entry != root)) {
2312 printk("lockdep:%s bad path found in chain graph\n", __func__);
2316 entry = get_lock_parent(entry);
2318 } while (entry && entry != root && (depth >= 0));
2320 print_irq_lock_scenario(root, other,
2321 middle ? middle->class : root->class, other->class);
2323 print_irq_lock_scenario(other, root,
2324 middle ? middle->class : other->class, root->class);
2326 lockdep_print_held_locks(curr);
2328 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2329 if (!save_trace(&root->trace))
2331 print_shortest_lock_dependencies(other, root);
2333 printk("\nstack backtrace:\n");
2340 * Prove that in the forwards-direction subgraph starting at <this>
2341 * there is no lock matching <mask>:
2344 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2345 enum lock_usage_bit bit, const char *irqclass)
2348 struct lock_list root;
2349 struct lock_list *uninitialized_var(target_entry);
2352 root.class = hlock_class(this);
2353 ret = find_usage_forwards(&root, bit, &target_entry);
2355 return print_bfs_bug(ret);
2359 return print_irq_inversion_bug(curr, &root, target_entry,
2364 * Prove that in the backwards-direction subgraph starting at <this>
2365 * there is no lock matching <mask>:
2368 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2369 enum lock_usage_bit bit, const char *irqclass)
2372 struct lock_list root;
2373 struct lock_list *uninitialized_var(target_entry);
2376 root.class = hlock_class(this);
2377 ret = find_usage_backwards(&root, bit, &target_entry);
2379 return print_bfs_bug(ret);
2383 return print_irq_inversion_bug(curr, &root, target_entry,
2387 void print_irqtrace_events(struct task_struct *curr)
2389 printk("irq event stamp: %u\n", curr->irq_events);
2390 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2391 print_ip_sym(curr->hardirq_enable_ip);
2392 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2393 print_ip_sym(curr->hardirq_disable_ip);
2394 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2395 print_ip_sym(curr->softirq_enable_ip);
2396 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2397 print_ip_sym(curr->softirq_disable_ip);
2400 static int HARDIRQ_verbose(struct lock_class *class)
2403 return class_filter(class);
2408 static int SOFTIRQ_verbose(struct lock_class *class)
2411 return class_filter(class);
2416 static int RECLAIM_FS_verbose(struct lock_class *class)
2419 return class_filter(class);
2424 #define STRICT_READ_CHECKS 1
2426 static int (*state_verbose_f[])(struct lock_class *class) = {
2427 #define LOCKDEP_STATE(__STATE) \
2429 #include "lockdep_states.h"
2430 #undef LOCKDEP_STATE
2433 static inline int state_verbose(enum lock_usage_bit bit,
2434 struct lock_class *class)
2436 return state_verbose_f[bit >> 2](class);
2439 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2440 enum lock_usage_bit bit, const char *name);
2443 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2444 enum lock_usage_bit new_bit)
2446 int excl_bit = exclusive_bit(new_bit);
2447 int read = new_bit & 1;
2448 int dir = new_bit & 2;
2451 * mark USED_IN has to look forwards -- to ensure no dependency
2452 * has ENABLED state, which would allow recursion deadlocks.
2454 * mark ENABLED has to look backwards -- to ensure no dependee
2455 * has USED_IN state, which, again, would allow recursion deadlocks.
2457 check_usage_f usage = dir ?
2458 check_usage_backwards : check_usage_forwards;
2461 * Validate that this particular lock does not have conflicting
2464 if (!valid_state(curr, this, new_bit, excl_bit))
2468 * Validate that the lock dependencies don't have conflicting usage
2471 if ((!read || !dir || STRICT_READ_CHECKS) &&
2472 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2476 * Check for read in write conflicts
2479 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2482 if (STRICT_READ_CHECKS &&
2483 !usage(curr, this, excl_bit + 1,
2484 state_name(new_bit + 1)))
2488 if (state_verbose(new_bit, hlock_class(this)))
2495 #define LOCKDEP_STATE(__STATE) __STATE,
2496 #include "lockdep_states.h"
2497 #undef LOCKDEP_STATE
2501 * Mark all held locks with a usage bit:
2504 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2506 enum lock_usage_bit usage_bit;
2507 struct held_lock *hlock;
2510 for (i = 0; i < curr->lockdep_depth; i++) {
2511 hlock = curr->held_locks + i;
2513 usage_bit = 2 + (mark << 2); /* ENABLED */
2515 usage_bit += 1; /* READ */
2517 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2522 if (!mark_lock(curr, hlock, usage_bit))
2530 * Hardirqs will be enabled:
2532 static void __trace_hardirqs_on_caller(unsigned long ip)
2534 struct task_struct *curr = current;
2536 /* we'll do an OFF -> ON transition: */
2537 curr->hardirqs_enabled = 1;
2540 * We are going to turn hardirqs on, so set the
2541 * usage bit for all held locks:
2543 if (!mark_held_locks(curr, HARDIRQ))
2546 * If we have softirqs enabled, then set the usage
2547 * bit for all held locks. (disabled hardirqs prevented
2548 * this bit from being set before)
2550 if (curr->softirqs_enabled)
2551 if (!mark_held_locks(curr, SOFTIRQ))
2554 curr->hardirq_enable_ip = ip;
2555 curr->hardirq_enable_event = ++curr->irq_events;
2556 debug_atomic_inc(hardirqs_on_events);
2559 __visible void trace_hardirqs_on_caller(unsigned long ip)
2561 time_hardirqs_on(CALLER_ADDR0, ip);
2563 if (unlikely(!debug_locks || current->lockdep_recursion))
2566 if (unlikely(current->hardirqs_enabled)) {
2568 * Neither irq nor preemption are disabled here
2569 * so this is racy by nature but losing one hit
2570 * in a stat is not a big deal.
2572 __debug_atomic_inc(redundant_hardirqs_on);
2577 * We're enabling irqs and according to our state above irqs weren't
2578 * already enabled, yet we find the hardware thinks they are in fact
2579 * enabled.. someone messed up their IRQ state tracing.
2581 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2585 * See the fine text that goes along with this variable definition.
2587 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2591 * Can't allow enabling interrupts while in an interrupt handler,
2592 * that's general bad form and such. Recursion, limited stack etc..
2594 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2597 current->lockdep_recursion = 1;
2598 __trace_hardirqs_on_caller(ip);
2599 current->lockdep_recursion = 0;
2601 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2603 void trace_hardirqs_on(void)
2605 trace_hardirqs_on_caller(CALLER_ADDR0);
2607 EXPORT_SYMBOL(trace_hardirqs_on);
2610 * Hardirqs were disabled:
2612 __visible void trace_hardirqs_off_caller(unsigned long ip)
2614 struct task_struct *curr = current;
2616 time_hardirqs_off(CALLER_ADDR0, ip);
2618 if (unlikely(!debug_locks || current->lockdep_recursion))
2622 * So we're supposed to get called after you mask local IRQs, but for
2623 * some reason the hardware doesn't quite think you did a proper job.
2625 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2628 if (curr->hardirqs_enabled) {
2630 * We have done an ON -> OFF transition:
2632 curr->hardirqs_enabled = 0;
2633 curr->hardirq_disable_ip = ip;
2634 curr->hardirq_disable_event = ++curr->irq_events;
2635 debug_atomic_inc(hardirqs_off_events);
2637 debug_atomic_inc(redundant_hardirqs_off);
2639 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2641 void trace_hardirqs_off(void)
2643 trace_hardirqs_off_caller(CALLER_ADDR0);
2645 EXPORT_SYMBOL(trace_hardirqs_off);
2648 * Softirqs will be enabled:
2650 void trace_softirqs_on(unsigned long ip)
2652 struct task_struct *curr = current;
2654 if (unlikely(!debug_locks || current->lockdep_recursion))
2658 * We fancy IRQs being disabled here, see softirq.c, avoids
2659 * funny state and nesting things.
2661 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2664 if (curr->softirqs_enabled) {
2665 debug_atomic_inc(redundant_softirqs_on);
2669 current->lockdep_recursion = 1;
2671 * We'll do an OFF -> ON transition:
2673 curr->softirqs_enabled = 1;
2674 curr->softirq_enable_ip = ip;
2675 curr->softirq_enable_event = ++curr->irq_events;
2676 debug_atomic_inc(softirqs_on_events);
2678 * We are going to turn softirqs on, so set the
2679 * usage bit for all held locks, if hardirqs are
2682 if (curr->hardirqs_enabled)
2683 mark_held_locks(curr, SOFTIRQ);
2684 current->lockdep_recursion = 0;
2688 * Softirqs were disabled:
2690 void trace_softirqs_off(unsigned long ip)
2692 struct task_struct *curr = current;
2694 if (unlikely(!debug_locks || current->lockdep_recursion))
2698 * We fancy IRQs being disabled here, see softirq.c
2700 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2703 if (curr->softirqs_enabled) {
2705 * We have done an ON -> OFF transition:
2707 curr->softirqs_enabled = 0;
2708 curr->softirq_disable_ip = ip;
2709 curr->softirq_disable_event = ++curr->irq_events;
2710 debug_atomic_inc(softirqs_off_events);
2712 * Whoops, we wanted softirqs off, so why aren't they?
2714 DEBUG_LOCKS_WARN_ON(!softirq_count());
2716 debug_atomic_inc(redundant_softirqs_off);
2719 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2721 struct task_struct *curr = current;
2723 if (unlikely(!debug_locks))
2726 /* no reclaim without waiting on it */
2727 if (!(gfp_mask & __GFP_WAIT))
2730 /* this guy won't enter reclaim */
2731 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2734 /* We're only interested __GFP_FS allocations for now */
2735 if (!(gfp_mask & __GFP_FS))
2739 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2741 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2744 mark_held_locks(curr, RECLAIM_FS);
2747 static void check_flags(unsigned long flags);
2749 void lockdep_trace_alloc(gfp_t gfp_mask)
2751 unsigned long flags;
2753 if (unlikely(current->lockdep_recursion))
2756 raw_local_irq_save(flags);
2758 current->lockdep_recursion = 1;
2759 __lockdep_trace_alloc(gfp_mask, flags);
2760 current->lockdep_recursion = 0;
2761 raw_local_irq_restore(flags);
2764 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2767 * If non-trylock use in a hardirq or softirq context, then
2768 * mark the lock as used in these contexts:
2770 if (!hlock->trylock) {
2772 if (curr->hardirq_context)
2773 if (!mark_lock(curr, hlock,
2774 LOCK_USED_IN_HARDIRQ_READ))
2776 if (curr->softirq_context)
2777 if (!mark_lock(curr, hlock,
2778 LOCK_USED_IN_SOFTIRQ_READ))
2781 if (curr->hardirq_context)
2782 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2784 if (curr->softirq_context)
2785 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2789 if (!hlock->hardirqs_off) {
2791 if (!mark_lock(curr, hlock,
2792 LOCK_ENABLED_HARDIRQ_READ))
2794 if (curr->softirqs_enabled)
2795 if (!mark_lock(curr, hlock,
2796 LOCK_ENABLED_SOFTIRQ_READ))
2799 if (!mark_lock(curr, hlock,
2800 LOCK_ENABLED_HARDIRQ))
2802 if (curr->softirqs_enabled)
2803 if (!mark_lock(curr, hlock,
2804 LOCK_ENABLED_SOFTIRQ))
2810 * We reuse the irq context infrastructure more broadly as a general
2811 * context checking code. This tests GFP_FS recursion (a lock taken
2812 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2815 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2817 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2820 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2828 static int separate_irq_context(struct task_struct *curr,
2829 struct held_lock *hlock)
2831 unsigned int depth = curr->lockdep_depth;
2834 * Keep track of points where we cross into an interrupt context:
2836 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2837 curr->softirq_context;
2839 struct held_lock *prev_hlock;
2841 prev_hlock = curr->held_locks + depth-1;
2843 * If we cross into another context, reset the
2844 * hash key (this also prevents the checking and the
2845 * adding of the dependency to 'prev'):
2847 if (prev_hlock->irq_context != hlock->irq_context)
2853 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2856 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2857 enum lock_usage_bit new_bit)
2859 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2863 static inline int mark_irqflags(struct task_struct *curr,
2864 struct held_lock *hlock)
2869 static inline int separate_irq_context(struct task_struct *curr,
2870 struct held_lock *hlock)
2875 void lockdep_trace_alloc(gfp_t gfp_mask)
2879 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2882 * Mark a lock with a usage bit, and validate the state transition:
2884 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2885 enum lock_usage_bit new_bit)
2887 unsigned int new_mask = 1 << new_bit, ret = 1;
2890 * If already set then do not dirty the cacheline,
2891 * nor do any checks:
2893 if (likely(hlock_class(this)->usage_mask & new_mask))
2899 * Make sure we didn't race:
2901 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2906 hlock_class(this)->usage_mask |= new_mask;
2908 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2912 #define LOCKDEP_STATE(__STATE) \
2913 case LOCK_USED_IN_##__STATE: \
2914 case LOCK_USED_IN_##__STATE##_READ: \
2915 case LOCK_ENABLED_##__STATE: \
2916 case LOCK_ENABLED_##__STATE##_READ:
2917 #include "lockdep_states.h"
2918 #undef LOCKDEP_STATE
2919 ret = mark_lock_irq(curr, this, new_bit);
2924 debug_atomic_dec(nr_unused_locks);
2927 if (!debug_locks_off_graph_unlock())
2936 * We must printk outside of the graph_lock:
2939 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2941 print_irqtrace_events(curr);
2949 * Initialize a lock instance's lock-class mapping info:
2951 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2952 struct lock_class_key *key, int subclass)
2956 kmemcheck_mark_initialized(lock, sizeof(*lock));
2958 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2959 lock->class_cache[i] = NULL;
2961 #ifdef CONFIG_LOCK_STAT
2962 lock->cpu = raw_smp_processor_id();
2966 * Can't be having no nameless bastards around this place!
2968 if (DEBUG_LOCKS_WARN_ON(!name)) {
2969 lock->name = "NULL";
2976 * No key, no joy, we need to hash something.
2978 if (DEBUG_LOCKS_WARN_ON(!key))
2981 * Sanity check, the lock-class key must be persistent:
2983 if (!static_obj(key)) {
2984 printk("BUG: key %p not in .data!\n", key);
2986 * What it says above ^^^^^, I suggest you read it.
2988 DEBUG_LOCKS_WARN_ON(1);
2993 if (unlikely(!debug_locks))
2997 unsigned long flags;
2999 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3002 raw_local_irq_save(flags);
3003 current->lockdep_recursion = 1;
3004 register_lock_class(lock, subclass, 1);
3005 current->lockdep_recursion = 0;
3006 raw_local_irq_restore(flags);
3009 EXPORT_SYMBOL_GPL(lockdep_init_map);
3011 struct lock_class_key __lockdep_no_validate__;
3012 EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3015 print_lock_nested_lock_not_held(struct task_struct *curr,
3016 struct held_lock *hlock,
3019 if (!debug_locks_off())
3021 if (debug_locks_silent)
3025 printk("==================================\n");
3026 printk("[ BUG: Nested lock was not taken ]\n");
3027 print_kernel_ident();
3028 printk("----------------------------------\n");
3030 printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3033 printk("\nbut this task is not holding:\n");
3034 printk("%s\n", hlock->nest_lock->name);
3036 printk("\nstack backtrace:\n");
3039 printk("\nother info that might help us debug this:\n");
3040 lockdep_print_held_locks(curr);
3042 printk("\nstack backtrace:\n");
3048 static int __lock_is_held(struct lockdep_map *lock);
3051 * This gets called for every mutex_lock*()/spin_lock*() operation.
3052 * We maintain the dependency maps and validate the locking attempt:
3054 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3055 int trylock, int read, int check, int hardirqs_off,
3056 struct lockdep_map *nest_lock, unsigned long ip,
3059 struct task_struct *curr = current;
3060 struct lock_class *class = NULL;
3061 struct held_lock *hlock;
3062 unsigned int depth, id;
3067 if (unlikely(!debug_locks))
3071 * Lockdep should run with IRQs disabled, otherwise we could
3072 * get an interrupt which would want to take locks, which would
3073 * end up in lockdep and have you got a head-ache already?
3075 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3078 if (!prove_locking || lock->key == &__lockdep_no_validate__)
3081 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3082 class = lock->class_cache[subclass];
3086 if (unlikely(!class)) {
3087 class = register_lock_class(lock, subclass, 0);
3091 atomic_inc((atomic_t *)&class->ops);
3092 if (very_verbose(class)) {
3093 printk("\nacquire class [%p] %s", class->key, class->name);
3094 if (class->name_version > 1)
3095 printk("#%d", class->name_version);
3101 * Add the lock to the list of currently held locks.
3102 * (we dont increase the depth just yet, up until the
3103 * dependency checks are done)
3105 depth = curr->lockdep_depth;
3107 * Ran out of static storage for our per-task lock stack again have we?
3109 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3112 class_idx = class - lock_classes + 1;
3115 hlock = curr->held_locks + depth - 1;
3116 if (hlock->class_idx == class_idx && nest_lock) {
3117 if (hlock->references)
3118 hlock->references++;
3120 hlock->references = 2;
3126 hlock = curr->held_locks + depth;
3128 * Plain impossible, we just registered it and checked it weren't no
3129 * NULL like.. I bet this mushroom I ate was good!
3131 if (DEBUG_LOCKS_WARN_ON(!class))
3133 hlock->class_idx = class_idx;
3134 hlock->acquire_ip = ip;
3135 hlock->instance = lock;
3136 hlock->nest_lock = nest_lock;
3137 hlock->trylock = trylock;
3139 hlock->check = check;
3140 hlock->hardirqs_off = !!hardirqs_off;
3141 hlock->references = references;
3142 #ifdef CONFIG_LOCK_STAT
3143 hlock->waittime_stamp = 0;
3144 hlock->holdtime_stamp = lockstat_clock();
3147 if (check && !mark_irqflags(curr, hlock))
3150 /* mark it as used: */
3151 if (!mark_lock(curr, hlock, LOCK_USED))
3155 * Calculate the chain hash: it's the combined hash of all the
3156 * lock keys along the dependency chain. We save the hash value
3157 * at every step so that we can get the current hash easily
3158 * after unlock. The chain hash is then used to cache dependency
3161 * The 'key ID' is what is the most compact key value to drive
3162 * the hash, not class->key.
3164 id = class - lock_classes;
3166 * Whoops, we did it again.. ran straight out of our static allocation.
3168 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3171 chain_key = curr->curr_chain_key;
3174 * How can we have a chain hash when we ain't got no keys?!
3176 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3181 hlock->prev_chain_key = chain_key;
3182 if (separate_irq_context(curr, hlock)) {
3186 chain_key = iterate_chain_key(chain_key, id);
3188 if (nest_lock && !__lock_is_held(nest_lock))
3189 return print_lock_nested_lock_not_held(curr, hlock, ip);
3191 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3194 curr->curr_chain_key = chain_key;
3195 curr->lockdep_depth++;
3196 check_chain_key(curr);
3197 #ifdef CONFIG_DEBUG_LOCKDEP
3198 if (unlikely(!debug_locks))
3201 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3203 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3204 printk(KERN_DEBUG "depth: %i max: %lu!\n",
3205 curr->lockdep_depth, MAX_LOCK_DEPTH);
3207 lockdep_print_held_locks(current);
3208 debug_show_all_locks();
3214 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3215 max_lockdep_depth = curr->lockdep_depth;
3221 print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3224 if (!debug_locks_off())
3226 if (debug_locks_silent)
3230 printk("=====================================\n");
3231 printk("[ BUG: bad unlock balance detected! ]\n");
3232 print_kernel_ident();
3233 printk("-------------------------------------\n");
3234 printk("%s/%d is trying to release lock (",
3235 curr->comm, task_pid_nr(curr));
3236 print_lockdep_cache(lock);
3239 printk("but there are no more locks to release!\n");
3240 printk("\nother info that might help us debug this:\n");
3241 lockdep_print_held_locks(curr);
3243 printk("\nstack backtrace:\n");
3250 * Common debugging checks for both nested and non-nested unlock:
3252 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3255 if (unlikely(!debug_locks))
3258 * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
3260 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3263 if (curr->lockdep_depth <= 0)
3264 return print_unlock_imbalance_bug(curr, lock, ip);
3269 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3271 if (hlock->instance == lock)
3274 if (hlock->references) {
3275 struct lock_class *class = lock->class_cache[0];
3278 class = look_up_lock_class(lock, 0);
3281 * If look_up_lock_class() failed to find a class, we're trying
3282 * to test if we hold a lock that has never yet been acquired.
3283 * Clearly if the lock hasn't been acquired _ever_, we're not
3284 * holding it either, so report failure.
3290 * References, but not a lock we're actually ref-counting?
3291 * State got messed up, follow the sites that change ->references
3292 * and try to make sense of it.
3294 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3297 if (hlock->class_idx == class - lock_classes + 1)
3305 __lock_set_class(struct lockdep_map *lock, const char *name,
3306 struct lock_class_key *key, unsigned int subclass,
3309 struct task_struct *curr = current;
3310 struct held_lock *hlock, *prev_hlock;
3311 struct lock_class *class;
3315 depth = curr->lockdep_depth;
3317 * This function is about (re)setting the class of a held lock,
3318 * yet we're not actually holding any locks. Naughty user!
3320 if (DEBUG_LOCKS_WARN_ON(!depth))
3324 for (i = depth-1; i >= 0; i--) {
3325 hlock = curr->held_locks + i;
3327 * We must not cross into another context:
3329 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3331 if (match_held_lock(hlock, lock))
3335 return print_unlock_imbalance_bug(curr, lock, ip);
3338 lockdep_init_map(lock, name, key, 0);
3339 class = register_lock_class(lock, subclass, 0);
3340 hlock->class_idx = class - lock_classes + 1;
3342 curr->lockdep_depth = i;
3343 curr->curr_chain_key = hlock->prev_chain_key;
3345 for (; i < depth; i++) {
3346 hlock = curr->held_locks + i;
3347 if (!__lock_acquire(hlock->instance,
3348 hlock_class(hlock)->subclass, hlock->trylock,
3349 hlock->read, hlock->check, hlock->hardirqs_off,
3350 hlock->nest_lock, hlock->acquire_ip,
3356 * I took it apart and put it back together again, except now I have
3357 * these 'spare' parts.. where shall I put them.
3359 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3365 * Remove the lock to the list of currently held locks in a
3366 * potentially non-nested (out of order) manner. This is a
3367 * relatively rare operation, as all the unlock APIs default
3368 * to nested mode (which uses lock_release()):
3371 lock_release_non_nested(struct task_struct *curr,
3372 struct lockdep_map *lock, unsigned long ip)
3374 struct held_lock *hlock, *prev_hlock;
3379 * Check whether the lock exists in the current stack
3382 depth = curr->lockdep_depth;
3384 * So we're all set to release this lock.. wait what lock? We don't
3385 * own any locks, you've been drinking again?
3387 if (DEBUG_LOCKS_WARN_ON(!depth))
3391 for (i = depth-1; i >= 0; i--) {
3392 hlock = curr->held_locks + i;
3394 * We must not cross into another context:
3396 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3398 if (match_held_lock(hlock, lock))
3402 return print_unlock_imbalance_bug(curr, lock, ip);
3405 if (hlock->instance == lock)
3406 lock_release_holdtime(hlock);
3408 if (hlock->references) {
3409 hlock->references--;
3410 if (hlock->references) {
3412 * We had, and after removing one, still have
3413 * references, the current lock stack is still
3414 * valid. We're done!
3421 * We have the right lock to unlock, 'hlock' points to it.
3422 * Now we remove it from the stack, and add back the other
3423 * entries (if any), recalculating the hash along the way:
3426 curr->lockdep_depth = i;
3427 curr->curr_chain_key = hlock->prev_chain_key;
3429 for (i++; i < depth; i++) {
3430 hlock = curr->held_locks + i;
3431 if (!__lock_acquire(hlock->instance,
3432 hlock_class(hlock)->subclass, hlock->trylock,
3433 hlock->read, hlock->check, hlock->hardirqs_off,
3434 hlock->nest_lock, hlock->acquire_ip,
3440 * We had N bottles of beer on the wall, we drank one, but now
3441 * there's not N-1 bottles of beer left on the wall...
3443 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3449 * Remove the lock to the list of currently held locks - this gets
3450 * called on mutex_unlock()/spin_unlock*() (or on a failed
3451 * mutex_lock_interruptible()). This is done for unlocks that nest
3452 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3454 static int lock_release_nested(struct task_struct *curr,
3455 struct lockdep_map *lock, unsigned long ip)
3457 struct held_lock *hlock;
3461 * Pop off the top of the lock stack:
3463 depth = curr->lockdep_depth - 1;
3464 hlock = curr->held_locks + depth;
3467 * Is the unlock non-nested:
3469 if (hlock->instance != lock || hlock->references)
3470 return lock_release_non_nested(curr, lock, ip);
3471 curr->lockdep_depth--;
3474 * No more locks, but somehow we've got hash left over, who left it?
3476 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3479 curr->curr_chain_key = hlock->prev_chain_key;
3481 lock_release_holdtime(hlock);
3483 #ifdef CONFIG_DEBUG_LOCKDEP
3484 hlock->prev_chain_key = 0;
3485 hlock->class_idx = 0;
3486 hlock->acquire_ip = 0;
3487 hlock->irq_context = 0;
3493 * Remove the lock to the list of currently held locks - this gets
3494 * called on mutex_unlock()/spin_unlock*() (or on a failed
3495 * mutex_lock_interruptible()). This is done for unlocks that nest
3496 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3499 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3501 struct task_struct *curr = current;
3503 if (!check_unlock(curr, lock, ip))
3507 if (!lock_release_nested(curr, lock, ip))
3510 if (!lock_release_non_nested(curr, lock, ip))
3514 check_chain_key(curr);
3517 static int __lock_is_held(struct lockdep_map *lock)
3519 struct task_struct *curr = current;
3522 for (i = 0; i < curr->lockdep_depth; i++) {
3523 struct held_lock *hlock = curr->held_locks + i;
3525 if (match_held_lock(hlock, lock))
3533 * Check whether we follow the irq-flags state precisely:
3535 static void check_flags(unsigned long flags)
3537 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3538 defined(CONFIG_TRACE_IRQFLAGS)
3542 if (irqs_disabled_flags(flags)) {
3543 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3544 printk("possible reason: unannotated irqs-off.\n");
3547 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3548 printk("possible reason: unannotated irqs-on.\n");
3553 * We dont accurately track softirq state in e.g.
3554 * hardirq contexts (such as on 4KSTACKS), so only
3555 * check if not in hardirq contexts:
3557 if (!hardirq_count()) {
3558 if (softirq_count()) {
3559 /* like the above, but with softirqs */
3560 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3562 /* lick the above, does it taste good? */
3563 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3568 print_irqtrace_events(current);
3572 void lock_set_class(struct lockdep_map *lock, const char *name,
3573 struct lock_class_key *key, unsigned int subclass,
3576 unsigned long flags;
3578 if (unlikely(current->lockdep_recursion))
3581 raw_local_irq_save(flags);
3582 current->lockdep_recursion = 1;
3584 if (__lock_set_class(lock, name, key, subclass, ip))
3585 check_chain_key(current);
3586 current->lockdep_recursion = 0;
3587 raw_local_irq_restore(flags);
3589 EXPORT_SYMBOL_GPL(lock_set_class);
3592 * We are not always called with irqs disabled - do that here,
3593 * and also avoid lockdep recursion:
3595 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3596 int trylock, int read, int check,
3597 struct lockdep_map *nest_lock, unsigned long ip)
3599 unsigned long flags;
3601 if (unlikely(current->lockdep_recursion))
3604 raw_local_irq_save(flags);
3607 current->lockdep_recursion = 1;
3608 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3609 __lock_acquire(lock, subclass, trylock, read, check,
3610 irqs_disabled_flags(flags), nest_lock, ip, 0);
3611 current->lockdep_recursion = 0;
3612 raw_local_irq_restore(flags);
3614 EXPORT_SYMBOL_GPL(lock_acquire);
3616 void lock_release(struct lockdep_map *lock, int nested,
3619 unsigned long flags;
3621 if (unlikely(current->lockdep_recursion))
3624 raw_local_irq_save(flags);
3626 current->lockdep_recursion = 1;
3627 trace_lock_release(lock, ip);
3628 __lock_release(lock, nested, ip);
3629 current->lockdep_recursion = 0;
3630 raw_local_irq_restore(flags);
3632 EXPORT_SYMBOL_GPL(lock_release);
3634 int lock_is_held(struct lockdep_map *lock)
3636 unsigned long flags;
3639 if (unlikely(current->lockdep_recursion))
3640 return 1; /* avoid false negative lockdep_assert_held() */
3642 raw_local_irq_save(flags);
3645 current->lockdep_recursion = 1;
3646 ret = __lock_is_held(lock);
3647 current->lockdep_recursion = 0;
3648 raw_local_irq_restore(flags);
3652 EXPORT_SYMBOL_GPL(lock_is_held);
3654 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3656 current->lockdep_reclaim_gfp = gfp_mask;
3659 void lockdep_clear_current_reclaim_state(void)
3661 current->lockdep_reclaim_gfp = 0;
3664 #ifdef CONFIG_LOCK_STAT
3666 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3669 if (!debug_locks_off())
3671 if (debug_locks_silent)
3675 printk("=================================\n");
3676 printk("[ BUG: bad contention detected! ]\n");
3677 print_kernel_ident();
3678 printk("---------------------------------\n");
3679 printk("%s/%d is trying to contend lock (",
3680 curr->comm, task_pid_nr(curr));
3681 print_lockdep_cache(lock);
3684 printk("but there are no locks held!\n");
3685 printk("\nother info that might help us debug this:\n");
3686 lockdep_print_held_locks(curr);
3688 printk("\nstack backtrace:\n");
3695 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3697 struct task_struct *curr = current;
3698 struct held_lock *hlock, *prev_hlock;
3699 struct lock_class_stats *stats;
3701 int i, contention_point, contending_point;
3703 depth = curr->lockdep_depth;
3705 * Whee, we contended on this lock, except it seems we're not
3706 * actually trying to acquire anything much at all..
3708 if (DEBUG_LOCKS_WARN_ON(!depth))
3712 for (i = depth-1; i >= 0; i--) {
3713 hlock = curr->held_locks + i;
3715 * We must not cross into another context:
3717 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3719 if (match_held_lock(hlock, lock))
3723 print_lock_contention_bug(curr, lock, ip);
3727 if (hlock->instance != lock)
3730 hlock->waittime_stamp = lockstat_clock();
3732 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3733 contending_point = lock_point(hlock_class(hlock)->contending_point,
3736 stats = get_lock_stats(hlock_class(hlock));
3737 if (contention_point < LOCKSTAT_POINTS)
3738 stats->contention_point[contention_point]++;
3739 if (contending_point < LOCKSTAT_POINTS)
3740 stats->contending_point[contending_point]++;
3741 if (lock->cpu != smp_processor_id())
3742 stats->bounces[bounce_contended + !!hlock->read]++;
3743 put_lock_stats(stats);
3747 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3749 struct task_struct *curr = current;
3750 struct held_lock *hlock, *prev_hlock;
3751 struct lock_class_stats *stats;
3753 u64 now, waittime = 0;
3756 depth = curr->lockdep_depth;
3758 * Yay, we acquired ownership of this lock we didn't try to
3759 * acquire, how the heck did that happen?
3761 if (DEBUG_LOCKS_WARN_ON(!depth))
3765 for (i = depth-1; i >= 0; i--) {
3766 hlock = curr->held_locks + i;
3768 * We must not cross into another context:
3770 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3772 if (match_held_lock(hlock, lock))
3776 print_lock_contention_bug(curr, lock, _RET_IP_);
3780 if (hlock->instance != lock)
3783 cpu = smp_processor_id();
3784 if (hlock->waittime_stamp) {
3785 now = lockstat_clock();
3786 waittime = now - hlock->waittime_stamp;
3787 hlock->holdtime_stamp = now;
3790 trace_lock_acquired(lock, ip);
3792 stats = get_lock_stats(hlock_class(hlock));
3795 lock_time_inc(&stats->read_waittime, waittime);
3797 lock_time_inc(&stats->write_waittime, waittime);
3799 if (lock->cpu != cpu)
3800 stats->bounces[bounce_acquired + !!hlock->read]++;
3801 put_lock_stats(stats);
3807 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3809 unsigned long flags;
3811 if (unlikely(!lock_stat))
3814 if (unlikely(current->lockdep_recursion))
3817 raw_local_irq_save(flags);
3819 current->lockdep_recursion = 1;
3820 trace_lock_contended(lock, ip);
3821 __lock_contended(lock, ip);
3822 current->lockdep_recursion = 0;
3823 raw_local_irq_restore(flags);
3825 EXPORT_SYMBOL_GPL(lock_contended);
3827 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3829 unsigned long flags;
3831 if (unlikely(!lock_stat))
3834 if (unlikely(current->lockdep_recursion))
3837 raw_local_irq_save(flags);
3839 current->lockdep_recursion = 1;
3840 __lock_acquired(lock, ip);
3841 current->lockdep_recursion = 0;
3842 raw_local_irq_restore(flags);
3844 EXPORT_SYMBOL_GPL(lock_acquired);
3848 * Used by the testsuite, sanitize the validator state
3849 * after a simulated failure:
3852 void lockdep_reset(void)
3854 unsigned long flags;
3857 raw_local_irq_save(flags);
3858 current->curr_chain_key = 0;
3859 current->lockdep_depth = 0;
3860 current->lockdep_recursion = 0;
3861 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3862 nr_hardirq_chains = 0;
3863 nr_softirq_chains = 0;
3864 nr_process_chains = 0;
3866 for (i = 0; i < CHAINHASH_SIZE; i++)
3867 INIT_LIST_HEAD(chainhash_table + i);
3868 raw_local_irq_restore(flags);
3871 static void zap_class(struct lock_class *class)
3876 * Remove all dependencies this lock is
3879 for (i = 0; i < nr_list_entries; i++) {
3880 if (list_entries[i].class == class)
3881 list_del_rcu(&list_entries[i].entry);
3884 * Unhash the class and remove it from the all_lock_classes list:
3886 list_del_rcu(&class->hash_entry);
3887 list_del_rcu(&class->lock_entry);
3892 static inline int within(const void *addr, void *start, unsigned long size)
3894 return addr >= start && addr < start + size;
3898 * Used in module.c to remove lock classes from memory that is going to be
3899 * freed; and possibly re-used by other modules.
3901 * We will have had one sync_sched() before getting here, so we're guaranteed
3902 * nobody will look up these exact classes -- they're properly dead but still
3905 void lockdep_free_key_range(void *start, unsigned long size)
3907 struct lock_class *class;
3908 struct list_head *head;
3909 unsigned long flags;
3913 raw_local_irq_save(flags);
3914 locked = graph_lock();
3917 * Unhash all classes that were created by this module:
3919 for (i = 0; i < CLASSHASH_SIZE; i++) {
3920 head = classhash_table + i;
3921 if (list_empty(head))
3923 list_for_each_entry_rcu(class, head, hash_entry) {
3924 if (within(class->key, start, size))
3926 else if (within(class->name, start, size))
3933 raw_local_irq_restore(flags);
3936 * Wait for any possible iterators from look_up_lock_class() to pass
3937 * before continuing to free the memory they refer to.
3939 * sync_sched() is sufficient because the read-side is IRQ disable.
3941 synchronize_sched();
3944 * XXX at this point we could return the resources to the pool;
3945 * instead we leak them. We would need to change to bitmap allocators
3946 * instead of the linear allocators we have now.
3950 void lockdep_reset_lock(struct lockdep_map *lock)
3952 struct lock_class *class;
3953 struct list_head *head;
3954 unsigned long flags;
3958 raw_local_irq_save(flags);
3961 * Remove all classes this lock might have:
3963 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3965 * If the class exists we look it up and zap it:
3967 class = look_up_lock_class(lock, j);
3972 * Debug check: in the end all mapped classes should
3975 locked = graph_lock();
3976 for (i = 0; i < CLASSHASH_SIZE; i++) {
3977 head = classhash_table + i;
3978 if (list_empty(head))
3980 list_for_each_entry_rcu(class, head, hash_entry) {
3983 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3984 match |= class == lock->class_cache[j];
3986 if (unlikely(match)) {
3987 if (debug_locks_off_graph_unlock()) {
3989 * We all just reset everything, how did it match?
4001 raw_local_irq_restore(flags);
4004 void lockdep_init(void)
4009 * Some architectures have their own start_kernel()
4010 * code which calls lockdep_init(), while we also
4011 * call lockdep_init() from the start_kernel() itself,
4012 * and we want to initialize the hashes only once:
4014 if (lockdep_initialized)
4017 for (i = 0; i < CLASSHASH_SIZE; i++)
4018 INIT_LIST_HEAD(classhash_table + i);
4020 for (i = 0; i < CHAINHASH_SIZE; i++)
4021 INIT_LIST_HEAD(chainhash_table + i);
4023 lockdep_initialized = 1;
4026 void __init lockdep_info(void)
4028 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4030 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
4031 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
4032 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
4033 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
4034 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
4035 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
4036 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
4038 printk(" memory used by lock dependency info: %lu kB\n",
4039 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4040 sizeof(struct list_head) * CLASSHASH_SIZE +
4041 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4042 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4043 sizeof(struct list_head) * CHAINHASH_SIZE
4044 #ifdef CONFIG_PROVE_LOCKING
4045 + sizeof(struct circular_queue)
4050 printk(" per task-struct memory footprint: %lu bytes\n",
4051 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4053 #ifdef CONFIG_DEBUG_LOCKDEP
4054 if (lockdep_init_error) {
4055 printk("WARNING: lockdep init error! lock-%s was acquired"
4056 "before lockdep_init\n", lock_init_error);
4057 printk("Call stack leading to lockdep invocation was:\n");
4058 print_stack_trace(&lockdep_init_trace, 0);
4064 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4065 const void *mem_to, struct held_lock *hlock)
4067 if (!debug_locks_off())
4069 if (debug_locks_silent)
4073 printk("=========================\n");
4074 printk("[ BUG: held lock freed! ]\n");
4075 print_kernel_ident();
4076 printk("-------------------------\n");
4077 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4078 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4080 lockdep_print_held_locks(curr);
4082 printk("\nstack backtrace:\n");
4086 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4087 const void* lock_from, unsigned long lock_len)
4089 return lock_from + lock_len <= mem_from ||
4090 mem_from + mem_len <= lock_from;
4094 * Called when kernel memory is freed (or unmapped), or if a lock
4095 * is destroyed or reinitialized - this code checks whether there is
4096 * any held lock in the memory range of <from> to <to>:
4098 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4100 struct task_struct *curr = current;
4101 struct held_lock *hlock;
4102 unsigned long flags;
4105 if (unlikely(!debug_locks))
4108 local_irq_save(flags);
4109 for (i = 0; i < curr->lockdep_depth; i++) {
4110 hlock = curr->held_locks + i;
4112 if (not_in_range(mem_from, mem_len, hlock->instance,
4113 sizeof(*hlock->instance)))
4116 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4119 local_irq_restore(flags);
4121 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4123 static void print_held_locks_bug(void)
4125 if (!debug_locks_off())
4127 if (debug_locks_silent)
4131 printk("=====================================\n");
4132 printk("[ BUG: %s/%d still has locks held! ]\n",
4133 current->comm, task_pid_nr(current));
4134 print_kernel_ident();
4135 printk("-------------------------------------\n");
4136 lockdep_print_held_locks(current);
4137 printk("\nstack backtrace:\n");
4141 void debug_check_no_locks_held(void)
4143 if (unlikely(current->lockdep_depth > 0))
4144 print_held_locks_bug();
4146 EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
4149 void debug_show_all_locks(void)
4151 struct task_struct *g, *p;
4155 if (unlikely(!debug_locks)) {
4156 printk("INFO: lockdep is turned off.\n");
4159 printk("\nShowing all locks held in the system:\n");
4162 * Here we try to get the tasklist_lock as hard as possible,
4163 * if not successful after 2 seconds we ignore it (but keep
4164 * trying). This is to enable a debug printout even if a
4165 * tasklist_lock-holding task deadlocks or crashes.
4168 if (!read_trylock(&tasklist_lock)) {
4170 printk("hm, tasklist_lock locked, retrying... ");
4173 printk(" #%d", 10-count);
4177 printk(" ignoring it.\n");
4181 printk(KERN_CONT " locked it.\n");
4184 do_each_thread(g, p) {
4186 * It's not reliable to print a task's held locks
4187 * if it's not sleeping (or if it's not the current
4190 if (p->state == TASK_RUNNING && p != current)
4192 if (p->lockdep_depth)
4193 lockdep_print_held_locks(p);
4195 if (read_trylock(&tasklist_lock))
4197 } while_each_thread(g, p);
4200 printk("=============================================\n\n");
4203 read_unlock(&tasklist_lock);
4205 EXPORT_SYMBOL_GPL(debug_show_all_locks);
4209 * Careful: only use this function if you are sure that
4210 * the task cannot run in parallel!
4212 void debug_show_held_locks(struct task_struct *task)
4214 if (unlikely(!debug_locks)) {
4215 printk("INFO: lockdep is turned off.\n");
4218 lockdep_print_held_locks(task);
4220 EXPORT_SYMBOL_GPL(debug_show_held_locks);
4222 asmlinkage __visible void lockdep_sys_exit(void)
4224 struct task_struct *curr = current;
4226 if (unlikely(curr->lockdep_depth)) {
4227 if (!debug_locks_off())
4230 printk("================================================\n");
4231 printk("[ BUG: lock held when returning to user space! ]\n");
4232 print_kernel_ident();
4233 printk("------------------------------------------------\n");
4234 printk("%s/%d is leaving the kernel with locks still held!\n",
4235 curr->comm, curr->pid);
4236 lockdep_print_held_locks(curr);
4240 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4242 struct task_struct *curr = current;
4244 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4245 if (!debug_locks_off())
4247 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4248 /* Note: the following can be executed concurrently, so be careful. */
4250 printk("===============================\n");
4251 printk("[ INFO: suspicious RCU usage. ]\n");
4252 print_kernel_ident();
4253 printk("-------------------------------\n");
4254 printk("%s:%d %s!\n", file, line, s);
4255 printk("\nother info that might help us debug this:\n\n");
4256 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4257 !rcu_lockdep_current_cpu_online()
4258 ? "RCU used illegally from offline CPU!\n"
4259 : !rcu_is_watching()
4260 ? "RCU used illegally from idle CPU!\n"
4262 rcu_scheduler_active, debug_locks);
4265 * If a CPU is in the RCU-free window in idle (ie: in the section
4266 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4267 * considers that CPU to be in an "extended quiescent state",
4268 * which means that RCU will be completely ignoring that CPU.
4269 * Therefore, rcu_read_lock() and friends have absolutely no
4270 * effect on a CPU running in that state. In other words, even if
4271 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4272 * delete data structures out from under it. RCU really has no
4273 * choice here: we need to keep an RCU-free window in idle where
4274 * the CPU may possibly enter into low power mode. This way we can
4275 * notice an extended quiescent state to other CPUs that started a grace
4276 * period. Otherwise we would delay any grace period as long as we run
4279 * So complain bitterly if someone does call rcu_read_lock(),
4280 * rcu_read_lock_bh() and so on from extended quiescent states.
4282 if (!rcu_is_watching())
4283 printk("RCU used illegally from extended quiescent state!\n");
4285 lockdep_print_held_locks(curr);
4286 printk("\nstack backtrace:\n");
4289 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);