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>
45 #include <asm/sections.h>
47 #include "lockdep_internals.h"
49 #ifdef CONFIG_PROVE_LOCKING
50 int prove_locking = 1;
51 module_param(prove_locking, int, 0644);
53 #define prove_locking 0
56 #ifdef CONFIG_LOCK_STAT
58 module_param(lock_stat, int, 0644);
64 * lockdep_lock: protects the lockdep graph, the hashes and the
65 * class/list/hash allocators.
67 * This is one of the rare exceptions where it's justified
68 * to use a raw spinlock - we really dont want the spinlock
69 * code to recurse back into the lockdep code...
71 static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
73 static int graph_lock(void)
75 __raw_spin_lock(&lockdep_lock);
77 * Make sure that if another CPU detected a bug while
78 * walking the graph we dont change it (while the other
79 * CPU is busy printing out stuff with the graph lock
83 __raw_spin_unlock(&lockdep_lock);
86 /* prevent any recursions within lockdep from causing deadlocks */
87 current->lockdep_recursion++;
91 static inline int graph_unlock(void)
93 if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
94 return DEBUG_LOCKS_WARN_ON(1);
96 current->lockdep_recursion--;
97 __raw_spin_unlock(&lockdep_lock);
102 * Turn lock debugging off and return with 0 if it was off already,
103 * and also release the graph lock:
105 static inline int debug_locks_off_graph_unlock(void)
107 int ret = debug_locks_off();
109 __raw_spin_unlock(&lockdep_lock);
114 static int lockdep_initialized;
116 unsigned long nr_list_entries;
117 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
120 * All data structures here are protected by the global debug_lock.
122 * Mutex key structs only get allocated, once during bootup, and never
123 * get freed - this significantly simplifies the debugging code.
125 unsigned long nr_lock_classes;
126 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
128 static inline struct lock_class *hlock_class(struct held_lock *hlock)
130 if (!hlock->class_idx) {
131 DEBUG_LOCKS_WARN_ON(1);
134 return lock_classes + hlock->class_idx - 1;
137 #ifdef CONFIG_LOCK_STAT
138 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
140 static int lock_point(unsigned long points[], unsigned long ip)
144 for (i = 0; i < LOCKSTAT_POINTS; i++) {
145 if (points[i] == 0) {
156 static void lock_time_inc(struct lock_time *lt, s64 time)
161 if (time < lt->min || !lt->min)
168 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
170 dst->min += src->min;
171 dst->max += src->max;
172 dst->total += src->total;
176 struct lock_class_stats lock_stats(struct lock_class *class)
178 struct lock_class_stats stats;
181 memset(&stats, 0, sizeof(struct lock_class_stats));
182 for_each_possible_cpu(cpu) {
183 struct lock_class_stats *pcs =
184 &per_cpu(lock_stats, cpu)[class - lock_classes];
186 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
187 stats.contention_point[i] += pcs->contention_point[i];
189 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
190 stats.contending_point[i] += pcs->contending_point[i];
192 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
193 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
195 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
196 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
198 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
199 stats.bounces[i] += pcs->bounces[i];
205 void clear_lock_stats(struct lock_class *class)
209 for_each_possible_cpu(cpu) {
210 struct lock_class_stats *cpu_stats =
211 &per_cpu(lock_stats, cpu)[class - lock_classes];
213 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
215 memset(class->contention_point, 0, sizeof(class->contention_point));
216 memset(class->contending_point, 0, sizeof(class->contending_point));
219 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
221 return &get_cpu_var(lock_stats)[class - lock_classes];
224 static void put_lock_stats(struct lock_class_stats *stats)
226 put_cpu_var(lock_stats);
229 static void lock_release_holdtime(struct held_lock *hlock)
231 struct lock_class_stats *stats;
237 holdtime = sched_clock() - hlock->holdtime_stamp;
239 stats = get_lock_stats(hlock_class(hlock));
241 lock_time_inc(&stats->read_holdtime, holdtime);
243 lock_time_inc(&stats->write_holdtime, holdtime);
244 put_lock_stats(stats);
247 static inline void lock_release_holdtime(struct held_lock *hlock)
253 * We keep a global list of all lock classes. The list only grows,
254 * never shrinks. The list is only accessed with the lockdep
255 * spinlock lock held.
257 LIST_HEAD(all_lock_classes);
260 * The lockdep classes are in a hash-table as well, for fast lookup:
262 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
263 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
264 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
265 #define classhashentry(key) (classhash_table + __classhashfn((key)))
267 static struct list_head classhash_table[CLASSHASH_SIZE];
270 * We put the lock dependency chains into a hash-table as well, to cache
273 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
274 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
275 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
276 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
278 static struct list_head chainhash_table[CHAINHASH_SIZE];
281 * The hash key of the lock dependency chains is a hash itself too:
282 * it's a hash of all locks taken up to that lock, including that lock.
283 * It's a 64-bit hash, because it's important for the keys to be
286 #define iterate_chain_key(key1, key2) \
287 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
288 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
291 void lockdep_off(void)
293 current->lockdep_recursion++;
295 EXPORT_SYMBOL(lockdep_off);
297 void lockdep_on(void)
299 current->lockdep_recursion--;
301 EXPORT_SYMBOL(lockdep_on);
304 * Debugging switches:
308 #define VERY_VERBOSE 0
311 # define HARDIRQ_VERBOSE 1
312 # define SOFTIRQ_VERBOSE 1
313 # define RECLAIM_VERBOSE 1
315 # define HARDIRQ_VERBOSE 0
316 # define SOFTIRQ_VERBOSE 0
317 # define RECLAIM_VERBOSE 0
320 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
322 * Quick filtering for interesting events:
324 static int class_filter(struct lock_class *class)
328 if (class->name_version == 1 &&
329 !strcmp(class->name, "lockname"))
331 if (class->name_version == 1 &&
332 !strcmp(class->name, "&struct->lockfield"))
335 /* Filter everything else. 1 would be to allow everything else */
340 static int verbose(struct lock_class *class)
343 return class_filter(class);
349 * Stack-trace: tightly packed array of stack backtrace
350 * addresses. Protected by the graph_lock.
352 unsigned long nr_stack_trace_entries;
353 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
355 static int save_trace(struct stack_trace *trace)
357 trace->nr_entries = 0;
358 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
359 trace->entries = stack_trace + nr_stack_trace_entries;
363 save_stack_trace(trace);
365 trace->max_entries = trace->nr_entries;
367 nr_stack_trace_entries += trace->nr_entries;
369 if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
370 if (!debug_locks_off_graph_unlock())
373 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
374 printk("turning off the locking correctness validator.\n");
383 unsigned int nr_hardirq_chains;
384 unsigned int nr_softirq_chains;
385 unsigned int nr_process_chains;
386 unsigned int max_lockdep_depth;
387 unsigned int max_recursion_depth;
389 static unsigned int lockdep_dependency_gen_id;
391 static bool lockdep_dependency_visit(struct lock_class *source,
395 lockdep_dependency_gen_id++;
396 if (source->dep_gen_id == lockdep_dependency_gen_id)
398 source->dep_gen_id = lockdep_dependency_gen_id;
402 #ifdef CONFIG_DEBUG_LOCKDEP
404 * We cannot printk in early bootup code. Not even early_printk()
405 * might work. So we mark any initialization errors and printk
406 * about it later on, in lockdep_info().
408 static int lockdep_init_error;
409 static unsigned long lockdep_init_trace_data[20];
410 static struct stack_trace lockdep_init_trace = {
411 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
412 .entries = lockdep_init_trace_data,
416 * Various lockdep statistics:
418 atomic_t chain_lookup_hits;
419 atomic_t chain_lookup_misses;
420 atomic_t hardirqs_on_events;
421 atomic_t hardirqs_off_events;
422 atomic_t redundant_hardirqs_on;
423 atomic_t redundant_hardirqs_off;
424 atomic_t softirqs_on_events;
425 atomic_t softirqs_off_events;
426 atomic_t redundant_softirqs_on;
427 atomic_t redundant_softirqs_off;
428 atomic_t nr_unused_locks;
429 atomic_t nr_cyclic_checks;
430 atomic_t nr_cyclic_check_recursions;
431 atomic_t nr_find_usage_forwards_checks;
432 atomic_t nr_find_usage_forwards_recursions;
433 atomic_t nr_find_usage_backwards_checks;
434 atomic_t nr_find_usage_backwards_recursions;
435 # define debug_atomic_inc(ptr) atomic_inc(ptr)
436 # define debug_atomic_dec(ptr) atomic_dec(ptr)
437 # define debug_atomic_read(ptr) atomic_read(ptr)
439 # define debug_atomic_inc(ptr) do { } while (0)
440 # define debug_atomic_dec(ptr) do { } while (0)
441 # define debug_atomic_read(ptr) 0
448 #define __STR(foo) #foo
449 #define STR(foo) __STR(foo)
451 #define __USAGE(__STATE) \
452 [LOCK_USED_IN_##__STATE] = "IN-"STR(__STATE)"-W", \
453 [LOCK_ENABLED_##__STATE] = STR(__STATE)"-ON-W", \
454 [LOCK_USED_IN_##__STATE##_READ] = "IN-"STR(__STATE)"-R", \
455 [LOCK_ENABLED_##__STATE##_READ] = STR(__STATE)"-ON-R",
457 static const char *usage_str[] =
459 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
460 #include "lockdep_states.h"
462 [LOCK_USED] = "INITIAL USE",
465 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
467 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
470 static inline unsigned long lock_flag(enum lock_usage_bit bit)
475 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
479 if (class->usage_mask & lock_flag(bit + 2))
481 if (class->usage_mask & lock_flag(bit)) {
483 if (class->usage_mask & lock_flag(bit + 2))
490 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
494 #define LOCKDEP_STATE(__STATE) \
495 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
496 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
497 #include "lockdep_states.h"
503 static void print_lock_name(struct lock_class *class)
505 char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
508 get_usage_chars(class, usage);
512 name = __get_key_name(class->key, str);
513 printk(" (%s", name);
515 printk(" (%s", name);
516 if (class->name_version > 1)
517 printk("#%d", class->name_version);
519 printk("/%d", class->subclass);
521 printk("){%s}", usage);
524 static void print_lockdep_cache(struct lockdep_map *lock)
527 char str[KSYM_NAME_LEN];
531 name = __get_key_name(lock->key->subkeys, str);
536 static void print_lock(struct held_lock *hlock)
538 print_lock_name(hlock_class(hlock));
540 print_ip_sym(hlock->acquire_ip);
543 static void lockdep_print_held_locks(struct task_struct *curr)
545 int i, depth = curr->lockdep_depth;
548 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
551 printk("%d lock%s held by %s/%d:\n",
552 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
554 for (i = 0; i < depth; i++) {
556 print_lock(curr->held_locks + i);
560 static void print_lock_class_header(struct lock_class *class, int depth)
564 printk("%*s->", depth, "");
565 print_lock_name(class);
566 printk(" ops: %lu", class->ops);
569 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
570 if (class->usage_mask & (1 << bit)) {
573 len += printk("%*s %s", depth, "", usage_str[bit]);
574 len += printk(" at:\n");
575 print_stack_trace(class->usage_traces + bit, len);
578 printk("%*s }\n", depth, "");
580 printk("%*s ... key at: ",depth,"");
581 print_ip_sym((unsigned long)class->key);
585 * printk all lock dependencies starting at <entry>:
588 print_lock_dependencies(struct lock_class *class, int depth)
590 struct lock_list *entry;
592 if (lockdep_dependency_visit(class, depth))
595 if (DEBUG_LOCKS_WARN_ON(depth >= 20))
598 print_lock_class_header(class, depth);
600 list_for_each_entry(entry, &class->locks_after, entry) {
601 if (DEBUG_LOCKS_WARN_ON(!entry->class))
604 print_lock_dependencies(entry->class, depth + 1);
606 printk("%*s ... acquired at:\n",depth,"");
607 print_stack_trace(&entry->trace, 2);
612 static void print_kernel_version(void)
614 printk("%s %.*s\n", init_utsname()->release,
615 (int)strcspn(init_utsname()->version, " "),
616 init_utsname()->version);
619 static int very_verbose(struct lock_class *class)
622 return class_filter(class);
628 * Is this the address of a static object:
630 static int static_obj(void *obj)
632 unsigned long start = (unsigned long) &_stext,
633 end = (unsigned long) &_end,
634 addr = (unsigned long) obj;
642 if ((addr >= start) && (addr < end))
649 for_each_possible_cpu(i) {
650 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
651 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
654 if ((addr >= start) && (addr < end))
662 return is_module_address(addr);
666 * To make lock name printouts unique, we calculate a unique
667 * class->name_version generation counter:
669 static int count_matching_names(struct lock_class *new_class)
671 struct lock_class *class;
674 if (!new_class->name)
677 list_for_each_entry(class, &all_lock_classes, lock_entry) {
678 if (new_class->key - new_class->subclass == class->key)
679 return class->name_version;
680 if (class->name && !strcmp(class->name, new_class->name))
681 count = max(count, class->name_version);
688 * Register a lock's class in the hash-table, if the class is not present
689 * yet. Otherwise we look it up. We cache the result in the lock object
690 * itself, so actual lookup of the hash should be once per lock object.
692 static inline struct lock_class *
693 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
695 struct lockdep_subclass_key *key;
696 struct list_head *hash_head;
697 struct lock_class *class;
699 #ifdef CONFIG_DEBUG_LOCKDEP
701 * If the architecture calls into lockdep before initializing
702 * the hashes then we'll warn about it later. (we cannot printk
705 if (unlikely(!lockdep_initialized)) {
707 lockdep_init_error = 1;
708 save_stack_trace(&lockdep_init_trace);
713 * Static locks do not have their class-keys yet - for them the key
714 * is the lock object itself:
716 if (unlikely(!lock->key))
717 lock->key = (void *)lock;
720 * NOTE: the class-key must be unique. For dynamic locks, a static
721 * lock_class_key variable is passed in through the mutex_init()
722 * (or spin_lock_init()) call - which acts as the key. For static
723 * locks we use the lock object itself as the key.
725 BUILD_BUG_ON(sizeof(struct lock_class_key) >
726 sizeof(struct lockdep_map));
728 key = lock->key->subkeys + subclass;
730 hash_head = classhashentry(key);
733 * We can walk the hash lockfree, because the hash only
734 * grows, and we are careful when adding entries to the end:
736 list_for_each_entry(class, hash_head, hash_entry) {
737 if (class->key == key) {
738 WARN_ON_ONCE(class->name != lock->name);
747 * Register a lock's class in the hash-table, if the class is not present
748 * yet. Otherwise we look it up. We cache the result in the lock object
749 * itself, so actual lookup of the hash should be once per lock object.
751 static inline struct lock_class *
752 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
754 struct lockdep_subclass_key *key;
755 struct list_head *hash_head;
756 struct lock_class *class;
759 class = look_up_lock_class(lock, subclass);
764 * Debug-check: all keys must be persistent!
766 if (!static_obj(lock->key)) {
768 printk("INFO: trying to register non-static key.\n");
769 printk("the code is fine but needs lockdep annotation.\n");
770 printk("turning off the locking correctness validator.\n");
776 key = lock->key->subkeys + subclass;
777 hash_head = classhashentry(key);
779 raw_local_irq_save(flags);
781 raw_local_irq_restore(flags);
785 * We have to do the hash-walk again, to avoid races
788 list_for_each_entry(class, hash_head, hash_entry)
789 if (class->key == key)
792 * Allocate a new key from the static array, and add it to
795 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
796 if (!debug_locks_off_graph_unlock()) {
797 raw_local_irq_restore(flags);
800 raw_local_irq_restore(flags);
802 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
803 printk("turning off the locking correctness validator.\n");
806 class = lock_classes + nr_lock_classes++;
807 debug_atomic_inc(&nr_unused_locks);
809 class->name = lock->name;
810 class->subclass = subclass;
811 INIT_LIST_HEAD(&class->lock_entry);
812 INIT_LIST_HEAD(&class->locks_before);
813 INIT_LIST_HEAD(&class->locks_after);
814 class->name_version = count_matching_names(class);
816 * We use RCU's safe list-add method to make
817 * parallel walking of the hash-list safe:
819 list_add_tail_rcu(&class->hash_entry, hash_head);
821 * Add it to the global list of classes:
823 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
825 if (verbose(class)) {
827 raw_local_irq_restore(flags);
829 printk("\nnew class %p: %s", class->key, class->name);
830 if (class->name_version > 1)
831 printk("#%d", class->name_version);
835 raw_local_irq_save(flags);
837 raw_local_irq_restore(flags);
843 raw_local_irq_restore(flags);
845 if (!subclass || force)
846 lock->class_cache = class;
848 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
854 #ifdef CONFIG_PROVE_LOCKING
856 * Allocate a lockdep entry. (assumes the graph_lock held, returns
857 * with NULL on failure)
859 static struct lock_list *alloc_list_entry(void)
861 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
862 if (!debug_locks_off_graph_unlock())
865 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
866 printk("turning off the locking correctness validator.\n");
869 return list_entries + nr_list_entries++;
873 * Add a new dependency to the head of the list:
875 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
876 struct list_head *head, unsigned long ip, int distance)
878 struct lock_list *entry;
880 * Lock not present yet - get a new dependency struct and
881 * add it to the list:
883 entry = alloc_list_entry();
887 if (!save_trace(&entry->trace))
891 entry->distance = distance;
893 * Since we never remove from the dependency list, the list can
894 * be walked lockless by other CPUs, it's only allocation
895 * that must be protected by the spinlock. But this also means
896 * we must make new entries visible only once writes to the
897 * entry become visible - hence the RCU op:
899 list_add_tail_rcu(&entry->entry, head);
905 * Recursive, forwards-direction lock-dependency checking, used for
906 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
909 * (to keep the stackframe of the recursive functions small we
910 * use these global variables, and we also mark various helper
911 * functions as noinline.)
913 static struct held_lock *check_source, *check_target;
916 * Print a dependency chain entry (this is only done when a deadlock
917 * has been detected):
920 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
922 if (debug_locks_silent)
924 printk("\n-> #%u", depth);
925 print_lock_name(target->class);
927 print_stack_trace(&target->trace, 6);
933 * When a circular dependency is detected, print the
937 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
939 struct task_struct *curr = current;
941 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
944 printk("\n=======================================================\n");
945 printk( "[ INFO: possible circular locking dependency detected ]\n");
946 print_kernel_version();
947 printk( "-------------------------------------------------------\n");
948 printk("%s/%d is trying to acquire lock:\n",
949 curr->comm, task_pid_nr(curr));
950 print_lock(check_source);
951 printk("\nbut task is already holding lock:\n");
952 print_lock(check_target);
953 printk("\nwhich lock already depends on the new lock.\n\n");
954 printk("\nthe existing dependency chain (in reverse order) is:\n");
956 print_circular_bug_entry(entry, depth);
961 static noinline int print_circular_bug_tail(void)
963 struct task_struct *curr = current;
964 struct lock_list this;
966 if (debug_locks_silent)
969 this.class = hlock_class(check_source);
970 if (!save_trace(&this.trace))
973 print_circular_bug_entry(&this, 0);
975 printk("\nother info that might help us debug this:\n\n");
976 lockdep_print_held_locks(curr);
978 printk("\nstack backtrace:\n");
984 #define RECURSION_LIMIT 40
986 static int noinline print_infinite_recursion_bug(void)
988 if (!debug_locks_off_graph_unlock())
996 unsigned long __lockdep_count_forward_deps(struct lock_class *class,
999 struct lock_list *entry;
1000 unsigned long ret = 1;
1002 if (lockdep_dependency_visit(class, depth))
1006 * Recurse this class's dependency list:
1008 list_for_each_entry(entry, &class->locks_after, entry)
1009 ret += __lockdep_count_forward_deps(entry->class, depth + 1);
1014 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1016 unsigned long ret, flags;
1018 local_irq_save(flags);
1019 __raw_spin_lock(&lockdep_lock);
1020 ret = __lockdep_count_forward_deps(class, 0);
1021 __raw_spin_unlock(&lockdep_lock);
1022 local_irq_restore(flags);
1027 unsigned long __lockdep_count_backward_deps(struct lock_class *class,
1030 struct lock_list *entry;
1031 unsigned long ret = 1;
1033 if (lockdep_dependency_visit(class, depth))
1036 * Recurse this class's dependency list:
1038 list_for_each_entry(entry, &class->locks_before, entry)
1039 ret += __lockdep_count_backward_deps(entry->class, depth + 1);
1044 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1046 unsigned long ret, flags;
1048 local_irq_save(flags);
1049 __raw_spin_lock(&lockdep_lock);
1050 ret = __lockdep_count_backward_deps(class, 0);
1051 __raw_spin_unlock(&lockdep_lock);
1052 local_irq_restore(flags);
1058 * Prove that the dependency graph starting at <entry> can not
1059 * lead to <target>. Print an error and return 0 if it does.
1062 check_noncircular(struct lock_class *source, unsigned int depth)
1064 struct lock_list *entry;
1066 if (lockdep_dependency_visit(source, depth))
1069 debug_atomic_inc(&nr_cyclic_check_recursions);
1070 if (depth > max_recursion_depth)
1071 max_recursion_depth = depth;
1072 if (depth >= RECURSION_LIMIT)
1073 return print_infinite_recursion_bug();
1075 * Check this lock's dependency list:
1077 list_for_each_entry(entry, &source->locks_after, entry) {
1078 if (entry->class == hlock_class(check_target))
1079 return print_circular_bug_header(entry, depth+1);
1080 debug_atomic_inc(&nr_cyclic_checks);
1081 if (!check_noncircular(entry->class, depth+1))
1082 return print_circular_bug_entry(entry, depth+1);
1087 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1089 * Forwards and backwards subgraph searching, for the purposes of
1090 * proving that two subgraphs can be connected by a new dependency
1091 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1093 static enum lock_usage_bit find_usage_bit;
1094 static struct lock_class *forwards_match, *backwards_match;
1097 * Find a node in the forwards-direction dependency sub-graph starting
1098 * at <source> that matches <find_usage_bit>.
1100 * Return 2 if such a node exists in the subgraph, and put that node
1101 * into <forwards_match>.
1103 * Return 1 otherwise and keep <forwards_match> unchanged.
1104 * Return 0 on error.
1107 find_usage_forwards(struct lock_class *source, unsigned int depth)
1109 struct lock_list *entry;
1112 if (lockdep_dependency_visit(source, depth))
1115 if (depth > max_recursion_depth)
1116 max_recursion_depth = depth;
1117 if (depth >= RECURSION_LIMIT)
1118 return print_infinite_recursion_bug();
1120 debug_atomic_inc(&nr_find_usage_forwards_checks);
1121 if (source->usage_mask & (1 << find_usage_bit)) {
1122 forwards_match = source;
1127 * Check this lock's dependency list:
1129 list_for_each_entry(entry, &source->locks_after, entry) {
1130 debug_atomic_inc(&nr_find_usage_forwards_recursions);
1131 ret = find_usage_forwards(entry->class, depth+1);
1132 if (ret == 2 || ret == 0)
1139 * Find a node in the backwards-direction dependency sub-graph starting
1140 * at <source> that matches <find_usage_bit>.
1142 * Return 2 if such a node exists in the subgraph, and put that node
1143 * into <backwards_match>.
1145 * Return 1 otherwise and keep <backwards_match> unchanged.
1146 * Return 0 on error.
1149 find_usage_backwards(struct lock_class *source, unsigned int depth)
1151 struct lock_list *entry;
1154 if (lockdep_dependency_visit(source, depth))
1157 if (!__raw_spin_is_locked(&lockdep_lock))
1158 return DEBUG_LOCKS_WARN_ON(1);
1160 if (depth > max_recursion_depth)
1161 max_recursion_depth = depth;
1162 if (depth >= RECURSION_LIMIT)
1163 return print_infinite_recursion_bug();
1165 debug_atomic_inc(&nr_find_usage_backwards_checks);
1166 if (source->usage_mask & (1 << find_usage_bit)) {
1167 backwards_match = source;
1171 if (!source && debug_locks_off_graph_unlock()) {
1177 * Check this lock's dependency list:
1179 list_for_each_entry(entry, &source->locks_before, entry) {
1180 debug_atomic_inc(&nr_find_usage_backwards_recursions);
1181 ret = find_usage_backwards(entry->class, depth+1);
1182 if (ret == 2 || ret == 0)
1189 print_bad_irq_dependency(struct task_struct *curr,
1190 struct held_lock *prev,
1191 struct held_lock *next,
1192 enum lock_usage_bit bit1,
1193 enum lock_usage_bit bit2,
1194 const char *irqclass)
1196 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1199 printk("\n======================================================\n");
1200 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1201 irqclass, irqclass);
1202 print_kernel_version();
1203 printk( "------------------------------------------------------\n");
1204 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1205 curr->comm, task_pid_nr(curr),
1206 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1207 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1208 curr->hardirqs_enabled,
1209 curr->softirqs_enabled);
1212 printk("\nand this task is already holding:\n");
1214 printk("which would create a new lock dependency:\n");
1215 print_lock_name(hlock_class(prev));
1217 print_lock_name(hlock_class(next));
1220 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1222 print_lock_name(backwards_match);
1223 printk("\n... which became %s-irq-safe at:\n", irqclass);
1225 print_stack_trace(backwards_match->usage_traces + bit1, 1);
1227 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1228 print_lock_name(forwards_match);
1229 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1232 print_stack_trace(forwards_match->usage_traces + bit2, 1);
1234 printk("\nother info that might help us debug this:\n\n");
1235 lockdep_print_held_locks(curr);
1237 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1238 print_lock_dependencies(backwards_match, 0);
1240 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1241 print_lock_dependencies(forwards_match, 0);
1243 printk("\nstack backtrace:\n");
1250 check_usage(struct task_struct *curr, struct held_lock *prev,
1251 struct held_lock *next, enum lock_usage_bit bit_backwards,
1252 enum lock_usage_bit bit_forwards, const char *irqclass)
1256 find_usage_bit = bit_backwards;
1257 /* fills in <backwards_match> */
1258 ret = find_usage_backwards(hlock_class(prev), 0);
1259 if (!ret || ret == 1)
1262 find_usage_bit = bit_forwards;
1263 ret = find_usage_forwards(hlock_class(next), 0);
1264 if (!ret || ret == 1)
1267 return print_bad_irq_dependency(curr, prev, next,
1268 bit_backwards, bit_forwards, irqclass);
1271 static const char *state_names[] = {
1272 #define LOCKDEP_STATE(__STATE) \
1274 #include "lockdep_states.h"
1275 #undef LOCKDEP_STATE
1278 static const char *state_rnames[] = {
1279 #define LOCKDEP_STATE(__STATE) \
1280 STR(__STATE)"-READ",
1281 #include "lockdep_states.h"
1282 #undef LOCKDEP_STATE
1285 static inline const char *state_name(enum lock_usage_bit bit)
1287 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1290 static int exclusive_bit(int new_bit)
1298 * bit 0 - write/read
1299 * bit 1 - used_in/enabled
1303 int state = new_bit & ~3;
1304 int dir = new_bit & 2;
1307 * keep state, bit flip the direction and strip read.
1309 return state | (dir ^ 2);
1312 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1313 struct held_lock *next, enum lock_usage_bit bit)
1316 * Prove that the new dependency does not connect a hardirq-safe
1317 * lock with a hardirq-unsafe lock - to achieve this we search
1318 * the backwards-subgraph starting at <prev>, and the
1319 * forwards-subgraph starting at <next>:
1321 if (!check_usage(curr, prev, next, bit,
1322 exclusive_bit(bit), state_name(bit)))
1328 * Prove that the new dependency does not connect a hardirq-safe-read
1329 * lock with a hardirq-unsafe lock - to achieve this we search
1330 * the backwards-subgraph starting at <prev>, and the
1331 * forwards-subgraph starting at <next>:
1333 if (!check_usage(curr, prev, next, bit,
1334 exclusive_bit(bit), state_name(bit)))
1341 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1342 struct held_lock *next)
1344 #define LOCKDEP_STATE(__STATE) \
1345 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1347 #include "lockdep_states.h"
1348 #undef LOCKDEP_STATE
1353 static void inc_chains(void)
1355 if (current->hardirq_context)
1356 nr_hardirq_chains++;
1358 if (current->softirq_context)
1359 nr_softirq_chains++;
1361 nr_process_chains++;
1368 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1369 struct held_lock *next)
1374 static inline void inc_chains(void)
1376 nr_process_chains++;
1382 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1383 struct held_lock *next)
1385 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1388 printk("\n=============================================\n");
1389 printk( "[ INFO: possible recursive locking detected ]\n");
1390 print_kernel_version();
1391 printk( "---------------------------------------------\n");
1392 printk("%s/%d is trying to acquire lock:\n",
1393 curr->comm, task_pid_nr(curr));
1395 printk("\nbut task is already holding lock:\n");
1398 printk("\nother info that might help us debug this:\n");
1399 lockdep_print_held_locks(curr);
1401 printk("\nstack backtrace:\n");
1408 * Check whether we are holding such a class already.
1410 * (Note that this has to be done separately, because the graph cannot
1411 * detect such classes of deadlocks.)
1413 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1416 check_deadlock(struct task_struct *curr, struct held_lock *next,
1417 struct lockdep_map *next_instance, int read)
1419 struct held_lock *prev;
1420 struct held_lock *nest = NULL;
1423 for (i = 0; i < curr->lockdep_depth; i++) {
1424 prev = curr->held_locks + i;
1426 if (prev->instance == next->nest_lock)
1429 if (hlock_class(prev) != hlock_class(next))
1433 * Allow read-after-read recursion of the same
1434 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1436 if ((read == 2) && prev->read)
1440 * We're holding the nest_lock, which serializes this lock's
1441 * nesting behaviour.
1446 return print_deadlock_bug(curr, prev, next);
1452 * There was a chain-cache miss, and we are about to add a new dependency
1453 * to a previous lock. We recursively validate the following rules:
1455 * - would the adding of the <prev> -> <next> dependency create a
1456 * circular dependency in the graph? [== circular deadlock]
1458 * - does the new prev->next dependency connect any hardirq-safe lock
1459 * (in the full backwards-subgraph starting at <prev>) with any
1460 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1461 * <next>)? [== illegal lock inversion with hardirq contexts]
1463 * - does the new prev->next dependency connect any softirq-safe lock
1464 * (in the full backwards-subgraph starting at <prev>) with any
1465 * softirq-unsafe lock (in the full forwards-subgraph starting at
1466 * <next>)? [== illegal lock inversion with softirq contexts]
1468 * any of these scenarios could lead to a deadlock.
1470 * Then if all the validations pass, we add the forwards and backwards
1474 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1475 struct held_lock *next, int distance)
1477 struct lock_list *entry;
1481 * Prove that the new <prev> -> <next> dependency would not
1482 * create a circular dependency in the graph. (We do this by
1483 * forward-recursing into the graph starting at <next>, and
1484 * checking whether we can reach <prev>.)
1486 * We are using global variables to control the recursion, to
1487 * keep the stackframe size of the recursive functions low:
1489 check_source = next;
1490 check_target = prev;
1491 if (!(check_noncircular(hlock_class(next), 0)))
1492 return print_circular_bug_tail();
1494 if (!check_prev_add_irq(curr, prev, next))
1498 * For recursive read-locks we do all the dependency checks,
1499 * but we dont store read-triggered dependencies (only
1500 * write-triggered dependencies). This ensures that only the
1501 * write-side dependencies matter, and that if for example a
1502 * write-lock never takes any other locks, then the reads are
1503 * equivalent to a NOP.
1505 if (next->read == 2 || prev->read == 2)
1508 * Is the <prev> -> <next> dependency already present?
1510 * (this may occur even though this is a new chain: consider
1511 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1512 * chains - the second one will be new, but L1 already has
1513 * L2 added to its dependency list, due to the first chain.)
1515 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1516 if (entry->class == hlock_class(next)) {
1518 entry->distance = 1;
1524 * Ok, all validations passed, add the new lock
1525 * to the previous lock's dependency list:
1527 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1528 &hlock_class(prev)->locks_after,
1529 next->acquire_ip, distance);
1534 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1535 &hlock_class(next)->locks_before,
1536 next->acquire_ip, distance);
1541 * Debugging printouts:
1543 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1545 printk("\n new dependency: ");
1546 print_lock_name(hlock_class(prev));
1548 print_lock_name(hlock_class(next));
1551 return graph_lock();
1557 * Add the dependency to all directly-previous locks that are 'relevant'.
1558 * The ones that are relevant are (in increasing distance from curr):
1559 * all consecutive trylock entries and the final non-trylock entry - or
1560 * the end of this context's lock-chain - whichever comes first.
1563 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1565 int depth = curr->lockdep_depth;
1566 struct held_lock *hlock;
1571 * Depth must not be zero for a non-head lock:
1576 * At least two relevant locks must exist for this
1579 if (curr->held_locks[depth].irq_context !=
1580 curr->held_locks[depth-1].irq_context)
1584 int distance = curr->lockdep_depth - depth + 1;
1585 hlock = curr->held_locks + depth-1;
1587 * Only non-recursive-read entries get new dependencies
1590 if (hlock->read != 2) {
1591 if (!check_prev_add(curr, hlock, next, distance))
1594 * Stop after the first non-trylock entry,
1595 * as non-trylock entries have added their
1596 * own direct dependencies already, so this
1597 * lock is connected to them indirectly:
1599 if (!hlock->trylock)
1604 * End of lock-stack?
1609 * Stop the search if we cross into another context:
1611 if (curr->held_locks[depth].irq_context !=
1612 curr->held_locks[depth-1].irq_context)
1617 if (!debug_locks_off_graph_unlock())
1625 unsigned long nr_lock_chains;
1626 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1627 int nr_chain_hlocks;
1628 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1630 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1632 return lock_classes + chain_hlocks[chain->base + i];
1636 * Look up a dependency chain. If the key is not present yet then
1637 * add it and return 1 - in this case the new dependency chain is
1638 * validated. If the key is already hashed, return 0.
1639 * (On return with 1 graph_lock is held.)
1641 static inline int lookup_chain_cache(struct task_struct *curr,
1642 struct held_lock *hlock,
1645 struct lock_class *class = hlock_class(hlock);
1646 struct list_head *hash_head = chainhashentry(chain_key);
1647 struct lock_chain *chain;
1648 struct held_lock *hlock_curr, *hlock_next;
1651 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1654 * We can walk it lock-free, because entries only get added
1657 list_for_each_entry(chain, hash_head, entry) {
1658 if (chain->chain_key == chain_key) {
1660 debug_atomic_inc(&chain_lookup_hits);
1661 if (very_verbose(class))
1662 printk("\nhash chain already cached, key: "
1663 "%016Lx tail class: [%p] %s\n",
1664 (unsigned long long)chain_key,
1665 class->key, class->name);
1669 if (very_verbose(class))
1670 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1671 (unsigned long long)chain_key, class->key, class->name);
1673 * Allocate a new chain entry from the static array, and add
1679 * We have to walk the chain again locked - to avoid duplicates:
1681 list_for_each_entry(chain, hash_head, entry) {
1682 if (chain->chain_key == chain_key) {
1687 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1688 if (!debug_locks_off_graph_unlock())
1691 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1692 printk("turning off the locking correctness validator.\n");
1695 chain = lock_chains + nr_lock_chains++;
1696 chain->chain_key = chain_key;
1697 chain->irq_context = hlock->irq_context;
1698 /* Find the first held_lock of current chain */
1700 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1701 hlock_curr = curr->held_locks + i;
1702 if (hlock_curr->irq_context != hlock_next->irq_context)
1707 chain->depth = curr->lockdep_depth + 1 - i;
1708 cn = nr_chain_hlocks;
1709 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1710 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1715 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1717 for (j = 0; j < chain->depth - 1; j++, i++) {
1718 int lock_id = curr->held_locks[i].class_idx - 1;
1719 chain_hlocks[chain->base + j] = lock_id;
1721 chain_hlocks[chain->base + j] = class - lock_classes;
1723 list_add_tail_rcu(&chain->entry, hash_head);
1724 debug_atomic_inc(&chain_lookup_misses);
1730 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1731 struct held_lock *hlock, int chain_head, u64 chain_key)
1734 * Trylock needs to maintain the stack of held locks, but it
1735 * does not add new dependencies, because trylock can be done
1738 * We look up the chain_key and do the O(N^2) check and update of
1739 * the dependencies only if this is a new dependency chain.
1740 * (If lookup_chain_cache() returns with 1 it acquires
1741 * graph_lock for us)
1743 if (!hlock->trylock && (hlock->check == 2) &&
1744 lookup_chain_cache(curr, hlock, chain_key)) {
1746 * Check whether last held lock:
1748 * - is irq-safe, if this lock is irq-unsafe
1749 * - is softirq-safe, if this lock is hardirq-unsafe
1751 * And check whether the new lock's dependency graph
1752 * could lead back to the previous lock.
1754 * any of these scenarios could lead to a deadlock. If
1757 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1762 * Mark recursive read, as we jump over it when
1763 * building dependencies (just like we jump over
1769 * Add dependency only if this lock is not the head
1770 * of the chain, and if it's not a secondary read-lock:
1772 if (!chain_head && ret != 2)
1773 if (!check_prevs_add(curr, hlock))
1777 /* after lookup_chain_cache(): */
1778 if (unlikely(!debug_locks))
1784 static inline int validate_chain(struct task_struct *curr,
1785 struct lockdep_map *lock, struct held_lock *hlock,
1786 int chain_head, u64 chain_key)
1793 * We are building curr_chain_key incrementally, so double-check
1794 * it from scratch, to make sure that it's done correctly:
1796 static void check_chain_key(struct task_struct *curr)
1798 #ifdef CONFIG_DEBUG_LOCKDEP
1799 struct held_lock *hlock, *prev_hlock = NULL;
1803 for (i = 0; i < curr->lockdep_depth; i++) {
1804 hlock = curr->held_locks + i;
1805 if (chain_key != hlock->prev_chain_key) {
1807 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1808 curr->lockdep_depth, i,
1809 (unsigned long long)chain_key,
1810 (unsigned long long)hlock->prev_chain_key);
1813 id = hlock->class_idx - 1;
1814 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1817 if (prev_hlock && (prev_hlock->irq_context !=
1818 hlock->irq_context))
1820 chain_key = iterate_chain_key(chain_key, id);
1823 if (chain_key != curr->curr_chain_key) {
1825 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1826 curr->lockdep_depth, i,
1827 (unsigned long long)chain_key,
1828 (unsigned long long)curr->curr_chain_key);
1834 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1835 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1837 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1840 printk("\n=================================\n");
1841 printk( "[ INFO: inconsistent lock state ]\n");
1842 print_kernel_version();
1843 printk( "---------------------------------\n");
1845 printk("inconsistent {%s} -> {%s} usage.\n",
1846 usage_str[prev_bit], usage_str[new_bit]);
1848 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1849 curr->comm, task_pid_nr(curr),
1850 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1851 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1852 trace_hardirqs_enabled(curr),
1853 trace_softirqs_enabled(curr));
1856 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1857 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
1859 print_irqtrace_events(curr);
1860 printk("\nother info that might help us debug this:\n");
1861 lockdep_print_held_locks(curr);
1863 printk("\nstack backtrace:\n");
1870 * Print out an error if an invalid bit is set:
1873 valid_state(struct task_struct *curr, struct held_lock *this,
1874 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1876 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
1877 return print_usage_bug(curr, this, bad_bit, new_bit);
1881 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1882 enum lock_usage_bit new_bit);
1884 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1887 * print irq inversion bug:
1890 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1891 struct held_lock *this, int forwards,
1892 const char *irqclass)
1894 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1897 printk("\n=========================================================\n");
1898 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1899 print_kernel_version();
1900 printk( "---------------------------------------------------------\n");
1901 printk("%s/%d just changed the state of lock:\n",
1902 curr->comm, task_pid_nr(curr));
1905 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1907 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1908 print_lock_name(other);
1909 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1911 printk("\nother info that might help us debug this:\n");
1912 lockdep_print_held_locks(curr);
1914 printk("\nthe first lock's dependencies:\n");
1915 print_lock_dependencies(hlock_class(this), 0);
1917 printk("\nthe second lock's dependencies:\n");
1918 print_lock_dependencies(other, 0);
1920 printk("\nstack backtrace:\n");
1927 * Prove that in the forwards-direction subgraph starting at <this>
1928 * there is no lock matching <mask>:
1931 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1932 enum lock_usage_bit bit, const char *irqclass)
1936 find_usage_bit = bit;
1937 /* fills in <forwards_match> */
1938 ret = find_usage_forwards(hlock_class(this), 0);
1939 if (!ret || ret == 1)
1942 return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1946 * Prove that in the backwards-direction subgraph starting at <this>
1947 * there is no lock matching <mask>:
1950 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1951 enum lock_usage_bit bit, const char *irqclass)
1955 find_usage_bit = bit;
1956 /* fills in <backwards_match> */
1957 ret = find_usage_backwards(hlock_class(this), 0);
1958 if (!ret || ret == 1)
1961 return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1964 void print_irqtrace_events(struct task_struct *curr)
1966 printk("irq event stamp: %u\n", curr->irq_events);
1967 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
1968 print_ip_sym(curr->hardirq_enable_ip);
1969 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1970 print_ip_sym(curr->hardirq_disable_ip);
1971 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
1972 print_ip_sym(curr->softirq_enable_ip);
1973 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1974 print_ip_sym(curr->softirq_disable_ip);
1977 static int HARDIRQ_verbose(struct lock_class *class)
1980 return class_filter(class);
1985 static int SOFTIRQ_verbose(struct lock_class *class)
1988 return class_filter(class);
1993 static int RECLAIM_FS_verbose(struct lock_class *class)
1996 return class_filter(class);
2001 #define STRICT_READ_CHECKS 1
2003 static int (*state_verbose_f[])(struct lock_class *class) = {
2004 #define LOCKDEP_STATE(__STATE) \
2006 #include "lockdep_states.h"
2007 #undef LOCKDEP_STATE
2010 static inline int state_verbose(enum lock_usage_bit bit,
2011 struct lock_class *class)
2013 return state_verbose_f[bit >> 2](class);
2016 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2017 enum lock_usage_bit bit, const char *name);
2020 mark_lock_irq(struct task_struct *curr, struct held_lock *this, int new_bit)
2022 int excl_bit = exclusive_bit(new_bit);
2023 int read = new_bit & 1;
2024 int dir = new_bit & 2;
2027 * mark USED_IN has to look forwards -- to ensure no dependency
2028 * has ENABLED state, which would allow recursion deadlocks.
2030 * mark ENABLED has to look backwards -- to ensure no dependee
2031 * has USED_IN state, which, again, would allow recursion deadlocks.
2033 check_usage_f usage = dir ?
2034 check_usage_backwards : check_usage_forwards;
2037 * Validate that this particular lock does not have conflicting
2040 if (!valid_state(curr, this, new_bit, excl_bit))
2044 * Validate that the lock dependencies don't have conflicting usage
2047 if ((!read || !dir || STRICT_READ_CHECKS) &&
2048 !usage(curr, this, excl_bit, state_name(new_bit)))
2052 * Check for read in write conflicts
2055 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2058 if (STRICT_READ_CHECKS &&
2059 !usage(curr, this, excl_bit + 1,
2060 state_name(new_bit + 1)))
2064 if (state_verbose(new_bit, hlock_class(this)))
2071 #define LOCKDEP_STATE(__STATE) __STATE,
2072 #include "lockdep_states.h"
2073 #undef LOCKDEP_STATE
2077 * Mark all held locks with a usage bit:
2080 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2082 enum lock_usage_bit usage_bit;
2083 struct held_lock *hlock;
2086 for (i = 0; i < curr->lockdep_depth; i++) {
2087 hlock = curr->held_locks + i;
2089 usage_bit = 2 + (mark << 2); /* ENABLED */
2091 usage_bit += 1; /* READ */
2093 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2095 if (!mark_lock(curr, hlock, usage_bit))
2103 * Debugging helper: via this flag we know that we are in
2104 * 'early bootup code', and will warn about any invalid irqs-on event:
2106 static int early_boot_irqs_enabled;
2108 void early_boot_irqs_off(void)
2110 early_boot_irqs_enabled = 0;
2113 void early_boot_irqs_on(void)
2115 early_boot_irqs_enabled = 1;
2119 * Hardirqs will be enabled:
2121 void trace_hardirqs_on_caller(unsigned long ip)
2123 struct task_struct *curr = current;
2125 time_hardirqs_on(CALLER_ADDR0, ip);
2127 if (unlikely(!debug_locks || current->lockdep_recursion))
2130 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2133 if (unlikely(curr->hardirqs_enabled)) {
2134 debug_atomic_inc(&redundant_hardirqs_on);
2137 /* we'll do an OFF -> ON transition: */
2138 curr->hardirqs_enabled = 1;
2140 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2142 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2145 * We are going to turn hardirqs on, so set the
2146 * usage bit for all held locks:
2148 if (!mark_held_locks(curr, HARDIRQ))
2151 * If we have softirqs enabled, then set the usage
2152 * bit for all held locks. (disabled hardirqs prevented
2153 * this bit from being set before)
2155 if (curr->softirqs_enabled)
2156 if (!mark_held_locks(curr, SOFTIRQ))
2159 curr->hardirq_enable_ip = ip;
2160 curr->hardirq_enable_event = ++curr->irq_events;
2161 debug_atomic_inc(&hardirqs_on_events);
2163 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2165 void trace_hardirqs_on(void)
2167 trace_hardirqs_on_caller(CALLER_ADDR0);
2169 EXPORT_SYMBOL(trace_hardirqs_on);
2172 * Hardirqs were disabled:
2174 void trace_hardirqs_off_caller(unsigned long ip)
2176 struct task_struct *curr = current;
2178 time_hardirqs_off(CALLER_ADDR0, ip);
2180 if (unlikely(!debug_locks || current->lockdep_recursion))
2183 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2186 if (curr->hardirqs_enabled) {
2188 * We have done an ON -> OFF transition:
2190 curr->hardirqs_enabled = 0;
2191 curr->hardirq_disable_ip = ip;
2192 curr->hardirq_disable_event = ++curr->irq_events;
2193 debug_atomic_inc(&hardirqs_off_events);
2195 debug_atomic_inc(&redundant_hardirqs_off);
2197 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2199 void trace_hardirqs_off(void)
2201 trace_hardirqs_off_caller(CALLER_ADDR0);
2203 EXPORT_SYMBOL(trace_hardirqs_off);
2206 * Softirqs will be enabled:
2208 void trace_softirqs_on(unsigned long ip)
2210 struct task_struct *curr = current;
2212 if (unlikely(!debug_locks))
2215 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2218 if (curr->softirqs_enabled) {
2219 debug_atomic_inc(&redundant_softirqs_on);
2224 * We'll do an OFF -> ON transition:
2226 curr->softirqs_enabled = 1;
2227 curr->softirq_enable_ip = ip;
2228 curr->softirq_enable_event = ++curr->irq_events;
2229 debug_atomic_inc(&softirqs_on_events);
2231 * We are going to turn softirqs on, so set the
2232 * usage bit for all held locks, if hardirqs are
2235 if (curr->hardirqs_enabled)
2236 mark_held_locks(curr, SOFTIRQ);
2240 * Softirqs were disabled:
2242 void trace_softirqs_off(unsigned long ip)
2244 struct task_struct *curr = current;
2246 if (unlikely(!debug_locks))
2249 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2252 if (curr->softirqs_enabled) {
2254 * We have done an ON -> OFF transition:
2256 curr->softirqs_enabled = 0;
2257 curr->softirq_disable_ip = ip;
2258 curr->softirq_disable_event = ++curr->irq_events;
2259 debug_atomic_inc(&softirqs_off_events);
2260 DEBUG_LOCKS_WARN_ON(!softirq_count());
2262 debug_atomic_inc(&redundant_softirqs_off);
2265 void lockdep_trace_alloc(gfp_t gfp_mask)
2267 struct task_struct *curr = current;
2269 if (unlikely(!debug_locks))
2272 /* no reclaim without waiting on it */
2273 if (!(gfp_mask & __GFP_WAIT))
2276 /* this guy won't enter reclaim */
2277 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2280 /* We're only interested __GFP_FS allocations for now */
2281 if (!(gfp_mask & __GFP_FS))
2284 if (DEBUG_LOCKS_WARN_ON(irqs_disabled()))
2287 mark_held_locks(curr, RECLAIM_FS);
2290 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2293 * If non-trylock use in a hardirq or softirq context, then
2294 * mark the lock as used in these contexts:
2296 if (!hlock->trylock) {
2298 if (curr->hardirq_context)
2299 if (!mark_lock(curr, hlock,
2300 LOCK_USED_IN_HARDIRQ_READ))
2302 if (curr->softirq_context)
2303 if (!mark_lock(curr, hlock,
2304 LOCK_USED_IN_SOFTIRQ_READ))
2307 if (curr->hardirq_context)
2308 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2310 if (curr->softirq_context)
2311 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2315 if (!hlock->hardirqs_off) {
2317 if (!mark_lock(curr, hlock,
2318 LOCK_ENABLED_HARDIRQ_READ))
2320 if (curr->softirqs_enabled)
2321 if (!mark_lock(curr, hlock,
2322 LOCK_ENABLED_SOFTIRQ_READ))
2325 if (!mark_lock(curr, hlock,
2326 LOCK_ENABLED_HARDIRQ))
2328 if (curr->softirqs_enabled)
2329 if (!mark_lock(curr, hlock,
2330 LOCK_ENABLED_SOFTIRQ))
2336 * We reuse the irq context infrastructure more broadly as a general
2337 * context checking code. This tests GFP_FS recursion (a lock taken
2338 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2341 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2343 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2346 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2354 static int separate_irq_context(struct task_struct *curr,
2355 struct held_lock *hlock)
2357 unsigned int depth = curr->lockdep_depth;
2360 * Keep track of points where we cross into an interrupt context:
2362 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2363 curr->softirq_context;
2365 struct held_lock *prev_hlock;
2367 prev_hlock = curr->held_locks + depth-1;
2369 * If we cross into another context, reset the
2370 * hash key (this also prevents the checking and the
2371 * adding of the dependency to 'prev'):
2373 if (prev_hlock->irq_context != hlock->irq_context)
2382 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2383 enum lock_usage_bit new_bit)
2389 static inline int mark_irqflags(struct task_struct *curr,
2390 struct held_lock *hlock)
2395 static inline int separate_irq_context(struct task_struct *curr,
2396 struct held_lock *hlock)
2404 * Mark a lock with a usage bit, and validate the state transition:
2406 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2407 enum lock_usage_bit new_bit)
2409 unsigned int new_mask = 1 << new_bit, ret = 1;
2412 * If already set then do not dirty the cacheline,
2413 * nor do any checks:
2415 if (likely(hlock_class(this)->usage_mask & new_mask))
2421 * Make sure we didnt race:
2423 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2428 hlock_class(this)->usage_mask |= new_mask;
2430 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2434 #define LOCKDEP_STATE(__STATE) \
2435 case LOCK_USED_IN_##__STATE: \
2436 case LOCK_USED_IN_##__STATE##_READ: \
2437 case LOCK_ENABLED_##__STATE: \
2438 case LOCK_ENABLED_##__STATE##_READ:
2439 #include "lockdep_states.h"
2440 #undef LOCKDEP_STATE
2441 ret = mark_lock_irq(curr, this, new_bit);
2446 debug_atomic_dec(&nr_unused_locks);
2449 if (!debug_locks_off_graph_unlock())
2458 * We must printk outside of the graph_lock:
2461 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2463 print_irqtrace_events(curr);
2471 * Initialize a lock instance's lock-class mapping info:
2473 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2474 struct lock_class_key *key, int subclass)
2476 if (unlikely(!debug_locks))
2479 if (DEBUG_LOCKS_WARN_ON(!key))
2481 if (DEBUG_LOCKS_WARN_ON(!name))
2484 * Sanity check, the lock-class key must be persistent:
2486 if (!static_obj(key)) {
2487 printk("BUG: key %p not in .data!\n", key);
2488 DEBUG_LOCKS_WARN_ON(1);
2493 lock->class_cache = NULL;
2494 #ifdef CONFIG_LOCK_STAT
2495 lock->cpu = raw_smp_processor_id();
2498 register_lock_class(lock, subclass, 1);
2500 EXPORT_SYMBOL_GPL(lockdep_init_map);
2503 * This gets called for every mutex_lock*()/spin_lock*() operation.
2504 * We maintain the dependency maps and validate the locking attempt:
2506 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2507 int trylock, int read, int check, int hardirqs_off,
2508 struct lockdep_map *nest_lock, unsigned long ip)
2510 struct task_struct *curr = current;
2511 struct lock_class *class = NULL;
2512 struct held_lock *hlock;
2513 unsigned int depth, id;
2520 if (unlikely(!debug_locks))
2523 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2526 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2528 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2529 printk("turning off the locking correctness validator.\n");
2534 class = lock->class_cache;
2536 * Not cached yet or subclass?
2538 if (unlikely(!class)) {
2539 class = register_lock_class(lock, subclass, 0);
2543 debug_atomic_inc((atomic_t *)&class->ops);
2544 if (very_verbose(class)) {
2545 printk("\nacquire class [%p] %s", class->key, class->name);
2546 if (class->name_version > 1)
2547 printk("#%d", class->name_version);
2553 * Add the lock to the list of currently held locks.
2554 * (we dont increase the depth just yet, up until the
2555 * dependency checks are done)
2557 depth = curr->lockdep_depth;
2558 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2561 hlock = curr->held_locks + depth;
2562 if (DEBUG_LOCKS_WARN_ON(!class))
2564 hlock->class_idx = class - lock_classes + 1;
2565 hlock->acquire_ip = ip;
2566 hlock->instance = lock;
2567 hlock->nest_lock = nest_lock;
2568 hlock->trylock = trylock;
2570 hlock->check = check;
2571 hlock->hardirqs_off = !!hardirqs_off;
2572 #ifdef CONFIG_LOCK_STAT
2573 hlock->waittime_stamp = 0;
2574 hlock->holdtime_stamp = sched_clock();
2577 if (check == 2 && !mark_irqflags(curr, hlock))
2580 /* mark it as used: */
2581 if (!mark_lock(curr, hlock, LOCK_USED))
2585 * Calculate the chain hash: it's the combined hash of all the
2586 * lock keys along the dependency chain. We save the hash value
2587 * at every step so that we can get the current hash easily
2588 * after unlock. The chain hash is then used to cache dependency
2591 * The 'key ID' is what is the most compact key value to drive
2592 * the hash, not class->key.
2594 id = class - lock_classes;
2595 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2598 chain_key = curr->curr_chain_key;
2600 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2605 hlock->prev_chain_key = chain_key;
2606 if (separate_irq_context(curr, hlock)) {
2610 chain_key = iterate_chain_key(chain_key, id);
2612 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2615 curr->curr_chain_key = chain_key;
2616 curr->lockdep_depth++;
2617 check_chain_key(curr);
2618 #ifdef CONFIG_DEBUG_LOCKDEP
2619 if (unlikely(!debug_locks))
2622 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2624 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2625 printk("turning off the locking correctness validator.\n");
2629 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2630 max_lockdep_depth = curr->lockdep_depth;
2636 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2639 if (!debug_locks_off())
2641 if (debug_locks_silent)
2644 printk("\n=====================================\n");
2645 printk( "[ BUG: bad unlock balance detected! ]\n");
2646 printk( "-------------------------------------\n");
2647 printk("%s/%d is trying to release lock (",
2648 curr->comm, task_pid_nr(curr));
2649 print_lockdep_cache(lock);
2652 printk("but there are no more locks to release!\n");
2653 printk("\nother info that might help us debug this:\n");
2654 lockdep_print_held_locks(curr);
2656 printk("\nstack backtrace:\n");
2663 * Common debugging checks for both nested and non-nested unlock:
2665 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2668 if (unlikely(!debug_locks))
2670 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2673 if (curr->lockdep_depth <= 0)
2674 return print_unlock_inbalance_bug(curr, lock, ip);
2680 __lock_set_class(struct lockdep_map *lock, const char *name,
2681 struct lock_class_key *key, unsigned int subclass,
2684 struct task_struct *curr = current;
2685 struct held_lock *hlock, *prev_hlock;
2686 struct lock_class *class;
2690 depth = curr->lockdep_depth;
2691 if (DEBUG_LOCKS_WARN_ON(!depth))
2695 for (i = depth-1; i >= 0; i--) {
2696 hlock = curr->held_locks + i;
2698 * We must not cross into another context:
2700 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2702 if (hlock->instance == lock)
2706 return print_unlock_inbalance_bug(curr, lock, ip);
2709 lockdep_init_map(lock, name, key, 0);
2710 class = register_lock_class(lock, subclass, 0);
2711 hlock->class_idx = class - lock_classes + 1;
2713 curr->lockdep_depth = i;
2714 curr->curr_chain_key = hlock->prev_chain_key;
2716 for (; i < depth; i++) {
2717 hlock = curr->held_locks + i;
2718 if (!__lock_acquire(hlock->instance,
2719 hlock_class(hlock)->subclass, hlock->trylock,
2720 hlock->read, hlock->check, hlock->hardirqs_off,
2721 hlock->nest_lock, hlock->acquire_ip))
2725 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2731 * Remove the lock to the list of currently held locks in a
2732 * potentially non-nested (out of order) manner. This is a
2733 * relatively rare operation, as all the unlock APIs default
2734 * to nested mode (which uses lock_release()):
2737 lock_release_non_nested(struct task_struct *curr,
2738 struct lockdep_map *lock, unsigned long ip)
2740 struct held_lock *hlock, *prev_hlock;
2745 * Check whether the lock exists in the current stack
2748 depth = curr->lockdep_depth;
2749 if (DEBUG_LOCKS_WARN_ON(!depth))
2753 for (i = depth-1; i >= 0; i--) {
2754 hlock = curr->held_locks + i;
2756 * We must not cross into another context:
2758 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2760 if (hlock->instance == lock)
2764 return print_unlock_inbalance_bug(curr, lock, ip);
2767 lock_release_holdtime(hlock);
2770 * We have the right lock to unlock, 'hlock' points to it.
2771 * Now we remove it from the stack, and add back the other
2772 * entries (if any), recalculating the hash along the way:
2774 curr->lockdep_depth = i;
2775 curr->curr_chain_key = hlock->prev_chain_key;
2777 for (i++; i < depth; i++) {
2778 hlock = curr->held_locks + i;
2779 if (!__lock_acquire(hlock->instance,
2780 hlock_class(hlock)->subclass, hlock->trylock,
2781 hlock->read, hlock->check, hlock->hardirqs_off,
2782 hlock->nest_lock, hlock->acquire_ip))
2786 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2792 * Remove the lock to the list of currently held locks - this gets
2793 * called on mutex_unlock()/spin_unlock*() (or on a failed
2794 * mutex_lock_interruptible()). This is done for unlocks that nest
2795 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2797 static int lock_release_nested(struct task_struct *curr,
2798 struct lockdep_map *lock, unsigned long ip)
2800 struct held_lock *hlock;
2804 * Pop off the top of the lock stack:
2806 depth = curr->lockdep_depth - 1;
2807 hlock = curr->held_locks + depth;
2810 * Is the unlock non-nested:
2812 if (hlock->instance != lock)
2813 return lock_release_non_nested(curr, lock, ip);
2814 curr->lockdep_depth--;
2816 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2819 curr->curr_chain_key = hlock->prev_chain_key;
2821 lock_release_holdtime(hlock);
2823 #ifdef CONFIG_DEBUG_LOCKDEP
2824 hlock->prev_chain_key = 0;
2825 hlock->class_idx = 0;
2826 hlock->acquire_ip = 0;
2827 hlock->irq_context = 0;
2833 * Remove the lock to the list of currently held locks - this gets
2834 * called on mutex_unlock()/spin_unlock*() (or on a failed
2835 * mutex_lock_interruptible()). This is done for unlocks that nest
2836 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2839 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2841 struct task_struct *curr = current;
2843 if (!check_unlock(curr, lock, ip))
2847 if (!lock_release_nested(curr, lock, ip))
2850 if (!lock_release_non_nested(curr, lock, ip))
2854 check_chain_key(curr);
2858 * Check whether we follow the irq-flags state precisely:
2860 static void check_flags(unsigned long flags)
2862 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2863 defined(CONFIG_TRACE_IRQFLAGS)
2867 if (irqs_disabled_flags(flags)) {
2868 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
2869 printk("possible reason: unannotated irqs-off.\n");
2872 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
2873 printk("possible reason: unannotated irqs-on.\n");
2878 * We dont accurately track softirq state in e.g.
2879 * hardirq contexts (such as on 4KSTACKS), so only
2880 * check if not in hardirq contexts:
2882 if (!hardirq_count()) {
2883 if (softirq_count())
2884 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2886 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2890 print_irqtrace_events(current);
2894 void lock_set_class(struct lockdep_map *lock, const char *name,
2895 struct lock_class_key *key, unsigned int subclass,
2898 unsigned long flags;
2900 if (unlikely(current->lockdep_recursion))
2903 raw_local_irq_save(flags);
2904 current->lockdep_recursion = 1;
2906 if (__lock_set_class(lock, name, key, subclass, ip))
2907 check_chain_key(current);
2908 current->lockdep_recursion = 0;
2909 raw_local_irq_restore(flags);
2911 EXPORT_SYMBOL_GPL(lock_set_class);
2914 * We are not always called with irqs disabled - do that here,
2915 * and also avoid lockdep recursion:
2917 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2918 int trylock, int read, int check,
2919 struct lockdep_map *nest_lock, unsigned long ip)
2921 unsigned long flags;
2923 if (unlikely(current->lockdep_recursion))
2926 raw_local_irq_save(flags);
2929 current->lockdep_recursion = 1;
2930 __lock_acquire(lock, subclass, trylock, read, check,
2931 irqs_disabled_flags(flags), nest_lock, ip);
2932 current->lockdep_recursion = 0;
2933 raw_local_irq_restore(flags);
2935 EXPORT_SYMBOL_GPL(lock_acquire);
2937 void lock_release(struct lockdep_map *lock, int nested,
2940 unsigned long flags;
2942 if (unlikely(current->lockdep_recursion))
2945 raw_local_irq_save(flags);
2947 current->lockdep_recursion = 1;
2948 __lock_release(lock, nested, ip);
2949 current->lockdep_recursion = 0;
2950 raw_local_irq_restore(flags);
2952 EXPORT_SYMBOL_GPL(lock_release);
2954 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
2956 current->lockdep_reclaim_gfp = gfp_mask;
2959 void lockdep_clear_current_reclaim_state(void)
2961 current->lockdep_reclaim_gfp = 0;
2964 #ifdef CONFIG_LOCK_STAT
2966 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
2969 if (!debug_locks_off())
2971 if (debug_locks_silent)
2974 printk("\n=================================\n");
2975 printk( "[ BUG: bad contention detected! ]\n");
2976 printk( "---------------------------------\n");
2977 printk("%s/%d is trying to contend lock (",
2978 curr->comm, task_pid_nr(curr));
2979 print_lockdep_cache(lock);
2982 printk("but there are no locks held!\n");
2983 printk("\nother info that might help us debug this:\n");
2984 lockdep_print_held_locks(curr);
2986 printk("\nstack backtrace:\n");
2993 __lock_contended(struct lockdep_map *lock, unsigned long ip)
2995 struct task_struct *curr = current;
2996 struct held_lock *hlock, *prev_hlock;
2997 struct lock_class_stats *stats;
2999 int i, contention_point, contending_point;
3001 depth = curr->lockdep_depth;
3002 if (DEBUG_LOCKS_WARN_ON(!depth))
3006 for (i = depth-1; i >= 0; i--) {
3007 hlock = curr->held_locks + i;
3009 * We must not cross into another context:
3011 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3013 if (hlock->instance == lock)
3017 print_lock_contention_bug(curr, lock, ip);
3021 hlock->waittime_stamp = sched_clock();
3023 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3024 contending_point = lock_point(hlock_class(hlock)->contending_point,
3027 stats = get_lock_stats(hlock_class(hlock));
3028 if (contention_point < LOCKSTAT_POINTS)
3029 stats->contention_point[contention_point]++;
3030 if (contending_point < LOCKSTAT_POINTS)
3031 stats->contending_point[contending_point]++;
3032 if (lock->cpu != smp_processor_id())
3033 stats->bounces[bounce_contended + !!hlock->read]++;
3034 put_lock_stats(stats);
3038 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3040 struct task_struct *curr = current;
3041 struct held_lock *hlock, *prev_hlock;
3042 struct lock_class_stats *stats;
3048 depth = curr->lockdep_depth;
3049 if (DEBUG_LOCKS_WARN_ON(!depth))
3053 for (i = depth-1; i >= 0; i--) {
3054 hlock = curr->held_locks + i;
3056 * We must not cross into another context:
3058 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3060 if (hlock->instance == lock)
3064 print_lock_contention_bug(curr, lock, _RET_IP_);
3068 cpu = smp_processor_id();
3069 if (hlock->waittime_stamp) {
3070 now = sched_clock();
3071 waittime = now - hlock->waittime_stamp;
3072 hlock->holdtime_stamp = now;
3075 stats = get_lock_stats(hlock_class(hlock));
3078 lock_time_inc(&stats->read_waittime, waittime);
3080 lock_time_inc(&stats->write_waittime, waittime);
3082 if (lock->cpu != cpu)
3083 stats->bounces[bounce_acquired + !!hlock->read]++;
3084 put_lock_stats(stats);
3090 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3092 unsigned long flags;
3094 if (unlikely(!lock_stat))
3097 if (unlikely(current->lockdep_recursion))
3100 raw_local_irq_save(flags);
3102 current->lockdep_recursion = 1;
3103 __lock_contended(lock, ip);
3104 current->lockdep_recursion = 0;
3105 raw_local_irq_restore(flags);
3107 EXPORT_SYMBOL_GPL(lock_contended);
3109 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3111 unsigned long flags;
3113 if (unlikely(!lock_stat))
3116 if (unlikely(current->lockdep_recursion))
3119 raw_local_irq_save(flags);
3121 current->lockdep_recursion = 1;
3122 __lock_acquired(lock, ip);
3123 current->lockdep_recursion = 0;
3124 raw_local_irq_restore(flags);
3126 EXPORT_SYMBOL_GPL(lock_acquired);
3130 * Used by the testsuite, sanitize the validator state
3131 * after a simulated failure:
3134 void lockdep_reset(void)
3136 unsigned long flags;
3139 raw_local_irq_save(flags);
3140 current->curr_chain_key = 0;
3141 current->lockdep_depth = 0;
3142 current->lockdep_recursion = 0;
3143 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3144 nr_hardirq_chains = 0;
3145 nr_softirq_chains = 0;
3146 nr_process_chains = 0;
3148 for (i = 0; i < CHAINHASH_SIZE; i++)
3149 INIT_LIST_HEAD(chainhash_table + i);
3150 raw_local_irq_restore(flags);
3153 static void zap_class(struct lock_class *class)
3158 * Remove all dependencies this lock is
3161 for (i = 0; i < nr_list_entries; i++) {
3162 if (list_entries[i].class == class)
3163 list_del_rcu(&list_entries[i].entry);
3166 * Unhash the class and remove it from the all_lock_classes list:
3168 list_del_rcu(&class->hash_entry);
3169 list_del_rcu(&class->lock_entry);
3174 static inline int within(const void *addr, void *start, unsigned long size)
3176 return addr >= start && addr < start + size;
3179 void lockdep_free_key_range(void *start, unsigned long size)
3181 struct lock_class *class, *next;
3182 struct list_head *head;
3183 unsigned long flags;
3187 raw_local_irq_save(flags);
3188 locked = graph_lock();
3191 * Unhash all classes that were created by this module:
3193 for (i = 0; i < CLASSHASH_SIZE; i++) {
3194 head = classhash_table + i;
3195 if (list_empty(head))
3197 list_for_each_entry_safe(class, next, head, hash_entry) {
3198 if (within(class->key, start, size))
3200 else if (within(class->name, start, size))
3207 raw_local_irq_restore(flags);
3210 void lockdep_reset_lock(struct lockdep_map *lock)
3212 struct lock_class *class, *next;
3213 struct list_head *head;
3214 unsigned long flags;
3218 raw_local_irq_save(flags);
3221 * Remove all classes this lock might have:
3223 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3225 * If the class exists we look it up and zap it:
3227 class = look_up_lock_class(lock, j);
3232 * Debug check: in the end all mapped classes should
3235 locked = graph_lock();
3236 for (i = 0; i < CLASSHASH_SIZE; i++) {
3237 head = classhash_table + i;
3238 if (list_empty(head))
3240 list_for_each_entry_safe(class, next, head, hash_entry) {
3241 if (unlikely(class == lock->class_cache)) {
3242 if (debug_locks_off_graph_unlock())
3252 raw_local_irq_restore(flags);
3255 void lockdep_init(void)
3260 * Some architectures have their own start_kernel()
3261 * code which calls lockdep_init(), while we also
3262 * call lockdep_init() from the start_kernel() itself,
3263 * and we want to initialize the hashes only once:
3265 if (lockdep_initialized)
3268 for (i = 0; i < CLASSHASH_SIZE; i++)
3269 INIT_LIST_HEAD(classhash_table + i);
3271 for (i = 0; i < CHAINHASH_SIZE; i++)
3272 INIT_LIST_HEAD(chainhash_table + i);
3274 lockdep_initialized = 1;
3277 void __init lockdep_info(void)
3279 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3281 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3282 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3283 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3284 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3285 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3286 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3287 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3289 printk(" memory used by lock dependency info: %lu kB\n",
3290 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3291 sizeof(struct list_head) * CLASSHASH_SIZE +
3292 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3293 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3294 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
3296 printk(" per task-struct memory footprint: %lu bytes\n",
3297 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3299 #ifdef CONFIG_DEBUG_LOCKDEP
3300 if (lockdep_init_error) {
3301 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3302 printk("Call stack leading to lockdep invocation was:\n");
3303 print_stack_trace(&lockdep_init_trace, 0);
3309 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3310 const void *mem_to, struct held_lock *hlock)
3312 if (!debug_locks_off())
3314 if (debug_locks_silent)
3317 printk("\n=========================\n");
3318 printk( "[ BUG: held lock freed! ]\n");
3319 printk( "-------------------------\n");
3320 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3321 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3323 lockdep_print_held_locks(curr);
3325 printk("\nstack backtrace:\n");
3329 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3330 const void* lock_from, unsigned long lock_len)
3332 return lock_from + lock_len <= mem_from ||
3333 mem_from + mem_len <= lock_from;
3337 * Called when kernel memory is freed (or unmapped), or if a lock
3338 * is destroyed or reinitialized - this code checks whether there is
3339 * any held lock in the memory range of <from> to <to>:
3341 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3343 struct task_struct *curr = current;
3344 struct held_lock *hlock;
3345 unsigned long flags;
3348 if (unlikely(!debug_locks))
3351 local_irq_save(flags);
3352 for (i = 0; i < curr->lockdep_depth; i++) {
3353 hlock = curr->held_locks + i;
3355 if (not_in_range(mem_from, mem_len, hlock->instance,
3356 sizeof(*hlock->instance)))
3359 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3362 local_irq_restore(flags);
3364 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3366 static void print_held_locks_bug(struct task_struct *curr)
3368 if (!debug_locks_off())
3370 if (debug_locks_silent)
3373 printk("\n=====================================\n");
3374 printk( "[ BUG: lock held at task exit time! ]\n");
3375 printk( "-------------------------------------\n");
3376 printk("%s/%d is exiting with locks still held!\n",
3377 curr->comm, task_pid_nr(curr));
3378 lockdep_print_held_locks(curr);
3380 printk("\nstack backtrace:\n");
3384 void debug_check_no_locks_held(struct task_struct *task)
3386 if (unlikely(task->lockdep_depth > 0))
3387 print_held_locks_bug(task);
3390 void debug_show_all_locks(void)
3392 struct task_struct *g, *p;
3396 if (unlikely(!debug_locks)) {
3397 printk("INFO: lockdep is turned off.\n");
3400 printk("\nShowing all locks held in the system:\n");
3403 * Here we try to get the tasklist_lock as hard as possible,
3404 * if not successful after 2 seconds we ignore it (but keep
3405 * trying). This is to enable a debug printout even if a
3406 * tasklist_lock-holding task deadlocks or crashes.
3409 if (!read_trylock(&tasklist_lock)) {
3411 printk("hm, tasklist_lock locked, retrying... ");
3414 printk(" #%d", 10-count);
3418 printk(" ignoring it.\n");
3422 printk(KERN_CONT " locked it.\n");
3425 do_each_thread(g, p) {
3427 * It's not reliable to print a task's held locks
3428 * if it's not sleeping (or if it's not the current
3431 if (p->state == TASK_RUNNING && p != current)
3433 if (p->lockdep_depth)
3434 lockdep_print_held_locks(p);
3436 if (read_trylock(&tasklist_lock))
3438 } while_each_thread(g, p);
3441 printk("=============================================\n\n");
3444 read_unlock(&tasklist_lock);
3446 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3449 * Careful: only use this function if you are sure that
3450 * the task cannot run in parallel!
3452 void __debug_show_held_locks(struct task_struct *task)
3454 if (unlikely(!debug_locks)) {
3455 printk("INFO: lockdep is turned off.\n");
3458 lockdep_print_held_locks(task);
3460 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3462 void debug_show_held_locks(struct task_struct *task)
3464 __debug_show_held_locks(task);
3466 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3468 void lockdep_sys_exit(void)
3470 struct task_struct *curr = current;
3472 if (unlikely(curr->lockdep_depth)) {
3473 if (!debug_locks_off())
3475 printk("\n================================================\n");
3476 printk( "[ BUG: lock held when returning to user space! ]\n");
3477 printk( "------------------------------------------------\n");
3478 printk("%s/%d is leaving the kernel with locks still held!\n",
3479 curr->comm, curr->pid);
3480 lockdep_print_held_locks(curr);