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>
46 #include <asm/sections.h>
48 #include "lockdep_internals.h"
50 #ifdef CONFIG_PROVE_LOCKING
51 int prove_locking = 1;
52 module_param(prove_locking, int, 0644);
54 #define prove_locking 0
57 #ifdef CONFIG_LOCK_STAT
59 module_param(lock_stat, int, 0644);
65 * lockdep_lock: protects the lockdep graph, the hashes and the
66 * class/list/hash allocators.
68 * This is one of the rare exceptions where it's justified
69 * to use a raw spinlock - we really dont want the spinlock
70 * code to recurse back into the lockdep code...
72 static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
74 static int graph_lock(void)
76 __raw_spin_lock(&lockdep_lock);
78 * Make sure that if another CPU detected a bug while
79 * walking the graph we dont change it (while the other
80 * CPU is busy printing out stuff with the graph lock
84 __raw_spin_unlock(&lockdep_lock);
87 /* prevent any recursions within lockdep from causing deadlocks */
88 current->lockdep_recursion++;
92 static inline int graph_unlock(void)
94 if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
95 return DEBUG_LOCKS_WARN_ON(1);
97 current->lockdep_recursion--;
98 __raw_spin_unlock(&lockdep_lock);
103 * Turn lock debugging off and return with 0 if it was off already,
104 * and also release the graph lock:
106 static inline int debug_locks_off_graph_unlock(void)
108 int ret = debug_locks_off();
110 __raw_spin_unlock(&lockdep_lock);
115 static int lockdep_initialized;
117 unsigned long nr_list_entries;
118 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
121 * All data structures here are protected by the global debug_lock.
123 * Mutex key structs only get allocated, once during bootup, and never
124 * get freed - this significantly simplifies the debugging code.
126 unsigned long nr_lock_classes;
127 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
129 static inline struct lock_class *hlock_class(struct held_lock *hlock)
131 if (!hlock->class_idx) {
132 DEBUG_LOCKS_WARN_ON(1);
135 return lock_classes + hlock->class_idx - 1;
138 #ifdef CONFIG_LOCK_STAT
139 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
141 static int lock_point(unsigned long points[], unsigned long ip)
145 for (i = 0; i < LOCKSTAT_POINTS; i++) {
146 if (points[i] == 0) {
157 static void lock_time_inc(struct lock_time *lt, s64 time)
162 if (time < lt->min || !lt->min)
169 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
171 dst->min += src->min;
172 dst->max += src->max;
173 dst->total += src->total;
177 struct lock_class_stats lock_stats(struct lock_class *class)
179 struct lock_class_stats stats;
182 memset(&stats, 0, sizeof(struct lock_class_stats));
183 for_each_possible_cpu(cpu) {
184 struct lock_class_stats *pcs =
185 &per_cpu(lock_stats, cpu)[class - lock_classes];
187 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
188 stats.contention_point[i] += pcs->contention_point[i];
190 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
191 stats.contending_point[i] += pcs->contending_point[i];
193 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
194 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
196 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
197 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
199 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
200 stats.bounces[i] += pcs->bounces[i];
206 void clear_lock_stats(struct lock_class *class)
210 for_each_possible_cpu(cpu) {
211 struct lock_class_stats *cpu_stats =
212 &per_cpu(lock_stats, cpu)[class - lock_classes];
214 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
216 memset(class->contention_point, 0, sizeof(class->contention_point));
217 memset(class->contending_point, 0, sizeof(class->contending_point));
220 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
222 return &get_cpu_var(lock_stats)[class - lock_classes];
225 static void put_lock_stats(struct lock_class_stats *stats)
227 put_cpu_var(lock_stats);
230 static void lock_release_holdtime(struct held_lock *hlock)
232 struct lock_class_stats *stats;
238 holdtime = sched_clock() - hlock->holdtime_stamp;
240 stats = get_lock_stats(hlock_class(hlock));
242 lock_time_inc(&stats->read_holdtime, holdtime);
244 lock_time_inc(&stats->write_holdtime, holdtime);
245 put_lock_stats(stats);
248 static inline void lock_release_holdtime(struct held_lock *hlock)
254 * We keep a global list of all lock classes. The list only grows,
255 * never shrinks. The list is only accessed with the lockdep
256 * spinlock lock held.
258 LIST_HEAD(all_lock_classes);
261 * The lockdep classes are in a hash-table as well, for fast lookup:
263 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
264 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
265 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
266 #define classhashentry(key) (classhash_table + __classhashfn((key)))
268 static struct list_head classhash_table[CLASSHASH_SIZE];
271 * We put the lock dependency chains into a hash-table as well, to cache
274 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
275 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
276 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
277 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
279 static struct list_head chainhash_table[CHAINHASH_SIZE];
282 * The hash key of the lock dependency chains is a hash itself too:
283 * it's a hash of all locks taken up to that lock, including that lock.
284 * It's a 64-bit hash, because it's important for the keys to be
287 #define iterate_chain_key(key1, key2) \
288 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
289 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
292 void lockdep_off(void)
294 current->lockdep_recursion++;
296 EXPORT_SYMBOL(lockdep_off);
298 void lockdep_on(void)
300 current->lockdep_recursion--;
302 EXPORT_SYMBOL(lockdep_on);
305 * Debugging switches:
309 #define VERY_VERBOSE 0
312 # define HARDIRQ_VERBOSE 1
313 # define SOFTIRQ_VERBOSE 1
314 # define RECLAIM_VERBOSE 1
316 # define HARDIRQ_VERBOSE 0
317 # define SOFTIRQ_VERBOSE 0
318 # define RECLAIM_VERBOSE 0
321 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
323 * Quick filtering for interesting events:
325 static int class_filter(struct lock_class *class)
329 if (class->name_version == 1 &&
330 !strcmp(class->name, "lockname"))
332 if (class->name_version == 1 &&
333 !strcmp(class->name, "&struct->lockfield"))
336 /* Filter everything else. 1 would be to allow everything else */
341 static int verbose(struct lock_class *class)
344 return class_filter(class);
350 * Stack-trace: tightly packed array of stack backtrace
351 * addresses. Protected by the graph_lock.
353 unsigned long nr_stack_trace_entries;
354 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
356 static int save_trace(struct stack_trace *trace)
358 trace->nr_entries = 0;
359 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
360 trace->entries = stack_trace + nr_stack_trace_entries;
364 save_stack_trace(trace);
366 trace->max_entries = trace->nr_entries;
368 nr_stack_trace_entries += trace->nr_entries;
370 if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
371 if (!debug_locks_off_graph_unlock())
374 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
375 printk("turning off the locking correctness validator.\n");
384 unsigned int nr_hardirq_chains;
385 unsigned int nr_softirq_chains;
386 unsigned int nr_process_chains;
387 unsigned int max_lockdep_depth;
388 unsigned int max_recursion_depth;
390 static unsigned int lockdep_dependency_gen_id;
392 static bool lockdep_dependency_visit(struct lock_class *source,
396 lockdep_dependency_gen_id++;
397 if (source->dep_gen_id == lockdep_dependency_gen_id)
399 source->dep_gen_id = lockdep_dependency_gen_id;
403 #ifdef CONFIG_DEBUG_LOCKDEP
405 * We cannot printk in early bootup code. Not even early_printk()
406 * might work. So we mark any initialization errors and printk
407 * about it later on, in lockdep_info().
409 static int lockdep_init_error;
410 static unsigned long lockdep_init_trace_data[20];
411 static struct stack_trace lockdep_init_trace = {
412 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
413 .entries = lockdep_init_trace_data,
417 * Various lockdep statistics:
419 atomic_t chain_lookup_hits;
420 atomic_t chain_lookup_misses;
421 atomic_t hardirqs_on_events;
422 atomic_t hardirqs_off_events;
423 atomic_t redundant_hardirqs_on;
424 atomic_t redundant_hardirqs_off;
425 atomic_t softirqs_on_events;
426 atomic_t softirqs_off_events;
427 atomic_t redundant_softirqs_on;
428 atomic_t redundant_softirqs_off;
429 atomic_t nr_unused_locks;
430 atomic_t nr_cyclic_checks;
431 atomic_t nr_cyclic_check_recursions;
432 atomic_t nr_find_usage_forwards_checks;
433 atomic_t nr_find_usage_forwards_recursions;
434 atomic_t nr_find_usage_backwards_checks;
435 atomic_t nr_find_usage_backwards_recursions;
442 #define __USAGE(__STATE) \
443 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
444 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
445 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
446 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
448 static const char *usage_str[] =
450 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
451 #include "lockdep_states.h"
453 [LOCK_USED] = "INITIAL USE",
456 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
458 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
461 static inline unsigned long lock_flag(enum lock_usage_bit bit)
466 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
470 if (class->usage_mask & lock_flag(bit + 2))
472 if (class->usage_mask & lock_flag(bit)) {
474 if (class->usage_mask & lock_flag(bit + 2))
481 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
485 #define LOCKDEP_STATE(__STATE) \
486 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
487 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
488 #include "lockdep_states.h"
494 static void print_lock_name(struct lock_class *class)
496 char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
499 get_usage_chars(class, usage);
503 name = __get_key_name(class->key, str);
504 printk(" (%s", name);
506 printk(" (%s", name);
507 if (class->name_version > 1)
508 printk("#%d", class->name_version);
510 printk("/%d", class->subclass);
512 printk("){%s}", usage);
515 static void print_lockdep_cache(struct lockdep_map *lock)
518 char str[KSYM_NAME_LEN];
522 name = __get_key_name(lock->key->subkeys, str);
527 static void print_lock(struct held_lock *hlock)
529 print_lock_name(hlock_class(hlock));
531 print_ip_sym(hlock->acquire_ip);
534 static void lockdep_print_held_locks(struct task_struct *curr)
536 int i, depth = curr->lockdep_depth;
539 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
542 printk("%d lock%s held by %s/%d:\n",
543 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
545 for (i = 0; i < depth; i++) {
547 print_lock(curr->held_locks + i);
551 static void print_lock_class_header(struct lock_class *class, int depth)
555 printk("%*s->", depth, "");
556 print_lock_name(class);
557 printk(" ops: %lu", class->ops);
560 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
561 if (class->usage_mask & (1 << bit)) {
564 len += printk("%*s %s", depth, "", usage_str[bit]);
565 len += printk(" at:\n");
566 print_stack_trace(class->usage_traces + bit, len);
569 printk("%*s }\n", depth, "");
571 printk("%*s ... key at: ",depth,"");
572 print_ip_sym((unsigned long)class->key);
576 * printk all lock dependencies starting at <entry>:
579 print_lock_dependencies(struct lock_class *class, int depth)
581 struct lock_list *entry;
583 if (lockdep_dependency_visit(class, depth))
586 if (DEBUG_LOCKS_WARN_ON(depth >= 20))
589 print_lock_class_header(class, depth);
591 list_for_each_entry(entry, &class->locks_after, entry) {
592 if (DEBUG_LOCKS_WARN_ON(!entry->class))
595 print_lock_dependencies(entry->class, depth + 1);
597 printk("%*s ... acquired at:\n",depth,"");
598 print_stack_trace(&entry->trace, 2);
603 static void print_kernel_version(void)
605 printk("%s %.*s\n", init_utsname()->release,
606 (int)strcspn(init_utsname()->version, " "),
607 init_utsname()->version);
610 static int very_verbose(struct lock_class *class)
613 return class_filter(class);
619 * Is this the address of a static object:
621 static int static_obj(void *obj)
623 unsigned long start = (unsigned long) &_stext,
624 end = (unsigned long) &_end,
625 addr = (unsigned long) obj;
633 if ((addr >= start) && (addr < end))
640 for_each_possible_cpu(i) {
641 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
642 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
645 if ((addr >= start) && (addr < end))
653 return is_module_address(addr);
657 * To make lock name printouts unique, we calculate a unique
658 * class->name_version generation counter:
660 static int count_matching_names(struct lock_class *new_class)
662 struct lock_class *class;
665 if (!new_class->name)
668 list_for_each_entry(class, &all_lock_classes, lock_entry) {
669 if (new_class->key - new_class->subclass == class->key)
670 return class->name_version;
671 if (class->name && !strcmp(class->name, new_class->name))
672 count = max(count, class->name_version);
679 * Register a lock's class in the hash-table, if the class is not present
680 * yet. Otherwise we look it up. We cache the result in the lock object
681 * itself, so actual lookup of the hash should be once per lock object.
683 static inline struct lock_class *
684 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
686 struct lockdep_subclass_key *key;
687 struct list_head *hash_head;
688 struct lock_class *class;
690 #ifdef CONFIG_DEBUG_LOCKDEP
692 * If the architecture calls into lockdep before initializing
693 * the hashes then we'll warn about it later. (we cannot printk
696 if (unlikely(!lockdep_initialized)) {
698 lockdep_init_error = 1;
699 save_stack_trace(&lockdep_init_trace);
704 * Static locks do not have their class-keys yet - for them the key
705 * is the lock object itself:
707 if (unlikely(!lock->key))
708 lock->key = (void *)lock;
711 * NOTE: the class-key must be unique. For dynamic locks, a static
712 * lock_class_key variable is passed in through the mutex_init()
713 * (or spin_lock_init()) call - which acts as the key. For static
714 * locks we use the lock object itself as the key.
716 BUILD_BUG_ON(sizeof(struct lock_class_key) >
717 sizeof(struct lockdep_map));
719 key = lock->key->subkeys + subclass;
721 hash_head = classhashentry(key);
724 * We can walk the hash lockfree, because the hash only
725 * grows, and we are careful when adding entries to the end:
727 list_for_each_entry(class, hash_head, hash_entry) {
728 if (class->key == key) {
729 WARN_ON_ONCE(class->name != lock->name);
738 * Register a lock's class in the hash-table, if the class is not present
739 * yet. Otherwise we look it up. We cache the result in the lock object
740 * itself, so actual lookup of the hash should be once per lock object.
742 static inline struct lock_class *
743 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
745 struct lockdep_subclass_key *key;
746 struct list_head *hash_head;
747 struct lock_class *class;
750 class = look_up_lock_class(lock, subclass);
755 * Debug-check: all keys must be persistent!
757 if (!static_obj(lock->key)) {
759 printk("INFO: trying to register non-static key.\n");
760 printk("the code is fine but needs lockdep annotation.\n");
761 printk("turning off the locking correctness validator.\n");
767 key = lock->key->subkeys + subclass;
768 hash_head = classhashentry(key);
770 raw_local_irq_save(flags);
772 raw_local_irq_restore(flags);
776 * We have to do the hash-walk again, to avoid races
779 list_for_each_entry(class, hash_head, hash_entry)
780 if (class->key == key)
783 * Allocate a new key from the static array, and add it to
786 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
787 if (!debug_locks_off_graph_unlock()) {
788 raw_local_irq_restore(flags);
791 raw_local_irq_restore(flags);
793 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
794 printk("turning off the locking correctness validator.\n");
798 class = lock_classes + nr_lock_classes++;
799 debug_atomic_inc(&nr_unused_locks);
801 class->name = lock->name;
802 class->subclass = subclass;
803 INIT_LIST_HEAD(&class->lock_entry);
804 INIT_LIST_HEAD(&class->locks_before);
805 INIT_LIST_HEAD(&class->locks_after);
806 class->name_version = count_matching_names(class);
808 * We use RCU's safe list-add method to make
809 * parallel walking of the hash-list safe:
811 list_add_tail_rcu(&class->hash_entry, hash_head);
813 * Add it to the global list of classes:
815 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
817 if (verbose(class)) {
819 raw_local_irq_restore(flags);
821 printk("\nnew class %p: %s", class->key, class->name);
822 if (class->name_version > 1)
823 printk("#%d", class->name_version);
827 raw_local_irq_save(flags);
829 raw_local_irq_restore(flags);
835 raw_local_irq_restore(flags);
837 if (!subclass || force)
838 lock->class_cache = class;
840 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
846 #ifdef CONFIG_PROVE_LOCKING
848 * Allocate a lockdep entry. (assumes the graph_lock held, returns
849 * with NULL on failure)
851 static struct lock_list *alloc_list_entry(void)
853 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
854 if (!debug_locks_off_graph_unlock())
857 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
858 printk("turning off the locking correctness validator.\n");
862 return list_entries + nr_list_entries++;
866 * Add a new dependency to the head of the list:
868 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
869 struct list_head *head, unsigned long ip, int distance)
871 struct lock_list *entry;
873 * Lock not present yet - get a new dependency struct and
874 * add it to the list:
876 entry = alloc_list_entry();
880 if (!save_trace(&entry->trace))
884 entry->distance = distance;
886 * Since we never remove from the dependency list, the list can
887 * be walked lockless by other CPUs, it's only allocation
888 * that must be protected by the spinlock. But this also means
889 * we must make new entries visible only once writes to the
890 * entry become visible - hence the RCU op:
892 list_add_tail_rcu(&entry->entry, head);
898 * Recursive, forwards-direction lock-dependency checking, used for
899 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
902 * (to keep the stackframe of the recursive functions small we
903 * use these global variables, and we also mark various helper
904 * functions as noinline.)
906 static struct held_lock *check_source, *check_target;
909 * Print a dependency chain entry (this is only done when a deadlock
910 * has been detected):
913 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
915 if (debug_locks_silent)
917 printk("\n-> #%u", depth);
918 print_lock_name(target->class);
920 print_stack_trace(&target->trace, 6);
926 * When a circular dependency is detected, print the
930 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
932 struct task_struct *curr = current;
934 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
937 printk("\n=======================================================\n");
938 printk( "[ INFO: possible circular locking dependency detected ]\n");
939 print_kernel_version();
940 printk( "-------------------------------------------------------\n");
941 printk("%s/%d is trying to acquire lock:\n",
942 curr->comm, task_pid_nr(curr));
943 print_lock(check_source);
944 printk("\nbut task is already holding lock:\n");
945 print_lock(check_target);
946 printk("\nwhich lock already depends on the new lock.\n\n");
947 printk("\nthe existing dependency chain (in reverse order) is:\n");
949 print_circular_bug_entry(entry, depth);
954 static noinline int print_circular_bug_tail(void)
956 struct task_struct *curr = current;
957 struct lock_list this;
959 if (debug_locks_silent)
962 this.class = hlock_class(check_source);
963 if (!save_trace(&this.trace))
966 print_circular_bug_entry(&this, 0);
968 printk("\nother info that might help us debug this:\n\n");
969 lockdep_print_held_locks(curr);
971 printk("\nstack backtrace:\n");
977 #define RECURSION_LIMIT 40
979 static int noinline print_infinite_recursion_bug(void)
981 if (!debug_locks_off_graph_unlock())
989 unsigned long __lockdep_count_forward_deps(struct lock_class *class,
992 struct lock_list *entry;
993 unsigned long ret = 1;
995 if (lockdep_dependency_visit(class, depth))
999 * Recurse this class's dependency list:
1001 list_for_each_entry(entry, &class->locks_after, entry)
1002 ret += __lockdep_count_forward_deps(entry->class, depth + 1);
1007 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1009 unsigned long ret, flags;
1011 local_irq_save(flags);
1012 __raw_spin_lock(&lockdep_lock);
1013 ret = __lockdep_count_forward_deps(class, 0);
1014 __raw_spin_unlock(&lockdep_lock);
1015 local_irq_restore(flags);
1020 unsigned long __lockdep_count_backward_deps(struct lock_class *class,
1023 struct lock_list *entry;
1024 unsigned long ret = 1;
1026 if (lockdep_dependency_visit(class, depth))
1029 * Recurse this class's dependency list:
1031 list_for_each_entry(entry, &class->locks_before, entry)
1032 ret += __lockdep_count_backward_deps(entry->class, depth + 1);
1037 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1039 unsigned long ret, flags;
1041 local_irq_save(flags);
1042 __raw_spin_lock(&lockdep_lock);
1043 ret = __lockdep_count_backward_deps(class, 0);
1044 __raw_spin_unlock(&lockdep_lock);
1045 local_irq_restore(flags);
1051 * Prove that the dependency graph starting at <entry> can not
1052 * lead to <target>. Print an error and return 0 if it does.
1055 check_noncircular(struct lock_class *source, unsigned int depth)
1057 struct lock_list *entry;
1059 if (lockdep_dependency_visit(source, depth))
1062 debug_atomic_inc(&nr_cyclic_check_recursions);
1063 if (depth > max_recursion_depth)
1064 max_recursion_depth = depth;
1065 if (depth >= RECURSION_LIMIT)
1066 return print_infinite_recursion_bug();
1068 * Check this lock's dependency list:
1070 list_for_each_entry(entry, &source->locks_after, entry) {
1071 if (entry->class == hlock_class(check_target))
1072 return print_circular_bug_header(entry, depth+1);
1073 debug_atomic_inc(&nr_cyclic_checks);
1074 if (!check_noncircular(entry->class, depth+1))
1075 return print_circular_bug_entry(entry, depth+1);
1080 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1082 * Forwards and backwards subgraph searching, for the purposes of
1083 * proving that two subgraphs can be connected by a new dependency
1084 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1086 static enum lock_usage_bit find_usage_bit;
1087 static struct lock_class *forwards_match, *backwards_match;
1090 * Find a node in the forwards-direction dependency sub-graph starting
1091 * at <source> that matches <find_usage_bit>.
1093 * Return 2 if such a node exists in the subgraph, and put that node
1094 * into <forwards_match>.
1096 * Return 1 otherwise and keep <forwards_match> unchanged.
1097 * Return 0 on error.
1100 find_usage_forwards(struct lock_class *source, unsigned int depth)
1102 struct lock_list *entry;
1105 if (lockdep_dependency_visit(source, depth))
1108 if (depth > max_recursion_depth)
1109 max_recursion_depth = depth;
1110 if (depth >= RECURSION_LIMIT)
1111 return print_infinite_recursion_bug();
1113 debug_atomic_inc(&nr_find_usage_forwards_checks);
1114 if (source->usage_mask & (1 << find_usage_bit)) {
1115 forwards_match = source;
1120 * Check this lock's dependency list:
1122 list_for_each_entry(entry, &source->locks_after, entry) {
1123 debug_atomic_inc(&nr_find_usage_forwards_recursions);
1124 ret = find_usage_forwards(entry->class, depth+1);
1125 if (ret == 2 || ret == 0)
1132 * Find a node in the backwards-direction dependency sub-graph starting
1133 * at <source> that matches <find_usage_bit>.
1135 * Return 2 if such a node exists in the subgraph, and put that node
1136 * into <backwards_match>.
1138 * Return 1 otherwise and keep <backwards_match> unchanged.
1139 * Return 0 on error.
1142 find_usage_backwards(struct lock_class *source, unsigned int depth)
1144 struct lock_list *entry;
1147 if (lockdep_dependency_visit(source, depth))
1150 if (!__raw_spin_is_locked(&lockdep_lock))
1151 return DEBUG_LOCKS_WARN_ON(1);
1153 if (depth > max_recursion_depth)
1154 max_recursion_depth = depth;
1155 if (depth >= RECURSION_LIMIT)
1156 return print_infinite_recursion_bug();
1158 debug_atomic_inc(&nr_find_usage_backwards_checks);
1159 if (source->usage_mask & (1 << find_usage_bit)) {
1160 backwards_match = source;
1164 if (!source && debug_locks_off_graph_unlock()) {
1170 * Check this lock's dependency list:
1172 list_for_each_entry(entry, &source->locks_before, entry) {
1173 debug_atomic_inc(&nr_find_usage_backwards_recursions);
1174 ret = find_usage_backwards(entry->class, depth+1);
1175 if (ret == 2 || ret == 0)
1182 print_bad_irq_dependency(struct task_struct *curr,
1183 struct held_lock *prev,
1184 struct held_lock *next,
1185 enum lock_usage_bit bit1,
1186 enum lock_usage_bit bit2,
1187 const char *irqclass)
1189 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1192 printk("\n======================================================\n");
1193 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1194 irqclass, irqclass);
1195 print_kernel_version();
1196 printk( "------------------------------------------------------\n");
1197 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1198 curr->comm, task_pid_nr(curr),
1199 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1200 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1201 curr->hardirqs_enabled,
1202 curr->softirqs_enabled);
1205 printk("\nand this task is already holding:\n");
1207 printk("which would create a new lock dependency:\n");
1208 print_lock_name(hlock_class(prev));
1210 print_lock_name(hlock_class(next));
1213 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1215 print_lock_name(backwards_match);
1216 printk("\n... which became %s-irq-safe at:\n", irqclass);
1218 print_stack_trace(backwards_match->usage_traces + bit1, 1);
1220 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1221 print_lock_name(forwards_match);
1222 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1225 print_stack_trace(forwards_match->usage_traces + bit2, 1);
1227 printk("\nother info that might help us debug this:\n\n");
1228 lockdep_print_held_locks(curr);
1230 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1231 print_lock_dependencies(backwards_match, 0);
1233 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1234 print_lock_dependencies(forwards_match, 0);
1236 printk("\nstack backtrace:\n");
1243 check_usage(struct task_struct *curr, struct held_lock *prev,
1244 struct held_lock *next, enum lock_usage_bit bit_backwards,
1245 enum lock_usage_bit bit_forwards, const char *irqclass)
1249 find_usage_bit = bit_backwards;
1250 /* fills in <backwards_match> */
1251 ret = find_usage_backwards(hlock_class(prev), 0);
1252 if (!ret || ret == 1)
1255 find_usage_bit = bit_forwards;
1256 ret = find_usage_forwards(hlock_class(next), 0);
1257 if (!ret || ret == 1)
1260 return print_bad_irq_dependency(curr, prev, next,
1261 bit_backwards, bit_forwards, irqclass);
1264 static const char *state_names[] = {
1265 #define LOCKDEP_STATE(__STATE) \
1266 __stringify(__STATE),
1267 #include "lockdep_states.h"
1268 #undef LOCKDEP_STATE
1271 static const char *state_rnames[] = {
1272 #define LOCKDEP_STATE(__STATE) \
1273 __stringify(__STATE)"-READ",
1274 #include "lockdep_states.h"
1275 #undef LOCKDEP_STATE
1278 static inline const char *state_name(enum lock_usage_bit bit)
1280 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1283 static int exclusive_bit(int new_bit)
1291 * bit 0 - write/read
1292 * bit 1 - used_in/enabled
1296 int state = new_bit & ~3;
1297 int dir = new_bit & 2;
1300 * keep state, bit flip the direction and strip read.
1302 return state | (dir ^ 2);
1305 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1306 struct held_lock *next, enum lock_usage_bit bit)
1309 * Prove that the new dependency does not connect a hardirq-safe
1310 * lock with a hardirq-unsafe lock - to achieve this we search
1311 * the backwards-subgraph starting at <prev>, and the
1312 * forwards-subgraph starting at <next>:
1314 if (!check_usage(curr, prev, next, bit,
1315 exclusive_bit(bit), state_name(bit)))
1321 * Prove that the new dependency does not connect a hardirq-safe-read
1322 * lock with a hardirq-unsafe lock - to achieve this we search
1323 * the backwards-subgraph starting at <prev>, and the
1324 * forwards-subgraph starting at <next>:
1326 if (!check_usage(curr, prev, next, bit,
1327 exclusive_bit(bit), state_name(bit)))
1334 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1335 struct held_lock *next)
1337 #define LOCKDEP_STATE(__STATE) \
1338 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1340 #include "lockdep_states.h"
1341 #undef LOCKDEP_STATE
1346 static void inc_chains(void)
1348 if (current->hardirq_context)
1349 nr_hardirq_chains++;
1351 if (current->softirq_context)
1352 nr_softirq_chains++;
1354 nr_process_chains++;
1361 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1362 struct held_lock *next)
1367 static inline void inc_chains(void)
1369 nr_process_chains++;
1375 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1376 struct held_lock *next)
1378 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1381 printk("\n=============================================\n");
1382 printk( "[ INFO: possible recursive locking detected ]\n");
1383 print_kernel_version();
1384 printk( "---------------------------------------------\n");
1385 printk("%s/%d is trying to acquire lock:\n",
1386 curr->comm, task_pid_nr(curr));
1388 printk("\nbut task is already holding lock:\n");
1391 printk("\nother info that might help us debug this:\n");
1392 lockdep_print_held_locks(curr);
1394 printk("\nstack backtrace:\n");
1401 * Check whether we are holding such a class already.
1403 * (Note that this has to be done separately, because the graph cannot
1404 * detect such classes of deadlocks.)
1406 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1409 check_deadlock(struct task_struct *curr, struct held_lock *next,
1410 struct lockdep_map *next_instance, int read)
1412 struct held_lock *prev;
1413 struct held_lock *nest = NULL;
1416 for (i = 0; i < curr->lockdep_depth; i++) {
1417 prev = curr->held_locks + i;
1419 if (prev->instance == next->nest_lock)
1422 if (hlock_class(prev) != hlock_class(next))
1426 * Allow read-after-read recursion of the same
1427 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1429 if ((read == 2) && prev->read)
1433 * We're holding the nest_lock, which serializes this lock's
1434 * nesting behaviour.
1439 return print_deadlock_bug(curr, prev, next);
1445 * There was a chain-cache miss, and we are about to add a new dependency
1446 * to a previous lock. We recursively validate the following rules:
1448 * - would the adding of the <prev> -> <next> dependency create a
1449 * circular dependency in the graph? [== circular deadlock]
1451 * - does the new prev->next dependency connect any hardirq-safe lock
1452 * (in the full backwards-subgraph starting at <prev>) with any
1453 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1454 * <next>)? [== illegal lock inversion with hardirq contexts]
1456 * - does the new prev->next dependency connect any softirq-safe lock
1457 * (in the full backwards-subgraph starting at <prev>) with any
1458 * softirq-unsafe lock (in the full forwards-subgraph starting at
1459 * <next>)? [== illegal lock inversion with softirq contexts]
1461 * any of these scenarios could lead to a deadlock.
1463 * Then if all the validations pass, we add the forwards and backwards
1467 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1468 struct held_lock *next, int distance)
1470 struct lock_list *entry;
1474 * Prove that the new <prev> -> <next> dependency would not
1475 * create a circular dependency in the graph. (We do this by
1476 * forward-recursing into the graph starting at <next>, and
1477 * checking whether we can reach <prev>.)
1479 * We are using global variables to control the recursion, to
1480 * keep the stackframe size of the recursive functions low:
1482 check_source = next;
1483 check_target = prev;
1484 if (!(check_noncircular(hlock_class(next), 0)))
1485 return print_circular_bug_tail();
1487 if (!check_prev_add_irq(curr, prev, next))
1491 * For recursive read-locks we do all the dependency checks,
1492 * but we dont store read-triggered dependencies (only
1493 * write-triggered dependencies). This ensures that only the
1494 * write-side dependencies matter, and that if for example a
1495 * write-lock never takes any other locks, then the reads are
1496 * equivalent to a NOP.
1498 if (next->read == 2 || prev->read == 2)
1501 * Is the <prev> -> <next> dependency already present?
1503 * (this may occur even though this is a new chain: consider
1504 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1505 * chains - the second one will be new, but L1 already has
1506 * L2 added to its dependency list, due to the first chain.)
1508 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1509 if (entry->class == hlock_class(next)) {
1511 entry->distance = 1;
1517 * Ok, all validations passed, add the new lock
1518 * to the previous lock's dependency list:
1520 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1521 &hlock_class(prev)->locks_after,
1522 next->acquire_ip, distance);
1527 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1528 &hlock_class(next)->locks_before,
1529 next->acquire_ip, distance);
1534 * Debugging printouts:
1536 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1538 printk("\n new dependency: ");
1539 print_lock_name(hlock_class(prev));
1541 print_lock_name(hlock_class(next));
1544 return graph_lock();
1550 * Add the dependency to all directly-previous locks that are 'relevant'.
1551 * The ones that are relevant are (in increasing distance from curr):
1552 * all consecutive trylock entries and the final non-trylock entry - or
1553 * the end of this context's lock-chain - whichever comes first.
1556 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1558 int depth = curr->lockdep_depth;
1559 struct held_lock *hlock;
1564 * Depth must not be zero for a non-head lock:
1569 * At least two relevant locks must exist for this
1572 if (curr->held_locks[depth].irq_context !=
1573 curr->held_locks[depth-1].irq_context)
1577 int distance = curr->lockdep_depth - depth + 1;
1578 hlock = curr->held_locks + depth-1;
1580 * Only non-recursive-read entries get new dependencies
1583 if (hlock->read != 2) {
1584 if (!check_prev_add(curr, hlock, next, distance))
1587 * Stop after the first non-trylock entry,
1588 * as non-trylock entries have added their
1589 * own direct dependencies already, so this
1590 * lock is connected to them indirectly:
1592 if (!hlock->trylock)
1597 * End of lock-stack?
1602 * Stop the search if we cross into another context:
1604 if (curr->held_locks[depth].irq_context !=
1605 curr->held_locks[depth-1].irq_context)
1610 if (!debug_locks_off_graph_unlock())
1618 unsigned long nr_lock_chains;
1619 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1620 int nr_chain_hlocks;
1621 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1623 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1625 return lock_classes + chain_hlocks[chain->base + i];
1629 * Look up a dependency chain. If the key is not present yet then
1630 * add it and return 1 - in this case the new dependency chain is
1631 * validated. If the key is already hashed, return 0.
1632 * (On return with 1 graph_lock is held.)
1634 static inline int lookup_chain_cache(struct task_struct *curr,
1635 struct held_lock *hlock,
1638 struct lock_class *class = hlock_class(hlock);
1639 struct list_head *hash_head = chainhashentry(chain_key);
1640 struct lock_chain *chain;
1641 struct held_lock *hlock_curr, *hlock_next;
1644 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1647 * We can walk it lock-free, because entries only get added
1650 list_for_each_entry(chain, hash_head, entry) {
1651 if (chain->chain_key == chain_key) {
1653 debug_atomic_inc(&chain_lookup_hits);
1654 if (very_verbose(class))
1655 printk("\nhash chain already cached, key: "
1656 "%016Lx tail class: [%p] %s\n",
1657 (unsigned long long)chain_key,
1658 class->key, class->name);
1662 if (very_verbose(class))
1663 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1664 (unsigned long long)chain_key, class->key, class->name);
1666 * Allocate a new chain entry from the static array, and add
1672 * We have to walk the chain again locked - to avoid duplicates:
1674 list_for_each_entry(chain, hash_head, entry) {
1675 if (chain->chain_key == chain_key) {
1680 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1681 if (!debug_locks_off_graph_unlock())
1684 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1685 printk("turning off the locking correctness validator.\n");
1689 chain = lock_chains + nr_lock_chains++;
1690 chain->chain_key = chain_key;
1691 chain->irq_context = hlock->irq_context;
1692 /* Find the first held_lock of current chain */
1694 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1695 hlock_curr = curr->held_locks + i;
1696 if (hlock_curr->irq_context != hlock_next->irq_context)
1701 chain->depth = curr->lockdep_depth + 1 - i;
1702 cn = nr_chain_hlocks;
1703 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1704 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1709 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1711 for (j = 0; j < chain->depth - 1; j++, i++) {
1712 int lock_id = curr->held_locks[i].class_idx - 1;
1713 chain_hlocks[chain->base + j] = lock_id;
1715 chain_hlocks[chain->base + j] = class - lock_classes;
1717 list_add_tail_rcu(&chain->entry, hash_head);
1718 debug_atomic_inc(&chain_lookup_misses);
1724 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1725 struct held_lock *hlock, int chain_head, u64 chain_key)
1728 * Trylock needs to maintain the stack of held locks, but it
1729 * does not add new dependencies, because trylock can be done
1732 * We look up the chain_key and do the O(N^2) check and update of
1733 * the dependencies only if this is a new dependency chain.
1734 * (If lookup_chain_cache() returns with 1 it acquires
1735 * graph_lock for us)
1737 if (!hlock->trylock && (hlock->check == 2) &&
1738 lookup_chain_cache(curr, hlock, chain_key)) {
1740 * Check whether last held lock:
1742 * - is irq-safe, if this lock is irq-unsafe
1743 * - is softirq-safe, if this lock is hardirq-unsafe
1745 * And check whether the new lock's dependency graph
1746 * could lead back to the previous lock.
1748 * any of these scenarios could lead to a deadlock. If
1751 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1756 * Mark recursive read, as we jump over it when
1757 * building dependencies (just like we jump over
1763 * Add dependency only if this lock is not the head
1764 * of the chain, and if it's not a secondary read-lock:
1766 if (!chain_head && ret != 2)
1767 if (!check_prevs_add(curr, hlock))
1771 /* after lookup_chain_cache(): */
1772 if (unlikely(!debug_locks))
1778 static inline int validate_chain(struct task_struct *curr,
1779 struct lockdep_map *lock, struct held_lock *hlock,
1780 int chain_head, u64 chain_key)
1787 * We are building curr_chain_key incrementally, so double-check
1788 * it from scratch, to make sure that it's done correctly:
1790 static void check_chain_key(struct task_struct *curr)
1792 #ifdef CONFIG_DEBUG_LOCKDEP
1793 struct held_lock *hlock, *prev_hlock = NULL;
1797 for (i = 0; i < curr->lockdep_depth; i++) {
1798 hlock = curr->held_locks + i;
1799 if (chain_key != hlock->prev_chain_key) {
1801 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1802 curr->lockdep_depth, i,
1803 (unsigned long long)chain_key,
1804 (unsigned long long)hlock->prev_chain_key);
1807 id = hlock->class_idx - 1;
1808 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1811 if (prev_hlock && (prev_hlock->irq_context !=
1812 hlock->irq_context))
1814 chain_key = iterate_chain_key(chain_key, id);
1817 if (chain_key != curr->curr_chain_key) {
1819 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1820 curr->lockdep_depth, i,
1821 (unsigned long long)chain_key,
1822 (unsigned long long)curr->curr_chain_key);
1828 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1829 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1831 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1834 printk("\n=================================\n");
1835 printk( "[ INFO: inconsistent lock state ]\n");
1836 print_kernel_version();
1837 printk( "---------------------------------\n");
1839 printk("inconsistent {%s} -> {%s} usage.\n",
1840 usage_str[prev_bit], usage_str[new_bit]);
1842 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1843 curr->comm, task_pid_nr(curr),
1844 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1845 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1846 trace_hardirqs_enabled(curr),
1847 trace_softirqs_enabled(curr));
1850 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1851 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
1853 print_irqtrace_events(curr);
1854 printk("\nother info that might help us debug this:\n");
1855 lockdep_print_held_locks(curr);
1857 printk("\nstack backtrace:\n");
1864 * Print out an error if an invalid bit is set:
1867 valid_state(struct task_struct *curr, struct held_lock *this,
1868 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1870 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
1871 return print_usage_bug(curr, this, bad_bit, new_bit);
1875 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1876 enum lock_usage_bit new_bit);
1878 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1881 * print irq inversion bug:
1884 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1885 struct held_lock *this, int forwards,
1886 const char *irqclass)
1888 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1891 printk("\n=========================================================\n");
1892 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1893 print_kernel_version();
1894 printk( "---------------------------------------------------------\n");
1895 printk("%s/%d just changed the state of lock:\n",
1896 curr->comm, task_pid_nr(curr));
1899 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
1901 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
1902 print_lock_name(other);
1903 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1905 printk("\nother info that might help us debug this:\n");
1906 lockdep_print_held_locks(curr);
1908 printk("\nthe first lock's dependencies:\n");
1909 print_lock_dependencies(hlock_class(this), 0);
1911 printk("\nthe second lock's dependencies:\n");
1912 print_lock_dependencies(other, 0);
1914 printk("\nstack backtrace:\n");
1921 * Prove that in the forwards-direction subgraph starting at <this>
1922 * there is no lock matching <mask>:
1925 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1926 enum lock_usage_bit bit, const char *irqclass)
1930 find_usage_bit = bit;
1931 /* fills in <forwards_match> */
1932 ret = find_usage_forwards(hlock_class(this), 0);
1933 if (!ret || ret == 1)
1936 return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1940 * Prove that in the backwards-direction subgraph starting at <this>
1941 * there is no lock matching <mask>:
1944 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1945 enum lock_usage_bit bit, const char *irqclass)
1949 find_usage_bit = bit;
1950 /* fills in <backwards_match> */
1951 ret = find_usage_backwards(hlock_class(this), 0);
1952 if (!ret || ret == 1)
1955 return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1958 void print_irqtrace_events(struct task_struct *curr)
1960 printk("irq event stamp: %u\n", curr->irq_events);
1961 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
1962 print_ip_sym(curr->hardirq_enable_ip);
1963 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1964 print_ip_sym(curr->hardirq_disable_ip);
1965 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
1966 print_ip_sym(curr->softirq_enable_ip);
1967 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1968 print_ip_sym(curr->softirq_disable_ip);
1971 static int HARDIRQ_verbose(struct lock_class *class)
1974 return class_filter(class);
1979 static int SOFTIRQ_verbose(struct lock_class *class)
1982 return class_filter(class);
1987 static int RECLAIM_FS_verbose(struct lock_class *class)
1990 return class_filter(class);
1995 #define STRICT_READ_CHECKS 1
1997 static int (*state_verbose_f[])(struct lock_class *class) = {
1998 #define LOCKDEP_STATE(__STATE) \
2000 #include "lockdep_states.h"
2001 #undef LOCKDEP_STATE
2004 static inline int state_verbose(enum lock_usage_bit bit,
2005 struct lock_class *class)
2007 return state_verbose_f[bit >> 2](class);
2010 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2011 enum lock_usage_bit bit, const char *name);
2014 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2015 enum lock_usage_bit new_bit)
2017 int excl_bit = exclusive_bit(new_bit);
2018 int read = new_bit & 1;
2019 int dir = new_bit & 2;
2022 * mark USED_IN has to look forwards -- to ensure no dependency
2023 * has ENABLED state, which would allow recursion deadlocks.
2025 * mark ENABLED has to look backwards -- to ensure no dependee
2026 * has USED_IN state, which, again, would allow recursion deadlocks.
2028 check_usage_f usage = dir ?
2029 check_usage_backwards : check_usage_forwards;
2032 * Validate that this particular lock does not have conflicting
2035 if (!valid_state(curr, this, new_bit, excl_bit))
2039 * Validate that the lock dependencies don't have conflicting usage
2042 if ((!read || !dir || STRICT_READ_CHECKS) &&
2043 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2047 * Check for read in write conflicts
2050 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2053 if (STRICT_READ_CHECKS &&
2054 !usage(curr, this, excl_bit + 1,
2055 state_name(new_bit + 1)))
2059 if (state_verbose(new_bit, hlock_class(this)))
2066 #define LOCKDEP_STATE(__STATE) __STATE,
2067 #include "lockdep_states.h"
2068 #undef LOCKDEP_STATE
2072 * Mark all held locks with a usage bit:
2075 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2077 enum lock_usage_bit usage_bit;
2078 struct held_lock *hlock;
2081 for (i = 0; i < curr->lockdep_depth; i++) {
2082 hlock = curr->held_locks + i;
2084 usage_bit = 2 + (mark << 2); /* ENABLED */
2086 usage_bit += 1; /* READ */
2088 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2090 if (!mark_lock(curr, hlock, usage_bit))
2098 * Debugging helper: via this flag we know that we are in
2099 * 'early bootup code', and will warn about any invalid irqs-on event:
2101 static int early_boot_irqs_enabled;
2103 void early_boot_irqs_off(void)
2105 early_boot_irqs_enabled = 0;
2108 void early_boot_irqs_on(void)
2110 early_boot_irqs_enabled = 1;
2114 * Hardirqs will be enabled:
2116 void trace_hardirqs_on_caller(unsigned long ip)
2118 struct task_struct *curr = current;
2120 time_hardirqs_on(CALLER_ADDR0, ip);
2122 if (unlikely(!debug_locks || current->lockdep_recursion))
2125 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2128 if (unlikely(curr->hardirqs_enabled)) {
2129 debug_atomic_inc(&redundant_hardirqs_on);
2132 /* we'll do an OFF -> ON transition: */
2133 curr->hardirqs_enabled = 1;
2135 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2137 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2140 * We are going to turn hardirqs on, so set the
2141 * usage bit for all held locks:
2143 if (!mark_held_locks(curr, HARDIRQ))
2146 * If we have softirqs enabled, then set the usage
2147 * bit for all held locks. (disabled hardirqs prevented
2148 * this bit from being set before)
2150 if (curr->softirqs_enabled)
2151 if (!mark_held_locks(curr, SOFTIRQ))
2154 curr->hardirq_enable_ip = ip;
2155 curr->hardirq_enable_event = ++curr->irq_events;
2156 debug_atomic_inc(&hardirqs_on_events);
2158 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2160 void trace_hardirqs_on(void)
2162 trace_hardirqs_on_caller(CALLER_ADDR0);
2164 EXPORT_SYMBOL(trace_hardirqs_on);
2167 * Hardirqs were disabled:
2169 void trace_hardirqs_off_caller(unsigned long ip)
2171 struct task_struct *curr = current;
2173 time_hardirqs_off(CALLER_ADDR0, ip);
2175 if (unlikely(!debug_locks || current->lockdep_recursion))
2178 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2181 if (curr->hardirqs_enabled) {
2183 * We have done an ON -> OFF transition:
2185 curr->hardirqs_enabled = 0;
2186 curr->hardirq_disable_ip = ip;
2187 curr->hardirq_disable_event = ++curr->irq_events;
2188 debug_atomic_inc(&hardirqs_off_events);
2190 debug_atomic_inc(&redundant_hardirqs_off);
2192 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2194 void trace_hardirqs_off(void)
2196 trace_hardirqs_off_caller(CALLER_ADDR0);
2198 EXPORT_SYMBOL(trace_hardirqs_off);
2201 * Softirqs will be enabled:
2203 void trace_softirqs_on(unsigned long ip)
2205 struct task_struct *curr = current;
2207 if (unlikely(!debug_locks))
2210 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2213 if (curr->softirqs_enabled) {
2214 debug_atomic_inc(&redundant_softirqs_on);
2219 * We'll do an OFF -> ON transition:
2221 curr->softirqs_enabled = 1;
2222 curr->softirq_enable_ip = ip;
2223 curr->softirq_enable_event = ++curr->irq_events;
2224 debug_atomic_inc(&softirqs_on_events);
2226 * We are going to turn softirqs on, so set the
2227 * usage bit for all held locks, if hardirqs are
2230 if (curr->hardirqs_enabled)
2231 mark_held_locks(curr, SOFTIRQ);
2235 * Softirqs were disabled:
2237 void trace_softirqs_off(unsigned long ip)
2239 struct task_struct *curr = current;
2241 if (unlikely(!debug_locks))
2244 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2247 if (curr->softirqs_enabled) {
2249 * We have done an ON -> OFF transition:
2251 curr->softirqs_enabled = 0;
2252 curr->softirq_disable_ip = ip;
2253 curr->softirq_disable_event = ++curr->irq_events;
2254 debug_atomic_inc(&softirqs_off_events);
2255 DEBUG_LOCKS_WARN_ON(!softirq_count());
2257 debug_atomic_inc(&redundant_softirqs_off);
2260 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2262 struct task_struct *curr = current;
2264 if (unlikely(!debug_locks))
2267 /* no reclaim without waiting on it */
2268 if (!(gfp_mask & __GFP_WAIT))
2271 /* this guy won't enter reclaim */
2272 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2275 /* We're only interested __GFP_FS allocations for now */
2276 if (!(gfp_mask & __GFP_FS))
2279 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2282 mark_held_locks(curr, RECLAIM_FS);
2285 static void check_flags(unsigned long flags);
2287 void lockdep_trace_alloc(gfp_t gfp_mask)
2289 unsigned long flags;
2291 if (unlikely(current->lockdep_recursion))
2294 raw_local_irq_save(flags);
2296 current->lockdep_recursion = 1;
2297 __lockdep_trace_alloc(gfp_mask, flags);
2298 current->lockdep_recursion = 0;
2299 raw_local_irq_restore(flags);
2302 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2305 * If non-trylock use in a hardirq or softirq context, then
2306 * mark the lock as used in these contexts:
2308 if (!hlock->trylock) {
2310 if (curr->hardirq_context)
2311 if (!mark_lock(curr, hlock,
2312 LOCK_USED_IN_HARDIRQ_READ))
2314 if (curr->softirq_context)
2315 if (!mark_lock(curr, hlock,
2316 LOCK_USED_IN_SOFTIRQ_READ))
2319 if (curr->hardirq_context)
2320 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2322 if (curr->softirq_context)
2323 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2327 if (!hlock->hardirqs_off) {
2329 if (!mark_lock(curr, hlock,
2330 LOCK_ENABLED_HARDIRQ_READ))
2332 if (curr->softirqs_enabled)
2333 if (!mark_lock(curr, hlock,
2334 LOCK_ENABLED_SOFTIRQ_READ))
2337 if (!mark_lock(curr, hlock,
2338 LOCK_ENABLED_HARDIRQ))
2340 if (curr->softirqs_enabled)
2341 if (!mark_lock(curr, hlock,
2342 LOCK_ENABLED_SOFTIRQ))
2348 * We reuse the irq context infrastructure more broadly as a general
2349 * context checking code. This tests GFP_FS recursion (a lock taken
2350 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2353 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2355 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2358 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2366 static int separate_irq_context(struct task_struct *curr,
2367 struct held_lock *hlock)
2369 unsigned int depth = curr->lockdep_depth;
2372 * Keep track of points where we cross into an interrupt context:
2374 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2375 curr->softirq_context;
2377 struct held_lock *prev_hlock;
2379 prev_hlock = curr->held_locks + depth-1;
2381 * If we cross into another context, reset the
2382 * hash key (this also prevents the checking and the
2383 * adding of the dependency to 'prev'):
2385 if (prev_hlock->irq_context != hlock->irq_context)
2394 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2395 enum lock_usage_bit new_bit)
2401 static inline int mark_irqflags(struct task_struct *curr,
2402 struct held_lock *hlock)
2407 static inline int separate_irq_context(struct task_struct *curr,
2408 struct held_lock *hlock)
2413 void lockdep_trace_alloc(gfp_t gfp_mask)
2420 * Mark a lock with a usage bit, and validate the state transition:
2422 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2423 enum lock_usage_bit new_bit)
2425 unsigned int new_mask = 1 << new_bit, ret = 1;
2428 * If already set then do not dirty the cacheline,
2429 * nor do any checks:
2431 if (likely(hlock_class(this)->usage_mask & new_mask))
2437 * Make sure we didnt race:
2439 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2444 hlock_class(this)->usage_mask |= new_mask;
2446 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2450 #define LOCKDEP_STATE(__STATE) \
2451 case LOCK_USED_IN_##__STATE: \
2452 case LOCK_USED_IN_##__STATE##_READ: \
2453 case LOCK_ENABLED_##__STATE: \
2454 case LOCK_ENABLED_##__STATE##_READ:
2455 #include "lockdep_states.h"
2456 #undef LOCKDEP_STATE
2457 ret = mark_lock_irq(curr, this, new_bit);
2462 debug_atomic_dec(&nr_unused_locks);
2465 if (!debug_locks_off_graph_unlock())
2474 * We must printk outside of the graph_lock:
2477 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2479 print_irqtrace_events(curr);
2487 * Initialize a lock instance's lock-class mapping info:
2489 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2490 struct lock_class_key *key, int subclass)
2492 if (unlikely(!debug_locks))
2495 if (DEBUG_LOCKS_WARN_ON(!key))
2497 if (DEBUG_LOCKS_WARN_ON(!name))
2500 * Sanity check, the lock-class key must be persistent:
2502 if (!static_obj(key)) {
2503 printk("BUG: key %p not in .data!\n", key);
2504 DEBUG_LOCKS_WARN_ON(1);
2509 lock->class_cache = NULL;
2510 #ifdef CONFIG_LOCK_STAT
2511 lock->cpu = raw_smp_processor_id();
2514 register_lock_class(lock, subclass, 1);
2516 EXPORT_SYMBOL_GPL(lockdep_init_map);
2519 * This gets called for every mutex_lock*()/spin_lock*() operation.
2520 * We maintain the dependency maps and validate the locking attempt:
2522 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2523 int trylock, int read, int check, int hardirqs_off,
2524 struct lockdep_map *nest_lock, unsigned long ip)
2526 struct task_struct *curr = current;
2527 struct lock_class *class = NULL;
2528 struct held_lock *hlock;
2529 unsigned int depth, id;
2536 if (unlikely(!debug_locks))
2539 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2542 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2544 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2545 printk("turning off the locking correctness validator.\n");
2551 class = lock->class_cache;
2553 * Not cached yet or subclass?
2555 if (unlikely(!class)) {
2556 class = register_lock_class(lock, subclass, 0);
2560 debug_atomic_inc((atomic_t *)&class->ops);
2561 if (very_verbose(class)) {
2562 printk("\nacquire class [%p] %s", class->key, class->name);
2563 if (class->name_version > 1)
2564 printk("#%d", class->name_version);
2570 * Add the lock to the list of currently held locks.
2571 * (we dont increase the depth just yet, up until the
2572 * dependency checks are done)
2574 depth = curr->lockdep_depth;
2575 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2578 hlock = curr->held_locks + depth;
2579 if (DEBUG_LOCKS_WARN_ON(!class))
2581 hlock->class_idx = class - lock_classes + 1;
2582 hlock->acquire_ip = ip;
2583 hlock->instance = lock;
2584 hlock->nest_lock = nest_lock;
2585 hlock->trylock = trylock;
2587 hlock->check = check;
2588 hlock->hardirqs_off = !!hardirqs_off;
2589 #ifdef CONFIG_LOCK_STAT
2590 hlock->waittime_stamp = 0;
2591 hlock->holdtime_stamp = sched_clock();
2594 if (check == 2 && !mark_irqflags(curr, hlock))
2597 /* mark it as used: */
2598 if (!mark_lock(curr, hlock, LOCK_USED))
2602 * Calculate the chain hash: it's the combined hash of all the
2603 * lock keys along the dependency chain. We save the hash value
2604 * at every step so that we can get the current hash easily
2605 * after unlock. The chain hash is then used to cache dependency
2608 * The 'key ID' is what is the most compact key value to drive
2609 * the hash, not class->key.
2611 id = class - lock_classes;
2612 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2615 chain_key = curr->curr_chain_key;
2617 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2622 hlock->prev_chain_key = chain_key;
2623 if (separate_irq_context(curr, hlock)) {
2627 chain_key = iterate_chain_key(chain_key, id);
2629 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2632 curr->curr_chain_key = chain_key;
2633 curr->lockdep_depth++;
2634 check_chain_key(curr);
2635 #ifdef CONFIG_DEBUG_LOCKDEP
2636 if (unlikely(!debug_locks))
2639 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2641 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2642 printk("turning off the locking correctness validator.\n");
2647 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2648 max_lockdep_depth = curr->lockdep_depth;
2654 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2657 if (!debug_locks_off())
2659 if (debug_locks_silent)
2662 printk("\n=====================================\n");
2663 printk( "[ BUG: bad unlock balance detected! ]\n");
2664 printk( "-------------------------------------\n");
2665 printk("%s/%d is trying to release lock (",
2666 curr->comm, task_pid_nr(curr));
2667 print_lockdep_cache(lock);
2670 printk("but there are no more locks to release!\n");
2671 printk("\nother info that might help us debug this:\n");
2672 lockdep_print_held_locks(curr);
2674 printk("\nstack backtrace:\n");
2681 * Common debugging checks for both nested and non-nested unlock:
2683 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2686 if (unlikely(!debug_locks))
2688 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2691 if (curr->lockdep_depth <= 0)
2692 return print_unlock_inbalance_bug(curr, lock, ip);
2698 __lock_set_class(struct lockdep_map *lock, const char *name,
2699 struct lock_class_key *key, unsigned int subclass,
2702 struct task_struct *curr = current;
2703 struct held_lock *hlock, *prev_hlock;
2704 struct lock_class *class;
2708 depth = curr->lockdep_depth;
2709 if (DEBUG_LOCKS_WARN_ON(!depth))
2713 for (i = depth-1; i >= 0; i--) {
2714 hlock = curr->held_locks + i;
2716 * We must not cross into another context:
2718 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2720 if (hlock->instance == lock)
2724 return print_unlock_inbalance_bug(curr, lock, ip);
2727 lockdep_init_map(lock, name, key, 0);
2728 class = register_lock_class(lock, subclass, 0);
2729 hlock->class_idx = class - lock_classes + 1;
2731 curr->lockdep_depth = i;
2732 curr->curr_chain_key = hlock->prev_chain_key;
2734 for (; i < depth; i++) {
2735 hlock = curr->held_locks + i;
2736 if (!__lock_acquire(hlock->instance,
2737 hlock_class(hlock)->subclass, hlock->trylock,
2738 hlock->read, hlock->check, hlock->hardirqs_off,
2739 hlock->nest_lock, hlock->acquire_ip))
2743 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2749 * Remove the lock to the list of currently held locks in a
2750 * potentially non-nested (out of order) manner. This is a
2751 * relatively rare operation, as all the unlock APIs default
2752 * to nested mode (which uses lock_release()):
2755 lock_release_non_nested(struct task_struct *curr,
2756 struct lockdep_map *lock, unsigned long ip)
2758 struct held_lock *hlock, *prev_hlock;
2763 * Check whether the lock exists in the current stack
2766 depth = curr->lockdep_depth;
2767 if (DEBUG_LOCKS_WARN_ON(!depth))
2771 for (i = depth-1; i >= 0; i--) {
2772 hlock = curr->held_locks + i;
2774 * We must not cross into another context:
2776 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2778 if (hlock->instance == lock)
2782 return print_unlock_inbalance_bug(curr, lock, ip);
2785 lock_release_holdtime(hlock);
2788 * We have the right lock to unlock, 'hlock' points to it.
2789 * Now we remove it from the stack, and add back the other
2790 * entries (if any), recalculating the hash along the way:
2792 curr->lockdep_depth = i;
2793 curr->curr_chain_key = hlock->prev_chain_key;
2795 for (i++; i < depth; i++) {
2796 hlock = curr->held_locks + i;
2797 if (!__lock_acquire(hlock->instance,
2798 hlock_class(hlock)->subclass, hlock->trylock,
2799 hlock->read, hlock->check, hlock->hardirqs_off,
2800 hlock->nest_lock, hlock->acquire_ip))
2804 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2810 * Remove the lock to the list of currently held locks - this gets
2811 * called on mutex_unlock()/spin_unlock*() (or on a failed
2812 * mutex_lock_interruptible()). This is done for unlocks that nest
2813 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2815 static int lock_release_nested(struct task_struct *curr,
2816 struct lockdep_map *lock, unsigned long ip)
2818 struct held_lock *hlock;
2822 * Pop off the top of the lock stack:
2824 depth = curr->lockdep_depth - 1;
2825 hlock = curr->held_locks + depth;
2828 * Is the unlock non-nested:
2830 if (hlock->instance != lock)
2831 return lock_release_non_nested(curr, lock, ip);
2832 curr->lockdep_depth--;
2834 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2837 curr->curr_chain_key = hlock->prev_chain_key;
2839 lock_release_holdtime(hlock);
2841 #ifdef CONFIG_DEBUG_LOCKDEP
2842 hlock->prev_chain_key = 0;
2843 hlock->class_idx = 0;
2844 hlock->acquire_ip = 0;
2845 hlock->irq_context = 0;
2851 * Remove the lock to the list of currently held locks - this gets
2852 * called on mutex_unlock()/spin_unlock*() (or on a failed
2853 * mutex_lock_interruptible()). This is done for unlocks that nest
2854 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2857 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2859 struct task_struct *curr = current;
2861 if (!check_unlock(curr, lock, ip))
2865 if (!lock_release_nested(curr, lock, ip))
2868 if (!lock_release_non_nested(curr, lock, ip))
2872 check_chain_key(curr);
2876 * Check whether we follow the irq-flags state precisely:
2878 static void check_flags(unsigned long flags)
2880 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2881 defined(CONFIG_TRACE_IRQFLAGS)
2885 if (irqs_disabled_flags(flags)) {
2886 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
2887 printk("possible reason: unannotated irqs-off.\n");
2890 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
2891 printk("possible reason: unannotated irqs-on.\n");
2896 * We dont accurately track softirq state in e.g.
2897 * hardirq contexts (such as on 4KSTACKS), so only
2898 * check if not in hardirq contexts:
2900 if (!hardirq_count()) {
2901 if (softirq_count())
2902 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2904 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2908 print_irqtrace_events(current);
2912 void lock_set_class(struct lockdep_map *lock, const char *name,
2913 struct lock_class_key *key, unsigned int subclass,
2916 unsigned long flags;
2918 if (unlikely(current->lockdep_recursion))
2921 raw_local_irq_save(flags);
2922 current->lockdep_recursion = 1;
2924 if (__lock_set_class(lock, name, key, subclass, ip))
2925 check_chain_key(current);
2926 current->lockdep_recursion = 0;
2927 raw_local_irq_restore(flags);
2929 EXPORT_SYMBOL_GPL(lock_set_class);
2932 * We are not always called with irqs disabled - do that here,
2933 * and also avoid lockdep recursion:
2935 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2936 int trylock, int read, int check,
2937 struct lockdep_map *nest_lock, unsigned long ip)
2939 unsigned long flags;
2941 if (unlikely(current->lockdep_recursion))
2944 raw_local_irq_save(flags);
2947 current->lockdep_recursion = 1;
2948 __lock_acquire(lock, subclass, trylock, read, check,
2949 irqs_disabled_flags(flags), nest_lock, ip);
2950 current->lockdep_recursion = 0;
2951 raw_local_irq_restore(flags);
2953 EXPORT_SYMBOL_GPL(lock_acquire);
2955 void lock_release(struct lockdep_map *lock, int nested,
2958 unsigned long flags;
2960 if (unlikely(current->lockdep_recursion))
2963 raw_local_irq_save(flags);
2965 current->lockdep_recursion = 1;
2966 __lock_release(lock, nested, ip);
2967 current->lockdep_recursion = 0;
2968 raw_local_irq_restore(flags);
2970 EXPORT_SYMBOL_GPL(lock_release);
2972 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
2974 current->lockdep_reclaim_gfp = gfp_mask;
2977 void lockdep_clear_current_reclaim_state(void)
2979 current->lockdep_reclaim_gfp = 0;
2982 #ifdef CONFIG_LOCK_STAT
2984 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
2987 if (!debug_locks_off())
2989 if (debug_locks_silent)
2992 printk("\n=================================\n");
2993 printk( "[ BUG: bad contention detected! ]\n");
2994 printk( "---------------------------------\n");
2995 printk("%s/%d is trying to contend lock (",
2996 curr->comm, task_pid_nr(curr));
2997 print_lockdep_cache(lock);
3000 printk("but there are no locks held!\n");
3001 printk("\nother info that might help us debug this:\n");
3002 lockdep_print_held_locks(curr);
3004 printk("\nstack backtrace:\n");
3011 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3013 struct task_struct *curr = current;
3014 struct held_lock *hlock, *prev_hlock;
3015 struct lock_class_stats *stats;
3017 int i, contention_point, contending_point;
3019 depth = curr->lockdep_depth;
3020 if (DEBUG_LOCKS_WARN_ON(!depth))
3024 for (i = depth-1; i >= 0; i--) {
3025 hlock = curr->held_locks + i;
3027 * We must not cross into another context:
3029 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3031 if (hlock->instance == lock)
3035 print_lock_contention_bug(curr, lock, ip);
3039 hlock->waittime_stamp = sched_clock();
3041 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3042 contending_point = lock_point(hlock_class(hlock)->contending_point,
3045 stats = get_lock_stats(hlock_class(hlock));
3046 if (contention_point < LOCKSTAT_POINTS)
3047 stats->contention_point[contention_point]++;
3048 if (contending_point < LOCKSTAT_POINTS)
3049 stats->contending_point[contending_point]++;
3050 if (lock->cpu != smp_processor_id())
3051 stats->bounces[bounce_contended + !!hlock->read]++;
3052 put_lock_stats(stats);
3056 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3058 struct task_struct *curr = current;
3059 struct held_lock *hlock, *prev_hlock;
3060 struct lock_class_stats *stats;
3066 depth = curr->lockdep_depth;
3067 if (DEBUG_LOCKS_WARN_ON(!depth))
3071 for (i = depth-1; i >= 0; i--) {
3072 hlock = curr->held_locks + i;
3074 * We must not cross into another context:
3076 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3078 if (hlock->instance == lock)
3082 print_lock_contention_bug(curr, lock, _RET_IP_);
3086 cpu = smp_processor_id();
3087 if (hlock->waittime_stamp) {
3088 now = sched_clock();
3089 waittime = now - hlock->waittime_stamp;
3090 hlock->holdtime_stamp = now;
3093 stats = get_lock_stats(hlock_class(hlock));
3096 lock_time_inc(&stats->read_waittime, waittime);
3098 lock_time_inc(&stats->write_waittime, waittime);
3100 if (lock->cpu != cpu)
3101 stats->bounces[bounce_acquired + !!hlock->read]++;
3102 put_lock_stats(stats);
3108 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3110 unsigned long flags;
3112 if (unlikely(!lock_stat))
3115 if (unlikely(current->lockdep_recursion))
3118 raw_local_irq_save(flags);
3120 current->lockdep_recursion = 1;
3121 __lock_contended(lock, ip);
3122 current->lockdep_recursion = 0;
3123 raw_local_irq_restore(flags);
3125 EXPORT_SYMBOL_GPL(lock_contended);
3127 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3129 unsigned long flags;
3131 if (unlikely(!lock_stat))
3134 if (unlikely(current->lockdep_recursion))
3137 raw_local_irq_save(flags);
3139 current->lockdep_recursion = 1;
3140 __lock_acquired(lock, ip);
3141 current->lockdep_recursion = 0;
3142 raw_local_irq_restore(flags);
3144 EXPORT_SYMBOL_GPL(lock_acquired);
3148 * Used by the testsuite, sanitize the validator state
3149 * after a simulated failure:
3152 void lockdep_reset(void)
3154 unsigned long flags;
3157 raw_local_irq_save(flags);
3158 current->curr_chain_key = 0;
3159 current->lockdep_depth = 0;
3160 current->lockdep_recursion = 0;
3161 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3162 nr_hardirq_chains = 0;
3163 nr_softirq_chains = 0;
3164 nr_process_chains = 0;
3166 for (i = 0; i < CHAINHASH_SIZE; i++)
3167 INIT_LIST_HEAD(chainhash_table + i);
3168 raw_local_irq_restore(flags);
3171 static void zap_class(struct lock_class *class)
3176 * Remove all dependencies this lock is
3179 for (i = 0; i < nr_list_entries; i++) {
3180 if (list_entries[i].class == class)
3181 list_del_rcu(&list_entries[i].entry);
3184 * Unhash the class and remove it from the all_lock_classes list:
3186 list_del_rcu(&class->hash_entry);
3187 list_del_rcu(&class->lock_entry);
3192 static inline int within(const void *addr, void *start, unsigned long size)
3194 return addr >= start && addr < start + size;
3197 void lockdep_free_key_range(void *start, unsigned long size)
3199 struct lock_class *class, *next;
3200 struct list_head *head;
3201 unsigned long flags;
3205 raw_local_irq_save(flags);
3206 locked = graph_lock();
3209 * Unhash all classes that were created by this module:
3211 for (i = 0; i < CLASSHASH_SIZE; i++) {
3212 head = classhash_table + i;
3213 if (list_empty(head))
3215 list_for_each_entry_safe(class, next, head, hash_entry) {
3216 if (within(class->key, start, size))
3218 else if (within(class->name, start, size))
3225 raw_local_irq_restore(flags);
3228 void lockdep_reset_lock(struct lockdep_map *lock)
3230 struct lock_class *class, *next;
3231 struct list_head *head;
3232 unsigned long flags;
3236 raw_local_irq_save(flags);
3239 * Remove all classes this lock might have:
3241 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3243 * If the class exists we look it up and zap it:
3245 class = look_up_lock_class(lock, j);
3250 * Debug check: in the end all mapped classes should
3253 locked = graph_lock();
3254 for (i = 0; i < CLASSHASH_SIZE; i++) {
3255 head = classhash_table + i;
3256 if (list_empty(head))
3258 list_for_each_entry_safe(class, next, head, hash_entry) {
3259 if (unlikely(class == lock->class_cache)) {
3260 if (debug_locks_off_graph_unlock())
3270 raw_local_irq_restore(flags);
3273 void lockdep_init(void)
3278 * Some architectures have their own start_kernel()
3279 * code which calls lockdep_init(), while we also
3280 * call lockdep_init() from the start_kernel() itself,
3281 * and we want to initialize the hashes only once:
3283 if (lockdep_initialized)
3286 for (i = 0; i < CLASSHASH_SIZE; i++)
3287 INIT_LIST_HEAD(classhash_table + i);
3289 for (i = 0; i < CHAINHASH_SIZE; i++)
3290 INIT_LIST_HEAD(chainhash_table + i);
3292 lockdep_initialized = 1;
3295 void __init lockdep_info(void)
3297 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3299 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3300 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3301 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3302 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3303 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3304 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3305 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3307 printk(" memory used by lock dependency info: %lu kB\n",
3308 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3309 sizeof(struct list_head) * CLASSHASH_SIZE +
3310 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3311 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3312 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
3314 printk(" per task-struct memory footprint: %lu bytes\n",
3315 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3317 #ifdef CONFIG_DEBUG_LOCKDEP
3318 if (lockdep_init_error) {
3319 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3320 printk("Call stack leading to lockdep invocation was:\n");
3321 print_stack_trace(&lockdep_init_trace, 0);
3327 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3328 const void *mem_to, struct held_lock *hlock)
3330 if (!debug_locks_off())
3332 if (debug_locks_silent)
3335 printk("\n=========================\n");
3336 printk( "[ BUG: held lock freed! ]\n");
3337 printk( "-------------------------\n");
3338 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3339 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3341 lockdep_print_held_locks(curr);
3343 printk("\nstack backtrace:\n");
3347 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3348 const void* lock_from, unsigned long lock_len)
3350 return lock_from + lock_len <= mem_from ||
3351 mem_from + mem_len <= lock_from;
3355 * Called when kernel memory is freed (or unmapped), or if a lock
3356 * is destroyed or reinitialized - this code checks whether there is
3357 * any held lock in the memory range of <from> to <to>:
3359 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3361 struct task_struct *curr = current;
3362 struct held_lock *hlock;
3363 unsigned long flags;
3366 if (unlikely(!debug_locks))
3369 local_irq_save(flags);
3370 for (i = 0; i < curr->lockdep_depth; i++) {
3371 hlock = curr->held_locks + i;
3373 if (not_in_range(mem_from, mem_len, hlock->instance,
3374 sizeof(*hlock->instance)))
3377 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3380 local_irq_restore(flags);
3382 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3384 static void print_held_locks_bug(struct task_struct *curr)
3386 if (!debug_locks_off())
3388 if (debug_locks_silent)
3391 printk("\n=====================================\n");
3392 printk( "[ BUG: lock held at task exit time! ]\n");
3393 printk( "-------------------------------------\n");
3394 printk("%s/%d is exiting with locks still held!\n",
3395 curr->comm, task_pid_nr(curr));
3396 lockdep_print_held_locks(curr);
3398 printk("\nstack backtrace:\n");
3402 void debug_check_no_locks_held(struct task_struct *task)
3404 if (unlikely(task->lockdep_depth > 0))
3405 print_held_locks_bug(task);
3408 void debug_show_all_locks(void)
3410 struct task_struct *g, *p;
3414 if (unlikely(!debug_locks)) {
3415 printk("INFO: lockdep is turned off.\n");
3418 printk("\nShowing all locks held in the system:\n");
3421 * Here we try to get the tasklist_lock as hard as possible,
3422 * if not successful after 2 seconds we ignore it (but keep
3423 * trying). This is to enable a debug printout even if a
3424 * tasklist_lock-holding task deadlocks or crashes.
3427 if (!read_trylock(&tasklist_lock)) {
3429 printk("hm, tasklist_lock locked, retrying... ");
3432 printk(" #%d", 10-count);
3436 printk(" ignoring it.\n");
3440 printk(KERN_CONT " locked it.\n");
3443 do_each_thread(g, p) {
3445 * It's not reliable to print a task's held locks
3446 * if it's not sleeping (or if it's not the current
3449 if (p->state == TASK_RUNNING && p != current)
3451 if (p->lockdep_depth)
3452 lockdep_print_held_locks(p);
3454 if (read_trylock(&tasklist_lock))
3456 } while_each_thread(g, p);
3459 printk("=============================================\n\n");
3462 read_unlock(&tasklist_lock);
3464 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3467 * Careful: only use this function if you are sure that
3468 * the task cannot run in parallel!
3470 void __debug_show_held_locks(struct task_struct *task)
3472 if (unlikely(!debug_locks)) {
3473 printk("INFO: lockdep is turned off.\n");
3476 lockdep_print_held_locks(task);
3478 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3480 void debug_show_held_locks(struct task_struct *task)
3482 __debug_show_held_locks(task);
3484 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3486 void lockdep_sys_exit(void)
3488 struct task_struct *curr = current;
3490 if (unlikely(curr->lockdep_depth)) {
3491 if (!debug_locks_off())
3493 printk("\n================================================\n");
3494 printk( "[ BUG: lock held when returning to user space! ]\n");
3495 printk( "------------------------------------------------\n");
3496 printk("%s/%d is leaving the kernel with locks still held!\n",
3497 curr->comm, curr->pid);
3498 lockdep_print_held_locks(curr);