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
314 # define HARDIRQ_VERBOSE 0
315 # define SOFTIRQ_VERBOSE 0
318 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
320 * Quick filtering for interesting events:
322 static int class_filter(struct lock_class *class)
326 if (class->name_version == 1 &&
327 !strcmp(class->name, "lockname"))
329 if (class->name_version == 1 &&
330 !strcmp(class->name, "&struct->lockfield"))
333 /* Filter everything else. 1 would be to allow everything else */
338 static int verbose(struct lock_class *class)
341 return class_filter(class);
347 * Stack-trace: tightly packed array of stack backtrace
348 * addresses. Protected by the graph_lock.
350 unsigned long nr_stack_trace_entries;
351 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
353 static int save_trace(struct stack_trace *trace)
355 trace->nr_entries = 0;
356 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
357 trace->entries = stack_trace + nr_stack_trace_entries;
361 save_stack_trace(trace);
363 trace->max_entries = trace->nr_entries;
365 nr_stack_trace_entries += trace->nr_entries;
367 if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
368 if (!debug_locks_off_graph_unlock())
371 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
372 printk("turning off the locking correctness validator.\n");
381 unsigned int nr_hardirq_chains;
382 unsigned int nr_softirq_chains;
383 unsigned int nr_process_chains;
384 unsigned int max_lockdep_depth;
385 unsigned int max_recursion_depth;
387 static unsigned int lockdep_dependency_gen_id;
389 static bool lockdep_dependency_visit(struct lock_class *source,
393 lockdep_dependency_gen_id++;
394 if (source->dep_gen_id == lockdep_dependency_gen_id)
396 source->dep_gen_id = lockdep_dependency_gen_id;
400 #ifdef CONFIG_DEBUG_LOCKDEP
402 * We cannot printk in early bootup code. Not even early_printk()
403 * might work. So we mark any initialization errors and printk
404 * about it later on, in lockdep_info().
406 static int lockdep_init_error;
407 static unsigned long lockdep_init_trace_data[20];
408 static struct stack_trace lockdep_init_trace = {
409 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
410 .entries = lockdep_init_trace_data,
414 * Various lockdep statistics:
416 atomic_t chain_lookup_hits;
417 atomic_t chain_lookup_misses;
418 atomic_t hardirqs_on_events;
419 atomic_t hardirqs_off_events;
420 atomic_t redundant_hardirqs_on;
421 atomic_t redundant_hardirqs_off;
422 atomic_t softirqs_on_events;
423 atomic_t softirqs_off_events;
424 atomic_t redundant_softirqs_on;
425 atomic_t redundant_softirqs_off;
426 atomic_t nr_unused_locks;
427 atomic_t nr_cyclic_checks;
428 atomic_t nr_cyclic_check_recursions;
429 atomic_t nr_find_usage_forwards_checks;
430 atomic_t nr_find_usage_forwards_recursions;
431 atomic_t nr_find_usage_backwards_checks;
432 atomic_t nr_find_usage_backwards_recursions;
433 # define debug_atomic_inc(ptr) atomic_inc(ptr)
434 # define debug_atomic_dec(ptr) atomic_dec(ptr)
435 # define debug_atomic_read(ptr) atomic_read(ptr)
437 # define debug_atomic_inc(ptr) do { } while (0)
438 # define debug_atomic_dec(ptr) do { } while (0)
439 # define debug_atomic_read(ptr) 0
446 static const char *usage_str[] =
448 [LOCK_USED] = "initial-use ",
449 [LOCK_USED_IN_HARDIRQ] = "in-hardirq-W",
450 [LOCK_USED_IN_SOFTIRQ] = "in-softirq-W",
451 [LOCK_ENABLED_SOFTIRQS] = "softirq-on-W",
452 [LOCK_ENABLED_HARDIRQS] = "hardirq-on-W",
453 [LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R",
454 [LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R",
455 [LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R",
456 [LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R",
459 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
461 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
465 get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
467 *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
469 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
472 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
475 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
478 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
481 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
483 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
485 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
489 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
491 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
493 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
498 static void print_lock_name(struct lock_class *class)
500 char str[KSYM_NAME_LEN], c1, c2, c3, c4;
503 get_usage_chars(class, &c1, &c2, &c3, &c4);
507 name = __get_key_name(class->key, str);
508 printk(" (%s", name);
510 printk(" (%s", name);
511 if (class->name_version > 1)
512 printk("#%d", class->name_version);
514 printk("/%d", class->subclass);
516 printk("){%c%c%c%c}", c1, c2, c3, c4);
519 static void print_lockdep_cache(struct lockdep_map *lock)
522 char str[KSYM_NAME_LEN];
526 name = __get_key_name(lock->key->subkeys, str);
531 static void print_lock(struct held_lock *hlock)
533 print_lock_name(hlock_class(hlock));
535 print_ip_sym(hlock->acquire_ip);
538 static void lockdep_print_held_locks(struct task_struct *curr)
540 int i, depth = curr->lockdep_depth;
543 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
546 printk("%d lock%s held by %s/%d:\n",
547 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
549 for (i = 0; i < depth; i++) {
551 print_lock(curr->held_locks + i);
555 static void print_lock_class_header(struct lock_class *class, int depth)
559 printk("%*s->", depth, "");
560 print_lock_name(class);
561 printk(" ops: %lu", class->ops);
564 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
565 if (class->usage_mask & (1 << bit)) {
568 len += printk("%*s %s", depth, "", usage_str[bit]);
569 len += printk(" at:\n");
570 print_stack_trace(class->usage_traces + bit, len);
573 printk("%*s }\n", depth, "");
575 printk("%*s ... key at: ",depth,"");
576 print_ip_sym((unsigned long)class->key);
580 * printk all lock dependencies starting at <entry>:
583 print_lock_dependencies(struct lock_class *class, int depth)
585 struct lock_list *entry;
587 if (lockdep_dependency_visit(class, depth))
590 if (DEBUG_LOCKS_WARN_ON(depth >= 20))
593 print_lock_class_header(class, depth);
595 list_for_each_entry(entry, &class->locks_after, entry) {
596 if (DEBUG_LOCKS_WARN_ON(!entry->class))
599 print_lock_dependencies(entry->class, depth + 1);
601 printk("%*s ... acquired at:\n",depth,"");
602 print_stack_trace(&entry->trace, 2);
607 static void print_kernel_version(void)
609 printk("%s %.*s\n", init_utsname()->release,
610 (int)strcspn(init_utsname()->version, " "),
611 init_utsname()->version);
614 static int very_verbose(struct lock_class *class)
617 return class_filter(class);
623 * Is this the address of a static object:
625 static int static_obj(void *obj)
627 unsigned long start = (unsigned long) &_stext,
628 end = (unsigned long) &_end,
629 addr = (unsigned long) obj;
637 if ((addr >= start) && (addr < end))
644 for_each_possible_cpu(i) {
645 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
646 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
649 if ((addr >= start) && (addr < end))
657 return is_module_address(addr);
661 * To make lock name printouts unique, we calculate a unique
662 * class->name_version generation counter:
664 static int count_matching_names(struct lock_class *new_class)
666 struct lock_class *class;
669 if (!new_class->name)
672 list_for_each_entry(class, &all_lock_classes, lock_entry) {
673 if (new_class->key - new_class->subclass == class->key)
674 return class->name_version;
675 if (class->name && !strcmp(class->name, new_class->name))
676 count = max(count, class->name_version);
683 * Register a lock's class in the hash-table, if the class is not present
684 * yet. Otherwise we look it up. We cache the result in the lock object
685 * itself, so actual lookup of the hash should be once per lock object.
687 static inline struct lock_class *
688 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
690 struct lockdep_subclass_key *key;
691 struct list_head *hash_head;
692 struct lock_class *class;
694 #ifdef CONFIG_DEBUG_LOCKDEP
696 * If the architecture calls into lockdep before initializing
697 * the hashes then we'll warn about it later. (we cannot printk
700 if (unlikely(!lockdep_initialized)) {
702 lockdep_init_error = 1;
703 save_stack_trace(&lockdep_init_trace);
708 * Static locks do not have their class-keys yet - for them the key
709 * is the lock object itself:
711 if (unlikely(!lock->key))
712 lock->key = (void *)lock;
715 * NOTE: the class-key must be unique. For dynamic locks, a static
716 * lock_class_key variable is passed in through the mutex_init()
717 * (or spin_lock_init()) call - which acts as the key. For static
718 * locks we use the lock object itself as the key.
720 BUILD_BUG_ON(sizeof(struct lock_class_key) >
721 sizeof(struct lockdep_map));
723 key = lock->key->subkeys + subclass;
725 hash_head = classhashentry(key);
728 * We can walk the hash lockfree, because the hash only
729 * grows, and we are careful when adding entries to the end:
731 list_for_each_entry(class, hash_head, hash_entry) {
732 if (class->key == key) {
733 WARN_ON_ONCE(class->name != lock->name);
742 * Register a lock's class in the hash-table, if the class is not present
743 * yet. Otherwise we look it up. We cache the result in the lock object
744 * itself, so actual lookup of the hash should be once per lock object.
746 static inline struct lock_class *
747 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
749 struct lockdep_subclass_key *key;
750 struct list_head *hash_head;
751 struct lock_class *class;
754 class = look_up_lock_class(lock, subclass);
759 * Debug-check: all keys must be persistent!
761 if (!static_obj(lock->key)) {
763 printk("INFO: trying to register non-static key.\n");
764 printk("the code is fine but needs lockdep annotation.\n");
765 printk("turning off the locking correctness validator.\n");
771 key = lock->key->subkeys + subclass;
772 hash_head = classhashentry(key);
774 raw_local_irq_save(flags);
776 raw_local_irq_restore(flags);
780 * We have to do the hash-walk again, to avoid races
783 list_for_each_entry(class, hash_head, hash_entry)
784 if (class->key == key)
787 * Allocate a new key from the static array, and add it to
790 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
791 if (!debug_locks_off_graph_unlock()) {
792 raw_local_irq_restore(flags);
795 raw_local_irq_restore(flags);
797 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
798 printk("turning off the locking correctness validator.\n");
801 class = lock_classes + nr_lock_classes++;
802 debug_atomic_inc(&nr_unused_locks);
804 class->name = lock->name;
805 class->subclass = subclass;
806 INIT_LIST_HEAD(&class->lock_entry);
807 INIT_LIST_HEAD(&class->locks_before);
808 INIT_LIST_HEAD(&class->locks_after);
809 class->name_version = count_matching_names(class);
811 * We use RCU's safe list-add method to make
812 * parallel walking of the hash-list safe:
814 list_add_tail_rcu(&class->hash_entry, hash_head);
816 * Add it to the global list of classes:
818 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
820 if (verbose(class)) {
822 raw_local_irq_restore(flags);
824 printk("\nnew class %p: %s", class->key, class->name);
825 if (class->name_version > 1)
826 printk("#%d", class->name_version);
830 raw_local_irq_save(flags);
832 raw_local_irq_restore(flags);
838 raw_local_irq_restore(flags);
840 if (!subclass || force)
841 lock->class_cache = class;
843 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
849 #ifdef CONFIG_PROVE_LOCKING
851 * Allocate a lockdep entry. (assumes the graph_lock held, returns
852 * with NULL on failure)
854 static struct lock_list *alloc_list_entry(void)
856 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
857 if (!debug_locks_off_graph_unlock())
860 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
861 printk("turning off the locking correctness validator.\n");
864 return list_entries + nr_list_entries++;
868 * Add a new dependency to the head of the list:
870 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
871 struct list_head *head, unsigned long ip, int distance)
873 struct lock_list *entry;
875 * Lock not present yet - get a new dependency struct and
876 * add it to the list:
878 entry = alloc_list_entry();
882 if (!save_trace(&entry->trace))
886 entry->distance = distance;
888 * Since we never remove from the dependency list, the list can
889 * be walked lockless by other CPUs, it's only allocation
890 * that must be protected by the spinlock. But this also means
891 * we must make new entries visible only once writes to the
892 * entry become visible - hence the RCU op:
894 list_add_tail_rcu(&entry->entry, head);
900 * Recursive, forwards-direction lock-dependency checking, used for
901 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
904 * (to keep the stackframe of the recursive functions small we
905 * use these global variables, and we also mark various helper
906 * functions as noinline.)
908 static struct held_lock *check_source, *check_target;
911 * Print a dependency chain entry (this is only done when a deadlock
912 * has been detected):
915 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
917 if (debug_locks_silent)
919 printk("\n-> #%u", depth);
920 print_lock_name(target->class);
922 print_stack_trace(&target->trace, 6);
928 * When a circular dependency is detected, print the
932 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
934 struct task_struct *curr = current;
936 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
939 printk("\n=======================================================\n");
940 printk( "[ INFO: possible circular locking dependency detected ]\n");
941 print_kernel_version();
942 printk( "-------------------------------------------------------\n");
943 printk("%s/%d is trying to acquire lock:\n",
944 curr->comm, task_pid_nr(curr));
945 print_lock(check_source);
946 printk("\nbut task is already holding lock:\n");
947 print_lock(check_target);
948 printk("\nwhich lock already depends on the new lock.\n\n");
949 printk("\nthe existing dependency chain (in reverse order) is:\n");
951 print_circular_bug_entry(entry, depth);
956 static noinline int print_circular_bug_tail(void)
958 struct task_struct *curr = current;
959 struct lock_list this;
961 if (debug_locks_silent)
964 this.class = hlock_class(check_source);
965 if (!save_trace(&this.trace))
968 print_circular_bug_entry(&this, 0);
970 printk("\nother info that might help us debug this:\n\n");
971 lockdep_print_held_locks(curr);
973 printk("\nstack backtrace:\n");
979 #define RECURSION_LIMIT 40
981 static int noinline print_infinite_recursion_bug(void)
983 if (!debug_locks_off_graph_unlock())
991 unsigned long __lockdep_count_forward_deps(struct lock_class *class,
994 struct lock_list *entry;
995 unsigned long ret = 1;
997 if (lockdep_dependency_visit(class, depth))
1001 * Recurse this class's dependency list:
1003 list_for_each_entry(entry, &class->locks_after, entry)
1004 ret += __lockdep_count_forward_deps(entry->class, depth + 1);
1009 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1011 unsigned long ret, flags;
1013 local_irq_save(flags);
1014 __raw_spin_lock(&lockdep_lock);
1015 ret = __lockdep_count_forward_deps(class, 0);
1016 __raw_spin_unlock(&lockdep_lock);
1017 local_irq_restore(flags);
1022 unsigned long __lockdep_count_backward_deps(struct lock_class *class,
1025 struct lock_list *entry;
1026 unsigned long ret = 1;
1028 if (lockdep_dependency_visit(class, depth))
1031 * Recurse this class's dependency list:
1033 list_for_each_entry(entry, &class->locks_before, entry)
1034 ret += __lockdep_count_backward_deps(entry->class, depth + 1);
1039 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1041 unsigned long ret, flags;
1043 local_irq_save(flags);
1044 __raw_spin_lock(&lockdep_lock);
1045 ret = __lockdep_count_backward_deps(class, 0);
1046 __raw_spin_unlock(&lockdep_lock);
1047 local_irq_restore(flags);
1053 * Prove that the dependency graph starting at <entry> can not
1054 * lead to <target>. Print an error and return 0 if it does.
1057 check_noncircular(struct lock_class *source, unsigned int depth)
1059 struct lock_list *entry;
1061 if (lockdep_dependency_visit(source, depth))
1064 debug_atomic_inc(&nr_cyclic_check_recursions);
1065 if (depth > max_recursion_depth)
1066 max_recursion_depth = depth;
1067 if (depth >= RECURSION_LIMIT)
1068 return print_infinite_recursion_bug();
1070 * Check this lock's dependency list:
1072 list_for_each_entry(entry, &source->locks_after, entry) {
1073 if (entry->class == hlock_class(check_target))
1074 return print_circular_bug_header(entry, depth+1);
1075 debug_atomic_inc(&nr_cyclic_checks);
1076 if (!check_noncircular(entry->class, depth+1))
1077 return print_circular_bug_entry(entry, depth+1);
1082 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1084 * Forwards and backwards subgraph searching, for the purposes of
1085 * proving that two subgraphs can be connected by a new dependency
1086 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1088 static enum lock_usage_bit find_usage_bit;
1089 static struct lock_class *forwards_match, *backwards_match;
1092 * Find a node in the forwards-direction dependency sub-graph starting
1093 * at <source> that matches <find_usage_bit>.
1095 * Return 2 if such a node exists in the subgraph, and put that node
1096 * into <forwards_match>.
1098 * Return 1 otherwise and keep <forwards_match> unchanged.
1099 * Return 0 on error.
1102 find_usage_forwards(struct lock_class *source, unsigned int depth)
1104 struct lock_list *entry;
1107 if (lockdep_dependency_visit(source, depth))
1110 if (depth > max_recursion_depth)
1111 max_recursion_depth = depth;
1112 if (depth >= RECURSION_LIMIT)
1113 return print_infinite_recursion_bug();
1115 debug_atomic_inc(&nr_find_usage_forwards_checks);
1116 if (source->usage_mask & (1 << find_usage_bit)) {
1117 forwards_match = source;
1122 * Check this lock's dependency list:
1124 list_for_each_entry(entry, &source->locks_after, entry) {
1125 debug_atomic_inc(&nr_find_usage_forwards_recursions);
1126 ret = find_usage_forwards(entry->class, depth+1);
1127 if (ret == 2 || ret == 0)
1134 * Find a node in the backwards-direction dependency sub-graph starting
1135 * at <source> that matches <find_usage_bit>.
1137 * Return 2 if such a node exists in the subgraph, and put that node
1138 * into <backwards_match>.
1140 * Return 1 otherwise and keep <backwards_match> unchanged.
1141 * Return 0 on error.
1144 find_usage_backwards(struct lock_class *source, unsigned int depth)
1146 struct lock_list *entry;
1149 if (lockdep_dependency_visit(source, depth))
1152 if (!__raw_spin_is_locked(&lockdep_lock))
1153 return DEBUG_LOCKS_WARN_ON(1);
1155 if (depth > max_recursion_depth)
1156 max_recursion_depth = depth;
1157 if (depth >= RECURSION_LIMIT)
1158 return print_infinite_recursion_bug();
1160 debug_atomic_inc(&nr_find_usage_backwards_checks);
1161 if (source->usage_mask & (1 << find_usage_bit)) {
1162 backwards_match = source;
1166 if (!source && debug_locks_off_graph_unlock()) {
1172 * Check this lock's dependency list:
1174 list_for_each_entry(entry, &source->locks_before, entry) {
1175 debug_atomic_inc(&nr_find_usage_backwards_recursions);
1176 ret = find_usage_backwards(entry->class, depth+1);
1177 if (ret == 2 || ret == 0)
1184 print_bad_irq_dependency(struct task_struct *curr,
1185 struct held_lock *prev,
1186 struct held_lock *next,
1187 enum lock_usage_bit bit1,
1188 enum lock_usage_bit bit2,
1189 const char *irqclass)
1191 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1194 printk("\n======================================================\n");
1195 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1196 irqclass, irqclass);
1197 print_kernel_version();
1198 printk( "------------------------------------------------------\n");
1199 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1200 curr->comm, task_pid_nr(curr),
1201 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1202 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1203 curr->hardirqs_enabled,
1204 curr->softirqs_enabled);
1207 printk("\nand this task is already holding:\n");
1209 printk("which would create a new lock dependency:\n");
1210 print_lock_name(hlock_class(prev));
1212 print_lock_name(hlock_class(next));
1215 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1217 print_lock_name(backwards_match);
1218 printk("\n... which became %s-irq-safe at:\n", irqclass);
1220 print_stack_trace(backwards_match->usage_traces + bit1, 1);
1222 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1223 print_lock_name(forwards_match);
1224 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1227 print_stack_trace(forwards_match->usage_traces + bit2, 1);
1229 printk("\nother info that might help us debug this:\n\n");
1230 lockdep_print_held_locks(curr);
1232 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1233 print_lock_dependencies(backwards_match, 0);
1235 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1236 print_lock_dependencies(forwards_match, 0);
1238 printk("\nstack backtrace:\n");
1245 check_usage(struct task_struct *curr, struct held_lock *prev,
1246 struct held_lock *next, enum lock_usage_bit bit_backwards,
1247 enum lock_usage_bit bit_forwards, const char *irqclass)
1251 find_usage_bit = bit_backwards;
1252 /* fills in <backwards_match> */
1253 ret = find_usage_backwards(hlock_class(prev), 0);
1254 if (!ret || ret == 1)
1257 find_usage_bit = bit_forwards;
1258 ret = find_usage_forwards(hlock_class(next), 0);
1259 if (!ret || ret == 1)
1262 return print_bad_irq_dependency(curr, prev, next,
1263 bit_backwards, bit_forwards, irqclass);
1267 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1268 struct held_lock *next)
1271 * Prove that the new dependency does not connect a hardirq-safe
1272 * lock with a hardirq-unsafe lock - to achieve this we search
1273 * the backwards-subgraph starting at <prev>, and the
1274 * forwards-subgraph starting at <next>:
1276 if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
1277 LOCK_ENABLED_HARDIRQS, "hard"))
1281 * Prove that the new dependency does not connect a hardirq-safe-read
1282 * lock with a hardirq-unsafe lock - to achieve this we search
1283 * the backwards-subgraph starting at <prev>, and the
1284 * forwards-subgraph starting at <next>:
1286 if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
1287 LOCK_ENABLED_HARDIRQS, "hard-read"))
1291 * Prove that the new dependency does not connect a softirq-safe
1292 * lock with a softirq-unsafe lock - to achieve this we search
1293 * the backwards-subgraph starting at <prev>, and the
1294 * forwards-subgraph starting at <next>:
1296 if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
1297 LOCK_ENABLED_SOFTIRQS, "soft"))
1300 * Prove that the new dependency does not connect a softirq-safe-read
1301 * lock with a softirq-unsafe lock - to achieve this we search
1302 * the backwards-subgraph starting at <prev>, and the
1303 * forwards-subgraph starting at <next>:
1305 if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
1306 LOCK_ENABLED_SOFTIRQS, "soft"))
1312 static void inc_chains(void)
1314 if (current->hardirq_context)
1315 nr_hardirq_chains++;
1317 if (current->softirq_context)
1318 nr_softirq_chains++;
1320 nr_process_chains++;
1327 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1328 struct held_lock *next)
1333 static inline void inc_chains(void)
1335 nr_process_chains++;
1341 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1342 struct held_lock *next)
1344 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1347 printk("\n=============================================\n");
1348 printk( "[ INFO: possible recursive locking detected ]\n");
1349 print_kernel_version();
1350 printk( "---------------------------------------------\n");
1351 printk("%s/%d is trying to acquire lock:\n",
1352 curr->comm, task_pid_nr(curr));
1354 printk("\nbut task is already holding lock:\n");
1357 printk("\nother info that might help us debug this:\n");
1358 lockdep_print_held_locks(curr);
1360 printk("\nstack backtrace:\n");
1367 * Check whether we are holding such a class already.
1369 * (Note that this has to be done separately, because the graph cannot
1370 * detect such classes of deadlocks.)
1372 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1375 check_deadlock(struct task_struct *curr, struct held_lock *next,
1376 struct lockdep_map *next_instance, int read)
1378 struct held_lock *prev;
1379 struct held_lock *nest = NULL;
1382 for (i = 0; i < curr->lockdep_depth; i++) {
1383 prev = curr->held_locks + i;
1385 if (prev->instance == next->nest_lock)
1388 if (hlock_class(prev) != hlock_class(next))
1392 * Allow read-after-read recursion of the same
1393 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1395 if ((read == 2) && prev->read)
1399 * We're holding the nest_lock, which serializes this lock's
1400 * nesting behaviour.
1405 return print_deadlock_bug(curr, prev, next);
1411 * There was a chain-cache miss, and we are about to add a new dependency
1412 * to a previous lock. We recursively validate the following rules:
1414 * - would the adding of the <prev> -> <next> dependency create a
1415 * circular dependency in the graph? [== circular deadlock]
1417 * - does the new prev->next dependency connect any hardirq-safe lock
1418 * (in the full backwards-subgraph starting at <prev>) with any
1419 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1420 * <next>)? [== illegal lock inversion with hardirq contexts]
1422 * - does the new prev->next dependency connect any softirq-safe lock
1423 * (in the full backwards-subgraph starting at <prev>) with any
1424 * softirq-unsafe lock (in the full forwards-subgraph starting at
1425 * <next>)? [== illegal lock inversion with softirq contexts]
1427 * any of these scenarios could lead to a deadlock.
1429 * Then if all the validations pass, we add the forwards and backwards
1433 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1434 struct held_lock *next, int distance)
1436 struct lock_list *entry;
1440 * Prove that the new <prev> -> <next> dependency would not
1441 * create a circular dependency in the graph. (We do this by
1442 * forward-recursing into the graph starting at <next>, and
1443 * checking whether we can reach <prev>.)
1445 * We are using global variables to control the recursion, to
1446 * keep the stackframe size of the recursive functions low:
1448 check_source = next;
1449 check_target = prev;
1450 if (!(check_noncircular(hlock_class(next), 0)))
1451 return print_circular_bug_tail();
1453 if (!check_prev_add_irq(curr, prev, next))
1457 * For recursive read-locks we do all the dependency checks,
1458 * but we dont store read-triggered dependencies (only
1459 * write-triggered dependencies). This ensures that only the
1460 * write-side dependencies matter, and that if for example a
1461 * write-lock never takes any other locks, then the reads are
1462 * equivalent to a NOP.
1464 if (next->read == 2 || prev->read == 2)
1467 * Is the <prev> -> <next> dependency already present?
1469 * (this may occur even though this is a new chain: consider
1470 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1471 * chains - the second one will be new, but L1 already has
1472 * L2 added to its dependency list, due to the first chain.)
1474 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1475 if (entry->class == hlock_class(next)) {
1477 entry->distance = 1;
1483 * Ok, all validations passed, add the new lock
1484 * to the previous lock's dependency list:
1486 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1487 &hlock_class(prev)->locks_after,
1488 next->acquire_ip, distance);
1493 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1494 &hlock_class(next)->locks_before,
1495 next->acquire_ip, distance);
1500 * Debugging printouts:
1502 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1504 printk("\n new dependency: ");
1505 print_lock_name(hlock_class(prev));
1507 print_lock_name(hlock_class(next));
1510 return graph_lock();
1516 * Add the dependency to all directly-previous locks that are 'relevant'.
1517 * The ones that are relevant are (in increasing distance from curr):
1518 * all consecutive trylock entries and the final non-trylock entry - or
1519 * the end of this context's lock-chain - whichever comes first.
1522 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1524 int depth = curr->lockdep_depth;
1525 struct held_lock *hlock;
1530 * Depth must not be zero for a non-head lock:
1535 * At least two relevant locks must exist for this
1538 if (curr->held_locks[depth].irq_context !=
1539 curr->held_locks[depth-1].irq_context)
1543 int distance = curr->lockdep_depth - depth + 1;
1544 hlock = curr->held_locks + depth-1;
1546 * Only non-recursive-read entries get new dependencies
1549 if (hlock->read != 2) {
1550 if (!check_prev_add(curr, hlock, next, distance))
1553 * Stop after the first non-trylock entry,
1554 * as non-trylock entries have added their
1555 * own direct dependencies already, so this
1556 * lock is connected to them indirectly:
1558 if (!hlock->trylock)
1563 * End of lock-stack?
1568 * Stop the search if we cross into another context:
1570 if (curr->held_locks[depth].irq_context !=
1571 curr->held_locks[depth-1].irq_context)
1576 if (!debug_locks_off_graph_unlock())
1584 unsigned long nr_lock_chains;
1585 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1586 int nr_chain_hlocks;
1587 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1589 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1591 return lock_classes + chain_hlocks[chain->base + i];
1595 * Look up a dependency chain. If the key is not present yet then
1596 * add it and return 1 - in this case the new dependency chain is
1597 * validated. If the key is already hashed, return 0.
1598 * (On return with 1 graph_lock is held.)
1600 static inline int lookup_chain_cache(struct task_struct *curr,
1601 struct held_lock *hlock,
1604 struct lock_class *class = hlock_class(hlock);
1605 struct list_head *hash_head = chainhashentry(chain_key);
1606 struct lock_chain *chain;
1607 struct held_lock *hlock_curr, *hlock_next;
1610 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1613 * We can walk it lock-free, because entries only get added
1616 list_for_each_entry(chain, hash_head, entry) {
1617 if (chain->chain_key == chain_key) {
1619 debug_atomic_inc(&chain_lookup_hits);
1620 if (very_verbose(class))
1621 printk("\nhash chain already cached, key: "
1622 "%016Lx tail class: [%p] %s\n",
1623 (unsigned long long)chain_key,
1624 class->key, class->name);
1628 if (very_verbose(class))
1629 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1630 (unsigned long long)chain_key, class->key, class->name);
1632 * Allocate a new chain entry from the static array, and add
1638 * We have to walk the chain again locked - to avoid duplicates:
1640 list_for_each_entry(chain, hash_head, entry) {
1641 if (chain->chain_key == chain_key) {
1646 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1647 if (!debug_locks_off_graph_unlock())
1650 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1651 printk("turning off the locking correctness validator.\n");
1654 chain = lock_chains + nr_lock_chains++;
1655 chain->chain_key = chain_key;
1656 chain->irq_context = hlock->irq_context;
1657 /* Find the first held_lock of current chain */
1659 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1660 hlock_curr = curr->held_locks + i;
1661 if (hlock_curr->irq_context != hlock_next->irq_context)
1666 chain->depth = curr->lockdep_depth + 1 - i;
1667 cn = nr_chain_hlocks;
1668 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1669 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1674 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1676 for (j = 0; j < chain->depth - 1; j++, i++) {
1677 int lock_id = curr->held_locks[i].class_idx - 1;
1678 chain_hlocks[chain->base + j] = lock_id;
1680 chain_hlocks[chain->base + j] = class - lock_classes;
1682 list_add_tail_rcu(&chain->entry, hash_head);
1683 debug_atomic_inc(&chain_lookup_misses);
1689 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1690 struct held_lock *hlock, int chain_head, u64 chain_key)
1693 * Trylock needs to maintain the stack of held locks, but it
1694 * does not add new dependencies, because trylock can be done
1697 * We look up the chain_key and do the O(N^2) check and update of
1698 * the dependencies only if this is a new dependency chain.
1699 * (If lookup_chain_cache() returns with 1 it acquires
1700 * graph_lock for us)
1702 if (!hlock->trylock && (hlock->check == 2) &&
1703 lookup_chain_cache(curr, hlock, chain_key)) {
1705 * Check whether last held lock:
1707 * - is irq-safe, if this lock is irq-unsafe
1708 * - is softirq-safe, if this lock is hardirq-unsafe
1710 * And check whether the new lock's dependency graph
1711 * could lead back to the previous lock.
1713 * any of these scenarios could lead to a deadlock. If
1716 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1721 * Mark recursive read, as we jump over it when
1722 * building dependencies (just like we jump over
1728 * Add dependency only if this lock is not the head
1729 * of the chain, and if it's not a secondary read-lock:
1731 if (!chain_head && ret != 2)
1732 if (!check_prevs_add(curr, hlock))
1736 /* after lookup_chain_cache(): */
1737 if (unlikely(!debug_locks))
1743 static inline int validate_chain(struct task_struct *curr,
1744 struct lockdep_map *lock, struct held_lock *hlock,
1745 int chain_head, u64 chain_key)
1752 * We are building curr_chain_key incrementally, so double-check
1753 * it from scratch, to make sure that it's done correctly:
1755 static void check_chain_key(struct task_struct *curr)
1757 #ifdef CONFIG_DEBUG_LOCKDEP
1758 struct held_lock *hlock, *prev_hlock = NULL;
1762 for (i = 0; i < curr->lockdep_depth; i++) {
1763 hlock = curr->held_locks + i;
1764 if (chain_key != hlock->prev_chain_key) {
1766 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1767 curr->lockdep_depth, i,
1768 (unsigned long long)chain_key,
1769 (unsigned long long)hlock->prev_chain_key);
1772 id = hlock->class_idx - 1;
1773 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1776 if (prev_hlock && (prev_hlock->irq_context !=
1777 hlock->irq_context))
1779 chain_key = iterate_chain_key(chain_key, id);
1782 if (chain_key != curr->curr_chain_key) {
1784 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1785 curr->lockdep_depth, i,
1786 (unsigned long long)chain_key,
1787 (unsigned long long)curr->curr_chain_key);
1793 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1794 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1796 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1799 printk("\n=================================\n");
1800 printk( "[ INFO: inconsistent lock state ]\n");
1801 print_kernel_version();
1802 printk( "---------------------------------\n");
1804 printk("inconsistent {%s} -> {%s} usage.\n",
1805 usage_str[prev_bit], usage_str[new_bit]);
1807 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1808 curr->comm, task_pid_nr(curr),
1809 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1810 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1811 trace_hardirqs_enabled(curr),
1812 trace_softirqs_enabled(curr));
1815 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1816 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
1818 print_irqtrace_events(curr);
1819 printk("\nother info that might help us debug this:\n");
1820 lockdep_print_held_locks(curr);
1822 printk("\nstack backtrace:\n");
1829 * Print out an error if an invalid bit is set:
1832 valid_state(struct task_struct *curr, struct held_lock *this,
1833 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1835 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
1836 return print_usage_bug(curr, this, bad_bit, new_bit);
1840 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1841 enum lock_usage_bit new_bit);
1843 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1846 * print irq inversion bug:
1849 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1850 struct held_lock *this, int forwards,
1851 const char *irqclass)
1853 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1856 printk("\n=========================================================\n");
1857 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1858 print_kernel_version();
1859 printk( "---------------------------------------------------------\n");
1860 printk("%s/%d just changed the state of lock:\n",
1861 curr->comm, task_pid_nr(curr));
1864 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1866 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1867 print_lock_name(other);
1868 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1870 printk("\nother info that might help us debug this:\n");
1871 lockdep_print_held_locks(curr);
1873 printk("\nthe first lock's dependencies:\n");
1874 print_lock_dependencies(hlock_class(this), 0);
1876 printk("\nthe second lock's dependencies:\n");
1877 print_lock_dependencies(other, 0);
1879 printk("\nstack backtrace:\n");
1886 * Prove that in the forwards-direction subgraph starting at <this>
1887 * there is no lock matching <mask>:
1890 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1891 enum lock_usage_bit bit, const char *irqclass)
1895 find_usage_bit = bit;
1896 /* fills in <forwards_match> */
1897 ret = find_usage_forwards(hlock_class(this), 0);
1898 if (!ret || ret == 1)
1901 return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1905 * Prove that in the backwards-direction subgraph starting at <this>
1906 * there is no lock matching <mask>:
1909 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1910 enum lock_usage_bit bit, const char *irqclass)
1914 find_usage_bit = bit;
1915 /* fills in <backwards_match> */
1916 ret = find_usage_backwards(hlock_class(this), 0);
1917 if (!ret || ret == 1)
1920 return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1923 void print_irqtrace_events(struct task_struct *curr)
1925 printk("irq event stamp: %u\n", curr->irq_events);
1926 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
1927 print_ip_sym(curr->hardirq_enable_ip);
1928 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1929 print_ip_sym(curr->hardirq_disable_ip);
1930 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
1931 print_ip_sym(curr->softirq_enable_ip);
1932 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1933 print_ip_sym(curr->softirq_disable_ip);
1936 static int hardirq_verbose(struct lock_class *class)
1939 return class_filter(class);
1944 static int softirq_verbose(struct lock_class *class)
1947 return class_filter(class);
1952 #define STRICT_READ_CHECKS 1
1954 static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
1955 enum lock_usage_bit new_bit)
1960 case LOCK_USED_IN_HARDIRQ:
1961 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1963 if (!valid_state(curr, this, new_bit,
1964 LOCK_ENABLED_HARDIRQS_READ))
1967 * just marked it hardirq-safe, check that this lock
1968 * took no hardirq-unsafe lock in the past:
1970 if (!check_usage_forwards(curr, this,
1971 LOCK_ENABLED_HARDIRQS, "hard"))
1973 #if STRICT_READ_CHECKS
1975 * just marked it hardirq-safe, check that this lock
1976 * took no hardirq-unsafe-read lock in the past:
1978 if (!check_usage_forwards(curr, this,
1979 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1982 if (hardirq_verbose(hlock_class(this)))
1985 case LOCK_USED_IN_SOFTIRQ:
1986 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1988 if (!valid_state(curr, this, new_bit,
1989 LOCK_ENABLED_SOFTIRQS_READ))
1992 * just marked it softirq-safe, check that this lock
1993 * took no softirq-unsafe lock in the past:
1995 if (!check_usage_forwards(curr, this,
1996 LOCK_ENABLED_SOFTIRQS, "soft"))
1998 #if STRICT_READ_CHECKS
2000 * just marked it softirq-safe, check that this lock
2001 * took no softirq-unsafe-read lock in the past:
2003 if (!check_usage_forwards(curr, this,
2004 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
2007 if (softirq_verbose(hlock_class(this)))
2010 case LOCK_USED_IN_HARDIRQ_READ:
2011 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
2014 * just marked it hardirq-read-safe, check that this lock
2015 * took no hardirq-unsafe lock in the past:
2017 if (!check_usage_forwards(curr, this,
2018 LOCK_ENABLED_HARDIRQS, "hard"))
2020 if (hardirq_verbose(hlock_class(this)))
2023 case LOCK_USED_IN_SOFTIRQ_READ:
2024 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
2027 * just marked it softirq-read-safe, check that this lock
2028 * took no softirq-unsafe lock in the past:
2030 if (!check_usage_forwards(curr, this,
2031 LOCK_ENABLED_SOFTIRQS, "soft"))
2033 if (softirq_verbose(hlock_class(this)))
2036 case LOCK_ENABLED_HARDIRQS:
2037 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
2039 if (!valid_state(curr, this, new_bit,
2040 LOCK_USED_IN_HARDIRQ_READ))
2043 * just marked it hardirq-unsafe, check that no hardirq-safe
2044 * lock in the system ever took it in the past:
2046 if (!check_usage_backwards(curr, this,
2047 LOCK_USED_IN_HARDIRQ, "hard"))
2049 #if STRICT_READ_CHECKS
2051 * just marked it hardirq-unsafe, check that no
2052 * hardirq-safe-read lock in the system ever took
2055 if (!check_usage_backwards(curr, this,
2056 LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
2059 if (hardirq_verbose(hlock_class(this)))
2062 case LOCK_ENABLED_SOFTIRQS:
2063 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
2065 if (!valid_state(curr, this, new_bit,
2066 LOCK_USED_IN_SOFTIRQ_READ))
2069 * just marked it softirq-unsafe, check that no softirq-safe
2070 * lock in the system ever took it in the past:
2072 if (!check_usage_backwards(curr, this,
2073 LOCK_USED_IN_SOFTIRQ, "soft"))
2075 #if STRICT_READ_CHECKS
2077 * just marked it softirq-unsafe, check that no
2078 * softirq-safe-read lock in the system ever took
2081 if (!check_usage_backwards(curr, this,
2082 LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
2085 if (softirq_verbose(hlock_class(this)))
2088 case LOCK_ENABLED_HARDIRQS_READ:
2089 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
2091 #if STRICT_READ_CHECKS
2093 * just marked it hardirq-read-unsafe, check that no
2094 * hardirq-safe lock in the system ever took it in the past:
2096 if (!check_usage_backwards(curr, this,
2097 LOCK_USED_IN_HARDIRQ, "hard"))
2100 if (hardirq_verbose(hlock_class(this)))
2103 case LOCK_ENABLED_SOFTIRQS_READ:
2104 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
2106 #if STRICT_READ_CHECKS
2108 * just marked it softirq-read-unsafe, check that no
2109 * softirq-safe lock in the system ever took it in the past:
2111 if (!check_usage_backwards(curr, this,
2112 LOCK_USED_IN_SOFTIRQ, "soft"))
2115 if (softirq_verbose(hlock_class(this)))
2127 * Mark all held locks with a usage bit:
2130 mark_held_locks(struct task_struct *curr, int hardirq)
2132 enum lock_usage_bit usage_bit;
2133 struct held_lock *hlock;
2136 for (i = 0; i < curr->lockdep_depth; i++) {
2137 hlock = curr->held_locks + i;
2141 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
2143 usage_bit = LOCK_ENABLED_HARDIRQS;
2146 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
2148 usage_bit = LOCK_ENABLED_SOFTIRQS;
2150 if (!mark_lock(curr, hlock, usage_bit))
2158 * Debugging helper: via this flag we know that we are in
2159 * 'early bootup code', and will warn about any invalid irqs-on event:
2161 static int early_boot_irqs_enabled;
2163 void early_boot_irqs_off(void)
2165 early_boot_irqs_enabled = 0;
2168 void early_boot_irqs_on(void)
2170 early_boot_irqs_enabled = 1;
2174 * Hardirqs will be enabled:
2176 void trace_hardirqs_on_caller(unsigned long ip)
2178 struct task_struct *curr = current;
2180 time_hardirqs_on(CALLER_ADDR0, ip);
2182 if (unlikely(!debug_locks || current->lockdep_recursion))
2185 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2188 if (unlikely(curr->hardirqs_enabled)) {
2189 debug_atomic_inc(&redundant_hardirqs_on);
2192 /* we'll do an OFF -> ON transition: */
2193 curr->hardirqs_enabled = 1;
2195 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2197 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2200 * We are going to turn hardirqs on, so set the
2201 * usage bit for all held locks:
2203 if (!mark_held_locks(curr, 1))
2206 * If we have softirqs enabled, then set the usage
2207 * bit for all held locks. (disabled hardirqs prevented
2208 * this bit from being set before)
2210 if (curr->softirqs_enabled)
2211 if (!mark_held_locks(curr, 0))
2214 curr->hardirq_enable_ip = ip;
2215 curr->hardirq_enable_event = ++curr->irq_events;
2216 debug_atomic_inc(&hardirqs_on_events);
2218 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2220 void trace_hardirqs_on(void)
2222 trace_hardirqs_on_caller(CALLER_ADDR0);
2224 EXPORT_SYMBOL(trace_hardirqs_on);
2227 * Hardirqs were disabled:
2229 void trace_hardirqs_off_caller(unsigned long ip)
2231 struct task_struct *curr = current;
2233 time_hardirqs_off(CALLER_ADDR0, ip);
2235 if (unlikely(!debug_locks || current->lockdep_recursion))
2238 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2241 if (curr->hardirqs_enabled) {
2243 * We have done an ON -> OFF transition:
2245 curr->hardirqs_enabled = 0;
2246 curr->hardirq_disable_ip = ip;
2247 curr->hardirq_disable_event = ++curr->irq_events;
2248 debug_atomic_inc(&hardirqs_off_events);
2250 debug_atomic_inc(&redundant_hardirqs_off);
2252 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2254 void trace_hardirqs_off(void)
2256 trace_hardirqs_off_caller(CALLER_ADDR0);
2258 EXPORT_SYMBOL(trace_hardirqs_off);
2261 * Softirqs will be enabled:
2263 void trace_softirqs_on(unsigned long ip)
2265 struct task_struct *curr = current;
2267 if (unlikely(!debug_locks))
2270 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2273 if (curr->softirqs_enabled) {
2274 debug_atomic_inc(&redundant_softirqs_on);
2279 * We'll do an OFF -> ON transition:
2281 curr->softirqs_enabled = 1;
2282 curr->softirq_enable_ip = ip;
2283 curr->softirq_enable_event = ++curr->irq_events;
2284 debug_atomic_inc(&softirqs_on_events);
2286 * We are going to turn softirqs on, so set the
2287 * usage bit for all held locks, if hardirqs are
2290 if (curr->hardirqs_enabled)
2291 mark_held_locks(curr, 0);
2295 * Softirqs were disabled:
2297 void trace_softirqs_off(unsigned long ip)
2299 struct task_struct *curr = current;
2301 if (unlikely(!debug_locks))
2304 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2307 if (curr->softirqs_enabled) {
2309 * We have done an ON -> OFF transition:
2311 curr->softirqs_enabled = 0;
2312 curr->softirq_disable_ip = ip;
2313 curr->softirq_disable_event = ++curr->irq_events;
2314 debug_atomic_inc(&softirqs_off_events);
2315 DEBUG_LOCKS_WARN_ON(!softirq_count());
2317 debug_atomic_inc(&redundant_softirqs_off);
2320 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2323 * If non-trylock use in a hardirq or softirq context, then
2324 * mark the lock as used in these contexts:
2326 if (!hlock->trylock) {
2328 if (curr->hardirq_context)
2329 if (!mark_lock(curr, hlock,
2330 LOCK_USED_IN_HARDIRQ_READ))
2332 if (curr->softirq_context)
2333 if (!mark_lock(curr, hlock,
2334 LOCK_USED_IN_SOFTIRQ_READ))
2337 if (curr->hardirq_context)
2338 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2340 if (curr->softirq_context)
2341 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2345 if (!hlock->hardirqs_off) {
2347 if (!mark_lock(curr, hlock,
2348 LOCK_ENABLED_HARDIRQS_READ))
2350 if (curr->softirqs_enabled)
2351 if (!mark_lock(curr, hlock,
2352 LOCK_ENABLED_SOFTIRQS_READ))
2355 if (!mark_lock(curr, hlock,
2356 LOCK_ENABLED_HARDIRQS))
2358 if (curr->softirqs_enabled)
2359 if (!mark_lock(curr, hlock,
2360 LOCK_ENABLED_SOFTIRQS))
2368 static int separate_irq_context(struct task_struct *curr,
2369 struct held_lock *hlock)
2371 unsigned int depth = curr->lockdep_depth;
2374 * Keep track of points where we cross into an interrupt context:
2376 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2377 curr->softirq_context;
2379 struct held_lock *prev_hlock;
2381 prev_hlock = curr->held_locks + depth-1;
2383 * If we cross into another context, reset the
2384 * hash key (this also prevents the checking and the
2385 * adding of the dependency to 'prev'):
2387 if (prev_hlock->irq_context != hlock->irq_context)
2396 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2397 enum lock_usage_bit new_bit)
2403 static inline int mark_irqflags(struct task_struct *curr,
2404 struct held_lock *hlock)
2409 static inline int separate_irq_context(struct task_struct *curr,
2410 struct held_lock *hlock)
2418 * Mark a lock with a usage bit, and validate the state transition:
2420 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2421 enum lock_usage_bit new_bit)
2423 unsigned int new_mask = 1 << new_bit, ret = 1;
2426 * If already set then do not dirty the cacheline,
2427 * nor do any checks:
2429 if (likely(hlock_class(this)->usage_mask & new_mask))
2435 * Make sure we didnt race:
2437 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2442 hlock_class(this)->usage_mask |= new_mask;
2444 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2448 case LOCK_USED_IN_HARDIRQ:
2449 case LOCK_USED_IN_SOFTIRQ:
2450 case LOCK_USED_IN_HARDIRQ_READ:
2451 case LOCK_USED_IN_SOFTIRQ_READ:
2452 case LOCK_ENABLED_HARDIRQS:
2453 case LOCK_ENABLED_SOFTIRQS:
2454 case LOCK_ENABLED_HARDIRQS_READ:
2455 case LOCK_ENABLED_SOFTIRQS_READ:
2456 ret = mark_lock_irq(curr, this, new_bit);
2461 debug_atomic_dec(&nr_unused_locks);
2464 if (!debug_locks_off_graph_unlock())
2473 * We must printk outside of the graph_lock:
2476 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2478 print_irqtrace_events(curr);
2486 * Initialize a lock instance's lock-class mapping info:
2488 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2489 struct lock_class_key *key, int subclass)
2491 if (unlikely(!debug_locks))
2494 if (DEBUG_LOCKS_WARN_ON(!key))
2496 if (DEBUG_LOCKS_WARN_ON(!name))
2499 * Sanity check, the lock-class key must be persistent:
2501 if (!static_obj(key)) {
2502 printk("BUG: key %p not in .data!\n", key);
2503 DEBUG_LOCKS_WARN_ON(1);
2508 lock->class_cache = NULL;
2509 #ifdef CONFIG_LOCK_STAT
2510 lock->cpu = raw_smp_processor_id();
2513 register_lock_class(lock, subclass, 1);
2515 EXPORT_SYMBOL_GPL(lockdep_init_map);
2518 * This gets called for every mutex_lock*()/spin_lock*() operation.
2519 * We maintain the dependency maps and validate the locking attempt:
2521 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2522 int trylock, int read, int check, int hardirqs_off,
2523 struct lockdep_map *nest_lock, unsigned long ip)
2525 struct task_struct *curr = current;
2526 struct lock_class *class = NULL;
2527 struct held_lock *hlock;
2528 unsigned int depth, id;
2535 if (unlikely(!debug_locks))
2538 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2541 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2543 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2544 printk("turning off the locking correctness validator.\n");
2549 class = lock->class_cache;
2551 * Not cached yet or subclass?
2553 if (unlikely(!class)) {
2554 class = register_lock_class(lock, subclass, 0);
2558 debug_atomic_inc((atomic_t *)&class->ops);
2559 if (very_verbose(class)) {
2560 printk("\nacquire class [%p] %s", class->key, class->name);
2561 if (class->name_version > 1)
2562 printk("#%d", class->name_version);
2568 * Add the lock to the list of currently held locks.
2569 * (we dont increase the depth just yet, up until the
2570 * dependency checks are done)
2572 depth = curr->lockdep_depth;
2573 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2576 hlock = curr->held_locks + depth;
2577 if (DEBUG_LOCKS_WARN_ON(!class))
2579 hlock->class_idx = class - lock_classes + 1;
2580 hlock->acquire_ip = ip;
2581 hlock->instance = lock;
2582 hlock->nest_lock = nest_lock;
2583 hlock->trylock = trylock;
2585 hlock->check = check;
2586 hlock->hardirqs_off = !!hardirqs_off;
2587 #ifdef CONFIG_LOCK_STAT
2588 hlock->waittime_stamp = 0;
2589 hlock->holdtime_stamp = sched_clock();
2592 if (check == 2 && !mark_irqflags(curr, hlock))
2595 /* mark it as used: */
2596 if (!mark_lock(curr, hlock, LOCK_USED))
2600 * Calculate the chain hash: it's the combined hash of all the
2601 * lock keys along the dependency chain. We save the hash value
2602 * at every step so that we can get the current hash easily
2603 * after unlock. The chain hash is then used to cache dependency
2606 * The 'key ID' is what is the most compact key value to drive
2607 * the hash, not class->key.
2609 id = class - lock_classes;
2610 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2613 chain_key = curr->curr_chain_key;
2615 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2620 hlock->prev_chain_key = chain_key;
2621 if (separate_irq_context(curr, hlock)) {
2625 chain_key = iterate_chain_key(chain_key, id);
2627 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2630 curr->curr_chain_key = chain_key;
2631 curr->lockdep_depth++;
2632 check_chain_key(curr);
2633 #ifdef CONFIG_DEBUG_LOCKDEP
2634 if (unlikely(!debug_locks))
2637 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2639 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2640 printk("turning off the locking correctness validator.\n");
2644 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2645 max_lockdep_depth = curr->lockdep_depth;
2651 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2654 if (!debug_locks_off())
2656 if (debug_locks_silent)
2659 printk("\n=====================================\n");
2660 printk( "[ BUG: bad unlock balance detected! ]\n");
2661 printk( "-------------------------------------\n");
2662 printk("%s/%d is trying to release lock (",
2663 curr->comm, task_pid_nr(curr));
2664 print_lockdep_cache(lock);
2667 printk("but there are no more locks to release!\n");
2668 printk("\nother info that might help us debug this:\n");
2669 lockdep_print_held_locks(curr);
2671 printk("\nstack backtrace:\n");
2678 * Common debugging checks for both nested and non-nested unlock:
2680 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2683 if (unlikely(!debug_locks))
2685 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2688 if (curr->lockdep_depth <= 0)
2689 return print_unlock_inbalance_bug(curr, lock, ip);
2695 __lock_set_class(struct lockdep_map *lock, const char *name,
2696 struct lock_class_key *key, unsigned int subclass,
2699 struct task_struct *curr = current;
2700 struct held_lock *hlock, *prev_hlock;
2701 struct lock_class *class;
2705 depth = curr->lockdep_depth;
2706 if (DEBUG_LOCKS_WARN_ON(!depth))
2710 for (i = depth-1; i >= 0; i--) {
2711 hlock = curr->held_locks + i;
2713 * We must not cross into another context:
2715 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2717 if (hlock->instance == lock)
2721 return print_unlock_inbalance_bug(curr, lock, ip);
2724 lockdep_init_map(lock, name, key, 0);
2725 class = register_lock_class(lock, subclass, 0);
2726 hlock->class_idx = class - lock_classes + 1;
2728 curr->lockdep_depth = i;
2729 curr->curr_chain_key = hlock->prev_chain_key;
2731 for (; i < depth; i++) {
2732 hlock = curr->held_locks + i;
2733 if (!__lock_acquire(hlock->instance,
2734 hlock_class(hlock)->subclass, hlock->trylock,
2735 hlock->read, hlock->check, hlock->hardirqs_off,
2736 hlock->nest_lock, hlock->acquire_ip))
2740 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2746 * Remove the lock to the list of currently held locks in a
2747 * potentially non-nested (out of order) manner. This is a
2748 * relatively rare operation, as all the unlock APIs default
2749 * to nested mode (which uses lock_release()):
2752 lock_release_non_nested(struct task_struct *curr,
2753 struct lockdep_map *lock, unsigned long ip)
2755 struct held_lock *hlock, *prev_hlock;
2760 * Check whether the lock exists in the current stack
2763 depth = curr->lockdep_depth;
2764 if (DEBUG_LOCKS_WARN_ON(!depth))
2768 for (i = depth-1; i >= 0; i--) {
2769 hlock = curr->held_locks + i;
2771 * We must not cross into another context:
2773 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2775 if (hlock->instance == lock)
2779 return print_unlock_inbalance_bug(curr, lock, ip);
2782 lock_release_holdtime(hlock);
2785 * We have the right lock to unlock, 'hlock' points to it.
2786 * Now we remove it from the stack, and add back the other
2787 * entries (if any), recalculating the hash along the way:
2789 curr->lockdep_depth = i;
2790 curr->curr_chain_key = hlock->prev_chain_key;
2792 for (i++; i < depth; i++) {
2793 hlock = curr->held_locks + i;
2794 if (!__lock_acquire(hlock->instance,
2795 hlock_class(hlock)->subclass, hlock->trylock,
2796 hlock->read, hlock->check, hlock->hardirqs_off,
2797 hlock->nest_lock, hlock->acquire_ip))
2801 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2807 * Remove the lock to the list of currently held locks - this gets
2808 * called on mutex_unlock()/spin_unlock*() (or on a failed
2809 * mutex_lock_interruptible()). This is done for unlocks that nest
2810 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2812 static int lock_release_nested(struct task_struct *curr,
2813 struct lockdep_map *lock, unsigned long ip)
2815 struct held_lock *hlock;
2819 * Pop off the top of the lock stack:
2821 depth = curr->lockdep_depth - 1;
2822 hlock = curr->held_locks + depth;
2825 * Is the unlock non-nested:
2827 if (hlock->instance != lock)
2828 return lock_release_non_nested(curr, lock, ip);
2829 curr->lockdep_depth--;
2831 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2834 curr->curr_chain_key = hlock->prev_chain_key;
2836 lock_release_holdtime(hlock);
2838 #ifdef CONFIG_DEBUG_LOCKDEP
2839 hlock->prev_chain_key = 0;
2840 hlock->class_idx = 0;
2841 hlock->acquire_ip = 0;
2842 hlock->irq_context = 0;
2848 * Remove the lock to the list of currently held locks - this gets
2849 * called on mutex_unlock()/spin_unlock*() (or on a failed
2850 * mutex_lock_interruptible()). This is done for unlocks that nest
2851 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2854 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2856 struct task_struct *curr = current;
2858 if (!check_unlock(curr, lock, ip))
2862 if (!lock_release_nested(curr, lock, ip))
2865 if (!lock_release_non_nested(curr, lock, ip))
2869 check_chain_key(curr);
2873 * Check whether we follow the irq-flags state precisely:
2875 static void check_flags(unsigned long flags)
2877 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2878 defined(CONFIG_TRACE_IRQFLAGS)
2882 if (irqs_disabled_flags(flags)) {
2883 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
2884 printk("possible reason: unannotated irqs-off.\n");
2887 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
2888 printk("possible reason: unannotated irqs-on.\n");
2893 * We dont accurately track softirq state in e.g.
2894 * hardirq contexts (such as on 4KSTACKS), so only
2895 * check if not in hardirq contexts:
2897 if (!hardirq_count()) {
2898 if (softirq_count())
2899 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2901 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2905 print_irqtrace_events(current);
2909 void lock_set_class(struct lockdep_map *lock, const char *name,
2910 struct lock_class_key *key, unsigned int subclass,
2913 unsigned long flags;
2915 if (unlikely(current->lockdep_recursion))
2918 raw_local_irq_save(flags);
2919 current->lockdep_recursion = 1;
2921 if (__lock_set_class(lock, name, key, subclass, ip))
2922 check_chain_key(current);
2923 current->lockdep_recursion = 0;
2924 raw_local_irq_restore(flags);
2926 EXPORT_SYMBOL_GPL(lock_set_class);
2929 * We are not always called with irqs disabled - do that here,
2930 * and also avoid lockdep recursion:
2932 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2933 int trylock, int read, int check,
2934 struct lockdep_map *nest_lock, unsigned long ip)
2936 unsigned long flags;
2938 if (unlikely(current->lockdep_recursion))
2941 raw_local_irq_save(flags);
2944 current->lockdep_recursion = 1;
2945 __lock_acquire(lock, subclass, trylock, read, check,
2946 irqs_disabled_flags(flags), nest_lock, ip);
2947 current->lockdep_recursion = 0;
2948 raw_local_irq_restore(flags);
2950 EXPORT_SYMBOL_GPL(lock_acquire);
2952 void lock_release(struct lockdep_map *lock, int nested,
2955 unsigned long flags;
2957 if (unlikely(current->lockdep_recursion))
2960 raw_local_irq_save(flags);
2962 current->lockdep_recursion = 1;
2963 __lock_release(lock, nested, ip);
2964 current->lockdep_recursion = 0;
2965 raw_local_irq_restore(flags);
2967 EXPORT_SYMBOL_GPL(lock_release);
2969 #ifdef CONFIG_LOCK_STAT
2971 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
2974 if (!debug_locks_off())
2976 if (debug_locks_silent)
2979 printk("\n=================================\n");
2980 printk( "[ BUG: bad contention detected! ]\n");
2981 printk( "---------------------------------\n");
2982 printk("%s/%d is trying to contend lock (",
2983 curr->comm, task_pid_nr(curr));
2984 print_lockdep_cache(lock);
2987 printk("but there are no locks held!\n");
2988 printk("\nother info that might help us debug this:\n");
2989 lockdep_print_held_locks(curr);
2991 printk("\nstack backtrace:\n");
2998 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3000 struct task_struct *curr = current;
3001 struct held_lock *hlock, *prev_hlock;
3002 struct lock_class_stats *stats;
3004 int i, contention_point, contending_point;
3006 depth = curr->lockdep_depth;
3007 if (DEBUG_LOCKS_WARN_ON(!depth))
3011 for (i = depth-1; i >= 0; i--) {
3012 hlock = curr->held_locks + i;
3014 * We must not cross into another context:
3016 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3018 if (hlock->instance == lock)
3022 print_lock_contention_bug(curr, lock, ip);
3026 hlock->waittime_stamp = sched_clock();
3028 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3029 contending_point = lock_point(hlock_class(hlock)->contending_point,
3032 stats = get_lock_stats(hlock_class(hlock));
3033 if (contention_point < LOCKSTAT_POINTS)
3034 stats->contention_point[contention_point]++;
3035 if (contending_point < LOCKSTAT_POINTS)
3036 stats->contending_point[contending_point]++;
3037 if (lock->cpu != smp_processor_id())
3038 stats->bounces[bounce_contended + !!hlock->read]++;
3039 put_lock_stats(stats);
3043 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3045 struct task_struct *curr = current;
3046 struct held_lock *hlock, *prev_hlock;
3047 struct lock_class_stats *stats;
3053 depth = curr->lockdep_depth;
3054 if (DEBUG_LOCKS_WARN_ON(!depth))
3058 for (i = depth-1; i >= 0; i--) {
3059 hlock = curr->held_locks + i;
3061 * We must not cross into another context:
3063 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3065 if (hlock->instance == lock)
3069 print_lock_contention_bug(curr, lock, _RET_IP_);
3073 cpu = smp_processor_id();
3074 if (hlock->waittime_stamp) {
3075 now = sched_clock();
3076 waittime = now - hlock->waittime_stamp;
3077 hlock->holdtime_stamp = now;
3080 stats = get_lock_stats(hlock_class(hlock));
3083 lock_time_inc(&stats->read_waittime, waittime);
3085 lock_time_inc(&stats->write_waittime, waittime);
3087 if (lock->cpu != cpu)
3088 stats->bounces[bounce_acquired + !!hlock->read]++;
3089 put_lock_stats(stats);
3095 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3097 unsigned long flags;
3099 if (unlikely(!lock_stat))
3102 if (unlikely(current->lockdep_recursion))
3105 raw_local_irq_save(flags);
3107 current->lockdep_recursion = 1;
3108 __lock_contended(lock, ip);
3109 current->lockdep_recursion = 0;
3110 raw_local_irq_restore(flags);
3112 EXPORT_SYMBOL_GPL(lock_contended);
3114 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3116 unsigned long flags;
3118 if (unlikely(!lock_stat))
3121 if (unlikely(current->lockdep_recursion))
3124 raw_local_irq_save(flags);
3126 current->lockdep_recursion = 1;
3127 __lock_acquired(lock, ip);
3128 current->lockdep_recursion = 0;
3129 raw_local_irq_restore(flags);
3131 EXPORT_SYMBOL_GPL(lock_acquired);
3135 * Used by the testsuite, sanitize the validator state
3136 * after a simulated failure:
3139 void lockdep_reset(void)
3141 unsigned long flags;
3144 raw_local_irq_save(flags);
3145 current->curr_chain_key = 0;
3146 current->lockdep_depth = 0;
3147 current->lockdep_recursion = 0;
3148 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3149 nr_hardirq_chains = 0;
3150 nr_softirq_chains = 0;
3151 nr_process_chains = 0;
3153 for (i = 0; i < CHAINHASH_SIZE; i++)
3154 INIT_LIST_HEAD(chainhash_table + i);
3155 raw_local_irq_restore(flags);
3158 static void zap_class(struct lock_class *class)
3163 * Remove all dependencies this lock is
3166 for (i = 0; i < nr_list_entries; i++) {
3167 if (list_entries[i].class == class)
3168 list_del_rcu(&list_entries[i].entry);
3171 * Unhash the class and remove it from the all_lock_classes list:
3173 list_del_rcu(&class->hash_entry);
3174 list_del_rcu(&class->lock_entry);
3179 static inline int within(const void *addr, void *start, unsigned long size)
3181 return addr >= start && addr < start + size;
3184 void lockdep_free_key_range(void *start, unsigned long size)
3186 struct lock_class *class, *next;
3187 struct list_head *head;
3188 unsigned long flags;
3192 raw_local_irq_save(flags);
3193 locked = graph_lock();
3196 * Unhash all classes that were created by this module:
3198 for (i = 0; i < CLASSHASH_SIZE; i++) {
3199 head = classhash_table + i;
3200 if (list_empty(head))
3202 list_for_each_entry_safe(class, next, head, hash_entry) {
3203 if (within(class->key, start, size))
3205 else if (within(class->name, start, size))
3212 raw_local_irq_restore(flags);
3215 void lockdep_reset_lock(struct lockdep_map *lock)
3217 struct lock_class *class, *next;
3218 struct list_head *head;
3219 unsigned long flags;
3223 raw_local_irq_save(flags);
3226 * Remove all classes this lock might have:
3228 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3230 * If the class exists we look it up and zap it:
3232 class = look_up_lock_class(lock, j);
3237 * Debug check: in the end all mapped classes should
3240 locked = graph_lock();
3241 for (i = 0; i < CLASSHASH_SIZE; i++) {
3242 head = classhash_table + i;
3243 if (list_empty(head))
3245 list_for_each_entry_safe(class, next, head, hash_entry) {
3246 if (unlikely(class == lock->class_cache)) {
3247 if (debug_locks_off_graph_unlock())
3257 raw_local_irq_restore(flags);
3260 void lockdep_init(void)
3265 * Some architectures have their own start_kernel()
3266 * code which calls lockdep_init(), while we also
3267 * call lockdep_init() from the start_kernel() itself,
3268 * and we want to initialize the hashes only once:
3270 if (lockdep_initialized)
3273 for (i = 0; i < CLASSHASH_SIZE; i++)
3274 INIT_LIST_HEAD(classhash_table + i);
3276 for (i = 0; i < CHAINHASH_SIZE; i++)
3277 INIT_LIST_HEAD(chainhash_table + i);
3279 lockdep_initialized = 1;
3282 void __init lockdep_info(void)
3284 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3286 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3287 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3288 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3289 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3290 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3291 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3292 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3294 printk(" memory used by lock dependency info: %lu kB\n",
3295 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3296 sizeof(struct list_head) * CLASSHASH_SIZE +
3297 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3298 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3299 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
3301 printk(" per task-struct memory footprint: %lu bytes\n",
3302 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3304 #ifdef CONFIG_DEBUG_LOCKDEP
3305 if (lockdep_init_error) {
3306 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3307 printk("Call stack leading to lockdep invocation was:\n");
3308 print_stack_trace(&lockdep_init_trace, 0);
3314 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3315 const void *mem_to, struct held_lock *hlock)
3317 if (!debug_locks_off())
3319 if (debug_locks_silent)
3322 printk("\n=========================\n");
3323 printk( "[ BUG: held lock freed! ]\n");
3324 printk( "-------------------------\n");
3325 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3326 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3328 lockdep_print_held_locks(curr);
3330 printk("\nstack backtrace:\n");
3334 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3335 const void* lock_from, unsigned long lock_len)
3337 return lock_from + lock_len <= mem_from ||
3338 mem_from + mem_len <= lock_from;
3342 * Called when kernel memory is freed (or unmapped), or if a lock
3343 * is destroyed or reinitialized - this code checks whether there is
3344 * any held lock in the memory range of <from> to <to>:
3346 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3348 struct task_struct *curr = current;
3349 struct held_lock *hlock;
3350 unsigned long flags;
3353 if (unlikely(!debug_locks))
3356 local_irq_save(flags);
3357 for (i = 0; i < curr->lockdep_depth; i++) {
3358 hlock = curr->held_locks + i;
3360 if (not_in_range(mem_from, mem_len, hlock->instance,
3361 sizeof(*hlock->instance)))
3364 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3367 local_irq_restore(flags);
3369 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3371 static void print_held_locks_bug(struct task_struct *curr)
3373 if (!debug_locks_off())
3375 if (debug_locks_silent)
3378 printk("\n=====================================\n");
3379 printk( "[ BUG: lock held at task exit time! ]\n");
3380 printk( "-------------------------------------\n");
3381 printk("%s/%d is exiting with locks still held!\n",
3382 curr->comm, task_pid_nr(curr));
3383 lockdep_print_held_locks(curr);
3385 printk("\nstack backtrace:\n");
3389 void debug_check_no_locks_held(struct task_struct *task)
3391 if (unlikely(task->lockdep_depth > 0))
3392 print_held_locks_bug(task);
3395 void debug_show_all_locks(void)
3397 struct task_struct *g, *p;
3401 if (unlikely(!debug_locks)) {
3402 printk("INFO: lockdep is turned off.\n");
3405 printk("\nShowing all locks held in the system:\n");
3408 * Here we try to get the tasklist_lock as hard as possible,
3409 * if not successful after 2 seconds we ignore it (but keep
3410 * trying). This is to enable a debug printout even if a
3411 * tasklist_lock-holding task deadlocks or crashes.
3414 if (!read_trylock(&tasklist_lock)) {
3416 printk("hm, tasklist_lock locked, retrying... ");
3419 printk(" #%d", 10-count);
3423 printk(" ignoring it.\n");
3427 printk(KERN_CONT " locked it.\n");
3430 do_each_thread(g, p) {
3432 * It's not reliable to print a task's held locks
3433 * if it's not sleeping (or if it's not the current
3436 if (p->state == TASK_RUNNING && p != current)
3438 if (p->lockdep_depth)
3439 lockdep_print_held_locks(p);
3441 if (read_trylock(&tasklist_lock))
3443 } while_each_thread(g, p);
3446 printk("=============================================\n\n");
3449 read_unlock(&tasklist_lock);
3451 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3454 * Careful: only use this function if you are sure that
3455 * the task cannot run in parallel!
3457 void __debug_show_held_locks(struct task_struct *task)
3459 if (unlikely(!debug_locks)) {
3460 printk("INFO: lockdep is turned off.\n");
3463 lockdep_print_held_locks(task);
3465 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3467 void debug_show_held_locks(struct task_struct *task)
3469 __debug_show_held_locks(task);
3471 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3473 void lockdep_sys_exit(void)
3475 struct task_struct *curr = current;
3477 if (unlikely(curr->lockdep_depth)) {
3478 if (!debug_locks_off())
3480 printk("\n================================================\n");
3481 printk( "[ BUG: lock held when returning to user space! ]\n");
3482 printk( "------------------------------------------------\n");
3483 printk("%s/%d is leaving the kernel with locks still held!\n",
3484 curr->comm, curr->pid);
3485 lockdep_print_held_locks(curr);