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 #include <linux/mutex.h>
29 #include <linux/sched.h>
30 #include <linux/delay.h>
31 #include <linux/module.h>
32 #include <linux/proc_fs.h>
33 #include <linux/seq_file.h>
34 #include <linux/spinlock.h>
35 #include <linux/kallsyms.h>
36 #include <linux/interrupt.h>
37 #include <linux/stacktrace.h>
38 #include <linux/debug_locks.h>
39 #include <linux/irqflags.h>
40 #include <linux/utsname.h>
41 #include <linux/hash.h>
42 #include <linux/ftrace.h>
44 #include <asm/sections.h>
46 #include "lockdep_internals.h"
48 #ifdef CONFIG_PROVE_LOCKING
49 int prove_locking = 1;
50 module_param(prove_locking, int, 0644);
52 #define prove_locking 0
55 #ifdef CONFIG_LOCK_STAT
57 module_param(lock_stat, int, 0644);
63 * lockdep_lock: protects the lockdep graph, the hashes and the
64 * class/list/hash allocators.
66 * This is one of the rare exceptions where it's justified
67 * to use a raw spinlock - we really dont want the spinlock
68 * code to recurse back into the lockdep code...
70 static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
72 static int graph_lock(void)
74 __raw_spin_lock(&lockdep_lock);
76 * Make sure that if another CPU detected a bug while
77 * walking the graph we dont change it (while the other
78 * CPU is busy printing out stuff with the graph lock
82 __raw_spin_unlock(&lockdep_lock);
85 /* prevent any recursions within lockdep from causing deadlocks */
86 current->lockdep_recursion++;
90 static inline int graph_unlock(void)
92 if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
93 return DEBUG_LOCKS_WARN_ON(1);
95 current->lockdep_recursion--;
96 __raw_spin_unlock(&lockdep_lock);
101 * Turn lock debugging off and return with 0 if it was off already,
102 * and also release the graph lock:
104 static inline int debug_locks_off_graph_unlock(void)
106 int ret = debug_locks_off();
108 __raw_spin_unlock(&lockdep_lock);
113 static int lockdep_initialized;
115 unsigned long nr_list_entries;
116 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
119 * All data structures here are protected by the global debug_lock.
121 * Mutex key structs only get allocated, once during bootup, and never
122 * get freed - this significantly simplifies the debugging code.
124 unsigned long nr_lock_classes;
125 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
127 #ifdef CONFIG_LOCK_STAT
128 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
130 static int lock_contention_point(struct lock_class *class, unsigned long ip)
134 for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {
135 if (class->contention_point[i] == 0) {
136 class->contention_point[i] = ip;
139 if (class->contention_point[i] == ip)
146 static void lock_time_inc(struct lock_time *lt, s64 time)
151 if (time < lt->min || !lt->min)
158 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
160 dst->min += src->min;
161 dst->max += src->max;
162 dst->total += src->total;
166 struct lock_class_stats lock_stats(struct lock_class *class)
168 struct lock_class_stats stats;
171 memset(&stats, 0, sizeof(struct lock_class_stats));
172 for_each_possible_cpu(cpu) {
173 struct lock_class_stats *pcs =
174 &per_cpu(lock_stats, cpu)[class - lock_classes];
176 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
177 stats.contention_point[i] += pcs->contention_point[i];
179 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
180 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
182 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
183 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
185 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
186 stats.bounces[i] += pcs->bounces[i];
192 void clear_lock_stats(struct lock_class *class)
196 for_each_possible_cpu(cpu) {
197 struct lock_class_stats *cpu_stats =
198 &per_cpu(lock_stats, cpu)[class - lock_classes];
200 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
202 memset(class->contention_point, 0, sizeof(class->contention_point));
205 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
207 return &get_cpu_var(lock_stats)[class - lock_classes];
210 static void put_lock_stats(struct lock_class_stats *stats)
212 put_cpu_var(lock_stats);
215 static void lock_release_holdtime(struct held_lock *hlock)
217 struct lock_class_stats *stats;
223 holdtime = sched_clock() - hlock->holdtime_stamp;
225 stats = get_lock_stats(hlock->class);
227 lock_time_inc(&stats->read_holdtime, holdtime);
229 lock_time_inc(&stats->write_holdtime, holdtime);
230 put_lock_stats(stats);
233 static inline void lock_release_holdtime(struct held_lock *hlock)
239 * We keep a global list of all lock classes. The list only grows,
240 * never shrinks. The list is only accessed with the lockdep
241 * spinlock lock held.
243 LIST_HEAD(all_lock_classes);
246 * The lockdep classes are in a hash-table as well, for fast lookup:
248 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
249 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
250 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
251 #define classhashentry(key) (classhash_table + __classhashfn((key)))
253 static struct list_head classhash_table[CLASSHASH_SIZE];
256 * We put the lock dependency chains into a hash-table as well, to cache
259 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
260 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
261 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
262 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
264 static struct list_head chainhash_table[CHAINHASH_SIZE];
267 * The hash key of the lock dependency chains is a hash itself too:
268 * it's a hash of all locks taken up to that lock, including that lock.
269 * It's a 64-bit hash, because it's important for the keys to be
272 #define iterate_chain_key(key1, key2) \
273 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
274 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
277 void lockdep_off(void)
279 current->lockdep_recursion++;
282 EXPORT_SYMBOL(lockdep_off);
284 void lockdep_on(void)
286 current->lockdep_recursion--;
289 EXPORT_SYMBOL(lockdep_on);
292 * Debugging switches:
296 #define VERY_VERBOSE 0
299 # define HARDIRQ_VERBOSE 1
300 # define SOFTIRQ_VERBOSE 1
302 # define HARDIRQ_VERBOSE 0
303 # define SOFTIRQ_VERBOSE 0
306 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
308 * Quick filtering for interesting events:
310 static int class_filter(struct lock_class *class)
314 if (class->name_version == 1 &&
315 !strcmp(class->name, "lockname"))
317 if (class->name_version == 1 &&
318 !strcmp(class->name, "&struct->lockfield"))
321 /* Filter everything else. 1 would be to allow everything else */
326 static int verbose(struct lock_class *class)
329 return class_filter(class);
335 * Stack-trace: tightly packed array of stack backtrace
336 * addresses. Protected by the graph_lock.
338 unsigned long nr_stack_trace_entries;
339 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
341 static int save_trace(struct stack_trace *trace)
343 trace->nr_entries = 0;
344 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
345 trace->entries = stack_trace + nr_stack_trace_entries;
349 save_stack_trace(trace);
351 trace->max_entries = trace->nr_entries;
353 nr_stack_trace_entries += trace->nr_entries;
355 if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
356 if (!debug_locks_off_graph_unlock())
359 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
360 printk("turning off the locking correctness validator.\n");
369 unsigned int nr_hardirq_chains;
370 unsigned int nr_softirq_chains;
371 unsigned int nr_process_chains;
372 unsigned int max_lockdep_depth;
373 unsigned int max_recursion_depth;
375 static unsigned int lockdep_dependency_gen_id;
377 static bool lockdep_dependency_visit(struct lock_class *source,
381 lockdep_dependency_gen_id++;
382 if (source->dep_gen_id == lockdep_dependency_gen_id)
384 source->dep_gen_id = lockdep_dependency_gen_id;
388 #ifdef CONFIG_DEBUG_LOCKDEP
390 * We cannot printk in early bootup code. Not even early_printk()
391 * might work. So we mark any initialization errors and printk
392 * about it later on, in lockdep_info().
394 static int lockdep_init_error;
395 static unsigned long lockdep_init_trace_data[20];
396 static struct stack_trace lockdep_init_trace = {
397 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
398 .entries = lockdep_init_trace_data,
402 * Various lockdep statistics:
404 atomic_t chain_lookup_hits;
405 atomic_t chain_lookup_misses;
406 atomic_t hardirqs_on_events;
407 atomic_t hardirqs_off_events;
408 atomic_t redundant_hardirqs_on;
409 atomic_t redundant_hardirqs_off;
410 atomic_t softirqs_on_events;
411 atomic_t softirqs_off_events;
412 atomic_t redundant_softirqs_on;
413 atomic_t redundant_softirqs_off;
414 atomic_t nr_unused_locks;
415 atomic_t nr_cyclic_checks;
416 atomic_t nr_cyclic_check_recursions;
417 atomic_t nr_find_usage_forwards_checks;
418 atomic_t nr_find_usage_forwards_recursions;
419 atomic_t nr_find_usage_backwards_checks;
420 atomic_t nr_find_usage_backwards_recursions;
421 # define debug_atomic_inc(ptr) atomic_inc(ptr)
422 # define debug_atomic_dec(ptr) atomic_dec(ptr)
423 # define debug_atomic_read(ptr) atomic_read(ptr)
425 # define debug_atomic_inc(ptr) do { } while (0)
426 # define debug_atomic_dec(ptr) do { } while (0)
427 # define debug_atomic_read(ptr) 0
434 static const char *usage_str[] =
436 [LOCK_USED] = "initial-use ",
437 [LOCK_USED_IN_HARDIRQ] = "in-hardirq-W",
438 [LOCK_USED_IN_SOFTIRQ] = "in-softirq-W",
439 [LOCK_ENABLED_SOFTIRQS] = "softirq-on-W",
440 [LOCK_ENABLED_HARDIRQS] = "hardirq-on-W",
441 [LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R",
442 [LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R",
443 [LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R",
444 [LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R",
447 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
449 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
453 get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
455 *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
457 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
460 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
463 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
466 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
469 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
471 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
473 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
477 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
479 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
481 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
486 static void print_lock_name(struct lock_class *class)
488 char str[KSYM_NAME_LEN], c1, c2, c3, c4;
491 get_usage_chars(class, &c1, &c2, &c3, &c4);
495 name = __get_key_name(class->key, str);
496 printk(" (%s", name);
498 printk(" (%s", name);
499 if (class->name_version > 1)
500 printk("#%d", class->name_version);
502 printk("/%d", class->subclass);
504 printk("){%c%c%c%c}", c1, c2, c3, c4);
507 static void print_lockdep_cache(struct lockdep_map *lock)
510 char str[KSYM_NAME_LEN];
514 name = __get_key_name(lock->key->subkeys, str);
519 static void print_lock(struct held_lock *hlock)
521 print_lock_name(hlock->class);
523 print_ip_sym(hlock->acquire_ip);
526 static void lockdep_print_held_locks(struct task_struct *curr)
528 int i, depth = curr->lockdep_depth;
531 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
534 printk("%d lock%s held by %s/%d:\n",
535 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
537 for (i = 0; i < depth; i++) {
539 print_lock(curr->held_locks + i);
543 static void print_lock_class_header(struct lock_class *class, int depth)
547 printk("%*s->", depth, "");
548 print_lock_name(class);
549 printk(" ops: %lu", class->ops);
552 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
553 if (class->usage_mask & (1 << bit)) {
556 len += printk("%*s %s", depth, "", usage_str[bit]);
557 len += printk(" at:\n");
558 print_stack_trace(class->usage_traces + bit, len);
561 printk("%*s }\n", depth, "");
563 printk("%*s ... key at: ",depth,"");
564 print_ip_sym((unsigned long)class->key);
568 * printk all lock dependencies starting at <entry>:
570 static void print_lock_dependencies(struct lock_class *class, int depth)
572 struct lock_list *entry;
574 if (lockdep_dependency_visit(class, depth))
577 if (DEBUG_LOCKS_WARN_ON(depth >= 20))
580 print_lock_class_header(class, depth);
582 list_for_each_entry(entry, &class->locks_after, entry) {
583 if (DEBUG_LOCKS_WARN_ON(!entry->class))
586 print_lock_dependencies(entry->class, depth + 1);
588 printk("%*s ... acquired at:\n",depth,"");
589 print_stack_trace(&entry->trace, 2);
594 static void print_kernel_version(void)
596 printk("%s %.*s\n", init_utsname()->release,
597 (int)strcspn(init_utsname()->version, " "),
598 init_utsname()->version);
601 static int very_verbose(struct lock_class *class)
604 return class_filter(class);
610 * Is this the address of a static object:
612 static int static_obj(void *obj)
614 unsigned long start = (unsigned long) &_stext,
615 end = (unsigned long) &_end,
616 addr = (unsigned long) obj;
624 if ((addr >= start) && (addr < end))
631 for_each_possible_cpu(i) {
632 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
633 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
636 if ((addr >= start) && (addr < end))
644 return is_module_address(addr);
648 * To make lock name printouts unique, we calculate a unique
649 * class->name_version generation counter:
651 static int count_matching_names(struct lock_class *new_class)
653 struct lock_class *class;
656 if (!new_class->name)
659 list_for_each_entry(class, &all_lock_classes, lock_entry) {
660 if (new_class->key - new_class->subclass == class->key)
661 return class->name_version;
662 if (class->name && !strcmp(class->name, new_class->name))
663 count = max(count, class->name_version);
670 * Register a lock's class in the hash-table, if the class is not present
671 * yet. Otherwise we look it up. We cache the result in the lock object
672 * itself, so actual lookup of the hash should be once per lock object.
674 static inline struct lock_class *
675 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
677 struct lockdep_subclass_key *key;
678 struct list_head *hash_head;
679 struct lock_class *class;
681 #ifdef CONFIG_DEBUG_LOCKDEP
683 * If the architecture calls into lockdep before initializing
684 * the hashes then we'll warn about it later. (we cannot printk
687 if (unlikely(!lockdep_initialized)) {
689 lockdep_init_error = 1;
690 save_stack_trace(&lockdep_init_trace);
695 * Static locks do not have their class-keys yet - for them the key
696 * is the lock object itself:
698 if (unlikely(!lock->key))
699 lock->key = (void *)lock;
702 * NOTE: the class-key must be unique. For dynamic locks, a static
703 * lock_class_key variable is passed in through the mutex_init()
704 * (or spin_lock_init()) call - which acts as the key. For static
705 * locks we use the lock object itself as the key.
707 BUILD_BUG_ON(sizeof(struct lock_class_key) >
708 sizeof(struct lockdep_map));
710 key = lock->key->subkeys + subclass;
712 hash_head = classhashentry(key);
715 * We can walk the hash lockfree, because the hash only
716 * grows, and we are careful when adding entries to the end:
718 list_for_each_entry(class, hash_head, hash_entry) {
719 if (class->key == key) {
720 WARN_ON_ONCE(class->name != lock->name);
729 * Register a lock's class in the hash-table, if the class is not present
730 * yet. Otherwise we look it up. We cache the result in the lock object
731 * itself, so actual lookup of the hash should be once per lock object.
733 static inline struct lock_class *
734 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
736 struct lockdep_subclass_key *key;
737 struct list_head *hash_head;
738 struct lock_class *class;
741 class = look_up_lock_class(lock, subclass);
746 * Debug-check: all keys must be persistent!
748 if (!static_obj(lock->key)) {
750 printk("INFO: trying to register non-static key.\n");
751 printk("the code is fine but needs lockdep annotation.\n");
752 printk("turning off the locking correctness validator.\n");
758 key = lock->key->subkeys + subclass;
759 hash_head = classhashentry(key);
761 raw_local_irq_save(flags);
763 raw_local_irq_restore(flags);
767 * We have to do the hash-walk again, to avoid races
770 list_for_each_entry(class, hash_head, hash_entry)
771 if (class->key == key)
774 * Allocate a new key from the static array, and add it to
777 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
778 if (!debug_locks_off_graph_unlock()) {
779 raw_local_irq_restore(flags);
782 raw_local_irq_restore(flags);
784 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
785 printk("turning off the locking correctness validator.\n");
788 class = lock_classes + nr_lock_classes++;
789 debug_atomic_inc(&nr_unused_locks);
791 class->name = lock->name;
792 class->subclass = subclass;
793 INIT_LIST_HEAD(&class->lock_entry);
794 INIT_LIST_HEAD(&class->locks_before);
795 INIT_LIST_HEAD(&class->locks_after);
796 class->name_version = count_matching_names(class);
798 * We use RCU's safe list-add method to make
799 * parallel walking of the hash-list safe:
801 list_add_tail_rcu(&class->hash_entry, hash_head);
803 * Add it to the global list of classes:
805 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
807 if (verbose(class)) {
809 raw_local_irq_restore(flags);
811 printk("\nnew class %p: %s", class->key, class->name);
812 if (class->name_version > 1)
813 printk("#%d", class->name_version);
817 raw_local_irq_save(flags);
819 raw_local_irq_restore(flags);
825 raw_local_irq_restore(flags);
827 if (!subclass || force)
828 lock->class_cache = class;
830 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
836 #ifdef CONFIG_PROVE_LOCKING
838 * Allocate a lockdep entry. (assumes the graph_lock held, returns
839 * with NULL on failure)
841 static struct lock_list *alloc_list_entry(void)
843 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
844 if (!debug_locks_off_graph_unlock())
847 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
848 printk("turning off the locking correctness validator.\n");
851 return list_entries + nr_list_entries++;
855 * Add a new dependency to the head of the list:
857 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
858 struct list_head *head, unsigned long ip, int distance)
860 struct lock_list *entry;
862 * Lock not present yet - get a new dependency struct and
863 * add it to the list:
865 entry = alloc_list_entry();
870 entry->distance = distance;
871 if (!save_trace(&entry->trace))
875 * Since we never remove from the dependency list, the list can
876 * be walked lockless by other CPUs, it's only allocation
877 * that must be protected by the spinlock. But this also means
878 * we must make new entries visible only once writes to the
879 * entry become visible - hence the RCU op:
881 list_add_tail_rcu(&entry->entry, head);
887 * Recursive, forwards-direction lock-dependency checking, used for
888 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
891 * (to keep the stackframe of the recursive functions small we
892 * use these global variables, and we also mark various helper
893 * functions as noinline.)
895 static struct held_lock *check_source, *check_target;
898 * Print a dependency chain entry (this is only done when a deadlock
899 * has been detected):
902 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
904 if (debug_locks_silent)
906 printk("\n-> #%u", depth);
907 print_lock_name(target->class);
909 print_stack_trace(&target->trace, 6);
915 * When a circular dependency is detected, print the
919 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
921 struct task_struct *curr = current;
923 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
926 printk("\n=======================================================\n");
927 printk( "[ INFO: possible circular locking dependency detected ]\n");
928 print_kernel_version();
929 printk( "-------------------------------------------------------\n");
930 printk("%s/%d is trying to acquire lock:\n",
931 curr->comm, task_pid_nr(curr));
932 print_lock(check_source);
933 printk("\nbut task is already holding lock:\n");
934 print_lock(check_target);
935 printk("\nwhich lock already depends on the new lock.\n\n");
936 printk("\nthe existing dependency chain (in reverse order) is:\n");
938 print_circular_bug_entry(entry, depth);
943 static noinline int print_circular_bug_tail(void)
945 struct task_struct *curr = current;
946 struct lock_list this;
948 if (debug_locks_silent)
951 this.class = check_source->class;
952 if (!save_trace(&this.trace))
955 print_circular_bug_entry(&this, 0);
957 printk("\nother info that might help us debug this:\n\n");
958 lockdep_print_held_locks(curr);
960 printk("\nstack backtrace:\n");
966 #define RECURSION_LIMIT 40
968 static int noinline print_infinite_recursion_bug(void)
970 if (!debug_locks_off_graph_unlock())
978 unsigned long __lockdep_count_forward_deps(struct lock_class *class,
981 struct lock_list *entry;
982 unsigned long ret = 1;
984 if (lockdep_dependency_visit(class, depth))
988 * Recurse this class's dependency list:
990 list_for_each_entry(entry, &class->locks_after, entry)
991 ret += __lockdep_count_forward_deps(entry->class, depth + 1);
996 unsigned long lockdep_count_forward_deps(struct lock_class *class)
998 unsigned long ret, flags;
1000 local_irq_save(flags);
1001 __raw_spin_lock(&lockdep_lock);
1002 ret = __lockdep_count_forward_deps(class, 0);
1003 __raw_spin_unlock(&lockdep_lock);
1004 local_irq_restore(flags);
1009 unsigned long __lockdep_count_backward_deps(struct lock_class *class,
1012 struct lock_list *entry;
1013 unsigned long ret = 1;
1015 if (lockdep_dependency_visit(class, depth))
1018 * Recurse this class's dependency list:
1020 list_for_each_entry(entry, &class->locks_before, entry)
1021 ret += __lockdep_count_backward_deps(entry->class, depth + 1);
1026 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1028 unsigned long ret, flags;
1030 local_irq_save(flags);
1031 __raw_spin_lock(&lockdep_lock);
1032 ret = __lockdep_count_backward_deps(class, 0);
1033 __raw_spin_unlock(&lockdep_lock);
1034 local_irq_restore(flags);
1040 * Prove that the dependency graph starting at <entry> can not
1041 * lead to <target>. Print an error and return 0 if it does.
1044 check_noncircular(struct lock_class *source, unsigned int depth)
1046 struct lock_list *entry;
1048 if (lockdep_dependency_visit(source, depth))
1051 debug_atomic_inc(&nr_cyclic_check_recursions);
1052 if (depth > max_recursion_depth)
1053 max_recursion_depth = depth;
1054 if (depth >= RECURSION_LIMIT)
1055 return print_infinite_recursion_bug();
1057 * Check this lock's dependency list:
1059 list_for_each_entry(entry, &source->locks_after, entry) {
1060 if (entry->class == check_target->class)
1061 return print_circular_bug_header(entry, depth+1);
1062 debug_atomic_inc(&nr_cyclic_checks);
1063 if (!check_noncircular(entry->class, depth+1))
1064 return print_circular_bug_entry(entry, depth+1);
1069 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1071 * Forwards and backwards subgraph searching, for the purposes of
1072 * proving that two subgraphs can be connected by a new dependency
1073 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1075 static enum lock_usage_bit find_usage_bit;
1076 static struct lock_class *forwards_match, *backwards_match;
1079 * Find a node in the forwards-direction dependency sub-graph starting
1080 * at <source> that matches <find_usage_bit>.
1082 * Return 2 if such a node exists in the subgraph, and put that node
1083 * into <forwards_match>.
1085 * Return 1 otherwise and keep <forwards_match> unchanged.
1086 * Return 0 on error.
1089 find_usage_forwards(struct lock_class *source, unsigned int depth)
1091 struct lock_list *entry;
1094 if (lockdep_dependency_visit(source, depth))
1097 if (depth > max_recursion_depth)
1098 max_recursion_depth = depth;
1099 if (depth >= RECURSION_LIMIT)
1100 return print_infinite_recursion_bug();
1102 debug_atomic_inc(&nr_find_usage_forwards_checks);
1103 if (source->usage_mask & (1 << find_usage_bit)) {
1104 forwards_match = source;
1109 * Check this lock's dependency list:
1111 list_for_each_entry(entry, &source->locks_after, entry) {
1112 debug_atomic_inc(&nr_find_usage_forwards_recursions);
1113 ret = find_usage_forwards(entry->class, depth+1);
1114 if (ret == 2 || ret == 0)
1121 * Find a node in the backwards-direction dependency sub-graph starting
1122 * at <source> that matches <find_usage_bit>.
1124 * Return 2 if such a node exists in the subgraph, and put that node
1125 * into <backwards_match>.
1127 * Return 1 otherwise and keep <backwards_match> unchanged.
1128 * Return 0 on error.
1131 find_usage_backwards(struct lock_class *source, unsigned int depth)
1133 struct lock_list *entry;
1136 if (lockdep_dependency_visit(source, depth))
1139 if (!__raw_spin_is_locked(&lockdep_lock))
1140 return DEBUG_LOCKS_WARN_ON(1);
1142 if (depth > max_recursion_depth)
1143 max_recursion_depth = depth;
1144 if (depth >= RECURSION_LIMIT)
1145 return print_infinite_recursion_bug();
1147 debug_atomic_inc(&nr_find_usage_backwards_checks);
1148 if (source->usage_mask & (1 << find_usage_bit)) {
1149 backwards_match = source;
1154 * Check this lock's dependency list:
1156 list_for_each_entry(entry, &source->locks_before, entry) {
1157 debug_atomic_inc(&nr_find_usage_backwards_recursions);
1158 ret = find_usage_backwards(entry->class, depth+1);
1159 if (ret == 2 || ret == 0)
1166 print_bad_irq_dependency(struct task_struct *curr,
1167 struct held_lock *prev,
1168 struct held_lock *next,
1169 enum lock_usage_bit bit1,
1170 enum lock_usage_bit bit2,
1171 const char *irqclass)
1173 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1176 printk("\n======================================================\n");
1177 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1178 irqclass, irqclass);
1179 print_kernel_version();
1180 printk( "------------------------------------------------------\n");
1181 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1182 curr->comm, task_pid_nr(curr),
1183 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1184 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1185 curr->hardirqs_enabled,
1186 curr->softirqs_enabled);
1189 printk("\nand this task is already holding:\n");
1191 printk("which would create a new lock dependency:\n");
1192 print_lock_name(prev->class);
1194 print_lock_name(next->class);
1197 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1199 print_lock_name(backwards_match);
1200 printk("\n... which became %s-irq-safe at:\n", irqclass);
1202 print_stack_trace(backwards_match->usage_traces + bit1, 1);
1204 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1205 print_lock_name(forwards_match);
1206 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1209 print_stack_trace(forwards_match->usage_traces + bit2, 1);
1211 printk("\nother info that might help us debug this:\n\n");
1212 lockdep_print_held_locks(curr);
1214 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1215 print_lock_dependencies(backwards_match, 0);
1217 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1218 print_lock_dependencies(forwards_match, 0);
1220 printk("\nstack backtrace:\n");
1227 check_usage(struct task_struct *curr, struct held_lock *prev,
1228 struct held_lock *next, enum lock_usage_bit bit_backwards,
1229 enum lock_usage_bit bit_forwards, const char *irqclass)
1233 find_usage_bit = bit_backwards;
1234 /* fills in <backwards_match> */
1235 ret = find_usage_backwards(prev->class, 0);
1236 if (!ret || ret == 1)
1239 find_usage_bit = bit_forwards;
1240 ret = find_usage_forwards(next->class, 0);
1241 if (!ret || ret == 1)
1244 return print_bad_irq_dependency(curr, prev, next,
1245 bit_backwards, bit_forwards, irqclass);
1249 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1250 struct held_lock *next)
1253 * Prove that the new dependency does not connect a hardirq-safe
1254 * lock with a hardirq-unsafe lock - to achieve this we search
1255 * the backwards-subgraph starting at <prev>, and the
1256 * forwards-subgraph starting at <next>:
1258 if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
1259 LOCK_ENABLED_HARDIRQS, "hard"))
1263 * Prove that the new dependency does not connect a hardirq-safe-read
1264 * lock with a hardirq-unsafe lock - to achieve this we search
1265 * the backwards-subgraph starting at <prev>, and the
1266 * forwards-subgraph starting at <next>:
1268 if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
1269 LOCK_ENABLED_HARDIRQS, "hard-read"))
1273 * Prove that the new dependency does not connect a softirq-safe
1274 * lock with a softirq-unsafe lock - to achieve this we search
1275 * the backwards-subgraph starting at <prev>, and the
1276 * forwards-subgraph starting at <next>:
1278 if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
1279 LOCK_ENABLED_SOFTIRQS, "soft"))
1282 * Prove that the new dependency does not connect a softirq-safe-read
1283 * lock with a softirq-unsafe lock - to achieve this we search
1284 * the backwards-subgraph starting at <prev>, and the
1285 * forwards-subgraph starting at <next>:
1287 if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
1288 LOCK_ENABLED_SOFTIRQS, "soft"))
1294 static void inc_chains(void)
1296 if (current->hardirq_context)
1297 nr_hardirq_chains++;
1299 if (current->softirq_context)
1300 nr_softirq_chains++;
1302 nr_process_chains++;
1309 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1310 struct held_lock *next)
1315 static inline void inc_chains(void)
1317 nr_process_chains++;
1323 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1324 struct held_lock *next)
1326 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1329 printk("\n=============================================\n");
1330 printk( "[ INFO: possible recursive locking detected ]\n");
1331 print_kernel_version();
1332 printk( "---------------------------------------------\n");
1333 printk("%s/%d is trying to acquire lock:\n",
1334 curr->comm, task_pid_nr(curr));
1336 printk("\nbut task is already holding lock:\n");
1339 printk("\nother info that might help us debug this:\n");
1340 lockdep_print_held_locks(curr);
1342 printk("\nstack backtrace:\n");
1349 * Check whether we are holding such a class already.
1351 * (Note that this has to be done separately, because the graph cannot
1352 * detect such classes of deadlocks.)
1354 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1357 check_deadlock(struct task_struct *curr, struct held_lock *next,
1358 struct lockdep_map *next_instance, int read)
1360 struct held_lock *prev;
1363 for (i = 0; i < curr->lockdep_depth; i++) {
1364 prev = curr->held_locks + i;
1365 if (prev->class != next->class)
1368 * Allow read-after-read recursion of the same
1369 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1371 if ((read == 2) && prev->read)
1373 return print_deadlock_bug(curr, prev, next);
1379 * There was a chain-cache miss, and we are about to add a new dependency
1380 * to a previous lock. We recursively validate the following rules:
1382 * - would the adding of the <prev> -> <next> dependency create a
1383 * circular dependency in the graph? [== circular deadlock]
1385 * - does the new prev->next dependency connect any hardirq-safe lock
1386 * (in the full backwards-subgraph starting at <prev>) with any
1387 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1388 * <next>)? [== illegal lock inversion with hardirq contexts]
1390 * - does the new prev->next dependency connect any softirq-safe lock
1391 * (in the full backwards-subgraph starting at <prev>) with any
1392 * softirq-unsafe lock (in the full forwards-subgraph starting at
1393 * <next>)? [== illegal lock inversion with softirq contexts]
1395 * any of these scenarios could lead to a deadlock.
1397 * Then if all the validations pass, we add the forwards and backwards
1401 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1402 struct held_lock *next, int distance)
1404 struct lock_list *entry;
1408 * Prove that the new <prev> -> <next> dependency would not
1409 * create a circular dependency in the graph. (We do this by
1410 * forward-recursing into the graph starting at <next>, and
1411 * checking whether we can reach <prev>.)
1413 * We are using global variables to control the recursion, to
1414 * keep the stackframe size of the recursive functions low:
1416 check_source = next;
1417 check_target = prev;
1418 if (!(check_noncircular(next->class, 0)))
1419 return print_circular_bug_tail();
1421 if (!check_prev_add_irq(curr, prev, next))
1425 * For recursive read-locks we do all the dependency checks,
1426 * but we dont store read-triggered dependencies (only
1427 * write-triggered dependencies). This ensures that only the
1428 * write-side dependencies matter, and that if for example a
1429 * write-lock never takes any other locks, then the reads are
1430 * equivalent to a NOP.
1432 if (next->read == 2 || prev->read == 2)
1435 * Is the <prev> -> <next> dependency already present?
1437 * (this may occur even though this is a new chain: consider
1438 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1439 * chains - the second one will be new, but L1 already has
1440 * L2 added to its dependency list, due to the first chain.)
1442 list_for_each_entry(entry, &prev->class->locks_after, entry) {
1443 if (entry->class == next->class) {
1445 entry->distance = 1;
1451 * Ok, all validations passed, add the new lock
1452 * to the previous lock's dependency list:
1454 ret = add_lock_to_list(prev->class, next->class,
1455 &prev->class->locks_after, next->acquire_ip, distance);
1460 ret = add_lock_to_list(next->class, prev->class,
1461 &next->class->locks_before, next->acquire_ip, distance);
1466 * Debugging printouts:
1468 if (verbose(prev->class) || verbose(next->class)) {
1470 printk("\n new dependency: ");
1471 print_lock_name(prev->class);
1473 print_lock_name(next->class);
1476 return graph_lock();
1482 * Add the dependency to all directly-previous locks that are 'relevant'.
1483 * The ones that are relevant are (in increasing distance from curr):
1484 * all consecutive trylock entries and the final non-trylock entry - or
1485 * the end of this context's lock-chain - whichever comes first.
1488 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1490 int depth = curr->lockdep_depth;
1491 struct held_lock *hlock;
1496 * Depth must not be zero for a non-head lock:
1501 * At least two relevant locks must exist for this
1504 if (curr->held_locks[depth].irq_context !=
1505 curr->held_locks[depth-1].irq_context)
1509 int distance = curr->lockdep_depth - depth + 1;
1510 hlock = curr->held_locks + depth-1;
1512 * Only non-recursive-read entries get new dependencies
1515 if (hlock->read != 2) {
1516 if (!check_prev_add(curr, hlock, next, distance))
1519 * Stop after the first non-trylock entry,
1520 * as non-trylock entries have added their
1521 * own direct dependencies already, so this
1522 * lock is connected to them indirectly:
1524 if (!hlock->trylock)
1529 * End of lock-stack?
1534 * Stop the search if we cross into another context:
1536 if (curr->held_locks[depth].irq_context !=
1537 curr->held_locks[depth-1].irq_context)
1542 if (!debug_locks_off_graph_unlock())
1550 unsigned long nr_lock_chains;
1551 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1552 int nr_chain_hlocks;
1553 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1555 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1557 return lock_classes + chain_hlocks[chain->base + i];
1561 * Look up a dependency chain. If the key is not present yet then
1562 * add it and return 1 - in this case the new dependency chain is
1563 * validated. If the key is already hashed, return 0.
1564 * (On return with 1 graph_lock is held.)
1566 static inline int lookup_chain_cache(struct task_struct *curr,
1567 struct held_lock *hlock,
1570 struct lock_class *class = hlock->class;
1571 struct list_head *hash_head = chainhashentry(chain_key);
1572 struct lock_chain *chain;
1573 struct held_lock *hlock_curr, *hlock_next;
1576 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1579 * We can walk it lock-free, because entries only get added
1582 list_for_each_entry(chain, hash_head, entry) {
1583 if (chain->chain_key == chain_key) {
1585 debug_atomic_inc(&chain_lookup_hits);
1586 if (very_verbose(class))
1587 printk("\nhash chain already cached, key: "
1588 "%016Lx tail class: [%p] %s\n",
1589 (unsigned long long)chain_key,
1590 class->key, class->name);
1594 if (very_verbose(class))
1595 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1596 (unsigned long long)chain_key, class->key, class->name);
1598 * Allocate a new chain entry from the static array, and add
1604 * We have to walk the chain again locked - to avoid duplicates:
1606 list_for_each_entry(chain, hash_head, entry) {
1607 if (chain->chain_key == chain_key) {
1612 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1613 if (!debug_locks_off_graph_unlock())
1616 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1617 printk("turning off the locking correctness validator.\n");
1620 chain = lock_chains + nr_lock_chains++;
1621 chain->chain_key = chain_key;
1622 chain->irq_context = hlock->irq_context;
1623 /* Find the first held_lock of current chain */
1625 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1626 hlock_curr = curr->held_locks + i;
1627 if (hlock_curr->irq_context != hlock_next->irq_context)
1632 chain->depth = curr->lockdep_depth + 1 - i;
1633 cn = nr_chain_hlocks;
1634 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1635 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1640 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1642 for (j = 0; j < chain->depth - 1; j++, i++) {
1643 int lock_id = curr->held_locks[i].class - lock_classes;
1644 chain_hlocks[chain->base + j] = lock_id;
1646 chain_hlocks[chain->base + j] = class - lock_classes;
1648 list_add_tail_rcu(&chain->entry, hash_head);
1649 debug_atomic_inc(&chain_lookup_misses);
1655 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1656 struct held_lock *hlock, int chain_head, u64 chain_key)
1659 * Trylock needs to maintain the stack of held locks, but it
1660 * does not add new dependencies, because trylock can be done
1663 * We look up the chain_key and do the O(N^2) check and update of
1664 * the dependencies only if this is a new dependency chain.
1665 * (If lookup_chain_cache() returns with 1 it acquires
1666 * graph_lock for us)
1668 if (!hlock->trylock && (hlock->check == 2) &&
1669 lookup_chain_cache(curr, hlock, chain_key)) {
1671 * Check whether last held lock:
1673 * - is irq-safe, if this lock is irq-unsafe
1674 * - is softirq-safe, if this lock is hardirq-unsafe
1676 * And check whether the new lock's dependency graph
1677 * could lead back to the previous lock.
1679 * any of these scenarios could lead to a deadlock. If
1682 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1687 * Mark recursive read, as we jump over it when
1688 * building dependencies (just like we jump over
1694 * Add dependency only if this lock is not the head
1695 * of the chain, and if it's not a secondary read-lock:
1697 if (!chain_head && ret != 2)
1698 if (!check_prevs_add(curr, hlock))
1702 /* after lookup_chain_cache(): */
1703 if (unlikely(!debug_locks))
1709 static inline int validate_chain(struct task_struct *curr,
1710 struct lockdep_map *lock, struct held_lock *hlock,
1711 int chain_head, u64 chain_key)
1718 * We are building curr_chain_key incrementally, so double-check
1719 * it from scratch, to make sure that it's done correctly:
1721 static void check_chain_key(struct task_struct *curr)
1723 #ifdef CONFIG_DEBUG_LOCKDEP
1724 struct held_lock *hlock, *prev_hlock = NULL;
1728 for (i = 0; i < curr->lockdep_depth; i++) {
1729 hlock = curr->held_locks + i;
1730 if (chain_key != hlock->prev_chain_key) {
1732 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1733 curr->lockdep_depth, i,
1734 (unsigned long long)chain_key,
1735 (unsigned long long)hlock->prev_chain_key);
1739 id = hlock->class - lock_classes;
1740 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1743 if (prev_hlock && (prev_hlock->irq_context !=
1744 hlock->irq_context))
1746 chain_key = iterate_chain_key(chain_key, id);
1749 if (chain_key != curr->curr_chain_key) {
1751 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1752 curr->lockdep_depth, i,
1753 (unsigned long long)chain_key,
1754 (unsigned long long)curr->curr_chain_key);
1761 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1762 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1764 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1767 printk("\n=================================\n");
1768 printk( "[ INFO: inconsistent lock state ]\n");
1769 print_kernel_version();
1770 printk( "---------------------------------\n");
1772 printk("inconsistent {%s} -> {%s} usage.\n",
1773 usage_str[prev_bit], usage_str[new_bit]);
1775 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1776 curr->comm, task_pid_nr(curr),
1777 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1778 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1779 trace_hardirqs_enabled(curr),
1780 trace_softirqs_enabled(curr));
1783 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1784 print_stack_trace(this->class->usage_traces + prev_bit, 1);
1786 print_irqtrace_events(curr);
1787 printk("\nother info that might help us debug this:\n");
1788 lockdep_print_held_locks(curr);
1790 printk("\nstack backtrace:\n");
1797 * Print out an error if an invalid bit is set:
1800 valid_state(struct task_struct *curr, struct held_lock *this,
1801 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1803 if (unlikely(this->class->usage_mask & (1 << bad_bit)))
1804 return print_usage_bug(curr, this, bad_bit, new_bit);
1808 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1809 enum lock_usage_bit new_bit);
1811 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1814 * print irq inversion bug:
1817 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1818 struct held_lock *this, int forwards,
1819 const char *irqclass)
1821 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1824 printk("\n=========================================================\n");
1825 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1826 print_kernel_version();
1827 printk( "---------------------------------------------------------\n");
1828 printk("%s/%d just changed the state of lock:\n",
1829 curr->comm, task_pid_nr(curr));
1832 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1834 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1835 print_lock_name(other);
1836 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1838 printk("\nother info that might help us debug this:\n");
1839 lockdep_print_held_locks(curr);
1841 printk("\nthe first lock's dependencies:\n");
1842 print_lock_dependencies(this->class, 0);
1844 printk("\nthe second lock's dependencies:\n");
1845 print_lock_dependencies(other, 0);
1847 printk("\nstack backtrace:\n");
1854 * Prove that in the forwards-direction subgraph starting at <this>
1855 * there is no lock matching <mask>:
1858 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1859 enum lock_usage_bit bit, const char *irqclass)
1863 find_usage_bit = bit;
1864 /* fills in <forwards_match> */
1865 ret = find_usage_forwards(this->class, 0);
1866 if (!ret || ret == 1)
1869 return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1873 * Prove that in the backwards-direction subgraph starting at <this>
1874 * there is no lock matching <mask>:
1877 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1878 enum lock_usage_bit bit, const char *irqclass)
1882 find_usage_bit = bit;
1883 /* fills in <backwards_match> */
1884 ret = find_usage_backwards(this->class, 0);
1885 if (!ret || ret == 1)
1888 return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1891 void print_irqtrace_events(struct task_struct *curr)
1893 printk("irq event stamp: %u\n", curr->irq_events);
1894 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
1895 print_ip_sym(curr->hardirq_enable_ip);
1896 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1897 print_ip_sym(curr->hardirq_disable_ip);
1898 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
1899 print_ip_sym(curr->softirq_enable_ip);
1900 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1901 print_ip_sym(curr->softirq_disable_ip);
1904 static int hardirq_verbose(struct lock_class *class)
1907 return class_filter(class);
1912 static int softirq_verbose(struct lock_class *class)
1915 return class_filter(class);
1920 #define STRICT_READ_CHECKS 1
1922 static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
1923 enum lock_usage_bit new_bit)
1928 case LOCK_USED_IN_HARDIRQ:
1929 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1931 if (!valid_state(curr, this, new_bit,
1932 LOCK_ENABLED_HARDIRQS_READ))
1935 * just marked it hardirq-safe, check that this lock
1936 * took no hardirq-unsafe lock in the past:
1938 if (!check_usage_forwards(curr, this,
1939 LOCK_ENABLED_HARDIRQS, "hard"))
1941 #if STRICT_READ_CHECKS
1943 * just marked it hardirq-safe, check that this lock
1944 * took no hardirq-unsafe-read lock in the past:
1946 if (!check_usage_forwards(curr, this,
1947 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1950 if (hardirq_verbose(this->class))
1953 case LOCK_USED_IN_SOFTIRQ:
1954 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1956 if (!valid_state(curr, this, new_bit,
1957 LOCK_ENABLED_SOFTIRQS_READ))
1960 * just marked it softirq-safe, check that this lock
1961 * took no softirq-unsafe lock in the past:
1963 if (!check_usage_forwards(curr, this,
1964 LOCK_ENABLED_SOFTIRQS, "soft"))
1966 #if STRICT_READ_CHECKS
1968 * just marked it softirq-safe, check that this lock
1969 * took no softirq-unsafe-read lock in the past:
1971 if (!check_usage_forwards(curr, this,
1972 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
1975 if (softirq_verbose(this->class))
1978 case LOCK_USED_IN_HARDIRQ_READ:
1979 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1982 * just marked it hardirq-read-safe, check that this lock
1983 * took no hardirq-unsafe lock in the past:
1985 if (!check_usage_forwards(curr, this,
1986 LOCK_ENABLED_HARDIRQS, "hard"))
1988 if (hardirq_verbose(this->class))
1991 case LOCK_USED_IN_SOFTIRQ_READ:
1992 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1995 * just marked it softirq-read-safe, check that this lock
1996 * took no softirq-unsafe lock in the past:
1998 if (!check_usage_forwards(curr, this,
1999 LOCK_ENABLED_SOFTIRQS, "soft"))
2001 if (softirq_verbose(this->class))
2004 case LOCK_ENABLED_HARDIRQS:
2005 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
2007 if (!valid_state(curr, this, new_bit,
2008 LOCK_USED_IN_HARDIRQ_READ))
2011 * just marked it hardirq-unsafe, check that no hardirq-safe
2012 * lock in the system ever took it in the past:
2014 if (!check_usage_backwards(curr, this,
2015 LOCK_USED_IN_HARDIRQ, "hard"))
2017 #if STRICT_READ_CHECKS
2019 * just marked it hardirq-unsafe, check that no
2020 * hardirq-safe-read lock in the system ever took
2023 if (!check_usage_backwards(curr, this,
2024 LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
2027 if (hardirq_verbose(this->class))
2030 case LOCK_ENABLED_SOFTIRQS:
2031 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
2033 if (!valid_state(curr, this, new_bit,
2034 LOCK_USED_IN_SOFTIRQ_READ))
2037 * just marked it softirq-unsafe, check that no softirq-safe
2038 * lock in the system ever took it in the past:
2040 if (!check_usage_backwards(curr, this,
2041 LOCK_USED_IN_SOFTIRQ, "soft"))
2043 #if STRICT_READ_CHECKS
2045 * just marked it softirq-unsafe, check that no
2046 * softirq-safe-read lock in the system ever took
2049 if (!check_usage_backwards(curr, this,
2050 LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
2053 if (softirq_verbose(this->class))
2056 case LOCK_ENABLED_HARDIRQS_READ:
2057 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
2059 #if STRICT_READ_CHECKS
2061 * just marked it hardirq-read-unsafe, check that no
2062 * hardirq-safe lock in the system ever took it in the past:
2064 if (!check_usage_backwards(curr, this,
2065 LOCK_USED_IN_HARDIRQ, "hard"))
2068 if (hardirq_verbose(this->class))
2071 case LOCK_ENABLED_SOFTIRQS_READ:
2072 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
2074 #if STRICT_READ_CHECKS
2076 * just marked it softirq-read-unsafe, check that no
2077 * softirq-safe lock in the system ever took it in the past:
2079 if (!check_usage_backwards(curr, this,
2080 LOCK_USED_IN_SOFTIRQ, "soft"))
2083 if (softirq_verbose(this->class))
2095 * Mark all held locks with a usage bit:
2098 mark_held_locks(struct task_struct *curr, int hardirq)
2100 enum lock_usage_bit usage_bit;
2101 struct held_lock *hlock;
2104 for (i = 0; i < curr->lockdep_depth; i++) {
2105 hlock = curr->held_locks + i;
2109 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
2111 usage_bit = LOCK_ENABLED_HARDIRQS;
2114 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
2116 usage_bit = LOCK_ENABLED_SOFTIRQS;
2118 if (!mark_lock(curr, hlock, usage_bit))
2126 * Debugging helper: via this flag we know that we are in
2127 * 'early bootup code', and will warn about any invalid irqs-on event:
2129 static int early_boot_irqs_enabled;
2131 void early_boot_irqs_off(void)
2133 early_boot_irqs_enabled = 0;
2136 void early_boot_irqs_on(void)
2138 early_boot_irqs_enabled = 1;
2142 * Hardirqs will be enabled:
2144 void trace_hardirqs_on_caller(unsigned long a0)
2146 struct task_struct *curr = current;
2149 time_hardirqs_on(CALLER_ADDR0, a0);
2151 if (unlikely(!debug_locks || current->lockdep_recursion))
2154 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2157 if (unlikely(curr->hardirqs_enabled)) {
2158 debug_atomic_inc(&redundant_hardirqs_on);
2161 /* we'll do an OFF -> ON transition: */
2162 curr->hardirqs_enabled = 1;
2163 ip = (unsigned long) __builtin_return_address(0);
2165 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2167 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2170 * We are going to turn hardirqs on, so set the
2171 * usage bit for all held locks:
2173 if (!mark_held_locks(curr, 1))
2176 * If we have softirqs enabled, then set the usage
2177 * bit for all held locks. (disabled hardirqs prevented
2178 * this bit from being set before)
2180 if (curr->softirqs_enabled)
2181 if (!mark_held_locks(curr, 0))
2184 curr->hardirq_enable_ip = ip;
2185 curr->hardirq_enable_event = ++curr->irq_events;
2186 debug_atomic_inc(&hardirqs_on_events);
2188 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2190 void trace_hardirqs_on(void)
2192 trace_hardirqs_on_caller(CALLER_ADDR0);
2194 EXPORT_SYMBOL(trace_hardirqs_on);
2197 * Hardirqs were disabled:
2199 void trace_hardirqs_off_caller(unsigned long a0)
2201 struct task_struct *curr = current;
2203 time_hardirqs_off(CALLER_ADDR0, a0);
2205 if (unlikely(!debug_locks || current->lockdep_recursion))
2208 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2211 if (curr->hardirqs_enabled) {
2213 * We have done an ON -> OFF transition:
2215 curr->hardirqs_enabled = 0;
2216 curr->hardirq_disable_ip = _RET_IP_;
2217 curr->hardirq_disable_event = ++curr->irq_events;
2218 debug_atomic_inc(&hardirqs_off_events);
2220 debug_atomic_inc(&redundant_hardirqs_off);
2222 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2224 void trace_hardirqs_off(void)
2226 trace_hardirqs_off_caller(CALLER_ADDR0);
2228 EXPORT_SYMBOL(trace_hardirqs_off);
2231 * Softirqs will be enabled:
2233 void trace_softirqs_on(unsigned long ip)
2235 struct task_struct *curr = current;
2237 if (unlikely(!debug_locks))
2240 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2243 if (curr->softirqs_enabled) {
2244 debug_atomic_inc(&redundant_softirqs_on);
2249 * We'll do an OFF -> ON transition:
2251 curr->softirqs_enabled = 1;
2252 curr->softirq_enable_ip = ip;
2253 curr->softirq_enable_event = ++curr->irq_events;
2254 debug_atomic_inc(&softirqs_on_events);
2256 * We are going to turn softirqs on, so set the
2257 * usage bit for all held locks, if hardirqs are
2260 if (curr->hardirqs_enabled)
2261 mark_held_locks(curr, 0);
2265 * Softirqs were disabled:
2267 void trace_softirqs_off(unsigned long ip)
2269 struct task_struct *curr = current;
2271 if (unlikely(!debug_locks))
2274 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2277 if (curr->softirqs_enabled) {
2279 * We have done an ON -> OFF transition:
2281 curr->softirqs_enabled = 0;
2282 curr->softirq_disable_ip = ip;
2283 curr->softirq_disable_event = ++curr->irq_events;
2284 debug_atomic_inc(&softirqs_off_events);
2285 DEBUG_LOCKS_WARN_ON(!softirq_count());
2287 debug_atomic_inc(&redundant_softirqs_off);
2290 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2293 * If non-trylock use in a hardirq or softirq context, then
2294 * mark the lock as used in these contexts:
2296 if (!hlock->trylock) {
2298 if (curr->hardirq_context)
2299 if (!mark_lock(curr, hlock,
2300 LOCK_USED_IN_HARDIRQ_READ))
2302 if (curr->softirq_context)
2303 if (!mark_lock(curr, hlock,
2304 LOCK_USED_IN_SOFTIRQ_READ))
2307 if (curr->hardirq_context)
2308 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2310 if (curr->softirq_context)
2311 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2315 if (!hlock->hardirqs_off) {
2317 if (!mark_lock(curr, hlock,
2318 LOCK_ENABLED_HARDIRQS_READ))
2320 if (curr->softirqs_enabled)
2321 if (!mark_lock(curr, hlock,
2322 LOCK_ENABLED_SOFTIRQS_READ))
2325 if (!mark_lock(curr, hlock,
2326 LOCK_ENABLED_HARDIRQS))
2328 if (curr->softirqs_enabled)
2329 if (!mark_lock(curr, hlock,
2330 LOCK_ENABLED_SOFTIRQS))
2338 static int separate_irq_context(struct task_struct *curr,
2339 struct held_lock *hlock)
2341 unsigned int depth = curr->lockdep_depth;
2344 * Keep track of points where we cross into an interrupt context:
2346 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2347 curr->softirq_context;
2349 struct held_lock *prev_hlock;
2351 prev_hlock = curr->held_locks + depth-1;
2353 * If we cross into another context, reset the
2354 * hash key (this also prevents the checking and the
2355 * adding of the dependency to 'prev'):
2357 if (prev_hlock->irq_context != hlock->irq_context)
2366 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2367 enum lock_usage_bit new_bit)
2373 static inline int mark_irqflags(struct task_struct *curr,
2374 struct held_lock *hlock)
2379 static inline int separate_irq_context(struct task_struct *curr,
2380 struct held_lock *hlock)
2388 * Mark a lock with a usage bit, and validate the state transition:
2390 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2391 enum lock_usage_bit new_bit)
2393 unsigned int new_mask = 1 << new_bit, ret = 1;
2396 * If already set then do not dirty the cacheline,
2397 * nor do any checks:
2399 if (likely(this->class->usage_mask & new_mask))
2405 * Make sure we didnt race:
2407 if (unlikely(this->class->usage_mask & new_mask)) {
2412 this->class->usage_mask |= new_mask;
2414 if (!save_trace(this->class->usage_traces + new_bit))
2418 case LOCK_USED_IN_HARDIRQ:
2419 case LOCK_USED_IN_SOFTIRQ:
2420 case LOCK_USED_IN_HARDIRQ_READ:
2421 case LOCK_USED_IN_SOFTIRQ_READ:
2422 case LOCK_ENABLED_HARDIRQS:
2423 case LOCK_ENABLED_SOFTIRQS:
2424 case LOCK_ENABLED_HARDIRQS_READ:
2425 case LOCK_ENABLED_SOFTIRQS_READ:
2426 ret = mark_lock_irq(curr, this, new_bit);
2431 debug_atomic_dec(&nr_unused_locks);
2434 if (!debug_locks_off_graph_unlock())
2443 * We must printk outside of the graph_lock:
2446 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2448 print_irqtrace_events(curr);
2456 * Initialize a lock instance's lock-class mapping info:
2458 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2459 struct lock_class_key *key, int subclass)
2461 if (unlikely(!debug_locks))
2464 if (DEBUG_LOCKS_WARN_ON(!key))
2466 if (DEBUG_LOCKS_WARN_ON(!name))
2469 * Sanity check, the lock-class key must be persistent:
2471 if (!static_obj(key)) {
2472 printk("BUG: key %p not in .data!\n", key);
2473 DEBUG_LOCKS_WARN_ON(1);
2478 lock->class_cache = NULL;
2479 #ifdef CONFIG_LOCK_STAT
2480 lock->cpu = raw_smp_processor_id();
2483 register_lock_class(lock, subclass, 1);
2486 EXPORT_SYMBOL_GPL(lockdep_init_map);
2489 * This gets called for every mutex_lock*()/spin_lock*() operation.
2490 * We maintain the dependency maps and validate the locking attempt:
2492 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2493 int trylock, int read, int check, int hardirqs_off,
2496 struct task_struct *curr = current;
2497 struct lock_class *class = NULL;
2498 struct held_lock *hlock;
2499 unsigned int depth, id;
2506 if (unlikely(!debug_locks))
2509 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2512 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2514 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2515 printk("turning off the locking correctness validator.\n");
2520 class = lock->class_cache;
2522 * Not cached yet or subclass?
2524 if (unlikely(!class)) {
2525 class = register_lock_class(lock, subclass, 0);
2529 debug_atomic_inc((atomic_t *)&class->ops);
2530 if (very_verbose(class)) {
2531 printk("\nacquire class [%p] %s", class->key, class->name);
2532 if (class->name_version > 1)
2533 printk("#%d", class->name_version);
2539 * Add the lock to the list of currently held locks.
2540 * (we dont increase the depth just yet, up until the
2541 * dependency checks are done)
2543 depth = curr->lockdep_depth;
2544 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2547 hlock = curr->held_locks + depth;
2549 hlock->class = class;
2550 hlock->acquire_ip = ip;
2551 hlock->instance = lock;
2552 hlock->trylock = trylock;
2554 hlock->check = check;
2555 hlock->hardirqs_off = hardirqs_off;
2556 #ifdef CONFIG_LOCK_STAT
2557 hlock->waittime_stamp = 0;
2558 hlock->holdtime_stamp = sched_clock();
2561 if (check == 2 && !mark_irqflags(curr, hlock))
2564 /* mark it as used: */
2565 if (!mark_lock(curr, hlock, LOCK_USED))
2569 * Calculate the chain hash: it's the combined hash of all the
2570 * lock keys along the dependency chain. We save the hash value
2571 * at every step so that we can get the current hash easily
2572 * after unlock. The chain hash is then used to cache dependency
2575 * The 'key ID' is what is the most compact key value to drive
2576 * the hash, not class->key.
2578 id = class - lock_classes;
2579 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2582 chain_key = curr->curr_chain_key;
2584 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2589 hlock->prev_chain_key = chain_key;
2590 if (separate_irq_context(curr, hlock)) {
2594 chain_key = iterate_chain_key(chain_key, id);
2596 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2599 curr->curr_chain_key = chain_key;
2600 curr->lockdep_depth++;
2601 check_chain_key(curr);
2602 #ifdef CONFIG_DEBUG_LOCKDEP
2603 if (unlikely(!debug_locks))
2606 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2608 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2609 printk("turning off the locking correctness validator.\n");
2613 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2614 max_lockdep_depth = curr->lockdep_depth;
2620 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2623 if (!debug_locks_off())
2625 if (debug_locks_silent)
2628 printk("\n=====================================\n");
2629 printk( "[ BUG: bad unlock balance detected! ]\n");
2630 printk( "-------------------------------------\n");
2631 printk("%s/%d is trying to release lock (",
2632 curr->comm, task_pid_nr(curr));
2633 print_lockdep_cache(lock);
2636 printk("but there are no more locks to release!\n");
2637 printk("\nother info that might help us debug this:\n");
2638 lockdep_print_held_locks(curr);
2640 printk("\nstack backtrace:\n");
2647 * Common debugging checks for both nested and non-nested unlock:
2649 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2652 if (unlikely(!debug_locks))
2654 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2657 if (curr->lockdep_depth <= 0)
2658 return print_unlock_inbalance_bug(curr, lock, ip);
2664 * Remove the lock to the list of currently held locks in a
2665 * potentially non-nested (out of order) manner. This is a
2666 * relatively rare operation, as all the unlock APIs default
2667 * to nested mode (which uses lock_release()):
2670 lock_release_non_nested(struct task_struct *curr,
2671 struct lockdep_map *lock, unsigned long ip)
2673 struct held_lock *hlock, *prev_hlock;
2678 * Check whether the lock exists in the current stack
2681 depth = curr->lockdep_depth;
2682 if (DEBUG_LOCKS_WARN_ON(!depth))
2686 for (i = depth-1; i >= 0; i--) {
2687 hlock = curr->held_locks + i;
2689 * We must not cross into another context:
2691 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2693 if (hlock->instance == lock)
2697 return print_unlock_inbalance_bug(curr, lock, ip);
2700 lock_release_holdtime(hlock);
2703 * We have the right lock to unlock, 'hlock' points to it.
2704 * Now we remove it from the stack, and add back the other
2705 * entries (if any), recalculating the hash along the way:
2707 curr->lockdep_depth = i;
2708 curr->curr_chain_key = hlock->prev_chain_key;
2710 for (i++; i < depth; i++) {
2711 hlock = curr->held_locks + i;
2712 if (!__lock_acquire(hlock->instance,
2713 hlock->class->subclass, hlock->trylock,
2714 hlock->read, hlock->check, hlock->hardirqs_off,
2719 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2725 * Remove the lock to the list of currently held locks - this gets
2726 * called on mutex_unlock()/spin_unlock*() (or on a failed
2727 * mutex_lock_interruptible()). This is done for unlocks that nest
2728 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2730 static int lock_release_nested(struct task_struct *curr,
2731 struct lockdep_map *lock, unsigned long ip)
2733 struct held_lock *hlock;
2737 * Pop off the top of the lock stack:
2739 depth = curr->lockdep_depth - 1;
2740 hlock = curr->held_locks + depth;
2743 * Is the unlock non-nested:
2745 if (hlock->instance != lock)
2746 return lock_release_non_nested(curr, lock, ip);
2747 curr->lockdep_depth--;
2749 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2752 curr->curr_chain_key = hlock->prev_chain_key;
2754 lock_release_holdtime(hlock);
2756 #ifdef CONFIG_DEBUG_LOCKDEP
2757 hlock->prev_chain_key = 0;
2758 hlock->class = NULL;
2759 hlock->acquire_ip = 0;
2760 hlock->irq_context = 0;
2766 * Remove the lock to the list of currently held locks - this gets
2767 * called on mutex_unlock()/spin_unlock*() (or on a failed
2768 * mutex_lock_interruptible()). This is done for unlocks that nest
2769 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2772 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2774 struct task_struct *curr = current;
2776 if (!check_unlock(curr, lock, ip))
2780 if (!lock_release_nested(curr, lock, ip))
2783 if (!lock_release_non_nested(curr, lock, ip))
2787 check_chain_key(curr);
2791 * Check whether we follow the irq-flags state precisely:
2793 static void check_flags(unsigned long flags)
2795 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2796 defined(CONFIG_TRACE_IRQFLAGS)
2800 if (irqs_disabled_flags(flags)) {
2801 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
2802 printk("possible reason: unannotated irqs-off.\n");
2805 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
2806 printk("possible reason: unannotated irqs-on.\n");
2811 * We dont accurately track softirq state in e.g.
2812 * hardirq contexts (such as on 4KSTACKS), so only
2813 * check if not in hardirq contexts:
2815 if (!hardirq_count()) {
2816 if (softirq_count())
2817 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2819 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2823 print_irqtrace_events(current);
2828 * We are not always called with irqs disabled - do that here,
2829 * and also avoid lockdep recursion:
2831 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2832 int trylock, int read, int check, unsigned long ip)
2834 unsigned long flags;
2836 if (unlikely(!lock_stat && !prove_locking))
2839 if (unlikely(current->lockdep_recursion))
2842 raw_local_irq_save(flags);
2845 current->lockdep_recursion = 1;
2846 __lock_acquire(lock, subclass, trylock, read, check,
2847 irqs_disabled_flags(flags), ip);
2848 current->lockdep_recursion = 0;
2849 raw_local_irq_restore(flags);
2852 EXPORT_SYMBOL_GPL(lock_acquire);
2854 void lock_release(struct lockdep_map *lock, int nested,
2857 unsigned long flags;
2859 if (unlikely(!lock_stat && !prove_locking))
2862 if (unlikely(current->lockdep_recursion))
2865 raw_local_irq_save(flags);
2867 current->lockdep_recursion = 1;
2868 __lock_release(lock, nested, ip);
2869 current->lockdep_recursion = 0;
2870 raw_local_irq_restore(flags);
2873 EXPORT_SYMBOL_GPL(lock_release);
2875 #ifdef CONFIG_LOCK_STAT
2877 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
2880 if (!debug_locks_off())
2882 if (debug_locks_silent)
2885 printk("\n=================================\n");
2886 printk( "[ BUG: bad contention detected! ]\n");
2887 printk( "---------------------------------\n");
2888 printk("%s/%d is trying to contend lock (",
2889 curr->comm, task_pid_nr(curr));
2890 print_lockdep_cache(lock);
2893 printk("but there are no locks held!\n");
2894 printk("\nother info that might help us debug this:\n");
2895 lockdep_print_held_locks(curr);
2897 printk("\nstack backtrace:\n");
2904 __lock_contended(struct lockdep_map *lock, unsigned long ip)
2906 struct task_struct *curr = current;
2907 struct held_lock *hlock, *prev_hlock;
2908 struct lock_class_stats *stats;
2912 depth = curr->lockdep_depth;
2913 if (DEBUG_LOCKS_WARN_ON(!depth))
2917 for (i = depth-1; i >= 0; i--) {
2918 hlock = curr->held_locks + i;
2920 * We must not cross into another context:
2922 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2924 if (hlock->instance == lock)
2928 print_lock_contention_bug(curr, lock, ip);
2932 hlock->waittime_stamp = sched_clock();
2934 point = lock_contention_point(hlock->class, ip);
2936 stats = get_lock_stats(hlock->class);
2937 if (point < ARRAY_SIZE(stats->contention_point))
2938 stats->contention_point[i]++;
2939 if (lock->cpu != smp_processor_id())
2940 stats->bounces[bounce_contended + !!hlock->read]++;
2941 put_lock_stats(stats);
2945 __lock_acquired(struct lockdep_map *lock)
2947 struct task_struct *curr = current;
2948 struct held_lock *hlock, *prev_hlock;
2949 struct lock_class_stats *stats;
2955 depth = curr->lockdep_depth;
2956 if (DEBUG_LOCKS_WARN_ON(!depth))
2960 for (i = depth-1; i >= 0; i--) {
2961 hlock = curr->held_locks + i;
2963 * We must not cross into another context:
2965 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2967 if (hlock->instance == lock)
2971 print_lock_contention_bug(curr, lock, _RET_IP_);
2975 cpu = smp_processor_id();
2976 if (hlock->waittime_stamp) {
2977 now = sched_clock();
2978 waittime = now - hlock->waittime_stamp;
2979 hlock->holdtime_stamp = now;
2982 stats = get_lock_stats(hlock->class);
2985 lock_time_inc(&stats->read_waittime, waittime);
2987 lock_time_inc(&stats->write_waittime, waittime);
2989 if (lock->cpu != cpu)
2990 stats->bounces[bounce_acquired + !!hlock->read]++;
2991 put_lock_stats(stats);
2996 void lock_contended(struct lockdep_map *lock, unsigned long ip)
2998 unsigned long flags;
3000 if (unlikely(!lock_stat))
3003 if (unlikely(current->lockdep_recursion))
3006 raw_local_irq_save(flags);
3008 current->lockdep_recursion = 1;
3009 __lock_contended(lock, ip);
3010 current->lockdep_recursion = 0;
3011 raw_local_irq_restore(flags);
3013 EXPORT_SYMBOL_GPL(lock_contended);
3015 void lock_acquired(struct lockdep_map *lock)
3017 unsigned long flags;
3019 if (unlikely(!lock_stat))
3022 if (unlikely(current->lockdep_recursion))
3025 raw_local_irq_save(flags);
3027 current->lockdep_recursion = 1;
3028 __lock_acquired(lock);
3029 current->lockdep_recursion = 0;
3030 raw_local_irq_restore(flags);
3032 EXPORT_SYMBOL_GPL(lock_acquired);
3036 * Used by the testsuite, sanitize the validator state
3037 * after a simulated failure:
3040 void lockdep_reset(void)
3042 unsigned long flags;
3045 raw_local_irq_save(flags);
3046 current->curr_chain_key = 0;
3047 current->lockdep_depth = 0;
3048 current->lockdep_recursion = 0;
3049 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3050 nr_hardirq_chains = 0;
3051 nr_softirq_chains = 0;
3052 nr_process_chains = 0;
3054 for (i = 0; i < CHAINHASH_SIZE; i++)
3055 INIT_LIST_HEAD(chainhash_table + i);
3056 raw_local_irq_restore(flags);
3059 static void zap_class(struct lock_class *class)
3064 * Remove all dependencies this lock is
3067 for (i = 0; i < nr_list_entries; i++) {
3068 if (list_entries[i].class == class)
3069 list_del_rcu(&list_entries[i].entry);
3072 * Unhash the class and remove it from the all_lock_classes list:
3074 list_del_rcu(&class->hash_entry);
3075 list_del_rcu(&class->lock_entry);
3079 static inline int within(const void *addr, void *start, unsigned long size)
3081 return addr >= start && addr < start + size;
3084 void lockdep_free_key_range(void *start, unsigned long size)
3086 struct lock_class *class, *next;
3087 struct list_head *head;
3088 unsigned long flags;
3092 raw_local_irq_save(flags);
3093 locked = graph_lock();
3096 * Unhash all classes that were created by this module:
3098 for (i = 0; i < CLASSHASH_SIZE; i++) {
3099 head = classhash_table + i;
3100 if (list_empty(head))
3102 list_for_each_entry_safe(class, next, head, hash_entry) {
3103 if (within(class->key, start, size))
3105 else if (within(class->name, start, size))
3112 raw_local_irq_restore(flags);
3115 void lockdep_reset_lock(struct lockdep_map *lock)
3117 struct lock_class *class, *next;
3118 struct list_head *head;
3119 unsigned long flags;
3123 raw_local_irq_save(flags);
3126 * Remove all classes this lock might have:
3128 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3130 * If the class exists we look it up and zap it:
3132 class = look_up_lock_class(lock, j);
3137 * Debug check: in the end all mapped classes should
3140 locked = graph_lock();
3141 for (i = 0; i < CLASSHASH_SIZE; i++) {
3142 head = classhash_table + i;
3143 if (list_empty(head))
3145 list_for_each_entry_safe(class, next, head, hash_entry) {
3146 if (unlikely(class == lock->class_cache)) {
3147 if (debug_locks_off_graph_unlock())
3157 raw_local_irq_restore(flags);
3160 void lockdep_init(void)
3165 * Some architectures have their own start_kernel()
3166 * code which calls lockdep_init(), while we also
3167 * call lockdep_init() from the start_kernel() itself,
3168 * and we want to initialize the hashes only once:
3170 if (lockdep_initialized)
3173 for (i = 0; i < CLASSHASH_SIZE; i++)
3174 INIT_LIST_HEAD(classhash_table + i);
3176 for (i = 0; i < CHAINHASH_SIZE; i++)
3177 INIT_LIST_HEAD(chainhash_table + i);
3179 lockdep_initialized = 1;
3182 void __init lockdep_info(void)
3184 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3186 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3187 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3188 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3189 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3190 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3191 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3192 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3194 printk(" memory used by lock dependency info: %lu kB\n",
3195 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3196 sizeof(struct list_head) * CLASSHASH_SIZE +
3197 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3198 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3199 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
3201 printk(" per task-struct memory footprint: %lu bytes\n",
3202 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3204 #ifdef CONFIG_DEBUG_LOCKDEP
3205 if (lockdep_init_error) {
3206 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3207 printk("Call stack leading to lockdep invocation was:\n");
3208 print_stack_trace(&lockdep_init_trace, 0);
3214 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3215 const void *mem_to, struct held_lock *hlock)
3217 if (!debug_locks_off())
3219 if (debug_locks_silent)
3222 printk("\n=========================\n");
3223 printk( "[ BUG: held lock freed! ]\n");
3224 printk( "-------------------------\n");
3225 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3226 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3228 lockdep_print_held_locks(curr);
3230 printk("\nstack backtrace:\n");
3234 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3235 const void* lock_from, unsigned long lock_len)
3237 return lock_from + lock_len <= mem_from ||
3238 mem_from + mem_len <= lock_from;
3242 * Called when kernel memory is freed (or unmapped), or if a lock
3243 * is destroyed or reinitialized - this code checks whether there is
3244 * any held lock in the memory range of <from> to <to>:
3246 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3248 struct task_struct *curr = current;
3249 struct held_lock *hlock;
3250 unsigned long flags;
3253 if (unlikely(!debug_locks))
3256 local_irq_save(flags);
3257 for (i = 0; i < curr->lockdep_depth; i++) {
3258 hlock = curr->held_locks + i;
3260 if (not_in_range(mem_from, mem_len, hlock->instance,
3261 sizeof(*hlock->instance)))
3264 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3267 local_irq_restore(flags);
3269 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3271 static void print_held_locks_bug(struct task_struct *curr)
3273 if (!debug_locks_off())
3275 if (debug_locks_silent)
3278 printk("\n=====================================\n");
3279 printk( "[ BUG: lock held at task exit time! ]\n");
3280 printk( "-------------------------------------\n");
3281 printk("%s/%d is exiting with locks still held!\n",
3282 curr->comm, task_pid_nr(curr));
3283 lockdep_print_held_locks(curr);
3285 printk("\nstack backtrace:\n");
3289 void debug_check_no_locks_held(struct task_struct *task)
3291 if (unlikely(task->lockdep_depth > 0))
3292 print_held_locks_bug(task);
3295 void debug_show_all_locks(void)
3297 struct task_struct *g, *p;
3301 if (unlikely(!debug_locks)) {
3302 printk("INFO: lockdep is turned off.\n");
3305 printk("\nShowing all locks held in the system:\n");
3308 * Here we try to get the tasklist_lock as hard as possible,
3309 * if not successful after 2 seconds we ignore it (but keep
3310 * trying). This is to enable a debug printout even if a
3311 * tasklist_lock-holding task deadlocks or crashes.
3314 if (!read_trylock(&tasklist_lock)) {
3316 printk("hm, tasklist_lock locked, retrying... ");
3319 printk(" #%d", 10-count);
3323 printk(" ignoring it.\n");
3327 printk(" locked it.\n");
3329 do_each_thread(g, p) {
3331 * It's not reliable to print a task's held locks
3332 * if it's not sleeping (or if it's not the current
3335 if (p->state == TASK_RUNNING && p != current)
3337 if (p->lockdep_depth)
3338 lockdep_print_held_locks(p);
3340 if (read_trylock(&tasklist_lock))
3342 } while_each_thread(g, p);
3345 printk("=============================================\n\n");
3348 read_unlock(&tasklist_lock);
3351 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3354 * Careful: only use this function if you are sure that
3355 * the task cannot run in parallel!
3357 void __debug_show_held_locks(struct task_struct *task)
3359 if (unlikely(!debug_locks)) {
3360 printk("INFO: lockdep is turned off.\n");
3363 lockdep_print_held_locks(task);
3365 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3367 void debug_show_held_locks(struct task_struct *task)
3369 __debug_show_held_locks(task);
3372 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3374 void lockdep_sys_exit(void)
3376 struct task_struct *curr = current;
3378 if (unlikely(curr->lockdep_depth)) {
3379 if (!debug_locks_off())
3381 printk("\n================================================\n");
3382 printk( "[ BUG: lock held when returning to user space! ]\n");
3383 printk( "------------------------------------------------\n");
3384 printk("%s/%d is leaving the kernel with locks still held!\n",
3385 curr->comm, curr->pid);
3386 lockdep_print_held_locks(curr);