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>
43 #include <asm/sections.h>
45 #include "lockdep_internals.h"
47 #ifdef CONFIG_PROVE_LOCKING
48 int prove_locking = 1;
49 module_param(prove_locking, int, 0644);
51 #define prove_locking 0
54 #ifdef CONFIG_LOCK_STAT
56 module_param(lock_stat, int, 0644);
62 * lockdep_lock: protects the lockdep graph, the hashes and the
63 * class/list/hash allocators.
65 * This is one of the rare exceptions where it's justified
66 * to use a raw spinlock - we really dont want the spinlock
67 * code to recurse back into the lockdep code...
69 static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
71 static int graph_lock(void)
73 __raw_spin_lock(&lockdep_lock);
75 * Make sure that if another CPU detected a bug while
76 * walking the graph we dont change it (while the other
77 * CPU is busy printing out stuff with the graph lock
81 __raw_spin_unlock(&lockdep_lock);
87 static inline int graph_unlock(void)
89 if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
90 return DEBUG_LOCKS_WARN_ON(1);
92 __raw_spin_unlock(&lockdep_lock);
97 * Turn lock debugging off and return with 0 if it was off already,
98 * and also release the graph lock:
100 static inline int debug_locks_off_graph_unlock(void)
102 int ret = debug_locks_off();
104 __raw_spin_unlock(&lockdep_lock);
109 static int lockdep_initialized;
111 unsigned long nr_list_entries;
112 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
115 * All data structures here are protected by the global debug_lock.
117 * Mutex key structs only get allocated, once during bootup, and never
118 * get freed - this significantly simplifies the debugging code.
120 unsigned long nr_lock_classes;
121 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
123 #ifdef CONFIG_LOCK_STAT
124 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
126 static int lock_contention_point(struct lock_class *class, unsigned long ip)
130 for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {
131 if (class->contention_point[i] == 0) {
132 class->contention_point[i] = ip;
135 if (class->contention_point[i] == ip)
142 static void lock_time_inc(struct lock_time *lt, s64 time)
147 if (time < lt->min || !lt->min)
154 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
156 dst->min += src->min;
157 dst->max += src->max;
158 dst->total += src->total;
162 struct lock_class_stats lock_stats(struct lock_class *class)
164 struct lock_class_stats stats;
167 memset(&stats, 0, sizeof(struct lock_class_stats));
168 for_each_possible_cpu(cpu) {
169 struct lock_class_stats *pcs =
170 &per_cpu(lock_stats, cpu)[class - lock_classes];
172 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
173 stats.contention_point[i] += pcs->contention_point[i];
175 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
176 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
178 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
179 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
181 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
182 stats.bounces[i] += pcs->bounces[i];
188 void clear_lock_stats(struct lock_class *class)
192 for_each_possible_cpu(cpu) {
193 struct lock_class_stats *cpu_stats =
194 &per_cpu(lock_stats, cpu)[class - lock_classes];
196 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
198 memset(class->contention_point, 0, sizeof(class->contention_point));
201 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
203 return &get_cpu_var(lock_stats)[class - lock_classes];
206 static void put_lock_stats(struct lock_class_stats *stats)
208 put_cpu_var(lock_stats);
211 static void lock_release_holdtime(struct held_lock *hlock)
213 struct lock_class_stats *stats;
219 holdtime = sched_clock() - hlock->holdtime_stamp;
221 stats = get_lock_stats(hlock->class);
223 lock_time_inc(&stats->read_holdtime, holdtime);
225 lock_time_inc(&stats->write_holdtime, holdtime);
226 put_lock_stats(stats);
229 static inline void lock_release_holdtime(struct held_lock *hlock)
235 * We keep a global list of all lock classes. The list only grows,
236 * never shrinks. The list is only accessed with the lockdep
237 * spinlock lock held.
239 LIST_HEAD(all_lock_classes);
242 * The lockdep classes are in a hash-table as well, for fast lookup:
244 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
245 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
246 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
247 #define classhashentry(key) (classhash_table + __classhashfn((key)))
249 static struct list_head classhash_table[CLASSHASH_SIZE];
252 * We put the lock dependency chains into a hash-table as well, to cache
255 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
256 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
257 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
258 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
260 static struct list_head chainhash_table[CHAINHASH_SIZE];
263 * The hash key of the lock dependency chains is a hash itself too:
264 * it's a hash of all locks taken up to that lock, including that lock.
265 * It's a 64-bit hash, because it's important for the keys to be
268 #define iterate_chain_key(key1, key2) \
269 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
270 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
273 void lockdep_off(void)
275 current->lockdep_recursion++;
278 EXPORT_SYMBOL(lockdep_off);
280 void lockdep_on(void)
282 current->lockdep_recursion--;
285 EXPORT_SYMBOL(lockdep_on);
288 * Debugging switches:
292 #define VERY_VERBOSE 0
295 # define HARDIRQ_VERBOSE 1
296 # define SOFTIRQ_VERBOSE 1
298 # define HARDIRQ_VERBOSE 0
299 # define SOFTIRQ_VERBOSE 0
302 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
304 * Quick filtering for interesting events:
306 static int class_filter(struct lock_class *class)
310 if (class->name_version == 1 &&
311 !strcmp(class->name, "lockname"))
313 if (class->name_version == 1 &&
314 !strcmp(class->name, "&struct->lockfield"))
317 /* Filter everything else. 1 would be to allow everything else */
322 static int verbose(struct lock_class *class)
325 return class_filter(class);
331 * Stack-trace: tightly packed array of stack backtrace
332 * addresses. Protected by the graph_lock.
334 unsigned long nr_stack_trace_entries;
335 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
337 static int save_trace(struct stack_trace *trace)
339 trace->nr_entries = 0;
340 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
341 trace->entries = stack_trace + nr_stack_trace_entries;
345 save_stack_trace(trace);
347 trace->max_entries = trace->nr_entries;
349 nr_stack_trace_entries += trace->nr_entries;
351 if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
352 if (!debug_locks_off_graph_unlock())
355 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
356 printk("turning off the locking correctness validator.\n");
365 unsigned int nr_hardirq_chains;
366 unsigned int nr_softirq_chains;
367 unsigned int nr_process_chains;
368 unsigned int max_lockdep_depth;
369 unsigned int max_recursion_depth;
371 #ifdef CONFIG_DEBUG_LOCKDEP
373 * We cannot printk in early bootup code. Not even early_printk()
374 * might work. So we mark any initialization errors and printk
375 * about it later on, in lockdep_info().
377 static int lockdep_init_error;
378 static unsigned long lockdep_init_trace_data[20];
379 static struct stack_trace lockdep_init_trace = {
380 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
381 .entries = lockdep_init_trace_data,
385 * Various lockdep statistics:
387 atomic_t chain_lookup_hits;
388 atomic_t chain_lookup_misses;
389 atomic_t hardirqs_on_events;
390 atomic_t hardirqs_off_events;
391 atomic_t redundant_hardirqs_on;
392 atomic_t redundant_hardirqs_off;
393 atomic_t softirqs_on_events;
394 atomic_t softirqs_off_events;
395 atomic_t redundant_softirqs_on;
396 atomic_t redundant_softirqs_off;
397 atomic_t nr_unused_locks;
398 atomic_t nr_cyclic_checks;
399 atomic_t nr_cyclic_check_recursions;
400 atomic_t nr_find_usage_forwards_checks;
401 atomic_t nr_find_usage_forwards_recursions;
402 atomic_t nr_find_usage_backwards_checks;
403 atomic_t nr_find_usage_backwards_recursions;
404 # define debug_atomic_inc(ptr) atomic_inc(ptr)
405 # define debug_atomic_dec(ptr) atomic_dec(ptr)
406 # define debug_atomic_read(ptr) atomic_read(ptr)
408 # define debug_atomic_inc(ptr) do { } while (0)
409 # define debug_atomic_dec(ptr) do { } while (0)
410 # define debug_atomic_read(ptr) 0
417 static const char *usage_str[] =
419 [LOCK_USED] = "initial-use ",
420 [LOCK_USED_IN_HARDIRQ] = "in-hardirq-W",
421 [LOCK_USED_IN_SOFTIRQ] = "in-softirq-W",
422 [LOCK_ENABLED_SOFTIRQS] = "softirq-on-W",
423 [LOCK_ENABLED_HARDIRQS] = "hardirq-on-W",
424 [LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R",
425 [LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R",
426 [LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R",
427 [LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R",
430 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
432 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
436 get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
438 *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
440 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
443 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
446 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
449 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
452 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
454 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
456 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
460 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
462 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
464 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
469 static void print_lock_name(struct lock_class *class)
471 char str[KSYM_NAME_LEN], c1, c2, c3, c4;
474 get_usage_chars(class, &c1, &c2, &c3, &c4);
478 name = __get_key_name(class->key, str);
479 printk(" (%s", name);
481 printk(" (%s", name);
482 if (class->name_version > 1)
483 printk("#%d", class->name_version);
485 printk("/%d", class->subclass);
487 printk("){%c%c%c%c}", c1, c2, c3, c4);
490 static void print_lockdep_cache(struct lockdep_map *lock)
493 char str[KSYM_NAME_LEN];
497 name = __get_key_name(lock->key->subkeys, str);
502 static void print_lock(struct held_lock *hlock)
504 print_lock_name(hlock->class);
506 print_ip_sym(hlock->acquire_ip);
509 static void lockdep_print_held_locks(struct task_struct *curr)
511 int i, depth = curr->lockdep_depth;
514 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
517 printk("%d lock%s held by %s/%d:\n",
518 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
520 for (i = 0; i < depth; i++) {
522 print_lock(curr->held_locks + i);
526 static void print_lock_class_header(struct lock_class *class, int depth)
530 printk("%*s->", depth, "");
531 print_lock_name(class);
532 printk(" ops: %lu", class->ops);
535 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
536 if (class->usage_mask & (1 << bit)) {
539 len += printk("%*s %s", depth, "", usage_str[bit]);
540 len += printk(" at:\n");
541 print_stack_trace(class->usage_traces + bit, len);
544 printk("%*s }\n", depth, "");
546 printk("%*s ... key at: ",depth,"");
547 print_ip_sym((unsigned long)class->key);
551 * printk all lock dependencies starting at <entry>:
553 static void print_lock_dependencies(struct lock_class *class, int depth)
555 struct lock_list *entry;
557 if (DEBUG_LOCKS_WARN_ON(depth >= 20))
560 print_lock_class_header(class, depth);
562 list_for_each_entry(entry, &class->locks_after, entry) {
563 if (DEBUG_LOCKS_WARN_ON(!entry->class))
566 print_lock_dependencies(entry->class, depth + 1);
568 printk("%*s ... acquired at:\n",depth,"");
569 print_stack_trace(&entry->trace, 2);
574 static void print_kernel_version(void)
576 printk("%s %.*s\n", init_utsname()->release,
577 (int)strcspn(init_utsname()->version, " "),
578 init_utsname()->version);
581 static int very_verbose(struct lock_class *class)
584 return class_filter(class);
590 * Is this the address of a static object:
592 static int static_obj(void *obj)
594 unsigned long start = (unsigned long) &_stext,
595 end = (unsigned long) &_end,
596 addr = (unsigned long) obj;
604 if ((addr >= start) && (addr < end))
611 for_each_possible_cpu(i) {
612 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
613 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
616 if ((addr >= start) && (addr < end))
624 return is_module_address(addr);
628 * To make lock name printouts unique, we calculate a unique
629 * class->name_version generation counter:
631 static int count_matching_names(struct lock_class *new_class)
633 struct lock_class *class;
636 if (!new_class->name)
639 list_for_each_entry(class, &all_lock_classes, lock_entry) {
640 if (new_class->key - new_class->subclass == class->key)
641 return class->name_version;
642 if (class->name && !strcmp(class->name, new_class->name))
643 count = max(count, class->name_version);
650 * Register a lock's class in the hash-table, if the class is not present
651 * yet. Otherwise we look it up. We cache the result in the lock object
652 * itself, so actual lookup of the hash should be once per lock object.
654 static inline struct lock_class *
655 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
657 struct lockdep_subclass_key *key;
658 struct list_head *hash_head;
659 struct lock_class *class;
661 #ifdef CONFIG_DEBUG_LOCKDEP
663 * If the architecture calls into lockdep before initializing
664 * the hashes then we'll warn about it later. (we cannot printk
667 if (unlikely(!lockdep_initialized)) {
669 lockdep_init_error = 1;
670 save_stack_trace(&lockdep_init_trace);
675 * Static locks do not have their class-keys yet - for them the key
676 * is the lock object itself:
678 if (unlikely(!lock->key))
679 lock->key = (void *)lock;
682 * NOTE: the class-key must be unique. For dynamic locks, a static
683 * lock_class_key variable is passed in through the mutex_init()
684 * (or spin_lock_init()) call - which acts as the key. For static
685 * locks we use the lock object itself as the key.
687 BUILD_BUG_ON(sizeof(struct lock_class_key) >
688 sizeof(struct lockdep_map));
690 key = lock->key->subkeys + subclass;
692 hash_head = classhashentry(key);
695 * We can walk the hash lockfree, because the hash only
696 * grows, and we are careful when adding entries to the end:
698 list_for_each_entry(class, hash_head, hash_entry) {
699 if (class->key == key) {
700 WARN_ON_ONCE(class->name != lock->name);
709 * Register a lock's class in the hash-table, if the class is not present
710 * yet. Otherwise we look it up. We cache the result in the lock object
711 * itself, so actual lookup of the hash should be once per lock object.
713 static inline struct lock_class *
714 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
716 struct lockdep_subclass_key *key;
717 struct list_head *hash_head;
718 struct lock_class *class;
721 class = look_up_lock_class(lock, subclass);
726 * Debug-check: all keys must be persistent!
728 if (!static_obj(lock->key)) {
730 printk("INFO: trying to register non-static key.\n");
731 printk("the code is fine but needs lockdep annotation.\n");
732 printk("turning off the locking correctness validator.\n");
738 key = lock->key->subkeys + subclass;
739 hash_head = classhashentry(key);
741 raw_local_irq_save(flags);
743 raw_local_irq_restore(flags);
747 * We have to do the hash-walk again, to avoid races
750 list_for_each_entry(class, hash_head, hash_entry)
751 if (class->key == key)
754 * Allocate a new key from the static array, and add it to
757 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
758 if (!debug_locks_off_graph_unlock()) {
759 raw_local_irq_restore(flags);
762 raw_local_irq_restore(flags);
764 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
765 printk("turning off the locking correctness validator.\n");
768 class = lock_classes + nr_lock_classes++;
769 debug_atomic_inc(&nr_unused_locks);
771 class->name = lock->name;
772 class->subclass = subclass;
773 INIT_LIST_HEAD(&class->lock_entry);
774 INIT_LIST_HEAD(&class->locks_before);
775 INIT_LIST_HEAD(&class->locks_after);
776 class->name_version = count_matching_names(class);
778 * We use RCU's safe list-add method to make
779 * parallel walking of the hash-list safe:
781 list_add_tail_rcu(&class->hash_entry, hash_head);
783 * Add it to the global list of classes:
785 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
787 if (verbose(class)) {
789 raw_local_irq_restore(flags);
791 printk("\nnew class %p: %s", class->key, class->name);
792 if (class->name_version > 1)
793 printk("#%d", class->name_version);
797 raw_local_irq_save(flags);
799 raw_local_irq_restore(flags);
805 raw_local_irq_restore(flags);
807 if (!subclass || force)
808 lock->class_cache = class;
810 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
816 #ifdef CONFIG_PROVE_LOCKING
818 * Allocate a lockdep entry. (assumes the graph_lock held, returns
819 * with NULL on failure)
821 static struct lock_list *alloc_list_entry(void)
823 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
824 if (!debug_locks_off_graph_unlock())
827 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
828 printk("turning off the locking correctness validator.\n");
831 return list_entries + nr_list_entries++;
835 * Add a new dependency to the head of the list:
837 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
838 struct list_head *head, unsigned long ip, int distance)
840 struct lock_list *entry;
842 * Lock not present yet - get a new dependency struct and
843 * add it to the list:
845 entry = alloc_list_entry();
850 entry->distance = distance;
851 if (!save_trace(&entry->trace))
855 * Since we never remove from the dependency list, the list can
856 * be walked lockless by other CPUs, it's only allocation
857 * that must be protected by the spinlock. But this also means
858 * we must make new entries visible only once writes to the
859 * entry become visible - hence the RCU op:
861 list_add_tail_rcu(&entry->entry, head);
867 * Recursive, forwards-direction lock-dependency checking, used for
868 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
871 * (to keep the stackframe of the recursive functions small we
872 * use these global variables, and we also mark various helper
873 * functions as noinline.)
875 static struct held_lock *check_source, *check_target;
878 * Print a dependency chain entry (this is only done when a deadlock
879 * has been detected):
882 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
884 if (debug_locks_silent)
886 printk("\n-> #%u", depth);
887 print_lock_name(target->class);
889 print_stack_trace(&target->trace, 6);
895 * When a circular dependency is detected, print the
899 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
901 struct task_struct *curr = current;
903 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
906 printk("\n=======================================================\n");
907 printk( "[ INFO: possible circular locking dependency detected ]\n");
908 print_kernel_version();
909 printk( "-------------------------------------------------------\n");
910 printk("%s/%d is trying to acquire lock:\n",
911 curr->comm, task_pid_nr(curr));
912 print_lock(check_source);
913 printk("\nbut task is already holding lock:\n");
914 print_lock(check_target);
915 printk("\nwhich lock already depends on the new lock.\n\n");
916 printk("\nthe existing dependency chain (in reverse order) is:\n");
918 print_circular_bug_entry(entry, depth);
923 static noinline int print_circular_bug_tail(void)
925 struct task_struct *curr = current;
926 struct lock_list this;
928 if (debug_locks_silent)
931 this.class = check_source->class;
932 if (!save_trace(&this.trace))
935 print_circular_bug_entry(&this, 0);
937 printk("\nother info that might help us debug this:\n\n");
938 lockdep_print_held_locks(curr);
940 printk("\nstack backtrace:\n");
946 #define RECURSION_LIMIT 40
948 static int noinline print_infinite_recursion_bug(void)
950 if (!debug_locks_off_graph_unlock())
959 * Prove that the dependency graph starting at <entry> can not
960 * lead to <target>. Print an error and return 0 if it does.
963 check_noncircular(struct lock_class *source, unsigned int depth)
965 struct lock_list *entry;
967 debug_atomic_inc(&nr_cyclic_check_recursions);
968 if (depth > max_recursion_depth)
969 max_recursion_depth = depth;
970 if (depth >= RECURSION_LIMIT)
971 return print_infinite_recursion_bug();
973 * Check this lock's dependency list:
975 list_for_each_entry(entry, &source->locks_after, entry) {
976 if (entry->class == check_target->class)
977 return print_circular_bug_header(entry, depth+1);
978 debug_atomic_inc(&nr_cyclic_checks);
979 if (!check_noncircular(entry->class, depth+1))
980 return print_circular_bug_entry(entry, depth+1);
985 #ifdef CONFIG_TRACE_IRQFLAGS
987 * Forwards and backwards subgraph searching, for the purposes of
988 * proving that two subgraphs can be connected by a new dependency
989 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
991 static enum lock_usage_bit find_usage_bit;
992 static struct lock_class *forwards_match, *backwards_match;
995 * Find a node in the forwards-direction dependency sub-graph starting
996 * at <source> that matches <find_usage_bit>.
998 * Return 2 if such a node exists in the subgraph, and put that node
999 * into <forwards_match>.
1001 * Return 1 otherwise and keep <forwards_match> unchanged.
1002 * Return 0 on error.
1005 find_usage_forwards(struct lock_class *source, unsigned int depth)
1007 struct lock_list *entry;
1010 if (depth > max_recursion_depth)
1011 max_recursion_depth = depth;
1012 if (depth >= RECURSION_LIMIT)
1013 return print_infinite_recursion_bug();
1015 debug_atomic_inc(&nr_find_usage_forwards_checks);
1016 if (source->usage_mask & (1 << find_usage_bit)) {
1017 forwards_match = source;
1022 * Check this lock's dependency list:
1024 list_for_each_entry(entry, &source->locks_after, entry) {
1025 debug_atomic_inc(&nr_find_usage_forwards_recursions);
1026 ret = find_usage_forwards(entry->class, depth+1);
1027 if (ret == 2 || ret == 0)
1034 * Find a node in the backwards-direction dependency sub-graph starting
1035 * at <source> that matches <find_usage_bit>.
1037 * Return 2 if such a node exists in the subgraph, and put that node
1038 * into <backwards_match>.
1040 * Return 1 otherwise and keep <backwards_match> unchanged.
1041 * Return 0 on error.
1044 find_usage_backwards(struct lock_class *source, unsigned int depth)
1046 struct lock_list *entry;
1049 if (!__raw_spin_is_locked(&lockdep_lock))
1050 return DEBUG_LOCKS_WARN_ON(1);
1052 if (depth > max_recursion_depth)
1053 max_recursion_depth = depth;
1054 if (depth >= RECURSION_LIMIT)
1055 return print_infinite_recursion_bug();
1057 debug_atomic_inc(&nr_find_usage_backwards_checks);
1058 if (source->usage_mask & (1 << find_usage_bit)) {
1059 backwards_match = source;
1064 * Check this lock's dependency list:
1066 list_for_each_entry(entry, &source->locks_before, entry) {
1067 debug_atomic_inc(&nr_find_usage_backwards_recursions);
1068 ret = find_usage_backwards(entry->class, depth+1);
1069 if (ret == 2 || ret == 0)
1076 print_bad_irq_dependency(struct task_struct *curr,
1077 struct held_lock *prev,
1078 struct held_lock *next,
1079 enum lock_usage_bit bit1,
1080 enum lock_usage_bit bit2,
1081 const char *irqclass)
1083 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1086 printk("\n======================================================\n");
1087 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1088 irqclass, irqclass);
1089 print_kernel_version();
1090 printk( "------------------------------------------------------\n");
1091 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1092 curr->comm, task_pid_nr(curr),
1093 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1094 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1095 curr->hardirqs_enabled,
1096 curr->softirqs_enabled);
1099 printk("\nand this task is already holding:\n");
1101 printk("which would create a new lock dependency:\n");
1102 print_lock_name(prev->class);
1104 print_lock_name(next->class);
1107 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1109 print_lock_name(backwards_match);
1110 printk("\n... which became %s-irq-safe at:\n", irqclass);
1112 print_stack_trace(backwards_match->usage_traces + bit1, 1);
1114 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1115 print_lock_name(forwards_match);
1116 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1119 print_stack_trace(forwards_match->usage_traces + bit2, 1);
1121 printk("\nother info that might help us debug this:\n\n");
1122 lockdep_print_held_locks(curr);
1124 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1125 print_lock_dependencies(backwards_match, 0);
1127 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1128 print_lock_dependencies(forwards_match, 0);
1130 printk("\nstack backtrace:\n");
1137 check_usage(struct task_struct *curr, struct held_lock *prev,
1138 struct held_lock *next, enum lock_usage_bit bit_backwards,
1139 enum lock_usage_bit bit_forwards, const char *irqclass)
1143 find_usage_bit = bit_backwards;
1144 /* fills in <backwards_match> */
1145 ret = find_usage_backwards(prev->class, 0);
1146 if (!ret || ret == 1)
1149 find_usage_bit = bit_forwards;
1150 ret = find_usage_forwards(next->class, 0);
1151 if (!ret || ret == 1)
1154 return print_bad_irq_dependency(curr, prev, next,
1155 bit_backwards, bit_forwards, irqclass);
1159 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1160 struct held_lock *next)
1163 * Prove that the new dependency does not connect a hardirq-safe
1164 * lock with a hardirq-unsafe lock - to achieve this we search
1165 * the backwards-subgraph starting at <prev>, and the
1166 * forwards-subgraph starting at <next>:
1168 if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
1169 LOCK_ENABLED_HARDIRQS, "hard"))
1173 * Prove that the new dependency does not connect a hardirq-safe-read
1174 * lock with a hardirq-unsafe lock - to achieve this we search
1175 * the backwards-subgraph starting at <prev>, and the
1176 * forwards-subgraph starting at <next>:
1178 if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
1179 LOCK_ENABLED_HARDIRQS, "hard-read"))
1183 * Prove that the new dependency does not connect a softirq-safe
1184 * lock with a softirq-unsafe lock - to achieve this we search
1185 * the backwards-subgraph starting at <prev>, and the
1186 * forwards-subgraph starting at <next>:
1188 if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
1189 LOCK_ENABLED_SOFTIRQS, "soft"))
1192 * Prove that the new dependency does not connect a softirq-safe-read
1193 * lock with a softirq-unsafe lock - to achieve this we search
1194 * the backwards-subgraph starting at <prev>, and the
1195 * forwards-subgraph starting at <next>:
1197 if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
1198 LOCK_ENABLED_SOFTIRQS, "soft"))
1204 static void inc_chains(void)
1206 if (current->hardirq_context)
1207 nr_hardirq_chains++;
1209 if (current->softirq_context)
1210 nr_softirq_chains++;
1212 nr_process_chains++;
1219 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1220 struct held_lock *next)
1225 static inline void inc_chains(void)
1227 nr_process_chains++;
1233 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1234 struct held_lock *next)
1236 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1239 printk("\n=============================================\n");
1240 printk( "[ INFO: possible recursive locking detected ]\n");
1241 print_kernel_version();
1242 printk( "---------------------------------------------\n");
1243 printk("%s/%d is trying to acquire lock:\n",
1244 curr->comm, task_pid_nr(curr));
1246 printk("\nbut task is already holding lock:\n");
1249 printk("\nother info that might help us debug this:\n");
1250 lockdep_print_held_locks(curr);
1252 printk("\nstack backtrace:\n");
1259 * Check whether we are holding such a class already.
1261 * (Note that this has to be done separately, because the graph cannot
1262 * detect such classes of deadlocks.)
1264 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1267 check_deadlock(struct task_struct *curr, struct held_lock *next,
1268 struct lockdep_map *next_instance, int read)
1270 struct held_lock *prev;
1273 for (i = 0; i < curr->lockdep_depth; i++) {
1274 prev = curr->held_locks + i;
1275 if (prev->class != next->class)
1278 * Allow read-after-read recursion of the same
1279 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1281 if ((read == 2) && prev->read)
1283 return print_deadlock_bug(curr, prev, next);
1289 * There was a chain-cache miss, and we are about to add a new dependency
1290 * to a previous lock. We recursively validate the following rules:
1292 * - would the adding of the <prev> -> <next> dependency create a
1293 * circular dependency in the graph? [== circular deadlock]
1295 * - does the new prev->next dependency connect any hardirq-safe lock
1296 * (in the full backwards-subgraph starting at <prev>) with any
1297 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1298 * <next>)? [== illegal lock inversion with hardirq contexts]
1300 * - does the new prev->next dependency connect any softirq-safe lock
1301 * (in the full backwards-subgraph starting at <prev>) with any
1302 * softirq-unsafe lock (in the full forwards-subgraph starting at
1303 * <next>)? [== illegal lock inversion with softirq contexts]
1305 * any of these scenarios could lead to a deadlock.
1307 * Then if all the validations pass, we add the forwards and backwards
1311 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1312 struct held_lock *next, int distance)
1314 struct lock_list *entry;
1318 * Prove that the new <prev> -> <next> dependency would not
1319 * create a circular dependency in the graph. (We do this by
1320 * forward-recursing into the graph starting at <next>, and
1321 * checking whether we can reach <prev>.)
1323 * We are using global variables to control the recursion, to
1324 * keep the stackframe size of the recursive functions low:
1326 check_source = next;
1327 check_target = prev;
1328 if (!(check_noncircular(next->class, 0)))
1329 return print_circular_bug_tail();
1331 if (!check_prev_add_irq(curr, prev, next))
1335 * For recursive read-locks we do all the dependency checks,
1336 * but we dont store read-triggered dependencies (only
1337 * write-triggered dependencies). This ensures that only the
1338 * write-side dependencies matter, and that if for example a
1339 * write-lock never takes any other locks, then the reads are
1340 * equivalent to a NOP.
1342 if (next->read == 2 || prev->read == 2)
1345 * Is the <prev> -> <next> dependency already present?
1347 * (this may occur even though this is a new chain: consider
1348 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1349 * chains - the second one will be new, but L1 already has
1350 * L2 added to its dependency list, due to the first chain.)
1352 list_for_each_entry(entry, &prev->class->locks_after, entry) {
1353 if (entry->class == next->class) {
1355 entry->distance = 1;
1361 * Ok, all validations passed, add the new lock
1362 * to the previous lock's dependency list:
1364 ret = add_lock_to_list(prev->class, next->class,
1365 &prev->class->locks_after, next->acquire_ip, distance);
1370 ret = add_lock_to_list(next->class, prev->class,
1371 &next->class->locks_before, next->acquire_ip, distance);
1376 * Debugging printouts:
1378 if (verbose(prev->class) || verbose(next->class)) {
1380 printk("\n new dependency: ");
1381 print_lock_name(prev->class);
1383 print_lock_name(next->class);
1386 return graph_lock();
1392 * Add the dependency to all directly-previous locks that are 'relevant'.
1393 * The ones that are relevant are (in increasing distance from curr):
1394 * all consecutive trylock entries and the final non-trylock entry - or
1395 * the end of this context's lock-chain - whichever comes first.
1398 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1400 int depth = curr->lockdep_depth;
1401 struct held_lock *hlock;
1406 * Depth must not be zero for a non-head lock:
1411 * At least two relevant locks must exist for this
1414 if (curr->held_locks[depth].irq_context !=
1415 curr->held_locks[depth-1].irq_context)
1419 int distance = curr->lockdep_depth - depth + 1;
1420 hlock = curr->held_locks + depth-1;
1422 * Only non-recursive-read entries get new dependencies
1425 if (hlock->read != 2) {
1426 if (!check_prev_add(curr, hlock, next, distance))
1429 * Stop after the first non-trylock entry,
1430 * as non-trylock entries have added their
1431 * own direct dependencies already, so this
1432 * lock is connected to them indirectly:
1434 if (!hlock->trylock)
1439 * End of lock-stack?
1444 * Stop the search if we cross into another context:
1446 if (curr->held_locks[depth].irq_context !=
1447 curr->held_locks[depth-1].irq_context)
1452 if (!debug_locks_off_graph_unlock())
1460 unsigned long nr_lock_chains;
1461 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1462 atomic_t nr_chain_hlocks;
1463 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1465 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1467 return lock_classes + chain_hlocks[chain->base + i];
1471 * Look up a dependency chain. If the key is not present yet then
1472 * add it and return 1 - in this case the new dependency chain is
1473 * validated. If the key is already hashed, return 0.
1474 * (On return with 1 graph_lock is held.)
1476 static inline int lookup_chain_cache(struct task_struct *curr,
1477 struct held_lock *hlock,
1480 struct lock_class *class = hlock->class;
1481 struct list_head *hash_head = chainhashentry(chain_key);
1482 struct lock_chain *chain;
1483 struct held_lock *hlock_curr, *hlock_next;
1486 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1489 * We can walk it lock-free, because entries only get added
1492 list_for_each_entry(chain, hash_head, entry) {
1493 if (chain->chain_key == chain_key) {
1495 debug_atomic_inc(&chain_lookup_hits);
1496 if (very_verbose(class))
1497 printk("\nhash chain already cached, key: "
1498 "%016Lx tail class: [%p] %s\n",
1499 (unsigned long long)chain_key,
1500 class->key, class->name);
1504 if (very_verbose(class))
1505 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1506 (unsigned long long)chain_key, class->key, class->name);
1508 * Allocate a new chain entry from the static array, and add
1514 * We have to walk the chain again locked - to avoid duplicates:
1516 list_for_each_entry(chain, hash_head, entry) {
1517 if (chain->chain_key == chain_key) {
1522 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1523 if (!debug_locks_off_graph_unlock())
1526 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1527 printk("turning off the locking correctness validator.\n");
1530 chain = lock_chains + nr_lock_chains++;
1531 chain->chain_key = chain_key;
1532 chain->irq_context = hlock->irq_context;
1533 /* Find the first held_lock of current chain */
1535 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1536 hlock_curr = curr->held_locks + i;
1537 if (hlock_curr->irq_context != hlock_next->irq_context)
1542 chain->depth = curr->lockdep_depth + 1 - i;
1543 n = atomic_add_return(chain->depth, &nr_chain_hlocks);
1544 if (unlikely(n < MAX_LOCKDEP_CHAIN_HLOCKS)) {
1545 chain->base = n - chain->depth;
1546 for (j = 0; j < chain->depth - 1; j++, i++) {
1547 int lock_id = curr->held_locks[i].class - lock_classes;
1548 chain_hlocks[chain->base + j] = lock_id;
1550 chain_hlocks[chain->base + j] = class - lock_classes;
1552 list_add_tail_rcu(&chain->entry, hash_head);
1553 debug_atomic_inc(&chain_lookup_misses);
1559 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1560 struct held_lock *hlock, int chain_head, u64 chain_key)
1563 * Trylock needs to maintain the stack of held locks, but it
1564 * does not add new dependencies, because trylock can be done
1567 * We look up the chain_key and do the O(N^2) check and update of
1568 * the dependencies only if this is a new dependency chain.
1569 * (If lookup_chain_cache() returns with 1 it acquires
1570 * graph_lock for us)
1572 if (!hlock->trylock && (hlock->check == 2) &&
1573 lookup_chain_cache(curr, hlock, chain_key)) {
1575 * Check whether last held lock:
1577 * - is irq-safe, if this lock is irq-unsafe
1578 * - is softirq-safe, if this lock is hardirq-unsafe
1580 * And check whether the new lock's dependency graph
1581 * could lead back to the previous lock.
1583 * any of these scenarios could lead to a deadlock. If
1586 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1591 * Mark recursive read, as we jump over it when
1592 * building dependencies (just like we jump over
1598 * Add dependency only if this lock is not the head
1599 * of the chain, and if it's not a secondary read-lock:
1601 if (!chain_head && ret != 2)
1602 if (!check_prevs_add(curr, hlock))
1606 /* after lookup_chain_cache(): */
1607 if (unlikely(!debug_locks))
1613 static inline int validate_chain(struct task_struct *curr,
1614 struct lockdep_map *lock, struct held_lock *hlock,
1615 int chain_head, u64 chain_key)
1622 * We are building curr_chain_key incrementally, so double-check
1623 * it from scratch, to make sure that it's done correctly:
1625 static void check_chain_key(struct task_struct *curr)
1627 #ifdef CONFIG_DEBUG_LOCKDEP
1628 struct held_lock *hlock, *prev_hlock = NULL;
1632 for (i = 0; i < curr->lockdep_depth; i++) {
1633 hlock = curr->held_locks + i;
1634 if (chain_key != hlock->prev_chain_key) {
1636 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1637 curr->lockdep_depth, i,
1638 (unsigned long long)chain_key,
1639 (unsigned long long)hlock->prev_chain_key);
1643 id = hlock->class - lock_classes;
1644 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1647 if (prev_hlock && (prev_hlock->irq_context !=
1648 hlock->irq_context))
1650 chain_key = iterate_chain_key(chain_key, id);
1653 if (chain_key != curr->curr_chain_key) {
1655 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1656 curr->lockdep_depth, i,
1657 (unsigned long long)chain_key,
1658 (unsigned long long)curr->curr_chain_key);
1665 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1666 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1668 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1671 printk("\n=================================\n");
1672 printk( "[ INFO: inconsistent lock state ]\n");
1673 print_kernel_version();
1674 printk( "---------------------------------\n");
1676 printk("inconsistent {%s} -> {%s} usage.\n",
1677 usage_str[prev_bit], usage_str[new_bit]);
1679 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1680 curr->comm, task_pid_nr(curr),
1681 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1682 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1683 trace_hardirqs_enabled(curr),
1684 trace_softirqs_enabled(curr));
1687 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1688 print_stack_trace(this->class->usage_traces + prev_bit, 1);
1690 print_irqtrace_events(curr);
1691 printk("\nother info that might help us debug this:\n");
1692 lockdep_print_held_locks(curr);
1694 printk("\nstack backtrace:\n");
1701 * Print out an error if an invalid bit is set:
1704 valid_state(struct task_struct *curr, struct held_lock *this,
1705 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1707 if (unlikely(this->class->usage_mask & (1 << bad_bit)))
1708 return print_usage_bug(curr, this, bad_bit, new_bit);
1712 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1713 enum lock_usage_bit new_bit);
1715 #ifdef CONFIG_TRACE_IRQFLAGS
1718 * print irq inversion bug:
1721 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1722 struct held_lock *this, int forwards,
1723 const char *irqclass)
1725 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1728 printk("\n=========================================================\n");
1729 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1730 print_kernel_version();
1731 printk( "---------------------------------------------------------\n");
1732 printk("%s/%d just changed the state of lock:\n",
1733 curr->comm, task_pid_nr(curr));
1736 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1738 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1739 print_lock_name(other);
1740 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1742 printk("\nother info that might help us debug this:\n");
1743 lockdep_print_held_locks(curr);
1745 printk("\nthe first lock's dependencies:\n");
1746 print_lock_dependencies(this->class, 0);
1748 printk("\nthe second lock's dependencies:\n");
1749 print_lock_dependencies(other, 0);
1751 printk("\nstack backtrace:\n");
1758 * Prove that in the forwards-direction subgraph starting at <this>
1759 * there is no lock matching <mask>:
1762 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1763 enum lock_usage_bit bit, const char *irqclass)
1767 find_usage_bit = bit;
1768 /* fills in <forwards_match> */
1769 ret = find_usage_forwards(this->class, 0);
1770 if (!ret || ret == 1)
1773 return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1777 * Prove that in the backwards-direction subgraph starting at <this>
1778 * there is no lock matching <mask>:
1781 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1782 enum lock_usage_bit bit, const char *irqclass)
1786 find_usage_bit = bit;
1787 /* fills in <backwards_match> */
1788 ret = find_usage_backwards(this->class, 0);
1789 if (!ret || ret == 1)
1792 return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1795 void print_irqtrace_events(struct task_struct *curr)
1797 printk("irq event stamp: %u\n", curr->irq_events);
1798 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
1799 print_ip_sym(curr->hardirq_enable_ip);
1800 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1801 print_ip_sym(curr->hardirq_disable_ip);
1802 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
1803 print_ip_sym(curr->softirq_enable_ip);
1804 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1805 print_ip_sym(curr->softirq_disable_ip);
1808 static int hardirq_verbose(struct lock_class *class)
1811 return class_filter(class);
1816 static int softirq_verbose(struct lock_class *class)
1819 return class_filter(class);
1824 #define STRICT_READ_CHECKS 1
1826 static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
1827 enum lock_usage_bit new_bit)
1832 case LOCK_USED_IN_HARDIRQ:
1833 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1835 if (!valid_state(curr, this, new_bit,
1836 LOCK_ENABLED_HARDIRQS_READ))
1839 * just marked it hardirq-safe, check that this lock
1840 * took no hardirq-unsafe lock in the past:
1842 if (!check_usage_forwards(curr, this,
1843 LOCK_ENABLED_HARDIRQS, "hard"))
1845 #if STRICT_READ_CHECKS
1847 * just marked it hardirq-safe, check that this lock
1848 * took no hardirq-unsafe-read lock in the past:
1850 if (!check_usage_forwards(curr, this,
1851 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1854 if (hardirq_verbose(this->class))
1857 case LOCK_USED_IN_SOFTIRQ:
1858 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1860 if (!valid_state(curr, this, new_bit,
1861 LOCK_ENABLED_SOFTIRQS_READ))
1864 * just marked it softirq-safe, check that this lock
1865 * took no softirq-unsafe lock in the past:
1867 if (!check_usage_forwards(curr, this,
1868 LOCK_ENABLED_SOFTIRQS, "soft"))
1870 #if STRICT_READ_CHECKS
1872 * just marked it softirq-safe, check that this lock
1873 * took no softirq-unsafe-read lock in the past:
1875 if (!check_usage_forwards(curr, this,
1876 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
1879 if (softirq_verbose(this->class))
1882 case LOCK_USED_IN_HARDIRQ_READ:
1883 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1886 * just marked it hardirq-read-safe, check that this lock
1887 * took no hardirq-unsafe lock in the past:
1889 if (!check_usage_forwards(curr, this,
1890 LOCK_ENABLED_HARDIRQS, "hard"))
1892 if (hardirq_verbose(this->class))
1895 case LOCK_USED_IN_SOFTIRQ_READ:
1896 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1899 * just marked it softirq-read-safe, check that this lock
1900 * took no softirq-unsafe lock in the past:
1902 if (!check_usage_forwards(curr, this,
1903 LOCK_ENABLED_SOFTIRQS, "soft"))
1905 if (softirq_verbose(this->class))
1908 case LOCK_ENABLED_HARDIRQS:
1909 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1911 if (!valid_state(curr, this, new_bit,
1912 LOCK_USED_IN_HARDIRQ_READ))
1915 * just marked it hardirq-unsafe, check that no hardirq-safe
1916 * lock in the system ever took it in the past:
1918 if (!check_usage_backwards(curr, this,
1919 LOCK_USED_IN_HARDIRQ, "hard"))
1921 #if STRICT_READ_CHECKS
1923 * just marked it hardirq-unsafe, check that no
1924 * hardirq-safe-read lock in the system ever took
1927 if (!check_usage_backwards(curr, this,
1928 LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
1931 if (hardirq_verbose(this->class))
1934 case LOCK_ENABLED_SOFTIRQS:
1935 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1937 if (!valid_state(curr, this, new_bit,
1938 LOCK_USED_IN_SOFTIRQ_READ))
1941 * just marked it softirq-unsafe, check that no softirq-safe
1942 * lock in the system ever took it in the past:
1944 if (!check_usage_backwards(curr, this,
1945 LOCK_USED_IN_SOFTIRQ, "soft"))
1947 #if STRICT_READ_CHECKS
1949 * just marked it softirq-unsafe, check that no
1950 * softirq-safe-read lock in the system ever took
1953 if (!check_usage_backwards(curr, this,
1954 LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
1957 if (softirq_verbose(this->class))
1960 case LOCK_ENABLED_HARDIRQS_READ:
1961 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1963 #if STRICT_READ_CHECKS
1965 * just marked it hardirq-read-unsafe, check that no
1966 * hardirq-safe lock in the system ever took it in the past:
1968 if (!check_usage_backwards(curr, this,
1969 LOCK_USED_IN_HARDIRQ, "hard"))
1972 if (hardirq_verbose(this->class))
1975 case LOCK_ENABLED_SOFTIRQS_READ:
1976 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1978 #if STRICT_READ_CHECKS
1980 * just marked it softirq-read-unsafe, check that no
1981 * softirq-safe lock in the system ever took it in the past:
1983 if (!check_usage_backwards(curr, this,
1984 LOCK_USED_IN_SOFTIRQ, "soft"))
1987 if (softirq_verbose(this->class))
1999 * Mark all held locks with a usage bit:
2002 mark_held_locks(struct task_struct *curr, int hardirq)
2004 enum lock_usage_bit usage_bit;
2005 struct held_lock *hlock;
2008 for (i = 0; i < curr->lockdep_depth; i++) {
2009 hlock = curr->held_locks + i;
2013 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
2015 usage_bit = LOCK_ENABLED_HARDIRQS;
2018 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
2020 usage_bit = LOCK_ENABLED_SOFTIRQS;
2022 if (!mark_lock(curr, hlock, usage_bit))
2030 * Debugging helper: via this flag we know that we are in
2031 * 'early bootup code', and will warn about any invalid irqs-on event:
2033 static int early_boot_irqs_enabled;
2035 void early_boot_irqs_off(void)
2037 early_boot_irqs_enabled = 0;
2040 void early_boot_irqs_on(void)
2042 early_boot_irqs_enabled = 1;
2046 * Hardirqs will be enabled:
2048 void trace_hardirqs_on(void)
2050 struct task_struct *curr = current;
2053 if (unlikely(!debug_locks || current->lockdep_recursion))
2056 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2059 if (unlikely(curr->hardirqs_enabled)) {
2060 debug_atomic_inc(&redundant_hardirqs_on);
2063 /* we'll do an OFF -> ON transition: */
2064 curr->hardirqs_enabled = 1;
2065 ip = (unsigned long) __builtin_return_address(0);
2067 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2069 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2072 * We are going to turn hardirqs on, so set the
2073 * usage bit for all held locks:
2075 if (!mark_held_locks(curr, 1))
2078 * If we have softirqs enabled, then set the usage
2079 * bit for all held locks. (disabled hardirqs prevented
2080 * this bit from being set before)
2082 if (curr->softirqs_enabled)
2083 if (!mark_held_locks(curr, 0))
2086 curr->hardirq_enable_ip = ip;
2087 curr->hardirq_enable_event = ++curr->irq_events;
2088 debug_atomic_inc(&hardirqs_on_events);
2091 EXPORT_SYMBOL(trace_hardirqs_on);
2094 * Hardirqs were disabled:
2096 void trace_hardirqs_off(void)
2098 struct task_struct *curr = current;
2100 if (unlikely(!debug_locks || current->lockdep_recursion))
2103 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2106 if (curr->hardirqs_enabled) {
2108 * We have done an ON -> OFF transition:
2110 curr->hardirqs_enabled = 0;
2111 curr->hardirq_disable_ip = _RET_IP_;
2112 curr->hardirq_disable_event = ++curr->irq_events;
2113 debug_atomic_inc(&hardirqs_off_events);
2115 debug_atomic_inc(&redundant_hardirqs_off);
2118 EXPORT_SYMBOL(trace_hardirqs_off);
2121 * Softirqs will be enabled:
2123 void trace_softirqs_on(unsigned long ip)
2125 struct task_struct *curr = current;
2127 if (unlikely(!debug_locks))
2130 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2133 if (curr->softirqs_enabled) {
2134 debug_atomic_inc(&redundant_softirqs_on);
2139 * We'll do an OFF -> ON transition:
2141 curr->softirqs_enabled = 1;
2142 curr->softirq_enable_ip = ip;
2143 curr->softirq_enable_event = ++curr->irq_events;
2144 debug_atomic_inc(&softirqs_on_events);
2146 * We are going to turn softirqs on, so set the
2147 * usage bit for all held locks, if hardirqs are
2150 if (curr->hardirqs_enabled)
2151 mark_held_locks(curr, 0);
2155 * Softirqs were disabled:
2157 void trace_softirqs_off(unsigned long ip)
2159 struct task_struct *curr = current;
2161 if (unlikely(!debug_locks))
2164 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2167 if (curr->softirqs_enabled) {
2169 * We have done an ON -> OFF transition:
2171 curr->softirqs_enabled = 0;
2172 curr->softirq_disable_ip = ip;
2173 curr->softirq_disable_event = ++curr->irq_events;
2174 debug_atomic_inc(&softirqs_off_events);
2175 DEBUG_LOCKS_WARN_ON(!softirq_count());
2177 debug_atomic_inc(&redundant_softirqs_off);
2180 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2183 * If non-trylock use in a hardirq or softirq context, then
2184 * mark the lock as used in these contexts:
2186 if (!hlock->trylock) {
2188 if (curr->hardirq_context)
2189 if (!mark_lock(curr, hlock,
2190 LOCK_USED_IN_HARDIRQ_READ))
2192 if (curr->softirq_context)
2193 if (!mark_lock(curr, hlock,
2194 LOCK_USED_IN_SOFTIRQ_READ))
2197 if (curr->hardirq_context)
2198 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2200 if (curr->softirq_context)
2201 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2205 if (!hlock->hardirqs_off) {
2207 if (!mark_lock(curr, hlock,
2208 LOCK_ENABLED_HARDIRQS_READ))
2210 if (curr->softirqs_enabled)
2211 if (!mark_lock(curr, hlock,
2212 LOCK_ENABLED_SOFTIRQS_READ))
2215 if (!mark_lock(curr, hlock,
2216 LOCK_ENABLED_HARDIRQS))
2218 if (curr->softirqs_enabled)
2219 if (!mark_lock(curr, hlock,
2220 LOCK_ENABLED_SOFTIRQS))
2228 static int separate_irq_context(struct task_struct *curr,
2229 struct held_lock *hlock)
2231 unsigned int depth = curr->lockdep_depth;
2234 * Keep track of points where we cross into an interrupt context:
2236 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2237 curr->softirq_context;
2239 struct held_lock *prev_hlock;
2241 prev_hlock = curr->held_locks + depth-1;
2243 * If we cross into another context, reset the
2244 * hash key (this also prevents the checking and the
2245 * adding of the dependency to 'prev'):
2247 if (prev_hlock->irq_context != hlock->irq_context)
2256 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2257 enum lock_usage_bit new_bit)
2263 static inline int mark_irqflags(struct task_struct *curr,
2264 struct held_lock *hlock)
2269 static inline int separate_irq_context(struct task_struct *curr,
2270 struct held_lock *hlock)
2278 * Mark a lock with a usage bit, and validate the state transition:
2280 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2281 enum lock_usage_bit new_bit)
2283 unsigned int new_mask = 1 << new_bit, ret = 1;
2286 * If already set then do not dirty the cacheline,
2287 * nor do any checks:
2289 if (likely(this->class->usage_mask & new_mask))
2295 * Make sure we didnt race:
2297 if (unlikely(this->class->usage_mask & new_mask)) {
2302 this->class->usage_mask |= new_mask;
2304 if (!save_trace(this->class->usage_traces + new_bit))
2308 case LOCK_USED_IN_HARDIRQ:
2309 case LOCK_USED_IN_SOFTIRQ:
2310 case LOCK_USED_IN_HARDIRQ_READ:
2311 case LOCK_USED_IN_SOFTIRQ_READ:
2312 case LOCK_ENABLED_HARDIRQS:
2313 case LOCK_ENABLED_SOFTIRQS:
2314 case LOCK_ENABLED_HARDIRQS_READ:
2315 case LOCK_ENABLED_SOFTIRQS_READ:
2316 ret = mark_lock_irq(curr, this, new_bit);
2321 debug_atomic_dec(&nr_unused_locks);
2324 if (!debug_locks_off_graph_unlock())
2333 * We must printk outside of the graph_lock:
2336 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2338 print_irqtrace_events(curr);
2346 * Initialize a lock instance's lock-class mapping info:
2348 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2349 struct lock_class_key *key, int subclass)
2351 if (unlikely(!debug_locks))
2354 if (DEBUG_LOCKS_WARN_ON(!key))
2356 if (DEBUG_LOCKS_WARN_ON(!name))
2359 * Sanity check, the lock-class key must be persistent:
2361 if (!static_obj(key)) {
2362 printk("BUG: key %p not in .data!\n", key);
2363 DEBUG_LOCKS_WARN_ON(1);
2368 lock->class_cache = NULL;
2369 #ifdef CONFIG_LOCK_STAT
2370 lock->cpu = raw_smp_processor_id();
2373 register_lock_class(lock, subclass, 1);
2376 EXPORT_SYMBOL_GPL(lockdep_init_map);
2379 * This gets called for every mutex_lock*()/spin_lock*() operation.
2380 * We maintain the dependency maps and validate the locking attempt:
2382 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2383 int trylock, int read, int check, int hardirqs_off,
2386 struct task_struct *curr = current;
2387 struct lock_class *class = NULL;
2388 struct held_lock *hlock;
2389 unsigned int depth, id;
2396 if (unlikely(!debug_locks))
2399 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2402 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2404 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2405 printk("turning off the locking correctness validator.\n");
2410 class = lock->class_cache;
2412 * Not cached yet or subclass?
2414 if (unlikely(!class)) {
2415 class = register_lock_class(lock, subclass, 0);
2419 debug_atomic_inc((atomic_t *)&class->ops);
2420 if (very_verbose(class)) {
2421 printk("\nacquire class [%p] %s", class->key, class->name);
2422 if (class->name_version > 1)
2423 printk("#%d", class->name_version);
2429 * Add the lock to the list of currently held locks.
2430 * (we dont increase the depth just yet, up until the
2431 * dependency checks are done)
2433 depth = curr->lockdep_depth;
2434 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2437 hlock = curr->held_locks + depth;
2439 hlock->class = class;
2440 hlock->acquire_ip = ip;
2441 hlock->instance = lock;
2442 hlock->trylock = trylock;
2444 hlock->check = check;
2445 hlock->hardirqs_off = hardirqs_off;
2446 #ifdef CONFIG_LOCK_STAT
2447 hlock->waittime_stamp = 0;
2448 hlock->holdtime_stamp = sched_clock();
2451 if (check == 2 && !mark_irqflags(curr, hlock))
2454 /* mark it as used: */
2455 if (!mark_lock(curr, hlock, LOCK_USED))
2459 * Calculate the chain hash: it's the combined hash of all the
2460 * lock keys along the dependency chain. We save the hash value
2461 * at every step so that we can get the current hash easily
2462 * after unlock. The chain hash is then used to cache dependency
2465 * The 'key ID' is what is the most compact key value to drive
2466 * the hash, not class->key.
2468 id = class - lock_classes;
2469 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2472 chain_key = curr->curr_chain_key;
2474 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2479 hlock->prev_chain_key = chain_key;
2480 if (separate_irq_context(curr, hlock)) {
2484 chain_key = iterate_chain_key(chain_key, id);
2486 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2489 curr->curr_chain_key = chain_key;
2490 curr->lockdep_depth++;
2491 check_chain_key(curr);
2492 #ifdef CONFIG_DEBUG_LOCKDEP
2493 if (unlikely(!debug_locks))
2496 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2498 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2499 printk("turning off the locking correctness validator.\n");
2503 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2504 max_lockdep_depth = curr->lockdep_depth;
2510 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2513 if (!debug_locks_off())
2515 if (debug_locks_silent)
2518 printk("\n=====================================\n");
2519 printk( "[ BUG: bad unlock balance detected! ]\n");
2520 printk( "-------------------------------------\n");
2521 printk("%s/%d is trying to release lock (",
2522 curr->comm, task_pid_nr(curr));
2523 print_lockdep_cache(lock);
2526 printk("but there are no more locks to release!\n");
2527 printk("\nother info that might help us debug this:\n");
2528 lockdep_print_held_locks(curr);
2530 printk("\nstack backtrace:\n");
2537 * Common debugging checks for both nested and non-nested unlock:
2539 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2542 if (unlikely(!debug_locks))
2544 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2547 if (curr->lockdep_depth <= 0)
2548 return print_unlock_inbalance_bug(curr, lock, ip);
2554 * Remove the lock to the list of currently held locks in a
2555 * potentially non-nested (out of order) manner. This is a
2556 * relatively rare operation, as all the unlock APIs default
2557 * to nested mode (which uses lock_release()):
2560 lock_release_non_nested(struct task_struct *curr,
2561 struct lockdep_map *lock, unsigned long ip)
2563 struct held_lock *hlock, *prev_hlock;
2568 * Check whether the lock exists in the current stack
2571 depth = curr->lockdep_depth;
2572 if (DEBUG_LOCKS_WARN_ON(!depth))
2576 for (i = depth-1; i >= 0; i--) {
2577 hlock = curr->held_locks + i;
2579 * We must not cross into another context:
2581 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2583 if (hlock->instance == lock)
2587 return print_unlock_inbalance_bug(curr, lock, ip);
2590 lock_release_holdtime(hlock);
2593 * We have the right lock to unlock, 'hlock' points to it.
2594 * Now we remove it from the stack, and add back the other
2595 * entries (if any), recalculating the hash along the way:
2597 curr->lockdep_depth = i;
2598 curr->curr_chain_key = hlock->prev_chain_key;
2600 for (i++; i < depth; i++) {
2601 hlock = curr->held_locks + i;
2602 if (!__lock_acquire(hlock->instance,
2603 hlock->class->subclass, hlock->trylock,
2604 hlock->read, hlock->check, hlock->hardirqs_off,
2609 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2615 * Remove the lock to the list of currently held locks - this gets
2616 * called on mutex_unlock()/spin_unlock*() (or on a failed
2617 * mutex_lock_interruptible()). This is done for unlocks that nest
2618 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2620 static int lock_release_nested(struct task_struct *curr,
2621 struct lockdep_map *lock, unsigned long ip)
2623 struct held_lock *hlock;
2627 * Pop off the top of the lock stack:
2629 depth = curr->lockdep_depth - 1;
2630 hlock = curr->held_locks + depth;
2633 * Is the unlock non-nested:
2635 if (hlock->instance != lock)
2636 return lock_release_non_nested(curr, lock, ip);
2637 curr->lockdep_depth--;
2639 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2642 curr->curr_chain_key = hlock->prev_chain_key;
2644 lock_release_holdtime(hlock);
2646 #ifdef CONFIG_DEBUG_LOCKDEP
2647 hlock->prev_chain_key = 0;
2648 hlock->class = NULL;
2649 hlock->acquire_ip = 0;
2650 hlock->irq_context = 0;
2656 * Remove the lock to the list of currently held locks - this gets
2657 * called on mutex_unlock()/spin_unlock*() (or on a failed
2658 * mutex_lock_interruptible()). This is done for unlocks that nest
2659 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2662 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2664 struct task_struct *curr = current;
2666 if (!check_unlock(curr, lock, ip))
2670 if (!lock_release_nested(curr, lock, ip))
2673 if (!lock_release_non_nested(curr, lock, ip))
2677 check_chain_key(curr);
2681 * Check whether we follow the irq-flags state precisely:
2683 static void check_flags(unsigned long flags)
2685 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2689 if (irqs_disabled_flags(flags)) {
2690 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
2691 printk("possible reason: unannotated irqs-off.\n");
2694 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
2695 printk("possible reason: unannotated irqs-on.\n");
2700 * We dont accurately track softirq state in e.g.
2701 * hardirq contexts (such as on 4KSTACKS), so only
2702 * check if not in hardirq contexts:
2704 if (!hardirq_count()) {
2705 if (softirq_count())
2706 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2708 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2712 print_irqtrace_events(current);
2717 * We are not always called with irqs disabled - do that here,
2718 * and also avoid lockdep recursion:
2720 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2721 int trylock, int read, int check, unsigned long ip)
2723 unsigned long flags;
2725 if (unlikely(!lock_stat && !prove_locking))
2728 if (unlikely(current->lockdep_recursion))
2731 raw_local_irq_save(flags);
2734 current->lockdep_recursion = 1;
2735 __lock_acquire(lock, subclass, trylock, read, check,
2736 irqs_disabled_flags(flags), ip);
2737 current->lockdep_recursion = 0;
2738 raw_local_irq_restore(flags);
2741 EXPORT_SYMBOL_GPL(lock_acquire);
2743 void lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2745 unsigned long flags;
2747 if (unlikely(!lock_stat && !prove_locking))
2750 if (unlikely(current->lockdep_recursion))
2753 raw_local_irq_save(flags);
2755 current->lockdep_recursion = 1;
2756 __lock_release(lock, nested, ip);
2757 current->lockdep_recursion = 0;
2758 raw_local_irq_restore(flags);
2761 EXPORT_SYMBOL_GPL(lock_release);
2763 #ifdef CONFIG_LOCK_STAT
2765 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
2768 if (!debug_locks_off())
2770 if (debug_locks_silent)
2773 printk("\n=================================\n");
2774 printk( "[ BUG: bad contention detected! ]\n");
2775 printk( "---------------------------------\n");
2776 printk("%s/%d is trying to contend lock (",
2777 curr->comm, task_pid_nr(curr));
2778 print_lockdep_cache(lock);
2781 printk("but there are no locks held!\n");
2782 printk("\nother info that might help us debug this:\n");
2783 lockdep_print_held_locks(curr);
2785 printk("\nstack backtrace:\n");
2792 __lock_contended(struct lockdep_map *lock, unsigned long ip)
2794 struct task_struct *curr = current;
2795 struct held_lock *hlock, *prev_hlock;
2796 struct lock_class_stats *stats;
2800 depth = curr->lockdep_depth;
2801 if (DEBUG_LOCKS_WARN_ON(!depth))
2805 for (i = depth-1; i >= 0; i--) {
2806 hlock = curr->held_locks + i;
2808 * We must not cross into another context:
2810 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2812 if (hlock->instance == lock)
2816 print_lock_contention_bug(curr, lock, ip);
2820 hlock->waittime_stamp = sched_clock();
2822 point = lock_contention_point(hlock->class, ip);
2824 stats = get_lock_stats(hlock->class);
2825 if (point < ARRAY_SIZE(stats->contention_point))
2826 stats->contention_point[i]++;
2827 if (lock->cpu != smp_processor_id())
2828 stats->bounces[bounce_contended + !!hlock->read]++;
2829 put_lock_stats(stats);
2833 __lock_acquired(struct lockdep_map *lock)
2835 struct task_struct *curr = current;
2836 struct held_lock *hlock, *prev_hlock;
2837 struct lock_class_stats *stats;
2843 depth = curr->lockdep_depth;
2844 if (DEBUG_LOCKS_WARN_ON(!depth))
2848 for (i = depth-1; i >= 0; i--) {
2849 hlock = curr->held_locks + i;
2851 * We must not cross into another context:
2853 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2855 if (hlock->instance == lock)
2859 print_lock_contention_bug(curr, lock, _RET_IP_);
2863 cpu = smp_processor_id();
2864 if (hlock->waittime_stamp) {
2865 now = sched_clock();
2866 waittime = now - hlock->waittime_stamp;
2867 hlock->holdtime_stamp = now;
2870 stats = get_lock_stats(hlock->class);
2873 lock_time_inc(&stats->read_waittime, waittime);
2875 lock_time_inc(&stats->write_waittime, waittime);
2877 if (lock->cpu != cpu)
2878 stats->bounces[bounce_acquired + !!hlock->read]++;
2879 put_lock_stats(stats);
2884 void lock_contended(struct lockdep_map *lock, unsigned long ip)
2886 unsigned long flags;
2888 if (unlikely(!lock_stat))
2891 if (unlikely(current->lockdep_recursion))
2894 raw_local_irq_save(flags);
2896 current->lockdep_recursion = 1;
2897 __lock_contended(lock, ip);
2898 current->lockdep_recursion = 0;
2899 raw_local_irq_restore(flags);
2901 EXPORT_SYMBOL_GPL(lock_contended);
2903 void lock_acquired(struct lockdep_map *lock)
2905 unsigned long flags;
2907 if (unlikely(!lock_stat))
2910 if (unlikely(current->lockdep_recursion))
2913 raw_local_irq_save(flags);
2915 current->lockdep_recursion = 1;
2916 __lock_acquired(lock);
2917 current->lockdep_recursion = 0;
2918 raw_local_irq_restore(flags);
2920 EXPORT_SYMBOL_GPL(lock_acquired);
2924 * Used by the testsuite, sanitize the validator state
2925 * after a simulated failure:
2928 void lockdep_reset(void)
2930 unsigned long flags;
2933 raw_local_irq_save(flags);
2934 current->curr_chain_key = 0;
2935 current->lockdep_depth = 0;
2936 current->lockdep_recursion = 0;
2937 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
2938 nr_hardirq_chains = 0;
2939 nr_softirq_chains = 0;
2940 nr_process_chains = 0;
2942 for (i = 0; i < CHAINHASH_SIZE; i++)
2943 INIT_LIST_HEAD(chainhash_table + i);
2944 raw_local_irq_restore(flags);
2947 static void zap_class(struct lock_class *class)
2952 * Remove all dependencies this lock is
2955 for (i = 0; i < nr_list_entries; i++) {
2956 if (list_entries[i].class == class)
2957 list_del_rcu(&list_entries[i].entry);
2960 * Unhash the class and remove it from the all_lock_classes list:
2962 list_del_rcu(&class->hash_entry);
2963 list_del_rcu(&class->lock_entry);
2967 static inline int within(const void *addr, void *start, unsigned long size)
2969 return addr >= start && addr < start + size;
2972 void lockdep_free_key_range(void *start, unsigned long size)
2974 struct lock_class *class, *next;
2975 struct list_head *head;
2976 unsigned long flags;
2980 raw_local_irq_save(flags);
2981 locked = graph_lock();
2984 * Unhash all classes that were created by this module:
2986 for (i = 0; i < CLASSHASH_SIZE; i++) {
2987 head = classhash_table + i;
2988 if (list_empty(head))
2990 list_for_each_entry_safe(class, next, head, hash_entry) {
2991 if (within(class->key, start, size))
2993 else if (within(class->name, start, size))
3000 raw_local_irq_restore(flags);
3003 void lockdep_reset_lock(struct lockdep_map *lock)
3005 struct lock_class *class, *next;
3006 struct list_head *head;
3007 unsigned long flags;
3011 raw_local_irq_save(flags);
3014 * Remove all classes this lock might have:
3016 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3018 * If the class exists we look it up and zap it:
3020 class = look_up_lock_class(lock, j);
3025 * Debug check: in the end all mapped classes should
3028 locked = graph_lock();
3029 for (i = 0; i < CLASSHASH_SIZE; i++) {
3030 head = classhash_table + i;
3031 if (list_empty(head))
3033 list_for_each_entry_safe(class, next, head, hash_entry) {
3034 if (unlikely(class == lock->class_cache)) {
3035 if (debug_locks_off_graph_unlock())
3045 raw_local_irq_restore(flags);
3048 void lockdep_init(void)
3053 * Some architectures have their own start_kernel()
3054 * code which calls lockdep_init(), while we also
3055 * call lockdep_init() from the start_kernel() itself,
3056 * and we want to initialize the hashes only once:
3058 if (lockdep_initialized)
3061 for (i = 0; i < CLASSHASH_SIZE; i++)
3062 INIT_LIST_HEAD(classhash_table + i);
3064 for (i = 0; i < CHAINHASH_SIZE; i++)
3065 INIT_LIST_HEAD(chainhash_table + i);
3067 lockdep_initialized = 1;
3070 void __init lockdep_info(void)
3072 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3074 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3075 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3076 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3077 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3078 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3079 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3080 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3082 printk(" memory used by lock dependency info: %lu kB\n",
3083 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3084 sizeof(struct list_head) * CLASSHASH_SIZE +
3085 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3086 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3087 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
3089 printk(" per task-struct memory footprint: %lu bytes\n",
3090 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3092 #ifdef CONFIG_DEBUG_LOCKDEP
3093 if (lockdep_init_error) {
3094 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3095 printk("Call stack leading to lockdep invocation was:\n");
3096 print_stack_trace(&lockdep_init_trace, 0);
3102 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3103 const void *mem_to, struct held_lock *hlock)
3105 if (!debug_locks_off())
3107 if (debug_locks_silent)
3110 printk("\n=========================\n");
3111 printk( "[ BUG: held lock freed! ]\n");
3112 printk( "-------------------------\n");
3113 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3114 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3116 lockdep_print_held_locks(curr);
3118 printk("\nstack backtrace:\n");
3122 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3123 const void* lock_from, unsigned long lock_len)
3125 return lock_from + lock_len <= mem_from ||
3126 mem_from + mem_len <= lock_from;
3130 * Called when kernel memory is freed (or unmapped), or if a lock
3131 * is destroyed or reinitialized - this code checks whether there is
3132 * any held lock in the memory range of <from> to <to>:
3134 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3136 struct task_struct *curr = current;
3137 struct held_lock *hlock;
3138 unsigned long flags;
3141 if (unlikely(!debug_locks))
3144 local_irq_save(flags);
3145 for (i = 0; i < curr->lockdep_depth; i++) {
3146 hlock = curr->held_locks + i;
3148 if (not_in_range(mem_from, mem_len, hlock->instance,
3149 sizeof(*hlock->instance)))
3152 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3155 local_irq_restore(flags);
3157 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3159 static void print_held_locks_bug(struct task_struct *curr)
3161 if (!debug_locks_off())
3163 if (debug_locks_silent)
3166 printk("\n=====================================\n");
3167 printk( "[ BUG: lock held at task exit time! ]\n");
3168 printk( "-------------------------------------\n");
3169 printk("%s/%d is exiting with locks still held!\n",
3170 curr->comm, task_pid_nr(curr));
3171 lockdep_print_held_locks(curr);
3173 printk("\nstack backtrace:\n");
3177 void debug_check_no_locks_held(struct task_struct *task)
3179 if (unlikely(task->lockdep_depth > 0))
3180 print_held_locks_bug(task);
3183 void debug_show_all_locks(void)
3185 struct task_struct *g, *p;
3189 if (unlikely(!debug_locks)) {
3190 printk("INFO: lockdep is turned off.\n");
3193 printk("\nShowing all locks held in the system:\n");
3196 * Here we try to get the tasklist_lock as hard as possible,
3197 * if not successful after 2 seconds we ignore it (but keep
3198 * trying). This is to enable a debug printout even if a
3199 * tasklist_lock-holding task deadlocks or crashes.
3202 if (!read_trylock(&tasklist_lock)) {
3204 printk("hm, tasklist_lock locked, retrying... ");
3207 printk(" #%d", 10-count);
3211 printk(" ignoring it.\n");
3215 printk(" locked it.\n");
3217 do_each_thread(g, p) {
3219 * It's not reliable to print a task's held locks
3220 * if it's not sleeping (or if it's not the current
3223 if (p->state == TASK_RUNNING && p != current)
3225 if (p->lockdep_depth)
3226 lockdep_print_held_locks(p);
3228 if (read_trylock(&tasklist_lock))
3230 } while_each_thread(g, p);
3233 printk("=============================================\n\n");
3236 read_unlock(&tasklist_lock);
3239 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3242 * Careful: only use this function if you are sure that
3243 * the task cannot run in parallel!
3245 void __debug_show_held_locks(struct task_struct *task)
3247 if (unlikely(!debug_locks)) {
3248 printk("INFO: lockdep is turned off.\n");
3251 lockdep_print_held_locks(task);
3253 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3255 void debug_show_held_locks(struct task_struct *task)
3257 __debug_show_held_locks(task);
3260 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3262 void lockdep_sys_exit(void)
3264 struct task_struct *curr = current;
3266 if (unlikely(curr->lockdep_depth)) {
3267 if (!debug_locks_off())
3269 printk("\n================================================\n");
3270 printk( "[ BUG: lock held when returning to user space! ]\n");
3271 printk( "------------------------------------------------\n");
3272 printk("%s/%d is leaving the kernel with locks still held!\n",
3273 curr->comm, curr->pid);
3274 lockdep_print_held_locks(curr);