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;
380 * Various lockdep statistics:
382 atomic_t chain_lookup_hits;
383 atomic_t chain_lookup_misses;
384 atomic_t hardirqs_on_events;
385 atomic_t hardirqs_off_events;
386 atomic_t redundant_hardirqs_on;
387 atomic_t redundant_hardirqs_off;
388 atomic_t softirqs_on_events;
389 atomic_t softirqs_off_events;
390 atomic_t redundant_softirqs_on;
391 atomic_t redundant_softirqs_off;
392 atomic_t nr_unused_locks;
393 atomic_t nr_cyclic_checks;
394 atomic_t nr_cyclic_check_recursions;
395 atomic_t nr_find_usage_forwards_checks;
396 atomic_t nr_find_usage_forwards_recursions;
397 atomic_t nr_find_usage_backwards_checks;
398 atomic_t nr_find_usage_backwards_recursions;
399 # define debug_atomic_inc(ptr) atomic_inc(ptr)
400 # define debug_atomic_dec(ptr) atomic_dec(ptr)
401 # define debug_atomic_read(ptr) atomic_read(ptr)
403 # define debug_atomic_inc(ptr) do { } while (0)
404 # define debug_atomic_dec(ptr) do { } while (0)
405 # define debug_atomic_read(ptr) 0
412 static const char *usage_str[] =
414 [LOCK_USED] = "initial-use ",
415 [LOCK_USED_IN_HARDIRQ] = "in-hardirq-W",
416 [LOCK_USED_IN_SOFTIRQ] = "in-softirq-W",
417 [LOCK_ENABLED_SOFTIRQS] = "softirq-on-W",
418 [LOCK_ENABLED_HARDIRQS] = "hardirq-on-W",
419 [LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R",
420 [LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R",
421 [LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R",
422 [LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R",
425 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
427 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
431 get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
433 *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
435 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
438 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
441 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
444 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
447 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
449 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
451 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
455 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
457 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
459 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
464 static void print_lock_name(struct lock_class *class)
466 char str[KSYM_NAME_LEN], c1, c2, c3, c4;
469 get_usage_chars(class, &c1, &c2, &c3, &c4);
473 name = __get_key_name(class->key, str);
474 printk(" (%s", name);
476 printk(" (%s", name);
477 if (class->name_version > 1)
478 printk("#%d", class->name_version);
480 printk("/%d", class->subclass);
482 printk("){%c%c%c%c}", c1, c2, c3, c4);
485 static void print_lockdep_cache(struct lockdep_map *lock)
488 char str[KSYM_NAME_LEN];
492 name = __get_key_name(lock->key->subkeys, str);
497 static void print_lock(struct held_lock *hlock)
499 print_lock_name(hlock->class);
501 print_ip_sym(hlock->acquire_ip);
504 static void lockdep_print_held_locks(struct task_struct *curr)
506 int i, depth = curr->lockdep_depth;
509 printk("no locks held by %s/%d.\n", curr->comm, curr->pid);
512 printk("%d lock%s held by %s/%d:\n",
513 depth, depth > 1 ? "s" : "", curr->comm, curr->pid);
515 for (i = 0; i < depth; i++) {
517 print_lock(curr->held_locks + i);
521 static void print_lock_class_header(struct lock_class *class, int depth)
525 printk("%*s->", depth, "");
526 print_lock_name(class);
527 printk(" ops: %lu", class->ops);
530 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
531 if (class->usage_mask & (1 << bit)) {
534 len += printk("%*s %s", depth, "", usage_str[bit]);
535 len += printk(" at:\n");
536 print_stack_trace(class->usage_traces + bit, len);
539 printk("%*s }\n", depth, "");
541 printk("%*s ... key at: ",depth,"");
542 print_ip_sym((unsigned long)class->key);
546 * printk all lock dependencies starting at <entry>:
548 static void print_lock_dependencies(struct lock_class *class, int depth)
550 struct lock_list *entry;
552 if (DEBUG_LOCKS_WARN_ON(depth >= 20))
555 print_lock_class_header(class, depth);
557 list_for_each_entry(entry, &class->locks_after, entry) {
558 if (DEBUG_LOCKS_WARN_ON(!entry->class))
561 print_lock_dependencies(entry->class, depth + 1);
563 printk("%*s ... acquired at:\n",depth,"");
564 print_stack_trace(&entry->trace, 2);
569 static void print_kernel_version(void)
571 printk("%s %.*s\n", init_utsname()->release,
572 (int)strcspn(init_utsname()->version, " "),
573 init_utsname()->version);
576 static int very_verbose(struct lock_class *class)
579 return class_filter(class);
585 * Is this the address of a static object:
587 static int static_obj(void *obj)
589 unsigned long start = (unsigned long) &_stext,
590 end = (unsigned long) &_end,
591 addr = (unsigned long) obj;
599 if ((addr >= start) && (addr < end))
606 for_each_possible_cpu(i) {
607 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
608 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
611 if ((addr >= start) && (addr < end))
619 return is_module_address(addr);
623 * To make lock name printouts unique, we calculate a unique
624 * class->name_version generation counter:
626 static int count_matching_names(struct lock_class *new_class)
628 struct lock_class *class;
631 if (!new_class->name)
634 list_for_each_entry(class, &all_lock_classes, lock_entry) {
635 if (new_class->key - new_class->subclass == class->key)
636 return class->name_version;
637 if (class->name && !strcmp(class->name, new_class->name))
638 count = max(count, class->name_version);
645 * Register a lock's class in the hash-table, if the class is not present
646 * yet. Otherwise we look it up. We cache the result in the lock object
647 * itself, so actual lookup of the hash should be once per lock object.
649 static inline struct lock_class *
650 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
652 struct lockdep_subclass_key *key;
653 struct list_head *hash_head;
654 struct lock_class *class;
656 #ifdef CONFIG_DEBUG_LOCKDEP
658 * If the architecture calls into lockdep before initializing
659 * the hashes then we'll warn about it later. (we cannot printk
662 if (unlikely(!lockdep_initialized)) {
664 lockdep_init_error = 1;
669 * Static locks do not have their class-keys yet - for them the key
670 * is the lock object itself:
672 if (unlikely(!lock->key))
673 lock->key = (void *)lock;
676 * NOTE: the class-key must be unique. For dynamic locks, a static
677 * lock_class_key variable is passed in through the mutex_init()
678 * (or spin_lock_init()) call - which acts as the key. For static
679 * locks we use the lock object itself as the key.
681 BUILD_BUG_ON(sizeof(struct lock_class_key) >
682 sizeof(struct lockdep_map));
684 key = lock->key->subkeys + subclass;
686 hash_head = classhashentry(key);
689 * We can walk the hash lockfree, because the hash only
690 * grows, and we are careful when adding entries to the end:
692 list_for_each_entry(class, hash_head, hash_entry) {
693 if (class->key == key) {
694 WARN_ON_ONCE(class->name != lock->name);
703 * Register a lock's class in the hash-table, if the class is not present
704 * yet. Otherwise we look it up. We cache the result in the lock object
705 * itself, so actual lookup of the hash should be once per lock object.
707 static inline struct lock_class *
708 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
710 struct lockdep_subclass_key *key;
711 struct list_head *hash_head;
712 struct lock_class *class;
715 class = look_up_lock_class(lock, subclass);
720 * Debug-check: all keys must be persistent!
722 if (!static_obj(lock->key)) {
724 printk("INFO: trying to register non-static key.\n");
725 printk("the code is fine but needs lockdep annotation.\n");
726 printk("turning off the locking correctness validator.\n");
732 key = lock->key->subkeys + subclass;
733 hash_head = classhashentry(key);
735 raw_local_irq_save(flags);
737 raw_local_irq_restore(flags);
741 * We have to do the hash-walk again, to avoid races
744 list_for_each_entry(class, hash_head, hash_entry)
745 if (class->key == key)
748 * Allocate a new key from the static array, and add it to
751 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
752 if (!debug_locks_off_graph_unlock()) {
753 raw_local_irq_restore(flags);
756 raw_local_irq_restore(flags);
758 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
759 printk("turning off the locking correctness validator.\n");
762 class = lock_classes + nr_lock_classes++;
763 debug_atomic_inc(&nr_unused_locks);
765 class->name = lock->name;
766 class->subclass = subclass;
767 INIT_LIST_HEAD(&class->lock_entry);
768 INIT_LIST_HEAD(&class->locks_before);
769 INIT_LIST_HEAD(&class->locks_after);
770 class->name_version = count_matching_names(class);
772 * We use RCU's safe list-add method to make
773 * parallel walking of the hash-list safe:
775 list_add_tail_rcu(&class->hash_entry, hash_head);
777 if (verbose(class)) {
779 raw_local_irq_restore(flags);
781 printk("\nnew class %p: %s", class->key, class->name);
782 if (class->name_version > 1)
783 printk("#%d", class->name_version);
787 raw_local_irq_save(flags);
789 raw_local_irq_restore(flags);
795 raw_local_irq_restore(flags);
797 if (!subclass || force)
798 lock->class_cache = class;
800 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
806 #ifdef CONFIG_PROVE_LOCKING
808 * Allocate a lockdep entry. (assumes the graph_lock held, returns
809 * with NULL on failure)
811 static struct lock_list *alloc_list_entry(void)
813 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
814 if (!debug_locks_off_graph_unlock())
817 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
818 printk("turning off the locking correctness validator.\n");
821 return list_entries + nr_list_entries++;
825 * Add a new dependency to the head of the list:
827 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
828 struct list_head *head, unsigned long ip, int distance)
830 struct lock_list *entry;
832 * Lock not present yet - get a new dependency struct and
833 * add it to the list:
835 entry = alloc_list_entry();
840 entry->distance = distance;
841 if (!save_trace(&entry->trace))
845 * Since we never remove from the dependency list, the list can
846 * be walked lockless by other CPUs, it's only allocation
847 * that must be protected by the spinlock. But this also means
848 * we must make new entries visible only once writes to the
849 * entry become visible - hence the RCU op:
851 list_add_tail_rcu(&entry->entry, head);
857 * Recursive, forwards-direction lock-dependency checking, used for
858 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
861 * (to keep the stackframe of the recursive functions small we
862 * use these global variables, and we also mark various helper
863 * functions as noinline.)
865 static struct held_lock *check_source, *check_target;
868 * Print a dependency chain entry (this is only done when a deadlock
869 * has been detected):
872 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
874 if (debug_locks_silent)
876 printk("\n-> #%u", depth);
877 print_lock_name(target->class);
879 print_stack_trace(&target->trace, 6);
885 * When a circular dependency is detected, print the
889 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
891 struct task_struct *curr = current;
893 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
896 printk("\n=======================================================\n");
897 printk( "[ INFO: possible circular locking dependency detected ]\n");
898 print_kernel_version();
899 printk( "-------------------------------------------------------\n");
900 printk("%s/%d is trying to acquire lock:\n",
901 curr->comm, curr->pid);
902 print_lock(check_source);
903 printk("\nbut task is already holding lock:\n");
904 print_lock(check_target);
905 printk("\nwhich lock already depends on the new lock.\n\n");
906 printk("\nthe existing dependency chain (in reverse order) is:\n");
908 print_circular_bug_entry(entry, depth);
913 static noinline int print_circular_bug_tail(void)
915 struct task_struct *curr = current;
916 struct lock_list this;
918 if (debug_locks_silent)
921 this.class = check_source->class;
922 if (!save_trace(&this.trace))
925 print_circular_bug_entry(&this, 0);
927 printk("\nother info that might help us debug this:\n\n");
928 lockdep_print_held_locks(curr);
930 printk("\nstack backtrace:\n");
936 #define RECURSION_LIMIT 40
938 static int noinline print_infinite_recursion_bug(void)
940 if (!debug_locks_off_graph_unlock())
949 * Prove that the dependency graph starting at <entry> can not
950 * lead to <target>. Print an error and return 0 if it does.
953 check_noncircular(struct lock_class *source, unsigned int depth)
955 struct lock_list *entry;
957 debug_atomic_inc(&nr_cyclic_check_recursions);
958 if (depth > max_recursion_depth)
959 max_recursion_depth = depth;
960 if (depth >= RECURSION_LIMIT)
961 return print_infinite_recursion_bug();
963 * Check this lock's dependency list:
965 list_for_each_entry(entry, &source->locks_after, entry) {
966 if (entry->class == check_target->class)
967 return print_circular_bug_header(entry, depth+1);
968 debug_atomic_inc(&nr_cyclic_checks);
969 if (!check_noncircular(entry->class, depth+1))
970 return print_circular_bug_entry(entry, depth+1);
975 #ifdef CONFIG_TRACE_IRQFLAGS
977 * Forwards and backwards subgraph searching, for the purposes of
978 * proving that two subgraphs can be connected by a new dependency
979 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
981 static enum lock_usage_bit find_usage_bit;
982 static struct lock_class *forwards_match, *backwards_match;
985 * Find a node in the forwards-direction dependency sub-graph starting
986 * at <source> that matches <find_usage_bit>.
988 * Return 2 if such a node exists in the subgraph, and put that node
989 * into <forwards_match>.
991 * Return 1 otherwise and keep <forwards_match> unchanged.
995 find_usage_forwards(struct lock_class *source, unsigned int depth)
997 struct lock_list *entry;
1000 if (depth > max_recursion_depth)
1001 max_recursion_depth = depth;
1002 if (depth >= RECURSION_LIMIT)
1003 return print_infinite_recursion_bug();
1005 debug_atomic_inc(&nr_find_usage_forwards_checks);
1006 if (source->usage_mask & (1 << find_usage_bit)) {
1007 forwards_match = source;
1012 * Check this lock's dependency list:
1014 list_for_each_entry(entry, &source->locks_after, entry) {
1015 debug_atomic_inc(&nr_find_usage_forwards_recursions);
1016 ret = find_usage_forwards(entry->class, depth+1);
1017 if (ret == 2 || ret == 0)
1024 * Find a node in the backwards-direction dependency sub-graph starting
1025 * at <source> that matches <find_usage_bit>.
1027 * Return 2 if such a node exists in the subgraph, and put that node
1028 * into <backwards_match>.
1030 * Return 1 otherwise and keep <backwards_match> unchanged.
1031 * Return 0 on error.
1034 find_usage_backwards(struct lock_class *source, unsigned int depth)
1036 struct lock_list *entry;
1039 if (!__raw_spin_is_locked(&lockdep_lock))
1040 return DEBUG_LOCKS_WARN_ON(1);
1042 if (depth > max_recursion_depth)
1043 max_recursion_depth = depth;
1044 if (depth >= RECURSION_LIMIT)
1045 return print_infinite_recursion_bug();
1047 debug_atomic_inc(&nr_find_usage_backwards_checks);
1048 if (source->usage_mask & (1 << find_usage_bit)) {
1049 backwards_match = source;
1054 * Check this lock's dependency list:
1056 list_for_each_entry(entry, &source->locks_before, entry) {
1057 debug_atomic_inc(&nr_find_usage_backwards_recursions);
1058 ret = find_usage_backwards(entry->class, depth+1);
1059 if (ret == 2 || ret == 0)
1066 print_bad_irq_dependency(struct task_struct *curr,
1067 struct held_lock *prev,
1068 struct held_lock *next,
1069 enum lock_usage_bit bit1,
1070 enum lock_usage_bit bit2,
1071 const char *irqclass)
1073 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1076 printk("\n======================================================\n");
1077 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1078 irqclass, irqclass);
1079 print_kernel_version();
1080 printk( "------------------------------------------------------\n");
1081 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1082 curr->comm, curr->pid,
1083 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1084 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1085 curr->hardirqs_enabled,
1086 curr->softirqs_enabled);
1089 printk("\nand this task is already holding:\n");
1091 printk("which would create a new lock dependency:\n");
1092 print_lock_name(prev->class);
1094 print_lock_name(next->class);
1097 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1099 print_lock_name(backwards_match);
1100 printk("\n... which became %s-irq-safe at:\n", irqclass);
1102 print_stack_trace(backwards_match->usage_traces + bit1, 1);
1104 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1105 print_lock_name(forwards_match);
1106 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1109 print_stack_trace(forwards_match->usage_traces + bit2, 1);
1111 printk("\nother info that might help us debug this:\n\n");
1112 lockdep_print_held_locks(curr);
1114 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1115 print_lock_dependencies(backwards_match, 0);
1117 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1118 print_lock_dependencies(forwards_match, 0);
1120 printk("\nstack backtrace:\n");
1127 check_usage(struct task_struct *curr, struct held_lock *prev,
1128 struct held_lock *next, enum lock_usage_bit bit_backwards,
1129 enum lock_usage_bit bit_forwards, const char *irqclass)
1133 find_usage_bit = bit_backwards;
1134 /* fills in <backwards_match> */
1135 ret = find_usage_backwards(prev->class, 0);
1136 if (!ret || ret == 1)
1139 find_usage_bit = bit_forwards;
1140 ret = find_usage_forwards(next->class, 0);
1141 if (!ret || ret == 1)
1144 return print_bad_irq_dependency(curr, prev, next,
1145 bit_backwards, bit_forwards, irqclass);
1149 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1150 struct held_lock *next)
1153 * Prove that the new dependency does not connect a hardirq-safe
1154 * lock with a hardirq-unsafe lock - to achieve this we search
1155 * the backwards-subgraph starting at <prev>, and the
1156 * forwards-subgraph starting at <next>:
1158 if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
1159 LOCK_ENABLED_HARDIRQS, "hard"))
1163 * Prove that the new dependency does not connect a hardirq-safe-read
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_READ,
1169 LOCK_ENABLED_HARDIRQS, "hard-read"))
1173 * Prove that the new dependency does not connect a softirq-safe
1174 * lock with a softirq-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_SOFTIRQ,
1179 LOCK_ENABLED_SOFTIRQS, "soft"))
1182 * Prove that the new dependency does not connect a softirq-safe-read
1183 * lock with a softirq-unsafe lock - to achieve this we search
1184 * the backwards-subgraph starting at <prev>, and the
1185 * forwards-subgraph starting at <next>:
1187 if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
1188 LOCK_ENABLED_SOFTIRQS, "soft"))
1194 static void inc_chains(void)
1196 if (current->hardirq_context)
1197 nr_hardirq_chains++;
1199 if (current->softirq_context)
1200 nr_softirq_chains++;
1202 nr_process_chains++;
1209 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1210 struct held_lock *next)
1215 static inline void inc_chains(void)
1217 nr_process_chains++;
1223 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1224 struct held_lock *next)
1226 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1229 printk("\n=============================================\n");
1230 printk( "[ INFO: possible recursive locking detected ]\n");
1231 print_kernel_version();
1232 printk( "---------------------------------------------\n");
1233 printk("%s/%d is trying to acquire lock:\n",
1234 curr->comm, curr->pid);
1236 printk("\nbut task is already holding lock:\n");
1239 printk("\nother info that might help us debug this:\n");
1240 lockdep_print_held_locks(curr);
1242 printk("\nstack backtrace:\n");
1249 * Check whether we are holding such a class already.
1251 * (Note that this has to be done separately, because the graph cannot
1252 * detect such classes of deadlocks.)
1254 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1257 check_deadlock(struct task_struct *curr, struct held_lock *next,
1258 struct lockdep_map *next_instance, int read)
1260 struct held_lock *prev;
1263 for (i = 0; i < curr->lockdep_depth; i++) {
1264 prev = curr->held_locks + i;
1265 if (prev->class != next->class)
1268 * Allow read-after-read recursion of the same
1269 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1271 if ((read == 2) && prev->read)
1273 return print_deadlock_bug(curr, prev, next);
1279 * There was a chain-cache miss, and we are about to add a new dependency
1280 * to a previous lock. We recursively validate the following rules:
1282 * - would the adding of the <prev> -> <next> dependency create a
1283 * circular dependency in the graph? [== circular deadlock]
1285 * - does the new prev->next dependency connect any hardirq-safe lock
1286 * (in the full backwards-subgraph starting at <prev>) with any
1287 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1288 * <next>)? [== illegal lock inversion with hardirq contexts]
1290 * - does the new prev->next dependency connect any softirq-safe lock
1291 * (in the full backwards-subgraph starting at <prev>) with any
1292 * softirq-unsafe lock (in the full forwards-subgraph starting at
1293 * <next>)? [== illegal lock inversion with softirq contexts]
1295 * any of these scenarios could lead to a deadlock.
1297 * Then if all the validations pass, we add the forwards and backwards
1301 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1302 struct held_lock *next, int distance)
1304 struct lock_list *entry;
1308 * Prove that the new <prev> -> <next> dependency would not
1309 * create a circular dependency in the graph. (We do this by
1310 * forward-recursing into the graph starting at <next>, and
1311 * checking whether we can reach <prev>.)
1313 * We are using global variables to control the recursion, to
1314 * keep the stackframe size of the recursive functions low:
1316 check_source = next;
1317 check_target = prev;
1318 if (!(check_noncircular(next->class, 0)))
1319 return print_circular_bug_tail();
1321 if (!check_prev_add_irq(curr, prev, next))
1325 * For recursive read-locks we do all the dependency checks,
1326 * but we dont store read-triggered dependencies (only
1327 * write-triggered dependencies). This ensures that only the
1328 * write-side dependencies matter, and that if for example a
1329 * write-lock never takes any other locks, then the reads are
1330 * equivalent to a NOP.
1332 if (next->read == 2 || prev->read == 2)
1335 * Is the <prev> -> <next> dependency already present?
1337 * (this may occur even though this is a new chain: consider
1338 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1339 * chains - the second one will be new, but L1 already has
1340 * L2 added to its dependency list, due to the first chain.)
1342 list_for_each_entry(entry, &prev->class->locks_after, entry) {
1343 if (entry->class == next->class) {
1345 entry->distance = 1;
1351 * Ok, all validations passed, add the new lock
1352 * to the previous lock's dependency list:
1354 ret = add_lock_to_list(prev->class, next->class,
1355 &prev->class->locks_after, next->acquire_ip, distance);
1360 ret = add_lock_to_list(next->class, prev->class,
1361 &next->class->locks_before, next->acquire_ip, distance);
1366 * Debugging printouts:
1368 if (verbose(prev->class) || verbose(next->class)) {
1370 printk("\n new dependency: ");
1371 print_lock_name(prev->class);
1373 print_lock_name(next->class);
1376 return graph_lock();
1382 * Add the dependency to all directly-previous locks that are 'relevant'.
1383 * The ones that are relevant are (in increasing distance from curr):
1384 * all consecutive trylock entries and the final non-trylock entry - or
1385 * the end of this context's lock-chain - whichever comes first.
1388 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1390 int depth = curr->lockdep_depth;
1391 struct held_lock *hlock;
1396 * Depth must not be zero for a non-head lock:
1401 * At least two relevant locks must exist for this
1404 if (curr->held_locks[depth].irq_context !=
1405 curr->held_locks[depth-1].irq_context)
1409 int distance = curr->lockdep_depth - depth + 1;
1410 hlock = curr->held_locks + depth-1;
1412 * Only non-recursive-read entries get new dependencies
1415 if (hlock->read != 2) {
1416 if (!check_prev_add(curr, hlock, next, distance))
1419 * Stop after the first non-trylock entry,
1420 * as non-trylock entries have added their
1421 * own direct dependencies already, so this
1422 * lock is connected to them indirectly:
1424 if (!hlock->trylock)
1429 * End of lock-stack?
1434 * Stop the search if we cross into another context:
1436 if (curr->held_locks[depth].irq_context !=
1437 curr->held_locks[depth-1].irq_context)
1442 if (!debug_locks_off_graph_unlock())
1450 unsigned long nr_lock_chains;
1451 static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1454 * Look up a dependency chain. If the key is not present yet then
1455 * add it and return 1 - in this case the new dependency chain is
1456 * validated. If the key is already hashed, return 0.
1457 * (On return with 1 graph_lock is held.)
1459 static inline int lookup_chain_cache(u64 chain_key, struct lock_class *class)
1461 struct list_head *hash_head = chainhashentry(chain_key);
1462 struct lock_chain *chain;
1464 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1467 * We can walk it lock-free, because entries only get added
1470 list_for_each_entry(chain, hash_head, entry) {
1471 if (chain->chain_key == chain_key) {
1473 debug_atomic_inc(&chain_lookup_hits);
1474 if (very_verbose(class))
1475 printk("\nhash chain already cached, key: "
1476 "%016Lx tail class: [%p] %s\n",
1477 (unsigned long long)chain_key,
1478 class->key, class->name);
1482 if (very_verbose(class))
1483 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1484 (unsigned long long)chain_key, class->key, class->name);
1486 * Allocate a new chain entry from the static array, and add
1492 * We have to walk the chain again locked - to avoid duplicates:
1494 list_for_each_entry(chain, hash_head, entry) {
1495 if (chain->chain_key == chain_key) {
1500 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1501 if (!debug_locks_off_graph_unlock())
1504 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1505 printk("turning off the locking correctness validator.\n");
1508 chain = lock_chains + nr_lock_chains++;
1509 chain->chain_key = chain_key;
1510 list_add_tail_rcu(&chain->entry, hash_head);
1511 debug_atomic_inc(&chain_lookup_misses);
1517 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1518 struct held_lock *hlock, int chain_head)
1521 * Trylock needs to maintain the stack of held locks, but it
1522 * does not add new dependencies, because trylock can be done
1525 * We look up the chain_key and do the O(N^2) check and update of
1526 * the dependencies only if this is a new dependency chain.
1527 * (If lookup_chain_cache() returns with 1 it acquires
1528 * graph_lock for us)
1530 if (!hlock->trylock && (hlock->check == 2) &&
1531 lookup_chain_cache(curr->curr_chain_key, hlock->class)) {
1533 * Check whether last held lock:
1535 * - is irq-safe, if this lock is irq-unsafe
1536 * - is softirq-safe, if this lock is hardirq-unsafe
1538 * And check whether the new lock's dependency graph
1539 * could lead back to the previous lock.
1541 * any of these scenarios could lead to a deadlock. If
1544 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1549 * Mark recursive read, as we jump over it when
1550 * building dependencies (just like we jump over
1556 * Add dependency only if this lock is not the head
1557 * of the chain, and if it's not a secondary read-lock:
1559 if (!chain_head && ret != 2)
1560 if (!check_prevs_add(curr, hlock))
1564 /* after lookup_chain_cache(): */
1565 if (unlikely(!debug_locks))
1571 static inline int validate_chain(struct task_struct *curr,
1572 struct lockdep_map *lock, struct held_lock *hlock,
1580 * We are building curr_chain_key incrementally, so double-check
1581 * it from scratch, to make sure that it's done correctly:
1583 static void check_chain_key(struct task_struct *curr)
1585 #ifdef CONFIG_DEBUG_LOCKDEP
1586 struct held_lock *hlock, *prev_hlock = NULL;
1590 for (i = 0; i < curr->lockdep_depth; i++) {
1591 hlock = curr->held_locks + i;
1592 if (chain_key != hlock->prev_chain_key) {
1594 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1595 curr->lockdep_depth, i,
1596 (unsigned long long)chain_key,
1597 (unsigned long long)hlock->prev_chain_key);
1601 id = hlock->class - lock_classes;
1602 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1605 if (prev_hlock && (prev_hlock->irq_context !=
1606 hlock->irq_context))
1608 chain_key = iterate_chain_key(chain_key, id);
1611 if (chain_key != curr->curr_chain_key) {
1613 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1614 curr->lockdep_depth, i,
1615 (unsigned long long)chain_key,
1616 (unsigned long long)curr->curr_chain_key);
1623 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1624 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1626 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1629 printk("\n=================================\n");
1630 printk( "[ INFO: inconsistent lock state ]\n");
1631 print_kernel_version();
1632 printk( "---------------------------------\n");
1634 printk("inconsistent {%s} -> {%s} usage.\n",
1635 usage_str[prev_bit], usage_str[new_bit]);
1637 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1638 curr->comm, curr->pid,
1639 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1640 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1641 trace_hardirqs_enabled(curr),
1642 trace_softirqs_enabled(curr));
1645 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1646 print_stack_trace(this->class->usage_traces + prev_bit, 1);
1648 print_irqtrace_events(curr);
1649 printk("\nother info that might help us debug this:\n");
1650 lockdep_print_held_locks(curr);
1652 printk("\nstack backtrace:\n");
1659 * Print out an error if an invalid bit is set:
1662 valid_state(struct task_struct *curr, struct held_lock *this,
1663 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1665 if (unlikely(this->class->usage_mask & (1 << bad_bit)))
1666 return print_usage_bug(curr, this, bad_bit, new_bit);
1670 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1671 enum lock_usage_bit new_bit);
1673 #ifdef CONFIG_TRACE_IRQFLAGS
1676 * print irq inversion bug:
1679 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1680 struct held_lock *this, int forwards,
1681 const char *irqclass)
1683 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1686 printk("\n=========================================================\n");
1687 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1688 print_kernel_version();
1689 printk( "---------------------------------------------------------\n");
1690 printk("%s/%d just changed the state of lock:\n",
1691 curr->comm, curr->pid);
1694 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1696 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1697 print_lock_name(other);
1698 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1700 printk("\nother info that might help us debug this:\n");
1701 lockdep_print_held_locks(curr);
1703 printk("\nthe first lock's dependencies:\n");
1704 print_lock_dependencies(this->class, 0);
1706 printk("\nthe second lock's dependencies:\n");
1707 print_lock_dependencies(other, 0);
1709 printk("\nstack backtrace:\n");
1716 * Prove that in the forwards-direction subgraph starting at <this>
1717 * there is no lock matching <mask>:
1720 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1721 enum lock_usage_bit bit, const char *irqclass)
1725 find_usage_bit = bit;
1726 /* fills in <forwards_match> */
1727 ret = find_usage_forwards(this->class, 0);
1728 if (!ret || ret == 1)
1731 return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1735 * Prove that in the backwards-direction subgraph starting at <this>
1736 * there is no lock matching <mask>:
1739 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1740 enum lock_usage_bit bit, const char *irqclass)
1744 find_usage_bit = bit;
1745 /* fills in <backwards_match> */
1746 ret = find_usage_backwards(this->class, 0);
1747 if (!ret || ret == 1)
1750 return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1753 void print_irqtrace_events(struct task_struct *curr)
1755 printk("irq event stamp: %u\n", curr->irq_events);
1756 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
1757 print_ip_sym(curr->hardirq_enable_ip);
1758 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1759 print_ip_sym(curr->hardirq_disable_ip);
1760 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
1761 print_ip_sym(curr->softirq_enable_ip);
1762 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1763 print_ip_sym(curr->softirq_disable_ip);
1766 static int hardirq_verbose(struct lock_class *class)
1769 return class_filter(class);
1774 static int softirq_verbose(struct lock_class *class)
1777 return class_filter(class);
1782 #define STRICT_READ_CHECKS 1
1784 static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
1785 enum lock_usage_bit new_bit)
1790 case LOCK_USED_IN_HARDIRQ:
1791 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1793 if (!valid_state(curr, this, new_bit,
1794 LOCK_ENABLED_HARDIRQS_READ))
1797 * just marked it hardirq-safe, check that this lock
1798 * took no hardirq-unsafe lock in the past:
1800 if (!check_usage_forwards(curr, this,
1801 LOCK_ENABLED_HARDIRQS, "hard"))
1803 #if STRICT_READ_CHECKS
1805 * just marked it hardirq-safe, check that this lock
1806 * took no hardirq-unsafe-read lock in the past:
1808 if (!check_usage_forwards(curr, this,
1809 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1812 if (hardirq_verbose(this->class))
1815 case LOCK_USED_IN_SOFTIRQ:
1816 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1818 if (!valid_state(curr, this, new_bit,
1819 LOCK_ENABLED_SOFTIRQS_READ))
1822 * just marked it softirq-safe, check that this lock
1823 * took no softirq-unsafe lock in the past:
1825 if (!check_usage_forwards(curr, this,
1826 LOCK_ENABLED_SOFTIRQS, "soft"))
1828 #if STRICT_READ_CHECKS
1830 * just marked it softirq-safe, check that this lock
1831 * took no softirq-unsafe-read lock in the past:
1833 if (!check_usage_forwards(curr, this,
1834 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
1837 if (softirq_verbose(this->class))
1840 case LOCK_USED_IN_HARDIRQ_READ:
1841 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1844 * just marked it hardirq-read-safe, check that this lock
1845 * took no hardirq-unsafe lock in the past:
1847 if (!check_usage_forwards(curr, this,
1848 LOCK_ENABLED_HARDIRQS, "hard"))
1850 if (hardirq_verbose(this->class))
1853 case LOCK_USED_IN_SOFTIRQ_READ:
1854 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1857 * just marked it softirq-read-safe, check that this lock
1858 * took no softirq-unsafe lock in the past:
1860 if (!check_usage_forwards(curr, this,
1861 LOCK_ENABLED_SOFTIRQS, "soft"))
1863 if (softirq_verbose(this->class))
1866 case LOCK_ENABLED_HARDIRQS:
1867 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1869 if (!valid_state(curr, this, new_bit,
1870 LOCK_USED_IN_HARDIRQ_READ))
1873 * just marked it hardirq-unsafe, check that no hardirq-safe
1874 * lock in the system ever took it in the past:
1876 if (!check_usage_backwards(curr, this,
1877 LOCK_USED_IN_HARDIRQ, "hard"))
1879 #if STRICT_READ_CHECKS
1881 * just marked it hardirq-unsafe, check that no
1882 * hardirq-safe-read lock in the system ever took
1885 if (!check_usage_backwards(curr, this,
1886 LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
1889 if (hardirq_verbose(this->class))
1892 case LOCK_ENABLED_SOFTIRQS:
1893 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1895 if (!valid_state(curr, this, new_bit,
1896 LOCK_USED_IN_SOFTIRQ_READ))
1899 * just marked it softirq-unsafe, check that no softirq-safe
1900 * lock in the system ever took it in the past:
1902 if (!check_usage_backwards(curr, this,
1903 LOCK_USED_IN_SOFTIRQ, "soft"))
1905 #if STRICT_READ_CHECKS
1907 * just marked it softirq-unsafe, check that no
1908 * softirq-safe-read lock in the system ever took
1911 if (!check_usage_backwards(curr, this,
1912 LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
1915 if (softirq_verbose(this->class))
1918 case LOCK_ENABLED_HARDIRQS_READ:
1919 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1921 #if STRICT_READ_CHECKS
1923 * just marked it hardirq-read-unsafe, check that no
1924 * hardirq-safe lock in the system ever took it in the past:
1926 if (!check_usage_backwards(curr, this,
1927 LOCK_USED_IN_HARDIRQ, "hard"))
1930 if (hardirq_verbose(this->class))
1933 case LOCK_ENABLED_SOFTIRQS_READ:
1934 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1936 #if STRICT_READ_CHECKS
1938 * just marked it softirq-read-unsafe, check that no
1939 * softirq-safe lock in the system ever took it in the past:
1941 if (!check_usage_backwards(curr, this,
1942 LOCK_USED_IN_SOFTIRQ, "soft"))
1945 if (softirq_verbose(this->class))
1957 * Mark all held locks with a usage bit:
1960 mark_held_locks(struct task_struct *curr, int hardirq)
1962 enum lock_usage_bit usage_bit;
1963 struct held_lock *hlock;
1966 for (i = 0; i < curr->lockdep_depth; i++) {
1967 hlock = curr->held_locks + i;
1971 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
1973 usage_bit = LOCK_ENABLED_HARDIRQS;
1976 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
1978 usage_bit = LOCK_ENABLED_SOFTIRQS;
1980 if (!mark_lock(curr, hlock, usage_bit))
1988 * Debugging helper: via this flag we know that we are in
1989 * 'early bootup code', and will warn about any invalid irqs-on event:
1991 static int early_boot_irqs_enabled;
1993 void early_boot_irqs_off(void)
1995 early_boot_irqs_enabled = 0;
1998 void early_boot_irqs_on(void)
2000 early_boot_irqs_enabled = 1;
2004 * Hardirqs will be enabled:
2006 void trace_hardirqs_on(void)
2008 struct task_struct *curr = current;
2011 if (unlikely(!debug_locks || current->lockdep_recursion))
2014 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2017 if (unlikely(curr->hardirqs_enabled)) {
2018 debug_atomic_inc(&redundant_hardirqs_on);
2021 /* we'll do an OFF -> ON transition: */
2022 curr->hardirqs_enabled = 1;
2023 ip = (unsigned long) __builtin_return_address(0);
2025 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2027 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2030 * We are going to turn hardirqs on, so set the
2031 * usage bit for all held locks:
2033 if (!mark_held_locks(curr, 1))
2036 * If we have softirqs enabled, then set the usage
2037 * bit for all held locks. (disabled hardirqs prevented
2038 * this bit from being set before)
2040 if (curr->softirqs_enabled)
2041 if (!mark_held_locks(curr, 0))
2044 curr->hardirq_enable_ip = ip;
2045 curr->hardirq_enable_event = ++curr->irq_events;
2046 debug_atomic_inc(&hardirqs_on_events);
2049 EXPORT_SYMBOL(trace_hardirqs_on);
2052 * Hardirqs were disabled:
2054 void trace_hardirqs_off(void)
2056 struct task_struct *curr = current;
2058 if (unlikely(!debug_locks || current->lockdep_recursion))
2061 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2064 if (curr->hardirqs_enabled) {
2066 * We have done an ON -> OFF transition:
2068 curr->hardirqs_enabled = 0;
2069 curr->hardirq_disable_ip = _RET_IP_;
2070 curr->hardirq_disable_event = ++curr->irq_events;
2071 debug_atomic_inc(&hardirqs_off_events);
2073 debug_atomic_inc(&redundant_hardirqs_off);
2076 EXPORT_SYMBOL(trace_hardirqs_off);
2079 * Softirqs will be enabled:
2081 void trace_softirqs_on(unsigned long ip)
2083 struct task_struct *curr = current;
2085 if (unlikely(!debug_locks))
2088 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2091 if (curr->softirqs_enabled) {
2092 debug_atomic_inc(&redundant_softirqs_on);
2097 * We'll do an OFF -> ON transition:
2099 curr->softirqs_enabled = 1;
2100 curr->softirq_enable_ip = ip;
2101 curr->softirq_enable_event = ++curr->irq_events;
2102 debug_atomic_inc(&softirqs_on_events);
2104 * We are going to turn softirqs on, so set the
2105 * usage bit for all held locks, if hardirqs are
2108 if (curr->hardirqs_enabled)
2109 mark_held_locks(curr, 0);
2113 * Softirqs were disabled:
2115 void trace_softirqs_off(unsigned long ip)
2117 struct task_struct *curr = current;
2119 if (unlikely(!debug_locks))
2122 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2125 if (curr->softirqs_enabled) {
2127 * We have done an ON -> OFF transition:
2129 curr->softirqs_enabled = 0;
2130 curr->softirq_disable_ip = ip;
2131 curr->softirq_disable_event = ++curr->irq_events;
2132 debug_atomic_inc(&softirqs_off_events);
2133 DEBUG_LOCKS_WARN_ON(!softirq_count());
2135 debug_atomic_inc(&redundant_softirqs_off);
2138 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2141 * If non-trylock use in a hardirq or softirq context, then
2142 * mark the lock as used in these contexts:
2144 if (!hlock->trylock) {
2146 if (curr->hardirq_context)
2147 if (!mark_lock(curr, hlock,
2148 LOCK_USED_IN_HARDIRQ_READ))
2150 if (curr->softirq_context)
2151 if (!mark_lock(curr, hlock,
2152 LOCK_USED_IN_SOFTIRQ_READ))
2155 if (curr->hardirq_context)
2156 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2158 if (curr->softirq_context)
2159 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2163 if (!hlock->hardirqs_off) {
2165 if (!mark_lock(curr, hlock,
2166 LOCK_ENABLED_HARDIRQS_READ))
2168 if (curr->softirqs_enabled)
2169 if (!mark_lock(curr, hlock,
2170 LOCK_ENABLED_SOFTIRQS_READ))
2173 if (!mark_lock(curr, hlock,
2174 LOCK_ENABLED_HARDIRQS))
2176 if (curr->softirqs_enabled)
2177 if (!mark_lock(curr, hlock,
2178 LOCK_ENABLED_SOFTIRQS))
2186 static int separate_irq_context(struct task_struct *curr,
2187 struct held_lock *hlock)
2189 unsigned int depth = curr->lockdep_depth;
2192 * Keep track of points where we cross into an interrupt context:
2194 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2195 curr->softirq_context;
2197 struct held_lock *prev_hlock;
2199 prev_hlock = curr->held_locks + depth-1;
2201 * If we cross into another context, reset the
2202 * hash key (this also prevents the checking and the
2203 * adding of the dependency to 'prev'):
2205 if (prev_hlock->irq_context != hlock->irq_context)
2214 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2215 enum lock_usage_bit new_bit)
2221 static inline int mark_irqflags(struct task_struct *curr,
2222 struct held_lock *hlock)
2227 static inline int separate_irq_context(struct task_struct *curr,
2228 struct held_lock *hlock)
2236 * Mark a lock with a usage bit, and validate the state transition:
2238 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2239 enum lock_usage_bit new_bit)
2241 unsigned int new_mask = 1 << new_bit, ret = 1;
2244 * If already set then do not dirty the cacheline,
2245 * nor do any checks:
2247 if (likely(this->class->usage_mask & new_mask))
2253 * Make sure we didnt race:
2255 if (unlikely(this->class->usage_mask & new_mask)) {
2260 this->class->usage_mask |= new_mask;
2262 if (!save_trace(this->class->usage_traces + new_bit))
2266 case LOCK_USED_IN_HARDIRQ:
2267 case LOCK_USED_IN_SOFTIRQ:
2268 case LOCK_USED_IN_HARDIRQ_READ:
2269 case LOCK_USED_IN_SOFTIRQ_READ:
2270 case LOCK_ENABLED_HARDIRQS:
2271 case LOCK_ENABLED_SOFTIRQS:
2272 case LOCK_ENABLED_HARDIRQS_READ:
2273 case LOCK_ENABLED_SOFTIRQS_READ:
2274 ret = mark_lock_irq(curr, this, new_bit);
2280 * Add it to the global list of classes:
2282 list_add_tail_rcu(&this->class->lock_entry, &all_lock_classes);
2283 debug_atomic_dec(&nr_unused_locks);
2286 if (!debug_locks_off_graph_unlock())
2295 * We must printk outside of the graph_lock:
2298 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2300 print_irqtrace_events(curr);
2308 * Initialize a lock instance's lock-class mapping info:
2310 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2311 struct lock_class_key *key, int subclass)
2313 if (unlikely(!debug_locks))
2316 if (DEBUG_LOCKS_WARN_ON(!key))
2318 if (DEBUG_LOCKS_WARN_ON(!name))
2321 * Sanity check, the lock-class key must be persistent:
2323 if (!static_obj(key)) {
2324 printk("BUG: key %p not in .data!\n", key);
2325 DEBUG_LOCKS_WARN_ON(1);
2330 lock->class_cache = NULL;
2331 #ifdef CONFIG_LOCK_STAT
2332 lock->cpu = raw_smp_processor_id();
2335 register_lock_class(lock, subclass, 1);
2338 EXPORT_SYMBOL_GPL(lockdep_init_map);
2341 * This gets called for every mutex_lock*()/spin_lock*() operation.
2342 * We maintain the dependency maps and validate the locking attempt:
2344 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2345 int trylock, int read, int check, int hardirqs_off,
2348 struct task_struct *curr = current;
2349 struct lock_class *class = NULL;
2350 struct held_lock *hlock;
2351 unsigned int depth, id;
2358 if (unlikely(!debug_locks))
2361 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2364 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2366 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2367 printk("turning off the locking correctness validator.\n");
2372 class = lock->class_cache;
2374 * Not cached yet or subclass?
2376 if (unlikely(!class)) {
2377 class = register_lock_class(lock, subclass, 0);
2381 debug_atomic_inc((atomic_t *)&class->ops);
2382 if (very_verbose(class)) {
2383 printk("\nacquire class [%p] %s", class->key, class->name);
2384 if (class->name_version > 1)
2385 printk("#%d", class->name_version);
2391 * Add the lock to the list of currently held locks.
2392 * (we dont increase the depth just yet, up until the
2393 * dependency checks are done)
2395 depth = curr->lockdep_depth;
2396 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2399 hlock = curr->held_locks + depth;
2401 hlock->class = class;
2402 hlock->acquire_ip = ip;
2403 hlock->instance = lock;
2404 hlock->trylock = trylock;
2406 hlock->check = check;
2407 hlock->hardirqs_off = hardirqs_off;
2408 #ifdef CONFIG_LOCK_STAT
2409 hlock->waittime_stamp = 0;
2410 hlock->holdtime_stamp = sched_clock();
2413 if (check == 2 && !mark_irqflags(curr, hlock))
2416 /* mark it as used: */
2417 if (!mark_lock(curr, hlock, LOCK_USED))
2421 * Calculate the chain hash: it's the combined has of all the
2422 * lock keys along the dependency chain. We save the hash value
2423 * at every step so that we can get the current hash easily
2424 * after unlock. The chain hash is then used to cache dependency
2427 * The 'key ID' is what is the most compact key value to drive
2428 * the hash, not class->key.
2430 id = class - lock_classes;
2431 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2434 chain_key = curr->curr_chain_key;
2436 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2441 hlock->prev_chain_key = chain_key;
2442 if (separate_irq_context(curr, hlock)) {
2446 chain_key = iterate_chain_key(chain_key, id);
2447 curr->curr_chain_key = chain_key;
2449 if (!validate_chain(curr, lock, hlock, chain_head))
2452 curr->lockdep_depth++;
2453 check_chain_key(curr);
2454 #ifdef CONFIG_DEBUG_LOCKDEP
2455 if (unlikely(!debug_locks))
2458 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2460 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2461 printk("turning off the locking correctness validator.\n");
2465 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2466 max_lockdep_depth = curr->lockdep_depth;
2472 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2475 if (!debug_locks_off())
2477 if (debug_locks_silent)
2480 printk("\n=====================================\n");
2481 printk( "[ BUG: bad unlock balance detected! ]\n");
2482 printk( "-------------------------------------\n");
2483 printk("%s/%d is trying to release lock (",
2484 curr->comm, curr->pid);
2485 print_lockdep_cache(lock);
2488 printk("but there are no more locks to release!\n");
2489 printk("\nother info that might help us debug this:\n");
2490 lockdep_print_held_locks(curr);
2492 printk("\nstack backtrace:\n");
2499 * Common debugging checks for both nested and non-nested unlock:
2501 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2504 if (unlikely(!debug_locks))
2506 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2509 if (curr->lockdep_depth <= 0)
2510 return print_unlock_inbalance_bug(curr, lock, ip);
2516 * Remove the lock to the list of currently held locks in a
2517 * potentially non-nested (out of order) manner. This is a
2518 * relatively rare operation, as all the unlock APIs default
2519 * to nested mode (which uses lock_release()):
2522 lock_release_non_nested(struct task_struct *curr,
2523 struct lockdep_map *lock, unsigned long ip)
2525 struct held_lock *hlock, *prev_hlock;
2530 * Check whether the lock exists in the current stack
2533 depth = curr->lockdep_depth;
2534 if (DEBUG_LOCKS_WARN_ON(!depth))
2538 for (i = depth-1; i >= 0; i--) {
2539 hlock = curr->held_locks + i;
2541 * We must not cross into another context:
2543 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2545 if (hlock->instance == lock)
2549 return print_unlock_inbalance_bug(curr, lock, ip);
2552 lock_release_holdtime(hlock);
2555 * We have the right lock to unlock, 'hlock' points to it.
2556 * Now we remove it from the stack, and add back the other
2557 * entries (if any), recalculating the hash along the way:
2559 curr->lockdep_depth = i;
2560 curr->curr_chain_key = hlock->prev_chain_key;
2562 for (i++; i < depth; i++) {
2563 hlock = curr->held_locks + i;
2564 if (!__lock_acquire(hlock->instance,
2565 hlock->class->subclass, hlock->trylock,
2566 hlock->read, hlock->check, hlock->hardirqs_off,
2571 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2577 * Remove the lock to the list of currently held locks - this gets
2578 * called on mutex_unlock()/spin_unlock*() (or on a failed
2579 * mutex_lock_interruptible()). This is done for unlocks that nest
2580 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2582 static int lock_release_nested(struct task_struct *curr,
2583 struct lockdep_map *lock, unsigned long ip)
2585 struct held_lock *hlock;
2589 * Pop off the top of the lock stack:
2591 depth = curr->lockdep_depth - 1;
2592 hlock = curr->held_locks + depth;
2595 * Is the unlock non-nested:
2597 if (hlock->instance != lock)
2598 return lock_release_non_nested(curr, lock, ip);
2599 curr->lockdep_depth--;
2601 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2604 curr->curr_chain_key = hlock->prev_chain_key;
2606 lock_release_holdtime(hlock);
2608 #ifdef CONFIG_DEBUG_LOCKDEP
2609 hlock->prev_chain_key = 0;
2610 hlock->class = NULL;
2611 hlock->acquire_ip = 0;
2612 hlock->irq_context = 0;
2618 * Remove the lock to the list of currently held locks - this gets
2619 * called on mutex_unlock()/spin_unlock*() (or on a failed
2620 * mutex_lock_interruptible()). This is done for unlocks that nest
2621 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2624 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2626 struct task_struct *curr = current;
2628 if (!check_unlock(curr, lock, ip))
2632 if (!lock_release_nested(curr, lock, ip))
2635 if (!lock_release_non_nested(curr, lock, ip))
2639 check_chain_key(curr);
2643 * Check whether we follow the irq-flags state precisely:
2645 static void check_flags(unsigned long flags)
2647 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2651 if (irqs_disabled_flags(flags))
2652 DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled);
2654 DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled);
2657 * We dont accurately track softirq state in e.g.
2658 * hardirq contexts (such as on 4KSTACKS), so only
2659 * check if not in hardirq contexts:
2661 if (!hardirq_count()) {
2662 if (softirq_count())
2663 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2665 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2669 print_irqtrace_events(current);
2674 * We are not always called with irqs disabled - do that here,
2675 * and also avoid lockdep recursion:
2677 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2678 int trylock, int read, int check, unsigned long ip)
2680 unsigned long flags;
2682 if (unlikely(!lock_stat && !prove_locking))
2685 if (unlikely(current->lockdep_recursion))
2688 raw_local_irq_save(flags);
2691 current->lockdep_recursion = 1;
2692 __lock_acquire(lock, subclass, trylock, read, check,
2693 irqs_disabled_flags(flags), ip);
2694 current->lockdep_recursion = 0;
2695 raw_local_irq_restore(flags);
2698 EXPORT_SYMBOL_GPL(lock_acquire);
2700 void lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2702 unsigned long flags;
2704 if (unlikely(!lock_stat && !prove_locking))
2707 if (unlikely(current->lockdep_recursion))
2710 raw_local_irq_save(flags);
2712 current->lockdep_recursion = 1;
2713 __lock_release(lock, nested, ip);
2714 current->lockdep_recursion = 0;
2715 raw_local_irq_restore(flags);
2718 EXPORT_SYMBOL_GPL(lock_release);
2720 #ifdef CONFIG_LOCK_STAT
2722 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
2725 if (!debug_locks_off())
2727 if (debug_locks_silent)
2730 printk("\n=================================\n");
2731 printk( "[ BUG: bad contention detected! ]\n");
2732 printk( "---------------------------------\n");
2733 printk("%s/%d is trying to contend lock (",
2734 curr->comm, curr->pid);
2735 print_lockdep_cache(lock);
2738 printk("but there are no locks held!\n");
2739 printk("\nother info that might help us debug this:\n");
2740 lockdep_print_held_locks(curr);
2742 printk("\nstack backtrace:\n");
2749 __lock_contended(struct lockdep_map *lock, unsigned long ip)
2751 struct task_struct *curr = current;
2752 struct held_lock *hlock, *prev_hlock;
2753 struct lock_class_stats *stats;
2757 depth = curr->lockdep_depth;
2758 if (DEBUG_LOCKS_WARN_ON(!depth))
2762 for (i = depth-1; i >= 0; i--) {
2763 hlock = curr->held_locks + i;
2765 * We must not cross into another context:
2767 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2769 if (hlock->instance == lock)
2773 print_lock_contention_bug(curr, lock, ip);
2777 hlock->waittime_stamp = sched_clock();
2779 point = lock_contention_point(hlock->class, ip);
2781 stats = get_lock_stats(hlock->class);
2782 if (point < ARRAY_SIZE(stats->contention_point))
2783 stats->contention_point[i]++;
2784 if (lock->cpu != smp_processor_id())
2785 stats->bounces[bounce_contended + !!hlock->read]++;
2786 put_lock_stats(stats);
2790 __lock_acquired(struct lockdep_map *lock)
2792 struct task_struct *curr = current;
2793 struct held_lock *hlock, *prev_hlock;
2794 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, _RET_IP_);
2820 cpu = smp_processor_id();
2821 if (hlock->waittime_stamp) {
2822 now = sched_clock();
2823 waittime = now - hlock->waittime_stamp;
2824 hlock->holdtime_stamp = now;
2827 stats = get_lock_stats(hlock->class);
2830 lock_time_inc(&stats->read_waittime, waittime);
2832 lock_time_inc(&stats->write_waittime, waittime);
2834 if (lock->cpu != cpu)
2835 stats->bounces[bounce_acquired + !!hlock->read]++;
2836 put_lock_stats(stats);
2841 void lock_contended(struct lockdep_map *lock, unsigned long ip)
2843 unsigned long flags;
2845 if (unlikely(!lock_stat))
2848 if (unlikely(current->lockdep_recursion))
2851 raw_local_irq_save(flags);
2853 current->lockdep_recursion = 1;
2854 __lock_contended(lock, ip);
2855 current->lockdep_recursion = 0;
2856 raw_local_irq_restore(flags);
2858 EXPORT_SYMBOL_GPL(lock_contended);
2860 void lock_acquired(struct lockdep_map *lock)
2862 unsigned long flags;
2864 if (unlikely(!lock_stat))
2867 if (unlikely(current->lockdep_recursion))
2870 raw_local_irq_save(flags);
2872 current->lockdep_recursion = 1;
2873 __lock_acquired(lock);
2874 current->lockdep_recursion = 0;
2875 raw_local_irq_restore(flags);
2877 EXPORT_SYMBOL_GPL(lock_acquired);
2881 * Used by the testsuite, sanitize the validator state
2882 * after a simulated failure:
2885 void lockdep_reset(void)
2887 unsigned long flags;
2890 raw_local_irq_save(flags);
2891 current->curr_chain_key = 0;
2892 current->lockdep_depth = 0;
2893 current->lockdep_recursion = 0;
2894 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
2895 nr_hardirq_chains = 0;
2896 nr_softirq_chains = 0;
2897 nr_process_chains = 0;
2899 for (i = 0; i < CHAINHASH_SIZE; i++)
2900 INIT_LIST_HEAD(chainhash_table + i);
2901 raw_local_irq_restore(flags);
2904 static void zap_class(struct lock_class *class)
2909 * Remove all dependencies this lock is
2912 for (i = 0; i < nr_list_entries; i++) {
2913 if (list_entries[i].class == class)
2914 list_del_rcu(&list_entries[i].entry);
2917 * Unhash the class and remove it from the all_lock_classes list:
2919 list_del_rcu(&class->hash_entry);
2920 list_del_rcu(&class->lock_entry);
2924 static inline int within(void *addr, void *start, unsigned long size)
2926 return addr >= start && addr < start + size;
2929 void lockdep_free_key_range(void *start, unsigned long size)
2931 struct lock_class *class, *next;
2932 struct list_head *head;
2933 unsigned long flags;
2936 raw_local_irq_save(flags);
2940 * Unhash all classes that were created by this module:
2942 for (i = 0; i < CLASSHASH_SIZE; i++) {
2943 head = classhash_table + i;
2944 if (list_empty(head))
2946 list_for_each_entry_safe(class, next, head, hash_entry)
2947 if (within(class->key, start, size))
2952 raw_local_irq_restore(flags);
2955 void lockdep_reset_lock(struct lockdep_map *lock)
2957 struct lock_class *class, *next;
2958 struct list_head *head;
2959 unsigned long flags;
2962 raw_local_irq_save(flags);
2965 * Remove all classes this lock might have:
2967 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
2969 * If the class exists we look it up and zap it:
2971 class = look_up_lock_class(lock, j);
2976 * Debug check: in the end all mapped classes should
2980 for (i = 0; i < CLASSHASH_SIZE; i++) {
2981 head = classhash_table + i;
2982 if (list_empty(head))
2984 list_for_each_entry_safe(class, next, head, hash_entry) {
2985 if (unlikely(class == lock->class_cache)) {
2986 if (debug_locks_off_graph_unlock())
2995 raw_local_irq_restore(flags);
2998 void lockdep_init(void)
3003 * Some architectures have their own start_kernel()
3004 * code which calls lockdep_init(), while we also
3005 * call lockdep_init() from the start_kernel() itself,
3006 * and we want to initialize the hashes only once:
3008 if (lockdep_initialized)
3011 for (i = 0; i < CLASSHASH_SIZE; i++)
3012 INIT_LIST_HEAD(classhash_table + i);
3014 for (i = 0; i < CHAINHASH_SIZE; i++)
3015 INIT_LIST_HEAD(chainhash_table + i);
3017 lockdep_initialized = 1;
3020 void __init lockdep_info(void)
3022 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3024 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3025 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3026 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3027 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3028 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3029 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3030 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3032 printk(" memory used by lock dependency info: %lu kB\n",
3033 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3034 sizeof(struct list_head) * CLASSHASH_SIZE +
3035 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3036 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3037 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
3039 printk(" per task-struct memory footprint: %lu bytes\n",
3040 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3042 #ifdef CONFIG_DEBUG_LOCKDEP
3043 if (lockdep_init_error)
3044 printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n");
3048 static inline int in_range(const void *start, const void *addr, const void *end)
3050 return addr >= start && addr <= end;
3054 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3055 const void *mem_to, struct held_lock *hlock)
3057 if (!debug_locks_off())
3059 if (debug_locks_silent)
3062 printk("\n=========================\n");
3063 printk( "[ BUG: held lock freed! ]\n");
3064 printk( "-------------------------\n");
3065 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3066 curr->comm, curr->pid, mem_from, mem_to-1);
3068 lockdep_print_held_locks(curr);
3070 printk("\nstack backtrace:\n");
3075 * Called when kernel memory is freed (or unmapped), or if a lock
3076 * is destroyed or reinitialized - this code checks whether there is
3077 * any held lock in the memory range of <from> to <to>:
3079 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3081 const void *mem_to = mem_from + mem_len, *lock_from, *lock_to;
3082 struct task_struct *curr = current;
3083 struct held_lock *hlock;
3084 unsigned long flags;
3087 if (unlikely(!debug_locks))
3090 local_irq_save(flags);
3091 for (i = 0; i < curr->lockdep_depth; i++) {
3092 hlock = curr->held_locks + i;
3094 lock_from = (void *)hlock->instance;
3095 lock_to = (void *)(hlock->instance + 1);
3097 if (!in_range(mem_from, lock_from, mem_to) &&
3098 !in_range(mem_from, lock_to, mem_to))
3101 print_freed_lock_bug(curr, mem_from, mem_to, hlock);
3104 local_irq_restore(flags);
3106 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3108 static void print_held_locks_bug(struct task_struct *curr)
3110 if (!debug_locks_off())
3112 if (debug_locks_silent)
3115 printk("\n=====================================\n");
3116 printk( "[ BUG: lock held at task exit time! ]\n");
3117 printk( "-------------------------------------\n");
3118 printk("%s/%d is exiting with locks still held!\n",
3119 curr->comm, curr->pid);
3120 lockdep_print_held_locks(curr);
3122 printk("\nstack backtrace:\n");
3126 void debug_check_no_locks_held(struct task_struct *task)
3128 if (unlikely(task->lockdep_depth > 0))
3129 print_held_locks_bug(task);
3132 void debug_show_all_locks(void)
3134 struct task_struct *g, *p;
3138 if (unlikely(!debug_locks)) {
3139 printk("INFO: lockdep is turned off.\n");
3142 printk("\nShowing all locks held in the system:\n");
3145 * Here we try to get the tasklist_lock as hard as possible,
3146 * if not successful after 2 seconds we ignore it (but keep
3147 * trying). This is to enable a debug printout even if a
3148 * tasklist_lock-holding task deadlocks or crashes.
3151 if (!read_trylock(&tasklist_lock)) {
3153 printk("hm, tasklist_lock locked, retrying... ");
3156 printk(" #%d", 10-count);
3160 printk(" ignoring it.\n");
3164 printk(" locked it.\n");
3166 do_each_thread(g, p) {
3167 if (p->lockdep_depth)
3168 lockdep_print_held_locks(p);
3170 if (read_trylock(&tasklist_lock))
3172 } while_each_thread(g, p);
3175 printk("=============================================\n\n");
3178 read_unlock(&tasklist_lock);
3181 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3183 void debug_show_held_locks(struct task_struct *task)
3185 if (unlikely(!debug_locks)) {
3186 printk("INFO: lockdep is turned off.\n");
3189 lockdep_print_held_locks(task);
3192 EXPORT_SYMBOL_GPL(debug_show_held_locks);