4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <asm/sections.h>
48 #include "lockdep_internals.h"
50 #define CREATE_TRACE_POINTS
51 #include <trace/events/lockdep.h>
53 #ifdef CONFIG_PROVE_LOCKING
54 int prove_locking
= 1;
55 module_param(prove_locking
, int, 0644);
57 #define prove_locking 0
60 #ifdef CONFIG_LOCK_STAT
62 module_param(lock_stat
, int, 0644);
68 * lockdep_lock: protects the lockdep graph, the hashes and the
69 * class/list/hash allocators.
71 * This is one of the rare exceptions where it's justified
72 * to use a raw spinlock - we really dont want the spinlock
73 * code to recurse back into the lockdep code...
75 static raw_spinlock_t lockdep_lock
= (raw_spinlock_t
)__RAW_SPIN_LOCK_UNLOCKED
;
77 static int graph_lock(void)
79 __raw_spin_lock(&lockdep_lock
);
81 * Make sure that if another CPU detected a bug while
82 * walking the graph we dont change it (while the other
83 * CPU is busy printing out stuff with the graph lock
87 __raw_spin_unlock(&lockdep_lock
);
90 /* prevent any recursions within lockdep from causing deadlocks */
91 current
->lockdep_recursion
++;
95 static inline int graph_unlock(void)
97 if (debug_locks
&& !__raw_spin_is_locked(&lockdep_lock
))
98 return DEBUG_LOCKS_WARN_ON(1);
100 current
->lockdep_recursion
--;
101 __raw_spin_unlock(&lockdep_lock
);
106 * Turn lock debugging off and return with 0 if it was off already,
107 * and also release the graph lock:
109 static inline int debug_locks_off_graph_unlock(void)
111 int ret
= debug_locks_off();
113 __raw_spin_unlock(&lockdep_lock
);
118 static int lockdep_initialized
;
120 unsigned long nr_list_entries
;
121 struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
124 * All data structures here are protected by the global debug_lock.
126 * Mutex key structs only get allocated, once during bootup, and never
127 * get freed - this significantly simplifies the debugging code.
129 unsigned long nr_lock_classes
;
130 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
132 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
134 if (!hlock
->class_idx
) {
135 DEBUG_LOCKS_WARN_ON(1);
138 return lock_classes
+ hlock
->class_idx
- 1;
141 #ifdef CONFIG_LOCK_STAT
142 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
], lock_stats
);
144 static int lock_point(unsigned long points
[], unsigned long ip
)
148 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
149 if (points
[i
] == 0) {
160 static void lock_time_inc(struct lock_time
*lt
, s64 time
)
165 if (time
< lt
->min
|| !lt
->min
)
172 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
174 dst
->min
+= src
->min
;
175 dst
->max
+= src
->max
;
176 dst
->total
+= src
->total
;
180 struct lock_class_stats
lock_stats(struct lock_class
*class)
182 struct lock_class_stats stats
;
185 memset(&stats
, 0, sizeof(struct lock_class_stats
));
186 for_each_possible_cpu(cpu
) {
187 struct lock_class_stats
*pcs
=
188 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
190 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
191 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
193 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
194 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
196 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
197 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
199 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
200 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
202 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
203 stats
.bounces
[i
] += pcs
->bounces
[i
];
209 void clear_lock_stats(struct lock_class
*class)
213 for_each_possible_cpu(cpu
) {
214 struct lock_class_stats
*cpu_stats
=
215 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
217 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
219 memset(class->contention_point
, 0, sizeof(class->contention_point
));
220 memset(class->contending_point
, 0, sizeof(class->contending_point
));
223 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
225 return &get_cpu_var(lock_stats
)[class - lock_classes
];
228 static void put_lock_stats(struct lock_class_stats
*stats
)
230 put_cpu_var(lock_stats
);
233 static void lock_release_holdtime(struct held_lock
*hlock
)
235 struct lock_class_stats
*stats
;
241 holdtime
= sched_clock() - hlock
->holdtime_stamp
;
243 stats
= get_lock_stats(hlock_class(hlock
));
245 lock_time_inc(&stats
->read_holdtime
, holdtime
);
247 lock_time_inc(&stats
->write_holdtime
, holdtime
);
248 put_lock_stats(stats
);
251 static inline void lock_release_holdtime(struct held_lock
*hlock
)
257 * We keep a global list of all lock classes. The list only grows,
258 * never shrinks. The list is only accessed with the lockdep
259 * spinlock lock held.
261 LIST_HEAD(all_lock_classes
);
264 * The lockdep classes are in a hash-table as well, for fast lookup:
266 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
267 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
268 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
269 #define classhashentry(key) (classhash_table + __classhashfn((key)))
271 static struct list_head classhash_table
[CLASSHASH_SIZE
];
274 * We put the lock dependency chains into a hash-table as well, to cache
277 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
278 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
279 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
280 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
282 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
285 * The hash key of the lock dependency chains is a hash itself too:
286 * it's a hash of all locks taken up to that lock, including that lock.
287 * It's a 64-bit hash, because it's important for the keys to be
290 #define iterate_chain_key(key1, key2) \
291 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
292 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
295 void lockdep_off(void)
297 current
->lockdep_recursion
++;
299 EXPORT_SYMBOL(lockdep_off
);
301 void lockdep_on(void)
303 current
->lockdep_recursion
--;
305 EXPORT_SYMBOL(lockdep_on
);
308 * Debugging switches:
312 #define VERY_VERBOSE 0
315 # define HARDIRQ_VERBOSE 1
316 # define SOFTIRQ_VERBOSE 1
317 # define RECLAIM_VERBOSE 1
319 # define HARDIRQ_VERBOSE 0
320 # define SOFTIRQ_VERBOSE 0
321 # define RECLAIM_VERBOSE 0
324 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
326 * Quick filtering for interesting events:
328 static int class_filter(struct lock_class
*class)
332 if (class->name_version
== 1 &&
333 !strcmp(class->name
, "lockname"))
335 if (class->name_version
== 1 &&
336 !strcmp(class->name
, "&struct->lockfield"))
339 /* Filter everything else. 1 would be to allow everything else */
344 static int verbose(struct lock_class
*class)
347 return class_filter(class);
353 * Stack-trace: tightly packed array of stack backtrace
354 * addresses. Protected by the graph_lock.
356 unsigned long nr_stack_trace_entries
;
357 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
359 static int save_trace(struct stack_trace
*trace
)
361 trace
->nr_entries
= 0;
362 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
363 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
367 save_stack_trace(trace
);
369 trace
->max_entries
= trace
->nr_entries
;
371 nr_stack_trace_entries
+= trace
->nr_entries
;
373 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
374 if (!debug_locks_off_graph_unlock())
377 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
378 printk("turning off the locking correctness validator.\n");
387 unsigned int nr_hardirq_chains
;
388 unsigned int nr_softirq_chains
;
389 unsigned int nr_process_chains
;
390 unsigned int max_lockdep_depth
;
391 unsigned int max_recursion_depth
;
393 static unsigned int lockdep_dependency_gen_id
;
395 static bool lockdep_dependency_visit(struct lock_class
*source
,
399 lockdep_dependency_gen_id
++;
400 if (source
->dep_gen_id
== lockdep_dependency_gen_id
)
402 source
->dep_gen_id
= lockdep_dependency_gen_id
;
406 #ifdef CONFIG_DEBUG_LOCKDEP
408 * We cannot printk in early bootup code. Not even early_printk()
409 * might work. So we mark any initialization errors and printk
410 * about it later on, in lockdep_info().
412 static int lockdep_init_error
;
413 static unsigned long lockdep_init_trace_data
[20];
414 static struct stack_trace lockdep_init_trace
= {
415 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
416 .entries
= lockdep_init_trace_data
,
420 * Various lockdep statistics:
422 atomic_t chain_lookup_hits
;
423 atomic_t chain_lookup_misses
;
424 atomic_t hardirqs_on_events
;
425 atomic_t hardirqs_off_events
;
426 atomic_t redundant_hardirqs_on
;
427 atomic_t redundant_hardirqs_off
;
428 atomic_t softirqs_on_events
;
429 atomic_t softirqs_off_events
;
430 atomic_t redundant_softirqs_on
;
431 atomic_t redundant_softirqs_off
;
432 atomic_t nr_unused_locks
;
433 atomic_t nr_cyclic_checks
;
434 atomic_t nr_cyclic_check_recursions
;
435 atomic_t nr_find_usage_forwards_checks
;
436 atomic_t nr_find_usage_forwards_recursions
;
437 atomic_t nr_find_usage_backwards_checks
;
438 atomic_t nr_find_usage_backwards_recursions
;
445 #define __USAGE(__STATE) \
446 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
447 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
448 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
449 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
451 static const char *usage_str
[] =
453 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
454 #include "lockdep_states.h"
456 [LOCK_USED
] = "INITIAL USE",
459 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
461 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
464 static inline unsigned long lock_flag(enum lock_usage_bit bit
)
469 static char get_usage_char(struct lock_class
*class, enum lock_usage_bit bit
)
473 if (class->usage_mask
& lock_flag(bit
+ 2))
475 if (class->usage_mask
& lock_flag(bit
)) {
477 if (class->usage_mask
& lock_flag(bit
+ 2))
484 void get_usage_chars(struct lock_class
*class, char usage
[LOCK_USAGE_CHARS
])
488 #define LOCKDEP_STATE(__STATE) \
489 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
490 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
491 #include "lockdep_states.h"
497 static void print_lock_name(struct lock_class
*class)
499 char str
[KSYM_NAME_LEN
], usage
[LOCK_USAGE_CHARS
];
502 get_usage_chars(class, usage
);
506 name
= __get_key_name(class->key
, str
);
507 printk(" (%s", name
);
509 printk(" (%s", name
);
510 if (class->name_version
> 1)
511 printk("#%d", class->name_version
);
513 printk("/%d", class->subclass
);
515 printk("){%s}", usage
);
518 static void print_lockdep_cache(struct lockdep_map
*lock
)
521 char str
[KSYM_NAME_LEN
];
525 name
= __get_key_name(lock
->key
->subkeys
, str
);
530 static void print_lock(struct held_lock
*hlock
)
532 print_lock_name(hlock_class(hlock
));
534 print_ip_sym(hlock
->acquire_ip
);
537 static void lockdep_print_held_locks(struct task_struct
*curr
)
539 int i
, depth
= curr
->lockdep_depth
;
542 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
545 printk("%d lock%s held by %s/%d:\n",
546 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
548 for (i
= 0; i
< depth
; i
++) {
550 print_lock(curr
->held_locks
+ i
);
554 static void print_lock_class_header(struct lock_class
*class, int depth
)
558 printk("%*s->", depth
, "");
559 print_lock_name(class);
560 printk(" ops: %lu", class->ops
);
563 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
564 if (class->usage_mask
& (1 << bit
)) {
567 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
568 len
+= printk(" at:\n");
569 print_stack_trace(class->usage_traces
+ bit
, len
);
572 printk("%*s }\n", depth
, "");
574 printk("%*s ... key at: ",depth
,"");
575 print_ip_sym((unsigned long)class->key
);
579 * printk all lock dependencies starting at <entry>:
582 print_lock_dependencies(struct lock_class
*class, int depth
)
584 struct lock_list
*entry
;
586 if (lockdep_dependency_visit(class, depth
))
589 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
592 print_lock_class_header(class, depth
);
594 list_for_each_entry(entry
, &class->locks_after
, entry
) {
595 if (DEBUG_LOCKS_WARN_ON(!entry
->class))
598 print_lock_dependencies(entry
->class, depth
+ 1);
600 printk("%*s ... acquired at:\n",depth
,"");
601 print_stack_trace(&entry
->trace
, 2);
606 static void print_kernel_version(void)
608 printk("%s %.*s\n", init_utsname()->release
,
609 (int)strcspn(init_utsname()->version
, " "),
610 init_utsname()->version
);
613 static int very_verbose(struct lock_class
*class)
616 return class_filter(class);
622 * Is this the address of a static object:
624 static int static_obj(void *obj
)
626 unsigned long start
= (unsigned long) &_stext
,
627 end
= (unsigned long) &_end
,
628 addr
= (unsigned long) obj
;
636 if ((addr
>= start
) && (addr
< end
))
643 for_each_possible_cpu(i
) {
644 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
645 end
= (unsigned long) &__per_cpu_start
+ PERCPU_ENOUGH_ROOM
648 if ((addr
>= start
) && (addr
< end
))
656 return is_module_address(addr
);
660 * To make lock name printouts unique, we calculate a unique
661 * class->name_version generation counter:
663 static int count_matching_names(struct lock_class
*new_class
)
665 struct lock_class
*class;
668 if (!new_class
->name
)
671 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
672 if (new_class
->key
- new_class
->subclass
== class->key
)
673 return class->name_version
;
674 if (class->name
&& !strcmp(class->name
, new_class
->name
))
675 count
= max(count
, class->name_version
);
682 * Register a lock's class in the hash-table, if the class is not present
683 * yet. Otherwise we look it up. We cache the result in the lock object
684 * itself, so actual lookup of the hash should be once per lock object.
686 static inline struct lock_class
*
687 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
689 struct lockdep_subclass_key
*key
;
690 struct list_head
*hash_head
;
691 struct lock_class
*class;
693 #ifdef CONFIG_DEBUG_LOCKDEP
695 * If the architecture calls into lockdep before initializing
696 * the hashes then we'll warn about it later. (we cannot printk
699 if (unlikely(!lockdep_initialized
)) {
701 lockdep_init_error
= 1;
702 save_stack_trace(&lockdep_init_trace
);
707 * Static locks do not have their class-keys yet - for them the key
708 * is the lock object itself:
710 if (unlikely(!lock
->key
))
711 lock
->key
= (void *)lock
;
714 * NOTE: the class-key must be unique. For dynamic locks, a static
715 * lock_class_key variable is passed in through the mutex_init()
716 * (or spin_lock_init()) call - which acts as the key. For static
717 * locks we use the lock object itself as the key.
719 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
720 sizeof(struct lockdep_map
));
722 key
= lock
->key
->subkeys
+ subclass
;
724 hash_head
= classhashentry(key
);
727 * We can walk the hash lockfree, because the hash only
728 * grows, and we are careful when adding entries to the end:
730 list_for_each_entry(class, hash_head
, hash_entry
) {
731 if (class->key
== key
) {
732 WARN_ON_ONCE(class->name
!= lock
->name
);
741 * Register a lock's class in the hash-table, if the class is not present
742 * yet. Otherwise we look it up. We cache the result in the lock object
743 * itself, so actual lookup of the hash should be once per lock object.
745 static inline struct lock_class
*
746 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
748 struct lockdep_subclass_key
*key
;
749 struct list_head
*hash_head
;
750 struct lock_class
*class;
753 class = look_up_lock_class(lock
, subclass
);
758 * Debug-check: all keys must be persistent!
760 if (!static_obj(lock
->key
)) {
762 printk("INFO: trying to register non-static key.\n");
763 printk("the code is fine but needs lockdep annotation.\n");
764 printk("turning off the locking correctness validator.\n");
770 key
= lock
->key
->subkeys
+ subclass
;
771 hash_head
= classhashentry(key
);
773 raw_local_irq_save(flags
);
775 raw_local_irq_restore(flags
);
779 * We have to do the hash-walk again, to avoid races
782 list_for_each_entry(class, hash_head
, hash_entry
)
783 if (class->key
== key
)
786 * Allocate a new key from the static array, and add it to
789 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
790 if (!debug_locks_off_graph_unlock()) {
791 raw_local_irq_restore(flags
);
794 raw_local_irq_restore(flags
);
796 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
797 printk("turning off the locking correctness validator.\n");
801 class = lock_classes
+ nr_lock_classes
++;
802 debug_atomic_inc(&nr_unused_locks
);
804 class->name
= lock
->name
;
805 class->subclass
= subclass
;
806 INIT_LIST_HEAD(&class->lock_entry
);
807 INIT_LIST_HEAD(&class->locks_before
);
808 INIT_LIST_HEAD(&class->locks_after
);
809 class->name_version
= count_matching_names(class);
811 * We use RCU's safe list-add method to make
812 * parallel walking of the hash-list safe:
814 list_add_tail_rcu(&class->hash_entry
, hash_head
);
816 * Add it to the global list of classes:
818 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
820 if (verbose(class)) {
822 raw_local_irq_restore(flags
);
824 printk("\nnew class %p: %s", class->key
, class->name
);
825 if (class->name_version
> 1)
826 printk("#%d", class->name_version
);
830 raw_local_irq_save(flags
);
832 raw_local_irq_restore(flags
);
838 raw_local_irq_restore(flags
);
840 if (!subclass
|| force
)
841 lock
->class_cache
= class;
843 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
849 #ifdef CONFIG_PROVE_LOCKING
851 * Allocate a lockdep entry. (assumes the graph_lock held, returns
852 * with NULL on failure)
854 static struct lock_list
*alloc_list_entry(void)
856 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
857 if (!debug_locks_off_graph_unlock())
860 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
861 printk("turning off the locking correctness validator.\n");
865 return list_entries
+ nr_list_entries
++;
869 * Add a new dependency to the head of the list:
871 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
872 struct list_head
*head
, unsigned long ip
, int distance
)
874 struct lock_list
*entry
;
876 * Lock not present yet - get a new dependency struct and
877 * add it to the list:
879 entry
= alloc_list_entry();
883 if (!save_trace(&entry
->trace
))
887 entry
->distance
= distance
;
889 * Since we never remove from the dependency list, the list can
890 * be walked lockless by other CPUs, it's only allocation
891 * that must be protected by the spinlock. But this also means
892 * we must make new entries visible only once writes to the
893 * entry become visible - hence the RCU op:
895 list_add_tail_rcu(&entry
->entry
, head
);
900 unsigned long bfs_accessed
[BITS_TO_LONGS(MAX_LOCKDEP_ENTRIES
)];
901 static struct circular_queue lock_cq
;
903 static int __bfs(struct lock_list
*source_entry
,
905 int (*match
)(struct lock_list
*entry
, void *data
),
906 struct lock_list
**target_entry
,
909 struct lock_list
*entry
;
910 struct list_head
*head
;
911 struct circular_queue
*cq
= &lock_cq
;
914 if (match(source_entry
, data
)) {
915 *target_entry
= source_entry
;
921 head
= &source_entry
->class->locks_after
;
923 head
= &source_entry
->class->locks_before
;
925 if (list_empty(head
))
929 __cq_enqueue(cq
, (unsigned long)source_entry
);
931 while (!__cq_empty(cq
)) {
932 struct lock_list
*lock
;
934 __cq_dequeue(cq
, (unsigned long *)&lock
);
942 head
= &lock
->class->locks_after
;
944 head
= &lock
->class->locks_before
;
946 list_for_each_entry(entry
, head
, entry
) {
947 if (!lock_accessed(entry
)) {
948 mark_lock_accessed(entry
, lock
);
949 if (match(entry
, data
)) {
950 *target_entry
= entry
;
955 if (__cq_enqueue(cq
, (unsigned long)entry
)) {
966 static inline int __bfs_forward(struct lock_list
*src_entry
,
968 int (*match
)(struct lock_list
*entry
, void *data
),
969 struct lock_list
**target_entry
)
971 return __bfs(src_entry
, data
, match
, target_entry
, 1);
975 static inline int __bfs_backward(struct lock_list
*src_entry
,
977 int (*match
)(struct lock_list
*entry
, void *data
),
978 struct lock_list
**target_entry
)
980 return __bfs(src_entry
, data
, match
, target_entry
, 0);
985 * Recursive, forwards-direction lock-dependency checking, used for
986 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
989 * (to keep the stackframe of the recursive functions small we
990 * use these global variables, and we also mark various helper
991 * functions as noinline.)
993 static struct held_lock
*check_source
, *check_target
;
996 * Print a dependency chain entry (this is only done when a deadlock
997 * has been detected):
1000 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
1002 if (debug_locks_silent
)
1004 printk("\n-> #%u", depth
);
1005 print_lock_name(target
->class);
1007 print_stack_trace(&target
->trace
, 6);
1013 * When a circular dependency is detected, print the
1017 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
)
1019 struct task_struct
*curr
= current
;
1021 if (debug_locks_silent
)
1024 printk("\n=======================================================\n");
1025 printk( "[ INFO: possible circular locking dependency detected ]\n");
1026 print_kernel_version();
1027 printk( "-------------------------------------------------------\n");
1028 printk("%s/%d is trying to acquire lock:\n",
1029 curr
->comm
, task_pid_nr(curr
));
1030 print_lock(check_source
);
1031 printk("\nbut task is already holding lock:\n");
1032 print_lock(check_target
);
1033 printk("\nwhich lock already depends on the new lock.\n\n");
1034 printk("\nthe existing dependency chain (in reverse order) is:\n");
1036 print_circular_bug_entry(entry
, depth
);
1041 static inline int class_equal(struct lock_list
*entry
, void *data
)
1043 return entry
->class == data
;
1046 static noinline
int print_circular_bug(void)
1048 struct task_struct
*curr
= current
;
1049 struct lock_list
this;
1050 struct lock_list
*target
;
1051 struct lock_list
*parent
;
1053 unsigned long depth
;
1055 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1058 this.class = hlock_class(check_source
);
1060 if (!save_trace(&this.trace
))
1063 result
= __bfs_forward(&this,
1064 hlock_class(check_target
),
1068 printk("\n%s:search shortest path failed:%d\n", __func__
,
1073 depth
= get_lock_depth(target
);
1075 print_circular_bug_header(target
, depth
);
1077 parent
= get_lock_parent(target
);
1080 print_circular_bug_entry(parent
, --depth
);
1081 parent
= get_lock_parent(parent
);
1084 printk("\nother info that might help us debug this:\n\n");
1085 lockdep_print_held_locks(curr
);
1087 printk("\nstack backtrace:\n");
1093 #define RECURSION_LIMIT 40
1095 static int noinline
print_infinite_recursion_bug(void)
1097 if (!debug_locks_off_graph_unlock())
1105 unsigned long __lockdep_count_forward_deps(struct lock_class
*class,
1108 struct lock_list
*entry
;
1109 unsigned long ret
= 1;
1111 if (lockdep_dependency_visit(class, depth
))
1115 * Recurse this class's dependency list:
1117 list_for_each_entry(entry
, &class->locks_after
, entry
)
1118 ret
+= __lockdep_count_forward_deps(entry
->class, depth
+ 1);
1123 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1125 unsigned long ret
, flags
;
1127 local_irq_save(flags
);
1128 __raw_spin_lock(&lockdep_lock
);
1129 ret
= __lockdep_count_forward_deps(class, 0);
1130 __raw_spin_unlock(&lockdep_lock
);
1131 local_irq_restore(flags
);
1136 unsigned long __lockdep_count_backward_deps(struct lock_class
*class,
1139 struct lock_list
*entry
;
1140 unsigned long ret
= 1;
1142 if (lockdep_dependency_visit(class, depth
))
1145 * Recurse this class's dependency list:
1147 list_for_each_entry(entry
, &class->locks_before
, entry
)
1148 ret
+= __lockdep_count_backward_deps(entry
->class, depth
+ 1);
1153 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1155 unsigned long ret
, flags
;
1157 local_irq_save(flags
);
1158 __raw_spin_lock(&lockdep_lock
);
1159 ret
= __lockdep_count_backward_deps(class, 0);
1160 __raw_spin_unlock(&lockdep_lock
);
1161 local_irq_restore(flags
);
1167 * Prove that the dependency graph starting at <entry> can not
1168 * lead to <target>. Print an error and return 0 if it does.
1171 check_noncircular(struct lock_class
*source
, unsigned int depth
)
1173 struct lock_list
*entry
;
1175 if (lockdep_dependency_visit(source
, depth
))
1178 debug_atomic_inc(&nr_cyclic_check_recursions
);
1179 if (depth
> max_recursion_depth
)
1180 max_recursion_depth
= depth
;
1181 if (depth
>= RECURSION_LIMIT
)
1182 return print_infinite_recursion_bug();
1184 * Check this lock's dependency list:
1186 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1187 if (entry
->class == hlock_class(check_target
))
1189 debug_atomic_inc(&nr_cyclic_checks
);
1190 if (check_noncircular(entry
->class, depth
+1) == 2)
1197 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1199 * Forwards and backwards subgraph searching, for the purposes of
1200 * proving that two subgraphs can be connected by a new dependency
1201 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1203 static enum lock_usage_bit find_usage_bit
;
1204 static struct lock_class
*forwards_match
, *backwards_match
;
1207 * Find a node in the forwards-direction dependency sub-graph starting
1208 * at <source> that matches <find_usage_bit>.
1210 * Return 2 if such a node exists in the subgraph, and put that node
1211 * into <forwards_match>.
1213 * Return 1 otherwise and keep <forwards_match> unchanged.
1214 * Return 0 on error.
1217 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
1219 struct lock_list
*entry
;
1222 if (lockdep_dependency_visit(source
, depth
))
1225 if (depth
> max_recursion_depth
)
1226 max_recursion_depth
= depth
;
1227 if (depth
>= RECURSION_LIMIT
)
1228 return print_infinite_recursion_bug();
1230 debug_atomic_inc(&nr_find_usage_forwards_checks
);
1231 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1232 forwards_match
= source
;
1237 * Check this lock's dependency list:
1239 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1240 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
1241 ret
= find_usage_forwards(entry
->class, depth
+1);
1242 if (ret
== 2 || ret
== 0)
1249 * Find a node in the backwards-direction dependency sub-graph starting
1250 * at <source> that matches <find_usage_bit>.
1252 * Return 2 if such a node exists in the subgraph, and put that node
1253 * into <backwards_match>.
1255 * Return 1 otherwise and keep <backwards_match> unchanged.
1256 * Return 0 on error.
1259 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
1261 struct lock_list
*entry
;
1264 if (lockdep_dependency_visit(source
, depth
))
1267 if (!__raw_spin_is_locked(&lockdep_lock
))
1268 return DEBUG_LOCKS_WARN_ON(1);
1270 if (depth
> max_recursion_depth
)
1271 max_recursion_depth
= depth
;
1272 if (depth
>= RECURSION_LIMIT
)
1273 return print_infinite_recursion_bug();
1275 debug_atomic_inc(&nr_find_usage_backwards_checks
);
1276 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1277 backwards_match
= source
;
1281 if (!source
&& debug_locks_off_graph_unlock()) {
1287 * Check this lock's dependency list:
1289 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
1290 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
1291 ret
= find_usage_backwards(entry
->class, depth
+1);
1292 if (ret
== 2 || ret
== 0)
1299 print_bad_irq_dependency(struct task_struct
*curr
,
1300 struct held_lock
*prev
,
1301 struct held_lock
*next
,
1302 enum lock_usage_bit bit1
,
1303 enum lock_usage_bit bit2
,
1304 const char *irqclass
)
1306 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1309 printk("\n======================================================\n");
1310 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1311 irqclass
, irqclass
);
1312 print_kernel_version();
1313 printk( "------------------------------------------------------\n");
1314 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1315 curr
->comm
, task_pid_nr(curr
),
1316 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1317 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1318 curr
->hardirqs_enabled
,
1319 curr
->softirqs_enabled
);
1322 printk("\nand this task is already holding:\n");
1324 printk("which would create a new lock dependency:\n");
1325 print_lock_name(hlock_class(prev
));
1327 print_lock_name(hlock_class(next
));
1330 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1332 print_lock_name(backwards_match
);
1333 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1335 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
1337 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1338 print_lock_name(forwards_match
);
1339 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1342 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
1344 printk("\nother info that might help us debug this:\n\n");
1345 lockdep_print_held_locks(curr
);
1347 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
1348 print_lock_dependencies(backwards_match
, 0);
1350 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
1351 print_lock_dependencies(forwards_match
, 0);
1353 printk("\nstack backtrace:\n");
1360 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1361 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1362 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1366 find_usage_bit
= bit_backwards
;
1367 /* fills in <backwards_match> */
1368 ret
= find_usage_backwards(hlock_class(prev
), 0);
1369 if (!ret
|| ret
== 1)
1372 find_usage_bit
= bit_forwards
;
1373 ret
= find_usage_forwards(hlock_class(next
), 0);
1374 if (!ret
|| ret
== 1)
1377 return print_bad_irq_dependency(curr
, prev
, next
,
1378 bit_backwards
, bit_forwards
, irqclass
);
1381 static const char *state_names
[] = {
1382 #define LOCKDEP_STATE(__STATE) \
1383 __stringify(__STATE),
1384 #include "lockdep_states.h"
1385 #undef LOCKDEP_STATE
1388 static const char *state_rnames
[] = {
1389 #define LOCKDEP_STATE(__STATE) \
1390 __stringify(__STATE)"-READ",
1391 #include "lockdep_states.h"
1392 #undef LOCKDEP_STATE
1395 static inline const char *state_name(enum lock_usage_bit bit
)
1397 return (bit
& 1) ? state_rnames
[bit
>> 2] : state_names
[bit
>> 2];
1400 static int exclusive_bit(int new_bit
)
1408 * bit 0 - write/read
1409 * bit 1 - used_in/enabled
1413 int state
= new_bit
& ~3;
1414 int dir
= new_bit
& 2;
1417 * keep state, bit flip the direction and strip read.
1419 return state
| (dir
^ 2);
1422 static int check_irq_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1423 struct held_lock
*next
, enum lock_usage_bit bit
)
1426 * Prove that the new dependency does not connect a hardirq-safe
1427 * lock with a hardirq-unsafe lock - to achieve this we search
1428 * the backwards-subgraph starting at <prev>, and the
1429 * forwards-subgraph starting at <next>:
1431 if (!check_usage(curr
, prev
, next
, bit
,
1432 exclusive_bit(bit
), state_name(bit
)))
1438 * Prove that the new dependency does not connect a hardirq-safe-read
1439 * lock with a hardirq-unsafe lock - to achieve this we search
1440 * the backwards-subgraph starting at <prev>, and the
1441 * forwards-subgraph starting at <next>:
1443 if (!check_usage(curr
, prev
, next
, bit
,
1444 exclusive_bit(bit
), state_name(bit
)))
1451 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1452 struct held_lock
*next
)
1454 #define LOCKDEP_STATE(__STATE) \
1455 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1457 #include "lockdep_states.h"
1458 #undef LOCKDEP_STATE
1463 static void inc_chains(void)
1465 if (current
->hardirq_context
)
1466 nr_hardirq_chains
++;
1468 if (current
->softirq_context
)
1469 nr_softirq_chains
++;
1471 nr_process_chains
++;
1478 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1479 struct held_lock
*next
)
1484 static inline void inc_chains(void)
1486 nr_process_chains
++;
1492 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1493 struct held_lock
*next
)
1495 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1498 printk("\n=============================================\n");
1499 printk( "[ INFO: possible recursive locking detected ]\n");
1500 print_kernel_version();
1501 printk( "---------------------------------------------\n");
1502 printk("%s/%d is trying to acquire lock:\n",
1503 curr
->comm
, task_pid_nr(curr
));
1505 printk("\nbut task is already holding lock:\n");
1508 printk("\nother info that might help us debug this:\n");
1509 lockdep_print_held_locks(curr
);
1511 printk("\nstack backtrace:\n");
1518 * Check whether we are holding such a class already.
1520 * (Note that this has to be done separately, because the graph cannot
1521 * detect such classes of deadlocks.)
1523 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1526 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1527 struct lockdep_map
*next_instance
, int read
)
1529 struct held_lock
*prev
;
1530 struct held_lock
*nest
= NULL
;
1533 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1534 prev
= curr
->held_locks
+ i
;
1536 if (prev
->instance
== next
->nest_lock
)
1539 if (hlock_class(prev
) != hlock_class(next
))
1543 * Allow read-after-read recursion of the same
1544 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1546 if ((read
== 2) && prev
->read
)
1550 * We're holding the nest_lock, which serializes this lock's
1551 * nesting behaviour.
1556 return print_deadlock_bug(curr
, prev
, next
);
1562 * There was a chain-cache miss, and we are about to add a new dependency
1563 * to a previous lock. We recursively validate the following rules:
1565 * - would the adding of the <prev> -> <next> dependency create a
1566 * circular dependency in the graph? [== circular deadlock]
1568 * - does the new prev->next dependency connect any hardirq-safe lock
1569 * (in the full backwards-subgraph starting at <prev>) with any
1570 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1571 * <next>)? [== illegal lock inversion with hardirq contexts]
1573 * - does the new prev->next dependency connect any softirq-safe lock
1574 * (in the full backwards-subgraph starting at <prev>) with any
1575 * softirq-unsafe lock (in the full forwards-subgraph starting at
1576 * <next>)? [== illegal lock inversion with softirq contexts]
1578 * any of these scenarios could lead to a deadlock.
1580 * Then if all the validations pass, we add the forwards and backwards
1584 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1585 struct held_lock
*next
, int distance
)
1587 struct lock_list
*entry
;
1591 * Prove that the new <prev> -> <next> dependency would not
1592 * create a circular dependency in the graph. (We do this by
1593 * forward-recursing into the graph starting at <next>, and
1594 * checking whether we can reach <prev>.)
1596 * We are using global variables to control the recursion, to
1597 * keep the stackframe size of the recursive functions low:
1599 check_source
= next
;
1600 check_target
= prev
;
1602 if (check_noncircular(hlock_class(next
), 0) == 2)
1603 return print_circular_bug();
1605 if (!check_prev_add_irq(curr
, prev
, next
))
1609 * For recursive read-locks we do all the dependency checks,
1610 * but we dont store read-triggered dependencies (only
1611 * write-triggered dependencies). This ensures that only the
1612 * write-side dependencies matter, and that if for example a
1613 * write-lock never takes any other locks, then the reads are
1614 * equivalent to a NOP.
1616 if (next
->read
== 2 || prev
->read
== 2)
1619 * Is the <prev> -> <next> dependency already present?
1621 * (this may occur even though this is a new chain: consider
1622 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1623 * chains - the second one will be new, but L1 already has
1624 * L2 added to its dependency list, due to the first chain.)
1626 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1627 if (entry
->class == hlock_class(next
)) {
1629 entry
->distance
= 1;
1635 * Ok, all validations passed, add the new lock
1636 * to the previous lock's dependency list:
1638 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1639 &hlock_class(prev
)->locks_after
,
1640 next
->acquire_ip
, distance
);
1645 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1646 &hlock_class(next
)->locks_before
,
1647 next
->acquire_ip
, distance
);
1652 * Debugging printouts:
1654 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1656 printk("\n new dependency: ");
1657 print_lock_name(hlock_class(prev
));
1659 print_lock_name(hlock_class(next
));
1662 return graph_lock();
1668 * Add the dependency to all directly-previous locks that are 'relevant'.
1669 * The ones that are relevant are (in increasing distance from curr):
1670 * all consecutive trylock entries and the final non-trylock entry - or
1671 * the end of this context's lock-chain - whichever comes first.
1674 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1676 int depth
= curr
->lockdep_depth
;
1677 struct held_lock
*hlock
;
1682 * Depth must not be zero for a non-head lock:
1687 * At least two relevant locks must exist for this
1690 if (curr
->held_locks
[depth
].irq_context
!=
1691 curr
->held_locks
[depth
-1].irq_context
)
1695 int distance
= curr
->lockdep_depth
- depth
+ 1;
1696 hlock
= curr
->held_locks
+ depth
-1;
1698 * Only non-recursive-read entries get new dependencies
1701 if (hlock
->read
!= 2) {
1702 if (!check_prev_add(curr
, hlock
, next
, distance
))
1705 * Stop after the first non-trylock entry,
1706 * as non-trylock entries have added their
1707 * own direct dependencies already, so this
1708 * lock is connected to them indirectly:
1710 if (!hlock
->trylock
)
1715 * End of lock-stack?
1720 * Stop the search if we cross into another context:
1722 if (curr
->held_locks
[depth
].irq_context
!=
1723 curr
->held_locks
[depth
-1].irq_context
)
1728 if (!debug_locks_off_graph_unlock())
1736 unsigned long nr_lock_chains
;
1737 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1738 int nr_chain_hlocks
;
1739 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1741 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1743 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1747 * Look up a dependency chain. If the key is not present yet then
1748 * add it and return 1 - in this case the new dependency chain is
1749 * validated. If the key is already hashed, return 0.
1750 * (On return with 1 graph_lock is held.)
1752 static inline int lookup_chain_cache(struct task_struct
*curr
,
1753 struct held_lock
*hlock
,
1756 struct lock_class
*class = hlock_class(hlock
);
1757 struct list_head
*hash_head
= chainhashentry(chain_key
);
1758 struct lock_chain
*chain
;
1759 struct held_lock
*hlock_curr
, *hlock_next
;
1762 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1765 * We can walk it lock-free, because entries only get added
1768 list_for_each_entry(chain
, hash_head
, entry
) {
1769 if (chain
->chain_key
== chain_key
) {
1771 debug_atomic_inc(&chain_lookup_hits
);
1772 if (very_verbose(class))
1773 printk("\nhash chain already cached, key: "
1774 "%016Lx tail class: [%p] %s\n",
1775 (unsigned long long)chain_key
,
1776 class->key
, class->name
);
1780 if (very_verbose(class))
1781 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1782 (unsigned long long)chain_key
, class->key
, class->name
);
1784 * Allocate a new chain entry from the static array, and add
1790 * We have to walk the chain again locked - to avoid duplicates:
1792 list_for_each_entry(chain
, hash_head
, entry
) {
1793 if (chain
->chain_key
== chain_key
) {
1798 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1799 if (!debug_locks_off_graph_unlock())
1802 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1803 printk("turning off the locking correctness validator.\n");
1807 chain
= lock_chains
+ nr_lock_chains
++;
1808 chain
->chain_key
= chain_key
;
1809 chain
->irq_context
= hlock
->irq_context
;
1810 /* Find the first held_lock of current chain */
1812 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
1813 hlock_curr
= curr
->held_locks
+ i
;
1814 if (hlock_curr
->irq_context
!= hlock_next
->irq_context
)
1819 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
1820 cn
= nr_chain_hlocks
;
1821 while (cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
) {
1822 n
= cmpxchg(&nr_chain_hlocks
, cn
, cn
+ chain
->depth
);
1827 if (likely(cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
1829 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
1830 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
1831 chain_hlocks
[chain
->base
+ j
] = lock_id
;
1833 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
1835 list_add_tail_rcu(&chain
->entry
, hash_head
);
1836 debug_atomic_inc(&chain_lookup_misses
);
1842 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
1843 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
1846 * Trylock needs to maintain the stack of held locks, but it
1847 * does not add new dependencies, because trylock can be done
1850 * We look up the chain_key and do the O(N^2) check and update of
1851 * the dependencies only if this is a new dependency chain.
1852 * (If lookup_chain_cache() returns with 1 it acquires
1853 * graph_lock for us)
1855 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
1856 lookup_chain_cache(curr
, hlock
, chain_key
)) {
1858 * Check whether last held lock:
1860 * - is irq-safe, if this lock is irq-unsafe
1861 * - is softirq-safe, if this lock is hardirq-unsafe
1863 * And check whether the new lock's dependency graph
1864 * could lead back to the previous lock.
1866 * any of these scenarios could lead to a deadlock. If
1869 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
1874 * Mark recursive read, as we jump over it when
1875 * building dependencies (just like we jump over
1881 * Add dependency only if this lock is not the head
1882 * of the chain, and if it's not a secondary read-lock:
1884 if (!chain_head
&& ret
!= 2)
1885 if (!check_prevs_add(curr
, hlock
))
1889 /* after lookup_chain_cache(): */
1890 if (unlikely(!debug_locks
))
1896 static inline int validate_chain(struct task_struct
*curr
,
1897 struct lockdep_map
*lock
, struct held_lock
*hlock
,
1898 int chain_head
, u64 chain_key
)
1905 * We are building curr_chain_key incrementally, so double-check
1906 * it from scratch, to make sure that it's done correctly:
1908 static void check_chain_key(struct task_struct
*curr
)
1910 #ifdef CONFIG_DEBUG_LOCKDEP
1911 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1915 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1916 hlock
= curr
->held_locks
+ i
;
1917 if (chain_key
!= hlock
->prev_chain_key
) {
1919 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1920 curr
->lockdep_depth
, i
,
1921 (unsigned long long)chain_key
,
1922 (unsigned long long)hlock
->prev_chain_key
);
1925 id
= hlock
->class_idx
- 1;
1926 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
1929 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1930 hlock
->irq_context
))
1932 chain_key
= iterate_chain_key(chain_key
, id
);
1935 if (chain_key
!= curr
->curr_chain_key
) {
1937 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1938 curr
->lockdep_depth
, i
,
1939 (unsigned long long)chain_key
,
1940 (unsigned long long)curr
->curr_chain_key
);
1946 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1947 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1949 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1952 printk("\n=================================\n");
1953 printk( "[ INFO: inconsistent lock state ]\n");
1954 print_kernel_version();
1955 printk( "---------------------------------\n");
1957 printk("inconsistent {%s} -> {%s} usage.\n",
1958 usage_str
[prev_bit
], usage_str
[new_bit
]);
1960 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1961 curr
->comm
, task_pid_nr(curr
),
1962 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1963 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1964 trace_hardirqs_enabled(curr
),
1965 trace_softirqs_enabled(curr
));
1968 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1969 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
1971 print_irqtrace_events(curr
);
1972 printk("\nother info that might help us debug this:\n");
1973 lockdep_print_held_locks(curr
);
1975 printk("\nstack backtrace:\n");
1982 * Print out an error if an invalid bit is set:
1985 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1986 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1988 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
1989 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1993 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1994 enum lock_usage_bit new_bit
);
1996 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1999 * print irq inversion bug:
2002 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
2003 struct held_lock
*this, int forwards
,
2004 const char *irqclass
)
2006 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2009 printk("\n=========================================================\n");
2010 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
2011 print_kernel_version();
2012 printk( "---------------------------------------------------------\n");
2013 printk("%s/%d just changed the state of lock:\n",
2014 curr
->comm
, task_pid_nr(curr
));
2017 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass
);
2019 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass
);
2020 print_lock_name(other
);
2021 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2023 printk("\nother info that might help us debug this:\n");
2024 lockdep_print_held_locks(curr
);
2026 printk("\nthe first lock's dependencies:\n");
2027 print_lock_dependencies(hlock_class(this), 0);
2029 printk("\nthe second lock's dependencies:\n");
2030 print_lock_dependencies(other
, 0);
2032 printk("\nstack backtrace:\n");
2039 * Prove that in the forwards-direction subgraph starting at <this>
2040 * there is no lock matching <mask>:
2043 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
2044 enum lock_usage_bit bit
, const char *irqclass
)
2048 find_usage_bit
= bit
;
2049 /* fills in <forwards_match> */
2050 ret
= find_usage_forwards(hlock_class(this), 0);
2051 if (!ret
|| ret
== 1)
2054 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
2058 * Prove that in the backwards-direction subgraph starting at <this>
2059 * there is no lock matching <mask>:
2062 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
2063 enum lock_usage_bit bit
, const char *irqclass
)
2067 find_usage_bit
= bit
;
2068 /* fills in <backwards_match> */
2069 ret
= find_usage_backwards(hlock_class(this), 0);
2070 if (!ret
|| ret
== 1)
2073 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
2076 void print_irqtrace_events(struct task_struct
*curr
)
2078 printk("irq event stamp: %u\n", curr
->irq_events
);
2079 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
2080 print_ip_sym(curr
->hardirq_enable_ip
);
2081 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
2082 print_ip_sym(curr
->hardirq_disable_ip
);
2083 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
2084 print_ip_sym(curr
->softirq_enable_ip
);
2085 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
2086 print_ip_sym(curr
->softirq_disable_ip
);
2089 static int HARDIRQ_verbose(struct lock_class
*class)
2092 return class_filter(class);
2097 static int SOFTIRQ_verbose(struct lock_class
*class)
2100 return class_filter(class);
2105 static int RECLAIM_FS_verbose(struct lock_class
*class)
2108 return class_filter(class);
2113 #define STRICT_READ_CHECKS 1
2115 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2116 #define LOCKDEP_STATE(__STATE) \
2118 #include "lockdep_states.h"
2119 #undef LOCKDEP_STATE
2122 static inline int state_verbose(enum lock_usage_bit bit
,
2123 struct lock_class
*class)
2125 return state_verbose_f
[bit
>> 2](class);
2128 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2129 enum lock_usage_bit bit
, const char *name
);
2132 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2133 enum lock_usage_bit new_bit
)
2135 int excl_bit
= exclusive_bit(new_bit
);
2136 int read
= new_bit
& 1;
2137 int dir
= new_bit
& 2;
2140 * mark USED_IN has to look forwards -- to ensure no dependency
2141 * has ENABLED state, which would allow recursion deadlocks.
2143 * mark ENABLED has to look backwards -- to ensure no dependee
2144 * has USED_IN state, which, again, would allow recursion deadlocks.
2146 check_usage_f usage
= dir
?
2147 check_usage_backwards
: check_usage_forwards
;
2150 * Validate that this particular lock does not have conflicting
2153 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2157 * Validate that the lock dependencies don't have conflicting usage
2160 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2161 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2165 * Check for read in write conflicts
2168 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2171 if (STRICT_READ_CHECKS
&&
2172 !usage(curr
, this, excl_bit
+ 1,
2173 state_name(new_bit
+ 1)))
2177 if (state_verbose(new_bit
, hlock_class(this)))
2184 #define LOCKDEP_STATE(__STATE) __STATE,
2185 #include "lockdep_states.h"
2186 #undef LOCKDEP_STATE
2190 * Mark all held locks with a usage bit:
2193 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2195 enum lock_usage_bit usage_bit
;
2196 struct held_lock
*hlock
;
2199 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2200 hlock
= curr
->held_locks
+ i
;
2202 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2204 usage_bit
+= 1; /* READ */
2206 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2208 if (!mark_lock(curr
, hlock
, usage_bit
))
2216 * Debugging helper: via this flag we know that we are in
2217 * 'early bootup code', and will warn about any invalid irqs-on event:
2219 static int early_boot_irqs_enabled
;
2221 void early_boot_irqs_off(void)
2223 early_boot_irqs_enabled
= 0;
2226 void early_boot_irqs_on(void)
2228 early_boot_irqs_enabled
= 1;
2232 * Hardirqs will be enabled:
2234 void trace_hardirqs_on_caller(unsigned long ip
)
2236 struct task_struct
*curr
= current
;
2238 time_hardirqs_on(CALLER_ADDR0
, ip
);
2240 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2243 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
2246 if (unlikely(curr
->hardirqs_enabled
)) {
2247 debug_atomic_inc(&redundant_hardirqs_on
);
2250 /* we'll do an OFF -> ON transition: */
2251 curr
->hardirqs_enabled
= 1;
2253 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2255 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2258 * We are going to turn hardirqs on, so set the
2259 * usage bit for all held locks:
2261 if (!mark_held_locks(curr
, HARDIRQ
))
2264 * If we have softirqs enabled, then set the usage
2265 * bit for all held locks. (disabled hardirqs prevented
2266 * this bit from being set before)
2268 if (curr
->softirqs_enabled
)
2269 if (!mark_held_locks(curr
, SOFTIRQ
))
2272 curr
->hardirq_enable_ip
= ip
;
2273 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2274 debug_atomic_inc(&hardirqs_on_events
);
2276 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2278 void trace_hardirqs_on(void)
2280 trace_hardirqs_on_caller(CALLER_ADDR0
);
2282 EXPORT_SYMBOL(trace_hardirqs_on
);
2285 * Hardirqs were disabled:
2287 void trace_hardirqs_off_caller(unsigned long ip
)
2289 struct task_struct
*curr
= current
;
2291 time_hardirqs_off(CALLER_ADDR0
, ip
);
2293 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2296 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2299 if (curr
->hardirqs_enabled
) {
2301 * We have done an ON -> OFF transition:
2303 curr
->hardirqs_enabled
= 0;
2304 curr
->hardirq_disable_ip
= ip
;
2305 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2306 debug_atomic_inc(&hardirqs_off_events
);
2308 debug_atomic_inc(&redundant_hardirqs_off
);
2310 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2312 void trace_hardirqs_off(void)
2314 trace_hardirqs_off_caller(CALLER_ADDR0
);
2316 EXPORT_SYMBOL(trace_hardirqs_off
);
2319 * Softirqs will be enabled:
2321 void trace_softirqs_on(unsigned long ip
)
2323 struct task_struct
*curr
= current
;
2325 if (unlikely(!debug_locks
))
2328 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2331 if (curr
->softirqs_enabled
) {
2332 debug_atomic_inc(&redundant_softirqs_on
);
2337 * We'll do an OFF -> ON transition:
2339 curr
->softirqs_enabled
= 1;
2340 curr
->softirq_enable_ip
= ip
;
2341 curr
->softirq_enable_event
= ++curr
->irq_events
;
2342 debug_atomic_inc(&softirqs_on_events
);
2344 * We are going to turn softirqs on, so set the
2345 * usage bit for all held locks, if hardirqs are
2348 if (curr
->hardirqs_enabled
)
2349 mark_held_locks(curr
, SOFTIRQ
);
2353 * Softirqs were disabled:
2355 void trace_softirqs_off(unsigned long ip
)
2357 struct task_struct
*curr
= current
;
2359 if (unlikely(!debug_locks
))
2362 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2365 if (curr
->softirqs_enabled
) {
2367 * We have done an ON -> OFF transition:
2369 curr
->softirqs_enabled
= 0;
2370 curr
->softirq_disable_ip
= ip
;
2371 curr
->softirq_disable_event
= ++curr
->irq_events
;
2372 debug_atomic_inc(&softirqs_off_events
);
2373 DEBUG_LOCKS_WARN_ON(!softirq_count());
2375 debug_atomic_inc(&redundant_softirqs_off
);
2378 static void __lockdep_trace_alloc(gfp_t gfp_mask
, unsigned long flags
)
2380 struct task_struct
*curr
= current
;
2382 if (unlikely(!debug_locks
))
2385 /* no reclaim without waiting on it */
2386 if (!(gfp_mask
& __GFP_WAIT
))
2389 /* this guy won't enter reclaim */
2390 if ((curr
->flags
& PF_MEMALLOC
) && !(gfp_mask
& __GFP_NOMEMALLOC
))
2393 /* We're only interested __GFP_FS allocations for now */
2394 if (!(gfp_mask
& __GFP_FS
))
2397 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags
)))
2400 mark_held_locks(curr
, RECLAIM_FS
);
2403 static void check_flags(unsigned long flags
);
2405 void lockdep_trace_alloc(gfp_t gfp_mask
)
2407 unsigned long flags
;
2409 if (unlikely(current
->lockdep_recursion
))
2412 raw_local_irq_save(flags
);
2414 current
->lockdep_recursion
= 1;
2415 __lockdep_trace_alloc(gfp_mask
, flags
);
2416 current
->lockdep_recursion
= 0;
2417 raw_local_irq_restore(flags
);
2420 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2423 * If non-trylock use in a hardirq or softirq context, then
2424 * mark the lock as used in these contexts:
2426 if (!hlock
->trylock
) {
2428 if (curr
->hardirq_context
)
2429 if (!mark_lock(curr
, hlock
,
2430 LOCK_USED_IN_HARDIRQ_READ
))
2432 if (curr
->softirq_context
)
2433 if (!mark_lock(curr
, hlock
,
2434 LOCK_USED_IN_SOFTIRQ_READ
))
2437 if (curr
->hardirq_context
)
2438 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2440 if (curr
->softirq_context
)
2441 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2445 if (!hlock
->hardirqs_off
) {
2447 if (!mark_lock(curr
, hlock
,
2448 LOCK_ENABLED_HARDIRQ_READ
))
2450 if (curr
->softirqs_enabled
)
2451 if (!mark_lock(curr
, hlock
,
2452 LOCK_ENABLED_SOFTIRQ_READ
))
2455 if (!mark_lock(curr
, hlock
,
2456 LOCK_ENABLED_HARDIRQ
))
2458 if (curr
->softirqs_enabled
)
2459 if (!mark_lock(curr
, hlock
,
2460 LOCK_ENABLED_SOFTIRQ
))
2466 * We reuse the irq context infrastructure more broadly as a general
2467 * context checking code. This tests GFP_FS recursion (a lock taken
2468 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2471 if (!hlock
->trylock
&& (curr
->lockdep_reclaim_gfp
& __GFP_FS
)) {
2473 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS_READ
))
2476 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS
))
2484 static int separate_irq_context(struct task_struct
*curr
,
2485 struct held_lock
*hlock
)
2487 unsigned int depth
= curr
->lockdep_depth
;
2490 * Keep track of points where we cross into an interrupt context:
2492 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2493 curr
->softirq_context
;
2495 struct held_lock
*prev_hlock
;
2497 prev_hlock
= curr
->held_locks
+ depth
-1;
2499 * If we cross into another context, reset the
2500 * hash key (this also prevents the checking and the
2501 * adding of the dependency to 'prev'):
2503 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2512 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2513 enum lock_usage_bit new_bit
)
2519 static inline int mark_irqflags(struct task_struct
*curr
,
2520 struct held_lock
*hlock
)
2525 static inline int separate_irq_context(struct task_struct
*curr
,
2526 struct held_lock
*hlock
)
2531 void lockdep_trace_alloc(gfp_t gfp_mask
)
2538 * Mark a lock with a usage bit, and validate the state transition:
2540 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2541 enum lock_usage_bit new_bit
)
2543 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2546 * If already set then do not dirty the cacheline,
2547 * nor do any checks:
2549 if (likely(hlock_class(this)->usage_mask
& new_mask
))
2555 * Make sure we didnt race:
2557 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
2562 hlock_class(this)->usage_mask
|= new_mask
;
2564 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
2568 #define LOCKDEP_STATE(__STATE) \
2569 case LOCK_USED_IN_##__STATE: \
2570 case LOCK_USED_IN_##__STATE##_READ: \
2571 case LOCK_ENABLED_##__STATE: \
2572 case LOCK_ENABLED_##__STATE##_READ:
2573 #include "lockdep_states.h"
2574 #undef LOCKDEP_STATE
2575 ret
= mark_lock_irq(curr
, this, new_bit
);
2580 debug_atomic_dec(&nr_unused_locks
);
2583 if (!debug_locks_off_graph_unlock())
2592 * We must printk outside of the graph_lock:
2595 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2597 print_irqtrace_events(curr
);
2605 * Initialize a lock instance's lock-class mapping info:
2607 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2608 struct lock_class_key
*key
, int subclass
)
2610 lock
->class_cache
= NULL
;
2611 #ifdef CONFIG_LOCK_STAT
2612 lock
->cpu
= raw_smp_processor_id();
2615 if (DEBUG_LOCKS_WARN_ON(!name
)) {
2616 lock
->name
= "NULL";
2622 if (DEBUG_LOCKS_WARN_ON(!key
))
2625 * Sanity check, the lock-class key must be persistent:
2627 if (!static_obj(key
)) {
2628 printk("BUG: key %p not in .data!\n", key
);
2629 DEBUG_LOCKS_WARN_ON(1);
2634 if (unlikely(!debug_locks
))
2638 register_lock_class(lock
, subclass
, 1);
2640 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2643 * This gets called for every mutex_lock*()/spin_lock*() operation.
2644 * We maintain the dependency maps and validate the locking attempt:
2646 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2647 int trylock
, int read
, int check
, int hardirqs_off
,
2648 struct lockdep_map
*nest_lock
, unsigned long ip
)
2650 struct task_struct
*curr
= current
;
2651 struct lock_class
*class = NULL
;
2652 struct held_lock
*hlock
;
2653 unsigned int depth
, id
;
2660 if (unlikely(!debug_locks
))
2663 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2666 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
2668 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2669 printk("turning off the locking correctness validator.\n");
2675 class = lock
->class_cache
;
2677 * Not cached yet or subclass?
2679 if (unlikely(!class)) {
2680 class = register_lock_class(lock
, subclass
, 0);
2684 debug_atomic_inc((atomic_t
*)&class->ops
);
2685 if (very_verbose(class)) {
2686 printk("\nacquire class [%p] %s", class->key
, class->name
);
2687 if (class->name_version
> 1)
2688 printk("#%d", class->name_version
);
2694 * Add the lock to the list of currently held locks.
2695 * (we dont increase the depth just yet, up until the
2696 * dependency checks are done)
2698 depth
= curr
->lockdep_depth
;
2699 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2702 hlock
= curr
->held_locks
+ depth
;
2703 if (DEBUG_LOCKS_WARN_ON(!class))
2705 hlock
->class_idx
= class - lock_classes
+ 1;
2706 hlock
->acquire_ip
= ip
;
2707 hlock
->instance
= lock
;
2708 hlock
->nest_lock
= nest_lock
;
2709 hlock
->trylock
= trylock
;
2711 hlock
->check
= check
;
2712 hlock
->hardirqs_off
= !!hardirqs_off
;
2713 #ifdef CONFIG_LOCK_STAT
2714 hlock
->waittime_stamp
= 0;
2715 hlock
->holdtime_stamp
= sched_clock();
2718 if (check
== 2 && !mark_irqflags(curr
, hlock
))
2721 /* mark it as used: */
2722 if (!mark_lock(curr
, hlock
, LOCK_USED
))
2726 * Calculate the chain hash: it's the combined hash of all the
2727 * lock keys along the dependency chain. We save the hash value
2728 * at every step so that we can get the current hash easily
2729 * after unlock. The chain hash is then used to cache dependency
2732 * The 'key ID' is what is the most compact key value to drive
2733 * the hash, not class->key.
2735 id
= class - lock_classes
;
2736 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2739 chain_key
= curr
->curr_chain_key
;
2741 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2746 hlock
->prev_chain_key
= chain_key
;
2747 if (separate_irq_context(curr
, hlock
)) {
2751 chain_key
= iterate_chain_key(chain_key
, id
);
2753 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
2756 curr
->curr_chain_key
= chain_key
;
2757 curr
->lockdep_depth
++;
2758 check_chain_key(curr
);
2759 #ifdef CONFIG_DEBUG_LOCKDEP
2760 if (unlikely(!debug_locks
))
2763 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2765 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2766 printk("turning off the locking correctness validator.\n");
2771 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2772 max_lockdep_depth
= curr
->lockdep_depth
;
2778 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2781 if (!debug_locks_off())
2783 if (debug_locks_silent
)
2786 printk("\n=====================================\n");
2787 printk( "[ BUG: bad unlock balance detected! ]\n");
2788 printk( "-------------------------------------\n");
2789 printk("%s/%d is trying to release lock (",
2790 curr
->comm
, task_pid_nr(curr
));
2791 print_lockdep_cache(lock
);
2794 printk("but there are no more locks to release!\n");
2795 printk("\nother info that might help us debug this:\n");
2796 lockdep_print_held_locks(curr
);
2798 printk("\nstack backtrace:\n");
2805 * Common debugging checks for both nested and non-nested unlock:
2807 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2810 if (unlikely(!debug_locks
))
2812 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2815 if (curr
->lockdep_depth
<= 0)
2816 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2822 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
2823 struct lock_class_key
*key
, unsigned int subclass
,
2826 struct task_struct
*curr
= current
;
2827 struct held_lock
*hlock
, *prev_hlock
;
2828 struct lock_class
*class;
2832 depth
= curr
->lockdep_depth
;
2833 if (DEBUG_LOCKS_WARN_ON(!depth
))
2837 for (i
= depth
-1; i
>= 0; i
--) {
2838 hlock
= curr
->held_locks
+ i
;
2840 * We must not cross into another context:
2842 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2844 if (hlock
->instance
== lock
)
2848 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2851 lockdep_init_map(lock
, name
, key
, 0);
2852 class = register_lock_class(lock
, subclass
, 0);
2853 hlock
->class_idx
= class - lock_classes
+ 1;
2855 curr
->lockdep_depth
= i
;
2856 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2858 for (; i
< depth
; i
++) {
2859 hlock
= curr
->held_locks
+ i
;
2860 if (!__lock_acquire(hlock
->instance
,
2861 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2862 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2863 hlock
->nest_lock
, hlock
->acquire_ip
))
2867 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
2873 * Remove the lock to the list of currently held locks in a
2874 * potentially non-nested (out of order) manner. This is a
2875 * relatively rare operation, as all the unlock APIs default
2876 * to nested mode (which uses lock_release()):
2879 lock_release_non_nested(struct task_struct
*curr
,
2880 struct lockdep_map
*lock
, unsigned long ip
)
2882 struct held_lock
*hlock
, *prev_hlock
;
2887 * Check whether the lock exists in the current stack
2890 depth
= curr
->lockdep_depth
;
2891 if (DEBUG_LOCKS_WARN_ON(!depth
))
2895 for (i
= depth
-1; i
>= 0; i
--) {
2896 hlock
= curr
->held_locks
+ i
;
2898 * We must not cross into another context:
2900 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2902 if (hlock
->instance
== lock
)
2906 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2909 lock_release_holdtime(hlock
);
2912 * We have the right lock to unlock, 'hlock' points to it.
2913 * Now we remove it from the stack, and add back the other
2914 * entries (if any), recalculating the hash along the way:
2916 curr
->lockdep_depth
= i
;
2917 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2919 for (i
++; i
< depth
; i
++) {
2920 hlock
= curr
->held_locks
+ i
;
2921 if (!__lock_acquire(hlock
->instance
,
2922 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2923 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2924 hlock
->nest_lock
, hlock
->acquire_ip
))
2928 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2934 * Remove the lock to the list of currently held locks - this gets
2935 * called on mutex_unlock()/spin_unlock*() (or on a failed
2936 * mutex_lock_interruptible()). This is done for unlocks that nest
2937 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2939 static int lock_release_nested(struct task_struct
*curr
,
2940 struct lockdep_map
*lock
, unsigned long ip
)
2942 struct held_lock
*hlock
;
2946 * Pop off the top of the lock stack:
2948 depth
= curr
->lockdep_depth
- 1;
2949 hlock
= curr
->held_locks
+ depth
;
2952 * Is the unlock non-nested:
2954 if (hlock
->instance
!= lock
)
2955 return lock_release_non_nested(curr
, lock
, ip
);
2956 curr
->lockdep_depth
--;
2958 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2961 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2963 lock_release_holdtime(hlock
);
2965 #ifdef CONFIG_DEBUG_LOCKDEP
2966 hlock
->prev_chain_key
= 0;
2967 hlock
->class_idx
= 0;
2968 hlock
->acquire_ip
= 0;
2969 hlock
->irq_context
= 0;
2975 * Remove the lock to the list of currently held locks - this gets
2976 * called on mutex_unlock()/spin_unlock*() (or on a failed
2977 * mutex_lock_interruptible()). This is done for unlocks that nest
2978 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2981 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2983 struct task_struct
*curr
= current
;
2985 if (!check_unlock(curr
, lock
, ip
))
2989 if (!lock_release_nested(curr
, lock
, ip
))
2992 if (!lock_release_non_nested(curr
, lock
, ip
))
2996 check_chain_key(curr
);
3000 * Check whether we follow the irq-flags state precisely:
3002 static void check_flags(unsigned long flags
)
3004 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3005 defined(CONFIG_TRACE_IRQFLAGS)
3009 if (irqs_disabled_flags(flags
)) {
3010 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
3011 printk("possible reason: unannotated irqs-off.\n");
3014 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
3015 printk("possible reason: unannotated irqs-on.\n");
3020 * We dont accurately track softirq state in e.g.
3021 * hardirq contexts (such as on 4KSTACKS), so only
3022 * check if not in hardirq contexts:
3024 if (!hardirq_count()) {
3025 if (softirq_count())
3026 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
3028 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
3032 print_irqtrace_events(current
);
3036 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
3037 struct lock_class_key
*key
, unsigned int subclass
,
3040 unsigned long flags
;
3042 if (unlikely(current
->lockdep_recursion
))
3045 raw_local_irq_save(flags
);
3046 current
->lockdep_recursion
= 1;
3048 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
3049 check_chain_key(current
);
3050 current
->lockdep_recursion
= 0;
3051 raw_local_irq_restore(flags
);
3053 EXPORT_SYMBOL_GPL(lock_set_class
);
3056 * We are not always called with irqs disabled - do that here,
3057 * and also avoid lockdep recursion:
3059 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3060 int trylock
, int read
, int check
,
3061 struct lockdep_map
*nest_lock
, unsigned long ip
)
3063 unsigned long flags
;
3065 trace_lock_acquire(lock
, subclass
, trylock
, read
, check
, nest_lock
, ip
);
3067 if (unlikely(current
->lockdep_recursion
))
3070 raw_local_irq_save(flags
);
3073 current
->lockdep_recursion
= 1;
3074 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
3075 irqs_disabled_flags(flags
), nest_lock
, ip
);
3076 current
->lockdep_recursion
= 0;
3077 raw_local_irq_restore(flags
);
3079 EXPORT_SYMBOL_GPL(lock_acquire
);
3081 void lock_release(struct lockdep_map
*lock
, int nested
,
3084 unsigned long flags
;
3086 trace_lock_release(lock
, nested
, ip
);
3088 if (unlikely(current
->lockdep_recursion
))
3091 raw_local_irq_save(flags
);
3093 current
->lockdep_recursion
= 1;
3094 __lock_release(lock
, nested
, ip
);
3095 current
->lockdep_recursion
= 0;
3096 raw_local_irq_restore(flags
);
3098 EXPORT_SYMBOL_GPL(lock_release
);
3100 void lockdep_set_current_reclaim_state(gfp_t gfp_mask
)
3102 current
->lockdep_reclaim_gfp
= gfp_mask
;
3105 void lockdep_clear_current_reclaim_state(void)
3107 current
->lockdep_reclaim_gfp
= 0;
3110 #ifdef CONFIG_LOCK_STAT
3112 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3115 if (!debug_locks_off())
3117 if (debug_locks_silent
)
3120 printk("\n=================================\n");
3121 printk( "[ BUG: bad contention detected! ]\n");
3122 printk( "---------------------------------\n");
3123 printk("%s/%d is trying to contend lock (",
3124 curr
->comm
, task_pid_nr(curr
));
3125 print_lockdep_cache(lock
);
3128 printk("but there are no locks held!\n");
3129 printk("\nother info that might help us debug this:\n");
3130 lockdep_print_held_locks(curr
);
3132 printk("\nstack backtrace:\n");
3139 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3141 struct task_struct
*curr
= current
;
3142 struct held_lock
*hlock
, *prev_hlock
;
3143 struct lock_class_stats
*stats
;
3145 int i
, contention_point
, contending_point
;
3147 depth
= curr
->lockdep_depth
;
3148 if (DEBUG_LOCKS_WARN_ON(!depth
))
3152 for (i
= depth
-1; i
>= 0; i
--) {
3153 hlock
= curr
->held_locks
+ i
;
3155 * We must not cross into another context:
3157 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3159 if (hlock
->instance
== lock
)
3163 print_lock_contention_bug(curr
, lock
, ip
);
3167 hlock
->waittime_stamp
= sched_clock();
3169 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3170 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3173 stats
= get_lock_stats(hlock_class(hlock
));
3174 if (contention_point
< LOCKSTAT_POINTS
)
3175 stats
->contention_point
[contention_point
]++;
3176 if (contending_point
< LOCKSTAT_POINTS
)
3177 stats
->contending_point
[contending_point
]++;
3178 if (lock
->cpu
!= smp_processor_id())
3179 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3180 put_lock_stats(stats
);
3184 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3186 struct task_struct
*curr
= current
;
3187 struct held_lock
*hlock
, *prev_hlock
;
3188 struct lock_class_stats
*stats
;
3194 depth
= curr
->lockdep_depth
;
3195 if (DEBUG_LOCKS_WARN_ON(!depth
))
3199 for (i
= depth
-1; i
>= 0; i
--) {
3200 hlock
= curr
->held_locks
+ i
;
3202 * We must not cross into another context:
3204 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3206 if (hlock
->instance
== lock
)
3210 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3214 cpu
= smp_processor_id();
3215 if (hlock
->waittime_stamp
) {
3216 now
= sched_clock();
3217 waittime
= now
- hlock
->waittime_stamp
;
3218 hlock
->holdtime_stamp
= now
;
3221 trace_lock_acquired(lock
, ip
, waittime
);
3223 stats
= get_lock_stats(hlock_class(hlock
));
3226 lock_time_inc(&stats
->read_waittime
, waittime
);
3228 lock_time_inc(&stats
->write_waittime
, waittime
);
3230 if (lock
->cpu
!= cpu
)
3231 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3232 put_lock_stats(stats
);
3238 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3240 unsigned long flags
;
3242 trace_lock_contended(lock
, ip
);
3244 if (unlikely(!lock_stat
))
3247 if (unlikely(current
->lockdep_recursion
))
3250 raw_local_irq_save(flags
);
3252 current
->lockdep_recursion
= 1;
3253 __lock_contended(lock
, ip
);
3254 current
->lockdep_recursion
= 0;
3255 raw_local_irq_restore(flags
);
3257 EXPORT_SYMBOL_GPL(lock_contended
);
3259 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3261 unsigned long flags
;
3263 if (unlikely(!lock_stat
))
3266 if (unlikely(current
->lockdep_recursion
))
3269 raw_local_irq_save(flags
);
3271 current
->lockdep_recursion
= 1;
3272 __lock_acquired(lock
, ip
);
3273 current
->lockdep_recursion
= 0;
3274 raw_local_irq_restore(flags
);
3276 EXPORT_SYMBOL_GPL(lock_acquired
);
3280 * Used by the testsuite, sanitize the validator state
3281 * after a simulated failure:
3284 void lockdep_reset(void)
3286 unsigned long flags
;
3289 raw_local_irq_save(flags
);
3290 current
->curr_chain_key
= 0;
3291 current
->lockdep_depth
= 0;
3292 current
->lockdep_recursion
= 0;
3293 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3294 nr_hardirq_chains
= 0;
3295 nr_softirq_chains
= 0;
3296 nr_process_chains
= 0;
3298 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3299 INIT_LIST_HEAD(chainhash_table
+ i
);
3300 raw_local_irq_restore(flags
);
3303 static void zap_class(struct lock_class
*class)
3308 * Remove all dependencies this lock is
3311 for (i
= 0; i
< nr_list_entries
; i
++) {
3312 if (list_entries
[i
].class == class)
3313 list_del_rcu(&list_entries
[i
].entry
);
3316 * Unhash the class and remove it from the all_lock_classes list:
3318 list_del_rcu(&class->hash_entry
);
3319 list_del_rcu(&class->lock_entry
);
3324 static inline int within(const void *addr
, void *start
, unsigned long size
)
3326 return addr
>= start
&& addr
< start
+ size
;
3329 void lockdep_free_key_range(void *start
, unsigned long size
)
3331 struct lock_class
*class, *next
;
3332 struct list_head
*head
;
3333 unsigned long flags
;
3337 raw_local_irq_save(flags
);
3338 locked
= graph_lock();
3341 * Unhash all classes that were created by this module:
3343 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3344 head
= classhash_table
+ i
;
3345 if (list_empty(head
))
3347 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3348 if (within(class->key
, start
, size
))
3350 else if (within(class->name
, start
, size
))
3357 raw_local_irq_restore(flags
);
3360 void lockdep_reset_lock(struct lockdep_map
*lock
)
3362 struct lock_class
*class, *next
;
3363 struct list_head
*head
;
3364 unsigned long flags
;
3368 raw_local_irq_save(flags
);
3371 * Remove all classes this lock might have:
3373 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3375 * If the class exists we look it up and zap it:
3377 class = look_up_lock_class(lock
, j
);
3382 * Debug check: in the end all mapped classes should
3385 locked
= graph_lock();
3386 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3387 head
= classhash_table
+ i
;
3388 if (list_empty(head
))
3390 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3391 if (unlikely(class == lock
->class_cache
)) {
3392 if (debug_locks_off_graph_unlock())
3402 raw_local_irq_restore(flags
);
3405 void lockdep_init(void)
3410 * Some architectures have their own start_kernel()
3411 * code which calls lockdep_init(), while we also
3412 * call lockdep_init() from the start_kernel() itself,
3413 * and we want to initialize the hashes only once:
3415 if (lockdep_initialized
)
3418 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3419 INIT_LIST_HEAD(classhash_table
+ i
);
3421 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3422 INIT_LIST_HEAD(chainhash_table
+ i
);
3424 lockdep_initialized
= 1;
3427 void __init
lockdep_info(void)
3429 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3431 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
3432 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
3433 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
3434 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
3435 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
3436 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
3437 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
3439 printk(" memory used by lock dependency info: %lu kB\n",
3440 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
3441 sizeof(struct list_head
) * CLASSHASH_SIZE
+
3442 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
3443 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
3444 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
3446 printk(" per task-struct memory footprint: %lu bytes\n",
3447 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
3449 #ifdef CONFIG_DEBUG_LOCKDEP
3450 if (lockdep_init_error
) {
3451 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3452 printk("Call stack leading to lockdep invocation was:\n");
3453 print_stack_trace(&lockdep_init_trace
, 0);
3459 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
3460 const void *mem_to
, struct held_lock
*hlock
)
3462 if (!debug_locks_off())
3464 if (debug_locks_silent
)
3467 printk("\n=========================\n");
3468 printk( "[ BUG: held lock freed! ]\n");
3469 printk( "-------------------------\n");
3470 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3471 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
3473 lockdep_print_held_locks(curr
);
3475 printk("\nstack backtrace:\n");
3479 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
3480 const void* lock_from
, unsigned long lock_len
)
3482 return lock_from
+ lock_len
<= mem_from
||
3483 mem_from
+ mem_len
<= lock_from
;
3487 * Called when kernel memory is freed (or unmapped), or if a lock
3488 * is destroyed or reinitialized - this code checks whether there is
3489 * any held lock in the memory range of <from> to <to>:
3491 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
3493 struct task_struct
*curr
= current
;
3494 struct held_lock
*hlock
;
3495 unsigned long flags
;
3498 if (unlikely(!debug_locks
))
3501 local_irq_save(flags
);
3502 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3503 hlock
= curr
->held_locks
+ i
;
3505 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
3506 sizeof(*hlock
->instance
)))
3509 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
3512 local_irq_restore(flags
);
3514 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
3516 static void print_held_locks_bug(struct task_struct
*curr
)
3518 if (!debug_locks_off())
3520 if (debug_locks_silent
)
3523 printk("\n=====================================\n");
3524 printk( "[ BUG: lock held at task exit time! ]\n");
3525 printk( "-------------------------------------\n");
3526 printk("%s/%d is exiting with locks still held!\n",
3527 curr
->comm
, task_pid_nr(curr
));
3528 lockdep_print_held_locks(curr
);
3530 printk("\nstack backtrace:\n");
3534 void debug_check_no_locks_held(struct task_struct
*task
)
3536 if (unlikely(task
->lockdep_depth
> 0))
3537 print_held_locks_bug(task
);
3540 void debug_show_all_locks(void)
3542 struct task_struct
*g
, *p
;
3546 if (unlikely(!debug_locks
)) {
3547 printk("INFO: lockdep is turned off.\n");
3550 printk("\nShowing all locks held in the system:\n");
3553 * Here we try to get the tasklist_lock as hard as possible,
3554 * if not successful after 2 seconds we ignore it (but keep
3555 * trying). This is to enable a debug printout even if a
3556 * tasklist_lock-holding task deadlocks or crashes.
3559 if (!read_trylock(&tasklist_lock
)) {
3561 printk("hm, tasklist_lock locked, retrying... ");
3564 printk(" #%d", 10-count
);
3568 printk(" ignoring it.\n");
3572 printk(KERN_CONT
" locked it.\n");
3575 do_each_thread(g
, p
) {
3577 * It's not reliable to print a task's held locks
3578 * if it's not sleeping (or if it's not the current
3581 if (p
->state
== TASK_RUNNING
&& p
!= current
)
3583 if (p
->lockdep_depth
)
3584 lockdep_print_held_locks(p
);
3586 if (read_trylock(&tasklist_lock
))
3588 } while_each_thread(g
, p
);
3591 printk("=============================================\n\n");
3594 read_unlock(&tasklist_lock
);
3596 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
3599 * Careful: only use this function if you are sure that
3600 * the task cannot run in parallel!
3602 void __debug_show_held_locks(struct task_struct
*task
)
3604 if (unlikely(!debug_locks
)) {
3605 printk("INFO: lockdep is turned off.\n");
3608 lockdep_print_held_locks(task
);
3610 EXPORT_SYMBOL_GPL(__debug_show_held_locks
);
3612 void debug_show_held_locks(struct task_struct
*task
)
3614 __debug_show_held_locks(task
);
3616 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
3618 void lockdep_sys_exit(void)
3620 struct task_struct
*curr
= current
;
3622 if (unlikely(curr
->lockdep_depth
)) {
3623 if (!debug_locks_off())
3625 printk("\n================================================\n");
3626 printk( "[ BUG: lock held when returning to user space! ]\n");
3627 printk( "------------------------------------------------\n");
3628 printk("%s/%d is leaving the kernel with locks still held!\n",
3629 curr
->comm
, curr
->pid
);
3630 lockdep_print_held_locks(curr
);