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 the shortest lock dependencies from @start to @end in reverse order:
582 print_shortest_lock_dependencies(struct lock_list
*leaf
,
583 struct lock_list
*root
)
585 struct lock_list
*entry
= leaf
;
588 /*compute depth from generated tree by BFS*/
589 depth
= get_lock_depth(leaf
);
592 print_lock_class_header(entry
->class, depth
);
593 printk("%*s ... acquired at:\n", depth
, "");
594 print_stack_trace(&entry
->trace
, 2);
597 if (depth
== 0 && (entry
!= root
)) {
598 printk("lockdep:%s bad BFS generated tree\n", __func__
);
602 entry
= get_lock_parent(entry
);
604 } while (entry
&& (depth
>= 0));
609 * printk all lock dependencies starting at <entry>:
612 print_lock_dependencies(struct lock_class
*class, int depth
)
614 struct lock_list
*entry
;
616 if (lockdep_dependency_visit(class, depth
))
619 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
622 print_lock_class_header(class, depth
);
624 list_for_each_entry(entry
, &class->locks_after
, entry
) {
625 if (DEBUG_LOCKS_WARN_ON(!entry
->class))
628 print_lock_dependencies(entry
->class, depth
+ 1);
630 printk("%*s ... acquired at:\n",depth
,"");
631 print_stack_trace(&entry
->trace
, 2);
636 static void print_kernel_version(void)
638 printk("%s %.*s\n", init_utsname()->release
,
639 (int)strcspn(init_utsname()->version
, " "),
640 init_utsname()->version
);
643 static int very_verbose(struct lock_class
*class)
646 return class_filter(class);
652 * Is this the address of a static object:
654 static int static_obj(void *obj
)
656 unsigned long start
= (unsigned long) &_stext
,
657 end
= (unsigned long) &_end
,
658 addr
= (unsigned long) obj
;
666 if ((addr
>= start
) && (addr
< end
))
673 for_each_possible_cpu(i
) {
674 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
675 end
= (unsigned long) &__per_cpu_start
+ PERCPU_ENOUGH_ROOM
678 if ((addr
>= start
) && (addr
< end
))
686 return is_module_address(addr
);
690 * To make lock name printouts unique, we calculate a unique
691 * class->name_version generation counter:
693 static int count_matching_names(struct lock_class
*new_class
)
695 struct lock_class
*class;
698 if (!new_class
->name
)
701 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
702 if (new_class
->key
- new_class
->subclass
== class->key
)
703 return class->name_version
;
704 if (class->name
&& !strcmp(class->name
, new_class
->name
))
705 count
= max(count
, class->name_version
);
712 * Register a lock's class in the hash-table, if the class is not present
713 * yet. Otherwise we look it up. We cache the result in the lock object
714 * itself, so actual lookup of the hash should be once per lock object.
716 static inline struct lock_class
*
717 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
719 struct lockdep_subclass_key
*key
;
720 struct list_head
*hash_head
;
721 struct lock_class
*class;
723 #ifdef CONFIG_DEBUG_LOCKDEP
725 * If the architecture calls into lockdep before initializing
726 * the hashes then we'll warn about it later. (we cannot printk
729 if (unlikely(!lockdep_initialized
)) {
731 lockdep_init_error
= 1;
732 save_stack_trace(&lockdep_init_trace
);
737 * Static locks do not have their class-keys yet - for them the key
738 * is the lock object itself:
740 if (unlikely(!lock
->key
))
741 lock
->key
= (void *)lock
;
744 * NOTE: the class-key must be unique. For dynamic locks, a static
745 * lock_class_key variable is passed in through the mutex_init()
746 * (or spin_lock_init()) call - which acts as the key. For static
747 * locks we use the lock object itself as the key.
749 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
750 sizeof(struct lockdep_map
));
752 key
= lock
->key
->subkeys
+ subclass
;
754 hash_head
= classhashentry(key
);
757 * We can walk the hash lockfree, because the hash only
758 * grows, and we are careful when adding entries to the end:
760 list_for_each_entry(class, hash_head
, hash_entry
) {
761 if (class->key
== key
) {
762 WARN_ON_ONCE(class->name
!= lock
->name
);
771 * Register a lock's class in the hash-table, if the class is not present
772 * yet. Otherwise we look it up. We cache the result in the lock object
773 * itself, so actual lookup of the hash should be once per lock object.
775 static inline struct lock_class
*
776 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
778 struct lockdep_subclass_key
*key
;
779 struct list_head
*hash_head
;
780 struct lock_class
*class;
783 class = look_up_lock_class(lock
, subclass
);
788 * Debug-check: all keys must be persistent!
790 if (!static_obj(lock
->key
)) {
792 printk("INFO: trying to register non-static key.\n");
793 printk("the code is fine but needs lockdep annotation.\n");
794 printk("turning off the locking correctness validator.\n");
800 key
= lock
->key
->subkeys
+ subclass
;
801 hash_head
= classhashentry(key
);
803 raw_local_irq_save(flags
);
805 raw_local_irq_restore(flags
);
809 * We have to do the hash-walk again, to avoid races
812 list_for_each_entry(class, hash_head
, hash_entry
)
813 if (class->key
== key
)
816 * Allocate a new key from the static array, and add it to
819 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
820 if (!debug_locks_off_graph_unlock()) {
821 raw_local_irq_restore(flags
);
824 raw_local_irq_restore(flags
);
826 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
827 printk("turning off the locking correctness validator.\n");
831 class = lock_classes
+ nr_lock_classes
++;
832 debug_atomic_inc(&nr_unused_locks
);
834 class->name
= lock
->name
;
835 class->subclass
= subclass
;
836 INIT_LIST_HEAD(&class->lock_entry
);
837 INIT_LIST_HEAD(&class->locks_before
);
838 INIT_LIST_HEAD(&class->locks_after
);
839 class->name_version
= count_matching_names(class);
841 * We use RCU's safe list-add method to make
842 * parallel walking of the hash-list safe:
844 list_add_tail_rcu(&class->hash_entry
, hash_head
);
846 * Add it to the global list of classes:
848 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
850 if (verbose(class)) {
852 raw_local_irq_restore(flags
);
854 printk("\nnew class %p: %s", class->key
, class->name
);
855 if (class->name_version
> 1)
856 printk("#%d", class->name_version
);
860 raw_local_irq_save(flags
);
862 raw_local_irq_restore(flags
);
868 raw_local_irq_restore(flags
);
870 if (!subclass
|| force
)
871 lock
->class_cache
= class;
873 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
879 #ifdef CONFIG_PROVE_LOCKING
881 * Allocate a lockdep entry. (assumes the graph_lock held, returns
882 * with NULL on failure)
884 static struct lock_list
*alloc_list_entry(void)
886 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
887 if (!debug_locks_off_graph_unlock())
890 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
891 printk("turning off the locking correctness validator.\n");
895 return list_entries
+ nr_list_entries
++;
899 * Add a new dependency to the head of the list:
901 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
902 struct list_head
*head
, unsigned long ip
, int distance
)
904 struct lock_list
*entry
;
906 * Lock not present yet - get a new dependency struct and
907 * add it to the list:
909 entry
= alloc_list_entry();
913 if (!save_trace(&entry
->trace
))
917 entry
->distance
= distance
;
919 * Since we never remove from the dependency list, the list can
920 * be walked lockless by other CPUs, it's only allocation
921 * that must be protected by the spinlock. But this also means
922 * we must make new entries visible only once writes to the
923 * entry become visible - hence the RCU op:
925 list_add_tail_rcu(&entry
->entry
, head
);
930 unsigned long bfs_accessed
[BITS_TO_LONGS(MAX_LOCKDEP_ENTRIES
)];
931 static struct circular_queue lock_cq
;
933 static int __bfs(struct lock_list
*source_entry
,
935 int (*match
)(struct lock_list
*entry
, void *data
),
936 struct lock_list
**target_entry
,
939 struct lock_list
*entry
;
940 struct list_head
*head
;
941 struct circular_queue
*cq
= &lock_cq
;
944 if (match(source_entry
, data
)) {
945 *target_entry
= source_entry
;
951 head
= &source_entry
->class->locks_after
;
953 head
= &source_entry
->class->locks_before
;
955 if (list_empty(head
))
959 __cq_enqueue(cq
, (unsigned long)source_entry
);
961 while (!__cq_empty(cq
)) {
962 struct lock_list
*lock
;
964 __cq_dequeue(cq
, (unsigned long *)&lock
);
972 head
= &lock
->class->locks_after
;
974 head
= &lock
->class->locks_before
;
976 list_for_each_entry(entry
, head
, entry
) {
977 if (!lock_accessed(entry
)) {
978 mark_lock_accessed(entry
, lock
);
979 if (match(entry
, data
)) {
980 *target_entry
= entry
;
985 if (__cq_enqueue(cq
, (unsigned long)entry
)) {
996 static inline int __bfs_forwards(struct lock_list
*src_entry
,
998 int (*match
)(struct lock_list
*entry
, void *data
),
999 struct lock_list
**target_entry
)
1001 return __bfs(src_entry
, data
, match
, target_entry
, 1);
1005 static inline int __bfs_backwards(struct lock_list
*src_entry
,
1007 int (*match
)(struct lock_list
*entry
, void *data
),
1008 struct lock_list
**target_entry
)
1010 return __bfs(src_entry
, data
, match
, target_entry
, 0);
1015 * Recursive, forwards-direction lock-dependency checking, used for
1016 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1021 * Print a dependency chain entry (this is only done when a deadlock
1022 * has been detected):
1025 print_circular_bug_entry(struct lock_list
*target
, int depth
)
1027 if (debug_locks_silent
)
1029 printk("\n-> #%u", depth
);
1030 print_lock_name(target
->class);
1032 print_stack_trace(&target
->trace
, 6);
1038 * When a circular dependency is detected, print the
1042 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
,
1043 struct held_lock
*check_src
,
1044 struct held_lock
*check_tgt
)
1046 struct task_struct
*curr
= current
;
1048 if (debug_locks_silent
)
1051 printk("\n=======================================================\n");
1052 printk( "[ INFO: possible circular locking dependency detected ]\n");
1053 print_kernel_version();
1054 printk( "-------------------------------------------------------\n");
1055 printk("%s/%d is trying to acquire lock:\n",
1056 curr
->comm
, task_pid_nr(curr
));
1057 print_lock(check_src
);
1058 printk("\nbut task is already holding lock:\n");
1059 print_lock(check_tgt
);
1060 printk("\nwhich lock already depends on the new lock.\n\n");
1061 printk("\nthe existing dependency chain (in reverse order) is:\n");
1063 print_circular_bug_entry(entry
, depth
);
1068 static inline int class_equal(struct lock_list
*entry
, void *data
)
1070 return entry
->class == data
;
1073 static noinline
int print_circular_bug(struct lock_list
*this,
1074 struct lock_list
*target
,
1075 struct held_lock
*check_src
,
1076 struct held_lock
*check_tgt
)
1078 struct task_struct
*curr
= current
;
1079 struct lock_list
*parent
;
1082 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1085 if (!save_trace(&this->trace
))
1088 depth
= get_lock_depth(target
);
1090 print_circular_bug_header(target
, depth
, check_src
, check_tgt
);
1092 parent
= get_lock_parent(target
);
1095 print_circular_bug_entry(parent
, --depth
);
1096 parent
= get_lock_parent(parent
);
1099 printk("\nother info that might help us debug this:\n\n");
1100 lockdep_print_held_locks(curr
);
1102 printk("\nstack backtrace:\n");
1108 static noinline
int print_bfs_bug(int ret
)
1110 if (!debug_locks_off_graph_unlock())
1113 WARN(1, "lockdep bfs error:%d\n", ret
);
1118 static int noop_count(struct lock_list
*entry
, void *data
)
1120 (*(unsigned long *)data
)++;
1124 unsigned long __lockdep_count_forward_deps(struct lock_list
*this)
1126 unsigned long count
= 0;
1127 struct lock_list
*uninitialized_var(target_entry
);
1129 __bfs_forwards(this, (void *)&count
, noop_count
, &target_entry
);
1133 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1135 unsigned long ret
, flags
;
1136 struct lock_list
this;
1141 local_irq_save(flags
);
1142 __raw_spin_lock(&lockdep_lock
);
1143 ret
= __lockdep_count_forward_deps(&this);
1144 __raw_spin_unlock(&lockdep_lock
);
1145 local_irq_restore(flags
);
1150 unsigned long __lockdep_count_backward_deps(struct lock_list
*this)
1152 unsigned long count
= 0;
1153 struct lock_list
*uninitialized_var(target_entry
);
1155 __bfs_backwards(this, (void *)&count
, noop_count
, &target_entry
);
1160 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1162 unsigned long ret
, flags
;
1163 struct lock_list
this;
1168 local_irq_save(flags
);
1169 __raw_spin_lock(&lockdep_lock
);
1170 ret
= __lockdep_count_backward_deps(&this);
1171 __raw_spin_unlock(&lockdep_lock
);
1172 local_irq_restore(flags
);
1178 * Prove that the dependency graph starting at <entry> can not
1179 * lead to <target>. Print an error and return 0 if it does.
1182 check_noncircular(struct lock_list
*root
, struct lock_class
*target
,
1183 struct lock_list
**target_entry
)
1187 debug_atomic_inc(&nr_cyclic_checks
);
1189 result
= __bfs_forwards(root
, target
, class_equal
, target_entry
);
1194 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1196 * Forwards and backwards subgraph searching, for the purposes of
1197 * proving that two subgraphs can be connected by a new dependency
1198 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1202 #define BFS_PROCESS_RET(ret) do { \
1204 return print_bfs_bug(ret); \
1209 static inline int usage_match(struct lock_list
*entry
, void *bit
)
1211 return entry
->class->usage_mask
& (1 << (enum lock_usage_bit
)bit
);
1217 * Find a node in the forwards-direction dependency sub-graph starting
1218 * at @root->class that matches @bit.
1220 * Return 0 if such a node exists in the subgraph, and put that node
1221 * into *@target_entry.
1223 * Return 1 otherwise and keep *@target_entry unchanged.
1224 * Return <0 on error.
1227 find_usage_forwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1228 struct lock_list
**target_entry
)
1232 debug_atomic_inc(&nr_find_usage_forwards_checks
);
1234 result
= __bfs_forwards(root
, (void *)bit
, usage_match
, target_entry
);
1240 * Find a node in the backwards-direction dependency sub-graph starting
1241 * at @root->class that matches @bit.
1243 * Return 0 if such a node exists in the subgraph, and put that node
1244 * into *@target_entry.
1246 * Return 1 otherwise and keep *@target_entry unchanged.
1247 * Return <0 on error.
1250 find_usage_backwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1251 struct lock_list
**target_entry
)
1255 debug_atomic_inc(&nr_find_usage_backwards_checks
);
1257 result
= __bfs_backwards(root
, (void *)bit
, usage_match
, target_entry
);
1264 print_bad_irq_dependency(struct task_struct
*curr
,
1265 struct lock_list
*prev_root
,
1266 struct lock_list
*next_root
,
1267 struct lock_list
*backwards_entry
,
1268 struct lock_list
*forwards_entry
,
1269 struct held_lock
*prev
,
1270 struct held_lock
*next
,
1271 enum lock_usage_bit bit1
,
1272 enum lock_usage_bit bit2
,
1273 const char *irqclass
)
1275 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1278 printk("\n======================================================\n");
1279 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1280 irqclass
, irqclass
);
1281 print_kernel_version();
1282 printk( "------------------------------------------------------\n");
1283 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1284 curr
->comm
, task_pid_nr(curr
),
1285 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1286 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1287 curr
->hardirqs_enabled
,
1288 curr
->softirqs_enabled
);
1291 printk("\nand this task is already holding:\n");
1293 printk("which would create a new lock dependency:\n");
1294 print_lock_name(hlock_class(prev
));
1296 print_lock_name(hlock_class(next
));
1299 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1301 print_lock_name(backwards_entry
->class);
1302 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1304 print_stack_trace(backwards_entry
->class->usage_traces
+ bit1
, 1);
1306 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1307 print_lock_name(forwards_entry
->class);
1308 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1311 print_stack_trace(forwards_entry
->class->usage_traces
+ bit2
, 1);
1313 printk("\nother info that might help us debug this:\n\n");
1314 lockdep_print_held_locks(curr
);
1316 printk("\nthe dependencies between %s-irq-safe lock", irqclass
);
1317 printk(" and the holding lock:\n");
1318 if (!save_trace(&prev_root
->trace
))
1320 print_shortest_lock_dependencies(backwards_entry
, prev_root
);
1322 printk("\nthe dependencies between the lock to be acquired");
1323 printk(" and %s-irq-unsafe lock:\n", irqclass
);
1324 if (!save_trace(&next_root
->trace
))
1326 print_shortest_lock_dependencies(forwards_entry
, next_root
);
1328 printk("\nstack backtrace:\n");
1335 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1336 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1337 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1340 struct lock_list
this, that
;
1341 struct lock_list
*uninitialized_var(target_entry
);
1342 struct lock_list
*uninitialized_var(target_entry1
);
1346 this.class = hlock_class(prev
);
1347 ret
= find_usage_backwards(&this, bit_backwards
, &target_entry
);
1348 BFS_PROCESS_RET(ret
);
1351 that
.class = hlock_class(next
);
1352 ret
= find_usage_forwards(&that
, bit_forwards
, &target_entry1
);
1353 BFS_PROCESS_RET(ret
);
1355 return print_bad_irq_dependency(curr
, &this, &that
,
1356 target_entry
, target_entry1
,
1358 bit_backwards
, bit_forwards
, irqclass
);
1361 static const char *state_names
[] = {
1362 #define LOCKDEP_STATE(__STATE) \
1363 __stringify(__STATE),
1364 #include "lockdep_states.h"
1365 #undef LOCKDEP_STATE
1368 static const char *state_rnames
[] = {
1369 #define LOCKDEP_STATE(__STATE) \
1370 __stringify(__STATE)"-READ",
1371 #include "lockdep_states.h"
1372 #undef LOCKDEP_STATE
1375 static inline const char *state_name(enum lock_usage_bit bit
)
1377 return (bit
& 1) ? state_rnames
[bit
>> 2] : state_names
[bit
>> 2];
1380 static int exclusive_bit(int new_bit
)
1388 * bit 0 - write/read
1389 * bit 1 - used_in/enabled
1393 int state
= new_bit
& ~3;
1394 int dir
= new_bit
& 2;
1397 * keep state, bit flip the direction and strip read.
1399 return state
| (dir
^ 2);
1402 static int check_irq_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1403 struct held_lock
*next
, enum lock_usage_bit bit
)
1406 * Prove that the new dependency does not connect a hardirq-safe
1407 * lock with a hardirq-unsafe lock - to achieve this we search
1408 * the backwards-subgraph starting at <prev>, and the
1409 * forwards-subgraph starting at <next>:
1411 if (!check_usage(curr
, prev
, next
, bit
,
1412 exclusive_bit(bit
), state_name(bit
)))
1418 * Prove that the new dependency does not connect a hardirq-safe-read
1419 * lock with a hardirq-unsafe lock - to achieve this we search
1420 * the backwards-subgraph starting at <prev>, and the
1421 * forwards-subgraph starting at <next>:
1423 if (!check_usage(curr
, prev
, next
, bit
,
1424 exclusive_bit(bit
), state_name(bit
)))
1431 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1432 struct held_lock
*next
)
1434 #define LOCKDEP_STATE(__STATE) \
1435 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1437 #include "lockdep_states.h"
1438 #undef LOCKDEP_STATE
1443 static void inc_chains(void)
1445 if (current
->hardirq_context
)
1446 nr_hardirq_chains
++;
1448 if (current
->softirq_context
)
1449 nr_softirq_chains
++;
1451 nr_process_chains
++;
1458 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1459 struct held_lock
*next
)
1464 static inline void inc_chains(void)
1466 nr_process_chains
++;
1472 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1473 struct held_lock
*next
)
1475 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1478 printk("\n=============================================\n");
1479 printk( "[ INFO: possible recursive locking detected ]\n");
1480 print_kernel_version();
1481 printk( "---------------------------------------------\n");
1482 printk("%s/%d is trying to acquire lock:\n",
1483 curr
->comm
, task_pid_nr(curr
));
1485 printk("\nbut task is already holding lock:\n");
1488 printk("\nother info that might help us debug this:\n");
1489 lockdep_print_held_locks(curr
);
1491 printk("\nstack backtrace:\n");
1498 * Check whether we are holding such a class already.
1500 * (Note that this has to be done separately, because the graph cannot
1501 * detect such classes of deadlocks.)
1503 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1506 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1507 struct lockdep_map
*next_instance
, int read
)
1509 struct held_lock
*prev
;
1510 struct held_lock
*nest
= NULL
;
1513 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1514 prev
= curr
->held_locks
+ i
;
1516 if (prev
->instance
== next
->nest_lock
)
1519 if (hlock_class(prev
) != hlock_class(next
))
1523 * Allow read-after-read recursion of the same
1524 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1526 if ((read
== 2) && prev
->read
)
1530 * We're holding the nest_lock, which serializes this lock's
1531 * nesting behaviour.
1536 return print_deadlock_bug(curr
, prev
, next
);
1542 * There was a chain-cache miss, and we are about to add a new dependency
1543 * to a previous lock. We recursively validate the following rules:
1545 * - would the adding of the <prev> -> <next> dependency create a
1546 * circular dependency in the graph? [== circular deadlock]
1548 * - does the new prev->next dependency connect any hardirq-safe lock
1549 * (in the full backwards-subgraph starting at <prev>) with any
1550 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1551 * <next>)? [== illegal lock inversion with hardirq contexts]
1553 * - does the new prev->next dependency connect any softirq-safe lock
1554 * (in the full backwards-subgraph starting at <prev>) with any
1555 * softirq-unsafe lock (in the full forwards-subgraph starting at
1556 * <next>)? [== illegal lock inversion with softirq contexts]
1558 * any of these scenarios could lead to a deadlock.
1560 * Then if all the validations pass, we add the forwards and backwards
1564 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1565 struct held_lock
*next
, int distance
)
1567 struct lock_list
*entry
;
1569 struct lock_list
this;
1570 struct lock_list
*uninitialized_var(target_entry
);
1573 * Prove that the new <prev> -> <next> dependency would not
1574 * create a circular dependency in the graph. (We do this by
1575 * forward-recursing into the graph starting at <next>, and
1576 * checking whether we can reach <prev>.)
1578 * We are using global variables to control the recursion, to
1579 * keep the stackframe size of the recursive functions low:
1581 this.class = hlock_class(next
);
1583 ret
= check_noncircular(&this, hlock_class(prev
), &target_entry
);
1585 return print_circular_bug(&this, target_entry
, next
, prev
);
1586 else if (unlikely(ret
< 0))
1587 return print_bfs_bug(ret
);
1589 if (!check_prev_add_irq(curr
, prev
, next
))
1593 * For recursive read-locks we do all the dependency checks,
1594 * but we dont store read-triggered dependencies (only
1595 * write-triggered dependencies). This ensures that only the
1596 * write-side dependencies matter, and that if for example a
1597 * write-lock never takes any other locks, then the reads are
1598 * equivalent to a NOP.
1600 if (next
->read
== 2 || prev
->read
== 2)
1603 * Is the <prev> -> <next> dependency already present?
1605 * (this may occur even though this is a new chain: consider
1606 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1607 * chains - the second one will be new, but L1 already has
1608 * L2 added to its dependency list, due to the first chain.)
1610 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1611 if (entry
->class == hlock_class(next
)) {
1613 entry
->distance
= 1;
1619 * Ok, all validations passed, add the new lock
1620 * to the previous lock's dependency list:
1622 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1623 &hlock_class(prev
)->locks_after
,
1624 next
->acquire_ip
, distance
);
1629 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1630 &hlock_class(next
)->locks_before
,
1631 next
->acquire_ip
, distance
);
1636 * Debugging printouts:
1638 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1640 printk("\n new dependency: ");
1641 print_lock_name(hlock_class(prev
));
1643 print_lock_name(hlock_class(next
));
1646 return graph_lock();
1652 * Add the dependency to all directly-previous locks that are 'relevant'.
1653 * The ones that are relevant are (in increasing distance from curr):
1654 * all consecutive trylock entries and the final non-trylock entry - or
1655 * the end of this context's lock-chain - whichever comes first.
1658 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1660 int depth
= curr
->lockdep_depth
;
1661 struct held_lock
*hlock
;
1666 * Depth must not be zero for a non-head lock:
1671 * At least two relevant locks must exist for this
1674 if (curr
->held_locks
[depth
].irq_context
!=
1675 curr
->held_locks
[depth
-1].irq_context
)
1679 int distance
= curr
->lockdep_depth
- depth
+ 1;
1680 hlock
= curr
->held_locks
+ depth
-1;
1682 * Only non-recursive-read entries get new dependencies
1685 if (hlock
->read
!= 2) {
1686 if (!check_prev_add(curr
, hlock
, next
, distance
))
1689 * Stop after the first non-trylock entry,
1690 * as non-trylock entries have added their
1691 * own direct dependencies already, so this
1692 * lock is connected to them indirectly:
1694 if (!hlock
->trylock
)
1699 * End of lock-stack?
1704 * Stop the search if we cross into another context:
1706 if (curr
->held_locks
[depth
].irq_context
!=
1707 curr
->held_locks
[depth
-1].irq_context
)
1712 if (!debug_locks_off_graph_unlock())
1720 unsigned long nr_lock_chains
;
1721 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1722 int nr_chain_hlocks
;
1723 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1725 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1727 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1731 * Look up a dependency chain. If the key is not present yet then
1732 * add it and return 1 - in this case the new dependency chain is
1733 * validated. If the key is already hashed, return 0.
1734 * (On return with 1 graph_lock is held.)
1736 static inline int lookup_chain_cache(struct task_struct
*curr
,
1737 struct held_lock
*hlock
,
1740 struct lock_class
*class = hlock_class(hlock
);
1741 struct list_head
*hash_head
= chainhashentry(chain_key
);
1742 struct lock_chain
*chain
;
1743 struct held_lock
*hlock_curr
, *hlock_next
;
1746 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1749 * We can walk it lock-free, because entries only get added
1752 list_for_each_entry(chain
, hash_head
, entry
) {
1753 if (chain
->chain_key
== chain_key
) {
1755 debug_atomic_inc(&chain_lookup_hits
);
1756 if (very_verbose(class))
1757 printk("\nhash chain already cached, key: "
1758 "%016Lx tail class: [%p] %s\n",
1759 (unsigned long long)chain_key
,
1760 class->key
, class->name
);
1764 if (very_verbose(class))
1765 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1766 (unsigned long long)chain_key
, class->key
, class->name
);
1768 * Allocate a new chain entry from the static array, and add
1774 * We have to walk the chain again locked - to avoid duplicates:
1776 list_for_each_entry(chain
, hash_head
, entry
) {
1777 if (chain
->chain_key
== chain_key
) {
1782 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1783 if (!debug_locks_off_graph_unlock())
1786 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1787 printk("turning off the locking correctness validator.\n");
1791 chain
= lock_chains
+ nr_lock_chains
++;
1792 chain
->chain_key
= chain_key
;
1793 chain
->irq_context
= hlock
->irq_context
;
1794 /* Find the first held_lock of current chain */
1796 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
1797 hlock_curr
= curr
->held_locks
+ i
;
1798 if (hlock_curr
->irq_context
!= hlock_next
->irq_context
)
1803 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
1804 cn
= nr_chain_hlocks
;
1805 while (cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
) {
1806 n
= cmpxchg(&nr_chain_hlocks
, cn
, cn
+ chain
->depth
);
1811 if (likely(cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
1813 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
1814 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
1815 chain_hlocks
[chain
->base
+ j
] = lock_id
;
1817 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
1819 list_add_tail_rcu(&chain
->entry
, hash_head
);
1820 debug_atomic_inc(&chain_lookup_misses
);
1826 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
1827 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
1830 * Trylock needs to maintain the stack of held locks, but it
1831 * does not add new dependencies, because trylock can be done
1834 * We look up the chain_key and do the O(N^2) check and update of
1835 * the dependencies only if this is a new dependency chain.
1836 * (If lookup_chain_cache() returns with 1 it acquires
1837 * graph_lock for us)
1839 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
1840 lookup_chain_cache(curr
, hlock
, chain_key
)) {
1842 * Check whether last held lock:
1844 * - is irq-safe, if this lock is irq-unsafe
1845 * - is softirq-safe, if this lock is hardirq-unsafe
1847 * And check whether the new lock's dependency graph
1848 * could lead back to the previous lock.
1850 * any of these scenarios could lead to a deadlock. If
1853 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
1858 * Mark recursive read, as we jump over it when
1859 * building dependencies (just like we jump over
1865 * Add dependency only if this lock is not the head
1866 * of the chain, and if it's not a secondary read-lock:
1868 if (!chain_head
&& ret
!= 2)
1869 if (!check_prevs_add(curr
, hlock
))
1873 /* after lookup_chain_cache(): */
1874 if (unlikely(!debug_locks
))
1880 static inline int validate_chain(struct task_struct
*curr
,
1881 struct lockdep_map
*lock
, struct held_lock
*hlock
,
1882 int chain_head
, u64 chain_key
)
1889 * We are building curr_chain_key incrementally, so double-check
1890 * it from scratch, to make sure that it's done correctly:
1892 static void check_chain_key(struct task_struct
*curr
)
1894 #ifdef CONFIG_DEBUG_LOCKDEP
1895 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1899 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1900 hlock
= curr
->held_locks
+ i
;
1901 if (chain_key
!= hlock
->prev_chain_key
) {
1903 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1904 curr
->lockdep_depth
, i
,
1905 (unsigned long long)chain_key
,
1906 (unsigned long long)hlock
->prev_chain_key
);
1909 id
= hlock
->class_idx
- 1;
1910 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
1913 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1914 hlock
->irq_context
))
1916 chain_key
= iterate_chain_key(chain_key
, id
);
1919 if (chain_key
!= curr
->curr_chain_key
) {
1921 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1922 curr
->lockdep_depth
, i
,
1923 (unsigned long long)chain_key
,
1924 (unsigned long long)curr
->curr_chain_key
);
1930 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1931 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1933 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1936 printk("\n=================================\n");
1937 printk( "[ INFO: inconsistent lock state ]\n");
1938 print_kernel_version();
1939 printk( "---------------------------------\n");
1941 printk("inconsistent {%s} -> {%s} usage.\n",
1942 usage_str
[prev_bit
], usage_str
[new_bit
]);
1944 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1945 curr
->comm
, task_pid_nr(curr
),
1946 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1947 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1948 trace_hardirqs_enabled(curr
),
1949 trace_softirqs_enabled(curr
));
1952 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1953 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
1955 print_irqtrace_events(curr
);
1956 printk("\nother info that might help us debug this:\n");
1957 lockdep_print_held_locks(curr
);
1959 printk("\nstack backtrace:\n");
1966 * Print out an error if an invalid bit is set:
1969 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1970 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1972 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
1973 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1977 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1978 enum lock_usage_bit new_bit
);
1980 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1983 * print irq inversion bug:
1986 print_irq_inversion_bug(struct task_struct
*curr
,
1987 struct lock_list
*root
, struct lock_list
*other
,
1988 struct held_lock
*this, int forwards
,
1989 const char *irqclass
)
1991 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1994 printk("\n=========================================================\n");
1995 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1996 print_kernel_version();
1997 printk( "---------------------------------------------------------\n");
1998 printk("%s/%d just changed the state of lock:\n",
1999 curr
->comm
, task_pid_nr(curr
));
2002 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass
);
2004 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass
);
2005 print_lock_name(other
->class);
2006 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2008 printk("\nother info that might help us debug this:\n");
2009 lockdep_print_held_locks(curr
);
2011 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2012 if (!save_trace(&root
->trace
))
2014 print_shortest_lock_dependencies(other
, root
);
2016 printk("\nstack backtrace:\n");
2023 * Prove that in the forwards-direction subgraph starting at <this>
2024 * there is no lock matching <mask>:
2027 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
2028 enum lock_usage_bit bit
, const char *irqclass
)
2031 struct lock_list root
;
2032 struct lock_list
*uninitialized_var(target_entry
);
2035 root
.class = hlock_class(this);
2036 ret
= find_usage_forwards(&root
, bit
, &target_entry
);
2037 BFS_PROCESS_RET(ret
);
2039 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2044 * Prove that in the backwards-direction subgraph starting at <this>
2045 * there is no lock matching <mask>:
2048 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
2049 enum lock_usage_bit bit
, const char *irqclass
)
2052 struct lock_list root
;
2053 struct lock_list
*uninitialized_var(target_entry
);
2056 root
.class = hlock_class(this);
2057 ret
= find_usage_backwards(&root
, bit
, &target_entry
);
2058 BFS_PROCESS_RET(ret
);
2060 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2064 void print_irqtrace_events(struct task_struct
*curr
)
2066 printk("irq event stamp: %u\n", curr
->irq_events
);
2067 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
2068 print_ip_sym(curr
->hardirq_enable_ip
);
2069 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
2070 print_ip_sym(curr
->hardirq_disable_ip
);
2071 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
2072 print_ip_sym(curr
->softirq_enable_ip
);
2073 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
2074 print_ip_sym(curr
->softirq_disable_ip
);
2077 static int HARDIRQ_verbose(struct lock_class
*class)
2080 return class_filter(class);
2085 static int SOFTIRQ_verbose(struct lock_class
*class)
2088 return class_filter(class);
2093 static int RECLAIM_FS_verbose(struct lock_class
*class)
2096 return class_filter(class);
2101 #define STRICT_READ_CHECKS 1
2103 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2104 #define LOCKDEP_STATE(__STATE) \
2106 #include "lockdep_states.h"
2107 #undef LOCKDEP_STATE
2110 static inline int state_verbose(enum lock_usage_bit bit
,
2111 struct lock_class
*class)
2113 return state_verbose_f
[bit
>> 2](class);
2116 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2117 enum lock_usage_bit bit
, const char *name
);
2120 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2121 enum lock_usage_bit new_bit
)
2123 int excl_bit
= exclusive_bit(new_bit
);
2124 int read
= new_bit
& 1;
2125 int dir
= new_bit
& 2;
2128 * mark USED_IN has to look forwards -- to ensure no dependency
2129 * has ENABLED state, which would allow recursion deadlocks.
2131 * mark ENABLED has to look backwards -- to ensure no dependee
2132 * has USED_IN state, which, again, would allow recursion deadlocks.
2134 check_usage_f usage
= dir
?
2135 check_usage_backwards
: check_usage_forwards
;
2138 * Validate that this particular lock does not have conflicting
2141 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2145 * Validate that the lock dependencies don't have conflicting usage
2148 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2149 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2153 * Check for read in write conflicts
2156 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2159 if (STRICT_READ_CHECKS
&&
2160 !usage(curr
, this, excl_bit
+ 1,
2161 state_name(new_bit
+ 1)))
2165 if (state_verbose(new_bit
, hlock_class(this)))
2172 #define LOCKDEP_STATE(__STATE) __STATE,
2173 #include "lockdep_states.h"
2174 #undef LOCKDEP_STATE
2178 * Mark all held locks with a usage bit:
2181 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2183 enum lock_usage_bit usage_bit
;
2184 struct held_lock
*hlock
;
2187 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2188 hlock
= curr
->held_locks
+ i
;
2190 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2192 usage_bit
+= 1; /* READ */
2194 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2196 if (!mark_lock(curr
, hlock
, usage_bit
))
2204 * Debugging helper: via this flag we know that we are in
2205 * 'early bootup code', and will warn about any invalid irqs-on event:
2207 static int early_boot_irqs_enabled
;
2209 void early_boot_irqs_off(void)
2211 early_boot_irqs_enabled
= 0;
2214 void early_boot_irqs_on(void)
2216 early_boot_irqs_enabled
= 1;
2220 * Hardirqs will be enabled:
2222 void trace_hardirqs_on_caller(unsigned long ip
)
2224 struct task_struct
*curr
= current
;
2226 time_hardirqs_on(CALLER_ADDR0
, ip
);
2228 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2231 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
2234 if (unlikely(curr
->hardirqs_enabled
)) {
2235 debug_atomic_inc(&redundant_hardirqs_on
);
2238 /* we'll do an OFF -> ON transition: */
2239 curr
->hardirqs_enabled
= 1;
2241 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2243 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2246 * We are going to turn hardirqs on, so set the
2247 * usage bit for all held locks:
2249 if (!mark_held_locks(curr
, HARDIRQ
))
2252 * If we have softirqs enabled, then set the usage
2253 * bit for all held locks. (disabled hardirqs prevented
2254 * this bit from being set before)
2256 if (curr
->softirqs_enabled
)
2257 if (!mark_held_locks(curr
, SOFTIRQ
))
2260 curr
->hardirq_enable_ip
= ip
;
2261 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2262 debug_atomic_inc(&hardirqs_on_events
);
2264 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2266 void trace_hardirqs_on(void)
2268 trace_hardirqs_on_caller(CALLER_ADDR0
);
2270 EXPORT_SYMBOL(trace_hardirqs_on
);
2273 * Hardirqs were disabled:
2275 void trace_hardirqs_off_caller(unsigned long ip
)
2277 struct task_struct
*curr
= current
;
2279 time_hardirqs_off(CALLER_ADDR0
, ip
);
2281 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2284 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2287 if (curr
->hardirqs_enabled
) {
2289 * We have done an ON -> OFF transition:
2291 curr
->hardirqs_enabled
= 0;
2292 curr
->hardirq_disable_ip
= ip
;
2293 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2294 debug_atomic_inc(&hardirqs_off_events
);
2296 debug_atomic_inc(&redundant_hardirqs_off
);
2298 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2300 void trace_hardirqs_off(void)
2302 trace_hardirqs_off_caller(CALLER_ADDR0
);
2304 EXPORT_SYMBOL(trace_hardirqs_off
);
2307 * Softirqs will be enabled:
2309 void trace_softirqs_on(unsigned long ip
)
2311 struct task_struct
*curr
= current
;
2313 if (unlikely(!debug_locks
))
2316 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2319 if (curr
->softirqs_enabled
) {
2320 debug_atomic_inc(&redundant_softirqs_on
);
2325 * We'll do an OFF -> ON transition:
2327 curr
->softirqs_enabled
= 1;
2328 curr
->softirq_enable_ip
= ip
;
2329 curr
->softirq_enable_event
= ++curr
->irq_events
;
2330 debug_atomic_inc(&softirqs_on_events
);
2332 * We are going to turn softirqs on, so set the
2333 * usage bit for all held locks, if hardirqs are
2336 if (curr
->hardirqs_enabled
)
2337 mark_held_locks(curr
, SOFTIRQ
);
2341 * Softirqs were disabled:
2343 void trace_softirqs_off(unsigned long ip
)
2345 struct task_struct
*curr
= current
;
2347 if (unlikely(!debug_locks
))
2350 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2353 if (curr
->softirqs_enabled
) {
2355 * We have done an ON -> OFF transition:
2357 curr
->softirqs_enabled
= 0;
2358 curr
->softirq_disable_ip
= ip
;
2359 curr
->softirq_disable_event
= ++curr
->irq_events
;
2360 debug_atomic_inc(&softirqs_off_events
);
2361 DEBUG_LOCKS_WARN_ON(!softirq_count());
2363 debug_atomic_inc(&redundant_softirqs_off
);
2366 static void __lockdep_trace_alloc(gfp_t gfp_mask
, unsigned long flags
)
2368 struct task_struct
*curr
= current
;
2370 if (unlikely(!debug_locks
))
2373 /* no reclaim without waiting on it */
2374 if (!(gfp_mask
& __GFP_WAIT
))
2377 /* this guy won't enter reclaim */
2378 if ((curr
->flags
& PF_MEMALLOC
) && !(gfp_mask
& __GFP_NOMEMALLOC
))
2381 /* We're only interested __GFP_FS allocations for now */
2382 if (!(gfp_mask
& __GFP_FS
))
2385 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags
)))
2388 mark_held_locks(curr
, RECLAIM_FS
);
2391 static void check_flags(unsigned long flags
);
2393 void lockdep_trace_alloc(gfp_t gfp_mask
)
2395 unsigned long flags
;
2397 if (unlikely(current
->lockdep_recursion
))
2400 raw_local_irq_save(flags
);
2402 current
->lockdep_recursion
= 1;
2403 __lockdep_trace_alloc(gfp_mask
, flags
);
2404 current
->lockdep_recursion
= 0;
2405 raw_local_irq_restore(flags
);
2408 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2411 * If non-trylock use in a hardirq or softirq context, then
2412 * mark the lock as used in these contexts:
2414 if (!hlock
->trylock
) {
2416 if (curr
->hardirq_context
)
2417 if (!mark_lock(curr
, hlock
,
2418 LOCK_USED_IN_HARDIRQ_READ
))
2420 if (curr
->softirq_context
)
2421 if (!mark_lock(curr
, hlock
,
2422 LOCK_USED_IN_SOFTIRQ_READ
))
2425 if (curr
->hardirq_context
)
2426 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2428 if (curr
->softirq_context
)
2429 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2433 if (!hlock
->hardirqs_off
) {
2435 if (!mark_lock(curr
, hlock
,
2436 LOCK_ENABLED_HARDIRQ_READ
))
2438 if (curr
->softirqs_enabled
)
2439 if (!mark_lock(curr
, hlock
,
2440 LOCK_ENABLED_SOFTIRQ_READ
))
2443 if (!mark_lock(curr
, hlock
,
2444 LOCK_ENABLED_HARDIRQ
))
2446 if (curr
->softirqs_enabled
)
2447 if (!mark_lock(curr
, hlock
,
2448 LOCK_ENABLED_SOFTIRQ
))
2454 * We reuse the irq context infrastructure more broadly as a general
2455 * context checking code. This tests GFP_FS recursion (a lock taken
2456 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2459 if (!hlock
->trylock
&& (curr
->lockdep_reclaim_gfp
& __GFP_FS
)) {
2461 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS_READ
))
2464 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS
))
2472 static int separate_irq_context(struct task_struct
*curr
,
2473 struct held_lock
*hlock
)
2475 unsigned int depth
= curr
->lockdep_depth
;
2478 * Keep track of points where we cross into an interrupt context:
2480 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2481 curr
->softirq_context
;
2483 struct held_lock
*prev_hlock
;
2485 prev_hlock
= curr
->held_locks
+ depth
-1;
2487 * If we cross into another context, reset the
2488 * hash key (this also prevents the checking and the
2489 * adding of the dependency to 'prev'):
2491 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2500 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2501 enum lock_usage_bit new_bit
)
2507 static inline int mark_irqflags(struct task_struct
*curr
,
2508 struct held_lock
*hlock
)
2513 static inline int separate_irq_context(struct task_struct
*curr
,
2514 struct held_lock
*hlock
)
2519 void lockdep_trace_alloc(gfp_t gfp_mask
)
2526 * Mark a lock with a usage bit, and validate the state transition:
2528 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2529 enum lock_usage_bit new_bit
)
2531 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2534 * If already set then do not dirty the cacheline,
2535 * nor do any checks:
2537 if (likely(hlock_class(this)->usage_mask
& new_mask
))
2543 * Make sure we didnt race:
2545 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
2550 hlock_class(this)->usage_mask
|= new_mask
;
2552 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
2556 #define LOCKDEP_STATE(__STATE) \
2557 case LOCK_USED_IN_##__STATE: \
2558 case LOCK_USED_IN_##__STATE##_READ: \
2559 case LOCK_ENABLED_##__STATE: \
2560 case LOCK_ENABLED_##__STATE##_READ:
2561 #include "lockdep_states.h"
2562 #undef LOCKDEP_STATE
2563 ret
= mark_lock_irq(curr
, this, new_bit
);
2568 debug_atomic_dec(&nr_unused_locks
);
2571 if (!debug_locks_off_graph_unlock())
2580 * We must printk outside of the graph_lock:
2583 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2585 print_irqtrace_events(curr
);
2593 * Initialize a lock instance's lock-class mapping info:
2595 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2596 struct lock_class_key
*key
, int subclass
)
2598 lock
->class_cache
= NULL
;
2599 #ifdef CONFIG_LOCK_STAT
2600 lock
->cpu
= raw_smp_processor_id();
2603 if (DEBUG_LOCKS_WARN_ON(!name
)) {
2604 lock
->name
= "NULL";
2610 if (DEBUG_LOCKS_WARN_ON(!key
))
2613 * Sanity check, the lock-class key must be persistent:
2615 if (!static_obj(key
)) {
2616 printk("BUG: key %p not in .data!\n", key
);
2617 DEBUG_LOCKS_WARN_ON(1);
2622 if (unlikely(!debug_locks
))
2626 register_lock_class(lock
, subclass
, 1);
2628 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2631 * This gets called for every mutex_lock*()/spin_lock*() operation.
2632 * We maintain the dependency maps and validate the locking attempt:
2634 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2635 int trylock
, int read
, int check
, int hardirqs_off
,
2636 struct lockdep_map
*nest_lock
, unsigned long ip
)
2638 struct task_struct
*curr
= current
;
2639 struct lock_class
*class = NULL
;
2640 struct held_lock
*hlock
;
2641 unsigned int depth
, id
;
2648 if (unlikely(!debug_locks
))
2651 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2654 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
2656 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2657 printk("turning off the locking correctness validator.\n");
2663 class = lock
->class_cache
;
2665 * Not cached yet or subclass?
2667 if (unlikely(!class)) {
2668 class = register_lock_class(lock
, subclass
, 0);
2672 debug_atomic_inc((atomic_t
*)&class->ops
);
2673 if (very_verbose(class)) {
2674 printk("\nacquire class [%p] %s", class->key
, class->name
);
2675 if (class->name_version
> 1)
2676 printk("#%d", class->name_version
);
2682 * Add the lock to the list of currently held locks.
2683 * (we dont increase the depth just yet, up until the
2684 * dependency checks are done)
2686 depth
= curr
->lockdep_depth
;
2687 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2690 hlock
= curr
->held_locks
+ depth
;
2691 if (DEBUG_LOCKS_WARN_ON(!class))
2693 hlock
->class_idx
= class - lock_classes
+ 1;
2694 hlock
->acquire_ip
= ip
;
2695 hlock
->instance
= lock
;
2696 hlock
->nest_lock
= nest_lock
;
2697 hlock
->trylock
= trylock
;
2699 hlock
->check
= check
;
2700 hlock
->hardirqs_off
= !!hardirqs_off
;
2701 #ifdef CONFIG_LOCK_STAT
2702 hlock
->waittime_stamp
= 0;
2703 hlock
->holdtime_stamp
= sched_clock();
2706 if (check
== 2 && !mark_irqflags(curr
, hlock
))
2709 /* mark it as used: */
2710 if (!mark_lock(curr
, hlock
, LOCK_USED
))
2714 * Calculate the chain hash: it's the combined hash of all the
2715 * lock keys along the dependency chain. We save the hash value
2716 * at every step so that we can get the current hash easily
2717 * after unlock. The chain hash is then used to cache dependency
2720 * The 'key ID' is what is the most compact key value to drive
2721 * the hash, not class->key.
2723 id
= class - lock_classes
;
2724 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2727 chain_key
= curr
->curr_chain_key
;
2729 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2734 hlock
->prev_chain_key
= chain_key
;
2735 if (separate_irq_context(curr
, hlock
)) {
2739 chain_key
= iterate_chain_key(chain_key
, id
);
2741 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
2744 curr
->curr_chain_key
= chain_key
;
2745 curr
->lockdep_depth
++;
2746 check_chain_key(curr
);
2747 #ifdef CONFIG_DEBUG_LOCKDEP
2748 if (unlikely(!debug_locks
))
2751 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2753 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2754 printk("turning off the locking correctness validator.\n");
2759 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2760 max_lockdep_depth
= curr
->lockdep_depth
;
2766 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2769 if (!debug_locks_off())
2771 if (debug_locks_silent
)
2774 printk("\n=====================================\n");
2775 printk( "[ BUG: bad unlock balance detected! ]\n");
2776 printk( "-------------------------------------\n");
2777 printk("%s/%d is trying to release lock (",
2778 curr
->comm
, task_pid_nr(curr
));
2779 print_lockdep_cache(lock
);
2782 printk("but there are no more locks to release!\n");
2783 printk("\nother info that might help us debug this:\n");
2784 lockdep_print_held_locks(curr
);
2786 printk("\nstack backtrace:\n");
2793 * Common debugging checks for both nested and non-nested unlock:
2795 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2798 if (unlikely(!debug_locks
))
2800 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2803 if (curr
->lockdep_depth
<= 0)
2804 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2810 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
2811 struct lock_class_key
*key
, unsigned int subclass
,
2814 struct task_struct
*curr
= current
;
2815 struct held_lock
*hlock
, *prev_hlock
;
2816 struct lock_class
*class;
2820 depth
= curr
->lockdep_depth
;
2821 if (DEBUG_LOCKS_WARN_ON(!depth
))
2825 for (i
= depth
-1; i
>= 0; i
--) {
2826 hlock
= curr
->held_locks
+ i
;
2828 * We must not cross into another context:
2830 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2832 if (hlock
->instance
== lock
)
2836 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2839 lockdep_init_map(lock
, name
, key
, 0);
2840 class = register_lock_class(lock
, subclass
, 0);
2841 hlock
->class_idx
= class - lock_classes
+ 1;
2843 curr
->lockdep_depth
= i
;
2844 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2846 for (; i
< depth
; i
++) {
2847 hlock
= curr
->held_locks
+ i
;
2848 if (!__lock_acquire(hlock
->instance
,
2849 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2850 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2851 hlock
->nest_lock
, hlock
->acquire_ip
))
2855 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
2861 * Remove the lock to the list of currently held locks in a
2862 * potentially non-nested (out of order) manner. This is a
2863 * relatively rare operation, as all the unlock APIs default
2864 * to nested mode (which uses lock_release()):
2867 lock_release_non_nested(struct task_struct
*curr
,
2868 struct lockdep_map
*lock
, unsigned long ip
)
2870 struct held_lock
*hlock
, *prev_hlock
;
2875 * Check whether the lock exists in the current stack
2878 depth
= curr
->lockdep_depth
;
2879 if (DEBUG_LOCKS_WARN_ON(!depth
))
2883 for (i
= depth
-1; i
>= 0; i
--) {
2884 hlock
= curr
->held_locks
+ i
;
2886 * We must not cross into another context:
2888 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2890 if (hlock
->instance
== lock
)
2894 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2897 lock_release_holdtime(hlock
);
2900 * We have the right lock to unlock, 'hlock' points to it.
2901 * Now we remove it from the stack, and add back the other
2902 * entries (if any), recalculating the hash along the way:
2904 curr
->lockdep_depth
= i
;
2905 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2907 for (i
++; i
< depth
; i
++) {
2908 hlock
= curr
->held_locks
+ i
;
2909 if (!__lock_acquire(hlock
->instance
,
2910 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2911 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2912 hlock
->nest_lock
, hlock
->acquire_ip
))
2916 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2922 * Remove the lock to the list of currently held locks - this gets
2923 * called on mutex_unlock()/spin_unlock*() (or on a failed
2924 * mutex_lock_interruptible()). This is done for unlocks that nest
2925 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2927 static int lock_release_nested(struct task_struct
*curr
,
2928 struct lockdep_map
*lock
, unsigned long ip
)
2930 struct held_lock
*hlock
;
2934 * Pop off the top of the lock stack:
2936 depth
= curr
->lockdep_depth
- 1;
2937 hlock
= curr
->held_locks
+ depth
;
2940 * Is the unlock non-nested:
2942 if (hlock
->instance
!= lock
)
2943 return lock_release_non_nested(curr
, lock
, ip
);
2944 curr
->lockdep_depth
--;
2946 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2949 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2951 lock_release_holdtime(hlock
);
2953 #ifdef CONFIG_DEBUG_LOCKDEP
2954 hlock
->prev_chain_key
= 0;
2955 hlock
->class_idx
= 0;
2956 hlock
->acquire_ip
= 0;
2957 hlock
->irq_context
= 0;
2963 * Remove the lock to the list of currently held locks - this gets
2964 * called on mutex_unlock()/spin_unlock*() (or on a failed
2965 * mutex_lock_interruptible()). This is done for unlocks that nest
2966 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2969 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2971 struct task_struct
*curr
= current
;
2973 if (!check_unlock(curr
, lock
, ip
))
2977 if (!lock_release_nested(curr
, lock
, ip
))
2980 if (!lock_release_non_nested(curr
, lock
, ip
))
2984 check_chain_key(curr
);
2988 * Check whether we follow the irq-flags state precisely:
2990 static void check_flags(unsigned long flags
)
2992 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2993 defined(CONFIG_TRACE_IRQFLAGS)
2997 if (irqs_disabled_flags(flags
)) {
2998 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
2999 printk("possible reason: unannotated irqs-off.\n");
3002 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
3003 printk("possible reason: unannotated irqs-on.\n");
3008 * We dont accurately track softirq state in e.g.
3009 * hardirq contexts (such as on 4KSTACKS), so only
3010 * check if not in hardirq contexts:
3012 if (!hardirq_count()) {
3013 if (softirq_count())
3014 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
3016 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
3020 print_irqtrace_events(current
);
3024 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
3025 struct lock_class_key
*key
, unsigned int subclass
,
3028 unsigned long flags
;
3030 if (unlikely(current
->lockdep_recursion
))
3033 raw_local_irq_save(flags
);
3034 current
->lockdep_recursion
= 1;
3036 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
3037 check_chain_key(current
);
3038 current
->lockdep_recursion
= 0;
3039 raw_local_irq_restore(flags
);
3041 EXPORT_SYMBOL_GPL(lock_set_class
);
3044 * We are not always called with irqs disabled - do that here,
3045 * and also avoid lockdep recursion:
3047 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3048 int trylock
, int read
, int check
,
3049 struct lockdep_map
*nest_lock
, unsigned long ip
)
3051 unsigned long flags
;
3053 trace_lock_acquire(lock
, subclass
, trylock
, read
, check
, nest_lock
, ip
);
3055 if (unlikely(current
->lockdep_recursion
))
3058 raw_local_irq_save(flags
);
3061 current
->lockdep_recursion
= 1;
3062 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
3063 irqs_disabled_flags(flags
), nest_lock
, ip
);
3064 current
->lockdep_recursion
= 0;
3065 raw_local_irq_restore(flags
);
3067 EXPORT_SYMBOL_GPL(lock_acquire
);
3069 void lock_release(struct lockdep_map
*lock
, int nested
,
3072 unsigned long flags
;
3074 trace_lock_release(lock
, nested
, ip
);
3076 if (unlikely(current
->lockdep_recursion
))
3079 raw_local_irq_save(flags
);
3081 current
->lockdep_recursion
= 1;
3082 __lock_release(lock
, nested
, ip
);
3083 current
->lockdep_recursion
= 0;
3084 raw_local_irq_restore(flags
);
3086 EXPORT_SYMBOL_GPL(lock_release
);
3088 void lockdep_set_current_reclaim_state(gfp_t gfp_mask
)
3090 current
->lockdep_reclaim_gfp
= gfp_mask
;
3093 void lockdep_clear_current_reclaim_state(void)
3095 current
->lockdep_reclaim_gfp
= 0;
3098 #ifdef CONFIG_LOCK_STAT
3100 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3103 if (!debug_locks_off())
3105 if (debug_locks_silent
)
3108 printk("\n=================================\n");
3109 printk( "[ BUG: bad contention detected! ]\n");
3110 printk( "---------------------------------\n");
3111 printk("%s/%d is trying to contend lock (",
3112 curr
->comm
, task_pid_nr(curr
));
3113 print_lockdep_cache(lock
);
3116 printk("but there are no locks held!\n");
3117 printk("\nother info that might help us debug this:\n");
3118 lockdep_print_held_locks(curr
);
3120 printk("\nstack backtrace:\n");
3127 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3129 struct task_struct
*curr
= current
;
3130 struct held_lock
*hlock
, *prev_hlock
;
3131 struct lock_class_stats
*stats
;
3133 int i
, contention_point
, contending_point
;
3135 depth
= curr
->lockdep_depth
;
3136 if (DEBUG_LOCKS_WARN_ON(!depth
))
3140 for (i
= depth
-1; i
>= 0; i
--) {
3141 hlock
= curr
->held_locks
+ i
;
3143 * We must not cross into another context:
3145 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3147 if (hlock
->instance
== lock
)
3151 print_lock_contention_bug(curr
, lock
, ip
);
3155 hlock
->waittime_stamp
= sched_clock();
3157 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3158 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3161 stats
= get_lock_stats(hlock_class(hlock
));
3162 if (contention_point
< LOCKSTAT_POINTS
)
3163 stats
->contention_point
[contention_point
]++;
3164 if (contending_point
< LOCKSTAT_POINTS
)
3165 stats
->contending_point
[contending_point
]++;
3166 if (lock
->cpu
!= smp_processor_id())
3167 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3168 put_lock_stats(stats
);
3172 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3174 struct task_struct
*curr
= current
;
3175 struct held_lock
*hlock
, *prev_hlock
;
3176 struct lock_class_stats
*stats
;
3182 depth
= curr
->lockdep_depth
;
3183 if (DEBUG_LOCKS_WARN_ON(!depth
))
3187 for (i
= depth
-1; i
>= 0; i
--) {
3188 hlock
= curr
->held_locks
+ i
;
3190 * We must not cross into another context:
3192 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3194 if (hlock
->instance
== lock
)
3198 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3202 cpu
= smp_processor_id();
3203 if (hlock
->waittime_stamp
) {
3204 now
= sched_clock();
3205 waittime
= now
- hlock
->waittime_stamp
;
3206 hlock
->holdtime_stamp
= now
;
3209 trace_lock_acquired(lock
, ip
, waittime
);
3211 stats
= get_lock_stats(hlock_class(hlock
));
3214 lock_time_inc(&stats
->read_waittime
, waittime
);
3216 lock_time_inc(&stats
->write_waittime
, waittime
);
3218 if (lock
->cpu
!= cpu
)
3219 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3220 put_lock_stats(stats
);
3226 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3228 unsigned long flags
;
3230 trace_lock_contended(lock
, ip
);
3232 if (unlikely(!lock_stat
))
3235 if (unlikely(current
->lockdep_recursion
))
3238 raw_local_irq_save(flags
);
3240 current
->lockdep_recursion
= 1;
3241 __lock_contended(lock
, ip
);
3242 current
->lockdep_recursion
= 0;
3243 raw_local_irq_restore(flags
);
3245 EXPORT_SYMBOL_GPL(lock_contended
);
3247 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3249 unsigned long flags
;
3251 if (unlikely(!lock_stat
))
3254 if (unlikely(current
->lockdep_recursion
))
3257 raw_local_irq_save(flags
);
3259 current
->lockdep_recursion
= 1;
3260 __lock_acquired(lock
, ip
);
3261 current
->lockdep_recursion
= 0;
3262 raw_local_irq_restore(flags
);
3264 EXPORT_SYMBOL_GPL(lock_acquired
);
3268 * Used by the testsuite, sanitize the validator state
3269 * after a simulated failure:
3272 void lockdep_reset(void)
3274 unsigned long flags
;
3277 raw_local_irq_save(flags
);
3278 current
->curr_chain_key
= 0;
3279 current
->lockdep_depth
= 0;
3280 current
->lockdep_recursion
= 0;
3281 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3282 nr_hardirq_chains
= 0;
3283 nr_softirq_chains
= 0;
3284 nr_process_chains
= 0;
3286 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3287 INIT_LIST_HEAD(chainhash_table
+ i
);
3288 raw_local_irq_restore(flags
);
3291 static void zap_class(struct lock_class
*class)
3296 * Remove all dependencies this lock is
3299 for (i
= 0; i
< nr_list_entries
; i
++) {
3300 if (list_entries
[i
].class == class)
3301 list_del_rcu(&list_entries
[i
].entry
);
3304 * Unhash the class and remove it from the all_lock_classes list:
3306 list_del_rcu(&class->hash_entry
);
3307 list_del_rcu(&class->lock_entry
);
3312 static inline int within(const void *addr
, void *start
, unsigned long size
)
3314 return addr
>= start
&& addr
< start
+ size
;
3317 void lockdep_free_key_range(void *start
, unsigned long size
)
3319 struct lock_class
*class, *next
;
3320 struct list_head
*head
;
3321 unsigned long flags
;
3325 raw_local_irq_save(flags
);
3326 locked
= graph_lock();
3329 * Unhash all classes that were created by this module:
3331 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3332 head
= classhash_table
+ i
;
3333 if (list_empty(head
))
3335 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3336 if (within(class->key
, start
, size
))
3338 else if (within(class->name
, start
, size
))
3345 raw_local_irq_restore(flags
);
3348 void lockdep_reset_lock(struct lockdep_map
*lock
)
3350 struct lock_class
*class, *next
;
3351 struct list_head
*head
;
3352 unsigned long flags
;
3356 raw_local_irq_save(flags
);
3359 * Remove all classes this lock might have:
3361 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3363 * If the class exists we look it up and zap it:
3365 class = look_up_lock_class(lock
, j
);
3370 * Debug check: in the end all mapped classes should
3373 locked
= graph_lock();
3374 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3375 head
= classhash_table
+ i
;
3376 if (list_empty(head
))
3378 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3379 if (unlikely(class == lock
->class_cache
)) {
3380 if (debug_locks_off_graph_unlock())
3390 raw_local_irq_restore(flags
);
3393 void lockdep_init(void)
3398 * Some architectures have their own start_kernel()
3399 * code which calls lockdep_init(), while we also
3400 * call lockdep_init() from the start_kernel() itself,
3401 * and we want to initialize the hashes only once:
3403 if (lockdep_initialized
)
3406 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3407 INIT_LIST_HEAD(classhash_table
+ i
);
3409 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3410 INIT_LIST_HEAD(chainhash_table
+ i
);
3412 lockdep_initialized
= 1;
3415 void __init
lockdep_info(void)
3417 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3419 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
3420 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
3421 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
3422 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
3423 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
3424 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
3425 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
3427 printk(" memory used by lock dependency info: %lu kB\n",
3428 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
3429 sizeof(struct list_head
) * CLASSHASH_SIZE
+
3430 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
3431 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
3432 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024
3433 #ifdef CONFIG_PROVE_LOCKING
3434 + sizeof(struct circular_queue
) + sizeof(bfs_accessed
)
3438 printk(" per task-struct memory footprint: %lu bytes\n",
3439 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
3441 #ifdef CONFIG_DEBUG_LOCKDEP
3442 if (lockdep_init_error
) {
3443 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3444 printk("Call stack leading to lockdep invocation was:\n");
3445 print_stack_trace(&lockdep_init_trace
, 0);
3451 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
3452 const void *mem_to
, struct held_lock
*hlock
)
3454 if (!debug_locks_off())
3456 if (debug_locks_silent
)
3459 printk("\n=========================\n");
3460 printk( "[ BUG: held lock freed! ]\n");
3461 printk( "-------------------------\n");
3462 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3463 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
3465 lockdep_print_held_locks(curr
);
3467 printk("\nstack backtrace:\n");
3471 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
3472 const void* lock_from
, unsigned long lock_len
)
3474 return lock_from
+ lock_len
<= mem_from
||
3475 mem_from
+ mem_len
<= lock_from
;
3479 * Called when kernel memory is freed (or unmapped), or if a lock
3480 * is destroyed or reinitialized - this code checks whether there is
3481 * any held lock in the memory range of <from> to <to>:
3483 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
3485 struct task_struct
*curr
= current
;
3486 struct held_lock
*hlock
;
3487 unsigned long flags
;
3490 if (unlikely(!debug_locks
))
3493 local_irq_save(flags
);
3494 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3495 hlock
= curr
->held_locks
+ i
;
3497 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
3498 sizeof(*hlock
->instance
)))
3501 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
3504 local_irq_restore(flags
);
3506 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
3508 static void print_held_locks_bug(struct task_struct
*curr
)
3510 if (!debug_locks_off())
3512 if (debug_locks_silent
)
3515 printk("\n=====================================\n");
3516 printk( "[ BUG: lock held at task exit time! ]\n");
3517 printk( "-------------------------------------\n");
3518 printk("%s/%d is exiting with locks still held!\n",
3519 curr
->comm
, task_pid_nr(curr
));
3520 lockdep_print_held_locks(curr
);
3522 printk("\nstack backtrace:\n");
3526 void debug_check_no_locks_held(struct task_struct
*task
)
3528 if (unlikely(task
->lockdep_depth
> 0))
3529 print_held_locks_bug(task
);
3532 void debug_show_all_locks(void)
3534 struct task_struct
*g
, *p
;
3538 if (unlikely(!debug_locks
)) {
3539 printk("INFO: lockdep is turned off.\n");
3542 printk("\nShowing all locks held in the system:\n");
3545 * Here we try to get the tasklist_lock as hard as possible,
3546 * if not successful after 2 seconds we ignore it (but keep
3547 * trying). This is to enable a debug printout even if a
3548 * tasklist_lock-holding task deadlocks or crashes.
3551 if (!read_trylock(&tasklist_lock
)) {
3553 printk("hm, tasklist_lock locked, retrying... ");
3556 printk(" #%d", 10-count
);
3560 printk(" ignoring it.\n");
3564 printk(KERN_CONT
" locked it.\n");
3567 do_each_thread(g
, p
) {
3569 * It's not reliable to print a task's held locks
3570 * if it's not sleeping (or if it's not the current
3573 if (p
->state
== TASK_RUNNING
&& p
!= current
)
3575 if (p
->lockdep_depth
)
3576 lockdep_print_held_locks(p
);
3578 if (read_trylock(&tasklist_lock
))
3580 } while_each_thread(g
, p
);
3583 printk("=============================================\n\n");
3586 read_unlock(&tasklist_lock
);
3588 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
3591 * Careful: only use this function if you are sure that
3592 * the task cannot run in parallel!
3594 void __debug_show_held_locks(struct task_struct
*task
)
3596 if (unlikely(!debug_locks
)) {
3597 printk("INFO: lockdep is turned off.\n");
3600 lockdep_print_held_locks(task
);
3602 EXPORT_SYMBOL_GPL(__debug_show_held_locks
);
3604 void debug_show_held_locks(struct task_struct
*task
)
3606 __debug_show_held_locks(task
);
3608 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
3610 void lockdep_sys_exit(void)
3612 struct task_struct
*curr
= current
;
3614 if (unlikely(curr
->lockdep_depth
)) {
3615 if (!debug_locks_off())
3617 printk("\n================================================\n");
3618 printk( "[ BUG: lock held when returning to user space! ]\n");
3619 printk( "------------------------------------------------\n");
3620 printk("%s/%d is leaving the kernel with locks still held!\n",
3621 curr
->comm
, curr
->pid
);
3622 lockdep_print_held_locks(curr
);