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>
45 #include <asm/sections.h>
47 #include "lockdep_internals.h"
49 #ifdef CONFIG_PROVE_LOCKING
50 int prove_locking
= 1;
51 module_param(prove_locking
, int, 0644);
53 #define prove_locking 0
56 #ifdef CONFIG_LOCK_STAT
58 module_param(lock_stat
, int, 0644);
64 * lockdep_lock: protects the lockdep graph, the hashes and the
65 * class/list/hash allocators.
67 * This is one of the rare exceptions where it's justified
68 * to use a raw spinlock - we really dont want the spinlock
69 * code to recurse back into the lockdep code...
71 static raw_spinlock_t lockdep_lock
= (raw_spinlock_t
)__RAW_SPIN_LOCK_UNLOCKED
;
73 static int graph_lock(void)
75 __raw_spin_lock(&lockdep_lock
);
77 * Make sure that if another CPU detected a bug while
78 * walking the graph we dont change it (while the other
79 * CPU is busy printing out stuff with the graph lock
83 __raw_spin_unlock(&lockdep_lock
);
86 /* prevent any recursions within lockdep from causing deadlocks */
87 current
->lockdep_recursion
++;
91 static inline int graph_unlock(void)
93 if (debug_locks
&& !__raw_spin_is_locked(&lockdep_lock
))
94 return DEBUG_LOCKS_WARN_ON(1);
96 current
->lockdep_recursion
--;
97 __raw_spin_unlock(&lockdep_lock
);
102 * Turn lock debugging off and return with 0 if it was off already,
103 * and also release the graph lock:
105 static inline int debug_locks_off_graph_unlock(void)
107 int ret
= debug_locks_off();
109 __raw_spin_unlock(&lockdep_lock
);
114 static int lockdep_initialized
;
116 unsigned long nr_list_entries
;
117 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
120 * All data structures here are protected by the global debug_lock.
122 * Mutex key structs only get allocated, once during bootup, and never
123 * get freed - this significantly simplifies the debugging code.
125 unsigned long nr_lock_classes
;
126 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
128 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
130 if (!hlock
->class_idx
) {
131 DEBUG_LOCKS_WARN_ON(1);
134 return lock_classes
+ hlock
->class_idx
- 1;
137 #ifdef CONFIG_LOCK_STAT
138 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
], lock_stats
);
140 static int lock_point(unsigned long points
[], unsigned long ip
)
144 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
145 if (points
[i
] == 0) {
156 static void lock_time_inc(struct lock_time
*lt
, s64 time
)
161 if (time
< lt
->min
|| !lt
->min
)
168 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
170 dst
->min
+= src
->min
;
171 dst
->max
+= src
->max
;
172 dst
->total
+= src
->total
;
176 struct lock_class_stats
lock_stats(struct lock_class
*class)
178 struct lock_class_stats stats
;
181 memset(&stats
, 0, sizeof(struct lock_class_stats
));
182 for_each_possible_cpu(cpu
) {
183 struct lock_class_stats
*pcs
=
184 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
186 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
187 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
189 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
190 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
192 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
193 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
195 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
196 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
198 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
199 stats
.bounces
[i
] += pcs
->bounces
[i
];
205 void clear_lock_stats(struct lock_class
*class)
209 for_each_possible_cpu(cpu
) {
210 struct lock_class_stats
*cpu_stats
=
211 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
213 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
215 memset(class->contention_point
, 0, sizeof(class->contention_point
));
216 memset(class->contending_point
, 0, sizeof(class->contending_point
));
219 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
221 return &get_cpu_var(lock_stats
)[class - lock_classes
];
224 static void put_lock_stats(struct lock_class_stats
*stats
)
226 put_cpu_var(lock_stats
);
229 static void lock_release_holdtime(struct held_lock
*hlock
)
231 struct lock_class_stats
*stats
;
237 holdtime
= sched_clock() - hlock
->holdtime_stamp
;
239 stats
= get_lock_stats(hlock_class(hlock
));
241 lock_time_inc(&stats
->read_holdtime
, holdtime
);
243 lock_time_inc(&stats
->write_holdtime
, holdtime
);
244 put_lock_stats(stats
);
247 static inline void lock_release_holdtime(struct held_lock
*hlock
)
253 * We keep a global list of all lock classes. The list only grows,
254 * never shrinks. The list is only accessed with the lockdep
255 * spinlock lock held.
257 LIST_HEAD(all_lock_classes
);
260 * The lockdep classes are in a hash-table as well, for fast lookup:
262 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
263 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
264 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
265 #define classhashentry(key) (classhash_table + __classhashfn((key)))
267 static struct list_head classhash_table
[CLASSHASH_SIZE
];
270 * We put the lock dependency chains into a hash-table as well, to cache
273 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
274 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
275 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
276 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
278 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
281 * The hash key of the lock dependency chains is a hash itself too:
282 * it's a hash of all locks taken up to that lock, including that lock.
283 * It's a 64-bit hash, because it's important for the keys to be
286 #define iterate_chain_key(key1, key2) \
287 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
288 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
291 void lockdep_off(void)
293 current
->lockdep_recursion
++;
295 EXPORT_SYMBOL(lockdep_off
);
297 void lockdep_on(void)
299 current
->lockdep_recursion
--;
301 EXPORT_SYMBOL(lockdep_on
);
304 * Debugging switches:
308 #define VERY_VERBOSE 0
311 # define HARDIRQ_VERBOSE 1
312 # define SOFTIRQ_VERBOSE 1
313 # define RECLAIM_VERBOSE 1
315 # define HARDIRQ_VERBOSE 0
316 # define SOFTIRQ_VERBOSE 0
317 # define RECLAIM_VERBOSE 0
320 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
322 * Quick filtering for interesting events:
324 static int class_filter(struct lock_class
*class)
328 if (class->name_version
== 1 &&
329 !strcmp(class->name
, "lockname"))
331 if (class->name_version
== 1 &&
332 !strcmp(class->name
, "&struct->lockfield"))
335 /* Filter everything else. 1 would be to allow everything else */
340 static int verbose(struct lock_class
*class)
343 return class_filter(class);
349 * Stack-trace: tightly packed array of stack backtrace
350 * addresses. Protected by the graph_lock.
352 unsigned long nr_stack_trace_entries
;
353 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
355 static int save_trace(struct stack_trace
*trace
)
357 trace
->nr_entries
= 0;
358 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
359 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
363 save_stack_trace(trace
);
365 trace
->max_entries
= trace
->nr_entries
;
367 nr_stack_trace_entries
+= trace
->nr_entries
;
369 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
370 if (!debug_locks_off_graph_unlock())
373 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
374 printk("turning off the locking correctness validator.\n");
383 unsigned int nr_hardirq_chains
;
384 unsigned int nr_softirq_chains
;
385 unsigned int nr_process_chains
;
386 unsigned int max_lockdep_depth
;
387 unsigned int max_recursion_depth
;
389 static unsigned int lockdep_dependency_gen_id
;
391 static bool lockdep_dependency_visit(struct lock_class
*source
,
395 lockdep_dependency_gen_id
++;
396 if (source
->dep_gen_id
== lockdep_dependency_gen_id
)
398 source
->dep_gen_id
= lockdep_dependency_gen_id
;
402 #ifdef CONFIG_DEBUG_LOCKDEP
404 * We cannot printk in early bootup code. Not even early_printk()
405 * might work. So we mark any initialization errors and printk
406 * about it later on, in lockdep_info().
408 static int lockdep_init_error
;
409 static unsigned long lockdep_init_trace_data
[20];
410 static struct stack_trace lockdep_init_trace
= {
411 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
412 .entries
= lockdep_init_trace_data
,
416 * Various lockdep statistics:
418 atomic_t chain_lookup_hits
;
419 atomic_t chain_lookup_misses
;
420 atomic_t hardirqs_on_events
;
421 atomic_t hardirqs_off_events
;
422 atomic_t redundant_hardirqs_on
;
423 atomic_t redundant_hardirqs_off
;
424 atomic_t softirqs_on_events
;
425 atomic_t softirqs_off_events
;
426 atomic_t redundant_softirqs_on
;
427 atomic_t redundant_softirqs_off
;
428 atomic_t nr_unused_locks
;
429 atomic_t nr_cyclic_checks
;
430 atomic_t nr_cyclic_check_recursions
;
431 atomic_t nr_find_usage_forwards_checks
;
432 atomic_t nr_find_usage_forwards_recursions
;
433 atomic_t nr_find_usage_backwards_checks
;
434 atomic_t nr_find_usage_backwards_recursions
;
435 # define debug_atomic_inc(ptr) atomic_inc(ptr)
436 # define debug_atomic_dec(ptr) atomic_dec(ptr)
437 # define debug_atomic_read(ptr) atomic_read(ptr)
439 # define debug_atomic_inc(ptr) do { } while (0)
440 # define debug_atomic_dec(ptr) do { } while (0)
441 # define debug_atomic_read(ptr) 0
448 #define __STR(foo) #foo
449 #define STR(foo) __STR(foo)
451 #define __USAGE(__STATE) \
452 [LOCK_USED_IN_##__STATE] = "IN-"STR(__STATE)"-W", \
453 [LOCK_ENABLED_##__STATE] = STR(__STATE)"-ON-W", \
454 [LOCK_USED_IN_##__STATE##_READ] = "IN-"STR(__STATE)"-R", \
455 [LOCK_ENABLED_##__STATE##_READ] = STR(__STATE)"-ON-R",
457 static const char *usage_str
[] =
459 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
460 #include "lockdep_states.h"
462 [LOCK_USED
] = "INITIAL USE",
465 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
467 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
471 get_usage_chars(struct lock_class
*class, char *c1
, char *c2
, char *c3
,
472 char *c4
, char *c5
, char *c6
)
474 *c1
= '.', *c2
= '.', *c3
= '.', *c4
= '.', *c5
= '.', *c6
= '.';
476 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ
)
479 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQ
)
482 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ
)
485 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQ
)
488 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQ_READ
)
490 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ_READ
) {
492 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQ_READ
)
496 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQ_READ
)
498 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ_READ
) {
500 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQ_READ
)
504 if (class->usage_mask
& LOCKF_USED_IN_RECLAIM_FS
)
507 if (class->usage_mask
& LOCKF_ENABLED_RECLAIM_FS
)
510 if (class->usage_mask
& LOCKF_ENABLED_RECLAIM_FS_READ
)
512 if (class->usage_mask
& LOCKF_USED_IN_RECLAIM_FS_READ
) {
514 if (class->usage_mask
& LOCKF_ENABLED_RECLAIM_FS_READ
)
520 static void print_lock_name(struct lock_class
*class)
522 char str
[KSYM_NAME_LEN
], c1
, c2
, c3
, c4
, c5
, c6
;
525 get_usage_chars(class, &c1
, &c2
, &c3
, &c4
, &c5
, &c6
);
529 name
= __get_key_name(class->key
, str
);
530 printk(" (%s", name
);
532 printk(" (%s", name
);
533 if (class->name_version
> 1)
534 printk("#%d", class->name_version
);
536 printk("/%d", class->subclass
);
538 printk("){%c%c%c%c%c%c}", c1
, c2
, c3
, c4
, c5
, c6
);
541 static void print_lockdep_cache(struct lockdep_map
*lock
)
544 char str
[KSYM_NAME_LEN
];
548 name
= __get_key_name(lock
->key
->subkeys
, str
);
553 static void print_lock(struct held_lock
*hlock
)
555 print_lock_name(hlock_class(hlock
));
557 print_ip_sym(hlock
->acquire_ip
);
560 static void lockdep_print_held_locks(struct task_struct
*curr
)
562 int i
, depth
= curr
->lockdep_depth
;
565 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
568 printk("%d lock%s held by %s/%d:\n",
569 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
571 for (i
= 0; i
< depth
; i
++) {
573 print_lock(curr
->held_locks
+ i
);
577 static void print_lock_class_header(struct lock_class
*class, int depth
)
581 printk("%*s->", depth
, "");
582 print_lock_name(class);
583 printk(" ops: %lu", class->ops
);
586 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
587 if (class->usage_mask
& (1 << bit
)) {
590 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
591 len
+= printk(" at:\n");
592 print_stack_trace(class->usage_traces
+ bit
, len
);
595 printk("%*s }\n", depth
, "");
597 printk("%*s ... key at: ",depth
,"");
598 print_ip_sym((unsigned long)class->key
);
602 * printk all lock dependencies starting at <entry>:
605 print_lock_dependencies(struct lock_class
*class, int depth
)
607 struct lock_list
*entry
;
609 if (lockdep_dependency_visit(class, depth
))
612 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
615 print_lock_class_header(class, depth
);
617 list_for_each_entry(entry
, &class->locks_after
, entry
) {
618 if (DEBUG_LOCKS_WARN_ON(!entry
->class))
621 print_lock_dependencies(entry
->class, depth
+ 1);
623 printk("%*s ... acquired at:\n",depth
,"");
624 print_stack_trace(&entry
->trace
, 2);
629 static void print_kernel_version(void)
631 printk("%s %.*s\n", init_utsname()->release
,
632 (int)strcspn(init_utsname()->version
, " "),
633 init_utsname()->version
);
636 static int very_verbose(struct lock_class
*class)
639 return class_filter(class);
645 * Is this the address of a static object:
647 static int static_obj(void *obj
)
649 unsigned long start
= (unsigned long) &_stext
,
650 end
= (unsigned long) &_end
,
651 addr
= (unsigned long) obj
;
659 if ((addr
>= start
) && (addr
< end
))
666 for_each_possible_cpu(i
) {
667 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
668 end
= (unsigned long) &__per_cpu_start
+ PERCPU_ENOUGH_ROOM
671 if ((addr
>= start
) && (addr
< end
))
679 return is_module_address(addr
);
683 * To make lock name printouts unique, we calculate a unique
684 * class->name_version generation counter:
686 static int count_matching_names(struct lock_class
*new_class
)
688 struct lock_class
*class;
691 if (!new_class
->name
)
694 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
695 if (new_class
->key
- new_class
->subclass
== class->key
)
696 return class->name_version
;
697 if (class->name
&& !strcmp(class->name
, new_class
->name
))
698 count
= max(count
, class->name_version
);
705 * Register a lock's class in the hash-table, if the class is not present
706 * yet. Otherwise we look it up. We cache the result in the lock object
707 * itself, so actual lookup of the hash should be once per lock object.
709 static inline struct lock_class
*
710 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
712 struct lockdep_subclass_key
*key
;
713 struct list_head
*hash_head
;
714 struct lock_class
*class;
716 #ifdef CONFIG_DEBUG_LOCKDEP
718 * If the architecture calls into lockdep before initializing
719 * the hashes then we'll warn about it later. (we cannot printk
722 if (unlikely(!lockdep_initialized
)) {
724 lockdep_init_error
= 1;
725 save_stack_trace(&lockdep_init_trace
);
730 * Static locks do not have their class-keys yet - for them the key
731 * is the lock object itself:
733 if (unlikely(!lock
->key
))
734 lock
->key
= (void *)lock
;
737 * NOTE: the class-key must be unique. For dynamic locks, a static
738 * lock_class_key variable is passed in through the mutex_init()
739 * (or spin_lock_init()) call - which acts as the key. For static
740 * locks we use the lock object itself as the key.
742 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
743 sizeof(struct lockdep_map
));
745 key
= lock
->key
->subkeys
+ subclass
;
747 hash_head
= classhashentry(key
);
750 * We can walk the hash lockfree, because the hash only
751 * grows, and we are careful when adding entries to the end:
753 list_for_each_entry(class, hash_head
, hash_entry
) {
754 if (class->key
== key
) {
755 WARN_ON_ONCE(class->name
!= lock
->name
);
764 * Register a lock's class in the hash-table, if the class is not present
765 * yet. Otherwise we look it up. We cache the result in the lock object
766 * itself, so actual lookup of the hash should be once per lock object.
768 static inline struct lock_class
*
769 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
771 struct lockdep_subclass_key
*key
;
772 struct list_head
*hash_head
;
773 struct lock_class
*class;
776 class = look_up_lock_class(lock
, subclass
);
781 * Debug-check: all keys must be persistent!
783 if (!static_obj(lock
->key
)) {
785 printk("INFO: trying to register non-static key.\n");
786 printk("the code is fine but needs lockdep annotation.\n");
787 printk("turning off the locking correctness validator.\n");
793 key
= lock
->key
->subkeys
+ subclass
;
794 hash_head
= classhashentry(key
);
796 raw_local_irq_save(flags
);
798 raw_local_irq_restore(flags
);
802 * We have to do the hash-walk again, to avoid races
805 list_for_each_entry(class, hash_head
, hash_entry
)
806 if (class->key
== key
)
809 * Allocate a new key from the static array, and add it to
812 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
813 if (!debug_locks_off_graph_unlock()) {
814 raw_local_irq_restore(flags
);
817 raw_local_irq_restore(flags
);
819 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
820 printk("turning off the locking correctness validator.\n");
823 class = lock_classes
+ nr_lock_classes
++;
824 debug_atomic_inc(&nr_unused_locks
);
826 class->name
= lock
->name
;
827 class->subclass
= subclass
;
828 INIT_LIST_HEAD(&class->lock_entry
);
829 INIT_LIST_HEAD(&class->locks_before
);
830 INIT_LIST_HEAD(&class->locks_after
);
831 class->name_version
= count_matching_names(class);
833 * We use RCU's safe list-add method to make
834 * parallel walking of the hash-list safe:
836 list_add_tail_rcu(&class->hash_entry
, hash_head
);
838 * Add it to the global list of classes:
840 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
842 if (verbose(class)) {
844 raw_local_irq_restore(flags
);
846 printk("\nnew class %p: %s", class->key
, class->name
);
847 if (class->name_version
> 1)
848 printk("#%d", class->name_version
);
852 raw_local_irq_save(flags
);
854 raw_local_irq_restore(flags
);
860 raw_local_irq_restore(flags
);
862 if (!subclass
|| force
)
863 lock
->class_cache
= class;
865 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
871 #ifdef CONFIG_PROVE_LOCKING
873 * Allocate a lockdep entry. (assumes the graph_lock held, returns
874 * with NULL on failure)
876 static struct lock_list
*alloc_list_entry(void)
878 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
879 if (!debug_locks_off_graph_unlock())
882 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
883 printk("turning off the locking correctness validator.\n");
886 return list_entries
+ nr_list_entries
++;
890 * Add a new dependency to the head of the list:
892 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
893 struct list_head
*head
, unsigned long ip
, int distance
)
895 struct lock_list
*entry
;
897 * Lock not present yet - get a new dependency struct and
898 * add it to the list:
900 entry
= alloc_list_entry();
904 if (!save_trace(&entry
->trace
))
908 entry
->distance
= distance
;
910 * Since we never remove from the dependency list, the list can
911 * be walked lockless by other CPUs, it's only allocation
912 * that must be protected by the spinlock. But this also means
913 * we must make new entries visible only once writes to the
914 * entry become visible - hence the RCU op:
916 list_add_tail_rcu(&entry
->entry
, head
);
922 * Recursive, forwards-direction lock-dependency checking, used for
923 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
926 * (to keep the stackframe of the recursive functions small we
927 * use these global variables, and we also mark various helper
928 * functions as noinline.)
930 static struct held_lock
*check_source
, *check_target
;
933 * Print a dependency chain entry (this is only done when a deadlock
934 * has been detected):
937 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
939 if (debug_locks_silent
)
941 printk("\n-> #%u", depth
);
942 print_lock_name(target
->class);
944 print_stack_trace(&target
->trace
, 6);
950 * When a circular dependency is detected, print the
954 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
)
956 struct task_struct
*curr
= current
;
958 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
961 printk("\n=======================================================\n");
962 printk( "[ INFO: possible circular locking dependency detected ]\n");
963 print_kernel_version();
964 printk( "-------------------------------------------------------\n");
965 printk("%s/%d is trying to acquire lock:\n",
966 curr
->comm
, task_pid_nr(curr
));
967 print_lock(check_source
);
968 printk("\nbut task is already holding lock:\n");
969 print_lock(check_target
);
970 printk("\nwhich lock already depends on the new lock.\n\n");
971 printk("\nthe existing dependency chain (in reverse order) is:\n");
973 print_circular_bug_entry(entry
, depth
);
978 static noinline
int print_circular_bug_tail(void)
980 struct task_struct
*curr
= current
;
981 struct lock_list
this;
983 if (debug_locks_silent
)
986 this.class = hlock_class(check_source
);
987 if (!save_trace(&this.trace
))
990 print_circular_bug_entry(&this, 0);
992 printk("\nother info that might help us debug this:\n\n");
993 lockdep_print_held_locks(curr
);
995 printk("\nstack backtrace:\n");
1001 #define RECURSION_LIMIT 40
1003 static int noinline
print_infinite_recursion_bug(void)
1005 if (!debug_locks_off_graph_unlock())
1013 unsigned long __lockdep_count_forward_deps(struct lock_class
*class,
1016 struct lock_list
*entry
;
1017 unsigned long ret
= 1;
1019 if (lockdep_dependency_visit(class, depth
))
1023 * Recurse this class's dependency list:
1025 list_for_each_entry(entry
, &class->locks_after
, entry
)
1026 ret
+= __lockdep_count_forward_deps(entry
->class, depth
+ 1);
1031 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1033 unsigned long ret
, flags
;
1035 local_irq_save(flags
);
1036 __raw_spin_lock(&lockdep_lock
);
1037 ret
= __lockdep_count_forward_deps(class, 0);
1038 __raw_spin_unlock(&lockdep_lock
);
1039 local_irq_restore(flags
);
1044 unsigned long __lockdep_count_backward_deps(struct lock_class
*class,
1047 struct lock_list
*entry
;
1048 unsigned long ret
= 1;
1050 if (lockdep_dependency_visit(class, depth
))
1053 * Recurse this class's dependency list:
1055 list_for_each_entry(entry
, &class->locks_before
, entry
)
1056 ret
+= __lockdep_count_backward_deps(entry
->class, depth
+ 1);
1061 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1063 unsigned long ret
, flags
;
1065 local_irq_save(flags
);
1066 __raw_spin_lock(&lockdep_lock
);
1067 ret
= __lockdep_count_backward_deps(class, 0);
1068 __raw_spin_unlock(&lockdep_lock
);
1069 local_irq_restore(flags
);
1075 * Prove that the dependency graph starting at <entry> can not
1076 * lead to <target>. Print an error and return 0 if it does.
1079 check_noncircular(struct lock_class
*source
, unsigned int depth
)
1081 struct lock_list
*entry
;
1083 if (lockdep_dependency_visit(source
, depth
))
1086 debug_atomic_inc(&nr_cyclic_check_recursions
);
1087 if (depth
> max_recursion_depth
)
1088 max_recursion_depth
= depth
;
1089 if (depth
>= RECURSION_LIMIT
)
1090 return print_infinite_recursion_bug();
1092 * Check this lock's dependency list:
1094 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1095 if (entry
->class == hlock_class(check_target
))
1096 return print_circular_bug_header(entry
, depth
+1);
1097 debug_atomic_inc(&nr_cyclic_checks
);
1098 if (!check_noncircular(entry
->class, depth
+1))
1099 return print_circular_bug_entry(entry
, depth
+1);
1104 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1106 * Forwards and backwards subgraph searching, for the purposes of
1107 * proving that two subgraphs can be connected by a new dependency
1108 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1110 static enum lock_usage_bit find_usage_bit
;
1111 static struct lock_class
*forwards_match
, *backwards_match
;
1114 * Find a node in the forwards-direction dependency sub-graph starting
1115 * at <source> that matches <find_usage_bit>.
1117 * Return 2 if such a node exists in the subgraph, and put that node
1118 * into <forwards_match>.
1120 * Return 1 otherwise and keep <forwards_match> unchanged.
1121 * Return 0 on error.
1124 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
1126 struct lock_list
*entry
;
1129 if (lockdep_dependency_visit(source
, depth
))
1132 if (depth
> max_recursion_depth
)
1133 max_recursion_depth
= depth
;
1134 if (depth
>= RECURSION_LIMIT
)
1135 return print_infinite_recursion_bug();
1137 debug_atomic_inc(&nr_find_usage_forwards_checks
);
1138 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1139 forwards_match
= source
;
1144 * Check this lock's dependency list:
1146 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1147 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
1148 ret
= find_usage_forwards(entry
->class, depth
+1);
1149 if (ret
== 2 || ret
== 0)
1156 * Find a node in the backwards-direction dependency sub-graph starting
1157 * at <source> that matches <find_usage_bit>.
1159 * Return 2 if such a node exists in the subgraph, and put that node
1160 * into <backwards_match>.
1162 * Return 1 otherwise and keep <backwards_match> unchanged.
1163 * Return 0 on error.
1166 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
1168 struct lock_list
*entry
;
1171 if (lockdep_dependency_visit(source
, depth
))
1174 if (!__raw_spin_is_locked(&lockdep_lock
))
1175 return DEBUG_LOCKS_WARN_ON(1);
1177 if (depth
> max_recursion_depth
)
1178 max_recursion_depth
= depth
;
1179 if (depth
>= RECURSION_LIMIT
)
1180 return print_infinite_recursion_bug();
1182 debug_atomic_inc(&nr_find_usage_backwards_checks
);
1183 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1184 backwards_match
= source
;
1188 if (!source
&& debug_locks_off_graph_unlock()) {
1194 * Check this lock's dependency list:
1196 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
1197 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
1198 ret
= find_usage_backwards(entry
->class, depth
+1);
1199 if (ret
== 2 || ret
== 0)
1206 print_bad_irq_dependency(struct task_struct
*curr
,
1207 struct held_lock
*prev
,
1208 struct held_lock
*next
,
1209 enum lock_usage_bit bit1
,
1210 enum lock_usage_bit bit2
,
1211 const char *irqclass
)
1213 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1216 printk("\n======================================================\n");
1217 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1218 irqclass
, irqclass
);
1219 print_kernel_version();
1220 printk( "------------------------------------------------------\n");
1221 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1222 curr
->comm
, task_pid_nr(curr
),
1223 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1224 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1225 curr
->hardirqs_enabled
,
1226 curr
->softirqs_enabled
);
1229 printk("\nand this task is already holding:\n");
1231 printk("which would create a new lock dependency:\n");
1232 print_lock_name(hlock_class(prev
));
1234 print_lock_name(hlock_class(next
));
1237 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1239 print_lock_name(backwards_match
);
1240 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1242 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
1244 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1245 print_lock_name(forwards_match
);
1246 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1249 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
1251 printk("\nother info that might help us debug this:\n\n");
1252 lockdep_print_held_locks(curr
);
1254 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
1255 print_lock_dependencies(backwards_match
, 0);
1257 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
1258 print_lock_dependencies(forwards_match
, 0);
1260 printk("\nstack backtrace:\n");
1267 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1268 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1269 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1273 find_usage_bit
= bit_backwards
;
1274 /* fills in <backwards_match> */
1275 ret
= find_usage_backwards(hlock_class(prev
), 0);
1276 if (!ret
|| ret
== 1)
1279 find_usage_bit
= bit_forwards
;
1280 ret
= find_usage_forwards(hlock_class(next
), 0);
1281 if (!ret
|| ret
== 1)
1284 return print_bad_irq_dependency(curr
, prev
, next
,
1285 bit_backwards
, bit_forwards
, irqclass
);
1289 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1290 struct held_lock
*next
)
1293 * Prove that the new dependency does not connect a hardirq-safe
1294 * lock with a hardirq-unsafe lock - to achieve this we search
1295 * the backwards-subgraph starting at <prev>, and the
1296 * forwards-subgraph starting at <next>:
1298 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ
,
1299 LOCK_ENABLED_HARDIRQ
, "hard"))
1303 * Prove that the new dependency does not connect a hardirq-safe-read
1304 * lock with a hardirq-unsafe lock - to achieve this we search
1305 * the backwards-subgraph starting at <prev>, and the
1306 * forwards-subgraph starting at <next>:
1308 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ_READ
,
1309 LOCK_ENABLED_HARDIRQ
, "hard-read"))
1313 * Prove that the new dependency does not connect a softirq-safe
1314 * lock with a softirq-unsafe lock - to achieve this we search
1315 * the backwards-subgraph starting at <prev>, and the
1316 * forwards-subgraph starting at <next>:
1318 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ
,
1319 LOCK_ENABLED_SOFTIRQ
, "soft"))
1322 * Prove that the new dependency does not connect a softirq-safe-read
1323 * lock with a softirq-unsafe lock - to achieve this we search
1324 * the backwards-subgraph starting at <prev>, and the
1325 * forwards-subgraph starting at <next>:
1327 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ_READ
,
1328 LOCK_ENABLED_SOFTIRQ
, "soft"))
1332 * Prove that the new dependency does not connect a reclaim-fs-safe
1333 * lock with a reclaim-fs-unsafe lock - to achieve this we search
1334 * the backwards-subgraph starting at <prev>, and the
1335 * forwards-subgraph starting at <next>:
1337 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_RECLAIM_FS
,
1338 LOCK_ENABLED_RECLAIM_FS
, "reclaim-fs"))
1342 * Prove that the new dependency does not connect a reclaim-fs-safe-read
1343 * lock with a reclaim-fs-unsafe lock - to achieve this we search
1344 * the backwards-subgraph starting at <prev>, and the
1345 * forwards-subgraph starting at <next>:
1347 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_RECLAIM_FS_READ
,
1348 LOCK_ENABLED_RECLAIM_FS
, "reclaim-fs-read"))
1354 static void inc_chains(void)
1356 if (current
->hardirq_context
)
1357 nr_hardirq_chains
++;
1359 if (current
->softirq_context
)
1360 nr_softirq_chains
++;
1362 nr_process_chains
++;
1369 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1370 struct held_lock
*next
)
1375 static inline void inc_chains(void)
1377 nr_process_chains
++;
1383 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1384 struct held_lock
*next
)
1386 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1389 printk("\n=============================================\n");
1390 printk( "[ INFO: possible recursive locking detected ]\n");
1391 print_kernel_version();
1392 printk( "---------------------------------------------\n");
1393 printk("%s/%d is trying to acquire lock:\n",
1394 curr
->comm
, task_pid_nr(curr
));
1396 printk("\nbut task is already holding lock:\n");
1399 printk("\nother info that might help us debug this:\n");
1400 lockdep_print_held_locks(curr
);
1402 printk("\nstack backtrace:\n");
1409 * Check whether we are holding such a class already.
1411 * (Note that this has to be done separately, because the graph cannot
1412 * detect such classes of deadlocks.)
1414 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1417 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1418 struct lockdep_map
*next_instance
, int read
)
1420 struct held_lock
*prev
;
1421 struct held_lock
*nest
= NULL
;
1424 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1425 prev
= curr
->held_locks
+ i
;
1427 if (prev
->instance
== next
->nest_lock
)
1430 if (hlock_class(prev
) != hlock_class(next
))
1434 * Allow read-after-read recursion of the same
1435 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1437 if ((read
== 2) && prev
->read
)
1441 * We're holding the nest_lock, which serializes this lock's
1442 * nesting behaviour.
1447 return print_deadlock_bug(curr
, prev
, next
);
1453 * There was a chain-cache miss, and we are about to add a new dependency
1454 * to a previous lock. We recursively validate the following rules:
1456 * - would the adding of the <prev> -> <next> dependency create a
1457 * circular dependency in the graph? [== circular deadlock]
1459 * - does the new prev->next dependency connect any hardirq-safe lock
1460 * (in the full backwards-subgraph starting at <prev>) with any
1461 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1462 * <next>)? [== illegal lock inversion with hardirq contexts]
1464 * - does the new prev->next dependency connect any softirq-safe lock
1465 * (in the full backwards-subgraph starting at <prev>) with any
1466 * softirq-unsafe lock (in the full forwards-subgraph starting at
1467 * <next>)? [== illegal lock inversion with softirq contexts]
1469 * any of these scenarios could lead to a deadlock.
1471 * Then if all the validations pass, we add the forwards and backwards
1475 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1476 struct held_lock
*next
, int distance
)
1478 struct lock_list
*entry
;
1482 * Prove that the new <prev> -> <next> dependency would not
1483 * create a circular dependency in the graph. (We do this by
1484 * forward-recursing into the graph starting at <next>, and
1485 * checking whether we can reach <prev>.)
1487 * We are using global variables to control the recursion, to
1488 * keep the stackframe size of the recursive functions low:
1490 check_source
= next
;
1491 check_target
= prev
;
1492 if (!(check_noncircular(hlock_class(next
), 0)))
1493 return print_circular_bug_tail();
1495 if (!check_prev_add_irq(curr
, prev
, next
))
1499 * For recursive read-locks we do all the dependency checks,
1500 * but we dont store read-triggered dependencies (only
1501 * write-triggered dependencies). This ensures that only the
1502 * write-side dependencies matter, and that if for example a
1503 * write-lock never takes any other locks, then the reads are
1504 * equivalent to a NOP.
1506 if (next
->read
== 2 || prev
->read
== 2)
1509 * Is the <prev> -> <next> dependency already present?
1511 * (this may occur even though this is a new chain: consider
1512 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1513 * chains - the second one will be new, but L1 already has
1514 * L2 added to its dependency list, due to the first chain.)
1516 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1517 if (entry
->class == hlock_class(next
)) {
1519 entry
->distance
= 1;
1525 * Ok, all validations passed, add the new lock
1526 * to the previous lock's dependency list:
1528 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1529 &hlock_class(prev
)->locks_after
,
1530 next
->acquire_ip
, distance
);
1535 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1536 &hlock_class(next
)->locks_before
,
1537 next
->acquire_ip
, distance
);
1542 * Debugging printouts:
1544 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1546 printk("\n new dependency: ");
1547 print_lock_name(hlock_class(prev
));
1549 print_lock_name(hlock_class(next
));
1552 return graph_lock();
1558 * Add the dependency to all directly-previous locks that are 'relevant'.
1559 * The ones that are relevant are (in increasing distance from curr):
1560 * all consecutive trylock entries and the final non-trylock entry - or
1561 * the end of this context's lock-chain - whichever comes first.
1564 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1566 int depth
= curr
->lockdep_depth
;
1567 struct held_lock
*hlock
;
1572 * Depth must not be zero for a non-head lock:
1577 * At least two relevant locks must exist for this
1580 if (curr
->held_locks
[depth
].irq_context
!=
1581 curr
->held_locks
[depth
-1].irq_context
)
1585 int distance
= curr
->lockdep_depth
- depth
+ 1;
1586 hlock
= curr
->held_locks
+ depth
-1;
1588 * Only non-recursive-read entries get new dependencies
1591 if (hlock
->read
!= 2) {
1592 if (!check_prev_add(curr
, hlock
, next
, distance
))
1595 * Stop after the first non-trylock entry,
1596 * as non-trylock entries have added their
1597 * own direct dependencies already, so this
1598 * lock is connected to them indirectly:
1600 if (!hlock
->trylock
)
1605 * End of lock-stack?
1610 * Stop the search if we cross into another context:
1612 if (curr
->held_locks
[depth
].irq_context
!=
1613 curr
->held_locks
[depth
-1].irq_context
)
1618 if (!debug_locks_off_graph_unlock())
1626 unsigned long nr_lock_chains
;
1627 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1628 int nr_chain_hlocks
;
1629 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1631 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1633 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1637 * Look up a dependency chain. If the key is not present yet then
1638 * add it and return 1 - in this case the new dependency chain is
1639 * validated. If the key is already hashed, return 0.
1640 * (On return with 1 graph_lock is held.)
1642 static inline int lookup_chain_cache(struct task_struct
*curr
,
1643 struct held_lock
*hlock
,
1646 struct lock_class
*class = hlock_class(hlock
);
1647 struct list_head
*hash_head
= chainhashentry(chain_key
);
1648 struct lock_chain
*chain
;
1649 struct held_lock
*hlock_curr
, *hlock_next
;
1652 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1655 * We can walk it lock-free, because entries only get added
1658 list_for_each_entry(chain
, hash_head
, entry
) {
1659 if (chain
->chain_key
== chain_key
) {
1661 debug_atomic_inc(&chain_lookup_hits
);
1662 if (very_verbose(class))
1663 printk("\nhash chain already cached, key: "
1664 "%016Lx tail class: [%p] %s\n",
1665 (unsigned long long)chain_key
,
1666 class->key
, class->name
);
1670 if (very_verbose(class))
1671 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1672 (unsigned long long)chain_key
, class->key
, class->name
);
1674 * Allocate a new chain entry from the static array, and add
1680 * We have to walk the chain again locked - to avoid duplicates:
1682 list_for_each_entry(chain
, hash_head
, entry
) {
1683 if (chain
->chain_key
== chain_key
) {
1688 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1689 if (!debug_locks_off_graph_unlock())
1692 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1693 printk("turning off the locking correctness validator.\n");
1696 chain
= lock_chains
+ nr_lock_chains
++;
1697 chain
->chain_key
= chain_key
;
1698 chain
->irq_context
= hlock
->irq_context
;
1699 /* Find the first held_lock of current chain */
1701 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
1702 hlock_curr
= curr
->held_locks
+ i
;
1703 if (hlock_curr
->irq_context
!= hlock_next
->irq_context
)
1708 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
1709 cn
= nr_chain_hlocks
;
1710 while (cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
) {
1711 n
= cmpxchg(&nr_chain_hlocks
, cn
, cn
+ chain
->depth
);
1716 if (likely(cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
1718 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
1719 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
1720 chain_hlocks
[chain
->base
+ j
] = lock_id
;
1722 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
1724 list_add_tail_rcu(&chain
->entry
, hash_head
);
1725 debug_atomic_inc(&chain_lookup_misses
);
1731 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
1732 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
1735 * Trylock needs to maintain the stack of held locks, but it
1736 * does not add new dependencies, because trylock can be done
1739 * We look up the chain_key and do the O(N^2) check and update of
1740 * the dependencies only if this is a new dependency chain.
1741 * (If lookup_chain_cache() returns with 1 it acquires
1742 * graph_lock for us)
1744 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
1745 lookup_chain_cache(curr
, hlock
, chain_key
)) {
1747 * Check whether last held lock:
1749 * - is irq-safe, if this lock is irq-unsafe
1750 * - is softirq-safe, if this lock is hardirq-unsafe
1752 * And check whether the new lock's dependency graph
1753 * could lead back to the previous lock.
1755 * any of these scenarios could lead to a deadlock. If
1758 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
1763 * Mark recursive read, as we jump over it when
1764 * building dependencies (just like we jump over
1770 * Add dependency only if this lock is not the head
1771 * of the chain, and if it's not a secondary read-lock:
1773 if (!chain_head
&& ret
!= 2)
1774 if (!check_prevs_add(curr
, hlock
))
1778 /* after lookup_chain_cache(): */
1779 if (unlikely(!debug_locks
))
1785 static inline int validate_chain(struct task_struct
*curr
,
1786 struct lockdep_map
*lock
, struct held_lock
*hlock
,
1787 int chain_head
, u64 chain_key
)
1794 * We are building curr_chain_key incrementally, so double-check
1795 * it from scratch, to make sure that it's done correctly:
1797 static void check_chain_key(struct task_struct
*curr
)
1799 #ifdef CONFIG_DEBUG_LOCKDEP
1800 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1804 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1805 hlock
= curr
->held_locks
+ i
;
1806 if (chain_key
!= hlock
->prev_chain_key
) {
1808 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1809 curr
->lockdep_depth
, i
,
1810 (unsigned long long)chain_key
,
1811 (unsigned long long)hlock
->prev_chain_key
);
1814 id
= hlock
->class_idx
- 1;
1815 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
1818 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1819 hlock
->irq_context
))
1821 chain_key
= iterate_chain_key(chain_key
, id
);
1824 if (chain_key
!= curr
->curr_chain_key
) {
1826 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1827 curr
->lockdep_depth
, i
,
1828 (unsigned long long)chain_key
,
1829 (unsigned long long)curr
->curr_chain_key
);
1835 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1836 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1838 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1841 printk("\n=================================\n");
1842 printk( "[ INFO: inconsistent lock state ]\n");
1843 print_kernel_version();
1844 printk( "---------------------------------\n");
1846 printk("inconsistent {%s} -> {%s} usage.\n",
1847 usage_str
[prev_bit
], usage_str
[new_bit
]);
1849 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1850 curr
->comm
, task_pid_nr(curr
),
1851 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1852 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1853 trace_hardirqs_enabled(curr
),
1854 trace_softirqs_enabled(curr
));
1857 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1858 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
1860 print_irqtrace_events(curr
);
1861 printk("\nother info that might help us debug this:\n");
1862 lockdep_print_held_locks(curr
);
1864 printk("\nstack backtrace:\n");
1871 * Print out an error if an invalid bit is set:
1874 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1875 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1877 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
1878 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1882 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1883 enum lock_usage_bit new_bit
);
1885 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1888 * print irq inversion bug:
1891 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
1892 struct held_lock
*this, int forwards
,
1893 const char *irqclass
)
1895 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1898 printk("\n=========================================================\n");
1899 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1900 print_kernel_version();
1901 printk( "---------------------------------------------------------\n");
1902 printk("%s/%d just changed the state of lock:\n",
1903 curr
->comm
, task_pid_nr(curr
));
1906 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass
);
1908 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass
);
1909 print_lock_name(other
);
1910 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1912 printk("\nother info that might help us debug this:\n");
1913 lockdep_print_held_locks(curr
);
1915 printk("\nthe first lock's dependencies:\n");
1916 print_lock_dependencies(hlock_class(this), 0);
1918 printk("\nthe second lock's dependencies:\n");
1919 print_lock_dependencies(other
, 0);
1921 printk("\nstack backtrace:\n");
1928 * Prove that in the forwards-direction subgraph starting at <this>
1929 * there is no lock matching <mask>:
1932 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
1933 enum lock_usage_bit bit
, const char *irqclass
)
1937 find_usage_bit
= bit
;
1938 /* fills in <forwards_match> */
1939 ret
= find_usage_forwards(hlock_class(this), 0);
1940 if (!ret
|| ret
== 1)
1943 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
1947 * Prove that in the backwards-direction subgraph starting at <this>
1948 * there is no lock matching <mask>:
1951 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
1952 enum lock_usage_bit bit
, const char *irqclass
)
1956 find_usage_bit
= bit
;
1957 /* fills in <backwards_match> */
1958 ret
= find_usage_backwards(hlock_class(this), 0);
1959 if (!ret
|| ret
== 1)
1962 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
1965 void print_irqtrace_events(struct task_struct
*curr
)
1967 printk("irq event stamp: %u\n", curr
->irq_events
);
1968 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
1969 print_ip_sym(curr
->hardirq_enable_ip
);
1970 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
1971 print_ip_sym(curr
->hardirq_disable_ip
);
1972 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
1973 print_ip_sym(curr
->softirq_enable_ip
);
1974 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
1975 print_ip_sym(curr
->softirq_disable_ip
);
1978 static int HARDIRQ_verbose(struct lock_class
*class)
1981 return class_filter(class);
1986 static int SOFTIRQ_verbose(struct lock_class
*class)
1989 return class_filter(class);
1994 static int RECLAIM_FS_verbose(struct lock_class
*class)
1997 return class_filter(class);
2002 #define STRICT_READ_CHECKS 1
2004 static const char *state_names
[] = {
2005 #define LOCKDEP_STATE(__STATE) \
2007 #include "lockdep_states.h"
2008 #undef LOCKDEP_STATE
2011 static inline const char *state_name(enum lock_usage_bit bit
)
2013 return state_names
[bit
>> 2];
2016 static const char *state_rnames
[] = {
2017 #define LOCKDEP_STATE(__STATE) \
2018 STR(__STATE)"-READ",
2019 #include "lockdep_states.h"
2020 #undef LOCKDEP_STATE
2023 static inline const char *state_rname(enum lock_usage_bit bit
)
2025 return state_rnames
[bit
>> 2];
2028 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2029 #define LOCKDEP_STATE(__STATE) \
2031 #include "lockdep_states.h"
2032 #undef LOCKDEP_STATE
2035 static inline int state_verbose(enum lock_usage_bit bit
,
2036 struct lock_class
*class)
2038 return state_verbose_f
[bit
>> 2](class);
2041 static int exclusive_bit(int new_bit
)
2049 * bit 0 - write/read
2050 * bit 1 - used_in/enabled
2054 int state
= new_bit
& ~3;
2055 int dir
= new_bit
& 2;
2058 * keep state, bit flip the direction and strip read.
2060 return state
| (dir
^ 2);
2063 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2064 enum lock_usage_bit bit
, const char *name
);
2067 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this, int new_bit
)
2069 const char *name
= state_name(new_bit
);
2070 const char *rname
= state_rname(new_bit
);
2072 int excl_bit
= exclusive_bit(new_bit
);
2073 int read
= new_bit
& 1;
2074 int dir
= new_bit
& 2;
2077 * mark USED_IN has to look forwards -- to ensure no dependency
2078 * has ENABLED state, which would allow recursion deadlocks.
2080 * mark ENABLED has to look backwards -- to ensure no dependee
2081 * has USED_IN state, which, again, would allow recursion deadlocks.
2083 check_usage_f usage
= dir
?
2084 check_usage_backwards
: check_usage_forwards
;
2087 * Validate that this particular lock does not have conflicting
2090 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2094 * Validate that the lock dependencies don't have conflicting usage
2097 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2098 !usage(curr
, this, excl_bit
, name
))
2102 * Check for read in write conflicts
2105 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2108 if (STRICT_READ_CHECKS
&&
2109 !usage(curr
, this, excl_bit
+ 1, rname
))
2113 if (state_verbose(new_bit
, hlock_class(this)))
2120 #define LOCKDEP_STATE(__STATE) __STATE,
2121 #include "lockdep_states.h"
2122 #undef LOCKDEP_STATE
2126 * Mark all held locks with a usage bit:
2129 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2131 enum lock_usage_bit usage_bit
;
2132 struct held_lock
*hlock
;
2135 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2136 hlock
= curr
->held_locks
+ i
;
2138 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2140 usage_bit
+= 1; /* READ */
2142 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2144 if (!mark_lock(curr
, hlock
, usage_bit
))
2152 * Debugging helper: via this flag we know that we are in
2153 * 'early bootup code', and will warn about any invalid irqs-on event:
2155 static int early_boot_irqs_enabled
;
2157 void early_boot_irqs_off(void)
2159 early_boot_irqs_enabled
= 0;
2162 void early_boot_irqs_on(void)
2164 early_boot_irqs_enabled
= 1;
2168 * Hardirqs will be enabled:
2170 void trace_hardirqs_on_caller(unsigned long ip
)
2172 struct task_struct
*curr
= current
;
2174 time_hardirqs_on(CALLER_ADDR0
, ip
);
2176 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2179 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
2182 if (unlikely(curr
->hardirqs_enabled
)) {
2183 debug_atomic_inc(&redundant_hardirqs_on
);
2186 /* we'll do an OFF -> ON transition: */
2187 curr
->hardirqs_enabled
= 1;
2189 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2191 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2194 * We are going to turn hardirqs on, so set the
2195 * usage bit for all held locks:
2197 if (!mark_held_locks(curr
, HARDIRQ
))
2200 * If we have softirqs enabled, then set the usage
2201 * bit for all held locks. (disabled hardirqs prevented
2202 * this bit from being set before)
2204 if (curr
->softirqs_enabled
)
2205 if (!mark_held_locks(curr
, SOFTIRQ
))
2208 curr
->hardirq_enable_ip
= ip
;
2209 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2210 debug_atomic_inc(&hardirqs_on_events
);
2212 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2214 void trace_hardirqs_on(void)
2216 trace_hardirqs_on_caller(CALLER_ADDR0
);
2218 EXPORT_SYMBOL(trace_hardirqs_on
);
2221 * Hardirqs were disabled:
2223 void trace_hardirqs_off_caller(unsigned long ip
)
2225 struct task_struct
*curr
= current
;
2227 time_hardirqs_off(CALLER_ADDR0
, ip
);
2229 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2232 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2235 if (curr
->hardirqs_enabled
) {
2237 * We have done an ON -> OFF transition:
2239 curr
->hardirqs_enabled
= 0;
2240 curr
->hardirq_disable_ip
= ip
;
2241 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2242 debug_atomic_inc(&hardirqs_off_events
);
2244 debug_atomic_inc(&redundant_hardirqs_off
);
2246 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2248 void trace_hardirqs_off(void)
2250 trace_hardirqs_off_caller(CALLER_ADDR0
);
2252 EXPORT_SYMBOL(trace_hardirqs_off
);
2255 * Softirqs will be enabled:
2257 void trace_softirqs_on(unsigned long ip
)
2259 struct task_struct
*curr
= current
;
2261 if (unlikely(!debug_locks
))
2264 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2267 if (curr
->softirqs_enabled
) {
2268 debug_atomic_inc(&redundant_softirqs_on
);
2273 * We'll do an OFF -> ON transition:
2275 curr
->softirqs_enabled
= 1;
2276 curr
->softirq_enable_ip
= ip
;
2277 curr
->softirq_enable_event
= ++curr
->irq_events
;
2278 debug_atomic_inc(&softirqs_on_events
);
2280 * We are going to turn softirqs on, so set the
2281 * usage bit for all held locks, if hardirqs are
2284 if (curr
->hardirqs_enabled
)
2285 mark_held_locks(curr
, SOFTIRQ
);
2289 * Softirqs were disabled:
2291 void trace_softirqs_off(unsigned long ip
)
2293 struct task_struct
*curr
= current
;
2295 if (unlikely(!debug_locks
))
2298 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2301 if (curr
->softirqs_enabled
) {
2303 * We have done an ON -> OFF transition:
2305 curr
->softirqs_enabled
= 0;
2306 curr
->softirq_disable_ip
= ip
;
2307 curr
->softirq_disable_event
= ++curr
->irq_events
;
2308 debug_atomic_inc(&softirqs_off_events
);
2309 DEBUG_LOCKS_WARN_ON(!softirq_count());
2311 debug_atomic_inc(&redundant_softirqs_off
);
2314 void lockdep_trace_alloc(gfp_t gfp_mask
)
2316 struct task_struct
*curr
= current
;
2318 if (unlikely(!debug_locks
))
2321 /* no reclaim without waiting on it */
2322 if (!(gfp_mask
& __GFP_WAIT
))
2325 /* this guy won't enter reclaim */
2326 if ((curr
->flags
& PF_MEMALLOC
) && !(gfp_mask
& __GFP_NOMEMALLOC
))
2329 /* We're only interested __GFP_FS allocations for now */
2330 if (!(gfp_mask
& __GFP_FS
))
2333 if (DEBUG_LOCKS_WARN_ON(irqs_disabled()))
2336 mark_held_locks(curr
, RECLAIM_FS
);
2339 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2342 * If non-trylock use in a hardirq or softirq context, then
2343 * mark the lock as used in these contexts:
2345 if (!hlock
->trylock
) {
2347 if (curr
->hardirq_context
)
2348 if (!mark_lock(curr
, hlock
,
2349 LOCK_USED_IN_HARDIRQ_READ
))
2351 if (curr
->softirq_context
)
2352 if (!mark_lock(curr
, hlock
,
2353 LOCK_USED_IN_SOFTIRQ_READ
))
2356 if (curr
->hardirq_context
)
2357 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2359 if (curr
->softirq_context
)
2360 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2364 if (!hlock
->hardirqs_off
) {
2366 if (!mark_lock(curr
, hlock
,
2367 LOCK_ENABLED_HARDIRQ_READ
))
2369 if (curr
->softirqs_enabled
)
2370 if (!mark_lock(curr
, hlock
,
2371 LOCK_ENABLED_SOFTIRQ_READ
))
2374 if (!mark_lock(curr
, hlock
,
2375 LOCK_ENABLED_HARDIRQ
))
2377 if (curr
->softirqs_enabled
)
2378 if (!mark_lock(curr
, hlock
,
2379 LOCK_ENABLED_SOFTIRQ
))
2385 * We reuse the irq context infrastructure more broadly as a general
2386 * context checking code. This tests GFP_FS recursion (a lock taken
2387 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2390 if (!hlock
->trylock
&& (curr
->lockdep_reclaim_gfp
& __GFP_FS
)) {
2392 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS_READ
))
2395 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS
))
2403 static int separate_irq_context(struct task_struct
*curr
,
2404 struct held_lock
*hlock
)
2406 unsigned int depth
= curr
->lockdep_depth
;
2409 * Keep track of points where we cross into an interrupt context:
2411 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2412 curr
->softirq_context
;
2414 struct held_lock
*prev_hlock
;
2416 prev_hlock
= curr
->held_locks
+ depth
-1;
2418 * If we cross into another context, reset the
2419 * hash key (this also prevents the checking and the
2420 * adding of the dependency to 'prev'):
2422 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2431 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2432 enum lock_usage_bit new_bit
)
2438 static inline int mark_irqflags(struct task_struct
*curr
,
2439 struct held_lock
*hlock
)
2444 static inline int separate_irq_context(struct task_struct
*curr
,
2445 struct held_lock
*hlock
)
2453 * Mark a lock with a usage bit, and validate the state transition:
2455 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2456 enum lock_usage_bit new_bit
)
2458 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2461 * If already set then do not dirty the cacheline,
2462 * nor do any checks:
2464 if (likely(hlock_class(this)->usage_mask
& new_mask
))
2470 * Make sure we didnt race:
2472 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
2477 hlock_class(this)->usage_mask
|= new_mask
;
2479 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
2483 #define LOCKDEP_STATE(__STATE) \
2484 case LOCK_USED_IN_##__STATE: \
2485 case LOCK_USED_IN_##__STATE##_READ: \
2486 case LOCK_ENABLED_##__STATE: \
2487 case LOCK_ENABLED_##__STATE##_READ:
2488 #include "lockdep_states.h"
2489 #undef LOCKDEP_STATE
2490 ret
= mark_lock_irq(curr
, this, new_bit
);
2495 debug_atomic_dec(&nr_unused_locks
);
2498 if (!debug_locks_off_graph_unlock())
2507 * We must printk outside of the graph_lock:
2510 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2512 print_irqtrace_events(curr
);
2520 * Initialize a lock instance's lock-class mapping info:
2522 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2523 struct lock_class_key
*key
, int subclass
)
2525 if (unlikely(!debug_locks
))
2528 if (DEBUG_LOCKS_WARN_ON(!key
))
2530 if (DEBUG_LOCKS_WARN_ON(!name
))
2533 * Sanity check, the lock-class key must be persistent:
2535 if (!static_obj(key
)) {
2536 printk("BUG: key %p not in .data!\n", key
);
2537 DEBUG_LOCKS_WARN_ON(1);
2542 lock
->class_cache
= NULL
;
2543 #ifdef CONFIG_LOCK_STAT
2544 lock
->cpu
= raw_smp_processor_id();
2547 register_lock_class(lock
, subclass
, 1);
2549 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2552 * This gets called for every mutex_lock*()/spin_lock*() operation.
2553 * We maintain the dependency maps and validate the locking attempt:
2555 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2556 int trylock
, int read
, int check
, int hardirqs_off
,
2557 struct lockdep_map
*nest_lock
, unsigned long ip
)
2559 struct task_struct
*curr
= current
;
2560 struct lock_class
*class = NULL
;
2561 struct held_lock
*hlock
;
2562 unsigned int depth
, id
;
2569 if (unlikely(!debug_locks
))
2572 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2575 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
2577 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2578 printk("turning off the locking correctness validator.\n");
2583 class = lock
->class_cache
;
2585 * Not cached yet or subclass?
2587 if (unlikely(!class)) {
2588 class = register_lock_class(lock
, subclass
, 0);
2592 debug_atomic_inc((atomic_t
*)&class->ops
);
2593 if (very_verbose(class)) {
2594 printk("\nacquire class [%p] %s", class->key
, class->name
);
2595 if (class->name_version
> 1)
2596 printk("#%d", class->name_version
);
2602 * Add the lock to the list of currently held locks.
2603 * (we dont increase the depth just yet, up until the
2604 * dependency checks are done)
2606 depth
= curr
->lockdep_depth
;
2607 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2610 hlock
= curr
->held_locks
+ depth
;
2611 if (DEBUG_LOCKS_WARN_ON(!class))
2613 hlock
->class_idx
= class - lock_classes
+ 1;
2614 hlock
->acquire_ip
= ip
;
2615 hlock
->instance
= lock
;
2616 hlock
->nest_lock
= nest_lock
;
2617 hlock
->trylock
= trylock
;
2619 hlock
->check
= check
;
2620 hlock
->hardirqs_off
= !!hardirqs_off
;
2621 #ifdef CONFIG_LOCK_STAT
2622 hlock
->waittime_stamp
= 0;
2623 hlock
->holdtime_stamp
= sched_clock();
2626 if (check
== 2 && !mark_irqflags(curr
, hlock
))
2629 /* mark it as used: */
2630 if (!mark_lock(curr
, hlock
, LOCK_USED
))
2634 * Calculate the chain hash: it's the combined hash of all the
2635 * lock keys along the dependency chain. We save the hash value
2636 * at every step so that we can get the current hash easily
2637 * after unlock. The chain hash is then used to cache dependency
2640 * The 'key ID' is what is the most compact key value to drive
2641 * the hash, not class->key.
2643 id
= class - lock_classes
;
2644 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2647 chain_key
= curr
->curr_chain_key
;
2649 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2654 hlock
->prev_chain_key
= chain_key
;
2655 if (separate_irq_context(curr
, hlock
)) {
2659 chain_key
= iterate_chain_key(chain_key
, id
);
2661 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
2664 curr
->curr_chain_key
= chain_key
;
2665 curr
->lockdep_depth
++;
2666 check_chain_key(curr
);
2667 #ifdef CONFIG_DEBUG_LOCKDEP
2668 if (unlikely(!debug_locks
))
2671 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2673 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2674 printk("turning off the locking correctness validator.\n");
2678 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2679 max_lockdep_depth
= curr
->lockdep_depth
;
2685 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2688 if (!debug_locks_off())
2690 if (debug_locks_silent
)
2693 printk("\n=====================================\n");
2694 printk( "[ BUG: bad unlock balance detected! ]\n");
2695 printk( "-------------------------------------\n");
2696 printk("%s/%d is trying to release lock (",
2697 curr
->comm
, task_pid_nr(curr
));
2698 print_lockdep_cache(lock
);
2701 printk("but there are no more locks to release!\n");
2702 printk("\nother info that might help us debug this:\n");
2703 lockdep_print_held_locks(curr
);
2705 printk("\nstack backtrace:\n");
2712 * Common debugging checks for both nested and non-nested unlock:
2714 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2717 if (unlikely(!debug_locks
))
2719 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2722 if (curr
->lockdep_depth
<= 0)
2723 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2729 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
2730 struct lock_class_key
*key
, unsigned int subclass
,
2733 struct task_struct
*curr
= current
;
2734 struct held_lock
*hlock
, *prev_hlock
;
2735 struct lock_class
*class;
2739 depth
= curr
->lockdep_depth
;
2740 if (DEBUG_LOCKS_WARN_ON(!depth
))
2744 for (i
= depth
-1; i
>= 0; i
--) {
2745 hlock
= curr
->held_locks
+ i
;
2747 * We must not cross into another context:
2749 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2751 if (hlock
->instance
== lock
)
2755 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2758 lockdep_init_map(lock
, name
, key
, 0);
2759 class = register_lock_class(lock
, subclass
, 0);
2760 hlock
->class_idx
= class - lock_classes
+ 1;
2762 curr
->lockdep_depth
= i
;
2763 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2765 for (; i
< depth
; i
++) {
2766 hlock
= curr
->held_locks
+ i
;
2767 if (!__lock_acquire(hlock
->instance
,
2768 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2769 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2770 hlock
->nest_lock
, hlock
->acquire_ip
))
2774 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
2780 * Remove the lock to the list of currently held locks in a
2781 * potentially non-nested (out of order) manner. This is a
2782 * relatively rare operation, as all the unlock APIs default
2783 * to nested mode (which uses lock_release()):
2786 lock_release_non_nested(struct task_struct
*curr
,
2787 struct lockdep_map
*lock
, unsigned long ip
)
2789 struct held_lock
*hlock
, *prev_hlock
;
2794 * Check whether the lock exists in the current stack
2797 depth
= curr
->lockdep_depth
;
2798 if (DEBUG_LOCKS_WARN_ON(!depth
))
2802 for (i
= depth
-1; i
>= 0; i
--) {
2803 hlock
= curr
->held_locks
+ i
;
2805 * We must not cross into another context:
2807 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2809 if (hlock
->instance
== lock
)
2813 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2816 lock_release_holdtime(hlock
);
2819 * We have the right lock to unlock, 'hlock' points to it.
2820 * Now we remove it from the stack, and add back the other
2821 * entries (if any), recalculating the hash along the way:
2823 curr
->lockdep_depth
= i
;
2824 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2826 for (i
++; i
< depth
; i
++) {
2827 hlock
= curr
->held_locks
+ i
;
2828 if (!__lock_acquire(hlock
->instance
,
2829 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2830 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2831 hlock
->nest_lock
, hlock
->acquire_ip
))
2835 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2841 * Remove the lock to the list of currently held locks - this gets
2842 * called on mutex_unlock()/spin_unlock*() (or on a failed
2843 * mutex_lock_interruptible()). This is done for unlocks that nest
2844 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2846 static int lock_release_nested(struct task_struct
*curr
,
2847 struct lockdep_map
*lock
, unsigned long ip
)
2849 struct held_lock
*hlock
;
2853 * Pop off the top of the lock stack:
2855 depth
= curr
->lockdep_depth
- 1;
2856 hlock
= curr
->held_locks
+ depth
;
2859 * Is the unlock non-nested:
2861 if (hlock
->instance
!= lock
)
2862 return lock_release_non_nested(curr
, lock
, ip
);
2863 curr
->lockdep_depth
--;
2865 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2868 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2870 lock_release_holdtime(hlock
);
2872 #ifdef CONFIG_DEBUG_LOCKDEP
2873 hlock
->prev_chain_key
= 0;
2874 hlock
->class_idx
= 0;
2875 hlock
->acquire_ip
= 0;
2876 hlock
->irq_context
= 0;
2882 * Remove the lock to the list of currently held locks - this gets
2883 * called on mutex_unlock()/spin_unlock*() (or on a failed
2884 * mutex_lock_interruptible()). This is done for unlocks that nest
2885 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2888 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2890 struct task_struct
*curr
= current
;
2892 if (!check_unlock(curr
, lock
, ip
))
2896 if (!lock_release_nested(curr
, lock
, ip
))
2899 if (!lock_release_non_nested(curr
, lock
, ip
))
2903 check_chain_key(curr
);
2907 * Check whether we follow the irq-flags state precisely:
2909 static void check_flags(unsigned long flags
)
2911 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2912 defined(CONFIG_TRACE_IRQFLAGS)
2916 if (irqs_disabled_flags(flags
)) {
2917 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
2918 printk("possible reason: unannotated irqs-off.\n");
2921 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
2922 printk("possible reason: unannotated irqs-on.\n");
2927 * We dont accurately track softirq state in e.g.
2928 * hardirq contexts (such as on 4KSTACKS), so only
2929 * check if not in hardirq contexts:
2931 if (!hardirq_count()) {
2932 if (softirq_count())
2933 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
2935 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
2939 print_irqtrace_events(current
);
2943 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
2944 struct lock_class_key
*key
, unsigned int subclass
,
2947 unsigned long flags
;
2949 if (unlikely(current
->lockdep_recursion
))
2952 raw_local_irq_save(flags
);
2953 current
->lockdep_recursion
= 1;
2955 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
2956 check_chain_key(current
);
2957 current
->lockdep_recursion
= 0;
2958 raw_local_irq_restore(flags
);
2960 EXPORT_SYMBOL_GPL(lock_set_class
);
2963 * We are not always called with irqs disabled - do that here,
2964 * and also avoid lockdep recursion:
2966 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2967 int trylock
, int read
, int check
,
2968 struct lockdep_map
*nest_lock
, unsigned long ip
)
2970 unsigned long flags
;
2972 if (unlikely(current
->lockdep_recursion
))
2975 raw_local_irq_save(flags
);
2978 current
->lockdep_recursion
= 1;
2979 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
2980 irqs_disabled_flags(flags
), nest_lock
, ip
);
2981 current
->lockdep_recursion
= 0;
2982 raw_local_irq_restore(flags
);
2984 EXPORT_SYMBOL_GPL(lock_acquire
);
2986 void lock_release(struct lockdep_map
*lock
, int nested
,
2989 unsigned long flags
;
2991 if (unlikely(current
->lockdep_recursion
))
2994 raw_local_irq_save(flags
);
2996 current
->lockdep_recursion
= 1;
2997 __lock_release(lock
, nested
, ip
);
2998 current
->lockdep_recursion
= 0;
2999 raw_local_irq_restore(flags
);
3001 EXPORT_SYMBOL_GPL(lock_release
);
3003 void lockdep_set_current_reclaim_state(gfp_t gfp_mask
)
3005 current
->lockdep_reclaim_gfp
= gfp_mask
;
3008 void lockdep_clear_current_reclaim_state(void)
3010 current
->lockdep_reclaim_gfp
= 0;
3013 #ifdef CONFIG_LOCK_STAT
3015 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3018 if (!debug_locks_off())
3020 if (debug_locks_silent
)
3023 printk("\n=================================\n");
3024 printk( "[ BUG: bad contention detected! ]\n");
3025 printk( "---------------------------------\n");
3026 printk("%s/%d is trying to contend lock (",
3027 curr
->comm
, task_pid_nr(curr
));
3028 print_lockdep_cache(lock
);
3031 printk("but there are no locks held!\n");
3032 printk("\nother info that might help us debug this:\n");
3033 lockdep_print_held_locks(curr
);
3035 printk("\nstack backtrace:\n");
3042 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3044 struct task_struct
*curr
= current
;
3045 struct held_lock
*hlock
, *prev_hlock
;
3046 struct lock_class_stats
*stats
;
3048 int i
, contention_point
, contending_point
;
3050 depth
= curr
->lockdep_depth
;
3051 if (DEBUG_LOCKS_WARN_ON(!depth
))
3055 for (i
= depth
-1; i
>= 0; i
--) {
3056 hlock
= curr
->held_locks
+ i
;
3058 * We must not cross into another context:
3060 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3062 if (hlock
->instance
== lock
)
3066 print_lock_contention_bug(curr
, lock
, ip
);
3070 hlock
->waittime_stamp
= sched_clock();
3072 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3073 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3076 stats
= get_lock_stats(hlock_class(hlock
));
3077 if (contention_point
< LOCKSTAT_POINTS
)
3078 stats
->contention_point
[contention_point
]++;
3079 if (contending_point
< LOCKSTAT_POINTS
)
3080 stats
->contending_point
[contending_point
]++;
3081 if (lock
->cpu
!= smp_processor_id())
3082 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3083 put_lock_stats(stats
);
3087 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3089 struct task_struct
*curr
= current
;
3090 struct held_lock
*hlock
, *prev_hlock
;
3091 struct lock_class_stats
*stats
;
3097 depth
= curr
->lockdep_depth
;
3098 if (DEBUG_LOCKS_WARN_ON(!depth
))
3102 for (i
= depth
-1; i
>= 0; i
--) {
3103 hlock
= curr
->held_locks
+ i
;
3105 * We must not cross into another context:
3107 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3109 if (hlock
->instance
== lock
)
3113 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3117 cpu
= smp_processor_id();
3118 if (hlock
->waittime_stamp
) {
3119 now
= sched_clock();
3120 waittime
= now
- hlock
->waittime_stamp
;
3121 hlock
->holdtime_stamp
= now
;
3124 stats
= get_lock_stats(hlock_class(hlock
));
3127 lock_time_inc(&stats
->read_waittime
, waittime
);
3129 lock_time_inc(&stats
->write_waittime
, waittime
);
3131 if (lock
->cpu
!= cpu
)
3132 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3133 put_lock_stats(stats
);
3139 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3141 unsigned long flags
;
3143 if (unlikely(!lock_stat
))
3146 if (unlikely(current
->lockdep_recursion
))
3149 raw_local_irq_save(flags
);
3151 current
->lockdep_recursion
= 1;
3152 __lock_contended(lock
, ip
);
3153 current
->lockdep_recursion
= 0;
3154 raw_local_irq_restore(flags
);
3156 EXPORT_SYMBOL_GPL(lock_contended
);
3158 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3160 unsigned long flags
;
3162 if (unlikely(!lock_stat
))
3165 if (unlikely(current
->lockdep_recursion
))
3168 raw_local_irq_save(flags
);
3170 current
->lockdep_recursion
= 1;
3171 __lock_acquired(lock
, ip
);
3172 current
->lockdep_recursion
= 0;
3173 raw_local_irq_restore(flags
);
3175 EXPORT_SYMBOL_GPL(lock_acquired
);
3179 * Used by the testsuite, sanitize the validator state
3180 * after a simulated failure:
3183 void lockdep_reset(void)
3185 unsigned long flags
;
3188 raw_local_irq_save(flags
);
3189 current
->curr_chain_key
= 0;
3190 current
->lockdep_depth
= 0;
3191 current
->lockdep_recursion
= 0;
3192 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3193 nr_hardirq_chains
= 0;
3194 nr_softirq_chains
= 0;
3195 nr_process_chains
= 0;
3197 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3198 INIT_LIST_HEAD(chainhash_table
+ i
);
3199 raw_local_irq_restore(flags
);
3202 static void zap_class(struct lock_class
*class)
3207 * Remove all dependencies this lock is
3210 for (i
= 0; i
< nr_list_entries
; i
++) {
3211 if (list_entries
[i
].class == class)
3212 list_del_rcu(&list_entries
[i
].entry
);
3215 * Unhash the class and remove it from the all_lock_classes list:
3217 list_del_rcu(&class->hash_entry
);
3218 list_del_rcu(&class->lock_entry
);
3223 static inline int within(const void *addr
, void *start
, unsigned long size
)
3225 return addr
>= start
&& addr
< start
+ size
;
3228 void lockdep_free_key_range(void *start
, unsigned long size
)
3230 struct lock_class
*class, *next
;
3231 struct list_head
*head
;
3232 unsigned long flags
;
3236 raw_local_irq_save(flags
);
3237 locked
= graph_lock();
3240 * Unhash all classes that were created by this module:
3242 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3243 head
= classhash_table
+ i
;
3244 if (list_empty(head
))
3246 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3247 if (within(class->key
, start
, size
))
3249 else if (within(class->name
, start
, size
))
3256 raw_local_irq_restore(flags
);
3259 void lockdep_reset_lock(struct lockdep_map
*lock
)
3261 struct lock_class
*class, *next
;
3262 struct list_head
*head
;
3263 unsigned long flags
;
3267 raw_local_irq_save(flags
);
3270 * Remove all classes this lock might have:
3272 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3274 * If the class exists we look it up and zap it:
3276 class = look_up_lock_class(lock
, j
);
3281 * Debug check: in the end all mapped classes should
3284 locked
= graph_lock();
3285 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3286 head
= classhash_table
+ i
;
3287 if (list_empty(head
))
3289 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3290 if (unlikely(class == lock
->class_cache
)) {
3291 if (debug_locks_off_graph_unlock())
3301 raw_local_irq_restore(flags
);
3304 void lockdep_init(void)
3309 * Some architectures have their own start_kernel()
3310 * code which calls lockdep_init(), while we also
3311 * call lockdep_init() from the start_kernel() itself,
3312 * and we want to initialize the hashes only once:
3314 if (lockdep_initialized
)
3317 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3318 INIT_LIST_HEAD(classhash_table
+ i
);
3320 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3321 INIT_LIST_HEAD(chainhash_table
+ i
);
3323 lockdep_initialized
= 1;
3326 void __init
lockdep_info(void)
3328 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3330 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
3331 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
3332 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
3333 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
3334 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
3335 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
3336 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
3338 printk(" memory used by lock dependency info: %lu kB\n",
3339 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
3340 sizeof(struct list_head
) * CLASSHASH_SIZE
+
3341 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
3342 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
3343 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
3345 printk(" per task-struct memory footprint: %lu bytes\n",
3346 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
3348 #ifdef CONFIG_DEBUG_LOCKDEP
3349 if (lockdep_init_error
) {
3350 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3351 printk("Call stack leading to lockdep invocation was:\n");
3352 print_stack_trace(&lockdep_init_trace
, 0);
3358 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
3359 const void *mem_to
, struct held_lock
*hlock
)
3361 if (!debug_locks_off())
3363 if (debug_locks_silent
)
3366 printk("\n=========================\n");
3367 printk( "[ BUG: held lock freed! ]\n");
3368 printk( "-------------------------\n");
3369 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3370 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
3372 lockdep_print_held_locks(curr
);
3374 printk("\nstack backtrace:\n");
3378 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
3379 const void* lock_from
, unsigned long lock_len
)
3381 return lock_from
+ lock_len
<= mem_from
||
3382 mem_from
+ mem_len
<= lock_from
;
3386 * Called when kernel memory is freed (or unmapped), or if a lock
3387 * is destroyed or reinitialized - this code checks whether there is
3388 * any held lock in the memory range of <from> to <to>:
3390 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
3392 struct task_struct
*curr
= current
;
3393 struct held_lock
*hlock
;
3394 unsigned long flags
;
3397 if (unlikely(!debug_locks
))
3400 local_irq_save(flags
);
3401 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3402 hlock
= curr
->held_locks
+ i
;
3404 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
3405 sizeof(*hlock
->instance
)))
3408 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
3411 local_irq_restore(flags
);
3413 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
3415 static void print_held_locks_bug(struct task_struct
*curr
)
3417 if (!debug_locks_off())
3419 if (debug_locks_silent
)
3422 printk("\n=====================================\n");
3423 printk( "[ BUG: lock held at task exit time! ]\n");
3424 printk( "-------------------------------------\n");
3425 printk("%s/%d is exiting with locks still held!\n",
3426 curr
->comm
, task_pid_nr(curr
));
3427 lockdep_print_held_locks(curr
);
3429 printk("\nstack backtrace:\n");
3433 void debug_check_no_locks_held(struct task_struct
*task
)
3435 if (unlikely(task
->lockdep_depth
> 0))
3436 print_held_locks_bug(task
);
3439 void debug_show_all_locks(void)
3441 struct task_struct
*g
, *p
;
3445 if (unlikely(!debug_locks
)) {
3446 printk("INFO: lockdep is turned off.\n");
3449 printk("\nShowing all locks held in the system:\n");
3452 * Here we try to get the tasklist_lock as hard as possible,
3453 * if not successful after 2 seconds we ignore it (but keep
3454 * trying). This is to enable a debug printout even if a
3455 * tasklist_lock-holding task deadlocks or crashes.
3458 if (!read_trylock(&tasklist_lock
)) {
3460 printk("hm, tasklist_lock locked, retrying... ");
3463 printk(" #%d", 10-count
);
3467 printk(" ignoring it.\n");
3471 printk(KERN_CONT
" locked it.\n");
3474 do_each_thread(g
, p
) {
3476 * It's not reliable to print a task's held locks
3477 * if it's not sleeping (or if it's not the current
3480 if (p
->state
== TASK_RUNNING
&& p
!= current
)
3482 if (p
->lockdep_depth
)
3483 lockdep_print_held_locks(p
);
3485 if (read_trylock(&tasklist_lock
))
3487 } while_each_thread(g
, p
);
3490 printk("=============================================\n\n");
3493 read_unlock(&tasklist_lock
);
3495 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
3498 * Careful: only use this function if you are sure that
3499 * the task cannot run in parallel!
3501 void __debug_show_held_locks(struct task_struct
*task
)
3503 if (unlikely(!debug_locks
)) {
3504 printk("INFO: lockdep is turned off.\n");
3507 lockdep_print_held_locks(task
);
3509 EXPORT_SYMBOL_GPL(__debug_show_held_locks
);
3511 void debug_show_held_locks(struct task_struct
*task
)
3513 __debug_show_held_locks(task
);
3515 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
3517 void lockdep_sys_exit(void)
3519 struct task_struct
*curr
= current
;
3521 if (unlikely(curr
->lockdep_depth
)) {
3522 if (!debug_locks_off())
3524 printk("\n================================================\n");
3525 printk( "[ BUG: lock held when returning to user space! ]\n");
3526 printk( "------------------------------------------------\n");
3527 printk("%s/%d is leaving the kernel with locks still held!\n",
3528 curr
->comm
, curr
->pid
);
3529 lockdep_print_held_locks(curr
);