4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <asm/sections.h>
48 #include "lockdep_internals.h"
50 #define CREATE_TRACE_POINTS
51 #include <trace/events/lockdep.h>
53 #ifdef CONFIG_PROVE_LOCKING
54 int prove_locking
= 1;
55 module_param(prove_locking
, int, 0644);
57 #define prove_locking 0
60 #ifdef CONFIG_LOCK_STAT
62 module_param(lock_stat
, int, 0644);
68 * lockdep_lock: protects the lockdep graph, the hashes and the
69 * class/list/hash allocators.
71 * This is one of the rare exceptions where it's justified
72 * to use a raw spinlock - we really dont want the spinlock
73 * code to recurse back into the lockdep code...
75 static raw_spinlock_t lockdep_lock
= (raw_spinlock_t
)__RAW_SPIN_LOCK_UNLOCKED
;
77 static int graph_lock(void)
79 __raw_spin_lock(&lockdep_lock
);
81 * Make sure that if another CPU detected a bug while
82 * walking the graph we dont change it (while the other
83 * CPU is busy printing out stuff with the graph lock
87 __raw_spin_unlock(&lockdep_lock
);
90 /* prevent any recursions within lockdep from causing deadlocks */
91 current
->lockdep_recursion
++;
95 static inline int graph_unlock(void)
97 if (debug_locks
&& !__raw_spin_is_locked(&lockdep_lock
))
98 return DEBUG_LOCKS_WARN_ON(1);
100 current
->lockdep_recursion
--;
101 __raw_spin_unlock(&lockdep_lock
);
106 * Turn lock debugging off and return with 0 if it was off already,
107 * and also release the graph lock:
109 static inline int debug_locks_off_graph_unlock(void)
111 int ret
= debug_locks_off();
113 __raw_spin_unlock(&lockdep_lock
);
118 static int lockdep_initialized
;
120 unsigned long nr_list_entries
;
121 struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
124 * All data structures here are protected by the global debug_lock.
126 * Mutex key structs only get allocated, once during bootup, and never
127 * get freed - this significantly simplifies the debugging code.
129 unsigned long nr_lock_classes
;
130 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
132 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
134 if (!hlock
->class_idx
) {
135 DEBUG_LOCKS_WARN_ON(1);
138 return lock_classes
+ hlock
->class_idx
- 1;
141 #ifdef CONFIG_LOCK_STAT
142 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
], lock_stats
);
144 static int lock_point(unsigned long points
[], unsigned long ip
)
148 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
149 if (points
[i
] == 0) {
160 static void lock_time_inc(struct lock_time
*lt
, s64 time
)
165 if (time
< lt
->min
|| !lt
->min
)
172 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
174 dst
->min
+= src
->min
;
175 dst
->max
+= src
->max
;
176 dst
->total
+= src
->total
;
180 struct lock_class_stats
lock_stats(struct lock_class
*class)
182 struct lock_class_stats stats
;
185 memset(&stats
, 0, sizeof(struct lock_class_stats
));
186 for_each_possible_cpu(cpu
) {
187 struct lock_class_stats
*pcs
=
188 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
190 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
191 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
193 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
194 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
196 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
197 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
199 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
200 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
202 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
203 stats
.bounces
[i
] += pcs
->bounces
[i
];
209 void clear_lock_stats(struct lock_class
*class)
213 for_each_possible_cpu(cpu
) {
214 struct lock_class_stats
*cpu_stats
=
215 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
217 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
219 memset(class->contention_point
, 0, sizeof(class->contention_point
));
220 memset(class->contending_point
, 0, sizeof(class->contending_point
));
223 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
225 return &get_cpu_var(lock_stats
)[class - lock_classes
];
228 static void put_lock_stats(struct lock_class_stats
*stats
)
230 put_cpu_var(lock_stats
);
233 static void lock_release_holdtime(struct held_lock
*hlock
)
235 struct lock_class_stats
*stats
;
241 holdtime
= sched_clock() - hlock
->holdtime_stamp
;
243 stats
= get_lock_stats(hlock_class(hlock
));
245 lock_time_inc(&stats
->read_holdtime
, holdtime
);
247 lock_time_inc(&stats
->write_holdtime
, holdtime
);
248 put_lock_stats(stats
);
251 static inline void lock_release_holdtime(struct held_lock
*hlock
)
257 * We keep a global list of all lock classes. The list only grows,
258 * never shrinks. The list is only accessed with the lockdep
259 * spinlock lock held.
261 LIST_HEAD(all_lock_classes
);
264 * The lockdep classes are in a hash-table as well, for fast lookup:
266 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
267 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
268 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
269 #define classhashentry(key) (classhash_table + __classhashfn((key)))
271 static struct list_head classhash_table
[CLASSHASH_SIZE
];
274 * We put the lock dependency chains into a hash-table as well, to cache
277 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
278 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
279 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
280 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
282 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
285 * The hash key of the lock dependency chains is a hash itself too:
286 * it's a hash of all locks taken up to that lock, including that lock.
287 * It's a 64-bit hash, because it's important for the keys to be
290 #define iterate_chain_key(key1, key2) \
291 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
292 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
295 void lockdep_off(void)
297 current
->lockdep_recursion
++;
299 EXPORT_SYMBOL(lockdep_off
);
301 void lockdep_on(void)
303 current
->lockdep_recursion
--;
305 EXPORT_SYMBOL(lockdep_on
);
308 * Debugging switches:
312 #define VERY_VERBOSE 0
315 # define HARDIRQ_VERBOSE 1
316 # define SOFTIRQ_VERBOSE 1
317 # define RECLAIM_VERBOSE 1
319 # define HARDIRQ_VERBOSE 0
320 # define SOFTIRQ_VERBOSE 0
321 # define RECLAIM_VERBOSE 0
324 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
326 * Quick filtering for interesting events:
328 static int class_filter(struct lock_class
*class)
332 if (class->name_version
== 1 &&
333 !strcmp(class->name
, "lockname"))
335 if (class->name_version
== 1 &&
336 !strcmp(class->name
, "&struct->lockfield"))
339 /* Filter everything else. 1 would be to allow everything else */
344 static int verbose(struct lock_class
*class)
347 return class_filter(class);
353 * Stack-trace: tightly packed array of stack backtrace
354 * addresses. Protected by the graph_lock.
356 unsigned long nr_stack_trace_entries
;
357 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
359 static int save_trace(struct stack_trace
*trace
)
361 trace
->nr_entries
= 0;
362 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
363 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
367 save_stack_trace(trace
);
369 trace
->max_entries
= trace
->nr_entries
;
371 nr_stack_trace_entries
+= trace
->nr_entries
;
373 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
374 if (!debug_locks_off_graph_unlock())
377 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
378 printk("turning off the locking correctness validator.\n");
387 unsigned int nr_hardirq_chains
;
388 unsigned int nr_softirq_chains
;
389 unsigned int nr_process_chains
;
390 unsigned int max_lockdep_depth
;
391 unsigned int max_recursion_depth
;
393 static unsigned int lockdep_dependency_gen_id
;
395 static bool lockdep_dependency_visit(struct lock_class
*source
,
399 lockdep_dependency_gen_id
++;
400 if (source
->dep_gen_id
== lockdep_dependency_gen_id
)
402 source
->dep_gen_id
= lockdep_dependency_gen_id
;
406 #ifdef CONFIG_DEBUG_LOCKDEP
408 * We cannot printk in early bootup code. Not even early_printk()
409 * might work. So we mark any initialization errors and printk
410 * about it later on, in lockdep_info().
412 static int lockdep_init_error
;
413 static unsigned long lockdep_init_trace_data
[20];
414 static struct stack_trace lockdep_init_trace
= {
415 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
416 .entries
= lockdep_init_trace_data
,
420 * Various lockdep statistics:
422 atomic_t chain_lookup_hits
;
423 atomic_t chain_lookup_misses
;
424 atomic_t hardirqs_on_events
;
425 atomic_t hardirqs_off_events
;
426 atomic_t redundant_hardirqs_on
;
427 atomic_t redundant_hardirqs_off
;
428 atomic_t softirqs_on_events
;
429 atomic_t softirqs_off_events
;
430 atomic_t redundant_softirqs_on
;
431 atomic_t redundant_softirqs_off
;
432 atomic_t nr_unused_locks
;
433 atomic_t nr_cyclic_checks
;
434 atomic_t nr_cyclic_check_recursions
;
435 atomic_t nr_find_usage_forwards_checks
;
436 atomic_t nr_find_usage_forwards_recursions
;
437 atomic_t nr_find_usage_backwards_checks
;
438 atomic_t nr_find_usage_backwards_recursions
;
445 #define __USAGE(__STATE) \
446 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
447 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
448 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
449 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
451 static const char *usage_str
[] =
453 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
454 #include "lockdep_states.h"
456 [LOCK_USED
] = "INITIAL USE",
459 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
461 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
464 static inline unsigned long lock_flag(enum lock_usage_bit bit
)
469 static char get_usage_char(struct lock_class
*class, enum lock_usage_bit bit
)
473 if (class->usage_mask
& lock_flag(bit
+ 2))
475 if (class->usage_mask
& lock_flag(bit
)) {
477 if (class->usage_mask
& lock_flag(bit
+ 2))
484 void get_usage_chars(struct lock_class
*class, char usage
[LOCK_USAGE_CHARS
])
488 #define LOCKDEP_STATE(__STATE) \
489 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
490 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
491 #include "lockdep_states.h"
497 static void print_lock_name(struct lock_class
*class)
499 char str
[KSYM_NAME_LEN
], usage
[LOCK_USAGE_CHARS
];
502 get_usage_chars(class, usage
);
506 name
= __get_key_name(class->key
, str
);
507 printk(" (%s", name
);
509 printk(" (%s", name
);
510 if (class->name_version
> 1)
511 printk("#%d", class->name_version
);
513 printk("/%d", class->subclass
);
515 printk("){%s}", usage
);
518 static void print_lockdep_cache(struct lockdep_map
*lock
)
521 char str
[KSYM_NAME_LEN
];
525 name
= __get_key_name(lock
->key
->subkeys
, str
);
530 static void print_lock(struct held_lock
*hlock
)
532 print_lock_name(hlock_class(hlock
));
534 print_ip_sym(hlock
->acquire_ip
);
537 static void lockdep_print_held_locks(struct task_struct
*curr
)
539 int i
, depth
= curr
->lockdep_depth
;
542 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
545 printk("%d lock%s held by %s/%d:\n",
546 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
548 for (i
= 0; i
< depth
; i
++) {
550 print_lock(curr
->held_locks
+ i
);
554 static void print_lock_class_header(struct lock_class
*class, int depth
)
558 printk("%*s->", depth
, "");
559 print_lock_name(class);
560 printk(" ops: %lu", class->ops
);
563 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
564 if (class->usage_mask
& (1 << bit
)) {
567 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
568 len
+= printk(" at:\n");
569 print_stack_trace(class->usage_traces
+ bit
, len
);
572 printk("%*s }\n", depth
, "");
574 printk("%*s ... key at: ",depth
,"");
575 print_ip_sym((unsigned long)class->key
);
579 * printk all lock dependencies starting at <entry>:
582 print_lock_dependencies(struct lock_class
*class, int depth
)
584 struct lock_list
*entry
;
586 if (lockdep_dependency_visit(class, depth
))
589 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
592 print_lock_class_header(class, depth
);
594 list_for_each_entry(entry
, &class->locks_after
, entry
) {
595 if (DEBUG_LOCKS_WARN_ON(!entry
->class))
598 print_lock_dependencies(entry
->class, depth
+ 1);
600 printk("%*s ... acquired at:\n",depth
,"");
601 print_stack_trace(&entry
->trace
, 2);
606 static void print_kernel_version(void)
608 printk("%s %.*s\n", init_utsname()->release
,
609 (int)strcspn(init_utsname()->version
, " "),
610 init_utsname()->version
);
613 static int very_verbose(struct lock_class
*class)
616 return class_filter(class);
622 * Is this the address of a static object:
624 static int static_obj(void *obj
)
626 unsigned long start
= (unsigned long) &_stext
,
627 end
= (unsigned long) &_end
,
628 addr
= (unsigned long) obj
;
636 if ((addr
>= start
) && (addr
< end
))
643 for_each_possible_cpu(i
) {
644 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
645 end
= (unsigned long) &__per_cpu_start
+ PERCPU_ENOUGH_ROOM
648 if ((addr
>= start
) && (addr
< end
))
656 return is_module_address(addr
);
660 * To make lock name printouts unique, we calculate a unique
661 * class->name_version generation counter:
663 static int count_matching_names(struct lock_class
*new_class
)
665 struct lock_class
*class;
668 if (!new_class
->name
)
671 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
672 if (new_class
->key
- new_class
->subclass
== class->key
)
673 return class->name_version
;
674 if (class->name
&& !strcmp(class->name
, new_class
->name
))
675 count
= max(count
, class->name_version
);
682 * Register a lock's class in the hash-table, if the class is not present
683 * yet. Otherwise we look it up. We cache the result in the lock object
684 * itself, so actual lookup of the hash should be once per lock object.
686 static inline struct lock_class
*
687 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
689 struct lockdep_subclass_key
*key
;
690 struct list_head
*hash_head
;
691 struct lock_class
*class;
693 #ifdef CONFIG_DEBUG_LOCKDEP
695 * If the architecture calls into lockdep before initializing
696 * the hashes then we'll warn about it later. (we cannot printk
699 if (unlikely(!lockdep_initialized
)) {
701 lockdep_init_error
= 1;
702 save_stack_trace(&lockdep_init_trace
);
707 * Static locks do not have their class-keys yet - for them the key
708 * is the lock object itself:
710 if (unlikely(!lock
->key
))
711 lock
->key
= (void *)lock
;
714 * NOTE: the class-key must be unique. For dynamic locks, a static
715 * lock_class_key variable is passed in through the mutex_init()
716 * (or spin_lock_init()) call - which acts as the key. For static
717 * locks we use the lock object itself as the key.
719 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
720 sizeof(struct lockdep_map
));
722 key
= lock
->key
->subkeys
+ subclass
;
724 hash_head
= classhashentry(key
);
727 * We can walk the hash lockfree, because the hash only
728 * grows, and we are careful when adding entries to the end:
730 list_for_each_entry(class, hash_head
, hash_entry
) {
731 if (class->key
== key
) {
732 WARN_ON_ONCE(class->name
!= lock
->name
);
741 * Register a lock's class in the hash-table, if the class is not present
742 * yet. Otherwise we look it up. We cache the result in the lock object
743 * itself, so actual lookup of the hash should be once per lock object.
745 static inline struct lock_class
*
746 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
748 struct lockdep_subclass_key
*key
;
749 struct list_head
*hash_head
;
750 struct lock_class
*class;
753 class = look_up_lock_class(lock
, subclass
);
758 * Debug-check: all keys must be persistent!
760 if (!static_obj(lock
->key
)) {
762 printk("INFO: trying to register non-static key.\n");
763 printk("the code is fine but needs lockdep annotation.\n");
764 printk("turning off the locking correctness validator.\n");
770 key
= lock
->key
->subkeys
+ subclass
;
771 hash_head
= classhashentry(key
);
773 raw_local_irq_save(flags
);
775 raw_local_irq_restore(flags
);
779 * We have to do the hash-walk again, to avoid races
782 list_for_each_entry(class, hash_head
, hash_entry
)
783 if (class->key
== key
)
786 * Allocate a new key from the static array, and add it to
789 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
790 if (!debug_locks_off_graph_unlock()) {
791 raw_local_irq_restore(flags
);
794 raw_local_irq_restore(flags
);
796 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
797 printk("turning off the locking correctness validator.\n");
801 class = lock_classes
+ nr_lock_classes
++;
802 debug_atomic_inc(&nr_unused_locks
);
804 class->name
= lock
->name
;
805 class->subclass
= subclass
;
806 INIT_LIST_HEAD(&class->lock_entry
);
807 INIT_LIST_HEAD(&class->locks_before
);
808 INIT_LIST_HEAD(&class->locks_after
);
809 class->name_version
= count_matching_names(class);
811 * We use RCU's safe list-add method to make
812 * parallel walking of the hash-list safe:
814 list_add_tail_rcu(&class->hash_entry
, hash_head
);
816 * Add it to the global list of classes:
818 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
820 if (verbose(class)) {
822 raw_local_irq_restore(flags
);
824 printk("\nnew class %p: %s", class->key
, class->name
);
825 if (class->name_version
> 1)
826 printk("#%d", class->name_version
);
830 raw_local_irq_save(flags
);
832 raw_local_irq_restore(flags
);
838 raw_local_irq_restore(flags
);
840 if (!subclass
|| force
)
841 lock
->class_cache
= class;
843 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
849 #ifdef CONFIG_PROVE_LOCKING
851 * Allocate a lockdep entry. (assumes the graph_lock held, returns
852 * with NULL on failure)
854 static struct lock_list
*alloc_list_entry(void)
856 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
857 if (!debug_locks_off_graph_unlock())
860 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
861 printk("turning off the locking correctness validator.\n");
865 return list_entries
+ nr_list_entries
++;
869 * Add a new dependency to the head of the list:
871 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
872 struct list_head
*head
, unsigned long ip
, int distance
)
874 struct lock_list
*entry
;
876 * Lock not present yet - get a new dependency struct and
877 * add it to the list:
879 entry
= alloc_list_entry();
883 if (!save_trace(&entry
->trace
))
887 entry
->distance
= distance
;
889 * Since we never remove from the dependency list, the list can
890 * be walked lockless by other CPUs, it's only allocation
891 * that must be protected by the spinlock. But this also means
892 * we must make new entries visible only once writes to the
893 * entry become visible - hence the RCU op:
895 list_add_tail_rcu(&entry
->entry
, head
);
900 unsigned long bfs_accessed
[BITS_TO_LONGS(MAX_LOCKDEP_ENTRIES
)];
901 static struct circular_queue lock_cq
;
903 static int __bfs(struct lock_list
*source_entry
,
905 int (*match
)(struct lock_list
*entry
, void *data
),
906 struct lock_list
**target_entry
,
909 struct lock_list
*entry
;
910 struct list_head
*head
;
911 struct circular_queue
*cq
= &lock_cq
;
914 if (match(source_entry
, data
)) {
915 *target_entry
= source_entry
;
921 head
= &source_entry
->class->locks_after
;
923 head
= &source_entry
->class->locks_before
;
925 if (list_empty(head
))
929 __cq_enqueue(cq
, (unsigned long)source_entry
);
931 while (!__cq_empty(cq
)) {
932 struct lock_list
*lock
;
934 __cq_dequeue(cq
, (unsigned long *)&lock
);
942 head
= &lock
->class->locks_after
;
944 head
= &lock
->class->locks_before
;
946 list_for_each_entry(entry
, head
, entry
) {
947 if (!lock_accessed(entry
)) {
948 mark_lock_accessed(entry
, lock
);
949 if (match(entry
, data
)) {
950 *target_entry
= entry
;
955 if (__cq_enqueue(cq
, (unsigned long)entry
)) {
966 static inline int __bfs_forward(struct lock_list
*src_entry
,
968 int (*match
)(struct lock_list
*entry
, void *data
),
969 struct lock_list
**target_entry
)
971 return __bfs(src_entry
, data
, match
, target_entry
, 1);
975 static inline int __bfs_backward(struct lock_list
*src_entry
,
977 int (*match
)(struct lock_list
*entry
, void *data
),
978 struct lock_list
**target_entry
)
980 return __bfs(src_entry
, data
, match
, target_entry
, 0);
985 * Recursive, forwards-direction lock-dependency checking, used for
986 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
991 * Print a dependency chain entry (this is only done when a deadlock
992 * has been detected):
995 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
997 if (debug_locks_silent
)
999 printk("\n-> #%u", depth
);
1000 print_lock_name(target
->class);
1002 print_stack_trace(&target
->trace
, 6);
1008 * When a circular dependency is detected, print the
1012 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
,
1013 struct held_lock
*check_src
,
1014 struct held_lock
*check_tgt
)
1016 struct task_struct
*curr
= current
;
1018 if (debug_locks_silent
)
1021 printk("\n=======================================================\n");
1022 printk( "[ INFO: possible circular locking dependency detected ]\n");
1023 print_kernel_version();
1024 printk( "-------------------------------------------------------\n");
1025 printk("%s/%d is trying to acquire lock:\n",
1026 curr
->comm
, task_pid_nr(curr
));
1027 print_lock(check_src
);
1028 printk("\nbut task is already holding lock:\n");
1029 print_lock(check_tgt
);
1030 printk("\nwhich lock already depends on the new lock.\n\n");
1031 printk("\nthe existing dependency chain (in reverse order) is:\n");
1033 print_circular_bug_entry(entry
, depth
);
1038 static inline int class_equal(struct lock_list
*entry
, void *data
)
1040 return entry
->class == data
;
1043 static noinline
int print_circular_bug(struct lock_list
*this,
1044 struct lock_list
*target
,
1045 struct held_lock
*check_src
,
1046 struct held_lock
*check_tgt
)
1048 struct task_struct
*curr
= current
;
1049 struct lock_list
*parent
;
1050 unsigned long depth
;
1052 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1055 if (!save_trace(&this->trace
))
1058 depth
= get_lock_depth(target
);
1060 print_circular_bug_header(target
, depth
, check_src
, check_tgt
);
1062 parent
= get_lock_parent(target
);
1065 print_circular_bug_entry(parent
, --depth
);
1066 parent
= get_lock_parent(parent
);
1069 printk("\nother info that might help us debug this:\n\n");
1070 lockdep_print_held_locks(curr
);
1072 printk("\nstack backtrace:\n");
1078 static noinline
int print_bfs_bug(int ret
)
1080 if (!debug_locks_off_graph_unlock())
1083 WARN(1, "lockdep bfs error:%d\n", ret
);
1088 #define RECURSION_LIMIT 40
1090 static int noinline
print_infinite_recursion_bug(void)
1092 if (!debug_locks_off_graph_unlock())
1100 unsigned long __lockdep_count_forward_deps(struct lock_class
*class,
1103 struct lock_list
*entry
;
1104 unsigned long ret
= 1;
1106 if (lockdep_dependency_visit(class, depth
))
1110 * Recurse this class's dependency list:
1112 list_for_each_entry(entry
, &class->locks_after
, entry
)
1113 ret
+= __lockdep_count_forward_deps(entry
->class, depth
+ 1);
1118 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1120 unsigned long ret
, flags
;
1122 local_irq_save(flags
);
1123 __raw_spin_lock(&lockdep_lock
);
1124 ret
= __lockdep_count_forward_deps(class, 0);
1125 __raw_spin_unlock(&lockdep_lock
);
1126 local_irq_restore(flags
);
1131 unsigned long __lockdep_count_backward_deps(struct lock_class
*class,
1134 struct lock_list
*entry
;
1135 unsigned long ret
= 1;
1137 if (lockdep_dependency_visit(class, depth
))
1140 * Recurse this class's dependency list:
1142 list_for_each_entry(entry
, &class->locks_before
, entry
)
1143 ret
+= __lockdep_count_backward_deps(entry
->class, depth
+ 1);
1148 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1150 unsigned long ret
, flags
;
1152 local_irq_save(flags
);
1153 __raw_spin_lock(&lockdep_lock
);
1154 ret
= __lockdep_count_backward_deps(class, 0);
1155 __raw_spin_unlock(&lockdep_lock
);
1156 local_irq_restore(flags
);
1162 * Prove that the dependency graph starting at <entry> can not
1163 * lead to <target>. Print an error and return 0 if it does.
1166 check_noncircular(struct lock_list
*root
, struct lock_class
*target
,
1167 struct lock_list
**target_entry
)
1171 debug_atomic_inc(&nr_cyclic_checks
);
1173 result
= __bfs_forward(root
, target
, class_equal
, target_entry
);
1178 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1180 * Forwards and backwards subgraph searching, for the purposes of
1181 * proving that two subgraphs can be connected by a new dependency
1182 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1184 static enum lock_usage_bit find_usage_bit
;
1185 static struct lock_class
*forwards_match
, *backwards_match
;
1188 * Find a node in the forwards-direction dependency sub-graph starting
1189 * at <source> that matches <find_usage_bit>.
1191 * Return 2 if such a node exists in the subgraph, and put that node
1192 * into <forwards_match>.
1194 * Return 1 otherwise and keep <forwards_match> unchanged.
1195 * Return 0 on error.
1198 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
1200 struct lock_list
*entry
;
1203 if (lockdep_dependency_visit(source
, depth
))
1206 if (depth
> max_recursion_depth
)
1207 max_recursion_depth
= depth
;
1208 if (depth
>= RECURSION_LIMIT
)
1209 return print_infinite_recursion_bug();
1211 debug_atomic_inc(&nr_find_usage_forwards_checks
);
1212 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1213 forwards_match
= source
;
1218 * Check this lock's dependency list:
1220 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1221 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
1222 ret
= find_usage_forwards(entry
->class, depth
+1);
1223 if (ret
== 2 || ret
== 0)
1230 * Find a node in the backwards-direction dependency sub-graph starting
1231 * at <source> that matches <find_usage_bit>.
1233 * Return 2 if such a node exists in the subgraph, and put that node
1234 * into <backwards_match>.
1236 * Return 1 otherwise and keep <backwards_match> unchanged.
1237 * Return 0 on error.
1240 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
1242 struct lock_list
*entry
;
1245 if (lockdep_dependency_visit(source
, depth
))
1248 if (!__raw_spin_is_locked(&lockdep_lock
))
1249 return DEBUG_LOCKS_WARN_ON(1);
1251 if (depth
> max_recursion_depth
)
1252 max_recursion_depth
= depth
;
1253 if (depth
>= RECURSION_LIMIT
)
1254 return print_infinite_recursion_bug();
1256 debug_atomic_inc(&nr_find_usage_backwards_checks
);
1257 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1258 backwards_match
= source
;
1262 if (!source
&& debug_locks_off_graph_unlock()) {
1268 * Check this lock's dependency list:
1270 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
1271 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
1272 ret
= find_usage_backwards(entry
->class, depth
+1);
1273 if (ret
== 2 || ret
== 0)
1280 print_bad_irq_dependency(struct task_struct
*curr
,
1281 struct held_lock
*prev
,
1282 struct held_lock
*next
,
1283 enum lock_usage_bit bit1
,
1284 enum lock_usage_bit bit2
,
1285 const char *irqclass
)
1287 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1290 printk("\n======================================================\n");
1291 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1292 irqclass
, irqclass
);
1293 print_kernel_version();
1294 printk( "------------------------------------------------------\n");
1295 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1296 curr
->comm
, task_pid_nr(curr
),
1297 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1298 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1299 curr
->hardirqs_enabled
,
1300 curr
->softirqs_enabled
);
1303 printk("\nand this task is already holding:\n");
1305 printk("which would create a new lock dependency:\n");
1306 print_lock_name(hlock_class(prev
));
1308 print_lock_name(hlock_class(next
));
1311 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1313 print_lock_name(backwards_match
);
1314 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1316 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
1318 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1319 print_lock_name(forwards_match
);
1320 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1323 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
1325 printk("\nother info that might help us debug this:\n\n");
1326 lockdep_print_held_locks(curr
);
1328 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
1329 print_lock_dependencies(backwards_match
, 0);
1331 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
1332 print_lock_dependencies(forwards_match
, 0);
1334 printk("\nstack backtrace:\n");
1341 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1342 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1343 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1347 find_usage_bit
= bit_backwards
;
1348 /* fills in <backwards_match> */
1349 ret
= find_usage_backwards(hlock_class(prev
), 0);
1350 if (!ret
|| ret
== 1)
1353 find_usage_bit
= bit_forwards
;
1354 ret
= find_usage_forwards(hlock_class(next
), 0);
1355 if (!ret
|| ret
== 1)
1358 return print_bad_irq_dependency(curr
, prev
, next
,
1359 bit_backwards
, bit_forwards
, irqclass
);
1362 static const char *state_names
[] = {
1363 #define LOCKDEP_STATE(__STATE) \
1364 __stringify(__STATE),
1365 #include "lockdep_states.h"
1366 #undef LOCKDEP_STATE
1369 static const char *state_rnames
[] = {
1370 #define LOCKDEP_STATE(__STATE) \
1371 __stringify(__STATE)"-READ",
1372 #include "lockdep_states.h"
1373 #undef LOCKDEP_STATE
1376 static inline const char *state_name(enum lock_usage_bit bit
)
1378 return (bit
& 1) ? state_rnames
[bit
>> 2] : state_names
[bit
>> 2];
1381 static int exclusive_bit(int new_bit
)
1389 * bit 0 - write/read
1390 * bit 1 - used_in/enabled
1394 int state
= new_bit
& ~3;
1395 int dir
= new_bit
& 2;
1398 * keep state, bit flip the direction and strip read.
1400 return state
| (dir
^ 2);
1403 static int check_irq_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1404 struct held_lock
*next
, enum lock_usage_bit bit
)
1407 * Prove that the new dependency does not connect a hardirq-safe
1408 * lock with a hardirq-unsafe lock - to achieve this we search
1409 * the backwards-subgraph starting at <prev>, and the
1410 * forwards-subgraph starting at <next>:
1412 if (!check_usage(curr
, prev
, next
, bit
,
1413 exclusive_bit(bit
), state_name(bit
)))
1419 * Prove that the new dependency does not connect a hardirq-safe-read
1420 * lock with a hardirq-unsafe lock - to achieve this we search
1421 * the backwards-subgraph starting at <prev>, and the
1422 * forwards-subgraph starting at <next>:
1424 if (!check_usage(curr
, prev
, next
, bit
,
1425 exclusive_bit(bit
), state_name(bit
)))
1432 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1433 struct held_lock
*next
)
1435 #define LOCKDEP_STATE(__STATE) \
1436 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1438 #include "lockdep_states.h"
1439 #undef LOCKDEP_STATE
1444 static void inc_chains(void)
1446 if (current
->hardirq_context
)
1447 nr_hardirq_chains
++;
1449 if (current
->softirq_context
)
1450 nr_softirq_chains
++;
1452 nr_process_chains
++;
1459 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1460 struct held_lock
*next
)
1465 static inline void inc_chains(void)
1467 nr_process_chains
++;
1473 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1474 struct held_lock
*next
)
1476 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1479 printk("\n=============================================\n");
1480 printk( "[ INFO: possible recursive locking detected ]\n");
1481 print_kernel_version();
1482 printk( "---------------------------------------------\n");
1483 printk("%s/%d is trying to acquire lock:\n",
1484 curr
->comm
, task_pid_nr(curr
));
1486 printk("\nbut task is already holding lock:\n");
1489 printk("\nother info that might help us debug this:\n");
1490 lockdep_print_held_locks(curr
);
1492 printk("\nstack backtrace:\n");
1499 * Check whether we are holding such a class already.
1501 * (Note that this has to be done separately, because the graph cannot
1502 * detect such classes of deadlocks.)
1504 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1507 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1508 struct lockdep_map
*next_instance
, int read
)
1510 struct held_lock
*prev
;
1511 struct held_lock
*nest
= NULL
;
1514 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1515 prev
= curr
->held_locks
+ i
;
1517 if (prev
->instance
== next
->nest_lock
)
1520 if (hlock_class(prev
) != hlock_class(next
))
1524 * Allow read-after-read recursion of the same
1525 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1527 if ((read
== 2) && prev
->read
)
1531 * We're holding the nest_lock, which serializes this lock's
1532 * nesting behaviour.
1537 return print_deadlock_bug(curr
, prev
, next
);
1543 * There was a chain-cache miss, and we are about to add a new dependency
1544 * to a previous lock. We recursively validate the following rules:
1546 * - would the adding of the <prev> -> <next> dependency create a
1547 * circular dependency in the graph? [== circular deadlock]
1549 * - does the new prev->next dependency connect any hardirq-safe lock
1550 * (in the full backwards-subgraph starting at <prev>) with any
1551 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1552 * <next>)? [== illegal lock inversion with hardirq contexts]
1554 * - does the new prev->next dependency connect any softirq-safe lock
1555 * (in the full backwards-subgraph starting at <prev>) with any
1556 * softirq-unsafe lock (in the full forwards-subgraph starting at
1557 * <next>)? [== illegal lock inversion with softirq contexts]
1559 * any of these scenarios could lead to a deadlock.
1561 * Then if all the validations pass, we add the forwards and backwards
1565 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1566 struct held_lock
*next
, int distance
)
1568 struct lock_list
*entry
;
1570 struct lock_list
this;
1571 struct lock_list
*uninitialized_var(target_entry
);
1574 * Prove that the new <prev> -> <next> dependency would not
1575 * create a circular dependency in the graph. (We do this by
1576 * forward-recursing into the graph starting at <next>, and
1577 * checking whether we can reach <prev>.)
1579 * We are using global variables to control the recursion, to
1580 * keep the stackframe size of the recursive functions low:
1582 this.class = hlock_class(next
);
1584 ret
= check_noncircular(&this, hlock_class(prev
), &target_entry
);
1586 return print_circular_bug(&this, target_entry
, next
, prev
);
1587 else if (unlikely(ret
< 0))
1588 return print_bfs_bug(ret
);
1590 if (!check_prev_add_irq(curr
, prev
, next
))
1594 * For recursive read-locks we do all the dependency checks,
1595 * but we dont store read-triggered dependencies (only
1596 * write-triggered dependencies). This ensures that only the
1597 * write-side dependencies matter, and that if for example a
1598 * write-lock never takes any other locks, then the reads are
1599 * equivalent to a NOP.
1601 if (next
->read
== 2 || prev
->read
== 2)
1604 * Is the <prev> -> <next> dependency already present?
1606 * (this may occur even though this is a new chain: consider
1607 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1608 * chains - the second one will be new, but L1 already has
1609 * L2 added to its dependency list, due to the first chain.)
1611 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1612 if (entry
->class == hlock_class(next
)) {
1614 entry
->distance
= 1;
1620 * Ok, all validations passed, add the new lock
1621 * to the previous lock's dependency list:
1623 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1624 &hlock_class(prev
)->locks_after
,
1625 next
->acquire_ip
, distance
);
1630 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1631 &hlock_class(next
)->locks_before
,
1632 next
->acquire_ip
, distance
);
1637 * Debugging printouts:
1639 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1641 printk("\n new dependency: ");
1642 print_lock_name(hlock_class(prev
));
1644 print_lock_name(hlock_class(next
));
1647 return graph_lock();
1653 * Add the dependency to all directly-previous locks that are 'relevant'.
1654 * The ones that are relevant are (in increasing distance from curr):
1655 * all consecutive trylock entries and the final non-trylock entry - or
1656 * the end of this context's lock-chain - whichever comes first.
1659 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1661 int depth
= curr
->lockdep_depth
;
1662 struct held_lock
*hlock
;
1667 * Depth must not be zero for a non-head lock:
1672 * At least two relevant locks must exist for this
1675 if (curr
->held_locks
[depth
].irq_context
!=
1676 curr
->held_locks
[depth
-1].irq_context
)
1680 int distance
= curr
->lockdep_depth
- depth
+ 1;
1681 hlock
= curr
->held_locks
+ depth
-1;
1683 * Only non-recursive-read entries get new dependencies
1686 if (hlock
->read
!= 2) {
1687 if (!check_prev_add(curr
, hlock
, next
, distance
))
1690 * Stop after the first non-trylock entry,
1691 * as non-trylock entries have added their
1692 * own direct dependencies already, so this
1693 * lock is connected to them indirectly:
1695 if (!hlock
->trylock
)
1700 * End of lock-stack?
1705 * Stop the search if we cross into another context:
1707 if (curr
->held_locks
[depth
].irq_context
!=
1708 curr
->held_locks
[depth
-1].irq_context
)
1713 if (!debug_locks_off_graph_unlock())
1721 unsigned long nr_lock_chains
;
1722 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1723 int nr_chain_hlocks
;
1724 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1726 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1728 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1732 * Look up a dependency chain. If the key is not present yet then
1733 * add it and return 1 - in this case the new dependency chain is
1734 * validated. If the key is already hashed, return 0.
1735 * (On return with 1 graph_lock is held.)
1737 static inline int lookup_chain_cache(struct task_struct
*curr
,
1738 struct held_lock
*hlock
,
1741 struct lock_class
*class = hlock_class(hlock
);
1742 struct list_head
*hash_head
= chainhashentry(chain_key
);
1743 struct lock_chain
*chain
;
1744 struct held_lock
*hlock_curr
, *hlock_next
;
1747 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1750 * We can walk it lock-free, because entries only get added
1753 list_for_each_entry(chain
, hash_head
, entry
) {
1754 if (chain
->chain_key
== chain_key
) {
1756 debug_atomic_inc(&chain_lookup_hits
);
1757 if (very_verbose(class))
1758 printk("\nhash chain already cached, key: "
1759 "%016Lx tail class: [%p] %s\n",
1760 (unsigned long long)chain_key
,
1761 class->key
, class->name
);
1765 if (very_verbose(class))
1766 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1767 (unsigned long long)chain_key
, class->key
, class->name
);
1769 * Allocate a new chain entry from the static array, and add
1775 * We have to walk the chain again locked - to avoid duplicates:
1777 list_for_each_entry(chain
, hash_head
, entry
) {
1778 if (chain
->chain_key
== chain_key
) {
1783 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1784 if (!debug_locks_off_graph_unlock())
1787 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1788 printk("turning off the locking correctness validator.\n");
1792 chain
= lock_chains
+ nr_lock_chains
++;
1793 chain
->chain_key
= chain_key
;
1794 chain
->irq_context
= hlock
->irq_context
;
1795 /* Find the first held_lock of current chain */
1797 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
1798 hlock_curr
= curr
->held_locks
+ i
;
1799 if (hlock_curr
->irq_context
!= hlock_next
->irq_context
)
1804 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
1805 cn
= nr_chain_hlocks
;
1806 while (cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
) {
1807 n
= cmpxchg(&nr_chain_hlocks
, cn
, cn
+ chain
->depth
);
1812 if (likely(cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
1814 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
1815 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
1816 chain_hlocks
[chain
->base
+ j
] = lock_id
;
1818 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
1820 list_add_tail_rcu(&chain
->entry
, hash_head
);
1821 debug_atomic_inc(&chain_lookup_misses
);
1827 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
1828 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
1831 * Trylock needs to maintain the stack of held locks, but it
1832 * does not add new dependencies, because trylock can be done
1835 * We look up the chain_key and do the O(N^2) check and update of
1836 * the dependencies only if this is a new dependency chain.
1837 * (If lookup_chain_cache() returns with 1 it acquires
1838 * graph_lock for us)
1840 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
1841 lookup_chain_cache(curr
, hlock
, chain_key
)) {
1843 * Check whether last held lock:
1845 * - is irq-safe, if this lock is irq-unsafe
1846 * - is softirq-safe, if this lock is hardirq-unsafe
1848 * And check whether the new lock's dependency graph
1849 * could lead back to the previous lock.
1851 * any of these scenarios could lead to a deadlock. If
1854 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
1859 * Mark recursive read, as we jump over it when
1860 * building dependencies (just like we jump over
1866 * Add dependency only if this lock is not the head
1867 * of the chain, and if it's not a secondary read-lock:
1869 if (!chain_head
&& ret
!= 2)
1870 if (!check_prevs_add(curr
, hlock
))
1874 /* after lookup_chain_cache(): */
1875 if (unlikely(!debug_locks
))
1881 static inline int validate_chain(struct task_struct
*curr
,
1882 struct lockdep_map
*lock
, struct held_lock
*hlock
,
1883 int chain_head
, u64 chain_key
)
1890 * We are building curr_chain_key incrementally, so double-check
1891 * it from scratch, to make sure that it's done correctly:
1893 static void check_chain_key(struct task_struct
*curr
)
1895 #ifdef CONFIG_DEBUG_LOCKDEP
1896 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1900 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1901 hlock
= curr
->held_locks
+ i
;
1902 if (chain_key
!= hlock
->prev_chain_key
) {
1904 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1905 curr
->lockdep_depth
, i
,
1906 (unsigned long long)chain_key
,
1907 (unsigned long long)hlock
->prev_chain_key
);
1910 id
= hlock
->class_idx
- 1;
1911 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
1914 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1915 hlock
->irq_context
))
1917 chain_key
= iterate_chain_key(chain_key
, id
);
1920 if (chain_key
!= curr
->curr_chain_key
) {
1922 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1923 curr
->lockdep_depth
, i
,
1924 (unsigned long long)chain_key
,
1925 (unsigned long long)curr
->curr_chain_key
);
1931 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1932 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1934 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1937 printk("\n=================================\n");
1938 printk( "[ INFO: inconsistent lock state ]\n");
1939 print_kernel_version();
1940 printk( "---------------------------------\n");
1942 printk("inconsistent {%s} -> {%s} usage.\n",
1943 usage_str
[prev_bit
], usage_str
[new_bit
]);
1945 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1946 curr
->comm
, task_pid_nr(curr
),
1947 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1948 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1949 trace_hardirqs_enabled(curr
),
1950 trace_softirqs_enabled(curr
));
1953 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1954 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
1956 print_irqtrace_events(curr
);
1957 printk("\nother info that might help us debug this:\n");
1958 lockdep_print_held_locks(curr
);
1960 printk("\nstack backtrace:\n");
1967 * Print out an error if an invalid bit is set:
1970 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1971 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1973 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
1974 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1978 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1979 enum lock_usage_bit new_bit
);
1981 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1984 * print irq inversion bug:
1987 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*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
);
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 first lock's dependencies:\n");
2012 print_lock_dependencies(hlock_class(this), 0);
2014 printk("\nthe second lock's dependencies:\n");
2015 print_lock_dependencies(other
, 0);
2017 printk("\nstack backtrace:\n");
2024 * Prove that in the forwards-direction subgraph starting at <this>
2025 * there is no lock matching <mask>:
2028 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
2029 enum lock_usage_bit bit
, const char *irqclass
)
2033 find_usage_bit
= bit
;
2034 /* fills in <forwards_match> */
2035 ret
= find_usage_forwards(hlock_class(this), 0);
2036 if (!ret
|| ret
== 1)
2039 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
2043 * Prove that in the backwards-direction subgraph starting at <this>
2044 * there is no lock matching <mask>:
2047 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
2048 enum lock_usage_bit bit
, const char *irqclass
)
2052 find_usage_bit
= bit
;
2053 /* fills in <backwards_match> */
2054 ret
= find_usage_backwards(hlock_class(this), 0);
2055 if (!ret
|| ret
== 1)
2058 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
2061 void print_irqtrace_events(struct task_struct
*curr
)
2063 printk("irq event stamp: %u\n", curr
->irq_events
);
2064 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
2065 print_ip_sym(curr
->hardirq_enable_ip
);
2066 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
2067 print_ip_sym(curr
->hardirq_disable_ip
);
2068 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
2069 print_ip_sym(curr
->softirq_enable_ip
);
2070 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
2071 print_ip_sym(curr
->softirq_disable_ip
);
2074 static int HARDIRQ_verbose(struct lock_class
*class)
2077 return class_filter(class);
2082 static int SOFTIRQ_verbose(struct lock_class
*class)
2085 return class_filter(class);
2090 static int RECLAIM_FS_verbose(struct lock_class
*class)
2093 return class_filter(class);
2098 #define STRICT_READ_CHECKS 1
2100 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2101 #define LOCKDEP_STATE(__STATE) \
2103 #include "lockdep_states.h"
2104 #undef LOCKDEP_STATE
2107 static inline int state_verbose(enum lock_usage_bit bit
,
2108 struct lock_class
*class)
2110 return state_verbose_f
[bit
>> 2](class);
2113 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2114 enum lock_usage_bit bit
, const char *name
);
2117 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2118 enum lock_usage_bit new_bit
)
2120 int excl_bit
= exclusive_bit(new_bit
);
2121 int read
= new_bit
& 1;
2122 int dir
= new_bit
& 2;
2125 * mark USED_IN has to look forwards -- to ensure no dependency
2126 * has ENABLED state, which would allow recursion deadlocks.
2128 * mark ENABLED has to look backwards -- to ensure no dependee
2129 * has USED_IN state, which, again, would allow recursion deadlocks.
2131 check_usage_f usage
= dir
?
2132 check_usage_backwards
: check_usage_forwards
;
2135 * Validate that this particular lock does not have conflicting
2138 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2142 * Validate that the lock dependencies don't have conflicting usage
2145 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2146 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2150 * Check for read in write conflicts
2153 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2156 if (STRICT_READ_CHECKS
&&
2157 !usage(curr
, this, excl_bit
+ 1,
2158 state_name(new_bit
+ 1)))
2162 if (state_verbose(new_bit
, hlock_class(this)))
2169 #define LOCKDEP_STATE(__STATE) __STATE,
2170 #include "lockdep_states.h"
2171 #undef LOCKDEP_STATE
2175 * Mark all held locks with a usage bit:
2178 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2180 enum lock_usage_bit usage_bit
;
2181 struct held_lock
*hlock
;
2184 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2185 hlock
= curr
->held_locks
+ i
;
2187 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2189 usage_bit
+= 1; /* READ */
2191 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2193 if (!mark_lock(curr
, hlock
, usage_bit
))
2201 * Debugging helper: via this flag we know that we are in
2202 * 'early bootup code', and will warn about any invalid irqs-on event:
2204 static int early_boot_irqs_enabled
;
2206 void early_boot_irqs_off(void)
2208 early_boot_irqs_enabled
= 0;
2211 void early_boot_irqs_on(void)
2213 early_boot_irqs_enabled
= 1;
2217 * Hardirqs will be enabled:
2219 void trace_hardirqs_on_caller(unsigned long ip
)
2221 struct task_struct
*curr
= current
;
2223 time_hardirqs_on(CALLER_ADDR0
, ip
);
2225 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2228 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
2231 if (unlikely(curr
->hardirqs_enabled
)) {
2232 debug_atomic_inc(&redundant_hardirqs_on
);
2235 /* we'll do an OFF -> ON transition: */
2236 curr
->hardirqs_enabled
= 1;
2238 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2240 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2243 * We are going to turn hardirqs on, so set the
2244 * usage bit for all held locks:
2246 if (!mark_held_locks(curr
, HARDIRQ
))
2249 * If we have softirqs enabled, then set the usage
2250 * bit for all held locks. (disabled hardirqs prevented
2251 * this bit from being set before)
2253 if (curr
->softirqs_enabled
)
2254 if (!mark_held_locks(curr
, SOFTIRQ
))
2257 curr
->hardirq_enable_ip
= ip
;
2258 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2259 debug_atomic_inc(&hardirqs_on_events
);
2261 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2263 void trace_hardirqs_on(void)
2265 trace_hardirqs_on_caller(CALLER_ADDR0
);
2267 EXPORT_SYMBOL(trace_hardirqs_on
);
2270 * Hardirqs were disabled:
2272 void trace_hardirqs_off_caller(unsigned long ip
)
2274 struct task_struct
*curr
= current
;
2276 time_hardirqs_off(CALLER_ADDR0
, ip
);
2278 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2281 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2284 if (curr
->hardirqs_enabled
) {
2286 * We have done an ON -> OFF transition:
2288 curr
->hardirqs_enabled
= 0;
2289 curr
->hardirq_disable_ip
= ip
;
2290 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2291 debug_atomic_inc(&hardirqs_off_events
);
2293 debug_atomic_inc(&redundant_hardirqs_off
);
2295 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2297 void trace_hardirqs_off(void)
2299 trace_hardirqs_off_caller(CALLER_ADDR0
);
2301 EXPORT_SYMBOL(trace_hardirqs_off
);
2304 * Softirqs will be enabled:
2306 void trace_softirqs_on(unsigned long ip
)
2308 struct task_struct
*curr
= current
;
2310 if (unlikely(!debug_locks
))
2313 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2316 if (curr
->softirqs_enabled
) {
2317 debug_atomic_inc(&redundant_softirqs_on
);
2322 * We'll do an OFF -> ON transition:
2324 curr
->softirqs_enabled
= 1;
2325 curr
->softirq_enable_ip
= ip
;
2326 curr
->softirq_enable_event
= ++curr
->irq_events
;
2327 debug_atomic_inc(&softirqs_on_events
);
2329 * We are going to turn softirqs on, so set the
2330 * usage bit for all held locks, if hardirqs are
2333 if (curr
->hardirqs_enabled
)
2334 mark_held_locks(curr
, SOFTIRQ
);
2338 * Softirqs were disabled:
2340 void trace_softirqs_off(unsigned long ip
)
2342 struct task_struct
*curr
= current
;
2344 if (unlikely(!debug_locks
))
2347 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2350 if (curr
->softirqs_enabled
) {
2352 * We have done an ON -> OFF transition:
2354 curr
->softirqs_enabled
= 0;
2355 curr
->softirq_disable_ip
= ip
;
2356 curr
->softirq_disable_event
= ++curr
->irq_events
;
2357 debug_atomic_inc(&softirqs_off_events
);
2358 DEBUG_LOCKS_WARN_ON(!softirq_count());
2360 debug_atomic_inc(&redundant_softirqs_off
);
2363 static void __lockdep_trace_alloc(gfp_t gfp_mask
, unsigned long flags
)
2365 struct task_struct
*curr
= current
;
2367 if (unlikely(!debug_locks
))
2370 /* no reclaim without waiting on it */
2371 if (!(gfp_mask
& __GFP_WAIT
))
2374 /* this guy won't enter reclaim */
2375 if ((curr
->flags
& PF_MEMALLOC
) && !(gfp_mask
& __GFP_NOMEMALLOC
))
2378 /* We're only interested __GFP_FS allocations for now */
2379 if (!(gfp_mask
& __GFP_FS
))
2382 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags
)))
2385 mark_held_locks(curr
, RECLAIM_FS
);
2388 static void check_flags(unsigned long flags
);
2390 void lockdep_trace_alloc(gfp_t gfp_mask
)
2392 unsigned long flags
;
2394 if (unlikely(current
->lockdep_recursion
))
2397 raw_local_irq_save(flags
);
2399 current
->lockdep_recursion
= 1;
2400 __lockdep_trace_alloc(gfp_mask
, flags
);
2401 current
->lockdep_recursion
= 0;
2402 raw_local_irq_restore(flags
);
2405 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2408 * If non-trylock use in a hardirq or softirq context, then
2409 * mark the lock as used in these contexts:
2411 if (!hlock
->trylock
) {
2413 if (curr
->hardirq_context
)
2414 if (!mark_lock(curr
, hlock
,
2415 LOCK_USED_IN_HARDIRQ_READ
))
2417 if (curr
->softirq_context
)
2418 if (!mark_lock(curr
, hlock
,
2419 LOCK_USED_IN_SOFTIRQ_READ
))
2422 if (curr
->hardirq_context
)
2423 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2425 if (curr
->softirq_context
)
2426 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2430 if (!hlock
->hardirqs_off
) {
2432 if (!mark_lock(curr
, hlock
,
2433 LOCK_ENABLED_HARDIRQ_READ
))
2435 if (curr
->softirqs_enabled
)
2436 if (!mark_lock(curr
, hlock
,
2437 LOCK_ENABLED_SOFTIRQ_READ
))
2440 if (!mark_lock(curr
, hlock
,
2441 LOCK_ENABLED_HARDIRQ
))
2443 if (curr
->softirqs_enabled
)
2444 if (!mark_lock(curr
, hlock
,
2445 LOCK_ENABLED_SOFTIRQ
))
2451 * We reuse the irq context infrastructure more broadly as a general
2452 * context checking code. This tests GFP_FS recursion (a lock taken
2453 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2456 if (!hlock
->trylock
&& (curr
->lockdep_reclaim_gfp
& __GFP_FS
)) {
2458 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS_READ
))
2461 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS
))
2469 static int separate_irq_context(struct task_struct
*curr
,
2470 struct held_lock
*hlock
)
2472 unsigned int depth
= curr
->lockdep_depth
;
2475 * Keep track of points where we cross into an interrupt context:
2477 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2478 curr
->softirq_context
;
2480 struct held_lock
*prev_hlock
;
2482 prev_hlock
= curr
->held_locks
+ depth
-1;
2484 * If we cross into another context, reset the
2485 * hash key (this also prevents the checking and the
2486 * adding of the dependency to 'prev'):
2488 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2497 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2498 enum lock_usage_bit new_bit
)
2504 static inline int mark_irqflags(struct task_struct
*curr
,
2505 struct held_lock
*hlock
)
2510 static inline int separate_irq_context(struct task_struct
*curr
,
2511 struct held_lock
*hlock
)
2516 void lockdep_trace_alloc(gfp_t gfp_mask
)
2523 * Mark a lock with a usage bit, and validate the state transition:
2525 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2526 enum lock_usage_bit new_bit
)
2528 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2531 * If already set then do not dirty the cacheline,
2532 * nor do any checks:
2534 if (likely(hlock_class(this)->usage_mask
& new_mask
))
2540 * Make sure we didnt race:
2542 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
2547 hlock_class(this)->usage_mask
|= new_mask
;
2549 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
2553 #define LOCKDEP_STATE(__STATE) \
2554 case LOCK_USED_IN_##__STATE: \
2555 case LOCK_USED_IN_##__STATE##_READ: \
2556 case LOCK_ENABLED_##__STATE: \
2557 case LOCK_ENABLED_##__STATE##_READ:
2558 #include "lockdep_states.h"
2559 #undef LOCKDEP_STATE
2560 ret
= mark_lock_irq(curr
, this, new_bit
);
2565 debug_atomic_dec(&nr_unused_locks
);
2568 if (!debug_locks_off_graph_unlock())
2577 * We must printk outside of the graph_lock:
2580 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2582 print_irqtrace_events(curr
);
2590 * Initialize a lock instance's lock-class mapping info:
2592 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2593 struct lock_class_key
*key
, int subclass
)
2595 lock
->class_cache
= NULL
;
2596 #ifdef CONFIG_LOCK_STAT
2597 lock
->cpu
= raw_smp_processor_id();
2600 if (DEBUG_LOCKS_WARN_ON(!name
)) {
2601 lock
->name
= "NULL";
2607 if (DEBUG_LOCKS_WARN_ON(!key
))
2610 * Sanity check, the lock-class key must be persistent:
2612 if (!static_obj(key
)) {
2613 printk("BUG: key %p not in .data!\n", key
);
2614 DEBUG_LOCKS_WARN_ON(1);
2619 if (unlikely(!debug_locks
))
2623 register_lock_class(lock
, subclass
, 1);
2625 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2628 * This gets called for every mutex_lock*()/spin_lock*() operation.
2629 * We maintain the dependency maps and validate the locking attempt:
2631 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2632 int trylock
, int read
, int check
, int hardirqs_off
,
2633 struct lockdep_map
*nest_lock
, unsigned long ip
)
2635 struct task_struct
*curr
= current
;
2636 struct lock_class
*class = NULL
;
2637 struct held_lock
*hlock
;
2638 unsigned int depth
, id
;
2645 if (unlikely(!debug_locks
))
2648 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2651 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
2653 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2654 printk("turning off the locking correctness validator.\n");
2660 class = lock
->class_cache
;
2662 * Not cached yet or subclass?
2664 if (unlikely(!class)) {
2665 class = register_lock_class(lock
, subclass
, 0);
2669 debug_atomic_inc((atomic_t
*)&class->ops
);
2670 if (very_verbose(class)) {
2671 printk("\nacquire class [%p] %s", class->key
, class->name
);
2672 if (class->name_version
> 1)
2673 printk("#%d", class->name_version
);
2679 * Add the lock to the list of currently held locks.
2680 * (we dont increase the depth just yet, up until the
2681 * dependency checks are done)
2683 depth
= curr
->lockdep_depth
;
2684 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2687 hlock
= curr
->held_locks
+ depth
;
2688 if (DEBUG_LOCKS_WARN_ON(!class))
2690 hlock
->class_idx
= class - lock_classes
+ 1;
2691 hlock
->acquire_ip
= ip
;
2692 hlock
->instance
= lock
;
2693 hlock
->nest_lock
= nest_lock
;
2694 hlock
->trylock
= trylock
;
2696 hlock
->check
= check
;
2697 hlock
->hardirqs_off
= !!hardirqs_off
;
2698 #ifdef CONFIG_LOCK_STAT
2699 hlock
->waittime_stamp
= 0;
2700 hlock
->holdtime_stamp
= sched_clock();
2703 if (check
== 2 && !mark_irqflags(curr
, hlock
))
2706 /* mark it as used: */
2707 if (!mark_lock(curr
, hlock
, LOCK_USED
))
2711 * Calculate the chain hash: it's the combined hash of all the
2712 * lock keys along the dependency chain. We save the hash value
2713 * at every step so that we can get the current hash easily
2714 * after unlock. The chain hash is then used to cache dependency
2717 * The 'key ID' is what is the most compact key value to drive
2718 * the hash, not class->key.
2720 id
= class - lock_classes
;
2721 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2724 chain_key
= curr
->curr_chain_key
;
2726 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2731 hlock
->prev_chain_key
= chain_key
;
2732 if (separate_irq_context(curr
, hlock
)) {
2736 chain_key
= iterate_chain_key(chain_key
, id
);
2738 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
2741 curr
->curr_chain_key
= chain_key
;
2742 curr
->lockdep_depth
++;
2743 check_chain_key(curr
);
2744 #ifdef CONFIG_DEBUG_LOCKDEP
2745 if (unlikely(!debug_locks
))
2748 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2750 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2751 printk("turning off the locking correctness validator.\n");
2756 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2757 max_lockdep_depth
= curr
->lockdep_depth
;
2763 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2766 if (!debug_locks_off())
2768 if (debug_locks_silent
)
2771 printk("\n=====================================\n");
2772 printk( "[ BUG: bad unlock balance detected! ]\n");
2773 printk( "-------------------------------------\n");
2774 printk("%s/%d is trying to release lock (",
2775 curr
->comm
, task_pid_nr(curr
));
2776 print_lockdep_cache(lock
);
2779 printk("but there are no more locks to release!\n");
2780 printk("\nother info that might help us debug this:\n");
2781 lockdep_print_held_locks(curr
);
2783 printk("\nstack backtrace:\n");
2790 * Common debugging checks for both nested and non-nested unlock:
2792 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2795 if (unlikely(!debug_locks
))
2797 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2800 if (curr
->lockdep_depth
<= 0)
2801 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2807 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
2808 struct lock_class_key
*key
, unsigned int subclass
,
2811 struct task_struct
*curr
= current
;
2812 struct held_lock
*hlock
, *prev_hlock
;
2813 struct lock_class
*class;
2817 depth
= curr
->lockdep_depth
;
2818 if (DEBUG_LOCKS_WARN_ON(!depth
))
2822 for (i
= depth
-1; i
>= 0; i
--) {
2823 hlock
= curr
->held_locks
+ i
;
2825 * We must not cross into another context:
2827 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2829 if (hlock
->instance
== lock
)
2833 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2836 lockdep_init_map(lock
, name
, key
, 0);
2837 class = register_lock_class(lock
, subclass
, 0);
2838 hlock
->class_idx
= class - lock_classes
+ 1;
2840 curr
->lockdep_depth
= i
;
2841 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2843 for (; i
< depth
; i
++) {
2844 hlock
= curr
->held_locks
+ i
;
2845 if (!__lock_acquire(hlock
->instance
,
2846 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2847 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2848 hlock
->nest_lock
, hlock
->acquire_ip
))
2852 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
2858 * Remove the lock to the list of currently held locks in a
2859 * potentially non-nested (out of order) manner. This is a
2860 * relatively rare operation, as all the unlock APIs default
2861 * to nested mode (which uses lock_release()):
2864 lock_release_non_nested(struct task_struct
*curr
,
2865 struct lockdep_map
*lock
, unsigned long ip
)
2867 struct held_lock
*hlock
, *prev_hlock
;
2872 * Check whether the lock exists in the current stack
2875 depth
= curr
->lockdep_depth
;
2876 if (DEBUG_LOCKS_WARN_ON(!depth
))
2880 for (i
= depth
-1; i
>= 0; i
--) {
2881 hlock
= curr
->held_locks
+ i
;
2883 * We must not cross into another context:
2885 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2887 if (hlock
->instance
== lock
)
2891 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2894 lock_release_holdtime(hlock
);
2897 * We have the right lock to unlock, 'hlock' points to it.
2898 * Now we remove it from the stack, and add back the other
2899 * entries (if any), recalculating the hash along the way:
2901 curr
->lockdep_depth
= i
;
2902 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2904 for (i
++; i
< depth
; i
++) {
2905 hlock
= curr
->held_locks
+ i
;
2906 if (!__lock_acquire(hlock
->instance
,
2907 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2908 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2909 hlock
->nest_lock
, hlock
->acquire_ip
))
2913 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2919 * Remove the lock to the list of currently held locks - this gets
2920 * called on mutex_unlock()/spin_unlock*() (or on a failed
2921 * mutex_lock_interruptible()). This is done for unlocks that nest
2922 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2924 static int lock_release_nested(struct task_struct
*curr
,
2925 struct lockdep_map
*lock
, unsigned long ip
)
2927 struct held_lock
*hlock
;
2931 * Pop off the top of the lock stack:
2933 depth
= curr
->lockdep_depth
- 1;
2934 hlock
= curr
->held_locks
+ depth
;
2937 * Is the unlock non-nested:
2939 if (hlock
->instance
!= lock
)
2940 return lock_release_non_nested(curr
, lock
, ip
);
2941 curr
->lockdep_depth
--;
2943 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2946 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2948 lock_release_holdtime(hlock
);
2950 #ifdef CONFIG_DEBUG_LOCKDEP
2951 hlock
->prev_chain_key
= 0;
2952 hlock
->class_idx
= 0;
2953 hlock
->acquire_ip
= 0;
2954 hlock
->irq_context
= 0;
2960 * Remove the lock to the list of currently held locks - this gets
2961 * called on mutex_unlock()/spin_unlock*() (or on a failed
2962 * mutex_lock_interruptible()). This is done for unlocks that nest
2963 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2966 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2968 struct task_struct
*curr
= current
;
2970 if (!check_unlock(curr
, lock
, ip
))
2974 if (!lock_release_nested(curr
, lock
, ip
))
2977 if (!lock_release_non_nested(curr
, lock
, ip
))
2981 check_chain_key(curr
);
2985 * Check whether we follow the irq-flags state precisely:
2987 static void check_flags(unsigned long flags
)
2989 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2990 defined(CONFIG_TRACE_IRQFLAGS)
2994 if (irqs_disabled_flags(flags
)) {
2995 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
2996 printk("possible reason: unannotated irqs-off.\n");
2999 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
3000 printk("possible reason: unannotated irqs-on.\n");
3005 * We dont accurately track softirq state in e.g.
3006 * hardirq contexts (such as on 4KSTACKS), so only
3007 * check if not in hardirq contexts:
3009 if (!hardirq_count()) {
3010 if (softirq_count())
3011 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
3013 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
3017 print_irqtrace_events(current
);
3021 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
3022 struct lock_class_key
*key
, unsigned int subclass
,
3025 unsigned long flags
;
3027 if (unlikely(current
->lockdep_recursion
))
3030 raw_local_irq_save(flags
);
3031 current
->lockdep_recursion
= 1;
3033 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
3034 check_chain_key(current
);
3035 current
->lockdep_recursion
= 0;
3036 raw_local_irq_restore(flags
);
3038 EXPORT_SYMBOL_GPL(lock_set_class
);
3041 * We are not always called with irqs disabled - do that here,
3042 * and also avoid lockdep recursion:
3044 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3045 int trylock
, int read
, int check
,
3046 struct lockdep_map
*nest_lock
, unsigned long ip
)
3048 unsigned long flags
;
3050 trace_lock_acquire(lock
, subclass
, trylock
, read
, check
, nest_lock
, ip
);
3052 if (unlikely(current
->lockdep_recursion
))
3055 raw_local_irq_save(flags
);
3058 current
->lockdep_recursion
= 1;
3059 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
3060 irqs_disabled_flags(flags
), nest_lock
, ip
);
3061 current
->lockdep_recursion
= 0;
3062 raw_local_irq_restore(flags
);
3064 EXPORT_SYMBOL_GPL(lock_acquire
);
3066 void lock_release(struct lockdep_map
*lock
, int nested
,
3069 unsigned long flags
;
3071 trace_lock_release(lock
, nested
, ip
);
3073 if (unlikely(current
->lockdep_recursion
))
3076 raw_local_irq_save(flags
);
3078 current
->lockdep_recursion
= 1;
3079 __lock_release(lock
, nested
, ip
);
3080 current
->lockdep_recursion
= 0;
3081 raw_local_irq_restore(flags
);
3083 EXPORT_SYMBOL_GPL(lock_release
);
3085 void lockdep_set_current_reclaim_state(gfp_t gfp_mask
)
3087 current
->lockdep_reclaim_gfp
= gfp_mask
;
3090 void lockdep_clear_current_reclaim_state(void)
3092 current
->lockdep_reclaim_gfp
= 0;
3095 #ifdef CONFIG_LOCK_STAT
3097 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3100 if (!debug_locks_off())
3102 if (debug_locks_silent
)
3105 printk("\n=================================\n");
3106 printk( "[ BUG: bad contention detected! ]\n");
3107 printk( "---------------------------------\n");
3108 printk("%s/%d is trying to contend lock (",
3109 curr
->comm
, task_pid_nr(curr
));
3110 print_lockdep_cache(lock
);
3113 printk("but there are no locks held!\n");
3114 printk("\nother info that might help us debug this:\n");
3115 lockdep_print_held_locks(curr
);
3117 printk("\nstack backtrace:\n");
3124 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3126 struct task_struct
*curr
= current
;
3127 struct held_lock
*hlock
, *prev_hlock
;
3128 struct lock_class_stats
*stats
;
3130 int i
, contention_point
, contending_point
;
3132 depth
= curr
->lockdep_depth
;
3133 if (DEBUG_LOCKS_WARN_ON(!depth
))
3137 for (i
= depth
-1; i
>= 0; i
--) {
3138 hlock
= curr
->held_locks
+ i
;
3140 * We must not cross into another context:
3142 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3144 if (hlock
->instance
== lock
)
3148 print_lock_contention_bug(curr
, lock
, ip
);
3152 hlock
->waittime_stamp
= sched_clock();
3154 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3155 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3158 stats
= get_lock_stats(hlock_class(hlock
));
3159 if (contention_point
< LOCKSTAT_POINTS
)
3160 stats
->contention_point
[contention_point
]++;
3161 if (contending_point
< LOCKSTAT_POINTS
)
3162 stats
->contending_point
[contending_point
]++;
3163 if (lock
->cpu
!= smp_processor_id())
3164 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3165 put_lock_stats(stats
);
3169 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3171 struct task_struct
*curr
= current
;
3172 struct held_lock
*hlock
, *prev_hlock
;
3173 struct lock_class_stats
*stats
;
3179 depth
= curr
->lockdep_depth
;
3180 if (DEBUG_LOCKS_WARN_ON(!depth
))
3184 for (i
= depth
-1; i
>= 0; i
--) {
3185 hlock
= curr
->held_locks
+ i
;
3187 * We must not cross into another context:
3189 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3191 if (hlock
->instance
== lock
)
3195 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3199 cpu
= smp_processor_id();
3200 if (hlock
->waittime_stamp
) {
3201 now
= sched_clock();
3202 waittime
= now
- hlock
->waittime_stamp
;
3203 hlock
->holdtime_stamp
= now
;
3206 trace_lock_acquired(lock
, ip
, waittime
);
3208 stats
= get_lock_stats(hlock_class(hlock
));
3211 lock_time_inc(&stats
->read_waittime
, waittime
);
3213 lock_time_inc(&stats
->write_waittime
, waittime
);
3215 if (lock
->cpu
!= cpu
)
3216 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3217 put_lock_stats(stats
);
3223 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3225 unsigned long flags
;
3227 trace_lock_contended(lock
, ip
);
3229 if (unlikely(!lock_stat
))
3232 if (unlikely(current
->lockdep_recursion
))
3235 raw_local_irq_save(flags
);
3237 current
->lockdep_recursion
= 1;
3238 __lock_contended(lock
, ip
);
3239 current
->lockdep_recursion
= 0;
3240 raw_local_irq_restore(flags
);
3242 EXPORT_SYMBOL_GPL(lock_contended
);
3244 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3246 unsigned long flags
;
3248 if (unlikely(!lock_stat
))
3251 if (unlikely(current
->lockdep_recursion
))
3254 raw_local_irq_save(flags
);
3256 current
->lockdep_recursion
= 1;
3257 __lock_acquired(lock
, ip
);
3258 current
->lockdep_recursion
= 0;
3259 raw_local_irq_restore(flags
);
3261 EXPORT_SYMBOL_GPL(lock_acquired
);
3265 * Used by the testsuite, sanitize the validator state
3266 * after a simulated failure:
3269 void lockdep_reset(void)
3271 unsigned long flags
;
3274 raw_local_irq_save(flags
);
3275 current
->curr_chain_key
= 0;
3276 current
->lockdep_depth
= 0;
3277 current
->lockdep_recursion
= 0;
3278 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3279 nr_hardirq_chains
= 0;
3280 nr_softirq_chains
= 0;
3281 nr_process_chains
= 0;
3283 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3284 INIT_LIST_HEAD(chainhash_table
+ i
);
3285 raw_local_irq_restore(flags
);
3288 static void zap_class(struct lock_class
*class)
3293 * Remove all dependencies this lock is
3296 for (i
= 0; i
< nr_list_entries
; i
++) {
3297 if (list_entries
[i
].class == class)
3298 list_del_rcu(&list_entries
[i
].entry
);
3301 * Unhash the class and remove it from the all_lock_classes list:
3303 list_del_rcu(&class->hash_entry
);
3304 list_del_rcu(&class->lock_entry
);
3309 static inline int within(const void *addr
, void *start
, unsigned long size
)
3311 return addr
>= start
&& addr
< start
+ size
;
3314 void lockdep_free_key_range(void *start
, unsigned long size
)
3316 struct lock_class
*class, *next
;
3317 struct list_head
*head
;
3318 unsigned long flags
;
3322 raw_local_irq_save(flags
);
3323 locked
= graph_lock();
3326 * Unhash all classes that were created by this module:
3328 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3329 head
= classhash_table
+ i
;
3330 if (list_empty(head
))
3332 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3333 if (within(class->key
, start
, size
))
3335 else if (within(class->name
, start
, size
))
3342 raw_local_irq_restore(flags
);
3345 void lockdep_reset_lock(struct lockdep_map
*lock
)
3347 struct lock_class
*class, *next
;
3348 struct list_head
*head
;
3349 unsigned long flags
;
3353 raw_local_irq_save(flags
);
3356 * Remove all classes this lock might have:
3358 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3360 * If the class exists we look it up and zap it:
3362 class = look_up_lock_class(lock
, j
);
3367 * Debug check: in the end all mapped classes should
3370 locked
= graph_lock();
3371 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3372 head
= classhash_table
+ i
;
3373 if (list_empty(head
))
3375 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3376 if (unlikely(class == lock
->class_cache
)) {
3377 if (debug_locks_off_graph_unlock())
3387 raw_local_irq_restore(flags
);
3390 void lockdep_init(void)
3395 * Some architectures have their own start_kernel()
3396 * code which calls lockdep_init(), while we also
3397 * call lockdep_init() from the start_kernel() itself,
3398 * and we want to initialize the hashes only once:
3400 if (lockdep_initialized
)
3403 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3404 INIT_LIST_HEAD(classhash_table
+ i
);
3406 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3407 INIT_LIST_HEAD(chainhash_table
+ i
);
3409 lockdep_initialized
= 1;
3412 void __init
lockdep_info(void)
3414 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3416 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
3417 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
3418 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
3419 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
3420 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
3421 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
3422 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
3424 printk(" memory used by lock dependency info: %lu kB\n",
3425 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
3426 sizeof(struct list_head
) * CLASSHASH_SIZE
+
3427 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
3428 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
3429 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
3431 printk(" per task-struct memory footprint: %lu bytes\n",
3432 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
3434 #ifdef CONFIG_DEBUG_LOCKDEP
3435 if (lockdep_init_error
) {
3436 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3437 printk("Call stack leading to lockdep invocation was:\n");
3438 print_stack_trace(&lockdep_init_trace
, 0);
3444 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
3445 const void *mem_to
, struct held_lock
*hlock
)
3447 if (!debug_locks_off())
3449 if (debug_locks_silent
)
3452 printk("\n=========================\n");
3453 printk( "[ BUG: held lock freed! ]\n");
3454 printk( "-------------------------\n");
3455 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3456 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
3458 lockdep_print_held_locks(curr
);
3460 printk("\nstack backtrace:\n");
3464 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
3465 const void* lock_from
, unsigned long lock_len
)
3467 return lock_from
+ lock_len
<= mem_from
||
3468 mem_from
+ mem_len
<= lock_from
;
3472 * Called when kernel memory is freed (or unmapped), or if a lock
3473 * is destroyed or reinitialized - this code checks whether there is
3474 * any held lock in the memory range of <from> to <to>:
3476 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
3478 struct task_struct
*curr
= current
;
3479 struct held_lock
*hlock
;
3480 unsigned long flags
;
3483 if (unlikely(!debug_locks
))
3486 local_irq_save(flags
);
3487 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3488 hlock
= curr
->held_locks
+ i
;
3490 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
3491 sizeof(*hlock
->instance
)))
3494 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
3497 local_irq_restore(flags
);
3499 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
3501 static void print_held_locks_bug(struct task_struct
*curr
)
3503 if (!debug_locks_off())
3505 if (debug_locks_silent
)
3508 printk("\n=====================================\n");
3509 printk( "[ BUG: lock held at task exit time! ]\n");
3510 printk( "-------------------------------------\n");
3511 printk("%s/%d is exiting with locks still held!\n",
3512 curr
->comm
, task_pid_nr(curr
));
3513 lockdep_print_held_locks(curr
);
3515 printk("\nstack backtrace:\n");
3519 void debug_check_no_locks_held(struct task_struct
*task
)
3521 if (unlikely(task
->lockdep_depth
> 0))
3522 print_held_locks_bug(task
);
3525 void debug_show_all_locks(void)
3527 struct task_struct
*g
, *p
;
3531 if (unlikely(!debug_locks
)) {
3532 printk("INFO: lockdep is turned off.\n");
3535 printk("\nShowing all locks held in the system:\n");
3538 * Here we try to get the tasklist_lock as hard as possible,
3539 * if not successful after 2 seconds we ignore it (but keep
3540 * trying). This is to enable a debug printout even if a
3541 * tasklist_lock-holding task deadlocks or crashes.
3544 if (!read_trylock(&tasklist_lock
)) {
3546 printk("hm, tasklist_lock locked, retrying... ");
3549 printk(" #%d", 10-count
);
3553 printk(" ignoring it.\n");
3557 printk(KERN_CONT
" locked it.\n");
3560 do_each_thread(g
, p
) {
3562 * It's not reliable to print a task's held locks
3563 * if it's not sleeping (or if it's not the current
3566 if (p
->state
== TASK_RUNNING
&& p
!= current
)
3568 if (p
->lockdep_depth
)
3569 lockdep_print_held_locks(p
);
3571 if (read_trylock(&tasklist_lock
))
3573 } while_each_thread(g
, p
);
3576 printk("=============================================\n\n");
3579 read_unlock(&tasklist_lock
);
3581 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
3584 * Careful: only use this function if you are sure that
3585 * the task cannot run in parallel!
3587 void __debug_show_held_locks(struct task_struct
*task
)
3589 if (unlikely(!debug_locks
)) {
3590 printk("INFO: lockdep is turned off.\n");
3593 lockdep_print_held_locks(task
);
3595 EXPORT_SYMBOL_GPL(__debug_show_held_locks
);
3597 void debug_show_held_locks(struct task_struct
*task
)
3599 __debug_show_held_locks(task
);
3601 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
3603 void lockdep_sys_exit(void)
3605 struct task_struct
*curr
= current
;
3607 if (unlikely(curr
->lockdep_depth
)) {
3608 if (!debug_locks_off())
3610 printk("\n================================================\n");
3611 printk( "[ BUG: lock held when returning to user space! ]\n");
3612 printk( "------------------------------------------------\n");
3613 printk("%s/%d is leaving the kernel with locks still held!\n",
3614 curr
->comm
, curr
->pid
);
3615 lockdep_print_held_locks(curr
);