4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #include <linux/mutex.h>
29 #include <linux/sched.h>
30 #include <linux/delay.h>
31 #include <linux/module.h>
32 #include <linux/proc_fs.h>
33 #include <linux/seq_file.h>
34 #include <linux/spinlock.h>
35 #include <linux/kallsyms.h>
36 #include <linux/interrupt.h>
37 #include <linux/stacktrace.h>
38 #include <linux/debug_locks.h>
39 #include <linux/irqflags.h>
40 #include <linux/utsname.h>
41 #include <linux/hash.h>
42 #include <linux/ftrace.h>
44 #include <asm/sections.h>
46 #include "lockdep_internals.h"
48 #ifdef CONFIG_PROVE_LOCKING
49 int prove_locking
= 1;
50 module_param(prove_locking
, int, 0644);
52 #define prove_locking 0
55 #ifdef CONFIG_LOCK_STAT
57 module_param(lock_stat
, int, 0644);
63 * lockdep_lock: protects the lockdep graph, the hashes and the
64 * class/list/hash allocators.
66 * This is one of the rare exceptions where it's justified
67 * to use a raw spinlock - we really dont want the spinlock
68 * code to recurse back into the lockdep code...
70 static raw_spinlock_t lockdep_lock
= (raw_spinlock_t
)__RAW_SPIN_LOCK_UNLOCKED
;
72 static int graph_lock(void)
74 __raw_spin_lock(&lockdep_lock
);
76 * Make sure that if another CPU detected a bug while
77 * walking the graph we dont change it (while the other
78 * CPU is busy printing out stuff with the graph lock
82 __raw_spin_unlock(&lockdep_lock
);
85 /* prevent any recursions within lockdep from causing deadlocks */
86 current
->lockdep_recursion
++;
90 static inline int graph_unlock(void)
92 if (debug_locks
&& !__raw_spin_is_locked(&lockdep_lock
))
93 return DEBUG_LOCKS_WARN_ON(1);
95 current
->lockdep_recursion
--;
96 __raw_spin_unlock(&lockdep_lock
);
101 * Turn lock debugging off and return with 0 if it was off already,
102 * and also release the graph lock:
104 static inline int debug_locks_off_graph_unlock(void)
106 int ret
= debug_locks_off();
108 __raw_spin_unlock(&lockdep_lock
);
113 static int lockdep_initialized
;
115 unsigned long nr_list_entries
;
116 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
119 * All data structures here are protected by the global debug_lock.
121 * Mutex key structs only get allocated, once during bootup, and never
122 * get freed - this significantly simplifies the debugging code.
124 unsigned long nr_lock_classes
;
125 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
127 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
129 if (!hlock
->class_idx
) {
130 DEBUG_LOCKS_WARN_ON(1);
133 return lock_classes
+ hlock
->class_idx
- 1;
136 #ifdef CONFIG_LOCK_STAT
137 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
], lock_stats
);
139 static int lock_contention_point(struct lock_class
*class, unsigned long ip
)
143 for (i
= 0; i
< ARRAY_SIZE(class->contention_point
); i
++) {
144 if (class->contention_point
[i
] == 0) {
145 class->contention_point
[i
] = ip
;
148 if (class->contention_point
[i
] == ip
)
155 static void lock_time_inc(struct lock_time
*lt
, s64 time
)
160 if (time
< lt
->min
|| !lt
->min
)
167 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
169 dst
->min
+= src
->min
;
170 dst
->max
+= src
->max
;
171 dst
->total
+= src
->total
;
175 struct lock_class_stats
lock_stats(struct lock_class
*class)
177 struct lock_class_stats stats
;
180 memset(&stats
, 0, sizeof(struct lock_class_stats
));
181 for_each_possible_cpu(cpu
) {
182 struct lock_class_stats
*pcs
=
183 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
185 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
186 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
188 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
189 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
191 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
192 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
194 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
195 stats
.bounces
[i
] += pcs
->bounces
[i
];
201 void clear_lock_stats(struct lock_class
*class)
205 for_each_possible_cpu(cpu
) {
206 struct lock_class_stats
*cpu_stats
=
207 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
209 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
211 memset(class->contention_point
, 0, sizeof(class->contention_point
));
214 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
216 return &get_cpu_var(lock_stats
)[class - lock_classes
];
219 static void put_lock_stats(struct lock_class_stats
*stats
)
221 put_cpu_var(lock_stats
);
224 static void lock_release_holdtime(struct held_lock
*hlock
)
226 struct lock_class_stats
*stats
;
232 holdtime
= sched_clock() - hlock
->holdtime_stamp
;
234 stats
= get_lock_stats(hlock_class(hlock
));
236 lock_time_inc(&stats
->read_holdtime
, holdtime
);
238 lock_time_inc(&stats
->write_holdtime
, holdtime
);
239 put_lock_stats(stats
);
242 static inline void lock_release_holdtime(struct held_lock
*hlock
)
248 * We keep a global list of all lock classes. The list only grows,
249 * never shrinks. The list is only accessed with the lockdep
250 * spinlock lock held.
252 LIST_HEAD(all_lock_classes
);
255 * The lockdep classes are in a hash-table as well, for fast lookup:
257 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
258 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
259 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
260 #define classhashentry(key) (classhash_table + __classhashfn((key)))
262 static struct list_head classhash_table
[CLASSHASH_SIZE
];
265 * We put the lock dependency chains into a hash-table as well, to cache
268 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
269 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
270 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
271 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
273 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
276 * The hash key of the lock dependency chains is a hash itself too:
277 * it's a hash of all locks taken up to that lock, including that lock.
278 * It's a 64-bit hash, because it's important for the keys to be
281 #define iterate_chain_key(key1, key2) \
282 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
283 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
286 void lockdep_off(void)
288 current
->lockdep_recursion
++;
291 EXPORT_SYMBOL(lockdep_off
);
293 void lockdep_on(void)
295 current
->lockdep_recursion
--;
298 EXPORT_SYMBOL(lockdep_on
);
301 * Debugging switches:
305 #define VERY_VERBOSE 0
308 # define HARDIRQ_VERBOSE 1
309 # define SOFTIRQ_VERBOSE 1
311 # define HARDIRQ_VERBOSE 0
312 # define SOFTIRQ_VERBOSE 0
315 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
317 * Quick filtering for interesting events:
319 static int class_filter(struct lock_class
*class)
323 if (class->name_version
== 1 &&
324 !strcmp(class->name
, "lockname"))
326 if (class->name_version
== 1 &&
327 !strcmp(class->name
, "&struct->lockfield"))
330 /* Filter everything else. 1 would be to allow everything else */
335 static int verbose(struct lock_class
*class)
338 return class_filter(class);
344 * Stack-trace: tightly packed array of stack backtrace
345 * addresses. Protected by the graph_lock.
347 unsigned long nr_stack_trace_entries
;
348 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
350 static int save_trace(struct stack_trace
*trace
)
352 trace
->nr_entries
= 0;
353 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
354 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
358 save_stack_trace(trace
);
360 trace
->max_entries
= trace
->nr_entries
;
362 nr_stack_trace_entries
+= trace
->nr_entries
;
364 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
365 if (!debug_locks_off_graph_unlock())
368 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
369 printk("turning off the locking correctness validator.\n");
378 unsigned int nr_hardirq_chains
;
379 unsigned int nr_softirq_chains
;
380 unsigned int nr_process_chains
;
381 unsigned int max_lockdep_depth
;
382 unsigned int max_recursion_depth
;
384 static unsigned int lockdep_dependency_gen_id
;
386 static bool lockdep_dependency_visit(struct lock_class
*source
,
390 lockdep_dependency_gen_id
++;
391 if (source
->dep_gen_id
== lockdep_dependency_gen_id
)
393 source
->dep_gen_id
= lockdep_dependency_gen_id
;
397 #ifdef CONFIG_DEBUG_LOCKDEP
399 * We cannot printk in early bootup code. Not even early_printk()
400 * might work. So we mark any initialization errors and printk
401 * about it later on, in lockdep_info().
403 static int lockdep_init_error
;
404 static unsigned long lockdep_init_trace_data
[20];
405 static struct stack_trace lockdep_init_trace
= {
406 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
407 .entries
= lockdep_init_trace_data
,
411 * Various lockdep statistics:
413 atomic_t chain_lookup_hits
;
414 atomic_t chain_lookup_misses
;
415 atomic_t hardirqs_on_events
;
416 atomic_t hardirqs_off_events
;
417 atomic_t redundant_hardirqs_on
;
418 atomic_t redundant_hardirqs_off
;
419 atomic_t softirqs_on_events
;
420 atomic_t softirqs_off_events
;
421 atomic_t redundant_softirqs_on
;
422 atomic_t redundant_softirqs_off
;
423 atomic_t nr_unused_locks
;
424 atomic_t nr_cyclic_checks
;
425 atomic_t nr_cyclic_check_recursions
;
426 atomic_t nr_find_usage_forwards_checks
;
427 atomic_t nr_find_usage_forwards_recursions
;
428 atomic_t nr_find_usage_backwards_checks
;
429 atomic_t nr_find_usage_backwards_recursions
;
430 # define debug_atomic_inc(ptr) atomic_inc(ptr)
431 # define debug_atomic_dec(ptr) atomic_dec(ptr)
432 # define debug_atomic_read(ptr) atomic_read(ptr)
434 # define debug_atomic_inc(ptr) do { } while (0)
435 # define debug_atomic_dec(ptr) do { } while (0)
436 # define debug_atomic_read(ptr) 0
443 static const char *usage_str
[] =
445 [LOCK_USED
] = "initial-use ",
446 [LOCK_USED_IN_HARDIRQ
] = "in-hardirq-W",
447 [LOCK_USED_IN_SOFTIRQ
] = "in-softirq-W",
448 [LOCK_ENABLED_SOFTIRQS
] = "softirq-on-W",
449 [LOCK_ENABLED_HARDIRQS
] = "hardirq-on-W",
450 [LOCK_USED_IN_HARDIRQ_READ
] = "in-hardirq-R",
451 [LOCK_USED_IN_SOFTIRQ_READ
] = "in-softirq-R",
452 [LOCK_ENABLED_SOFTIRQS_READ
] = "softirq-on-R",
453 [LOCK_ENABLED_HARDIRQS_READ
] = "hardirq-on-R",
456 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
458 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
462 get_usage_chars(struct lock_class
*class, char *c1
, char *c2
, char *c3
, char *c4
)
464 *c1
= '.', *c2
= '.', *c3
= '.', *c4
= '.';
466 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ
)
469 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS
)
472 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ
)
475 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS
)
478 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
480 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ_READ
) {
482 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
486 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
488 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ_READ
) {
490 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
495 static void print_lock_name(struct lock_class
*class)
497 char str
[KSYM_NAME_LEN
], c1
, c2
, c3
, c4
;
500 get_usage_chars(class, &c1
, &c2
, &c3
, &c4
);
504 name
= __get_key_name(class->key
, str
);
505 printk(" (%s", name
);
507 printk(" (%s", name
);
508 if (class->name_version
> 1)
509 printk("#%d", class->name_version
);
511 printk("/%d", class->subclass
);
513 printk("){%c%c%c%c}", c1
, c2
, c3
, c4
);
516 static void print_lockdep_cache(struct lockdep_map
*lock
)
519 char str
[KSYM_NAME_LEN
];
523 name
= __get_key_name(lock
->key
->subkeys
, str
);
528 static void print_lock(struct held_lock
*hlock
)
530 print_lock_name(hlock_class(hlock
));
532 print_ip_sym(hlock
->acquire_ip
);
535 static void lockdep_print_held_locks(struct task_struct
*curr
)
537 int i
, depth
= curr
->lockdep_depth
;
540 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
543 printk("%d lock%s held by %s/%d:\n",
544 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
546 for (i
= 0; i
< depth
; i
++) {
548 print_lock(curr
->held_locks
+ i
);
552 static void print_lock_class_header(struct lock_class
*class, int depth
)
556 printk("%*s->", depth
, "");
557 print_lock_name(class);
558 printk(" ops: %lu", class->ops
);
561 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
562 if (class->usage_mask
& (1 << bit
)) {
565 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
566 len
+= printk(" at:\n");
567 print_stack_trace(class->usage_traces
+ bit
, len
);
570 printk("%*s }\n", depth
, "");
572 printk("%*s ... key at: ",depth
,"");
573 print_ip_sym((unsigned long)class->key
);
577 * printk all lock dependencies starting at <entry>:
579 static void print_lock_dependencies(struct lock_class
*class, int depth
)
581 struct lock_list
*entry
;
583 if (lockdep_dependency_visit(class, depth
))
586 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
589 print_lock_class_header(class, depth
);
591 list_for_each_entry(entry
, &class->locks_after
, entry
) {
592 if (DEBUG_LOCKS_WARN_ON(!entry
->class))
595 print_lock_dependencies(entry
->class, depth
+ 1);
597 printk("%*s ... acquired at:\n",depth
,"");
598 print_stack_trace(&entry
->trace
, 2);
603 static void print_kernel_version(void)
605 printk("%s %.*s\n", init_utsname()->release
,
606 (int)strcspn(init_utsname()->version
, " "),
607 init_utsname()->version
);
610 static int very_verbose(struct lock_class
*class)
613 return class_filter(class);
619 * Is this the address of a static object:
621 static int static_obj(void *obj
)
623 unsigned long start
= (unsigned long) &_stext
,
624 end
= (unsigned long) &_end
,
625 addr
= (unsigned long) obj
;
633 if ((addr
>= start
) && (addr
< end
))
640 for_each_possible_cpu(i
) {
641 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
642 end
= (unsigned long) &__per_cpu_start
+ PERCPU_ENOUGH_ROOM
645 if ((addr
>= start
) && (addr
< end
))
653 return is_module_address(addr
);
657 * To make lock name printouts unique, we calculate a unique
658 * class->name_version generation counter:
660 static int count_matching_names(struct lock_class
*new_class
)
662 struct lock_class
*class;
665 if (!new_class
->name
)
668 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
669 if (new_class
->key
- new_class
->subclass
== class->key
)
670 return class->name_version
;
671 if (class->name
&& !strcmp(class->name
, new_class
->name
))
672 count
= max(count
, class->name_version
);
679 * Register a lock's class in the hash-table, if the class is not present
680 * yet. Otherwise we look it up. We cache the result in the lock object
681 * itself, so actual lookup of the hash should be once per lock object.
683 static inline struct lock_class
*
684 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
686 struct lockdep_subclass_key
*key
;
687 struct list_head
*hash_head
;
688 struct lock_class
*class;
690 #ifdef CONFIG_DEBUG_LOCKDEP
692 * If the architecture calls into lockdep before initializing
693 * the hashes then we'll warn about it later. (we cannot printk
696 if (unlikely(!lockdep_initialized
)) {
698 lockdep_init_error
= 1;
699 save_stack_trace(&lockdep_init_trace
);
704 * Static locks do not have their class-keys yet - for them the key
705 * is the lock object itself:
707 if (unlikely(!lock
->key
))
708 lock
->key
= (void *)lock
;
711 * NOTE: the class-key must be unique. For dynamic locks, a static
712 * lock_class_key variable is passed in through the mutex_init()
713 * (or spin_lock_init()) call - which acts as the key. For static
714 * locks we use the lock object itself as the key.
716 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
717 sizeof(struct lockdep_map
));
719 key
= lock
->key
->subkeys
+ subclass
;
721 hash_head
= classhashentry(key
);
724 * We can walk the hash lockfree, because the hash only
725 * grows, and we are careful when adding entries to the end:
727 list_for_each_entry(class, hash_head
, hash_entry
) {
728 if (class->key
== key
) {
729 WARN_ON_ONCE(class->name
!= lock
->name
);
738 * Register a lock's class in the hash-table, if the class is not present
739 * yet. Otherwise we look it up. We cache the result in the lock object
740 * itself, so actual lookup of the hash should be once per lock object.
742 static inline struct lock_class
*
743 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
745 struct lockdep_subclass_key
*key
;
746 struct list_head
*hash_head
;
747 struct lock_class
*class;
750 class = look_up_lock_class(lock
, subclass
);
755 * Debug-check: all keys must be persistent!
757 if (!static_obj(lock
->key
)) {
759 printk("INFO: trying to register non-static key.\n");
760 printk("the code is fine but needs lockdep annotation.\n");
761 printk("turning off the locking correctness validator.\n");
767 key
= lock
->key
->subkeys
+ subclass
;
768 hash_head
= classhashentry(key
);
770 raw_local_irq_save(flags
);
772 raw_local_irq_restore(flags
);
776 * We have to do the hash-walk again, to avoid races
779 list_for_each_entry(class, hash_head
, hash_entry
)
780 if (class->key
== key
)
783 * Allocate a new key from the static array, and add it to
786 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
787 if (!debug_locks_off_graph_unlock()) {
788 raw_local_irq_restore(flags
);
791 raw_local_irq_restore(flags
);
793 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
794 printk("turning off the locking correctness validator.\n");
797 class = lock_classes
+ nr_lock_classes
++;
798 debug_atomic_inc(&nr_unused_locks
);
800 class->name
= lock
->name
;
801 class->subclass
= subclass
;
802 INIT_LIST_HEAD(&class->lock_entry
);
803 INIT_LIST_HEAD(&class->locks_before
);
804 INIT_LIST_HEAD(&class->locks_after
);
805 class->name_version
= count_matching_names(class);
807 * We use RCU's safe list-add method to make
808 * parallel walking of the hash-list safe:
810 list_add_tail_rcu(&class->hash_entry
, hash_head
);
812 * Add it to the global list of classes:
814 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
816 if (verbose(class)) {
818 raw_local_irq_restore(flags
);
820 printk("\nnew class %p: %s", class->key
, class->name
);
821 if (class->name_version
> 1)
822 printk("#%d", class->name_version
);
826 raw_local_irq_save(flags
);
828 raw_local_irq_restore(flags
);
834 raw_local_irq_restore(flags
);
836 if (!subclass
|| force
)
837 lock
->class_cache
= class;
839 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
845 #ifdef CONFIG_PROVE_LOCKING
847 * Allocate a lockdep entry. (assumes the graph_lock held, returns
848 * with NULL on failure)
850 static struct lock_list
*alloc_list_entry(void)
852 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
853 if (!debug_locks_off_graph_unlock())
856 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
857 printk("turning off the locking correctness validator.\n");
860 return list_entries
+ nr_list_entries
++;
864 * Add a new dependency to the head of the list:
866 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
867 struct list_head
*head
, unsigned long ip
, int distance
)
869 struct lock_list
*entry
;
871 * Lock not present yet - get a new dependency struct and
872 * add it to the list:
874 entry
= alloc_list_entry();
879 entry
->distance
= distance
;
880 if (!save_trace(&entry
->trace
))
884 * Since we never remove from the dependency list, the list can
885 * be walked lockless by other CPUs, it's only allocation
886 * that must be protected by the spinlock. But this also means
887 * we must make new entries visible only once writes to the
888 * entry become visible - hence the RCU op:
890 list_add_tail_rcu(&entry
->entry
, head
);
896 * Recursive, forwards-direction lock-dependency checking, used for
897 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
900 * (to keep the stackframe of the recursive functions small we
901 * use these global variables, and we also mark various helper
902 * functions as noinline.)
904 static struct held_lock
*check_source
, *check_target
;
907 * Print a dependency chain entry (this is only done when a deadlock
908 * has been detected):
911 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
913 if (debug_locks_silent
)
915 printk("\n-> #%u", depth
);
916 print_lock_name(target
->class);
918 print_stack_trace(&target
->trace
, 6);
924 * When a circular dependency is detected, print the
928 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
)
930 struct task_struct
*curr
= current
;
932 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
935 printk("\n=======================================================\n");
936 printk( "[ INFO: possible circular locking dependency detected ]\n");
937 print_kernel_version();
938 printk( "-------------------------------------------------------\n");
939 printk("%s/%d is trying to acquire lock:\n",
940 curr
->comm
, task_pid_nr(curr
));
941 print_lock(check_source
);
942 printk("\nbut task is already holding lock:\n");
943 print_lock(check_target
);
944 printk("\nwhich lock already depends on the new lock.\n\n");
945 printk("\nthe existing dependency chain (in reverse order) is:\n");
947 print_circular_bug_entry(entry
, depth
);
952 static noinline
int print_circular_bug_tail(void)
954 struct task_struct
*curr
= current
;
955 struct lock_list
this;
957 if (debug_locks_silent
)
960 this.class = hlock_class(check_source
);
961 if (!save_trace(&this.trace
))
964 print_circular_bug_entry(&this, 0);
966 printk("\nother info that might help us debug this:\n\n");
967 lockdep_print_held_locks(curr
);
969 printk("\nstack backtrace:\n");
975 #define RECURSION_LIMIT 40
977 static int noinline
print_infinite_recursion_bug(void)
979 if (!debug_locks_off_graph_unlock())
987 unsigned long __lockdep_count_forward_deps(struct lock_class
*class,
990 struct lock_list
*entry
;
991 unsigned long ret
= 1;
993 if (lockdep_dependency_visit(class, depth
))
997 * Recurse this class's dependency list:
999 list_for_each_entry(entry
, &class->locks_after
, entry
)
1000 ret
+= __lockdep_count_forward_deps(entry
->class, depth
+ 1);
1005 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1007 unsigned long ret
, flags
;
1009 local_irq_save(flags
);
1010 __raw_spin_lock(&lockdep_lock
);
1011 ret
= __lockdep_count_forward_deps(class, 0);
1012 __raw_spin_unlock(&lockdep_lock
);
1013 local_irq_restore(flags
);
1018 unsigned long __lockdep_count_backward_deps(struct lock_class
*class,
1021 struct lock_list
*entry
;
1022 unsigned long ret
= 1;
1024 if (lockdep_dependency_visit(class, depth
))
1027 * Recurse this class's dependency list:
1029 list_for_each_entry(entry
, &class->locks_before
, entry
)
1030 ret
+= __lockdep_count_backward_deps(entry
->class, depth
+ 1);
1035 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1037 unsigned long ret
, flags
;
1039 local_irq_save(flags
);
1040 __raw_spin_lock(&lockdep_lock
);
1041 ret
= __lockdep_count_backward_deps(class, 0);
1042 __raw_spin_unlock(&lockdep_lock
);
1043 local_irq_restore(flags
);
1049 * Prove that the dependency graph starting at <entry> can not
1050 * lead to <target>. Print an error and return 0 if it does.
1053 check_noncircular(struct lock_class
*source
, unsigned int depth
)
1055 struct lock_list
*entry
;
1057 if (lockdep_dependency_visit(source
, depth
))
1060 debug_atomic_inc(&nr_cyclic_check_recursions
);
1061 if (depth
> max_recursion_depth
)
1062 max_recursion_depth
= depth
;
1063 if (depth
>= RECURSION_LIMIT
)
1064 return print_infinite_recursion_bug();
1066 * Check this lock's dependency list:
1068 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1069 if (entry
->class == hlock_class(check_target
))
1070 return print_circular_bug_header(entry
, depth
+1);
1071 debug_atomic_inc(&nr_cyclic_checks
);
1072 if (!check_noncircular(entry
->class, depth
+1))
1073 return print_circular_bug_entry(entry
, depth
+1);
1078 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1080 * Forwards and backwards subgraph searching, for the purposes of
1081 * proving that two subgraphs can be connected by a new dependency
1082 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1084 static enum lock_usage_bit find_usage_bit
;
1085 static struct lock_class
*forwards_match
, *backwards_match
;
1088 * Find a node in the forwards-direction dependency sub-graph starting
1089 * at <source> that matches <find_usage_bit>.
1091 * Return 2 if such a node exists in the subgraph, and put that node
1092 * into <forwards_match>.
1094 * Return 1 otherwise and keep <forwards_match> unchanged.
1095 * Return 0 on error.
1098 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
1100 struct lock_list
*entry
;
1103 if (lockdep_dependency_visit(source
, depth
))
1106 if (depth
> max_recursion_depth
)
1107 max_recursion_depth
= depth
;
1108 if (depth
>= RECURSION_LIMIT
)
1109 return print_infinite_recursion_bug();
1111 debug_atomic_inc(&nr_find_usage_forwards_checks
);
1112 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1113 forwards_match
= source
;
1118 * Check this lock's dependency list:
1120 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1121 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
1122 ret
= find_usage_forwards(entry
->class, depth
+1);
1123 if (ret
== 2 || ret
== 0)
1130 * Find a node in the backwards-direction dependency sub-graph starting
1131 * at <source> that matches <find_usage_bit>.
1133 * Return 2 if such a node exists in the subgraph, and put that node
1134 * into <backwards_match>.
1136 * Return 1 otherwise and keep <backwards_match> unchanged.
1137 * Return 0 on error.
1140 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
1142 struct lock_list
*entry
;
1145 if (lockdep_dependency_visit(source
, depth
))
1148 if (!__raw_spin_is_locked(&lockdep_lock
))
1149 return DEBUG_LOCKS_WARN_ON(1);
1151 if (depth
> max_recursion_depth
)
1152 max_recursion_depth
= depth
;
1153 if (depth
>= RECURSION_LIMIT
)
1154 return print_infinite_recursion_bug();
1156 debug_atomic_inc(&nr_find_usage_backwards_checks
);
1157 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1158 backwards_match
= source
;
1162 if (!source
&& debug_locks_off_graph_unlock()) {
1168 * Check this lock's dependency list:
1170 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
1171 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
1172 ret
= find_usage_backwards(entry
->class, depth
+1);
1173 if (ret
== 2 || ret
== 0)
1180 print_bad_irq_dependency(struct task_struct
*curr
,
1181 struct held_lock
*prev
,
1182 struct held_lock
*next
,
1183 enum lock_usage_bit bit1
,
1184 enum lock_usage_bit bit2
,
1185 const char *irqclass
)
1187 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1190 printk("\n======================================================\n");
1191 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1192 irqclass
, irqclass
);
1193 print_kernel_version();
1194 printk( "------------------------------------------------------\n");
1195 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1196 curr
->comm
, task_pid_nr(curr
),
1197 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1198 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1199 curr
->hardirqs_enabled
,
1200 curr
->softirqs_enabled
);
1203 printk("\nand this task is already holding:\n");
1205 printk("which would create a new lock dependency:\n");
1206 print_lock_name(hlock_class(prev
));
1208 print_lock_name(hlock_class(next
));
1211 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1213 print_lock_name(backwards_match
);
1214 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1216 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
1218 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1219 print_lock_name(forwards_match
);
1220 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1223 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
1225 printk("\nother info that might help us debug this:\n\n");
1226 lockdep_print_held_locks(curr
);
1228 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
1229 print_lock_dependencies(backwards_match
, 0);
1231 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
1232 print_lock_dependencies(forwards_match
, 0);
1234 printk("\nstack backtrace:\n");
1241 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1242 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1243 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1247 find_usage_bit
= bit_backwards
;
1248 /* fills in <backwards_match> */
1249 ret
= find_usage_backwards(hlock_class(prev
), 0);
1250 if (!ret
|| ret
== 1)
1253 find_usage_bit
= bit_forwards
;
1254 ret
= find_usage_forwards(hlock_class(next
), 0);
1255 if (!ret
|| ret
== 1)
1258 return print_bad_irq_dependency(curr
, prev
, next
,
1259 bit_backwards
, bit_forwards
, irqclass
);
1263 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1264 struct held_lock
*next
)
1267 * Prove that the new dependency does not connect a hardirq-safe
1268 * lock with a hardirq-unsafe lock - to achieve this we search
1269 * the backwards-subgraph starting at <prev>, and the
1270 * forwards-subgraph starting at <next>:
1272 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ
,
1273 LOCK_ENABLED_HARDIRQS
, "hard"))
1277 * Prove that the new dependency does not connect a hardirq-safe-read
1278 * lock with a hardirq-unsafe lock - to achieve this we search
1279 * the backwards-subgraph starting at <prev>, and the
1280 * forwards-subgraph starting at <next>:
1282 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ_READ
,
1283 LOCK_ENABLED_HARDIRQS
, "hard-read"))
1287 * Prove that the new dependency does not connect a softirq-safe
1288 * lock with a softirq-unsafe lock - to achieve this we search
1289 * the backwards-subgraph starting at <prev>, and the
1290 * forwards-subgraph starting at <next>:
1292 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ
,
1293 LOCK_ENABLED_SOFTIRQS
, "soft"))
1296 * Prove that the new dependency does not connect a softirq-safe-read
1297 * lock with a softirq-unsafe lock - to achieve this we search
1298 * the backwards-subgraph starting at <prev>, and the
1299 * forwards-subgraph starting at <next>:
1301 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ_READ
,
1302 LOCK_ENABLED_SOFTIRQS
, "soft"))
1308 static void inc_chains(void)
1310 if (current
->hardirq_context
)
1311 nr_hardirq_chains
++;
1313 if (current
->softirq_context
)
1314 nr_softirq_chains
++;
1316 nr_process_chains
++;
1323 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1324 struct held_lock
*next
)
1329 static inline void inc_chains(void)
1331 nr_process_chains
++;
1337 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1338 struct held_lock
*next
)
1340 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1343 printk("\n=============================================\n");
1344 printk( "[ INFO: possible recursive locking detected ]\n");
1345 print_kernel_version();
1346 printk( "---------------------------------------------\n");
1347 printk("%s/%d is trying to acquire lock:\n",
1348 curr
->comm
, task_pid_nr(curr
));
1350 printk("\nbut task is already holding lock:\n");
1353 printk("\nother info that might help us debug this:\n");
1354 lockdep_print_held_locks(curr
);
1356 printk("\nstack backtrace:\n");
1363 * Check whether we are holding such a class already.
1365 * (Note that this has to be done separately, because the graph cannot
1366 * detect such classes of deadlocks.)
1368 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1371 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1372 struct lockdep_map
*next_instance
, int read
)
1374 struct held_lock
*prev
;
1377 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1378 prev
= curr
->held_locks
+ i
;
1379 if (hlock_class(prev
) != hlock_class(next
))
1382 * Allow read-after-read recursion of the same
1383 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1385 if ((read
== 2) && prev
->read
)
1387 return print_deadlock_bug(curr
, prev
, next
);
1393 * There was a chain-cache miss, and we are about to add a new dependency
1394 * to a previous lock. We recursively validate the following rules:
1396 * - would the adding of the <prev> -> <next> dependency create a
1397 * circular dependency in the graph? [== circular deadlock]
1399 * - does the new prev->next dependency connect any hardirq-safe lock
1400 * (in the full backwards-subgraph starting at <prev>) with any
1401 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1402 * <next>)? [== illegal lock inversion with hardirq contexts]
1404 * - does the new prev->next dependency connect any softirq-safe lock
1405 * (in the full backwards-subgraph starting at <prev>) with any
1406 * softirq-unsafe lock (in the full forwards-subgraph starting at
1407 * <next>)? [== illegal lock inversion with softirq contexts]
1409 * any of these scenarios could lead to a deadlock.
1411 * Then if all the validations pass, we add the forwards and backwards
1415 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1416 struct held_lock
*next
, int distance
)
1418 struct lock_list
*entry
;
1422 * Prove that the new <prev> -> <next> dependency would not
1423 * create a circular dependency in the graph. (We do this by
1424 * forward-recursing into the graph starting at <next>, and
1425 * checking whether we can reach <prev>.)
1427 * We are using global variables to control the recursion, to
1428 * keep the stackframe size of the recursive functions low:
1430 check_source
= next
;
1431 check_target
= prev
;
1432 if (!(check_noncircular(hlock_class(next
), 0)))
1433 return print_circular_bug_tail();
1435 if (!check_prev_add_irq(curr
, prev
, next
))
1439 * For recursive read-locks we do all the dependency checks,
1440 * but we dont store read-triggered dependencies (only
1441 * write-triggered dependencies). This ensures that only the
1442 * write-side dependencies matter, and that if for example a
1443 * write-lock never takes any other locks, then the reads are
1444 * equivalent to a NOP.
1446 if (next
->read
== 2 || prev
->read
== 2)
1449 * Is the <prev> -> <next> dependency already present?
1451 * (this may occur even though this is a new chain: consider
1452 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1453 * chains - the second one will be new, but L1 already has
1454 * L2 added to its dependency list, due to the first chain.)
1456 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1457 if (entry
->class == hlock_class(next
)) {
1459 entry
->distance
= 1;
1465 * Ok, all validations passed, add the new lock
1466 * to the previous lock's dependency list:
1468 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1469 &hlock_class(prev
)->locks_after
,
1470 next
->acquire_ip
, distance
);
1475 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1476 &hlock_class(next
)->locks_before
,
1477 next
->acquire_ip
, distance
);
1482 * Debugging printouts:
1484 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1486 printk("\n new dependency: ");
1487 print_lock_name(hlock_class(prev
));
1489 print_lock_name(hlock_class(next
));
1492 return graph_lock();
1498 * Add the dependency to all directly-previous locks that are 'relevant'.
1499 * The ones that are relevant are (in increasing distance from curr):
1500 * all consecutive trylock entries and the final non-trylock entry - or
1501 * the end of this context's lock-chain - whichever comes first.
1504 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1506 int depth
= curr
->lockdep_depth
;
1507 struct held_lock
*hlock
;
1512 * Depth must not be zero for a non-head lock:
1517 * At least two relevant locks must exist for this
1520 if (curr
->held_locks
[depth
].irq_context
!=
1521 curr
->held_locks
[depth
-1].irq_context
)
1525 int distance
= curr
->lockdep_depth
- depth
+ 1;
1526 hlock
= curr
->held_locks
+ depth
-1;
1528 * Only non-recursive-read entries get new dependencies
1531 if (hlock
->read
!= 2) {
1532 if (!check_prev_add(curr
, hlock
, next
, distance
))
1535 * Stop after the first non-trylock entry,
1536 * as non-trylock entries have added their
1537 * own direct dependencies already, so this
1538 * lock is connected to them indirectly:
1540 if (!hlock
->trylock
)
1545 * End of lock-stack?
1550 * Stop the search if we cross into another context:
1552 if (curr
->held_locks
[depth
].irq_context
!=
1553 curr
->held_locks
[depth
-1].irq_context
)
1558 if (!debug_locks_off_graph_unlock())
1566 unsigned long nr_lock_chains
;
1567 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1568 int nr_chain_hlocks
;
1569 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1571 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1573 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1577 * Look up a dependency chain. If the key is not present yet then
1578 * add it and return 1 - in this case the new dependency chain is
1579 * validated. If the key is already hashed, return 0.
1580 * (On return with 1 graph_lock is held.)
1582 static inline int lookup_chain_cache(struct task_struct
*curr
,
1583 struct held_lock
*hlock
,
1586 struct lock_class
*class = hlock_class(hlock
);
1587 struct list_head
*hash_head
= chainhashentry(chain_key
);
1588 struct lock_chain
*chain
;
1589 struct held_lock
*hlock_curr
, *hlock_next
;
1592 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1595 * We can walk it lock-free, because entries only get added
1598 list_for_each_entry(chain
, hash_head
, entry
) {
1599 if (chain
->chain_key
== chain_key
) {
1601 debug_atomic_inc(&chain_lookup_hits
);
1602 if (very_verbose(class))
1603 printk("\nhash chain already cached, key: "
1604 "%016Lx tail class: [%p] %s\n",
1605 (unsigned long long)chain_key
,
1606 class->key
, class->name
);
1610 if (very_verbose(class))
1611 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1612 (unsigned long long)chain_key
, class->key
, class->name
);
1614 * Allocate a new chain entry from the static array, and add
1620 * We have to walk the chain again locked - to avoid duplicates:
1622 list_for_each_entry(chain
, hash_head
, entry
) {
1623 if (chain
->chain_key
== chain_key
) {
1628 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1629 if (!debug_locks_off_graph_unlock())
1632 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1633 printk("turning off the locking correctness validator.\n");
1636 chain
= lock_chains
+ nr_lock_chains
++;
1637 chain
->chain_key
= chain_key
;
1638 chain
->irq_context
= hlock
->irq_context
;
1639 /* Find the first held_lock of current chain */
1641 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
1642 hlock_curr
= curr
->held_locks
+ i
;
1643 if (hlock_curr
->irq_context
!= hlock_next
->irq_context
)
1648 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
1649 cn
= nr_chain_hlocks
;
1650 while (cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
) {
1651 n
= cmpxchg(&nr_chain_hlocks
, cn
, cn
+ chain
->depth
);
1656 if (likely(cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
1658 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
1659 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
1660 chain_hlocks
[chain
->base
+ j
] = lock_id
;
1662 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
1664 list_add_tail_rcu(&chain
->entry
, hash_head
);
1665 debug_atomic_inc(&chain_lookup_misses
);
1671 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
1672 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
1675 * Trylock needs to maintain the stack of held locks, but it
1676 * does not add new dependencies, because trylock can be done
1679 * We look up the chain_key and do the O(N^2) check and update of
1680 * the dependencies only if this is a new dependency chain.
1681 * (If lookup_chain_cache() returns with 1 it acquires
1682 * graph_lock for us)
1684 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
1685 lookup_chain_cache(curr
, hlock
, chain_key
)) {
1687 * Check whether last held lock:
1689 * - is irq-safe, if this lock is irq-unsafe
1690 * - is softirq-safe, if this lock is hardirq-unsafe
1692 * And check whether the new lock's dependency graph
1693 * could lead back to the previous lock.
1695 * any of these scenarios could lead to a deadlock. If
1698 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
1703 * Mark recursive read, as we jump over it when
1704 * building dependencies (just like we jump over
1710 * Add dependency only if this lock is not the head
1711 * of the chain, and if it's not a secondary read-lock:
1713 if (!chain_head
&& ret
!= 2)
1714 if (!check_prevs_add(curr
, hlock
))
1718 /* after lookup_chain_cache(): */
1719 if (unlikely(!debug_locks
))
1725 static inline int validate_chain(struct task_struct
*curr
,
1726 struct lockdep_map
*lock
, struct held_lock
*hlock
,
1727 int chain_head
, u64 chain_key
)
1734 * We are building curr_chain_key incrementally, so double-check
1735 * it from scratch, to make sure that it's done correctly:
1737 static void check_chain_key(struct task_struct
*curr
)
1739 #ifdef CONFIG_DEBUG_LOCKDEP
1740 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1744 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1745 hlock
= curr
->held_locks
+ i
;
1746 if (chain_key
!= hlock
->prev_chain_key
) {
1748 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1749 curr
->lockdep_depth
, i
,
1750 (unsigned long long)chain_key
,
1751 (unsigned long long)hlock
->prev_chain_key
);
1755 id
= hlock
->class_idx
- 1;
1756 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
1759 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1760 hlock
->irq_context
))
1762 chain_key
= iterate_chain_key(chain_key
, id
);
1765 if (chain_key
!= curr
->curr_chain_key
) {
1767 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1768 curr
->lockdep_depth
, i
,
1769 (unsigned long long)chain_key
,
1770 (unsigned long long)curr
->curr_chain_key
);
1777 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1778 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1780 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1783 printk("\n=================================\n");
1784 printk( "[ INFO: inconsistent lock state ]\n");
1785 print_kernel_version();
1786 printk( "---------------------------------\n");
1788 printk("inconsistent {%s} -> {%s} usage.\n",
1789 usage_str
[prev_bit
], usage_str
[new_bit
]);
1791 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1792 curr
->comm
, task_pid_nr(curr
),
1793 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1794 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1795 trace_hardirqs_enabled(curr
),
1796 trace_softirqs_enabled(curr
));
1799 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1800 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
1802 print_irqtrace_events(curr
);
1803 printk("\nother info that might help us debug this:\n");
1804 lockdep_print_held_locks(curr
);
1806 printk("\nstack backtrace:\n");
1813 * Print out an error if an invalid bit is set:
1816 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1817 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1819 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
1820 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1824 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1825 enum lock_usage_bit new_bit
);
1827 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1830 * print irq inversion bug:
1833 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
1834 struct held_lock
*this, int forwards
,
1835 const char *irqclass
)
1837 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1840 printk("\n=========================================================\n");
1841 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1842 print_kernel_version();
1843 printk( "---------------------------------------------------------\n");
1844 printk("%s/%d just changed the state of lock:\n",
1845 curr
->comm
, task_pid_nr(curr
));
1848 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass
);
1850 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass
);
1851 print_lock_name(other
);
1852 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1854 printk("\nother info that might help us debug this:\n");
1855 lockdep_print_held_locks(curr
);
1857 printk("\nthe first lock's dependencies:\n");
1858 print_lock_dependencies(hlock_class(this), 0);
1860 printk("\nthe second lock's dependencies:\n");
1861 print_lock_dependencies(other
, 0);
1863 printk("\nstack backtrace:\n");
1870 * Prove that in the forwards-direction subgraph starting at <this>
1871 * there is no lock matching <mask>:
1874 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
1875 enum lock_usage_bit bit
, const char *irqclass
)
1879 find_usage_bit
= bit
;
1880 /* fills in <forwards_match> */
1881 ret
= find_usage_forwards(hlock_class(this), 0);
1882 if (!ret
|| ret
== 1)
1885 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
1889 * Prove that in the backwards-direction subgraph starting at <this>
1890 * there is no lock matching <mask>:
1893 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
1894 enum lock_usage_bit bit
, const char *irqclass
)
1898 find_usage_bit
= bit
;
1899 /* fills in <backwards_match> */
1900 ret
= find_usage_backwards(hlock_class(this), 0);
1901 if (!ret
|| ret
== 1)
1904 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
1907 void print_irqtrace_events(struct task_struct
*curr
)
1909 printk("irq event stamp: %u\n", curr
->irq_events
);
1910 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
1911 print_ip_sym(curr
->hardirq_enable_ip
);
1912 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
1913 print_ip_sym(curr
->hardirq_disable_ip
);
1914 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
1915 print_ip_sym(curr
->softirq_enable_ip
);
1916 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
1917 print_ip_sym(curr
->softirq_disable_ip
);
1920 static int hardirq_verbose(struct lock_class
*class)
1923 return class_filter(class);
1928 static int softirq_verbose(struct lock_class
*class)
1931 return class_filter(class);
1936 #define STRICT_READ_CHECKS 1
1938 static int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
1939 enum lock_usage_bit new_bit
)
1944 case LOCK_USED_IN_HARDIRQ
:
1945 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1947 if (!valid_state(curr
, this, new_bit
,
1948 LOCK_ENABLED_HARDIRQS_READ
))
1951 * just marked it hardirq-safe, check that this lock
1952 * took no hardirq-unsafe lock in the past:
1954 if (!check_usage_forwards(curr
, this,
1955 LOCK_ENABLED_HARDIRQS
, "hard"))
1957 #if STRICT_READ_CHECKS
1959 * just marked it hardirq-safe, check that this lock
1960 * took no hardirq-unsafe-read lock in the past:
1962 if (!check_usage_forwards(curr
, this,
1963 LOCK_ENABLED_HARDIRQS_READ
, "hard-read"))
1966 if (hardirq_verbose(hlock_class(this)))
1969 case LOCK_USED_IN_SOFTIRQ
:
1970 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1972 if (!valid_state(curr
, this, new_bit
,
1973 LOCK_ENABLED_SOFTIRQS_READ
))
1976 * just marked it softirq-safe, check that this lock
1977 * took no softirq-unsafe lock in the past:
1979 if (!check_usage_forwards(curr
, this,
1980 LOCK_ENABLED_SOFTIRQS
, "soft"))
1982 #if STRICT_READ_CHECKS
1984 * just marked it softirq-safe, check that this lock
1985 * took no softirq-unsafe-read lock in the past:
1987 if (!check_usage_forwards(curr
, this,
1988 LOCK_ENABLED_SOFTIRQS_READ
, "soft-read"))
1991 if (softirq_verbose(hlock_class(this)))
1994 case LOCK_USED_IN_HARDIRQ_READ
:
1995 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1998 * just marked it hardirq-read-safe, check that this lock
1999 * took no hardirq-unsafe lock in the past:
2001 if (!check_usage_forwards(curr
, this,
2002 LOCK_ENABLED_HARDIRQS
, "hard"))
2004 if (hardirq_verbose(hlock_class(this)))
2007 case LOCK_USED_IN_SOFTIRQ_READ
:
2008 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
2011 * just marked it softirq-read-safe, check that this lock
2012 * took no softirq-unsafe lock in the past:
2014 if (!check_usage_forwards(curr
, this,
2015 LOCK_ENABLED_SOFTIRQS
, "soft"))
2017 if (softirq_verbose(hlock_class(this)))
2020 case LOCK_ENABLED_HARDIRQS
:
2021 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
2023 if (!valid_state(curr
, this, new_bit
,
2024 LOCK_USED_IN_HARDIRQ_READ
))
2027 * just marked it hardirq-unsafe, check that no hardirq-safe
2028 * lock in the system ever took it in the past:
2030 if (!check_usage_backwards(curr
, this,
2031 LOCK_USED_IN_HARDIRQ
, "hard"))
2033 #if STRICT_READ_CHECKS
2035 * just marked it hardirq-unsafe, check that no
2036 * hardirq-safe-read lock in the system ever took
2039 if (!check_usage_backwards(curr
, this,
2040 LOCK_USED_IN_HARDIRQ_READ
, "hard-read"))
2043 if (hardirq_verbose(hlock_class(this)))
2046 case LOCK_ENABLED_SOFTIRQS
:
2047 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
2049 if (!valid_state(curr
, this, new_bit
,
2050 LOCK_USED_IN_SOFTIRQ_READ
))
2053 * just marked it softirq-unsafe, check that no softirq-safe
2054 * lock in the system ever took it in the past:
2056 if (!check_usage_backwards(curr
, this,
2057 LOCK_USED_IN_SOFTIRQ
, "soft"))
2059 #if STRICT_READ_CHECKS
2061 * just marked it softirq-unsafe, check that no
2062 * softirq-safe-read lock in the system ever took
2065 if (!check_usage_backwards(curr
, this,
2066 LOCK_USED_IN_SOFTIRQ_READ
, "soft-read"))
2069 if (softirq_verbose(hlock_class(this)))
2072 case LOCK_ENABLED_HARDIRQS_READ
:
2073 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
2075 #if STRICT_READ_CHECKS
2077 * just marked it hardirq-read-unsafe, check that no
2078 * hardirq-safe lock in the system ever took it in the past:
2080 if (!check_usage_backwards(curr
, this,
2081 LOCK_USED_IN_HARDIRQ
, "hard"))
2084 if (hardirq_verbose(hlock_class(this)))
2087 case LOCK_ENABLED_SOFTIRQS_READ
:
2088 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
2090 #if STRICT_READ_CHECKS
2092 * just marked it softirq-read-unsafe, check that no
2093 * softirq-safe lock in the system ever took it in the past:
2095 if (!check_usage_backwards(curr
, this,
2096 LOCK_USED_IN_SOFTIRQ
, "soft"))
2099 if (softirq_verbose(hlock_class(this)))
2111 * Mark all held locks with a usage bit:
2114 mark_held_locks(struct task_struct
*curr
, int hardirq
)
2116 enum lock_usage_bit usage_bit
;
2117 struct held_lock
*hlock
;
2120 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2121 hlock
= curr
->held_locks
+ i
;
2125 usage_bit
= LOCK_ENABLED_HARDIRQS_READ
;
2127 usage_bit
= LOCK_ENABLED_HARDIRQS
;
2130 usage_bit
= LOCK_ENABLED_SOFTIRQS_READ
;
2132 usage_bit
= LOCK_ENABLED_SOFTIRQS
;
2134 if (!mark_lock(curr
, hlock
, usage_bit
))
2142 * Debugging helper: via this flag we know that we are in
2143 * 'early bootup code', and will warn about any invalid irqs-on event:
2145 static int early_boot_irqs_enabled
;
2147 void early_boot_irqs_off(void)
2149 early_boot_irqs_enabled
= 0;
2152 void early_boot_irqs_on(void)
2154 early_boot_irqs_enabled
= 1;
2158 * Hardirqs will be enabled:
2160 void trace_hardirqs_on_caller(unsigned long a0
)
2162 struct task_struct
*curr
= current
;
2165 time_hardirqs_on(CALLER_ADDR0
, a0
);
2167 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2170 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
2173 if (unlikely(curr
->hardirqs_enabled
)) {
2174 debug_atomic_inc(&redundant_hardirqs_on
);
2177 /* we'll do an OFF -> ON transition: */
2178 curr
->hardirqs_enabled
= 1;
2179 ip
= (unsigned long) __builtin_return_address(0);
2181 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2183 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2186 * We are going to turn hardirqs on, so set the
2187 * usage bit for all held locks:
2189 if (!mark_held_locks(curr
, 1))
2192 * If we have softirqs enabled, then set the usage
2193 * bit for all held locks. (disabled hardirqs prevented
2194 * this bit from being set before)
2196 if (curr
->softirqs_enabled
)
2197 if (!mark_held_locks(curr
, 0))
2200 curr
->hardirq_enable_ip
= ip
;
2201 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2202 debug_atomic_inc(&hardirqs_on_events
);
2204 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2206 void trace_hardirqs_on(void)
2208 trace_hardirqs_on_caller(CALLER_ADDR0
);
2210 EXPORT_SYMBOL(trace_hardirqs_on
);
2213 * Hardirqs were disabled:
2215 void trace_hardirqs_off_caller(unsigned long a0
)
2217 struct task_struct
*curr
= current
;
2219 time_hardirqs_off(CALLER_ADDR0
, a0
);
2221 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2224 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2227 if (curr
->hardirqs_enabled
) {
2229 * We have done an ON -> OFF transition:
2231 curr
->hardirqs_enabled
= 0;
2232 curr
->hardirq_disable_ip
= _RET_IP_
;
2233 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2234 debug_atomic_inc(&hardirqs_off_events
);
2236 debug_atomic_inc(&redundant_hardirqs_off
);
2238 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2240 void trace_hardirqs_off(void)
2242 trace_hardirqs_off_caller(CALLER_ADDR0
);
2244 EXPORT_SYMBOL(trace_hardirqs_off
);
2247 * Softirqs will be enabled:
2249 void trace_softirqs_on(unsigned long ip
)
2251 struct task_struct
*curr
= current
;
2253 if (unlikely(!debug_locks
))
2256 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2259 if (curr
->softirqs_enabled
) {
2260 debug_atomic_inc(&redundant_softirqs_on
);
2265 * We'll do an OFF -> ON transition:
2267 curr
->softirqs_enabled
= 1;
2268 curr
->softirq_enable_ip
= ip
;
2269 curr
->softirq_enable_event
= ++curr
->irq_events
;
2270 debug_atomic_inc(&softirqs_on_events
);
2272 * We are going to turn softirqs on, so set the
2273 * usage bit for all held locks, if hardirqs are
2276 if (curr
->hardirqs_enabled
)
2277 mark_held_locks(curr
, 0);
2281 * Softirqs were disabled:
2283 void trace_softirqs_off(unsigned long ip
)
2285 struct task_struct
*curr
= current
;
2287 if (unlikely(!debug_locks
))
2290 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2293 if (curr
->softirqs_enabled
) {
2295 * We have done an ON -> OFF transition:
2297 curr
->softirqs_enabled
= 0;
2298 curr
->softirq_disable_ip
= ip
;
2299 curr
->softirq_disable_event
= ++curr
->irq_events
;
2300 debug_atomic_inc(&softirqs_off_events
);
2301 DEBUG_LOCKS_WARN_ON(!softirq_count());
2303 debug_atomic_inc(&redundant_softirqs_off
);
2306 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2309 * If non-trylock use in a hardirq or softirq context, then
2310 * mark the lock as used in these contexts:
2312 if (!hlock
->trylock
) {
2314 if (curr
->hardirq_context
)
2315 if (!mark_lock(curr
, hlock
,
2316 LOCK_USED_IN_HARDIRQ_READ
))
2318 if (curr
->softirq_context
)
2319 if (!mark_lock(curr
, hlock
,
2320 LOCK_USED_IN_SOFTIRQ_READ
))
2323 if (curr
->hardirq_context
)
2324 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2326 if (curr
->softirq_context
)
2327 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2331 if (!hlock
->hardirqs_off
) {
2333 if (!mark_lock(curr
, hlock
,
2334 LOCK_ENABLED_HARDIRQS_READ
))
2336 if (curr
->softirqs_enabled
)
2337 if (!mark_lock(curr
, hlock
,
2338 LOCK_ENABLED_SOFTIRQS_READ
))
2341 if (!mark_lock(curr
, hlock
,
2342 LOCK_ENABLED_HARDIRQS
))
2344 if (curr
->softirqs_enabled
)
2345 if (!mark_lock(curr
, hlock
,
2346 LOCK_ENABLED_SOFTIRQS
))
2354 static int separate_irq_context(struct task_struct
*curr
,
2355 struct held_lock
*hlock
)
2357 unsigned int depth
= curr
->lockdep_depth
;
2360 * Keep track of points where we cross into an interrupt context:
2362 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2363 curr
->softirq_context
;
2365 struct held_lock
*prev_hlock
;
2367 prev_hlock
= curr
->held_locks
+ depth
-1;
2369 * If we cross into another context, reset the
2370 * hash key (this also prevents the checking and the
2371 * adding of the dependency to 'prev'):
2373 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2382 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2383 enum lock_usage_bit new_bit
)
2389 static inline int mark_irqflags(struct task_struct
*curr
,
2390 struct held_lock
*hlock
)
2395 static inline int separate_irq_context(struct task_struct
*curr
,
2396 struct held_lock
*hlock
)
2404 * Mark a lock with a usage bit, and validate the state transition:
2406 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2407 enum lock_usage_bit new_bit
)
2409 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2412 * If already set then do not dirty the cacheline,
2413 * nor do any checks:
2415 if (likely(hlock_class(this)->usage_mask
& new_mask
))
2421 * Make sure we didnt race:
2423 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
2428 hlock_class(this)->usage_mask
|= new_mask
;
2430 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
2434 case LOCK_USED_IN_HARDIRQ
:
2435 case LOCK_USED_IN_SOFTIRQ
:
2436 case LOCK_USED_IN_HARDIRQ_READ
:
2437 case LOCK_USED_IN_SOFTIRQ_READ
:
2438 case LOCK_ENABLED_HARDIRQS
:
2439 case LOCK_ENABLED_SOFTIRQS
:
2440 case LOCK_ENABLED_HARDIRQS_READ
:
2441 case LOCK_ENABLED_SOFTIRQS_READ
:
2442 ret
= mark_lock_irq(curr
, this, new_bit
);
2447 debug_atomic_dec(&nr_unused_locks
);
2450 if (!debug_locks_off_graph_unlock())
2459 * We must printk outside of the graph_lock:
2462 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2464 print_irqtrace_events(curr
);
2472 * Initialize a lock instance's lock-class mapping info:
2474 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2475 struct lock_class_key
*key
, int subclass
)
2477 if (unlikely(!debug_locks
))
2480 if (DEBUG_LOCKS_WARN_ON(!key
))
2482 if (DEBUG_LOCKS_WARN_ON(!name
))
2485 * Sanity check, the lock-class key must be persistent:
2487 if (!static_obj(key
)) {
2488 printk("BUG: key %p not in .data!\n", key
);
2489 DEBUG_LOCKS_WARN_ON(1);
2494 lock
->class_cache
= NULL
;
2495 #ifdef CONFIG_LOCK_STAT
2496 lock
->cpu
= raw_smp_processor_id();
2499 register_lock_class(lock
, subclass
, 1);
2502 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2505 * This gets called for every mutex_lock*()/spin_lock*() operation.
2506 * We maintain the dependency maps and validate the locking attempt:
2508 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2509 int trylock
, int read
, int check
, int hardirqs_off
,
2512 struct task_struct
*curr
= current
;
2513 struct lock_class
*class = NULL
;
2514 struct held_lock
*hlock
;
2515 unsigned int depth
, id
;
2522 if (unlikely(!debug_locks
))
2525 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2528 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
2530 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2531 printk("turning off the locking correctness validator.\n");
2536 class = lock
->class_cache
;
2538 * Not cached yet or subclass?
2540 if (unlikely(!class)) {
2541 class = register_lock_class(lock
, subclass
, 0);
2545 debug_atomic_inc((atomic_t
*)&class->ops
);
2546 if (very_verbose(class)) {
2547 printk("\nacquire class [%p] %s", class->key
, class->name
);
2548 if (class->name_version
> 1)
2549 printk("#%d", class->name_version
);
2555 * Add the lock to the list of currently held locks.
2556 * (we dont increase the depth just yet, up until the
2557 * dependency checks are done)
2559 depth
= curr
->lockdep_depth
;
2560 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2563 hlock
= curr
->held_locks
+ depth
;
2564 if (DEBUG_LOCKS_WARN_ON(!class))
2566 hlock
->class_idx
= class - lock_classes
+ 1;
2567 hlock
->acquire_ip
= ip
;
2568 hlock
->instance
= lock
;
2569 hlock
->trylock
= trylock
;
2571 hlock
->check
= check
;
2572 hlock
->hardirqs_off
= hardirqs_off
;
2573 #ifdef CONFIG_LOCK_STAT
2574 hlock
->waittime_stamp
= 0;
2575 hlock
->holdtime_stamp
= sched_clock();
2578 if (check
== 2 && !mark_irqflags(curr
, hlock
))
2581 /* mark it as used: */
2582 if (!mark_lock(curr
, hlock
, LOCK_USED
))
2586 * Calculate the chain hash: it's the combined hash of all the
2587 * lock keys along the dependency chain. We save the hash value
2588 * at every step so that we can get the current hash easily
2589 * after unlock. The chain hash is then used to cache dependency
2592 * The 'key ID' is what is the most compact key value to drive
2593 * the hash, not class->key.
2595 id
= class - lock_classes
;
2596 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2599 chain_key
= curr
->curr_chain_key
;
2601 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2606 hlock
->prev_chain_key
= chain_key
;
2607 if (separate_irq_context(curr
, hlock
)) {
2611 chain_key
= iterate_chain_key(chain_key
, id
);
2613 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
2616 curr
->curr_chain_key
= chain_key
;
2617 curr
->lockdep_depth
++;
2618 check_chain_key(curr
);
2619 #ifdef CONFIG_DEBUG_LOCKDEP
2620 if (unlikely(!debug_locks
))
2623 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2625 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2626 printk("turning off the locking correctness validator.\n");
2630 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2631 max_lockdep_depth
= curr
->lockdep_depth
;
2637 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2640 if (!debug_locks_off())
2642 if (debug_locks_silent
)
2645 printk("\n=====================================\n");
2646 printk( "[ BUG: bad unlock balance detected! ]\n");
2647 printk( "-------------------------------------\n");
2648 printk("%s/%d is trying to release lock (",
2649 curr
->comm
, task_pid_nr(curr
));
2650 print_lockdep_cache(lock
);
2653 printk("but there are no more locks to release!\n");
2654 printk("\nother info that might help us debug this:\n");
2655 lockdep_print_held_locks(curr
);
2657 printk("\nstack backtrace:\n");
2664 * Common debugging checks for both nested and non-nested unlock:
2666 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2669 if (unlikely(!debug_locks
))
2671 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2674 if (curr
->lockdep_depth
<= 0)
2675 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2681 __lock_set_subclass(struct lockdep_map
*lock
,
2682 unsigned int subclass
, unsigned long ip
)
2684 struct task_struct
*curr
= current
;
2685 struct held_lock
*hlock
, *prev_hlock
;
2686 struct lock_class
*class;
2690 depth
= curr
->lockdep_depth
;
2691 if (DEBUG_LOCKS_WARN_ON(!depth
))
2695 for (i
= depth
-1; i
>= 0; i
--) {
2696 hlock
= curr
->held_locks
+ i
;
2698 * We must not cross into another context:
2700 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2702 if (hlock
->instance
== lock
)
2706 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2709 class = register_lock_class(lock
, subclass
, 0);
2710 hlock
->class_idx
= class - lock_classes
+ 1;
2712 curr
->lockdep_depth
= i
;
2713 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2715 for (; i
< depth
; i
++) {
2716 hlock
= curr
->held_locks
+ i
;
2717 if (!__lock_acquire(hlock
->instance
,
2718 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2719 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2724 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
2730 * Remove the lock to the list of currently held locks in a
2731 * potentially non-nested (out of order) manner. This is a
2732 * relatively rare operation, as all the unlock APIs default
2733 * to nested mode (which uses lock_release()):
2736 lock_release_non_nested(struct task_struct
*curr
,
2737 struct lockdep_map
*lock
, unsigned long ip
)
2739 struct held_lock
*hlock
, *prev_hlock
;
2744 * Check whether the lock exists in the current stack
2747 depth
= curr
->lockdep_depth
;
2748 if (DEBUG_LOCKS_WARN_ON(!depth
))
2752 for (i
= depth
-1; i
>= 0; i
--) {
2753 hlock
= curr
->held_locks
+ i
;
2755 * We must not cross into another context:
2757 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2759 if (hlock
->instance
== lock
)
2763 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2766 lock_release_holdtime(hlock
);
2769 * We have the right lock to unlock, 'hlock' points to it.
2770 * Now we remove it from the stack, and add back the other
2771 * entries (if any), recalculating the hash along the way:
2773 curr
->lockdep_depth
= i
;
2774 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2776 for (i
++; i
< depth
; i
++) {
2777 hlock
= curr
->held_locks
+ i
;
2778 if (!__lock_acquire(hlock
->instance
,
2779 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2780 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2785 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2791 * Remove the lock to the list of currently held locks - this gets
2792 * called on mutex_unlock()/spin_unlock*() (or on a failed
2793 * mutex_lock_interruptible()). This is done for unlocks that nest
2794 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2796 static int lock_release_nested(struct task_struct
*curr
,
2797 struct lockdep_map
*lock
, unsigned long ip
)
2799 struct held_lock
*hlock
;
2803 * Pop off the top of the lock stack:
2805 depth
= curr
->lockdep_depth
- 1;
2806 hlock
= curr
->held_locks
+ depth
;
2809 * Is the unlock non-nested:
2811 if (hlock
->instance
!= lock
)
2812 return lock_release_non_nested(curr
, lock
, ip
);
2813 curr
->lockdep_depth
--;
2815 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2818 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2820 lock_release_holdtime(hlock
);
2822 #ifdef CONFIG_DEBUG_LOCKDEP
2823 hlock
->prev_chain_key
= 0;
2824 hlock
->class_idx
= 0;
2825 hlock
->acquire_ip
= 0;
2826 hlock
->irq_context
= 0;
2832 * Remove the lock to the list of currently held locks - this gets
2833 * called on mutex_unlock()/spin_unlock*() (or on a failed
2834 * mutex_lock_interruptible()). This is done for unlocks that nest
2835 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2838 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2840 struct task_struct
*curr
= current
;
2842 if (!check_unlock(curr
, lock
, ip
))
2846 if (!lock_release_nested(curr
, lock
, ip
))
2849 if (!lock_release_non_nested(curr
, lock
, ip
))
2853 check_chain_key(curr
);
2857 * Check whether we follow the irq-flags state precisely:
2859 static void check_flags(unsigned long flags
)
2861 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2862 defined(CONFIG_TRACE_IRQFLAGS)
2866 if (irqs_disabled_flags(flags
)) {
2867 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
2868 printk("possible reason: unannotated irqs-off.\n");
2871 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
2872 printk("possible reason: unannotated irqs-on.\n");
2877 * We dont accurately track softirq state in e.g.
2878 * hardirq contexts (such as on 4KSTACKS), so only
2879 * check if not in hardirq contexts:
2881 if (!hardirq_count()) {
2882 if (softirq_count())
2883 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
2885 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
2889 print_irqtrace_events(current
);
2894 lock_set_subclass(struct lockdep_map
*lock
,
2895 unsigned int subclass
, unsigned long ip
)
2897 unsigned long flags
;
2899 if (unlikely(current
->lockdep_recursion
))
2902 raw_local_irq_save(flags
);
2903 current
->lockdep_recursion
= 1;
2905 if (__lock_set_subclass(lock
, subclass
, ip
))
2906 check_chain_key(current
);
2907 current
->lockdep_recursion
= 0;
2908 raw_local_irq_restore(flags
);
2911 EXPORT_SYMBOL_GPL(lock_set_subclass
);
2914 * We are not always called with irqs disabled - do that here,
2915 * and also avoid lockdep recursion:
2917 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2918 int trylock
, int read
, int check
, unsigned long ip
)
2920 unsigned long flags
;
2922 if (unlikely(!lock_stat
&& !prove_locking
))
2925 if (unlikely(current
->lockdep_recursion
))
2928 raw_local_irq_save(flags
);
2931 current
->lockdep_recursion
= 1;
2932 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
2933 irqs_disabled_flags(flags
), ip
);
2934 current
->lockdep_recursion
= 0;
2935 raw_local_irq_restore(flags
);
2938 EXPORT_SYMBOL_GPL(lock_acquire
);
2940 void lock_release(struct lockdep_map
*lock
, int nested
,
2943 unsigned long flags
;
2945 if (unlikely(!lock_stat
&& !prove_locking
))
2948 if (unlikely(current
->lockdep_recursion
))
2951 raw_local_irq_save(flags
);
2953 current
->lockdep_recursion
= 1;
2954 __lock_release(lock
, nested
, ip
);
2955 current
->lockdep_recursion
= 0;
2956 raw_local_irq_restore(flags
);
2959 EXPORT_SYMBOL_GPL(lock_release
);
2961 #ifdef CONFIG_LOCK_STAT
2963 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2966 if (!debug_locks_off())
2968 if (debug_locks_silent
)
2971 printk("\n=================================\n");
2972 printk( "[ BUG: bad contention detected! ]\n");
2973 printk( "---------------------------------\n");
2974 printk("%s/%d is trying to contend lock (",
2975 curr
->comm
, task_pid_nr(curr
));
2976 print_lockdep_cache(lock
);
2979 printk("but there are no locks held!\n");
2980 printk("\nother info that might help us debug this:\n");
2981 lockdep_print_held_locks(curr
);
2983 printk("\nstack backtrace:\n");
2990 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
2992 struct task_struct
*curr
= current
;
2993 struct held_lock
*hlock
, *prev_hlock
;
2994 struct lock_class_stats
*stats
;
2998 depth
= curr
->lockdep_depth
;
2999 if (DEBUG_LOCKS_WARN_ON(!depth
))
3003 for (i
= depth
-1; i
>= 0; i
--) {
3004 hlock
= curr
->held_locks
+ i
;
3006 * We must not cross into another context:
3008 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3010 if (hlock
->instance
== lock
)
3014 print_lock_contention_bug(curr
, lock
, ip
);
3018 hlock
->waittime_stamp
= sched_clock();
3020 point
= lock_contention_point(hlock_class(hlock
), ip
);
3022 stats
= get_lock_stats(hlock_class(hlock
));
3023 if (point
< ARRAY_SIZE(stats
->contention_point
))
3024 stats
->contention_point
[i
]++;
3025 if (lock
->cpu
!= smp_processor_id())
3026 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3027 put_lock_stats(stats
);
3031 __lock_acquired(struct lockdep_map
*lock
)
3033 struct task_struct
*curr
= current
;
3034 struct held_lock
*hlock
, *prev_hlock
;
3035 struct lock_class_stats
*stats
;
3041 depth
= curr
->lockdep_depth
;
3042 if (DEBUG_LOCKS_WARN_ON(!depth
))
3046 for (i
= depth
-1; i
>= 0; i
--) {
3047 hlock
= curr
->held_locks
+ i
;
3049 * We must not cross into another context:
3051 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3053 if (hlock
->instance
== lock
)
3057 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3061 cpu
= smp_processor_id();
3062 if (hlock
->waittime_stamp
) {
3063 now
= sched_clock();
3064 waittime
= now
- hlock
->waittime_stamp
;
3065 hlock
->holdtime_stamp
= now
;
3068 stats
= get_lock_stats(hlock_class(hlock
));
3071 lock_time_inc(&stats
->read_waittime
, waittime
);
3073 lock_time_inc(&stats
->write_waittime
, waittime
);
3075 if (lock
->cpu
!= cpu
)
3076 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3077 put_lock_stats(stats
);
3082 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3084 unsigned long flags
;
3086 if (unlikely(!lock_stat
))
3089 if (unlikely(current
->lockdep_recursion
))
3092 raw_local_irq_save(flags
);
3094 current
->lockdep_recursion
= 1;
3095 __lock_contended(lock
, ip
);
3096 current
->lockdep_recursion
= 0;
3097 raw_local_irq_restore(flags
);
3099 EXPORT_SYMBOL_GPL(lock_contended
);
3101 void lock_acquired(struct lockdep_map
*lock
)
3103 unsigned long flags
;
3105 if (unlikely(!lock_stat
))
3108 if (unlikely(current
->lockdep_recursion
))
3111 raw_local_irq_save(flags
);
3113 current
->lockdep_recursion
= 1;
3114 __lock_acquired(lock
);
3115 current
->lockdep_recursion
= 0;
3116 raw_local_irq_restore(flags
);
3118 EXPORT_SYMBOL_GPL(lock_acquired
);
3122 * Used by the testsuite, sanitize the validator state
3123 * after a simulated failure:
3126 void lockdep_reset(void)
3128 unsigned long flags
;
3131 raw_local_irq_save(flags
);
3132 current
->curr_chain_key
= 0;
3133 current
->lockdep_depth
= 0;
3134 current
->lockdep_recursion
= 0;
3135 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3136 nr_hardirq_chains
= 0;
3137 nr_softirq_chains
= 0;
3138 nr_process_chains
= 0;
3140 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3141 INIT_LIST_HEAD(chainhash_table
+ i
);
3142 raw_local_irq_restore(flags
);
3145 static void zap_class(struct lock_class
*class)
3150 * Remove all dependencies this lock is
3153 for (i
= 0; i
< nr_list_entries
; i
++) {
3154 if (list_entries
[i
].class == class)
3155 list_del_rcu(&list_entries
[i
].entry
);
3158 * Unhash the class and remove it from the all_lock_classes list:
3160 list_del_rcu(&class->hash_entry
);
3161 list_del_rcu(&class->lock_entry
);
3165 static inline int within(const void *addr
, void *start
, unsigned long size
)
3167 return addr
>= start
&& addr
< start
+ size
;
3170 void lockdep_free_key_range(void *start
, unsigned long size
)
3172 struct lock_class
*class, *next
;
3173 struct list_head
*head
;
3174 unsigned long flags
;
3178 raw_local_irq_save(flags
);
3179 locked
= graph_lock();
3182 * Unhash all classes that were created by this module:
3184 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3185 head
= classhash_table
+ i
;
3186 if (list_empty(head
))
3188 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3189 if (within(class->key
, start
, size
))
3191 else if (within(class->name
, start
, size
))
3198 raw_local_irq_restore(flags
);
3201 void lockdep_reset_lock(struct lockdep_map
*lock
)
3203 struct lock_class
*class, *next
;
3204 struct list_head
*head
;
3205 unsigned long flags
;
3209 raw_local_irq_save(flags
);
3212 * Remove all classes this lock might have:
3214 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3216 * If the class exists we look it up and zap it:
3218 class = look_up_lock_class(lock
, j
);
3223 * Debug check: in the end all mapped classes should
3226 locked
= graph_lock();
3227 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3228 head
= classhash_table
+ i
;
3229 if (list_empty(head
))
3231 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3232 if (unlikely(class == lock
->class_cache
)) {
3233 if (debug_locks_off_graph_unlock())
3243 raw_local_irq_restore(flags
);
3246 void lockdep_init(void)
3251 * Some architectures have their own start_kernel()
3252 * code which calls lockdep_init(), while we also
3253 * call lockdep_init() from the start_kernel() itself,
3254 * and we want to initialize the hashes only once:
3256 if (lockdep_initialized
)
3259 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3260 INIT_LIST_HEAD(classhash_table
+ i
);
3262 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3263 INIT_LIST_HEAD(chainhash_table
+ i
);
3265 lockdep_initialized
= 1;
3268 void __init
lockdep_info(void)
3270 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3272 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
3273 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
3274 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
3275 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
3276 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
3277 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
3278 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
3280 printk(" memory used by lock dependency info: %lu kB\n",
3281 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
3282 sizeof(struct list_head
) * CLASSHASH_SIZE
+
3283 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
3284 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
3285 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
3287 printk(" per task-struct memory footprint: %lu bytes\n",
3288 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
3290 #ifdef CONFIG_DEBUG_LOCKDEP
3291 if (lockdep_init_error
) {
3292 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3293 printk("Call stack leading to lockdep invocation was:\n");
3294 print_stack_trace(&lockdep_init_trace
, 0);
3300 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
3301 const void *mem_to
, struct held_lock
*hlock
)
3303 if (!debug_locks_off())
3305 if (debug_locks_silent
)
3308 printk("\n=========================\n");
3309 printk( "[ BUG: held lock freed! ]\n");
3310 printk( "-------------------------\n");
3311 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3312 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
3314 lockdep_print_held_locks(curr
);
3316 printk("\nstack backtrace:\n");
3320 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
3321 const void* lock_from
, unsigned long lock_len
)
3323 return lock_from
+ lock_len
<= mem_from
||
3324 mem_from
+ mem_len
<= lock_from
;
3328 * Called when kernel memory is freed (or unmapped), or if a lock
3329 * is destroyed or reinitialized - this code checks whether there is
3330 * any held lock in the memory range of <from> to <to>:
3332 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
3334 struct task_struct
*curr
= current
;
3335 struct held_lock
*hlock
;
3336 unsigned long flags
;
3339 if (unlikely(!debug_locks
))
3342 local_irq_save(flags
);
3343 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3344 hlock
= curr
->held_locks
+ i
;
3346 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
3347 sizeof(*hlock
->instance
)))
3350 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
3353 local_irq_restore(flags
);
3355 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
3357 static void print_held_locks_bug(struct task_struct
*curr
)
3359 if (!debug_locks_off())
3361 if (debug_locks_silent
)
3364 printk("\n=====================================\n");
3365 printk( "[ BUG: lock held at task exit time! ]\n");
3366 printk( "-------------------------------------\n");
3367 printk("%s/%d is exiting with locks still held!\n",
3368 curr
->comm
, task_pid_nr(curr
));
3369 lockdep_print_held_locks(curr
);
3371 printk("\nstack backtrace:\n");
3375 void debug_check_no_locks_held(struct task_struct
*task
)
3377 if (unlikely(task
->lockdep_depth
> 0))
3378 print_held_locks_bug(task
);
3381 void debug_show_all_locks(void)
3383 struct task_struct
*g
, *p
;
3387 if (unlikely(!debug_locks
)) {
3388 printk("INFO: lockdep is turned off.\n");
3391 printk("\nShowing all locks held in the system:\n");
3394 * Here we try to get the tasklist_lock as hard as possible,
3395 * if not successful after 2 seconds we ignore it (but keep
3396 * trying). This is to enable a debug printout even if a
3397 * tasklist_lock-holding task deadlocks or crashes.
3400 if (!read_trylock(&tasklist_lock
)) {
3402 printk("hm, tasklist_lock locked, retrying... ");
3405 printk(" #%d", 10-count
);
3409 printk(" ignoring it.\n");
3413 printk(" locked it.\n");
3415 do_each_thread(g
, p
) {
3417 * It's not reliable to print a task's held locks
3418 * if it's not sleeping (or if it's not the current
3421 if (p
->state
== TASK_RUNNING
&& p
!= current
)
3423 if (p
->lockdep_depth
)
3424 lockdep_print_held_locks(p
);
3426 if (read_trylock(&tasklist_lock
))
3428 } while_each_thread(g
, p
);
3431 printk("=============================================\n\n");
3434 read_unlock(&tasklist_lock
);
3437 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
3440 * Careful: only use this function if you are sure that
3441 * the task cannot run in parallel!
3443 void __debug_show_held_locks(struct task_struct
*task
)
3445 if (unlikely(!debug_locks
)) {
3446 printk("INFO: lockdep is turned off.\n");
3449 lockdep_print_held_locks(task
);
3451 EXPORT_SYMBOL_GPL(__debug_show_held_locks
);
3453 void debug_show_held_locks(struct task_struct
*task
)
3455 __debug_show_held_locks(task
);
3458 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
3460 void lockdep_sys_exit(void)
3462 struct task_struct
*curr
= current
;
3464 if (unlikely(curr
->lockdep_depth
)) {
3465 if (!debug_locks_off())
3467 printk("\n================================================\n");
3468 printk( "[ BUG: lock held when returning to user space! ]\n");
3469 printk( "------------------------------------------------\n");
3470 printk("%s/%d is leaving the kernel with locks still held!\n",
3471 curr
->comm
, curr
->pid
);
3472 lockdep_print_held_locks(curr
);