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_point(unsigned long points
[], unsigned long ip
)
143 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
144 if (points
[i
] == 0) {
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 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
189 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
191 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
192 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
194 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
195 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
197 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
198 stats
.bounces
[i
] += pcs
->bounces
[i
];
204 void clear_lock_stats(struct lock_class
*class)
208 for_each_possible_cpu(cpu
) {
209 struct lock_class_stats
*cpu_stats
=
210 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
212 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
214 memset(class->contention_point
, 0, sizeof(class->contention_point
));
215 memset(class->contending_point
, 0, sizeof(class->contending_point
));
218 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
220 return &get_cpu_var(lock_stats
)[class - lock_classes
];
223 static void put_lock_stats(struct lock_class_stats
*stats
)
225 put_cpu_var(lock_stats
);
228 static void lock_release_holdtime(struct held_lock
*hlock
)
230 struct lock_class_stats
*stats
;
236 holdtime
= sched_clock() - hlock
->holdtime_stamp
;
238 stats
= get_lock_stats(hlock_class(hlock
));
240 lock_time_inc(&stats
->read_holdtime
, holdtime
);
242 lock_time_inc(&stats
->write_holdtime
, holdtime
);
243 put_lock_stats(stats
);
246 static inline void lock_release_holdtime(struct held_lock
*hlock
)
252 * We keep a global list of all lock classes. The list only grows,
253 * never shrinks. The list is only accessed with the lockdep
254 * spinlock lock held.
256 LIST_HEAD(all_lock_classes
);
259 * The lockdep classes are in a hash-table as well, for fast lookup:
261 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
262 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
263 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
264 #define classhashentry(key) (classhash_table + __classhashfn((key)))
266 static struct list_head classhash_table
[CLASSHASH_SIZE
];
269 * We put the lock dependency chains into a hash-table as well, to cache
272 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
273 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
274 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
275 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
277 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
280 * The hash key of the lock dependency chains is a hash itself too:
281 * it's a hash of all locks taken up to that lock, including that lock.
282 * It's a 64-bit hash, because it's important for the keys to be
285 #define iterate_chain_key(key1, key2) \
286 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
287 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
290 void lockdep_off(void)
292 current
->lockdep_recursion
++;
294 EXPORT_SYMBOL(lockdep_off
);
296 void lockdep_on(void)
298 current
->lockdep_recursion
--;
300 EXPORT_SYMBOL(lockdep_on
);
303 * Debugging switches:
307 #define VERY_VERBOSE 0
310 # define HARDIRQ_VERBOSE 1
311 # define SOFTIRQ_VERBOSE 1
313 # define HARDIRQ_VERBOSE 0
314 # define SOFTIRQ_VERBOSE 0
317 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
319 * Quick filtering for interesting events:
321 static int class_filter(struct lock_class
*class)
325 if (class->name_version
== 1 &&
326 !strcmp(class->name
, "lockname"))
328 if (class->name_version
== 1 &&
329 !strcmp(class->name
, "&struct->lockfield"))
332 /* Filter everything else. 1 would be to allow everything else */
337 static int verbose(struct lock_class
*class)
340 return class_filter(class);
346 * Stack-trace: tightly packed array of stack backtrace
347 * addresses. Protected by the graph_lock.
349 unsigned long nr_stack_trace_entries
;
350 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
352 static int save_trace(struct stack_trace
*trace
)
354 trace
->nr_entries
= 0;
355 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
356 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
360 save_stack_trace(trace
);
362 trace
->max_entries
= trace
->nr_entries
;
364 nr_stack_trace_entries
+= trace
->nr_entries
;
366 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
367 if (!debug_locks_off_graph_unlock())
370 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
371 printk("turning off the locking correctness validator.\n");
380 unsigned int nr_hardirq_chains
;
381 unsigned int nr_softirq_chains
;
382 unsigned int nr_process_chains
;
383 unsigned int max_lockdep_depth
;
384 unsigned int max_recursion_depth
;
386 static unsigned int lockdep_dependency_gen_id
;
388 static bool lockdep_dependency_visit(struct lock_class
*source
,
392 lockdep_dependency_gen_id
++;
393 if (source
->dep_gen_id
== lockdep_dependency_gen_id
)
395 source
->dep_gen_id
= lockdep_dependency_gen_id
;
399 #ifdef CONFIG_DEBUG_LOCKDEP
401 * We cannot printk in early bootup code. Not even early_printk()
402 * might work. So we mark any initialization errors and printk
403 * about it later on, in lockdep_info().
405 static int lockdep_init_error
;
406 static unsigned long lockdep_init_trace_data
[20];
407 static struct stack_trace lockdep_init_trace
= {
408 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
409 .entries
= lockdep_init_trace_data
,
413 * Various lockdep statistics:
415 atomic_t chain_lookup_hits
;
416 atomic_t chain_lookup_misses
;
417 atomic_t hardirqs_on_events
;
418 atomic_t hardirqs_off_events
;
419 atomic_t redundant_hardirqs_on
;
420 atomic_t redundant_hardirqs_off
;
421 atomic_t softirqs_on_events
;
422 atomic_t softirqs_off_events
;
423 atomic_t redundant_softirqs_on
;
424 atomic_t redundant_softirqs_off
;
425 atomic_t nr_unused_locks
;
426 atomic_t nr_cyclic_checks
;
427 atomic_t nr_cyclic_check_recursions
;
428 atomic_t nr_find_usage_forwards_checks
;
429 atomic_t nr_find_usage_forwards_recursions
;
430 atomic_t nr_find_usage_backwards_checks
;
431 atomic_t nr_find_usage_backwards_recursions
;
432 # define debug_atomic_inc(ptr) atomic_inc(ptr)
433 # define debug_atomic_dec(ptr) atomic_dec(ptr)
434 # define debug_atomic_read(ptr) atomic_read(ptr)
436 # define debug_atomic_inc(ptr) do { } while (0)
437 # define debug_atomic_dec(ptr) do { } while (0)
438 # define debug_atomic_read(ptr) 0
445 static const char *usage_str
[] =
447 [LOCK_USED
] = "initial-use ",
448 [LOCK_USED_IN_HARDIRQ
] = "in-hardirq-W",
449 [LOCK_USED_IN_SOFTIRQ
] = "in-softirq-W",
450 [LOCK_ENABLED_SOFTIRQS
] = "softirq-on-W",
451 [LOCK_ENABLED_HARDIRQS
] = "hardirq-on-W",
452 [LOCK_USED_IN_HARDIRQ_READ
] = "in-hardirq-R",
453 [LOCK_USED_IN_SOFTIRQ_READ
] = "in-softirq-R",
454 [LOCK_ENABLED_SOFTIRQS_READ
] = "softirq-on-R",
455 [LOCK_ENABLED_HARDIRQS_READ
] = "hardirq-on-R",
458 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
460 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
464 get_usage_chars(struct lock_class
*class, char *c1
, char *c2
, char *c3
, char *c4
)
466 *c1
= '.', *c2
= '.', *c3
= '.', *c4
= '.';
468 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ
)
471 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS
)
474 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ
)
477 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS
)
480 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
482 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ_READ
) {
484 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
488 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
490 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ_READ
) {
492 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
497 static void print_lock_name(struct lock_class
*class)
499 char str
[KSYM_NAME_LEN
], c1
, c2
, c3
, c4
;
502 get_usage_chars(class, &c1
, &c2
, &c3
, &c4
);
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("){%c%c%c%c}", c1
, c2
, c3
, c4
);
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");
800 class = lock_classes
+ nr_lock_classes
++;
801 debug_atomic_inc(&nr_unused_locks
);
803 class->name
= lock
->name
;
804 class->subclass
= subclass
;
805 INIT_LIST_HEAD(&class->lock_entry
);
806 INIT_LIST_HEAD(&class->locks_before
);
807 INIT_LIST_HEAD(&class->locks_after
);
808 class->name_version
= count_matching_names(class);
810 * We use RCU's safe list-add method to make
811 * parallel walking of the hash-list safe:
813 list_add_tail_rcu(&class->hash_entry
, hash_head
);
815 * Add it to the global list of classes:
817 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
819 if (verbose(class)) {
821 raw_local_irq_restore(flags
);
823 printk("\nnew class %p: %s", class->key
, class->name
);
824 if (class->name_version
> 1)
825 printk("#%d", class->name_version
);
829 raw_local_irq_save(flags
);
831 raw_local_irq_restore(flags
);
837 raw_local_irq_restore(flags
);
839 if (!subclass
|| force
)
840 lock
->class_cache
= class;
842 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
848 #ifdef CONFIG_PROVE_LOCKING
850 * Allocate a lockdep entry. (assumes the graph_lock held, returns
851 * with NULL on failure)
853 static struct lock_list
*alloc_list_entry(void)
855 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
856 if (!debug_locks_off_graph_unlock())
859 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
860 printk("turning off the locking correctness validator.\n");
863 return list_entries
+ nr_list_entries
++;
867 * Add a new dependency to the head of the list:
869 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
870 struct list_head
*head
, unsigned long ip
, int distance
)
872 struct lock_list
*entry
;
874 * Lock not present yet - get a new dependency struct and
875 * add it to the list:
877 entry
= alloc_list_entry();
881 if (!save_trace(&entry
->trace
))
885 entry
->distance
= distance
;
887 * Since we never remove from the dependency list, the list can
888 * be walked lockless by other CPUs, it's only allocation
889 * that must be protected by the spinlock. But this also means
890 * we must make new entries visible only once writes to the
891 * entry become visible - hence the RCU op:
893 list_add_tail_rcu(&entry
->entry
, head
);
899 * Recursive, forwards-direction lock-dependency checking, used for
900 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
903 * (to keep the stackframe of the recursive functions small we
904 * use these global variables, and we also mark various helper
905 * functions as noinline.)
907 static struct held_lock
*check_source
, *check_target
;
910 * Print a dependency chain entry (this is only done when a deadlock
911 * has been detected):
914 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
916 if (debug_locks_silent
)
918 printk("\n-> #%u", depth
);
919 print_lock_name(target
->class);
921 print_stack_trace(&target
->trace
, 6);
927 * When a circular dependency is detected, print the
931 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
)
933 struct task_struct
*curr
= current
;
935 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
938 printk("\n=======================================================\n");
939 printk( "[ INFO: possible circular locking dependency detected ]\n");
940 print_kernel_version();
941 printk( "-------------------------------------------------------\n");
942 printk("%s/%d is trying to acquire lock:\n",
943 curr
->comm
, task_pid_nr(curr
));
944 print_lock(check_source
);
945 printk("\nbut task is already holding lock:\n");
946 print_lock(check_target
);
947 printk("\nwhich lock already depends on the new lock.\n\n");
948 printk("\nthe existing dependency chain (in reverse order) is:\n");
950 print_circular_bug_entry(entry
, depth
);
955 static noinline
int print_circular_bug_tail(void)
957 struct task_struct
*curr
= current
;
958 struct lock_list
this;
960 if (debug_locks_silent
)
963 this.class = hlock_class(check_source
);
964 if (!save_trace(&this.trace
))
967 print_circular_bug_entry(&this, 0);
969 printk("\nother info that might help us debug this:\n\n");
970 lockdep_print_held_locks(curr
);
972 printk("\nstack backtrace:\n");
978 #define RECURSION_LIMIT 40
980 static int noinline
print_infinite_recursion_bug(void)
982 if (!debug_locks_off_graph_unlock())
990 unsigned long __lockdep_count_forward_deps(struct lock_class
*class,
993 struct lock_list
*entry
;
994 unsigned long ret
= 1;
996 if (lockdep_dependency_visit(class, depth
))
1000 * Recurse this class's dependency list:
1002 list_for_each_entry(entry
, &class->locks_after
, entry
)
1003 ret
+= __lockdep_count_forward_deps(entry
->class, depth
+ 1);
1008 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1010 unsigned long ret
, flags
;
1012 local_irq_save(flags
);
1013 __raw_spin_lock(&lockdep_lock
);
1014 ret
= __lockdep_count_forward_deps(class, 0);
1015 __raw_spin_unlock(&lockdep_lock
);
1016 local_irq_restore(flags
);
1021 unsigned long __lockdep_count_backward_deps(struct lock_class
*class,
1024 struct lock_list
*entry
;
1025 unsigned long ret
= 1;
1027 if (lockdep_dependency_visit(class, depth
))
1030 * Recurse this class's dependency list:
1032 list_for_each_entry(entry
, &class->locks_before
, entry
)
1033 ret
+= __lockdep_count_backward_deps(entry
->class, depth
+ 1);
1038 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1040 unsigned long ret
, flags
;
1042 local_irq_save(flags
);
1043 __raw_spin_lock(&lockdep_lock
);
1044 ret
= __lockdep_count_backward_deps(class, 0);
1045 __raw_spin_unlock(&lockdep_lock
);
1046 local_irq_restore(flags
);
1052 * Prove that the dependency graph starting at <entry> can not
1053 * lead to <target>. Print an error and return 0 if it does.
1056 check_noncircular(struct lock_class
*source
, unsigned int depth
)
1058 struct lock_list
*entry
;
1060 if (lockdep_dependency_visit(source
, depth
))
1063 debug_atomic_inc(&nr_cyclic_check_recursions
);
1064 if (depth
> max_recursion_depth
)
1065 max_recursion_depth
= depth
;
1066 if (depth
>= RECURSION_LIMIT
)
1067 return print_infinite_recursion_bug();
1069 * Check this lock's dependency list:
1071 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1072 if (entry
->class == hlock_class(check_target
))
1073 return print_circular_bug_header(entry
, depth
+1);
1074 debug_atomic_inc(&nr_cyclic_checks
);
1075 if (!check_noncircular(entry
->class, depth
+1))
1076 return print_circular_bug_entry(entry
, depth
+1);
1081 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1083 * Forwards and backwards subgraph searching, for the purposes of
1084 * proving that two subgraphs can be connected by a new dependency
1085 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1087 static enum lock_usage_bit find_usage_bit
;
1088 static struct lock_class
*forwards_match
, *backwards_match
;
1091 * Find a node in the forwards-direction dependency sub-graph starting
1092 * at <source> that matches <find_usage_bit>.
1094 * Return 2 if such a node exists in the subgraph, and put that node
1095 * into <forwards_match>.
1097 * Return 1 otherwise and keep <forwards_match> unchanged.
1098 * Return 0 on error.
1101 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
1103 struct lock_list
*entry
;
1106 if (lockdep_dependency_visit(source
, depth
))
1109 if (depth
> max_recursion_depth
)
1110 max_recursion_depth
= depth
;
1111 if (depth
>= RECURSION_LIMIT
)
1112 return print_infinite_recursion_bug();
1114 debug_atomic_inc(&nr_find_usage_forwards_checks
);
1115 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1116 forwards_match
= source
;
1121 * Check this lock's dependency list:
1123 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1124 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
1125 ret
= find_usage_forwards(entry
->class, depth
+1);
1126 if (ret
== 2 || ret
== 0)
1133 * Find a node in the backwards-direction dependency sub-graph starting
1134 * at <source> that matches <find_usage_bit>.
1136 * Return 2 if such a node exists in the subgraph, and put that node
1137 * into <backwards_match>.
1139 * Return 1 otherwise and keep <backwards_match> unchanged.
1140 * Return 0 on error.
1143 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
1145 struct lock_list
*entry
;
1148 if (lockdep_dependency_visit(source
, depth
))
1151 if (!__raw_spin_is_locked(&lockdep_lock
))
1152 return DEBUG_LOCKS_WARN_ON(1);
1154 if (depth
> max_recursion_depth
)
1155 max_recursion_depth
= depth
;
1156 if (depth
>= RECURSION_LIMIT
)
1157 return print_infinite_recursion_bug();
1159 debug_atomic_inc(&nr_find_usage_backwards_checks
);
1160 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1161 backwards_match
= source
;
1165 if (!source
&& debug_locks_off_graph_unlock()) {
1171 * Check this lock's dependency list:
1173 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
1174 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
1175 ret
= find_usage_backwards(entry
->class, depth
+1);
1176 if (ret
== 2 || ret
== 0)
1183 print_bad_irq_dependency(struct task_struct
*curr
,
1184 struct held_lock
*prev
,
1185 struct held_lock
*next
,
1186 enum lock_usage_bit bit1
,
1187 enum lock_usage_bit bit2
,
1188 const char *irqclass
)
1190 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1193 printk("\n======================================================\n");
1194 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1195 irqclass
, irqclass
);
1196 print_kernel_version();
1197 printk( "------------------------------------------------------\n");
1198 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1199 curr
->comm
, task_pid_nr(curr
),
1200 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1201 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1202 curr
->hardirqs_enabled
,
1203 curr
->softirqs_enabled
);
1206 printk("\nand this task is already holding:\n");
1208 printk("which would create a new lock dependency:\n");
1209 print_lock_name(hlock_class(prev
));
1211 print_lock_name(hlock_class(next
));
1214 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1216 print_lock_name(backwards_match
);
1217 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1219 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
1221 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1222 print_lock_name(forwards_match
);
1223 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1226 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
1228 printk("\nother info that might help us debug this:\n\n");
1229 lockdep_print_held_locks(curr
);
1231 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
1232 print_lock_dependencies(backwards_match
, 0);
1234 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
1235 print_lock_dependencies(forwards_match
, 0);
1237 printk("\nstack backtrace:\n");
1244 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1245 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1246 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1250 find_usage_bit
= bit_backwards
;
1251 /* fills in <backwards_match> */
1252 ret
= find_usage_backwards(hlock_class(prev
), 0);
1253 if (!ret
|| ret
== 1)
1256 find_usage_bit
= bit_forwards
;
1257 ret
= find_usage_forwards(hlock_class(next
), 0);
1258 if (!ret
|| ret
== 1)
1261 return print_bad_irq_dependency(curr
, prev
, next
,
1262 bit_backwards
, bit_forwards
, irqclass
);
1266 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1267 struct held_lock
*next
)
1270 * Prove that the new dependency does not connect a hardirq-safe
1271 * lock with a hardirq-unsafe lock - to achieve this we search
1272 * the backwards-subgraph starting at <prev>, and the
1273 * forwards-subgraph starting at <next>:
1275 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ
,
1276 LOCK_ENABLED_HARDIRQS
, "hard"))
1280 * Prove that the new dependency does not connect a hardirq-safe-read
1281 * lock with a hardirq-unsafe lock - to achieve this we search
1282 * the backwards-subgraph starting at <prev>, and the
1283 * forwards-subgraph starting at <next>:
1285 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ_READ
,
1286 LOCK_ENABLED_HARDIRQS
, "hard-read"))
1290 * Prove that the new dependency does not connect a softirq-safe
1291 * lock with a softirq-unsafe lock - to achieve this we search
1292 * the backwards-subgraph starting at <prev>, and the
1293 * forwards-subgraph starting at <next>:
1295 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ
,
1296 LOCK_ENABLED_SOFTIRQS
, "soft"))
1299 * Prove that the new dependency does not connect a softirq-safe-read
1300 * lock with a softirq-unsafe lock - to achieve this we search
1301 * the backwards-subgraph starting at <prev>, and the
1302 * forwards-subgraph starting at <next>:
1304 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ_READ
,
1305 LOCK_ENABLED_SOFTIRQS
, "soft"))
1311 static void inc_chains(void)
1313 if (current
->hardirq_context
)
1314 nr_hardirq_chains
++;
1316 if (current
->softirq_context
)
1317 nr_softirq_chains
++;
1319 nr_process_chains
++;
1326 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1327 struct held_lock
*next
)
1332 static inline void inc_chains(void)
1334 nr_process_chains
++;
1340 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1341 struct held_lock
*next
)
1343 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1346 printk("\n=============================================\n");
1347 printk( "[ INFO: possible recursive locking detected ]\n");
1348 print_kernel_version();
1349 printk( "---------------------------------------------\n");
1350 printk("%s/%d is trying to acquire lock:\n",
1351 curr
->comm
, task_pid_nr(curr
));
1353 printk("\nbut task is already holding lock:\n");
1356 printk("\nother info that might help us debug this:\n");
1357 lockdep_print_held_locks(curr
);
1359 printk("\nstack backtrace:\n");
1366 * Check whether we are holding such a class already.
1368 * (Note that this has to be done separately, because the graph cannot
1369 * detect such classes of deadlocks.)
1371 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1374 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1375 struct lockdep_map
*next_instance
, int read
)
1377 struct held_lock
*prev
;
1378 struct held_lock
*nest
= NULL
;
1381 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1382 prev
= curr
->held_locks
+ i
;
1384 if (prev
->instance
== next
->nest_lock
)
1387 if (hlock_class(prev
) != hlock_class(next
))
1391 * Allow read-after-read recursion of the same
1392 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1394 if ((read
== 2) && prev
->read
)
1398 * We're holding the nest_lock, which serializes this lock's
1399 * nesting behaviour.
1404 return print_deadlock_bug(curr
, prev
, next
);
1410 * There was a chain-cache miss, and we are about to add a new dependency
1411 * to a previous lock. We recursively validate the following rules:
1413 * - would the adding of the <prev> -> <next> dependency create a
1414 * circular dependency in the graph? [== circular deadlock]
1416 * - does the new prev->next dependency connect any hardirq-safe lock
1417 * (in the full backwards-subgraph starting at <prev>) with any
1418 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1419 * <next>)? [== illegal lock inversion with hardirq contexts]
1421 * - does the new prev->next dependency connect any softirq-safe lock
1422 * (in the full backwards-subgraph starting at <prev>) with any
1423 * softirq-unsafe lock (in the full forwards-subgraph starting at
1424 * <next>)? [== illegal lock inversion with softirq contexts]
1426 * any of these scenarios could lead to a deadlock.
1428 * Then if all the validations pass, we add the forwards and backwards
1432 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1433 struct held_lock
*next
, int distance
)
1435 struct lock_list
*entry
;
1439 * Prove that the new <prev> -> <next> dependency would not
1440 * create a circular dependency in the graph. (We do this by
1441 * forward-recursing into the graph starting at <next>, and
1442 * checking whether we can reach <prev>.)
1444 * We are using global variables to control the recursion, to
1445 * keep the stackframe size of the recursive functions low:
1447 check_source
= next
;
1448 check_target
= prev
;
1449 if (!(check_noncircular(hlock_class(next
), 0)))
1450 return print_circular_bug_tail();
1452 if (!check_prev_add_irq(curr
, prev
, next
))
1456 * For recursive read-locks we do all the dependency checks,
1457 * but we dont store read-triggered dependencies (only
1458 * write-triggered dependencies). This ensures that only the
1459 * write-side dependencies matter, and that if for example a
1460 * write-lock never takes any other locks, then the reads are
1461 * equivalent to a NOP.
1463 if (next
->read
== 2 || prev
->read
== 2)
1466 * Is the <prev> -> <next> dependency already present?
1468 * (this may occur even though this is a new chain: consider
1469 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1470 * chains - the second one will be new, but L1 already has
1471 * L2 added to its dependency list, due to the first chain.)
1473 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1474 if (entry
->class == hlock_class(next
)) {
1476 entry
->distance
= 1;
1482 * Ok, all validations passed, add the new lock
1483 * to the previous lock's dependency list:
1485 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1486 &hlock_class(prev
)->locks_after
,
1487 next
->acquire_ip
, distance
);
1492 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1493 &hlock_class(next
)->locks_before
,
1494 next
->acquire_ip
, distance
);
1499 * Debugging printouts:
1501 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1503 printk("\n new dependency: ");
1504 print_lock_name(hlock_class(prev
));
1506 print_lock_name(hlock_class(next
));
1509 return graph_lock();
1515 * Add the dependency to all directly-previous locks that are 'relevant'.
1516 * The ones that are relevant are (in increasing distance from curr):
1517 * all consecutive trylock entries and the final non-trylock entry - or
1518 * the end of this context's lock-chain - whichever comes first.
1521 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1523 int depth
= curr
->lockdep_depth
;
1524 struct held_lock
*hlock
;
1529 * Depth must not be zero for a non-head lock:
1534 * At least two relevant locks must exist for this
1537 if (curr
->held_locks
[depth
].irq_context
!=
1538 curr
->held_locks
[depth
-1].irq_context
)
1542 int distance
= curr
->lockdep_depth
- depth
+ 1;
1543 hlock
= curr
->held_locks
+ depth
-1;
1545 * Only non-recursive-read entries get new dependencies
1548 if (hlock
->read
!= 2) {
1549 if (!check_prev_add(curr
, hlock
, next
, distance
))
1552 * Stop after the first non-trylock entry,
1553 * as non-trylock entries have added their
1554 * own direct dependencies already, so this
1555 * lock is connected to them indirectly:
1557 if (!hlock
->trylock
)
1562 * End of lock-stack?
1567 * Stop the search if we cross into another context:
1569 if (curr
->held_locks
[depth
].irq_context
!=
1570 curr
->held_locks
[depth
-1].irq_context
)
1575 if (!debug_locks_off_graph_unlock())
1583 unsigned long nr_lock_chains
;
1584 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1585 int nr_chain_hlocks
;
1586 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1588 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1590 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1594 * Look up a dependency chain. If the key is not present yet then
1595 * add it and return 1 - in this case the new dependency chain is
1596 * validated. If the key is already hashed, return 0.
1597 * (On return with 1 graph_lock is held.)
1599 static inline int lookup_chain_cache(struct task_struct
*curr
,
1600 struct held_lock
*hlock
,
1603 struct lock_class
*class = hlock_class(hlock
);
1604 struct list_head
*hash_head
= chainhashentry(chain_key
);
1605 struct lock_chain
*chain
;
1606 struct held_lock
*hlock_curr
, *hlock_next
;
1609 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1612 * We can walk it lock-free, because entries only get added
1615 list_for_each_entry(chain
, hash_head
, entry
) {
1616 if (chain
->chain_key
== chain_key
) {
1618 debug_atomic_inc(&chain_lookup_hits
);
1619 if (very_verbose(class))
1620 printk("\nhash chain already cached, key: "
1621 "%016Lx tail class: [%p] %s\n",
1622 (unsigned long long)chain_key
,
1623 class->key
, class->name
);
1627 if (very_verbose(class))
1628 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1629 (unsigned long long)chain_key
, class->key
, class->name
);
1631 * Allocate a new chain entry from the static array, and add
1637 * We have to walk the chain again locked - to avoid duplicates:
1639 list_for_each_entry(chain
, hash_head
, entry
) {
1640 if (chain
->chain_key
== chain_key
) {
1645 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1646 if (!debug_locks_off_graph_unlock())
1649 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1650 printk("turning off the locking correctness validator.\n");
1653 chain
= lock_chains
+ nr_lock_chains
++;
1654 chain
->chain_key
= chain_key
;
1655 chain
->irq_context
= hlock
->irq_context
;
1656 /* Find the first held_lock of current chain */
1658 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
1659 hlock_curr
= curr
->held_locks
+ i
;
1660 if (hlock_curr
->irq_context
!= hlock_next
->irq_context
)
1665 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
1666 cn
= nr_chain_hlocks
;
1667 while (cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
) {
1668 n
= cmpxchg(&nr_chain_hlocks
, cn
, cn
+ chain
->depth
);
1673 if (likely(cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
1675 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
1676 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
1677 chain_hlocks
[chain
->base
+ j
] = lock_id
;
1679 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
1681 list_add_tail_rcu(&chain
->entry
, hash_head
);
1682 debug_atomic_inc(&chain_lookup_misses
);
1688 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
1689 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
1692 * Trylock needs to maintain the stack of held locks, but it
1693 * does not add new dependencies, because trylock can be done
1696 * We look up the chain_key and do the O(N^2) check and update of
1697 * the dependencies only if this is a new dependency chain.
1698 * (If lookup_chain_cache() returns with 1 it acquires
1699 * graph_lock for us)
1701 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
1702 lookup_chain_cache(curr
, hlock
, chain_key
)) {
1704 * Check whether last held lock:
1706 * - is irq-safe, if this lock is irq-unsafe
1707 * - is softirq-safe, if this lock is hardirq-unsafe
1709 * And check whether the new lock's dependency graph
1710 * could lead back to the previous lock.
1712 * any of these scenarios could lead to a deadlock. If
1715 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
1720 * Mark recursive read, as we jump over it when
1721 * building dependencies (just like we jump over
1727 * Add dependency only if this lock is not the head
1728 * of the chain, and if it's not a secondary read-lock:
1730 if (!chain_head
&& ret
!= 2)
1731 if (!check_prevs_add(curr
, hlock
))
1735 /* after lookup_chain_cache(): */
1736 if (unlikely(!debug_locks
))
1742 static inline int validate_chain(struct task_struct
*curr
,
1743 struct lockdep_map
*lock
, struct held_lock
*hlock
,
1744 int chain_head
, u64 chain_key
)
1751 * We are building curr_chain_key incrementally, so double-check
1752 * it from scratch, to make sure that it's done correctly:
1754 static void check_chain_key(struct task_struct
*curr
)
1756 #ifdef CONFIG_DEBUG_LOCKDEP
1757 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1761 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1762 hlock
= curr
->held_locks
+ i
;
1763 if (chain_key
!= hlock
->prev_chain_key
) {
1765 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1766 curr
->lockdep_depth
, i
,
1767 (unsigned long long)chain_key
,
1768 (unsigned long long)hlock
->prev_chain_key
);
1771 id
= hlock
->class_idx
- 1;
1772 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
1775 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1776 hlock
->irq_context
))
1778 chain_key
= iterate_chain_key(chain_key
, id
);
1781 if (chain_key
!= curr
->curr_chain_key
) {
1783 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1784 curr
->lockdep_depth
, i
,
1785 (unsigned long long)chain_key
,
1786 (unsigned long long)curr
->curr_chain_key
);
1792 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1793 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1795 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1798 printk("\n=================================\n");
1799 printk( "[ INFO: inconsistent lock state ]\n");
1800 print_kernel_version();
1801 printk( "---------------------------------\n");
1803 printk("inconsistent {%s} -> {%s} usage.\n",
1804 usage_str
[prev_bit
], usage_str
[new_bit
]);
1806 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1807 curr
->comm
, task_pid_nr(curr
),
1808 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1809 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1810 trace_hardirqs_enabled(curr
),
1811 trace_softirqs_enabled(curr
));
1814 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1815 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
1817 print_irqtrace_events(curr
);
1818 printk("\nother info that might help us debug this:\n");
1819 lockdep_print_held_locks(curr
);
1821 printk("\nstack backtrace:\n");
1828 * Print out an error if an invalid bit is set:
1831 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1832 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1834 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
1835 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1839 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1840 enum lock_usage_bit new_bit
);
1842 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1845 * print irq inversion bug:
1848 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
1849 struct held_lock
*this, int forwards
,
1850 const char *irqclass
)
1852 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1855 printk("\n=========================================================\n");
1856 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1857 print_kernel_version();
1858 printk( "---------------------------------------------------------\n");
1859 printk("%s/%d just changed the state of lock:\n",
1860 curr
->comm
, task_pid_nr(curr
));
1863 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass
);
1865 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass
);
1866 print_lock_name(other
);
1867 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1869 printk("\nother info that might help us debug this:\n");
1870 lockdep_print_held_locks(curr
);
1872 printk("\nthe first lock's dependencies:\n");
1873 print_lock_dependencies(hlock_class(this), 0);
1875 printk("\nthe second lock's dependencies:\n");
1876 print_lock_dependencies(other
, 0);
1878 printk("\nstack backtrace:\n");
1885 * Prove that in the forwards-direction subgraph starting at <this>
1886 * there is no lock matching <mask>:
1889 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
1890 enum lock_usage_bit bit
, const char *irqclass
)
1894 find_usage_bit
= bit
;
1895 /* fills in <forwards_match> */
1896 ret
= find_usage_forwards(hlock_class(this), 0);
1897 if (!ret
|| ret
== 1)
1900 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
1904 * Prove that in the backwards-direction subgraph starting at <this>
1905 * there is no lock matching <mask>:
1908 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
1909 enum lock_usage_bit bit
, const char *irqclass
)
1913 find_usage_bit
= bit
;
1914 /* fills in <backwards_match> */
1915 ret
= find_usage_backwards(hlock_class(this), 0);
1916 if (!ret
|| ret
== 1)
1919 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
1922 void print_irqtrace_events(struct task_struct
*curr
)
1924 printk("irq event stamp: %u\n", curr
->irq_events
);
1925 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
1926 print_ip_sym(curr
->hardirq_enable_ip
);
1927 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
1928 print_ip_sym(curr
->hardirq_disable_ip
);
1929 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
1930 print_ip_sym(curr
->softirq_enable_ip
);
1931 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
1932 print_ip_sym(curr
->softirq_disable_ip
);
1935 static int hardirq_verbose(struct lock_class
*class)
1938 return class_filter(class);
1943 static int softirq_verbose(struct lock_class
*class)
1946 return class_filter(class);
1951 #define STRICT_READ_CHECKS 1
1953 static int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
1954 enum lock_usage_bit new_bit
)
1959 case LOCK_USED_IN_HARDIRQ
:
1960 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1962 if (!valid_state(curr
, this, new_bit
,
1963 LOCK_ENABLED_HARDIRQS_READ
))
1966 * just marked it hardirq-safe, check that this lock
1967 * took no hardirq-unsafe lock in the past:
1969 if (!check_usage_forwards(curr
, this,
1970 LOCK_ENABLED_HARDIRQS
, "hard"))
1972 #if STRICT_READ_CHECKS
1974 * just marked it hardirq-safe, check that this lock
1975 * took no hardirq-unsafe-read lock in the past:
1977 if (!check_usage_forwards(curr
, this,
1978 LOCK_ENABLED_HARDIRQS_READ
, "hard-read"))
1981 if (hardirq_verbose(hlock_class(this)))
1984 case LOCK_USED_IN_SOFTIRQ
:
1985 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1987 if (!valid_state(curr
, this, new_bit
,
1988 LOCK_ENABLED_SOFTIRQS_READ
))
1991 * just marked it softirq-safe, check that this lock
1992 * took no softirq-unsafe lock in the past:
1994 if (!check_usage_forwards(curr
, this,
1995 LOCK_ENABLED_SOFTIRQS
, "soft"))
1997 #if STRICT_READ_CHECKS
1999 * just marked it softirq-safe, check that this lock
2000 * took no softirq-unsafe-read lock in the past:
2002 if (!check_usage_forwards(curr
, this,
2003 LOCK_ENABLED_SOFTIRQS_READ
, "soft-read"))
2006 if (softirq_verbose(hlock_class(this)))
2009 case LOCK_USED_IN_HARDIRQ_READ
:
2010 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
2013 * just marked it hardirq-read-safe, check that this lock
2014 * took no hardirq-unsafe lock in the past:
2016 if (!check_usage_forwards(curr
, this,
2017 LOCK_ENABLED_HARDIRQS
, "hard"))
2019 if (hardirq_verbose(hlock_class(this)))
2022 case LOCK_USED_IN_SOFTIRQ_READ
:
2023 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
2026 * just marked it softirq-read-safe, check that this lock
2027 * took no softirq-unsafe lock in the past:
2029 if (!check_usage_forwards(curr
, this,
2030 LOCK_ENABLED_SOFTIRQS
, "soft"))
2032 if (softirq_verbose(hlock_class(this)))
2035 case LOCK_ENABLED_HARDIRQS
:
2036 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
2038 if (!valid_state(curr
, this, new_bit
,
2039 LOCK_USED_IN_HARDIRQ_READ
))
2042 * just marked it hardirq-unsafe, check that no hardirq-safe
2043 * lock in the system ever took it in the past:
2045 if (!check_usage_backwards(curr
, this,
2046 LOCK_USED_IN_HARDIRQ
, "hard"))
2048 #if STRICT_READ_CHECKS
2050 * just marked it hardirq-unsafe, check that no
2051 * hardirq-safe-read lock in the system ever took
2054 if (!check_usage_backwards(curr
, this,
2055 LOCK_USED_IN_HARDIRQ_READ
, "hard-read"))
2058 if (hardirq_verbose(hlock_class(this)))
2061 case LOCK_ENABLED_SOFTIRQS
:
2062 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
2064 if (!valid_state(curr
, this, new_bit
,
2065 LOCK_USED_IN_SOFTIRQ_READ
))
2068 * just marked it softirq-unsafe, check that no softirq-safe
2069 * lock in the system ever took it in the past:
2071 if (!check_usage_backwards(curr
, this,
2072 LOCK_USED_IN_SOFTIRQ
, "soft"))
2074 #if STRICT_READ_CHECKS
2076 * just marked it softirq-unsafe, check that no
2077 * softirq-safe-read lock in the system ever took
2080 if (!check_usage_backwards(curr
, this,
2081 LOCK_USED_IN_SOFTIRQ_READ
, "soft-read"))
2084 if (softirq_verbose(hlock_class(this)))
2087 case LOCK_ENABLED_HARDIRQS_READ
:
2088 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
2090 #if STRICT_READ_CHECKS
2092 * just marked it hardirq-read-unsafe, check that no
2093 * hardirq-safe lock in the system ever took it in the past:
2095 if (!check_usage_backwards(curr
, this,
2096 LOCK_USED_IN_HARDIRQ
, "hard"))
2099 if (hardirq_verbose(hlock_class(this)))
2102 case LOCK_ENABLED_SOFTIRQS_READ
:
2103 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
2105 #if STRICT_READ_CHECKS
2107 * just marked it softirq-read-unsafe, check that no
2108 * softirq-safe lock in the system ever took it in the past:
2110 if (!check_usage_backwards(curr
, this,
2111 LOCK_USED_IN_SOFTIRQ
, "soft"))
2114 if (softirq_verbose(hlock_class(this)))
2126 * Mark all held locks with a usage bit:
2129 mark_held_locks(struct task_struct
*curr
, int hardirq
)
2131 enum lock_usage_bit usage_bit
;
2132 struct held_lock
*hlock
;
2135 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2136 hlock
= curr
->held_locks
+ i
;
2140 usage_bit
= LOCK_ENABLED_HARDIRQS_READ
;
2142 usage_bit
= LOCK_ENABLED_HARDIRQS
;
2145 usage_bit
= LOCK_ENABLED_SOFTIRQS_READ
;
2147 usage_bit
= LOCK_ENABLED_SOFTIRQS
;
2149 if (!mark_lock(curr
, hlock
, usage_bit
))
2157 * Debugging helper: via this flag we know that we are in
2158 * 'early bootup code', and will warn about any invalid irqs-on event:
2160 static int early_boot_irqs_enabled
;
2162 void early_boot_irqs_off(void)
2164 early_boot_irqs_enabled
= 0;
2167 void early_boot_irqs_on(void)
2169 early_boot_irqs_enabled
= 1;
2173 * Hardirqs will be enabled:
2175 void trace_hardirqs_on_caller(unsigned long ip
)
2177 struct task_struct
*curr
= current
;
2179 time_hardirqs_on(CALLER_ADDR0
, ip
);
2181 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2184 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
2187 if (unlikely(curr
->hardirqs_enabled
)) {
2188 debug_atomic_inc(&redundant_hardirqs_on
);
2191 /* we'll do an OFF -> ON transition: */
2192 curr
->hardirqs_enabled
= 1;
2194 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2196 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2199 * We are going to turn hardirqs on, so set the
2200 * usage bit for all held locks:
2202 if (!mark_held_locks(curr
, 1))
2205 * If we have softirqs enabled, then set the usage
2206 * bit for all held locks. (disabled hardirqs prevented
2207 * this bit from being set before)
2209 if (curr
->softirqs_enabled
)
2210 if (!mark_held_locks(curr
, 0))
2213 curr
->hardirq_enable_ip
= ip
;
2214 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2215 debug_atomic_inc(&hardirqs_on_events
);
2217 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2219 void trace_hardirqs_on(void)
2221 trace_hardirqs_on_caller(CALLER_ADDR0
);
2223 EXPORT_SYMBOL(trace_hardirqs_on
);
2226 * Hardirqs were disabled:
2228 void trace_hardirqs_off_caller(unsigned long ip
)
2230 struct task_struct
*curr
= current
;
2232 time_hardirqs_off(CALLER_ADDR0
, ip
);
2234 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2237 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2240 if (curr
->hardirqs_enabled
) {
2242 * We have done an ON -> OFF transition:
2244 curr
->hardirqs_enabled
= 0;
2245 curr
->hardirq_disable_ip
= ip
;
2246 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2247 debug_atomic_inc(&hardirqs_off_events
);
2249 debug_atomic_inc(&redundant_hardirqs_off
);
2251 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2253 void trace_hardirqs_off(void)
2255 trace_hardirqs_off_caller(CALLER_ADDR0
);
2257 EXPORT_SYMBOL(trace_hardirqs_off
);
2260 * Softirqs will be enabled:
2262 void trace_softirqs_on(unsigned long ip
)
2264 struct task_struct
*curr
= current
;
2266 if (unlikely(!debug_locks
))
2269 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2272 if (curr
->softirqs_enabled
) {
2273 debug_atomic_inc(&redundant_softirqs_on
);
2278 * We'll do an OFF -> ON transition:
2280 curr
->softirqs_enabled
= 1;
2281 curr
->softirq_enable_ip
= ip
;
2282 curr
->softirq_enable_event
= ++curr
->irq_events
;
2283 debug_atomic_inc(&softirqs_on_events
);
2285 * We are going to turn softirqs on, so set the
2286 * usage bit for all held locks, if hardirqs are
2289 if (curr
->hardirqs_enabled
)
2290 mark_held_locks(curr
, 0);
2294 * Softirqs were disabled:
2296 void trace_softirqs_off(unsigned long ip
)
2298 struct task_struct
*curr
= current
;
2300 if (unlikely(!debug_locks
))
2303 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2306 if (curr
->softirqs_enabled
) {
2308 * We have done an ON -> OFF transition:
2310 curr
->softirqs_enabled
= 0;
2311 curr
->softirq_disable_ip
= ip
;
2312 curr
->softirq_disable_event
= ++curr
->irq_events
;
2313 debug_atomic_inc(&softirqs_off_events
);
2314 DEBUG_LOCKS_WARN_ON(!softirq_count());
2316 debug_atomic_inc(&redundant_softirqs_off
);
2319 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2322 * If non-trylock use in a hardirq or softirq context, then
2323 * mark the lock as used in these contexts:
2325 if (!hlock
->trylock
) {
2327 if (curr
->hardirq_context
)
2328 if (!mark_lock(curr
, hlock
,
2329 LOCK_USED_IN_HARDIRQ_READ
))
2331 if (curr
->softirq_context
)
2332 if (!mark_lock(curr
, hlock
,
2333 LOCK_USED_IN_SOFTIRQ_READ
))
2336 if (curr
->hardirq_context
)
2337 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2339 if (curr
->softirq_context
)
2340 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2344 if (!hlock
->hardirqs_off
) {
2346 if (!mark_lock(curr
, hlock
,
2347 LOCK_ENABLED_HARDIRQS_READ
))
2349 if (curr
->softirqs_enabled
)
2350 if (!mark_lock(curr
, hlock
,
2351 LOCK_ENABLED_SOFTIRQS_READ
))
2354 if (!mark_lock(curr
, hlock
,
2355 LOCK_ENABLED_HARDIRQS
))
2357 if (curr
->softirqs_enabled
)
2358 if (!mark_lock(curr
, hlock
,
2359 LOCK_ENABLED_SOFTIRQS
))
2367 static int separate_irq_context(struct task_struct
*curr
,
2368 struct held_lock
*hlock
)
2370 unsigned int depth
= curr
->lockdep_depth
;
2373 * Keep track of points where we cross into an interrupt context:
2375 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2376 curr
->softirq_context
;
2378 struct held_lock
*prev_hlock
;
2380 prev_hlock
= curr
->held_locks
+ depth
-1;
2382 * If we cross into another context, reset the
2383 * hash key (this also prevents the checking and the
2384 * adding of the dependency to 'prev'):
2386 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2395 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2396 enum lock_usage_bit new_bit
)
2402 static inline int mark_irqflags(struct task_struct
*curr
,
2403 struct held_lock
*hlock
)
2408 static inline int separate_irq_context(struct task_struct
*curr
,
2409 struct held_lock
*hlock
)
2417 * Mark a lock with a usage bit, and validate the state transition:
2419 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2420 enum lock_usage_bit new_bit
)
2422 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2425 * If already set then do not dirty the cacheline,
2426 * nor do any checks:
2428 if (likely(hlock_class(this)->usage_mask
& new_mask
))
2434 * Make sure we didnt race:
2436 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
2441 hlock_class(this)->usage_mask
|= new_mask
;
2443 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
2447 case LOCK_USED_IN_HARDIRQ
:
2448 case LOCK_USED_IN_SOFTIRQ
:
2449 case LOCK_USED_IN_HARDIRQ_READ
:
2450 case LOCK_USED_IN_SOFTIRQ_READ
:
2451 case LOCK_ENABLED_HARDIRQS
:
2452 case LOCK_ENABLED_SOFTIRQS
:
2453 case LOCK_ENABLED_HARDIRQS_READ
:
2454 case LOCK_ENABLED_SOFTIRQS_READ
:
2455 ret
= mark_lock_irq(curr
, this, new_bit
);
2460 debug_atomic_dec(&nr_unused_locks
);
2463 if (!debug_locks_off_graph_unlock())
2472 * We must printk outside of the graph_lock:
2475 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2477 print_irqtrace_events(curr
);
2485 * Initialize a lock instance's lock-class mapping info:
2487 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2488 struct lock_class_key
*key
, int subclass
)
2490 if (unlikely(!debug_locks
))
2493 if (DEBUG_LOCKS_WARN_ON(!key
))
2495 if (DEBUG_LOCKS_WARN_ON(!name
))
2498 * Sanity check, the lock-class key must be persistent:
2500 if (!static_obj(key
)) {
2501 printk("BUG: key %p not in .data!\n", key
);
2502 DEBUG_LOCKS_WARN_ON(1);
2507 lock
->class_cache
= NULL
;
2508 #ifdef CONFIG_LOCK_STAT
2509 lock
->cpu
= raw_smp_processor_id();
2512 register_lock_class(lock
, subclass
, 1);
2514 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2517 * This gets called for every mutex_lock*()/spin_lock*() operation.
2518 * We maintain the dependency maps and validate the locking attempt:
2520 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2521 int trylock
, int read
, int check
, int hardirqs_off
,
2522 struct lockdep_map
*nest_lock
, unsigned long ip
)
2524 struct task_struct
*curr
= current
;
2525 struct lock_class
*class = NULL
;
2526 struct held_lock
*hlock
;
2527 unsigned int depth
, id
;
2534 if (unlikely(!debug_locks
))
2537 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2540 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
2542 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2543 printk("turning off the locking correctness validator.\n");
2548 class = lock
->class_cache
;
2550 * Not cached yet or subclass?
2552 if (unlikely(!class)) {
2553 class = register_lock_class(lock
, subclass
, 0);
2557 debug_atomic_inc((atomic_t
*)&class->ops
);
2558 if (very_verbose(class)) {
2559 printk("\nacquire class [%p] %s", class->key
, class->name
);
2560 if (class->name_version
> 1)
2561 printk("#%d", class->name_version
);
2567 * Add the lock to the list of currently held locks.
2568 * (we dont increase the depth just yet, up until the
2569 * dependency checks are done)
2571 depth
= curr
->lockdep_depth
;
2572 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2575 hlock
= curr
->held_locks
+ depth
;
2576 if (DEBUG_LOCKS_WARN_ON(!class))
2578 hlock
->class_idx
= class - lock_classes
+ 1;
2579 hlock
->acquire_ip
= ip
;
2580 hlock
->instance
= lock
;
2581 hlock
->nest_lock
= nest_lock
;
2582 hlock
->trylock
= trylock
;
2584 hlock
->check
= check
;
2585 hlock
->hardirqs_off
= !!hardirqs_off
;
2586 #ifdef CONFIG_LOCK_STAT
2587 hlock
->waittime_stamp
= 0;
2588 hlock
->holdtime_stamp
= sched_clock();
2591 if (check
== 2 && !mark_irqflags(curr
, hlock
))
2594 /* mark it as used: */
2595 if (!mark_lock(curr
, hlock
, LOCK_USED
))
2599 * Calculate the chain hash: it's the combined hash of all the
2600 * lock keys along the dependency chain. We save the hash value
2601 * at every step so that we can get the current hash easily
2602 * after unlock. The chain hash is then used to cache dependency
2605 * The 'key ID' is what is the most compact key value to drive
2606 * the hash, not class->key.
2608 id
= class - lock_classes
;
2609 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2612 chain_key
= curr
->curr_chain_key
;
2614 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2619 hlock
->prev_chain_key
= chain_key
;
2620 if (separate_irq_context(curr
, hlock
)) {
2624 chain_key
= iterate_chain_key(chain_key
, id
);
2626 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
2629 curr
->curr_chain_key
= chain_key
;
2630 curr
->lockdep_depth
++;
2631 check_chain_key(curr
);
2632 #ifdef CONFIG_DEBUG_LOCKDEP
2633 if (unlikely(!debug_locks
))
2636 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2638 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2639 printk("turning off the locking correctness validator.\n");
2643 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2644 max_lockdep_depth
= curr
->lockdep_depth
;
2650 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2653 if (!debug_locks_off())
2655 if (debug_locks_silent
)
2658 printk("\n=====================================\n");
2659 printk( "[ BUG: bad unlock balance detected! ]\n");
2660 printk( "-------------------------------------\n");
2661 printk("%s/%d is trying to release lock (",
2662 curr
->comm
, task_pid_nr(curr
));
2663 print_lockdep_cache(lock
);
2666 printk("but there are no more locks to release!\n");
2667 printk("\nother info that might help us debug this:\n");
2668 lockdep_print_held_locks(curr
);
2670 printk("\nstack backtrace:\n");
2677 * Common debugging checks for both nested and non-nested unlock:
2679 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2682 if (unlikely(!debug_locks
))
2684 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2687 if (curr
->lockdep_depth
<= 0)
2688 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2694 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
2695 struct lock_class_key
*key
, unsigned int subclass
,
2698 struct task_struct
*curr
= current
;
2699 struct held_lock
*hlock
, *prev_hlock
;
2700 struct lock_class
*class;
2704 depth
= curr
->lockdep_depth
;
2705 if (DEBUG_LOCKS_WARN_ON(!depth
))
2709 for (i
= depth
-1; i
>= 0; i
--) {
2710 hlock
= curr
->held_locks
+ i
;
2712 * We must not cross into another context:
2714 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2716 if (hlock
->instance
== lock
)
2720 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2723 lockdep_init_map(lock
, name
, key
, 0);
2724 class = register_lock_class(lock
, subclass
, 0);
2725 hlock
->class_idx
= class - lock_classes
+ 1;
2727 curr
->lockdep_depth
= i
;
2728 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2730 for (; i
< depth
; i
++) {
2731 hlock
= curr
->held_locks
+ i
;
2732 if (!__lock_acquire(hlock
->instance
,
2733 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2734 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2735 hlock
->nest_lock
, hlock
->acquire_ip
))
2739 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
2745 * Remove the lock to the list of currently held locks in a
2746 * potentially non-nested (out of order) manner. This is a
2747 * relatively rare operation, as all the unlock APIs default
2748 * to nested mode (which uses lock_release()):
2751 lock_release_non_nested(struct task_struct
*curr
,
2752 struct lockdep_map
*lock
, unsigned long ip
)
2754 struct held_lock
*hlock
, *prev_hlock
;
2759 * Check whether the lock exists in the current stack
2762 depth
= curr
->lockdep_depth
;
2763 if (DEBUG_LOCKS_WARN_ON(!depth
))
2767 for (i
= depth
-1; i
>= 0; i
--) {
2768 hlock
= curr
->held_locks
+ i
;
2770 * We must not cross into another context:
2772 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2774 if (hlock
->instance
== lock
)
2778 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2781 lock_release_holdtime(hlock
);
2784 * We have the right lock to unlock, 'hlock' points to it.
2785 * Now we remove it from the stack, and add back the other
2786 * entries (if any), recalculating the hash along the way:
2788 curr
->lockdep_depth
= i
;
2789 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2791 for (i
++; i
< depth
; i
++) {
2792 hlock
= curr
->held_locks
+ i
;
2793 if (!__lock_acquire(hlock
->instance
,
2794 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2795 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2796 hlock
->nest_lock
, hlock
->acquire_ip
))
2800 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2806 * Remove the lock to the list of currently held locks - this gets
2807 * called on mutex_unlock()/spin_unlock*() (or on a failed
2808 * mutex_lock_interruptible()). This is done for unlocks that nest
2809 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2811 static int lock_release_nested(struct task_struct
*curr
,
2812 struct lockdep_map
*lock
, unsigned long ip
)
2814 struct held_lock
*hlock
;
2818 * Pop off the top of the lock stack:
2820 depth
= curr
->lockdep_depth
- 1;
2821 hlock
= curr
->held_locks
+ depth
;
2824 * Is the unlock non-nested:
2826 if (hlock
->instance
!= lock
)
2827 return lock_release_non_nested(curr
, lock
, ip
);
2828 curr
->lockdep_depth
--;
2830 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2833 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2835 lock_release_holdtime(hlock
);
2837 #ifdef CONFIG_DEBUG_LOCKDEP
2838 hlock
->prev_chain_key
= 0;
2839 hlock
->class_idx
= 0;
2840 hlock
->acquire_ip
= 0;
2841 hlock
->irq_context
= 0;
2847 * Remove the lock to the list of currently held locks - this gets
2848 * called on mutex_unlock()/spin_unlock*() (or on a failed
2849 * mutex_lock_interruptible()). This is done for unlocks that nest
2850 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2853 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2855 struct task_struct
*curr
= current
;
2857 if (!check_unlock(curr
, lock
, ip
))
2861 if (!lock_release_nested(curr
, lock
, ip
))
2864 if (!lock_release_non_nested(curr
, lock
, ip
))
2868 check_chain_key(curr
);
2872 * Check whether we follow the irq-flags state precisely:
2874 static void check_flags(unsigned long flags
)
2876 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2877 defined(CONFIG_TRACE_IRQFLAGS)
2881 if (irqs_disabled_flags(flags
)) {
2882 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
2883 printk("possible reason: unannotated irqs-off.\n");
2886 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
2887 printk("possible reason: unannotated irqs-on.\n");
2892 * We dont accurately track softirq state in e.g.
2893 * hardirq contexts (such as on 4KSTACKS), so only
2894 * check if not in hardirq contexts:
2896 if (!hardirq_count()) {
2897 if (softirq_count())
2898 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
2900 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
2904 print_irqtrace_events(current
);
2908 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
2909 struct lock_class_key
*key
, unsigned int subclass
,
2912 unsigned long flags
;
2914 if (unlikely(current
->lockdep_recursion
))
2917 raw_local_irq_save(flags
);
2918 current
->lockdep_recursion
= 1;
2920 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
2921 check_chain_key(current
);
2922 current
->lockdep_recursion
= 0;
2923 raw_local_irq_restore(flags
);
2925 EXPORT_SYMBOL_GPL(lock_set_class
);
2928 * We are not always called with irqs disabled - do that here,
2929 * and also avoid lockdep recursion:
2931 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2932 int trylock
, int read
, int check
,
2933 struct lockdep_map
*nest_lock
, unsigned long ip
)
2935 unsigned long flags
;
2937 if (unlikely(current
->lockdep_recursion
))
2940 raw_local_irq_save(flags
);
2943 current
->lockdep_recursion
= 1;
2944 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
2945 irqs_disabled_flags(flags
), nest_lock
, ip
);
2946 current
->lockdep_recursion
= 0;
2947 raw_local_irq_restore(flags
);
2949 EXPORT_SYMBOL_GPL(lock_acquire
);
2951 void lock_release(struct lockdep_map
*lock
, int nested
,
2954 unsigned long flags
;
2956 if (unlikely(current
->lockdep_recursion
))
2959 raw_local_irq_save(flags
);
2961 current
->lockdep_recursion
= 1;
2962 __lock_release(lock
, nested
, ip
);
2963 current
->lockdep_recursion
= 0;
2964 raw_local_irq_restore(flags
);
2966 EXPORT_SYMBOL_GPL(lock_release
);
2968 #ifdef CONFIG_LOCK_STAT
2970 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2973 if (!debug_locks_off())
2975 if (debug_locks_silent
)
2978 printk("\n=================================\n");
2979 printk( "[ BUG: bad contention detected! ]\n");
2980 printk( "---------------------------------\n");
2981 printk("%s/%d is trying to contend lock (",
2982 curr
->comm
, task_pid_nr(curr
));
2983 print_lockdep_cache(lock
);
2986 printk("but there are no locks held!\n");
2987 printk("\nother info that might help us debug this:\n");
2988 lockdep_print_held_locks(curr
);
2990 printk("\nstack backtrace:\n");
2997 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
2999 struct task_struct
*curr
= current
;
3000 struct held_lock
*hlock
, *prev_hlock
;
3001 struct lock_class_stats
*stats
;
3003 int i
, contention_point
, contending_point
;
3005 depth
= curr
->lockdep_depth
;
3006 if (DEBUG_LOCKS_WARN_ON(!depth
))
3010 for (i
= depth
-1; i
>= 0; i
--) {
3011 hlock
= curr
->held_locks
+ i
;
3013 * We must not cross into another context:
3015 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3017 if (hlock
->instance
== lock
)
3021 print_lock_contention_bug(curr
, lock
, ip
);
3025 hlock
->waittime_stamp
= sched_clock();
3027 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3028 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3031 stats
= get_lock_stats(hlock_class(hlock
));
3032 if (contention_point
< LOCKSTAT_POINTS
)
3033 stats
->contention_point
[contention_point
]++;
3034 if (contending_point
< LOCKSTAT_POINTS
)
3035 stats
->contending_point
[contending_point
]++;
3036 if (lock
->cpu
!= smp_processor_id())
3037 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3038 put_lock_stats(stats
);
3042 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3044 struct task_struct
*curr
= current
;
3045 struct held_lock
*hlock
, *prev_hlock
;
3046 struct lock_class_stats
*stats
;
3052 depth
= curr
->lockdep_depth
;
3053 if (DEBUG_LOCKS_WARN_ON(!depth
))
3057 for (i
= depth
-1; i
>= 0; i
--) {
3058 hlock
= curr
->held_locks
+ i
;
3060 * We must not cross into another context:
3062 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3064 if (hlock
->instance
== lock
)
3068 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3072 cpu
= smp_processor_id();
3073 if (hlock
->waittime_stamp
) {
3074 now
= sched_clock();
3075 waittime
= now
- hlock
->waittime_stamp
;
3076 hlock
->holdtime_stamp
= now
;
3079 stats
= get_lock_stats(hlock_class(hlock
));
3082 lock_time_inc(&stats
->read_waittime
, waittime
);
3084 lock_time_inc(&stats
->write_waittime
, waittime
);
3086 if (lock
->cpu
!= cpu
)
3087 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3088 put_lock_stats(stats
);
3094 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3096 unsigned long flags
;
3098 if (unlikely(!lock_stat
))
3101 if (unlikely(current
->lockdep_recursion
))
3104 raw_local_irq_save(flags
);
3106 current
->lockdep_recursion
= 1;
3107 __lock_contended(lock
, ip
);
3108 current
->lockdep_recursion
= 0;
3109 raw_local_irq_restore(flags
);
3111 EXPORT_SYMBOL_GPL(lock_contended
);
3113 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3115 unsigned long flags
;
3117 if (unlikely(!lock_stat
))
3120 if (unlikely(current
->lockdep_recursion
))
3123 raw_local_irq_save(flags
);
3125 current
->lockdep_recursion
= 1;
3126 __lock_acquired(lock
, ip
);
3127 current
->lockdep_recursion
= 0;
3128 raw_local_irq_restore(flags
);
3130 EXPORT_SYMBOL_GPL(lock_acquired
);
3134 * Used by the testsuite, sanitize the validator state
3135 * after a simulated failure:
3138 void lockdep_reset(void)
3140 unsigned long flags
;
3143 raw_local_irq_save(flags
);
3144 current
->curr_chain_key
= 0;
3145 current
->lockdep_depth
= 0;
3146 current
->lockdep_recursion
= 0;
3147 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3148 nr_hardirq_chains
= 0;
3149 nr_softirq_chains
= 0;
3150 nr_process_chains
= 0;
3152 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3153 INIT_LIST_HEAD(chainhash_table
+ i
);
3154 raw_local_irq_restore(flags
);
3157 static void zap_class(struct lock_class
*class)
3162 * Remove all dependencies this lock is
3165 for (i
= 0; i
< nr_list_entries
; i
++) {
3166 if (list_entries
[i
].class == class)
3167 list_del_rcu(&list_entries
[i
].entry
);
3170 * Unhash the class and remove it from the all_lock_classes list:
3172 list_del_rcu(&class->hash_entry
);
3173 list_del_rcu(&class->lock_entry
);
3178 static inline int within(const void *addr
, void *start
, unsigned long size
)
3180 return addr
>= start
&& addr
< start
+ size
;
3183 void lockdep_free_key_range(void *start
, unsigned long size
)
3185 struct lock_class
*class, *next
;
3186 struct list_head
*head
;
3187 unsigned long flags
;
3191 raw_local_irq_save(flags
);
3192 locked
= graph_lock();
3195 * Unhash all classes that were created by this module:
3197 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3198 head
= classhash_table
+ i
;
3199 if (list_empty(head
))
3201 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3202 if (within(class->key
, start
, size
))
3204 else if (within(class->name
, start
, size
))
3211 raw_local_irq_restore(flags
);
3214 void lockdep_reset_lock(struct lockdep_map
*lock
)
3216 struct lock_class
*class, *next
;
3217 struct list_head
*head
;
3218 unsigned long flags
;
3222 raw_local_irq_save(flags
);
3225 * Remove all classes this lock might have:
3227 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3229 * If the class exists we look it up and zap it:
3231 class = look_up_lock_class(lock
, j
);
3236 * Debug check: in the end all mapped classes should
3239 locked
= graph_lock();
3240 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3241 head
= classhash_table
+ i
;
3242 if (list_empty(head
))
3244 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3245 if (unlikely(class == lock
->class_cache
)) {
3246 if (debug_locks_off_graph_unlock())
3256 raw_local_irq_restore(flags
);
3259 void lockdep_init(void)
3264 * Some architectures have their own start_kernel()
3265 * code which calls lockdep_init(), while we also
3266 * call lockdep_init() from the start_kernel() itself,
3267 * and we want to initialize the hashes only once:
3269 if (lockdep_initialized
)
3272 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3273 INIT_LIST_HEAD(classhash_table
+ i
);
3275 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3276 INIT_LIST_HEAD(chainhash_table
+ i
);
3278 lockdep_initialized
= 1;
3281 void __init
lockdep_info(void)
3283 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3285 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
3286 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
3287 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
3288 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
3289 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
3290 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
3291 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
3293 printk(" memory used by lock dependency info: %lu kB\n",
3294 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
3295 sizeof(struct list_head
) * CLASSHASH_SIZE
+
3296 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
3297 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
3298 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
3300 printk(" per task-struct memory footprint: %lu bytes\n",
3301 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
3303 #ifdef CONFIG_DEBUG_LOCKDEP
3304 if (lockdep_init_error
) {
3305 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3306 printk("Call stack leading to lockdep invocation was:\n");
3307 print_stack_trace(&lockdep_init_trace
, 0);
3313 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
3314 const void *mem_to
, struct held_lock
*hlock
)
3316 if (!debug_locks_off())
3318 if (debug_locks_silent
)
3321 printk("\n=========================\n");
3322 printk( "[ BUG: held lock freed! ]\n");
3323 printk( "-------------------------\n");
3324 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3325 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
3327 lockdep_print_held_locks(curr
);
3329 printk("\nstack backtrace:\n");
3333 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
3334 const void* lock_from
, unsigned long lock_len
)
3336 return lock_from
+ lock_len
<= mem_from
||
3337 mem_from
+ mem_len
<= lock_from
;
3341 * Called when kernel memory is freed (or unmapped), or if a lock
3342 * is destroyed or reinitialized - this code checks whether there is
3343 * any held lock in the memory range of <from> to <to>:
3345 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
3347 struct task_struct
*curr
= current
;
3348 struct held_lock
*hlock
;
3349 unsigned long flags
;
3352 if (unlikely(!debug_locks
))
3355 local_irq_save(flags
);
3356 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3357 hlock
= curr
->held_locks
+ i
;
3359 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
3360 sizeof(*hlock
->instance
)))
3363 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
3366 local_irq_restore(flags
);
3368 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
3370 static void print_held_locks_bug(struct task_struct
*curr
)
3372 if (!debug_locks_off())
3374 if (debug_locks_silent
)
3377 printk("\n=====================================\n");
3378 printk( "[ BUG: lock held at task exit time! ]\n");
3379 printk( "-------------------------------------\n");
3380 printk("%s/%d is exiting with locks still held!\n",
3381 curr
->comm
, task_pid_nr(curr
));
3382 lockdep_print_held_locks(curr
);
3384 printk("\nstack backtrace:\n");
3388 void debug_check_no_locks_held(struct task_struct
*task
)
3390 if (unlikely(task
->lockdep_depth
> 0))
3391 print_held_locks_bug(task
);
3394 void debug_show_all_locks(void)
3396 struct task_struct
*g
, *p
;
3400 if (unlikely(!debug_locks
)) {
3401 printk("INFO: lockdep is turned off.\n");
3404 printk("\nShowing all locks held in the system:\n");
3407 * Here we try to get the tasklist_lock as hard as possible,
3408 * if not successful after 2 seconds we ignore it (but keep
3409 * trying). This is to enable a debug printout even if a
3410 * tasklist_lock-holding task deadlocks or crashes.
3413 if (!read_trylock(&tasklist_lock
)) {
3415 printk("hm, tasklist_lock locked, retrying... ");
3418 printk(" #%d", 10-count
);
3422 printk(" ignoring it.\n");
3426 printk(KERN_CONT
" locked it.\n");
3429 do_each_thread(g
, p
) {
3431 * It's not reliable to print a task's held locks
3432 * if it's not sleeping (or if it's not the current
3435 if (p
->state
== TASK_RUNNING
&& p
!= current
)
3437 if (p
->lockdep_depth
)
3438 lockdep_print_held_locks(p
);
3440 if (read_trylock(&tasklist_lock
))
3442 } while_each_thread(g
, p
);
3445 printk("=============================================\n\n");
3448 read_unlock(&tasklist_lock
);
3450 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
3453 * Careful: only use this function if you are sure that
3454 * the task cannot run in parallel!
3456 void __debug_show_held_locks(struct task_struct
*task
)
3458 if (unlikely(!debug_locks
)) {
3459 printk("INFO: lockdep is turned off.\n");
3462 lockdep_print_held_locks(task
);
3464 EXPORT_SYMBOL_GPL(__debug_show_held_locks
);
3466 void debug_show_held_locks(struct task_struct
*task
)
3468 __debug_show_held_locks(task
);
3470 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
3472 void lockdep_sys_exit(void)
3474 struct task_struct
*curr
= current
;
3476 if (unlikely(curr
->lockdep_depth
)) {
3477 if (!debug_locks_off())
3479 printk("\n================================================\n");
3480 printk( "[ BUG: lock held when returning to user space! ]\n");
3481 printk( "------------------------------------------------\n");
3482 printk("%s/%d is leaving the kernel with locks still held!\n",
3483 curr
->comm
, curr
->pid
);
3484 lockdep_print_held_locks(curr
);