4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
45 #include <asm/sections.h>
47 #include "lockdep_internals.h"
49 #ifdef CONFIG_PROVE_LOCKING
50 int prove_locking
= 1;
51 module_param(prove_locking
, int, 0644);
53 #define prove_locking 0
56 #ifdef CONFIG_LOCK_STAT
58 module_param(lock_stat
, int, 0644);
64 * lockdep_lock: protects the lockdep graph, the hashes and the
65 * class/list/hash allocators.
67 * This is one of the rare exceptions where it's justified
68 * to use a raw spinlock - we really dont want the spinlock
69 * code to recurse back into the lockdep code...
71 static raw_spinlock_t lockdep_lock
= (raw_spinlock_t
)__RAW_SPIN_LOCK_UNLOCKED
;
73 static int graph_lock(void)
75 __raw_spin_lock(&lockdep_lock
);
77 * Make sure that if another CPU detected a bug while
78 * walking the graph we dont change it (while the other
79 * CPU is busy printing out stuff with the graph lock
83 __raw_spin_unlock(&lockdep_lock
);
86 /* prevent any recursions within lockdep from causing deadlocks */
87 current
->lockdep_recursion
++;
91 static inline int graph_unlock(void)
93 if (debug_locks
&& !__raw_spin_is_locked(&lockdep_lock
))
94 return DEBUG_LOCKS_WARN_ON(1);
96 current
->lockdep_recursion
--;
97 __raw_spin_unlock(&lockdep_lock
);
102 * Turn lock debugging off and return with 0 if it was off already,
103 * and also release the graph lock:
105 static inline int debug_locks_off_graph_unlock(void)
107 int ret
= debug_locks_off();
109 __raw_spin_unlock(&lockdep_lock
);
114 static int lockdep_initialized
;
116 unsigned long nr_list_entries
;
117 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
120 * All data structures here are protected by the global debug_lock.
122 * Mutex key structs only get allocated, once during bootup, and never
123 * get freed - this significantly simplifies the debugging code.
125 unsigned long nr_lock_classes
;
126 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
128 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
130 if (!hlock
->class_idx
) {
131 DEBUG_LOCKS_WARN_ON(1);
134 return lock_classes
+ hlock
->class_idx
- 1;
137 #ifdef CONFIG_LOCK_STAT
138 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
], lock_stats
);
140 static int lock_point(unsigned long points
[], unsigned long ip
)
144 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
145 if (points
[i
] == 0) {
156 static void lock_time_inc(struct lock_time
*lt
, s64 time
)
161 if (time
< lt
->min
|| !lt
->min
)
168 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
170 dst
->min
+= src
->min
;
171 dst
->max
+= src
->max
;
172 dst
->total
+= src
->total
;
176 struct lock_class_stats
lock_stats(struct lock_class
*class)
178 struct lock_class_stats stats
;
181 memset(&stats
, 0, sizeof(struct lock_class_stats
));
182 for_each_possible_cpu(cpu
) {
183 struct lock_class_stats
*pcs
=
184 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
186 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
187 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
189 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
190 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
192 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
193 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
195 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
196 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
198 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
199 stats
.bounces
[i
] += pcs
->bounces
[i
];
205 void clear_lock_stats(struct lock_class
*class)
209 for_each_possible_cpu(cpu
) {
210 struct lock_class_stats
*cpu_stats
=
211 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
213 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
215 memset(class->contention_point
, 0, sizeof(class->contention_point
));
216 memset(class->contending_point
, 0, sizeof(class->contending_point
));
219 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
221 return &get_cpu_var(lock_stats
)[class - lock_classes
];
224 static void put_lock_stats(struct lock_class_stats
*stats
)
226 put_cpu_var(lock_stats
);
229 static void lock_release_holdtime(struct held_lock
*hlock
)
231 struct lock_class_stats
*stats
;
237 holdtime
= sched_clock() - hlock
->holdtime_stamp
;
239 stats
= get_lock_stats(hlock_class(hlock
));
241 lock_time_inc(&stats
->read_holdtime
, holdtime
);
243 lock_time_inc(&stats
->write_holdtime
, holdtime
);
244 put_lock_stats(stats
);
247 static inline void lock_release_holdtime(struct held_lock
*hlock
)
253 * We keep a global list of all lock classes. The list only grows,
254 * never shrinks. The list is only accessed with the lockdep
255 * spinlock lock held.
257 LIST_HEAD(all_lock_classes
);
260 * The lockdep classes are in a hash-table as well, for fast lookup:
262 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
263 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
264 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
265 #define classhashentry(key) (classhash_table + __classhashfn((key)))
267 static struct list_head classhash_table
[CLASSHASH_SIZE
];
270 * We put the lock dependency chains into a hash-table as well, to cache
273 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
274 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
275 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
276 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
278 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
281 * The hash key of the lock dependency chains is a hash itself too:
282 * it's a hash of all locks taken up to that lock, including that lock.
283 * It's a 64-bit hash, because it's important for the keys to be
286 #define iterate_chain_key(key1, key2) \
287 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
288 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
291 void lockdep_off(void)
293 current
->lockdep_recursion
++;
296 EXPORT_SYMBOL(lockdep_off
);
298 void lockdep_on(void)
300 current
->lockdep_recursion
--;
303 EXPORT_SYMBOL(lockdep_on
);
306 * Debugging switches:
310 #define VERY_VERBOSE 0
313 # define HARDIRQ_VERBOSE 1
314 # define SOFTIRQ_VERBOSE 1
316 # define HARDIRQ_VERBOSE 0
317 # define SOFTIRQ_VERBOSE 0
320 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
322 * Quick filtering for interesting events:
324 static int class_filter(struct lock_class
*class)
328 if (class->name_version
== 1 &&
329 !strcmp(class->name
, "lockname"))
331 if (class->name_version
== 1 &&
332 !strcmp(class->name
, "&struct->lockfield"))
335 /* Filter everything else. 1 would be to allow everything else */
340 static int verbose(struct lock_class
*class)
343 return class_filter(class);
349 * Stack-trace: tightly packed array of stack backtrace
350 * addresses. Protected by the graph_lock.
352 unsigned long nr_stack_trace_entries
;
353 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
355 static int save_trace(struct stack_trace
*trace
)
357 trace
->nr_entries
= 0;
358 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
359 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
363 save_stack_trace(trace
);
365 trace
->max_entries
= trace
->nr_entries
;
367 nr_stack_trace_entries
+= trace
->nr_entries
;
369 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
370 if (!debug_locks_off_graph_unlock())
373 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
374 printk("turning off the locking correctness validator.\n");
383 unsigned int nr_hardirq_chains
;
384 unsigned int nr_softirq_chains
;
385 unsigned int nr_process_chains
;
386 unsigned int max_lockdep_depth
;
387 unsigned int max_recursion_depth
;
389 static unsigned int lockdep_dependency_gen_id
;
391 static bool lockdep_dependency_visit(struct lock_class
*source
,
395 lockdep_dependency_gen_id
++;
396 if (source
->dep_gen_id
== lockdep_dependency_gen_id
)
398 source
->dep_gen_id
= lockdep_dependency_gen_id
;
402 #ifdef CONFIG_DEBUG_LOCKDEP
404 * We cannot printk in early bootup code. Not even early_printk()
405 * might work. So we mark any initialization errors and printk
406 * about it later on, in lockdep_info().
408 static int lockdep_init_error
;
409 static unsigned long lockdep_init_trace_data
[20];
410 static struct stack_trace lockdep_init_trace
= {
411 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
412 .entries
= lockdep_init_trace_data
,
416 * Various lockdep statistics:
418 atomic_t chain_lookup_hits
;
419 atomic_t chain_lookup_misses
;
420 atomic_t hardirqs_on_events
;
421 atomic_t hardirqs_off_events
;
422 atomic_t redundant_hardirqs_on
;
423 atomic_t redundant_hardirqs_off
;
424 atomic_t softirqs_on_events
;
425 atomic_t softirqs_off_events
;
426 atomic_t redundant_softirqs_on
;
427 atomic_t redundant_softirqs_off
;
428 atomic_t nr_unused_locks
;
429 atomic_t nr_cyclic_checks
;
430 atomic_t nr_cyclic_check_recursions
;
431 atomic_t nr_find_usage_forwards_checks
;
432 atomic_t nr_find_usage_forwards_recursions
;
433 atomic_t nr_find_usage_backwards_checks
;
434 atomic_t nr_find_usage_backwards_recursions
;
435 # define debug_atomic_inc(ptr) atomic_inc(ptr)
436 # define debug_atomic_dec(ptr) atomic_dec(ptr)
437 # define debug_atomic_read(ptr) atomic_read(ptr)
439 # define debug_atomic_inc(ptr) do { } while (0)
440 # define debug_atomic_dec(ptr) do { } while (0)
441 # define debug_atomic_read(ptr) 0
448 static const char *usage_str
[] =
450 [LOCK_USED
] = "initial-use ",
451 [LOCK_USED_IN_HARDIRQ
] = "in-hardirq-W",
452 [LOCK_USED_IN_SOFTIRQ
] = "in-softirq-W",
453 [LOCK_ENABLED_SOFTIRQS
] = "softirq-on-W",
454 [LOCK_ENABLED_HARDIRQS
] = "hardirq-on-W",
455 [LOCK_USED_IN_HARDIRQ_READ
] = "in-hardirq-R",
456 [LOCK_USED_IN_SOFTIRQ_READ
] = "in-softirq-R",
457 [LOCK_ENABLED_SOFTIRQS_READ
] = "softirq-on-R",
458 [LOCK_ENABLED_HARDIRQS_READ
] = "hardirq-on-R",
461 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
463 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
467 get_usage_chars(struct lock_class
*class, char *c1
, char *c2
, char *c3
, char *c4
)
469 *c1
= '.', *c2
= '.', *c3
= '.', *c4
= '.';
471 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ
)
474 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS
)
477 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ
)
480 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS
)
483 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
485 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ_READ
) {
487 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
491 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
493 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ_READ
) {
495 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
500 static void print_lock_name(struct lock_class
*class)
502 char str
[KSYM_NAME_LEN
], c1
, c2
, c3
, c4
;
505 get_usage_chars(class, &c1
, &c2
, &c3
, &c4
);
509 name
= __get_key_name(class->key
, str
);
510 printk(" (%s", name
);
512 printk(" (%s", name
);
513 if (class->name_version
> 1)
514 printk("#%d", class->name_version
);
516 printk("/%d", class->subclass
);
518 printk("){%c%c%c%c}", c1
, c2
, c3
, c4
);
521 static void print_lockdep_cache(struct lockdep_map
*lock
)
524 char str
[KSYM_NAME_LEN
];
528 name
= __get_key_name(lock
->key
->subkeys
, str
);
533 static void print_lock(struct held_lock
*hlock
)
535 print_lock_name(hlock_class(hlock
));
537 print_ip_sym(hlock
->acquire_ip
);
540 static void lockdep_print_held_locks(struct task_struct
*curr
)
542 int i
, depth
= curr
->lockdep_depth
;
545 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
548 printk("%d lock%s held by %s/%d:\n",
549 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
551 for (i
= 0; i
< depth
; i
++) {
553 print_lock(curr
->held_locks
+ i
);
557 static void print_lock_class_header(struct lock_class
*class, int depth
)
561 printk("%*s->", depth
, "");
562 print_lock_name(class);
563 printk(" ops: %lu", class->ops
);
566 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
567 if (class->usage_mask
& (1 << bit
)) {
570 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
571 len
+= printk(" at:\n");
572 print_stack_trace(class->usage_traces
+ bit
, len
);
575 printk("%*s }\n", depth
, "");
577 printk("%*s ... key at: ",depth
,"");
578 print_ip_sym((unsigned long)class->key
);
582 * printk all lock dependencies starting at <entry>:
584 static void print_lock_dependencies(struct lock_class
*class, int depth
)
586 struct lock_list
*entry
;
588 if (lockdep_dependency_visit(class, depth
))
591 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
594 print_lock_class_header(class, depth
);
596 list_for_each_entry(entry
, &class->locks_after
, entry
) {
597 if (DEBUG_LOCKS_WARN_ON(!entry
->class))
600 print_lock_dependencies(entry
->class, depth
+ 1);
602 printk("%*s ... acquired at:\n",depth
,"");
603 print_stack_trace(&entry
->trace
, 2);
608 static void print_kernel_version(void)
610 printk("%s %.*s\n", init_utsname()->release
,
611 (int)strcspn(init_utsname()->version
, " "),
612 init_utsname()->version
);
615 static int very_verbose(struct lock_class
*class)
618 return class_filter(class);
624 * Is this the address of a static object:
626 static int static_obj(void *obj
)
628 unsigned long start
= (unsigned long) &_stext
,
629 end
= (unsigned long) &_end
,
630 addr
= (unsigned long) obj
;
638 if ((addr
>= start
) && (addr
< end
))
645 for_each_possible_cpu(i
) {
646 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
647 end
= (unsigned long) &__per_cpu_start
+ PERCPU_ENOUGH_ROOM
650 if ((addr
>= start
) && (addr
< end
))
658 return is_module_address(addr
);
662 * To make lock name printouts unique, we calculate a unique
663 * class->name_version generation counter:
665 static int count_matching_names(struct lock_class
*new_class
)
667 struct lock_class
*class;
670 if (!new_class
->name
)
673 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
674 if (new_class
->key
- new_class
->subclass
== class->key
)
675 return class->name_version
;
676 if (class->name
&& !strcmp(class->name
, new_class
->name
))
677 count
= max(count
, class->name_version
);
684 * Register a lock's class in the hash-table, if the class is not present
685 * yet. Otherwise we look it up. We cache the result in the lock object
686 * itself, so actual lookup of the hash should be once per lock object.
688 static inline struct lock_class
*
689 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
691 struct lockdep_subclass_key
*key
;
692 struct list_head
*hash_head
;
693 struct lock_class
*class;
695 #ifdef CONFIG_DEBUG_LOCKDEP
697 * If the architecture calls into lockdep before initializing
698 * the hashes then we'll warn about it later. (we cannot printk
701 if (unlikely(!lockdep_initialized
)) {
703 lockdep_init_error
= 1;
704 save_stack_trace(&lockdep_init_trace
);
709 * Static locks do not have their class-keys yet - for them the key
710 * is the lock object itself:
712 if (unlikely(!lock
->key
))
713 lock
->key
= (void *)lock
;
716 * NOTE: the class-key must be unique. For dynamic locks, a static
717 * lock_class_key variable is passed in through the mutex_init()
718 * (or spin_lock_init()) call - which acts as the key. For static
719 * locks we use the lock object itself as the key.
721 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
722 sizeof(struct lockdep_map
));
724 key
= lock
->key
->subkeys
+ subclass
;
726 hash_head
= classhashentry(key
);
729 * We can walk the hash lockfree, because the hash only
730 * grows, and we are careful when adding entries to the end:
732 list_for_each_entry(class, hash_head
, hash_entry
) {
733 if (class->key
== key
) {
734 WARN_ON_ONCE(class->name
!= lock
->name
);
743 * Register a lock's class in the hash-table, if the class is not present
744 * yet. Otherwise we look it up. We cache the result in the lock object
745 * itself, so actual lookup of the hash should be once per lock object.
747 static inline struct lock_class
*
748 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
750 struct lockdep_subclass_key
*key
;
751 struct list_head
*hash_head
;
752 struct lock_class
*class;
755 class = look_up_lock_class(lock
, subclass
);
760 * Debug-check: all keys must be persistent!
762 if (!static_obj(lock
->key
)) {
764 printk("INFO: trying to register non-static key.\n");
765 printk("the code is fine but needs lockdep annotation.\n");
766 printk("turning off the locking correctness validator.\n");
772 key
= lock
->key
->subkeys
+ subclass
;
773 hash_head
= classhashentry(key
);
775 raw_local_irq_save(flags
);
777 raw_local_irq_restore(flags
);
781 * We have to do the hash-walk again, to avoid races
784 list_for_each_entry(class, hash_head
, hash_entry
)
785 if (class->key
== key
)
788 * Allocate a new key from the static array, and add it to
791 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
792 if (!debug_locks_off_graph_unlock()) {
793 raw_local_irq_restore(flags
);
796 raw_local_irq_restore(flags
);
798 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
799 printk("turning off the locking correctness validator.\n");
802 class = lock_classes
+ nr_lock_classes
++;
803 debug_atomic_inc(&nr_unused_locks
);
805 class->name
= lock
->name
;
806 class->subclass
= subclass
;
807 INIT_LIST_HEAD(&class->lock_entry
);
808 INIT_LIST_HEAD(&class->locks_before
);
809 INIT_LIST_HEAD(&class->locks_after
);
810 class->name_version
= count_matching_names(class);
812 * We use RCU's safe list-add method to make
813 * parallel walking of the hash-list safe:
815 list_add_tail_rcu(&class->hash_entry
, hash_head
);
817 * Add it to the global list of classes:
819 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
821 if (verbose(class)) {
823 raw_local_irq_restore(flags
);
825 printk("\nnew class %p: %s", class->key
, class->name
);
826 if (class->name_version
> 1)
827 printk("#%d", class->name_version
);
831 raw_local_irq_save(flags
);
833 raw_local_irq_restore(flags
);
839 raw_local_irq_restore(flags
);
841 if (!subclass
|| force
)
842 lock
->class_cache
= class;
844 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
850 #ifdef CONFIG_PROVE_LOCKING
852 * Allocate a lockdep entry. (assumes the graph_lock held, returns
853 * with NULL on failure)
855 static struct lock_list
*alloc_list_entry(void)
857 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
858 if (!debug_locks_off_graph_unlock())
861 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
862 printk("turning off the locking correctness validator.\n");
865 return list_entries
+ nr_list_entries
++;
869 * Add a new dependency to the head of the list:
871 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
872 struct list_head
*head
, unsigned long ip
, int distance
)
874 struct lock_list
*entry
;
876 * Lock not present yet - get a new dependency struct and
877 * add it to the list:
879 entry
= alloc_list_entry();
883 if (!save_trace(&entry
->trace
))
887 entry
->distance
= distance
;
889 * Since we never remove from the dependency list, the list can
890 * be walked lockless by other CPUs, it's only allocation
891 * that must be protected by the spinlock. But this also means
892 * we must make new entries visible only once writes to the
893 * entry become visible - hence the RCU op:
895 list_add_tail_rcu(&entry
->entry
, head
);
901 * Recursive, forwards-direction lock-dependency checking, used for
902 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
905 * (to keep the stackframe of the recursive functions small we
906 * use these global variables, and we also mark various helper
907 * functions as noinline.)
909 static struct held_lock
*check_source
, *check_target
;
912 * Print a dependency chain entry (this is only done when a deadlock
913 * has been detected):
916 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
918 if (debug_locks_silent
)
920 printk("\n-> #%u", depth
);
921 print_lock_name(target
->class);
923 print_stack_trace(&target
->trace
, 6);
929 * When a circular dependency is detected, print the
933 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
)
935 struct task_struct
*curr
= current
;
937 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
940 printk("\n=======================================================\n");
941 printk( "[ INFO: possible circular locking dependency detected ]\n");
942 print_kernel_version();
943 printk( "-------------------------------------------------------\n");
944 printk("%s/%d is trying to acquire lock:\n",
945 curr
->comm
, task_pid_nr(curr
));
946 print_lock(check_source
);
947 printk("\nbut task is already holding lock:\n");
948 print_lock(check_target
);
949 printk("\nwhich lock already depends on the new lock.\n\n");
950 printk("\nthe existing dependency chain (in reverse order) is:\n");
952 print_circular_bug_entry(entry
, depth
);
957 static noinline
int print_circular_bug_tail(void)
959 struct task_struct
*curr
= current
;
960 struct lock_list
this;
962 if (debug_locks_silent
)
965 this.class = hlock_class(check_source
);
966 if (!save_trace(&this.trace
))
969 print_circular_bug_entry(&this, 0);
971 printk("\nother info that might help us debug this:\n\n");
972 lockdep_print_held_locks(curr
);
974 printk("\nstack backtrace:\n");
980 #define RECURSION_LIMIT 40
982 static int noinline
print_infinite_recursion_bug(void)
984 if (!debug_locks_off_graph_unlock())
992 unsigned long __lockdep_count_forward_deps(struct lock_class
*class,
995 struct lock_list
*entry
;
996 unsigned long ret
= 1;
998 if (lockdep_dependency_visit(class, depth
))
1002 * Recurse this class's dependency list:
1004 list_for_each_entry(entry
, &class->locks_after
, entry
)
1005 ret
+= __lockdep_count_forward_deps(entry
->class, depth
+ 1);
1010 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1012 unsigned long ret
, flags
;
1014 local_irq_save(flags
);
1015 __raw_spin_lock(&lockdep_lock
);
1016 ret
= __lockdep_count_forward_deps(class, 0);
1017 __raw_spin_unlock(&lockdep_lock
);
1018 local_irq_restore(flags
);
1023 unsigned long __lockdep_count_backward_deps(struct lock_class
*class,
1026 struct lock_list
*entry
;
1027 unsigned long ret
= 1;
1029 if (lockdep_dependency_visit(class, depth
))
1032 * Recurse this class's dependency list:
1034 list_for_each_entry(entry
, &class->locks_before
, entry
)
1035 ret
+= __lockdep_count_backward_deps(entry
->class, depth
+ 1);
1040 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1042 unsigned long ret
, flags
;
1044 local_irq_save(flags
);
1045 __raw_spin_lock(&lockdep_lock
);
1046 ret
= __lockdep_count_backward_deps(class, 0);
1047 __raw_spin_unlock(&lockdep_lock
);
1048 local_irq_restore(flags
);
1054 * Prove that the dependency graph starting at <entry> can not
1055 * lead to <target>. Print an error and return 0 if it does.
1058 check_noncircular(struct lock_class
*source
, unsigned int depth
)
1060 struct lock_list
*entry
;
1062 if (lockdep_dependency_visit(source
, depth
))
1065 debug_atomic_inc(&nr_cyclic_check_recursions
);
1066 if (depth
> max_recursion_depth
)
1067 max_recursion_depth
= depth
;
1068 if (depth
>= RECURSION_LIMIT
)
1069 return print_infinite_recursion_bug();
1071 * Check this lock's dependency list:
1073 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1074 if (entry
->class == hlock_class(check_target
))
1075 return print_circular_bug_header(entry
, depth
+1);
1076 debug_atomic_inc(&nr_cyclic_checks
);
1077 if (!check_noncircular(entry
->class, depth
+1))
1078 return print_circular_bug_entry(entry
, depth
+1);
1083 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1085 * Forwards and backwards subgraph searching, for the purposes of
1086 * proving that two subgraphs can be connected by a new dependency
1087 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1089 static enum lock_usage_bit find_usage_bit
;
1090 static struct lock_class
*forwards_match
, *backwards_match
;
1093 * Find a node in the forwards-direction dependency sub-graph starting
1094 * at <source> that matches <find_usage_bit>.
1096 * Return 2 if such a node exists in the subgraph, and put that node
1097 * into <forwards_match>.
1099 * Return 1 otherwise and keep <forwards_match> unchanged.
1100 * Return 0 on error.
1103 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
1105 struct lock_list
*entry
;
1108 if (lockdep_dependency_visit(source
, depth
))
1111 if (depth
> max_recursion_depth
)
1112 max_recursion_depth
= depth
;
1113 if (depth
>= RECURSION_LIMIT
)
1114 return print_infinite_recursion_bug();
1116 debug_atomic_inc(&nr_find_usage_forwards_checks
);
1117 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1118 forwards_match
= source
;
1123 * Check this lock's dependency list:
1125 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1126 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
1127 ret
= find_usage_forwards(entry
->class, depth
+1);
1128 if (ret
== 2 || ret
== 0)
1135 * Find a node in the backwards-direction dependency sub-graph starting
1136 * at <source> that matches <find_usage_bit>.
1138 * Return 2 if such a node exists in the subgraph, and put that node
1139 * into <backwards_match>.
1141 * Return 1 otherwise and keep <backwards_match> unchanged.
1142 * Return 0 on error.
1145 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
1147 struct lock_list
*entry
;
1150 if (lockdep_dependency_visit(source
, depth
))
1153 if (!__raw_spin_is_locked(&lockdep_lock
))
1154 return DEBUG_LOCKS_WARN_ON(1);
1156 if (depth
> max_recursion_depth
)
1157 max_recursion_depth
= depth
;
1158 if (depth
>= RECURSION_LIMIT
)
1159 return print_infinite_recursion_bug();
1161 debug_atomic_inc(&nr_find_usage_backwards_checks
);
1162 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1163 backwards_match
= source
;
1167 if (!source
&& debug_locks_off_graph_unlock()) {
1173 * Check this lock's dependency list:
1175 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
1176 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
1177 ret
= find_usage_backwards(entry
->class, depth
+1);
1178 if (ret
== 2 || ret
== 0)
1185 print_bad_irq_dependency(struct task_struct
*curr
,
1186 struct held_lock
*prev
,
1187 struct held_lock
*next
,
1188 enum lock_usage_bit bit1
,
1189 enum lock_usage_bit bit2
,
1190 const char *irqclass
)
1192 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1195 printk("\n======================================================\n");
1196 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1197 irqclass
, irqclass
);
1198 print_kernel_version();
1199 printk( "------------------------------------------------------\n");
1200 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1201 curr
->comm
, task_pid_nr(curr
),
1202 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1203 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1204 curr
->hardirqs_enabled
,
1205 curr
->softirqs_enabled
);
1208 printk("\nand this task is already holding:\n");
1210 printk("which would create a new lock dependency:\n");
1211 print_lock_name(hlock_class(prev
));
1213 print_lock_name(hlock_class(next
));
1216 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1218 print_lock_name(backwards_match
);
1219 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1221 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
1223 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1224 print_lock_name(forwards_match
);
1225 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1228 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
1230 printk("\nother info that might help us debug this:\n\n");
1231 lockdep_print_held_locks(curr
);
1233 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
1234 print_lock_dependencies(backwards_match
, 0);
1236 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
1237 print_lock_dependencies(forwards_match
, 0);
1239 printk("\nstack backtrace:\n");
1246 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1247 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1248 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1252 find_usage_bit
= bit_backwards
;
1253 /* fills in <backwards_match> */
1254 ret
= find_usage_backwards(hlock_class(prev
), 0);
1255 if (!ret
|| ret
== 1)
1258 find_usage_bit
= bit_forwards
;
1259 ret
= find_usage_forwards(hlock_class(next
), 0);
1260 if (!ret
|| ret
== 1)
1263 return print_bad_irq_dependency(curr
, prev
, next
,
1264 bit_backwards
, bit_forwards
, irqclass
);
1268 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1269 struct held_lock
*next
)
1272 * Prove that the new dependency does not connect a hardirq-safe
1273 * lock with a hardirq-unsafe lock - to achieve this we search
1274 * the backwards-subgraph starting at <prev>, and the
1275 * forwards-subgraph starting at <next>:
1277 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ
,
1278 LOCK_ENABLED_HARDIRQS
, "hard"))
1282 * Prove that the new dependency does not connect a hardirq-safe-read
1283 * lock with a hardirq-unsafe lock - to achieve this we search
1284 * the backwards-subgraph starting at <prev>, and the
1285 * forwards-subgraph starting at <next>:
1287 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ_READ
,
1288 LOCK_ENABLED_HARDIRQS
, "hard-read"))
1292 * Prove that the new dependency does not connect a softirq-safe
1293 * lock with a softirq-unsafe lock - to achieve this we search
1294 * the backwards-subgraph starting at <prev>, and the
1295 * forwards-subgraph starting at <next>:
1297 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ
,
1298 LOCK_ENABLED_SOFTIRQS
, "soft"))
1301 * Prove that the new dependency does not connect a softirq-safe-read
1302 * lock with a softirq-unsafe lock - to achieve this we search
1303 * the backwards-subgraph starting at <prev>, and the
1304 * forwards-subgraph starting at <next>:
1306 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ_READ
,
1307 LOCK_ENABLED_SOFTIRQS
, "soft"))
1313 static void inc_chains(void)
1315 if (current
->hardirq_context
)
1316 nr_hardirq_chains
++;
1318 if (current
->softirq_context
)
1319 nr_softirq_chains
++;
1321 nr_process_chains
++;
1328 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1329 struct held_lock
*next
)
1334 static inline void inc_chains(void)
1336 nr_process_chains
++;
1342 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1343 struct held_lock
*next
)
1345 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1348 printk("\n=============================================\n");
1349 printk( "[ INFO: possible recursive locking detected ]\n");
1350 print_kernel_version();
1351 printk( "---------------------------------------------\n");
1352 printk("%s/%d is trying to acquire lock:\n",
1353 curr
->comm
, task_pid_nr(curr
));
1355 printk("\nbut task is already holding lock:\n");
1358 printk("\nother info that might help us debug this:\n");
1359 lockdep_print_held_locks(curr
);
1361 printk("\nstack backtrace:\n");
1368 * Check whether we are holding such a class already.
1370 * (Note that this has to be done separately, because the graph cannot
1371 * detect such classes of deadlocks.)
1373 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1376 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1377 struct lockdep_map
*next_instance
, int read
)
1379 struct held_lock
*prev
;
1380 struct held_lock
*nest
= NULL
;
1383 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1384 prev
= curr
->held_locks
+ i
;
1386 if (prev
->instance
== next
->nest_lock
)
1389 if (hlock_class(prev
) != hlock_class(next
))
1393 * Allow read-after-read recursion of the same
1394 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1396 if ((read
== 2) && prev
->read
)
1400 * We're holding the nest_lock, which serializes this lock's
1401 * nesting behaviour.
1406 return print_deadlock_bug(curr
, prev
, next
);
1412 * There was a chain-cache miss, and we are about to add a new dependency
1413 * to a previous lock. We recursively validate the following rules:
1415 * - would the adding of the <prev> -> <next> dependency create a
1416 * circular dependency in the graph? [== circular deadlock]
1418 * - does the new prev->next dependency connect any hardirq-safe lock
1419 * (in the full backwards-subgraph starting at <prev>) with any
1420 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1421 * <next>)? [== illegal lock inversion with hardirq contexts]
1423 * - does the new prev->next dependency connect any softirq-safe lock
1424 * (in the full backwards-subgraph starting at <prev>) with any
1425 * softirq-unsafe lock (in the full forwards-subgraph starting at
1426 * <next>)? [== illegal lock inversion with softirq contexts]
1428 * any of these scenarios could lead to a deadlock.
1430 * Then if all the validations pass, we add the forwards and backwards
1434 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1435 struct held_lock
*next
, int distance
)
1437 struct lock_list
*entry
;
1441 * Prove that the new <prev> -> <next> dependency would not
1442 * create a circular dependency in the graph. (We do this by
1443 * forward-recursing into the graph starting at <next>, and
1444 * checking whether we can reach <prev>.)
1446 * We are using global variables to control the recursion, to
1447 * keep the stackframe size of the recursive functions low:
1449 check_source
= next
;
1450 check_target
= prev
;
1451 if (!(check_noncircular(hlock_class(next
), 0)))
1452 return print_circular_bug_tail();
1454 if (!check_prev_add_irq(curr
, prev
, next
))
1458 * For recursive read-locks we do all the dependency checks,
1459 * but we dont store read-triggered dependencies (only
1460 * write-triggered dependencies). This ensures that only the
1461 * write-side dependencies matter, and that if for example a
1462 * write-lock never takes any other locks, then the reads are
1463 * equivalent to a NOP.
1465 if (next
->read
== 2 || prev
->read
== 2)
1468 * Is the <prev> -> <next> dependency already present?
1470 * (this may occur even though this is a new chain: consider
1471 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1472 * chains - the second one will be new, but L1 already has
1473 * L2 added to its dependency list, due to the first chain.)
1475 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1476 if (entry
->class == hlock_class(next
)) {
1478 entry
->distance
= 1;
1484 * Ok, all validations passed, add the new lock
1485 * to the previous lock's dependency list:
1487 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1488 &hlock_class(prev
)->locks_after
,
1489 next
->acquire_ip
, distance
);
1494 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1495 &hlock_class(next
)->locks_before
,
1496 next
->acquire_ip
, distance
);
1501 * Debugging printouts:
1503 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1505 printk("\n new dependency: ");
1506 print_lock_name(hlock_class(prev
));
1508 print_lock_name(hlock_class(next
));
1511 return graph_lock();
1517 * Add the dependency to all directly-previous locks that are 'relevant'.
1518 * The ones that are relevant are (in increasing distance from curr):
1519 * all consecutive trylock entries and the final non-trylock entry - or
1520 * the end of this context's lock-chain - whichever comes first.
1523 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1525 int depth
= curr
->lockdep_depth
;
1526 struct held_lock
*hlock
;
1531 * Depth must not be zero for a non-head lock:
1536 * At least two relevant locks must exist for this
1539 if (curr
->held_locks
[depth
].irq_context
!=
1540 curr
->held_locks
[depth
-1].irq_context
)
1544 int distance
= curr
->lockdep_depth
- depth
+ 1;
1545 hlock
= curr
->held_locks
+ depth
-1;
1547 * Only non-recursive-read entries get new dependencies
1550 if (hlock
->read
!= 2) {
1551 if (!check_prev_add(curr
, hlock
, next
, distance
))
1554 * Stop after the first non-trylock entry,
1555 * as non-trylock entries have added their
1556 * own direct dependencies already, so this
1557 * lock is connected to them indirectly:
1559 if (!hlock
->trylock
)
1564 * End of lock-stack?
1569 * Stop the search if we cross into another context:
1571 if (curr
->held_locks
[depth
].irq_context
!=
1572 curr
->held_locks
[depth
-1].irq_context
)
1577 if (!debug_locks_off_graph_unlock())
1585 unsigned long nr_lock_chains
;
1586 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1587 int nr_chain_hlocks
;
1588 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1590 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1592 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1596 * Look up a dependency chain. If the key is not present yet then
1597 * add it and return 1 - in this case the new dependency chain is
1598 * validated. If the key is already hashed, return 0.
1599 * (On return with 1 graph_lock is held.)
1601 static inline int lookup_chain_cache(struct task_struct
*curr
,
1602 struct held_lock
*hlock
,
1605 struct lock_class
*class = hlock_class(hlock
);
1606 struct list_head
*hash_head
= chainhashentry(chain_key
);
1607 struct lock_chain
*chain
;
1608 struct held_lock
*hlock_curr
, *hlock_next
;
1611 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1614 * We can walk it lock-free, because entries only get added
1617 list_for_each_entry(chain
, hash_head
, entry
) {
1618 if (chain
->chain_key
== chain_key
) {
1620 debug_atomic_inc(&chain_lookup_hits
);
1621 if (very_verbose(class))
1622 printk("\nhash chain already cached, key: "
1623 "%016Lx tail class: [%p] %s\n",
1624 (unsigned long long)chain_key
,
1625 class->key
, class->name
);
1629 if (very_verbose(class))
1630 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1631 (unsigned long long)chain_key
, class->key
, class->name
);
1633 * Allocate a new chain entry from the static array, and add
1639 * We have to walk the chain again locked - to avoid duplicates:
1641 list_for_each_entry(chain
, hash_head
, entry
) {
1642 if (chain
->chain_key
== chain_key
) {
1647 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1648 if (!debug_locks_off_graph_unlock())
1651 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1652 printk("turning off the locking correctness validator.\n");
1655 chain
= lock_chains
+ nr_lock_chains
++;
1656 chain
->chain_key
= chain_key
;
1657 chain
->irq_context
= hlock
->irq_context
;
1658 /* Find the first held_lock of current chain */
1660 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
1661 hlock_curr
= curr
->held_locks
+ i
;
1662 if (hlock_curr
->irq_context
!= hlock_next
->irq_context
)
1667 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
1668 cn
= nr_chain_hlocks
;
1669 while (cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
) {
1670 n
= cmpxchg(&nr_chain_hlocks
, cn
, cn
+ chain
->depth
);
1675 if (likely(cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
1677 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
1678 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
1679 chain_hlocks
[chain
->base
+ j
] = lock_id
;
1681 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
1683 list_add_tail_rcu(&chain
->entry
, hash_head
);
1684 debug_atomic_inc(&chain_lookup_misses
);
1690 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
1691 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
1694 * Trylock needs to maintain the stack of held locks, but it
1695 * does not add new dependencies, because trylock can be done
1698 * We look up the chain_key and do the O(N^2) check and update of
1699 * the dependencies only if this is a new dependency chain.
1700 * (If lookup_chain_cache() returns with 1 it acquires
1701 * graph_lock for us)
1703 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
1704 lookup_chain_cache(curr
, hlock
, chain_key
)) {
1706 * Check whether last held lock:
1708 * - is irq-safe, if this lock is irq-unsafe
1709 * - is softirq-safe, if this lock is hardirq-unsafe
1711 * And check whether the new lock's dependency graph
1712 * could lead back to the previous lock.
1714 * any of these scenarios could lead to a deadlock. If
1717 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
1722 * Mark recursive read, as we jump over it when
1723 * building dependencies (just like we jump over
1729 * Add dependency only if this lock is not the head
1730 * of the chain, and if it's not a secondary read-lock:
1732 if (!chain_head
&& ret
!= 2)
1733 if (!check_prevs_add(curr
, hlock
))
1737 /* after lookup_chain_cache(): */
1738 if (unlikely(!debug_locks
))
1744 static inline int validate_chain(struct task_struct
*curr
,
1745 struct lockdep_map
*lock
, struct held_lock
*hlock
,
1746 int chain_head
, u64 chain_key
)
1753 * We are building curr_chain_key incrementally, so double-check
1754 * it from scratch, to make sure that it's done correctly:
1756 static void check_chain_key(struct task_struct
*curr
)
1758 #ifdef CONFIG_DEBUG_LOCKDEP
1759 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1763 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1764 hlock
= curr
->held_locks
+ i
;
1765 if (chain_key
!= hlock
->prev_chain_key
) {
1767 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1768 curr
->lockdep_depth
, i
,
1769 (unsigned long long)chain_key
,
1770 (unsigned long long)hlock
->prev_chain_key
);
1773 id
= hlock
->class_idx
- 1;
1774 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
1777 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1778 hlock
->irq_context
))
1780 chain_key
= iterate_chain_key(chain_key
, id
);
1783 if (chain_key
!= curr
->curr_chain_key
) {
1785 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1786 curr
->lockdep_depth
, i
,
1787 (unsigned long long)chain_key
,
1788 (unsigned long long)curr
->curr_chain_key
);
1794 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1795 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1797 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1800 printk("\n=================================\n");
1801 printk( "[ INFO: inconsistent lock state ]\n");
1802 print_kernel_version();
1803 printk( "---------------------------------\n");
1805 printk("inconsistent {%s} -> {%s} usage.\n",
1806 usage_str
[prev_bit
], usage_str
[new_bit
]);
1808 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1809 curr
->comm
, task_pid_nr(curr
),
1810 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1811 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1812 trace_hardirqs_enabled(curr
),
1813 trace_softirqs_enabled(curr
));
1816 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1817 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
1819 print_irqtrace_events(curr
);
1820 printk("\nother info that might help us debug this:\n");
1821 lockdep_print_held_locks(curr
);
1823 printk("\nstack backtrace:\n");
1830 * Print out an error if an invalid bit is set:
1833 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1834 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1836 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
1837 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1841 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1842 enum lock_usage_bit new_bit
);
1844 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1847 * print irq inversion bug:
1850 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
1851 struct held_lock
*this, int forwards
,
1852 const char *irqclass
)
1854 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1857 printk("\n=========================================================\n");
1858 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1859 print_kernel_version();
1860 printk( "---------------------------------------------------------\n");
1861 printk("%s/%d just changed the state of lock:\n",
1862 curr
->comm
, task_pid_nr(curr
));
1865 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass
);
1867 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass
);
1868 print_lock_name(other
);
1869 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1871 printk("\nother info that might help us debug this:\n");
1872 lockdep_print_held_locks(curr
);
1874 printk("\nthe first lock's dependencies:\n");
1875 print_lock_dependencies(hlock_class(this), 0);
1877 printk("\nthe second lock's dependencies:\n");
1878 print_lock_dependencies(other
, 0);
1880 printk("\nstack backtrace:\n");
1887 * Prove that in the forwards-direction subgraph starting at <this>
1888 * there is no lock matching <mask>:
1891 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
1892 enum lock_usage_bit bit
, const char *irqclass
)
1896 find_usage_bit
= bit
;
1897 /* fills in <forwards_match> */
1898 ret
= find_usage_forwards(hlock_class(this), 0);
1899 if (!ret
|| ret
== 1)
1902 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
1906 * Prove that in the backwards-direction subgraph starting at <this>
1907 * there is no lock matching <mask>:
1910 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
1911 enum lock_usage_bit bit
, const char *irqclass
)
1915 find_usage_bit
= bit
;
1916 /* fills in <backwards_match> */
1917 ret
= find_usage_backwards(hlock_class(this), 0);
1918 if (!ret
|| ret
== 1)
1921 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
1924 void print_irqtrace_events(struct task_struct
*curr
)
1926 printk("irq event stamp: %u\n", curr
->irq_events
);
1927 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
1928 print_ip_sym(curr
->hardirq_enable_ip
);
1929 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
1930 print_ip_sym(curr
->hardirq_disable_ip
);
1931 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
1932 print_ip_sym(curr
->softirq_enable_ip
);
1933 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
1934 print_ip_sym(curr
->softirq_disable_ip
);
1937 static int hardirq_verbose(struct lock_class
*class)
1940 return class_filter(class);
1945 static int softirq_verbose(struct lock_class
*class)
1948 return class_filter(class);
1953 #define STRICT_READ_CHECKS 1
1955 static int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
1956 enum lock_usage_bit new_bit
)
1961 case LOCK_USED_IN_HARDIRQ
:
1962 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1964 if (!valid_state(curr
, this, new_bit
,
1965 LOCK_ENABLED_HARDIRQS_READ
))
1968 * just marked it hardirq-safe, check that this lock
1969 * took no hardirq-unsafe lock in the past:
1971 if (!check_usage_forwards(curr
, this,
1972 LOCK_ENABLED_HARDIRQS
, "hard"))
1974 #if STRICT_READ_CHECKS
1976 * just marked it hardirq-safe, check that this lock
1977 * took no hardirq-unsafe-read lock in the past:
1979 if (!check_usage_forwards(curr
, this,
1980 LOCK_ENABLED_HARDIRQS_READ
, "hard-read"))
1983 if (hardirq_verbose(hlock_class(this)))
1986 case LOCK_USED_IN_SOFTIRQ
:
1987 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1989 if (!valid_state(curr
, this, new_bit
,
1990 LOCK_ENABLED_SOFTIRQS_READ
))
1993 * just marked it softirq-safe, check that this lock
1994 * took no softirq-unsafe lock in the past:
1996 if (!check_usage_forwards(curr
, this,
1997 LOCK_ENABLED_SOFTIRQS
, "soft"))
1999 #if STRICT_READ_CHECKS
2001 * just marked it softirq-safe, check that this lock
2002 * took no softirq-unsafe-read lock in the past:
2004 if (!check_usage_forwards(curr
, this,
2005 LOCK_ENABLED_SOFTIRQS_READ
, "soft-read"))
2008 if (softirq_verbose(hlock_class(this)))
2011 case LOCK_USED_IN_HARDIRQ_READ
:
2012 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
2015 * just marked it hardirq-read-safe, check that this lock
2016 * took no hardirq-unsafe lock in the past:
2018 if (!check_usage_forwards(curr
, this,
2019 LOCK_ENABLED_HARDIRQS
, "hard"))
2021 if (hardirq_verbose(hlock_class(this)))
2024 case LOCK_USED_IN_SOFTIRQ_READ
:
2025 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
2028 * just marked it softirq-read-safe, check that this lock
2029 * took no softirq-unsafe lock in the past:
2031 if (!check_usage_forwards(curr
, this,
2032 LOCK_ENABLED_SOFTIRQS
, "soft"))
2034 if (softirq_verbose(hlock_class(this)))
2037 case LOCK_ENABLED_HARDIRQS
:
2038 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
2040 if (!valid_state(curr
, this, new_bit
,
2041 LOCK_USED_IN_HARDIRQ_READ
))
2044 * just marked it hardirq-unsafe, check that no hardirq-safe
2045 * lock in the system ever took it in the past:
2047 if (!check_usage_backwards(curr
, this,
2048 LOCK_USED_IN_HARDIRQ
, "hard"))
2050 #if STRICT_READ_CHECKS
2052 * just marked it hardirq-unsafe, check that no
2053 * hardirq-safe-read lock in the system ever took
2056 if (!check_usage_backwards(curr
, this,
2057 LOCK_USED_IN_HARDIRQ_READ
, "hard-read"))
2060 if (hardirq_verbose(hlock_class(this)))
2063 case LOCK_ENABLED_SOFTIRQS
:
2064 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
2066 if (!valid_state(curr
, this, new_bit
,
2067 LOCK_USED_IN_SOFTIRQ_READ
))
2070 * just marked it softirq-unsafe, check that no softirq-safe
2071 * lock in the system ever took it in the past:
2073 if (!check_usage_backwards(curr
, this,
2074 LOCK_USED_IN_SOFTIRQ
, "soft"))
2076 #if STRICT_READ_CHECKS
2078 * just marked it softirq-unsafe, check that no
2079 * softirq-safe-read lock in the system ever took
2082 if (!check_usage_backwards(curr
, this,
2083 LOCK_USED_IN_SOFTIRQ_READ
, "soft-read"))
2086 if (softirq_verbose(hlock_class(this)))
2089 case LOCK_ENABLED_HARDIRQS_READ
:
2090 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
2092 #if STRICT_READ_CHECKS
2094 * just marked it hardirq-read-unsafe, check that no
2095 * hardirq-safe lock in the system ever took it in the past:
2097 if (!check_usage_backwards(curr
, this,
2098 LOCK_USED_IN_HARDIRQ
, "hard"))
2101 if (hardirq_verbose(hlock_class(this)))
2104 case LOCK_ENABLED_SOFTIRQS_READ
:
2105 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
2107 #if STRICT_READ_CHECKS
2109 * just marked it softirq-read-unsafe, check that no
2110 * softirq-safe lock in the system ever took it in the past:
2112 if (!check_usage_backwards(curr
, this,
2113 LOCK_USED_IN_SOFTIRQ
, "soft"))
2116 if (softirq_verbose(hlock_class(this)))
2128 * Mark all held locks with a usage bit:
2131 mark_held_locks(struct task_struct
*curr
, int hardirq
)
2133 enum lock_usage_bit usage_bit
;
2134 struct held_lock
*hlock
;
2137 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2138 hlock
= curr
->held_locks
+ i
;
2142 usage_bit
= LOCK_ENABLED_HARDIRQS_READ
;
2144 usage_bit
= LOCK_ENABLED_HARDIRQS
;
2147 usage_bit
= LOCK_ENABLED_SOFTIRQS_READ
;
2149 usage_bit
= LOCK_ENABLED_SOFTIRQS
;
2151 if (!mark_lock(curr
, hlock
, usage_bit
))
2159 * Debugging helper: via this flag we know that we are in
2160 * 'early bootup code', and will warn about any invalid irqs-on event:
2162 static int early_boot_irqs_enabled
;
2164 void early_boot_irqs_off(void)
2166 early_boot_irqs_enabled
= 0;
2169 void early_boot_irqs_on(void)
2171 early_boot_irqs_enabled
= 1;
2175 * Hardirqs will be enabled:
2177 void trace_hardirqs_on_caller(unsigned long ip
)
2179 struct task_struct
*curr
= current
;
2181 time_hardirqs_on(CALLER_ADDR0
, ip
);
2183 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2186 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
2189 if (unlikely(curr
->hardirqs_enabled
)) {
2190 debug_atomic_inc(&redundant_hardirqs_on
);
2193 /* we'll do an OFF -> ON transition: */
2194 curr
->hardirqs_enabled
= 1;
2196 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2198 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2201 * We are going to turn hardirqs on, so set the
2202 * usage bit for all held locks:
2204 if (!mark_held_locks(curr
, 1))
2207 * If we have softirqs enabled, then set the usage
2208 * bit for all held locks. (disabled hardirqs prevented
2209 * this bit from being set before)
2211 if (curr
->softirqs_enabled
)
2212 if (!mark_held_locks(curr
, 0))
2215 curr
->hardirq_enable_ip
= ip
;
2216 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2217 debug_atomic_inc(&hardirqs_on_events
);
2219 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2221 void trace_hardirqs_on(void)
2223 trace_hardirqs_on_caller(CALLER_ADDR0
);
2225 EXPORT_SYMBOL(trace_hardirqs_on
);
2228 * Hardirqs were disabled:
2230 void trace_hardirqs_off_caller(unsigned long ip
)
2232 struct task_struct
*curr
= current
;
2234 time_hardirqs_off(CALLER_ADDR0
, ip
);
2236 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2239 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2242 if (curr
->hardirqs_enabled
) {
2244 * We have done an ON -> OFF transition:
2246 curr
->hardirqs_enabled
= 0;
2247 curr
->hardirq_disable_ip
= ip
;
2248 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2249 debug_atomic_inc(&hardirqs_off_events
);
2251 debug_atomic_inc(&redundant_hardirqs_off
);
2253 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2255 void trace_hardirqs_off(void)
2257 trace_hardirqs_off_caller(CALLER_ADDR0
);
2259 EXPORT_SYMBOL(trace_hardirqs_off
);
2262 * Softirqs will be enabled:
2264 void trace_softirqs_on(unsigned long ip
)
2266 struct task_struct
*curr
= current
;
2268 if (unlikely(!debug_locks
))
2271 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2274 if (curr
->softirqs_enabled
) {
2275 debug_atomic_inc(&redundant_softirqs_on
);
2280 * We'll do an OFF -> ON transition:
2282 curr
->softirqs_enabled
= 1;
2283 curr
->softirq_enable_ip
= ip
;
2284 curr
->softirq_enable_event
= ++curr
->irq_events
;
2285 debug_atomic_inc(&softirqs_on_events
);
2287 * We are going to turn softirqs on, so set the
2288 * usage bit for all held locks, if hardirqs are
2291 if (curr
->hardirqs_enabled
)
2292 mark_held_locks(curr
, 0);
2296 * Softirqs were disabled:
2298 void trace_softirqs_off(unsigned long ip
)
2300 struct task_struct
*curr
= current
;
2302 if (unlikely(!debug_locks
))
2305 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2308 if (curr
->softirqs_enabled
) {
2310 * We have done an ON -> OFF transition:
2312 curr
->softirqs_enabled
= 0;
2313 curr
->softirq_disable_ip
= ip
;
2314 curr
->softirq_disable_event
= ++curr
->irq_events
;
2315 debug_atomic_inc(&softirqs_off_events
);
2316 DEBUG_LOCKS_WARN_ON(!softirq_count());
2318 debug_atomic_inc(&redundant_softirqs_off
);
2321 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2324 * If non-trylock use in a hardirq or softirq context, then
2325 * mark the lock as used in these contexts:
2327 if (!hlock
->trylock
) {
2329 if (curr
->hardirq_context
)
2330 if (!mark_lock(curr
, hlock
,
2331 LOCK_USED_IN_HARDIRQ_READ
))
2333 if (curr
->softirq_context
)
2334 if (!mark_lock(curr
, hlock
,
2335 LOCK_USED_IN_SOFTIRQ_READ
))
2338 if (curr
->hardirq_context
)
2339 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2341 if (curr
->softirq_context
)
2342 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2346 if (!hlock
->hardirqs_off
) {
2348 if (!mark_lock(curr
, hlock
,
2349 LOCK_ENABLED_HARDIRQS_READ
))
2351 if (curr
->softirqs_enabled
)
2352 if (!mark_lock(curr
, hlock
,
2353 LOCK_ENABLED_SOFTIRQS_READ
))
2356 if (!mark_lock(curr
, hlock
,
2357 LOCK_ENABLED_HARDIRQS
))
2359 if (curr
->softirqs_enabled
)
2360 if (!mark_lock(curr
, hlock
,
2361 LOCK_ENABLED_SOFTIRQS
))
2369 static int separate_irq_context(struct task_struct
*curr
,
2370 struct held_lock
*hlock
)
2372 unsigned int depth
= curr
->lockdep_depth
;
2375 * Keep track of points where we cross into an interrupt context:
2377 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2378 curr
->softirq_context
;
2380 struct held_lock
*prev_hlock
;
2382 prev_hlock
= curr
->held_locks
+ depth
-1;
2384 * If we cross into another context, reset the
2385 * hash key (this also prevents the checking and the
2386 * adding of the dependency to 'prev'):
2388 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2397 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2398 enum lock_usage_bit new_bit
)
2404 static inline int mark_irqflags(struct task_struct
*curr
,
2405 struct held_lock
*hlock
)
2410 static inline int separate_irq_context(struct task_struct
*curr
,
2411 struct held_lock
*hlock
)
2419 * Mark a lock with a usage bit, and validate the state transition:
2421 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2422 enum lock_usage_bit new_bit
)
2424 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2427 * If already set then do not dirty the cacheline,
2428 * nor do any checks:
2430 if (likely(hlock_class(this)->usage_mask
& new_mask
))
2436 * Make sure we didnt race:
2438 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
2443 hlock_class(this)->usage_mask
|= new_mask
;
2445 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
2449 case LOCK_USED_IN_HARDIRQ
:
2450 case LOCK_USED_IN_SOFTIRQ
:
2451 case LOCK_USED_IN_HARDIRQ_READ
:
2452 case LOCK_USED_IN_SOFTIRQ_READ
:
2453 case LOCK_ENABLED_HARDIRQS
:
2454 case LOCK_ENABLED_SOFTIRQS
:
2455 case LOCK_ENABLED_HARDIRQS_READ
:
2456 case LOCK_ENABLED_SOFTIRQS_READ
:
2457 ret
= mark_lock_irq(curr
, this, new_bit
);
2462 debug_atomic_dec(&nr_unused_locks
);
2465 if (!debug_locks_off_graph_unlock())
2474 * We must printk outside of the graph_lock:
2477 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2479 print_irqtrace_events(curr
);
2487 * Initialize a lock instance's lock-class mapping info:
2489 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2490 struct lock_class_key
*key
, int subclass
)
2492 if (unlikely(!debug_locks
))
2495 if (DEBUG_LOCKS_WARN_ON(!key
))
2497 if (DEBUG_LOCKS_WARN_ON(!name
))
2500 * Sanity check, the lock-class key must be persistent:
2502 if (!static_obj(key
)) {
2503 printk("BUG: key %p not in .data!\n", key
);
2504 DEBUG_LOCKS_WARN_ON(1);
2509 lock
->class_cache
= NULL
;
2510 #ifdef CONFIG_LOCK_STAT
2511 lock
->cpu
= raw_smp_processor_id();
2514 register_lock_class(lock
, subclass
, 1);
2517 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2520 * This gets called for every mutex_lock*()/spin_lock*() operation.
2521 * We maintain the dependency maps and validate the locking attempt:
2523 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2524 int trylock
, int read
, int check
, int hardirqs_off
,
2525 struct lockdep_map
*nest_lock
, unsigned long ip
)
2527 struct task_struct
*curr
= current
;
2528 struct lock_class
*class = NULL
;
2529 struct held_lock
*hlock
;
2530 unsigned int depth
, id
;
2537 if (unlikely(!debug_locks
))
2540 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2543 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
2545 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2546 printk("turning off the locking correctness validator.\n");
2551 class = lock
->class_cache
;
2553 * Not cached yet or subclass?
2555 if (unlikely(!class)) {
2556 class = register_lock_class(lock
, subclass
, 0);
2560 debug_atomic_inc((atomic_t
*)&class->ops
);
2561 if (very_verbose(class)) {
2562 printk("\nacquire class [%p] %s", class->key
, class->name
);
2563 if (class->name_version
> 1)
2564 printk("#%d", class->name_version
);
2570 * Add the lock to the list of currently held locks.
2571 * (we dont increase the depth just yet, up until the
2572 * dependency checks are done)
2574 depth
= curr
->lockdep_depth
;
2575 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2578 hlock
= curr
->held_locks
+ depth
;
2579 if (DEBUG_LOCKS_WARN_ON(!class))
2581 hlock
->class_idx
= class - lock_classes
+ 1;
2582 hlock
->acquire_ip
= ip
;
2583 hlock
->instance
= lock
;
2584 hlock
->nest_lock
= nest_lock
;
2585 hlock
->trylock
= trylock
;
2587 hlock
->check
= check
;
2588 hlock
->hardirqs_off
= !!hardirqs_off
;
2589 #ifdef CONFIG_LOCK_STAT
2590 hlock
->waittime_stamp
= 0;
2591 hlock
->holdtime_stamp
= sched_clock();
2594 if (check
== 2 && !mark_irqflags(curr
, hlock
))
2597 /* mark it as used: */
2598 if (!mark_lock(curr
, hlock
, LOCK_USED
))
2602 * Calculate the chain hash: it's the combined hash of all the
2603 * lock keys along the dependency chain. We save the hash value
2604 * at every step so that we can get the current hash easily
2605 * after unlock. The chain hash is then used to cache dependency
2608 * The 'key ID' is what is the most compact key value to drive
2609 * the hash, not class->key.
2611 id
= class - lock_classes
;
2612 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2615 chain_key
= curr
->curr_chain_key
;
2617 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2622 hlock
->prev_chain_key
= chain_key
;
2623 if (separate_irq_context(curr
, hlock
)) {
2627 chain_key
= iterate_chain_key(chain_key
, id
);
2629 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
2632 curr
->curr_chain_key
= chain_key
;
2633 curr
->lockdep_depth
++;
2634 check_chain_key(curr
);
2635 #ifdef CONFIG_DEBUG_LOCKDEP
2636 if (unlikely(!debug_locks
))
2639 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2641 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2642 printk("turning off the locking correctness validator.\n");
2646 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2647 max_lockdep_depth
= curr
->lockdep_depth
;
2653 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2656 if (!debug_locks_off())
2658 if (debug_locks_silent
)
2661 printk("\n=====================================\n");
2662 printk( "[ BUG: bad unlock balance detected! ]\n");
2663 printk( "-------------------------------------\n");
2664 printk("%s/%d is trying to release lock (",
2665 curr
->comm
, task_pid_nr(curr
));
2666 print_lockdep_cache(lock
);
2669 printk("but there are no more locks to release!\n");
2670 printk("\nother info that might help us debug this:\n");
2671 lockdep_print_held_locks(curr
);
2673 printk("\nstack backtrace:\n");
2680 * Common debugging checks for both nested and non-nested unlock:
2682 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2685 if (unlikely(!debug_locks
))
2687 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2690 if (curr
->lockdep_depth
<= 0)
2691 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2697 __lock_set_subclass(struct lockdep_map
*lock
,
2698 unsigned int subclass
, unsigned long ip
)
2700 struct task_struct
*curr
= current
;
2701 struct held_lock
*hlock
, *prev_hlock
;
2702 struct lock_class
*class;
2706 depth
= curr
->lockdep_depth
;
2707 if (DEBUG_LOCKS_WARN_ON(!depth
))
2711 for (i
= depth
-1; i
>= 0; i
--) {
2712 hlock
= curr
->held_locks
+ i
;
2714 * We must not cross into another context:
2716 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2718 if (hlock
->instance
== lock
)
2722 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2725 class = register_lock_class(lock
, subclass
, 0);
2726 hlock
->class_idx
= class - lock_classes
+ 1;
2728 curr
->lockdep_depth
= i
;
2729 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2731 for (; i
< depth
; i
++) {
2732 hlock
= curr
->held_locks
+ i
;
2733 if (!__lock_acquire(hlock
->instance
,
2734 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2735 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2736 hlock
->nest_lock
, hlock
->acquire_ip
))
2740 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
2746 * Remove the lock to the list of currently held locks in a
2747 * potentially non-nested (out of order) manner. This is a
2748 * relatively rare operation, as all the unlock APIs default
2749 * to nested mode (which uses lock_release()):
2752 lock_release_non_nested(struct task_struct
*curr
,
2753 struct lockdep_map
*lock
, unsigned long ip
)
2755 struct held_lock
*hlock
, *prev_hlock
;
2760 * Check whether the lock exists in the current stack
2763 depth
= curr
->lockdep_depth
;
2764 if (DEBUG_LOCKS_WARN_ON(!depth
))
2768 for (i
= depth
-1; i
>= 0; i
--) {
2769 hlock
= curr
->held_locks
+ i
;
2771 * We must not cross into another context:
2773 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2775 if (hlock
->instance
== lock
)
2779 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2782 lock_release_holdtime(hlock
);
2785 * We have the right lock to unlock, 'hlock' points to it.
2786 * Now we remove it from the stack, and add back the other
2787 * entries (if any), recalculating the hash along the way:
2789 curr
->lockdep_depth
= i
;
2790 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2792 for (i
++; i
< depth
; i
++) {
2793 hlock
= curr
->held_locks
+ i
;
2794 if (!__lock_acquire(hlock
->instance
,
2795 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2796 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2797 hlock
->nest_lock
, hlock
->acquire_ip
))
2801 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2807 * Remove the lock to the list of currently held locks - this gets
2808 * called on mutex_unlock()/spin_unlock*() (or on a failed
2809 * mutex_lock_interruptible()). This is done for unlocks that nest
2810 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2812 static int lock_release_nested(struct task_struct
*curr
,
2813 struct lockdep_map
*lock
, unsigned long ip
)
2815 struct held_lock
*hlock
;
2819 * Pop off the top of the lock stack:
2821 depth
= curr
->lockdep_depth
- 1;
2822 hlock
= curr
->held_locks
+ depth
;
2825 * Is the unlock non-nested:
2827 if (hlock
->instance
!= lock
)
2828 return lock_release_non_nested(curr
, lock
, ip
);
2829 curr
->lockdep_depth
--;
2831 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2834 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2836 lock_release_holdtime(hlock
);
2838 #ifdef CONFIG_DEBUG_LOCKDEP
2839 hlock
->prev_chain_key
= 0;
2840 hlock
->class_idx
= 0;
2841 hlock
->acquire_ip
= 0;
2842 hlock
->irq_context
= 0;
2848 * Remove the lock to the list of currently held locks - this gets
2849 * called on mutex_unlock()/spin_unlock*() (or on a failed
2850 * mutex_lock_interruptible()). This is done for unlocks that nest
2851 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2854 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2856 struct task_struct
*curr
= current
;
2858 if (!check_unlock(curr
, lock
, ip
))
2862 if (!lock_release_nested(curr
, lock
, ip
))
2865 if (!lock_release_non_nested(curr
, lock
, ip
))
2869 check_chain_key(curr
);
2873 * Check whether we follow the irq-flags state precisely:
2875 static void check_flags(unsigned long flags
)
2877 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2878 defined(CONFIG_TRACE_IRQFLAGS)
2882 if (irqs_disabled_flags(flags
)) {
2883 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
2884 printk("possible reason: unannotated irqs-off.\n");
2887 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
2888 printk("possible reason: unannotated irqs-on.\n");
2893 * We dont accurately track softirq state in e.g.
2894 * hardirq contexts (such as on 4KSTACKS), so only
2895 * check if not in hardirq contexts:
2897 if (!hardirq_count()) {
2898 if (softirq_count())
2899 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
2901 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
2905 print_irqtrace_events(current
);
2910 lock_set_subclass(struct lockdep_map
*lock
,
2911 unsigned int subclass
, unsigned long ip
)
2913 unsigned long flags
;
2915 if (unlikely(current
->lockdep_recursion
))
2918 raw_local_irq_save(flags
);
2919 current
->lockdep_recursion
= 1;
2921 if (__lock_set_subclass(lock
, subclass
, ip
))
2922 check_chain_key(current
);
2923 current
->lockdep_recursion
= 0;
2924 raw_local_irq_restore(flags
);
2927 EXPORT_SYMBOL_GPL(lock_set_subclass
);
2930 * We are not always called with irqs disabled - do that here,
2931 * and also avoid lockdep recursion:
2933 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2934 int trylock
, int read
, int check
,
2935 struct lockdep_map
*nest_lock
, unsigned long ip
)
2937 unsigned long flags
;
2939 if (unlikely(current
->lockdep_recursion
))
2942 raw_local_irq_save(flags
);
2945 current
->lockdep_recursion
= 1;
2946 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
2947 irqs_disabled_flags(flags
), nest_lock
, ip
);
2948 current
->lockdep_recursion
= 0;
2949 raw_local_irq_restore(flags
);
2952 EXPORT_SYMBOL_GPL(lock_acquire
);
2954 void lock_release(struct lockdep_map
*lock
, int nested
,
2957 unsigned long flags
;
2959 if (unlikely(current
->lockdep_recursion
))
2962 raw_local_irq_save(flags
);
2964 current
->lockdep_recursion
= 1;
2965 __lock_release(lock
, nested
, ip
);
2966 current
->lockdep_recursion
= 0;
2967 raw_local_irq_restore(flags
);
2970 EXPORT_SYMBOL_GPL(lock_release
);
2972 #ifdef CONFIG_LOCK_STAT
2974 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2977 if (!debug_locks_off())
2979 if (debug_locks_silent
)
2982 printk("\n=================================\n");
2983 printk( "[ BUG: bad contention detected! ]\n");
2984 printk( "---------------------------------\n");
2985 printk("%s/%d is trying to contend lock (",
2986 curr
->comm
, task_pid_nr(curr
));
2987 print_lockdep_cache(lock
);
2990 printk("but there are no locks held!\n");
2991 printk("\nother info that might help us debug this:\n");
2992 lockdep_print_held_locks(curr
);
2994 printk("\nstack backtrace:\n");
3001 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3003 struct task_struct
*curr
= current
;
3004 struct held_lock
*hlock
, *prev_hlock
;
3005 struct lock_class_stats
*stats
;
3007 int i
, contention_point
, contending_point
;
3009 depth
= curr
->lockdep_depth
;
3010 if (DEBUG_LOCKS_WARN_ON(!depth
))
3014 for (i
= depth
-1; i
>= 0; i
--) {
3015 hlock
= curr
->held_locks
+ i
;
3017 * We must not cross into another context:
3019 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3021 if (hlock
->instance
== lock
)
3025 print_lock_contention_bug(curr
, lock
, ip
);
3029 hlock
->waittime_stamp
= sched_clock();
3031 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3032 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3035 stats
= get_lock_stats(hlock_class(hlock
));
3036 if (contention_point
< LOCKSTAT_POINTS
)
3037 stats
->contention_point
[contention_point
]++;
3038 if (contending_point
< LOCKSTAT_POINTS
)
3039 stats
->contending_point
[contending_point
]++;
3040 if (lock
->cpu
!= smp_processor_id())
3041 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3042 put_lock_stats(stats
);
3046 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3048 struct task_struct
*curr
= current
;
3049 struct held_lock
*hlock
, *prev_hlock
;
3050 struct lock_class_stats
*stats
;
3056 depth
= curr
->lockdep_depth
;
3057 if (DEBUG_LOCKS_WARN_ON(!depth
))
3061 for (i
= depth
-1; i
>= 0; i
--) {
3062 hlock
= curr
->held_locks
+ i
;
3064 * We must not cross into another context:
3066 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3068 if (hlock
->instance
== lock
)
3072 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3076 cpu
= smp_processor_id();
3077 if (hlock
->waittime_stamp
) {
3078 now
= sched_clock();
3079 waittime
= now
- hlock
->waittime_stamp
;
3080 hlock
->holdtime_stamp
= now
;
3083 stats
= get_lock_stats(hlock_class(hlock
));
3086 lock_time_inc(&stats
->read_waittime
, waittime
);
3088 lock_time_inc(&stats
->write_waittime
, waittime
);
3090 if (lock
->cpu
!= cpu
)
3091 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3092 put_lock_stats(stats
);
3098 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3100 unsigned long flags
;
3102 if (unlikely(!lock_stat
))
3105 if (unlikely(current
->lockdep_recursion
))
3108 raw_local_irq_save(flags
);
3110 current
->lockdep_recursion
= 1;
3111 __lock_contended(lock
, ip
);
3112 current
->lockdep_recursion
= 0;
3113 raw_local_irq_restore(flags
);
3115 EXPORT_SYMBOL_GPL(lock_contended
);
3117 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3119 unsigned long flags
;
3121 if (unlikely(!lock_stat
))
3124 if (unlikely(current
->lockdep_recursion
))
3127 raw_local_irq_save(flags
);
3129 current
->lockdep_recursion
= 1;
3130 __lock_acquired(lock
, ip
);
3131 current
->lockdep_recursion
= 0;
3132 raw_local_irq_restore(flags
);
3134 EXPORT_SYMBOL_GPL(lock_acquired
);
3138 * Used by the testsuite, sanitize the validator state
3139 * after a simulated failure:
3142 void lockdep_reset(void)
3144 unsigned long flags
;
3147 raw_local_irq_save(flags
);
3148 current
->curr_chain_key
= 0;
3149 current
->lockdep_depth
= 0;
3150 current
->lockdep_recursion
= 0;
3151 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3152 nr_hardirq_chains
= 0;
3153 nr_softirq_chains
= 0;
3154 nr_process_chains
= 0;
3156 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3157 INIT_LIST_HEAD(chainhash_table
+ i
);
3158 raw_local_irq_restore(flags
);
3161 static void zap_class(struct lock_class
*class)
3166 * Remove all dependencies this lock is
3169 for (i
= 0; i
< nr_list_entries
; i
++) {
3170 if (list_entries
[i
].class == class)
3171 list_del_rcu(&list_entries
[i
].entry
);
3174 * Unhash the class and remove it from the all_lock_classes list:
3176 list_del_rcu(&class->hash_entry
);
3177 list_del_rcu(&class->lock_entry
);
3182 static inline int within(const void *addr
, void *start
, unsigned long size
)
3184 return addr
>= start
&& addr
< start
+ size
;
3187 void lockdep_free_key_range(void *start
, unsigned long size
)
3189 struct lock_class
*class, *next
;
3190 struct list_head
*head
;
3191 unsigned long flags
;
3195 raw_local_irq_save(flags
);
3196 locked
= graph_lock();
3199 * Unhash all classes that were created by this module:
3201 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3202 head
= classhash_table
+ i
;
3203 if (list_empty(head
))
3205 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3206 if (within(class->key
, start
, size
))
3208 else if (within(class->name
, start
, size
))
3215 raw_local_irq_restore(flags
);
3218 void lockdep_reset_lock(struct lockdep_map
*lock
)
3220 struct lock_class
*class, *next
;
3221 struct list_head
*head
;
3222 unsigned long flags
;
3226 raw_local_irq_save(flags
);
3229 * Remove all classes this lock might have:
3231 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3233 * If the class exists we look it up and zap it:
3235 class = look_up_lock_class(lock
, j
);
3240 * Debug check: in the end all mapped classes should
3243 locked
= graph_lock();
3244 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3245 head
= classhash_table
+ i
;
3246 if (list_empty(head
))
3248 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3249 if (unlikely(class == lock
->class_cache
)) {
3250 if (debug_locks_off_graph_unlock())
3260 raw_local_irq_restore(flags
);
3263 void lockdep_init(void)
3268 * Some architectures have their own start_kernel()
3269 * code which calls lockdep_init(), while we also
3270 * call lockdep_init() from the start_kernel() itself,
3271 * and we want to initialize the hashes only once:
3273 if (lockdep_initialized
)
3276 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3277 INIT_LIST_HEAD(classhash_table
+ i
);
3279 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3280 INIT_LIST_HEAD(chainhash_table
+ i
);
3282 lockdep_initialized
= 1;
3285 void __init
lockdep_info(void)
3287 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3289 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
3290 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
3291 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
3292 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
3293 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
3294 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
3295 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
3297 printk(" memory used by lock dependency info: %lu kB\n",
3298 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
3299 sizeof(struct list_head
) * CLASSHASH_SIZE
+
3300 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
3301 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
3302 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
3304 printk(" per task-struct memory footprint: %lu bytes\n",
3305 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
3307 #ifdef CONFIG_DEBUG_LOCKDEP
3308 if (lockdep_init_error
) {
3309 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3310 printk("Call stack leading to lockdep invocation was:\n");
3311 print_stack_trace(&lockdep_init_trace
, 0);
3317 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
3318 const void *mem_to
, struct held_lock
*hlock
)
3320 if (!debug_locks_off())
3322 if (debug_locks_silent
)
3325 printk("\n=========================\n");
3326 printk( "[ BUG: held lock freed! ]\n");
3327 printk( "-------------------------\n");
3328 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3329 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
3331 lockdep_print_held_locks(curr
);
3333 printk("\nstack backtrace:\n");
3337 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
3338 const void* lock_from
, unsigned long lock_len
)
3340 return lock_from
+ lock_len
<= mem_from
||
3341 mem_from
+ mem_len
<= lock_from
;
3345 * Called when kernel memory is freed (or unmapped), or if a lock
3346 * is destroyed or reinitialized - this code checks whether there is
3347 * any held lock in the memory range of <from> to <to>:
3349 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
3351 struct task_struct
*curr
= current
;
3352 struct held_lock
*hlock
;
3353 unsigned long flags
;
3356 if (unlikely(!debug_locks
))
3359 local_irq_save(flags
);
3360 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3361 hlock
= curr
->held_locks
+ i
;
3363 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
3364 sizeof(*hlock
->instance
)))
3367 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
3370 local_irq_restore(flags
);
3372 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
3374 static void print_held_locks_bug(struct task_struct
*curr
)
3376 if (!debug_locks_off())
3378 if (debug_locks_silent
)
3381 printk("\n=====================================\n");
3382 printk( "[ BUG: lock held at task exit time! ]\n");
3383 printk( "-------------------------------------\n");
3384 printk("%s/%d is exiting with locks still held!\n",
3385 curr
->comm
, task_pid_nr(curr
));
3386 lockdep_print_held_locks(curr
);
3388 printk("\nstack backtrace:\n");
3392 void debug_check_no_locks_held(struct task_struct
*task
)
3394 if (unlikely(task
->lockdep_depth
> 0))
3395 print_held_locks_bug(task
);
3398 void debug_show_all_locks(void)
3400 struct task_struct
*g
, *p
;
3404 if (unlikely(!debug_locks
)) {
3405 printk("INFO: lockdep is turned off.\n");
3408 printk("\nShowing all locks held in the system:\n");
3411 * Here we try to get the tasklist_lock as hard as possible,
3412 * if not successful after 2 seconds we ignore it (but keep
3413 * trying). This is to enable a debug printout even if a
3414 * tasklist_lock-holding task deadlocks or crashes.
3417 if (!read_trylock(&tasklist_lock
)) {
3419 printk("hm, tasklist_lock locked, retrying... ");
3422 printk(" #%d", 10-count
);
3426 printk(" ignoring it.\n");
3430 printk(KERN_CONT
" locked it.\n");
3433 do_each_thread(g
, p
) {
3435 * It's not reliable to print a task's held locks
3436 * if it's not sleeping (or if it's not the current
3439 if (p
->state
== TASK_RUNNING
&& p
!= current
)
3441 if (p
->lockdep_depth
)
3442 lockdep_print_held_locks(p
);
3444 if (read_trylock(&tasklist_lock
))
3446 } while_each_thread(g
, p
);
3449 printk("=============================================\n\n");
3452 read_unlock(&tasklist_lock
);
3455 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
3458 * Careful: only use this function if you are sure that
3459 * the task cannot run in parallel!
3461 void __debug_show_held_locks(struct task_struct
*task
)
3463 if (unlikely(!debug_locks
)) {
3464 printk("INFO: lockdep is turned off.\n");
3467 lockdep_print_held_locks(task
);
3469 EXPORT_SYMBOL_GPL(__debug_show_held_locks
);
3471 void debug_show_held_locks(struct task_struct
*task
)
3473 __debug_show_held_locks(task
);
3476 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
3478 void lockdep_sys_exit(void)
3480 struct task_struct
*curr
= current
;
3482 if (unlikely(curr
->lockdep_depth
)) {
3483 if (!debug_locks_off())
3485 printk("\n================================================\n");
3486 printk( "[ BUG: lock held when returning to user space! ]\n");
3487 printk( "------------------------------------------------\n");
3488 printk("%s/%d is leaving the kernel with locks still held!\n",
3489 curr
->comm
, curr
->pid
);
3490 lockdep_print_held_locks(curr
);