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
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
47 #include <linux/kmemcheck.h>
49 #include <asm/sections.h>
51 #include "lockdep_internals.h"
53 #define CREATE_TRACE_POINTS
54 #include <trace/events/lock.h>
56 #ifdef CONFIG_PROVE_LOCKING
57 int prove_locking
= 1;
58 module_param(prove_locking
, int, 0644);
60 #define prove_locking 0
63 #ifdef CONFIG_LOCK_STAT
65 module_param(lock_stat
, int, 0644);
71 * lockdep_lock: protects the lockdep graph, the hashes and the
72 * class/list/hash allocators.
74 * This is one of the rare exceptions where it's justified
75 * to use a raw spinlock - we really dont want the spinlock
76 * code to recurse back into the lockdep code...
78 static arch_spinlock_t lockdep_lock
= (arch_spinlock_t
)__ARCH_SPIN_LOCK_UNLOCKED
;
80 static int graph_lock(void)
82 arch_spin_lock(&lockdep_lock
);
84 * Make sure that if another CPU detected a bug while
85 * walking the graph we dont change it (while the other
86 * CPU is busy printing out stuff with the graph lock
90 arch_spin_unlock(&lockdep_lock
);
93 /* prevent any recursions within lockdep from causing deadlocks */
94 current
->lockdep_recursion
++;
98 static inline int graph_unlock(void)
100 if (debug_locks
&& !arch_spin_is_locked(&lockdep_lock
)) {
102 * The lockdep graph lock isn't locked while we expect it to
103 * be, we're confused now, bye!
105 return DEBUG_LOCKS_WARN_ON(1);
108 current
->lockdep_recursion
--;
109 arch_spin_unlock(&lockdep_lock
);
114 * Turn lock debugging off and return with 0 if it was off already,
115 * and also release the graph lock:
117 static inline int debug_locks_off_graph_unlock(void)
119 int ret
= debug_locks_off();
121 arch_spin_unlock(&lockdep_lock
);
126 static int lockdep_initialized
;
128 unsigned long nr_list_entries
;
129 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
132 * All data structures here are protected by the global debug_lock.
134 * Mutex key structs only get allocated, once during bootup, and never
135 * get freed - this significantly simplifies the debugging code.
137 unsigned long nr_lock_classes
;
138 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
140 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
142 if (!hlock
->class_idx
) {
144 * Someone passed in garbage, we give up.
146 DEBUG_LOCKS_WARN_ON(1);
149 return lock_classes
+ hlock
->class_idx
- 1;
152 #ifdef CONFIG_LOCK_STAT
153 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
],
156 static inline u64
lockstat_clock(void)
158 return local_clock();
161 static int lock_point(unsigned long points
[], unsigned long ip
)
165 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
166 if (points
[i
] == 0) {
177 static void lock_time_inc(struct lock_time
*lt
, u64 time
)
182 if (time
< lt
->min
|| !lt
->nr
)
189 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
194 if (src
->max
> dst
->max
)
197 if (src
->min
< dst
->min
|| !dst
->nr
)
200 dst
->total
+= src
->total
;
204 struct lock_class_stats
lock_stats(struct lock_class
*class)
206 struct lock_class_stats stats
;
209 memset(&stats
, 0, sizeof(struct lock_class_stats
));
210 for_each_possible_cpu(cpu
) {
211 struct lock_class_stats
*pcs
=
212 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
214 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
215 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
217 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
218 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
220 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
221 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
223 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
224 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
226 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
227 stats
.bounces
[i
] += pcs
->bounces
[i
];
233 void clear_lock_stats(struct lock_class
*class)
237 for_each_possible_cpu(cpu
) {
238 struct lock_class_stats
*cpu_stats
=
239 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
241 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
243 memset(class->contention_point
, 0, sizeof(class->contention_point
));
244 memset(class->contending_point
, 0, sizeof(class->contending_point
));
247 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
249 return &get_cpu_var(cpu_lock_stats
)[class - lock_classes
];
252 static void put_lock_stats(struct lock_class_stats
*stats
)
254 put_cpu_var(cpu_lock_stats
);
257 static void lock_release_holdtime(struct held_lock
*hlock
)
259 struct lock_class_stats
*stats
;
265 holdtime
= lockstat_clock() - hlock
->holdtime_stamp
;
267 stats
= get_lock_stats(hlock_class(hlock
));
269 lock_time_inc(&stats
->read_holdtime
, holdtime
);
271 lock_time_inc(&stats
->write_holdtime
, holdtime
);
272 put_lock_stats(stats
);
275 static inline void lock_release_holdtime(struct held_lock
*hlock
)
281 * We keep a global list of all lock classes. The list only grows,
282 * never shrinks. The list is only accessed with the lockdep
283 * spinlock lock held.
285 LIST_HEAD(all_lock_classes
);
288 * The lockdep classes are in a hash-table as well, for fast lookup:
290 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
291 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
292 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
293 #define classhashentry(key) (classhash_table + __classhashfn((key)))
295 static struct hlist_head classhash_table
[CLASSHASH_SIZE
];
298 * We put the lock dependency chains into a hash-table as well, to cache
301 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
302 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
303 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
304 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
306 static struct hlist_head chainhash_table
[CHAINHASH_SIZE
];
309 * The hash key of the lock dependency chains is a hash itself too:
310 * it's a hash of all locks taken up to that lock, including that lock.
311 * It's a 64-bit hash, because it's important for the keys to be
314 #define iterate_chain_key(key1, key2) \
315 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
316 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
319 void lockdep_off(void)
321 current
->lockdep_recursion
++;
323 EXPORT_SYMBOL(lockdep_off
);
325 void lockdep_on(void)
327 current
->lockdep_recursion
--;
329 EXPORT_SYMBOL(lockdep_on
);
332 * Debugging switches:
336 #define VERY_VERBOSE 0
339 # define HARDIRQ_VERBOSE 1
340 # define SOFTIRQ_VERBOSE 1
341 # define RECLAIM_VERBOSE 1
343 # define HARDIRQ_VERBOSE 0
344 # define SOFTIRQ_VERBOSE 0
345 # define RECLAIM_VERBOSE 0
348 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
350 * Quick filtering for interesting events:
352 static int class_filter(struct lock_class
*class)
356 if (class->name_version
== 1 &&
357 !strcmp(class->name
, "lockname"))
359 if (class->name_version
== 1 &&
360 !strcmp(class->name
, "&struct->lockfield"))
363 /* Filter everything else. 1 would be to allow everything else */
368 static int verbose(struct lock_class
*class)
371 return class_filter(class);
377 * Stack-trace: tightly packed array of stack backtrace
378 * addresses. Protected by the graph_lock.
380 unsigned long nr_stack_trace_entries
;
381 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
383 static void print_lockdep_off(const char *bug_msg
)
385 printk(KERN_DEBUG
"%s\n", bug_msg
);
386 printk(KERN_DEBUG
"turning off the locking correctness validator.\n");
387 #ifdef CONFIG_LOCK_STAT
388 printk(KERN_DEBUG
"Please attach the output of /proc/lock_stat to the bug report\n");
392 static int save_trace(struct stack_trace
*trace
)
394 trace
->nr_entries
= 0;
395 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
396 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
400 save_stack_trace(trace
);
403 * Some daft arches put -1 at the end to indicate its a full trace.
405 * <rant> this is buggy anyway, since it takes a whole extra entry so a
406 * complete trace that maxes out the entries provided will be reported
407 * as incomplete, friggin useless </rant>
409 if (trace
->nr_entries
!= 0 &&
410 trace
->entries
[trace
->nr_entries
-1] == ULONG_MAX
)
413 trace
->max_entries
= trace
->nr_entries
;
415 nr_stack_trace_entries
+= trace
->nr_entries
;
417 if (nr_stack_trace_entries
>= MAX_STACK_TRACE_ENTRIES
-1) {
418 if (!debug_locks_off_graph_unlock())
421 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
430 unsigned int nr_hardirq_chains
;
431 unsigned int nr_softirq_chains
;
432 unsigned int nr_process_chains
;
433 unsigned int max_lockdep_depth
;
435 #ifdef CONFIG_DEBUG_LOCKDEP
437 * We cannot printk in early bootup code. Not even early_printk()
438 * might work. So we mark any initialization errors and printk
439 * about it later on, in lockdep_info().
441 static int lockdep_init_error
;
442 static const char *lock_init_error
;
443 static unsigned long lockdep_init_trace_data
[20];
444 static struct stack_trace lockdep_init_trace
= {
445 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
446 .entries
= lockdep_init_trace_data
,
450 * Various lockdep statistics:
452 DEFINE_PER_CPU(struct lockdep_stats
, lockdep_stats
);
459 #define __USAGE(__STATE) \
460 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
461 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
462 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
463 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
465 static const char *usage_str
[] =
467 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
468 #include "lockdep_states.h"
470 [LOCK_USED
] = "INITIAL USE",
473 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
475 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
478 static inline unsigned long lock_flag(enum lock_usage_bit bit
)
483 static char get_usage_char(struct lock_class
*class, enum lock_usage_bit bit
)
487 if (class->usage_mask
& lock_flag(bit
+ 2))
489 if (class->usage_mask
& lock_flag(bit
)) {
491 if (class->usage_mask
& lock_flag(bit
+ 2))
498 void get_usage_chars(struct lock_class
*class, char usage
[LOCK_USAGE_CHARS
])
502 #define LOCKDEP_STATE(__STATE) \
503 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
504 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
505 #include "lockdep_states.h"
511 static void __print_lock_name(struct lock_class
*class)
513 char str
[KSYM_NAME_LEN
];
518 name
= __get_key_name(class->key
, str
);
522 if (class->name_version
> 1)
523 printk("#%d", class->name_version
);
525 printk("/%d", class->subclass
);
529 static void print_lock_name(struct lock_class
*class)
531 char usage
[LOCK_USAGE_CHARS
];
533 get_usage_chars(class, usage
);
536 __print_lock_name(class);
537 printk("){%s}", usage
);
540 static void print_lockdep_cache(struct lockdep_map
*lock
)
543 char str
[KSYM_NAME_LEN
];
547 name
= __get_key_name(lock
->key
->subkeys
, str
);
552 static void print_lock(struct held_lock
*hlock
)
555 * We can be called locklessly through debug_show_all_locks() so be
556 * extra careful, the hlock might have been released and cleared.
558 unsigned int class_idx
= hlock
->class_idx
;
560 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
563 if (!class_idx
|| (class_idx
- 1) >= MAX_LOCKDEP_KEYS
) {
564 printk("<RELEASED>\n");
568 print_lock_name(lock_classes
+ class_idx
- 1);
570 print_ip_sym(hlock
->acquire_ip
);
573 static void lockdep_print_held_locks(struct task_struct
*curr
)
575 int i
, depth
= curr
->lockdep_depth
;
578 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
581 printk("%d lock%s held by %s/%d:\n",
582 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
584 for (i
= 0; i
< depth
; i
++) {
586 print_lock(curr
->held_locks
+ i
);
590 static void print_kernel_ident(void)
592 printk("%s %.*s %s\n", init_utsname()->release
,
593 (int)strcspn(init_utsname()->version
, " "),
594 init_utsname()->version
,
598 static int very_verbose(struct lock_class
*class)
601 return class_filter(class);
607 * Is this the address of a static object:
610 static int static_obj(void *obj
)
612 unsigned long start
= (unsigned long) &_stext
,
613 end
= (unsigned long) &_end
,
614 addr
= (unsigned long) obj
;
619 if ((addr
>= start
) && (addr
< end
))
622 if (arch_is_kernel_data(addr
))
626 * in-kernel percpu var?
628 if (is_kernel_percpu_address(addr
))
632 * module static or percpu var?
634 return is_module_address(addr
) || is_module_percpu_address(addr
);
639 * To make lock name printouts unique, we calculate a unique
640 * class->name_version generation counter:
642 static int count_matching_names(struct lock_class
*new_class
)
644 struct lock_class
*class;
647 if (!new_class
->name
)
650 list_for_each_entry_rcu(class, &all_lock_classes
, lock_entry
) {
651 if (new_class
->key
- new_class
->subclass
== class->key
)
652 return class->name_version
;
653 if (class->name
&& !strcmp(class->name
, new_class
->name
))
654 count
= max(count
, class->name_version
);
661 * Register a lock's class in the hash-table, if the class is not present
662 * yet. Otherwise we look it up. We cache the result in the lock object
663 * itself, so actual lookup of the hash should be once per lock object.
665 static inline struct lock_class
*
666 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
668 struct lockdep_subclass_key
*key
;
669 struct hlist_head
*hash_head
;
670 struct lock_class
*class;
672 #ifdef CONFIG_DEBUG_LOCKDEP
674 * If the architecture calls into lockdep before initializing
675 * the hashes then we'll warn about it later. (we cannot printk
678 if (unlikely(!lockdep_initialized
)) {
680 lockdep_init_error
= 1;
681 lock_init_error
= lock
->name
;
682 save_stack_trace(&lockdep_init_trace
);
686 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
689 "BUG: looking up invalid subclass: %u\n", subclass
);
691 "turning off the locking correctness validator.\n");
697 * Static locks do not have their class-keys yet - for them the key
698 * is the lock object itself:
700 if (unlikely(!lock
->key
))
701 lock
->key
= (void *)lock
;
704 * NOTE: the class-key must be unique. For dynamic locks, a static
705 * lock_class_key variable is passed in through the mutex_init()
706 * (or spin_lock_init()) call - which acts as the key. For static
707 * locks we use the lock object itself as the key.
709 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
710 sizeof(struct lockdep_map
));
712 key
= lock
->key
->subkeys
+ subclass
;
714 hash_head
= classhashentry(key
);
717 * We do an RCU walk of the hash, see lockdep_free_key_range().
719 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
722 hlist_for_each_entry_rcu(class, hash_head
, hash_entry
) {
723 if (class->key
== key
) {
725 * Huh! same key, different name? Did someone trample
726 * on some memory? We're most confused.
728 WARN_ON_ONCE(class->name
!= lock
->name
);
737 * Register a lock's class in the hash-table, if the class is not present
738 * yet. Otherwise we look it up. We cache the result in the lock object
739 * itself, so actual lookup of the hash should be once per lock object.
741 static inline struct lock_class
*
742 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
744 struct lockdep_subclass_key
*key
;
745 struct hlist_head
*hash_head
;
746 struct lock_class
*class;
748 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
750 class = look_up_lock_class(lock
, subclass
);
752 goto out_set_class_cache
;
755 * Debug-check: all keys must be persistent!
757 if (!static_obj(lock
->key
)) {
759 printk("INFO: trying to register non-static key.\n");
760 printk("the code is fine but needs lockdep annotation.\n");
761 printk("turning off the locking correctness validator.\n");
767 key
= lock
->key
->subkeys
+ subclass
;
768 hash_head
= classhashentry(key
);
774 * We have to do the hash-walk again, to avoid races
777 hlist_for_each_entry_rcu(class, hash_head
, hash_entry
) {
778 if (class->key
== key
)
783 * Allocate a new key from the static array, and add it to
786 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
787 if (!debug_locks_off_graph_unlock()) {
791 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
795 class = lock_classes
+ nr_lock_classes
++;
796 debug_atomic_inc(nr_unused_locks
);
798 class->name
= lock
->name
;
799 class->subclass
= subclass
;
800 INIT_LIST_HEAD(&class->lock_entry
);
801 INIT_LIST_HEAD(&class->locks_before
);
802 INIT_LIST_HEAD(&class->locks_after
);
803 class->name_version
= count_matching_names(class);
805 * We use RCU's safe list-add method to make
806 * parallel walking of the hash-list safe:
808 hlist_add_head_rcu(&class->hash_entry
, hash_head
);
810 * Add it to the global list of classes:
812 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
814 if (verbose(class)) {
817 printk("\nnew class %p: %s", class->key
, class->name
);
818 if (class->name_version
> 1)
819 printk("#%d", class->name_version
);
831 if (!subclass
|| force
)
832 lock
->class_cache
[0] = class;
833 else if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
834 lock
->class_cache
[subclass
] = class;
837 * Hash collision, did we smoke some? We found a class with a matching
838 * hash but the subclass -- which is hashed in -- didn't match.
840 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
846 #ifdef CONFIG_PROVE_LOCKING
848 * Allocate a lockdep entry. (assumes the graph_lock held, returns
849 * with NULL on failure)
851 static struct lock_list
*alloc_list_entry(void)
853 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
854 if (!debug_locks_off_graph_unlock())
857 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
861 return list_entries
+ nr_list_entries
++;
865 * Add a new dependency to the head of the list:
867 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
868 struct list_head
*head
, unsigned long ip
,
869 int distance
, struct stack_trace
*trace
)
871 struct lock_list
*entry
;
873 * Lock not present yet - get a new dependency struct and
874 * add it to the list:
876 entry
= alloc_list_entry();
881 entry
->distance
= distance
;
882 entry
->trace
= *trace
;
884 * Both allocation and removal are done under the graph lock; but
885 * iteration is under RCU-sched; see look_up_lock_class() and
886 * lockdep_free_key_range().
888 list_add_tail_rcu(&entry
->entry
, head
);
894 * For good efficiency of modular, we use power of 2
896 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
897 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
900 * The circular_queue and helpers is used to implement the
901 * breadth-first search(BFS)algorithem, by which we can build
902 * the shortest path from the next lock to be acquired to the
903 * previous held lock if there is a circular between them.
905 struct circular_queue
{
906 unsigned long element
[MAX_CIRCULAR_QUEUE_SIZE
];
907 unsigned int front
, rear
;
910 static struct circular_queue lock_cq
;
912 unsigned int max_bfs_queue_depth
;
914 static unsigned int lockdep_dependency_gen_id
;
916 static inline void __cq_init(struct circular_queue
*cq
)
918 cq
->front
= cq
->rear
= 0;
919 lockdep_dependency_gen_id
++;
922 static inline int __cq_empty(struct circular_queue
*cq
)
924 return (cq
->front
== cq
->rear
);
927 static inline int __cq_full(struct circular_queue
*cq
)
929 return ((cq
->rear
+ 1) & CQ_MASK
) == cq
->front
;
932 static inline int __cq_enqueue(struct circular_queue
*cq
, unsigned long elem
)
937 cq
->element
[cq
->rear
] = elem
;
938 cq
->rear
= (cq
->rear
+ 1) & CQ_MASK
;
942 static inline int __cq_dequeue(struct circular_queue
*cq
, unsigned long *elem
)
947 *elem
= cq
->element
[cq
->front
];
948 cq
->front
= (cq
->front
+ 1) & CQ_MASK
;
952 static inline unsigned int __cq_get_elem_count(struct circular_queue
*cq
)
954 return (cq
->rear
- cq
->front
) & CQ_MASK
;
957 static inline void mark_lock_accessed(struct lock_list
*lock
,
958 struct lock_list
*parent
)
962 nr
= lock
- list_entries
;
963 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
964 lock
->parent
= parent
;
965 lock
->class->dep_gen_id
= lockdep_dependency_gen_id
;
968 static inline unsigned long lock_accessed(struct lock_list
*lock
)
972 nr
= lock
- list_entries
;
973 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
974 return lock
->class->dep_gen_id
== lockdep_dependency_gen_id
;
977 static inline struct lock_list
*get_lock_parent(struct lock_list
*child
)
979 return child
->parent
;
982 static inline int get_lock_depth(struct lock_list
*child
)
985 struct lock_list
*parent
;
987 while ((parent
= get_lock_parent(child
))) {
994 static int __bfs(struct lock_list
*source_entry
,
996 int (*match
)(struct lock_list
*entry
, void *data
),
997 struct lock_list
**target_entry
,
1000 struct lock_list
*entry
;
1001 struct list_head
*head
;
1002 struct circular_queue
*cq
= &lock_cq
;
1005 if (match(source_entry
, data
)) {
1006 *target_entry
= source_entry
;
1012 head
= &source_entry
->class->locks_after
;
1014 head
= &source_entry
->class->locks_before
;
1016 if (list_empty(head
))
1020 __cq_enqueue(cq
, (unsigned long)source_entry
);
1022 while (!__cq_empty(cq
)) {
1023 struct lock_list
*lock
;
1025 __cq_dequeue(cq
, (unsigned long *)&lock
);
1033 head
= &lock
->class->locks_after
;
1035 head
= &lock
->class->locks_before
;
1037 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1039 list_for_each_entry_rcu(entry
, head
, entry
) {
1040 if (!lock_accessed(entry
)) {
1041 unsigned int cq_depth
;
1042 mark_lock_accessed(entry
, lock
);
1043 if (match(entry
, data
)) {
1044 *target_entry
= entry
;
1049 if (__cq_enqueue(cq
, (unsigned long)entry
)) {
1053 cq_depth
= __cq_get_elem_count(cq
);
1054 if (max_bfs_queue_depth
< cq_depth
)
1055 max_bfs_queue_depth
= cq_depth
;
1063 static inline int __bfs_forwards(struct lock_list
*src_entry
,
1065 int (*match
)(struct lock_list
*entry
, void *data
),
1066 struct lock_list
**target_entry
)
1068 return __bfs(src_entry
, data
, match
, target_entry
, 1);
1072 static inline int __bfs_backwards(struct lock_list
*src_entry
,
1074 int (*match
)(struct lock_list
*entry
, void *data
),
1075 struct lock_list
**target_entry
)
1077 return __bfs(src_entry
, data
, match
, target_entry
, 0);
1082 * Recursive, forwards-direction lock-dependency checking, used for
1083 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1088 * Print a dependency chain entry (this is only done when a deadlock
1089 * has been detected):
1092 print_circular_bug_entry(struct lock_list
*target
, int depth
)
1094 if (debug_locks_silent
)
1096 printk("\n-> #%u", depth
);
1097 print_lock_name(target
->class);
1099 print_stack_trace(&target
->trace
, 6);
1105 print_circular_lock_scenario(struct held_lock
*src
,
1106 struct held_lock
*tgt
,
1107 struct lock_list
*prt
)
1109 struct lock_class
*source
= hlock_class(src
);
1110 struct lock_class
*target
= hlock_class(tgt
);
1111 struct lock_class
*parent
= prt
->class;
1114 * A direct locking problem where unsafe_class lock is taken
1115 * directly by safe_class lock, then all we need to show
1116 * is the deadlock scenario, as it is obvious that the
1117 * unsafe lock is taken under the safe lock.
1119 * But if there is a chain instead, where the safe lock takes
1120 * an intermediate lock (middle_class) where this lock is
1121 * not the same as the safe lock, then the lock chain is
1122 * used to describe the problem. Otherwise we would need
1123 * to show a different CPU case for each link in the chain
1124 * from the safe_class lock to the unsafe_class lock.
1126 if (parent
!= source
) {
1127 printk("Chain exists of:\n ");
1128 __print_lock_name(source
);
1130 __print_lock_name(parent
);
1132 __print_lock_name(target
);
1136 printk(" Possible unsafe locking scenario:\n\n");
1137 printk(" CPU0 CPU1\n");
1138 printk(" ---- ----\n");
1140 __print_lock_name(target
);
1143 __print_lock_name(parent
);
1146 __print_lock_name(target
);
1149 __print_lock_name(source
);
1151 printk("\n *** DEADLOCK ***\n\n");
1155 * When a circular dependency is detected, print the
1159 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
,
1160 struct held_lock
*check_src
,
1161 struct held_lock
*check_tgt
)
1163 struct task_struct
*curr
= current
;
1165 if (debug_locks_silent
)
1169 printk("======================================================\n");
1170 printk("[ INFO: possible circular locking dependency detected ]\n");
1171 print_kernel_ident();
1172 printk("-------------------------------------------------------\n");
1173 printk("%s/%d is trying to acquire lock:\n",
1174 curr
->comm
, task_pid_nr(curr
));
1175 print_lock(check_src
);
1176 printk("\nbut task is already holding lock:\n");
1177 print_lock(check_tgt
);
1178 printk("\nwhich lock already depends on the new lock.\n\n");
1179 printk("\nthe existing dependency chain (in reverse order) is:\n");
1181 print_circular_bug_entry(entry
, depth
);
1186 static inline int class_equal(struct lock_list
*entry
, void *data
)
1188 return entry
->class == data
;
1191 static noinline
int print_circular_bug(struct lock_list
*this,
1192 struct lock_list
*target
,
1193 struct held_lock
*check_src
,
1194 struct held_lock
*check_tgt
)
1196 struct task_struct
*curr
= current
;
1197 struct lock_list
*parent
;
1198 struct lock_list
*first_parent
;
1201 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1204 if (!save_trace(&this->trace
))
1207 depth
= get_lock_depth(target
);
1209 print_circular_bug_header(target
, depth
, check_src
, check_tgt
);
1211 parent
= get_lock_parent(target
);
1212 first_parent
= parent
;
1215 print_circular_bug_entry(parent
, --depth
);
1216 parent
= get_lock_parent(parent
);
1219 printk("\nother info that might help us debug this:\n\n");
1220 print_circular_lock_scenario(check_src
, check_tgt
,
1223 lockdep_print_held_locks(curr
);
1225 printk("\nstack backtrace:\n");
1231 static noinline
int print_bfs_bug(int ret
)
1233 if (!debug_locks_off_graph_unlock())
1237 * Breadth-first-search failed, graph got corrupted?
1239 WARN(1, "lockdep bfs error:%d\n", ret
);
1244 static int noop_count(struct lock_list
*entry
, void *data
)
1246 (*(unsigned long *)data
)++;
1250 static unsigned long __lockdep_count_forward_deps(struct lock_list
*this)
1252 unsigned long count
= 0;
1253 struct lock_list
*uninitialized_var(target_entry
);
1255 __bfs_forwards(this, (void *)&count
, noop_count
, &target_entry
);
1259 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1261 unsigned long ret
, flags
;
1262 struct lock_list
this;
1267 local_irq_save(flags
);
1268 arch_spin_lock(&lockdep_lock
);
1269 ret
= __lockdep_count_forward_deps(&this);
1270 arch_spin_unlock(&lockdep_lock
);
1271 local_irq_restore(flags
);
1276 static unsigned long __lockdep_count_backward_deps(struct lock_list
*this)
1278 unsigned long count
= 0;
1279 struct lock_list
*uninitialized_var(target_entry
);
1281 __bfs_backwards(this, (void *)&count
, noop_count
, &target_entry
);
1286 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1288 unsigned long ret
, flags
;
1289 struct lock_list
this;
1294 local_irq_save(flags
);
1295 arch_spin_lock(&lockdep_lock
);
1296 ret
= __lockdep_count_backward_deps(&this);
1297 arch_spin_unlock(&lockdep_lock
);
1298 local_irq_restore(flags
);
1304 * Prove that the dependency graph starting at <entry> can not
1305 * lead to <target>. Print an error and return 0 if it does.
1308 check_noncircular(struct lock_list
*root
, struct lock_class
*target
,
1309 struct lock_list
**target_entry
)
1313 debug_atomic_inc(nr_cyclic_checks
);
1315 result
= __bfs_forwards(root
, target
, class_equal
, target_entry
);
1320 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1322 * Forwards and backwards subgraph searching, for the purposes of
1323 * proving that two subgraphs can be connected by a new dependency
1324 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1327 static inline int usage_match(struct lock_list
*entry
, void *bit
)
1329 return entry
->class->usage_mask
& (1 << (enum lock_usage_bit
)bit
);
1335 * Find a node in the forwards-direction dependency sub-graph starting
1336 * at @root->class that matches @bit.
1338 * Return 0 if such a node exists in the subgraph, and put that node
1339 * into *@target_entry.
1341 * Return 1 otherwise and keep *@target_entry unchanged.
1342 * Return <0 on error.
1345 find_usage_forwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1346 struct lock_list
**target_entry
)
1350 debug_atomic_inc(nr_find_usage_forwards_checks
);
1352 result
= __bfs_forwards(root
, (void *)bit
, usage_match
, target_entry
);
1358 * Find a node in the backwards-direction dependency sub-graph starting
1359 * at @root->class that matches @bit.
1361 * Return 0 if such a node exists in the subgraph, and put that node
1362 * into *@target_entry.
1364 * Return 1 otherwise and keep *@target_entry unchanged.
1365 * Return <0 on error.
1368 find_usage_backwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1369 struct lock_list
**target_entry
)
1373 debug_atomic_inc(nr_find_usage_backwards_checks
);
1375 result
= __bfs_backwards(root
, (void *)bit
, usage_match
, target_entry
);
1380 static void print_lock_class_header(struct lock_class
*class, int depth
)
1384 printk("%*s->", depth
, "");
1385 print_lock_name(class);
1386 printk(" ops: %lu", class->ops
);
1389 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
1390 if (class->usage_mask
& (1 << bit
)) {
1393 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
1394 len
+= printk(" at:\n");
1395 print_stack_trace(class->usage_traces
+ bit
, len
);
1398 printk("%*s }\n", depth
, "");
1400 printk("%*s ... key at: ",depth
,"");
1401 print_ip_sym((unsigned long)class->key
);
1405 * printk the shortest lock dependencies from @start to @end in reverse order:
1408 print_shortest_lock_dependencies(struct lock_list
*leaf
,
1409 struct lock_list
*root
)
1411 struct lock_list
*entry
= leaf
;
1414 /*compute depth from generated tree by BFS*/
1415 depth
= get_lock_depth(leaf
);
1418 print_lock_class_header(entry
->class, depth
);
1419 printk("%*s ... acquired at:\n", depth
, "");
1420 print_stack_trace(&entry
->trace
, 2);
1423 if (depth
== 0 && (entry
!= root
)) {
1424 printk("lockdep:%s bad path found in chain graph\n", __func__
);
1428 entry
= get_lock_parent(entry
);
1430 } while (entry
&& (depth
>= 0));
1436 print_irq_lock_scenario(struct lock_list
*safe_entry
,
1437 struct lock_list
*unsafe_entry
,
1438 struct lock_class
*prev_class
,
1439 struct lock_class
*next_class
)
1441 struct lock_class
*safe_class
= safe_entry
->class;
1442 struct lock_class
*unsafe_class
= unsafe_entry
->class;
1443 struct lock_class
*middle_class
= prev_class
;
1445 if (middle_class
== safe_class
)
1446 middle_class
= next_class
;
1449 * A direct locking problem where unsafe_class lock is taken
1450 * directly by safe_class lock, then all we need to show
1451 * is the deadlock scenario, as it is obvious that the
1452 * unsafe lock is taken under the safe lock.
1454 * But if there is a chain instead, where the safe lock takes
1455 * an intermediate lock (middle_class) where this lock is
1456 * not the same as the safe lock, then the lock chain is
1457 * used to describe the problem. Otherwise we would need
1458 * to show a different CPU case for each link in the chain
1459 * from the safe_class lock to the unsafe_class lock.
1461 if (middle_class
!= unsafe_class
) {
1462 printk("Chain exists of:\n ");
1463 __print_lock_name(safe_class
);
1465 __print_lock_name(middle_class
);
1467 __print_lock_name(unsafe_class
);
1471 printk(" Possible interrupt unsafe locking scenario:\n\n");
1472 printk(" CPU0 CPU1\n");
1473 printk(" ---- ----\n");
1475 __print_lock_name(unsafe_class
);
1477 printk(" local_irq_disable();\n");
1479 __print_lock_name(safe_class
);
1482 __print_lock_name(middle_class
);
1484 printk(" <Interrupt>\n");
1486 __print_lock_name(safe_class
);
1488 printk("\n *** DEADLOCK ***\n\n");
1492 print_bad_irq_dependency(struct task_struct
*curr
,
1493 struct lock_list
*prev_root
,
1494 struct lock_list
*next_root
,
1495 struct lock_list
*backwards_entry
,
1496 struct lock_list
*forwards_entry
,
1497 struct held_lock
*prev
,
1498 struct held_lock
*next
,
1499 enum lock_usage_bit bit1
,
1500 enum lock_usage_bit bit2
,
1501 const char *irqclass
)
1503 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1507 printk("======================================================\n");
1508 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1509 irqclass
, irqclass
);
1510 print_kernel_ident();
1511 printk("------------------------------------------------------\n");
1512 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1513 curr
->comm
, task_pid_nr(curr
),
1514 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1515 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1516 curr
->hardirqs_enabled
,
1517 curr
->softirqs_enabled
);
1520 printk("\nand this task is already holding:\n");
1522 printk("which would create a new lock dependency:\n");
1523 print_lock_name(hlock_class(prev
));
1525 print_lock_name(hlock_class(next
));
1528 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1530 print_lock_name(backwards_entry
->class);
1531 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1533 print_stack_trace(backwards_entry
->class->usage_traces
+ bit1
, 1);
1535 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1536 print_lock_name(forwards_entry
->class);
1537 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1540 print_stack_trace(forwards_entry
->class->usage_traces
+ bit2
, 1);
1542 printk("\nother info that might help us debug this:\n\n");
1543 print_irq_lock_scenario(backwards_entry
, forwards_entry
,
1544 hlock_class(prev
), hlock_class(next
));
1546 lockdep_print_held_locks(curr
);
1548 printk("\nthe dependencies between %s-irq-safe lock", irqclass
);
1549 printk(" and the holding lock:\n");
1550 if (!save_trace(&prev_root
->trace
))
1552 print_shortest_lock_dependencies(backwards_entry
, prev_root
);
1554 printk("\nthe dependencies between the lock to be acquired");
1555 printk(" and %s-irq-unsafe lock:\n", irqclass
);
1556 if (!save_trace(&next_root
->trace
))
1558 print_shortest_lock_dependencies(forwards_entry
, next_root
);
1560 printk("\nstack backtrace:\n");
1567 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1568 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1569 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1572 struct lock_list
this, that
;
1573 struct lock_list
*uninitialized_var(target_entry
);
1574 struct lock_list
*uninitialized_var(target_entry1
);
1578 this.class = hlock_class(prev
);
1579 ret
= find_usage_backwards(&this, bit_backwards
, &target_entry
);
1581 return print_bfs_bug(ret
);
1586 that
.class = hlock_class(next
);
1587 ret
= find_usage_forwards(&that
, bit_forwards
, &target_entry1
);
1589 return print_bfs_bug(ret
);
1593 return print_bad_irq_dependency(curr
, &this, &that
,
1594 target_entry
, target_entry1
,
1596 bit_backwards
, bit_forwards
, irqclass
);
1599 static const char *state_names
[] = {
1600 #define LOCKDEP_STATE(__STATE) \
1601 __stringify(__STATE),
1602 #include "lockdep_states.h"
1603 #undef LOCKDEP_STATE
1606 static const char *state_rnames
[] = {
1607 #define LOCKDEP_STATE(__STATE) \
1608 __stringify(__STATE)"-READ",
1609 #include "lockdep_states.h"
1610 #undef LOCKDEP_STATE
1613 static inline const char *state_name(enum lock_usage_bit bit
)
1615 return (bit
& 1) ? state_rnames
[bit
>> 2] : state_names
[bit
>> 2];
1618 static int exclusive_bit(int new_bit
)
1626 * bit 0 - write/read
1627 * bit 1 - used_in/enabled
1631 int state
= new_bit
& ~3;
1632 int dir
= new_bit
& 2;
1635 * keep state, bit flip the direction and strip read.
1637 return state
| (dir
^ 2);
1640 static int check_irq_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1641 struct held_lock
*next
, enum lock_usage_bit bit
)
1644 * Prove that the new dependency does not connect a hardirq-safe
1645 * lock with a hardirq-unsafe lock - to achieve this we search
1646 * the backwards-subgraph starting at <prev>, and the
1647 * forwards-subgraph starting at <next>:
1649 if (!check_usage(curr
, prev
, next
, bit
,
1650 exclusive_bit(bit
), state_name(bit
)))
1656 * Prove that the new dependency does not connect a hardirq-safe-read
1657 * lock with a hardirq-unsafe lock - to achieve this we search
1658 * the backwards-subgraph starting at <prev>, and the
1659 * forwards-subgraph starting at <next>:
1661 if (!check_usage(curr
, prev
, next
, bit
,
1662 exclusive_bit(bit
), state_name(bit
)))
1669 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1670 struct held_lock
*next
)
1672 #define LOCKDEP_STATE(__STATE) \
1673 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1675 #include "lockdep_states.h"
1676 #undef LOCKDEP_STATE
1681 static void inc_chains(void)
1683 if (current
->hardirq_context
)
1684 nr_hardirq_chains
++;
1686 if (current
->softirq_context
)
1687 nr_softirq_chains
++;
1689 nr_process_chains
++;
1696 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1697 struct held_lock
*next
)
1702 static inline void inc_chains(void)
1704 nr_process_chains
++;
1710 print_deadlock_scenario(struct held_lock
*nxt
,
1711 struct held_lock
*prv
)
1713 struct lock_class
*next
= hlock_class(nxt
);
1714 struct lock_class
*prev
= hlock_class(prv
);
1716 printk(" Possible unsafe locking scenario:\n\n");
1720 __print_lock_name(prev
);
1723 __print_lock_name(next
);
1725 printk("\n *** DEADLOCK ***\n\n");
1726 printk(" May be due to missing lock nesting notation\n\n");
1730 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1731 struct held_lock
*next
)
1733 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1737 printk("=============================================\n");
1738 printk("[ INFO: possible recursive locking detected ]\n");
1739 print_kernel_ident();
1740 printk("---------------------------------------------\n");
1741 printk("%s/%d is trying to acquire lock:\n",
1742 curr
->comm
, task_pid_nr(curr
));
1744 printk("\nbut task is already holding lock:\n");
1747 printk("\nother info that might help us debug this:\n");
1748 print_deadlock_scenario(next
, prev
);
1749 lockdep_print_held_locks(curr
);
1751 printk("\nstack backtrace:\n");
1758 * Check whether we are holding such a class already.
1760 * (Note that this has to be done separately, because the graph cannot
1761 * detect such classes of deadlocks.)
1763 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1766 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1767 struct lockdep_map
*next_instance
, int read
)
1769 struct held_lock
*prev
;
1770 struct held_lock
*nest
= NULL
;
1773 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1774 prev
= curr
->held_locks
+ i
;
1776 if (prev
->instance
== next
->nest_lock
)
1779 if (hlock_class(prev
) != hlock_class(next
))
1783 * Allow read-after-read recursion of the same
1784 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1786 if ((read
== 2) && prev
->read
)
1790 * We're holding the nest_lock, which serializes this lock's
1791 * nesting behaviour.
1796 return print_deadlock_bug(curr
, prev
, next
);
1802 * There was a chain-cache miss, and we are about to add a new dependency
1803 * to a previous lock. We recursively validate the following rules:
1805 * - would the adding of the <prev> -> <next> dependency create a
1806 * circular dependency in the graph? [== circular deadlock]
1808 * - does the new prev->next dependency connect any hardirq-safe lock
1809 * (in the full backwards-subgraph starting at <prev>) with any
1810 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1811 * <next>)? [== illegal lock inversion with hardirq contexts]
1813 * - does the new prev->next dependency connect any softirq-safe lock
1814 * (in the full backwards-subgraph starting at <prev>) with any
1815 * softirq-unsafe lock (in the full forwards-subgraph starting at
1816 * <next>)? [== illegal lock inversion with softirq contexts]
1818 * any of these scenarios could lead to a deadlock.
1820 * Then if all the validations pass, we add the forwards and backwards
1824 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1825 struct held_lock
*next
, int distance
, int *stack_saved
)
1827 struct lock_list
*entry
;
1829 struct lock_list
this;
1830 struct lock_list
*uninitialized_var(target_entry
);
1832 * Static variable, serialized by the graph_lock().
1834 * We use this static variable to save the stack trace in case
1835 * we call into this function multiple times due to encountering
1836 * trylocks in the held lock stack.
1838 static struct stack_trace trace
;
1841 * Prove that the new <prev> -> <next> dependency would not
1842 * create a circular dependency in the graph. (We do this by
1843 * forward-recursing into the graph starting at <next>, and
1844 * checking whether we can reach <prev>.)
1846 * We are using global variables to control the recursion, to
1847 * keep the stackframe size of the recursive functions low:
1849 this.class = hlock_class(next
);
1851 ret
= check_noncircular(&this, hlock_class(prev
), &target_entry
);
1853 return print_circular_bug(&this, target_entry
, next
, prev
);
1854 else if (unlikely(ret
< 0))
1855 return print_bfs_bug(ret
);
1857 if (!check_prev_add_irq(curr
, prev
, next
))
1861 * For recursive read-locks we do all the dependency checks,
1862 * but we dont store read-triggered dependencies (only
1863 * write-triggered dependencies). This ensures that only the
1864 * write-side dependencies matter, and that if for example a
1865 * write-lock never takes any other locks, then the reads are
1866 * equivalent to a NOP.
1868 if (next
->read
== 2 || prev
->read
== 2)
1871 * Is the <prev> -> <next> dependency already present?
1873 * (this may occur even though this is a new chain: consider
1874 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1875 * chains - the second one will be new, but L1 already has
1876 * L2 added to its dependency list, due to the first chain.)
1878 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1879 if (entry
->class == hlock_class(next
)) {
1881 entry
->distance
= 1;
1886 if (!*stack_saved
) {
1887 if (!save_trace(&trace
))
1893 * Ok, all validations passed, add the new lock
1894 * to the previous lock's dependency list:
1896 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1897 &hlock_class(prev
)->locks_after
,
1898 next
->acquire_ip
, distance
, &trace
);
1903 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1904 &hlock_class(next
)->locks_before
,
1905 next
->acquire_ip
, distance
, &trace
);
1910 * Debugging printouts:
1912 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1913 /* We drop graph lock, so another thread can overwrite trace. */
1916 printk("\n new dependency: ");
1917 print_lock_name(hlock_class(prev
));
1919 print_lock_name(hlock_class(next
));
1922 return graph_lock();
1928 * Add the dependency to all directly-previous locks that are 'relevant'.
1929 * The ones that are relevant are (in increasing distance from curr):
1930 * all consecutive trylock entries and the final non-trylock entry - or
1931 * the end of this context's lock-chain - whichever comes first.
1934 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1936 int depth
= curr
->lockdep_depth
;
1937 int stack_saved
= 0;
1938 struct held_lock
*hlock
;
1943 * Depth must not be zero for a non-head lock:
1948 * At least two relevant locks must exist for this
1951 if (curr
->held_locks
[depth
].irq_context
!=
1952 curr
->held_locks
[depth
-1].irq_context
)
1956 int distance
= curr
->lockdep_depth
- depth
+ 1;
1957 hlock
= curr
->held_locks
+ depth
- 1;
1959 * Only non-recursive-read entries get new dependencies
1962 if (hlock
->read
!= 2 && hlock
->check
) {
1963 if (!check_prev_add(curr
, hlock
, next
,
1964 distance
, &stack_saved
))
1967 * Stop after the first non-trylock entry,
1968 * as non-trylock entries have added their
1969 * own direct dependencies already, so this
1970 * lock is connected to them indirectly:
1972 if (!hlock
->trylock
)
1977 * End of lock-stack?
1982 * Stop the search if we cross into another context:
1984 if (curr
->held_locks
[depth
].irq_context
!=
1985 curr
->held_locks
[depth
-1].irq_context
)
1990 if (!debug_locks_off_graph_unlock())
1994 * Clearly we all shouldn't be here, but since we made it we
1995 * can reliable say we messed up our state. See the above two
1996 * gotos for reasons why we could possibly end up here.
2003 unsigned long nr_lock_chains
;
2004 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
2005 int nr_chain_hlocks
;
2006 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
2008 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
2010 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
2014 * Look up a dependency chain. If the key is not present yet then
2015 * add it and return 1 - in this case the new dependency chain is
2016 * validated. If the key is already hashed, return 0.
2017 * (On return with 1 graph_lock is held.)
2019 static inline int lookup_chain_cache(struct task_struct
*curr
,
2020 struct held_lock
*hlock
,
2023 struct lock_class
*class = hlock_class(hlock
);
2024 struct hlist_head
*hash_head
= chainhashentry(chain_key
);
2025 struct lock_chain
*chain
;
2026 struct held_lock
*hlock_curr
;
2030 * We might need to take the graph lock, ensure we've got IRQs
2031 * disabled to make this an IRQ-safe lock.. for recursion reasons
2032 * lockdep won't complain about its own locking errors.
2034 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2037 * We can walk it lock-free, because entries only get added
2040 hlist_for_each_entry_rcu(chain
, hash_head
, entry
) {
2041 if (chain
->chain_key
== chain_key
) {
2043 debug_atomic_inc(chain_lookup_hits
);
2044 if (very_verbose(class))
2045 printk("\nhash chain already cached, key: "
2046 "%016Lx tail class: [%p] %s\n",
2047 (unsigned long long)chain_key
,
2048 class->key
, class->name
);
2052 if (very_verbose(class))
2053 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2054 (unsigned long long)chain_key
, class->key
, class->name
);
2056 * Allocate a new chain entry from the static array, and add
2062 * We have to walk the chain again locked - to avoid duplicates:
2064 hlist_for_each_entry(chain
, hash_head
, entry
) {
2065 if (chain
->chain_key
== chain_key
) {
2070 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
2071 if (!debug_locks_off_graph_unlock())
2074 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2078 chain
= lock_chains
+ nr_lock_chains
++;
2079 chain
->chain_key
= chain_key
;
2080 chain
->irq_context
= hlock
->irq_context
;
2081 /* Find the first held_lock of current chain */
2082 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
2083 hlock_curr
= curr
->held_locks
+ i
;
2084 if (hlock_curr
->irq_context
!= hlock
->irq_context
)
2088 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
2089 if (likely(nr_chain_hlocks
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2090 chain
->base
= nr_chain_hlocks
;
2091 nr_chain_hlocks
+= chain
->depth
;
2092 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2093 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
2094 chain_hlocks
[chain
->base
+ j
] = lock_id
;
2096 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
2098 hlist_add_head_rcu(&chain
->entry
, hash_head
);
2099 debug_atomic_inc(chain_lookup_misses
);
2105 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
2106 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
2109 * Trylock needs to maintain the stack of held locks, but it
2110 * does not add new dependencies, because trylock can be done
2113 * We look up the chain_key and do the O(N^2) check and update of
2114 * the dependencies only if this is a new dependency chain.
2115 * (If lookup_chain_cache() returns with 1 it acquires
2116 * graph_lock for us)
2118 if (!hlock
->trylock
&& hlock
->check
&&
2119 lookup_chain_cache(curr
, hlock
, chain_key
)) {
2121 * Check whether last held lock:
2123 * - is irq-safe, if this lock is irq-unsafe
2124 * - is softirq-safe, if this lock is hardirq-unsafe
2126 * And check whether the new lock's dependency graph
2127 * could lead back to the previous lock.
2129 * any of these scenarios could lead to a deadlock. If
2132 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
2137 * Mark recursive read, as we jump over it when
2138 * building dependencies (just like we jump over
2144 * Add dependency only if this lock is not the head
2145 * of the chain, and if it's not a secondary read-lock:
2147 if (!chain_head
&& ret
!= 2)
2148 if (!check_prevs_add(curr
, hlock
))
2152 /* after lookup_chain_cache(): */
2153 if (unlikely(!debug_locks
))
2159 static inline int validate_chain(struct task_struct
*curr
,
2160 struct lockdep_map
*lock
, struct held_lock
*hlock
,
2161 int chain_head
, u64 chain_key
)
2168 * We are building curr_chain_key incrementally, so double-check
2169 * it from scratch, to make sure that it's done correctly:
2171 static void check_chain_key(struct task_struct
*curr
)
2173 #ifdef CONFIG_DEBUG_LOCKDEP
2174 struct held_lock
*hlock
, *prev_hlock
= NULL
;
2178 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2179 hlock
= curr
->held_locks
+ i
;
2180 if (chain_key
!= hlock
->prev_chain_key
) {
2183 * We got mighty confused, our chain keys don't match
2184 * with what we expect, someone trample on our task state?
2186 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2187 curr
->lockdep_depth
, i
,
2188 (unsigned long long)chain_key
,
2189 (unsigned long long)hlock
->prev_chain_key
);
2192 id
= hlock
->class_idx
- 1;
2194 * Whoops ran out of static storage again?
2196 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2199 if (prev_hlock
&& (prev_hlock
->irq_context
!=
2200 hlock
->irq_context
))
2202 chain_key
= iterate_chain_key(chain_key
, id
);
2205 if (chain_key
!= curr
->curr_chain_key
) {
2208 * More smoking hash instead of calculating it, damn see these
2209 * numbers float.. I bet that a pink elephant stepped on my memory.
2211 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2212 curr
->lockdep_depth
, i
,
2213 (unsigned long long)chain_key
,
2214 (unsigned long long)curr
->curr_chain_key
);
2220 print_usage_bug_scenario(struct held_lock
*lock
)
2222 struct lock_class
*class = hlock_class(lock
);
2224 printk(" Possible unsafe locking scenario:\n\n");
2228 __print_lock_name(class);
2230 printk(" <Interrupt>\n");
2232 __print_lock_name(class);
2234 printk("\n *** DEADLOCK ***\n\n");
2238 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
2239 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
2241 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2245 printk("=================================\n");
2246 printk("[ INFO: inconsistent lock state ]\n");
2247 print_kernel_ident();
2248 printk("---------------------------------\n");
2250 printk("inconsistent {%s} -> {%s} usage.\n",
2251 usage_str
[prev_bit
], usage_str
[new_bit
]);
2253 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2254 curr
->comm
, task_pid_nr(curr
),
2255 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
2256 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
2257 trace_hardirqs_enabled(curr
),
2258 trace_softirqs_enabled(curr
));
2261 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
2262 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
2264 print_irqtrace_events(curr
);
2265 printk("\nother info that might help us debug this:\n");
2266 print_usage_bug_scenario(this);
2268 lockdep_print_held_locks(curr
);
2270 printk("\nstack backtrace:\n");
2277 * Print out an error if an invalid bit is set:
2280 valid_state(struct task_struct
*curr
, struct held_lock
*this,
2281 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
2283 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
2284 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
2288 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2289 enum lock_usage_bit new_bit
);
2291 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2294 * print irq inversion bug:
2297 print_irq_inversion_bug(struct task_struct
*curr
,
2298 struct lock_list
*root
, struct lock_list
*other
,
2299 struct held_lock
*this, int forwards
,
2300 const char *irqclass
)
2302 struct lock_list
*entry
= other
;
2303 struct lock_list
*middle
= NULL
;
2306 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2310 printk("=========================================================\n");
2311 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2312 print_kernel_ident();
2313 printk("---------------------------------------------------------\n");
2314 printk("%s/%d just changed the state of lock:\n",
2315 curr
->comm
, task_pid_nr(curr
));
2318 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass
);
2320 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass
);
2321 print_lock_name(other
->class);
2322 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2324 printk("\nother info that might help us debug this:\n");
2326 /* Find a middle lock (if one exists) */
2327 depth
= get_lock_depth(other
);
2329 if (depth
== 0 && (entry
!= root
)) {
2330 printk("lockdep:%s bad path found in chain graph\n", __func__
);
2334 entry
= get_lock_parent(entry
);
2336 } while (entry
&& entry
!= root
&& (depth
>= 0));
2338 print_irq_lock_scenario(root
, other
,
2339 middle
? middle
->class : root
->class, other
->class);
2341 print_irq_lock_scenario(other
, root
,
2342 middle
? middle
->class : other
->class, root
->class);
2344 lockdep_print_held_locks(curr
);
2346 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2347 if (!save_trace(&root
->trace
))
2349 print_shortest_lock_dependencies(other
, root
);
2351 printk("\nstack backtrace:\n");
2358 * Prove that in the forwards-direction subgraph starting at <this>
2359 * there is no lock matching <mask>:
2362 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
2363 enum lock_usage_bit bit
, const char *irqclass
)
2366 struct lock_list root
;
2367 struct lock_list
*uninitialized_var(target_entry
);
2370 root
.class = hlock_class(this);
2371 ret
= find_usage_forwards(&root
, bit
, &target_entry
);
2373 return print_bfs_bug(ret
);
2377 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2382 * Prove that in the backwards-direction subgraph starting at <this>
2383 * there is no lock matching <mask>:
2386 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
2387 enum lock_usage_bit bit
, const char *irqclass
)
2390 struct lock_list root
;
2391 struct lock_list
*uninitialized_var(target_entry
);
2394 root
.class = hlock_class(this);
2395 ret
= find_usage_backwards(&root
, bit
, &target_entry
);
2397 return print_bfs_bug(ret
);
2401 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2405 void print_irqtrace_events(struct task_struct
*curr
)
2407 printk("irq event stamp: %u\n", curr
->irq_events
);
2408 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
2409 print_ip_sym(curr
->hardirq_enable_ip
);
2410 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
2411 print_ip_sym(curr
->hardirq_disable_ip
);
2412 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
2413 print_ip_sym(curr
->softirq_enable_ip
);
2414 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
2415 print_ip_sym(curr
->softirq_disable_ip
);
2418 static int HARDIRQ_verbose(struct lock_class
*class)
2421 return class_filter(class);
2426 static int SOFTIRQ_verbose(struct lock_class
*class)
2429 return class_filter(class);
2434 static int RECLAIM_FS_verbose(struct lock_class
*class)
2437 return class_filter(class);
2442 #define STRICT_READ_CHECKS 1
2444 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2445 #define LOCKDEP_STATE(__STATE) \
2447 #include "lockdep_states.h"
2448 #undef LOCKDEP_STATE
2451 static inline int state_verbose(enum lock_usage_bit bit
,
2452 struct lock_class
*class)
2454 return state_verbose_f
[bit
>> 2](class);
2457 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2458 enum lock_usage_bit bit
, const char *name
);
2461 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2462 enum lock_usage_bit new_bit
)
2464 int excl_bit
= exclusive_bit(new_bit
);
2465 int read
= new_bit
& 1;
2466 int dir
= new_bit
& 2;
2469 * mark USED_IN has to look forwards -- to ensure no dependency
2470 * has ENABLED state, which would allow recursion deadlocks.
2472 * mark ENABLED has to look backwards -- to ensure no dependee
2473 * has USED_IN state, which, again, would allow recursion deadlocks.
2475 check_usage_f usage
= dir
?
2476 check_usage_backwards
: check_usage_forwards
;
2479 * Validate that this particular lock does not have conflicting
2482 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2486 * Validate that the lock dependencies don't have conflicting usage
2489 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2490 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2494 * Check for read in write conflicts
2497 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2500 if (STRICT_READ_CHECKS
&&
2501 !usage(curr
, this, excl_bit
+ 1,
2502 state_name(new_bit
+ 1)))
2506 if (state_verbose(new_bit
, hlock_class(this)))
2513 #define LOCKDEP_STATE(__STATE) __STATE,
2514 #include "lockdep_states.h"
2515 #undef LOCKDEP_STATE
2519 * Mark all held locks with a usage bit:
2522 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2524 enum lock_usage_bit usage_bit
;
2525 struct held_lock
*hlock
;
2528 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2529 hlock
= curr
->held_locks
+ i
;
2531 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2533 usage_bit
+= 1; /* READ */
2535 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2540 if (!mark_lock(curr
, hlock
, usage_bit
))
2548 * Hardirqs will be enabled:
2550 static void __trace_hardirqs_on_caller(unsigned long ip
)
2552 struct task_struct
*curr
= current
;
2554 /* we'll do an OFF -> ON transition: */
2555 curr
->hardirqs_enabled
= 1;
2558 * We are going to turn hardirqs on, so set the
2559 * usage bit for all held locks:
2561 if (!mark_held_locks(curr
, HARDIRQ
))
2564 * If we have softirqs enabled, then set the usage
2565 * bit for all held locks. (disabled hardirqs prevented
2566 * this bit from being set before)
2568 if (curr
->softirqs_enabled
)
2569 if (!mark_held_locks(curr
, SOFTIRQ
))
2572 curr
->hardirq_enable_ip
= ip
;
2573 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2574 debug_atomic_inc(hardirqs_on_events
);
2577 __visible
void trace_hardirqs_on_caller(unsigned long ip
)
2579 time_hardirqs_on(CALLER_ADDR0
, ip
);
2581 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2584 if (unlikely(current
->hardirqs_enabled
)) {
2586 * Neither irq nor preemption are disabled here
2587 * so this is racy by nature but losing one hit
2588 * in a stat is not a big deal.
2590 __debug_atomic_inc(redundant_hardirqs_on
);
2595 * We're enabling irqs and according to our state above irqs weren't
2596 * already enabled, yet we find the hardware thinks they are in fact
2597 * enabled.. someone messed up their IRQ state tracing.
2599 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2603 * See the fine text that goes along with this variable definition.
2605 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled
)))
2609 * Can't allow enabling interrupts while in an interrupt handler,
2610 * that's general bad form and such. Recursion, limited stack etc..
2612 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2615 current
->lockdep_recursion
= 1;
2616 __trace_hardirqs_on_caller(ip
);
2617 current
->lockdep_recursion
= 0;
2619 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2621 void trace_hardirqs_on(void)
2623 trace_hardirqs_on_caller(CALLER_ADDR0
);
2625 EXPORT_SYMBOL(trace_hardirqs_on
);
2628 * Hardirqs were disabled:
2630 __visible
void trace_hardirqs_off_caller(unsigned long ip
)
2632 struct task_struct
*curr
= current
;
2634 time_hardirqs_off(CALLER_ADDR0
, ip
);
2636 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2640 * So we're supposed to get called after you mask local IRQs, but for
2641 * some reason the hardware doesn't quite think you did a proper job.
2643 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2646 if (curr
->hardirqs_enabled
) {
2648 * We have done an ON -> OFF transition:
2650 curr
->hardirqs_enabled
= 0;
2651 curr
->hardirq_disable_ip
= ip
;
2652 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2653 debug_atomic_inc(hardirqs_off_events
);
2655 debug_atomic_inc(redundant_hardirqs_off
);
2657 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2659 void trace_hardirqs_off(void)
2661 trace_hardirqs_off_caller(CALLER_ADDR0
);
2663 EXPORT_SYMBOL(trace_hardirqs_off
);
2666 * Softirqs will be enabled:
2668 void trace_softirqs_on(unsigned long ip
)
2670 struct task_struct
*curr
= current
;
2672 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2676 * We fancy IRQs being disabled here, see softirq.c, avoids
2677 * funny state and nesting things.
2679 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2682 if (curr
->softirqs_enabled
) {
2683 debug_atomic_inc(redundant_softirqs_on
);
2687 current
->lockdep_recursion
= 1;
2689 * We'll do an OFF -> ON transition:
2691 curr
->softirqs_enabled
= 1;
2692 curr
->softirq_enable_ip
= ip
;
2693 curr
->softirq_enable_event
= ++curr
->irq_events
;
2694 debug_atomic_inc(softirqs_on_events
);
2696 * We are going to turn softirqs on, so set the
2697 * usage bit for all held locks, if hardirqs are
2700 if (curr
->hardirqs_enabled
)
2701 mark_held_locks(curr
, SOFTIRQ
);
2702 current
->lockdep_recursion
= 0;
2706 * Softirqs were disabled:
2708 void trace_softirqs_off(unsigned long ip
)
2710 struct task_struct
*curr
= current
;
2712 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2716 * We fancy IRQs being disabled here, see softirq.c
2718 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2721 if (curr
->softirqs_enabled
) {
2723 * We have done an ON -> OFF transition:
2725 curr
->softirqs_enabled
= 0;
2726 curr
->softirq_disable_ip
= ip
;
2727 curr
->softirq_disable_event
= ++curr
->irq_events
;
2728 debug_atomic_inc(softirqs_off_events
);
2730 * Whoops, we wanted softirqs off, so why aren't they?
2732 DEBUG_LOCKS_WARN_ON(!softirq_count());
2734 debug_atomic_inc(redundant_softirqs_off
);
2737 static void __lockdep_trace_alloc(gfp_t gfp_mask
, unsigned long flags
)
2739 struct task_struct
*curr
= current
;
2741 if (unlikely(!debug_locks
))
2744 /* no reclaim without waiting on it */
2745 if (!(gfp_mask
& __GFP_DIRECT_RECLAIM
))
2748 /* this guy won't enter reclaim */
2749 if ((curr
->flags
& PF_MEMALLOC
) && !(gfp_mask
& __GFP_NOMEMALLOC
))
2752 /* We're only interested __GFP_FS allocations for now */
2753 if (!(gfp_mask
& __GFP_FS
))
2757 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2759 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags
)))
2762 mark_held_locks(curr
, RECLAIM_FS
);
2765 static void check_flags(unsigned long flags
);
2767 void lockdep_trace_alloc(gfp_t gfp_mask
)
2769 unsigned long flags
;
2771 if (unlikely(current
->lockdep_recursion
))
2774 raw_local_irq_save(flags
);
2776 current
->lockdep_recursion
= 1;
2777 __lockdep_trace_alloc(gfp_mask
, flags
);
2778 current
->lockdep_recursion
= 0;
2779 raw_local_irq_restore(flags
);
2782 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2785 * If non-trylock use in a hardirq or softirq context, then
2786 * mark the lock as used in these contexts:
2788 if (!hlock
->trylock
) {
2790 if (curr
->hardirq_context
)
2791 if (!mark_lock(curr
, hlock
,
2792 LOCK_USED_IN_HARDIRQ_READ
))
2794 if (curr
->softirq_context
)
2795 if (!mark_lock(curr
, hlock
,
2796 LOCK_USED_IN_SOFTIRQ_READ
))
2799 if (curr
->hardirq_context
)
2800 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2802 if (curr
->softirq_context
)
2803 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2807 if (!hlock
->hardirqs_off
) {
2809 if (!mark_lock(curr
, hlock
,
2810 LOCK_ENABLED_HARDIRQ_READ
))
2812 if (curr
->softirqs_enabled
)
2813 if (!mark_lock(curr
, hlock
,
2814 LOCK_ENABLED_SOFTIRQ_READ
))
2817 if (!mark_lock(curr
, hlock
,
2818 LOCK_ENABLED_HARDIRQ
))
2820 if (curr
->softirqs_enabled
)
2821 if (!mark_lock(curr
, hlock
,
2822 LOCK_ENABLED_SOFTIRQ
))
2828 * We reuse the irq context infrastructure more broadly as a general
2829 * context checking code. This tests GFP_FS recursion (a lock taken
2830 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2833 if (!hlock
->trylock
&& (curr
->lockdep_reclaim_gfp
& __GFP_FS
)) {
2835 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS_READ
))
2838 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS
))
2846 static int separate_irq_context(struct task_struct
*curr
,
2847 struct held_lock
*hlock
)
2849 unsigned int depth
= curr
->lockdep_depth
;
2852 * Keep track of points where we cross into an interrupt context:
2854 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2855 curr
->softirq_context
;
2857 struct held_lock
*prev_hlock
;
2859 prev_hlock
= curr
->held_locks
+ depth
-1;
2861 * If we cross into another context, reset the
2862 * hash key (this also prevents the checking and the
2863 * adding of the dependency to 'prev'):
2865 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2871 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2874 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2875 enum lock_usage_bit new_bit
)
2877 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2881 static inline int mark_irqflags(struct task_struct
*curr
,
2882 struct held_lock
*hlock
)
2887 static inline int separate_irq_context(struct task_struct
*curr
,
2888 struct held_lock
*hlock
)
2893 void lockdep_trace_alloc(gfp_t gfp_mask
)
2897 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2900 * Mark a lock with a usage bit, and validate the state transition:
2902 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2903 enum lock_usage_bit new_bit
)
2905 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2908 * If already set then do not dirty the cacheline,
2909 * nor do any checks:
2911 if (likely(hlock_class(this)->usage_mask
& new_mask
))
2917 * Make sure we didn't race:
2919 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
2924 hlock_class(this)->usage_mask
|= new_mask
;
2926 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
2930 #define LOCKDEP_STATE(__STATE) \
2931 case LOCK_USED_IN_##__STATE: \
2932 case LOCK_USED_IN_##__STATE##_READ: \
2933 case LOCK_ENABLED_##__STATE: \
2934 case LOCK_ENABLED_##__STATE##_READ:
2935 #include "lockdep_states.h"
2936 #undef LOCKDEP_STATE
2937 ret
= mark_lock_irq(curr
, this, new_bit
);
2942 debug_atomic_dec(nr_unused_locks
);
2945 if (!debug_locks_off_graph_unlock())
2954 * We must printk outside of the graph_lock:
2957 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2959 print_irqtrace_events(curr
);
2967 * Initialize a lock instance's lock-class mapping info:
2969 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2970 struct lock_class_key
*key
, int subclass
)
2974 kmemcheck_mark_initialized(lock
, sizeof(*lock
));
2976 for (i
= 0; i
< NR_LOCKDEP_CACHING_CLASSES
; i
++)
2977 lock
->class_cache
[i
] = NULL
;
2979 #ifdef CONFIG_LOCK_STAT
2980 lock
->cpu
= raw_smp_processor_id();
2984 * Can't be having no nameless bastards around this place!
2986 if (DEBUG_LOCKS_WARN_ON(!name
)) {
2987 lock
->name
= "NULL";
2994 * No key, no joy, we need to hash something.
2996 if (DEBUG_LOCKS_WARN_ON(!key
))
2999 * Sanity check, the lock-class key must be persistent:
3001 if (!static_obj(key
)) {
3002 printk("BUG: key %p not in .data!\n", key
);
3004 * What it says above ^^^^^, I suggest you read it.
3006 DEBUG_LOCKS_WARN_ON(1);
3011 if (unlikely(!debug_locks
))
3015 unsigned long flags
;
3017 if (DEBUG_LOCKS_WARN_ON(current
->lockdep_recursion
))
3020 raw_local_irq_save(flags
);
3021 current
->lockdep_recursion
= 1;
3022 register_lock_class(lock
, subclass
, 1);
3023 current
->lockdep_recursion
= 0;
3024 raw_local_irq_restore(flags
);
3027 EXPORT_SYMBOL_GPL(lockdep_init_map
);
3029 struct lock_class_key __lockdep_no_validate__
;
3030 EXPORT_SYMBOL_GPL(__lockdep_no_validate__
);
3033 print_lock_nested_lock_not_held(struct task_struct
*curr
,
3034 struct held_lock
*hlock
,
3037 if (!debug_locks_off())
3039 if (debug_locks_silent
)
3043 printk("==================================\n");
3044 printk("[ BUG: Nested lock was not taken ]\n");
3045 print_kernel_ident();
3046 printk("----------------------------------\n");
3048 printk("%s/%d is trying to lock:\n", curr
->comm
, task_pid_nr(curr
));
3051 printk("\nbut this task is not holding:\n");
3052 printk("%s\n", hlock
->nest_lock
->name
);
3054 printk("\nstack backtrace:\n");
3057 printk("\nother info that might help us debug this:\n");
3058 lockdep_print_held_locks(curr
);
3060 printk("\nstack backtrace:\n");
3066 static int __lock_is_held(struct lockdep_map
*lock
);
3069 * This gets called for every mutex_lock*()/spin_lock*() operation.
3070 * We maintain the dependency maps and validate the locking attempt:
3072 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3073 int trylock
, int read
, int check
, int hardirqs_off
,
3074 struct lockdep_map
*nest_lock
, unsigned long ip
,
3075 int references
, int pin_count
)
3077 struct task_struct
*curr
= current
;
3078 struct lock_class
*class = NULL
;
3079 struct held_lock
*hlock
;
3080 unsigned int depth
, id
;
3085 if (unlikely(!debug_locks
))
3089 * Lockdep should run with IRQs disabled, otherwise we could
3090 * get an interrupt which would want to take locks, which would
3091 * end up in lockdep and have you got a head-ache already?
3093 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3096 if (!prove_locking
|| lock
->key
== &__lockdep_no_validate__
)
3099 if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
3100 class = lock
->class_cache
[subclass
];
3104 if (unlikely(!class)) {
3105 class = register_lock_class(lock
, subclass
, 0);
3109 atomic_inc((atomic_t
*)&class->ops
);
3110 if (very_verbose(class)) {
3111 printk("\nacquire class [%p] %s", class->key
, class->name
);
3112 if (class->name_version
> 1)
3113 printk("#%d", class->name_version
);
3119 * Add the lock to the list of currently held locks.
3120 * (we dont increase the depth just yet, up until the
3121 * dependency checks are done)
3123 depth
= curr
->lockdep_depth
;
3125 * Ran out of static storage for our per-task lock stack again have we?
3127 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
3130 class_idx
= class - lock_classes
+ 1;
3133 hlock
= curr
->held_locks
+ depth
- 1;
3134 if (hlock
->class_idx
== class_idx
&& nest_lock
) {
3135 if (hlock
->references
)
3136 hlock
->references
++;
3138 hlock
->references
= 2;
3144 hlock
= curr
->held_locks
+ depth
;
3146 * Plain impossible, we just registered it and checked it weren't no
3147 * NULL like.. I bet this mushroom I ate was good!
3149 if (DEBUG_LOCKS_WARN_ON(!class))
3151 hlock
->class_idx
= class_idx
;
3152 hlock
->acquire_ip
= ip
;
3153 hlock
->instance
= lock
;
3154 hlock
->nest_lock
= nest_lock
;
3155 hlock
->trylock
= trylock
;
3157 hlock
->check
= check
;
3158 hlock
->hardirqs_off
= !!hardirqs_off
;
3159 hlock
->references
= references
;
3160 #ifdef CONFIG_LOCK_STAT
3161 hlock
->waittime_stamp
= 0;
3162 hlock
->holdtime_stamp
= lockstat_clock();
3164 hlock
->pin_count
= pin_count
;
3166 if (check
&& !mark_irqflags(curr
, hlock
))
3169 /* mark it as used: */
3170 if (!mark_lock(curr
, hlock
, LOCK_USED
))
3174 * Calculate the chain hash: it's the combined hash of all the
3175 * lock keys along the dependency chain. We save the hash value
3176 * at every step so that we can get the current hash easily
3177 * after unlock. The chain hash is then used to cache dependency
3180 * The 'key ID' is what is the most compact key value to drive
3181 * the hash, not class->key.
3183 id
= class - lock_classes
;
3185 * Whoops, we did it again.. ran straight out of our static allocation.
3187 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
3190 chain_key
= curr
->curr_chain_key
;
3193 * How can we have a chain hash when we ain't got no keys?!
3195 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
3200 hlock
->prev_chain_key
= chain_key
;
3201 if (separate_irq_context(curr
, hlock
)) {
3205 chain_key
= iterate_chain_key(chain_key
, id
);
3207 if (nest_lock
&& !__lock_is_held(nest_lock
))
3208 return print_lock_nested_lock_not_held(curr
, hlock
, ip
);
3210 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
3213 curr
->curr_chain_key
= chain_key
;
3214 curr
->lockdep_depth
++;
3215 check_chain_key(curr
);
3216 #ifdef CONFIG_DEBUG_LOCKDEP
3217 if (unlikely(!debug_locks
))
3220 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
3222 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3223 printk(KERN_DEBUG
"depth: %i max: %lu!\n",
3224 curr
->lockdep_depth
, MAX_LOCK_DEPTH
);
3226 lockdep_print_held_locks(current
);
3227 debug_show_all_locks();
3233 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
3234 max_lockdep_depth
= curr
->lockdep_depth
;
3240 print_unlock_imbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3243 if (!debug_locks_off())
3245 if (debug_locks_silent
)
3249 printk("=====================================\n");
3250 printk("[ BUG: bad unlock balance detected! ]\n");
3251 print_kernel_ident();
3252 printk("-------------------------------------\n");
3253 printk("%s/%d is trying to release lock (",
3254 curr
->comm
, task_pid_nr(curr
));
3255 print_lockdep_cache(lock
);
3258 printk("but there are no more locks to release!\n");
3259 printk("\nother info that might help us debug this:\n");
3260 lockdep_print_held_locks(curr
);
3262 printk("\nstack backtrace:\n");
3268 static int match_held_lock(struct held_lock
*hlock
, struct lockdep_map
*lock
)
3270 if (hlock
->instance
== lock
)
3273 if (hlock
->references
) {
3274 struct lock_class
*class = lock
->class_cache
[0];
3277 class = look_up_lock_class(lock
, 0);
3280 * If look_up_lock_class() failed to find a class, we're trying
3281 * to test if we hold a lock that has never yet been acquired.
3282 * Clearly if the lock hasn't been acquired _ever_, we're not
3283 * holding it either, so report failure.
3289 * References, but not a lock we're actually ref-counting?
3290 * State got messed up, follow the sites that change ->references
3291 * and try to make sense of it.
3293 if (DEBUG_LOCKS_WARN_ON(!hlock
->nest_lock
))
3296 if (hlock
->class_idx
== class - lock_classes
+ 1)
3304 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
3305 struct lock_class_key
*key
, unsigned int subclass
,
3308 struct task_struct
*curr
= current
;
3309 struct held_lock
*hlock
, *prev_hlock
;
3310 struct lock_class
*class;
3314 depth
= curr
->lockdep_depth
;
3316 * This function is about (re)setting the class of a held lock,
3317 * yet we're not actually holding any locks. Naughty user!
3319 if (DEBUG_LOCKS_WARN_ON(!depth
))
3323 for (i
= depth
-1; i
>= 0; i
--) {
3324 hlock
= curr
->held_locks
+ i
;
3326 * We must not cross into another context:
3328 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3330 if (match_held_lock(hlock
, lock
))
3334 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3337 lockdep_init_map(lock
, name
, key
, 0);
3338 class = register_lock_class(lock
, subclass
, 0);
3339 hlock
->class_idx
= class - lock_classes
+ 1;
3341 curr
->lockdep_depth
= i
;
3342 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3344 for (; i
< depth
; i
++) {
3345 hlock
= curr
->held_locks
+ i
;
3346 if (!__lock_acquire(hlock
->instance
,
3347 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3348 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3349 hlock
->nest_lock
, hlock
->acquire_ip
,
3350 hlock
->references
, hlock
->pin_count
))
3355 * I took it apart and put it back together again, except now I have
3356 * these 'spare' parts.. where shall I put them.
3358 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
3364 * Remove the lock to the list of currently held locks - this gets
3365 * called on mutex_unlock()/spin_unlock*() (or on a failed
3366 * mutex_lock_interruptible()).
3368 * @nested is an hysterical artifact, needs a tree wide cleanup.
3371 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
3373 struct task_struct
*curr
= current
;
3374 struct held_lock
*hlock
, *prev_hlock
;
3378 if (unlikely(!debug_locks
))
3381 depth
= curr
->lockdep_depth
;
3383 * So we're all set to release this lock.. wait what lock? We don't
3384 * own any locks, you've been drinking again?
3386 if (DEBUG_LOCKS_WARN_ON(depth
<= 0))
3387 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3390 * Check whether the lock exists in the current stack
3394 for (i
= depth
-1; i
>= 0; i
--) {
3395 hlock
= curr
->held_locks
+ i
;
3397 * We must not cross into another context:
3399 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3401 if (match_held_lock(hlock
, lock
))
3405 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3408 if (hlock
->instance
== lock
)
3409 lock_release_holdtime(hlock
);
3411 WARN(hlock
->pin_count
, "releasing a pinned lock\n");
3413 if (hlock
->references
) {
3414 hlock
->references
--;
3415 if (hlock
->references
) {
3417 * We had, and after removing one, still have
3418 * references, the current lock stack is still
3419 * valid. We're done!
3426 * We have the right lock to unlock, 'hlock' points to it.
3427 * Now we remove it from the stack, and add back the other
3428 * entries (if any), recalculating the hash along the way:
3431 curr
->lockdep_depth
= i
;
3432 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3434 for (i
++; i
< depth
; i
++) {
3435 hlock
= curr
->held_locks
+ i
;
3436 if (!__lock_acquire(hlock
->instance
,
3437 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3438 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3439 hlock
->nest_lock
, hlock
->acquire_ip
,
3440 hlock
->references
, hlock
->pin_count
))
3445 * We had N bottles of beer on the wall, we drank one, but now
3446 * there's not N-1 bottles of beer left on the wall...
3448 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
3454 static int __lock_is_held(struct lockdep_map
*lock
)
3456 struct task_struct
*curr
= current
;
3459 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3460 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3462 if (match_held_lock(hlock
, lock
))
3469 static void __lock_pin_lock(struct lockdep_map
*lock
)
3471 struct task_struct
*curr
= current
;
3474 if (unlikely(!debug_locks
))
3477 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3478 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3480 if (match_held_lock(hlock
, lock
)) {
3486 WARN(1, "pinning an unheld lock\n");
3489 static void __lock_unpin_lock(struct lockdep_map
*lock
)
3491 struct task_struct
*curr
= current
;
3494 if (unlikely(!debug_locks
))
3497 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3498 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3500 if (match_held_lock(hlock
, lock
)) {
3501 if (WARN(!hlock
->pin_count
, "unpinning an unpinned lock\n"))
3509 WARN(1, "unpinning an unheld lock\n");
3513 * Check whether we follow the irq-flags state precisely:
3515 static void check_flags(unsigned long flags
)
3517 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3518 defined(CONFIG_TRACE_IRQFLAGS)
3522 if (irqs_disabled_flags(flags
)) {
3523 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
3524 printk("possible reason: unannotated irqs-off.\n");
3527 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
3528 printk("possible reason: unannotated irqs-on.\n");
3533 * We dont accurately track softirq state in e.g.
3534 * hardirq contexts (such as on 4KSTACKS), so only
3535 * check if not in hardirq contexts:
3537 if (!hardirq_count()) {
3538 if (softirq_count()) {
3539 /* like the above, but with softirqs */
3540 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
3542 /* lick the above, does it taste good? */
3543 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
3548 print_irqtrace_events(current
);
3552 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
3553 struct lock_class_key
*key
, unsigned int subclass
,
3556 unsigned long flags
;
3558 if (unlikely(current
->lockdep_recursion
))
3561 raw_local_irq_save(flags
);
3562 current
->lockdep_recursion
= 1;
3564 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
3565 check_chain_key(current
);
3566 current
->lockdep_recursion
= 0;
3567 raw_local_irq_restore(flags
);
3569 EXPORT_SYMBOL_GPL(lock_set_class
);
3572 * We are not always called with irqs disabled - do that here,
3573 * and also avoid lockdep recursion:
3575 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3576 int trylock
, int read
, int check
,
3577 struct lockdep_map
*nest_lock
, unsigned long ip
)
3579 unsigned long flags
;
3581 if (unlikely(current
->lockdep_recursion
))
3584 raw_local_irq_save(flags
);
3587 current
->lockdep_recursion
= 1;
3588 trace_lock_acquire(lock
, subclass
, trylock
, read
, check
, nest_lock
, ip
);
3589 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
3590 irqs_disabled_flags(flags
), nest_lock
, ip
, 0, 0);
3591 current
->lockdep_recursion
= 0;
3592 raw_local_irq_restore(flags
);
3594 EXPORT_SYMBOL_GPL(lock_acquire
);
3596 void lock_release(struct lockdep_map
*lock
, int nested
,
3599 unsigned long flags
;
3601 if (unlikely(current
->lockdep_recursion
))
3604 raw_local_irq_save(flags
);
3606 current
->lockdep_recursion
= 1;
3607 trace_lock_release(lock
, ip
);
3608 if (__lock_release(lock
, nested
, ip
))
3609 check_chain_key(current
);
3610 current
->lockdep_recursion
= 0;
3611 raw_local_irq_restore(flags
);
3613 EXPORT_SYMBOL_GPL(lock_release
);
3615 int lock_is_held(struct lockdep_map
*lock
)
3617 unsigned long flags
;
3620 if (unlikely(current
->lockdep_recursion
))
3621 return 1; /* avoid false negative lockdep_assert_held() */
3623 raw_local_irq_save(flags
);
3626 current
->lockdep_recursion
= 1;
3627 ret
= __lock_is_held(lock
);
3628 current
->lockdep_recursion
= 0;
3629 raw_local_irq_restore(flags
);
3633 EXPORT_SYMBOL_GPL(lock_is_held
);
3635 void lock_pin_lock(struct lockdep_map
*lock
)
3637 unsigned long flags
;
3639 if (unlikely(current
->lockdep_recursion
))
3642 raw_local_irq_save(flags
);
3645 current
->lockdep_recursion
= 1;
3646 __lock_pin_lock(lock
);
3647 current
->lockdep_recursion
= 0;
3648 raw_local_irq_restore(flags
);
3650 EXPORT_SYMBOL_GPL(lock_pin_lock
);
3652 void lock_unpin_lock(struct lockdep_map
*lock
)
3654 unsigned long flags
;
3656 if (unlikely(current
->lockdep_recursion
))
3659 raw_local_irq_save(flags
);
3662 current
->lockdep_recursion
= 1;
3663 __lock_unpin_lock(lock
);
3664 current
->lockdep_recursion
= 0;
3665 raw_local_irq_restore(flags
);
3667 EXPORT_SYMBOL_GPL(lock_unpin_lock
);
3669 void lockdep_set_current_reclaim_state(gfp_t gfp_mask
)
3671 current
->lockdep_reclaim_gfp
= gfp_mask
;
3674 void lockdep_clear_current_reclaim_state(void)
3676 current
->lockdep_reclaim_gfp
= 0;
3679 #ifdef CONFIG_LOCK_STAT
3681 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3684 if (!debug_locks_off())
3686 if (debug_locks_silent
)
3690 printk("=================================\n");
3691 printk("[ BUG: bad contention detected! ]\n");
3692 print_kernel_ident();
3693 printk("---------------------------------\n");
3694 printk("%s/%d is trying to contend lock (",
3695 curr
->comm
, task_pid_nr(curr
));
3696 print_lockdep_cache(lock
);
3699 printk("but there are no locks held!\n");
3700 printk("\nother info that might help us debug this:\n");
3701 lockdep_print_held_locks(curr
);
3703 printk("\nstack backtrace:\n");
3710 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3712 struct task_struct
*curr
= current
;
3713 struct held_lock
*hlock
, *prev_hlock
;
3714 struct lock_class_stats
*stats
;
3716 int i
, contention_point
, contending_point
;
3718 depth
= curr
->lockdep_depth
;
3720 * Whee, we contended on this lock, except it seems we're not
3721 * actually trying to acquire anything much at all..
3723 if (DEBUG_LOCKS_WARN_ON(!depth
))
3727 for (i
= depth
-1; i
>= 0; i
--) {
3728 hlock
= curr
->held_locks
+ i
;
3730 * We must not cross into another context:
3732 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3734 if (match_held_lock(hlock
, lock
))
3738 print_lock_contention_bug(curr
, lock
, ip
);
3742 if (hlock
->instance
!= lock
)
3745 hlock
->waittime_stamp
= lockstat_clock();
3747 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3748 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3751 stats
= get_lock_stats(hlock_class(hlock
));
3752 if (contention_point
< LOCKSTAT_POINTS
)
3753 stats
->contention_point
[contention_point
]++;
3754 if (contending_point
< LOCKSTAT_POINTS
)
3755 stats
->contending_point
[contending_point
]++;
3756 if (lock
->cpu
!= smp_processor_id())
3757 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3758 put_lock_stats(stats
);
3762 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3764 struct task_struct
*curr
= current
;
3765 struct held_lock
*hlock
, *prev_hlock
;
3766 struct lock_class_stats
*stats
;
3768 u64 now
, waittime
= 0;
3771 depth
= curr
->lockdep_depth
;
3773 * Yay, we acquired ownership of this lock we didn't try to
3774 * acquire, how the heck did that happen?
3776 if (DEBUG_LOCKS_WARN_ON(!depth
))
3780 for (i
= depth
-1; i
>= 0; i
--) {
3781 hlock
= curr
->held_locks
+ i
;
3783 * We must not cross into another context:
3785 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3787 if (match_held_lock(hlock
, lock
))
3791 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3795 if (hlock
->instance
!= lock
)
3798 cpu
= smp_processor_id();
3799 if (hlock
->waittime_stamp
) {
3800 now
= lockstat_clock();
3801 waittime
= now
- hlock
->waittime_stamp
;
3802 hlock
->holdtime_stamp
= now
;
3805 trace_lock_acquired(lock
, ip
);
3807 stats
= get_lock_stats(hlock_class(hlock
));
3810 lock_time_inc(&stats
->read_waittime
, waittime
);
3812 lock_time_inc(&stats
->write_waittime
, waittime
);
3814 if (lock
->cpu
!= cpu
)
3815 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3816 put_lock_stats(stats
);
3822 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3824 unsigned long flags
;
3826 if (unlikely(!lock_stat
))
3829 if (unlikely(current
->lockdep_recursion
))
3832 raw_local_irq_save(flags
);
3834 current
->lockdep_recursion
= 1;
3835 trace_lock_contended(lock
, ip
);
3836 __lock_contended(lock
, ip
);
3837 current
->lockdep_recursion
= 0;
3838 raw_local_irq_restore(flags
);
3840 EXPORT_SYMBOL_GPL(lock_contended
);
3842 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3844 unsigned long flags
;
3846 if (unlikely(!lock_stat
))
3849 if (unlikely(current
->lockdep_recursion
))
3852 raw_local_irq_save(flags
);
3854 current
->lockdep_recursion
= 1;
3855 __lock_acquired(lock
, ip
);
3856 current
->lockdep_recursion
= 0;
3857 raw_local_irq_restore(flags
);
3859 EXPORT_SYMBOL_GPL(lock_acquired
);
3863 * Used by the testsuite, sanitize the validator state
3864 * after a simulated failure:
3867 void lockdep_reset(void)
3869 unsigned long flags
;
3872 raw_local_irq_save(flags
);
3873 current
->curr_chain_key
= 0;
3874 current
->lockdep_depth
= 0;
3875 current
->lockdep_recursion
= 0;
3876 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3877 nr_hardirq_chains
= 0;
3878 nr_softirq_chains
= 0;
3879 nr_process_chains
= 0;
3881 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3882 INIT_HLIST_HEAD(chainhash_table
+ i
);
3883 raw_local_irq_restore(flags
);
3886 static void zap_class(struct lock_class
*class)
3891 * Remove all dependencies this lock is
3894 for (i
= 0; i
< nr_list_entries
; i
++) {
3895 if (list_entries
[i
].class == class)
3896 list_del_rcu(&list_entries
[i
].entry
);
3899 * Unhash the class and remove it from the all_lock_classes list:
3901 hlist_del_rcu(&class->hash_entry
);
3902 list_del_rcu(&class->lock_entry
);
3904 RCU_INIT_POINTER(class->key
, NULL
);
3905 RCU_INIT_POINTER(class->name
, NULL
);
3908 static inline int within(const void *addr
, void *start
, unsigned long size
)
3910 return addr
>= start
&& addr
< start
+ size
;
3914 * Used in module.c to remove lock classes from memory that is going to be
3915 * freed; and possibly re-used by other modules.
3917 * We will have had one sync_sched() before getting here, so we're guaranteed
3918 * nobody will look up these exact classes -- they're properly dead but still
3921 void lockdep_free_key_range(void *start
, unsigned long size
)
3923 struct lock_class
*class;
3924 struct hlist_head
*head
;
3925 unsigned long flags
;
3929 raw_local_irq_save(flags
);
3930 locked
= graph_lock();
3933 * Unhash all classes that were created by this module:
3935 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3936 head
= classhash_table
+ i
;
3937 hlist_for_each_entry_rcu(class, head
, hash_entry
) {
3938 if (within(class->key
, start
, size
))
3940 else if (within(class->name
, start
, size
))
3947 raw_local_irq_restore(flags
);
3950 * Wait for any possible iterators from look_up_lock_class() to pass
3951 * before continuing to free the memory they refer to.
3953 * sync_sched() is sufficient because the read-side is IRQ disable.
3955 synchronize_sched();
3958 * XXX at this point we could return the resources to the pool;
3959 * instead we leak them. We would need to change to bitmap allocators
3960 * instead of the linear allocators we have now.
3964 void lockdep_reset_lock(struct lockdep_map
*lock
)
3966 struct lock_class
*class;
3967 struct hlist_head
*head
;
3968 unsigned long flags
;
3972 raw_local_irq_save(flags
);
3975 * Remove all classes this lock might have:
3977 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3979 * If the class exists we look it up and zap it:
3981 class = look_up_lock_class(lock
, j
);
3986 * Debug check: in the end all mapped classes should
3989 locked
= graph_lock();
3990 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3991 head
= classhash_table
+ i
;
3992 hlist_for_each_entry_rcu(class, head
, hash_entry
) {
3995 for (j
= 0; j
< NR_LOCKDEP_CACHING_CLASSES
; j
++)
3996 match
|= class == lock
->class_cache
[j
];
3998 if (unlikely(match
)) {
3999 if (debug_locks_off_graph_unlock()) {
4001 * We all just reset everything, how did it match?
4013 raw_local_irq_restore(flags
);
4016 void lockdep_init(void)
4021 * Some architectures have their own start_kernel()
4022 * code which calls lockdep_init(), while we also
4023 * call lockdep_init() from the start_kernel() itself,
4024 * and we want to initialize the hashes only once:
4026 if (lockdep_initialized
)
4029 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
4030 INIT_HLIST_HEAD(classhash_table
+ i
);
4032 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
4033 INIT_HLIST_HEAD(chainhash_table
+ i
);
4035 lockdep_initialized
= 1;
4038 void __init
lockdep_info(void)
4040 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4042 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
4043 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
4044 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
4045 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
4046 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
4047 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
4048 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
4050 printk(" memory used by lock dependency info: %lu kB\n",
4051 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
4052 sizeof(struct list_head
) * CLASSHASH_SIZE
+
4053 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
4054 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
4055 sizeof(struct list_head
) * CHAINHASH_SIZE
4056 #ifdef CONFIG_PROVE_LOCKING
4057 + sizeof(struct circular_queue
)
4062 printk(" per task-struct memory footprint: %lu bytes\n",
4063 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
4065 #ifdef CONFIG_DEBUG_LOCKDEP
4066 if (lockdep_init_error
) {
4067 printk("WARNING: lockdep init error: lock '%s' was acquired before lockdep_init().\n", lock_init_error
);
4068 printk("Call stack leading to lockdep invocation was:\n");
4069 print_stack_trace(&lockdep_init_trace
, 0);
4075 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
4076 const void *mem_to
, struct held_lock
*hlock
)
4078 if (!debug_locks_off())
4080 if (debug_locks_silent
)
4084 printk("=========================\n");
4085 printk("[ BUG: held lock freed! ]\n");
4086 print_kernel_ident();
4087 printk("-------------------------\n");
4088 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4089 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
4091 lockdep_print_held_locks(curr
);
4093 printk("\nstack backtrace:\n");
4097 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
4098 const void* lock_from
, unsigned long lock_len
)
4100 return lock_from
+ lock_len
<= mem_from
||
4101 mem_from
+ mem_len
<= lock_from
;
4105 * Called when kernel memory is freed (or unmapped), or if a lock
4106 * is destroyed or reinitialized - this code checks whether there is
4107 * any held lock in the memory range of <from> to <to>:
4109 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
4111 struct task_struct
*curr
= current
;
4112 struct held_lock
*hlock
;
4113 unsigned long flags
;
4116 if (unlikely(!debug_locks
))
4119 local_irq_save(flags
);
4120 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
4121 hlock
= curr
->held_locks
+ i
;
4123 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
4124 sizeof(*hlock
->instance
)))
4127 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
4130 local_irq_restore(flags
);
4132 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
4134 static void print_held_locks_bug(void)
4136 if (!debug_locks_off())
4138 if (debug_locks_silent
)
4142 printk("=====================================\n");
4143 printk("[ BUG: %s/%d still has locks held! ]\n",
4144 current
->comm
, task_pid_nr(current
));
4145 print_kernel_ident();
4146 printk("-------------------------------------\n");
4147 lockdep_print_held_locks(current
);
4148 printk("\nstack backtrace:\n");
4152 void debug_check_no_locks_held(void)
4154 if (unlikely(current
->lockdep_depth
> 0))
4155 print_held_locks_bug();
4157 EXPORT_SYMBOL_GPL(debug_check_no_locks_held
);
4160 void debug_show_all_locks(void)
4162 struct task_struct
*g
, *p
;
4166 if (unlikely(!debug_locks
)) {
4167 printk("INFO: lockdep is turned off.\n");
4170 printk("\nShowing all locks held in the system:\n");
4173 * Here we try to get the tasklist_lock as hard as possible,
4174 * if not successful after 2 seconds we ignore it (but keep
4175 * trying). This is to enable a debug printout even if a
4176 * tasklist_lock-holding task deadlocks or crashes.
4179 if (!read_trylock(&tasklist_lock
)) {
4181 printk("hm, tasklist_lock locked, retrying... ");
4184 printk(" #%d", 10-count
);
4188 printk(" ignoring it.\n");
4192 printk(KERN_CONT
" locked it.\n");
4195 do_each_thread(g
, p
) {
4197 * It's not reliable to print a task's held locks
4198 * if it's not sleeping (or if it's not the current
4201 if (p
->state
== TASK_RUNNING
&& p
!= current
)
4203 if (p
->lockdep_depth
)
4204 lockdep_print_held_locks(p
);
4206 if (read_trylock(&tasklist_lock
))
4208 } while_each_thread(g
, p
);
4211 printk("=============================================\n\n");
4214 read_unlock(&tasklist_lock
);
4216 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
4220 * Careful: only use this function if you are sure that
4221 * the task cannot run in parallel!
4223 void debug_show_held_locks(struct task_struct
*task
)
4225 if (unlikely(!debug_locks
)) {
4226 printk("INFO: lockdep is turned off.\n");
4229 lockdep_print_held_locks(task
);
4231 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
4233 asmlinkage __visible
void lockdep_sys_exit(void)
4235 struct task_struct
*curr
= current
;
4237 if (unlikely(curr
->lockdep_depth
)) {
4238 if (!debug_locks_off())
4241 printk("================================================\n");
4242 printk("[ BUG: lock held when returning to user space! ]\n");
4243 print_kernel_ident();
4244 printk("------------------------------------------------\n");
4245 printk("%s/%d is leaving the kernel with locks still held!\n",
4246 curr
->comm
, curr
->pid
);
4247 lockdep_print_held_locks(curr
);
4251 void lockdep_rcu_suspicious(const char *file
, const int line
, const char *s
)
4253 struct task_struct
*curr
= current
;
4255 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4256 if (!debug_locks_off())
4258 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4259 /* Note: the following can be executed concurrently, so be careful. */
4261 printk("===============================\n");
4262 printk("[ INFO: suspicious RCU usage. ]\n");
4263 print_kernel_ident();
4264 printk("-------------------------------\n");
4265 printk("%s:%d %s!\n", file
, line
, s
);
4266 printk("\nother info that might help us debug this:\n\n");
4267 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4268 !rcu_lockdep_current_cpu_online()
4269 ? "RCU used illegally from offline CPU!\n"
4270 : !rcu_is_watching()
4271 ? "RCU used illegally from idle CPU!\n"
4273 rcu_scheduler_active
, debug_locks
);
4276 * If a CPU is in the RCU-free window in idle (ie: in the section
4277 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4278 * considers that CPU to be in an "extended quiescent state",
4279 * which means that RCU will be completely ignoring that CPU.
4280 * Therefore, rcu_read_lock() and friends have absolutely no
4281 * effect on a CPU running in that state. In other words, even if
4282 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4283 * delete data structures out from under it. RCU really has no
4284 * choice here: we need to keep an RCU-free window in idle where
4285 * the CPU may possibly enter into low power mode. This way we can
4286 * notice an extended quiescent state to other CPUs that started a grace
4287 * period. Otherwise we would delay any grace period as long as we run
4290 * So complain bitterly if someone does call rcu_read_lock(),
4291 * rcu_read_lock_bh() and so on from extended quiescent states.
4293 if (!rcu_is_watching())
4294 printk("RCU used illegally from extended quiescent state!\n");
4296 lockdep_print_held_locks(curr
);
4297 printk("\nstack backtrace:\n");
4300 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious
);