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 unsigned long nr_list_entries
;
127 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
130 * All data structures here are protected by the global debug_lock.
132 * Mutex key structs only get allocated, once during bootup, and never
133 * get freed - this significantly simplifies the debugging code.
135 unsigned long nr_lock_classes
;
136 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
138 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
140 if (!hlock
->class_idx
) {
142 * Someone passed in garbage, we give up.
144 DEBUG_LOCKS_WARN_ON(1);
147 return lock_classes
+ hlock
->class_idx
- 1;
150 #ifdef CONFIG_LOCK_STAT
151 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
], cpu_lock_stats
);
153 static inline u64
lockstat_clock(void)
155 return local_clock();
158 static int lock_point(unsigned long points
[], unsigned long ip
)
162 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
163 if (points
[i
] == 0) {
174 static void lock_time_inc(struct lock_time
*lt
, u64 time
)
179 if (time
< lt
->min
|| !lt
->nr
)
186 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
191 if (src
->max
> dst
->max
)
194 if (src
->min
< dst
->min
|| !dst
->nr
)
197 dst
->total
+= src
->total
;
201 struct lock_class_stats
lock_stats(struct lock_class
*class)
203 struct lock_class_stats stats
;
206 memset(&stats
, 0, sizeof(struct lock_class_stats
));
207 for_each_possible_cpu(cpu
) {
208 struct lock_class_stats
*pcs
=
209 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
211 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
212 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
214 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
215 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
217 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
218 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
220 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
221 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
223 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
224 stats
.bounces
[i
] += pcs
->bounces
[i
];
230 void clear_lock_stats(struct lock_class
*class)
234 for_each_possible_cpu(cpu
) {
235 struct lock_class_stats
*cpu_stats
=
236 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
238 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
240 memset(class->contention_point
, 0, sizeof(class->contention_point
));
241 memset(class->contending_point
, 0, sizeof(class->contending_point
));
244 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
246 return &get_cpu_var(cpu_lock_stats
)[class - lock_classes
];
249 static void put_lock_stats(struct lock_class_stats
*stats
)
251 put_cpu_var(cpu_lock_stats
);
254 static void lock_release_holdtime(struct held_lock
*hlock
)
256 struct lock_class_stats
*stats
;
262 holdtime
= lockstat_clock() - hlock
->holdtime_stamp
;
264 stats
= get_lock_stats(hlock_class(hlock
));
266 lock_time_inc(&stats
->read_holdtime
, holdtime
);
268 lock_time_inc(&stats
->write_holdtime
, holdtime
);
269 put_lock_stats(stats
);
272 static inline void lock_release_holdtime(struct held_lock
*hlock
)
278 * We keep a global list of all lock classes. The list only grows,
279 * never shrinks. The list is only accessed with the lockdep
280 * spinlock lock held.
282 LIST_HEAD(all_lock_classes
);
285 * The lockdep classes are in a hash-table as well, for fast lookup:
287 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
288 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
289 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
290 #define classhashentry(key) (classhash_table + __classhashfn((key)))
292 static struct hlist_head classhash_table
[CLASSHASH_SIZE
];
295 * We put the lock dependency chains into a hash-table as well, to cache
298 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
299 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
300 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
301 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
303 static struct hlist_head chainhash_table
[CHAINHASH_SIZE
];
306 * The hash key of the lock dependency chains is a hash itself too:
307 * it's a hash of all locks taken up to that lock, including that lock.
308 * It's a 64-bit hash, because it's important for the keys to be
311 #define iterate_chain_key(key1, key2) \
312 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
313 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
316 void lockdep_off(void)
318 current
->lockdep_recursion
++;
320 EXPORT_SYMBOL(lockdep_off
);
322 void lockdep_on(void)
324 current
->lockdep_recursion
--;
326 EXPORT_SYMBOL(lockdep_on
);
329 * Debugging switches:
333 #define VERY_VERBOSE 0
336 # define HARDIRQ_VERBOSE 1
337 # define SOFTIRQ_VERBOSE 1
338 # define RECLAIM_VERBOSE 1
340 # define HARDIRQ_VERBOSE 0
341 # define SOFTIRQ_VERBOSE 0
342 # define RECLAIM_VERBOSE 0
345 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
347 * Quick filtering for interesting events:
349 static int class_filter(struct lock_class
*class)
353 if (class->name_version
== 1 &&
354 !strcmp(class->name
, "lockname"))
356 if (class->name_version
== 1 &&
357 !strcmp(class->name
, "&struct->lockfield"))
360 /* Filter everything else. 1 would be to allow everything else */
365 static int verbose(struct lock_class
*class)
368 return class_filter(class);
374 * Stack-trace: tightly packed array of stack backtrace
375 * addresses. Protected by the graph_lock.
377 unsigned long nr_stack_trace_entries
;
378 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
380 static void print_lockdep_off(const char *bug_msg
)
382 printk(KERN_DEBUG
"%s\n", bug_msg
);
383 printk(KERN_DEBUG
"turning off the locking correctness validator.\n");
384 #ifdef CONFIG_LOCK_STAT
385 printk(KERN_DEBUG
"Please attach the output of /proc/lock_stat to the bug report\n");
389 static int save_trace(struct stack_trace
*trace
)
391 trace
->nr_entries
= 0;
392 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
393 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
397 save_stack_trace(trace
);
400 * Some daft arches put -1 at the end to indicate its a full trace.
402 * <rant> this is buggy anyway, since it takes a whole extra entry so a
403 * complete trace that maxes out the entries provided will be reported
404 * as incomplete, friggin useless </rant>
406 if (trace
->nr_entries
!= 0 &&
407 trace
->entries
[trace
->nr_entries
-1] == ULONG_MAX
)
410 trace
->max_entries
= trace
->nr_entries
;
412 nr_stack_trace_entries
+= trace
->nr_entries
;
414 if (nr_stack_trace_entries
>= MAX_STACK_TRACE_ENTRIES
-1) {
415 if (!debug_locks_off_graph_unlock())
418 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
427 unsigned int nr_hardirq_chains
;
428 unsigned int nr_softirq_chains
;
429 unsigned int nr_process_chains
;
430 unsigned int max_lockdep_depth
;
432 #ifdef CONFIG_DEBUG_LOCKDEP
434 * Various lockdep statistics:
436 DEFINE_PER_CPU(struct lockdep_stats
, lockdep_stats
);
443 #define __USAGE(__STATE) \
444 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
445 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
446 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
447 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
449 static const char *usage_str
[] =
451 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
452 #include "lockdep_states.h"
454 [LOCK_USED
] = "INITIAL USE",
457 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
459 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
462 static inline unsigned long lock_flag(enum lock_usage_bit bit
)
467 static char get_usage_char(struct lock_class
*class, enum lock_usage_bit bit
)
471 if (class->usage_mask
& lock_flag(bit
+ 2))
473 if (class->usage_mask
& lock_flag(bit
)) {
475 if (class->usage_mask
& lock_flag(bit
+ 2))
482 void get_usage_chars(struct lock_class
*class, char usage
[LOCK_USAGE_CHARS
])
486 #define LOCKDEP_STATE(__STATE) \
487 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
488 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
489 #include "lockdep_states.h"
495 static void __print_lock_name(struct lock_class
*class)
497 char str
[KSYM_NAME_LEN
];
502 name
= __get_key_name(class->key
, str
);
506 if (class->name_version
> 1)
507 printk("#%d", class->name_version
);
509 printk("/%d", class->subclass
);
513 static void print_lock_name(struct lock_class
*class)
515 char usage
[LOCK_USAGE_CHARS
];
517 get_usage_chars(class, usage
);
520 __print_lock_name(class);
521 printk("){%s}", usage
);
524 static void print_lockdep_cache(struct lockdep_map
*lock
)
527 char str
[KSYM_NAME_LEN
];
531 name
= __get_key_name(lock
->key
->subkeys
, str
);
536 static void print_lock(struct held_lock
*hlock
)
539 * We can be called locklessly through debug_show_all_locks() so be
540 * extra careful, the hlock might have been released and cleared.
542 unsigned int class_idx
= hlock
->class_idx
;
544 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
547 if (!class_idx
|| (class_idx
- 1) >= MAX_LOCKDEP_KEYS
) {
548 printk("<RELEASED>\n");
552 print_lock_name(lock_classes
+ class_idx
- 1);
554 print_ip_sym(hlock
->acquire_ip
);
557 static void lockdep_print_held_locks(struct task_struct
*curr
)
559 int i
, depth
= curr
->lockdep_depth
;
562 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
565 printk("%d lock%s held by %s/%d:\n",
566 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
568 for (i
= 0; i
< depth
; i
++) {
570 print_lock(curr
->held_locks
+ i
);
574 static void print_kernel_ident(void)
576 printk("%s %.*s %s\n", init_utsname()->release
,
577 (int)strcspn(init_utsname()->version
, " "),
578 init_utsname()->version
,
582 static int very_verbose(struct lock_class
*class)
585 return class_filter(class);
591 * Is this the address of a static object:
594 static int static_obj(void *obj
)
596 unsigned long start
= (unsigned long) &_stext
,
597 end
= (unsigned long) &_end
,
598 addr
= (unsigned long) obj
;
603 if ((addr
>= start
) && (addr
< end
))
606 if (arch_is_kernel_data(addr
))
610 * in-kernel percpu var?
612 if (is_kernel_percpu_address(addr
))
616 * module static or percpu var?
618 return is_module_address(addr
) || is_module_percpu_address(addr
);
623 * To make lock name printouts unique, we calculate a unique
624 * class->name_version generation counter:
626 static int count_matching_names(struct lock_class
*new_class
)
628 struct lock_class
*class;
631 if (!new_class
->name
)
634 list_for_each_entry_rcu(class, &all_lock_classes
, lock_entry
) {
635 if (new_class
->key
- new_class
->subclass
== class->key
)
636 return class->name_version
;
637 if (class->name
&& !strcmp(class->name
, new_class
->name
))
638 count
= max(count
, class->name_version
);
645 * Register a lock's class in the hash-table, if the class is not present
646 * yet. Otherwise we look it up. We cache the result in the lock object
647 * itself, so actual lookup of the hash should be once per lock object.
649 static inline struct lock_class
*
650 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
652 struct lockdep_subclass_key
*key
;
653 struct hlist_head
*hash_head
;
654 struct lock_class
*class;
656 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
659 "BUG: looking up invalid subclass: %u\n", subclass
);
661 "turning off the locking correctness validator.\n");
667 * Static locks do not have their class-keys yet - for them the key
668 * is the lock object itself:
670 if (unlikely(!lock
->key
))
671 lock
->key
= (void *)lock
;
674 * NOTE: the class-key must be unique. For dynamic locks, a static
675 * lock_class_key variable is passed in through the mutex_init()
676 * (or spin_lock_init()) call - which acts as the key. For static
677 * locks we use the lock object itself as the key.
679 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
680 sizeof(struct lockdep_map
));
682 key
= lock
->key
->subkeys
+ subclass
;
684 hash_head
= classhashentry(key
);
687 * We do an RCU walk of the hash, see lockdep_free_key_range().
689 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
692 hlist_for_each_entry_rcu(class, hash_head
, hash_entry
) {
693 if (class->key
== key
) {
695 * Huh! same key, different name? Did someone trample
696 * on some memory? We're most confused.
698 WARN_ON_ONCE(class->name
!= lock
->name
);
707 * Register a lock's class in the hash-table, if the class is not present
708 * yet. Otherwise we look it up. We cache the result in the lock object
709 * itself, so actual lookup of the hash should be once per lock object.
711 static inline struct lock_class
*
712 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
714 struct lockdep_subclass_key
*key
;
715 struct hlist_head
*hash_head
;
716 struct lock_class
*class;
718 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
720 class = look_up_lock_class(lock
, subclass
);
722 goto out_set_class_cache
;
725 * Debug-check: all keys must be persistent!
727 if (!static_obj(lock
->key
)) {
729 printk("INFO: trying to register non-static key.\n");
730 printk("the code is fine but needs lockdep annotation.\n");
731 printk("turning off the locking correctness validator.\n");
737 key
= lock
->key
->subkeys
+ subclass
;
738 hash_head
= classhashentry(key
);
744 * We have to do the hash-walk again, to avoid races
747 hlist_for_each_entry_rcu(class, hash_head
, hash_entry
) {
748 if (class->key
== key
)
753 * Allocate a new key from the static array, and add it to
756 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
757 if (!debug_locks_off_graph_unlock()) {
761 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
765 class = lock_classes
+ nr_lock_classes
++;
766 debug_atomic_inc(nr_unused_locks
);
768 class->name
= lock
->name
;
769 class->subclass
= subclass
;
770 INIT_LIST_HEAD(&class->lock_entry
);
771 INIT_LIST_HEAD(&class->locks_before
);
772 INIT_LIST_HEAD(&class->locks_after
);
773 class->name_version
= count_matching_names(class);
775 * We use RCU's safe list-add method to make
776 * parallel walking of the hash-list safe:
778 hlist_add_head_rcu(&class->hash_entry
, hash_head
);
780 * Add it to the global list of classes:
782 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
784 if (verbose(class)) {
787 printk("\nnew class %p: %s", class->key
, class->name
);
788 if (class->name_version
> 1)
789 printk("#%d", class->name_version
);
801 if (!subclass
|| force
)
802 lock
->class_cache
[0] = class;
803 else if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
804 lock
->class_cache
[subclass
] = class;
807 * Hash collision, did we smoke some? We found a class with a matching
808 * hash but the subclass -- which is hashed in -- didn't match.
810 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
816 #ifdef CONFIG_PROVE_LOCKING
818 * Allocate a lockdep entry. (assumes the graph_lock held, returns
819 * with NULL on failure)
821 static struct lock_list
*alloc_list_entry(void)
823 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
824 if (!debug_locks_off_graph_unlock())
827 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
831 return list_entries
+ nr_list_entries
++;
835 * Add a new dependency to the head of the list:
837 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
838 struct list_head
*head
, unsigned long ip
,
839 int distance
, struct stack_trace
*trace
)
841 struct lock_list
*entry
;
843 * Lock not present yet - get a new dependency struct and
844 * add it to the list:
846 entry
= alloc_list_entry();
851 entry
->distance
= distance
;
852 entry
->trace
= *trace
;
854 * Both allocation and removal are done under the graph lock; but
855 * iteration is under RCU-sched; see look_up_lock_class() and
856 * lockdep_free_key_range().
858 list_add_tail_rcu(&entry
->entry
, head
);
864 * For good efficiency of modular, we use power of 2
866 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
867 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
870 * The circular_queue and helpers is used to implement the
871 * breadth-first search(BFS)algorithem, by which we can build
872 * the shortest path from the next lock to be acquired to the
873 * previous held lock if there is a circular between them.
875 struct circular_queue
{
876 unsigned long element
[MAX_CIRCULAR_QUEUE_SIZE
];
877 unsigned int front
, rear
;
880 static struct circular_queue lock_cq
;
882 unsigned int max_bfs_queue_depth
;
884 static unsigned int lockdep_dependency_gen_id
;
886 static inline void __cq_init(struct circular_queue
*cq
)
888 cq
->front
= cq
->rear
= 0;
889 lockdep_dependency_gen_id
++;
892 static inline int __cq_empty(struct circular_queue
*cq
)
894 return (cq
->front
== cq
->rear
);
897 static inline int __cq_full(struct circular_queue
*cq
)
899 return ((cq
->rear
+ 1) & CQ_MASK
) == cq
->front
;
902 static inline int __cq_enqueue(struct circular_queue
*cq
, unsigned long elem
)
907 cq
->element
[cq
->rear
] = elem
;
908 cq
->rear
= (cq
->rear
+ 1) & CQ_MASK
;
912 static inline int __cq_dequeue(struct circular_queue
*cq
, unsigned long *elem
)
917 *elem
= cq
->element
[cq
->front
];
918 cq
->front
= (cq
->front
+ 1) & CQ_MASK
;
922 static inline unsigned int __cq_get_elem_count(struct circular_queue
*cq
)
924 return (cq
->rear
- cq
->front
) & CQ_MASK
;
927 static inline void mark_lock_accessed(struct lock_list
*lock
,
928 struct lock_list
*parent
)
932 nr
= lock
- list_entries
;
933 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
934 lock
->parent
= parent
;
935 lock
->class->dep_gen_id
= lockdep_dependency_gen_id
;
938 static inline unsigned long lock_accessed(struct lock_list
*lock
)
942 nr
= lock
- list_entries
;
943 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
944 return lock
->class->dep_gen_id
== lockdep_dependency_gen_id
;
947 static inline struct lock_list
*get_lock_parent(struct lock_list
*child
)
949 return child
->parent
;
952 static inline int get_lock_depth(struct lock_list
*child
)
955 struct lock_list
*parent
;
957 while ((parent
= get_lock_parent(child
))) {
964 static int __bfs(struct lock_list
*source_entry
,
966 int (*match
)(struct lock_list
*entry
, void *data
),
967 struct lock_list
**target_entry
,
970 struct lock_list
*entry
;
971 struct list_head
*head
;
972 struct circular_queue
*cq
= &lock_cq
;
975 if (match(source_entry
, data
)) {
976 *target_entry
= source_entry
;
982 head
= &source_entry
->class->locks_after
;
984 head
= &source_entry
->class->locks_before
;
986 if (list_empty(head
))
990 __cq_enqueue(cq
, (unsigned long)source_entry
);
992 while (!__cq_empty(cq
)) {
993 struct lock_list
*lock
;
995 __cq_dequeue(cq
, (unsigned long *)&lock
);
1003 head
= &lock
->class->locks_after
;
1005 head
= &lock
->class->locks_before
;
1007 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1009 list_for_each_entry_rcu(entry
, head
, entry
) {
1010 if (!lock_accessed(entry
)) {
1011 unsigned int cq_depth
;
1012 mark_lock_accessed(entry
, lock
);
1013 if (match(entry
, data
)) {
1014 *target_entry
= entry
;
1019 if (__cq_enqueue(cq
, (unsigned long)entry
)) {
1023 cq_depth
= __cq_get_elem_count(cq
);
1024 if (max_bfs_queue_depth
< cq_depth
)
1025 max_bfs_queue_depth
= cq_depth
;
1033 static inline int __bfs_forwards(struct lock_list
*src_entry
,
1035 int (*match
)(struct lock_list
*entry
, void *data
),
1036 struct lock_list
**target_entry
)
1038 return __bfs(src_entry
, data
, match
, target_entry
, 1);
1042 static inline int __bfs_backwards(struct lock_list
*src_entry
,
1044 int (*match
)(struct lock_list
*entry
, void *data
),
1045 struct lock_list
**target_entry
)
1047 return __bfs(src_entry
, data
, match
, target_entry
, 0);
1052 * Recursive, forwards-direction lock-dependency checking, used for
1053 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1058 * Print a dependency chain entry (this is only done when a deadlock
1059 * has been detected):
1062 print_circular_bug_entry(struct lock_list
*target
, int depth
)
1064 if (debug_locks_silent
)
1066 printk("\n-> #%u", depth
);
1067 print_lock_name(target
->class);
1069 print_stack_trace(&target
->trace
, 6);
1075 print_circular_lock_scenario(struct held_lock
*src
,
1076 struct held_lock
*tgt
,
1077 struct lock_list
*prt
)
1079 struct lock_class
*source
= hlock_class(src
);
1080 struct lock_class
*target
= hlock_class(tgt
);
1081 struct lock_class
*parent
= prt
->class;
1084 * A direct locking problem where unsafe_class lock is taken
1085 * directly by safe_class lock, then all we need to show
1086 * is the deadlock scenario, as it is obvious that the
1087 * unsafe lock is taken under the safe lock.
1089 * But if there is a chain instead, where the safe lock takes
1090 * an intermediate lock (middle_class) where this lock is
1091 * not the same as the safe lock, then the lock chain is
1092 * used to describe the problem. Otherwise we would need
1093 * to show a different CPU case for each link in the chain
1094 * from the safe_class lock to the unsafe_class lock.
1096 if (parent
!= source
) {
1097 printk("Chain exists of:\n ");
1098 __print_lock_name(source
);
1100 __print_lock_name(parent
);
1102 __print_lock_name(target
);
1106 printk(" Possible unsafe locking scenario:\n\n");
1107 printk(" CPU0 CPU1\n");
1108 printk(" ---- ----\n");
1110 __print_lock_name(target
);
1113 __print_lock_name(parent
);
1116 __print_lock_name(target
);
1119 __print_lock_name(source
);
1121 printk("\n *** DEADLOCK ***\n\n");
1125 * When a circular dependency is detected, print the
1129 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
,
1130 struct held_lock
*check_src
,
1131 struct held_lock
*check_tgt
)
1133 struct task_struct
*curr
= current
;
1135 if (debug_locks_silent
)
1139 printk("======================================================\n");
1140 printk("[ INFO: possible circular locking dependency detected ]\n");
1141 print_kernel_ident();
1142 printk("-------------------------------------------------------\n");
1143 printk("%s/%d is trying to acquire lock:\n",
1144 curr
->comm
, task_pid_nr(curr
));
1145 print_lock(check_src
);
1146 printk("\nbut task is already holding lock:\n");
1147 print_lock(check_tgt
);
1148 printk("\nwhich lock already depends on the new lock.\n\n");
1149 printk("\nthe existing dependency chain (in reverse order) is:\n");
1151 print_circular_bug_entry(entry
, depth
);
1156 static inline int class_equal(struct lock_list
*entry
, void *data
)
1158 return entry
->class == data
;
1161 static noinline
int print_circular_bug(struct lock_list
*this,
1162 struct lock_list
*target
,
1163 struct held_lock
*check_src
,
1164 struct held_lock
*check_tgt
)
1166 struct task_struct
*curr
= current
;
1167 struct lock_list
*parent
;
1168 struct lock_list
*first_parent
;
1171 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1174 if (!save_trace(&this->trace
))
1177 depth
= get_lock_depth(target
);
1179 print_circular_bug_header(target
, depth
, check_src
, check_tgt
);
1181 parent
= get_lock_parent(target
);
1182 first_parent
= parent
;
1185 print_circular_bug_entry(parent
, --depth
);
1186 parent
= get_lock_parent(parent
);
1189 printk("\nother info that might help us debug this:\n\n");
1190 print_circular_lock_scenario(check_src
, check_tgt
,
1193 lockdep_print_held_locks(curr
);
1195 printk("\nstack backtrace:\n");
1201 static noinline
int print_bfs_bug(int ret
)
1203 if (!debug_locks_off_graph_unlock())
1207 * Breadth-first-search failed, graph got corrupted?
1209 WARN(1, "lockdep bfs error:%d\n", ret
);
1214 static int noop_count(struct lock_list
*entry
, void *data
)
1216 (*(unsigned long *)data
)++;
1220 static unsigned long __lockdep_count_forward_deps(struct lock_list
*this)
1222 unsigned long count
= 0;
1223 struct lock_list
*uninitialized_var(target_entry
);
1225 __bfs_forwards(this, (void *)&count
, noop_count
, &target_entry
);
1229 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1231 unsigned long ret
, flags
;
1232 struct lock_list
this;
1237 local_irq_save(flags
);
1238 arch_spin_lock(&lockdep_lock
);
1239 ret
= __lockdep_count_forward_deps(&this);
1240 arch_spin_unlock(&lockdep_lock
);
1241 local_irq_restore(flags
);
1246 static unsigned long __lockdep_count_backward_deps(struct lock_list
*this)
1248 unsigned long count
= 0;
1249 struct lock_list
*uninitialized_var(target_entry
);
1251 __bfs_backwards(this, (void *)&count
, noop_count
, &target_entry
);
1256 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1258 unsigned long ret
, flags
;
1259 struct lock_list
this;
1264 local_irq_save(flags
);
1265 arch_spin_lock(&lockdep_lock
);
1266 ret
= __lockdep_count_backward_deps(&this);
1267 arch_spin_unlock(&lockdep_lock
);
1268 local_irq_restore(flags
);
1274 * Prove that the dependency graph starting at <entry> can not
1275 * lead to <target>. Print an error and return 0 if it does.
1278 check_noncircular(struct lock_list
*root
, struct lock_class
*target
,
1279 struct lock_list
**target_entry
)
1283 debug_atomic_inc(nr_cyclic_checks
);
1285 result
= __bfs_forwards(root
, target
, class_equal
, target_entry
);
1290 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1292 * Forwards and backwards subgraph searching, for the purposes of
1293 * proving that two subgraphs can be connected by a new dependency
1294 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1297 static inline int usage_match(struct lock_list
*entry
, void *bit
)
1299 return entry
->class->usage_mask
& (1 << (enum lock_usage_bit
)bit
);
1305 * Find a node in the forwards-direction dependency sub-graph starting
1306 * at @root->class that matches @bit.
1308 * Return 0 if such a node exists in the subgraph, and put that node
1309 * into *@target_entry.
1311 * Return 1 otherwise and keep *@target_entry unchanged.
1312 * Return <0 on error.
1315 find_usage_forwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1316 struct lock_list
**target_entry
)
1320 debug_atomic_inc(nr_find_usage_forwards_checks
);
1322 result
= __bfs_forwards(root
, (void *)bit
, usage_match
, target_entry
);
1328 * Find a node in the backwards-direction dependency sub-graph starting
1329 * at @root->class that matches @bit.
1331 * Return 0 if such a node exists in the subgraph, and put that node
1332 * into *@target_entry.
1334 * Return 1 otherwise and keep *@target_entry unchanged.
1335 * Return <0 on error.
1338 find_usage_backwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1339 struct lock_list
**target_entry
)
1343 debug_atomic_inc(nr_find_usage_backwards_checks
);
1345 result
= __bfs_backwards(root
, (void *)bit
, usage_match
, target_entry
);
1350 static void print_lock_class_header(struct lock_class
*class, int depth
)
1354 printk("%*s->", depth
, "");
1355 print_lock_name(class);
1356 printk(" ops: %lu", class->ops
);
1359 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
1360 if (class->usage_mask
& (1 << bit
)) {
1363 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
1364 len
+= printk(" at:\n");
1365 print_stack_trace(class->usage_traces
+ bit
, len
);
1368 printk("%*s }\n", depth
, "");
1370 printk("%*s ... key at: ",depth
,"");
1371 print_ip_sym((unsigned long)class->key
);
1375 * printk the shortest lock dependencies from @start to @end in reverse order:
1378 print_shortest_lock_dependencies(struct lock_list
*leaf
,
1379 struct lock_list
*root
)
1381 struct lock_list
*entry
= leaf
;
1384 /*compute depth from generated tree by BFS*/
1385 depth
= get_lock_depth(leaf
);
1388 print_lock_class_header(entry
->class, depth
);
1389 printk("%*s ... acquired at:\n", depth
, "");
1390 print_stack_trace(&entry
->trace
, 2);
1393 if (depth
== 0 && (entry
!= root
)) {
1394 printk("lockdep:%s bad path found in chain graph\n", __func__
);
1398 entry
= get_lock_parent(entry
);
1400 } while (entry
&& (depth
>= 0));
1406 print_irq_lock_scenario(struct lock_list
*safe_entry
,
1407 struct lock_list
*unsafe_entry
,
1408 struct lock_class
*prev_class
,
1409 struct lock_class
*next_class
)
1411 struct lock_class
*safe_class
= safe_entry
->class;
1412 struct lock_class
*unsafe_class
= unsafe_entry
->class;
1413 struct lock_class
*middle_class
= prev_class
;
1415 if (middle_class
== safe_class
)
1416 middle_class
= next_class
;
1419 * A direct locking problem where unsafe_class lock is taken
1420 * directly by safe_class lock, then all we need to show
1421 * is the deadlock scenario, as it is obvious that the
1422 * unsafe lock is taken under the safe lock.
1424 * But if there is a chain instead, where the safe lock takes
1425 * an intermediate lock (middle_class) where this lock is
1426 * not the same as the safe lock, then the lock chain is
1427 * used to describe the problem. Otherwise we would need
1428 * to show a different CPU case for each link in the chain
1429 * from the safe_class lock to the unsafe_class lock.
1431 if (middle_class
!= unsafe_class
) {
1432 printk("Chain exists of:\n ");
1433 __print_lock_name(safe_class
);
1435 __print_lock_name(middle_class
);
1437 __print_lock_name(unsafe_class
);
1441 printk(" Possible interrupt unsafe locking scenario:\n\n");
1442 printk(" CPU0 CPU1\n");
1443 printk(" ---- ----\n");
1445 __print_lock_name(unsafe_class
);
1447 printk(" local_irq_disable();\n");
1449 __print_lock_name(safe_class
);
1452 __print_lock_name(middle_class
);
1454 printk(" <Interrupt>\n");
1456 __print_lock_name(safe_class
);
1458 printk("\n *** DEADLOCK ***\n\n");
1462 print_bad_irq_dependency(struct task_struct
*curr
,
1463 struct lock_list
*prev_root
,
1464 struct lock_list
*next_root
,
1465 struct lock_list
*backwards_entry
,
1466 struct lock_list
*forwards_entry
,
1467 struct held_lock
*prev
,
1468 struct held_lock
*next
,
1469 enum lock_usage_bit bit1
,
1470 enum lock_usage_bit bit2
,
1471 const char *irqclass
)
1473 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1477 printk("======================================================\n");
1478 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1479 irqclass
, irqclass
);
1480 print_kernel_ident();
1481 printk("------------------------------------------------------\n");
1482 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1483 curr
->comm
, task_pid_nr(curr
),
1484 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1485 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1486 curr
->hardirqs_enabled
,
1487 curr
->softirqs_enabled
);
1490 printk("\nand this task is already holding:\n");
1492 printk("which would create a new lock dependency:\n");
1493 print_lock_name(hlock_class(prev
));
1495 print_lock_name(hlock_class(next
));
1498 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1500 print_lock_name(backwards_entry
->class);
1501 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1503 print_stack_trace(backwards_entry
->class->usage_traces
+ bit1
, 1);
1505 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1506 print_lock_name(forwards_entry
->class);
1507 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1510 print_stack_trace(forwards_entry
->class->usage_traces
+ bit2
, 1);
1512 printk("\nother info that might help us debug this:\n\n");
1513 print_irq_lock_scenario(backwards_entry
, forwards_entry
,
1514 hlock_class(prev
), hlock_class(next
));
1516 lockdep_print_held_locks(curr
);
1518 printk("\nthe dependencies between %s-irq-safe lock", irqclass
);
1519 printk(" and the holding lock:\n");
1520 if (!save_trace(&prev_root
->trace
))
1522 print_shortest_lock_dependencies(backwards_entry
, prev_root
);
1524 printk("\nthe dependencies between the lock to be acquired");
1525 printk(" and %s-irq-unsafe lock:\n", irqclass
);
1526 if (!save_trace(&next_root
->trace
))
1528 print_shortest_lock_dependencies(forwards_entry
, next_root
);
1530 printk("\nstack backtrace:\n");
1537 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1538 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1539 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1542 struct lock_list
this, that
;
1543 struct lock_list
*uninitialized_var(target_entry
);
1544 struct lock_list
*uninitialized_var(target_entry1
);
1548 this.class = hlock_class(prev
);
1549 ret
= find_usage_backwards(&this, bit_backwards
, &target_entry
);
1551 return print_bfs_bug(ret
);
1556 that
.class = hlock_class(next
);
1557 ret
= find_usage_forwards(&that
, bit_forwards
, &target_entry1
);
1559 return print_bfs_bug(ret
);
1563 return print_bad_irq_dependency(curr
, &this, &that
,
1564 target_entry
, target_entry1
,
1566 bit_backwards
, bit_forwards
, irqclass
);
1569 static const char *state_names
[] = {
1570 #define LOCKDEP_STATE(__STATE) \
1571 __stringify(__STATE),
1572 #include "lockdep_states.h"
1573 #undef LOCKDEP_STATE
1576 static const char *state_rnames
[] = {
1577 #define LOCKDEP_STATE(__STATE) \
1578 __stringify(__STATE)"-READ",
1579 #include "lockdep_states.h"
1580 #undef LOCKDEP_STATE
1583 static inline const char *state_name(enum lock_usage_bit bit
)
1585 return (bit
& 1) ? state_rnames
[bit
>> 2] : state_names
[bit
>> 2];
1588 static int exclusive_bit(int new_bit
)
1596 * bit 0 - write/read
1597 * bit 1 - used_in/enabled
1601 int state
= new_bit
& ~3;
1602 int dir
= new_bit
& 2;
1605 * keep state, bit flip the direction and strip read.
1607 return state
| (dir
^ 2);
1610 static int check_irq_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1611 struct held_lock
*next
, enum lock_usage_bit bit
)
1614 * Prove that the new dependency does not connect a hardirq-safe
1615 * lock with a hardirq-unsafe lock - to achieve this we search
1616 * the backwards-subgraph starting at <prev>, and the
1617 * forwards-subgraph starting at <next>:
1619 if (!check_usage(curr
, prev
, next
, bit
,
1620 exclusive_bit(bit
), state_name(bit
)))
1626 * Prove that the new dependency does not connect a hardirq-safe-read
1627 * lock with a hardirq-unsafe lock - to achieve this we search
1628 * the backwards-subgraph starting at <prev>, and the
1629 * forwards-subgraph starting at <next>:
1631 if (!check_usage(curr
, prev
, next
, bit
,
1632 exclusive_bit(bit
), state_name(bit
)))
1639 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1640 struct held_lock
*next
)
1642 #define LOCKDEP_STATE(__STATE) \
1643 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1645 #include "lockdep_states.h"
1646 #undef LOCKDEP_STATE
1651 static void inc_chains(void)
1653 if (current
->hardirq_context
)
1654 nr_hardirq_chains
++;
1656 if (current
->softirq_context
)
1657 nr_softirq_chains
++;
1659 nr_process_chains
++;
1666 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1667 struct held_lock
*next
)
1672 static inline void inc_chains(void)
1674 nr_process_chains
++;
1680 print_deadlock_scenario(struct held_lock
*nxt
,
1681 struct held_lock
*prv
)
1683 struct lock_class
*next
= hlock_class(nxt
);
1684 struct lock_class
*prev
= hlock_class(prv
);
1686 printk(" Possible unsafe locking scenario:\n\n");
1690 __print_lock_name(prev
);
1693 __print_lock_name(next
);
1695 printk("\n *** DEADLOCK ***\n\n");
1696 printk(" May be due to missing lock nesting notation\n\n");
1700 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1701 struct held_lock
*next
)
1703 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1707 printk("=============================================\n");
1708 printk("[ INFO: possible recursive locking detected ]\n");
1709 print_kernel_ident();
1710 printk("---------------------------------------------\n");
1711 printk("%s/%d is trying to acquire lock:\n",
1712 curr
->comm
, task_pid_nr(curr
));
1714 printk("\nbut task is already holding lock:\n");
1717 printk("\nother info that might help us debug this:\n");
1718 print_deadlock_scenario(next
, prev
);
1719 lockdep_print_held_locks(curr
);
1721 printk("\nstack backtrace:\n");
1728 * Check whether we are holding such a class already.
1730 * (Note that this has to be done separately, because the graph cannot
1731 * detect such classes of deadlocks.)
1733 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1736 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1737 struct lockdep_map
*next_instance
, int read
)
1739 struct held_lock
*prev
;
1740 struct held_lock
*nest
= NULL
;
1743 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1744 prev
= curr
->held_locks
+ i
;
1746 if (prev
->instance
== next
->nest_lock
)
1749 if (hlock_class(prev
) != hlock_class(next
))
1753 * Allow read-after-read recursion of the same
1754 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1756 if ((read
== 2) && prev
->read
)
1760 * We're holding the nest_lock, which serializes this lock's
1761 * nesting behaviour.
1766 return print_deadlock_bug(curr
, prev
, next
);
1772 * There was a chain-cache miss, and we are about to add a new dependency
1773 * to a previous lock. We recursively validate the following rules:
1775 * - would the adding of the <prev> -> <next> dependency create a
1776 * circular dependency in the graph? [== circular deadlock]
1778 * - does the new prev->next dependency connect any hardirq-safe lock
1779 * (in the full backwards-subgraph starting at <prev>) with any
1780 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1781 * <next>)? [== illegal lock inversion with hardirq contexts]
1783 * - does the new prev->next dependency connect any softirq-safe lock
1784 * (in the full backwards-subgraph starting at <prev>) with any
1785 * softirq-unsafe lock (in the full forwards-subgraph starting at
1786 * <next>)? [== illegal lock inversion with softirq contexts]
1788 * any of these scenarios could lead to a deadlock.
1790 * Then if all the validations pass, we add the forwards and backwards
1794 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1795 struct held_lock
*next
, int distance
, int *stack_saved
)
1797 struct lock_list
*entry
;
1799 struct lock_list
this;
1800 struct lock_list
*uninitialized_var(target_entry
);
1802 * Static variable, serialized by the graph_lock().
1804 * We use this static variable to save the stack trace in case
1805 * we call into this function multiple times due to encountering
1806 * trylocks in the held lock stack.
1808 static struct stack_trace trace
;
1811 * Prove that the new <prev> -> <next> dependency would not
1812 * create a circular dependency in the graph. (We do this by
1813 * forward-recursing into the graph starting at <next>, and
1814 * checking whether we can reach <prev>.)
1816 * We are using global variables to control the recursion, to
1817 * keep the stackframe size of the recursive functions low:
1819 this.class = hlock_class(next
);
1821 ret
= check_noncircular(&this, hlock_class(prev
), &target_entry
);
1823 return print_circular_bug(&this, target_entry
, next
, prev
);
1824 else if (unlikely(ret
< 0))
1825 return print_bfs_bug(ret
);
1827 if (!check_prev_add_irq(curr
, prev
, next
))
1831 * For recursive read-locks we do all the dependency checks,
1832 * but we dont store read-triggered dependencies (only
1833 * write-triggered dependencies). This ensures that only the
1834 * write-side dependencies matter, and that if for example a
1835 * write-lock never takes any other locks, then the reads are
1836 * equivalent to a NOP.
1838 if (next
->read
== 2 || prev
->read
== 2)
1841 * Is the <prev> -> <next> dependency already present?
1843 * (this may occur even though this is a new chain: consider
1844 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1845 * chains - the second one will be new, but L1 already has
1846 * L2 added to its dependency list, due to the first chain.)
1848 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1849 if (entry
->class == hlock_class(next
)) {
1851 entry
->distance
= 1;
1856 if (!*stack_saved
) {
1857 if (!save_trace(&trace
))
1863 * Ok, all validations passed, add the new lock
1864 * to the previous lock's dependency list:
1866 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1867 &hlock_class(prev
)->locks_after
,
1868 next
->acquire_ip
, distance
, &trace
);
1873 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1874 &hlock_class(next
)->locks_before
,
1875 next
->acquire_ip
, distance
, &trace
);
1880 * Debugging printouts:
1882 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1883 /* We drop graph lock, so another thread can overwrite trace. */
1886 printk("\n new dependency: ");
1887 print_lock_name(hlock_class(prev
));
1889 print_lock_name(hlock_class(next
));
1892 return graph_lock();
1898 * Add the dependency to all directly-previous locks that are 'relevant'.
1899 * The ones that are relevant are (in increasing distance from curr):
1900 * all consecutive trylock entries and the final non-trylock entry - or
1901 * the end of this context's lock-chain - whichever comes first.
1904 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1906 int depth
= curr
->lockdep_depth
;
1907 int stack_saved
= 0;
1908 struct held_lock
*hlock
;
1913 * Depth must not be zero for a non-head lock:
1918 * At least two relevant locks must exist for this
1921 if (curr
->held_locks
[depth
].irq_context
!=
1922 curr
->held_locks
[depth
-1].irq_context
)
1926 int distance
= curr
->lockdep_depth
- depth
+ 1;
1927 hlock
= curr
->held_locks
+ depth
- 1;
1929 * Only non-recursive-read entries get new dependencies
1932 if (hlock
->read
!= 2 && hlock
->check
) {
1933 if (!check_prev_add(curr
, hlock
, next
,
1934 distance
, &stack_saved
))
1937 * Stop after the first non-trylock entry,
1938 * as non-trylock entries have added their
1939 * own direct dependencies already, so this
1940 * lock is connected to them indirectly:
1942 if (!hlock
->trylock
)
1947 * End of lock-stack?
1952 * Stop the search if we cross into another context:
1954 if (curr
->held_locks
[depth
].irq_context
!=
1955 curr
->held_locks
[depth
-1].irq_context
)
1960 if (!debug_locks_off_graph_unlock())
1964 * Clearly we all shouldn't be here, but since we made it we
1965 * can reliable say we messed up our state. See the above two
1966 * gotos for reasons why we could possibly end up here.
1973 unsigned long nr_lock_chains
;
1974 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1975 int nr_chain_hlocks
;
1976 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1978 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1980 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1984 * Returns the index of the first held_lock of the current chain
1986 static inline int get_first_held_lock(struct task_struct
*curr
,
1987 struct held_lock
*hlock
)
1990 struct held_lock
*hlock_curr
;
1992 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
1993 hlock_curr
= curr
->held_locks
+ i
;
1994 if (hlock_curr
->irq_context
!= hlock
->irq_context
)
2003 * Returns the next chain_key iteration
2005 static u64
print_chain_key_iteration(int class_idx
, u64 chain_key
)
2007 u64 new_chain_key
= iterate_chain_key(chain_key
, class_idx
);
2009 printk(" class_idx:%d -> chain_key:%016Lx",
2011 (unsigned long long)new_chain_key
);
2012 return new_chain_key
;
2016 print_chain_keys_held_locks(struct task_struct
*curr
, struct held_lock
*hlock_next
)
2018 struct held_lock
*hlock
;
2020 int depth
= curr
->lockdep_depth
;
2023 printk("depth: %u\n", depth
+ 1);
2024 for (i
= get_first_held_lock(curr
, hlock_next
); i
< depth
; i
++) {
2025 hlock
= curr
->held_locks
+ i
;
2026 chain_key
= print_chain_key_iteration(hlock
->class_idx
, chain_key
);
2031 print_chain_key_iteration(hlock_next
->class_idx
, chain_key
);
2032 print_lock(hlock_next
);
2035 static void print_chain_keys_chain(struct lock_chain
*chain
)
2041 printk("depth: %u\n", chain
->depth
);
2042 for (i
= 0; i
< chain
->depth
; i
++) {
2043 class_id
= chain_hlocks
[chain
->base
+ i
];
2044 chain_key
= print_chain_key_iteration(class_id
+ 1, chain_key
);
2046 print_lock_name(lock_classes
+ class_id
);
2051 static void print_collision(struct task_struct
*curr
,
2052 struct held_lock
*hlock_next
,
2053 struct lock_chain
*chain
)
2056 printk("======================\n");
2057 printk("[chain_key collision ]\n");
2058 print_kernel_ident();
2059 printk("----------------------\n");
2060 printk("%s/%d: ", current
->comm
, task_pid_nr(current
));
2061 printk("Hash chain already cached but the contents don't match!\n");
2063 printk("Held locks:");
2064 print_chain_keys_held_locks(curr
, hlock_next
);
2066 printk("Locks in cached chain:");
2067 print_chain_keys_chain(chain
);
2069 printk("\nstack backtrace:\n");
2074 * Checks whether the chain and the current held locks are consistent
2075 * in depth and also in content. If they are not it most likely means
2076 * that there was a collision during the calculation of the chain_key.
2077 * Returns: 0 not passed, 1 passed
2079 static int check_no_collision(struct task_struct
*curr
,
2080 struct held_lock
*hlock
,
2081 struct lock_chain
*chain
)
2083 #ifdef CONFIG_DEBUG_LOCKDEP
2086 i
= get_first_held_lock(curr
, hlock
);
2088 if (DEBUG_LOCKS_WARN_ON(chain
->depth
!= curr
->lockdep_depth
- (i
- 1))) {
2089 print_collision(curr
, hlock
, chain
);
2093 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2094 id
= curr
->held_locks
[i
].class_idx
- 1;
2096 if (DEBUG_LOCKS_WARN_ON(chain_hlocks
[chain
->base
+ j
] != id
)) {
2097 print_collision(curr
, hlock
, chain
);
2106 * Look up a dependency chain. If the key is not present yet then
2107 * add it and return 1 - in this case the new dependency chain is
2108 * validated. If the key is already hashed, return 0.
2109 * (On return with 1 graph_lock is held.)
2111 static inline int lookup_chain_cache(struct task_struct
*curr
,
2112 struct held_lock
*hlock
,
2115 struct lock_class
*class = hlock_class(hlock
);
2116 struct hlist_head
*hash_head
= chainhashentry(chain_key
);
2117 struct lock_chain
*chain
;
2121 * We might need to take the graph lock, ensure we've got IRQs
2122 * disabled to make this an IRQ-safe lock.. for recursion reasons
2123 * lockdep won't complain about its own locking errors.
2125 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2128 * We can walk it lock-free, because entries only get added
2131 hlist_for_each_entry_rcu(chain
, hash_head
, entry
) {
2132 if (chain
->chain_key
== chain_key
) {
2134 debug_atomic_inc(chain_lookup_hits
);
2135 if (!check_no_collision(curr
, hlock
, chain
))
2138 if (very_verbose(class))
2139 printk("\nhash chain already cached, key: "
2140 "%016Lx tail class: [%p] %s\n",
2141 (unsigned long long)chain_key
,
2142 class->key
, class->name
);
2146 if (very_verbose(class))
2147 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2148 (unsigned long long)chain_key
, class->key
, class->name
);
2150 * Allocate a new chain entry from the static array, and add
2156 * We have to walk the chain again locked - to avoid duplicates:
2158 hlist_for_each_entry(chain
, hash_head
, entry
) {
2159 if (chain
->chain_key
== chain_key
) {
2164 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
2165 if (!debug_locks_off_graph_unlock())
2168 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2172 chain
= lock_chains
+ nr_lock_chains
++;
2173 chain
->chain_key
= chain_key
;
2174 chain
->irq_context
= hlock
->irq_context
;
2175 i
= get_first_held_lock(curr
, hlock
);
2176 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
2177 if (likely(nr_chain_hlocks
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2178 chain
->base
= nr_chain_hlocks
;
2179 nr_chain_hlocks
+= chain
->depth
;
2180 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2181 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
2182 chain_hlocks
[chain
->base
+ j
] = lock_id
;
2184 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
2186 hlist_add_head_rcu(&chain
->entry
, hash_head
);
2187 debug_atomic_inc(chain_lookup_misses
);
2193 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
2194 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
2197 * Trylock needs to maintain the stack of held locks, but it
2198 * does not add new dependencies, because trylock can be done
2201 * We look up the chain_key and do the O(N^2) check and update of
2202 * the dependencies only if this is a new dependency chain.
2203 * (If lookup_chain_cache() returns with 1 it acquires
2204 * graph_lock for us)
2206 if (!hlock
->trylock
&& hlock
->check
&&
2207 lookup_chain_cache(curr
, hlock
, chain_key
)) {
2209 * Check whether last held lock:
2211 * - is irq-safe, if this lock is irq-unsafe
2212 * - is softirq-safe, if this lock is hardirq-unsafe
2214 * And check whether the new lock's dependency graph
2215 * could lead back to the previous lock.
2217 * any of these scenarios could lead to a deadlock. If
2220 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
2225 * Mark recursive read, as we jump over it when
2226 * building dependencies (just like we jump over
2232 * Add dependency only if this lock is not the head
2233 * of the chain, and if it's not a secondary read-lock:
2235 if (!chain_head
&& ret
!= 2)
2236 if (!check_prevs_add(curr
, hlock
))
2240 /* after lookup_chain_cache(): */
2241 if (unlikely(!debug_locks
))
2247 static inline int validate_chain(struct task_struct
*curr
,
2248 struct lockdep_map
*lock
, struct held_lock
*hlock
,
2249 int chain_head
, u64 chain_key
)
2256 * We are building curr_chain_key incrementally, so double-check
2257 * it from scratch, to make sure that it's done correctly:
2259 static void check_chain_key(struct task_struct
*curr
)
2261 #ifdef CONFIG_DEBUG_LOCKDEP
2262 struct held_lock
*hlock
, *prev_hlock
= NULL
;
2266 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2267 hlock
= curr
->held_locks
+ i
;
2268 if (chain_key
!= hlock
->prev_chain_key
) {
2271 * We got mighty confused, our chain keys don't match
2272 * with what we expect, someone trample on our task state?
2274 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2275 curr
->lockdep_depth
, i
,
2276 (unsigned long long)chain_key
,
2277 (unsigned long long)hlock
->prev_chain_key
);
2281 * Whoops ran out of static storage again?
2283 if (DEBUG_LOCKS_WARN_ON(hlock
->class_idx
> MAX_LOCKDEP_KEYS
))
2286 if (prev_hlock
&& (prev_hlock
->irq_context
!=
2287 hlock
->irq_context
))
2289 chain_key
= iterate_chain_key(chain_key
, hlock
->class_idx
);
2292 if (chain_key
!= curr
->curr_chain_key
) {
2295 * More smoking hash instead of calculating it, damn see these
2296 * numbers float.. I bet that a pink elephant stepped on my memory.
2298 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2299 curr
->lockdep_depth
, i
,
2300 (unsigned long long)chain_key
,
2301 (unsigned long long)curr
->curr_chain_key
);
2307 print_usage_bug_scenario(struct held_lock
*lock
)
2309 struct lock_class
*class = hlock_class(lock
);
2311 printk(" Possible unsafe locking scenario:\n\n");
2315 __print_lock_name(class);
2317 printk(" <Interrupt>\n");
2319 __print_lock_name(class);
2321 printk("\n *** DEADLOCK ***\n\n");
2325 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
2326 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
2328 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2332 printk("=================================\n");
2333 printk("[ INFO: inconsistent lock state ]\n");
2334 print_kernel_ident();
2335 printk("---------------------------------\n");
2337 printk("inconsistent {%s} -> {%s} usage.\n",
2338 usage_str
[prev_bit
], usage_str
[new_bit
]);
2340 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2341 curr
->comm
, task_pid_nr(curr
),
2342 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
2343 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
2344 trace_hardirqs_enabled(curr
),
2345 trace_softirqs_enabled(curr
));
2348 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
2349 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
2351 print_irqtrace_events(curr
);
2352 printk("\nother info that might help us debug this:\n");
2353 print_usage_bug_scenario(this);
2355 lockdep_print_held_locks(curr
);
2357 printk("\nstack backtrace:\n");
2364 * Print out an error if an invalid bit is set:
2367 valid_state(struct task_struct
*curr
, struct held_lock
*this,
2368 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
2370 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
2371 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
2375 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2376 enum lock_usage_bit new_bit
);
2378 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2381 * print irq inversion bug:
2384 print_irq_inversion_bug(struct task_struct
*curr
,
2385 struct lock_list
*root
, struct lock_list
*other
,
2386 struct held_lock
*this, int forwards
,
2387 const char *irqclass
)
2389 struct lock_list
*entry
= other
;
2390 struct lock_list
*middle
= NULL
;
2393 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2397 printk("=========================================================\n");
2398 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2399 print_kernel_ident();
2400 printk("---------------------------------------------------------\n");
2401 printk("%s/%d just changed the state of lock:\n",
2402 curr
->comm
, task_pid_nr(curr
));
2405 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass
);
2407 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass
);
2408 print_lock_name(other
->class);
2409 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2411 printk("\nother info that might help us debug this:\n");
2413 /* Find a middle lock (if one exists) */
2414 depth
= get_lock_depth(other
);
2416 if (depth
== 0 && (entry
!= root
)) {
2417 printk("lockdep:%s bad path found in chain graph\n", __func__
);
2421 entry
= get_lock_parent(entry
);
2423 } while (entry
&& entry
!= root
&& (depth
>= 0));
2425 print_irq_lock_scenario(root
, other
,
2426 middle
? middle
->class : root
->class, other
->class);
2428 print_irq_lock_scenario(other
, root
,
2429 middle
? middle
->class : other
->class, root
->class);
2431 lockdep_print_held_locks(curr
);
2433 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2434 if (!save_trace(&root
->trace
))
2436 print_shortest_lock_dependencies(other
, root
);
2438 printk("\nstack backtrace:\n");
2445 * Prove that in the forwards-direction subgraph starting at <this>
2446 * there is no lock matching <mask>:
2449 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
2450 enum lock_usage_bit bit
, const char *irqclass
)
2453 struct lock_list root
;
2454 struct lock_list
*uninitialized_var(target_entry
);
2457 root
.class = hlock_class(this);
2458 ret
= find_usage_forwards(&root
, bit
, &target_entry
);
2460 return print_bfs_bug(ret
);
2464 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2469 * Prove that in the backwards-direction subgraph starting at <this>
2470 * there is no lock matching <mask>:
2473 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
2474 enum lock_usage_bit bit
, const char *irqclass
)
2477 struct lock_list root
;
2478 struct lock_list
*uninitialized_var(target_entry
);
2481 root
.class = hlock_class(this);
2482 ret
= find_usage_backwards(&root
, bit
, &target_entry
);
2484 return print_bfs_bug(ret
);
2488 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2492 void print_irqtrace_events(struct task_struct
*curr
)
2494 printk("irq event stamp: %u\n", curr
->irq_events
);
2495 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
2496 print_ip_sym(curr
->hardirq_enable_ip
);
2497 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
2498 print_ip_sym(curr
->hardirq_disable_ip
);
2499 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
2500 print_ip_sym(curr
->softirq_enable_ip
);
2501 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
2502 print_ip_sym(curr
->softirq_disable_ip
);
2505 static int HARDIRQ_verbose(struct lock_class
*class)
2508 return class_filter(class);
2513 static int SOFTIRQ_verbose(struct lock_class
*class)
2516 return class_filter(class);
2521 static int RECLAIM_FS_verbose(struct lock_class
*class)
2524 return class_filter(class);
2529 #define STRICT_READ_CHECKS 1
2531 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2532 #define LOCKDEP_STATE(__STATE) \
2534 #include "lockdep_states.h"
2535 #undef LOCKDEP_STATE
2538 static inline int state_verbose(enum lock_usage_bit bit
,
2539 struct lock_class
*class)
2541 return state_verbose_f
[bit
>> 2](class);
2544 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2545 enum lock_usage_bit bit
, const char *name
);
2548 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2549 enum lock_usage_bit new_bit
)
2551 int excl_bit
= exclusive_bit(new_bit
);
2552 int read
= new_bit
& 1;
2553 int dir
= new_bit
& 2;
2556 * mark USED_IN has to look forwards -- to ensure no dependency
2557 * has ENABLED state, which would allow recursion deadlocks.
2559 * mark ENABLED has to look backwards -- to ensure no dependee
2560 * has USED_IN state, which, again, would allow recursion deadlocks.
2562 check_usage_f usage
= dir
?
2563 check_usage_backwards
: check_usage_forwards
;
2566 * Validate that this particular lock does not have conflicting
2569 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2573 * Validate that the lock dependencies don't have conflicting usage
2576 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2577 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2581 * Check for read in write conflicts
2584 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2587 if (STRICT_READ_CHECKS
&&
2588 !usage(curr
, this, excl_bit
+ 1,
2589 state_name(new_bit
+ 1)))
2593 if (state_verbose(new_bit
, hlock_class(this)))
2600 #define LOCKDEP_STATE(__STATE) __STATE,
2601 #include "lockdep_states.h"
2602 #undef LOCKDEP_STATE
2606 * Mark all held locks with a usage bit:
2609 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2611 enum lock_usage_bit usage_bit
;
2612 struct held_lock
*hlock
;
2615 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2616 hlock
= curr
->held_locks
+ i
;
2618 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2620 usage_bit
+= 1; /* READ */
2622 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2627 if (!mark_lock(curr
, hlock
, usage_bit
))
2635 * Hardirqs will be enabled:
2637 static void __trace_hardirqs_on_caller(unsigned long ip
)
2639 struct task_struct
*curr
= current
;
2641 /* we'll do an OFF -> ON transition: */
2642 curr
->hardirqs_enabled
= 1;
2645 * We are going to turn hardirqs on, so set the
2646 * usage bit for all held locks:
2648 if (!mark_held_locks(curr
, HARDIRQ
))
2651 * If we have softirqs enabled, then set the usage
2652 * bit for all held locks. (disabled hardirqs prevented
2653 * this bit from being set before)
2655 if (curr
->softirqs_enabled
)
2656 if (!mark_held_locks(curr
, SOFTIRQ
))
2659 curr
->hardirq_enable_ip
= ip
;
2660 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2661 debug_atomic_inc(hardirqs_on_events
);
2664 __visible
void trace_hardirqs_on_caller(unsigned long ip
)
2666 time_hardirqs_on(CALLER_ADDR0
, ip
);
2668 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2671 if (unlikely(current
->hardirqs_enabled
)) {
2673 * Neither irq nor preemption are disabled here
2674 * so this is racy by nature but losing one hit
2675 * in a stat is not a big deal.
2677 __debug_atomic_inc(redundant_hardirqs_on
);
2682 * We're enabling irqs and according to our state above irqs weren't
2683 * already enabled, yet we find the hardware thinks they are in fact
2684 * enabled.. someone messed up their IRQ state tracing.
2686 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2690 * See the fine text that goes along with this variable definition.
2692 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled
)))
2696 * Can't allow enabling interrupts while in an interrupt handler,
2697 * that's general bad form and such. Recursion, limited stack etc..
2699 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2702 current
->lockdep_recursion
= 1;
2703 __trace_hardirqs_on_caller(ip
);
2704 current
->lockdep_recursion
= 0;
2706 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2708 void trace_hardirqs_on(void)
2710 trace_hardirqs_on_caller(CALLER_ADDR0
);
2712 EXPORT_SYMBOL(trace_hardirqs_on
);
2715 * Hardirqs were disabled:
2717 __visible
void trace_hardirqs_off_caller(unsigned long ip
)
2719 struct task_struct
*curr
= current
;
2721 time_hardirqs_off(CALLER_ADDR0
, ip
);
2723 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2727 * So we're supposed to get called after you mask local IRQs, but for
2728 * some reason the hardware doesn't quite think you did a proper job.
2730 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2733 if (curr
->hardirqs_enabled
) {
2735 * We have done an ON -> OFF transition:
2737 curr
->hardirqs_enabled
= 0;
2738 curr
->hardirq_disable_ip
= ip
;
2739 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2740 debug_atomic_inc(hardirqs_off_events
);
2742 debug_atomic_inc(redundant_hardirqs_off
);
2744 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2746 void trace_hardirqs_off(void)
2748 trace_hardirqs_off_caller(CALLER_ADDR0
);
2750 EXPORT_SYMBOL(trace_hardirqs_off
);
2753 * Softirqs will be enabled:
2755 void trace_softirqs_on(unsigned long ip
)
2757 struct task_struct
*curr
= current
;
2759 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2763 * We fancy IRQs being disabled here, see softirq.c, avoids
2764 * funny state and nesting things.
2766 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2769 if (curr
->softirqs_enabled
) {
2770 debug_atomic_inc(redundant_softirqs_on
);
2774 current
->lockdep_recursion
= 1;
2776 * We'll do an OFF -> ON transition:
2778 curr
->softirqs_enabled
= 1;
2779 curr
->softirq_enable_ip
= ip
;
2780 curr
->softirq_enable_event
= ++curr
->irq_events
;
2781 debug_atomic_inc(softirqs_on_events
);
2783 * We are going to turn softirqs on, so set the
2784 * usage bit for all held locks, if hardirqs are
2787 if (curr
->hardirqs_enabled
)
2788 mark_held_locks(curr
, SOFTIRQ
);
2789 current
->lockdep_recursion
= 0;
2793 * Softirqs were disabled:
2795 void trace_softirqs_off(unsigned long ip
)
2797 struct task_struct
*curr
= current
;
2799 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2803 * We fancy IRQs being disabled here, see softirq.c
2805 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2808 if (curr
->softirqs_enabled
) {
2810 * We have done an ON -> OFF transition:
2812 curr
->softirqs_enabled
= 0;
2813 curr
->softirq_disable_ip
= ip
;
2814 curr
->softirq_disable_event
= ++curr
->irq_events
;
2815 debug_atomic_inc(softirqs_off_events
);
2817 * Whoops, we wanted softirqs off, so why aren't they?
2819 DEBUG_LOCKS_WARN_ON(!softirq_count());
2821 debug_atomic_inc(redundant_softirqs_off
);
2824 static void __lockdep_trace_alloc(gfp_t gfp_mask
, unsigned long flags
)
2826 struct task_struct
*curr
= current
;
2828 if (unlikely(!debug_locks
))
2831 /* no reclaim without waiting on it */
2832 if (!(gfp_mask
& __GFP_DIRECT_RECLAIM
))
2835 /* this guy won't enter reclaim */
2836 if ((curr
->flags
& PF_MEMALLOC
) && !(gfp_mask
& __GFP_NOMEMALLOC
))
2839 /* We're only interested __GFP_FS allocations for now */
2840 if (!(gfp_mask
& __GFP_FS
))
2844 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2846 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags
)))
2849 mark_held_locks(curr
, RECLAIM_FS
);
2852 static void check_flags(unsigned long flags
);
2854 void lockdep_trace_alloc(gfp_t gfp_mask
)
2856 unsigned long flags
;
2858 if (unlikely(current
->lockdep_recursion
))
2861 raw_local_irq_save(flags
);
2863 current
->lockdep_recursion
= 1;
2864 __lockdep_trace_alloc(gfp_mask
, flags
);
2865 current
->lockdep_recursion
= 0;
2866 raw_local_irq_restore(flags
);
2869 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2872 * If non-trylock use in a hardirq or softirq context, then
2873 * mark the lock as used in these contexts:
2875 if (!hlock
->trylock
) {
2877 if (curr
->hardirq_context
)
2878 if (!mark_lock(curr
, hlock
,
2879 LOCK_USED_IN_HARDIRQ_READ
))
2881 if (curr
->softirq_context
)
2882 if (!mark_lock(curr
, hlock
,
2883 LOCK_USED_IN_SOFTIRQ_READ
))
2886 if (curr
->hardirq_context
)
2887 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2889 if (curr
->softirq_context
)
2890 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2894 if (!hlock
->hardirqs_off
) {
2896 if (!mark_lock(curr
, hlock
,
2897 LOCK_ENABLED_HARDIRQ_READ
))
2899 if (curr
->softirqs_enabled
)
2900 if (!mark_lock(curr
, hlock
,
2901 LOCK_ENABLED_SOFTIRQ_READ
))
2904 if (!mark_lock(curr
, hlock
,
2905 LOCK_ENABLED_HARDIRQ
))
2907 if (curr
->softirqs_enabled
)
2908 if (!mark_lock(curr
, hlock
,
2909 LOCK_ENABLED_SOFTIRQ
))
2915 * We reuse the irq context infrastructure more broadly as a general
2916 * context checking code. This tests GFP_FS recursion (a lock taken
2917 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2920 if (!hlock
->trylock
&& (curr
->lockdep_reclaim_gfp
& __GFP_FS
)) {
2922 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS_READ
))
2925 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS
))
2933 static int separate_irq_context(struct task_struct
*curr
,
2934 struct held_lock
*hlock
)
2936 unsigned int depth
= curr
->lockdep_depth
;
2939 * Keep track of points where we cross into an interrupt context:
2941 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2942 curr
->softirq_context
;
2944 struct held_lock
*prev_hlock
;
2946 prev_hlock
= curr
->held_locks
+ depth
-1;
2948 * If we cross into another context, reset the
2949 * hash key (this also prevents the checking and the
2950 * adding of the dependency to 'prev'):
2952 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2958 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2961 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2962 enum lock_usage_bit new_bit
)
2964 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2968 static inline int mark_irqflags(struct task_struct
*curr
,
2969 struct held_lock
*hlock
)
2974 static inline int separate_irq_context(struct task_struct
*curr
,
2975 struct held_lock
*hlock
)
2980 void lockdep_trace_alloc(gfp_t gfp_mask
)
2984 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2987 * Mark a lock with a usage bit, and validate the state transition:
2989 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2990 enum lock_usage_bit new_bit
)
2992 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2995 * If already set then do not dirty the cacheline,
2996 * nor do any checks:
2998 if (likely(hlock_class(this)->usage_mask
& new_mask
))
3004 * Make sure we didn't race:
3006 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
3011 hlock_class(this)->usage_mask
|= new_mask
;
3013 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
3017 #define LOCKDEP_STATE(__STATE) \
3018 case LOCK_USED_IN_##__STATE: \
3019 case LOCK_USED_IN_##__STATE##_READ: \
3020 case LOCK_ENABLED_##__STATE: \
3021 case LOCK_ENABLED_##__STATE##_READ:
3022 #include "lockdep_states.h"
3023 #undef LOCKDEP_STATE
3024 ret
= mark_lock_irq(curr
, this, new_bit
);
3029 debug_atomic_dec(nr_unused_locks
);
3032 if (!debug_locks_off_graph_unlock())
3041 * We must printk outside of the graph_lock:
3044 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
3046 print_irqtrace_events(curr
);
3054 * Initialize a lock instance's lock-class mapping info:
3056 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
3057 struct lock_class_key
*key
, int subclass
)
3061 kmemcheck_mark_initialized(lock
, sizeof(*lock
));
3063 for (i
= 0; i
< NR_LOCKDEP_CACHING_CLASSES
; i
++)
3064 lock
->class_cache
[i
] = NULL
;
3066 #ifdef CONFIG_LOCK_STAT
3067 lock
->cpu
= raw_smp_processor_id();
3071 * Can't be having no nameless bastards around this place!
3073 if (DEBUG_LOCKS_WARN_ON(!name
)) {
3074 lock
->name
= "NULL";
3081 * No key, no joy, we need to hash something.
3083 if (DEBUG_LOCKS_WARN_ON(!key
))
3086 * Sanity check, the lock-class key must be persistent:
3088 if (!static_obj(key
)) {
3089 printk("BUG: key %p not in .data!\n", key
);
3091 * What it says above ^^^^^, I suggest you read it.
3093 DEBUG_LOCKS_WARN_ON(1);
3098 if (unlikely(!debug_locks
))
3102 unsigned long flags
;
3104 if (DEBUG_LOCKS_WARN_ON(current
->lockdep_recursion
))
3107 raw_local_irq_save(flags
);
3108 current
->lockdep_recursion
= 1;
3109 register_lock_class(lock
, subclass
, 1);
3110 current
->lockdep_recursion
= 0;
3111 raw_local_irq_restore(flags
);
3114 EXPORT_SYMBOL_GPL(lockdep_init_map
);
3116 struct lock_class_key __lockdep_no_validate__
;
3117 EXPORT_SYMBOL_GPL(__lockdep_no_validate__
);
3120 print_lock_nested_lock_not_held(struct task_struct
*curr
,
3121 struct held_lock
*hlock
,
3124 if (!debug_locks_off())
3126 if (debug_locks_silent
)
3130 printk("==================================\n");
3131 printk("[ BUG: Nested lock was not taken ]\n");
3132 print_kernel_ident();
3133 printk("----------------------------------\n");
3135 printk("%s/%d is trying to lock:\n", curr
->comm
, task_pid_nr(curr
));
3138 printk("\nbut this task is not holding:\n");
3139 printk("%s\n", hlock
->nest_lock
->name
);
3141 printk("\nstack backtrace:\n");
3144 printk("\nother info that might help us debug this:\n");
3145 lockdep_print_held_locks(curr
);
3147 printk("\nstack backtrace:\n");
3153 static int __lock_is_held(struct lockdep_map
*lock
);
3156 * This gets called for every mutex_lock*()/spin_lock*() operation.
3157 * We maintain the dependency maps and validate the locking attempt:
3159 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3160 int trylock
, int read
, int check
, int hardirqs_off
,
3161 struct lockdep_map
*nest_lock
, unsigned long ip
,
3162 int references
, int pin_count
)
3164 struct task_struct
*curr
= current
;
3165 struct lock_class
*class = NULL
;
3166 struct held_lock
*hlock
;
3172 if (unlikely(!debug_locks
))
3176 * Lockdep should run with IRQs disabled, otherwise we could
3177 * get an interrupt which would want to take locks, which would
3178 * end up in lockdep and have you got a head-ache already?
3180 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3183 if (!prove_locking
|| lock
->key
== &__lockdep_no_validate__
)
3186 if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
3187 class = lock
->class_cache
[subclass
];
3191 if (unlikely(!class)) {
3192 class = register_lock_class(lock
, subclass
, 0);
3196 atomic_inc((atomic_t
*)&class->ops
);
3197 if (very_verbose(class)) {
3198 printk("\nacquire class [%p] %s", class->key
, class->name
);
3199 if (class->name_version
> 1)
3200 printk("#%d", class->name_version
);
3206 * Add the lock to the list of currently held locks.
3207 * (we dont increase the depth just yet, up until the
3208 * dependency checks are done)
3210 depth
= curr
->lockdep_depth
;
3212 * Ran out of static storage for our per-task lock stack again have we?
3214 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
3217 class_idx
= class - lock_classes
+ 1;
3220 hlock
= curr
->held_locks
+ depth
- 1;
3221 if (hlock
->class_idx
== class_idx
&& nest_lock
) {
3222 if (hlock
->references
)
3223 hlock
->references
++;
3225 hlock
->references
= 2;
3231 hlock
= curr
->held_locks
+ depth
;
3233 * Plain impossible, we just registered it and checked it weren't no
3234 * NULL like.. I bet this mushroom I ate was good!
3236 if (DEBUG_LOCKS_WARN_ON(!class))
3238 hlock
->class_idx
= class_idx
;
3239 hlock
->acquire_ip
= ip
;
3240 hlock
->instance
= lock
;
3241 hlock
->nest_lock
= nest_lock
;
3242 hlock
->trylock
= trylock
;
3244 hlock
->check
= check
;
3245 hlock
->hardirqs_off
= !!hardirqs_off
;
3246 hlock
->references
= references
;
3247 #ifdef CONFIG_LOCK_STAT
3248 hlock
->waittime_stamp
= 0;
3249 hlock
->holdtime_stamp
= lockstat_clock();
3251 hlock
->pin_count
= pin_count
;
3253 if (check
&& !mark_irqflags(curr
, hlock
))
3256 /* mark it as used: */
3257 if (!mark_lock(curr
, hlock
, LOCK_USED
))
3261 * Calculate the chain hash: it's the combined hash of all the
3262 * lock keys along the dependency chain. We save the hash value
3263 * at every step so that we can get the current hash easily
3264 * after unlock. The chain hash is then used to cache dependency
3267 * The 'key ID' is what is the most compact key value to drive
3268 * the hash, not class->key.
3271 * Whoops, we did it again.. ran straight out of our static allocation.
3273 if (DEBUG_LOCKS_WARN_ON(class_idx
> MAX_LOCKDEP_KEYS
))
3276 chain_key
= curr
->curr_chain_key
;
3279 * How can we have a chain hash when we ain't got no keys?!
3281 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
3286 hlock
->prev_chain_key
= chain_key
;
3287 if (separate_irq_context(curr
, hlock
)) {
3291 chain_key
= iterate_chain_key(chain_key
, class_idx
);
3293 if (nest_lock
&& !__lock_is_held(nest_lock
))
3294 return print_lock_nested_lock_not_held(curr
, hlock
, ip
);
3296 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
3299 curr
->curr_chain_key
= chain_key
;
3300 curr
->lockdep_depth
++;
3301 check_chain_key(curr
);
3302 #ifdef CONFIG_DEBUG_LOCKDEP
3303 if (unlikely(!debug_locks
))
3306 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
3308 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3309 printk(KERN_DEBUG
"depth: %i max: %lu!\n",
3310 curr
->lockdep_depth
, MAX_LOCK_DEPTH
);
3312 lockdep_print_held_locks(current
);
3313 debug_show_all_locks();
3319 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
3320 max_lockdep_depth
= curr
->lockdep_depth
;
3326 print_unlock_imbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3329 if (!debug_locks_off())
3331 if (debug_locks_silent
)
3335 printk("=====================================\n");
3336 printk("[ BUG: bad unlock balance detected! ]\n");
3337 print_kernel_ident();
3338 printk("-------------------------------------\n");
3339 printk("%s/%d is trying to release lock (",
3340 curr
->comm
, task_pid_nr(curr
));
3341 print_lockdep_cache(lock
);
3344 printk("but there are no more locks to release!\n");
3345 printk("\nother info that might help us debug this:\n");
3346 lockdep_print_held_locks(curr
);
3348 printk("\nstack backtrace:\n");
3354 static int match_held_lock(struct held_lock
*hlock
, struct lockdep_map
*lock
)
3356 if (hlock
->instance
== lock
)
3359 if (hlock
->references
) {
3360 struct lock_class
*class = lock
->class_cache
[0];
3363 class = look_up_lock_class(lock
, 0);
3366 * If look_up_lock_class() failed to find a class, we're trying
3367 * to test if we hold a lock that has never yet been acquired.
3368 * Clearly if the lock hasn't been acquired _ever_, we're not
3369 * holding it either, so report failure.
3375 * References, but not a lock we're actually ref-counting?
3376 * State got messed up, follow the sites that change ->references
3377 * and try to make sense of it.
3379 if (DEBUG_LOCKS_WARN_ON(!hlock
->nest_lock
))
3382 if (hlock
->class_idx
== class - lock_classes
+ 1)
3390 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
3391 struct lock_class_key
*key
, unsigned int subclass
,
3394 struct task_struct
*curr
= current
;
3395 struct held_lock
*hlock
, *prev_hlock
;
3396 struct lock_class
*class;
3400 depth
= curr
->lockdep_depth
;
3402 * This function is about (re)setting the class of a held lock,
3403 * yet we're not actually holding any locks. Naughty user!
3405 if (DEBUG_LOCKS_WARN_ON(!depth
))
3409 for (i
= depth
-1; i
>= 0; i
--) {
3410 hlock
= curr
->held_locks
+ i
;
3412 * We must not cross into another context:
3414 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3416 if (match_held_lock(hlock
, lock
))
3420 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3423 lockdep_init_map(lock
, name
, key
, 0);
3424 class = register_lock_class(lock
, subclass
, 0);
3425 hlock
->class_idx
= class - lock_classes
+ 1;
3427 curr
->lockdep_depth
= i
;
3428 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3430 for (; i
< depth
; i
++) {
3431 hlock
= curr
->held_locks
+ i
;
3432 if (!__lock_acquire(hlock
->instance
,
3433 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3434 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3435 hlock
->nest_lock
, hlock
->acquire_ip
,
3436 hlock
->references
, hlock
->pin_count
))
3441 * I took it apart and put it back together again, except now I have
3442 * these 'spare' parts.. where shall I put them.
3444 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
3450 * Remove the lock to the list of currently held locks - this gets
3451 * called on mutex_unlock()/spin_unlock*() (or on a failed
3452 * mutex_lock_interruptible()).
3454 * @nested is an hysterical artifact, needs a tree wide cleanup.
3457 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
3459 struct task_struct
*curr
= current
;
3460 struct held_lock
*hlock
, *prev_hlock
;
3464 if (unlikely(!debug_locks
))
3467 depth
= curr
->lockdep_depth
;
3469 * So we're all set to release this lock.. wait what lock? We don't
3470 * own any locks, you've been drinking again?
3472 if (DEBUG_LOCKS_WARN_ON(depth
<= 0))
3473 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3476 * Check whether the lock exists in the current stack
3480 for (i
= depth
-1; i
>= 0; i
--) {
3481 hlock
= curr
->held_locks
+ i
;
3483 * We must not cross into another context:
3485 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3487 if (match_held_lock(hlock
, lock
))
3491 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3494 if (hlock
->instance
== lock
)
3495 lock_release_holdtime(hlock
);
3497 WARN(hlock
->pin_count
, "releasing a pinned lock\n");
3499 if (hlock
->references
) {
3500 hlock
->references
--;
3501 if (hlock
->references
) {
3503 * We had, and after removing one, still have
3504 * references, the current lock stack is still
3505 * valid. We're done!
3512 * We have the right lock to unlock, 'hlock' points to it.
3513 * Now we remove it from the stack, and add back the other
3514 * entries (if any), recalculating the hash along the way:
3517 curr
->lockdep_depth
= i
;
3518 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3520 for (i
++; i
< depth
; i
++) {
3521 hlock
= curr
->held_locks
+ i
;
3522 if (!__lock_acquire(hlock
->instance
,
3523 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3524 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3525 hlock
->nest_lock
, hlock
->acquire_ip
,
3526 hlock
->references
, hlock
->pin_count
))
3531 * We had N bottles of beer on the wall, we drank one, but now
3532 * there's not N-1 bottles of beer left on the wall...
3534 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
3540 static int __lock_is_held(struct lockdep_map
*lock
)
3542 struct task_struct
*curr
= current
;
3545 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3546 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3548 if (match_held_lock(hlock
, lock
))
3555 static void __lock_pin_lock(struct lockdep_map
*lock
)
3557 struct task_struct
*curr
= current
;
3560 if (unlikely(!debug_locks
))
3563 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3564 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3566 if (match_held_lock(hlock
, lock
)) {
3572 WARN(1, "pinning an unheld lock\n");
3575 static void __lock_unpin_lock(struct lockdep_map
*lock
)
3577 struct task_struct
*curr
= current
;
3580 if (unlikely(!debug_locks
))
3583 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3584 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3586 if (match_held_lock(hlock
, lock
)) {
3587 if (WARN(!hlock
->pin_count
, "unpinning an unpinned lock\n"))
3595 WARN(1, "unpinning an unheld lock\n");
3599 * Check whether we follow the irq-flags state precisely:
3601 static void check_flags(unsigned long flags
)
3603 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3604 defined(CONFIG_TRACE_IRQFLAGS)
3608 if (irqs_disabled_flags(flags
)) {
3609 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
3610 printk("possible reason: unannotated irqs-off.\n");
3613 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
3614 printk("possible reason: unannotated irqs-on.\n");
3619 * We dont accurately track softirq state in e.g.
3620 * hardirq contexts (such as on 4KSTACKS), so only
3621 * check if not in hardirq contexts:
3623 if (!hardirq_count()) {
3624 if (softirq_count()) {
3625 /* like the above, but with softirqs */
3626 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
3628 /* lick the above, does it taste good? */
3629 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
3634 print_irqtrace_events(current
);
3638 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
3639 struct lock_class_key
*key
, unsigned int subclass
,
3642 unsigned long flags
;
3644 if (unlikely(current
->lockdep_recursion
))
3647 raw_local_irq_save(flags
);
3648 current
->lockdep_recursion
= 1;
3650 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
3651 check_chain_key(current
);
3652 current
->lockdep_recursion
= 0;
3653 raw_local_irq_restore(flags
);
3655 EXPORT_SYMBOL_GPL(lock_set_class
);
3658 * We are not always called with irqs disabled - do that here,
3659 * and also avoid lockdep recursion:
3661 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3662 int trylock
, int read
, int check
,
3663 struct lockdep_map
*nest_lock
, unsigned long ip
)
3665 unsigned long flags
;
3667 if (unlikely(current
->lockdep_recursion
))
3670 raw_local_irq_save(flags
);
3673 current
->lockdep_recursion
= 1;
3674 trace_lock_acquire(lock
, subclass
, trylock
, read
, check
, nest_lock
, ip
);
3675 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
3676 irqs_disabled_flags(flags
), nest_lock
, ip
, 0, 0);
3677 current
->lockdep_recursion
= 0;
3678 raw_local_irq_restore(flags
);
3680 EXPORT_SYMBOL_GPL(lock_acquire
);
3682 void lock_release(struct lockdep_map
*lock
, int nested
,
3685 unsigned long flags
;
3687 if (unlikely(current
->lockdep_recursion
))
3690 raw_local_irq_save(flags
);
3692 current
->lockdep_recursion
= 1;
3693 trace_lock_release(lock
, ip
);
3694 if (__lock_release(lock
, nested
, ip
))
3695 check_chain_key(current
);
3696 current
->lockdep_recursion
= 0;
3697 raw_local_irq_restore(flags
);
3699 EXPORT_SYMBOL_GPL(lock_release
);
3701 int lock_is_held(struct lockdep_map
*lock
)
3703 unsigned long flags
;
3706 if (unlikely(current
->lockdep_recursion
))
3707 return 1; /* avoid false negative lockdep_assert_held() */
3709 raw_local_irq_save(flags
);
3712 current
->lockdep_recursion
= 1;
3713 ret
= __lock_is_held(lock
);
3714 current
->lockdep_recursion
= 0;
3715 raw_local_irq_restore(flags
);
3719 EXPORT_SYMBOL_GPL(lock_is_held
);
3721 void lock_pin_lock(struct lockdep_map
*lock
)
3723 unsigned long flags
;
3725 if (unlikely(current
->lockdep_recursion
))
3728 raw_local_irq_save(flags
);
3731 current
->lockdep_recursion
= 1;
3732 __lock_pin_lock(lock
);
3733 current
->lockdep_recursion
= 0;
3734 raw_local_irq_restore(flags
);
3736 EXPORT_SYMBOL_GPL(lock_pin_lock
);
3738 void lock_unpin_lock(struct lockdep_map
*lock
)
3740 unsigned long flags
;
3742 if (unlikely(current
->lockdep_recursion
))
3745 raw_local_irq_save(flags
);
3748 current
->lockdep_recursion
= 1;
3749 __lock_unpin_lock(lock
);
3750 current
->lockdep_recursion
= 0;
3751 raw_local_irq_restore(flags
);
3753 EXPORT_SYMBOL_GPL(lock_unpin_lock
);
3755 void lockdep_set_current_reclaim_state(gfp_t gfp_mask
)
3757 current
->lockdep_reclaim_gfp
= gfp_mask
;
3760 void lockdep_clear_current_reclaim_state(void)
3762 current
->lockdep_reclaim_gfp
= 0;
3765 #ifdef CONFIG_LOCK_STAT
3767 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3770 if (!debug_locks_off())
3772 if (debug_locks_silent
)
3776 printk("=================================\n");
3777 printk("[ BUG: bad contention detected! ]\n");
3778 print_kernel_ident();
3779 printk("---------------------------------\n");
3780 printk("%s/%d is trying to contend lock (",
3781 curr
->comm
, task_pid_nr(curr
));
3782 print_lockdep_cache(lock
);
3785 printk("but there are no locks held!\n");
3786 printk("\nother info that might help us debug this:\n");
3787 lockdep_print_held_locks(curr
);
3789 printk("\nstack backtrace:\n");
3796 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3798 struct task_struct
*curr
= current
;
3799 struct held_lock
*hlock
, *prev_hlock
;
3800 struct lock_class_stats
*stats
;
3802 int i
, contention_point
, contending_point
;
3804 depth
= curr
->lockdep_depth
;
3806 * Whee, we contended on this lock, except it seems we're not
3807 * actually trying to acquire anything much at all..
3809 if (DEBUG_LOCKS_WARN_ON(!depth
))
3813 for (i
= depth
-1; i
>= 0; i
--) {
3814 hlock
= curr
->held_locks
+ i
;
3816 * We must not cross into another context:
3818 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3820 if (match_held_lock(hlock
, lock
))
3824 print_lock_contention_bug(curr
, lock
, ip
);
3828 if (hlock
->instance
!= lock
)
3831 hlock
->waittime_stamp
= lockstat_clock();
3833 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3834 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3837 stats
= get_lock_stats(hlock_class(hlock
));
3838 if (contention_point
< LOCKSTAT_POINTS
)
3839 stats
->contention_point
[contention_point
]++;
3840 if (contending_point
< LOCKSTAT_POINTS
)
3841 stats
->contending_point
[contending_point
]++;
3842 if (lock
->cpu
!= smp_processor_id())
3843 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3844 put_lock_stats(stats
);
3848 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3850 struct task_struct
*curr
= current
;
3851 struct held_lock
*hlock
, *prev_hlock
;
3852 struct lock_class_stats
*stats
;
3854 u64 now
, waittime
= 0;
3857 depth
= curr
->lockdep_depth
;
3859 * Yay, we acquired ownership of this lock we didn't try to
3860 * acquire, how the heck did that happen?
3862 if (DEBUG_LOCKS_WARN_ON(!depth
))
3866 for (i
= depth
-1; i
>= 0; i
--) {
3867 hlock
= curr
->held_locks
+ i
;
3869 * We must not cross into another context:
3871 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3873 if (match_held_lock(hlock
, lock
))
3877 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3881 if (hlock
->instance
!= lock
)
3884 cpu
= smp_processor_id();
3885 if (hlock
->waittime_stamp
) {
3886 now
= lockstat_clock();
3887 waittime
= now
- hlock
->waittime_stamp
;
3888 hlock
->holdtime_stamp
= now
;
3891 trace_lock_acquired(lock
, ip
);
3893 stats
= get_lock_stats(hlock_class(hlock
));
3896 lock_time_inc(&stats
->read_waittime
, waittime
);
3898 lock_time_inc(&stats
->write_waittime
, waittime
);
3900 if (lock
->cpu
!= cpu
)
3901 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3902 put_lock_stats(stats
);
3908 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3910 unsigned long flags
;
3912 if (unlikely(!lock_stat
))
3915 if (unlikely(current
->lockdep_recursion
))
3918 raw_local_irq_save(flags
);
3920 current
->lockdep_recursion
= 1;
3921 trace_lock_contended(lock
, ip
);
3922 __lock_contended(lock
, ip
);
3923 current
->lockdep_recursion
= 0;
3924 raw_local_irq_restore(flags
);
3926 EXPORT_SYMBOL_GPL(lock_contended
);
3928 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3930 unsigned long flags
;
3932 if (unlikely(!lock_stat
))
3935 if (unlikely(current
->lockdep_recursion
))
3938 raw_local_irq_save(flags
);
3940 current
->lockdep_recursion
= 1;
3941 __lock_acquired(lock
, ip
);
3942 current
->lockdep_recursion
= 0;
3943 raw_local_irq_restore(flags
);
3945 EXPORT_SYMBOL_GPL(lock_acquired
);
3949 * Used by the testsuite, sanitize the validator state
3950 * after a simulated failure:
3953 void lockdep_reset(void)
3955 unsigned long flags
;
3958 raw_local_irq_save(flags
);
3959 current
->curr_chain_key
= 0;
3960 current
->lockdep_depth
= 0;
3961 current
->lockdep_recursion
= 0;
3962 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3963 nr_hardirq_chains
= 0;
3964 nr_softirq_chains
= 0;
3965 nr_process_chains
= 0;
3967 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3968 INIT_HLIST_HEAD(chainhash_table
+ i
);
3969 raw_local_irq_restore(flags
);
3972 static void zap_class(struct lock_class
*class)
3977 * Remove all dependencies this lock is
3980 for (i
= 0; i
< nr_list_entries
; i
++) {
3981 if (list_entries
[i
].class == class)
3982 list_del_rcu(&list_entries
[i
].entry
);
3985 * Unhash the class and remove it from the all_lock_classes list:
3987 hlist_del_rcu(&class->hash_entry
);
3988 list_del_rcu(&class->lock_entry
);
3990 RCU_INIT_POINTER(class->key
, NULL
);
3991 RCU_INIT_POINTER(class->name
, NULL
);
3994 static inline int within(const void *addr
, void *start
, unsigned long size
)
3996 return addr
>= start
&& addr
< start
+ size
;
4000 * Used in module.c to remove lock classes from memory that is going to be
4001 * freed; and possibly re-used by other modules.
4003 * We will have had one sync_sched() before getting here, so we're guaranteed
4004 * nobody will look up these exact classes -- they're properly dead but still
4007 void lockdep_free_key_range(void *start
, unsigned long size
)
4009 struct lock_class
*class;
4010 struct hlist_head
*head
;
4011 unsigned long flags
;
4015 raw_local_irq_save(flags
);
4016 locked
= graph_lock();
4019 * Unhash all classes that were created by this module:
4021 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
4022 head
= classhash_table
+ i
;
4023 hlist_for_each_entry_rcu(class, head
, hash_entry
) {
4024 if (within(class->key
, start
, size
))
4026 else if (within(class->name
, start
, size
))
4033 raw_local_irq_restore(flags
);
4036 * Wait for any possible iterators from look_up_lock_class() to pass
4037 * before continuing to free the memory they refer to.
4039 * sync_sched() is sufficient because the read-side is IRQ disable.
4041 synchronize_sched();
4044 * XXX at this point we could return the resources to the pool;
4045 * instead we leak them. We would need to change to bitmap allocators
4046 * instead of the linear allocators we have now.
4050 void lockdep_reset_lock(struct lockdep_map
*lock
)
4052 struct lock_class
*class;
4053 struct hlist_head
*head
;
4054 unsigned long flags
;
4058 raw_local_irq_save(flags
);
4061 * Remove all classes this lock might have:
4063 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
4065 * If the class exists we look it up and zap it:
4067 class = look_up_lock_class(lock
, j
);
4072 * Debug check: in the end all mapped classes should
4075 locked
= graph_lock();
4076 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
4077 head
= classhash_table
+ i
;
4078 hlist_for_each_entry_rcu(class, head
, hash_entry
) {
4081 for (j
= 0; j
< NR_LOCKDEP_CACHING_CLASSES
; j
++)
4082 match
|= class == lock
->class_cache
[j
];
4084 if (unlikely(match
)) {
4085 if (debug_locks_off_graph_unlock()) {
4087 * We all just reset everything, how did it match?
4099 raw_local_irq_restore(flags
);
4102 void __init
lockdep_info(void)
4104 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4106 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
4107 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
4108 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
4109 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
4110 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
4111 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
4112 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
4114 printk(" memory used by lock dependency info: %lu kB\n",
4115 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
4116 sizeof(struct list_head
) * CLASSHASH_SIZE
+
4117 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
4118 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
4119 sizeof(struct list_head
) * CHAINHASH_SIZE
4120 #ifdef CONFIG_PROVE_LOCKING
4121 + sizeof(struct circular_queue
)
4126 printk(" per task-struct memory footprint: %lu bytes\n",
4127 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
4131 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
4132 const void *mem_to
, struct held_lock
*hlock
)
4134 if (!debug_locks_off())
4136 if (debug_locks_silent
)
4140 printk("=========================\n");
4141 printk("[ BUG: held lock freed! ]\n");
4142 print_kernel_ident();
4143 printk("-------------------------\n");
4144 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4145 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
4147 lockdep_print_held_locks(curr
);
4149 printk("\nstack backtrace:\n");
4153 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
4154 const void* lock_from
, unsigned long lock_len
)
4156 return lock_from
+ lock_len
<= mem_from
||
4157 mem_from
+ mem_len
<= lock_from
;
4161 * Called when kernel memory is freed (or unmapped), or if a lock
4162 * is destroyed or reinitialized - this code checks whether there is
4163 * any held lock in the memory range of <from> to <to>:
4165 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
4167 struct task_struct
*curr
= current
;
4168 struct held_lock
*hlock
;
4169 unsigned long flags
;
4172 if (unlikely(!debug_locks
))
4175 local_irq_save(flags
);
4176 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
4177 hlock
= curr
->held_locks
+ i
;
4179 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
4180 sizeof(*hlock
->instance
)))
4183 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
4186 local_irq_restore(flags
);
4188 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
4190 static void print_held_locks_bug(void)
4192 if (!debug_locks_off())
4194 if (debug_locks_silent
)
4198 printk("=====================================\n");
4199 printk("[ BUG: %s/%d still has locks held! ]\n",
4200 current
->comm
, task_pid_nr(current
));
4201 print_kernel_ident();
4202 printk("-------------------------------------\n");
4203 lockdep_print_held_locks(current
);
4204 printk("\nstack backtrace:\n");
4208 void debug_check_no_locks_held(void)
4210 if (unlikely(current
->lockdep_depth
> 0))
4211 print_held_locks_bug();
4213 EXPORT_SYMBOL_GPL(debug_check_no_locks_held
);
4216 void debug_show_all_locks(void)
4218 struct task_struct
*g
, *p
;
4222 if (unlikely(!debug_locks
)) {
4223 printk("INFO: lockdep is turned off.\n");
4226 printk("\nShowing all locks held in the system:\n");
4229 * Here we try to get the tasklist_lock as hard as possible,
4230 * if not successful after 2 seconds we ignore it (but keep
4231 * trying). This is to enable a debug printout even if a
4232 * tasklist_lock-holding task deadlocks or crashes.
4235 if (!read_trylock(&tasklist_lock
)) {
4237 printk("hm, tasklist_lock locked, retrying... ");
4240 printk(" #%d", 10-count
);
4244 printk(" ignoring it.\n");
4248 printk(KERN_CONT
" locked it.\n");
4251 do_each_thread(g
, p
) {
4253 * It's not reliable to print a task's held locks
4254 * if it's not sleeping (or if it's not the current
4257 if (p
->state
== TASK_RUNNING
&& p
!= current
)
4259 if (p
->lockdep_depth
)
4260 lockdep_print_held_locks(p
);
4262 if (read_trylock(&tasklist_lock
))
4264 } while_each_thread(g
, p
);
4267 printk("=============================================\n\n");
4270 read_unlock(&tasklist_lock
);
4272 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
4276 * Careful: only use this function if you are sure that
4277 * the task cannot run in parallel!
4279 void debug_show_held_locks(struct task_struct
*task
)
4281 if (unlikely(!debug_locks
)) {
4282 printk("INFO: lockdep is turned off.\n");
4285 lockdep_print_held_locks(task
);
4287 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
4289 asmlinkage __visible
void lockdep_sys_exit(void)
4291 struct task_struct
*curr
= current
;
4293 if (unlikely(curr
->lockdep_depth
)) {
4294 if (!debug_locks_off())
4297 printk("================================================\n");
4298 printk("[ BUG: lock held when returning to user space! ]\n");
4299 print_kernel_ident();
4300 printk("------------------------------------------------\n");
4301 printk("%s/%d is leaving the kernel with locks still held!\n",
4302 curr
->comm
, curr
->pid
);
4303 lockdep_print_held_locks(curr
);
4307 void lockdep_rcu_suspicious(const char *file
, const int line
, const char *s
)
4309 struct task_struct
*curr
= current
;
4311 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4312 if (!debug_locks_off())
4314 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4315 /* Note: the following can be executed concurrently, so be careful. */
4317 printk("===============================\n");
4318 printk("[ INFO: suspicious RCU usage. ]\n");
4319 print_kernel_ident();
4320 printk("-------------------------------\n");
4321 printk("%s:%d %s!\n", file
, line
, s
);
4322 printk("\nother info that might help us debug this:\n\n");
4323 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4324 !rcu_lockdep_current_cpu_online()
4325 ? "RCU used illegally from offline CPU!\n"
4326 : !rcu_is_watching()
4327 ? "RCU used illegally from idle CPU!\n"
4329 rcu_scheduler_active
, debug_locks
);
4332 * If a CPU is in the RCU-free window in idle (ie: in the section
4333 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4334 * considers that CPU to be in an "extended quiescent state",
4335 * which means that RCU will be completely ignoring that CPU.
4336 * Therefore, rcu_read_lock() and friends have absolutely no
4337 * effect on a CPU running in that state. In other words, even if
4338 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4339 * delete data structures out from under it. RCU really has no
4340 * choice here: we need to keep an RCU-free window in idle where
4341 * the CPU may possibly enter into low power mode. This way we can
4342 * notice an extended quiescent state to other CPUs that started a grace
4343 * period. Otherwise we would delay any grace period as long as we run
4346 * So complain bitterly if someone does call rcu_read_lock(),
4347 * rcu_read_lock_bh() and so on from extended quiescent states.
4349 if (!rcu_is_watching())
4350 printk("RCU used illegally from extended quiescent state!\n");
4352 lockdep_print_held_locks(curr
);
4353 printk("\nstack backtrace:\n");
4356 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious
);