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
)
2002 #ifdef CONFIG_DEBUG_LOCKDEP
2004 * Returns the next chain_key iteration
2006 static u64
print_chain_key_iteration(int class_idx
, u64 chain_key
)
2008 u64 new_chain_key
= iterate_chain_key(chain_key
, class_idx
);
2010 printk(" class_idx:%d -> chain_key:%016Lx",
2012 (unsigned long long)new_chain_key
);
2013 return new_chain_key
;
2017 print_chain_keys_held_locks(struct task_struct
*curr
, struct held_lock
*hlock_next
)
2019 struct held_lock
*hlock
;
2021 int depth
= curr
->lockdep_depth
;
2024 printk("depth: %u\n", depth
+ 1);
2025 for (i
= get_first_held_lock(curr
, hlock_next
); i
< depth
; i
++) {
2026 hlock
= curr
->held_locks
+ i
;
2027 chain_key
= print_chain_key_iteration(hlock
->class_idx
, chain_key
);
2032 print_chain_key_iteration(hlock_next
->class_idx
, chain_key
);
2033 print_lock(hlock_next
);
2036 static void print_chain_keys_chain(struct lock_chain
*chain
)
2042 printk("depth: %u\n", chain
->depth
);
2043 for (i
= 0; i
< chain
->depth
; i
++) {
2044 class_id
= chain_hlocks
[chain
->base
+ i
];
2045 chain_key
= print_chain_key_iteration(class_id
+ 1, chain_key
);
2047 print_lock_name(lock_classes
+ class_id
);
2052 static void print_collision(struct task_struct
*curr
,
2053 struct held_lock
*hlock_next
,
2054 struct lock_chain
*chain
)
2057 printk("======================\n");
2058 printk("[chain_key collision ]\n");
2059 print_kernel_ident();
2060 printk("----------------------\n");
2061 printk("%s/%d: ", current
->comm
, task_pid_nr(current
));
2062 printk("Hash chain already cached but the contents don't match!\n");
2064 printk("Held locks:");
2065 print_chain_keys_held_locks(curr
, hlock_next
);
2067 printk("Locks in cached chain:");
2068 print_chain_keys_chain(chain
);
2070 printk("\nstack backtrace:\n");
2076 * Checks whether the chain and the current held locks are consistent
2077 * in depth and also in content. If they are not it most likely means
2078 * that there was a collision during the calculation of the chain_key.
2079 * Returns: 0 not passed, 1 passed
2081 static int check_no_collision(struct task_struct
*curr
,
2082 struct held_lock
*hlock
,
2083 struct lock_chain
*chain
)
2085 #ifdef CONFIG_DEBUG_LOCKDEP
2088 i
= get_first_held_lock(curr
, hlock
);
2090 if (DEBUG_LOCKS_WARN_ON(chain
->depth
!= curr
->lockdep_depth
- (i
- 1))) {
2091 print_collision(curr
, hlock
, chain
);
2095 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2096 id
= curr
->held_locks
[i
].class_idx
- 1;
2098 if (DEBUG_LOCKS_WARN_ON(chain_hlocks
[chain
->base
+ j
] != id
)) {
2099 print_collision(curr
, hlock
, chain
);
2108 * Look up a dependency chain. If the key is not present yet then
2109 * add it and return 1 - in this case the new dependency chain is
2110 * validated. If the key is already hashed, return 0.
2111 * (On return with 1 graph_lock is held.)
2113 static inline int lookup_chain_cache(struct task_struct
*curr
,
2114 struct held_lock
*hlock
,
2117 struct lock_class
*class = hlock_class(hlock
);
2118 struct hlist_head
*hash_head
= chainhashentry(chain_key
);
2119 struct lock_chain
*chain
;
2123 * We might need to take the graph lock, ensure we've got IRQs
2124 * disabled to make this an IRQ-safe lock.. for recursion reasons
2125 * lockdep won't complain about its own locking errors.
2127 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2130 * We can walk it lock-free, because entries only get added
2133 hlist_for_each_entry_rcu(chain
, hash_head
, entry
) {
2134 if (chain
->chain_key
== chain_key
) {
2136 debug_atomic_inc(chain_lookup_hits
);
2137 if (!check_no_collision(curr
, hlock
, chain
))
2140 if (very_verbose(class))
2141 printk("\nhash chain already cached, key: "
2142 "%016Lx tail class: [%p] %s\n",
2143 (unsigned long long)chain_key
,
2144 class->key
, class->name
);
2148 if (very_verbose(class))
2149 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2150 (unsigned long long)chain_key
, class->key
, class->name
);
2152 * Allocate a new chain entry from the static array, and add
2158 * We have to walk the chain again locked - to avoid duplicates:
2160 hlist_for_each_entry(chain
, hash_head
, entry
) {
2161 if (chain
->chain_key
== chain_key
) {
2166 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
2167 if (!debug_locks_off_graph_unlock())
2170 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2174 chain
= lock_chains
+ nr_lock_chains
++;
2175 chain
->chain_key
= chain_key
;
2176 chain
->irq_context
= hlock
->irq_context
;
2177 i
= get_first_held_lock(curr
, hlock
);
2178 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
2179 if (likely(nr_chain_hlocks
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2180 chain
->base
= nr_chain_hlocks
;
2181 nr_chain_hlocks
+= chain
->depth
;
2182 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2183 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
2184 chain_hlocks
[chain
->base
+ j
] = lock_id
;
2186 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
2188 hlist_add_head_rcu(&chain
->entry
, hash_head
);
2189 debug_atomic_inc(chain_lookup_misses
);
2195 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
2196 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
2199 * Trylock needs to maintain the stack of held locks, but it
2200 * does not add new dependencies, because trylock can be done
2203 * We look up the chain_key and do the O(N^2) check and update of
2204 * the dependencies only if this is a new dependency chain.
2205 * (If lookup_chain_cache() returns with 1 it acquires
2206 * graph_lock for us)
2208 if (!hlock
->trylock
&& hlock
->check
&&
2209 lookup_chain_cache(curr
, hlock
, chain_key
)) {
2211 * Check whether last held lock:
2213 * - is irq-safe, if this lock is irq-unsafe
2214 * - is softirq-safe, if this lock is hardirq-unsafe
2216 * And check whether the new lock's dependency graph
2217 * could lead back to the previous lock.
2219 * any of these scenarios could lead to a deadlock. If
2222 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
2227 * Mark recursive read, as we jump over it when
2228 * building dependencies (just like we jump over
2234 * Add dependency only if this lock is not the head
2235 * of the chain, and if it's not a secondary read-lock:
2237 if (!chain_head
&& ret
!= 2)
2238 if (!check_prevs_add(curr
, hlock
))
2242 /* after lookup_chain_cache(): */
2243 if (unlikely(!debug_locks
))
2249 static inline int validate_chain(struct task_struct
*curr
,
2250 struct lockdep_map
*lock
, struct held_lock
*hlock
,
2251 int chain_head
, u64 chain_key
)
2258 * We are building curr_chain_key incrementally, so double-check
2259 * it from scratch, to make sure that it's done correctly:
2261 static void check_chain_key(struct task_struct
*curr
)
2263 #ifdef CONFIG_DEBUG_LOCKDEP
2264 struct held_lock
*hlock
, *prev_hlock
= NULL
;
2268 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2269 hlock
= curr
->held_locks
+ i
;
2270 if (chain_key
!= hlock
->prev_chain_key
) {
2273 * We got mighty confused, our chain keys don't match
2274 * with what we expect, someone trample on our task state?
2276 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2277 curr
->lockdep_depth
, i
,
2278 (unsigned long long)chain_key
,
2279 (unsigned long long)hlock
->prev_chain_key
);
2283 * Whoops ran out of static storage again?
2285 if (DEBUG_LOCKS_WARN_ON(hlock
->class_idx
> MAX_LOCKDEP_KEYS
))
2288 if (prev_hlock
&& (prev_hlock
->irq_context
!=
2289 hlock
->irq_context
))
2291 chain_key
= iterate_chain_key(chain_key
, hlock
->class_idx
);
2294 if (chain_key
!= curr
->curr_chain_key
) {
2297 * More smoking hash instead of calculating it, damn see these
2298 * numbers float.. I bet that a pink elephant stepped on my memory.
2300 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2301 curr
->lockdep_depth
, i
,
2302 (unsigned long long)chain_key
,
2303 (unsigned long long)curr
->curr_chain_key
);
2309 print_usage_bug_scenario(struct held_lock
*lock
)
2311 struct lock_class
*class = hlock_class(lock
);
2313 printk(" Possible unsafe locking scenario:\n\n");
2317 __print_lock_name(class);
2319 printk(" <Interrupt>\n");
2321 __print_lock_name(class);
2323 printk("\n *** DEADLOCK ***\n\n");
2327 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
2328 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
2330 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2334 printk("=================================\n");
2335 printk("[ INFO: inconsistent lock state ]\n");
2336 print_kernel_ident();
2337 printk("---------------------------------\n");
2339 printk("inconsistent {%s} -> {%s} usage.\n",
2340 usage_str
[prev_bit
], usage_str
[new_bit
]);
2342 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2343 curr
->comm
, task_pid_nr(curr
),
2344 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
2345 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
2346 trace_hardirqs_enabled(curr
),
2347 trace_softirqs_enabled(curr
));
2350 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
2351 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
2353 print_irqtrace_events(curr
);
2354 printk("\nother info that might help us debug this:\n");
2355 print_usage_bug_scenario(this);
2357 lockdep_print_held_locks(curr
);
2359 printk("\nstack backtrace:\n");
2366 * Print out an error if an invalid bit is set:
2369 valid_state(struct task_struct
*curr
, struct held_lock
*this,
2370 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
2372 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
2373 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
2377 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2378 enum lock_usage_bit new_bit
);
2380 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2383 * print irq inversion bug:
2386 print_irq_inversion_bug(struct task_struct
*curr
,
2387 struct lock_list
*root
, struct lock_list
*other
,
2388 struct held_lock
*this, int forwards
,
2389 const char *irqclass
)
2391 struct lock_list
*entry
= other
;
2392 struct lock_list
*middle
= NULL
;
2395 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2399 printk("=========================================================\n");
2400 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2401 print_kernel_ident();
2402 printk("---------------------------------------------------------\n");
2403 printk("%s/%d just changed the state of lock:\n",
2404 curr
->comm
, task_pid_nr(curr
));
2407 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass
);
2409 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass
);
2410 print_lock_name(other
->class);
2411 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2413 printk("\nother info that might help us debug this:\n");
2415 /* Find a middle lock (if one exists) */
2416 depth
= get_lock_depth(other
);
2418 if (depth
== 0 && (entry
!= root
)) {
2419 printk("lockdep:%s bad path found in chain graph\n", __func__
);
2423 entry
= get_lock_parent(entry
);
2425 } while (entry
&& entry
!= root
&& (depth
>= 0));
2427 print_irq_lock_scenario(root
, other
,
2428 middle
? middle
->class : root
->class, other
->class);
2430 print_irq_lock_scenario(other
, root
,
2431 middle
? middle
->class : other
->class, root
->class);
2433 lockdep_print_held_locks(curr
);
2435 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2436 if (!save_trace(&root
->trace
))
2438 print_shortest_lock_dependencies(other
, root
);
2440 printk("\nstack backtrace:\n");
2447 * Prove that in the forwards-direction subgraph starting at <this>
2448 * there is no lock matching <mask>:
2451 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
2452 enum lock_usage_bit bit
, const char *irqclass
)
2455 struct lock_list root
;
2456 struct lock_list
*uninitialized_var(target_entry
);
2459 root
.class = hlock_class(this);
2460 ret
= find_usage_forwards(&root
, bit
, &target_entry
);
2462 return print_bfs_bug(ret
);
2466 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2471 * Prove that in the backwards-direction subgraph starting at <this>
2472 * there is no lock matching <mask>:
2475 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
2476 enum lock_usage_bit bit
, const char *irqclass
)
2479 struct lock_list root
;
2480 struct lock_list
*uninitialized_var(target_entry
);
2483 root
.class = hlock_class(this);
2484 ret
= find_usage_backwards(&root
, bit
, &target_entry
);
2486 return print_bfs_bug(ret
);
2490 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2494 void print_irqtrace_events(struct task_struct
*curr
)
2496 printk("irq event stamp: %u\n", curr
->irq_events
);
2497 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
2498 print_ip_sym(curr
->hardirq_enable_ip
);
2499 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
2500 print_ip_sym(curr
->hardirq_disable_ip
);
2501 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
2502 print_ip_sym(curr
->softirq_enable_ip
);
2503 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
2504 print_ip_sym(curr
->softirq_disable_ip
);
2507 static int HARDIRQ_verbose(struct lock_class
*class)
2510 return class_filter(class);
2515 static int SOFTIRQ_verbose(struct lock_class
*class)
2518 return class_filter(class);
2523 static int RECLAIM_FS_verbose(struct lock_class
*class)
2526 return class_filter(class);
2531 #define STRICT_READ_CHECKS 1
2533 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2534 #define LOCKDEP_STATE(__STATE) \
2536 #include "lockdep_states.h"
2537 #undef LOCKDEP_STATE
2540 static inline int state_verbose(enum lock_usage_bit bit
,
2541 struct lock_class
*class)
2543 return state_verbose_f
[bit
>> 2](class);
2546 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2547 enum lock_usage_bit bit
, const char *name
);
2550 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2551 enum lock_usage_bit new_bit
)
2553 int excl_bit
= exclusive_bit(new_bit
);
2554 int read
= new_bit
& 1;
2555 int dir
= new_bit
& 2;
2558 * mark USED_IN has to look forwards -- to ensure no dependency
2559 * has ENABLED state, which would allow recursion deadlocks.
2561 * mark ENABLED has to look backwards -- to ensure no dependee
2562 * has USED_IN state, which, again, would allow recursion deadlocks.
2564 check_usage_f usage
= dir
?
2565 check_usage_backwards
: check_usage_forwards
;
2568 * Validate that this particular lock does not have conflicting
2571 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2575 * Validate that the lock dependencies don't have conflicting usage
2578 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2579 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2583 * Check for read in write conflicts
2586 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2589 if (STRICT_READ_CHECKS
&&
2590 !usage(curr
, this, excl_bit
+ 1,
2591 state_name(new_bit
+ 1)))
2595 if (state_verbose(new_bit
, hlock_class(this)))
2602 #define LOCKDEP_STATE(__STATE) __STATE,
2603 #include "lockdep_states.h"
2604 #undef LOCKDEP_STATE
2608 * Mark all held locks with a usage bit:
2611 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2613 enum lock_usage_bit usage_bit
;
2614 struct held_lock
*hlock
;
2617 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2618 hlock
= curr
->held_locks
+ i
;
2620 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2622 usage_bit
+= 1; /* READ */
2624 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2629 if (!mark_lock(curr
, hlock
, usage_bit
))
2637 * Hardirqs will be enabled:
2639 static void __trace_hardirqs_on_caller(unsigned long ip
)
2641 struct task_struct
*curr
= current
;
2643 /* we'll do an OFF -> ON transition: */
2644 curr
->hardirqs_enabled
= 1;
2647 * We are going to turn hardirqs on, so set the
2648 * usage bit for all held locks:
2650 if (!mark_held_locks(curr
, HARDIRQ
))
2653 * If we have softirqs enabled, then set the usage
2654 * bit for all held locks. (disabled hardirqs prevented
2655 * this bit from being set before)
2657 if (curr
->softirqs_enabled
)
2658 if (!mark_held_locks(curr
, SOFTIRQ
))
2661 curr
->hardirq_enable_ip
= ip
;
2662 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2663 debug_atomic_inc(hardirqs_on_events
);
2666 __visible
void trace_hardirqs_on_caller(unsigned long ip
)
2668 time_hardirqs_on(CALLER_ADDR0
, ip
);
2670 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2673 if (unlikely(current
->hardirqs_enabled
)) {
2675 * Neither irq nor preemption are disabled here
2676 * so this is racy by nature but losing one hit
2677 * in a stat is not a big deal.
2679 __debug_atomic_inc(redundant_hardirqs_on
);
2684 * We're enabling irqs and according to our state above irqs weren't
2685 * already enabled, yet we find the hardware thinks they are in fact
2686 * enabled.. someone messed up their IRQ state tracing.
2688 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2692 * See the fine text that goes along with this variable definition.
2694 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled
)))
2698 * Can't allow enabling interrupts while in an interrupt handler,
2699 * that's general bad form and such. Recursion, limited stack etc..
2701 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2704 current
->lockdep_recursion
= 1;
2705 __trace_hardirqs_on_caller(ip
);
2706 current
->lockdep_recursion
= 0;
2708 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2710 void trace_hardirqs_on(void)
2712 trace_hardirqs_on_caller(CALLER_ADDR0
);
2714 EXPORT_SYMBOL(trace_hardirqs_on
);
2717 * Hardirqs were disabled:
2719 __visible
void trace_hardirqs_off_caller(unsigned long ip
)
2721 struct task_struct
*curr
= current
;
2723 time_hardirqs_off(CALLER_ADDR0
, ip
);
2725 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2729 * So we're supposed to get called after you mask local IRQs, but for
2730 * some reason the hardware doesn't quite think you did a proper job.
2732 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2735 if (curr
->hardirqs_enabled
) {
2737 * We have done an ON -> OFF transition:
2739 curr
->hardirqs_enabled
= 0;
2740 curr
->hardirq_disable_ip
= ip
;
2741 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2742 debug_atomic_inc(hardirqs_off_events
);
2744 debug_atomic_inc(redundant_hardirqs_off
);
2746 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2748 void trace_hardirqs_off(void)
2750 trace_hardirqs_off_caller(CALLER_ADDR0
);
2752 EXPORT_SYMBOL(trace_hardirqs_off
);
2755 * Softirqs will be enabled:
2757 void trace_softirqs_on(unsigned long ip
)
2759 struct task_struct
*curr
= current
;
2761 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2765 * We fancy IRQs being disabled here, see softirq.c, avoids
2766 * funny state and nesting things.
2768 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2771 if (curr
->softirqs_enabled
) {
2772 debug_atomic_inc(redundant_softirqs_on
);
2776 current
->lockdep_recursion
= 1;
2778 * We'll do an OFF -> ON transition:
2780 curr
->softirqs_enabled
= 1;
2781 curr
->softirq_enable_ip
= ip
;
2782 curr
->softirq_enable_event
= ++curr
->irq_events
;
2783 debug_atomic_inc(softirqs_on_events
);
2785 * We are going to turn softirqs on, so set the
2786 * usage bit for all held locks, if hardirqs are
2789 if (curr
->hardirqs_enabled
)
2790 mark_held_locks(curr
, SOFTIRQ
);
2791 current
->lockdep_recursion
= 0;
2795 * Softirqs were disabled:
2797 void trace_softirqs_off(unsigned long ip
)
2799 struct task_struct
*curr
= current
;
2801 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2805 * We fancy IRQs being disabled here, see softirq.c
2807 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2810 if (curr
->softirqs_enabled
) {
2812 * We have done an ON -> OFF transition:
2814 curr
->softirqs_enabled
= 0;
2815 curr
->softirq_disable_ip
= ip
;
2816 curr
->softirq_disable_event
= ++curr
->irq_events
;
2817 debug_atomic_inc(softirqs_off_events
);
2819 * Whoops, we wanted softirqs off, so why aren't they?
2821 DEBUG_LOCKS_WARN_ON(!softirq_count());
2823 debug_atomic_inc(redundant_softirqs_off
);
2826 static void __lockdep_trace_alloc(gfp_t gfp_mask
, unsigned long flags
)
2828 struct task_struct
*curr
= current
;
2830 if (unlikely(!debug_locks
))
2833 /* no reclaim without waiting on it */
2834 if (!(gfp_mask
& __GFP_DIRECT_RECLAIM
))
2837 /* this guy won't enter reclaim */
2838 if ((curr
->flags
& PF_MEMALLOC
) && !(gfp_mask
& __GFP_NOMEMALLOC
))
2841 /* We're only interested __GFP_FS allocations for now */
2842 if (!(gfp_mask
& __GFP_FS
))
2846 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2848 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags
)))
2851 mark_held_locks(curr
, RECLAIM_FS
);
2854 static void check_flags(unsigned long flags
);
2856 void lockdep_trace_alloc(gfp_t gfp_mask
)
2858 unsigned long flags
;
2860 if (unlikely(current
->lockdep_recursion
))
2863 raw_local_irq_save(flags
);
2865 current
->lockdep_recursion
= 1;
2866 __lockdep_trace_alloc(gfp_mask
, flags
);
2867 current
->lockdep_recursion
= 0;
2868 raw_local_irq_restore(flags
);
2871 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2874 * If non-trylock use in a hardirq or softirq context, then
2875 * mark the lock as used in these contexts:
2877 if (!hlock
->trylock
) {
2879 if (curr
->hardirq_context
)
2880 if (!mark_lock(curr
, hlock
,
2881 LOCK_USED_IN_HARDIRQ_READ
))
2883 if (curr
->softirq_context
)
2884 if (!mark_lock(curr
, hlock
,
2885 LOCK_USED_IN_SOFTIRQ_READ
))
2888 if (curr
->hardirq_context
)
2889 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2891 if (curr
->softirq_context
)
2892 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2896 if (!hlock
->hardirqs_off
) {
2898 if (!mark_lock(curr
, hlock
,
2899 LOCK_ENABLED_HARDIRQ_READ
))
2901 if (curr
->softirqs_enabled
)
2902 if (!mark_lock(curr
, hlock
,
2903 LOCK_ENABLED_SOFTIRQ_READ
))
2906 if (!mark_lock(curr
, hlock
,
2907 LOCK_ENABLED_HARDIRQ
))
2909 if (curr
->softirqs_enabled
)
2910 if (!mark_lock(curr
, hlock
,
2911 LOCK_ENABLED_SOFTIRQ
))
2917 * We reuse the irq context infrastructure more broadly as a general
2918 * context checking code. This tests GFP_FS recursion (a lock taken
2919 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2922 if (!hlock
->trylock
&& (curr
->lockdep_reclaim_gfp
& __GFP_FS
)) {
2924 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS_READ
))
2927 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS
))
2935 static inline unsigned int task_irq_context(struct task_struct
*task
)
2937 return 2 * !!task
->hardirq_context
+ !!task
->softirq_context
;
2940 static int separate_irq_context(struct task_struct
*curr
,
2941 struct held_lock
*hlock
)
2943 unsigned int depth
= curr
->lockdep_depth
;
2946 * Keep track of points where we cross into an interrupt context:
2949 struct held_lock
*prev_hlock
;
2951 prev_hlock
= curr
->held_locks
+ depth
-1;
2953 * If we cross into another context, reset the
2954 * hash key (this also prevents the checking and the
2955 * adding of the dependency to 'prev'):
2957 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2963 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2966 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2967 enum lock_usage_bit new_bit
)
2969 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2973 static inline int mark_irqflags(struct task_struct
*curr
,
2974 struct held_lock
*hlock
)
2979 static inline unsigned int task_irq_context(struct task_struct
*task
)
2984 static inline int separate_irq_context(struct task_struct
*curr
,
2985 struct held_lock
*hlock
)
2990 void lockdep_trace_alloc(gfp_t gfp_mask
)
2994 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2997 * Mark a lock with a usage bit, and validate the state transition:
2999 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
3000 enum lock_usage_bit new_bit
)
3002 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
3005 * If already set then do not dirty the cacheline,
3006 * nor do any checks:
3008 if (likely(hlock_class(this)->usage_mask
& new_mask
))
3014 * Make sure we didn't race:
3016 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
3021 hlock_class(this)->usage_mask
|= new_mask
;
3023 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
3027 #define LOCKDEP_STATE(__STATE) \
3028 case LOCK_USED_IN_##__STATE: \
3029 case LOCK_USED_IN_##__STATE##_READ: \
3030 case LOCK_ENABLED_##__STATE: \
3031 case LOCK_ENABLED_##__STATE##_READ:
3032 #include "lockdep_states.h"
3033 #undef LOCKDEP_STATE
3034 ret
= mark_lock_irq(curr
, this, new_bit
);
3039 debug_atomic_dec(nr_unused_locks
);
3042 if (!debug_locks_off_graph_unlock())
3051 * We must printk outside of the graph_lock:
3054 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
3056 print_irqtrace_events(curr
);
3064 * Initialize a lock instance's lock-class mapping info:
3066 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
3067 struct lock_class_key
*key
, int subclass
)
3071 kmemcheck_mark_initialized(lock
, sizeof(*lock
));
3073 for (i
= 0; i
< NR_LOCKDEP_CACHING_CLASSES
; i
++)
3074 lock
->class_cache
[i
] = NULL
;
3076 #ifdef CONFIG_LOCK_STAT
3077 lock
->cpu
= raw_smp_processor_id();
3081 * Can't be having no nameless bastards around this place!
3083 if (DEBUG_LOCKS_WARN_ON(!name
)) {
3084 lock
->name
= "NULL";
3091 * No key, no joy, we need to hash something.
3093 if (DEBUG_LOCKS_WARN_ON(!key
))
3096 * Sanity check, the lock-class key must be persistent:
3098 if (!static_obj(key
)) {
3099 printk("BUG: key %p not in .data!\n", key
);
3101 * What it says above ^^^^^, I suggest you read it.
3103 DEBUG_LOCKS_WARN_ON(1);
3108 if (unlikely(!debug_locks
))
3112 unsigned long flags
;
3114 if (DEBUG_LOCKS_WARN_ON(current
->lockdep_recursion
))
3117 raw_local_irq_save(flags
);
3118 current
->lockdep_recursion
= 1;
3119 register_lock_class(lock
, subclass
, 1);
3120 current
->lockdep_recursion
= 0;
3121 raw_local_irq_restore(flags
);
3124 EXPORT_SYMBOL_GPL(lockdep_init_map
);
3126 struct lock_class_key __lockdep_no_validate__
;
3127 EXPORT_SYMBOL_GPL(__lockdep_no_validate__
);
3130 print_lock_nested_lock_not_held(struct task_struct
*curr
,
3131 struct held_lock
*hlock
,
3134 if (!debug_locks_off())
3136 if (debug_locks_silent
)
3140 printk("==================================\n");
3141 printk("[ BUG: Nested lock was not taken ]\n");
3142 print_kernel_ident();
3143 printk("----------------------------------\n");
3145 printk("%s/%d is trying to lock:\n", curr
->comm
, task_pid_nr(curr
));
3148 printk("\nbut this task is not holding:\n");
3149 printk("%s\n", hlock
->nest_lock
->name
);
3151 printk("\nstack backtrace:\n");
3154 printk("\nother info that might help us debug this:\n");
3155 lockdep_print_held_locks(curr
);
3157 printk("\nstack backtrace:\n");
3163 static int __lock_is_held(struct lockdep_map
*lock
);
3166 * This gets called for every mutex_lock*()/spin_lock*() operation.
3167 * We maintain the dependency maps and validate the locking attempt:
3169 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3170 int trylock
, int read
, int check
, int hardirqs_off
,
3171 struct lockdep_map
*nest_lock
, unsigned long ip
,
3172 int references
, int pin_count
)
3174 struct task_struct
*curr
= current
;
3175 struct lock_class
*class = NULL
;
3176 struct held_lock
*hlock
;
3182 if (unlikely(!debug_locks
))
3186 * Lockdep should run with IRQs disabled, otherwise we could
3187 * get an interrupt which would want to take locks, which would
3188 * end up in lockdep and have you got a head-ache already?
3190 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3193 if (!prove_locking
|| lock
->key
== &__lockdep_no_validate__
)
3196 if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
3197 class = lock
->class_cache
[subclass
];
3201 if (unlikely(!class)) {
3202 class = register_lock_class(lock
, subclass
, 0);
3206 atomic_inc((atomic_t
*)&class->ops
);
3207 if (very_verbose(class)) {
3208 printk("\nacquire class [%p] %s", class->key
, class->name
);
3209 if (class->name_version
> 1)
3210 printk("#%d", class->name_version
);
3216 * Add the lock to the list of currently held locks.
3217 * (we dont increase the depth just yet, up until the
3218 * dependency checks are done)
3220 depth
= curr
->lockdep_depth
;
3222 * Ran out of static storage for our per-task lock stack again have we?
3224 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
3227 class_idx
= class - lock_classes
+ 1;
3230 hlock
= curr
->held_locks
+ depth
- 1;
3231 if (hlock
->class_idx
== class_idx
&& nest_lock
) {
3232 if (hlock
->references
)
3233 hlock
->references
++;
3235 hlock
->references
= 2;
3241 hlock
= curr
->held_locks
+ depth
;
3243 * Plain impossible, we just registered it and checked it weren't no
3244 * NULL like.. I bet this mushroom I ate was good!
3246 if (DEBUG_LOCKS_WARN_ON(!class))
3248 hlock
->class_idx
= class_idx
;
3249 hlock
->acquire_ip
= ip
;
3250 hlock
->instance
= lock
;
3251 hlock
->nest_lock
= nest_lock
;
3252 hlock
->irq_context
= task_irq_context(curr
);
3253 hlock
->trylock
= trylock
;
3255 hlock
->check
= check
;
3256 hlock
->hardirqs_off
= !!hardirqs_off
;
3257 hlock
->references
= references
;
3258 #ifdef CONFIG_LOCK_STAT
3259 hlock
->waittime_stamp
= 0;
3260 hlock
->holdtime_stamp
= lockstat_clock();
3262 hlock
->pin_count
= pin_count
;
3264 if (check
&& !mark_irqflags(curr
, hlock
))
3267 /* mark it as used: */
3268 if (!mark_lock(curr
, hlock
, LOCK_USED
))
3272 * Calculate the chain hash: it's the combined hash of all the
3273 * lock keys along the dependency chain. We save the hash value
3274 * at every step so that we can get the current hash easily
3275 * after unlock. The chain hash is then used to cache dependency
3278 * The 'key ID' is what is the most compact key value to drive
3279 * the hash, not class->key.
3282 * Whoops, we did it again.. ran straight out of our static allocation.
3284 if (DEBUG_LOCKS_WARN_ON(class_idx
> MAX_LOCKDEP_KEYS
))
3287 chain_key
= curr
->curr_chain_key
;
3290 * How can we have a chain hash when we ain't got no keys?!
3292 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
3297 hlock
->prev_chain_key
= chain_key
;
3298 if (separate_irq_context(curr
, hlock
)) {
3302 chain_key
= iterate_chain_key(chain_key
, class_idx
);
3304 if (nest_lock
&& !__lock_is_held(nest_lock
))
3305 return print_lock_nested_lock_not_held(curr
, hlock
, ip
);
3307 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
3310 curr
->curr_chain_key
= chain_key
;
3311 curr
->lockdep_depth
++;
3312 check_chain_key(curr
);
3313 #ifdef CONFIG_DEBUG_LOCKDEP
3314 if (unlikely(!debug_locks
))
3317 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
3319 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3320 printk(KERN_DEBUG
"depth: %i max: %lu!\n",
3321 curr
->lockdep_depth
, MAX_LOCK_DEPTH
);
3323 lockdep_print_held_locks(current
);
3324 debug_show_all_locks();
3330 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
3331 max_lockdep_depth
= curr
->lockdep_depth
;
3337 print_unlock_imbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3340 if (!debug_locks_off())
3342 if (debug_locks_silent
)
3346 printk("=====================================\n");
3347 printk("[ BUG: bad unlock balance detected! ]\n");
3348 print_kernel_ident();
3349 printk("-------------------------------------\n");
3350 printk("%s/%d is trying to release lock (",
3351 curr
->comm
, task_pid_nr(curr
));
3352 print_lockdep_cache(lock
);
3355 printk("but there are no more locks to release!\n");
3356 printk("\nother info that might help us debug this:\n");
3357 lockdep_print_held_locks(curr
);
3359 printk("\nstack backtrace:\n");
3365 static int match_held_lock(struct held_lock
*hlock
, struct lockdep_map
*lock
)
3367 if (hlock
->instance
== lock
)
3370 if (hlock
->references
) {
3371 struct lock_class
*class = lock
->class_cache
[0];
3374 class = look_up_lock_class(lock
, 0);
3377 * If look_up_lock_class() failed to find a class, we're trying
3378 * to test if we hold a lock that has never yet been acquired.
3379 * Clearly if the lock hasn't been acquired _ever_, we're not
3380 * holding it either, so report failure.
3386 * References, but not a lock we're actually ref-counting?
3387 * State got messed up, follow the sites that change ->references
3388 * and try to make sense of it.
3390 if (DEBUG_LOCKS_WARN_ON(!hlock
->nest_lock
))
3393 if (hlock
->class_idx
== class - lock_classes
+ 1)
3401 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
3402 struct lock_class_key
*key
, unsigned int subclass
,
3405 struct task_struct
*curr
= current
;
3406 struct held_lock
*hlock
, *prev_hlock
;
3407 struct lock_class
*class;
3411 depth
= curr
->lockdep_depth
;
3413 * This function is about (re)setting the class of a held lock,
3414 * yet we're not actually holding any locks. Naughty user!
3416 if (DEBUG_LOCKS_WARN_ON(!depth
))
3420 for (i
= depth
-1; i
>= 0; i
--) {
3421 hlock
= curr
->held_locks
+ i
;
3423 * We must not cross into another context:
3425 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3427 if (match_held_lock(hlock
, lock
))
3431 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3434 lockdep_init_map(lock
, name
, key
, 0);
3435 class = register_lock_class(lock
, subclass
, 0);
3436 hlock
->class_idx
= class - lock_classes
+ 1;
3438 curr
->lockdep_depth
= i
;
3439 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3441 for (; i
< depth
; i
++) {
3442 hlock
= curr
->held_locks
+ i
;
3443 if (!__lock_acquire(hlock
->instance
,
3444 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3445 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3446 hlock
->nest_lock
, hlock
->acquire_ip
,
3447 hlock
->references
, hlock
->pin_count
))
3452 * I took it apart and put it back together again, except now I have
3453 * these 'spare' parts.. where shall I put them.
3455 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
3461 * Remove the lock to the list of currently held locks - this gets
3462 * called on mutex_unlock()/spin_unlock*() (or on a failed
3463 * mutex_lock_interruptible()).
3465 * @nested is an hysterical artifact, needs a tree wide cleanup.
3468 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
3470 struct task_struct
*curr
= current
;
3471 struct held_lock
*hlock
, *prev_hlock
;
3475 if (unlikely(!debug_locks
))
3478 depth
= curr
->lockdep_depth
;
3480 * So we're all set to release this lock.. wait what lock? We don't
3481 * own any locks, you've been drinking again?
3483 if (DEBUG_LOCKS_WARN_ON(depth
<= 0))
3484 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3487 * Check whether the lock exists in the current stack
3491 for (i
= depth
-1; i
>= 0; i
--) {
3492 hlock
= curr
->held_locks
+ i
;
3494 * We must not cross into another context:
3496 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3498 if (match_held_lock(hlock
, lock
))
3502 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3505 if (hlock
->instance
== lock
)
3506 lock_release_holdtime(hlock
);
3508 WARN(hlock
->pin_count
, "releasing a pinned lock\n");
3510 if (hlock
->references
) {
3511 hlock
->references
--;
3512 if (hlock
->references
) {
3514 * We had, and after removing one, still have
3515 * references, the current lock stack is still
3516 * valid. We're done!
3523 * We have the right lock to unlock, 'hlock' points to it.
3524 * Now we remove it from the stack, and add back the other
3525 * entries (if any), recalculating the hash along the way:
3528 curr
->lockdep_depth
= i
;
3529 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3531 for (i
++; i
< depth
; i
++) {
3532 hlock
= curr
->held_locks
+ i
;
3533 if (!__lock_acquire(hlock
->instance
,
3534 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3535 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3536 hlock
->nest_lock
, hlock
->acquire_ip
,
3537 hlock
->references
, hlock
->pin_count
))
3542 * We had N bottles of beer on the wall, we drank one, but now
3543 * there's not N-1 bottles of beer left on the wall...
3545 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
3551 static int __lock_is_held(struct lockdep_map
*lock
)
3553 struct task_struct
*curr
= current
;
3556 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3557 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3559 if (match_held_lock(hlock
, lock
))
3566 static void __lock_pin_lock(struct lockdep_map
*lock
)
3568 struct task_struct
*curr
= current
;
3571 if (unlikely(!debug_locks
))
3574 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3575 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3577 if (match_held_lock(hlock
, lock
)) {
3583 WARN(1, "pinning an unheld lock\n");
3586 static void __lock_unpin_lock(struct lockdep_map
*lock
)
3588 struct task_struct
*curr
= current
;
3591 if (unlikely(!debug_locks
))
3594 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3595 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3597 if (match_held_lock(hlock
, lock
)) {
3598 if (WARN(!hlock
->pin_count
, "unpinning an unpinned lock\n"))
3606 WARN(1, "unpinning an unheld lock\n");
3610 * Check whether we follow the irq-flags state precisely:
3612 static void check_flags(unsigned long flags
)
3614 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3615 defined(CONFIG_TRACE_IRQFLAGS)
3619 if (irqs_disabled_flags(flags
)) {
3620 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
3621 printk("possible reason: unannotated irqs-off.\n");
3624 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
3625 printk("possible reason: unannotated irqs-on.\n");
3630 * We dont accurately track softirq state in e.g.
3631 * hardirq contexts (such as on 4KSTACKS), so only
3632 * check if not in hardirq contexts:
3634 if (!hardirq_count()) {
3635 if (softirq_count()) {
3636 /* like the above, but with softirqs */
3637 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
3639 /* lick the above, does it taste good? */
3640 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
3645 print_irqtrace_events(current
);
3649 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
3650 struct lock_class_key
*key
, unsigned int subclass
,
3653 unsigned long flags
;
3655 if (unlikely(current
->lockdep_recursion
))
3658 raw_local_irq_save(flags
);
3659 current
->lockdep_recursion
= 1;
3661 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
3662 check_chain_key(current
);
3663 current
->lockdep_recursion
= 0;
3664 raw_local_irq_restore(flags
);
3666 EXPORT_SYMBOL_GPL(lock_set_class
);
3669 * We are not always called with irqs disabled - do that here,
3670 * and also avoid lockdep recursion:
3672 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3673 int trylock
, int read
, int check
,
3674 struct lockdep_map
*nest_lock
, unsigned long ip
)
3676 unsigned long flags
;
3678 if (unlikely(current
->lockdep_recursion
))
3681 raw_local_irq_save(flags
);
3684 current
->lockdep_recursion
= 1;
3685 trace_lock_acquire(lock
, subclass
, trylock
, read
, check
, nest_lock
, ip
);
3686 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
3687 irqs_disabled_flags(flags
), nest_lock
, ip
, 0, 0);
3688 current
->lockdep_recursion
= 0;
3689 raw_local_irq_restore(flags
);
3691 EXPORT_SYMBOL_GPL(lock_acquire
);
3693 void lock_release(struct lockdep_map
*lock
, int nested
,
3696 unsigned long flags
;
3698 if (unlikely(current
->lockdep_recursion
))
3701 raw_local_irq_save(flags
);
3703 current
->lockdep_recursion
= 1;
3704 trace_lock_release(lock
, ip
);
3705 if (__lock_release(lock
, nested
, ip
))
3706 check_chain_key(current
);
3707 current
->lockdep_recursion
= 0;
3708 raw_local_irq_restore(flags
);
3710 EXPORT_SYMBOL_GPL(lock_release
);
3712 int lock_is_held(struct lockdep_map
*lock
)
3714 unsigned long flags
;
3717 if (unlikely(current
->lockdep_recursion
))
3718 return 1; /* avoid false negative lockdep_assert_held() */
3720 raw_local_irq_save(flags
);
3723 current
->lockdep_recursion
= 1;
3724 ret
= __lock_is_held(lock
);
3725 current
->lockdep_recursion
= 0;
3726 raw_local_irq_restore(flags
);
3730 EXPORT_SYMBOL_GPL(lock_is_held
);
3732 void lock_pin_lock(struct lockdep_map
*lock
)
3734 unsigned long flags
;
3736 if (unlikely(current
->lockdep_recursion
))
3739 raw_local_irq_save(flags
);
3742 current
->lockdep_recursion
= 1;
3743 __lock_pin_lock(lock
);
3744 current
->lockdep_recursion
= 0;
3745 raw_local_irq_restore(flags
);
3747 EXPORT_SYMBOL_GPL(lock_pin_lock
);
3749 void lock_unpin_lock(struct lockdep_map
*lock
)
3751 unsigned long flags
;
3753 if (unlikely(current
->lockdep_recursion
))
3756 raw_local_irq_save(flags
);
3759 current
->lockdep_recursion
= 1;
3760 __lock_unpin_lock(lock
);
3761 current
->lockdep_recursion
= 0;
3762 raw_local_irq_restore(flags
);
3764 EXPORT_SYMBOL_GPL(lock_unpin_lock
);
3766 void lockdep_set_current_reclaim_state(gfp_t gfp_mask
)
3768 current
->lockdep_reclaim_gfp
= gfp_mask
;
3771 void lockdep_clear_current_reclaim_state(void)
3773 current
->lockdep_reclaim_gfp
= 0;
3776 #ifdef CONFIG_LOCK_STAT
3778 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3781 if (!debug_locks_off())
3783 if (debug_locks_silent
)
3787 printk("=================================\n");
3788 printk("[ BUG: bad contention detected! ]\n");
3789 print_kernel_ident();
3790 printk("---------------------------------\n");
3791 printk("%s/%d is trying to contend lock (",
3792 curr
->comm
, task_pid_nr(curr
));
3793 print_lockdep_cache(lock
);
3796 printk("but there are no locks held!\n");
3797 printk("\nother info that might help us debug this:\n");
3798 lockdep_print_held_locks(curr
);
3800 printk("\nstack backtrace:\n");
3807 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3809 struct task_struct
*curr
= current
;
3810 struct held_lock
*hlock
, *prev_hlock
;
3811 struct lock_class_stats
*stats
;
3813 int i
, contention_point
, contending_point
;
3815 depth
= curr
->lockdep_depth
;
3817 * Whee, we contended on this lock, except it seems we're not
3818 * actually trying to acquire anything much at all..
3820 if (DEBUG_LOCKS_WARN_ON(!depth
))
3824 for (i
= depth
-1; i
>= 0; i
--) {
3825 hlock
= curr
->held_locks
+ i
;
3827 * We must not cross into another context:
3829 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3831 if (match_held_lock(hlock
, lock
))
3835 print_lock_contention_bug(curr
, lock
, ip
);
3839 if (hlock
->instance
!= lock
)
3842 hlock
->waittime_stamp
= lockstat_clock();
3844 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3845 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3848 stats
= get_lock_stats(hlock_class(hlock
));
3849 if (contention_point
< LOCKSTAT_POINTS
)
3850 stats
->contention_point
[contention_point
]++;
3851 if (contending_point
< LOCKSTAT_POINTS
)
3852 stats
->contending_point
[contending_point
]++;
3853 if (lock
->cpu
!= smp_processor_id())
3854 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3855 put_lock_stats(stats
);
3859 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3861 struct task_struct
*curr
= current
;
3862 struct held_lock
*hlock
, *prev_hlock
;
3863 struct lock_class_stats
*stats
;
3865 u64 now
, waittime
= 0;
3868 depth
= curr
->lockdep_depth
;
3870 * Yay, we acquired ownership of this lock we didn't try to
3871 * acquire, how the heck did that happen?
3873 if (DEBUG_LOCKS_WARN_ON(!depth
))
3877 for (i
= depth
-1; i
>= 0; i
--) {
3878 hlock
= curr
->held_locks
+ i
;
3880 * We must not cross into another context:
3882 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3884 if (match_held_lock(hlock
, lock
))
3888 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3892 if (hlock
->instance
!= lock
)
3895 cpu
= smp_processor_id();
3896 if (hlock
->waittime_stamp
) {
3897 now
= lockstat_clock();
3898 waittime
= now
- hlock
->waittime_stamp
;
3899 hlock
->holdtime_stamp
= now
;
3902 trace_lock_acquired(lock
, ip
);
3904 stats
= get_lock_stats(hlock_class(hlock
));
3907 lock_time_inc(&stats
->read_waittime
, waittime
);
3909 lock_time_inc(&stats
->write_waittime
, waittime
);
3911 if (lock
->cpu
!= cpu
)
3912 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3913 put_lock_stats(stats
);
3919 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3921 unsigned long flags
;
3923 if (unlikely(!lock_stat
))
3926 if (unlikely(current
->lockdep_recursion
))
3929 raw_local_irq_save(flags
);
3931 current
->lockdep_recursion
= 1;
3932 trace_lock_contended(lock
, ip
);
3933 __lock_contended(lock
, ip
);
3934 current
->lockdep_recursion
= 0;
3935 raw_local_irq_restore(flags
);
3937 EXPORT_SYMBOL_GPL(lock_contended
);
3939 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3941 unsigned long flags
;
3943 if (unlikely(!lock_stat
))
3946 if (unlikely(current
->lockdep_recursion
))
3949 raw_local_irq_save(flags
);
3951 current
->lockdep_recursion
= 1;
3952 __lock_acquired(lock
, ip
);
3953 current
->lockdep_recursion
= 0;
3954 raw_local_irq_restore(flags
);
3956 EXPORT_SYMBOL_GPL(lock_acquired
);
3960 * Used by the testsuite, sanitize the validator state
3961 * after a simulated failure:
3964 void lockdep_reset(void)
3966 unsigned long flags
;
3969 raw_local_irq_save(flags
);
3970 current
->curr_chain_key
= 0;
3971 current
->lockdep_depth
= 0;
3972 current
->lockdep_recursion
= 0;
3973 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3974 nr_hardirq_chains
= 0;
3975 nr_softirq_chains
= 0;
3976 nr_process_chains
= 0;
3978 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3979 INIT_HLIST_HEAD(chainhash_table
+ i
);
3980 raw_local_irq_restore(flags
);
3983 static void zap_class(struct lock_class
*class)
3988 * Remove all dependencies this lock is
3991 for (i
= 0; i
< nr_list_entries
; i
++) {
3992 if (list_entries
[i
].class == class)
3993 list_del_rcu(&list_entries
[i
].entry
);
3996 * Unhash the class and remove it from the all_lock_classes list:
3998 hlist_del_rcu(&class->hash_entry
);
3999 list_del_rcu(&class->lock_entry
);
4001 RCU_INIT_POINTER(class->key
, NULL
);
4002 RCU_INIT_POINTER(class->name
, NULL
);
4005 static inline int within(const void *addr
, void *start
, unsigned long size
)
4007 return addr
>= start
&& addr
< start
+ size
;
4011 * Used in module.c to remove lock classes from memory that is going to be
4012 * freed; and possibly re-used by other modules.
4014 * We will have had one sync_sched() before getting here, so we're guaranteed
4015 * nobody will look up these exact classes -- they're properly dead but still
4018 void lockdep_free_key_range(void *start
, unsigned long size
)
4020 struct lock_class
*class;
4021 struct hlist_head
*head
;
4022 unsigned long flags
;
4026 raw_local_irq_save(flags
);
4027 locked
= graph_lock();
4030 * Unhash all classes that were created by this module:
4032 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
4033 head
= classhash_table
+ i
;
4034 hlist_for_each_entry_rcu(class, head
, hash_entry
) {
4035 if (within(class->key
, start
, size
))
4037 else if (within(class->name
, start
, size
))
4044 raw_local_irq_restore(flags
);
4047 * Wait for any possible iterators from look_up_lock_class() to pass
4048 * before continuing to free the memory they refer to.
4050 * sync_sched() is sufficient because the read-side is IRQ disable.
4052 synchronize_sched();
4055 * XXX at this point we could return the resources to the pool;
4056 * instead we leak them. We would need to change to bitmap allocators
4057 * instead of the linear allocators we have now.
4061 void lockdep_reset_lock(struct lockdep_map
*lock
)
4063 struct lock_class
*class;
4064 struct hlist_head
*head
;
4065 unsigned long flags
;
4069 raw_local_irq_save(flags
);
4072 * Remove all classes this lock might have:
4074 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
4076 * If the class exists we look it up and zap it:
4078 class = look_up_lock_class(lock
, j
);
4083 * Debug check: in the end all mapped classes should
4086 locked
= graph_lock();
4087 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
4088 head
= classhash_table
+ i
;
4089 hlist_for_each_entry_rcu(class, head
, hash_entry
) {
4092 for (j
= 0; j
< NR_LOCKDEP_CACHING_CLASSES
; j
++)
4093 match
|= class == lock
->class_cache
[j
];
4095 if (unlikely(match
)) {
4096 if (debug_locks_off_graph_unlock()) {
4098 * We all just reset everything, how did it match?
4110 raw_local_irq_restore(flags
);
4113 void __init
lockdep_info(void)
4115 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4117 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
4118 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
4119 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
4120 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
4121 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
4122 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
4123 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
4125 printk(" memory used by lock dependency info: %lu kB\n",
4126 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
4127 sizeof(struct list_head
) * CLASSHASH_SIZE
+
4128 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
4129 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
4130 sizeof(struct list_head
) * CHAINHASH_SIZE
4131 #ifdef CONFIG_PROVE_LOCKING
4132 + sizeof(struct circular_queue
)
4137 printk(" per task-struct memory footprint: %lu bytes\n",
4138 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
4142 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
4143 const void *mem_to
, struct held_lock
*hlock
)
4145 if (!debug_locks_off())
4147 if (debug_locks_silent
)
4151 printk("=========================\n");
4152 printk("[ BUG: held lock freed! ]\n");
4153 print_kernel_ident();
4154 printk("-------------------------\n");
4155 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4156 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
4158 lockdep_print_held_locks(curr
);
4160 printk("\nstack backtrace:\n");
4164 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
4165 const void* lock_from
, unsigned long lock_len
)
4167 return lock_from
+ lock_len
<= mem_from
||
4168 mem_from
+ mem_len
<= lock_from
;
4172 * Called when kernel memory is freed (or unmapped), or if a lock
4173 * is destroyed or reinitialized - this code checks whether there is
4174 * any held lock in the memory range of <from> to <to>:
4176 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
4178 struct task_struct
*curr
= current
;
4179 struct held_lock
*hlock
;
4180 unsigned long flags
;
4183 if (unlikely(!debug_locks
))
4186 local_irq_save(flags
);
4187 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
4188 hlock
= curr
->held_locks
+ i
;
4190 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
4191 sizeof(*hlock
->instance
)))
4194 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
4197 local_irq_restore(flags
);
4199 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
4201 static void print_held_locks_bug(void)
4203 if (!debug_locks_off())
4205 if (debug_locks_silent
)
4209 printk("=====================================\n");
4210 printk("[ BUG: %s/%d still has locks held! ]\n",
4211 current
->comm
, task_pid_nr(current
));
4212 print_kernel_ident();
4213 printk("-------------------------------------\n");
4214 lockdep_print_held_locks(current
);
4215 printk("\nstack backtrace:\n");
4219 void debug_check_no_locks_held(void)
4221 if (unlikely(current
->lockdep_depth
> 0))
4222 print_held_locks_bug();
4224 EXPORT_SYMBOL_GPL(debug_check_no_locks_held
);
4227 void debug_show_all_locks(void)
4229 struct task_struct
*g
, *p
;
4233 if (unlikely(!debug_locks
)) {
4234 printk("INFO: lockdep is turned off.\n");
4237 printk("\nShowing all locks held in the system:\n");
4240 * Here we try to get the tasklist_lock as hard as possible,
4241 * if not successful after 2 seconds we ignore it (but keep
4242 * trying). This is to enable a debug printout even if a
4243 * tasklist_lock-holding task deadlocks or crashes.
4246 if (!read_trylock(&tasklist_lock
)) {
4248 printk("hm, tasklist_lock locked, retrying... ");
4251 printk(" #%d", 10-count
);
4255 printk(" ignoring it.\n");
4259 printk(KERN_CONT
" locked it.\n");
4262 do_each_thread(g
, p
) {
4264 * It's not reliable to print a task's held locks
4265 * if it's not sleeping (or if it's not the current
4268 if (p
->state
== TASK_RUNNING
&& p
!= current
)
4270 if (p
->lockdep_depth
)
4271 lockdep_print_held_locks(p
);
4273 if (read_trylock(&tasklist_lock
))
4275 } while_each_thread(g
, p
);
4278 printk("=============================================\n\n");
4281 read_unlock(&tasklist_lock
);
4283 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
4287 * Careful: only use this function if you are sure that
4288 * the task cannot run in parallel!
4290 void debug_show_held_locks(struct task_struct
*task
)
4292 if (unlikely(!debug_locks
)) {
4293 printk("INFO: lockdep is turned off.\n");
4296 lockdep_print_held_locks(task
);
4298 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
4300 asmlinkage __visible
void lockdep_sys_exit(void)
4302 struct task_struct
*curr
= current
;
4304 if (unlikely(curr
->lockdep_depth
)) {
4305 if (!debug_locks_off())
4308 printk("================================================\n");
4309 printk("[ BUG: lock held when returning to user space! ]\n");
4310 print_kernel_ident();
4311 printk("------------------------------------------------\n");
4312 printk("%s/%d is leaving the kernel with locks still held!\n",
4313 curr
->comm
, curr
->pid
);
4314 lockdep_print_held_locks(curr
);
4318 void lockdep_rcu_suspicious(const char *file
, const int line
, const char *s
)
4320 struct task_struct
*curr
= current
;
4322 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4323 if (!debug_locks_off())
4325 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4326 /* Note: the following can be executed concurrently, so be careful. */
4328 printk("===============================\n");
4329 printk("[ INFO: suspicious RCU usage. ]\n");
4330 print_kernel_ident();
4331 printk("-------------------------------\n");
4332 printk("%s:%d %s!\n", file
, line
, s
);
4333 printk("\nother info that might help us debug this:\n\n");
4334 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4335 !rcu_lockdep_current_cpu_online()
4336 ? "RCU used illegally from offline CPU!\n"
4337 : !rcu_is_watching()
4338 ? "RCU used illegally from idle CPU!\n"
4340 rcu_scheduler_active
, debug_locks
);
4343 * If a CPU is in the RCU-free window in idle (ie: in the section
4344 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4345 * considers that CPU to be in an "extended quiescent state",
4346 * which means that RCU will be completely ignoring that CPU.
4347 * Therefore, rcu_read_lock() and friends have absolutely no
4348 * effect on a CPU running in that state. In other words, even if
4349 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4350 * delete data structures out from under it. RCU really has no
4351 * choice here: we need to keep an RCU-free window in idle where
4352 * the CPU may possibly enter into low power mode. This way we can
4353 * notice an extended quiescent state to other CPUs that started a grace
4354 * period. Otherwise we would delay any grace period as long as we run
4357 * So complain bitterly if someone does call rcu_read_lock(),
4358 * rcu_read_lock_bh() and so on from extended quiescent states.
4360 if (!rcu_is_watching())
4361 printk("RCU used illegally from extended quiescent state!\n");
4363 lockdep_print_held_locks(curr
);
4364 printk("\nstack backtrace:\n");
4367 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious
);