4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
47 #include <linux/kmemcheck.h>
49 #include <asm/sections.h>
51 #include "lockdep_internals.h"
53 #define CREATE_TRACE_POINTS
54 #include <trace/events/lock.h>
56 #ifdef CONFIG_PROVE_LOCKING
57 int prove_locking
= 1;
58 module_param(prove_locking
, int, 0644);
60 #define prove_locking 0
63 #ifdef CONFIG_LOCK_STAT
65 module_param(lock_stat
, int, 0644);
71 * lockdep_lock: protects the lockdep graph, the hashes and the
72 * class/list/hash allocators.
74 * This is one of the rare exceptions where it's justified
75 * to use a raw spinlock - we really dont want the spinlock
76 * code to recurse back into the lockdep code...
78 static arch_spinlock_t lockdep_lock
= (arch_spinlock_t
)__ARCH_SPIN_LOCK_UNLOCKED
;
80 static int graph_lock(void)
82 arch_spin_lock(&lockdep_lock
);
84 * Make sure that if another CPU detected a bug while
85 * walking the graph we dont change it (while the other
86 * CPU is busy printing out stuff with the graph lock
90 arch_spin_unlock(&lockdep_lock
);
93 /* prevent any recursions within lockdep from causing deadlocks */
94 current
->lockdep_recursion
++;
98 static inline int graph_unlock(void)
100 if (debug_locks
&& !arch_spin_is_locked(&lockdep_lock
)) {
102 * The lockdep graph lock isn't locked while we expect it to
103 * be, we're confused now, bye!
105 return DEBUG_LOCKS_WARN_ON(1);
108 current
->lockdep_recursion
--;
109 arch_spin_unlock(&lockdep_lock
);
114 * Turn lock debugging off and return with 0 if it was off already,
115 * and also release the graph lock:
117 static inline int debug_locks_off_graph_unlock(void)
119 int ret
= debug_locks_off();
121 arch_spin_unlock(&lockdep_lock
);
126 static int lockdep_initialized
;
128 unsigned long nr_list_entries
;
129 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
132 * All data structures here are protected by the global debug_lock.
134 * Mutex key structs only get allocated, once during bootup, and never
135 * get freed - this significantly simplifies the debugging code.
137 unsigned long nr_lock_classes
;
138 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
140 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
142 if (!hlock
->class_idx
) {
144 * Someone passed in garbage, we give up.
146 DEBUG_LOCKS_WARN_ON(1);
149 return lock_classes
+ hlock
->class_idx
- 1;
152 #ifdef CONFIG_LOCK_STAT
153 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
],
156 static inline u64
lockstat_clock(void)
158 return local_clock();
161 static int lock_point(unsigned long points
[], unsigned long ip
)
165 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
166 if (points
[i
] == 0) {
177 static void lock_time_inc(struct lock_time
*lt
, u64 time
)
182 if (time
< lt
->min
|| !lt
->nr
)
189 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
194 if (src
->max
> dst
->max
)
197 if (src
->min
< dst
->min
|| !dst
->nr
)
200 dst
->total
+= src
->total
;
204 struct lock_class_stats
lock_stats(struct lock_class
*class)
206 struct lock_class_stats stats
;
209 memset(&stats
, 0, sizeof(struct lock_class_stats
));
210 for_each_possible_cpu(cpu
) {
211 struct lock_class_stats
*pcs
=
212 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
214 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
215 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
217 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
218 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
220 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
221 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
223 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
224 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
226 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
227 stats
.bounces
[i
] += pcs
->bounces
[i
];
233 void clear_lock_stats(struct lock_class
*class)
237 for_each_possible_cpu(cpu
) {
238 struct lock_class_stats
*cpu_stats
=
239 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
241 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
243 memset(class->contention_point
, 0, sizeof(class->contention_point
));
244 memset(class->contending_point
, 0, sizeof(class->contending_point
));
247 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
249 return &get_cpu_var(cpu_lock_stats
)[class - lock_classes
];
252 static void put_lock_stats(struct lock_class_stats
*stats
)
254 put_cpu_var(cpu_lock_stats
);
257 static void lock_release_holdtime(struct held_lock
*hlock
)
259 struct lock_class_stats
*stats
;
265 holdtime
= lockstat_clock() - hlock
->holdtime_stamp
;
267 stats
= get_lock_stats(hlock_class(hlock
));
269 lock_time_inc(&stats
->read_holdtime
, holdtime
);
271 lock_time_inc(&stats
->write_holdtime
, holdtime
);
272 put_lock_stats(stats
);
275 static inline void lock_release_holdtime(struct held_lock
*hlock
)
281 * We keep a global list of all lock classes. The list only grows,
282 * never shrinks. The list is only accessed with the lockdep
283 * spinlock lock held.
285 LIST_HEAD(all_lock_classes
);
288 * The lockdep classes are in a hash-table as well, for fast lookup:
290 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
291 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
292 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
293 #define classhashentry(key) (classhash_table + __classhashfn((key)))
295 static struct list_head classhash_table
[CLASSHASH_SIZE
];
298 * We put the lock dependency chains into a hash-table as well, to cache
301 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
302 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
303 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
304 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
306 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
309 * The hash key of the lock dependency chains is a hash itself too:
310 * it's a hash of all locks taken up to that lock, including that lock.
311 * It's a 64-bit hash, because it's important for the keys to be
314 #define iterate_chain_key(key1, key2) \
315 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
316 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
319 void lockdep_off(void)
321 current
->lockdep_recursion
++;
323 EXPORT_SYMBOL(lockdep_off
);
325 void lockdep_on(void)
327 current
->lockdep_recursion
--;
329 EXPORT_SYMBOL(lockdep_on
);
332 * Debugging switches:
336 #define VERY_VERBOSE 0
339 # define HARDIRQ_VERBOSE 1
340 # define SOFTIRQ_VERBOSE 1
341 # define RECLAIM_VERBOSE 1
343 # define HARDIRQ_VERBOSE 0
344 # define SOFTIRQ_VERBOSE 0
345 # define RECLAIM_VERBOSE 0
348 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
350 * Quick filtering for interesting events:
352 static int class_filter(struct lock_class
*class)
356 if (class->name_version
== 1 &&
357 !strcmp(class->name
, "lockname"))
359 if (class->name_version
== 1 &&
360 !strcmp(class->name
, "&struct->lockfield"))
363 /* Filter everything else. 1 would be to allow everything else */
368 static int verbose(struct lock_class
*class)
371 return class_filter(class);
377 * Stack-trace: tightly packed array of stack backtrace
378 * addresses. Protected by the graph_lock.
380 unsigned long nr_stack_trace_entries
;
381 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
383 static int save_trace(struct stack_trace
*trace
)
385 trace
->nr_entries
= 0;
386 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
387 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
391 save_stack_trace(trace
);
394 * Some daft arches put -1 at the end to indicate its a full trace.
396 * <rant> this is buggy anyway, since it takes a whole extra entry so a
397 * complete trace that maxes out the entries provided will be reported
398 * as incomplete, friggin useless </rant>
400 if (trace
->nr_entries
!= 0 &&
401 trace
->entries
[trace
->nr_entries
-1] == ULONG_MAX
)
404 trace
->max_entries
= trace
->nr_entries
;
406 nr_stack_trace_entries
+= trace
->nr_entries
;
408 if (nr_stack_trace_entries
>= MAX_STACK_TRACE_ENTRIES
-1) {
409 if (!debug_locks_off_graph_unlock())
412 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
413 printk("turning off the locking correctness validator.\n");
414 printk("Attach output of /proc/lock_stat to bug report\n");
423 unsigned int nr_hardirq_chains
;
424 unsigned int nr_softirq_chains
;
425 unsigned int nr_process_chains
;
426 unsigned int max_lockdep_depth
;
428 #ifdef CONFIG_DEBUG_LOCKDEP
430 * We cannot printk in early bootup code. Not even early_printk()
431 * might work. So we mark any initialization errors and printk
432 * about it later on, in lockdep_info().
434 static int lockdep_init_error
;
435 static const char *lock_init_error
;
436 static unsigned long lockdep_init_trace_data
[20];
437 static struct stack_trace lockdep_init_trace
= {
438 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
439 .entries
= lockdep_init_trace_data
,
443 * Various lockdep statistics:
445 DEFINE_PER_CPU(struct lockdep_stats
, lockdep_stats
);
452 #define __USAGE(__STATE) \
453 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
454 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
455 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
456 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
458 static const char *usage_str
[] =
460 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
461 #include "lockdep_states.h"
463 [LOCK_USED
] = "INITIAL USE",
466 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
468 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
471 static inline unsigned long lock_flag(enum lock_usage_bit bit
)
476 static char get_usage_char(struct lock_class
*class, enum lock_usage_bit bit
)
480 if (class->usage_mask
& lock_flag(bit
+ 2))
482 if (class->usage_mask
& lock_flag(bit
)) {
484 if (class->usage_mask
& lock_flag(bit
+ 2))
491 void get_usage_chars(struct lock_class
*class, char usage
[LOCK_USAGE_CHARS
])
495 #define LOCKDEP_STATE(__STATE) \
496 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
497 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
498 #include "lockdep_states.h"
504 static void __print_lock_name(struct lock_class
*class)
506 char str
[KSYM_NAME_LEN
];
511 name
= __get_key_name(class->key
, str
);
515 if (class->name_version
> 1)
516 printk("#%d", class->name_version
);
518 printk("/%d", class->subclass
);
522 static void print_lock_name(struct lock_class
*class)
524 char usage
[LOCK_USAGE_CHARS
];
526 get_usage_chars(class, usage
);
529 __print_lock_name(class);
530 printk("){%s}", usage
);
533 static void print_lockdep_cache(struct lockdep_map
*lock
)
536 char str
[KSYM_NAME_LEN
];
540 name
= __get_key_name(lock
->key
->subkeys
, str
);
545 static void print_lock(struct held_lock
*hlock
)
547 print_lock_name(hlock_class(hlock
));
549 print_ip_sym(hlock
->acquire_ip
);
552 static void lockdep_print_held_locks(struct task_struct
*curr
)
554 int i
, depth
= curr
->lockdep_depth
;
557 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
560 printk("%d lock%s held by %s/%d:\n",
561 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
563 for (i
= 0; i
< depth
; i
++) {
565 print_lock(curr
->held_locks
+ i
);
569 static void print_kernel_ident(void)
571 printk("%s %.*s %s\n", init_utsname()->release
,
572 (int)strcspn(init_utsname()->version
, " "),
573 init_utsname()->version
,
577 static int very_verbose(struct lock_class
*class)
580 return class_filter(class);
586 * Is this the address of a static object:
588 static int static_obj(void *obj
)
590 unsigned long start
= (unsigned long) &_stext
,
591 end
= (unsigned long) &_end
,
592 addr
= (unsigned long) obj
;
597 if ((addr
>= start
) && (addr
< end
))
600 if (arch_is_kernel_data(addr
))
604 * in-kernel percpu var?
606 if (is_kernel_percpu_address(addr
))
610 * module static or percpu var?
612 return is_module_address(addr
) || is_module_percpu_address(addr
);
616 * To make lock name printouts unique, we calculate a unique
617 * class->name_version generation counter:
619 static int count_matching_names(struct lock_class
*new_class
)
621 struct lock_class
*class;
624 if (!new_class
->name
)
627 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
628 if (new_class
->key
- new_class
->subclass
== class->key
)
629 return class->name_version
;
630 if (class->name
&& !strcmp(class->name
, new_class
->name
))
631 count
= max(count
, class->name_version
);
638 * Register a lock's class in the hash-table, if the class is not present
639 * yet. Otherwise we look it up. We cache the result in the lock object
640 * itself, so actual lookup of the hash should be once per lock object.
642 static inline struct lock_class
*
643 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
645 struct lockdep_subclass_key
*key
;
646 struct list_head
*hash_head
;
647 struct lock_class
*class;
649 #ifdef CONFIG_DEBUG_LOCKDEP
651 * If the architecture calls into lockdep before initializing
652 * the hashes then we'll warn about it later. (we cannot printk
655 if (unlikely(!lockdep_initialized
)) {
657 lockdep_init_error
= 1;
658 lock_init_error
= lock
->name
;
659 save_stack_trace(&lockdep_init_trace
);
663 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
666 "BUG: looking up invalid subclass: %u\n", subclass
);
668 "turning off the locking correctness validator.\n");
674 * Static locks do not have their class-keys yet - for them the key
675 * is the lock object itself:
677 if (unlikely(!lock
->key
))
678 lock
->key
= (void *)lock
;
681 * NOTE: the class-key must be unique. For dynamic locks, a static
682 * lock_class_key variable is passed in through the mutex_init()
683 * (or spin_lock_init()) call - which acts as the key. For static
684 * locks we use the lock object itself as the key.
686 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
687 sizeof(struct lockdep_map
));
689 key
= lock
->key
->subkeys
+ subclass
;
691 hash_head
= classhashentry(key
);
694 * We can walk the hash lockfree, because the hash only
695 * grows, and we are careful when adding entries to the end:
697 list_for_each_entry(class, hash_head
, hash_entry
) {
698 if (class->key
== key
) {
700 * Huh! same key, different name? Did someone trample
701 * on some memory? We're most confused.
703 WARN_ON_ONCE(class->name
!= lock
->name
);
712 * Register a lock's class in the hash-table, if the class is not present
713 * yet. Otherwise we look it up. We cache the result in the lock object
714 * itself, so actual lookup of the hash should be once per lock object.
716 static inline struct lock_class
*
717 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
719 struct lockdep_subclass_key
*key
;
720 struct list_head
*hash_head
;
721 struct lock_class
*class;
724 class = look_up_lock_class(lock
, subclass
);
726 goto out_set_class_cache
;
729 * Debug-check: all keys must be persistent!
731 if (!static_obj(lock
->key
)) {
733 printk("INFO: trying to register non-static key.\n");
734 printk("the code is fine but needs lockdep annotation.\n");
735 printk("turning off the locking correctness validator.\n");
741 key
= lock
->key
->subkeys
+ subclass
;
742 hash_head
= classhashentry(key
);
744 raw_local_irq_save(flags
);
746 raw_local_irq_restore(flags
);
750 * We have to do the hash-walk again, to avoid races
753 list_for_each_entry(class, hash_head
, hash_entry
)
754 if (class->key
== key
)
757 * Allocate a new key from the static array, and add it to
760 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
761 if (!debug_locks_off_graph_unlock()) {
762 raw_local_irq_restore(flags
);
765 raw_local_irq_restore(flags
);
767 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
768 printk("turning off the locking correctness validator.\n");
769 printk("Attach output of /proc/lock_stat to bug report\n");
773 class = lock_classes
+ nr_lock_classes
++;
774 debug_atomic_inc(nr_unused_locks
);
776 class->name
= lock
->name
;
777 class->subclass
= subclass
;
778 INIT_LIST_HEAD(&class->lock_entry
);
779 INIT_LIST_HEAD(&class->locks_before
);
780 INIT_LIST_HEAD(&class->locks_after
);
781 class->name_version
= count_matching_names(class);
783 * We use RCU's safe list-add method to make
784 * parallel walking of the hash-list safe:
786 list_add_tail_rcu(&class->hash_entry
, hash_head
);
788 * Add it to the global list of classes:
790 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
792 if (verbose(class)) {
794 raw_local_irq_restore(flags
);
796 printk("\nnew class %p: %s", class->key
, class->name
);
797 if (class->name_version
> 1)
798 printk("#%d", class->name_version
);
802 raw_local_irq_save(flags
);
804 raw_local_irq_restore(flags
);
810 raw_local_irq_restore(flags
);
813 if (!subclass
|| force
)
814 lock
->class_cache
[0] = class;
815 else if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
816 lock
->class_cache
[subclass
] = class;
819 * Hash collision, did we smoke some? We found a class with a matching
820 * hash but the subclass -- which is hashed in -- didn't match.
822 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
828 #ifdef CONFIG_PROVE_LOCKING
830 * Allocate a lockdep entry. (assumes the graph_lock held, returns
831 * with NULL on failure)
833 static struct lock_list
*alloc_list_entry(void)
835 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
836 if (!debug_locks_off_graph_unlock())
839 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
840 printk("turning off the locking correctness validator.\n");
841 printk("Attach output of /proc/lock_stat to bug report\n");
845 return list_entries
+ nr_list_entries
++;
849 * Add a new dependency to the head of the list:
851 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
852 struct list_head
*head
, unsigned long ip
,
853 int distance
, struct stack_trace
*trace
)
855 struct lock_list
*entry
;
857 * Lock not present yet - get a new dependency struct and
858 * add it to the list:
860 entry
= alloc_list_entry();
865 entry
->distance
= distance
;
866 entry
->trace
= *trace
;
868 * Since we never remove from the dependency list, the list can
869 * be walked lockless by other CPUs, it's only allocation
870 * that must be protected by the spinlock. But this also means
871 * we must make new entries visible only once writes to the
872 * entry become visible - hence the RCU op:
874 list_add_tail_rcu(&entry
->entry
, head
);
880 * For good efficiency of modular, we use power of 2
882 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
883 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
886 * The circular_queue and helpers is used to implement the
887 * breadth-first search(BFS)algorithem, by which we can build
888 * the shortest path from the next lock to be acquired to the
889 * previous held lock if there is a circular between them.
891 struct circular_queue
{
892 unsigned long element
[MAX_CIRCULAR_QUEUE_SIZE
];
893 unsigned int front
, rear
;
896 static struct circular_queue lock_cq
;
898 unsigned int max_bfs_queue_depth
;
900 static unsigned int lockdep_dependency_gen_id
;
902 static inline void __cq_init(struct circular_queue
*cq
)
904 cq
->front
= cq
->rear
= 0;
905 lockdep_dependency_gen_id
++;
908 static inline int __cq_empty(struct circular_queue
*cq
)
910 return (cq
->front
== cq
->rear
);
913 static inline int __cq_full(struct circular_queue
*cq
)
915 return ((cq
->rear
+ 1) & CQ_MASK
) == cq
->front
;
918 static inline int __cq_enqueue(struct circular_queue
*cq
, unsigned long elem
)
923 cq
->element
[cq
->rear
] = elem
;
924 cq
->rear
= (cq
->rear
+ 1) & CQ_MASK
;
928 static inline int __cq_dequeue(struct circular_queue
*cq
, unsigned long *elem
)
933 *elem
= cq
->element
[cq
->front
];
934 cq
->front
= (cq
->front
+ 1) & CQ_MASK
;
938 static inline unsigned int __cq_get_elem_count(struct circular_queue
*cq
)
940 return (cq
->rear
- cq
->front
) & CQ_MASK
;
943 static inline void mark_lock_accessed(struct lock_list
*lock
,
944 struct lock_list
*parent
)
948 nr
= lock
- list_entries
;
949 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
950 lock
->parent
= parent
;
951 lock
->class->dep_gen_id
= lockdep_dependency_gen_id
;
954 static inline unsigned long lock_accessed(struct lock_list
*lock
)
958 nr
= lock
- list_entries
;
959 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
960 return lock
->class->dep_gen_id
== lockdep_dependency_gen_id
;
963 static inline struct lock_list
*get_lock_parent(struct lock_list
*child
)
965 return child
->parent
;
968 static inline int get_lock_depth(struct lock_list
*child
)
971 struct lock_list
*parent
;
973 while ((parent
= get_lock_parent(child
))) {
980 static int __bfs(struct lock_list
*source_entry
,
982 int (*match
)(struct lock_list
*entry
, void *data
),
983 struct lock_list
**target_entry
,
986 struct lock_list
*entry
;
987 struct list_head
*head
;
988 struct circular_queue
*cq
= &lock_cq
;
991 if (match(source_entry
, data
)) {
992 *target_entry
= source_entry
;
998 head
= &source_entry
->class->locks_after
;
1000 head
= &source_entry
->class->locks_before
;
1002 if (list_empty(head
))
1006 __cq_enqueue(cq
, (unsigned long)source_entry
);
1008 while (!__cq_empty(cq
)) {
1009 struct lock_list
*lock
;
1011 __cq_dequeue(cq
, (unsigned long *)&lock
);
1019 head
= &lock
->class->locks_after
;
1021 head
= &lock
->class->locks_before
;
1023 list_for_each_entry(entry
, head
, entry
) {
1024 if (!lock_accessed(entry
)) {
1025 unsigned int cq_depth
;
1026 mark_lock_accessed(entry
, lock
);
1027 if (match(entry
, data
)) {
1028 *target_entry
= entry
;
1033 if (__cq_enqueue(cq
, (unsigned long)entry
)) {
1037 cq_depth
= __cq_get_elem_count(cq
);
1038 if (max_bfs_queue_depth
< cq_depth
)
1039 max_bfs_queue_depth
= cq_depth
;
1047 static inline int __bfs_forwards(struct lock_list
*src_entry
,
1049 int (*match
)(struct lock_list
*entry
, void *data
),
1050 struct lock_list
**target_entry
)
1052 return __bfs(src_entry
, data
, match
, target_entry
, 1);
1056 static inline int __bfs_backwards(struct lock_list
*src_entry
,
1058 int (*match
)(struct lock_list
*entry
, void *data
),
1059 struct lock_list
**target_entry
)
1061 return __bfs(src_entry
, data
, match
, target_entry
, 0);
1066 * Recursive, forwards-direction lock-dependency checking, used for
1067 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1072 * Print a dependency chain entry (this is only done when a deadlock
1073 * has been detected):
1076 print_circular_bug_entry(struct lock_list
*target
, int depth
)
1078 if (debug_locks_silent
)
1080 printk("\n-> #%u", depth
);
1081 print_lock_name(target
->class);
1083 print_stack_trace(&target
->trace
, 6);
1089 print_circular_lock_scenario(struct held_lock
*src
,
1090 struct held_lock
*tgt
,
1091 struct lock_list
*prt
)
1093 struct lock_class
*source
= hlock_class(src
);
1094 struct lock_class
*target
= hlock_class(tgt
);
1095 struct lock_class
*parent
= prt
->class;
1098 * A direct locking problem where unsafe_class lock is taken
1099 * directly by safe_class lock, then all we need to show
1100 * is the deadlock scenario, as it is obvious that the
1101 * unsafe lock is taken under the safe lock.
1103 * But if there is a chain instead, where the safe lock takes
1104 * an intermediate lock (middle_class) where this lock is
1105 * not the same as the safe lock, then the lock chain is
1106 * used to describe the problem. Otherwise we would need
1107 * to show a different CPU case for each link in the chain
1108 * from the safe_class lock to the unsafe_class lock.
1110 if (parent
!= source
) {
1111 printk("Chain exists of:\n ");
1112 __print_lock_name(source
);
1114 __print_lock_name(parent
);
1116 __print_lock_name(target
);
1120 printk(" Possible unsafe locking scenario:\n\n");
1121 printk(" CPU0 CPU1\n");
1122 printk(" ---- ----\n");
1124 __print_lock_name(target
);
1127 __print_lock_name(parent
);
1130 __print_lock_name(target
);
1133 __print_lock_name(source
);
1135 printk("\n *** DEADLOCK ***\n\n");
1139 * When a circular dependency is detected, print the
1143 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
,
1144 struct held_lock
*check_src
,
1145 struct held_lock
*check_tgt
)
1147 struct task_struct
*curr
= current
;
1149 if (debug_locks_silent
)
1153 printk("======================================================\n");
1154 printk("[ INFO: possible circular locking dependency detected ]\n");
1155 print_kernel_ident();
1156 printk("-------------------------------------------------------\n");
1157 printk("%s/%d is trying to acquire lock:\n",
1158 curr
->comm
, task_pid_nr(curr
));
1159 print_lock(check_src
);
1160 printk("\nbut task is already holding lock:\n");
1161 print_lock(check_tgt
);
1162 printk("\nwhich lock already depends on the new lock.\n\n");
1163 printk("\nthe existing dependency chain (in reverse order) is:\n");
1165 print_circular_bug_entry(entry
, depth
);
1170 static inline int class_equal(struct lock_list
*entry
, void *data
)
1172 return entry
->class == data
;
1175 static noinline
int print_circular_bug(struct lock_list
*this,
1176 struct lock_list
*target
,
1177 struct held_lock
*check_src
,
1178 struct held_lock
*check_tgt
)
1180 struct task_struct
*curr
= current
;
1181 struct lock_list
*parent
;
1182 struct lock_list
*first_parent
;
1185 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1188 if (!save_trace(&this->trace
))
1191 depth
= get_lock_depth(target
);
1193 print_circular_bug_header(target
, depth
, check_src
, check_tgt
);
1195 parent
= get_lock_parent(target
);
1196 first_parent
= parent
;
1199 print_circular_bug_entry(parent
, --depth
);
1200 parent
= get_lock_parent(parent
);
1203 printk("\nother info that might help us debug this:\n\n");
1204 print_circular_lock_scenario(check_src
, check_tgt
,
1207 lockdep_print_held_locks(curr
);
1209 printk("\nstack backtrace:\n");
1215 static noinline
int print_bfs_bug(int ret
)
1217 if (!debug_locks_off_graph_unlock())
1221 * Breadth-first-search failed, graph got corrupted?
1223 WARN(1, "lockdep bfs error:%d\n", ret
);
1228 static int noop_count(struct lock_list
*entry
, void *data
)
1230 (*(unsigned long *)data
)++;
1234 unsigned long __lockdep_count_forward_deps(struct lock_list
*this)
1236 unsigned long count
= 0;
1237 struct lock_list
*uninitialized_var(target_entry
);
1239 __bfs_forwards(this, (void *)&count
, noop_count
, &target_entry
);
1243 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1245 unsigned long ret
, flags
;
1246 struct lock_list
this;
1251 local_irq_save(flags
);
1252 arch_spin_lock(&lockdep_lock
);
1253 ret
= __lockdep_count_forward_deps(&this);
1254 arch_spin_unlock(&lockdep_lock
);
1255 local_irq_restore(flags
);
1260 unsigned long __lockdep_count_backward_deps(struct lock_list
*this)
1262 unsigned long count
= 0;
1263 struct lock_list
*uninitialized_var(target_entry
);
1265 __bfs_backwards(this, (void *)&count
, noop_count
, &target_entry
);
1270 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1272 unsigned long ret
, flags
;
1273 struct lock_list
this;
1278 local_irq_save(flags
);
1279 arch_spin_lock(&lockdep_lock
);
1280 ret
= __lockdep_count_backward_deps(&this);
1281 arch_spin_unlock(&lockdep_lock
);
1282 local_irq_restore(flags
);
1288 * Prove that the dependency graph starting at <entry> can not
1289 * lead to <target>. Print an error and return 0 if it does.
1292 check_noncircular(struct lock_list
*root
, struct lock_class
*target
,
1293 struct lock_list
**target_entry
)
1297 debug_atomic_inc(nr_cyclic_checks
);
1299 result
= __bfs_forwards(root
, target
, class_equal
, target_entry
);
1304 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1306 * Forwards and backwards subgraph searching, for the purposes of
1307 * proving that two subgraphs can be connected by a new dependency
1308 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1311 static inline int usage_match(struct lock_list
*entry
, void *bit
)
1313 return entry
->class->usage_mask
& (1 << (enum lock_usage_bit
)bit
);
1319 * Find a node in the forwards-direction dependency sub-graph starting
1320 * at @root->class that matches @bit.
1322 * Return 0 if such a node exists in the subgraph, and put that node
1323 * into *@target_entry.
1325 * Return 1 otherwise and keep *@target_entry unchanged.
1326 * Return <0 on error.
1329 find_usage_forwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1330 struct lock_list
**target_entry
)
1334 debug_atomic_inc(nr_find_usage_forwards_checks
);
1336 result
= __bfs_forwards(root
, (void *)bit
, usage_match
, target_entry
);
1342 * Find a node in the backwards-direction dependency sub-graph starting
1343 * at @root->class that matches @bit.
1345 * Return 0 if such a node exists in the subgraph, and put that node
1346 * into *@target_entry.
1348 * Return 1 otherwise and keep *@target_entry unchanged.
1349 * Return <0 on error.
1352 find_usage_backwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1353 struct lock_list
**target_entry
)
1357 debug_atomic_inc(nr_find_usage_backwards_checks
);
1359 result
= __bfs_backwards(root
, (void *)bit
, usage_match
, target_entry
);
1364 static void print_lock_class_header(struct lock_class
*class, int depth
)
1368 printk("%*s->", depth
, "");
1369 print_lock_name(class);
1370 printk(" ops: %lu", class->ops
);
1373 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
1374 if (class->usage_mask
& (1 << bit
)) {
1377 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
1378 len
+= printk(" at:\n");
1379 print_stack_trace(class->usage_traces
+ bit
, len
);
1382 printk("%*s }\n", depth
, "");
1384 printk("%*s ... key at: ",depth
,"");
1385 print_ip_sym((unsigned long)class->key
);
1389 * printk the shortest lock dependencies from @start to @end in reverse order:
1392 print_shortest_lock_dependencies(struct lock_list
*leaf
,
1393 struct lock_list
*root
)
1395 struct lock_list
*entry
= leaf
;
1398 /*compute depth from generated tree by BFS*/
1399 depth
= get_lock_depth(leaf
);
1402 print_lock_class_header(entry
->class, depth
);
1403 printk("%*s ... acquired at:\n", depth
, "");
1404 print_stack_trace(&entry
->trace
, 2);
1407 if (depth
== 0 && (entry
!= root
)) {
1408 printk("lockdep:%s bad path found in chain graph\n", __func__
);
1412 entry
= get_lock_parent(entry
);
1414 } while (entry
&& (depth
>= 0));
1420 print_irq_lock_scenario(struct lock_list
*safe_entry
,
1421 struct lock_list
*unsafe_entry
,
1422 struct lock_class
*prev_class
,
1423 struct lock_class
*next_class
)
1425 struct lock_class
*safe_class
= safe_entry
->class;
1426 struct lock_class
*unsafe_class
= unsafe_entry
->class;
1427 struct lock_class
*middle_class
= prev_class
;
1429 if (middle_class
== safe_class
)
1430 middle_class
= next_class
;
1433 * A direct locking problem where unsafe_class lock is taken
1434 * directly by safe_class lock, then all we need to show
1435 * is the deadlock scenario, as it is obvious that the
1436 * unsafe lock is taken under the safe lock.
1438 * But if there is a chain instead, where the safe lock takes
1439 * an intermediate lock (middle_class) where this lock is
1440 * not the same as the safe lock, then the lock chain is
1441 * used to describe the problem. Otherwise we would need
1442 * to show a different CPU case for each link in the chain
1443 * from the safe_class lock to the unsafe_class lock.
1445 if (middle_class
!= unsafe_class
) {
1446 printk("Chain exists of:\n ");
1447 __print_lock_name(safe_class
);
1449 __print_lock_name(middle_class
);
1451 __print_lock_name(unsafe_class
);
1455 printk(" Possible interrupt unsafe locking scenario:\n\n");
1456 printk(" CPU0 CPU1\n");
1457 printk(" ---- ----\n");
1459 __print_lock_name(unsafe_class
);
1461 printk(" local_irq_disable();\n");
1463 __print_lock_name(safe_class
);
1466 __print_lock_name(middle_class
);
1468 printk(" <Interrupt>\n");
1470 __print_lock_name(safe_class
);
1472 printk("\n *** DEADLOCK ***\n\n");
1476 print_bad_irq_dependency(struct task_struct
*curr
,
1477 struct lock_list
*prev_root
,
1478 struct lock_list
*next_root
,
1479 struct lock_list
*backwards_entry
,
1480 struct lock_list
*forwards_entry
,
1481 struct held_lock
*prev
,
1482 struct held_lock
*next
,
1483 enum lock_usage_bit bit1
,
1484 enum lock_usage_bit bit2
,
1485 const char *irqclass
)
1487 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1491 printk("======================================================\n");
1492 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1493 irqclass
, irqclass
);
1494 print_kernel_ident();
1495 printk("------------------------------------------------------\n");
1496 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1497 curr
->comm
, task_pid_nr(curr
),
1498 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1499 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1500 curr
->hardirqs_enabled
,
1501 curr
->softirqs_enabled
);
1504 printk("\nand this task is already holding:\n");
1506 printk("which would create a new lock dependency:\n");
1507 print_lock_name(hlock_class(prev
));
1509 print_lock_name(hlock_class(next
));
1512 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1514 print_lock_name(backwards_entry
->class);
1515 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1517 print_stack_trace(backwards_entry
->class->usage_traces
+ bit1
, 1);
1519 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1520 print_lock_name(forwards_entry
->class);
1521 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1524 print_stack_trace(forwards_entry
->class->usage_traces
+ bit2
, 1);
1526 printk("\nother info that might help us debug this:\n\n");
1527 print_irq_lock_scenario(backwards_entry
, forwards_entry
,
1528 hlock_class(prev
), hlock_class(next
));
1530 lockdep_print_held_locks(curr
);
1532 printk("\nthe dependencies between %s-irq-safe lock", irqclass
);
1533 printk(" and the holding lock:\n");
1534 if (!save_trace(&prev_root
->trace
))
1536 print_shortest_lock_dependencies(backwards_entry
, prev_root
);
1538 printk("\nthe dependencies between the lock to be acquired");
1539 printk(" and %s-irq-unsafe lock:\n", irqclass
);
1540 if (!save_trace(&next_root
->trace
))
1542 print_shortest_lock_dependencies(forwards_entry
, next_root
);
1544 printk("\nstack backtrace:\n");
1551 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1552 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1553 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1556 struct lock_list
this, that
;
1557 struct lock_list
*uninitialized_var(target_entry
);
1558 struct lock_list
*uninitialized_var(target_entry1
);
1562 this.class = hlock_class(prev
);
1563 ret
= find_usage_backwards(&this, bit_backwards
, &target_entry
);
1565 return print_bfs_bug(ret
);
1570 that
.class = hlock_class(next
);
1571 ret
= find_usage_forwards(&that
, bit_forwards
, &target_entry1
);
1573 return print_bfs_bug(ret
);
1577 return print_bad_irq_dependency(curr
, &this, &that
,
1578 target_entry
, target_entry1
,
1580 bit_backwards
, bit_forwards
, irqclass
);
1583 static const char *state_names
[] = {
1584 #define LOCKDEP_STATE(__STATE) \
1585 __stringify(__STATE),
1586 #include "lockdep_states.h"
1587 #undef LOCKDEP_STATE
1590 static const char *state_rnames
[] = {
1591 #define LOCKDEP_STATE(__STATE) \
1592 __stringify(__STATE)"-READ",
1593 #include "lockdep_states.h"
1594 #undef LOCKDEP_STATE
1597 static inline const char *state_name(enum lock_usage_bit bit
)
1599 return (bit
& 1) ? state_rnames
[bit
>> 2] : state_names
[bit
>> 2];
1602 static int exclusive_bit(int new_bit
)
1610 * bit 0 - write/read
1611 * bit 1 - used_in/enabled
1615 int state
= new_bit
& ~3;
1616 int dir
= new_bit
& 2;
1619 * keep state, bit flip the direction and strip read.
1621 return state
| (dir
^ 2);
1624 static int check_irq_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1625 struct held_lock
*next
, enum lock_usage_bit bit
)
1628 * Prove that the new dependency does not connect a hardirq-safe
1629 * lock with a hardirq-unsafe lock - to achieve this we search
1630 * the backwards-subgraph starting at <prev>, and the
1631 * forwards-subgraph starting at <next>:
1633 if (!check_usage(curr
, prev
, next
, bit
,
1634 exclusive_bit(bit
), state_name(bit
)))
1640 * Prove that the new dependency does not connect a hardirq-safe-read
1641 * lock with a hardirq-unsafe lock - to achieve this we search
1642 * the backwards-subgraph starting at <prev>, and the
1643 * forwards-subgraph starting at <next>:
1645 if (!check_usage(curr
, prev
, next
, bit
,
1646 exclusive_bit(bit
), state_name(bit
)))
1653 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1654 struct held_lock
*next
)
1656 #define LOCKDEP_STATE(__STATE) \
1657 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1659 #include "lockdep_states.h"
1660 #undef LOCKDEP_STATE
1665 static void inc_chains(void)
1667 if (current
->hardirq_context
)
1668 nr_hardirq_chains
++;
1670 if (current
->softirq_context
)
1671 nr_softirq_chains
++;
1673 nr_process_chains
++;
1680 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1681 struct held_lock
*next
)
1686 static inline void inc_chains(void)
1688 nr_process_chains
++;
1694 print_deadlock_scenario(struct held_lock
*nxt
,
1695 struct held_lock
*prv
)
1697 struct lock_class
*next
= hlock_class(nxt
);
1698 struct lock_class
*prev
= hlock_class(prv
);
1700 printk(" Possible unsafe locking scenario:\n\n");
1704 __print_lock_name(prev
);
1707 __print_lock_name(next
);
1709 printk("\n *** DEADLOCK ***\n\n");
1710 printk(" May be due to missing lock nesting notation\n\n");
1714 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1715 struct held_lock
*next
)
1717 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1721 printk("=============================================\n");
1722 printk("[ INFO: possible recursive locking detected ]\n");
1723 print_kernel_ident();
1724 printk("---------------------------------------------\n");
1725 printk("%s/%d is trying to acquire lock:\n",
1726 curr
->comm
, task_pid_nr(curr
));
1728 printk("\nbut task is already holding lock:\n");
1731 printk("\nother info that might help us debug this:\n");
1732 print_deadlock_scenario(next
, prev
);
1733 lockdep_print_held_locks(curr
);
1735 printk("\nstack backtrace:\n");
1742 * Check whether we are holding such a class already.
1744 * (Note that this has to be done separately, because the graph cannot
1745 * detect such classes of deadlocks.)
1747 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1750 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1751 struct lockdep_map
*next_instance
, int read
)
1753 struct held_lock
*prev
;
1754 struct held_lock
*nest
= NULL
;
1757 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1758 prev
= curr
->held_locks
+ i
;
1760 if (prev
->instance
== next
->nest_lock
)
1763 if (hlock_class(prev
) != hlock_class(next
))
1767 * Allow read-after-read recursion of the same
1768 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1770 if ((read
== 2) && prev
->read
)
1774 * We're holding the nest_lock, which serializes this lock's
1775 * nesting behaviour.
1780 return print_deadlock_bug(curr
, prev
, next
);
1786 * There was a chain-cache miss, and we are about to add a new dependency
1787 * to a previous lock. We recursively validate the following rules:
1789 * - would the adding of the <prev> -> <next> dependency create a
1790 * circular dependency in the graph? [== circular deadlock]
1792 * - does the new prev->next dependency connect any hardirq-safe lock
1793 * (in the full backwards-subgraph starting at <prev>) with any
1794 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1795 * <next>)? [== illegal lock inversion with hardirq contexts]
1797 * - does the new prev->next dependency connect any softirq-safe lock
1798 * (in the full backwards-subgraph starting at <prev>) with any
1799 * softirq-unsafe lock (in the full forwards-subgraph starting at
1800 * <next>)? [== illegal lock inversion with softirq contexts]
1802 * any of these scenarios could lead to a deadlock.
1804 * Then if all the validations pass, we add the forwards and backwards
1808 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1809 struct held_lock
*next
, int distance
, int trylock_loop
)
1811 struct lock_list
*entry
;
1813 struct lock_list
this;
1814 struct lock_list
*uninitialized_var(target_entry
);
1816 * Static variable, serialized by the graph_lock().
1818 * We use this static variable to save the stack trace in case
1819 * we call into this function multiple times due to encountering
1820 * trylocks in the held lock stack.
1822 static struct stack_trace trace
;
1825 * Prove that the new <prev> -> <next> dependency would not
1826 * create a circular dependency in the graph. (We do this by
1827 * forward-recursing into the graph starting at <next>, and
1828 * checking whether we can reach <prev>.)
1830 * We are using global variables to control the recursion, to
1831 * keep the stackframe size of the recursive functions low:
1833 this.class = hlock_class(next
);
1835 ret
= check_noncircular(&this, hlock_class(prev
), &target_entry
);
1837 return print_circular_bug(&this, target_entry
, next
, prev
);
1838 else if (unlikely(ret
< 0))
1839 return print_bfs_bug(ret
);
1841 if (!check_prev_add_irq(curr
, prev
, next
))
1845 * For recursive read-locks we do all the dependency checks,
1846 * but we dont store read-triggered dependencies (only
1847 * write-triggered dependencies). This ensures that only the
1848 * write-side dependencies matter, and that if for example a
1849 * write-lock never takes any other locks, then the reads are
1850 * equivalent to a NOP.
1852 if (next
->read
== 2 || prev
->read
== 2)
1855 * Is the <prev> -> <next> dependency already present?
1857 * (this may occur even though this is a new chain: consider
1858 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1859 * chains - the second one will be new, but L1 already has
1860 * L2 added to its dependency list, due to the first chain.)
1862 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1863 if (entry
->class == hlock_class(next
)) {
1865 entry
->distance
= 1;
1870 if (!trylock_loop
&& !save_trace(&trace
))
1874 * Ok, all validations passed, add the new lock
1875 * to the previous lock's dependency list:
1877 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1878 &hlock_class(prev
)->locks_after
,
1879 next
->acquire_ip
, distance
, &trace
);
1884 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1885 &hlock_class(next
)->locks_before
,
1886 next
->acquire_ip
, distance
, &trace
);
1891 * Debugging printouts:
1893 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1895 printk("\n new dependency: ");
1896 print_lock_name(hlock_class(prev
));
1898 print_lock_name(hlock_class(next
));
1901 return graph_lock();
1907 * Add the dependency to all directly-previous locks that are 'relevant'.
1908 * The ones that are relevant are (in increasing distance from curr):
1909 * all consecutive trylock entries and the final non-trylock entry - or
1910 * the end of this context's lock-chain - whichever comes first.
1913 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1915 int depth
= curr
->lockdep_depth
;
1916 int trylock_loop
= 0;
1917 struct held_lock
*hlock
;
1922 * Depth must not be zero for a non-head lock:
1927 * At least two relevant locks must exist for this
1930 if (curr
->held_locks
[depth
].irq_context
!=
1931 curr
->held_locks
[depth
-1].irq_context
)
1935 int distance
= curr
->lockdep_depth
- depth
+ 1;
1936 hlock
= curr
->held_locks
+ depth
-1;
1938 * Only non-recursive-read entries get new dependencies
1941 if (hlock
->read
!= 2) {
1942 if (!check_prev_add(curr
, hlock
, next
,
1943 distance
, trylock_loop
))
1946 * Stop after the first non-trylock entry,
1947 * as non-trylock entries have added their
1948 * own direct dependencies already, so this
1949 * lock is connected to them indirectly:
1951 if (!hlock
->trylock
)
1956 * End of lock-stack?
1961 * Stop the search if we cross into another context:
1963 if (curr
->held_locks
[depth
].irq_context
!=
1964 curr
->held_locks
[depth
-1].irq_context
)
1970 if (!debug_locks_off_graph_unlock())
1974 * Clearly we all shouldn't be here, but since we made it we
1975 * can reliable say we messed up our state. See the above two
1976 * gotos for reasons why we could possibly end up here.
1983 unsigned long nr_lock_chains
;
1984 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1985 int nr_chain_hlocks
;
1986 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1988 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1990 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1994 * Look up a dependency chain. If the key is not present yet then
1995 * add it and return 1 - in this case the new dependency chain is
1996 * validated. If the key is already hashed, return 0.
1997 * (On return with 1 graph_lock is held.)
1999 static inline int lookup_chain_cache(struct task_struct
*curr
,
2000 struct held_lock
*hlock
,
2003 struct lock_class
*class = hlock_class(hlock
);
2004 struct list_head
*hash_head
= chainhashentry(chain_key
);
2005 struct lock_chain
*chain
;
2006 struct held_lock
*hlock_curr
;
2010 * We might need to take the graph lock, ensure we've got IRQs
2011 * disabled to make this an IRQ-safe lock.. for recursion reasons
2012 * lockdep won't complain about its own locking errors.
2014 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2017 * We can walk it lock-free, because entries only get added
2020 list_for_each_entry(chain
, hash_head
, entry
) {
2021 if (chain
->chain_key
== chain_key
) {
2023 debug_atomic_inc(chain_lookup_hits
);
2024 if (very_verbose(class))
2025 printk("\nhash chain already cached, key: "
2026 "%016Lx tail class: [%p] %s\n",
2027 (unsigned long long)chain_key
,
2028 class->key
, class->name
);
2032 if (very_verbose(class))
2033 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2034 (unsigned long long)chain_key
, class->key
, class->name
);
2036 * Allocate a new chain entry from the static array, and add
2042 * We have to walk the chain again locked - to avoid duplicates:
2044 list_for_each_entry(chain
, hash_head
, entry
) {
2045 if (chain
->chain_key
== chain_key
) {
2050 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
2051 if (!debug_locks_off_graph_unlock())
2054 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2055 printk("turning off the locking correctness validator.\n");
2056 printk("Attach output of /proc/lock_stat to bug report\n");
2060 chain
= lock_chains
+ nr_lock_chains
++;
2061 chain
->chain_key
= chain_key
;
2062 chain
->irq_context
= hlock
->irq_context
;
2063 /* Find the first held_lock of current chain */
2064 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
2065 hlock_curr
= curr
->held_locks
+ i
;
2066 if (hlock_curr
->irq_context
!= hlock
->irq_context
)
2070 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
2071 if (likely(nr_chain_hlocks
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2072 chain
->base
= nr_chain_hlocks
;
2073 nr_chain_hlocks
+= chain
->depth
;
2074 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2075 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
2076 chain_hlocks
[chain
->base
+ j
] = lock_id
;
2078 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
2080 list_add_tail_rcu(&chain
->entry
, hash_head
);
2081 debug_atomic_inc(chain_lookup_misses
);
2087 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
2088 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
2091 * Trylock needs to maintain the stack of held locks, but it
2092 * does not add new dependencies, because trylock can be done
2095 * We look up the chain_key and do the O(N^2) check and update of
2096 * the dependencies only if this is a new dependency chain.
2097 * (If lookup_chain_cache() returns with 1 it acquires
2098 * graph_lock for us)
2100 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
2101 lookup_chain_cache(curr
, hlock
, chain_key
)) {
2103 * Check whether last held lock:
2105 * - is irq-safe, if this lock is irq-unsafe
2106 * - is softirq-safe, if this lock is hardirq-unsafe
2108 * And check whether the new lock's dependency graph
2109 * could lead back to the previous lock.
2111 * any of these scenarios could lead to a deadlock. If
2114 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
2119 * Mark recursive read, as we jump over it when
2120 * building dependencies (just like we jump over
2126 * Add dependency only if this lock is not the head
2127 * of the chain, and if it's not a secondary read-lock:
2129 if (!chain_head
&& ret
!= 2)
2130 if (!check_prevs_add(curr
, hlock
))
2134 /* after lookup_chain_cache(): */
2135 if (unlikely(!debug_locks
))
2141 static inline int validate_chain(struct task_struct
*curr
,
2142 struct lockdep_map
*lock
, struct held_lock
*hlock
,
2143 int chain_head
, u64 chain_key
)
2150 * We are building curr_chain_key incrementally, so double-check
2151 * it from scratch, to make sure that it's done correctly:
2153 static void check_chain_key(struct task_struct
*curr
)
2155 #ifdef CONFIG_DEBUG_LOCKDEP
2156 struct held_lock
*hlock
, *prev_hlock
= NULL
;
2160 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2161 hlock
= curr
->held_locks
+ i
;
2162 if (chain_key
!= hlock
->prev_chain_key
) {
2165 * We got mighty confused, our chain keys don't match
2166 * with what we expect, someone trample on our task state?
2168 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2169 curr
->lockdep_depth
, i
,
2170 (unsigned long long)chain_key
,
2171 (unsigned long long)hlock
->prev_chain_key
);
2174 id
= hlock
->class_idx
- 1;
2176 * Whoops ran out of static storage again?
2178 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2181 if (prev_hlock
&& (prev_hlock
->irq_context
!=
2182 hlock
->irq_context
))
2184 chain_key
= iterate_chain_key(chain_key
, id
);
2187 if (chain_key
!= curr
->curr_chain_key
) {
2190 * More smoking hash instead of calculating it, damn see these
2191 * numbers float.. I bet that a pink elephant stepped on my memory.
2193 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2194 curr
->lockdep_depth
, i
,
2195 (unsigned long long)chain_key
,
2196 (unsigned long long)curr
->curr_chain_key
);
2202 print_usage_bug_scenario(struct held_lock
*lock
)
2204 struct lock_class
*class = hlock_class(lock
);
2206 printk(" Possible unsafe locking scenario:\n\n");
2210 __print_lock_name(class);
2212 printk(" <Interrupt>\n");
2214 __print_lock_name(class);
2216 printk("\n *** DEADLOCK ***\n\n");
2220 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
2221 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
2223 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2227 printk("=================================\n");
2228 printk("[ INFO: inconsistent lock state ]\n");
2229 print_kernel_ident();
2230 printk("---------------------------------\n");
2232 printk("inconsistent {%s} -> {%s} usage.\n",
2233 usage_str
[prev_bit
], usage_str
[new_bit
]);
2235 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2236 curr
->comm
, task_pid_nr(curr
),
2237 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
2238 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
2239 trace_hardirqs_enabled(curr
),
2240 trace_softirqs_enabled(curr
));
2243 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
2244 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
2246 print_irqtrace_events(curr
);
2247 printk("\nother info that might help us debug this:\n");
2248 print_usage_bug_scenario(this);
2250 lockdep_print_held_locks(curr
);
2252 printk("\nstack backtrace:\n");
2259 * Print out an error if an invalid bit is set:
2262 valid_state(struct task_struct
*curr
, struct held_lock
*this,
2263 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
2265 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
2266 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
2270 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2271 enum lock_usage_bit new_bit
);
2273 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2276 * print irq inversion bug:
2279 print_irq_inversion_bug(struct task_struct
*curr
,
2280 struct lock_list
*root
, struct lock_list
*other
,
2281 struct held_lock
*this, int forwards
,
2282 const char *irqclass
)
2284 struct lock_list
*entry
= other
;
2285 struct lock_list
*middle
= NULL
;
2288 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2292 printk("=========================================================\n");
2293 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2294 print_kernel_ident();
2295 printk("---------------------------------------------------------\n");
2296 printk("%s/%d just changed the state of lock:\n",
2297 curr
->comm
, task_pid_nr(curr
));
2300 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass
);
2302 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass
);
2303 print_lock_name(other
->class);
2304 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2306 printk("\nother info that might help us debug this:\n");
2308 /* Find a middle lock (if one exists) */
2309 depth
= get_lock_depth(other
);
2311 if (depth
== 0 && (entry
!= root
)) {
2312 printk("lockdep:%s bad path found in chain graph\n", __func__
);
2316 entry
= get_lock_parent(entry
);
2318 } while (entry
&& entry
!= root
&& (depth
>= 0));
2320 print_irq_lock_scenario(root
, other
,
2321 middle
? middle
->class : root
->class, other
->class);
2323 print_irq_lock_scenario(other
, root
,
2324 middle
? middle
->class : other
->class, root
->class);
2326 lockdep_print_held_locks(curr
);
2328 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2329 if (!save_trace(&root
->trace
))
2331 print_shortest_lock_dependencies(other
, root
);
2333 printk("\nstack backtrace:\n");
2340 * Prove that in the forwards-direction subgraph starting at <this>
2341 * there is no lock matching <mask>:
2344 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
2345 enum lock_usage_bit bit
, const char *irqclass
)
2348 struct lock_list root
;
2349 struct lock_list
*uninitialized_var(target_entry
);
2352 root
.class = hlock_class(this);
2353 ret
= find_usage_forwards(&root
, bit
, &target_entry
);
2355 return print_bfs_bug(ret
);
2359 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2364 * Prove that in the backwards-direction subgraph starting at <this>
2365 * there is no lock matching <mask>:
2368 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
2369 enum lock_usage_bit bit
, const char *irqclass
)
2372 struct lock_list root
;
2373 struct lock_list
*uninitialized_var(target_entry
);
2376 root
.class = hlock_class(this);
2377 ret
= find_usage_backwards(&root
, bit
, &target_entry
);
2379 return print_bfs_bug(ret
);
2383 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2387 void print_irqtrace_events(struct task_struct
*curr
)
2389 printk("irq event stamp: %u\n", curr
->irq_events
);
2390 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
2391 print_ip_sym(curr
->hardirq_enable_ip
);
2392 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
2393 print_ip_sym(curr
->hardirq_disable_ip
);
2394 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
2395 print_ip_sym(curr
->softirq_enable_ip
);
2396 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
2397 print_ip_sym(curr
->softirq_disable_ip
);
2400 static int HARDIRQ_verbose(struct lock_class
*class)
2403 return class_filter(class);
2408 static int SOFTIRQ_verbose(struct lock_class
*class)
2411 return class_filter(class);
2416 static int RECLAIM_FS_verbose(struct lock_class
*class)
2419 return class_filter(class);
2424 #define STRICT_READ_CHECKS 1
2426 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2427 #define LOCKDEP_STATE(__STATE) \
2429 #include "lockdep_states.h"
2430 #undef LOCKDEP_STATE
2433 static inline int state_verbose(enum lock_usage_bit bit
,
2434 struct lock_class
*class)
2436 return state_verbose_f
[bit
>> 2](class);
2439 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2440 enum lock_usage_bit bit
, const char *name
);
2443 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2444 enum lock_usage_bit new_bit
)
2446 int excl_bit
= exclusive_bit(new_bit
);
2447 int read
= new_bit
& 1;
2448 int dir
= new_bit
& 2;
2451 * mark USED_IN has to look forwards -- to ensure no dependency
2452 * has ENABLED state, which would allow recursion deadlocks.
2454 * mark ENABLED has to look backwards -- to ensure no dependee
2455 * has USED_IN state, which, again, would allow recursion deadlocks.
2457 check_usage_f usage
= dir
?
2458 check_usage_backwards
: check_usage_forwards
;
2461 * Validate that this particular lock does not have conflicting
2464 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2468 * Validate that the lock dependencies don't have conflicting usage
2471 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2472 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2476 * Check for read in write conflicts
2479 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2482 if (STRICT_READ_CHECKS
&&
2483 !usage(curr
, this, excl_bit
+ 1,
2484 state_name(new_bit
+ 1)))
2488 if (state_verbose(new_bit
, hlock_class(this)))
2495 #define LOCKDEP_STATE(__STATE) __STATE,
2496 #include "lockdep_states.h"
2497 #undef LOCKDEP_STATE
2501 * Mark all held locks with a usage bit:
2504 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2506 enum lock_usage_bit usage_bit
;
2507 struct held_lock
*hlock
;
2510 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2511 hlock
= curr
->held_locks
+ i
;
2513 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2515 usage_bit
+= 1; /* READ */
2517 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2519 if (hlock_class(hlock
)->key
== __lockdep_no_validate__
.subkeys
)
2522 if (!mark_lock(curr
, hlock
, usage_bit
))
2530 * Hardirqs will be enabled:
2532 static void __trace_hardirqs_on_caller(unsigned long ip
)
2534 struct task_struct
*curr
= current
;
2536 /* we'll do an OFF -> ON transition: */
2537 curr
->hardirqs_enabled
= 1;
2540 * We are going to turn hardirqs on, so set the
2541 * usage bit for all held locks:
2543 if (!mark_held_locks(curr
, HARDIRQ
))
2546 * If we have softirqs enabled, then set the usage
2547 * bit for all held locks. (disabled hardirqs prevented
2548 * this bit from being set before)
2550 if (curr
->softirqs_enabled
)
2551 if (!mark_held_locks(curr
, SOFTIRQ
))
2554 curr
->hardirq_enable_ip
= ip
;
2555 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2556 debug_atomic_inc(hardirqs_on_events
);
2559 void trace_hardirqs_on_caller(unsigned long ip
)
2561 time_hardirqs_on(CALLER_ADDR0
, ip
);
2563 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2566 if (unlikely(current
->hardirqs_enabled
)) {
2568 * Neither irq nor preemption are disabled here
2569 * so this is racy by nature but losing one hit
2570 * in a stat is not a big deal.
2572 __debug_atomic_inc(redundant_hardirqs_on
);
2577 * We're enabling irqs and according to our state above irqs weren't
2578 * already enabled, yet we find the hardware thinks they are in fact
2579 * enabled.. someone messed up their IRQ state tracing.
2581 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2585 * See the fine text that goes along with this variable definition.
2587 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled
)))
2591 * Can't allow enabling interrupts while in an interrupt handler,
2592 * that's general bad form and such. Recursion, limited stack etc..
2594 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2597 current
->lockdep_recursion
= 1;
2598 __trace_hardirqs_on_caller(ip
);
2599 current
->lockdep_recursion
= 0;
2601 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2603 void trace_hardirqs_on(void)
2605 trace_hardirqs_on_caller(CALLER_ADDR0
);
2607 EXPORT_SYMBOL(trace_hardirqs_on
);
2610 * Hardirqs were disabled:
2612 void trace_hardirqs_off_caller(unsigned long ip
)
2614 struct task_struct
*curr
= current
;
2616 time_hardirqs_off(CALLER_ADDR0
, ip
);
2618 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2622 * So we're supposed to get called after you mask local IRQs, but for
2623 * some reason the hardware doesn't quite think you did a proper job.
2625 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2628 if (curr
->hardirqs_enabled
) {
2630 * We have done an ON -> OFF transition:
2632 curr
->hardirqs_enabled
= 0;
2633 curr
->hardirq_disable_ip
= ip
;
2634 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2635 debug_atomic_inc(hardirqs_off_events
);
2637 debug_atomic_inc(redundant_hardirqs_off
);
2639 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2641 void trace_hardirqs_off(void)
2643 trace_hardirqs_off_caller(CALLER_ADDR0
);
2645 EXPORT_SYMBOL(trace_hardirqs_off
);
2648 * Softirqs will be enabled:
2650 void trace_softirqs_on(unsigned long ip
)
2652 struct task_struct
*curr
= current
;
2654 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2658 * We fancy IRQs being disabled here, see softirq.c, avoids
2659 * funny state and nesting things.
2661 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2664 if (curr
->softirqs_enabled
) {
2665 debug_atomic_inc(redundant_softirqs_on
);
2669 current
->lockdep_recursion
= 1;
2671 * We'll do an OFF -> ON transition:
2673 curr
->softirqs_enabled
= 1;
2674 curr
->softirq_enable_ip
= ip
;
2675 curr
->softirq_enable_event
= ++curr
->irq_events
;
2676 debug_atomic_inc(softirqs_on_events
);
2678 * We are going to turn softirqs on, so set the
2679 * usage bit for all held locks, if hardirqs are
2682 if (curr
->hardirqs_enabled
)
2683 mark_held_locks(curr
, SOFTIRQ
);
2684 current
->lockdep_recursion
= 0;
2688 * Softirqs were disabled:
2690 void trace_softirqs_off(unsigned long ip
)
2692 struct task_struct
*curr
= current
;
2694 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2698 * We fancy IRQs being disabled here, see softirq.c
2700 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2703 if (curr
->softirqs_enabled
) {
2705 * We have done an ON -> OFF transition:
2707 curr
->softirqs_enabled
= 0;
2708 curr
->softirq_disable_ip
= ip
;
2709 curr
->softirq_disable_event
= ++curr
->irq_events
;
2710 debug_atomic_inc(softirqs_off_events
);
2712 * Whoops, we wanted softirqs off, so why aren't they?
2714 DEBUG_LOCKS_WARN_ON(!softirq_count());
2716 debug_atomic_inc(redundant_softirqs_off
);
2719 static void __lockdep_trace_alloc(gfp_t gfp_mask
, unsigned long flags
)
2721 struct task_struct
*curr
= current
;
2723 if (unlikely(!debug_locks
))
2726 /* no reclaim without waiting on it */
2727 if (!(gfp_mask
& __GFP_WAIT
))
2730 /* this guy won't enter reclaim */
2731 if ((curr
->flags
& PF_MEMALLOC
) && !(gfp_mask
& __GFP_NOMEMALLOC
))
2734 /* We're only interested __GFP_FS allocations for now */
2735 if (!(gfp_mask
& __GFP_FS
))
2739 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2741 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags
)))
2744 mark_held_locks(curr
, RECLAIM_FS
);
2747 static void check_flags(unsigned long flags
);
2749 void lockdep_trace_alloc(gfp_t gfp_mask
)
2751 unsigned long flags
;
2753 if (unlikely(current
->lockdep_recursion
))
2756 raw_local_irq_save(flags
);
2758 current
->lockdep_recursion
= 1;
2759 __lockdep_trace_alloc(gfp_mask
, flags
);
2760 current
->lockdep_recursion
= 0;
2761 raw_local_irq_restore(flags
);
2764 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2767 * If non-trylock use in a hardirq or softirq context, then
2768 * mark the lock as used in these contexts:
2770 if (!hlock
->trylock
) {
2772 if (curr
->hardirq_context
)
2773 if (!mark_lock(curr
, hlock
,
2774 LOCK_USED_IN_HARDIRQ_READ
))
2776 if (curr
->softirq_context
)
2777 if (!mark_lock(curr
, hlock
,
2778 LOCK_USED_IN_SOFTIRQ_READ
))
2781 if (curr
->hardirq_context
)
2782 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2784 if (curr
->softirq_context
)
2785 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2789 if (!hlock
->hardirqs_off
) {
2791 if (!mark_lock(curr
, hlock
,
2792 LOCK_ENABLED_HARDIRQ_READ
))
2794 if (curr
->softirqs_enabled
)
2795 if (!mark_lock(curr
, hlock
,
2796 LOCK_ENABLED_SOFTIRQ_READ
))
2799 if (!mark_lock(curr
, hlock
,
2800 LOCK_ENABLED_HARDIRQ
))
2802 if (curr
->softirqs_enabled
)
2803 if (!mark_lock(curr
, hlock
,
2804 LOCK_ENABLED_SOFTIRQ
))
2810 * We reuse the irq context infrastructure more broadly as a general
2811 * context checking code. This tests GFP_FS recursion (a lock taken
2812 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2815 if (!hlock
->trylock
&& (curr
->lockdep_reclaim_gfp
& __GFP_FS
)) {
2817 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS_READ
))
2820 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS
))
2828 static int separate_irq_context(struct task_struct
*curr
,
2829 struct held_lock
*hlock
)
2831 unsigned int depth
= curr
->lockdep_depth
;
2834 * Keep track of points where we cross into an interrupt context:
2836 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2837 curr
->softirq_context
;
2839 struct held_lock
*prev_hlock
;
2841 prev_hlock
= curr
->held_locks
+ depth
-1;
2843 * If we cross into another context, reset the
2844 * hash key (this also prevents the checking and the
2845 * adding of the dependency to 'prev'):
2847 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2853 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2856 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2857 enum lock_usage_bit new_bit
)
2859 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2863 static inline int mark_irqflags(struct task_struct
*curr
,
2864 struct held_lock
*hlock
)
2869 static inline int separate_irq_context(struct task_struct
*curr
,
2870 struct held_lock
*hlock
)
2875 void lockdep_trace_alloc(gfp_t gfp_mask
)
2879 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2882 * Mark a lock with a usage bit, and validate the state transition:
2884 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2885 enum lock_usage_bit new_bit
)
2887 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2890 * If already set then do not dirty the cacheline,
2891 * nor do any checks:
2893 if (likely(hlock_class(this)->usage_mask
& new_mask
))
2899 * Make sure we didn't race:
2901 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
2906 hlock_class(this)->usage_mask
|= new_mask
;
2908 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
2912 #define LOCKDEP_STATE(__STATE) \
2913 case LOCK_USED_IN_##__STATE: \
2914 case LOCK_USED_IN_##__STATE##_READ: \
2915 case LOCK_ENABLED_##__STATE: \
2916 case LOCK_ENABLED_##__STATE##_READ:
2917 #include "lockdep_states.h"
2918 #undef LOCKDEP_STATE
2919 ret
= mark_lock_irq(curr
, this, new_bit
);
2924 debug_atomic_dec(nr_unused_locks
);
2927 if (!debug_locks_off_graph_unlock())
2936 * We must printk outside of the graph_lock:
2939 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2941 print_irqtrace_events(curr
);
2949 * Initialize a lock instance's lock-class mapping info:
2951 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2952 struct lock_class_key
*key
, int subclass
)
2956 kmemcheck_mark_initialized(lock
, sizeof(*lock
));
2958 for (i
= 0; i
< NR_LOCKDEP_CACHING_CLASSES
; i
++)
2959 lock
->class_cache
[i
] = NULL
;
2961 #ifdef CONFIG_LOCK_STAT
2962 lock
->cpu
= raw_smp_processor_id();
2966 * Can't be having no nameless bastards around this place!
2968 if (DEBUG_LOCKS_WARN_ON(!name
)) {
2969 lock
->name
= "NULL";
2976 * No key, no joy, we need to hash something.
2978 if (DEBUG_LOCKS_WARN_ON(!key
))
2981 * Sanity check, the lock-class key must be persistent:
2983 if (!static_obj(key
)) {
2984 printk("BUG: key %p not in .data!\n", key
);
2986 * What it says above ^^^^^, I suggest you read it.
2988 DEBUG_LOCKS_WARN_ON(1);
2993 if (unlikely(!debug_locks
))
2997 register_lock_class(lock
, subclass
, 1);
2999 EXPORT_SYMBOL_GPL(lockdep_init_map
);
3001 struct lock_class_key __lockdep_no_validate__
;
3004 print_lock_nested_lock_not_held(struct task_struct
*curr
,
3005 struct held_lock
*hlock
,
3008 if (!debug_locks_off())
3010 if (debug_locks_silent
)
3014 printk("==================================\n");
3015 printk("[ BUG: Nested lock was not taken ]\n");
3016 print_kernel_ident();
3017 printk("----------------------------------\n");
3019 printk("%s/%d is trying to lock:\n", curr
->comm
, task_pid_nr(curr
));
3022 printk("\nbut this task is not holding:\n");
3023 printk("%s\n", hlock
->nest_lock
->name
);
3025 printk("\nstack backtrace:\n");
3028 printk("\nother info that might help us debug this:\n");
3029 lockdep_print_held_locks(curr
);
3031 printk("\nstack backtrace:\n");
3037 static int __lock_is_held(struct lockdep_map
*lock
);
3040 * This gets called for every mutex_lock*()/spin_lock*() operation.
3041 * We maintain the dependency maps and validate the locking attempt:
3043 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3044 int trylock
, int read
, int check
, int hardirqs_off
,
3045 struct lockdep_map
*nest_lock
, unsigned long ip
,
3048 struct task_struct
*curr
= current
;
3049 struct lock_class
*class = NULL
;
3050 struct held_lock
*hlock
;
3051 unsigned int depth
, id
;
3059 if (unlikely(!debug_locks
))
3063 * Lockdep should run with IRQs disabled, otherwise we could
3064 * get an interrupt which would want to take locks, which would
3065 * end up in lockdep and have you got a head-ache already?
3067 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3070 if (lock
->key
== &__lockdep_no_validate__
)
3073 if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
3074 class = lock
->class_cache
[subclass
];
3078 if (unlikely(!class)) {
3079 class = register_lock_class(lock
, subclass
, 0);
3083 atomic_inc((atomic_t
*)&class->ops
);
3084 if (very_verbose(class)) {
3085 printk("\nacquire class [%p] %s", class->key
, class->name
);
3086 if (class->name_version
> 1)
3087 printk("#%d", class->name_version
);
3093 * Add the lock to the list of currently held locks.
3094 * (we dont increase the depth just yet, up until the
3095 * dependency checks are done)
3097 depth
= curr
->lockdep_depth
;
3099 * Ran out of static storage for our per-task lock stack again have we?
3101 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
3104 class_idx
= class - lock_classes
+ 1;
3107 hlock
= curr
->held_locks
+ depth
- 1;
3108 if (hlock
->class_idx
== class_idx
&& nest_lock
) {
3109 if (hlock
->references
)
3110 hlock
->references
++;
3112 hlock
->references
= 2;
3118 hlock
= curr
->held_locks
+ depth
;
3120 * Plain impossible, we just registered it and checked it weren't no
3121 * NULL like.. I bet this mushroom I ate was good!
3123 if (DEBUG_LOCKS_WARN_ON(!class))
3125 hlock
->class_idx
= class_idx
;
3126 hlock
->acquire_ip
= ip
;
3127 hlock
->instance
= lock
;
3128 hlock
->nest_lock
= nest_lock
;
3129 hlock
->trylock
= trylock
;
3131 hlock
->check
= check
;
3132 hlock
->hardirqs_off
= !!hardirqs_off
;
3133 hlock
->references
= references
;
3134 #ifdef CONFIG_LOCK_STAT
3135 hlock
->waittime_stamp
= 0;
3136 hlock
->holdtime_stamp
= lockstat_clock();
3139 if (check
== 2 && !mark_irqflags(curr
, hlock
))
3142 /* mark it as used: */
3143 if (!mark_lock(curr
, hlock
, LOCK_USED
))
3147 * Calculate the chain hash: it's the combined hash of all the
3148 * lock keys along the dependency chain. We save the hash value
3149 * at every step so that we can get the current hash easily
3150 * after unlock. The chain hash is then used to cache dependency
3153 * The 'key ID' is what is the most compact key value to drive
3154 * the hash, not class->key.
3156 id
= class - lock_classes
;
3158 * Whoops, we did it again.. ran straight out of our static allocation.
3160 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
3163 chain_key
= curr
->curr_chain_key
;
3166 * How can we have a chain hash when we ain't got no keys?!
3168 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
3173 hlock
->prev_chain_key
= chain_key
;
3174 if (separate_irq_context(curr
, hlock
)) {
3178 chain_key
= iterate_chain_key(chain_key
, id
);
3180 if (nest_lock
&& !__lock_is_held(nest_lock
))
3181 return print_lock_nested_lock_not_held(curr
, hlock
, ip
);
3183 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
3186 curr
->curr_chain_key
= chain_key
;
3187 curr
->lockdep_depth
++;
3188 check_chain_key(curr
);
3189 #ifdef CONFIG_DEBUG_LOCKDEP
3190 if (unlikely(!debug_locks
))
3193 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
3195 printk("BUG: MAX_LOCK_DEPTH too low, depth: %i max: %lu!\n",
3196 curr
->lockdep_depth
, MAX_LOCK_DEPTH
);
3197 printk("turning off the locking correctness validator.\n");
3198 printk("Attach output of /proc/lock_stat to bug report\n");
3200 lockdep_print_held_locks(current
);
3201 debug_show_all_locks();
3207 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
3208 max_lockdep_depth
= curr
->lockdep_depth
;
3214 print_unlock_imbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3217 if (!debug_locks_off())
3219 if (debug_locks_silent
)
3223 printk("=====================================\n");
3224 printk("[ BUG: bad unlock balance detected! ]\n");
3225 print_kernel_ident();
3226 printk("-------------------------------------\n");
3227 printk("%s/%d is trying to release lock (",
3228 curr
->comm
, task_pid_nr(curr
));
3229 print_lockdep_cache(lock
);
3232 printk("but there are no more locks to release!\n");
3233 printk("\nother info that might help us debug this:\n");
3234 lockdep_print_held_locks(curr
);
3236 printk("\nstack backtrace:\n");
3243 * Common debugging checks for both nested and non-nested unlock:
3245 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
3248 if (unlikely(!debug_locks
))
3251 * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
3253 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3256 if (curr
->lockdep_depth
<= 0)
3257 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3262 static int match_held_lock(struct held_lock
*hlock
, struct lockdep_map
*lock
)
3264 if (hlock
->instance
== lock
)
3267 if (hlock
->references
) {
3268 struct lock_class
*class = lock
->class_cache
[0];
3271 class = look_up_lock_class(lock
, 0);
3274 * If look_up_lock_class() failed to find a class, we're trying
3275 * to test if we hold a lock that has never yet been acquired.
3276 * Clearly if the lock hasn't been acquired _ever_, we're not
3277 * holding it either, so report failure.
3283 * References, but not a lock we're actually ref-counting?
3284 * State got messed up, follow the sites that change ->references
3285 * and try to make sense of it.
3287 if (DEBUG_LOCKS_WARN_ON(!hlock
->nest_lock
))
3290 if (hlock
->class_idx
== class - lock_classes
+ 1)
3298 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
3299 struct lock_class_key
*key
, unsigned int subclass
,
3302 struct task_struct
*curr
= current
;
3303 struct held_lock
*hlock
, *prev_hlock
;
3304 struct lock_class
*class;
3308 depth
= curr
->lockdep_depth
;
3310 * This function is about (re)setting the class of a held lock,
3311 * yet we're not actually holding any locks. Naughty user!
3313 if (DEBUG_LOCKS_WARN_ON(!depth
))
3317 for (i
= depth
-1; i
>= 0; i
--) {
3318 hlock
= curr
->held_locks
+ i
;
3320 * We must not cross into another context:
3322 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3324 if (match_held_lock(hlock
, lock
))
3328 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3331 lockdep_init_map(lock
, name
, key
, 0);
3332 class = register_lock_class(lock
, subclass
, 0);
3333 hlock
->class_idx
= class - lock_classes
+ 1;
3335 curr
->lockdep_depth
= i
;
3336 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3338 for (; i
< depth
; i
++) {
3339 hlock
= curr
->held_locks
+ i
;
3340 if (!__lock_acquire(hlock
->instance
,
3341 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3342 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3343 hlock
->nest_lock
, hlock
->acquire_ip
,
3349 * I took it apart and put it back together again, except now I have
3350 * these 'spare' parts.. where shall I put them.
3352 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
3358 * Remove the lock to the list of currently held locks in a
3359 * potentially non-nested (out of order) manner. This is a
3360 * relatively rare operation, as all the unlock APIs default
3361 * to nested mode (which uses lock_release()):
3364 lock_release_non_nested(struct task_struct
*curr
,
3365 struct lockdep_map
*lock
, unsigned long ip
)
3367 struct held_lock
*hlock
, *prev_hlock
;
3372 * Check whether the lock exists in the current stack
3375 depth
= curr
->lockdep_depth
;
3377 * So we're all set to release this lock.. wait what lock? We don't
3378 * own any locks, you've been drinking again?
3380 if (DEBUG_LOCKS_WARN_ON(!depth
))
3384 for (i
= depth
-1; i
>= 0; i
--) {
3385 hlock
= curr
->held_locks
+ i
;
3387 * We must not cross into another context:
3389 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3391 if (match_held_lock(hlock
, lock
))
3395 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3398 if (hlock
->instance
== lock
)
3399 lock_release_holdtime(hlock
);
3401 if (hlock
->references
) {
3402 hlock
->references
--;
3403 if (hlock
->references
) {
3405 * We had, and after removing one, still have
3406 * references, the current lock stack is still
3407 * valid. We're done!
3414 * We have the right lock to unlock, 'hlock' points to it.
3415 * Now we remove it from the stack, and add back the other
3416 * entries (if any), recalculating the hash along the way:
3419 curr
->lockdep_depth
= i
;
3420 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3422 for (i
++; i
< depth
; i
++) {
3423 hlock
= curr
->held_locks
+ i
;
3424 if (!__lock_acquire(hlock
->instance
,
3425 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3426 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3427 hlock
->nest_lock
, hlock
->acquire_ip
,
3433 * We had N bottles of beer on the wall, we drank one, but now
3434 * there's not N-1 bottles of beer left on the wall...
3436 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
3442 * Remove the lock to the list of currently held locks - this gets
3443 * called on mutex_unlock()/spin_unlock*() (or on a failed
3444 * mutex_lock_interruptible()). This is done for unlocks that nest
3445 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3447 static int lock_release_nested(struct task_struct
*curr
,
3448 struct lockdep_map
*lock
, unsigned long ip
)
3450 struct held_lock
*hlock
;
3454 * Pop off the top of the lock stack:
3456 depth
= curr
->lockdep_depth
- 1;
3457 hlock
= curr
->held_locks
+ depth
;
3460 * Is the unlock non-nested:
3462 if (hlock
->instance
!= lock
|| hlock
->references
)
3463 return lock_release_non_nested(curr
, lock
, ip
);
3464 curr
->lockdep_depth
--;
3467 * No more locks, but somehow we've got hash left over, who left it?
3469 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
3472 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3474 lock_release_holdtime(hlock
);
3476 #ifdef CONFIG_DEBUG_LOCKDEP
3477 hlock
->prev_chain_key
= 0;
3478 hlock
->class_idx
= 0;
3479 hlock
->acquire_ip
= 0;
3480 hlock
->irq_context
= 0;
3486 * Remove the lock to the list of currently held locks - this gets
3487 * called on mutex_unlock()/spin_unlock*() (or on a failed
3488 * mutex_lock_interruptible()). This is done for unlocks that nest
3489 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3492 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
3494 struct task_struct
*curr
= current
;
3496 if (!check_unlock(curr
, lock
, ip
))
3500 if (!lock_release_nested(curr
, lock
, ip
))
3503 if (!lock_release_non_nested(curr
, lock
, ip
))
3507 check_chain_key(curr
);
3510 static int __lock_is_held(struct lockdep_map
*lock
)
3512 struct task_struct
*curr
= current
;
3515 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3516 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3518 if (match_held_lock(hlock
, lock
))
3526 * Check whether we follow the irq-flags state precisely:
3528 static void check_flags(unsigned long flags
)
3530 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3531 defined(CONFIG_TRACE_IRQFLAGS)
3535 if (irqs_disabled_flags(flags
)) {
3536 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
3537 printk("possible reason: unannotated irqs-off.\n");
3540 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
3541 printk("possible reason: unannotated irqs-on.\n");
3546 * We dont accurately track softirq state in e.g.
3547 * hardirq contexts (such as on 4KSTACKS), so only
3548 * check if not in hardirq contexts:
3550 if (!hardirq_count()) {
3551 if (softirq_count()) {
3552 /* like the above, but with softirqs */
3553 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
3555 /* lick the above, does it taste good? */
3556 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
3561 print_irqtrace_events(current
);
3565 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
3566 struct lock_class_key
*key
, unsigned int subclass
,
3569 unsigned long flags
;
3571 if (unlikely(current
->lockdep_recursion
))
3574 raw_local_irq_save(flags
);
3575 current
->lockdep_recursion
= 1;
3577 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
3578 check_chain_key(current
);
3579 current
->lockdep_recursion
= 0;
3580 raw_local_irq_restore(flags
);
3582 EXPORT_SYMBOL_GPL(lock_set_class
);
3585 * We are not always called with irqs disabled - do that here,
3586 * and also avoid lockdep recursion:
3588 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3589 int trylock
, int read
, int check
,
3590 struct lockdep_map
*nest_lock
, unsigned long ip
)
3592 unsigned long flags
;
3594 if (unlikely(current
->lockdep_recursion
))
3597 raw_local_irq_save(flags
);
3600 current
->lockdep_recursion
= 1;
3601 trace_lock_acquire(lock
, subclass
, trylock
, read
, check
, nest_lock
, ip
);
3602 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
3603 irqs_disabled_flags(flags
), nest_lock
, ip
, 0);
3604 current
->lockdep_recursion
= 0;
3605 raw_local_irq_restore(flags
);
3607 EXPORT_SYMBOL_GPL(lock_acquire
);
3609 void lock_release(struct lockdep_map
*lock
, int nested
,
3612 unsigned long flags
;
3614 if (unlikely(current
->lockdep_recursion
))
3617 raw_local_irq_save(flags
);
3619 current
->lockdep_recursion
= 1;
3620 trace_lock_release(lock
, ip
);
3621 __lock_release(lock
, nested
, ip
);
3622 current
->lockdep_recursion
= 0;
3623 raw_local_irq_restore(flags
);
3625 EXPORT_SYMBOL_GPL(lock_release
);
3627 int lock_is_held(struct lockdep_map
*lock
)
3629 unsigned long flags
;
3632 if (unlikely(current
->lockdep_recursion
))
3633 return 1; /* avoid false negative lockdep_assert_held() */
3635 raw_local_irq_save(flags
);
3638 current
->lockdep_recursion
= 1;
3639 ret
= __lock_is_held(lock
);
3640 current
->lockdep_recursion
= 0;
3641 raw_local_irq_restore(flags
);
3645 EXPORT_SYMBOL_GPL(lock_is_held
);
3647 void lockdep_set_current_reclaim_state(gfp_t gfp_mask
)
3649 current
->lockdep_reclaim_gfp
= gfp_mask
;
3652 void lockdep_clear_current_reclaim_state(void)
3654 current
->lockdep_reclaim_gfp
= 0;
3657 #ifdef CONFIG_LOCK_STAT
3659 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3662 if (!debug_locks_off())
3664 if (debug_locks_silent
)
3668 printk("=================================\n");
3669 printk("[ BUG: bad contention detected! ]\n");
3670 print_kernel_ident();
3671 printk("---------------------------------\n");
3672 printk("%s/%d is trying to contend lock (",
3673 curr
->comm
, task_pid_nr(curr
));
3674 print_lockdep_cache(lock
);
3677 printk("but there are no locks held!\n");
3678 printk("\nother info that might help us debug this:\n");
3679 lockdep_print_held_locks(curr
);
3681 printk("\nstack backtrace:\n");
3688 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3690 struct task_struct
*curr
= current
;
3691 struct held_lock
*hlock
, *prev_hlock
;
3692 struct lock_class_stats
*stats
;
3694 int i
, contention_point
, contending_point
;
3696 depth
= curr
->lockdep_depth
;
3698 * Whee, we contended on this lock, except it seems we're not
3699 * actually trying to acquire anything much at all..
3701 if (DEBUG_LOCKS_WARN_ON(!depth
))
3705 for (i
= depth
-1; i
>= 0; i
--) {
3706 hlock
= curr
->held_locks
+ i
;
3708 * We must not cross into another context:
3710 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3712 if (match_held_lock(hlock
, lock
))
3716 print_lock_contention_bug(curr
, lock
, ip
);
3720 if (hlock
->instance
!= lock
)
3723 hlock
->waittime_stamp
= lockstat_clock();
3725 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3726 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3729 stats
= get_lock_stats(hlock_class(hlock
));
3730 if (contention_point
< LOCKSTAT_POINTS
)
3731 stats
->contention_point
[contention_point
]++;
3732 if (contending_point
< LOCKSTAT_POINTS
)
3733 stats
->contending_point
[contending_point
]++;
3734 if (lock
->cpu
!= smp_processor_id())
3735 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3736 put_lock_stats(stats
);
3740 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3742 struct task_struct
*curr
= current
;
3743 struct held_lock
*hlock
, *prev_hlock
;
3744 struct lock_class_stats
*stats
;
3746 u64 now
, waittime
= 0;
3749 depth
= curr
->lockdep_depth
;
3751 * Yay, we acquired ownership of this lock we didn't try to
3752 * acquire, how the heck did that happen?
3754 if (DEBUG_LOCKS_WARN_ON(!depth
))
3758 for (i
= depth
-1; i
>= 0; i
--) {
3759 hlock
= curr
->held_locks
+ i
;
3761 * We must not cross into another context:
3763 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3765 if (match_held_lock(hlock
, lock
))
3769 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3773 if (hlock
->instance
!= lock
)
3776 cpu
= smp_processor_id();
3777 if (hlock
->waittime_stamp
) {
3778 now
= lockstat_clock();
3779 waittime
= now
- hlock
->waittime_stamp
;
3780 hlock
->holdtime_stamp
= now
;
3783 trace_lock_acquired(lock
, ip
);
3785 stats
= get_lock_stats(hlock_class(hlock
));
3788 lock_time_inc(&stats
->read_waittime
, waittime
);
3790 lock_time_inc(&stats
->write_waittime
, waittime
);
3792 if (lock
->cpu
!= cpu
)
3793 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3794 put_lock_stats(stats
);
3800 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3802 unsigned long flags
;
3804 if (unlikely(!lock_stat
))
3807 if (unlikely(current
->lockdep_recursion
))
3810 raw_local_irq_save(flags
);
3812 current
->lockdep_recursion
= 1;
3813 trace_lock_contended(lock
, ip
);
3814 __lock_contended(lock
, ip
);
3815 current
->lockdep_recursion
= 0;
3816 raw_local_irq_restore(flags
);
3818 EXPORT_SYMBOL_GPL(lock_contended
);
3820 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3822 unsigned long flags
;
3824 if (unlikely(!lock_stat
))
3827 if (unlikely(current
->lockdep_recursion
))
3830 raw_local_irq_save(flags
);
3832 current
->lockdep_recursion
= 1;
3833 __lock_acquired(lock
, ip
);
3834 current
->lockdep_recursion
= 0;
3835 raw_local_irq_restore(flags
);
3837 EXPORT_SYMBOL_GPL(lock_acquired
);
3841 * Used by the testsuite, sanitize the validator state
3842 * after a simulated failure:
3845 void lockdep_reset(void)
3847 unsigned long flags
;
3850 raw_local_irq_save(flags
);
3851 current
->curr_chain_key
= 0;
3852 current
->lockdep_depth
= 0;
3853 current
->lockdep_recursion
= 0;
3854 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3855 nr_hardirq_chains
= 0;
3856 nr_softirq_chains
= 0;
3857 nr_process_chains
= 0;
3859 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3860 INIT_LIST_HEAD(chainhash_table
+ i
);
3861 raw_local_irq_restore(flags
);
3864 static void zap_class(struct lock_class
*class)
3869 * Remove all dependencies this lock is
3872 for (i
= 0; i
< nr_list_entries
; i
++) {
3873 if (list_entries
[i
].class == class)
3874 list_del_rcu(&list_entries
[i
].entry
);
3877 * Unhash the class and remove it from the all_lock_classes list:
3879 list_del_rcu(&class->hash_entry
);
3880 list_del_rcu(&class->lock_entry
);
3885 static inline int within(const void *addr
, void *start
, unsigned long size
)
3887 return addr
>= start
&& addr
< start
+ size
;
3890 void lockdep_free_key_range(void *start
, unsigned long size
)
3892 struct lock_class
*class, *next
;
3893 struct list_head
*head
;
3894 unsigned long flags
;
3898 raw_local_irq_save(flags
);
3899 locked
= graph_lock();
3902 * Unhash all classes that were created by this module:
3904 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3905 head
= classhash_table
+ i
;
3906 if (list_empty(head
))
3908 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3909 if (within(class->key
, start
, size
))
3911 else if (within(class->name
, start
, size
))
3918 raw_local_irq_restore(flags
);
3921 void lockdep_reset_lock(struct lockdep_map
*lock
)
3923 struct lock_class
*class, *next
;
3924 struct list_head
*head
;
3925 unsigned long flags
;
3929 raw_local_irq_save(flags
);
3932 * Remove all classes this lock might have:
3934 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3936 * If the class exists we look it up and zap it:
3938 class = look_up_lock_class(lock
, j
);
3943 * Debug check: in the end all mapped classes should
3946 locked
= graph_lock();
3947 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3948 head
= classhash_table
+ i
;
3949 if (list_empty(head
))
3951 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3954 for (j
= 0; j
< NR_LOCKDEP_CACHING_CLASSES
; j
++)
3955 match
|= class == lock
->class_cache
[j
];
3957 if (unlikely(match
)) {
3958 if (debug_locks_off_graph_unlock()) {
3960 * We all just reset everything, how did it match?
3972 raw_local_irq_restore(flags
);
3975 void lockdep_init(void)
3980 * Some architectures have their own start_kernel()
3981 * code which calls lockdep_init(), while we also
3982 * call lockdep_init() from the start_kernel() itself,
3983 * and we want to initialize the hashes only once:
3985 if (lockdep_initialized
)
3988 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3989 INIT_LIST_HEAD(classhash_table
+ i
);
3991 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3992 INIT_LIST_HEAD(chainhash_table
+ i
);
3994 lockdep_initialized
= 1;
3997 void __init
lockdep_info(void)
3999 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4001 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
4002 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
4003 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
4004 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
4005 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
4006 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
4007 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
4009 printk(" memory used by lock dependency info: %lu kB\n",
4010 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
4011 sizeof(struct list_head
) * CLASSHASH_SIZE
+
4012 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
4013 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
4014 sizeof(struct list_head
) * CHAINHASH_SIZE
4015 #ifdef CONFIG_PROVE_LOCKING
4016 + sizeof(struct circular_queue
)
4021 printk(" per task-struct memory footprint: %lu bytes\n",
4022 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
4024 #ifdef CONFIG_DEBUG_LOCKDEP
4025 if (lockdep_init_error
) {
4026 printk("WARNING: lockdep init error! lock-%s was acquired"
4027 "before lockdep_init\n", lock_init_error
);
4028 printk("Call stack leading to lockdep invocation was:\n");
4029 print_stack_trace(&lockdep_init_trace
, 0);
4035 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
4036 const void *mem_to
, struct held_lock
*hlock
)
4038 if (!debug_locks_off())
4040 if (debug_locks_silent
)
4044 printk("=========================\n");
4045 printk("[ BUG: held lock freed! ]\n");
4046 print_kernel_ident();
4047 printk("-------------------------\n");
4048 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4049 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
4051 lockdep_print_held_locks(curr
);
4053 printk("\nstack backtrace:\n");
4057 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
4058 const void* lock_from
, unsigned long lock_len
)
4060 return lock_from
+ lock_len
<= mem_from
||
4061 mem_from
+ mem_len
<= lock_from
;
4065 * Called when kernel memory is freed (or unmapped), or if a lock
4066 * is destroyed or reinitialized - this code checks whether there is
4067 * any held lock in the memory range of <from> to <to>:
4069 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
4071 struct task_struct
*curr
= current
;
4072 struct held_lock
*hlock
;
4073 unsigned long flags
;
4076 if (unlikely(!debug_locks
))
4079 local_irq_save(flags
);
4080 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
4081 hlock
= curr
->held_locks
+ i
;
4083 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
4084 sizeof(*hlock
->instance
)))
4087 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
4090 local_irq_restore(flags
);
4092 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
4094 static void print_held_locks_bug(struct task_struct
*curr
)
4096 if (!debug_locks_off())
4098 if (debug_locks_silent
)
4102 printk("=====================================\n");
4103 printk("[ BUG: lock held at task exit time! ]\n");
4104 print_kernel_ident();
4105 printk("-------------------------------------\n");
4106 printk("%s/%d is exiting with locks still held!\n",
4107 curr
->comm
, task_pid_nr(curr
));
4108 lockdep_print_held_locks(curr
);
4110 printk("\nstack backtrace:\n");
4114 void debug_check_no_locks_held(struct task_struct
*task
)
4116 if (unlikely(task
->lockdep_depth
> 0))
4117 print_held_locks_bug(task
);
4120 void debug_show_all_locks(void)
4122 struct task_struct
*g
, *p
;
4126 if (unlikely(!debug_locks
)) {
4127 printk("INFO: lockdep is turned off.\n");
4130 printk("\nShowing all locks held in the system:\n");
4133 * Here we try to get the tasklist_lock as hard as possible,
4134 * if not successful after 2 seconds we ignore it (but keep
4135 * trying). This is to enable a debug printout even if a
4136 * tasklist_lock-holding task deadlocks or crashes.
4139 if (!read_trylock(&tasklist_lock
)) {
4141 printk("hm, tasklist_lock locked, retrying... ");
4144 printk(" #%d", 10-count
);
4148 printk(" ignoring it.\n");
4152 printk(KERN_CONT
" locked it.\n");
4155 do_each_thread(g
, p
) {
4157 * It's not reliable to print a task's held locks
4158 * if it's not sleeping (or if it's not the current
4161 if (p
->state
== TASK_RUNNING
&& p
!= current
)
4163 if (p
->lockdep_depth
)
4164 lockdep_print_held_locks(p
);
4166 if (read_trylock(&tasklist_lock
))
4168 } while_each_thread(g
, p
);
4171 printk("=============================================\n\n");
4174 read_unlock(&tasklist_lock
);
4176 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
4179 * Careful: only use this function if you are sure that
4180 * the task cannot run in parallel!
4182 void debug_show_held_locks(struct task_struct
*task
)
4184 if (unlikely(!debug_locks
)) {
4185 printk("INFO: lockdep is turned off.\n");
4188 lockdep_print_held_locks(task
);
4190 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
4192 void lockdep_sys_exit(void)
4194 struct task_struct
*curr
= current
;
4196 if (unlikely(curr
->lockdep_depth
)) {
4197 if (!debug_locks_off())
4200 printk("================================================\n");
4201 printk("[ BUG: lock held when returning to user space! ]\n");
4202 print_kernel_ident();
4203 printk("------------------------------------------------\n");
4204 printk("%s/%d is leaving the kernel with locks still held!\n",
4205 curr
->comm
, curr
->pid
);
4206 lockdep_print_held_locks(curr
);
4210 void lockdep_rcu_suspicious(const char *file
, const int line
, const char *s
)
4212 struct task_struct
*curr
= current
;
4214 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4215 if (!debug_locks_off())
4217 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4218 /* Note: the following can be executed concurrently, so be careful. */
4220 printk("===============================\n");
4221 printk("[ INFO: suspicious RCU usage. ]\n");
4222 print_kernel_ident();
4223 printk("-------------------------------\n");
4224 printk("%s:%d %s!\n", file
, line
, s
);
4225 printk("\nother info that might help us debug this:\n\n");
4226 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4227 !rcu_lockdep_current_cpu_online()
4228 ? "RCU used illegally from offline CPU!\n"
4230 ? "RCU used illegally from idle CPU!\n"
4232 rcu_scheduler_active
, debug_locks
);
4235 * If a CPU is in the RCU-free window in idle (ie: in the section
4236 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4237 * considers that CPU to be in an "extended quiescent state",
4238 * which means that RCU will be completely ignoring that CPU.
4239 * Therefore, rcu_read_lock() and friends have absolutely no
4240 * effect on a CPU running in that state. In other words, even if
4241 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4242 * delete data structures out from under it. RCU really has no
4243 * choice here: we need to keep an RCU-free window in idle where
4244 * the CPU may possibly enter into low power mode. This way we can
4245 * notice an extended quiescent state to other CPUs that started a grace
4246 * period. Otherwise we would delay any grace period as long as we run
4249 * So complain bitterly if someone does call rcu_read_lock(),
4250 * rcu_read_lock_bh() and so on from extended quiescent states.
4252 if (rcu_is_cpu_idle())
4253 printk("RCU used illegally from extended quiescent state!\n");
4255 lockdep_print_held_locks(curr
);
4256 printk("\nstack backtrace:\n");
4259 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious
);