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>
46 #include <asm/sections.h>
48 #include "lockdep_internals.h"
50 #ifdef CONFIG_PROVE_LOCKING
51 int prove_locking
= 1;
52 module_param(prove_locking
, int, 0644);
54 #define prove_locking 0
57 #ifdef CONFIG_LOCK_STAT
59 module_param(lock_stat
, int, 0644);
65 * lockdep_lock: protects the lockdep graph, the hashes and the
66 * class/list/hash allocators.
68 * This is one of the rare exceptions where it's justified
69 * to use a raw spinlock - we really dont want the spinlock
70 * code to recurse back into the lockdep code...
72 static raw_spinlock_t lockdep_lock
= (raw_spinlock_t
)__RAW_SPIN_LOCK_UNLOCKED
;
74 static int graph_lock(void)
76 __raw_spin_lock(&lockdep_lock
);
78 * Make sure that if another CPU detected a bug while
79 * walking the graph we dont change it (while the other
80 * CPU is busy printing out stuff with the graph lock
84 __raw_spin_unlock(&lockdep_lock
);
87 /* prevent any recursions within lockdep from causing deadlocks */
88 current
->lockdep_recursion
++;
92 static inline int graph_unlock(void)
94 if (debug_locks
&& !__raw_spin_is_locked(&lockdep_lock
))
95 return DEBUG_LOCKS_WARN_ON(1);
97 current
->lockdep_recursion
--;
98 __raw_spin_unlock(&lockdep_lock
);
103 * Turn lock debugging off and return with 0 if it was off already,
104 * and also release the graph lock:
106 static inline int debug_locks_off_graph_unlock(void)
108 int ret
= debug_locks_off();
110 __raw_spin_unlock(&lockdep_lock
);
115 static int lockdep_initialized
;
117 unsigned long nr_list_entries
;
118 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
121 * All data structures here are protected by the global debug_lock.
123 * Mutex key structs only get allocated, once during bootup, and never
124 * get freed - this significantly simplifies the debugging code.
126 unsigned long nr_lock_classes
;
127 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
129 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
131 if (!hlock
->class_idx
) {
132 DEBUG_LOCKS_WARN_ON(1);
135 return lock_classes
+ hlock
->class_idx
- 1;
138 #ifdef CONFIG_LOCK_STAT
139 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
], lock_stats
);
141 static int lock_point(unsigned long points
[], unsigned long ip
)
145 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
146 if (points
[i
] == 0) {
157 static void lock_time_inc(struct lock_time
*lt
, s64 time
)
162 if (time
< lt
->min
|| !lt
->min
)
169 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
171 dst
->min
+= src
->min
;
172 dst
->max
+= src
->max
;
173 dst
->total
+= src
->total
;
177 struct lock_class_stats
lock_stats(struct lock_class
*class)
179 struct lock_class_stats stats
;
182 memset(&stats
, 0, sizeof(struct lock_class_stats
));
183 for_each_possible_cpu(cpu
) {
184 struct lock_class_stats
*pcs
=
185 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
187 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
188 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
190 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
191 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
193 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
194 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
196 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
197 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
199 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
200 stats
.bounces
[i
] += pcs
->bounces
[i
];
206 void clear_lock_stats(struct lock_class
*class)
210 for_each_possible_cpu(cpu
) {
211 struct lock_class_stats
*cpu_stats
=
212 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
214 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
216 memset(class->contention_point
, 0, sizeof(class->contention_point
));
217 memset(class->contending_point
, 0, sizeof(class->contending_point
));
220 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
222 return &get_cpu_var(lock_stats
)[class - lock_classes
];
225 static void put_lock_stats(struct lock_class_stats
*stats
)
227 put_cpu_var(lock_stats
);
230 static void lock_release_holdtime(struct held_lock
*hlock
)
232 struct lock_class_stats
*stats
;
238 holdtime
= sched_clock() - hlock
->holdtime_stamp
;
240 stats
= get_lock_stats(hlock_class(hlock
));
242 lock_time_inc(&stats
->read_holdtime
, holdtime
);
244 lock_time_inc(&stats
->write_holdtime
, holdtime
);
245 put_lock_stats(stats
);
248 static inline void lock_release_holdtime(struct held_lock
*hlock
)
254 * We keep a global list of all lock classes. The list only grows,
255 * never shrinks. The list is only accessed with the lockdep
256 * spinlock lock held.
258 LIST_HEAD(all_lock_classes
);
261 * The lockdep classes are in a hash-table as well, for fast lookup:
263 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
264 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
265 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
266 #define classhashentry(key) (classhash_table + __classhashfn((key)))
268 static struct list_head classhash_table
[CLASSHASH_SIZE
];
271 * We put the lock dependency chains into a hash-table as well, to cache
274 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
275 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
276 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
277 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
279 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
282 * The hash key of the lock dependency chains is a hash itself too:
283 * it's a hash of all locks taken up to that lock, including that lock.
284 * It's a 64-bit hash, because it's important for the keys to be
287 #define iterate_chain_key(key1, key2) \
288 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
289 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
292 void lockdep_off(void)
294 current
->lockdep_recursion
++;
296 EXPORT_SYMBOL(lockdep_off
);
298 void lockdep_on(void)
300 current
->lockdep_recursion
--;
302 EXPORT_SYMBOL(lockdep_on
);
305 * Debugging switches:
309 #define VERY_VERBOSE 0
312 # define HARDIRQ_VERBOSE 1
313 # define SOFTIRQ_VERBOSE 1
314 # define RECLAIM_VERBOSE 1
316 # define HARDIRQ_VERBOSE 0
317 # define SOFTIRQ_VERBOSE 0
318 # define RECLAIM_VERBOSE 0
321 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
323 * Quick filtering for interesting events:
325 static int class_filter(struct lock_class
*class)
329 if (class->name_version
== 1 &&
330 !strcmp(class->name
, "lockname"))
332 if (class->name_version
== 1 &&
333 !strcmp(class->name
, "&struct->lockfield"))
336 /* Filter everything else. 1 would be to allow everything else */
341 static int verbose(struct lock_class
*class)
344 return class_filter(class);
350 * Stack-trace: tightly packed array of stack backtrace
351 * addresses. Protected by the graph_lock.
353 unsigned long nr_stack_trace_entries
;
354 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
356 static int save_trace(struct stack_trace
*trace
)
358 trace
->nr_entries
= 0;
359 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
360 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
364 save_stack_trace(trace
);
366 trace
->max_entries
= trace
->nr_entries
;
368 nr_stack_trace_entries
+= trace
->nr_entries
;
370 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
371 if (!debug_locks_off_graph_unlock())
374 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
375 printk("turning off the locking correctness validator.\n");
384 unsigned int nr_hardirq_chains
;
385 unsigned int nr_softirq_chains
;
386 unsigned int nr_process_chains
;
387 unsigned int max_lockdep_depth
;
388 unsigned int max_recursion_depth
;
390 static unsigned int lockdep_dependency_gen_id
;
392 static bool lockdep_dependency_visit(struct lock_class
*source
,
396 lockdep_dependency_gen_id
++;
397 if (source
->dep_gen_id
== lockdep_dependency_gen_id
)
399 source
->dep_gen_id
= lockdep_dependency_gen_id
;
403 #ifdef CONFIG_DEBUG_LOCKDEP
405 * We cannot printk in early bootup code. Not even early_printk()
406 * might work. So we mark any initialization errors and printk
407 * about it later on, in lockdep_info().
409 static int lockdep_init_error
;
410 static unsigned long lockdep_init_trace_data
[20];
411 static struct stack_trace lockdep_init_trace
= {
412 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
413 .entries
= lockdep_init_trace_data
,
417 * Various lockdep statistics:
419 atomic_t chain_lookup_hits
;
420 atomic_t chain_lookup_misses
;
421 atomic_t hardirqs_on_events
;
422 atomic_t hardirqs_off_events
;
423 atomic_t redundant_hardirqs_on
;
424 atomic_t redundant_hardirqs_off
;
425 atomic_t softirqs_on_events
;
426 atomic_t softirqs_off_events
;
427 atomic_t redundant_softirqs_on
;
428 atomic_t redundant_softirqs_off
;
429 atomic_t nr_unused_locks
;
430 atomic_t nr_cyclic_checks
;
431 atomic_t nr_cyclic_check_recursions
;
432 atomic_t nr_find_usage_forwards_checks
;
433 atomic_t nr_find_usage_forwards_recursions
;
434 atomic_t nr_find_usage_backwards_checks
;
435 atomic_t nr_find_usage_backwards_recursions
;
442 #define __USAGE(__STATE) \
443 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
444 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
445 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
446 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
448 static const char *usage_str
[] =
450 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
451 #include "lockdep_states.h"
453 [LOCK_USED
] = "INITIAL USE",
456 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
458 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
461 static inline unsigned long lock_flag(enum lock_usage_bit bit
)
466 static char get_usage_char(struct lock_class
*class, enum lock_usage_bit bit
)
470 if (class->usage_mask
& lock_flag(bit
+ 2))
472 if (class->usage_mask
& lock_flag(bit
)) {
474 if (class->usage_mask
& lock_flag(bit
+ 2))
481 void get_usage_chars(struct lock_class
*class, char usage
[LOCK_USAGE_CHARS
])
485 #define LOCKDEP_STATE(__STATE) \
486 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
487 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
488 #include "lockdep_states.h"
494 static void print_lock_name(struct lock_class
*class)
496 char str
[KSYM_NAME_LEN
], usage
[LOCK_USAGE_CHARS
];
499 get_usage_chars(class, usage
);
503 name
= __get_key_name(class->key
, str
);
504 printk(" (%s", name
);
506 printk(" (%s", name
);
507 if (class->name_version
> 1)
508 printk("#%d", class->name_version
);
510 printk("/%d", class->subclass
);
512 printk("){%s}", usage
);
515 static void print_lockdep_cache(struct lockdep_map
*lock
)
518 char str
[KSYM_NAME_LEN
];
522 name
= __get_key_name(lock
->key
->subkeys
, str
);
527 static void print_lock(struct held_lock
*hlock
)
529 print_lock_name(hlock_class(hlock
));
531 print_ip_sym(hlock
->acquire_ip
);
534 static void lockdep_print_held_locks(struct task_struct
*curr
)
536 int i
, depth
= curr
->lockdep_depth
;
539 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
542 printk("%d lock%s held by %s/%d:\n",
543 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
545 for (i
= 0; i
< depth
; i
++) {
547 print_lock(curr
->held_locks
+ i
);
551 static void print_lock_class_header(struct lock_class
*class, int depth
)
555 printk("%*s->", depth
, "");
556 print_lock_name(class);
557 printk(" ops: %lu", class->ops
);
560 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
561 if (class->usage_mask
& (1 << bit
)) {
564 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
565 len
+= printk(" at:\n");
566 print_stack_trace(class->usage_traces
+ bit
, len
);
569 printk("%*s }\n", depth
, "");
571 printk("%*s ... key at: ",depth
,"");
572 print_ip_sym((unsigned long)class->key
);
576 * printk all lock dependencies starting at <entry>:
579 print_lock_dependencies(struct lock_class
*class, int depth
)
581 struct lock_list
*entry
;
583 if (lockdep_dependency_visit(class, depth
))
586 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
589 print_lock_class_header(class, depth
);
591 list_for_each_entry(entry
, &class->locks_after
, entry
) {
592 if (DEBUG_LOCKS_WARN_ON(!entry
->class))
595 print_lock_dependencies(entry
->class, depth
+ 1);
597 printk("%*s ... acquired at:\n",depth
,"");
598 print_stack_trace(&entry
->trace
, 2);
603 static void print_kernel_version(void)
605 printk("%s %.*s\n", init_utsname()->release
,
606 (int)strcspn(init_utsname()->version
, " "),
607 init_utsname()->version
);
610 static int very_verbose(struct lock_class
*class)
613 return class_filter(class);
619 * Is this the address of a static object:
621 static int static_obj(void *obj
)
623 unsigned long start
= (unsigned long) &_stext
,
624 end
= (unsigned long) &_end
,
625 addr
= (unsigned long) obj
;
633 if ((addr
>= start
) && (addr
< end
))
640 for_each_possible_cpu(i
) {
641 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
642 end
= (unsigned long) &__per_cpu_start
+ PERCPU_ENOUGH_ROOM
645 if ((addr
>= start
) && (addr
< end
))
653 return is_module_address(addr
);
657 * To make lock name printouts unique, we calculate a unique
658 * class->name_version generation counter:
660 static int count_matching_names(struct lock_class
*new_class
)
662 struct lock_class
*class;
665 if (!new_class
->name
)
668 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
669 if (new_class
->key
- new_class
->subclass
== class->key
)
670 return class->name_version
;
671 if (class->name
&& !strcmp(class->name
, new_class
->name
))
672 count
= max(count
, class->name_version
);
679 * Register a lock's class in the hash-table, if the class is not present
680 * yet. Otherwise we look it up. We cache the result in the lock object
681 * itself, so actual lookup of the hash should be once per lock object.
683 static inline struct lock_class
*
684 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
686 struct lockdep_subclass_key
*key
;
687 struct list_head
*hash_head
;
688 struct lock_class
*class;
690 #ifdef CONFIG_DEBUG_LOCKDEP
692 * If the architecture calls into lockdep before initializing
693 * the hashes then we'll warn about it later. (we cannot printk
696 if (unlikely(!lockdep_initialized
)) {
698 lockdep_init_error
= 1;
699 save_stack_trace(&lockdep_init_trace
);
704 * Static locks do not have their class-keys yet - for them the key
705 * is the lock object itself:
707 if (unlikely(!lock
->key
))
708 lock
->key
= (void *)lock
;
711 * NOTE: the class-key must be unique. For dynamic locks, a static
712 * lock_class_key variable is passed in through the mutex_init()
713 * (or spin_lock_init()) call - which acts as the key. For static
714 * locks we use the lock object itself as the key.
716 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
717 sizeof(struct lockdep_map
));
719 key
= lock
->key
->subkeys
+ subclass
;
721 hash_head
= classhashentry(key
);
724 * We can walk the hash lockfree, because the hash only
725 * grows, and we are careful when adding entries to the end:
727 list_for_each_entry(class, hash_head
, hash_entry
) {
728 if (class->key
== key
) {
729 WARN_ON_ONCE(class->name
!= lock
->name
);
738 * Register a lock's class in the hash-table, if the class is not present
739 * yet. Otherwise we look it up. We cache the result in the lock object
740 * itself, so actual lookup of the hash should be once per lock object.
742 static inline struct lock_class
*
743 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
745 struct lockdep_subclass_key
*key
;
746 struct list_head
*hash_head
;
747 struct lock_class
*class;
750 class = look_up_lock_class(lock
, subclass
);
755 * Debug-check: all keys must be persistent!
757 if (!static_obj(lock
->key
)) {
759 printk("INFO: trying to register non-static key.\n");
760 printk("the code is fine but needs lockdep annotation.\n");
761 printk("turning off the locking correctness validator.\n");
767 key
= lock
->key
->subkeys
+ subclass
;
768 hash_head
= classhashentry(key
);
770 raw_local_irq_save(flags
);
772 raw_local_irq_restore(flags
);
776 * We have to do the hash-walk again, to avoid races
779 list_for_each_entry(class, hash_head
, hash_entry
)
780 if (class->key
== key
)
783 * Allocate a new key from the static array, and add it to
786 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
787 if (!debug_locks_off_graph_unlock()) {
788 raw_local_irq_restore(flags
);
791 raw_local_irq_restore(flags
);
793 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
794 printk("turning off the locking correctness validator.\n");
797 class = lock_classes
+ nr_lock_classes
++;
798 debug_atomic_inc(&nr_unused_locks
);
800 class->name
= lock
->name
;
801 class->subclass
= subclass
;
802 INIT_LIST_HEAD(&class->lock_entry
);
803 INIT_LIST_HEAD(&class->locks_before
);
804 INIT_LIST_HEAD(&class->locks_after
);
805 class->name_version
= count_matching_names(class);
807 * We use RCU's safe list-add method to make
808 * parallel walking of the hash-list safe:
810 list_add_tail_rcu(&class->hash_entry
, hash_head
);
812 * Add it to the global list of classes:
814 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
816 if (verbose(class)) {
818 raw_local_irq_restore(flags
);
820 printk("\nnew class %p: %s", class->key
, class->name
);
821 if (class->name_version
> 1)
822 printk("#%d", class->name_version
);
826 raw_local_irq_save(flags
);
828 raw_local_irq_restore(flags
);
834 raw_local_irq_restore(flags
);
836 if (!subclass
|| force
)
837 lock
->class_cache
= class;
839 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
845 #ifdef CONFIG_PROVE_LOCKING
847 * Allocate a lockdep entry. (assumes the graph_lock held, returns
848 * with NULL on failure)
850 static struct lock_list
*alloc_list_entry(void)
852 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
853 if (!debug_locks_off_graph_unlock())
856 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
857 printk("turning off the locking correctness validator.\n");
860 return list_entries
+ nr_list_entries
++;
864 * Add a new dependency to the head of the list:
866 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
867 struct list_head
*head
, unsigned long ip
, int distance
)
869 struct lock_list
*entry
;
871 * Lock not present yet - get a new dependency struct and
872 * add it to the list:
874 entry
= alloc_list_entry();
878 if (!save_trace(&entry
->trace
))
882 entry
->distance
= distance
;
884 * Since we never remove from the dependency list, the list can
885 * be walked lockless by other CPUs, it's only allocation
886 * that must be protected by the spinlock. But this also means
887 * we must make new entries visible only once writes to the
888 * entry become visible - hence the RCU op:
890 list_add_tail_rcu(&entry
->entry
, head
);
896 * Recursive, forwards-direction lock-dependency checking, used for
897 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
900 * (to keep the stackframe of the recursive functions small we
901 * use these global variables, and we also mark various helper
902 * functions as noinline.)
904 static struct held_lock
*check_source
, *check_target
;
907 * Print a dependency chain entry (this is only done when a deadlock
908 * has been detected):
911 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
913 if (debug_locks_silent
)
915 printk("\n-> #%u", depth
);
916 print_lock_name(target
->class);
918 print_stack_trace(&target
->trace
, 6);
924 * When a circular dependency is detected, print the
928 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
)
930 struct task_struct
*curr
= current
;
932 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
935 printk("\n=======================================================\n");
936 printk( "[ INFO: possible circular locking dependency detected ]\n");
937 print_kernel_version();
938 printk( "-------------------------------------------------------\n");
939 printk("%s/%d is trying to acquire lock:\n",
940 curr
->comm
, task_pid_nr(curr
));
941 print_lock(check_source
);
942 printk("\nbut task is already holding lock:\n");
943 print_lock(check_target
);
944 printk("\nwhich lock already depends on the new lock.\n\n");
945 printk("\nthe existing dependency chain (in reverse order) is:\n");
947 print_circular_bug_entry(entry
, depth
);
952 static noinline
int print_circular_bug_tail(void)
954 struct task_struct
*curr
= current
;
955 struct lock_list
this;
957 if (debug_locks_silent
)
960 this.class = hlock_class(check_source
);
961 if (!save_trace(&this.trace
))
964 print_circular_bug_entry(&this, 0);
966 printk("\nother info that might help us debug this:\n\n");
967 lockdep_print_held_locks(curr
);
969 printk("\nstack backtrace:\n");
975 #define RECURSION_LIMIT 40
977 static int noinline
print_infinite_recursion_bug(void)
979 if (!debug_locks_off_graph_unlock())
987 unsigned long __lockdep_count_forward_deps(struct lock_class
*class,
990 struct lock_list
*entry
;
991 unsigned long ret
= 1;
993 if (lockdep_dependency_visit(class, depth
))
997 * Recurse this class's dependency list:
999 list_for_each_entry(entry
, &class->locks_after
, entry
)
1000 ret
+= __lockdep_count_forward_deps(entry
->class, depth
+ 1);
1005 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1007 unsigned long ret
, flags
;
1009 local_irq_save(flags
);
1010 __raw_spin_lock(&lockdep_lock
);
1011 ret
= __lockdep_count_forward_deps(class, 0);
1012 __raw_spin_unlock(&lockdep_lock
);
1013 local_irq_restore(flags
);
1018 unsigned long __lockdep_count_backward_deps(struct lock_class
*class,
1021 struct lock_list
*entry
;
1022 unsigned long ret
= 1;
1024 if (lockdep_dependency_visit(class, depth
))
1027 * Recurse this class's dependency list:
1029 list_for_each_entry(entry
, &class->locks_before
, entry
)
1030 ret
+= __lockdep_count_backward_deps(entry
->class, depth
+ 1);
1035 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1037 unsigned long ret
, flags
;
1039 local_irq_save(flags
);
1040 __raw_spin_lock(&lockdep_lock
);
1041 ret
= __lockdep_count_backward_deps(class, 0);
1042 __raw_spin_unlock(&lockdep_lock
);
1043 local_irq_restore(flags
);
1049 * Prove that the dependency graph starting at <entry> can not
1050 * lead to <target>. Print an error and return 0 if it does.
1053 check_noncircular(struct lock_class
*source
, unsigned int depth
)
1055 struct lock_list
*entry
;
1057 if (lockdep_dependency_visit(source
, depth
))
1060 debug_atomic_inc(&nr_cyclic_check_recursions
);
1061 if (depth
> max_recursion_depth
)
1062 max_recursion_depth
= depth
;
1063 if (depth
>= RECURSION_LIMIT
)
1064 return print_infinite_recursion_bug();
1066 * Check this lock's dependency list:
1068 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1069 if (entry
->class == hlock_class(check_target
))
1070 return print_circular_bug_header(entry
, depth
+1);
1071 debug_atomic_inc(&nr_cyclic_checks
);
1072 if (!check_noncircular(entry
->class, depth
+1))
1073 return print_circular_bug_entry(entry
, depth
+1);
1078 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1080 * Forwards and backwards subgraph searching, for the purposes of
1081 * proving that two subgraphs can be connected by a new dependency
1082 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1084 static enum lock_usage_bit find_usage_bit
;
1085 static struct lock_class
*forwards_match
, *backwards_match
;
1088 * Find a node in the forwards-direction dependency sub-graph starting
1089 * at <source> that matches <find_usage_bit>.
1091 * Return 2 if such a node exists in the subgraph, and put that node
1092 * into <forwards_match>.
1094 * Return 1 otherwise and keep <forwards_match> unchanged.
1095 * Return 0 on error.
1098 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
1100 struct lock_list
*entry
;
1103 if (lockdep_dependency_visit(source
, depth
))
1106 if (depth
> max_recursion_depth
)
1107 max_recursion_depth
= depth
;
1108 if (depth
>= RECURSION_LIMIT
)
1109 return print_infinite_recursion_bug();
1111 debug_atomic_inc(&nr_find_usage_forwards_checks
);
1112 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1113 forwards_match
= source
;
1118 * Check this lock's dependency list:
1120 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1121 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
1122 ret
= find_usage_forwards(entry
->class, depth
+1);
1123 if (ret
== 2 || ret
== 0)
1130 * Find a node in the backwards-direction dependency sub-graph starting
1131 * at <source> that matches <find_usage_bit>.
1133 * Return 2 if such a node exists in the subgraph, and put that node
1134 * into <backwards_match>.
1136 * Return 1 otherwise and keep <backwards_match> unchanged.
1137 * Return 0 on error.
1140 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
1142 struct lock_list
*entry
;
1145 if (lockdep_dependency_visit(source
, depth
))
1148 if (!__raw_spin_is_locked(&lockdep_lock
))
1149 return DEBUG_LOCKS_WARN_ON(1);
1151 if (depth
> max_recursion_depth
)
1152 max_recursion_depth
= depth
;
1153 if (depth
>= RECURSION_LIMIT
)
1154 return print_infinite_recursion_bug();
1156 debug_atomic_inc(&nr_find_usage_backwards_checks
);
1157 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1158 backwards_match
= source
;
1162 if (!source
&& debug_locks_off_graph_unlock()) {
1168 * Check this lock's dependency list:
1170 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
1171 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
1172 ret
= find_usage_backwards(entry
->class, depth
+1);
1173 if (ret
== 2 || ret
== 0)
1180 print_bad_irq_dependency(struct task_struct
*curr
,
1181 struct held_lock
*prev
,
1182 struct held_lock
*next
,
1183 enum lock_usage_bit bit1
,
1184 enum lock_usage_bit bit2
,
1185 const char *irqclass
)
1187 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1190 printk("\n======================================================\n");
1191 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1192 irqclass
, irqclass
);
1193 print_kernel_version();
1194 printk( "------------------------------------------------------\n");
1195 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1196 curr
->comm
, task_pid_nr(curr
),
1197 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1198 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1199 curr
->hardirqs_enabled
,
1200 curr
->softirqs_enabled
);
1203 printk("\nand this task is already holding:\n");
1205 printk("which would create a new lock dependency:\n");
1206 print_lock_name(hlock_class(prev
));
1208 print_lock_name(hlock_class(next
));
1211 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1213 print_lock_name(backwards_match
);
1214 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1216 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
1218 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1219 print_lock_name(forwards_match
);
1220 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1223 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
1225 printk("\nother info that might help us debug this:\n\n");
1226 lockdep_print_held_locks(curr
);
1228 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
1229 print_lock_dependencies(backwards_match
, 0);
1231 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
1232 print_lock_dependencies(forwards_match
, 0);
1234 printk("\nstack backtrace:\n");
1241 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1242 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1243 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1247 find_usage_bit
= bit_backwards
;
1248 /* fills in <backwards_match> */
1249 ret
= find_usage_backwards(hlock_class(prev
), 0);
1250 if (!ret
|| ret
== 1)
1253 find_usage_bit
= bit_forwards
;
1254 ret
= find_usage_forwards(hlock_class(next
), 0);
1255 if (!ret
|| ret
== 1)
1258 return print_bad_irq_dependency(curr
, prev
, next
,
1259 bit_backwards
, bit_forwards
, irqclass
);
1262 static const char *state_names
[] = {
1263 #define LOCKDEP_STATE(__STATE) \
1264 __stringify(__STATE),
1265 #include "lockdep_states.h"
1266 #undef LOCKDEP_STATE
1269 static const char *state_rnames
[] = {
1270 #define LOCKDEP_STATE(__STATE) \
1271 __stringify(__STATE)"-READ",
1272 #include "lockdep_states.h"
1273 #undef LOCKDEP_STATE
1276 static inline const char *state_name(enum lock_usage_bit bit
)
1278 return (bit
& 1) ? state_rnames
[bit
>> 2] : state_names
[bit
>> 2];
1281 static int exclusive_bit(int new_bit
)
1289 * bit 0 - write/read
1290 * bit 1 - used_in/enabled
1294 int state
= new_bit
& ~3;
1295 int dir
= new_bit
& 2;
1298 * keep state, bit flip the direction and strip read.
1300 return state
| (dir
^ 2);
1303 static int check_irq_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1304 struct held_lock
*next
, enum lock_usage_bit bit
)
1307 * Prove that the new dependency does not connect a hardirq-safe
1308 * lock with a hardirq-unsafe lock - to achieve this we search
1309 * the backwards-subgraph starting at <prev>, and the
1310 * forwards-subgraph starting at <next>:
1312 if (!check_usage(curr
, prev
, next
, bit
,
1313 exclusive_bit(bit
), state_name(bit
)))
1319 * Prove that the new dependency does not connect a hardirq-safe-read
1320 * lock with a hardirq-unsafe lock - to achieve this we search
1321 * the backwards-subgraph starting at <prev>, and the
1322 * forwards-subgraph starting at <next>:
1324 if (!check_usage(curr
, prev
, next
, bit
,
1325 exclusive_bit(bit
), state_name(bit
)))
1332 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1333 struct held_lock
*next
)
1335 #define LOCKDEP_STATE(__STATE) \
1336 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1338 #include "lockdep_states.h"
1339 #undef LOCKDEP_STATE
1344 static void inc_chains(void)
1346 if (current
->hardirq_context
)
1347 nr_hardirq_chains
++;
1349 if (current
->softirq_context
)
1350 nr_softirq_chains
++;
1352 nr_process_chains
++;
1359 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1360 struct held_lock
*next
)
1365 static inline void inc_chains(void)
1367 nr_process_chains
++;
1373 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1374 struct held_lock
*next
)
1376 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1379 printk("\n=============================================\n");
1380 printk( "[ INFO: possible recursive locking detected ]\n");
1381 print_kernel_version();
1382 printk( "---------------------------------------------\n");
1383 printk("%s/%d is trying to acquire lock:\n",
1384 curr
->comm
, task_pid_nr(curr
));
1386 printk("\nbut task is already holding lock:\n");
1389 printk("\nother info that might help us debug this:\n");
1390 lockdep_print_held_locks(curr
);
1392 printk("\nstack backtrace:\n");
1399 * Check whether we are holding such a class already.
1401 * (Note that this has to be done separately, because the graph cannot
1402 * detect such classes of deadlocks.)
1404 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1407 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1408 struct lockdep_map
*next_instance
, int read
)
1410 struct held_lock
*prev
;
1411 struct held_lock
*nest
= NULL
;
1414 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1415 prev
= curr
->held_locks
+ i
;
1417 if (prev
->instance
== next
->nest_lock
)
1420 if (hlock_class(prev
) != hlock_class(next
))
1424 * Allow read-after-read recursion of the same
1425 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1427 if ((read
== 2) && prev
->read
)
1431 * We're holding the nest_lock, which serializes this lock's
1432 * nesting behaviour.
1437 return print_deadlock_bug(curr
, prev
, next
);
1443 * There was a chain-cache miss, and we are about to add a new dependency
1444 * to a previous lock. We recursively validate the following rules:
1446 * - would the adding of the <prev> -> <next> dependency create a
1447 * circular dependency in the graph? [== circular deadlock]
1449 * - does the new prev->next dependency connect any hardirq-safe lock
1450 * (in the full backwards-subgraph starting at <prev>) with any
1451 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1452 * <next>)? [== illegal lock inversion with hardirq contexts]
1454 * - does the new prev->next dependency connect any softirq-safe lock
1455 * (in the full backwards-subgraph starting at <prev>) with any
1456 * softirq-unsafe lock (in the full forwards-subgraph starting at
1457 * <next>)? [== illegal lock inversion with softirq contexts]
1459 * any of these scenarios could lead to a deadlock.
1461 * Then if all the validations pass, we add the forwards and backwards
1465 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1466 struct held_lock
*next
, int distance
)
1468 struct lock_list
*entry
;
1472 * Prove that the new <prev> -> <next> dependency would not
1473 * create a circular dependency in the graph. (We do this by
1474 * forward-recursing into the graph starting at <next>, and
1475 * checking whether we can reach <prev>.)
1477 * We are using global variables to control the recursion, to
1478 * keep the stackframe size of the recursive functions low:
1480 check_source
= next
;
1481 check_target
= prev
;
1482 if (!(check_noncircular(hlock_class(next
), 0)))
1483 return print_circular_bug_tail();
1485 if (!check_prev_add_irq(curr
, prev
, next
))
1489 * For recursive read-locks we do all the dependency checks,
1490 * but we dont store read-triggered dependencies (only
1491 * write-triggered dependencies). This ensures that only the
1492 * write-side dependencies matter, and that if for example a
1493 * write-lock never takes any other locks, then the reads are
1494 * equivalent to a NOP.
1496 if (next
->read
== 2 || prev
->read
== 2)
1499 * Is the <prev> -> <next> dependency already present?
1501 * (this may occur even though this is a new chain: consider
1502 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1503 * chains - the second one will be new, but L1 already has
1504 * L2 added to its dependency list, due to the first chain.)
1506 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1507 if (entry
->class == hlock_class(next
)) {
1509 entry
->distance
= 1;
1515 * Ok, all validations passed, add the new lock
1516 * to the previous lock's dependency list:
1518 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1519 &hlock_class(prev
)->locks_after
,
1520 next
->acquire_ip
, distance
);
1525 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1526 &hlock_class(next
)->locks_before
,
1527 next
->acquire_ip
, distance
);
1532 * Debugging printouts:
1534 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1536 printk("\n new dependency: ");
1537 print_lock_name(hlock_class(prev
));
1539 print_lock_name(hlock_class(next
));
1542 return graph_lock();
1548 * Add the dependency to all directly-previous locks that are 'relevant'.
1549 * The ones that are relevant are (in increasing distance from curr):
1550 * all consecutive trylock entries and the final non-trylock entry - or
1551 * the end of this context's lock-chain - whichever comes first.
1554 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1556 int depth
= curr
->lockdep_depth
;
1557 struct held_lock
*hlock
;
1562 * Depth must not be zero for a non-head lock:
1567 * At least two relevant locks must exist for this
1570 if (curr
->held_locks
[depth
].irq_context
!=
1571 curr
->held_locks
[depth
-1].irq_context
)
1575 int distance
= curr
->lockdep_depth
- depth
+ 1;
1576 hlock
= curr
->held_locks
+ depth
-1;
1578 * Only non-recursive-read entries get new dependencies
1581 if (hlock
->read
!= 2) {
1582 if (!check_prev_add(curr
, hlock
, next
, distance
))
1585 * Stop after the first non-trylock entry,
1586 * as non-trylock entries have added their
1587 * own direct dependencies already, so this
1588 * lock is connected to them indirectly:
1590 if (!hlock
->trylock
)
1595 * End of lock-stack?
1600 * Stop the search if we cross into another context:
1602 if (curr
->held_locks
[depth
].irq_context
!=
1603 curr
->held_locks
[depth
-1].irq_context
)
1608 if (!debug_locks_off_graph_unlock())
1616 unsigned long nr_lock_chains
;
1617 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1618 int nr_chain_hlocks
;
1619 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1621 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1623 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1627 * Look up a dependency chain. If the key is not present yet then
1628 * add it and return 1 - in this case the new dependency chain is
1629 * validated. If the key is already hashed, return 0.
1630 * (On return with 1 graph_lock is held.)
1632 static inline int lookup_chain_cache(struct task_struct
*curr
,
1633 struct held_lock
*hlock
,
1636 struct lock_class
*class = hlock_class(hlock
);
1637 struct list_head
*hash_head
= chainhashentry(chain_key
);
1638 struct lock_chain
*chain
;
1639 struct held_lock
*hlock_curr
, *hlock_next
;
1642 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1645 * We can walk it lock-free, because entries only get added
1648 list_for_each_entry(chain
, hash_head
, entry
) {
1649 if (chain
->chain_key
== chain_key
) {
1651 debug_atomic_inc(&chain_lookup_hits
);
1652 if (very_verbose(class))
1653 printk("\nhash chain already cached, key: "
1654 "%016Lx tail class: [%p] %s\n",
1655 (unsigned long long)chain_key
,
1656 class->key
, class->name
);
1660 if (very_verbose(class))
1661 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1662 (unsigned long long)chain_key
, class->key
, class->name
);
1664 * Allocate a new chain entry from the static array, and add
1670 * We have to walk the chain again locked - to avoid duplicates:
1672 list_for_each_entry(chain
, hash_head
, entry
) {
1673 if (chain
->chain_key
== chain_key
) {
1678 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1679 if (!debug_locks_off_graph_unlock())
1682 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1683 printk("turning off the locking correctness validator.\n");
1686 chain
= lock_chains
+ nr_lock_chains
++;
1687 chain
->chain_key
= chain_key
;
1688 chain
->irq_context
= hlock
->irq_context
;
1689 /* Find the first held_lock of current chain */
1691 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
1692 hlock_curr
= curr
->held_locks
+ i
;
1693 if (hlock_curr
->irq_context
!= hlock_next
->irq_context
)
1698 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
1699 cn
= nr_chain_hlocks
;
1700 while (cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
) {
1701 n
= cmpxchg(&nr_chain_hlocks
, cn
, cn
+ chain
->depth
);
1706 if (likely(cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
1708 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
1709 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
1710 chain_hlocks
[chain
->base
+ j
] = lock_id
;
1712 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
1714 list_add_tail_rcu(&chain
->entry
, hash_head
);
1715 debug_atomic_inc(&chain_lookup_misses
);
1721 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
1722 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
1725 * Trylock needs to maintain the stack of held locks, but it
1726 * does not add new dependencies, because trylock can be done
1729 * We look up the chain_key and do the O(N^2) check and update of
1730 * the dependencies only if this is a new dependency chain.
1731 * (If lookup_chain_cache() returns with 1 it acquires
1732 * graph_lock for us)
1734 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
1735 lookup_chain_cache(curr
, hlock
, chain_key
)) {
1737 * Check whether last held lock:
1739 * - is irq-safe, if this lock is irq-unsafe
1740 * - is softirq-safe, if this lock is hardirq-unsafe
1742 * And check whether the new lock's dependency graph
1743 * could lead back to the previous lock.
1745 * any of these scenarios could lead to a deadlock. If
1748 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
1753 * Mark recursive read, as we jump over it when
1754 * building dependencies (just like we jump over
1760 * Add dependency only if this lock is not the head
1761 * of the chain, and if it's not a secondary read-lock:
1763 if (!chain_head
&& ret
!= 2)
1764 if (!check_prevs_add(curr
, hlock
))
1768 /* after lookup_chain_cache(): */
1769 if (unlikely(!debug_locks
))
1775 static inline int validate_chain(struct task_struct
*curr
,
1776 struct lockdep_map
*lock
, struct held_lock
*hlock
,
1777 int chain_head
, u64 chain_key
)
1784 * We are building curr_chain_key incrementally, so double-check
1785 * it from scratch, to make sure that it's done correctly:
1787 static void check_chain_key(struct task_struct
*curr
)
1789 #ifdef CONFIG_DEBUG_LOCKDEP
1790 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1794 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1795 hlock
= curr
->held_locks
+ i
;
1796 if (chain_key
!= hlock
->prev_chain_key
) {
1798 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1799 curr
->lockdep_depth
, i
,
1800 (unsigned long long)chain_key
,
1801 (unsigned long long)hlock
->prev_chain_key
);
1804 id
= hlock
->class_idx
- 1;
1805 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
1808 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1809 hlock
->irq_context
))
1811 chain_key
= iterate_chain_key(chain_key
, id
);
1814 if (chain_key
!= curr
->curr_chain_key
) {
1816 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1817 curr
->lockdep_depth
, i
,
1818 (unsigned long long)chain_key
,
1819 (unsigned long long)curr
->curr_chain_key
);
1825 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1826 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1828 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1831 printk("\n=================================\n");
1832 printk( "[ INFO: inconsistent lock state ]\n");
1833 print_kernel_version();
1834 printk( "---------------------------------\n");
1836 printk("inconsistent {%s} -> {%s} usage.\n",
1837 usage_str
[prev_bit
], usage_str
[new_bit
]);
1839 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1840 curr
->comm
, task_pid_nr(curr
),
1841 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1842 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1843 trace_hardirqs_enabled(curr
),
1844 trace_softirqs_enabled(curr
));
1847 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1848 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
1850 print_irqtrace_events(curr
);
1851 printk("\nother info that might help us debug this:\n");
1852 lockdep_print_held_locks(curr
);
1854 printk("\nstack backtrace:\n");
1861 * Print out an error if an invalid bit is set:
1864 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1865 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1867 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
1868 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1872 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1873 enum lock_usage_bit new_bit
);
1875 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1878 * print irq inversion bug:
1881 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
1882 struct held_lock
*this, int forwards
,
1883 const char *irqclass
)
1885 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1888 printk("\n=========================================================\n");
1889 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1890 print_kernel_version();
1891 printk( "---------------------------------------------------------\n");
1892 printk("%s/%d just changed the state of lock:\n",
1893 curr
->comm
, task_pid_nr(curr
));
1896 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass
);
1898 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass
);
1899 print_lock_name(other
);
1900 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1902 printk("\nother info that might help us debug this:\n");
1903 lockdep_print_held_locks(curr
);
1905 printk("\nthe first lock's dependencies:\n");
1906 print_lock_dependencies(hlock_class(this), 0);
1908 printk("\nthe second lock's dependencies:\n");
1909 print_lock_dependencies(other
, 0);
1911 printk("\nstack backtrace:\n");
1918 * Prove that in the forwards-direction subgraph starting at <this>
1919 * there is no lock matching <mask>:
1922 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
1923 enum lock_usage_bit bit
, const char *irqclass
)
1927 find_usage_bit
= bit
;
1928 /* fills in <forwards_match> */
1929 ret
= find_usage_forwards(hlock_class(this), 0);
1930 if (!ret
|| ret
== 1)
1933 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
1937 * Prove that in the backwards-direction subgraph starting at <this>
1938 * there is no lock matching <mask>:
1941 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
1942 enum lock_usage_bit bit
, const char *irqclass
)
1946 find_usage_bit
= bit
;
1947 /* fills in <backwards_match> */
1948 ret
= find_usage_backwards(hlock_class(this), 0);
1949 if (!ret
|| ret
== 1)
1952 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
1955 void print_irqtrace_events(struct task_struct
*curr
)
1957 printk("irq event stamp: %u\n", curr
->irq_events
);
1958 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
1959 print_ip_sym(curr
->hardirq_enable_ip
);
1960 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
1961 print_ip_sym(curr
->hardirq_disable_ip
);
1962 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
1963 print_ip_sym(curr
->softirq_enable_ip
);
1964 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
1965 print_ip_sym(curr
->softirq_disable_ip
);
1968 static int HARDIRQ_verbose(struct lock_class
*class)
1971 return class_filter(class);
1976 static int SOFTIRQ_verbose(struct lock_class
*class)
1979 return class_filter(class);
1984 static int RECLAIM_FS_verbose(struct lock_class
*class)
1987 return class_filter(class);
1992 #define STRICT_READ_CHECKS 1
1994 static int (*state_verbose_f
[])(struct lock_class
*class) = {
1995 #define LOCKDEP_STATE(__STATE) \
1997 #include "lockdep_states.h"
1998 #undef LOCKDEP_STATE
2001 static inline int state_verbose(enum lock_usage_bit bit
,
2002 struct lock_class
*class)
2004 return state_verbose_f
[bit
>> 2](class);
2007 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2008 enum lock_usage_bit bit
, const char *name
);
2011 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2012 enum lock_usage_bit new_bit
)
2014 int excl_bit
= exclusive_bit(new_bit
);
2015 int read
= new_bit
& 1;
2016 int dir
= new_bit
& 2;
2019 * mark USED_IN has to look forwards -- to ensure no dependency
2020 * has ENABLED state, which would allow recursion deadlocks.
2022 * mark ENABLED has to look backwards -- to ensure no dependee
2023 * has USED_IN state, which, again, would allow recursion deadlocks.
2025 check_usage_f usage
= dir
?
2026 check_usage_backwards
: check_usage_forwards
;
2029 * Validate that this particular lock does not have conflicting
2032 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2036 * Validate that the lock dependencies don't have conflicting usage
2039 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2040 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2044 * Check for read in write conflicts
2047 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2050 if (STRICT_READ_CHECKS
&&
2051 !usage(curr
, this, excl_bit
+ 1,
2052 state_name(new_bit
+ 1)))
2056 if (state_verbose(new_bit
, hlock_class(this)))
2063 #define LOCKDEP_STATE(__STATE) __STATE,
2064 #include "lockdep_states.h"
2065 #undef LOCKDEP_STATE
2069 * Mark all held locks with a usage bit:
2072 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2074 enum lock_usage_bit usage_bit
;
2075 struct held_lock
*hlock
;
2078 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2079 hlock
= curr
->held_locks
+ i
;
2081 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2083 usage_bit
+= 1; /* READ */
2085 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2087 if (!mark_lock(curr
, hlock
, usage_bit
))
2095 * Debugging helper: via this flag we know that we are in
2096 * 'early bootup code', and will warn about any invalid irqs-on event:
2098 static int early_boot_irqs_enabled
;
2100 void early_boot_irqs_off(void)
2102 early_boot_irqs_enabled
= 0;
2105 void early_boot_irqs_on(void)
2107 early_boot_irqs_enabled
= 1;
2111 * Hardirqs will be enabled:
2113 void trace_hardirqs_on_caller(unsigned long ip
)
2115 struct task_struct
*curr
= current
;
2117 time_hardirqs_on(CALLER_ADDR0
, ip
);
2119 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2122 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
2125 if (unlikely(curr
->hardirqs_enabled
)) {
2126 debug_atomic_inc(&redundant_hardirqs_on
);
2129 /* we'll do an OFF -> ON transition: */
2130 curr
->hardirqs_enabled
= 1;
2132 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2134 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2137 * We are going to turn hardirqs on, so set the
2138 * usage bit for all held locks:
2140 if (!mark_held_locks(curr
, HARDIRQ
))
2143 * If we have softirqs enabled, then set the usage
2144 * bit for all held locks. (disabled hardirqs prevented
2145 * this bit from being set before)
2147 if (curr
->softirqs_enabled
)
2148 if (!mark_held_locks(curr
, SOFTIRQ
))
2151 curr
->hardirq_enable_ip
= ip
;
2152 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2153 debug_atomic_inc(&hardirqs_on_events
);
2155 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2157 void trace_hardirqs_on(void)
2159 trace_hardirqs_on_caller(CALLER_ADDR0
);
2161 EXPORT_SYMBOL(trace_hardirqs_on
);
2164 * Hardirqs were disabled:
2166 void trace_hardirqs_off_caller(unsigned long ip
)
2168 struct task_struct
*curr
= current
;
2170 time_hardirqs_off(CALLER_ADDR0
, ip
);
2172 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2175 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2178 if (curr
->hardirqs_enabled
) {
2180 * We have done an ON -> OFF transition:
2182 curr
->hardirqs_enabled
= 0;
2183 curr
->hardirq_disable_ip
= ip
;
2184 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2185 debug_atomic_inc(&hardirqs_off_events
);
2187 debug_atomic_inc(&redundant_hardirqs_off
);
2189 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2191 void trace_hardirqs_off(void)
2193 trace_hardirqs_off_caller(CALLER_ADDR0
);
2195 EXPORT_SYMBOL(trace_hardirqs_off
);
2198 * Softirqs will be enabled:
2200 void trace_softirqs_on(unsigned long ip
)
2202 struct task_struct
*curr
= current
;
2204 if (unlikely(!debug_locks
))
2207 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2210 if (curr
->softirqs_enabled
) {
2211 debug_atomic_inc(&redundant_softirqs_on
);
2216 * We'll do an OFF -> ON transition:
2218 curr
->softirqs_enabled
= 1;
2219 curr
->softirq_enable_ip
= ip
;
2220 curr
->softirq_enable_event
= ++curr
->irq_events
;
2221 debug_atomic_inc(&softirqs_on_events
);
2223 * We are going to turn softirqs on, so set the
2224 * usage bit for all held locks, if hardirqs are
2227 if (curr
->hardirqs_enabled
)
2228 mark_held_locks(curr
, SOFTIRQ
);
2232 * Softirqs were disabled:
2234 void trace_softirqs_off(unsigned long ip
)
2236 struct task_struct
*curr
= current
;
2238 if (unlikely(!debug_locks
))
2241 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2244 if (curr
->softirqs_enabled
) {
2246 * We have done an ON -> OFF transition:
2248 curr
->softirqs_enabled
= 0;
2249 curr
->softirq_disable_ip
= ip
;
2250 curr
->softirq_disable_event
= ++curr
->irq_events
;
2251 debug_atomic_inc(&softirqs_off_events
);
2252 DEBUG_LOCKS_WARN_ON(!softirq_count());
2254 debug_atomic_inc(&redundant_softirqs_off
);
2257 static void __lockdep_trace_alloc(gfp_t gfp_mask
, unsigned long flags
)
2259 struct task_struct
*curr
= current
;
2261 if (unlikely(!debug_locks
))
2264 /* no reclaim without waiting on it */
2265 if (!(gfp_mask
& __GFP_WAIT
))
2268 /* this guy won't enter reclaim */
2269 if ((curr
->flags
& PF_MEMALLOC
) && !(gfp_mask
& __GFP_NOMEMALLOC
))
2272 /* We're only interested __GFP_FS allocations for now */
2273 if (!(gfp_mask
& __GFP_FS
))
2276 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags
)))
2279 mark_held_locks(curr
, RECLAIM_FS
);
2282 static void check_flags(unsigned long flags
);
2284 void lockdep_trace_alloc(gfp_t gfp_mask
)
2286 unsigned long flags
;
2288 if (unlikely(current
->lockdep_recursion
))
2291 raw_local_irq_save(flags
);
2293 current
->lockdep_recursion
= 1;
2294 __lockdep_trace_alloc(gfp_mask
, flags
);
2295 current
->lockdep_recursion
= 0;
2296 raw_local_irq_restore(flags
);
2299 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2302 * If non-trylock use in a hardirq or softirq context, then
2303 * mark the lock as used in these contexts:
2305 if (!hlock
->trylock
) {
2307 if (curr
->hardirq_context
)
2308 if (!mark_lock(curr
, hlock
,
2309 LOCK_USED_IN_HARDIRQ_READ
))
2311 if (curr
->softirq_context
)
2312 if (!mark_lock(curr
, hlock
,
2313 LOCK_USED_IN_SOFTIRQ_READ
))
2316 if (curr
->hardirq_context
)
2317 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2319 if (curr
->softirq_context
)
2320 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2324 if (!hlock
->hardirqs_off
) {
2326 if (!mark_lock(curr
, hlock
,
2327 LOCK_ENABLED_HARDIRQ_READ
))
2329 if (curr
->softirqs_enabled
)
2330 if (!mark_lock(curr
, hlock
,
2331 LOCK_ENABLED_SOFTIRQ_READ
))
2334 if (!mark_lock(curr
, hlock
,
2335 LOCK_ENABLED_HARDIRQ
))
2337 if (curr
->softirqs_enabled
)
2338 if (!mark_lock(curr
, hlock
,
2339 LOCK_ENABLED_SOFTIRQ
))
2345 * We reuse the irq context infrastructure more broadly as a general
2346 * context checking code. This tests GFP_FS recursion (a lock taken
2347 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2350 if (!hlock
->trylock
&& (curr
->lockdep_reclaim_gfp
& __GFP_FS
)) {
2352 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS_READ
))
2355 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS
))
2363 static int separate_irq_context(struct task_struct
*curr
,
2364 struct held_lock
*hlock
)
2366 unsigned int depth
= curr
->lockdep_depth
;
2369 * Keep track of points where we cross into an interrupt context:
2371 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2372 curr
->softirq_context
;
2374 struct held_lock
*prev_hlock
;
2376 prev_hlock
= curr
->held_locks
+ depth
-1;
2378 * If we cross into another context, reset the
2379 * hash key (this also prevents the checking and the
2380 * adding of the dependency to 'prev'):
2382 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2391 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2392 enum lock_usage_bit new_bit
)
2398 static inline int mark_irqflags(struct task_struct
*curr
,
2399 struct held_lock
*hlock
)
2404 static inline int separate_irq_context(struct task_struct
*curr
,
2405 struct held_lock
*hlock
)
2410 void lockdep_trace_alloc(gfp_t gfp_mask
)
2417 * Mark a lock with a usage bit, and validate the state transition:
2419 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2420 enum lock_usage_bit new_bit
)
2422 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2425 * If already set then do not dirty the cacheline,
2426 * nor do any checks:
2428 if (likely(hlock_class(this)->usage_mask
& new_mask
))
2434 * Make sure we didnt race:
2436 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
2441 hlock_class(this)->usage_mask
|= new_mask
;
2443 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
2447 #define LOCKDEP_STATE(__STATE) \
2448 case LOCK_USED_IN_##__STATE: \
2449 case LOCK_USED_IN_##__STATE##_READ: \
2450 case LOCK_ENABLED_##__STATE: \
2451 case LOCK_ENABLED_##__STATE##_READ:
2452 #include "lockdep_states.h"
2453 #undef LOCKDEP_STATE
2454 ret
= mark_lock_irq(curr
, this, new_bit
);
2459 debug_atomic_dec(&nr_unused_locks
);
2462 if (!debug_locks_off_graph_unlock())
2471 * We must printk outside of the graph_lock:
2474 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2476 print_irqtrace_events(curr
);
2484 * Initialize a lock instance's lock-class mapping info:
2486 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2487 struct lock_class_key
*key
, int subclass
)
2489 if (unlikely(!debug_locks
))
2492 if (DEBUG_LOCKS_WARN_ON(!key
))
2494 if (DEBUG_LOCKS_WARN_ON(!name
))
2497 * Sanity check, the lock-class key must be persistent:
2499 if (!static_obj(key
)) {
2500 printk("BUG: key %p not in .data!\n", key
);
2501 DEBUG_LOCKS_WARN_ON(1);
2506 lock
->class_cache
= NULL
;
2507 #ifdef CONFIG_LOCK_STAT
2508 lock
->cpu
= raw_smp_processor_id();
2511 register_lock_class(lock
, subclass
, 1);
2513 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2516 * This gets called for every mutex_lock*()/spin_lock*() operation.
2517 * We maintain the dependency maps and validate the locking attempt:
2519 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2520 int trylock
, int read
, int check
, int hardirqs_off
,
2521 struct lockdep_map
*nest_lock
, unsigned long ip
)
2523 struct task_struct
*curr
= current
;
2524 struct lock_class
*class = NULL
;
2525 struct held_lock
*hlock
;
2526 unsigned int depth
, id
;
2533 if (unlikely(!debug_locks
))
2536 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2539 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
2541 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2542 printk("turning off the locking correctness validator.\n");
2547 class = lock
->class_cache
;
2549 * Not cached yet or subclass?
2551 if (unlikely(!class)) {
2552 class = register_lock_class(lock
, subclass
, 0);
2556 debug_atomic_inc((atomic_t
*)&class->ops
);
2557 if (very_verbose(class)) {
2558 printk("\nacquire class [%p] %s", class->key
, class->name
);
2559 if (class->name_version
> 1)
2560 printk("#%d", class->name_version
);
2566 * Add the lock to the list of currently held locks.
2567 * (we dont increase the depth just yet, up until the
2568 * dependency checks are done)
2570 depth
= curr
->lockdep_depth
;
2571 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2574 hlock
= curr
->held_locks
+ depth
;
2575 if (DEBUG_LOCKS_WARN_ON(!class))
2577 hlock
->class_idx
= class - lock_classes
+ 1;
2578 hlock
->acquire_ip
= ip
;
2579 hlock
->instance
= lock
;
2580 hlock
->nest_lock
= nest_lock
;
2581 hlock
->trylock
= trylock
;
2583 hlock
->check
= check
;
2584 hlock
->hardirqs_off
= !!hardirqs_off
;
2585 #ifdef CONFIG_LOCK_STAT
2586 hlock
->waittime_stamp
= 0;
2587 hlock
->holdtime_stamp
= sched_clock();
2590 if (check
== 2 && !mark_irqflags(curr
, hlock
))
2593 /* mark it as used: */
2594 if (!mark_lock(curr
, hlock
, LOCK_USED
))
2598 * Calculate the chain hash: it's the combined hash of all the
2599 * lock keys along the dependency chain. We save the hash value
2600 * at every step so that we can get the current hash easily
2601 * after unlock. The chain hash is then used to cache dependency
2604 * The 'key ID' is what is the most compact key value to drive
2605 * the hash, not class->key.
2607 id
= class - lock_classes
;
2608 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2611 chain_key
= curr
->curr_chain_key
;
2613 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2618 hlock
->prev_chain_key
= chain_key
;
2619 if (separate_irq_context(curr
, hlock
)) {
2623 chain_key
= iterate_chain_key(chain_key
, id
);
2625 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
2628 curr
->curr_chain_key
= chain_key
;
2629 curr
->lockdep_depth
++;
2630 check_chain_key(curr
);
2631 #ifdef CONFIG_DEBUG_LOCKDEP
2632 if (unlikely(!debug_locks
))
2635 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2637 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2638 printk("turning off the locking correctness validator.\n");
2642 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2643 max_lockdep_depth
= curr
->lockdep_depth
;
2649 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2652 if (!debug_locks_off())
2654 if (debug_locks_silent
)
2657 printk("\n=====================================\n");
2658 printk( "[ BUG: bad unlock balance detected! ]\n");
2659 printk( "-------------------------------------\n");
2660 printk("%s/%d is trying to release lock (",
2661 curr
->comm
, task_pid_nr(curr
));
2662 print_lockdep_cache(lock
);
2665 printk("but there are no more locks to release!\n");
2666 printk("\nother info that might help us debug this:\n");
2667 lockdep_print_held_locks(curr
);
2669 printk("\nstack backtrace:\n");
2676 * Common debugging checks for both nested and non-nested unlock:
2678 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2681 if (unlikely(!debug_locks
))
2683 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2686 if (curr
->lockdep_depth
<= 0)
2687 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2693 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
2694 struct lock_class_key
*key
, unsigned int subclass
,
2697 struct task_struct
*curr
= current
;
2698 struct held_lock
*hlock
, *prev_hlock
;
2699 struct lock_class
*class;
2703 depth
= curr
->lockdep_depth
;
2704 if (DEBUG_LOCKS_WARN_ON(!depth
))
2708 for (i
= depth
-1; i
>= 0; i
--) {
2709 hlock
= curr
->held_locks
+ i
;
2711 * We must not cross into another context:
2713 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2715 if (hlock
->instance
== lock
)
2719 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2722 lockdep_init_map(lock
, name
, key
, 0);
2723 class = register_lock_class(lock
, subclass
, 0);
2724 hlock
->class_idx
= class - lock_classes
+ 1;
2726 curr
->lockdep_depth
= i
;
2727 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2729 for (; i
< depth
; i
++) {
2730 hlock
= curr
->held_locks
+ i
;
2731 if (!__lock_acquire(hlock
->instance
,
2732 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2733 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2734 hlock
->nest_lock
, hlock
->acquire_ip
))
2738 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
2744 * Remove the lock to the list of currently held locks in a
2745 * potentially non-nested (out of order) manner. This is a
2746 * relatively rare operation, as all the unlock APIs default
2747 * to nested mode (which uses lock_release()):
2750 lock_release_non_nested(struct task_struct
*curr
,
2751 struct lockdep_map
*lock
, unsigned long ip
)
2753 struct held_lock
*hlock
, *prev_hlock
;
2758 * Check whether the lock exists in the current stack
2761 depth
= curr
->lockdep_depth
;
2762 if (DEBUG_LOCKS_WARN_ON(!depth
))
2766 for (i
= depth
-1; i
>= 0; i
--) {
2767 hlock
= curr
->held_locks
+ i
;
2769 * We must not cross into another context:
2771 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2773 if (hlock
->instance
== lock
)
2777 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2780 lock_release_holdtime(hlock
);
2783 * We have the right lock to unlock, 'hlock' points to it.
2784 * Now we remove it from the stack, and add back the other
2785 * entries (if any), recalculating the hash along the way:
2787 curr
->lockdep_depth
= i
;
2788 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2790 for (i
++; i
< depth
; i
++) {
2791 hlock
= curr
->held_locks
+ i
;
2792 if (!__lock_acquire(hlock
->instance
,
2793 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2794 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2795 hlock
->nest_lock
, hlock
->acquire_ip
))
2799 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2805 * Remove the lock to the list of currently held locks - this gets
2806 * called on mutex_unlock()/spin_unlock*() (or on a failed
2807 * mutex_lock_interruptible()). This is done for unlocks that nest
2808 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2810 static int lock_release_nested(struct task_struct
*curr
,
2811 struct lockdep_map
*lock
, unsigned long ip
)
2813 struct held_lock
*hlock
;
2817 * Pop off the top of the lock stack:
2819 depth
= curr
->lockdep_depth
- 1;
2820 hlock
= curr
->held_locks
+ depth
;
2823 * Is the unlock non-nested:
2825 if (hlock
->instance
!= lock
)
2826 return lock_release_non_nested(curr
, lock
, ip
);
2827 curr
->lockdep_depth
--;
2829 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2832 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2834 lock_release_holdtime(hlock
);
2836 #ifdef CONFIG_DEBUG_LOCKDEP
2837 hlock
->prev_chain_key
= 0;
2838 hlock
->class_idx
= 0;
2839 hlock
->acquire_ip
= 0;
2840 hlock
->irq_context
= 0;
2846 * Remove the lock to the list of currently held locks - this gets
2847 * called on mutex_unlock()/spin_unlock*() (or on a failed
2848 * mutex_lock_interruptible()). This is done for unlocks that nest
2849 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2852 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2854 struct task_struct
*curr
= current
;
2856 if (!check_unlock(curr
, lock
, ip
))
2860 if (!lock_release_nested(curr
, lock
, ip
))
2863 if (!lock_release_non_nested(curr
, lock
, ip
))
2867 check_chain_key(curr
);
2871 * Check whether we follow the irq-flags state precisely:
2873 static void check_flags(unsigned long flags
)
2875 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2876 defined(CONFIG_TRACE_IRQFLAGS)
2880 if (irqs_disabled_flags(flags
)) {
2881 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
2882 printk("possible reason: unannotated irqs-off.\n");
2885 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
2886 printk("possible reason: unannotated irqs-on.\n");
2891 * We dont accurately track softirq state in e.g.
2892 * hardirq contexts (such as on 4KSTACKS), so only
2893 * check if not in hardirq contexts:
2895 if (!hardirq_count()) {
2896 if (softirq_count())
2897 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
2899 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
2903 print_irqtrace_events(current
);
2907 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
2908 struct lock_class_key
*key
, unsigned int subclass
,
2911 unsigned long flags
;
2913 if (unlikely(current
->lockdep_recursion
))
2916 raw_local_irq_save(flags
);
2917 current
->lockdep_recursion
= 1;
2919 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
2920 check_chain_key(current
);
2921 current
->lockdep_recursion
= 0;
2922 raw_local_irq_restore(flags
);
2924 EXPORT_SYMBOL_GPL(lock_set_class
);
2927 * We are not always called with irqs disabled - do that here,
2928 * and also avoid lockdep recursion:
2930 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2931 int trylock
, int read
, int check
,
2932 struct lockdep_map
*nest_lock
, unsigned long ip
)
2934 unsigned long flags
;
2936 if (unlikely(current
->lockdep_recursion
))
2939 raw_local_irq_save(flags
);
2942 current
->lockdep_recursion
= 1;
2943 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
2944 irqs_disabled_flags(flags
), nest_lock
, ip
);
2945 current
->lockdep_recursion
= 0;
2946 raw_local_irq_restore(flags
);
2948 EXPORT_SYMBOL_GPL(lock_acquire
);
2950 void lock_release(struct lockdep_map
*lock
, int nested
,
2953 unsigned long flags
;
2955 if (unlikely(current
->lockdep_recursion
))
2958 raw_local_irq_save(flags
);
2960 current
->lockdep_recursion
= 1;
2961 __lock_release(lock
, nested
, ip
);
2962 current
->lockdep_recursion
= 0;
2963 raw_local_irq_restore(flags
);
2965 EXPORT_SYMBOL_GPL(lock_release
);
2967 void lockdep_set_current_reclaim_state(gfp_t gfp_mask
)
2969 current
->lockdep_reclaim_gfp
= gfp_mask
;
2972 void lockdep_clear_current_reclaim_state(void)
2974 current
->lockdep_reclaim_gfp
= 0;
2977 #ifdef CONFIG_LOCK_STAT
2979 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2982 if (!debug_locks_off())
2984 if (debug_locks_silent
)
2987 printk("\n=================================\n");
2988 printk( "[ BUG: bad contention detected! ]\n");
2989 printk( "---------------------------------\n");
2990 printk("%s/%d is trying to contend lock (",
2991 curr
->comm
, task_pid_nr(curr
));
2992 print_lockdep_cache(lock
);
2995 printk("but there are no locks held!\n");
2996 printk("\nother info that might help us debug this:\n");
2997 lockdep_print_held_locks(curr
);
2999 printk("\nstack backtrace:\n");
3006 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3008 struct task_struct
*curr
= current
;
3009 struct held_lock
*hlock
, *prev_hlock
;
3010 struct lock_class_stats
*stats
;
3012 int i
, contention_point
, contending_point
;
3014 depth
= curr
->lockdep_depth
;
3015 if (DEBUG_LOCKS_WARN_ON(!depth
))
3019 for (i
= depth
-1; i
>= 0; i
--) {
3020 hlock
= curr
->held_locks
+ i
;
3022 * We must not cross into another context:
3024 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3026 if (hlock
->instance
== lock
)
3030 print_lock_contention_bug(curr
, lock
, ip
);
3034 hlock
->waittime_stamp
= sched_clock();
3036 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3037 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3040 stats
= get_lock_stats(hlock_class(hlock
));
3041 if (contention_point
< LOCKSTAT_POINTS
)
3042 stats
->contention_point
[contention_point
]++;
3043 if (contending_point
< LOCKSTAT_POINTS
)
3044 stats
->contending_point
[contending_point
]++;
3045 if (lock
->cpu
!= smp_processor_id())
3046 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3047 put_lock_stats(stats
);
3051 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3053 struct task_struct
*curr
= current
;
3054 struct held_lock
*hlock
, *prev_hlock
;
3055 struct lock_class_stats
*stats
;
3061 depth
= curr
->lockdep_depth
;
3062 if (DEBUG_LOCKS_WARN_ON(!depth
))
3066 for (i
= depth
-1; i
>= 0; i
--) {
3067 hlock
= curr
->held_locks
+ i
;
3069 * We must not cross into another context:
3071 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3073 if (hlock
->instance
== lock
)
3077 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3081 cpu
= smp_processor_id();
3082 if (hlock
->waittime_stamp
) {
3083 now
= sched_clock();
3084 waittime
= now
- hlock
->waittime_stamp
;
3085 hlock
->holdtime_stamp
= now
;
3088 stats
= get_lock_stats(hlock_class(hlock
));
3091 lock_time_inc(&stats
->read_waittime
, waittime
);
3093 lock_time_inc(&stats
->write_waittime
, waittime
);
3095 if (lock
->cpu
!= cpu
)
3096 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3097 put_lock_stats(stats
);
3103 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3105 unsigned long flags
;
3107 if (unlikely(!lock_stat
))
3110 if (unlikely(current
->lockdep_recursion
))
3113 raw_local_irq_save(flags
);
3115 current
->lockdep_recursion
= 1;
3116 __lock_contended(lock
, ip
);
3117 current
->lockdep_recursion
= 0;
3118 raw_local_irq_restore(flags
);
3120 EXPORT_SYMBOL_GPL(lock_contended
);
3122 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3124 unsigned long flags
;
3126 if (unlikely(!lock_stat
))
3129 if (unlikely(current
->lockdep_recursion
))
3132 raw_local_irq_save(flags
);
3134 current
->lockdep_recursion
= 1;
3135 __lock_acquired(lock
, ip
);
3136 current
->lockdep_recursion
= 0;
3137 raw_local_irq_restore(flags
);
3139 EXPORT_SYMBOL_GPL(lock_acquired
);
3143 * Used by the testsuite, sanitize the validator state
3144 * after a simulated failure:
3147 void lockdep_reset(void)
3149 unsigned long flags
;
3152 raw_local_irq_save(flags
);
3153 current
->curr_chain_key
= 0;
3154 current
->lockdep_depth
= 0;
3155 current
->lockdep_recursion
= 0;
3156 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3157 nr_hardirq_chains
= 0;
3158 nr_softirq_chains
= 0;
3159 nr_process_chains
= 0;
3161 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3162 INIT_LIST_HEAD(chainhash_table
+ i
);
3163 raw_local_irq_restore(flags
);
3166 static void zap_class(struct lock_class
*class)
3171 * Remove all dependencies this lock is
3174 for (i
= 0; i
< nr_list_entries
; i
++) {
3175 if (list_entries
[i
].class == class)
3176 list_del_rcu(&list_entries
[i
].entry
);
3179 * Unhash the class and remove it from the all_lock_classes list:
3181 list_del_rcu(&class->hash_entry
);
3182 list_del_rcu(&class->lock_entry
);
3187 static inline int within(const void *addr
, void *start
, unsigned long size
)
3189 return addr
>= start
&& addr
< start
+ size
;
3192 void lockdep_free_key_range(void *start
, unsigned long size
)
3194 struct lock_class
*class, *next
;
3195 struct list_head
*head
;
3196 unsigned long flags
;
3200 raw_local_irq_save(flags
);
3201 locked
= graph_lock();
3204 * Unhash all classes that were created by this module:
3206 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3207 head
= classhash_table
+ i
;
3208 if (list_empty(head
))
3210 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3211 if (within(class->key
, start
, size
))
3213 else if (within(class->name
, start
, size
))
3220 raw_local_irq_restore(flags
);
3223 void lockdep_reset_lock(struct lockdep_map
*lock
)
3225 struct lock_class
*class, *next
;
3226 struct list_head
*head
;
3227 unsigned long flags
;
3231 raw_local_irq_save(flags
);
3234 * Remove all classes this lock might have:
3236 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3238 * If the class exists we look it up and zap it:
3240 class = look_up_lock_class(lock
, j
);
3245 * Debug check: in the end all mapped classes should
3248 locked
= graph_lock();
3249 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3250 head
= classhash_table
+ i
;
3251 if (list_empty(head
))
3253 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3254 if (unlikely(class == lock
->class_cache
)) {
3255 if (debug_locks_off_graph_unlock())
3265 raw_local_irq_restore(flags
);
3268 void lockdep_init(void)
3273 * Some architectures have their own start_kernel()
3274 * code which calls lockdep_init(), while we also
3275 * call lockdep_init() from the start_kernel() itself,
3276 * and we want to initialize the hashes only once:
3278 if (lockdep_initialized
)
3281 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3282 INIT_LIST_HEAD(classhash_table
+ i
);
3284 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3285 INIT_LIST_HEAD(chainhash_table
+ i
);
3287 lockdep_initialized
= 1;
3290 void __init
lockdep_info(void)
3292 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3294 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
3295 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
3296 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
3297 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
3298 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
3299 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
3300 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
3302 printk(" memory used by lock dependency info: %lu kB\n",
3303 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
3304 sizeof(struct list_head
) * CLASSHASH_SIZE
+
3305 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
3306 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
3307 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
3309 printk(" per task-struct memory footprint: %lu bytes\n",
3310 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
3312 #ifdef CONFIG_DEBUG_LOCKDEP
3313 if (lockdep_init_error
) {
3314 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3315 printk("Call stack leading to lockdep invocation was:\n");
3316 print_stack_trace(&lockdep_init_trace
, 0);
3322 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
3323 const void *mem_to
, struct held_lock
*hlock
)
3325 if (!debug_locks_off())
3327 if (debug_locks_silent
)
3330 printk("\n=========================\n");
3331 printk( "[ BUG: held lock freed! ]\n");
3332 printk( "-------------------------\n");
3333 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3334 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
3336 lockdep_print_held_locks(curr
);
3338 printk("\nstack backtrace:\n");
3342 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
3343 const void* lock_from
, unsigned long lock_len
)
3345 return lock_from
+ lock_len
<= mem_from
||
3346 mem_from
+ mem_len
<= lock_from
;
3350 * Called when kernel memory is freed (or unmapped), or if a lock
3351 * is destroyed or reinitialized - this code checks whether there is
3352 * any held lock in the memory range of <from> to <to>:
3354 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
3356 struct task_struct
*curr
= current
;
3357 struct held_lock
*hlock
;
3358 unsigned long flags
;
3361 if (unlikely(!debug_locks
))
3364 local_irq_save(flags
);
3365 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3366 hlock
= curr
->held_locks
+ i
;
3368 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
3369 sizeof(*hlock
->instance
)))
3372 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
3375 local_irq_restore(flags
);
3377 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
3379 static void print_held_locks_bug(struct task_struct
*curr
)
3381 if (!debug_locks_off())
3383 if (debug_locks_silent
)
3386 printk("\n=====================================\n");
3387 printk( "[ BUG: lock held at task exit time! ]\n");
3388 printk( "-------------------------------------\n");
3389 printk("%s/%d is exiting with locks still held!\n",
3390 curr
->comm
, task_pid_nr(curr
));
3391 lockdep_print_held_locks(curr
);
3393 printk("\nstack backtrace:\n");
3397 void debug_check_no_locks_held(struct task_struct
*task
)
3399 if (unlikely(task
->lockdep_depth
> 0))
3400 print_held_locks_bug(task
);
3403 void debug_show_all_locks(void)
3405 struct task_struct
*g
, *p
;
3409 if (unlikely(!debug_locks
)) {
3410 printk("INFO: lockdep is turned off.\n");
3413 printk("\nShowing all locks held in the system:\n");
3416 * Here we try to get the tasklist_lock as hard as possible,
3417 * if not successful after 2 seconds we ignore it (but keep
3418 * trying). This is to enable a debug printout even if a
3419 * tasklist_lock-holding task deadlocks or crashes.
3422 if (!read_trylock(&tasklist_lock
)) {
3424 printk("hm, tasklist_lock locked, retrying... ");
3427 printk(" #%d", 10-count
);
3431 printk(" ignoring it.\n");
3435 printk(KERN_CONT
" locked it.\n");
3438 do_each_thread(g
, p
) {
3440 * It's not reliable to print a task's held locks
3441 * if it's not sleeping (or if it's not the current
3444 if (p
->state
== TASK_RUNNING
&& p
!= current
)
3446 if (p
->lockdep_depth
)
3447 lockdep_print_held_locks(p
);
3449 if (read_trylock(&tasklist_lock
))
3451 } while_each_thread(g
, p
);
3454 printk("=============================================\n\n");
3457 read_unlock(&tasklist_lock
);
3459 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
3462 * Careful: only use this function if you are sure that
3463 * the task cannot run in parallel!
3465 void __debug_show_held_locks(struct task_struct
*task
)
3467 if (unlikely(!debug_locks
)) {
3468 printk("INFO: lockdep is turned off.\n");
3471 lockdep_print_held_locks(task
);
3473 EXPORT_SYMBOL_GPL(__debug_show_held_locks
);
3475 void debug_show_held_locks(struct task_struct
*task
)
3477 __debug_show_held_locks(task
);
3479 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
3481 void lockdep_sys_exit(void)
3483 struct task_struct
*curr
= current
;
3485 if (unlikely(curr
->lockdep_depth
)) {
3486 if (!debug_locks_off())
3488 printk("\n================================================\n");
3489 printk( "[ BUG: lock held when returning to user space! ]\n");
3490 printk( "------------------------------------------------\n");
3491 printk("%s/%d is leaving the kernel with locks still held!\n",
3492 curr
->comm
, curr
->pid
);
3493 lockdep_print_held_locks(curr
);