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 #include <linux/mutex.h>
29 #include <linux/sched.h>
30 #include <linux/delay.h>
31 #include <linux/module.h>
32 #include <linux/proc_fs.h>
33 #include <linux/seq_file.h>
34 #include <linux/spinlock.h>
35 #include <linux/kallsyms.h>
36 #include <linux/interrupt.h>
37 #include <linux/stacktrace.h>
38 #include <linux/debug_locks.h>
39 #include <linux/irqflags.h>
40 #include <linux/utsname.h>
41 #include <linux/hash.h>
42 #include <linux/ftrace.h>
44 #include <asm/sections.h>
46 #include "lockdep_internals.h"
48 #ifdef CONFIG_PROVE_LOCKING
49 int prove_locking
= 1;
50 module_param(prove_locking
, int, 0644);
52 #define prove_locking 0
55 #ifdef CONFIG_LOCK_STAT
57 module_param(lock_stat
, int, 0644);
63 * lockdep_lock: protects the lockdep graph, the hashes and the
64 * class/list/hash allocators.
66 * This is one of the rare exceptions where it's justified
67 * to use a raw spinlock - we really dont want the spinlock
68 * code to recurse back into the lockdep code...
70 static raw_spinlock_t lockdep_lock
= (raw_spinlock_t
)__RAW_SPIN_LOCK_UNLOCKED
;
72 static int graph_lock(void)
74 __raw_spin_lock(&lockdep_lock
);
76 * Make sure that if another CPU detected a bug while
77 * walking the graph we dont change it (while the other
78 * CPU is busy printing out stuff with the graph lock
82 __raw_spin_unlock(&lockdep_lock
);
88 static inline int graph_unlock(void)
90 if (debug_locks
&& !__raw_spin_is_locked(&lockdep_lock
))
91 return DEBUG_LOCKS_WARN_ON(1);
93 __raw_spin_unlock(&lockdep_lock
);
98 * Turn lock debugging off and return with 0 if it was off already,
99 * and also release the graph lock:
101 static inline int debug_locks_off_graph_unlock(void)
103 int ret
= debug_locks_off();
105 __raw_spin_unlock(&lockdep_lock
);
110 static int lockdep_initialized
;
112 unsigned long nr_list_entries
;
113 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
116 * All data structures here are protected by the global debug_lock.
118 * Mutex key structs only get allocated, once during bootup, and never
119 * get freed - this significantly simplifies the debugging code.
121 unsigned long nr_lock_classes
;
122 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
124 #ifdef CONFIG_LOCK_STAT
125 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
], lock_stats
);
127 static int lock_contention_point(struct lock_class
*class, unsigned long ip
)
131 for (i
= 0; i
< ARRAY_SIZE(class->contention_point
); i
++) {
132 if (class->contention_point
[i
] == 0) {
133 class->contention_point
[i
] = ip
;
136 if (class->contention_point
[i
] == ip
)
143 static void lock_time_inc(struct lock_time
*lt
, s64 time
)
148 if (time
< lt
->min
|| !lt
->min
)
155 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
157 dst
->min
+= src
->min
;
158 dst
->max
+= src
->max
;
159 dst
->total
+= src
->total
;
163 struct lock_class_stats
lock_stats(struct lock_class
*class)
165 struct lock_class_stats stats
;
168 memset(&stats
, 0, sizeof(struct lock_class_stats
));
169 for_each_possible_cpu(cpu
) {
170 struct lock_class_stats
*pcs
=
171 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
173 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
174 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
176 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
177 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
179 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
180 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
182 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
183 stats
.bounces
[i
] += pcs
->bounces
[i
];
189 void clear_lock_stats(struct lock_class
*class)
193 for_each_possible_cpu(cpu
) {
194 struct lock_class_stats
*cpu_stats
=
195 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
197 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
199 memset(class->contention_point
, 0, sizeof(class->contention_point
));
202 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
204 return &get_cpu_var(lock_stats
)[class - lock_classes
];
207 static void put_lock_stats(struct lock_class_stats
*stats
)
209 put_cpu_var(lock_stats
);
212 static void lock_release_holdtime(struct held_lock
*hlock
)
214 struct lock_class_stats
*stats
;
220 holdtime
= sched_clock() - hlock
->holdtime_stamp
;
222 stats
= get_lock_stats(hlock
->class);
224 lock_time_inc(&stats
->read_holdtime
, holdtime
);
226 lock_time_inc(&stats
->write_holdtime
, holdtime
);
227 put_lock_stats(stats
);
230 static inline void lock_release_holdtime(struct held_lock
*hlock
)
236 * We keep a global list of all lock classes. The list only grows,
237 * never shrinks. The list is only accessed with the lockdep
238 * spinlock lock held.
240 LIST_HEAD(all_lock_classes
);
243 * The lockdep classes are in a hash-table as well, for fast lookup:
245 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
246 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
247 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
248 #define classhashentry(key) (classhash_table + __classhashfn((key)))
250 static struct list_head classhash_table
[CLASSHASH_SIZE
];
253 * We put the lock dependency chains into a hash-table as well, to cache
256 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
257 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
258 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
259 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
261 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
264 * The hash key of the lock dependency chains is a hash itself too:
265 * it's a hash of all locks taken up to that lock, including that lock.
266 * It's a 64-bit hash, because it's important for the keys to be
269 #define iterate_chain_key(key1, key2) \
270 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
271 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
274 notrace
void lockdep_off(void)
276 current
->lockdep_recursion
++;
279 EXPORT_SYMBOL(lockdep_off
);
281 notrace
void lockdep_on(void)
283 current
->lockdep_recursion
--;
286 EXPORT_SYMBOL(lockdep_on
);
289 * Debugging switches:
293 #define VERY_VERBOSE 0
296 # define HARDIRQ_VERBOSE 1
297 # define SOFTIRQ_VERBOSE 1
299 # define HARDIRQ_VERBOSE 0
300 # define SOFTIRQ_VERBOSE 0
303 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
305 * Quick filtering for interesting events:
307 static int class_filter(struct lock_class
*class)
311 if (class->name_version
== 1 &&
312 !strcmp(class->name
, "lockname"))
314 if (class->name_version
== 1 &&
315 !strcmp(class->name
, "&struct->lockfield"))
318 /* Filter everything else. 1 would be to allow everything else */
323 static int verbose(struct lock_class
*class)
326 return class_filter(class);
332 * Stack-trace: tightly packed array of stack backtrace
333 * addresses. Protected by the graph_lock.
335 unsigned long nr_stack_trace_entries
;
336 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
338 static int save_trace(struct stack_trace
*trace
)
340 trace
->nr_entries
= 0;
341 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
342 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
346 save_stack_trace(trace
);
348 trace
->max_entries
= trace
->nr_entries
;
350 nr_stack_trace_entries
+= trace
->nr_entries
;
352 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
353 if (!debug_locks_off_graph_unlock())
356 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
357 printk("turning off the locking correctness validator.\n");
366 unsigned int nr_hardirq_chains
;
367 unsigned int nr_softirq_chains
;
368 unsigned int nr_process_chains
;
369 unsigned int max_lockdep_depth
;
370 unsigned int max_recursion_depth
;
372 #ifdef CONFIG_DEBUG_LOCKDEP
374 * We cannot printk in early bootup code. Not even early_printk()
375 * might work. So we mark any initialization errors and printk
376 * about it later on, in lockdep_info().
378 static int lockdep_init_error
;
379 static unsigned long lockdep_init_trace_data
[20];
380 static struct stack_trace lockdep_init_trace
= {
381 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
382 .entries
= lockdep_init_trace_data
,
386 * Various lockdep statistics:
388 atomic_t chain_lookup_hits
;
389 atomic_t chain_lookup_misses
;
390 atomic_t hardirqs_on_events
;
391 atomic_t hardirqs_off_events
;
392 atomic_t redundant_hardirqs_on
;
393 atomic_t redundant_hardirqs_off
;
394 atomic_t softirqs_on_events
;
395 atomic_t softirqs_off_events
;
396 atomic_t redundant_softirqs_on
;
397 atomic_t redundant_softirqs_off
;
398 atomic_t nr_unused_locks
;
399 atomic_t nr_cyclic_checks
;
400 atomic_t nr_cyclic_check_recursions
;
401 atomic_t nr_find_usage_forwards_checks
;
402 atomic_t nr_find_usage_forwards_recursions
;
403 atomic_t nr_find_usage_backwards_checks
;
404 atomic_t nr_find_usage_backwards_recursions
;
405 # define debug_atomic_inc(ptr) atomic_inc(ptr)
406 # define debug_atomic_dec(ptr) atomic_dec(ptr)
407 # define debug_atomic_read(ptr) atomic_read(ptr)
409 # define debug_atomic_inc(ptr) do { } while (0)
410 # define debug_atomic_dec(ptr) do { } while (0)
411 # define debug_atomic_read(ptr) 0
418 static const char *usage_str
[] =
420 [LOCK_USED
] = "initial-use ",
421 [LOCK_USED_IN_HARDIRQ
] = "in-hardirq-W",
422 [LOCK_USED_IN_SOFTIRQ
] = "in-softirq-W",
423 [LOCK_ENABLED_SOFTIRQS
] = "softirq-on-W",
424 [LOCK_ENABLED_HARDIRQS
] = "hardirq-on-W",
425 [LOCK_USED_IN_HARDIRQ_READ
] = "in-hardirq-R",
426 [LOCK_USED_IN_SOFTIRQ_READ
] = "in-softirq-R",
427 [LOCK_ENABLED_SOFTIRQS_READ
] = "softirq-on-R",
428 [LOCK_ENABLED_HARDIRQS_READ
] = "hardirq-on-R",
431 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
433 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
437 get_usage_chars(struct lock_class
*class, char *c1
, char *c2
, char *c3
, char *c4
)
439 *c1
= '.', *c2
= '.', *c3
= '.', *c4
= '.';
441 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ
)
444 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS
)
447 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ
)
450 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS
)
453 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
455 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ_READ
) {
457 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
461 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
463 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ_READ
) {
465 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
470 static void print_lock_name(struct lock_class
*class)
472 char str
[KSYM_NAME_LEN
], c1
, c2
, c3
, c4
;
475 get_usage_chars(class, &c1
, &c2
, &c3
, &c4
);
479 name
= __get_key_name(class->key
, str
);
480 printk(" (%s", name
);
482 printk(" (%s", name
);
483 if (class->name_version
> 1)
484 printk("#%d", class->name_version
);
486 printk("/%d", class->subclass
);
488 printk("){%c%c%c%c}", c1
, c2
, c3
, c4
);
491 static void print_lockdep_cache(struct lockdep_map
*lock
)
494 char str
[KSYM_NAME_LEN
];
498 name
= __get_key_name(lock
->key
->subkeys
, str
);
503 static void print_lock(struct held_lock
*hlock
)
505 print_lock_name(hlock
->class);
507 print_ip_sym(hlock
->acquire_ip
);
510 static void lockdep_print_held_locks(struct task_struct
*curr
)
512 int i
, depth
= curr
->lockdep_depth
;
515 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
518 printk("%d lock%s held by %s/%d:\n",
519 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
521 for (i
= 0; i
< depth
; i
++) {
523 print_lock(curr
->held_locks
+ i
);
527 static void print_lock_class_header(struct lock_class
*class, int depth
)
531 printk("%*s->", depth
, "");
532 print_lock_name(class);
533 printk(" ops: %lu", class->ops
);
536 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
537 if (class->usage_mask
& (1 << bit
)) {
540 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
541 len
+= printk(" at:\n");
542 print_stack_trace(class->usage_traces
+ bit
, len
);
545 printk("%*s }\n", depth
, "");
547 printk("%*s ... key at: ",depth
,"");
548 print_ip_sym((unsigned long)class->key
);
552 * printk all lock dependencies starting at <entry>:
554 static void print_lock_dependencies(struct lock_class
*class, int depth
)
556 struct lock_list
*entry
;
558 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
561 print_lock_class_header(class, depth
);
563 list_for_each_entry(entry
, &class->locks_after
, entry
) {
564 if (DEBUG_LOCKS_WARN_ON(!entry
->class))
567 print_lock_dependencies(entry
->class, depth
+ 1);
569 printk("%*s ... acquired at:\n",depth
,"");
570 print_stack_trace(&entry
->trace
, 2);
575 static void print_kernel_version(void)
577 printk("%s %.*s\n", init_utsname()->release
,
578 (int)strcspn(init_utsname()->version
, " "),
579 init_utsname()->version
);
582 static int very_verbose(struct lock_class
*class)
585 return class_filter(class);
591 * Is this the address of a static object:
593 static int static_obj(void *obj
)
595 unsigned long start
= (unsigned long) &_stext
,
596 end
= (unsigned long) &_end
,
597 addr
= (unsigned long) obj
;
605 if ((addr
>= start
) && (addr
< end
))
612 for_each_possible_cpu(i
) {
613 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
614 end
= (unsigned long) &__per_cpu_start
+ PERCPU_ENOUGH_ROOM
617 if ((addr
>= start
) && (addr
< end
))
625 return is_module_address(addr
);
629 * To make lock name printouts unique, we calculate a unique
630 * class->name_version generation counter:
632 static int count_matching_names(struct lock_class
*new_class
)
634 struct lock_class
*class;
637 if (!new_class
->name
)
640 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
641 if (new_class
->key
- new_class
->subclass
== class->key
)
642 return class->name_version
;
643 if (class->name
&& !strcmp(class->name
, new_class
->name
))
644 count
= max(count
, class->name_version
);
651 * Register a lock's class in the hash-table, if the class is not present
652 * yet. Otherwise we look it up. We cache the result in the lock object
653 * itself, so actual lookup of the hash should be once per lock object.
655 static inline struct lock_class
*
656 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
658 struct lockdep_subclass_key
*key
;
659 struct list_head
*hash_head
;
660 struct lock_class
*class;
662 #ifdef CONFIG_DEBUG_LOCKDEP
664 * If the architecture calls into lockdep before initializing
665 * the hashes then we'll warn about it later. (we cannot printk
668 if (unlikely(!lockdep_initialized
)) {
670 lockdep_init_error
= 1;
671 save_stack_trace(&lockdep_init_trace
);
676 * Static locks do not have their class-keys yet - for them the key
677 * is the lock object itself:
679 if (unlikely(!lock
->key
))
680 lock
->key
= (void *)lock
;
683 * NOTE: the class-key must be unique. For dynamic locks, a static
684 * lock_class_key variable is passed in through the mutex_init()
685 * (or spin_lock_init()) call - which acts as the key. For static
686 * locks we use the lock object itself as the key.
688 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
689 sizeof(struct lockdep_map
));
691 key
= lock
->key
->subkeys
+ subclass
;
693 hash_head
= classhashentry(key
);
696 * We can walk the hash lockfree, because the hash only
697 * grows, and we are careful when adding entries to the end:
699 list_for_each_entry(class, hash_head
, hash_entry
) {
700 if (class->key
== key
) {
701 WARN_ON_ONCE(class->name
!= lock
->name
);
710 * Register a lock's class in the hash-table, if the class is not present
711 * yet. Otherwise we look it up. We cache the result in the lock object
712 * itself, so actual lookup of the hash should be once per lock object.
714 static inline struct lock_class
*
715 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
717 struct lockdep_subclass_key
*key
;
718 struct list_head
*hash_head
;
719 struct lock_class
*class;
722 class = look_up_lock_class(lock
, subclass
);
727 * Debug-check: all keys must be persistent!
729 if (!static_obj(lock
->key
)) {
731 printk("INFO: trying to register non-static key.\n");
732 printk("the code is fine but needs lockdep annotation.\n");
733 printk("turning off the locking correctness validator.\n");
739 key
= lock
->key
->subkeys
+ subclass
;
740 hash_head
= classhashentry(key
);
742 raw_local_irq_save(flags
);
744 raw_local_irq_restore(flags
);
748 * We have to do the hash-walk again, to avoid races
751 list_for_each_entry(class, hash_head
, hash_entry
)
752 if (class->key
== key
)
755 * Allocate a new key from the static array, and add it to
758 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
759 if (!debug_locks_off_graph_unlock()) {
760 raw_local_irq_restore(flags
);
763 raw_local_irq_restore(flags
);
765 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
766 printk("turning off the locking correctness validator.\n");
769 class = lock_classes
+ nr_lock_classes
++;
770 debug_atomic_inc(&nr_unused_locks
);
772 class->name
= lock
->name
;
773 class->subclass
= subclass
;
774 INIT_LIST_HEAD(&class->lock_entry
);
775 INIT_LIST_HEAD(&class->locks_before
);
776 INIT_LIST_HEAD(&class->locks_after
);
777 class->name_version
= count_matching_names(class);
779 * We use RCU's safe list-add method to make
780 * parallel walking of the hash-list safe:
782 list_add_tail_rcu(&class->hash_entry
, hash_head
);
784 * Add it to the global list of classes:
786 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
788 if (verbose(class)) {
790 raw_local_irq_restore(flags
);
792 printk("\nnew class %p: %s", class->key
, class->name
);
793 if (class->name_version
> 1)
794 printk("#%d", class->name_version
);
798 raw_local_irq_save(flags
);
800 raw_local_irq_restore(flags
);
806 raw_local_irq_restore(flags
);
808 if (!subclass
|| force
)
809 lock
->class_cache
= class;
811 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
817 #ifdef CONFIG_PROVE_LOCKING
819 * Allocate a lockdep entry. (assumes the graph_lock held, returns
820 * with NULL on failure)
822 static struct lock_list
*alloc_list_entry(void)
824 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
825 if (!debug_locks_off_graph_unlock())
828 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
829 printk("turning off the locking correctness validator.\n");
832 return list_entries
+ nr_list_entries
++;
836 * Add a new dependency to the head of the list:
838 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
839 struct list_head
*head
, unsigned long ip
, int distance
)
841 struct lock_list
*entry
;
843 * Lock not present yet - get a new dependency struct and
844 * add it to the list:
846 entry
= alloc_list_entry();
851 entry
->distance
= distance
;
852 if (!save_trace(&entry
->trace
))
856 * Since we never remove from the dependency list, the list can
857 * be walked lockless by other CPUs, it's only allocation
858 * that must be protected by the spinlock. But this also means
859 * we must make new entries visible only once writes to the
860 * entry become visible - hence the RCU op:
862 list_add_tail_rcu(&entry
->entry
, head
);
868 * Recursive, forwards-direction lock-dependency checking, used for
869 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
872 * (to keep the stackframe of the recursive functions small we
873 * use these global variables, and we also mark various helper
874 * functions as noinline.)
876 static struct held_lock
*check_source
, *check_target
;
879 * Print a dependency chain entry (this is only done when a deadlock
880 * has been detected):
883 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
885 if (debug_locks_silent
)
887 printk("\n-> #%u", depth
);
888 print_lock_name(target
->class);
890 print_stack_trace(&target
->trace
, 6);
896 * When a circular dependency is detected, print the
900 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
)
902 struct task_struct
*curr
= current
;
904 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
907 printk("\n=======================================================\n");
908 printk( "[ INFO: possible circular locking dependency detected ]\n");
909 print_kernel_version();
910 printk( "-------------------------------------------------------\n");
911 printk("%s/%d is trying to acquire lock:\n",
912 curr
->comm
, task_pid_nr(curr
));
913 print_lock(check_source
);
914 printk("\nbut task is already holding lock:\n");
915 print_lock(check_target
);
916 printk("\nwhich lock already depends on the new lock.\n\n");
917 printk("\nthe existing dependency chain (in reverse order) is:\n");
919 print_circular_bug_entry(entry
, depth
);
924 static noinline
int print_circular_bug_tail(void)
926 struct task_struct
*curr
= current
;
927 struct lock_list
this;
929 if (debug_locks_silent
)
932 this.class = check_source
->class;
933 if (!save_trace(&this.trace
))
936 print_circular_bug_entry(&this, 0);
938 printk("\nother info that might help us debug this:\n\n");
939 lockdep_print_held_locks(curr
);
941 printk("\nstack backtrace:\n");
947 #define RECURSION_LIMIT 40
949 static int noinline
print_infinite_recursion_bug(void)
951 if (!debug_locks_off_graph_unlock())
960 * Prove that the dependency graph starting at <entry> can not
961 * lead to <target>. Print an error and return 0 if it does.
964 check_noncircular(struct lock_class
*source
, unsigned int depth
)
966 struct lock_list
*entry
;
968 debug_atomic_inc(&nr_cyclic_check_recursions
);
969 if (depth
> max_recursion_depth
)
970 max_recursion_depth
= depth
;
971 if (depth
>= RECURSION_LIMIT
)
972 return print_infinite_recursion_bug();
974 * Check this lock's dependency list:
976 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
977 if (entry
->class == check_target
->class)
978 return print_circular_bug_header(entry
, depth
+1);
979 debug_atomic_inc(&nr_cyclic_checks
);
980 if (!check_noncircular(entry
->class, depth
+1))
981 return print_circular_bug_entry(entry
, depth
+1);
986 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
988 * Forwards and backwards subgraph searching, for the purposes of
989 * proving that two subgraphs can be connected by a new dependency
990 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
992 static enum lock_usage_bit find_usage_bit
;
993 static struct lock_class
*forwards_match
, *backwards_match
;
996 * Find a node in the forwards-direction dependency sub-graph starting
997 * at <source> that matches <find_usage_bit>.
999 * Return 2 if such a node exists in the subgraph, and put that node
1000 * into <forwards_match>.
1002 * Return 1 otherwise and keep <forwards_match> unchanged.
1003 * Return 0 on error.
1006 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
1008 struct lock_list
*entry
;
1011 if (depth
> max_recursion_depth
)
1012 max_recursion_depth
= depth
;
1013 if (depth
>= RECURSION_LIMIT
)
1014 return print_infinite_recursion_bug();
1016 debug_atomic_inc(&nr_find_usage_forwards_checks
);
1017 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1018 forwards_match
= source
;
1023 * Check this lock's dependency list:
1025 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1026 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
1027 ret
= find_usage_forwards(entry
->class, depth
+1);
1028 if (ret
== 2 || ret
== 0)
1035 * Find a node in the backwards-direction dependency sub-graph starting
1036 * at <source> that matches <find_usage_bit>.
1038 * Return 2 if such a node exists in the subgraph, and put that node
1039 * into <backwards_match>.
1041 * Return 1 otherwise and keep <backwards_match> unchanged.
1042 * Return 0 on error.
1044 static noinline notrace
int
1045 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
1047 struct lock_list
*entry
;
1050 if (!__raw_spin_is_locked(&lockdep_lock
))
1051 return DEBUG_LOCKS_WARN_ON(1);
1053 if (depth
> max_recursion_depth
)
1054 max_recursion_depth
= depth
;
1055 if (depth
>= RECURSION_LIMIT
)
1056 return print_infinite_recursion_bug();
1058 debug_atomic_inc(&nr_find_usage_backwards_checks
);
1059 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1060 backwards_match
= source
;
1065 * Check this lock's dependency list:
1067 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
1068 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
1069 ret
= find_usage_backwards(entry
->class, depth
+1);
1070 if (ret
== 2 || ret
== 0)
1077 print_bad_irq_dependency(struct task_struct
*curr
,
1078 struct held_lock
*prev
,
1079 struct held_lock
*next
,
1080 enum lock_usage_bit bit1
,
1081 enum lock_usage_bit bit2
,
1082 const char *irqclass
)
1084 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1087 printk("\n======================================================\n");
1088 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1089 irqclass
, irqclass
);
1090 print_kernel_version();
1091 printk( "------------------------------------------------------\n");
1092 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1093 curr
->comm
, task_pid_nr(curr
),
1094 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1095 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1096 curr
->hardirqs_enabled
,
1097 curr
->softirqs_enabled
);
1100 printk("\nand this task is already holding:\n");
1102 printk("which would create a new lock dependency:\n");
1103 print_lock_name(prev
->class);
1105 print_lock_name(next
->class);
1108 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1110 print_lock_name(backwards_match
);
1111 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1113 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
1115 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1116 print_lock_name(forwards_match
);
1117 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1120 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
1122 printk("\nother info that might help us debug this:\n\n");
1123 lockdep_print_held_locks(curr
);
1125 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
1126 print_lock_dependencies(backwards_match
, 0);
1128 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
1129 print_lock_dependencies(forwards_match
, 0);
1131 printk("\nstack backtrace:\n");
1138 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1139 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1140 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1144 find_usage_bit
= bit_backwards
;
1145 /* fills in <backwards_match> */
1146 ret
= find_usage_backwards(prev
->class, 0);
1147 if (!ret
|| ret
== 1)
1150 find_usage_bit
= bit_forwards
;
1151 ret
= find_usage_forwards(next
->class, 0);
1152 if (!ret
|| ret
== 1)
1155 return print_bad_irq_dependency(curr
, prev
, next
,
1156 bit_backwards
, bit_forwards
, irqclass
);
1160 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1161 struct held_lock
*next
)
1164 * Prove that the new dependency does not connect a hardirq-safe
1165 * lock with a hardirq-unsafe lock - to achieve this we search
1166 * the backwards-subgraph starting at <prev>, and the
1167 * forwards-subgraph starting at <next>:
1169 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ
,
1170 LOCK_ENABLED_HARDIRQS
, "hard"))
1174 * Prove that the new dependency does not connect a hardirq-safe-read
1175 * lock with a hardirq-unsafe lock - to achieve this we search
1176 * the backwards-subgraph starting at <prev>, and the
1177 * forwards-subgraph starting at <next>:
1179 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ_READ
,
1180 LOCK_ENABLED_HARDIRQS
, "hard-read"))
1184 * Prove that the new dependency does not connect a softirq-safe
1185 * lock with a softirq-unsafe lock - to achieve this we search
1186 * the backwards-subgraph starting at <prev>, and the
1187 * forwards-subgraph starting at <next>:
1189 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ
,
1190 LOCK_ENABLED_SOFTIRQS
, "soft"))
1193 * Prove that the new dependency does not connect a softirq-safe-read
1194 * lock with a softirq-unsafe lock - to achieve this we search
1195 * the backwards-subgraph starting at <prev>, and the
1196 * forwards-subgraph starting at <next>:
1198 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ_READ
,
1199 LOCK_ENABLED_SOFTIRQS
, "soft"))
1205 static void inc_chains(void)
1207 if (current
->hardirq_context
)
1208 nr_hardirq_chains
++;
1210 if (current
->softirq_context
)
1211 nr_softirq_chains
++;
1213 nr_process_chains
++;
1220 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1221 struct held_lock
*next
)
1226 static inline void inc_chains(void)
1228 nr_process_chains
++;
1234 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1235 struct held_lock
*next
)
1237 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1240 printk("\n=============================================\n");
1241 printk( "[ INFO: possible recursive locking detected ]\n");
1242 print_kernel_version();
1243 printk( "---------------------------------------------\n");
1244 printk("%s/%d is trying to acquire lock:\n",
1245 curr
->comm
, task_pid_nr(curr
));
1247 printk("\nbut task is already holding lock:\n");
1250 printk("\nother info that might help us debug this:\n");
1251 lockdep_print_held_locks(curr
);
1253 printk("\nstack backtrace:\n");
1260 * Check whether we are holding such a class already.
1262 * (Note that this has to be done separately, because the graph cannot
1263 * detect such classes of deadlocks.)
1265 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1268 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1269 struct lockdep_map
*next_instance
, int read
)
1271 struct held_lock
*prev
;
1274 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1275 prev
= curr
->held_locks
+ i
;
1276 if (prev
->class != next
->class)
1279 * Allow read-after-read recursion of the same
1280 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1282 if ((read
== 2) && prev
->read
)
1284 return print_deadlock_bug(curr
, prev
, next
);
1290 * There was a chain-cache miss, and we are about to add a new dependency
1291 * to a previous lock. We recursively validate the following rules:
1293 * - would the adding of the <prev> -> <next> dependency create a
1294 * circular dependency in the graph? [== circular deadlock]
1296 * - does the new prev->next dependency connect any hardirq-safe lock
1297 * (in the full backwards-subgraph starting at <prev>) with any
1298 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1299 * <next>)? [== illegal lock inversion with hardirq contexts]
1301 * - does the new prev->next dependency connect any softirq-safe lock
1302 * (in the full backwards-subgraph starting at <prev>) with any
1303 * softirq-unsafe lock (in the full forwards-subgraph starting at
1304 * <next>)? [== illegal lock inversion with softirq contexts]
1306 * any of these scenarios could lead to a deadlock.
1308 * Then if all the validations pass, we add the forwards and backwards
1312 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1313 struct held_lock
*next
, int distance
)
1315 struct lock_list
*entry
;
1319 * Prove that the new <prev> -> <next> dependency would not
1320 * create a circular dependency in the graph. (We do this by
1321 * forward-recursing into the graph starting at <next>, and
1322 * checking whether we can reach <prev>.)
1324 * We are using global variables to control the recursion, to
1325 * keep the stackframe size of the recursive functions low:
1327 check_source
= next
;
1328 check_target
= prev
;
1329 if (!(check_noncircular(next
->class, 0)))
1330 return print_circular_bug_tail();
1332 if (!check_prev_add_irq(curr
, prev
, next
))
1336 * For recursive read-locks we do all the dependency checks,
1337 * but we dont store read-triggered dependencies (only
1338 * write-triggered dependencies). This ensures that only the
1339 * write-side dependencies matter, and that if for example a
1340 * write-lock never takes any other locks, then the reads are
1341 * equivalent to a NOP.
1343 if (next
->read
== 2 || prev
->read
== 2)
1346 * Is the <prev> -> <next> dependency already present?
1348 * (this may occur even though this is a new chain: consider
1349 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1350 * chains - the second one will be new, but L1 already has
1351 * L2 added to its dependency list, due to the first chain.)
1353 list_for_each_entry(entry
, &prev
->class->locks_after
, entry
) {
1354 if (entry
->class == next
->class) {
1356 entry
->distance
= 1;
1362 * Ok, all validations passed, add the new lock
1363 * to the previous lock's dependency list:
1365 ret
= add_lock_to_list(prev
->class, next
->class,
1366 &prev
->class->locks_after
, next
->acquire_ip
, distance
);
1371 ret
= add_lock_to_list(next
->class, prev
->class,
1372 &next
->class->locks_before
, next
->acquire_ip
, distance
);
1377 * Debugging printouts:
1379 if (verbose(prev
->class) || verbose(next
->class)) {
1381 printk("\n new dependency: ");
1382 print_lock_name(prev
->class);
1384 print_lock_name(next
->class);
1387 return graph_lock();
1393 * Add the dependency to all directly-previous locks that are 'relevant'.
1394 * The ones that are relevant are (in increasing distance from curr):
1395 * all consecutive trylock entries and the final non-trylock entry - or
1396 * the end of this context's lock-chain - whichever comes first.
1399 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1401 int depth
= curr
->lockdep_depth
;
1402 struct held_lock
*hlock
;
1407 * Depth must not be zero for a non-head lock:
1412 * At least two relevant locks must exist for this
1415 if (curr
->held_locks
[depth
].irq_context
!=
1416 curr
->held_locks
[depth
-1].irq_context
)
1420 int distance
= curr
->lockdep_depth
- depth
+ 1;
1421 hlock
= curr
->held_locks
+ depth
-1;
1423 * Only non-recursive-read entries get new dependencies
1426 if (hlock
->read
!= 2) {
1427 if (!check_prev_add(curr
, hlock
, next
, distance
))
1430 * Stop after the first non-trylock entry,
1431 * as non-trylock entries have added their
1432 * own direct dependencies already, so this
1433 * lock is connected to them indirectly:
1435 if (!hlock
->trylock
)
1440 * End of lock-stack?
1445 * Stop the search if we cross into another context:
1447 if (curr
->held_locks
[depth
].irq_context
!=
1448 curr
->held_locks
[depth
-1].irq_context
)
1453 if (!debug_locks_off_graph_unlock())
1461 unsigned long nr_lock_chains
;
1462 static struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1465 * Look up a dependency chain. If the key is not present yet then
1466 * add it and return 1 - in this case the new dependency chain is
1467 * validated. If the key is already hashed, return 0.
1468 * (On return with 1 graph_lock is held.)
1470 static inline int lookup_chain_cache(u64 chain_key
, struct lock_class
*class)
1472 struct list_head
*hash_head
= chainhashentry(chain_key
);
1473 struct lock_chain
*chain
;
1475 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1478 * We can walk it lock-free, because entries only get added
1481 list_for_each_entry(chain
, hash_head
, entry
) {
1482 if (chain
->chain_key
== chain_key
) {
1484 debug_atomic_inc(&chain_lookup_hits
);
1485 if (very_verbose(class))
1486 printk("\nhash chain already cached, key: "
1487 "%016Lx tail class: [%p] %s\n",
1488 (unsigned long long)chain_key
,
1489 class->key
, class->name
);
1493 if (very_verbose(class))
1494 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1495 (unsigned long long)chain_key
, class->key
, class->name
);
1497 * Allocate a new chain entry from the static array, and add
1503 * We have to walk the chain again locked - to avoid duplicates:
1505 list_for_each_entry(chain
, hash_head
, entry
) {
1506 if (chain
->chain_key
== chain_key
) {
1511 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1512 if (!debug_locks_off_graph_unlock())
1515 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1516 printk("turning off the locking correctness validator.\n");
1519 chain
= lock_chains
+ nr_lock_chains
++;
1520 chain
->chain_key
= chain_key
;
1521 list_add_tail_rcu(&chain
->entry
, hash_head
);
1522 debug_atomic_inc(&chain_lookup_misses
);
1528 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
1529 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
1532 * Trylock needs to maintain the stack of held locks, but it
1533 * does not add new dependencies, because trylock can be done
1536 * We look up the chain_key and do the O(N^2) check and update of
1537 * the dependencies only if this is a new dependency chain.
1538 * (If lookup_chain_cache() returns with 1 it acquires
1539 * graph_lock for us)
1541 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
1542 lookup_chain_cache(chain_key
, hlock
->class)) {
1544 * Check whether last held lock:
1546 * - is irq-safe, if this lock is irq-unsafe
1547 * - is softirq-safe, if this lock is hardirq-unsafe
1549 * And check whether the new lock's dependency graph
1550 * could lead back to the previous lock.
1552 * any of these scenarios could lead to a deadlock. If
1555 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
1560 * Mark recursive read, as we jump over it when
1561 * building dependencies (just like we jump over
1567 * Add dependency only if this lock is not the head
1568 * of the chain, and if it's not a secondary read-lock:
1570 if (!chain_head
&& ret
!= 2)
1571 if (!check_prevs_add(curr
, hlock
))
1575 /* after lookup_chain_cache(): */
1576 if (unlikely(!debug_locks
))
1582 static inline int validate_chain(struct task_struct
*curr
,
1583 struct lockdep_map
*lock
, struct held_lock
*hlock
,
1584 int chain_head
, u64 chain_key
)
1591 * We are building curr_chain_key incrementally, so double-check
1592 * it from scratch, to make sure that it's done correctly:
1594 static notrace
void check_chain_key(struct task_struct
*curr
)
1596 #ifdef CONFIG_DEBUG_LOCKDEP
1597 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1601 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1602 hlock
= curr
->held_locks
+ i
;
1603 if (chain_key
!= hlock
->prev_chain_key
) {
1605 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1606 curr
->lockdep_depth
, i
,
1607 (unsigned long long)chain_key
,
1608 (unsigned long long)hlock
->prev_chain_key
);
1612 id
= hlock
->class - lock_classes
;
1613 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
1616 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1617 hlock
->irq_context
))
1619 chain_key
= iterate_chain_key(chain_key
, id
);
1622 if (chain_key
!= curr
->curr_chain_key
) {
1624 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1625 curr
->lockdep_depth
, i
,
1626 (unsigned long long)chain_key
,
1627 (unsigned long long)curr
->curr_chain_key
);
1634 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1635 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1637 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1640 printk("\n=================================\n");
1641 printk( "[ INFO: inconsistent lock state ]\n");
1642 print_kernel_version();
1643 printk( "---------------------------------\n");
1645 printk("inconsistent {%s} -> {%s} usage.\n",
1646 usage_str
[prev_bit
], usage_str
[new_bit
]);
1648 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1649 curr
->comm
, task_pid_nr(curr
),
1650 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1651 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1652 trace_hardirqs_enabled(curr
),
1653 trace_softirqs_enabled(curr
));
1656 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1657 print_stack_trace(this->class->usage_traces
+ prev_bit
, 1);
1659 print_irqtrace_events(curr
);
1660 printk("\nother info that might help us debug this:\n");
1661 lockdep_print_held_locks(curr
);
1663 printk("\nstack backtrace:\n");
1670 * Print out an error if an invalid bit is set:
1673 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1674 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1676 if (unlikely(this->class->usage_mask
& (1 << bad_bit
)))
1677 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1681 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1682 enum lock_usage_bit new_bit
);
1684 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1687 * print irq inversion bug:
1690 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
1691 struct held_lock
*this, int forwards
,
1692 const char *irqclass
)
1694 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1697 printk("\n=========================================================\n");
1698 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1699 print_kernel_version();
1700 printk( "---------------------------------------------------------\n");
1701 printk("%s/%d just changed the state of lock:\n",
1702 curr
->comm
, task_pid_nr(curr
));
1705 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass
);
1707 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass
);
1708 print_lock_name(other
);
1709 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1711 printk("\nother info that might help us debug this:\n");
1712 lockdep_print_held_locks(curr
);
1714 printk("\nthe first lock's dependencies:\n");
1715 print_lock_dependencies(this->class, 0);
1717 printk("\nthe second lock's dependencies:\n");
1718 print_lock_dependencies(other
, 0);
1720 printk("\nstack backtrace:\n");
1727 * Prove that in the forwards-direction subgraph starting at <this>
1728 * there is no lock matching <mask>:
1731 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
1732 enum lock_usage_bit bit
, const char *irqclass
)
1736 find_usage_bit
= bit
;
1737 /* fills in <forwards_match> */
1738 ret
= find_usage_forwards(this->class, 0);
1739 if (!ret
|| ret
== 1)
1742 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
1746 * Prove that in the backwards-direction subgraph starting at <this>
1747 * there is no lock matching <mask>:
1750 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
1751 enum lock_usage_bit bit
, const char *irqclass
)
1755 find_usage_bit
= bit
;
1756 /* fills in <backwards_match> */
1757 ret
= find_usage_backwards(this->class, 0);
1758 if (!ret
|| ret
== 1)
1761 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
1764 void print_irqtrace_events(struct task_struct
*curr
)
1766 printk("irq event stamp: %u\n", curr
->irq_events
);
1767 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
1768 print_ip_sym(curr
->hardirq_enable_ip
);
1769 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
1770 print_ip_sym(curr
->hardirq_disable_ip
);
1771 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
1772 print_ip_sym(curr
->softirq_enable_ip
);
1773 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
1774 print_ip_sym(curr
->softirq_disable_ip
);
1777 static int hardirq_verbose(struct lock_class
*class)
1780 return class_filter(class);
1785 static int softirq_verbose(struct lock_class
*class)
1788 return class_filter(class);
1793 #define STRICT_READ_CHECKS 1
1795 static int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
1796 enum lock_usage_bit new_bit
)
1801 case LOCK_USED_IN_HARDIRQ
:
1802 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1804 if (!valid_state(curr
, this, new_bit
,
1805 LOCK_ENABLED_HARDIRQS_READ
))
1808 * just marked it hardirq-safe, check that this lock
1809 * took no hardirq-unsafe lock in the past:
1811 if (!check_usage_forwards(curr
, this,
1812 LOCK_ENABLED_HARDIRQS
, "hard"))
1814 #if STRICT_READ_CHECKS
1816 * just marked it hardirq-safe, check that this lock
1817 * took no hardirq-unsafe-read lock in the past:
1819 if (!check_usage_forwards(curr
, this,
1820 LOCK_ENABLED_HARDIRQS_READ
, "hard-read"))
1823 if (hardirq_verbose(this->class))
1826 case LOCK_USED_IN_SOFTIRQ
:
1827 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1829 if (!valid_state(curr
, this, new_bit
,
1830 LOCK_ENABLED_SOFTIRQS_READ
))
1833 * just marked it softirq-safe, check that this lock
1834 * took no softirq-unsafe lock in the past:
1836 if (!check_usage_forwards(curr
, this,
1837 LOCK_ENABLED_SOFTIRQS
, "soft"))
1839 #if STRICT_READ_CHECKS
1841 * just marked it softirq-safe, check that this lock
1842 * took no softirq-unsafe-read lock in the past:
1844 if (!check_usage_forwards(curr
, this,
1845 LOCK_ENABLED_SOFTIRQS_READ
, "soft-read"))
1848 if (softirq_verbose(this->class))
1851 case LOCK_USED_IN_HARDIRQ_READ
:
1852 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1855 * just marked it hardirq-read-safe, check that this lock
1856 * took no hardirq-unsafe lock in the past:
1858 if (!check_usage_forwards(curr
, this,
1859 LOCK_ENABLED_HARDIRQS
, "hard"))
1861 if (hardirq_verbose(this->class))
1864 case LOCK_USED_IN_SOFTIRQ_READ
:
1865 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1868 * just marked it softirq-read-safe, check that this lock
1869 * took no softirq-unsafe lock in the past:
1871 if (!check_usage_forwards(curr
, this,
1872 LOCK_ENABLED_SOFTIRQS
, "soft"))
1874 if (softirq_verbose(this->class))
1877 case LOCK_ENABLED_HARDIRQS
:
1878 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1880 if (!valid_state(curr
, this, new_bit
,
1881 LOCK_USED_IN_HARDIRQ_READ
))
1884 * just marked it hardirq-unsafe, check that no hardirq-safe
1885 * lock in the system ever took it in the past:
1887 if (!check_usage_backwards(curr
, this,
1888 LOCK_USED_IN_HARDIRQ
, "hard"))
1890 #if STRICT_READ_CHECKS
1892 * just marked it hardirq-unsafe, check that no
1893 * hardirq-safe-read lock in the system ever took
1896 if (!check_usage_backwards(curr
, this,
1897 LOCK_USED_IN_HARDIRQ_READ
, "hard-read"))
1900 if (hardirq_verbose(this->class))
1903 case LOCK_ENABLED_SOFTIRQS
:
1904 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1906 if (!valid_state(curr
, this, new_bit
,
1907 LOCK_USED_IN_SOFTIRQ_READ
))
1910 * just marked it softirq-unsafe, check that no softirq-safe
1911 * lock in the system ever took it in the past:
1913 if (!check_usage_backwards(curr
, this,
1914 LOCK_USED_IN_SOFTIRQ
, "soft"))
1916 #if STRICT_READ_CHECKS
1918 * just marked it softirq-unsafe, check that no
1919 * softirq-safe-read lock in the system ever took
1922 if (!check_usage_backwards(curr
, this,
1923 LOCK_USED_IN_SOFTIRQ_READ
, "soft-read"))
1926 if (softirq_verbose(this->class))
1929 case LOCK_ENABLED_HARDIRQS_READ
:
1930 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1932 #if STRICT_READ_CHECKS
1934 * just marked it hardirq-read-unsafe, check that no
1935 * hardirq-safe lock in the system ever took it in the past:
1937 if (!check_usage_backwards(curr
, this,
1938 LOCK_USED_IN_HARDIRQ
, "hard"))
1941 if (hardirq_verbose(this->class))
1944 case LOCK_ENABLED_SOFTIRQS_READ
:
1945 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1947 #if STRICT_READ_CHECKS
1949 * just marked it softirq-read-unsafe, check that no
1950 * softirq-safe lock in the system ever took it in the past:
1952 if (!check_usage_backwards(curr
, this,
1953 LOCK_USED_IN_SOFTIRQ
, "soft"))
1956 if (softirq_verbose(this->class))
1968 * Mark all held locks with a usage bit:
1971 mark_held_locks(struct task_struct
*curr
, int hardirq
)
1973 enum lock_usage_bit usage_bit
;
1974 struct held_lock
*hlock
;
1977 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1978 hlock
= curr
->held_locks
+ i
;
1982 usage_bit
= LOCK_ENABLED_HARDIRQS_READ
;
1984 usage_bit
= LOCK_ENABLED_HARDIRQS
;
1987 usage_bit
= LOCK_ENABLED_SOFTIRQS_READ
;
1989 usage_bit
= LOCK_ENABLED_SOFTIRQS
;
1991 if (!mark_lock(curr
, hlock
, usage_bit
))
1999 * Debugging helper: via this flag we know that we are in
2000 * 'early bootup code', and will warn about any invalid irqs-on event:
2002 static int early_boot_irqs_enabled
;
2004 void early_boot_irqs_off(void)
2006 early_boot_irqs_enabled
= 0;
2009 void early_boot_irqs_on(void)
2011 early_boot_irqs_enabled
= 1;
2015 * Hardirqs will be enabled:
2017 void notrace
trace_hardirqs_on_caller(unsigned long a0
)
2019 struct task_struct
*curr
= current
;
2022 time_hardirqs_on(CALLER_ADDR0
, a0
);
2024 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2027 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
2030 if (unlikely(curr
->hardirqs_enabled
)) {
2031 debug_atomic_inc(&redundant_hardirqs_on
);
2034 /* we'll do an OFF -> ON transition: */
2035 curr
->hardirqs_enabled
= 1;
2036 ip
= (unsigned long) __builtin_return_address(0);
2038 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2040 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2043 * We are going to turn hardirqs on, so set the
2044 * usage bit for all held locks:
2046 if (!mark_held_locks(curr
, 1))
2049 * If we have softirqs enabled, then set the usage
2050 * bit for all held locks. (disabled hardirqs prevented
2051 * this bit from being set before)
2053 if (curr
->softirqs_enabled
)
2054 if (!mark_held_locks(curr
, 0))
2057 curr
->hardirq_enable_ip
= ip
;
2058 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2059 debug_atomic_inc(&hardirqs_on_events
);
2061 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2063 void notrace
trace_hardirqs_on(void)
2065 trace_hardirqs_on_caller(CALLER_ADDR0
);
2067 EXPORT_SYMBOL(trace_hardirqs_on
);
2070 * Hardirqs were disabled:
2072 void notrace
trace_hardirqs_off_caller(unsigned long a0
)
2074 struct task_struct
*curr
= current
;
2076 time_hardirqs_off(CALLER_ADDR0
, a0
);
2078 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2081 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2084 if (curr
->hardirqs_enabled
) {
2086 * We have done an ON -> OFF transition:
2088 curr
->hardirqs_enabled
= 0;
2089 curr
->hardirq_disable_ip
= _RET_IP_
;
2090 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2091 debug_atomic_inc(&hardirqs_off_events
);
2093 debug_atomic_inc(&redundant_hardirqs_off
);
2095 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2097 void notrace
trace_hardirqs_off(void)
2099 trace_hardirqs_off_caller(CALLER_ADDR0
);
2101 EXPORT_SYMBOL(trace_hardirqs_off
);
2104 * Softirqs will be enabled:
2106 void trace_softirqs_on(unsigned long ip
)
2108 struct task_struct
*curr
= current
;
2110 if (unlikely(!debug_locks
))
2113 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2116 if (curr
->softirqs_enabled
) {
2117 debug_atomic_inc(&redundant_softirqs_on
);
2122 * We'll do an OFF -> ON transition:
2124 curr
->softirqs_enabled
= 1;
2125 curr
->softirq_enable_ip
= ip
;
2126 curr
->softirq_enable_event
= ++curr
->irq_events
;
2127 debug_atomic_inc(&softirqs_on_events
);
2129 * We are going to turn softirqs on, so set the
2130 * usage bit for all held locks, if hardirqs are
2133 if (curr
->hardirqs_enabled
)
2134 mark_held_locks(curr
, 0);
2138 * Softirqs were disabled:
2140 void trace_softirqs_off(unsigned long ip
)
2142 struct task_struct
*curr
= current
;
2144 if (unlikely(!debug_locks
))
2147 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2150 if (curr
->softirqs_enabled
) {
2152 * We have done an ON -> OFF transition:
2154 curr
->softirqs_enabled
= 0;
2155 curr
->softirq_disable_ip
= ip
;
2156 curr
->softirq_disable_event
= ++curr
->irq_events
;
2157 debug_atomic_inc(&softirqs_off_events
);
2158 DEBUG_LOCKS_WARN_ON(!softirq_count());
2160 debug_atomic_inc(&redundant_softirqs_off
);
2163 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2166 * If non-trylock use in a hardirq or softirq context, then
2167 * mark the lock as used in these contexts:
2169 if (!hlock
->trylock
) {
2171 if (curr
->hardirq_context
)
2172 if (!mark_lock(curr
, hlock
,
2173 LOCK_USED_IN_HARDIRQ_READ
))
2175 if (curr
->softirq_context
)
2176 if (!mark_lock(curr
, hlock
,
2177 LOCK_USED_IN_SOFTIRQ_READ
))
2180 if (curr
->hardirq_context
)
2181 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2183 if (curr
->softirq_context
)
2184 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2188 if (!hlock
->hardirqs_off
) {
2190 if (!mark_lock(curr
, hlock
,
2191 LOCK_ENABLED_HARDIRQS_READ
))
2193 if (curr
->softirqs_enabled
)
2194 if (!mark_lock(curr
, hlock
,
2195 LOCK_ENABLED_SOFTIRQS_READ
))
2198 if (!mark_lock(curr
, hlock
,
2199 LOCK_ENABLED_HARDIRQS
))
2201 if (curr
->softirqs_enabled
)
2202 if (!mark_lock(curr
, hlock
,
2203 LOCK_ENABLED_SOFTIRQS
))
2211 static int separate_irq_context(struct task_struct
*curr
,
2212 struct held_lock
*hlock
)
2214 unsigned int depth
= curr
->lockdep_depth
;
2217 * Keep track of points where we cross into an interrupt context:
2219 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2220 curr
->softirq_context
;
2222 struct held_lock
*prev_hlock
;
2224 prev_hlock
= curr
->held_locks
+ depth
-1;
2226 * If we cross into another context, reset the
2227 * hash key (this also prevents the checking and the
2228 * adding of the dependency to 'prev'):
2230 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2239 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2240 enum lock_usage_bit new_bit
)
2246 static inline int mark_irqflags(struct task_struct
*curr
,
2247 struct held_lock
*hlock
)
2252 static inline int separate_irq_context(struct task_struct
*curr
,
2253 struct held_lock
*hlock
)
2261 * Mark a lock with a usage bit, and validate the state transition:
2263 static notrace
int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2264 enum lock_usage_bit new_bit
)
2266 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2269 * If already set then do not dirty the cacheline,
2270 * nor do any checks:
2272 if (likely(this->class->usage_mask
& new_mask
))
2278 * Make sure we didnt race:
2280 if (unlikely(this->class->usage_mask
& new_mask
)) {
2285 this->class->usage_mask
|= new_mask
;
2287 if (!save_trace(this->class->usage_traces
+ new_bit
))
2291 case LOCK_USED_IN_HARDIRQ
:
2292 case LOCK_USED_IN_SOFTIRQ
:
2293 case LOCK_USED_IN_HARDIRQ_READ
:
2294 case LOCK_USED_IN_SOFTIRQ_READ
:
2295 case LOCK_ENABLED_HARDIRQS
:
2296 case LOCK_ENABLED_SOFTIRQS
:
2297 case LOCK_ENABLED_HARDIRQS_READ
:
2298 case LOCK_ENABLED_SOFTIRQS_READ
:
2299 ret
= mark_lock_irq(curr
, this, new_bit
);
2304 debug_atomic_dec(&nr_unused_locks
);
2307 if (!debug_locks_off_graph_unlock())
2316 * We must printk outside of the graph_lock:
2319 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2321 print_irqtrace_events(curr
);
2329 * Initialize a lock instance's lock-class mapping info:
2331 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2332 struct lock_class_key
*key
, int subclass
)
2334 if (unlikely(!debug_locks
))
2337 if (DEBUG_LOCKS_WARN_ON(!key
))
2339 if (DEBUG_LOCKS_WARN_ON(!name
))
2342 * Sanity check, the lock-class key must be persistent:
2344 if (!static_obj(key
)) {
2345 printk("BUG: key %p not in .data!\n", key
);
2346 DEBUG_LOCKS_WARN_ON(1);
2351 lock
->class_cache
= NULL
;
2352 #ifdef CONFIG_LOCK_STAT
2353 lock
->cpu
= raw_smp_processor_id();
2356 register_lock_class(lock
, subclass
, 1);
2359 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2362 * This gets called for every mutex_lock*()/spin_lock*() operation.
2363 * We maintain the dependency maps and validate the locking attempt:
2365 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2366 int trylock
, int read
, int check
, int hardirqs_off
,
2369 struct task_struct
*curr
= current
;
2370 struct lock_class
*class = NULL
;
2371 struct held_lock
*hlock
;
2372 unsigned int depth
, id
;
2379 if (unlikely(!debug_locks
))
2382 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2385 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
2387 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2388 printk("turning off the locking correctness validator.\n");
2393 class = lock
->class_cache
;
2395 * Not cached yet or subclass?
2397 if (unlikely(!class)) {
2398 class = register_lock_class(lock
, subclass
, 0);
2402 debug_atomic_inc((atomic_t
*)&class->ops
);
2403 if (very_verbose(class)) {
2404 printk("\nacquire class [%p] %s", class->key
, class->name
);
2405 if (class->name_version
> 1)
2406 printk("#%d", class->name_version
);
2412 * Add the lock to the list of currently held locks.
2413 * (we dont increase the depth just yet, up until the
2414 * dependency checks are done)
2416 depth
= curr
->lockdep_depth
;
2417 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2420 hlock
= curr
->held_locks
+ depth
;
2422 hlock
->class = class;
2423 hlock
->acquire_ip
= ip
;
2424 hlock
->instance
= lock
;
2425 hlock
->trylock
= trylock
;
2427 hlock
->check
= check
;
2428 hlock
->hardirqs_off
= hardirqs_off
;
2429 #ifdef CONFIG_LOCK_STAT
2430 hlock
->waittime_stamp
= 0;
2431 hlock
->holdtime_stamp
= sched_clock();
2434 if (check
== 2 && !mark_irqflags(curr
, hlock
))
2437 /* mark it as used: */
2438 if (!mark_lock(curr
, hlock
, LOCK_USED
))
2442 * Calculate the chain hash: it's the combined hash of all the
2443 * lock keys along the dependency chain. We save the hash value
2444 * at every step so that we can get the current hash easily
2445 * after unlock. The chain hash is then used to cache dependency
2448 * The 'key ID' is what is the most compact key value to drive
2449 * the hash, not class->key.
2451 id
= class - lock_classes
;
2452 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2455 chain_key
= curr
->curr_chain_key
;
2457 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2462 hlock
->prev_chain_key
= chain_key
;
2463 if (separate_irq_context(curr
, hlock
)) {
2467 chain_key
= iterate_chain_key(chain_key
, id
);
2469 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
2472 curr
->curr_chain_key
= chain_key
;
2473 curr
->lockdep_depth
++;
2474 check_chain_key(curr
);
2475 #ifdef CONFIG_DEBUG_LOCKDEP
2476 if (unlikely(!debug_locks
))
2479 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2481 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2482 printk("turning off the locking correctness validator.\n");
2486 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2487 max_lockdep_depth
= curr
->lockdep_depth
;
2493 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2496 if (!debug_locks_off())
2498 if (debug_locks_silent
)
2501 printk("\n=====================================\n");
2502 printk( "[ BUG: bad unlock balance detected! ]\n");
2503 printk( "-------------------------------------\n");
2504 printk("%s/%d is trying to release lock (",
2505 curr
->comm
, task_pid_nr(curr
));
2506 print_lockdep_cache(lock
);
2509 printk("but there are no more locks to release!\n");
2510 printk("\nother info that might help us debug this:\n");
2511 lockdep_print_held_locks(curr
);
2513 printk("\nstack backtrace:\n");
2520 * Common debugging checks for both nested and non-nested unlock:
2522 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2525 if (unlikely(!debug_locks
))
2527 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2530 if (curr
->lockdep_depth
<= 0)
2531 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2537 * Remove the lock to the list of currently held locks in a
2538 * potentially non-nested (out of order) manner. This is a
2539 * relatively rare operation, as all the unlock APIs default
2540 * to nested mode (which uses lock_release()):
2543 lock_release_non_nested(struct task_struct
*curr
,
2544 struct lockdep_map
*lock
, unsigned long ip
)
2546 struct held_lock
*hlock
, *prev_hlock
;
2551 * Check whether the lock exists in the current stack
2554 depth
= curr
->lockdep_depth
;
2555 if (DEBUG_LOCKS_WARN_ON(!depth
))
2559 for (i
= depth
-1; i
>= 0; i
--) {
2560 hlock
= curr
->held_locks
+ i
;
2562 * We must not cross into another context:
2564 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2566 if (hlock
->instance
== lock
)
2570 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2573 lock_release_holdtime(hlock
);
2576 * We have the right lock to unlock, 'hlock' points to it.
2577 * Now we remove it from the stack, and add back the other
2578 * entries (if any), recalculating the hash along the way:
2580 curr
->lockdep_depth
= i
;
2581 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2583 for (i
++; i
< depth
; i
++) {
2584 hlock
= curr
->held_locks
+ i
;
2585 if (!__lock_acquire(hlock
->instance
,
2586 hlock
->class->subclass
, hlock
->trylock
,
2587 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2592 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2598 * Remove the lock to the list of currently held locks - this gets
2599 * called on mutex_unlock()/spin_unlock*() (or on a failed
2600 * mutex_lock_interruptible()). This is done for unlocks that nest
2601 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2603 static int lock_release_nested(struct task_struct
*curr
,
2604 struct lockdep_map
*lock
, unsigned long ip
)
2606 struct held_lock
*hlock
;
2610 * Pop off the top of the lock stack:
2612 depth
= curr
->lockdep_depth
- 1;
2613 hlock
= curr
->held_locks
+ depth
;
2616 * Is the unlock non-nested:
2618 if (hlock
->instance
!= lock
)
2619 return lock_release_non_nested(curr
, lock
, ip
);
2620 curr
->lockdep_depth
--;
2622 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2625 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2627 lock_release_holdtime(hlock
);
2629 #ifdef CONFIG_DEBUG_LOCKDEP
2630 hlock
->prev_chain_key
= 0;
2631 hlock
->class = NULL
;
2632 hlock
->acquire_ip
= 0;
2633 hlock
->irq_context
= 0;
2639 * Remove the lock to the list of currently held locks - this gets
2640 * called on mutex_unlock()/spin_unlock*() (or on a failed
2641 * mutex_lock_interruptible()). This is done for unlocks that nest
2642 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2645 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2647 struct task_struct
*curr
= current
;
2649 if (!check_unlock(curr
, lock
, ip
))
2653 if (!lock_release_nested(curr
, lock
, ip
))
2656 if (!lock_release_non_nested(curr
, lock
, ip
))
2660 check_chain_key(curr
);
2664 * Check whether we follow the irq-flags state precisely:
2666 static notrace
void check_flags(unsigned long flags
)
2668 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2672 if (irqs_disabled_flags(flags
)) {
2673 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
2674 printk("possible reason: unannotated irqs-off.\n");
2677 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
2678 printk("possible reason: unannotated irqs-on.\n");
2683 * We dont accurately track softirq state in e.g.
2684 * hardirq contexts (such as on 4KSTACKS), so only
2685 * check if not in hardirq contexts:
2687 if (!hardirq_count()) {
2688 if (softirq_count())
2689 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
2691 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
2695 print_irqtrace_events(current
);
2700 * We are not always called with irqs disabled - do that here,
2701 * and also avoid lockdep recursion:
2703 notrace
void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2704 int trylock
, int read
, int check
, unsigned long ip
)
2706 unsigned long flags
;
2708 if (unlikely(!lock_stat
&& !prove_locking
))
2711 if (unlikely(current
->lockdep_recursion
))
2714 raw_local_irq_save(flags
);
2717 current
->lockdep_recursion
= 1;
2718 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
2719 irqs_disabled_flags(flags
), ip
);
2720 current
->lockdep_recursion
= 0;
2721 raw_local_irq_restore(flags
);
2724 EXPORT_SYMBOL_GPL(lock_acquire
);
2726 notrace
void lock_release(struct lockdep_map
*lock
, int nested
,
2729 unsigned long flags
;
2731 if (unlikely(!lock_stat
&& !prove_locking
))
2734 if (unlikely(current
->lockdep_recursion
))
2737 raw_local_irq_save(flags
);
2739 current
->lockdep_recursion
= 1;
2740 __lock_release(lock
, nested
, ip
);
2741 current
->lockdep_recursion
= 0;
2742 raw_local_irq_restore(flags
);
2745 EXPORT_SYMBOL_GPL(lock_release
);
2747 #ifdef CONFIG_LOCK_STAT
2749 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2752 if (!debug_locks_off())
2754 if (debug_locks_silent
)
2757 printk("\n=================================\n");
2758 printk( "[ BUG: bad contention detected! ]\n");
2759 printk( "---------------------------------\n");
2760 printk("%s/%d is trying to contend lock (",
2761 curr
->comm
, task_pid_nr(curr
));
2762 print_lockdep_cache(lock
);
2765 printk("but there are no locks held!\n");
2766 printk("\nother info that might help us debug this:\n");
2767 lockdep_print_held_locks(curr
);
2769 printk("\nstack backtrace:\n");
2776 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
2778 struct task_struct
*curr
= current
;
2779 struct held_lock
*hlock
, *prev_hlock
;
2780 struct lock_class_stats
*stats
;
2784 depth
= curr
->lockdep_depth
;
2785 if (DEBUG_LOCKS_WARN_ON(!depth
))
2789 for (i
= depth
-1; i
>= 0; i
--) {
2790 hlock
= curr
->held_locks
+ i
;
2792 * We must not cross into another context:
2794 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2796 if (hlock
->instance
== lock
)
2800 print_lock_contention_bug(curr
, lock
, ip
);
2804 hlock
->waittime_stamp
= sched_clock();
2806 point
= lock_contention_point(hlock
->class, ip
);
2808 stats
= get_lock_stats(hlock
->class);
2809 if (point
< ARRAY_SIZE(stats
->contention_point
))
2810 stats
->contention_point
[i
]++;
2811 if (lock
->cpu
!= smp_processor_id())
2812 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
2813 put_lock_stats(stats
);
2817 __lock_acquired(struct lockdep_map
*lock
)
2819 struct task_struct
*curr
= current
;
2820 struct held_lock
*hlock
, *prev_hlock
;
2821 struct lock_class_stats
*stats
;
2827 depth
= curr
->lockdep_depth
;
2828 if (DEBUG_LOCKS_WARN_ON(!depth
))
2832 for (i
= depth
-1; i
>= 0; i
--) {
2833 hlock
= curr
->held_locks
+ i
;
2835 * We must not cross into another context:
2837 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2839 if (hlock
->instance
== lock
)
2843 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
2847 cpu
= smp_processor_id();
2848 if (hlock
->waittime_stamp
) {
2849 now
= sched_clock();
2850 waittime
= now
- hlock
->waittime_stamp
;
2851 hlock
->holdtime_stamp
= now
;
2854 stats
= get_lock_stats(hlock
->class);
2857 lock_time_inc(&stats
->read_waittime
, waittime
);
2859 lock_time_inc(&stats
->write_waittime
, waittime
);
2861 if (lock
->cpu
!= cpu
)
2862 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
2863 put_lock_stats(stats
);
2868 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
2870 unsigned long flags
;
2872 if (unlikely(!lock_stat
))
2875 if (unlikely(current
->lockdep_recursion
))
2878 raw_local_irq_save(flags
);
2880 current
->lockdep_recursion
= 1;
2881 __lock_contended(lock
, ip
);
2882 current
->lockdep_recursion
= 0;
2883 raw_local_irq_restore(flags
);
2885 EXPORT_SYMBOL_GPL(lock_contended
);
2887 void lock_acquired(struct lockdep_map
*lock
)
2889 unsigned long flags
;
2891 if (unlikely(!lock_stat
))
2894 if (unlikely(current
->lockdep_recursion
))
2897 raw_local_irq_save(flags
);
2899 current
->lockdep_recursion
= 1;
2900 __lock_acquired(lock
);
2901 current
->lockdep_recursion
= 0;
2902 raw_local_irq_restore(flags
);
2904 EXPORT_SYMBOL_GPL(lock_acquired
);
2908 * Used by the testsuite, sanitize the validator state
2909 * after a simulated failure:
2912 void lockdep_reset(void)
2914 unsigned long flags
;
2917 raw_local_irq_save(flags
);
2918 current
->curr_chain_key
= 0;
2919 current
->lockdep_depth
= 0;
2920 current
->lockdep_recursion
= 0;
2921 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
2922 nr_hardirq_chains
= 0;
2923 nr_softirq_chains
= 0;
2924 nr_process_chains
= 0;
2926 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
2927 INIT_LIST_HEAD(chainhash_table
+ i
);
2928 raw_local_irq_restore(flags
);
2931 static void zap_class(struct lock_class
*class)
2936 * Remove all dependencies this lock is
2939 for (i
= 0; i
< nr_list_entries
; i
++) {
2940 if (list_entries
[i
].class == class)
2941 list_del_rcu(&list_entries
[i
].entry
);
2944 * Unhash the class and remove it from the all_lock_classes list:
2946 list_del_rcu(&class->hash_entry
);
2947 list_del_rcu(&class->lock_entry
);
2951 static inline int within(const void *addr
, void *start
, unsigned long size
)
2953 return addr
>= start
&& addr
< start
+ size
;
2956 void lockdep_free_key_range(void *start
, unsigned long size
)
2958 struct lock_class
*class, *next
;
2959 struct list_head
*head
;
2960 unsigned long flags
;
2964 raw_local_irq_save(flags
);
2965 locked
= graph_lock();
2968 * Unhash all classes that were created by this module:
2970 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
2971 head
= classhash_table
+ i
;
2972 if (list_empty(head
))
2974 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
2975 if (within(class->key
, start
, size
))
2977 else if (within(class->name
, start
, size
))
2984 raw_local_irq_restore(flags
);
2987 void lockdep_reset_lock(struct lockdep_map
*lock
)
2989 struct lock_class
*class, *next
;
2990 struct list_head
*head
;
2991 unsigned long flags
;
2995 raw_local_irq_save(flags
);
2998 * Remove all classes this lock might have:
3000 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3002 * If the class exists we look it up and zap it:
3004 class = look_up_lock_class(lock
, j
);
3009 * Debug check: in the end all mapped classes should
3012 locked
= graph_lock();
3013 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3014 head
= classhash_table
+ i
;
3015 if (list_empty(head
))
3017 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3018 if (unlikely(class == lock
->class_cache
)) {
3019 if (debug_locks_off_graph_unlock())
3029 raw_local_irq_restore(flags
);
3032 void lockdep_init(void)
3037 * Some architectures have their own start_kernel()
3038 * code which calls lockdep_init(), while we also
3039 * call lockdep_init() from the start_kernel() itself,
3040 * and we want to initialize the hashes only once:
3042 if (lockdep_initialized
)
3045 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3046 INIT_LIST_HEAD(classhash_table
+ i
);
3048 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3049 INIT_LIST_HEAD(chainhash_table
+ i
);
3051 lockdep_initialized
= 1;
3054 void __init
lockdep_info(void)
3056 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3058 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
3059 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
3060 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
3061 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
3062 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
3063 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
3064 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
3066 printk(" memory used by lock dependency info: %lu kB\n",
3067 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
3068 sizeof(struct list_head
) * CLASSHASH_SIZE
+
3069 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
3070 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
3071 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
3073 printk(" per task-struct memory footprint: %lu bytes\n",
3074 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
3076 #ifdef CONFIG_DEBUG_LOCKDEP
3077 if (lockdep_init_error
) {
3078 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3079 printk("Call stack leading to lockdep invocation was:\n");
3080 print_stack_trace(&lockdep_init_trace
, 0);
3086 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
3087 const void *mem_to
, struct held_lock
*hlock
)
3089 if (!debug_locks_off())
3091 if (debug_locks_silent
)
3094 printk("\n=========================\n");
3095 printk( "[ BUG: held lock freed! ]\n");
3096 printk( "-------------------------\n");
3097 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3098 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
3100 lockdep_print_held_locks(curr
);
3102 printk("\nstack backtrace:\n");
3106 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
3107 const void* lock_from
, unsigned long lock_len
)
3109 return lock_from
+ lock_len
<= mem_from
||
3110 mem_from
+ mem_len
<= lock_from
;
3114 * Called when kernel memory is freed (or unmapped), or if a lock
3115 * is destroyed or reinitialized - this code checks whether there is
3116 * any held lock in the memory range of <from> to <to>:
3118 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
3120 struct task_struct
*curr
= current
;
3121 struct held_lock
*hlock
;
3122 unsigned long flags
;
3125 if (unlikely(!debug_locks
))
3128 local_irq_save(flags
);
3129 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3130 hlock
= curr
->held_locks
+ i
;
3132 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
3133 sizeof(*hlock
->instance
)))
3136 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
3139 local_irq_restore(flags
);
3141 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
3143 static void print_held_locks_bug(struct task_struct
*curr
)
3145 if (!debug_locks_off())
3147 if (debug_locks_silent
)
3150 printk("\n=====================================\n");
3151 printk( "[ BUG: lock held at task exit time! ]\n");
3152 printk( "-------------------------------------\n");
3153 printk("%s/%d is exiting with locks still held!\n",
3154 curr
->comm
, task_pid_nr(curr
));
3155 lockdep_print_held_locks(curr
);
3157 printk("\nstack backtrace:\n");
3161 void debug_check_no_locks_held(struct task_struct
*task
)
3163 if (unlikely(task
->lockdep_depth
> 0))
3164 print_held_locks_bug(task
);
3167 void debug_show_all_locks(void)
3169 struct task_struct
*g
, *p
;
3173 if (unlikely(!debug_locks
)) {
3174 printk("INFO: lockdep is turned off.\n");
3177 printk("\nShowing all locks held in the system:\n");
3180 * Here we try to get the tasklist_lock as hard as possible,
3181 * if not successful after 2 seconds we ignore it (but keep
3182 * trying). This is to enable a debug printout even if a
3183 * tasklist_lock-holding task deadlocks or crashes.
3186 if (!read_trylock(&tasklist_lock
)) {
3188 printk("hm, tasklist_lock locked, retrying... ");
3191 printk(" #%d", 10-count
);
3195 printk(" ignoring it.\n");
3199 printk(" locked it.\n");
3201 do_each_thread(g
, p
) {
3203 * It's not reliable to print a task's held locks
3204 * if it's not sleeping (or if it's not the current
3207 if (p
->state
== TASK_RUNNING
&& p
!= current
)
3209 if (p
->lockdep_depth
)
3210 lockdep_print_held_locks(p
);
3212 if (read_trylock(&tasklist_lock
))
3214 } while_each_thread(g
, p
);
3217 printk("=============================================\n\n");
3220 read_unlock(&tasklist_lock
);
3223 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
3226 * Careful: only use this function if you are sure that
3227 * the task cannot run in parallel!
3229 void __debug_show_held_locks(struct task_struct
*task
)
3231 if (unlikely(!debug_locks
)) {
3232 printk("INFO: lockdep is turned off.\n");
3235 lockdep_print_held_locks(task
);
3237 EXPORT_SYMBOL_GPL(__debug_show_held_locks
);
3239 void debug_show_held_locks(struct task_struct
*task
)
3241 __debug_show_held_locks(task
);
3244 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
3246 void lockdep_sys_exit(void)
3248 struct task_struct
*curr
= current
;
3250 if (unlikely(curr
->lockdep_depth
)) {
3251 if (!debug_locks_off())
3253 printk("\n================================================\n");
3254 printk( "[ BUG: lock held when returning to user space! ]\n");
3255 printk( "------------------------------------------------\n");
3256 printk("%s/%d is leaving the kernel with locks still held!\n",
3257 curr
->comm
, curr
->pid
);
3258 lockdep_print_held_locks(curr
);