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
);
85 /* prevent any recursions within lockdep from causing deadlocks */
86 current
->lockdep_recursion
++;
90 static inline int graph_unlock(void)
92 if (debug_locks
&& !__raw_spin_is_locked(&lockdep_lock
))
93 return DEBUG_LOCKS_WARN_ON(1);
95 current
->lockdep_recursion
--;
96 __raw_spin_unlock(&lockdep_lock
);
101 * Turn lock debugging off and return with 0 if it was off already,
102 * and also release the graph lock:
104 static inline int debug_locks_off_graph_unlock(void)
106 int ret
= debug_locks_off();
108 __raw_spin_unlock(&lockdep_lock
);
113 static int lockdep_initialized
;
115 unsigned long nr_list_entries
;
116 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
119 * All data structures here are protected by the global debug_lock.
121 * Mutex key structs only get allocated, once during bootup, and never
122 * get freed - this significantly simplifies the debugging code.
124 unsigned long nr_lock_classes
;
125 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
127 #ifdef CONFIG_LOCK_STAT
128 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
], lock_stats
);
130 static int lock_contention_point(struct lock_class
*class, unsigned long ip
)
134 for (i
= 0; i
< ARRAY_SIZE(class->contention_point
); i
++) {
135 if (class->contention_point
[i
] == 0) {
136 class->contention_point
[i
] = ip
;
139 if (class->contention_point
[i
] == ip
)
146 static void lock_time_inc(struct lock_time
*lt
, s64 time
)
151 if (time
< lt
->min
|| !lt
->min
)
158 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
160 dst
->min
+= src
->min
;
161 dst
->max
+= src
->max
;
162 dst
->total
+= src
->total
;
166 struct lock_class_stats
lock_stats(struct lock_class
*class)
168 struct lock_class_stats stats
;
171 memset(&stats
, 0, sizeof(struct lock_class_stats
));
172 for_each_possible_cpu(cpu
) {
173 struct lock_class_stats
*pcs
=
174 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
176 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
177 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
179 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
180 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
182 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
183 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
185 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
186 stats
.bounces
[i
] += pcs
->bounces
[i
];
192 void clear_lock_stats(struct lock_class
*class)
196 for_each_possible_cpu(cpu
) {
197 struct lock_class_stats
*cpu_stats
=
198 &per_cpu(lock_stats
, cpu
)[class - lock_classes
];
200 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
202 memset(class->contention_point
, 0, sizeof(class->contention_point
));
205 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
207 return &get_cpu_var(lock_stats
)[class - lock_classes
];
210 static void put_lock_stats(struct lock_class_stats
*stats
)
212 put_cpu_var(lock_stats
);
215 static void lock_release_holdtime(struct held_lock
*hlock
)
217 struct lock_class_stats
*stats
;
223 holdtime
= sched_clock() - hlock
->holdtime_stamp
;
225 stats
= get_lock_stats(hlock
->class);
227 lock_time_inc(&stats
->read_holdtime
, holdtime
);
229 lock_time_inc(&stats
->write_holdtime
, holdtime
);
230 put_lock_stats(stats
);
233 static inline void lock_release_holdtime(struct held_lock
*hlock
)
239 * We keep a global list of all lock classes. The list only grows,
240 * never shrinks. The list is only accessed with the lockdep
241 * spinlock lock held.
243 LIST_HEAD(all_lock_classes
);
246 * The lockdep classes are in a hash-table as well, for fast lookup:
248 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
249 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
250 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
251 #define classhashentry(key) (classhash_table + __classhashfn((key)))
253 static struct list_head classhash_table
[CLASSHASH_SIZE
];
256 * We put the lock dependency chains into a hash-table as well, to cache
259 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
260 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
261 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
262 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
264 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
267 * The hash key of the lock dependency chains is a hash itself too:
268 * it's a hash of all locks taken up to that lock, including that lock.
269 * It's a 64-bit hash, because it's important for the keys to be
272 #define iterate_chain_key(key1, key2) \
273 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
274 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
277 void lockdep_off(void)
279 current
->lockdep_recursion
++;
282 EXPORT_SYMBOL(lockdep_off
);
284 void lockdep_on(void)
286 current
->lockdep_recursion
--;
289 EXPORT_SYMBOL(lockdep_on
);
292 * Debugging switches:
296 #define VERY_VERBOSE 0
299 # define HARDIRQ_VERBOSE 1
300 # define SOFTIRQ_VERBOSE 1
302 # define HARDIRQ_VERBOSE 0
303 # define SOFTIRQ_VERBOSE 0
306 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
308 * Quick filtering for interesting events:
310 static int class_filter(struct lock_class
*class)
314 if (class->name_version
== 1 &&
315 !strcmp(class->name
, "lockname"))
317 if (class->name_version
== 1 &&
318 !strcmp(class->name
, "&struct->lockfield"))
321 /* Filter everything else. 1 would be to allow everything else */
326 static int verbose(struct lock_class
*class)
329 return class_filter(class);
335 * Stack-trace: tightly packed array of stack backtrace
336 * addresses. Protected by the graph_lock.
338 unsigned long nr_stack_trace_entries
;
339 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
341 static int save_trace(struct stack_trace
*trace
)
343 trace
->nr_entries
= 0;
344 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
345 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
349 save_stack_trace(trace
);
351 trace
->max_entries
= trace
->nr_entries
;
353 nr_stack_trace_entries
+= trace
->nr_entries
;
355 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
356 if (!debug_locks_off_graph_unlock())
359 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
360 printk("turning off the locking correctness validator.\n");
369 unsigned int nr_hardirq_chains
;
370 unsigned int nr_softirq_chains
;
371 unsigned int nr_process_chains
;
372 unsigned int max_lockdep_depth
;
373 unsigned int max_recursion_depth
;
375 #ifdef CONFIG_DEBUG_LOCKDEP
377 * We cannot printk in early bootup code. Not even early_printk()
378 * might work. So we mark any initialization errors and printk
379 * about it later on, in lockdep_info().
381 static int lockdep_init_error
;
382 static unsigned long lockdep_init_trace_data
[20];
383 static struct stack_trace lockdep_init_trace
= {
384 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
385 .entries
= lockdep_init_trace_data
,
389 * Various lockdep statistics:
391 atomic_t chain_lookup_hits
;
392 atomic_t chain_lookup_misses
;
393 atomic_t hardirqs_on_events
;
394 atomic_t hardirqs_off_events
;
395 atomic_t redundant_hardirqs_on
;
396 atomic_t redundant_hardirqs_off
;
397 atomic_t softirqs_on_events
;
398 atomic_t softirqs_off_events
;
399 atomic_t redundant_softirqs_on
;
400 atomic_t redundant_softirqs_off
;
401 atomic_t nr_unused_locks
;
402 atomic_t nr_cyclic_checks
;
403 atomic_t nr_cyclic_check_recursions
;
404 atomic_t nr_find_usage_forwards_checks
;
405 atomic_t nr_find_usage_forwards_recursions
;
406 atomic_t nr_find_usage_backwards_checks
;
407 atomic_t nr_find_usage_backwards_recursions
;
408 # define debug_atomic_inc(ptr) atomic_inc(ptr)
409 # define debug_atomic_dec(ptr) atomic_dec(ptr)
410 # define debug_atomic_read(ptr) atomic_read(ptr)
412 # define debug_atomic_inc(ptr) do { } while (0)
413 # define debug_atomic_dec(ptr) do { } while (0)
414 # define debug_atomic_read(ptr) 0
421 static const char *usage_str
[] =
423 [LOCK_USED
] = "initial-use ",
424 [LOCK_USED_IN_HARDIRQ
] = "in-hardirq-W",
425 [LOCK_USED_IN_SOFTIRQ
] = "in-softirq-W",
426 [LOCK_ENABLED_SOFTIRQS
] = "softirq-on-W",
427 [LOCK_ENABLED_HARDIRQS
] = "hardirq-on-W",
428 [LOCK_USED_IN_HARDIRQ_READ
] = "in-hardirq-R",
429 [LOCK_USED_IN_SOFTIRQ_READ
] = "in-softirq-R",
430 [LOCK_ENABLED_SOFTIRQS_READ
] = "softirq-on-R",
431 [LOCK_ENABLED_HARDIRQS_READ
] = "hardirq-on-R",
434 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
436 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
440 get_usage_chars(struct lock_class
*class, char *c1
, char *c2
, char *c3
, char *c4
)
442 *c1
= '.', *c2
= '.', *c3
= '.', *c4
= '.';
444 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ
)
447 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS
)
450 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ
)
453 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS
)
456 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
458 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ_READ
) {
460 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
464 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
466 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ_READ
) {
468 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
473 static void print_lock_name(struct lock_class
*class)
475 char str
[KSYM_NAME_LEN
], c1
, c2
, c3
, c4
;
478 get_usage_chars(class, &c1
, &c2
, &c3
, &c4
);
482 name
= __get_key_name(class->key
, str
);
483 printk(" (%s", name
);
485 printk(" (%s", name
);
486 if (class->name_version
> 1)
487 printk("#%d", class->name_version
);
489 printk("/%d", class->subclass
);
491 printk("){%c%c%c%c}", c1
, c2
, c3
, c4
);
494 static void print_lockdep_cache(struct lockdep_map
*lock
)
497 char str
[KSYM_NAME_LEN
];
501 name
= __get_key_name(lock
->key
->subkeys
, str
);
506 static void print_lock(struct held_lock
*hlock
)
508 print_lock_name(hlock
->class);
510 print_ip_sym(hlock
->acquire_ip
);
513 static void lockdep_print_held_locks(struct task_struct
*curr
)
515 int i
, depth
= curr
->lockdep_depth
;
518 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
521 printk("%d lock%s held by %s/%d:\n",
522 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
524 for (i
= 0; i
< depth
; i
++) {
526 print_lock(curr
->held_locks
+ i
);
530 static void print_lock_class_header(struct lock_class
*class, int depth
)
534 printk("%*s->", depth
, "");
535 print_lock_name(class);
536 printk(" ops: %lu", class->ops
);
539 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
540 if (class->usage_mask
& (1 << bit
)) {
543 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
544 len
+= printk(" at:\n");
545 print_stack_trace(class->usage_traces
+ bit
, len
);
548 printk("%*s }\n", depth
, "");
550 printk("%*s ... key at: ",depth
,"");
551 print_ip_sym((unsigned long)class->key
);
555 * printk all lock dependencies starting at <entry>:
557 static void print_lock_dependencies(struct lock_class
*class, int depth
)
559 struct lock_list
*entry
;
561 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
564 print_lock_class_header(class, depth
);
566 list_for_each_entry(entry
, &class->locks_after
, entry
) {
567 if (DEBUG_LOCKS_WARN_ON(!entry
->class))
570 print_lock_dependencies(entry
->class, depth
+ 1);
572 printk("%*s ... acquired at:\n",depth
,"");
573 print_stack_trace(&entry
->trace
, 2);
578 static void print_kernel_version(void)
580 printk("%s %.*s\n", init_utsname()->release
,
581 (int)strcspn(init_utsname()->version
, " "),
582 init_utsname()->version
);
585 static int very_verbose(struct lock_class
*class)
588 return class_filter(class);
594 * Is this the address of a static object:
596 static int static_obj(void *obj
)
598 unsigned long start
= (unsigned long) &_stext
,
599 end
= (unsigned long) &_end
,
600 addr
= (unsigned long) obj
;
608 if ((addr
>= start
) && (addr
< end
))
615 for_each_possible_cpu(i
) {
616 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
617 end
= (unsigned long) &__per_cpu_start
+ PERCPU_ENOUGH_ROOM
620 if ((addr
>= start
) && (addr
< end
))
628 return is_module_address(addr
);
632 * To make lock name printouts unique, we calculate a unique
633 * class->name_version generation counter:
635 static int count_matching_names(struct lock_class
*new_class
)
637 struct lock_class
*class;
640 if (!new_class
->name
)
643 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
644 if (new_class
->key
- new_class
->subclass
== class->key
)
645 return class->name_version
;
646 if (class->name
&& !strcmp(class->name
, new_class
->name
))
647 count
= max(count
, class->name_version
);
654 * Register a lock's class in the hash-table, if the class is not present
655 * yet. Otherwise we look it up. We cache the result in the lock object
656 * itself, so actual lookup of the hash should be once per lock object.
658 static inline struct lock_class
*
659 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
661 struct lockdep_subclass_key
*key
;
662 struct list_head
*hash_head
;
663 struct lock_class
*class;
665 #ifdef CONFIG_DEBUG_LOCKDEP
667 * If the architecture calls into lockdep before initializing
668 * the hashes then we'll warn about it later. (we cannot printk
671 if (unlikely(!lockdep_initialized
)) {
673 lockdep_init_error
= 1;
674 save_stack_trace(&lockdep_init_trace
);
679 * Static locks do not have their class-keys yet - for them the key
680 * is the lock object itself:
682 if (unlikely(!lock
->key
))
683 lock
->key
= (void *)lock
;
686 * NOTE: the class-key must be unique. For dynamic locks, a static
687 * lock_class_key variable is passed in through the mutex_init()
688 * (or spin_lock_init()) call - which acts as the key. For static
689 * locks we use the lock object itself as the key.
691 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
692 sizeof(struct lockdep_map
));
694 key
= lock
->key
->subkeys
+ subclass
;
696 hash_head
= classhashentry(key
);
699 * We can walk the hash lockfree, because the hash only
700 * grows, and we are careful when adding entries to the end:
702 list_for_each_entry(class, hash_head
, hash_entry
) {
703 if (class->key
== key
) {
704 WARN_ON_ONCE(class->name
!= lock
->name
);
713 * Register a lock's class in the hash-table, if the class is not present
714 * yet. Otherwise we look it up. We cache the result in the lock object
715 * itself, so actual lookup of the hash should be once per lock object.
717 static inline struct lock_class
*
718 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
720 struct lockdep_subclass_key
*key
;
721 struct list_head
*hash_head
;
722 struct lock_class
*class;
725 class = look_up_lock_class(lock
, subclass
);
730 * Debug-check: all keys must be persistent!
732 if (!static_obj(lock
->key
)) {
734 printk("INFO: trying to register non-static key.\n");
735 printk("the code is fine but needs lockdep annotation.\n");
736 printk("turning off the locking correctness validator.\n");
742 key
= lock
->key
->subkeys
+ subclass
;
743 hash_head
= classhashentry(key
);
745 raw_local_irq_save(flags
);
747 raw_local_irq_restore(flags
);
751 * We have to do the hash-walk again, to avoid races
754 list_for_each_entry(class, hash_head
, hash_entry
)
755 if (class->key
== key
)
758 * Allocate a new key from the static array, and add it to
761 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
762 if (!debug_locks_off_graph_unlock()) {
763 raw_local_irq_restore(flags
);
766 raw_local_irq_restore(flags
);
768 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
769 printk("turning off the locking correctness validator.\n");
772 class = lock_classes
+ nr_lock_classes
++;
773 debug_atomic_inc(&nr_unused_locks
);
775 class->name
= lock
->name
;
776 class->subclass
= subclass
;
777 INIT_LIST_HEAD(&class->lock_entry
);
778 INIT_LIST_HEAD(&class->locks_before
);
779 INIT_LIST_HEAD(&class->locks_after
);
780 class->name_version
= count_matching_names(class);
782 * We use RCU's safe list-add method to make
783 * parallel walking of the hash-list safe:
785 list_add_tail_rcu(&class->hash_entry
, hash_head
);
787 * Add it to the global list of classes:
789 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
791 if (verbose(class)) {
793 raw_local_irq_restore(flags
);
795 printk("\nnew class %p: %s", class->key
, class->name
);
796 if (class->name_version
> 1)
797 printk("#%d", class->name_version
);
801 raw_local_irq_save(flags
);
803 raw_local_irq_restore(flags
);
809 raw_local_irq_restore(flags
);
811 if (!subclass
|| force
)
812 lock
->class_cache
= class;
814 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
820 #ifdef CONFIG_PROVE_LOCKING
822 * Allocate a lockdep entry. (assumes the graph_lock held, returns
823 * with NULL on failure)
825 static struct lock_list
*alloc_list_entry(void)
827 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
828 if (!debug_locks_off_graph_unlock())
831 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
832 printk("turning off the locking correctness validator.\n");
835 return list_entries
+ nr_list_entries
++;
839 * Add a new dependency to the head of the list:
841 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
842 struct list_head
*head
, unsigned long ip
, int distance
)
844 struct lock_list
*entry
;
846 * Lock not present yet - get a new dependency struct and
847 * add it to the list:
849 entry
= alloc_list_entry();
854 entry
->distance
= distance
;
855 if (!save_trace(&entry
->trace
))
859 * Since we never remove from the dependency list, the list can
860 * be walked lockless by other CPUs, it's only allocation
861 * that must be protected by the spinlock. But this also means
862 * we must make new entries visible only once writes to the
863 * entry become visible - hence the RCU op:
865 list_add_tail_rcu(&entry
->entry
, head
);
871 * Recursive, forwards-direction lock-dependency checking, used for
872 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
875 * (to keep the stackframe of the recursive functions small we
876 * use these global variables, and we also mark various helper
877 * functions as noinline.)
879 static struct held_lock
*check_source
, *check_target
;
882 * Print a dependency chain entry (this is only done when a deadlock
883 * has been detected):
886 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
888 if (debug_locks_silent
)
890 printk("\n-> #%u", depth
);
891 print_lock_name(target
->class);
893 print_stack_trace(&target
->trace
, 6);
899 * When a circular dependency is detected, print the
903 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
)
905 struct task_struct
*curr
= current
;
907 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
910 printk("\n=======================================================\n");
911 printk( "[ INFO: possible circular locking dependency detected ]\n");
912 print_kernel_version();
913 printk( "-------------------------------------------------------\n");
914 printk("%s/%d is trying to acquire lock:\n",
915 curr
->comm
, task_pid_nr(curr
));
916 print_lock(check_source
);
917 printk("\nbut task is already holding lock:\n");
918 print_lock(check_target
);
919 printk("\nwhich lock already depends on the new lock.\n\n");
920 printk("\nthe existing dependency chain (in reverse order) is:\n");
922 print_circular_bug_entry(entry
, depth
);
927 static noinline
int print_circular_bug_tail(void)
929 struct task_struct
*curr
= current
;
930 struct lock_list
this;
932 if (debug_locks_silent
)
935 this.class = check_source
->class;
936 if (!save_trace(&this.trace
))
939 print_circular_bug_entry(&this, 0);
941 printk("\nother info that might help us debug this:\n\n");
942 lockdep_print_held_locks(curr
);
944 printk("\nstack backtrace:\n");
950 #define RECURSION_LIMIT 40
952 static int noinline
print_infinite_recursion_bug(void)
954 if (!debug_locks_off_graph_unlock())
963 * Prove that the dependency graph starting at <entry> can not
964 * lead to <target>. Print an error and return 0 if it does.
967 check_noncircular(struct lock_class
*source
, unsigned int depth
)
969 struct lock_list
*entry
;
971 debug_atomic_inc(&nr_cyclic_check_recursions
);
972 if (depth
> max_recursion_depth
)
973 max_recursion_depth
= depth
;
974 if (depth
>= RECURSION_LIMIT
)
975 return print_infinite_recursion_bug();
977 * Check this lock's dependency list:
979 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
980 if (entry
->class == check_target
->class)
981 return print_circular_bug_header(entry
, depth
+1);
982 debug_atomic_inc(&nr_cyclic_checks
);
983 if (!check_noncircular(entry
->class, depth
+1))
984 return print_circular_bug_entry(entry
, depth
+1);
989 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
991 * Forwards and backwards subgraph searching, for the purposes of
992 * proving that two subgraphs can be connected by a new dependency
993 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
995 static enum lock_usage_bit find_usage_bit
;
996 static struct lock_class
*forwards_match
, *backwards_match
;
999 * Find a node in the forwards-direction dependency sub-graph starting
1000 * at <source> that matches <find_usage_bit>.
1002 * Return 2 if such a node exists in the subgraph, and put that node
1003 * into <forwards_match>.
1005 * Return 1 otherwise and keep <forwards_match> unchanged.
1006 * Return 0 on error.
1009 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
1011 struct lock_list
*entry
;
1014 if (depth
> max_recursion_depth
)
1015 max_recursion_depth
= depth
;
1016 if (depth
>= RECURSION_LIMIT
)
1017 return print_infinite_recursion_bug();
1019 debug_atomic_inc(&nr_find_usage_forwards_checks
);
1020 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1021 forwards_match
= source
;
1026 * Check this lock's dependency list:
1028 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
1029 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
1030 ret
= find_usage_forwards(entry
->class, depth
+1);
1031 if (ret
== 2 || ret
== 0)
1038 * Find a node in the backwards-direction dependency sub-graph starting
1039 * at <source> that matches <find_usage_bit>.
1041 * Return 2 if such a node exists in the subgraph, and put that node
1042 * into <backwards_match>.
1044 * Return 1 otherwise and keep <backwards_match> unchanged.
1045 * Return 0 on error.
1048 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
1050 struct lock_list
*entry
;
1053 if (!__raw_spin_is_locked(&lockdep_lock
))
1054 return DEBUG_LOCKS_WARN_ON(1);
1056 if (depth
> max_recursion_depth
)
1057 max_recursion_depth
= depth
;
1058 if (depth
>= RECURSION_LIMIT
)
1059 return print_infinite_recursion_bug();
1061 debug_atomic_inc(&nr_find_usage_backwards_checks
);
1062 if (source
->usage_mask
& (1 << find_usage_bit
)) {
1063 backwards_match
= source
;
1068 * Check this lock's dependency list:
1070 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
1071 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
1072 ret
= find_usage_backwards(entry
->class, depth
+1);
1073 if (ret
== 2 || ret
== 0)
1080 print_bad_irq_dependency(struct task_struct
*curr
,
1081 struct held_lock
*prev
,
1082 struct held_lock
*next
,
1083 enum lock_usage_bit bit1
,
1084 enum lock_usage_bit bit2
,
1085 const char *irqclass
)
1087 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1090 printk("\n======================================================\n");
1091 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1092 irqclass
, irqclass
);
1093 print_kernel_version();
1094 printk( "------------------------------------------------------\n");
1095 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1096 curr
->comm
, task_pid_nr(curr
),
1097 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1098 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1099 curr
->hardirqs_enabled
,
1100 curr
->softirqs_enabled
);
1103 printk("\nand this task is already holding:\n");
1105 printk("which would create a new lock dependency:\n");
1106 print_lock_name(prev
->class);
1108 print_lock_name(next
->class);
1111 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1113 print_lock_name(backwards_match
);
1114 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1116 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
1118 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1119 print_lock_name(forwards_match
);
1120 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1123 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
1125 printk("\nother info that might help us debug this:\n\n");
1126 lockdep_print_held_locks(curr
);
1128 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
1129 print_lock_dependencies(backwards_match
, 0);
1131 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
1132 print_lock_dependencies(forwards_match
, 0);
1134 printk("\nstack backtrace:\n");
1141 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1142 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1143 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1147 find_usage_bit
= bit_backwards
;
1148 /* fills in <backwards_match> */
1149 ret
= find_usage_backwards(prev
->class, 0);
1150 if (!ret
|| ret
== 1)
1153 find_usage_bit
= bit_forwards
;
1154 ret
= find_usage_forwards(next
->class, 0);
1155 if (!ret
|| ret
== 1)
1158 return print_bad_irq_dependency(curr
, prev
, next
,
1159 bit_backwards
, bit_forwards
, irqclass
);
1163 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1164 struct held_lock
*next
)
1167 * Prove that the new dependency does not connect a hardirq-safe
1168 * lock with a hardirq-unsafe lock - to achieve this we search
1169 * the backwards-subgraph starting at <prev>, and the
1170 * forwards-subgraph starting at <next>:
1172 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ
,
1173 LOCK_ENABLED_HARDIRQS
, "hard"))
1177 * Prove that the new dependency does not connect a hardirq-safe-read
1178 * lock with a hardirq-unsafe lock - to achieve this we search
1179 * the backwards-subgraph starting at <prev>, and the
1180 * forwards-subgraph starting at <next>:
1182 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ_READ
,
1183 LOCK_ENABLED_HARDIRQS
, "hard-read"))
1187 * Prove that the new dependency does not connect a softirq-safe
1188 * lock with a softirq-unsafe lock - to achieve this we search
1189 * the backwards-subgraph starting at <prev>, and the
1190 * forwards-subgraph starting at <next>:
1192 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ
,
1193 LOCK_ENABLED_SOFTIRQS
, "soft"))
1196 * Prove that the new dependency does not connect a softirq-safe-read
1197 * lock with a softirq-unsafe lock - to achieve this we search
1198 * the backwards-subgraph starting at <prev>, and the
1199 * forwards-subgraph starting at <next>:
1201 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ_READ
,
1202 LOCK_ENABLED_SOFTIRQS
, "soft"))
1208 static void inc_chains(void)
1210 if (current
->hardirq_context
)
1211 nr_hardirq_chains
++;
1213 if (current
->softirq_context
)
1214 nr_softirq_chains
++;
1216 nr_process_chains
++;
1223 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1224 struct held_lock
*next
)
1229 static inline void inc_chains(void)
1231 nr_process_chains
++;
1237 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1238 struct held_lock
*next
)
1240 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1243 printk("\n=============================================\n");
1244 printk( "[ INFO: possible recursive locking detected ]\n");
1245 print_kernel_version();
1246 printk( "---------------------------------------------\n");
1247 printk("%s/%d is trying to acquire lock:\n",
1248 curr
->comm
, task_pid_nr(curr
));
1250 printk("\nbut task is already holding lock:\n");
1253 printk("\nother info that might help us debug this:\n");
1254 lockdep_print_held_locks(curr
);
1256 printk("\nstack backtrace:\n");
1263 * Check whether we are holding such a class already.
1265 * (Note that this has to be done separately, because the graph cannot
1266 * detect such classes of deadlocks.)
1268 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1271 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1272 struct lockdep_map
*next_instance
, int read
)
1274 struct held_lock
*prev
;
1277 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1278 prev
= curr
->held_locks
+ i
;
1279 if (prev
->class != next
->class)
1282 * Allow read-after-read recursion of the same
1283 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1285 if ((read
== 2) && prev
->read
)
1287 return print_deadlock_bug(curr
, prev
, next
);
1293 * There was a chain-cache miss, and we are about to add a new dependency
1294 * to a previous lock. We recursively validate the following rules:
1296 * - would the adding of the <prev> -> <next> dependency create a
1297 * circular dependency in the graph? [== circular deadlock]
1299 * - does the new prev->next dependency connect any hardirq-safe lock
1300 * (in the full backwards-subgraph starting at <prev>) with any
1301 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1302 * <next>)? [== illegal lock inversion with hardirq contexts]
1304 * - does the new prev->next dependency connect any softirq-safe lock
1305 * (in the full backwards-subgraph starting at <prev>) with any
1306 * softirq-unsafe lock (in the full forwards-subgraph starting at
1307 * <next>)? [== illegal lock inversion with softirq contexts]
1309 * any of these scenarios could lead to a deadlock.
1311 * Then if all the validations pass, we add the forwards and backwards
1315 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1316 struct held_lock
*next
, int distance
)
1318 struct lock_list
*entry
;
1322 * Prove that the new <prev> -> <next> dependency would not
1323 * create a circular dependency in the graph. (We do this by
1324 * forward-recursing into the graph starting at <next>, and
1325 * checking whether we can reach <prev>.)
1327 * We are using global variables to control the recursion, to
1328 * keep the stackframe size of the recursive functions low:
1330 check_source
= next
;
1331 check_target
= prev
;
1332 if (!(check_noncircular(next
->class, 0)))
1333 return print_circular_bug_tail();
1335 if (!check_prev_add_irq(curr
, prev
, next
))
1339 * For recursive read-locks we do all the dependency checks,
1340 * but we dont store read-triggered dependencies (only
1341 * write-triggered dependencies). This ensures that only the
1342 * write-side dependencies matter, and that if for example a
1343 * write-lock never takes any other locks, then the reads are
1344 * equivalent to a NOP.
1346 if (next
->read
== 2 || prev
->read
== 2)
1349 * Is the <prev> -> <next> dependency already present?
1351 * (this may occur even though this is a new chain: consider
1352 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1353 * chains - the second one will be new, but L1 already has
1354 * L2 added to its dependency list, due to the first chain.)
1356 list_for_each_entry(entry
, &prev
->class->locks_after
, entry
) {
1357 if (entry
->class == next
->class) {
1359 entry
->distance
= 1;
1365 * Ok, all validations passed, add the new lock
1366 * to the previous lock's dependency list:
1368 ret
= add_lock_to_list(prev
->class, next
->class,
1369 &prev
->class->locks_after
, next
->acquire_ip
, distance
);
1374 ret
= add_lock_to_list(next
->class, prev
->class,
1375 &next
->class->locks_before
, next
->acquire_ip
, distance
);
1380 * Debugging printouts:
1382 if (verbose(prev
->class) || verbose(next
->class)) {
1384 printk("\n new dependency: ");
1385 print_lock_name(prev
->class);
1387 print_lock_name(next
->class);
1390 return graph_lock();
1396 * Add the dependency to all directly-previous locks that are 'relevant'.
1397 * The ones that are relevant are (in increasing distance from curr):
1398 * all consecutive trylock entries and the final non-trylock entry - or
1399 * the end of this context's lock-chain - whichever comes first.
1402 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1404 int depth
= curr
->lockdep_depth
;
1405 struct held_lock
*hlock
;
1410 * Depth must not be zero for a non-head lock:
1415 * At least two relevant locks must exist for this
1418 if (curr
->held_locks
[depth
].irq_context
!=
1419 curr
->held_locks
[depth
-1].irq_context
)
1423 int distance
= curr
->lockdep_depth
- depth
+ 1;
1424 hlock
= curr
->held_locks
+ depth
-1;
1426 * Only non-recursive-read entries get new dependencies
1429 if (hlock
->read
!= 2) {
1430 if (!check_prev_add(curr
, hlock
, next
, distance
))
1433 * Stop after the first non-trylock entry,
1434 * as non-trylock entries have added their
1435 * own direct dependencies already, so this
1436 * lock is connected to them indirectly:
1438 if (!hlock
->trylock
)
1443 * End of lock-stack?
1448 * Stop the search if we cross into another context:
1450 if (curr
->held_locks
[depth
].irq_context
!=
1451 curr
->held_locks
[depth
-1].irq_context
)
1456 if (!debug_locks_off_graph_unlock())
1464 unsigned long nr_lock_chains
;
1465 static struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1468 * Look up a dependency chain. If the key is not present yet then
1469 * add it and return 1 - in this case the new dependency chain is
1470 * validated. If the key is already hashed, return 0.
1471 * (On return with 1 graph_lock is held.)
1473 static inline int lookup_chain_cache(u64 chain_key
, struct lock_class
*class)
1475 struct list_head
*hash_head
= chainhashentry(chain_key
);
1476 struct lock_chain
*chain
;
1478 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1481 * We can walk it lock-free, because entries only get added
1484 list_for_each_entry(chain
, hash_head
, entry
) {
1485 if (chain
->chain_key
== chain_key
) {
1487 debug_atomic_inc(&chain_lookup_hits
);
1488 if (very_verbose(class))
1489 printk("\nhash chain already cached, key: "
1490 "%016Lx tail class: [%p] %s\n",
1491 (unsigned long long)chain_key
,
1492 class->key
, class->name
);
1496 if (very_verbose(class))
1497 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1498 (unsigned long long)chain_key
, class->key
, class->name
);
1500 * Allocate a new chain entry from the static array, and add
1506 * We have to walk the chain again locked - to avoid duplicates:
1508 list_for_each_entry(chain
, hash_head
, entry
) {
1509 if (chain
->chain_key
== chain_key
) {
1514 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1515 if (!debug_locks_off_graph_unlock())
1518 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1519 printk("turning off the locking correctness validator.\n");
1522 chain
= lock_chains
+ nr_lock_chains
++;
1523 chain
->chain_key
= chain_key
;
1524 list_add_tail_rcu(&chain
->entry
, hash_head
);
1525 debug_atomic_inc(&chain_lookup_misses
);
1531 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
1532 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
1535 * Trylock needs to maintain the stack of held locks, but it
1536 * does not add new dependencies, because trylock can be done
1539 * We look up the chain_key and do the O(N^2) check and update of
1540 * the dependencies only if this is a new dependency chain.
1541 * (If lookup_chain_cache() returns with 1 it acquires
1542 * graph_lock for us)
1544 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
1545 lookup_chain_cache(chain_key
, hlock
->class)) {
1547 * Check whether last held lock:
1549 * - is irq-safe, if this lock is irq-unsafe
1550 * - is softirq-safe, if this lock is hardirq-unsafe
1552 * And check whether the new lock's dependency graph
1553 * could lead back to the previous lock.
1555 * any of these scenarios could lead to a deadlock. If
1558 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
1563 * Mark recursive read, as we jump over it when
1564 * building dependencies (just like we jump over
1570 * Add dependency only if this lock is not the head
1571 * of the chain, and if it's not a secondary read-lock:
1573 if (!chain_head
&& ret
!= 2)
1574 if (!check_prevs_add(curr
, hlock
))
1578 /* after lookup_chain_cache(): */
1579 if (unlikely(!debug_locks
))
1585 static inline int validate_chain(struct task_struct
*curr
,
1586 struct lockdep_map
*lock
, struct held_lock
*hlock
,
1587 int chain_head
, u64 chain_key
)
1594 * We are building curr_chain_key incrementally, so double-check
1595 * it from scratch, to make sure that it's done correctly:
1597 static void check_chain_key(struct task_struct
*curr
)
1599 #ifdef CONFIG_DEBUG_LOCKDEP
1600 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1604 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1605 hlock
= curr
->held_locks
+ i
;
1606 if (chain_key
!= hlock
->prev_chain_key
) {
1608 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1609 curr
->lockdep_depth
, i
,
1610 (unsigned long long)chain_key
,
1611 (unsigned long long)hlock
->prev_chain_key
);
1615 id
= hlock
->class - lock_classes
;
1616 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
1619 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1620 hlock
->irq_context
))
1622 chain_key
= iterate_chain_key(chain_key
, id
);
1625 if (chain_key
!= curr
->curr_chain_key
) {
1627 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1628 curr
->lockdep_depth
, i
,
1629 (unsigned long long)chain_key
,
1630 (unsigned long long)curr
->curr_chain_key
);
1637 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1638 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1640 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1643 printk("\n=================================\n");
1644 printk( "[ INFO: inconsistent lock state ]\n");
1645 print_kernel_version();
1646 printk( "---------------------------------\n");
1648 printk("inconsistent {%s} -> {%s} usage.\n",
1649 usage_str
[prev_bit
], usage_str
[new_bit
]);
1651 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1652 curr
->comm
, task_pid_nr(curr
),
1653 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1654 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1655 trace_hardirqs_enabled(curr
),
1656 trace_softirqs_enabled(curr
));
1659 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1660 print_stack_trace(this->class->usage_traces
+ prev_bit
, 1);
1662 print_irqtrace_events(curr
);
1663 printk("\nother info that might help us debug this:\n");
1664 lockdep_print_held_locks(curr
);
1666 printk("\nstack backtrace:\n");
1673 * Print out an error if an invalid bit is set:
1676 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1677 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1679 if (unlikely(this->class->usage_mask
& (1 << bad_bit
)))
1680 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1684 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1685 enum lock_usage_bit new_bit
);
1687 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1690 * print irq inversion bug:
1693 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
1694 struct held_lock
*this, int forwards
,
1695 const char *irqclass
)
1697 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1700 printk("\n=========================================================\n");
1701 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1702 print_kernel_version();
1703 printk( "---------------------------------------------------------\n");
1704 printk("%s/%d just changed the state of lock:\n",
1705 curr
->comm
, task_pid_nr(curr
));
1708 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass
);
1710 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass
);
1711 print_lock_name(other
);
1712 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1714 printk("\nother info that might help us debug this:\n");
1715 lockdep_print_held_locks(curr
);
1717 printk("\nthe first lock's dependencies:\n");
1718 print_lock_dependencies(this->class, 0);
1720 printk("\nthe second lock's dependencies:\n");
1721 print_lock_dependencies(other
, 0);
1723 printk("\nstack backtrace:\n");
1730 * Prove that in the forwards-direction subgraph starting at <this>
1731 * there is no lock matching <mask>:
1734 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
1735 enum lock_usage_bit bit
, const char *irqclass
)
1739 find_usage_bit
= bit
;
1740 /* fills in <forwards_match> */
1741 ret
= find_usage_forwards(this->class, 0);
1742 if (!ret
|| ret
== 1)
1745 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
1749 * Prove that in the backwards-direction subgraph starting at <this>
1750 * there is no lock matching <mask>:
1753 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
1754 enum lock_usage_bit bit
, const char *irqclass
)
1758 find_usage_bit
= bit
;
1759 /* fills in <backwards_match> */
1760 ret
= find_usage_backwards(this->class, 0);
1761 if (!ret
|| ret
== 1)
1764 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
1767 void print_irqtrace_events(struct task_struct
*curr
)
1769 printk("irq event stamp: %u\n", curr
->irq_events
);
1770 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
1771 print_ip_sym(curr
->hardirq_enable_ip
);
1772 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
1773 print_ip_sym(curr
->hardirq_disable_ip
);
1774 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
1775 print_ip_sym(curr
->softirq_enable_ip
);
1776 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
1777 print_ip_sym(curr
->softirq_disable_ip
);
1780 static int hardirq_verbose(struct lock_class
*class)
1783 return class_filter(class);
1788 static int softirq_verbose(struct lock_class
*class)
1791 return class_filter(class);
1796 #define STRICT_READ_CHECKS 1
1798 static int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
1799 enum lock_usage_bit new_bit
)
1804 case LOCK_USED_IN_HARDIRQ
:
1805 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1807 if (!valid_state(curr
, this, new_bit
,
1808 LOCK_ENABLED_HARDIRQS_READ
))
1811 * just marked it hardirq-safe, check that this lock
1812 * took no hardirq-unsafe lock in the past:
1814 if (!check_usage_forwards(curr
, this,
1815 LOCK_ENABLED_HARDIRQS
, "hard"))
1817 #if STRICT_READ_CHECKS
1819 * just marked it hardirq-safe, check that this lock
1820 * took no hardirq-unsafe-read lock in the past:
1822 if (!check_usage_forwards(curr
, this,
1823 LOCK_ENABLED_HARDIRQS_READ
, "hard-read"))
1826 if (hardirq_verbose(this->class))
1829 case LOCK_USED_IN_SOFTIRQ
:
1830 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1832 if (!valid_state(curr
, this, new_bit
,
1833 LOCK_ENABLED_SOFTIRQS_READ
))
1836 * just marked it softirq-safe, check that this lock
1837 * took no softirq-unsafe lock in the past:
1839 if (!check_usage_forwards(curr
, this,
1840 LOCK_ENABLED_SOFTIRQS
, "soft"))
1842 #if STRICT_READ_CHECKS
1844 * just marked it softirq-safe, check that this lock
1845 * took no softirq-unsafe-read lock in the past:
1847 if (!check_usage_forwards(curr
, this,
1848 LOCK_ENABLED_SOFTIRQS_READ
, "soft-read"))
1851 if (softirq_verbose(this->class))
1854 case LOCK_USED_IN_HARDIRQ_READ
:
1855 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1858 * just marked it hardirq-read-safe, check that this lock
1859 * took no hardirq-unsafe lock in the past:
1861 if (!check_usage_forwards(curr
, this,
1862 LOCK_ENABLED_HARDIRQS
, "hard"))
1864 if (hardirq_verbose(this->class))
1867 case LOCK_USED_IN_SOFTIRQ_READ
:
1868 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1871 * just marked it softirq-read-safe, check that this lock
1872 * took no softirq-unsafe lock in the past:
1874 if (!check_usage_forwards(curr
, this,
1875 LOCK_ENABLED_SOFTIRQS
, "soft"))
1877 if (softirq_verbose(this->class))
1880 case LOCK_ENABLED_HARDIRQS
:
1881 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1883 if (!valid_state(curr
, this, new_bit
,
1884 LOCK_USED_IN_HARDIRQ_READ
))
1887 * just marked it hardirq-unsafe, check that no hardirq-safe
1888 * lock in the system ever took it in the past:
1890 if (!check_usage_backwards(curr
, this,
1891 LOCK_USED_IN_HARDIRQ
, "hard"))
1893 #if STRICT_READ_CHECKS
1895 * just marked it hardirq-unsafe, check that no
1896 * hardirq-safe-read lock in the system ever took
1899 if (!check_usage_backwards(curr
, this,
1900 LOCK_USED_IN_HARDIRQ_READ
, "hard-read"))
1903 if (hardirq_verbose(this->class))
1906 case LOCK_ENABLED_SOFTIRQS
:
1907 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1909 if (!valid_state(curr
, this, new_bit
,
1910 LOCK_USED_IN_SOFTIRQ_READ
))
1913 * just marked it softirq-unsafe, check that no softirq-safe
1914 * lock in the system ever took it in the past:
1916 if (!check_usage_backwards(curr
, this,
1917 LOCK_USED_IN_SOFTIRQ
, "soft"))
1919 #if STRICT_READ_CHECKS
1921 * just marked it softirq-unsafe, check that no
1922 * softirq-safe-read lock in the system ever took
1925 if (!check_usage_backwards(curr
, this,
1926 LOCK_USED_IN_SOFTIRQ_READ
, "soft-read"))
1929 if (softirq_verbose(this->class))
1932 case LOCK_ENABLED_HARDIRQS_READ
:
1933 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1935 #if STRICT_READ_CHECKS
1937 * just marked it hardirq-read-unsafe, check that no
1938 * hardirq-safe lock in the system ever took it in the past:
1940 if (!check_usage_backwards(curr
, this,
1941 LOCK_USED_IN_HARDIRQ
, "hard"))
1944 if (hardirq_verbose(this->class))
1947 case LOCK_ENABLED_SOFTIRQS_READ
:
1948 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1950 #if STRICT_READ_CHECKS
1952 * just marked it softirq-read-unsafe, check that no
1953 * softirq-safe lock in the system ever took it in the past:
1955 if (!check_usage_backwards(curr
, this,
1956 LOCK_USED_IN_SOFTIRQ
, "soft"))
1959 if (softirq_verbose(this->class))
1971 * Mark all held locks with a usage bit:
1974 mark_held_locks(struct task_struct
*curr
, int hardirq
)
1976 enum lock_usage_bit usage_bit
;
1977 struct held_lock
*hlock
;
1980 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1981 hlock
= curr
->held_locks
+ i
;
1985 usage_bit
= LOCK_ENABLED_HARDIRQS_READ
;
1987 usage_bit
= LOCK_ENABLED_HARDIRQS
;
1990 usage_bit
= LOCK_ENABLED_SOFTIRQS_READ
;
1992 usage_bit
= LOCK_ENABLED_SOFTIRQS
;
1994 if (!mark_lock(curr
, hlock
, usage_bit
))
2002 * Debugging helper: via this flag we know that we are in
2003 * 'early bootup code', and will warn about any invalid irqs-on event:
2005 static int early_boot_irqs_enabled
;
2007 void early_boot_irqs_off(void)
2009 early_boot_irqs_enabled
= 0;
2012 void early_boot_irqs_on(void)
2014 early_boot_irqs_enabled
= 1;
2018 * Hardirqs will be enabled:
2020 void trace_hardirqs_on_caller(unsigned long a0
)
2022 struct task_struct
*curr
= current
;
2025 time_hardirqs_on(CALLER_ADDR0
, a0
);
2027 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2030 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
2033 if (unlikely(curr
->hardirqs_enabled
)) {
2034 debug_atomic_inc(&redundant_hardirqs_on
);
2037 /* we'll do an OFF -> ON transition: */
2038 curr
->hardirqs_enabled
= 1;
2039 ip
= (unsigned long) __builtin_return_address(0);
2041 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2043 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2046 * We are going to turn hardirqs on, so set the
2047 * usage bit for all held locks:
2049 if (!mark_held_locks(curr
, 1))
2052 * If we have softirqs enabled, then set the usage
2053 * bit for all held locks. (disabled hardirqs prevented
2054 * this bit from being set before)
2056 if (curr
->softirqs_enabled
)
2057 if (!mark_held_locks(curr
, 0))
2060 curr
->hardirq_enable_ip
= ip
;
2061 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2062 debug_atomic_inc(&hardirqs_on_events
);
2064 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2066 void trace_hardirqs_on(void)
2068 trace_hardirqs_on_caller(CALLER_ADDR0
);
2070 EXPORT_SYMBOL(trace_hardirqs_on
);
2073 * Hardirqs were disabled:
2075 void trace_hardirqs_off_caller(unsigned long a0
)
2077 struct task_struct
*curr
= current
;
2079 time_hardirqs_off(CALLER_ADDR0
, a0
);
2081 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2084 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2087 if (curr
->hardirqs_enabled
) {
2089 * We have done an ON -> OFF transition:
2091 curr
->hardirqs_enabled
= 0;
2092 curr
->hardirq_disable_ip
= _RET_IP_
;
2093 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2094 debug_atomic_inc(&hardirqs_off_events
);
2096 debug_atomic_inc(&redundant_hardirqs_off
);
2098 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2100 void trace_hardirqs_off(void)
2102 trace_hardirqs_off_caller(CALLER_ADDR0
);
2104 EXPORT_SYMBOL(trace_hardirqs_off
);
2107 * Softirqs will be enabled:
2109 void trace_softirqs_on(unsigned long ip
)
2111 struct task_struct
*curr
= current
;
2113 if (unlikely(!debug_locks
))
2116 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2119 if (curr
->softirqs_enabled
) {
2120 debug_atomic_inc(&redundant_softirqs_on
);
2125 * We'll do an OFF -> ON transition:
2127 curr
->softirqs_enabled
= 1;
2128 curr
->softirq_enable_ip
= ip
;
2129 curr
->softirq_enable_event
= ++curr
->irq_events
;
2130 debug_atomic_inc(&softirqs_on_events
);
2132 * We are going to turn softirqs on, so set the
2133 * usage bit for all held locks, if hardirqs are
2136 if (curr
->hardirqs_enabled
)
2137 mark_held_locks(curr
, 0);
2141 * Softirqs were disabled:
2143 void trace_softirqs_off(unsigned long ip
)
2145 struct task_struct
*curr
= current
;
2147 if (unlikely(!debug_locks
))
2150 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2153 if (curr
->softirqs_enabled
) {
2155 * We have done an ON -> OFF transition:
2157 curr
->softirqs_enabled
= 0;
2158 curr
->softirq_disable_ip
= ip
;
2159 curr
->softirq_disable_event
= ++curr
->irq_events
;
2160 debug_atomic_inc(&softirqs_off_events
);
2161 DEBUG_LOCKS_WARN_ON(!softirq_count());
2163 debug_atomic_inc(&redundant_softirqs_off
);
2166 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2169 * If non-trylock use in a hardirq or softirq context, then
2170 * mark the lock as used in these contexts:
2172 if (!hlock
->trylock
) {
2174 if (curr
->hardirq_context
)
2175 if (!mark_lock(curr
, hlock
,
2176 LOCK_USED_IN_HARDIRQ_READ
))
2178 if (curr
->softirq_context
)
2179 if (!mark_lock(curr
, hlock
,
2180 LOCK_USED_IN_SOFTIRQ_READ
))
2183 if (curr
->hardirq_context
)
2184 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2186 if (curr
->softirq_context
)
2187 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2191 if (!hlock
->hardirqs_off
) {
2193 if (!mark_lock(curr
, hlock
,
2194 LOCK_ENABLED_HARDIRQS_READ
))
2196 if (curr
->softirqs_enabled
)
2197 if (!mark_lock(curr
, hlock
,
2198 LOCK_ENABLED_SOFTIRQS_READ
))
2201 if (!mark_lock(curr
, hlock
,
2202 LOCK_ENABLED_HARDIRQS
))
2204 if (curr
->softirqs_enabled
)
2205 if (!mark_lock(curr
, hlock
,
2206 LOCK_ENABLED_SOFTIRQS
))
2214 static int separate_irq_context(struct task_struct
*curr
,
2215 struct held_lock
*hlock
)
2217 unsigned int depth
= curr
->lockdep_depth
;
2220 * Keep track of points where we cross into an interrupt context:
2222 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2223 curr
->softirq_context
;
2225 struct held_lock
*prev_hlock
;
2227 prev_hlock
= curr
->held_locks
+ depth
-1;
2229 * If we cross into another context, reset the
2230 * hash key (this also prevents the checking and the
2231 * adding of the dependency to 'prev'):
2233 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2242 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2243 enum lock_usage_bit new_bit
)
2249 static inline int mark_irqflags(struct task_struct
*curr
,
2250 struct held_lock
*hlock
)
2255 static inline int separate_irq_context(struct task_struct
*curr
,
2256 struct held_lock
*hlock
)
2264 * Mark a lock with a usage bit, and validate the state transition:
2266 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2267 enum lock_usage_bit new_bit
)
2269 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2272 * If already set then do not dirty the cacheline,
2273 * nor do any checks:
2275 if (likely(this->class->usage_mask
& new_mask
))
2281 * Make sure we didnt race:
2283 if (unlikely(this->class->usage_mask
& new_mask
)) {
2288 this->class->usage_mask
|= new_mask
;
2290 if (!save_trace(this->class->usage_traces
+ new_bit
))
2294 case LOCK_USED_IN_HARDIRQ
:
2295 case LOCK_USED_IN_SOFTIRQ
:
2296 case LOCK_USED_IN_HARDIRQ_READ
:
2297 case LOCK_USED_IN_SOFTIRQ_READ
:
2298 case LOCK_ENABLED_HARDIRQS
:
2299 case LOCK_ENABLED_SOFTIRQS
:
2300 case LOCK_ENABLED_HARDIRQS_READ
:
2301 case LOCK_ENABLED_SOFTIRQS_READ
:
2302 ret
= mark_lock_irq(curr
, this, new_bit
);
2307 debug_atomic_dec(&nr_unused_locks
);
2310 if (!debug_locks_off_graph_unlock())
2319 * We must printk outside of the graph_lock:
2322 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2324 print_irqtrace_events(curr
);
2332 * Initialize a lock instance's lock-class mapping info:
2334 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2335 struct lock_class_key
*key
, int subclass
)
2337 if (unlikely(!debug_locks
))
2340 if (DEBUG_LOCKS_WARN_ON(!key
))
2342 if (DEBUG_LOCKS_WARN_ON(!name
))
2345 * Sanity check, the lock-class key must be persistent:
2347 if (!static_obj(key
)) {
2348 printk("BUG: key %p not in .data!\n", key
);
2349 DEBUG_LOCKS_WARN_ON(1);
2354 lock
->class_cache
= NULL
;
2355 #ifdef CONFIG_LOCK_STAT
2356 lock
->cpu
= raw_smp_processor_id();
2359 register_lock_class(lock
, subclass
, 1);
2362 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2365 * This gets called for every mutex_lock*()/spin_lock*() operation.
2366 * We maintain the dependency maps and validate the locking attempt:
2368 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2369 int trylock
, int read
, int check
, int hardirqs_off
,
2372 struct task_struct
*curr
= current
;
2373 struct lock_class
*class = NULL
;
2374 struct held_lock
*hlock
;
2375 unsigned int depth
, id
;
2382 if (unlikely(!debug_locks
))
2385 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2388 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
2390 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2391 printk("turning off the locking correctness validator.\n");
2396 class = lock
->class_cache
;
2398 * Not cached yet or subclass?
2400 if (unlikely(!class)) {
2401 class = register_lock_class(lock
, subclass
, 0);
2405 debug_atomic_inc((atomic_t
*)&class->ops
);
2406 if (very_verbose(class)) {
2407 printk("\nacquire class [%p] %s", class->key
, class->name
);
2408 if (class->name_version
> 1)
2409 printk("#%d", class->name_version
);
2415 * Add the lock to the list of currently held locks.
2416 * (we dont increase the depth just yet, up until the
2417 * dependency checks are done)
2419 depth
= curr
->lockdep_depth
;
2420 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2423 hlock
= curr
->held_locks
+ depth
;
2425 hlock
->class = class;
2426 hlock
->acquire_ip
= ip
;
2427 hlock
->instance
= lock
;
2428 hlock
->trylock
= trylock
;
2430 hlock
->check
= check
;
2431 hlock
->hardirqs_off
= hardirqs_off
;
2432 #ifdef CONFIG_LOCK_STAT
2433 hlock
->waittime_stamp
= 0;
2434 hlock
->holdtime_stamp
= sched_clock();
2437 if (check
== 2 && !mark_irqflags(curr
, hlock
))
2440 /* mark it as used: */
2441 if (!mark_lock(curr
, hlock
, LOCK_USED
))
2445 * Calculate the chain hash: it's the combined hash of all the
2446 * lock keys along the dependency chain. We save the hash value
2447 * at every step so that we can get the current hash easily
2448 * after unlock. The chain hash is then used to cache dependency
2451 * The 'key ID' is what is the most compact key value to drive
2452 * the hash, not class->key.
2454 id
= class - lock_classes
;
2455 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2458 chain_key
= curr
->curr_chain_key
;
2460 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2465 hlock
->prev_chain_key
= chain_key
;
2466 if (separate_irq_context(curr
, hlock
)) {
2470 chain_key
= iterate_chain_key(chain_key
, id
);
2472 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
2475 curr
->curr_chain_key
= chain_key
;
2476 curr
->lockdep_depth
++;
2477 check_chain_key(curr
);
2478 #ifdef CONFIG_DEBUG_LOCKDEP
2479 if (unlikely(!debug_locks
))
2482 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2484 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2485 printk("turning off the locking correctness validator.\n");
2489 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2490 max_lockdep_depth
= curr
->lockdep_depth
;
2496 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2499 if (!debug_locks_off())
2501 if (debug_locks_silent
)
2504 printk("\n=====================================\n");
2505 printk( "[ BUG: bad unlock balance detected! ]\n");
2506 printk( "-------------------------------------\n");
2507 printk("%s/%d is trying to release lock (",
2508 curr
->comm
, task_pid_nr(curr
));
2509 print_lockdep_cache(lock
);
2512 printk("but there are no more locks to release!\n");
2513 printk("\nother info that might help us debug this:\n");
2514 lockdep_print_held_locks(curr
);
2516 printk("\nstack backtrace:\n");
2523 * Common debugging checks for both nested and non-nested unlock:
2525 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2528 if (unlikely(!debug_locks
))
2530 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2533 if (curr
->lockdep_depth
<= 0)
2534 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2540 * Remove the lock to the list of currently held locks in a
2541 * potentially non-nested (out of order) manner. This is a
2542 * relatively rare operation, as all the unlock APIs default
2543 * to nested mode (which uses lock_release()):
2546 lock_release_non_nested(struct task_struct
*curr
,
2547 struct lockdep_map
*lock
, unsigned long ip
)
2549 struct held_lock
*hlock
, *prev_hlock
;
2554 * Check whether the lock exists in the current stack
2557 depth
= curr
->lockdep_depth
;
2558 if (DEBUG_LOCKS_WARN_ON(!depth
))
2562 for (i
= depth
-1; i
>= 0; i
--) {
2563 hlock
= curr
->held_locks
+ i
;
2565 * We must not cross into another context:
2567 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2569 if (hlock
->instance
== lock
)
2573 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2576 lock_release_holdtime(hlock
);
2579 * We have the right lock to unlock, 'hlock' points to it.
2580 * Now we remove it from the stack, and add back the other
2581 * entries (if any), recalculating the hash along the way:
2583 curr
->lockdep_depth
= i
;
2584 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2586 for (i
++; i
< depth
; i
++) {
2587 hlock
= curr
->held_locks
+ i
;
2588 if (!__lock_acquire(hlock
->instance
,
2589 hlock
->class->subclass
, hlock
->trylock
,
2590 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2595 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2601 * Remove the lock to the list of currently held locks - this gets
2602 * called on mutex_unlock()/spin_unlock*() (or on a failed
2603 * mutex_lock_interruptible()). This is done for unlocks that nest
2604 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2606 static int lock_release_nested(struct task_struct
*curr
,
2607 struct lockdep_map
*lock
, unsigned long ip
)
2609 struct held_lock
*hlock
;
2613 * Pop off the top of the lock stack:
2615 depth
= curr
->lockdep_depth
- 1;
2616 hlock
= curr
->held_locks
+ depth
;
2619 * Is the unlock non-nested:
2621 if (hlock
->instance
!= lock
)
2622 return lock_release_non_nested(curr
, lock
, ip
);
2623 curr
->lockdep_depth
--;
2625 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2628 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2630 lock_release_holdtime(hlock
);
2632 #ifdef CONFIG_DEBUG_LOCKDEP
2633 hlock
->prev_chain_key
= 0;
2634 hlock
->class = NULL
;
2635 hlock
->acquire_ip
= 0;
2636 hlock
->irq_context
= 0;
2642 * Remove the lock to the list of currently held locks - this gets
2643 * called on mutex_unlock()/spin_unlock*() (or on a failed
2644 * mutex_lock_interruptible()). This is done for unlocks that nest
2645 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2648 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2650 struct task_struct
*curr
= current
;
2652 if (!check_unlock(curr
, lock
, ip
))
2656 if (!lock_release_nested(curr
, lock
, ip
))
2659 if (!lock_release_non_nested(curr
, lock
, ip
))
2663 check_chain_key(curr
);
2667 * Check whether we follow the irq-flags state precisely:
2669 static void check_flags(unsigned long flags
)
2671 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2675 if (irqs_disabled_flags(flags
)) {
2676 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
2677 printk("possible reason: unannotated irqs-off.\n");
2680 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
2681 printk("possible reason: unannotated irqs-on.\n");
2686 * We dont accurately track softirq state in e.g.
2687 * hardirq contexts (such as on 4KSTACKS), so only
2688 * check if not in hardirq contexts:
2690 if (!hardirq_count()) {
2691 if (softirq_count())
2692 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
2694 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
2698 print_irqtrace_events(current
);
2703 * We are not always called with irqs disabled - do that here,
2704 * and also avoid lockdep recursion:
2706 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2707 int trylock
, int read
, int check
, unsigned long ip
)
2709 unsigned long flags
;
2711 if (unlikely(!lock_stat
&& !prove_locking
))
2714 if (unlikely(current
->lockdep_recursion
))
2717 raw_local_irq_save(flags
);
2720 current
->lockdep_recursion
= 1;
2721 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
2722 irqs_disabled_flags(flags
), ip
);
2723 current
->lockdep_recursion
= 0;
2724 raw_local_irq_restore(flags
);
2727 EXPORT_SYMBOL_GPL(lock_acquire
);
2729 void lock_release(struct lockdep_map
*lock
, int nested
,
2732 unsigned long flags
;
2734 if (unlikely(!lock_stat
&& !prove_locking
))
2737 if (unlikely(current
->lockdep_recursion
))
2740 raw_local_irq_save(flags
);
2742 current
->lockdep_recursion
= 1;
2743 __lock_release(lock
, nested
, ip
);
2744 current
->lockdep_recursion
= 0;
2745 raw_local_irq_restore(flags
);
2748 EXPORT_SYMBOL_GPL(lock_release
);
2750 #ifdef CONFIG_LOCK_STAT
2752 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2755 if (!debug_locks_off())
2757 if (debug_locks_silent
)
2760 printk("\n=================================\n");
2761 printk( "[ BUG: bad contention detected! ]\n");
2762 printk( "---------------------------------\n");
2763 printk("%s/%d is trying to contend lock (",
2764 curr
->comm
, task_pid_nr(curr
));
2765 print_lockdep_cache(lock
);
2768 printk("but there are no locks held!\n");
2769 printk("\nother info that might help us debug this:\n");
2770 lockdep_print_held_locks(curr
);
2772 printk("\nstack backtrace:\n");
2779 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
2781 struct task_struct
*curr
= current
;
2782 struct held_lock
*hlock
, *prev_hlock
;
2783 struct lock_class_stats
*stats
;
2787 depth
= curr
->lockdep_depth
;
2788 if (DEBUG_LOCKS_WARN_ON(!depth
))
2792 for (i
= depth
-1; i
>= 0; i
--) {
2793 hlock
= curr
->held_locks
+ i
;
2795 * We must not cross into another context:
2797 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2799 if (hlock
->instance
== lock
)
2803 print_lock_contention_bug(curr
, lock
, ip
);
2807 hlock
->waittime_stamp
= sched_clock();
2809 point
= lock_contention_point(hlock
->class, ip
);
2811 stats
= get_lock_stats(hlock
->class);
2812 if (point
< ARRAY_SIZE(stats
->contention_point
))
2813 stats
->contention_point
[i
]++;
2814 if (lock
->cpu
!= smp_processor_id())
2815 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
2816 put_lock_stats(stats
);
2820 __lock_acquired(struct lockdep_map
*lock
)
2822 struct task_struct
*curr
= current
;
2823 struct held_lock
*hlock
, *prev_hlock
;
2824 struct lock_class_stats
*stats
;
2830 depth
= curr
->lockdep_depth
;
2831 if (DEBUG_LOCKS_WARN_ON(!depth
))
2835 for (i
= depth
-1; i
>= 0; i
--) {
2836 hlock
= curr
->held_locks
+ i
;
2838 * We must not cross into another context:
2840 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2842 if (hlock
->instance
== lock
)
2846 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
2850 cpu
= smp_processor_id();
2851 if (hlock
->waittime_stamp
) {
2852 now
= sched_clock();
2853 waittime
= now
- hlock
->waittime_stamp
;
2854 hlock
->holdtime_stamp
= now
;
2857 stats
= get_lock_stats(hlock
->class);
2860 lock_time_inc(&stats
->read_waittime
, waittime
);
2862 lock_time_inc(&stats
->write_waittime
, waittime
);
2864 if (lock
->cpu
!= cpu
)
2865 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
2866 put_lock_stats(stats
);
2871 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
2873 unsigned long flags
;
2875 if (unlikely(!lock_stat
))
2878 if (unlikely(current
->lockdep_recursion
))
2881 raw_local_irq_save(flags
);
2883 current
->lockdep_recursion
= 1;
2884 __lock_contended(lock
, ip
);
2885 current
->lockdep_recursion
= 0;
2886 raw_local_irq_restore(flags
);
2888 EXPORT_SYMBOL_GPL(lock_contended
);
2890 void lock_acquired(struct lockdep_map
*lock
)
2892 unsigned long flags
;
2894 if (unlikely(!lock_stat
))
2897 if (unlikely(current
->lockdep_recursion
))
2900 raw_local_irq_save(flags
);
2902 current
->lockdep_recursion
= 1;
2903 __lock_acquired(lock
);
2904 current
->lockdep_recursion
= 0;
2905 raw_local_irq_restore(flags
);
2907 EXPORT_SYMBOL_GPL(lock_acquired
);
2911 * Used by the testsuite, sanitize the validator state
2912 * after a simulated failure:
2915 void lockdep_reset(void)
2917 unsigned long flags
;
2920 raw_local_irq_save(flags
);
2921 current
->curr_chain_key
= 0;
2922 current
->lockdep_depth
= 0;
2923 current
->lockdep_recursion
= 0;
2924 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
2925 nr_hardirq_chains
= 0;
2926 nr_softirq_chains
= 0;
2927 nr_process_chains
= 0;
2929 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
2930 INIT_LIST_HEAD(chainhash_table
+ i
);
2931 raw_local_irq_restore(flags
);
2934 static void zap_class(struct lock_class
*class)
2939 * Remove all dependencies this lock is
2942 for (i
= 0; i
< nr_list_entries
; i
++) {
2943 if (list_entries
[i
].class == class)
2944 list_del_rcu(&list_entries
[i
].entry
);
2947 * Unhash the class and remove it from the all_lock_classes list:
2949 list_del_rcu(&class->hash_entry
);
2950 list_del_rcu(&class->lock_entry
);
2954 static inline int within(const void *addr
, void *start
, unsigned long size
)
2956 return addr
>= start
&& addr
< start
+ size
;
2959 void lockdep_free_key_range(void *start
, unsigned long size
)
2961 struct lock_class
*class, *next
;
2962 struct list_head
*head
;
2963 unsigned long flags
;
2967 raw_local_irq_save(flags
);
2968 locked
= graph_lock();
2971 * Unhash all classes that were created by this module:
2973 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
2974 head
= classhash_table
+ i
;
2975 if (list_empty(head
))
2977 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
2978 if (within(class->key
, start
, size
))
2980 else if (within(class->name
, start
, size
))
2987 raw_local_irq_restore(flags
);
2990 void lockdep_reset_lock(struct lockdep_map
*lock
)
2992 struct lock_class
*class, *next
;
2993 struct list_head
*head
;
2994 unsigned long flags
;
2998 raw_local_irq_save(flags
);
3001 * Remove all classes this lock might have:
3003 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3005 * If the class exists we look it up and zap it:
3007 class = look_up_lock_class(lock
, j
);
3012 * Debug check: in the end all mapped classes should
3015 locked
= graph_lock();
3016 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3017 head
= classhash_table
+ i
;
3018 if (list_empty(head
))
3020 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3021 if (unlikely(class == lock
->class_cache
)) {
3022 if (debug_locks_off_graph_unlock())
3032 raw_local_irq_restore(flags
);
3035 void lockdep_init(void)
3040 * Some architectures have their own start_kernel()
3041 * code which calls lockdep_init(), while we also
3042 * call lockdep_init() from the start_kernel() itself,
3043 * and we want to initialize the hashes only once:
3045 if (lockdep_initialized
)
3048 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3049 INIT_LIST_HEAD(classhash_table
+ i
);
3051 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3052 INIT_LIST_HEAD(chainhash_table
+ i
);
3054 lockdep_initialized
= 1;
3057 void __init
lockdep_info(void)
3059 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3061 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
3062 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
3063 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
3064 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
3065 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
3066 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
3067 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
3069 printk(" memory used by lock dependency info: %lu kB\n",
3070 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
3071 sizeof(struct list_head
) * CLASSHASH_SIZE
+
3072 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
3073 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
3074 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
3076 printk(" per task-struct memory footprint: %lu bytes\n",
3077 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
3079 #ifdef CONFIG_DEBUG_LOCKDEP
3080 if (lockdep_init_error
) {
3081 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3082 printk("Call stack leading to lockdep invocation was:\n");
3083 print_stack_trace(&lockdep_init_trace
, 0);
3089 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
3090 const void *mem_to
, struct held_lock
*hlock
)
3092 if (!debug_locks_off())
3094 if (debug_locks_silent
)
3097 printk("\n=========================\n");
3098 printk( "[ BUG: held lock freed! ]\n");
3099 printk( "-------------------------\n");
3100 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3101 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
3103 lockdep_print_held_locks(curr
);
3105 printk("\nstack backtrace:\n");
3109 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
3110 const void* lock_from
, unsigned long lock_len
)
3112 return lock_from
+ lock_len
<= mem_from
||
3113 mem_from
+ mem_len
<= lock_from
;
3117 * Called when kernel memory is freed (or unmapped), or if a lock
3118 * is destroyed or reinitialized - this code checks whether there is
3119 * any held lock in the memory range of <from> to <to>:
3121 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
3123 struct task_struct
*curr
= current
;
3124 struct held_lock
*hlock
;
3125 unsigned long flags
;
3128 if (unlikely(!debug_locks
))
3131 local_irq_save(flags
);
3132 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3133 hlock
= curr
->held_locks
+ i
;
3135 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
3136 sizeof(*hlock
->instance
)))
3139 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
3142 local_irq_restore(flags
);
3144 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
3146 static void print_held_locks_bug(struct task_struct
*curr
)
3148 if (!debug_locks_off())
3150 if (debug_locks_silent
)
3153 printk("\n=====================================\n");
3154 printk( "[ BUG: lock held at task exit time! ]\n");
3155 printk( "-------------------------------------\n");
3156 printk("%s/%d is exiting with locks still held!\n",
3157 curr
->comm
, task_pid_nr(curr
));
3158 lockdep_print_held_locks(curr
);
3160 printk("\nstack backtrace:\n");
3164 void debug_check_no_locks_held(struct task_struct
*task
)
3166 if (unlikely(task
->lockdep_depth
> 0))
3167 print_held_locks_bug(task
);
3170 void debug_show_all_locks(void)
3172 struct task_struct
*g
, *p
;
3176 if (unlikely(!debug_locks
)) {
3177 printk("INFO: lockdep is turned off.\n");
3180 printk("\nShowing all locks held in the system:\n");
3183 * Here we try to get the tasklist_lock as hard as possible,
3184 * if not successful after 2 seconds we ignore it (but keep
3185 * trying). This is to enable a debug printout even if a
3186 * tasklist_lock-holding task deadlocks or crashes.
3189 if (!read_trylock(&tasklist_lock
)) {
3191 printk("hm, tasklist_lock locked, retrying... ");
3194 printk(" #%d", 10-count
);
3198 printk(" ignoring it.\n");
3202 printk(" locked it.\n");
3204 do_each_thread(g
, p
) {
3206 * It's not reliable to print a task's held locks
3207 * if it's not sleeping (or if it's not the current
3210 if (p
->state
== TASK_RUNNING
&& p
!= current
)
3212 if (p
->lockdep_depth
)
3213 lockdep_print_held_locks(p
);
3215 if (read_trylock(&tasklist_lock
))
3217 } while_each_thread(g
, p
);
3220 printk("=============================================\n\n");
3223 read_unlock(&tasklist_lock
);
3226 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
3229 * Careful: only use this function if you are sure that
3230 * the task cannot run in parallel!
3232 void __debug_show_held_locks(struct task_struct
*task
)
3234 if (unlikely(!debug_locks
)) {
3235 printk("INFO: lockdep is turned off.\n");
3238 lockdep_print_held_locks(task
);
3240 EXPORT_SYMBOL_GPL(__debug_show_held_locks
);
3242 void debug_show_held_locks(struct task_struct
*task
)
3244 __debug_show_held_locks(task
);
3247 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
3249 void lockdep_sys_exit(void)
3251 struct task_struct
*curr
= current
;
3253 if (unlikely(curr
->lockdep_depth
)) {
3254 if (!debug_locks_off())
3256 printk("\n================================================\n");
3257 printk( "[ BUG: lock held when returning to user space! ]\n");
3258 printk( "------------------------------------------------\n");
3259 printk("%s/%d is leaving the kernel with locks still held!\n",
3260 curr
->comm
, curr
->pid
);
3261 lockdep_print_held_locks(curr
);