4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
48 #include <asm/sections.h>
50 #include "lockdep_internals.h"
52 #define CREATE_TRACE_POINTS
53 #include <trace/events/lock.h>
55 #ifdef CONFIG_PROVE_LOCKING
56 int prove_locking
= 1;
57 module_param(prove_locking
, int, 0644);
59 #define prove_locking 0
62 #ifdef CONFIG_LOCK_STAT
64 module_param(lock_stat
, int, 0644);
70 * lockdep_lock: protects the lockdep graph, the hashes and the
71 * class/list/hash allocators.
73 * This is one of the rare exceptions where it's justified
74 * to use a raw spinlock - we really dont want the spinlock
75 * code to recurse back into the lockdep code...
77 static arch_spinlock_t lockdep_lock
= (arch_spinlock_t
)__ARCH_SPIN_LOCK_UNLOCKED
;
79 static int graph_lock(void)
81 arch_spin_lock(&lockdep_lock
);
83 * Make sure that if another CPU detected a bug while
84 * walking the graph we dont change it (while the other
85 * CPU is busy printing out stuff with the graph lock
89 arch_spin_unlock(&lockdep_lock
);
92 /* prevent any recursions within lockdep from causing deadlocks */
93 current
->lockdep_recursion
++;
97 static inline int graph_unlock(void)
99 if (debug_locks
&& !arch_spin_is_locked(&lockdep_lock
))
100 return DEBUG_LOCKS_WARN_ON(1);
102 current
->lockdep_recursion
--;
103 arch_spin_unlock(&lockdep_lock
);
108 * Turn lock debugging off and return with 0 if it was off already,
109 * and also release the graph lock:
111 static inline int debug_locks_off_graph_unlock(void)
113 int ret
= debug_locks_off();
115 arch_spin_unlock(&lockdep_lock
);
120 static int lockdep_initialized
;
122 unsigned long nr_list_entries
;
123 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
126 * All data structures here are protected by the global debug_lock.
128 * Mutex key structs only get allocated, once during bootup, and never
129 * get freed - this significantly simplifies the debugging code.
131 unsigned long nr_lock_classes
;
132 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
134 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
136 if (!hlock
->class_idx
) {
137 DEBUG_LOCKS_WARN_ON(1);
140 return lock_classes
+ hlock
->class_idx
- 1;
143 #ifdef CONFIG_LOCK_STAT
144 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
],
147 static inline u64
lockstat_clock(void)
149 return cpu_clock(smp_processor_id());
152 static int lock_point(unsigned long points
[], unsigned long ip
)
156 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
157 if (points
[i
] == 0) {
168 static void lock_time_inc(struct lock_time
*lt
, u64 time
)
173 if (time
< lt
->min
|| !lt
->nr
)
180 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
185 if (src
->max
> dst
->max
)
188 if (src
->min
< dst
->min
|| !dst
->nr
)
191 dst
->total
+= src
->total
;
195 struct lock_class_stats
lock_stats(struct lock_class
*class)
197 struct lock_class_stats stats
;
200 memset(&stats
, 0, sizeof(struct lock_class_stats
));
201 for_each_possible_cpu(cpu
) {
202 struct lock_class_stats
*pcs
=
203 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
205 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
206 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
208 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
209 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
211 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
212 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
214 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
215 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
217 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
218 stats
.bounces
[i
] += pcs
->bounces
[i
];
224 void clear_lock_stats(struct lock_class
*class)
228 for_each_possible_cpu(cpu
) {
229 struct lock_class_stats
*cpu_stats
=
230 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
232 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
234 memset(class->contention_point
, 0, sizeof(class->contention_point
));
235 memset(class->contending_point
, 0, sizeof(class->contending_point
));
238 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
240 return &get_cpu_var(cpu_lock_stats
)[class - lock_classes
];
243 static void put_lock_stats(struct lock_class_stats
*stats
)
245 put_cpu_var(cpu_lock_stats
);
248 static void lock_release_holdtime(struct held_lock
*hlock
)
250 struct lock_class_stats
*stats
;
256 holdtime
= lockstat_clock() - hlock
->holdtime_stamp
;
258 stats
= get_lock_stats(hlock_class(hlock
));
260 lock_time_inc(&stats
->read_holdtime
, holdtime
);
262 lock_time_inc(&stats
->write_holdtime
, holdtime
);
263 put_lock_stats(stats
);
266 static inline void lock_release_holdtime(struct held_lock
*hlock
)
272 * We keep a global list of all lock classes. The list only grows,
273 * never shrinks. The list is only accessed with the lockdep
274 * spinlock lock held.
276 LIST_HEAD(all_lock_classes
);
279 * The lockdep classes are in a hash-table as well, for fast lookup:
281 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
282 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
283 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
284 #define classhashentry(key) (classhash_table + __classhashfn((key)))
286 static struct list_head classhash_table
[CLASSHASH_SIZE
];
289 * We put the lock dependency chains into a hash-table as well, to cache
292 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
293 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
294 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
295 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
297 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
300 * The hash key of the lock dependency chains is a hash itself too:
301 * it's a hash of all locks taken up to that lock, including that lock.
302 * It's a 64-bit hash, because it's important for the keys to be
305 #define iterate_chain_key(key1, key2) \
306 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
307 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
310 void lockdep_off(void)
312 current
->lockdep_recursion
++;
314 EXPORT_SYMBOL(lockdep_off
);
316 void lockdep_on(void)
318 current
->lockdep_recursion
--;
320 EXPORT_SYMBOL(lockdep_on
);
323 * Debugging switches:
327 #define VERY_VERBOSE 0
330 # define HARDIRQ_VERBOSE 1
331 # define SOFTIRQ_VERBOSE 1
332 # define RECLAIM_VERBOSE 1
334 # define HARDIRQ_VERBOSE 0
335 # define SOFTIRQ_VERBOSE 0
336 # define RECLAIM_VERBOSE 0
339 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
341 * Quick filtering for interesting events:
343 static int class_filter(struct lock_class
*class)
347 if (class->name_version
== 1 &&
348 !strcmp(class->name
, "lockname"))
350 if (class->name_version
== 1 &&
351 !strcmp(class->name
, "&struct->lockfield"))
354 /* Filter everything else. 1 would be to allow everything else */
359 static int verbose(struct lock_class
*class)
362 return class_filter(class);
368 * Stack-trace: tightly packed array of stack backtrace
369 * addresses. Protected by the graph_lock.
371 unsigned long nr_stack_trace_entries
;
372 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
374 static int save_trace(struct stack_trace
*trace
)
376 trace
->nr_entries
= 0;
377 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
378 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
382 save_stack_trace(trace
);
385 * Some daft arches put -1 at the end to indicate its a full trace.
387 * <rant> this is buggy anyway, since it takes a whole extra entry so a
388 * complete trace that maxes out the entries provided will be reported
389 * as incomplete, friggin useless </rant>
391 if (trace
->nr_entries
!= 0 &&
392 trace
->entries
[trace
->nr_entries
-1] == ULONG_MAX
)
395 trace
->max_entries
= trace
->nr_entries
;
397 nr_stack_trace_entries
+= trace
->nr_entries
;
399 if (nr_stack_trace_entries
>= MAX_STACK_TRACE_ENTRIES
-1) {
400 if (!debug_locks_off_graph_unlock())
403 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
404 printk("turning off the locking correctness validator.\n");
413 unsigned int nr_hardirq_chains
;
414 unsigned int nr_softirq_chains
;
415 unsigned int nr_process_chains
;
416 unsigned int max_lockdep_depth
;
418 #ifdef CONFIG_DEBUG_LOCKDEP
420 * We cannot printk in early bootup code. Not even early_printk()
421 * might work. So we mark any initialization errors and printk
422 * about it later on, in lockdep_info().
424 static int lockdep_init_error
;
425 static unsigned long lockdep_init_trace_data
[20];
426 static struct stack_trace lockdep_init_trace
= {
427 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
428 .entries
= lockdep_init_trace_data
,
432 * Various lockdep statistics:
434 DEFINE_PER_CPU(struct lockdep_stats
, lockdep_stats
);
441 #define __USAGE(__STATE) \
442 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
443 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
444 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
445 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
447 static const char *usage_str
[] =
449 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
450 #include "lockdep_states.h"
452 [LOCK_USED
] = "INITIAL USE",
455 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
457 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
460 static inline unsigned long lock_flag(enum lock_usage_bit bit
)
465 static char get_usage_char(struct lock_class
*class, enum lock_usage_bit bit
)
469 if (class->usage_mask
& lock_flag(bit
+ 2))
471 if (class->usage_mask
& lock_flag(bit
)) {
473 if (class->usage_mask
& lock_flag(bit
+ 2))
480 void get_usage_chars(struct lock_class
*class, char usage
[LOCK_USAGE_CHARS
])
484 #define LOCKDEP_STATE(__STATE) \
485 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
486 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
487 #include "lockdep_states.h"
493 static void print_lock_name(struct lock_class
*class)
495 char str
[KSYM_NAME_LEN
], usage
[LOCK_USAGE_CHARS
];
498 get_usage_chars(class, usage
);
502 name
= __get_key_name(class->key
, str
);
503 printk(" (%s", name
);
505 printk(" (%s", name
);
506 if (class->name_version
> 1)
507 printk("#%d", class->name_version
);
509 printk("/%d", class->subclass
);
511 printk("){%s}", usage
);
514 static void print_lockdep_cache(struct lockdep_map
*lock
)
517 char str
[KSYM_NAME_LEN
];
521 name
= __get_key_name(lock
->key
->subkeys
, str
);
526 static void print_lock(struct held_lock
*hlock
)
528 print_lock_name(hlock_class(hlock
));
530 print_ip_sym(hlock
->acquire_ip
);
533 static void lockdep_print_held_locks(struct task_struct
*curr
)
535 int i
, depth
= curr
->lockdep_depth
;
538 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
541 printk("%d lock%s held by %s/%d:\n",
542 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
544 for (i
= 0; i
< depth
; i
++) {
546 print_lock(curr
->held_locks
+ i
);
550 static void print_kernel_version(void)
552 printk("%s %.*s\n", init_utsname()->release
,
553 (int)strcspn(init_utsname()->version
, " "),
554 init_utsname()->version
);
557 static int very_verbose(struct lock_class
*class)
560 return class_filter(class);
566 * Is this the address of a static object:
568 static int static_obj(void *obj
)
570 unsigned long start
= (unsigned long) &_stext
,
571 end
= (unsigned long) &_end
,
572 addr
= (unsigned long) obj
;
577 if ((addr
>= start
) && (addr
< end
))
580 if (arch_is_kernel_data(addr
))
584 * in-kernel percpu var?
586 if (is_kernel_percpu_address(addr
))
590 * module static or percpu var?
592 return is_module_address(addr
) || is_module_percpu_address(addr
);
596 * To make lock name printouts unique, we calculate a unique
597 * class->name_version generation counter:
599 static int count_matching_names(struct lock_class
*new_class
)
601 struct lock_class
*class;
604 if (!new_class
->name
)
607 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
608 if (new_class
->key
- new_class
->subclass
== class->key
)
609 return class->name_version
;
610 if (class->name
&& !strcmp(class->name
, new_class
->name
))
611 count
= max(count
, class->name_version
);
618 * Register a lock's class in the hash-table, if the class is not present
619 * yet. Otherwise we look it up. We cache the result in the lock object
620 * itself, so actual lookup of the hash should be once per lock object.
622 static inline struct lock_class
*
623 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
625 struct lockdep_subclass_key
*key
;
626 struct list_head
*hash_head
;
627 struct lock_class
*class;
629 #ifdef CONFIG_DEBUG_LOCKDEP
631 * If the architecture calls into lockdep before initializing
632 * the hashes then we'll warn about it later. (we cannot printk
635 if (unlikely(!lockdep_initialized
)) {
637 lockdep_init_error
= 1;
638 save_stack_trace(&lockdep_init_trace
);
643 * Static locks do not have their class-keys yet - for them the key
644 * is the lock object itself:
646 if (unlikely(!lock
->key
))
647 lock
->key
= (void *)lock
;
650 * NOTE: the class-key must be unique. For dynamic locks, a static
651 * lock_class_key variable is passed in through the mutex_init()
652 * (or spin_lock_init()) call - which acts as the key. For static
653 * locks we use the lock object itself as the key.
655 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
656 sizeof(struct lockdep_map
));
658 key
= lock
->key
->subkeys
+ subclass
;
660 hash_head
= classhashentry(key
);
663 * We can walk the hash lockfree, because the hash only
664 * grows, and we are careful when adding entries to the end:
666 list_for_each_entry(class, hash_head
, hash_entry
) {
667 if (class->key
== key
) {
668 WARN_ON_ONCE(class->name
!= lock
->name
);
677 * Register a lock's class in the hash-table, if the class is not present
678 * yet. Otherwise we look it up. We cache the result in the lock object
679 * itself, so actual lookup of the hash should be once per lock object.
681 static inline struct lock_class
*
682 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
684 struct lockdep_subclass_key
*key
;
685 struct list_head
*hash_head
;
686 struct lock_class
*class;
689 class = look_up_lock_class(lock
, subclass
);
694 * Debug-check: all keys must be persistent!
696 if (!static_obj(lock
->key
)) {
698 printk("INFO: trying to register non-static key.\n");
699 printk("the code is fine but needs lockdep annotation.\n");
700 printk("turning off the locking correctness validator.\n");
706 key
= lock
->key
->subkeys
+ subclass
;
707 hash_head
= classhashentry(key
);
709 raw_local_irq_save(flags
);
711 raw_local_irq_restore(flags
);
715 * We have to do the hash-walk again, to avoid races
718 list_for_each_entry(class, hash_head
, hash_entry
)
719 if (class->key
== key
)
722 * Allocate a new key from the static array, and add it to
725 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
726 if (!debug_locks_off_graph_unlock()) {
727 raw_local_irq_restore(flags
);
730 raw_local_irq_restore(flags
);
732 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
733 printk("turning off the locking correctness validator.\n");
737 class = lock_classes
+ nr_lock_classes
++;
738 debug_atomic_inc(nr_unused_locks
);
740 class->name
= lock
->name
;
741 class->subclass
= subclass
;
742 INIT_LIST_HEAD(&class->lock_entry
);
743 INIT_LIST_HEAD(&class->locks_before
);
744 INIT_LIST_HEAD(&class->locks_after
);
745 class->name_version
= count_matching_names(class);
747 * We use RCU's safe list-add method to make
748 * parallel walking of the hash-list safe:
750 list_add_tail_rcu(&class->hash_entry
, hash_head
);
752 * Add it to the global list of classes:
754 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
756 if (verbose(class)) {
758 raw_local_irq_restore(flags
);
760 printk("\nnew class %p: %s", class->key
, class->name
);
761 if (class->name_version
> 1)
762 printk("#%d", class->name_version
);
766 raw_local_irq_save(flags
);
768 raw_local_irq_restore(flags
);
774 raw_local_irq_restore(flags
);
776 if (!subclass
|| force
)
777 lock
->class_cache
= class;
779 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
785 #ifdef CONFIG_PROVE_LOCKING
787 * Allocate a lockdep entry. (assumes the graph_lock held, returns
788 * with NULL on failure)
790 static struct lock_list
*alloc_list_entry(void)
792 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
793 if (!debug_locks_off_graph_unlock())
796 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
797 printk("turning off the locking correctness validator.\n");
801 return list_entries
+ nr_list_entries
++;
805 * Add a new dependency to the head of the list:
807 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
808 struct list_head
*head
, unsigned long ip
, int distance
)
810 struct lock_list
*entry
;
812 * Lock not present yet - get a new dependency struct and
813 * add it to the list:
815 entry
= alloc_list_entry();
819 if (!save_trace(&entry
->trace
))
823 entry
->distance
= distance
;
825 * Since we never remove from the dependency list, the list can
826 * be walked lockless by other CPUs, it's only allocation
827 * that must be protected by the spinlock. But this also means
828 * we must make new entries visible only once writes to the
829 * entry become visible - hence the RCU op:
831 list_add_tail_rcu(&entry
->entry
, head
);
837 * For good efficiency of modular, we use power of 2
839 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
840 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
843 * The circular_queue and helpers is used to implement the
844 * breadth-first search(BFS)algorithem, by which we can build
845 * the shortest path from the next lock to be acquired to the
846 * previous held lock if there is a circular between them.
848 struct circular_queue
{
849 unsigned long element
[MAX_CIRCULAR_QUEUE_SIZE
];
850 unsigned int front
, rear
;
853 static struct circular_queue lock_cq
;
855 unsigned int max_bfs_queue_depth
;
857 static unsigned int lockdep_dependency_gen_id
;
859 static inline void __cq_init(struct circular_queue
*cq
)
861 cq
->front
= cq
->rear
= 0;
862 lockdep_dependency_gen_id
++;
865 static inline int __cq_empty(struct circular_queue
*cq
)
867 return (cq
->front
== cq
->rear
);
870 static inline int __cq_full(struct circular_queue
*cq
)
872 return ((cq
->rear
+ 1) & CQ_MASK
) == cq
->front
;
875 static inline int __cq_enqueue(struct circular_queue
*cq
, unsigned long elem
)
880 cq
->element
[cq
->rear
] = elem
;
881 cq
->rear
= (cq
->rear
+ 1) & CQ_MASK
;
885 static inline int __cq_dequeue(struct circular_queue
*cq
, unsigned long *elem
)
890 *elem
= cq
->element
[cq
->front
];
891 cq
->front
= (cq
->front
+ 1) & CQ_MASK
;
895 static inline unsigned int __cq_get_elem_count(struct circular_queue
*cq
)
897 return (cq
->rear
- cq
->front
) & CQ_MASK
;
900 static inline void mark_lock_accessed(struct lock_list
*lock
,
901 struct lock_list
*parent
)
905 nr
= lock
- list_entries
;
906 WARN_ON(nr
>= nr_list_entries
);
907 lock
->parent
= parent
;
908 lock
->class->dep_gen_id
= lockdep_dependency_gen_id
;
911 static inline unsigned long lock_accessed(struct lock_list
*lock
)
915 nr
= lock
- list_entries
;
916 WARN_ON(nr
>= nr_list_entries
);
917 return lock
->class->dep_gen_id
== lockdep_dependency_gen_id
;
920 static inline struct lock_list
*get_lock_parent(struct lock_list
*child
)
922 return child
->parent
;
925 static inline int get_lock_depth(struct lock_list
*child
)
928 struct lock_list
*parent
;
930 while ((parent
= get_lock_parent(child
))) {
937 static int __bfs(struct lock_list
*source_entry
,
939 int (*match
)(struct lock_list
*entry
, void *data
),
940 struct lock_list
**target_entry
,
943 struct lock_list
*entry
;
944 struct list_head
*head
;
945 struct circular_queue
*cq
= &lock_cq
;
948 if (match(source_entry
, data
)) {
949 *target_entry
= source_entry
;
955 head
= &source_entry
->class->locks_after
;
957 head
= &source_entry
->class->locks_before
;
959 if (list_empty(head
))
963 __cq_enqueue(cq
, (unsigned long)source_entry
);
965 while (!__cq_empty(cq
)) {
966 struct lock_list
*lock
;
968 __cq_dequeue(cq
, (unsigned long *)&lock
);
976 head
= &lock
->class->locks_after
;
978 head
= &lock
->class->locks_before
;
980 list_for_each_entry(entry
, head
, entry
) {
981 if (!lock_accessed(entry
)) {
982 unsigned int cq_depth
;
983 mark_lock_accessed(entry
, lock
);
984 if (match(entry
, data
)) {
985 *target_entry
= entry
;
990 if (__cq_enqueue(cq
, (unsigned long)entry
)) {
994 cq_depth
= __cq_get_elem_count(cq
);
995 if (max_bfs_queue_depth
< cq_depth
)
996 max_bfs_queue_depth
= cq_depth
;
1004 static inline int __bfs_forwards(struct lock_list
*src_entry
,
1006 int (*match
)(struct lock_list
*entry
, void *data
),
1007 struct lock_list
**target_entry
)
1009 return __bfs(src_entry
, data
, match
, target_entry
, 1);
1013 static inline int __bfs_backwards(struct lock_list
*src_entry
,
1015 int (*match
)(struct lock_list
*entry
, void *data
),
1016 struct lock_list
**target_entry
)
1018 return __bfs(src_entry
, data
, match
, target_entry
, 0);
1023 * Recursive, forwards-direction lock-dependency checking, used for
1024 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1029 * Print a dependency chain entry (this is only done when a deadlock
1030 * has been detected):
1033 print_circular_bug_entry(struct lock_list
*target
, int depth
)
1035 if (debug_locks_silent
)
1037 printk("\n-> #%u", depth
);
1038 print_lock_name(target
->class);
1040 print_stack_trace(&target
->trace
, 6);
1046 * When a circular dependency is detected, print the
1050 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
,
1051 struct held_lock
*check_src
,
1052 struct held_lock
*check_tgt
)
1054 struct task_struct
*curr
= current
;
1056 if (debug_locks_silent
)
1059 printk("\n=======================================================\n");
1060 printk( "[ INFO: possible circular locking dependency detected ]\n");
1061 print_kernel_version();
1062 printk( "-------------------------------------------------------\n");
1063 printk("%s/%d is trying to acquire lock:\n",
1064 curr
->comm
, task_pid_nr(curr
));
1065 print_lock(check_src
);
1066 printk("\nbut task is already holding lock:\n");
1067 print_lock(check_tgt
);
1068 printk("\nwhich lock already depends on the new lock.\n\n");
1069 printk("\nthe existing dependency chain (in reverse order) is:\n");
1071 print_circular_bug_entry(entry
, depth
);
1076 static inline int class_equal(struct lock_list
*entry
, void *data
)
1078 return entry
->class == data
;
1081 static noinline
int print_circular_bug(struct lock_list
*this,
1082 struct lock_list
*target
,
1083 struct held_lock
*check_src
,
1084 struct held_lock
*check_tgt
)
1086 struct task_struct
*curr
= current
;
1087 struct lock_list
*parent
;
1090 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1093 if (!save_trace(&this->trace
))
1096 depth
= get_lock_depth(target
);
1098 print_circular_bug_header(target
, depth
, check_src
, check_tgt
);
1100 parent
= get_lock_parent(target
);
1103 print_circular_bug_entry(parent
, --depth
);
1104 parent
= get_lock_parent(parent
);
1107 printk("\nother info that might help us debug this:\n\n");
1108 lockdep_print_held_locks(curr
);
1110 printk("\nstack backtrace:\n");
1116 static noinline
int print_bfs_bug(int ret
)
1118 if (!debug_locks_off_graph_unlock())
1121 WARN(1, "lockdep bfs error:%d\n", ret
);
1126 static int noop_count(struct lock_list
*entry
, void *data
)
1128 (*(unsigned long *)data
)++;
1132 unsigned long __lockdep_count_forward_deps(struct lock_list
*this)
1134 unsigned long count
= 0;
1135 struct lock_list
*uninitialized_var(target_entry
);
1137 __bfs_forwards(this, (void *)&count
, noop_count
, &target_entry
);
1141 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1143 unsigned long ret
, flags
;
1144 struct lock_list
this;
1149 local_irq_save(flags
);
1150 arch_spin_lock(&lockdep_lock
);
1151 ret
= __lockdep_count_forward_deps(&this);
1152 arch_spin_unlock(&lockdep_lock
);
1153 local_irq_restore(flags
);
1158 unsigned long __lockdep_count_backward_deps(struct lock_list
*this)
1160 unsigned long count
= 0;
1161 struct lock_list
*uninitialized_var(target_entry
);
1163 __bfs_backwards(this, (void *)&count
, noop_count
, &target_entry
);
1168 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1170 unsigned long ret
, flags
;
1171 struct lock_list
this;
1176 local_irq_save(flags
);
1177 arch_spin_lock(&lockdep_lock
);
1178 ret
= __lockdep_count_backward_deps(&this);
1179 arch_spin_unlock(&lockdep_lock
);
1180 local_irq_restore(flags
);
1186 * Prove that the dependency graph starting at <entry> can not
1187 * lead to <target>. Print an error and return 0 if it does.
1190 check_noncircular(struct lock_list
*root
, struct lock_class
*target
,
1191 struct lock_list
**target_entry
)
1195 debug_atomic_inc(nr_cyclic_checks
);
1197 result
= __bfs_forwards(root
, target
, class_equal
, target_entry
);
1202 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1204 * Forwards and backwards subgraph searching, for the purposes of
1205 * proving that two subgraphs can be connected by a new dependency
1206 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1209 static inline int usage_match(struct lock_list
*entry
, void *bit
)
1211 return entry
->class->usage_mask
& (1 << (enum lock_usage_bit
)bit
);
1217 * Find a node in the forwards-direction dependency sub-graph starting
1218 * at @root->class that matches @bit.
1220 * Return 0 if such a node exists in the subgraph, and put that node
1221 * into *@target_entry.
1223 * Return 1 otherwise and keep *@target_entry unchanged.
1224 * Return <0 on error.
1227 find_usage_forwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1228 struct lock_list
**target_entry
)
1232 debug_atomic_inc(nr_find_usage_forwards_checks
);
1234 result
= __bfs_forwards(root
, (void *)bit
, usage_match
, target_entry
);
1240 * Find a node in the backwards-direction dependency sub-graph starting
1241 * at @root->class that matches @bit.
1243 * Return 0 if such a node exists in the subgraph, and put that node
1244 * into *@target_entry.
1246 * Return 1 otherwise and keep *@target_entry unchanged.
1247 * Return <0 on error.
1250 find_usage_backwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1251 struct lock_list
**target_entry
)
1255 debug_atomic_inc(nr_find_usage_backwards_checks
);
1257 result
= __bfs_backwards(root
, (void *)bit
, usage_match
, target_entry
);
1262 static void print_lock_class_header(struct lock_class
*class, int depth
)
1266 printk("%*s->", depth
, "");
1267 print_lock_name(class);
1268 printk(" ops: %lu", class->ops
);
1271 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
1272 if (class->usage_mask
& (1 << bit
)) {
1275 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
1276 len
+= printk(" at:\n");
1277 print_stack_trace(class->usage_traces
+ bit
, len
);
1280 printk("%*s }\n", depth
, "");
1282 printk("%*s ... key at: ",depth
,"");
1283 print_ip_sym((unsigned long)class->key
);
1287 * printk the shortest lock dependencies from @start to @end in reverse order:
1290 print_shortest_lock_dependencies(struct lock_list
*leaf
,
1291 struct lock_list
*root
)
1293 struct lock_list
*entry
= leaf
;
1296 /*compute depth from generated tree by BFS*/
1297 depth
= get_lock_depth(leaf
);
1300 print_lock_class_header(entry
->class, depth
);
1301 printk("%*s ... acquired at:\n", depth
, "");
1302 print_stack_trace(&entry
->trace
, 2);
1305 if (depth
== 0 && (entry
!= root
)) {
1306 printk("lockdep:%s bad BFS generated tree\n", __func__
);
1310 entry
= get_lock_parent(entry
);
1312 } while (entry
&& (depth
>= 0));
1318 print_bad_irq_dependency(struct task_struct
*curr
,
1319 struct lock_list
*prev_root
,
1320 struct lock_list
*next_root
,
1321 struct lock_list
*backwards_entry
,
1322 struct lock_list
*forwards_entry
,
1323 struct held_lock
*prev
,
1324 struct held_lock
*next
,
1325 enum lock_usage_bit bit1
,
1326 enum lock_usage_bit bit2
,
1327 const char *irqclass
)
1329 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1332 printk("\n======================================================\n");
1333 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1334 irqclass
, irqclass
);
1335 print_kernel_version();
1336 printk( "------------------------------------------------------\n");
1337 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1338 curr
->comm
, task_pid_nr(curr
),
1339 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1340 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1341 curr
->hardirqs_enabled
,
1342 curr
->softirqs_enabled
);
1345 printk("\nand this task is already holding:\n");
1347 printk("which would create a new lock dependency:\n");
1348 print_lock_name(hlock_class(prev
));
1350 print_lock_name(hlock_class(next
));
1353 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1355 print_lock_name(backwards_entry
->class);
1356 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1358 print_stack_trace(backwards_entry
->class->usage_traces
+ bit1
, 1);
1360 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1361 print_lock_name(forwards_entry
->class);
1362 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1365 print_stack_trace(forwards_entry
->class->usage_traces
+ bit2
, 1);
1367 printk("\nother info that might help us debug this:\n\n");
1368 lockdep_print_held_locks(curr
);
1370 printk("\nthe dependencies between %s-irq-safe lock", irqclass
);
1371 printk(" and the holding lock:\n");
1372 if (!save_trace(&prev_root
->trace
))
1374 print_shortest_lock_dependencies(backwards_entry
, prev_root
);
1376 printk("\nthe dependencies between the lock to be acquired");
1377 printk(" and %s-irq-unsafe lock:\n", irqclass
);
1378 if (!save_trace(&next_root
->trace
))
1380 print_shortest_lock_dependencies(forwards_entry
, next_root
);
1382 printk("\nstack backtrace:\n");
1389 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1390 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1391 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1394 struct lock_list
this, that
;
1395 struct lock_list
*uninitialized_var(target_entry
);
1396 struct lock_list
*uninitialized_var(target_entry1
);
1400 this.class = hlock_class(prev
);
1401 ret
= find_usage_backwards(&this, bit_backwards
, &target_entry
);
1403 return print_bfs_bug(ret
);
1408 that
.class = hlock_class(next
);
1409 ret
= find_usage_forwards(&that
, bit_forwards
, &target_entry1
);
1411 return print_bfs_bug(ret
);
1415 return print_bad_irq_dependency(curr
, &this, &that
,
1416 target_entry
, target_entry1
,
1418 bit_backwards
, bit_forwards
, irqclass
);
1421 static const char *state_names
[] = {
1422 #define LOCKDEP_STATE(__STATE) \
1423 __stringify(__STATE),
1424 #include "lockdep_states.h"
1425 #undef LOCKDEP_STATE
1428 static const char *state_rnames
[] = {
1429 #define LOCKDEP_STATE(__STATE) \
1430 __stringify(__STATE)"-READ",
1431 #include "lockdep_states.h"
1432 #undef LOCKDEP_STATE
1435 static inline const char *state_name(enum lock_usage_bit bit
)
1437 return (bit
& 1) ? state_rnames
[bit
>> 2] : state_names
[bit
>> 2];
1440 static int exclusive_bit(int new_bit
)
1448 * bit 0 - write/read
1449 * bit 1 - used_in/enabled
1453 int state
= new_bit
& ~3;
1454 int dir
= new_bit
& 2;
1457 * keep state, bit flip the direction and strip read.
1459 return state
| (dir
^ 2);
1462 static int check_irq_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1463 struct held_lock
*next
, enum lock_usage_bit bit
)
1466 * Prove that the new dependency does not connect a hardirq-safe
1467 * lock with a hardirq-unsafe lock - to achieve this we search
1468 * the backwards-subgraph starting at <prev>, and the
1469 * forwards-subgraph starting at <next>:
1471 if (!check_usage(curr
, prev
, next
, bit
,
1472 exclusive_bit(bit
), state_name(bit
)))
1478 * Prove that the new dependency does not connect a hardirq-safe-read
1479 * lock with a hardirq-unsafe lock - to achieve this we search
1480 * the backwards-subgraph starting at <prev>, and the
1481 * forwards-subgraph starting at <next>:
1483 if (!check_usage(curr
, prev
, next
, bit
,
1484 exclusive_bit(bit
), state_name(bit
)))
1491 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1492 struct held_lock
*next
)
1494 #define LOCKDEP_STATE(__STATE) \
1495 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1497 #include "lockdep_states.h"
1498 #undef LOCKDEP_STATE
1503 static void inc_chains(void)
1505 if (current
->hardirq_context
)
1506 nr_hardirq_chains
++;
1508 if (current
->softirq_context
)
1509 nr_softirq_chains
++;
1511 nr_process_chains
++;
1518 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1519 struct held_lock
*next
)
1524 static inline void inc_chains(void)
1526 nr_process_chains
++;
1532 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1533 struct held_lock
*next
)
1535 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1538 printk("\n=============================================\n");
1539 printk( "[ INFO: possible recursive locking detected ]\n");
1540 print_kernel_version();
1541 printk( "---------------------------------------------\n");
1542 printk("%s/%d is trying to acquire lock:\n",
1543 curr
->comm
, task_pid_nr(curr
));
1545 printk("\nbut task is already holding lock:\n");
1548 printk("\nother info that might help us debug this:\n");
1549 lockdep_print_held_locks(curr
);
1551 printk("\nstack backtrace:\n");
1558 * Check whether we are holding such a class already.
1560 * (Note that this has to be done separately, because the graph cannot
1561 * detect such classes of deadlocks.)
1563 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1566 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1567 struct lockdep_map
*next_instance
, int read
)
1569 struct held_lock
*prev
;
1570 struct held_lock
*nest
= NULL
;
1573 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1574 prev
= curr
->held_locks
+ i
;
1576 if (prev
->instance
== next
->nest_lock
)
1579 if (hlock_class(prev
) != hlock_class(next
))
1583 * Allow read-after-read recursion of the same
1584 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1586 if ((read
== 2) && prev
->read
)
1590 * We're holding the nest_lock, which serializes this lock's
1591 * nesting behaviour.
1596 return print_deadlock_bug(curr
, prev
, next
);
1602 * There was a chain-cache miss, and we are about to add a new dependency
1603 * to a previous lock. We recursively validate the following rules:
1605 * - would the adding of the <prev> -> <next> dependency create a
1606 * circular dependency in the graph? [== circular deadlock]
1608 * - does the new prev->next dependency connect any hardirq-safe lock
1609 * (in the full backwards-subgraph starting at <prev>) with any
1610 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1611 * <next>)? [== illegal lock inversion with hardirq contexts]
1613 * - does the new prev->next dependency connect any softirq-safe lock
1614 * (in the full backwards-subgraph starting at <prev>) with any
1615 * softirq-unsafe lock (in the full forwards-subgraph starting at
1616 * <next>)? [== illegal lock inversion with softirq contexts]
1618 * any of these scenarios could lead to a deadlock.
1620 * Then if all the validations pass, we add the forwards and backwards
1624 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1625 struct held_lock
*next
, int distance
)
1627 struct lock_list
*entry
;
1629 struct lock_list
this;
1630 struct lock_list
*uninitialized_var(target_entry
);
1633 * Prove that the new <prev> -> <next> dependency would not
1634 * create a circular dependency in the graph. (We do this by
1635 * forward-recursing into the graph starting at <next>, and
1636 * checking whether we can reach <prev>.)
1638 * We are using global variables to control the recursion, to
1639 * keep the stackframe size of the recursive functions low:
1641 this.class = hlock_class(next
);
1643 ret
= check_noncircular(&this, hlock_class(prev
), &target_entry
);
1645 return print_circular_bug(&this, target_entry
, next
, prev
);
1646 else if (unlikely(ret
< 0))
1647 return print_bfs_bug(ret
);
1649 if (!check_prev_add_irq(curr
, prev
, next
))
1653 * For recursive read-locks we do all the dependency checks,
1654 * but we dont store read-triggered dependencies (only
1655 * write-triggered dependencies). This ensures that only the
1656 * write-side dependencies matter, and that if for example a
1657 * write-lock never takes any other locks, then the reads are
1658 * equivalent to a NOP.
1660 if (next
->read
== 2 || prev
->read
== 2)
1663 * Is the <prev> -> <next> dependency already present?
1665 * (this may occur even though this is a new chain: consider
1666 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1667 * chains - the second one will be new, but L1 already has
1668 * L2 added to its dependency list, due to the first chain.)
1670 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1671 if (entry
->class == hlock_class(next
)) {
1673 entry
->distance
= 1;
1679 * Ok, all validations passed, add the new lock
1680 * to the previous lock's dependency list:
1682 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1683 &hlock_class(prev
)->locks_after
,
1684 next
->acquire_ip
, distance
);
1689 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1690 &hlock_class(next
)->locks_before
,
1691 next
->acquire_ip
, distance
);
1696 * Debugging printouts:
1698 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1700 printk("\n new dependency: ");
1701 print_lock_name(hlock_class(prev
));
1703 print_lock_name(hlock_class(next
));
1706 return graph_lock();
1712 * Add the dependency to all directly-previous locks that are 'relevant'.
1713 * The ones that are relevant are (in increasing distance from curr):
1714 * all consecutive trylock entries and the final non-trylock entry - or
1715 * the end of this context's lock-chain - whichever comes first.
1718 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1720 int depth
= curr
->lockdep_depth
;
1721 struct held_lock
*hlock
;
1726 * Depth must not be zero for a non-head lock:
1731 * At least two relevant locks must exist for this
1734 if (curr
->held_locks
[depth
].irq_context
!=
1735 curr
->held_locks
[depth
-1].irq_context
)
1739 int distance
= curr
->lockdep_depth
- depth
+ 1;
1740 hlock
= curr
->held_locks
+ depth
-1;
1742 * Only non-recursive-read entries get new dependencies
1745 if (hlock
->read
!= 2) {
1746 if (!check_prev_add(curr
, hlock
, next
, distance
))
1749 * Stop after the first non-trylock entry,
1750 * as non-trylock entries have added their
1751 * own direct dependencies already, so this
1752 * lock is connected to them indirectly:
1754 if (!hlock
->trylock
)
1759 * End of lock-stack?
1764 * Stop the search if we cross into another context:
1766 if (curr
->held_locks
[depth
].irq_context
!=
1767 curr
->held_locks
[depth
-1].irq_context
)
1772 if (!debug_locks_off_graph_unlock())
1780 unsigned long nr_lock_chains
;
1781 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1782 int nr_chain_hlocks
;
1783 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1785 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1787 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1791 * Look up a dependency chain. If the key is not present yet then
1792 * add it and return 1 - in this case the new dependency chain is
1793 * validated. If the key is already hashed, return 0.
1794 * (On return with 1 graph_lock is held.)
1796 static inline int lookup_chain_cache(struct task_struct
*curr
,
1797 struct held_lock
*hlock
,
1800 struct lock_class
*class = hlock_class(hlock
);
1801 struct list_head
*hash_head
= chainhashentry(chain_key
);
1802 struct lock_chain
*chain
;
1803 struct held_lock
*hlock_curr
, *hlock_next
;
1806 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1809 * We can walk it lock-free, because entries only get added
1812 list_for_each_entry(chain
, hash_head
, entry
) {
1813 if (chain
->chain_key
== chain_key
) {
1815 debug_atomic_inc(chain_lookup_hits
);
1816 if (very_verbose(class))
1817 printk("\nhash chain already cached, key: "
1818 "%016Lx tail class: [%p] %s\n",
1819 (unsigned long long)chain_key
,
1820 class->key
, class->name
);
1824 if (very_verbose(class))
1825 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1826 (unsigned long long)chain_key
, class->key
, class->name
);
1828 * Allocate a new chain entry from the static array, and add
1834 * We have to walk the chain again locked - to avoid duplicates:
1836 list_for_each_entry(chain
, hash_head
, entry
) {
1837 if (chain
->chain_key
== chain_key
) {
1842 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1843 if (!debug_locks_off_graph_unlock())
1846 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1847 printk("turning off the locking correctness validator.\n");
1851 chain
= lock_chains
+ nr_lock_chains
++;
1852 chain
->chain_key
= chain_key
;
1853 chain
->irq_context
= hlock
->irq_context
;
1854 /* Find the first held_lock of current chain */
1856 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
1857 hlock_curr
= curr
->held_locks
+ i
;
1858 if (hlock_curr
->irq_context
!= hlock_next
->irq_context
)
1863 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
1864 cn
= nr_chain_hlocks
;
1865 while (cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
) {
1866 n
= cmpxchg(&nr_chain_hlocks
, cn
, cn
+ chain
->depth
);
1871 if (likely(cn
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
1873 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
1874 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
1875 chain_hlocks
[chain
->base
+ j
] = lock_id
;
1877 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
1879 list_add_tail_rcu(&chain
->entry
, hash_head
);
1880 debug_atomic_inc(chain_lookup_misses
);
1886 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
1887 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
1890 * Trylock needs to maintain the stack of held locks, but it
1891 * does not add new dependencies, because trylock can be done
1894 * We look up the chain_key and do the O(N^2) check and update of
1895 * the dependencies only if this is a new dependency chain.
1896 * (If lookup_chain_cache() returns with 1 it acquires
1897 * graph_lock for us)
1899 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
1900 lookup_chain_cache(curr
, hlock
, chain_key
)) {
1902 * Check whether last held lock:
1904 * - is irq-safe, if this lock is irq-unsafe
1905 * - is softirq-safe, if this lock is hardirq-unsafe
1907 * And check whether the new lock's dependency graph
1908 * could lead back to the previous lock.
1910 * any of these scenarios could lead to a deadlock. If
1913 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
1918 * Mark recursive read, as we jump over it when
1919 * building dependencies (just like we jump over
1925 * Add dependency only if this lock is not the head
1926 * of the chain, and if it's not a secondary read-lock:
1928 if (!chain_head
&& ret
!= 2)
1929 if (!check_prevs_add(curr
, hlock
))
1933 /* after lookup_chain_cache(): */
1934 if (unlikely(!debug_locks
))
1940 static inline int validate_chain(struct task_struct
*curr
,
1941 struct lockdep_map
*lock
, struct held_lock
*hlock
,
1942 int chain_head
, u64 chain_key
)
1949 * We are building curr_chain_key incrementally, so double-check
1950 * it from scratch, to make sure that it's done correctly:
1952 static void check_chain_key(struct task_struct
*curr
)
1954 #ifdef CONFIG_DEBUG_LOCKDEP
1955 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1959 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1960 hlock
= curr
->held_locks
+ i
;
1961 if (chain_key
!= hlock
->prev_chain_key
) {
1963 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1964 curr
->lockdep_depth
, i
,
1965 (unsigned long long)chain_key
,
1966 (unsigned long long)hlock
->prev_chain_key
);
1969 id
= hlock
->class_idx
- 1;
1970 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
1973 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1974 hlock
->irq_context
))
1976 chain_key
= iterate_chain_key(chain_key
, id
);
1979 if (chain_key
!= curr
->curr_chain_key
) {
1981 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1982 curr
->lockdep_depth
, i
,
1983 (unsigned long long)chain_key
,
1984 (unsigned long long)curr
->curr_chain_key
);
1990 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1991 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1993 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1996 printk("\n=================================\n");
1997 printk( "[ INFO: inconsistent lock state ]\n");
1998 print_kernel_version();
1999 printk( "---------------------------------\n");
2001 printk("inconsistent {%s} -> {%s} usage.\n",
2002 usage_str
[prev_bit
], usage_str
[new_bit
]);
2004 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2005 curr
->comm
, task_pid_nr(curr
),
2006 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
2007 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
2008 trace_hardirqs_enabled(curr
),
2009 trace_softirqs_enabled(curr
));
2012 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
2013 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
2015 print_irqtrace_events(curr
);
2016 printk("\nother info that might help us debug this:\n");
2017 lockdep_print_held_locks(curr
);
2019 printk("\nstack backtrace:\n");
2026 * Print out an error if an invalid bit is set:
2029 valid_state(struct task_struct
*curr
, struct held_lock
*this,
2030 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
2032 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
2033 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
2037 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2038 enum lock_usage_bit new_bit
);
2040 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2043 * print irq inversion bug:
2046 print_irq_inversion_bug(struct task_struct
*curr
,
2047 struct lock_list
*root
, struct lock_list
*other
,
2048 struct held_lock
*this, int forwards
,
2049 const char *irqclass
)
2051 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2054 printk("\n=========================================================\n");
2055 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
2056 print_kernel_version();
2057 printk( "---------------------------------------------------------\n");
2058 printk("%s/%d just changed the state of lock:\n",
2059 curr
->comm
, task_pid_nr(curr
));
2062 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass
);
2064 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass
);
2065 print_lock_name(other
->class);
2066 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2068 printk("\nother info that might help us debug this:\n");
2069 lockdep_print_held_locks(curr
);
2071 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2072 if (!save_trace(&root
->trace
))
2074 print_shortest_lock_dependencies(other
, root
);
2076 printk("\nstack backtrace:\n");
2083 * Prove that in the forwards-direction subgraph starting at <this>
2084 * there is no lock matching <mask>:
2087 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
2088 enum lock_usage_bit bit
, const char *irqclass
)
2091 struct lock_list root
;
2092 struct lock_list
*uninitialized_var(target_entry
);
2095 root
.class = hlock_class(this);
2096 ret
= find_usage_forwards(&root
, bit
, &target_entry
);
2098 return print_bfs_bug(ret
);
2102 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2107 * Prove that in the backwards-direction subgraph starting at <this>
2108 * there is no lock matching <mask>:
2111 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
2112 enum lock_usage_bit bit
, const char *irqclass
)
2115 struct lock_list root
;
2116 struct lock_list
*uninitialized_var(target_entry
);
2119 root
.class = hlock_class(this);
2120 ret
= find_usage_backwards(&root
, bit
, &target_entry
);
2122 return print_bfs_bug(ret
);
2126 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2130 void print_irqtrace_events(struct task_struct
*curr
)
2132 printk("irq event stamp: %u\n", curr
->irq_events
);
2133 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
2134 print_ip_sym(curr
->hardirq_enable_ip
);
2135 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
2136 print_ip_sym(curr
->hardirq_disable_ip
);
2137 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
2138 print_ip_sym(curr
->softirq_enable_ip
);
2139 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
2140 print_ip_sym(curr
->softirq_disable_ip
);
2143 static int HARDIRQ_verbose(struct lock_class
*class)
2146 return class_filter(class);
2151 static int SOFTIRQ_verbose(struct lock_class
*class)
2154 return class_filter(class);
2159 static int RECLAIM_FS_verbose(struct lock_class
*class)
2162 return class_filter(class);
2167 #define STRICT_READ_CHECKS 1
2169 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2170 #define LOCKDEP_STATE(__STATE) \
2172 #include "lockdep_states.h"
2173 #undef LOCKDEP_STATE
2176 static inline int state_verbose(enum lock_usage_bit bit
,
2177 struct lock_class
*class)
2179 return state_verbose_f
[bit
>> 2](class);
2182 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2183 enum lock_usage_bit bit
, const char *name
);
2186 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2187 enum lock_usage_bit new_bit
)
2189 int excl_bit
= exclusive_bit(new_bit
);
2190 int read
= new_bit
& 1;
2191 int dir
= new_bit
& 2;
2194 * mark USED_IN has to look forwards -- to ensure no dependency
2195 * has ENABLED state, which would allow recursion deadlocks.
2197 * mark ENABLED has to look backwards -- to ensure no dependee
2198 * has USED_IN state, which, again, would allow recursion deadlocks.
2200 check_usage_f usage
= dir
?
2201 check_usage_backwards
: check_usage_forwards
;
2204 * Validate that this particular lock does not have conflicting
2207 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2211 * Validate that the lock dependencies don't have conflicting usage
2214 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2215 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2219 * Check for read in write conflicts
2222 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2225 if (STRICT_READ_CHECKS
&&
2226 !usage(curr
, this, excl_bit
+ 1,
2227 state_name(new_bit
+ 1)))
2231 if (state_verbose(new_bit
, hlock_class(this)))
2238 #define LOCKDEP_STATE(__STATE) __STATE,
2239 #include "lockdep_states.h"
2240 #undef LOCKDEP_STATE
2244 * Mark all held locks with a usage bit:
2247 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2249 enum lock_usage_bit usage_bit
;
2250 struct held_lock
*hlock
;
2253 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2254 hlock
= curr
->held_locks
+ i
;
2256 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2258 usage_bit
+= 1; /* READ */
2260 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2262 if (!mark_lock(curr
, hlock
, usage_bit
))
2270 * Debugging helper: via this flag we know that we are in
2271 * 'early bootup code', and will warn about any invalid irqs-on event:
2273 static int early_boot_irqs_enabled
;
2275 void early_boot_irqs_off(void)
2277 early_boot_irqs_enabled
= 0;
2280 void early_boot_irqs_on(void)
2282 early_boot_irqs_enabled
= 1;
2286 * Hardirqs will be enabled:
2288 void trace_hardirqs_on_caller(unsigned long ip
)
2290 struct task_struct
*curr
= current
;
2292 time_hardirqs_on(CALLER_ADDR0
, ip
);
2294 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2297 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
2300 if (unlikely(curr
->hardirqs_enabled
)) {
2302 * Neither irq nor preemption are disabled here
2303 * so this is racy by nature but loosing one hit
2304 * in a stat is not a big deal.
2306 this_cpu_inc(lockdep_stats
.redundant_hardirqs_on
);
2309 /* we'll do an OFF -> ON transition: */
2310 curr
->hardirqs_enabled
= 1;
2312 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2314 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2317 * We are going to turn hardirqs on, so set the
2318 * usage bit for all held locks:
2320 if (!mark_held_locks(curr
, HARDIRQ
))
2323 * If we have softirqs enabled, then set the usage
2324 * bit for all held locks. (disabled hardirqs prevented
2325 * this bit from being set before)
2327 if (curr
->softirqs_enabled
)
2328 if (!mark_held_locks(curr
, SOFTIRQ
))
2331 curr
->hardirq_enable_ip
= ip
;
2332 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2333 debug_atomic_inc(hardirqs_on_events
);
2335 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2337 void trace_hardirqs_on(void)
2339 trace_hardirqs_on_caller(CALLER_ADDR0
);
2341 EXPORT_SYMBOL(trace_hardirqs_on
);
2344 * Hardirqs were disabled:
2346 void trace_hardirqs_off_caller(unsigned long ip
)
2348 struct task_struct
*curr
= current
;
2350 time_hardirqs_off(CALLER_ADDR0
, ip
);
2352 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2355 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2358 if (curr
->hardirqs_enabled
) {
2360 * We have done an ON -> OFF transition:
2362 curr
->hardirqs_enabled
= 0;
2363 curr
->hardirq_disable_ip
= ip
;
2364 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2365 debug_atomic_inc(hardirqs_off_events
);
2367 debug_atomic_inc(redundant_hardirqs_off
);
2369 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2371 void trace_hardirqs_off(void)
2373 trace_hardirqs_off_caller(CALLER_ADDR0
);
2375 EXPORT_SYMBOL(trace_hardirqs_off
);
2378 * Softirqs will be enabled:
2380 void trace_softirqs_on(unsigned long ip
)
2382 struct task_struct
*curr
= current
;
2384 if (unlikely(!debug_locks
))
2387 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2390 if (curr
->softirqs_enabled
) {
2391 debug_atomic_inc(redundant_softirqs_on
);
2396 * We'll do an OFF -> ON transition:
2398 curr
->softirqs_enabled
= 1;
2399 curr
->softirq_enable_ip
= ip
;
2400 curr
->softirq_enable_event
= ++curr
->irq_events
;
2401 debug_atomic_inc(softirqs_on_events
);
2403 * We are going to turn softirqs on, so set the
2404 * usage bit for all held locks, if hardirqs are
2407 if (curr
->hardirqs_enabled
)
2408 mark_held_locks(curr
, SOFTIRQ
);
2412 * Softirqs were disabled:
2414 void trace_softirqs_off(unsigned long ip
)
2416 struct task_struct
*curr
= current
;
2418 if (unlikely(!debug_locks
))
2421 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2424 if (curr
->softirqs_enabled
) {
2426 * We have done an ON -> OFF transition:
2428 curr
->softirqs_enabled
= 0;
2429 curr
->softirq_disable_ip
= ip
;
2430 curr
->softirq_disable_event
= ++curr
->irq_events
;
2431 debug_atomic_inc(softirqs_off_events
);
2432 DEBUG_LOCKS_WARN_ON(!softirq_count());
2434 debug_atomic_inc(redundant_softirqs_off
);
2437 static void __lockdep_trace_alloc(gfp_t gfp_mask
, unsigned long flags
)
2439 struct task_struct
*curr
= current
;
2441 if (unlikely(!debug_locks
))
2444 /* no reclaim without waiting on it */
2445 if (!(gfp_mask
& __GFP_WAIT
))
2448 /* this guy won't enter reclaim */
2449 if ((curr
->flags
& PF_MEMALLOC
) && !(gfp_mask
& __GFP_NOMEMALLOC
))
2452 /* We're only interested __GFP_FS allocations for now */
2453 if (!(gfp_mask
& __GFP_FS
))
2456 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags
)))
2459 mark_held_locks(curr
, RECLAIM_FS
);
2462 static void check_flags(unsigned long flags
);
2464 void lockdep_trace_alloc(gfp_t gfp_mask
)
2466 unsigned long flags
;
2468 if (unlikely(current
->lockdep_recursion
))
2471 raw_local_irq_save(flags
);
2473 current
->lockdep_recursion
= 1;
2474 __lockdep_trace_alloc(gfp_mask
, flags
);
2475 current
->lockdep_recursion
= 0;
2476 raw_local_irq_restore(flags
);
2479 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2482 * If non-trylock use in a hardirq or softirq context, then
2483 * mark the lock as used in these contexts:
2485 if (!hlock
->trylock
) {
2487 if (curr
->hardirq_context
)
2488 if (!mark_lock(curr
, hlock
,
2489 LOCK_USED_IN_HARDIRQ_READ
))
2491 if (curr
->softirq_context
)
2492 if (!mark_lock(curr
, hlock
,
2493 LOCK_USED_IN_SOFTIRQ_READ
))
2496 if (curr
->hardirq_context
)
2497 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2499 if (curr
->softirq_context
)
2500 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2504 if (!hlock
->hardirqs_off
) {
2506 if (!mark_lock(curr
, hlock
,
2507 LOCK_ENABLED_HARDIRQ_READ
))
2509 if (curr
->softirqs_enabled
)
2510 if (!mark_lock(curr
, hlock
,
2511 LOCK_ENABLED_SOFTIRQ_READ
))
2514 if (!mark_lock(curr
, hlock
,
2515 LOCK_ENABLED_HARDIRQ
))
2517 if (curr
->softirqs_enabled
)
2518 if (!mark_lock(curr
, hlock
,
2519 LOCK_ENABLED_SOFTIRQ
))
2525 * We reuse the irq context infrastructure more broadly as a general
2526 * context checking code. This tests GFP_FS recursion (a lock taken
2527 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2530 if (!hlock
->trylock
&& (curr
->lockdep_reclaim_gfp
& __GFP_FS
)) {
2532 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS_READ
))
2535 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS
))
2543 static int separate_irq_context(struct task_struct
*curr
,
2544 struct held_lock
*hlock
)
2546 unsigned int depth
= curr
->lockdep_depth
;
2549 * Keep track of points where we cross into an interrupt context:
2551 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2552 curr
->softirq_context
;
2554 struct held_lock
*prev_hlock
;
2556 prev_hlock
= curr
->held_locks
+ depth
-1;
2558 * If we cross into another context, reset the
2559 * hash key (this also prevents the checking and the
2560 * adding of the dependency to 'prev'):
2562 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2571 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2572 enum lock_usage_bit new_bit
)
2578 static inline int mark_irqflags(struct task_struct
*curr
,
2579 struct held_lock
*hlock
)
2584 static inline int separate_irq_context(struct task_struct
*curr
,
2585 struct held_lock
*hlock
)
2590 void lockdep_trace_alloc(gfp_t gfp_mask
)
2597 * Mark a lock with a usage bit, and validate the state transition:
2599 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2600 enum lock_usage_bit new_bit
)
2602 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2605 * If already set then do not dirty the cacheline,
2606 * nor do any checks:
2608 if (likely(hlock_class(this)->usage_mask
& new_mask
))
2614 * Make sure we didnt race:
2616 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
2621 hlock_class(this)->usage_mask
|= new_mask
;
2623 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
2627 #define LOCKDEP_STATE(__STATE) \
2628 case LOCK_USED_IN_##__STATE: \
2629 case LOCK_USED_IN_##__STATE##_READ: \
2630 case LOCK_ENABLED_##__STATE: \
2631 case LOCK_ENABLED_##__STATE##_READ:
2632 #include "lockdep_states.h"
2633 #undef LOCKDEP_STATE
2634 ret
= mark_lock_irq(curr
, this, new_bit
);
2639 debug_atomic_dec(nr_unused_locks
);
2642 if (!debug_locks_off_graph_unlock())
2651 * We must printk outside of the graph_lock:
2654 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2656 print_irqtrace_events(curr
);
2664 * Initialize a lock instance's lock-class mapping info:
2666 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2667 struct lock_class_key
*key
, int subclass
)
2669 lock
->class_cache
= NULL
;
2670 #ifdef CONFIG_LOCK_STAT
2671 lock
->cpu
= raw_smp_processor_id();
2674 if (DEBUG_LOCKS_WARN_ON(!name
)) {
2675 lock
->name
= "NULL";
2681 if (DEBUG_LOCKS_WARN_ON(!key
))
2684 * Sanity check, the lock-class key must be persistent:
2686 if (!static_obj(key
)) {
2687 printk("BUG: key %p not in .data!\n", key
);
2688 DEBUG_LOCKS_WARN_ON(1);
2693 if (unlikely(!debug_locks
))
2697 register_lock_class(lock
, subclass
, 1);
2699 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2702 * This gets called for every mutex_lock*()/spin_lock*() operation.
2703 * We maintain the dependency maps and validate the locking attempt:
2705 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2706 int trylock
, int read
, int check
, int hardirqs_off
,
2707 struct lockdep_map
*nest_lock
, unsigned long ip
,
2710 struct task_struct
*curr
= current
;
2711 struct lock_class
*class = NULL
;
2712 struct held_lock
*hlock
;
2713 unsigned int depth
, id
;
2721 if (unlikely(!debug_locks
))
2724 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2727 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
2729 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2730 printk("turning off the locking correctness validator.\n");
2736 class = lock
->class_cache
;
2738 * Not cached yet or subclass?
2740 if (unlikely(!class)) {
2741 class = register_lock_class(lock
, subclass
, 0);
2745 atomic_inc((atomic_t
*)&class->ops
);
2746 if (very_verbose(class)) {
2747 printk("\nacquire class [%p] %s", class->key
, class->name
);
2748 if (class->name_version
> 1)
2749 printk("#%d", class->name_version
);
2755 * Add the lock to the list of currently held locks.
2756 * (we dont increase the depth just yet, up until the
2757 * dependency checks are done)
2759 depth
= curr
->lockdep_depth
;
2760 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2763 class_idx
= class - lock_classes
+ 1;
2766 hlock
= curr
->held_locks
+ depth
- 1;
2767 if (hlock
->class_idx
== class_idx
&& nest_lock
) {
2768 if (hlock
->references
)
2769 hlock
->references
++;
2771 hlock
->references
= 2;
2777 hlock
= curr
->held_locks
+ depth
;
2778 if (DEBUG_LOCKS_WARN_ON(!class))
2780 hlock
->class_idx
= class_idx
;
2781 hlock
->acquire_ip
= ip
;
2782 hlock
->instance
= lock
;
2783 hlock
->nest_lock
= nest_lock
;
2784 hlock
->trylock
= trylock
;
2786 hlock
->check
= check
;
2787 hlock
->hardirqs_off
= !!hardirqs_off
;
2788 hlock
->references
= references
;
2789 #ifdef CONFIG_LOCK_STAT
2790 hlock
->waittime_stamp
= 0;
2791 hlock
->holdtime_stamp
= lockstat_clock();
2794 if (check
== 2 && !mark_irqflags(curr
, hlock
))
2797 /* mark it as used: */
2798 if (!mark_lock(curr
, hlock
, LOCK_USED
))
2802 * Calculate the chain hash: it's the combined hash of all the
2803 * lock keys along the dependency chain. We save the hash value
2804 * at every step so that we can get the current hash easily
2805 * after unlock. The chain hash is then used to cache dependency
2808 * The 'key ID' is what is the most compact key value to drive
2809 * the hash, not class->key.
2811 id
= class - lock_classes
;
2812 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2815 chain_key
= curr
->curr_chain_key
;
2817 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2822 hlock
->prev_chain_key
= chain_key
;
2823 if (separate_irq_context(curr
, hlock
)) {
2827 chain_key
= iterate_chain_key(chain_key
, id
);
2829 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
2832 curr
->curr_chain_key
= chain_key
;
2833 curr
->lockdep_depth
++;
2834 check_chain_key(curr
);
2835 #ifdef CONFIG_DEBUG_LOCKDEP
2836 if (unlikely(!debug_locks
))
2839 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2841 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2842 printk("turning off the locking correctness validator.\n");
2847 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2848 max_lockdep_depth
= curr
->lockdep_depth
;
2854 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2857 if (!debug_locks_off())
2859 if (debug_locks_silent
)
2862 printk("\n=====================================\n");
2863 printk( "[ BUG: bad unlock balance detected! ]\n");
2864 printk( "-------------------------------------\n");
2865 printk("%s/%d is trying to release lock (",
2866 curr
->comm
, task_pid_nr(curr
));
2867 print_lockdep_cache(lock
);
2870 printk("but there are no more locks to release!\n");
2871 printk("\nother info that might help us debug this:\n");
2872 lockdep_print_held_locks(curr
);
2874 printk("\nstack backtrace:\n");
2881 * Common debugging checks for both nested and non-nested unlock:
2883 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2886 if (unlikely(!debug_locks
))
2888 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2891 if (curr
->lockdep_depth
<= 0)
2892 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2897 static int match_held_lock(struct held_lock
*hlock
, struct lockdep_map
*lock
)
2899 if (hlock
->instance
== lock
)
2902 if (hlock
->references
) {
2903 struct lock_class
*class = lock
->class_cache
;
2906 class = look_up_lock_class(lock
, 0);
2908 if (DEBUG_LOCKS_WARN_ON(!class))
2911 if (DEBUG_LOCKS_WARN_ON(!hlock
->nest_lock
))
2914 if (hlock
->class_idx
== class - lock_classes
+ 1)
2922 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
2923 struct lock_class_key
*key
, unsigned int subclass
,
2926 struct task_struct
*curr
= current
;
2927 struct held_lock
*hlock
, *prev_hlock
;
2928 struct lock_class
*class;
2932 depth
= curr
->lockdep_depth
;
2933 if (DEBUG_LOCKS_WARN_ON(!depth
))
2937 for (i
= depth
-1; i
>= 0; i
--) {
2938 hlock
= curr
->held_locks
+ i
;
2940 * We must not cross into another context:
2942 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2944 if (match_held_lock(hlock
, lock
))
2948 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2951 lockdep_init_map(lock
, name
, key
, 0);
2952 class = register_lock_class(lock
, subclass
, 0);
2953 hlock
->class_idx
= class - lock_classes
+ 1;
2955 curr
->lockdep_depth
= i
;
2956 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2958 for (; i
< depth
; i
++) {
2959 hlock
= curr
->held_locks
+ i
;
2960 if (!__lock_acquire(hlock
->instance
,
2961 hlock_class(hlock
)->subclass
, hlock
->trylock
,
2962 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2963 hlock
->nest_lock
, hlock
->acquire_ip
,
2968 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
2974 * Remove the lock to the list of currently held locks in a
2975 * potentially non-nested (out of order) manner. This is a
2976 * relatively rare operation, as all the unlock APIs default
2977 * to nested mode (which uses lock_release()):
2980 lock_release_non_nested(struct task_struct
*curr
,
2981 struct lockdep_map
*lock
, unsigned long ip
)
2983 struct held_lock
*hlock
, *prev_hlock
;
2988 * Check whether the lock exists in the current stack
2991 depth
= curr
->lockdep_depth
;
2992 if (DEBUG_LOCKS_WARN_ON(!depth
))
2996 for (i
= depth
-1; i
>= 0; i
--) {
2997 hlock
= curr
->held_locks
+ i
;
2999 * We must not cross into another context:
3001 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3003 if (match_held_lock(hlock
, lock
))
3007 return print_unlock_inbalance_bug(curr
, lock
, ip
);
3010 if (hlock
->instance
== lock
)
3011 lock_release_holdtime(hlock
);
3013 if (hlock
->references
) {
3014 hlock
->references
--;
3015 if (hlock
->references
) {
3017 * We had, and after removing one, still have
3018 * references, the current lock stack is still
3019 * valid. We're done!
3026 * We have the right lock to unlock, 'hlock' points to it.
3027 * Now we remove it from the stack, and add back the other
3028 * entries (if any), recalculating the hash along the way:
3031 curr
->lockdep_depth
= i
;
3032 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3034 for (i
++; i
< depth
; i
++) {
3035 hlock
= curr
->held_locks
+ i
;
3036 if (!__lock_acquire(hlock
->instance
,
3037 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3038 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3039 hlock
->nest_lock
, hlock
->acquire_ip
,
3044 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
3050 * Remove the lock to the list of currently held locks - this gets
3051 * called on mutex_unlock()/spin_unlock*() (or on a failed
3052 * mutex_lock_interruptible()). This is done for unlocks that nest
3053 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3055 static int lock_release_nested(struct task_struct
*curr
,
3056 struct lockdep_map
*lock
, unsigned long ip
)
3058 struct held_lock
*hlock
;
3062 * Pop off the top of the lock stack:
3064 depth
= curr
->lockdep_depth
- 1;
3065 hlock
= curr
->held_locks
+ depth
;
3068 * Is the unlock non-nested:
3070 if (hlock
->instance
!= lock
|| hlock
->references
)
3071 return lock_release_non_nested(curr
, lock
, ip
);
3072 curr
->lockdep_depth
--;
3074 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
3077 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3079 lock_release_holdtime(hlock
);
3081 #ifdef CONFIG_DEBUG_LOCKDEP
3082 hlock
->prev_chain_key
= 0;
3083 hlock
->class_idx
= 0;
3084 hlock
->acquire_ip
= 0;
3085 hlock
->irq_context
= 0;
3091 * Remove the lock to the list of currently held locks - this gets
3092 * called on mutex_unlock()/spin_unlock*() (or on a failed
3093 * mutex_lock_interruptible()). This is done for unlocks that nest
3094 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3097 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
3099 struct task_struct
*curr
= current
;
3101 if (!check_unlock(curr
, lock
, ip
))
3105 if (!lock_release_nested(curr
, lock
, ip
))
3108 if (!lock_release_non_nested(curr
, lock
, ip
))
3112 check_chain_key(curr
);
3115 static int __lock_is_held(struct lockdep_map
*lock
)
3117 struct task_struct
*curr
= current
;
3120 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3121 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3123 if (match_held_lock(hlock
, lock
))
3131 * Check whether we follow the irq-flags state precisely:
3133 static void check_flags(unsigned long flags
)
3135 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3136 defined(CONFIG_TRACE_IRQFLAGS)
3140 if (irqs_disabled_flags(flags
)) {
3141 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
3142 printk("possible reason: unannotated irqs-off.\n");
3145 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
3146 printk("possible reason: unannotated irqs-on.\n");
3151 * We dont accurately track softirq state in e.g.
3152 * hardirq contexts (such as on 4KSTACKS), so only
3153 * check if not in hardirq contexts:
3155 if (!hardirq_count()) {
3156 if (softirq_count())
3157 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
3159 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
3163 print_irqtrace_events(current
);
3167 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
3168 struct lock_class_key
*key
, unsigned int subclass
,
3171 unsigned long flags
;
3173 if (unlikely(current
->lockdep_recursion
))
3176 raw_local_irq_save(flags
);
3177 current
->lockdep_recursion
= 1;
3179 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
3180 check_chain_key(current
);
3181 current
->lockdep_recursion
= 0;
3182 raw_local_irq_restore(flags
);
3184 EXPORT_SYMBOL_GPL(lock_set_class
);
3187 * We are not always called with irqs disabled - do that here,
3188 * and also avoid lockdep recursion:
3190 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3191 int trylock
, int read
, int check
,
3192 struct lockdep_map
*nest_lock
, unsigned long ip
)
3194 unsigned long flags
;
3196 if (unlikely(current
->lockdep_recursion
))
3199 raw_local_irq_save(flags
);
3202 current
->lockdep_recursion
= 1;
3203 trace_lock_acquire(lock
, subclass
, trylock
, read
, check
, nest_lock
, ip
);
3204 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
3205 irqs_disabled_flags(flags
), nest_lock
, ip
, 0);
3206 current
->lockdep_recursion
= 0;
3207 raw_local_irq_restore(flags
);
3209 EXPORT_SYMBOL_GPL(lock_acquire
);
3211 void lock_release(struct lockdep_map
*lock
, int nested
,
3214 unsigned long flags
;
3216 if (unlikely(current
->lockdep_recursion
))
3219 raw_local_irq_save(flags
);
3221 current
->lockdep_recursion
= 1;
3222 trace_lock_release(lock
, nested
, ip
);
3223 __lock_release(lock
, nested
, ip
);
3224 current
->lockdep_recursion
= 0;
3225 raw_local_irq_restore(flags
);
3227 EXPORT_SYMBOL_GPL(lock_release
);
3229 int lock_is_held(struct lockdep_map
*lock
)
3231 unsigned long flags
;
3234 if (unlikely(current
->lockdep_recursion
))
3237 raw_local_irq_save(flags
);
3240 current
->lockdep_recursion
= 1;
3241 ret
= __lock_is_held(lock
);
3242 current
->lockdep_recursion
= 0;
3243 raw_local_irq_restore(flags
);
3247 EXPORT_SYMBOL_GPL(lock_is_held
);
3249 void lockdep_set_current_reclaim_state(gfp_t gfp_mask
)
3251 current
->lockdep_reclaim_gfp
= gfp_mask
;
3254 void lockdep_clear_current_reclaim_state(void)
3256 current
->lockdep_reclaim_gfp
= 0;
3259 #ifdef CONFIG_LOCK_STAT
3261 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3264 if (!debug_locks_off())
3266 if (debug_locks_silent
)
3269 printk("\n=================================\n");
3270 printk( "[ BUG: bad contention detected! ]\n");
3271 printk( "---------------------------------\n");
3272 printk("%s/%d is trying to contend lock (",
3273 curr
->comm
, task_pid_nr(curr
));
3274 print_lockdep_cache(lock
);
3277 printk("but there are no locks held!\n");
3278 printk("\nother info that might help us debug this:\n");
3279 lockdep_print_held_locks(curr
);
3281 printk("\nstack backtrace:\n");
3288 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3290 struct task_struct
*curr
= current
;
3291 struct held_lock
*hlock
, *prev_hlock
;
3292 struct lock_class_stats
*stats
;
3294 int i
, contention_point
, contending_point
;
3296 depth
= curr
->lockdep_depth
;
3297 if (DEBUG_LOCKS_WARN_ON(!depth
))
3301 for (i
= depth
-1; i
>= 0; i
--) {
3302 hlock
= curr
->held_locks
+ i
;
3304 * We must not cross into another context:
3306 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3308 if (match_held_lock(hlock
, lock
))
3312 print_lock_contention_bug(curr
, lock
, ip
);
3316 if (hlock
->instance
!= lock
)
3319 hlock
->waittime_stamp
= lockstat_clock();
3321 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3322 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3325 stats
= get_lock_stats(hlock_class(hlock
));
3326 if (contention_point
< LOCKSTAT_POINTS
)
3327 stats
->contention_point
[contention_point
]++;
3328 if (contending_point
< LOCKSTAT_POINTS
)
3329 stats
->contending_point
[contending_point
]++;
3330 if (lock
->cpu
!= smp_processor_id())
3331 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3332 put_lock_stats(stats
);
3336 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3338 struct task_struct
*curr
= current
;
3339 struct held_lock
*hlock
, *prev_hlock
;
3340 struct lock_class_stats
*stats
;
3342 u64 now
, waittime
= 0;
3345 depth
= curr
->lockdep_depth
;
3346 if (DEBUG_LOCKS_WARN_ON(!depth
))
3350 for (i
= depth
-1; i
>= 0; i
--) {
3351 hlock
= curr
->held_locks
+ i
;
3353 * We must not cross into another context:
3355 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3357 if (match_held_lock(hlock
, lock
))
3361 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3365 if (hlock
->instance
!= lock
)
3368 cpu
= smp_processor_id();
3369 if (hlock
->waittime_stamp
) {
3370 now
= lockstat_clock();
3371 waittime
= now
- hlock
->waittime_stamp
;
3372 hlock
->holdtime_stamp
= now
;
3375 trace_lock_acquired(lock
, ip
, waittime
);
3377 stats
= get_lock_stats(hlock_class(hlock
));
3380 lock_time_inc(&stats
->read_waittime
, waittime
);
3382 lock_time_inc(&stats
->write_waittime
, waittime
);
3384 if (lock
->cpu
!= cpu
)
3385 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3386 put_lock_stats(stats
);
3392 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3394 unsigned long flags
;
3396 if (unlikely(!lock_stat
))
3399 if (unlikely(current
->lockdep_recursion
))
3402 raw_local_irq_save(flags
);
3404 current
->lockdep_recursion
= 1;
3405 trace_lock_contended(lock
, ip
);
3406 __lock_contended(lock
, ip
);
3407 current
->lockdep_recursion
= 0;
3408 raw_local_irq_restore(flags
);
3410 EXPORT_SYMBOL_GPL(lock_contended
);
3412 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3414 unsigned long flags
;
3416 if (unlikely(!lock_stat
))
3419 if (unlikely(current
->lockdep_recursion
))
3422 raw_local_irq_save(flags
);
3424 current
->lockdep_recursion
= 1;
3425 __lock_acquired(lock
, ip
);
3426 current
->lockdep_recursion
= 0;
3427 raw_local_irq_restore(flags
);
3429 EXPORT_SYMBOL_GPL(lock_acquired
);
3433 * Used by the testsuite, sanitize the validator state
3434 * after a simulated failure:
3437 void lockdep_reset(void)
3439 unsigned long flags
;
3442 raw_local_irq_save(flags
);
3443 current
->curr_chain_key
= 0;
3444 current
->lockdep_depth
= 0;
3445 current
->lockdep_recursion
= 0;
3446 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3447 nr_hardirq_chains
= 0;
3448 nr_softirq_chains
= 0;
3449 nr_process_chains
= 0;
3451 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3452 INIT_LIST_HEAD(chainhash_table
+ i
);
3453 raw_local_irq_restore(flags
);
3456 static void zap_class(struct lock_class
*class)
3461 * Remove all dependencies this lock is
3464 for (i
= 0; i
< nr_list_entries
; i
++) {
3465 if (list_entries
[i
].class == class)
3466 list_del_rcu(&list_entries
[i
].entry
);
3469 * Unhash the class and remove it from the all_lock_classes list:
3471 list_del_rcu(&class->hash_entry
);
3472 list_del_rcu(&class->lock_entry
);
3477 static inline int within(const void *addr
, void *start
, unsigned long size
)
3479 return addr
>= start
&& addr
< start
+ size
;
3482 void lockdep_free_key_range(void *start
, unsigned long size
)
3484 struct lock_class
*class, *next
;
3485 struct list_head
*head
;
3486 unsigned long flags
;
3490 raw_local_irq_save(flags
);
3491 locked
= graph_lock();
3494 * Unhash all classes that were created by this module:
3496 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3497 head
= classhash_table
+ i
;
3498 if (list_empty(head
))
3500 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3501 if (within(class->key
, start
, size
))
3503 else if (within(class->name
, start
, size
))
3510 raw_local_irq_restore(flags
);
3513 void lockdep_reset_lock(struct lockdep_map
*lock
)
3515 struct lock_class
*class, *next
;
3516 struct list_head
*head
;
3517 unsigned long flags
;
3521 raw_local_irq_save(flags
);
3524 * Remove all classes this lock might have:
3526 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3528 * If the class exists we look it up and zap it:
3530 class = look_up_lock_class(lock
, j
);
3535 * Debug check: in the end all mapped classes should
3538 locked
= graph_lock();
3539 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3540 head
= classhash_table
+ i
;
3541 if (list_empty(head
))
3543 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3544 if (unlikely(class == lock
->class_cache
)) {
3545 if (debug_locks_off_graph_unlock())
3555 raw_local_irq_restore(flags
);
3558 void lockdep_init(void)
3563 * Some architectures have their own start_kernel()
3564 * code which calls lockdep_init(), while we also
3565 * call lockdep_init() from the start_kernel() itself,
3566 * and we want to initialize the hashes only once:
3568 if (lockdep_initialized
)
3571 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3572 INIT_LIST_HEAD(classhash_table
+ i
);
3574 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3575 INIT_LIST_HEAD(chainhash_table
+ i
);
3577 lockdep_initialized
= 1;
3580 void __init
lockdep_info(void)
3582 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3584 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
3585 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
3586 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
3587 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
3588 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
3589 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
3590 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
3592 printk(" memory used by lock dependency info: %lu kB\n",
3593 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
3594 sizeof(struct list_head
) * CLASSHASH_SIZE
+
3595 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
3596 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
3597 sizeof(struct list_head
) * CHAINHASH_SIZE
3598 #ifdef CONFIG_PROVE_LOCKING
3599 + sizeof(struct circular_queue
)
3604 printk(" per task-struct memory footprint: %lu bytes\n",
3605 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
3607 #ifdef CONFIG_DEBUG_LOCKDEP
3608 if (lockdep_init_error
) {
3609 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3610 printk("Call stack leading to lockdep invocation was:\n");
3611 print_stack_trace(&lockdep_init_trace
, 0);
3617 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
3618 const void *mem_to
, struct held_lock
*hlock
)
3620 if (!debug_locks_off())
3622 if (debug_locks_silent
)
3625 printk("\n=========================\n");
3626 printk( "[ BUG: held lock freed! ]\n");
3627 printk( "-------------------------\n");
3628 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3629 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
3631 lockdep_print_held_locks(curr
);
3633 printk("\nstack backtrace:\n");
3637 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
3638 const void* lock_from
, unsigned long lock_len
)
3640 return lock_from
+ lock_len
<= mem_from
||
3641 mem_from
+ mem_len
<= lock_from
;
3645 * Called when kernel memory is freed (or unmapped), or if a lock
3646 * is destroyed or reinitialized - this code checks whether there is
3647 * any held lock in the memory range of <from> to <to>:
3649 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
3651 struct task_struct
*curr
= current
;
3652 struct held_lock
*hlock
;
3653 unsigned long flags
;
3656 if (unlikely(!debug_locks
))
3659 local_irq_save(flags
);
3660 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3661 hlock
= curr
->held_locks
+ i
;
3663 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
3664 sizeof(*hlock
->instance
)))
3667 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
3670 local_irq_restore(flags
);
3672 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
3674 static void print_held_locks_bug(struct task_struct
*curr
)
3676 if (!debug_locks_off())
3678 if (debug_locks_silent
)
3681 printk("\n=====================================\n");
3682 printk( "[ BUG: lock held at task exit time! ]\n");
3683 printk( "-------------------------------------\n");
3684 printk("%s/%d is exiting with locks still held!\n",
3685 curr
->comm
, task_pid_nr(curr
));
3686 lockdep_print_held_locks(curr
);
3688 printk("\nstack backtrace:\n");
3692 void debug_check_no_locks_held(struct task_struct
*task
)
3694 if (unlikely(task
->lockdep_depth
> 0))
3695 print_held_locks_bug(task
);
3698 void debug_show_all_locks(void)
3700 struct task_struct
*g
, *p
;
3704 if (unlikely(!debug_locks
)) {
3705 printk("INFO: lockdep is turned off.\n");
3708 printk("\nShowing all locks held in the system:\n");
3711 * Here we try to get the tasklist_lock as hard as possible,
3712 * if not successful after 2 seconds we ignore it (but keep
3713 * trying). This is to enable a debug printout even if a
3714 * tasklist_lock-holding task deadlocks or crashes.
3717 if (!read_trylock(&tasklist_lock
)) {
3719 printk("hm, tasklist_lock locked, retrying... ");
3722 printk(" #%d", 10-count
);
3726 printk(" ignoring it.\n");
3730 printk(KERN_CONT
" locked it.\n");
3733 do_each_thread(g
, p
) {
3735 * It's not reliable to print a task's held locks
3736 * if it's not sleeping (or if it's not the current
3739 if (p
->state
== TASK_RUNNING
&& p
!= current
)
3741 if (p
->lockdep_depth
)
3742 lockdep_print_held_locks(p
);
3744 if (read_trylock(&tasklist_lock
))
3746 } while_each_thread(g
, p
);
3749 printk("=============================================\n\n");
3752 read_unlock(&tasklist_lock
);
3754 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
3757 * Careful: only use this function if you are sure that
3758 * the task cannot run in parallel!
3760 void __debug_show_held_locks(struct task_struct
*task
)
3762 if (unlikely(!debug_locks
)) {
3763 printk("INFO: lockdep is turned off.\n");
3766 lockdep_print_held_locks(task
);
3768 EXPORT_SYMBOL_GPL(__debug_show_held_locks
);
3770 void debug_show_held_locks(struct task_struct
*task
)
3772 __debug_show_held_locks(task
);
3774 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
3776 void lockdep_sys_exit(void)
3778 struct task_struct
*curr
= current
;
3780 if (unlikely(curr
->lockdep_depth
)) {
3781 if (!debug_locks_off())
3783 printk("\n================================================\n");
3784 printk( "[ BUG: lock held when returning to user space! ]\n");
3785 printk( "------------------------------------------------\n");
3786 printk("%s/%d is leaving the kernel with locks still held!\n",
3787 curr
->comm
, curr
->pid
);
3788 lockdep_print_held_locks(curr
);
3792 void lockdep_rcu_dereference(const char *file
, const int line
)
3794 struct task_struct
*curr
= current
;
3796 if (!debug_locks_off())
3798 printk("\n===================================================\n");
3799 printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3800 printk( "---------------------------------------------------\n");
3801 printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3803 printk("\nother info that might help us debug this:\n\n");
3804 printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active
, debug_locks
);
3805 lockdep_print_held_locks(curr
);
3806 printk("\nstack backtrace:\n");
3809 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference
);