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
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/sched/clock.h>
32 #include <linux/sched/task.h>
33 #include <linux/sched/mm.h>
34 #include <linux/delay.h>
35 #include <linux/module.h>
36 #include <linux/proc_fs.h>
37 #include <linux/seq_file.h>
38 #include <linux/spinlock.h>
39 #include <linux/kallsyms.h>
40 #include <linux/interrupt.h>
41 #include <linux/stacktrace.h>
42 #include <linux/debug_locks.h>
43 #include <linux/irqflags.h>
44 #include <linux/utsname.h>
45 #include <linux/hash.h>
46 #include <linux/ftrace.h>
47 #include <linux/stringify.h>
48 #include <linux/bitops.h>
49 #include <linux/gfp.h>
50 #include <linux/random.h>
51 #include <linux/jhash.h>
52 #include <linux/nmi.h>
54 #include <asm/sections.h>
56 #include "lockdep_internals.h"
58 #define CREATE_TRACE_POINTS
59 #include <trace/events/lock.h>
61 #ifdef CONFIG_PROVE_LOCKING
62 int prove_locking
= 1;
63 module_param(prove_locking
, int, 0644);
65 #define prove_locking 0
68 #ifdef CONFIG_LOCK_STAT
70 module_param(lock_stat
, int, 0644);
76 * lockdep_lock: protects the lockdep graph, the hashes and the
77 * class/list/hash allocators.
79 * This is one of the rare exceptions where it's justified
80 * to use a raw spinlock - we really dont want the spinlock
81 * code to recurse back into the lockdep code...
83 static arch_spinlock_t lockdep_lock
= (arch_spinlock_t
)__ARCH_SPIN_LOCK_UNLOCKED
;
85 static int graph_lock(void)
87 arch_spin_lock(&lockdep_lock
);
89 * Make sure that if another CPU detected a bug while
90 * walking the graph we dont change it (while the other
91 * CPU is busy printing out stuff with the graph lock
95 arch_spin_unlock(&lockdep_lock
);
98 /* prevent any recursions within lockdep from causing deadlocks */
99 current
->lockdep_recursion
++;
103 static inline int graph_unlock(void)
105 if (debug_locks
&& !arch_spin_is_locked(&lockdep_lock
)) {
107 * The lockdep graph lock isn't locked while we expect it to
108 * be, we're confused now, bye!
110 return DEBUG_LOCKS_WARN_ON(1);
113 current
->lockdep_recursion
--;
114 arch_spin_unlock(&lockdep_lock
);
119 * Turn lock debugging off and return with 0 if it was off already,
120 * and also release the graph lock:
122 static inline int debug_locks_off_graph_unlock(void)
124 int ret
= debug_locks_off();
126 arch_spin_unlock(&lockdep_lock
);
131 unsigned long nr_list_entries
;
132 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
135 * All data structures here are protected by the global debug_lock.
137 * Mutex key structs only get allocated, once during bootup, and never
138 * get freed - this significantly simplifies the debugging code.
140 unsigned long nr_lock_classes
;
141 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
143 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
145 if (!hlock
->class_idx
) {
147 * Someone passed in garbage, we give up.
149 DEBUG_LOCKS_WARN_ON(1);
152 return lock_classes
+ hlock
->class_idx
- 1;
155 #ifdef CONFIG_LOCK_STAT
156 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
], cpu_lock_stats
);
158 static inline u64
lockstat_clock(void)
160 return local_clock();
163 static int lock_point(unsigned long points
[], unsigned long ip
)
167 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
168 if (points
[i
] == 0) {
179 static void lock_time_inc(struct lock_time
*lt
, u64 time
)
184 if (time
< lt
->min
|| !lt
->nr
)
191 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
196 if (src
->max
> dst
->max
)
199 if (src
->min
< dst
->min
|| !dst
->nr
)
202 dst
->total
+= src
->total
;
206 struct lock_class_stats
lock_stats(struct lock_class
*class)
208 struct lock_class_stats stats
;
211 memset(&stats
, 0, sizeof(struct lock_class_stats
));
212 for_each_possible_cpu(cpu
) {
213 struct lock_class_stats
*pcs
=
214 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
216 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
217 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
219 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
220 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
222 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
223 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
225 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
226 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
228 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
229 stats
.bounces
[i
] += pcs
->bounces
[i
];
235 void clear_lock_stats(struct lock_class
*class)
239 for_each_possible_cpu(cpu
) {
240 struct lock_class_stats
*cpu_stats
=
241 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
243 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
245 memset(class->contention_point
, 0, sizeof(class->contention_point
));
246 memset(class->contending_point
, 0, sizeof(class->contending_point
));
249 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
251 return &get_cpu_var(cpu_lock_stats
)[class - lock_classes
];
254 static void put_lock_stats(struct lock_class_stats
*stats
)
256 put_cpu_var(cpu_lock_stats
);
259 static void lock_release_holdtime(struct held_lock
*hlock
)
261 struct lock_class_stats
*stats
;
267 holdtime
= lockstat_clock() - hlock
->holdtime_stamp
;
269 stats
= get_lock_stats(hlock_class(hlock
));
271 lock_time_inc(&stats
->read_holdtime
, holdtime
);
273 lock_time_inc(&stats
->write_holdtime
, holdtime
);
274 put_lock_stats(stats
);
277 static inline void lock_release_holdtime(struct held_lock
*hlock
)
283 * We keep a global list of all lock classes. The list only grows,
284 * never shrinks. The list is only accessed with the lockdep
285 * spinlock lock held.
287 LIST_HEAD(all_lock_classes
);
290 * The lockdep classes are in a hash-table as well, for fast lookup:
292 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
293 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
294 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
295 #define classhashentry(key) (classhash_table + __classhashfn((key)))
297 static struct hlist_head classhash_table
[CLASSHASH_SIZE
];
300 * We put the lock dependency chains into a hash-table as well, to cache
303 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
304 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
305 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
306 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
308 static struct hlist_head chainhash_table
[CHAINHASH_SIZE
];
311 * The hash key of the lock dependency chains is a hash itself too:
312 * it's a hash of all locks taken up to that lock, including that lock.
313 * It's a 64-bit hash, because it's important for the keys to be
316 static inline u64
iterate_chain_key(u64 key
, u32 idx
)
318 u32 k0
= key
, k1
= key
>> 32;
320 __jhash_mix(idx
, k0
, k1
); /* Macro that modifies arguments! */
322 return k0
| (u64
)k1
<< 32;
325 void lockdep_off(void)
327 current
->lockdep_recursion
++;
329 EXPORT_SYMBOL(lockdep_off
);
331 void lockdep_on(void)
333 current
->lockdep_recursion
--;
335 EXPORT_SYMBOL(lockdep_on
);
338 * Debugging switches:
342 #define VERY_VERBOSE 0
345 # define HARDIRQ_VERBOSE 1
346 # define SOFTIRQ_VERBOSE 1
348 # define HARDIRQ_VERBOSE 0
349 # define SOFTIRQ_VERBOSE 0
352 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
354 * Quick filtering for interesting events:
356 static int class_filter(struct lock_class
*class)
360 if (class->name_version
== 1 &&
361 !strcmp(class->name
, "lockname"))
363 if (class->name_version
== 1 &&
364 !strcmp(class->name
, "&struct->lockfield"))
367 /* Filter everything else. 1 would be to allow everything else */
372 static int verbose(struct lock_class
*class)
375 return class_filter(class);
381 * Stack-trace: tightly packed array of stack backtrace
382 * addresses. Protected by the graph_lock.
384 unsigned long nr_stack_trace_entries
;
385 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
387 static void print_lockdep_off(const char *bug_msg
)
389 printk(KERN_DEBUG
"%s\n", bug_msg
);
390 printk(KERN_DEBUG
"turning off the locking correctness validator.\n");
391 #ifdef CONFIG_LOCK_STAT
392 printk(KERN_DEBUG
"Please attach the output of /proc/lock_stat to the bug report\n");
396 static int save_trace(struct stack_trace
*trace
)
398 trace
->nr_entries
= 0;
399 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
400 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
404 save_stack_trace(trace
);
407 * Some daft arches put -1 at the end to indicate its a full trace.
409 * <rant> this is buggy anyway, since it takes a whole extra entry so a
410 * complete trace that maxes out the entries provided will be reported
411 * as incomplete, friggin useless </rant>
413 if (trace
->nr_entries
!= 0 &&
414 trace
->entries
[trace
->nr_entries
-1] == ULONG_MAX
)
417 trace
->max_entries
= trace
->nr_entries
;
419 nr_stack_trace_entries
+= trace
->nr_entries
;
421 if (nr_stack_trace_entries
>= MAX_STACK_TRACE_ENTRIES
-1) {
422 if (!debug_locks_off_graph_unlock())
425 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
434 unsigned int nr_hardirq_chains
;
435 unsigned int nr_softirq_chains
;
436 unsigned int nr_process_chains
;
437 unsigned int max_lockdep_depth
;
439 #ifdef CONFIG_DEBUG_LOCKDEP
441 * Various lockdep statistics:
443 DEFINE_PER_CPU(struct lockdep_stats
, lockdep_stats
);
450 #define __USAGE(__STATE) \
451 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
452 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
453 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
454 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
456 static const char *usage_str
[] =
458 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
459 #include "lockdep_states.h"
461 [LOCK_USED
] = "INITIAL USE",
464 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
466 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
469 static inline unsigned long lock_flag(enum lock_usage_bit bit
)
474 static char get_usage_char(struct lock_class
*class, enum lock_usage_bit bit
)
478 if (class->usage_mask
& lock_flag(bit
+ 2))
480 if (class->usage_mask
& lock_flag(bit
)) {
482 if (class->usage_mask
& lock_flag(bit
+ 2))
489 void get_usage_chars(struct lock_class
*class, char usage
[LOCK_USAGE_CHARS
])
493 #define LOCKDEP_STATE(__STATE) \
494 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
495 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
496 #include "lockdep_states.h"
502 static void __print_lock_name(struct lock_class
*class)
504 char str
[KSYM_NAME_LEN
];
509 name
= __get_key_name(class->key
, str
);
510 printk(KERN_CONT
"%s", name
);
512 printk(KERN_CONT
"%s", name
);
513 if (class->name_version
> 1)
514 printk(KERN_CONT
"#%d", class->name_version
);
516 printk(KERN_CONT
"/%d", class->subclass
);
520 static void print_lock_name(struct lock_class
*class)
522 char usage
[LOCK_USAGE_CHARS
];
524 get_usage_chars(class, usage
);
526 printk(KERN_CONT
" (");
527 __print_lock_name(class);
528 printk(KERN_CONT
"){%s}", usage
);
531 static void print_lockdep_cache(struct lockdep_map
*lock
)
534 char str
[KSYM_NAME_LEN
];
538 name
= __get_key_name(lock
->key
->subkeys
, str
);
540 printk(KERN_CONT
"%s", name
);
543 static void print_lock(struct held_lock
*hlock
)
546 * We can be called locklessly through debug_show_all_locks() so be
547 * extra careful, the hlock might have been released and cleared.
549 unsigned int class_idx
= hlock
->class_idx
;
551 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
554 if (!class_idx
|| (class_idx
- 1) >= MAX_LOCKDEP_KEYS
) {
555 printk(KERN_CONT
"<RELEASED>\n");
559 print_lock_name(lock_classes
+ class_idx
- 1);
560 printk(KERN_CONT
", at: [<%p>] %pS\n",
561 (void *)hlock
->acquire_ip
, (void *)hlock
->acquire_ip
);
564 static void lockdep_print_held_locks(struct task_struct
*curr
)
566 int i
, depth
= curr
->lockdep_depth
;
569 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
572 printk("%d lock%s held by %s/%d:\n",
573 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
575 for (i
= 0; i
< depth
; i
++) {
577 print_lock(curr
->held_locks
+ i
);
581 static void print_kernel_ident(void)
583 printk("%s %.*s %s\n", init_utsname()->release
,
584 (int)strcspn(init_utsname()->version
, " "),
585 init_utsname()->version
,
589 static int very_verbose(struct lock_class
*class)
592 return class_filter(class);
598 * Is this the address of a static object:
601 static int static_obj(void *obj
)
603 unsigned long start
= (unsigned long) &_stext
,
604 end
= (unsigned long) &_end
,
605 addr
= (unsigned long) obj
;
610 if ((addr
>= start
) && (addr
< end
))
613 if (arch_is_kernel_data(addr
))
617 * in-kernel percpu var?
619 if (is_kernel_percpu_address(addr
))
623 * module static or percpu var?
625 return is_module_address(addr
) || is_module_percpu_address(addr
);
630 * To make lock name printouts unique, we calculate a unique
631 * class->name_version generation counter:
633 static int count_matching_names(struct lock_class
*new_class
)
635 struct lock_class
*class;
638 if (!new_class
->name
)
641 list_for_each_entry_rcu(class, &all_lock_classes
, lock_entry
) {
642 if (new_class
->key
- new_class
->subclass
== class->key
)
643 return class->name_version
;
644 if (class->name
&& !strcmp(class->name
, new_class
->name
))
645 count
= max(count
, class->name_version
);
652 * Register a lock's class in the hash-table, if the class is not present
653 * yet. Otherwise we look it up. We cache the result in the lock object
654 * itself, so actual lookup of the hash should be once per lock object.
656 static inline struct lock_class
*
657 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
659 struct lockdep_subclass_key
*key
;
660 struct hlist_head
*hash_head
;
661 struct lock_class
*class;
662 bool is_static
= false;
664 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
667 "BUG: looking up invalid subclass: %u\n", subclass
);
669 "turning off the locking correctness validator.\n");
675 * Static locks do not have their class-keys yet - for them the key
676 * is the lock object itself. If the lock is in the per cpu area,
677 * the canonical address of the lock (per cpu offset removed) is
680 if (unlikely(!lock
->key
)) {
681 unsigned long can_addr
, addr
= (unsigned long)lock
;
683 if (__is_kernel_percpu_address(addr
, &can_addr
))
684 lock
->key
= (void *)can_addr
;
685 else if (__is_module_percpu_address(addr
, &can_addr
))
686 lock
->key
= (void *)can_addr
;
687 else if (static_obj(lock
))
688 lock
->key
= (void *)lock
;
690 return ERR_PTR(-EINVAL
);
695 * NOTE: the class-key must be unique. For dynamic locks, a static
696 * lock_class_key variable is passed in through the mutex_init()
697 * (or spin_lock_init()) call - which acts as the key. For static
698 * locks we use the lock object itself as the key.
700 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
701 sizeof(struct lockdep_map
));
703 key
= lock
->key
->subkeys
+ subclass
;
705 hash_head
= classhashentry(key
);
708 * We do an RCU walk of the hash, see lockdep_free_key_range().
710 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
713 hlist_for_each_entry_rcu(class, hash_head
, hash_entry
) {
714 if (class->key
== key
) {
716 * Huh! same key, different name? Did someone trample
717 * on some memory? We're most confused.
719 WARN_ON_ONCE(class->name
!= lock
->name
);
724 return is_static
|| static_obj(lock
->key
) ? NULL
: ERR_PTR(-EINVAL
);
728 * Register a lock's class in the hash-table, if the class is not present
729 * yet. Otherwise we look it up. We cache the result in the lock object
730 * itself, so actual lookup of the hash should be once per lock object.
732 static struct lock_class
*
733 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
735 struct lockdep_subclass_key
*key
;
736 struct hlist_head
*hash_head
;
737 struct lock_class
*class;
739 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
741 class = look_up_lock_class(lock
, subclass
);
742 if (likely(!IS_ERR_OR_NULL(class)))
743 goto out_set_class_cache
;
746 * Debug-check: all keys must be persistent!
750 printk("INFO: trying to register non-static key.\n");
751 printk("the code is fine but needs lockdep annotation.\n");
752 printk("turning off the locking correctness validator.\n");
757 key
= lock
->key
->subkeys
+ subclass
;
758 hash_head
= classhashentry(key
);
764 * We have to do the hash-walk again, to avoid races
767 hlist_for_each_entry_rcu(class, hash_head
, hash_entry
) {
768 if (class->key
== key
)
773 * Allocate a new key from the static array, and add it to
776 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
777 if (!debug_locks_off_graph_unlock()) {
781 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
785 class = lock_classes
+ nr_lock_classes
++;
786 debug_atomic_inc(nr_unused_locks
);
788 class->name
= lock
->name
;
789 class->subclass
= subclass
;
790 INIT_LIST_HEAD(&class->lock_entry
);
791 INIT_LIST_HEAD(&class->locks_before
);
792 INIT_LIST_HEAD(&class->locks_after
);
793 class->name_version
= count_matching_names(class);
795 * We use RCU's safe list-add method to make
796 * parallel walking of the hash-list safe:
798 hlist_add_head_rcu(&class->hash_entry
, hash_head
);
800 * Add it to the global list of classes:
802 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
804 if (verbose(class)) {
807 printk("\nnew class %p: %s", class->key
, class->name
);
808 if (class->name_version
> 1)
809 printk(KERN_CONT
"#%d", class->name_version
);
810 printk(KERN_CONT
"\n");
821 if (!subclass
|| force
)
822 lock
->class_cache
[0] = class;
823 else if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
824 lock
->class_cache
[subclass
] = class;
827 * Hash collision, did we smoke some? We found a class with a matching
828 * hash but the subclass -- which is hashed in -- didn't match.
830 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
836 #ifdef CONFIG_PROVE_LOCKING
838 * Allocate a lockdep entry. (assumes the graph_lock held, returns
839 * with NULL on failure)
841 static struct lock_list
*alloc_list_entry(void)
843 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
844 if (!debug_locks_off_graph_unlock())
847 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
851 return list_entries
+ nr_list_entries
++;
855 * Add a new dependency to the head of the list:
857 static int add_lock_to_list(struct lock_class
*this, struct list_head
*head
,
858 unsigned long ip
, int distance
,
859 struct stack_trace
*trace
)
861 struct lock_list
*entry
;
863 * Lock not present yet - get a new dependency struct and
864 * add it to the list:
866 entry
= alloc_list_entry();
871 entry
->distance
= distance
;
872 entry
->trace
= *trace
;
874 * Both allocation and removal are done under the graph lock; but
875 * iteration is under RCU-sched; see look_up_lock_class() and
876 * lockdep_free_key_range().
878 list_add_tail_rcu(&entry
->entry
, head
);
884 * For good efficiency of modular, we use power of 2
886 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
887 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
890 * The circular_queue and helpers is used to implement the
891 * breadth-first search(BFS)algorithem, by which we can build
892 * the shortest path from the next lock to be acquired to the
893 * previous held lock if there is a circular between them.
895 struct circular_queue
{
896 unsigned long element
[MAX_CIRCULAR_QUEUE_SIZE
];
897 unsigned int front
, rear
;
900 static struct circular_queue lock_cq
;
902 unsigned int max_bfs_queue_depth
;
904 static unsigned int lockdep_dependency_gen_id
;
906 static inline void __cq_init(struct circular_queue
*cq
)
908 cq
->front
= cq
->rear
= 0;
909 lockdep_dependency_gen_id
++;
912 static inline int __cq_empty(struct circular_queue
*cq
)
914 return (cq
->front
== cq
->rear
);
917 static inline int __cq_full(struct circular_queue
*cq
)
919 return ((cq
->rear
+ 1) & CQ_MASK
) == cq
->front
;
922 static inline int __cq_enqueue(struct circular_queue
*cq
, unsigned long elem
)
927 cq
->element
[cq
->rear
] = elem
;
928 cq
->rear
= (cq
->rear
+ 1) & CQ_MASK
;
932 static inline int __cq_dequeue(struct circular_queue
*cq
, unsigned long *elem
)
937 *elem
= cq
->element
[cq
->front
];
938 cq
->front
= (cq
->front
+ 1) & CQ_MASK
;
942 static inline unsigned int __cq_get_elem_count(struct circular_queue
*cq
)
944 return (cq
->rear
- cq
->front
) & CQ_MASK
;
947 static inline void mark_lock_accessed(struct lock_list
*lock
,
948 struct lock_list
*parent
)
952 nr
= lock
- list_entries
;
953 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
954 lock
->parent
= parent
;
955 lock
->class->dep_gen_id
= lockdep_dependency_gen_id
;
958 static inline unsigned long lock_accessed(struct lock_list
*lock
)
962 nr
= lock
- list_entries
;
963 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
964 return lock
->class->dep_gen_id
== lockdep_dependency_gen_id
;
967 static inline struct lock_list
*get_lock_parent(struct lock_list
*child
)
969 return child
->parent
;
972 static inline int get_lock_depth(struct lock_list
*child
)
975 struct lock_list
*parent
;
977 while ((parent
= get_lock_parent(child
))) {
984 static int __bfs(struct lock_list
*source_entry
,
986 int (*match
)(struct lock_list
*entry
, void *data
),
987 struct lock_list
**target_entry
,
990 struct lock_list
*entry
;
991 struct list_head
*head
;
992 struct circular_queue
*cq
= &lock_cq
;
995 if (match(source_entry
, data
)) {
996 *target_entry
= source_entry
;
1002 head
= &source_entry
->class->locks_after
;
1004 head
= &source_entry
->class->locks_before
;
1006 if (list_empty(head
))
1010 __cq_enqueue(cq
, (unsigned long)source_entry
);
1012 while (!__cq_empty(cq
)) {
1013 struct lock_list
*lock
;
1015 __cq_dequeue(cq
, (unsigned long *)&lock
);
1023 head
= &lock
->class->locks_after
;
1025 head
= &lock
->class->locks_before
;
1027 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1029 list_for_each_entry_rcu(entry
, head
, entry
) {
1030 if (!lock_accessed(entry
)) {
1031 unsigned int cq_depth
;
1032 mark_lock_accessed(entry
, lock
);
1033 if (match(entry
, data
)) {
1034 *target_entry
= entry
;
1039 if (__cq_enqueue(cq
, (unsigned long)entry
)) {
1043 cq_depth
= __cq_get_elem_count(cq
);
1044 if (max_bfs_queue_depth
< cq_depth
)
1045 max_bfs_queue_depth
= cq_depth
;
1053 static inline int __bfs_forwards(struct lock_list
*src_entry
,
1055 int (*match
)(struct lock_list
*entry
, void *data
),
1056 struct lock_list
**target_entry
)
1058 return __bfs(src_entry
, data
, match
, target_entry
, 1);
1062 static inline int __bfs_backwards(struct lock_list
*src_entry
,
1064 int (*match
)(struct lock_list
*entry
, void *data
),
1065 struct lock_list
**target_entry
)
1067 return __bfs(src_entry
, data
, match
, target_entry
, 0);
1072 * Recursive, forwards-direction lock-dependency checking, used for
1073 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1078 * Print a dependency chain entry (this is only done when a deadlock
1079 * has been detected):
1082 print_circular_bug_entry(struct lock_list
*target
, int depth
)
1084 if (debug_locks_silent
)
1086 printk("\n-> #%u", depth
);
1087 print_lock_name(target
->class);
1088 printk(KERN_CONT
":\n");
1089 print_stack_trace(&target
->trace
, 6);
1095 print_circular_lock_scenario(struct held_lock
*src
,
1096 struct held_lock
*tgt
,
1097 struct lock_list
*prt
)
1099 struct lock_class
*source
= hlock_class(src
);
1100 struct lock_class
*target
= hlock_class(tgt
);
1101 struct lock_class
*parent
= prt
->class;
1104 * A direct locking problem where unsafe_class lock is taken
1105 * directly by safe_class lock, then all we need to show
1106 * is the deadlock scenario, as it is obvious that the
1107 * unsafe lock is taken under the safe lock.
1109 * But if there is a chain instead, where the safe lock takes
1110 * an intermediate lock (middle_class) where this lock is
1111 * not the same as the safe lock, then the lock chain is
1112 * used to describe the problem. Otherwise we would need
1113 * to show a different CPU case for each link in the chain
1114 * from the safe_class lock to the unsafe_class lock.
1116 if (parent
!= source
) {
1117 printk("Chain exists of:\n ");
1118 __print_lock_name(source
);
1119 printk(KERN_CONT
" --> ");
1120 __print_lock_name(parent
);
1121 printk(KERN_CONT
" --> ");
1122 __print_lock_name(target
);
1123 printk(KERN_CONT
"\n\n");
1126 printk(" Possible unsafe locking scenario:\n\n");
1127 printk(" CPU0 CPU1\n");
1128 printk(" ---- ----\n");
1130 __print_lock_name(target
);
1131 printk(KERN_CONT
");\n");
1133 __print_lock_name(parent
);
1134 printk(KERN_CONT
");\n");
1136 __print_lock_name(target
);
1137 printk(KERN_CONT
");\n");
1139 __print_lock_name(source
);
1140 printk(KERN_CONT
");\n");
1141 printk("\n *** DEADLOCK ***\n\n");
1145 * When a circular dependency is detected, print the
1149 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
,
1150 struct held_lock
*check_src
,
1151 struct held_lock
*check_tgt
)
1153 struct task_struct
*curr
= current
;
1155 if (debug_locks_silent
)
1159 pr_warn("======================================================\n");
1160 pr_warn("WARNING: possible circular locking dependency detected\n");
1161 print_kernel_ident();
1162 pr_warn("------------------------------------------------------\n");
1163 pr_warn("%s/%d is trying to acquire lock:\n",
1164 curr
->comm
, task_pid_nr(curr
));
1165 print_lock(check_src
);
1167 pr_warn("\nbut task is already holding lock:\n");
1169 print_lock(check_tgt
);
1170 pr_warn("\nwhich lock already depends on the new lock.\n\n");
1171 pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1173 print_circular_bug_entry(entry
, depth
);
1178 static inline int class_equal(struct lock_list
*entry
, void *data
)
1180 return entry
->class == data
;
1183 static noinline
int print_circular_bug(struct lock_list
*this,
1184 struct lock_list
*target
,
1185 struct held_lock
*check_src
,
1186 struct held_lock
*check_tgt
,
1187 struct stack_trace
*trace
)
1189 struct task_struct
*curr
= current
;
1190 struct lock_list
*parent
;
1191 struct lock_list
*first_parent
;
1194 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1197 if (!save_trace(&this->trace
))
1200 depth
= get_lock_depth(target
);
1202 print_circular_bug_header(target
, depth
, check_src
, check_tgt
);
1204 parent
= get_lock_parent(target
);
1205 first_parent
= parent
;
1208 print_circular_bug_entry(parent
, --depth
);
1209 parent
= get_lock_parent(parent
);
1212 printk("\nother info that might help us debug this:\n\n");
1213 print_circular_lock_scenario(check_src
, check_tgt
,
1216 lockdep_print_held_locks(curr
);
1218 printk("\nstack backtrace:\n");
1224 static noinline
int print_bfs_bug(int ret
)
1226 if (!debug_locks_off_graph_unlock())
1230 * Breadth-first-search failed, graph got corrupted?
1232 WARN(1, "lockdep bfs error:%d\n", ret
);
1237 static int noop_count(struct lock_list
*entry
, void *data
)
1239 (*(unsigned long *)data
)++;
1243 static unsigned long __lockdep_count_forward_deps(struct lock_list
*this)
1245 unsigned long count
= 0;
1246 struct lock_list
*uninitialized_var(target_entry
);
1248 __bfs_forwards(this, (void *)&count
, noop_count
, &target_entry
);
1252 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1254 unsigned long ret
, flags
;
1255 struct lock_list
this;
1260 local_irq_save(flags
);
1261 arch_spin_lock(&lockdep_lock
);
1262 ret
= __lockdep_count_forward_deps(&this);
1263 arch_spin_unlock(&lockdep_lock
);
1264 local_irq_restore(flags
);
1269 static unsigned long __lockdep_count_backward_deps(struct lock_list
*this)
1271 unsigned long count
= 0;
1272 struct lock_list
*uninitialized_var(target_entry
);
1274 __bfs_backwards(this, (void *)&count
, noop_count
, &target_entry
);
1279 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1281 unsigned long ret
, flags
;
1282 struct lock_list
this;
1287 local_irq_save(flags
);
1288 arch_spin_lock(&lockdep_lock
);
1289 ret
= __lockdep_count_backward_deps(&this);
1290 arch_spin_unlock(&lockdep_lock
);
1291 local_irq_restore(flags
);
1297 * Prove that the dependency graph starting at <entry> can not
1298 * lead to <target>. Print an error and return 0 if it does.
1301 check_noncircular(struct lock_list
*root
, struct lock_class
*target
,
1302 struct lock_list
**target_entry
)
1306 debug_atomic_inc(nr_cyclic_checks
);
1308 result
= __bfs_forwards(root
, target
, class_equal
, target_entry
);
1314 check_redundant(struct lock_list
*root
, struct lock_class
*target
,
1315 struct lock_list
**target_entry
)
1319 debug_atomic_inc(nr_redundant_checks
);
1321 result
= __bfs_forwards(root
, target
, class_equal
, target_entry
);
1326 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1328 * Forwards and backwards subgraph searching, for the purposes of
1329 * proving that two subgraphs can be connected by a new dependency
1330 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1333 static inline int usage_match(struct lock_list
*entry
, void *bit
)
1335 return entry
->class->usage_mask
& (1 << (enum lock_usage_bit
)bit
);
1341 * Find a node in the forwards-direction dependency sub-graph starting
1342 * at @root->class that matches @bit.
1344 * Return 0 if such a node exists in the subgraph, and put that node
1345 * into *@target_entry.
1347 * Return 1 otherwise and keep *@target_entry unchanged.
1348 * Return <0 on error.
1351 find_usage_forwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1352 struct lock_list
**target_entry
)
1356 debug_atomic_inc(nr_find_usage_forwards_checks
);
1358 result
= __bfs_forwards(root
, (void *)bit
, usage_match
, target_entry
);
1364 * Find a node in the backwards-direction dependency sub-graph starting
1365 * at @root->class that matches @bit.
1367 * Return 0 if such a node exists in the subgraph, and put that node
1368 * into *@target_entry.
1370 * Return 1 otherwise and keep *@target_entry unchanged.
1371 * Return <0 on error.
1374 find_usage_backwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1375 struct lock_list
**target_entry
)
1379 debug_atomic_inc(nr_find_usage_backwards_checks
);
1381 result
= __bfs_backwards(root
, (void *)bit
, usage_match
, target_entry
);
1386 static void print_lock_class_header(struct lock_class
*class, int depth
)
1390 printk("%*s->", depth
, "");
1391 print_lock_name(class);
1392 printk(KERN_CONT
" ops: %lu", class->ops
);
1393 printk(KERN_CONT
" {\n");
1395 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
1396 if (class->usage_mask
& (1 << bit
)) {
1399 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
1400 len
+= printk(KERN_CONT
" at:\n");
1401 print_stack_trace(class->usage_traces
+ bit
, len
);
1404 printk("%*s }\n", depth
, "");
1406 printk("%*s ... key at: [<%p>] %pS\n",
1407 depth
, "", class->key
, class->key
);
1411 * printk the shortest lock dependencies from @start to @end in reverse order:
1414 print_shortest_lock_dependencies(struct lock_list
*leaf
,
1415 struct lock_list
*root
)
1417 struct lock_list
*entry
= leaf
;
1420 /*compute depth from generated tree by BFS*/
1421 depth
= get_lock_depth(leaf
);
1424 print_lock_class_header(entry
->class, depth
);
1425 printk("%*s ... acquired at:\n", depth
, "");
1426 print_stack_trace(&entry
->trace
, 2);
1429 if (depth
== 0 && (entry
!= root
)) {
1430 printk("lockdep:%s bad path found in chain graph\n", __func__
);
1434 entry
= get_lock_parent(entry
);
1436 } while (entry
&& (depth
>= 0));
1442 print_irq_lock_scenario(struct lock_list
*safe_entry
,
1443 struct lock_list
*unsafe_entry
,
1444 struct lock_class
*prev_class
,
1445 struct lock_class
*next_class
)
1447 struct lock_class
*safe_class
= safe_entry
->class;
1448 struct lock_class
*unsafe_class
= unsafe_entry
->class;
1449 struct lock_class
*middle_class
= prev_class
;
1451 if (middle_class
== safe_class
)
1452 middle_class
= next_class
;
1455 * A direct locking problem where unsafe_class lock is taken
1456 * directly by safe_class lock, then all we need to show
1457 * is the deadlock scenario, as it is obvious that the
1458 * unsafe lock is taken under the safe lock.
1460 * But if there is a chain instead, where the safe lock takes
1461 * an intermediate lock (middle_class) where this lock is
1462 * not the same as the safe lock, then the lock chain is
1463 * used to describe the problem. Otherwise we would need
1464 * to show a different CPU case for each link in the chain
1465 * from the safe_class lock to the unsafe_class lock.
1467 if (middle_class
!= unsafe_class
) {
1468 printk("Chain exists of:\n ");
1469 __print_lock_name(safe_class
);
1470 printk(KERN_CONT
" --> ");
1471 __print_lock_name(middle_class
);
1472 printk(KERN_CONT
" --> ");
1473 __print_lock_name(unsafe_class
);
1474 printk(KERN_CONT
"\n\n");
1477 printk(" Possible interrupt unsafe locking scenario:\n\n");
1478 printk(" CPU0 CPU1\n");
1479 printk(" ---- ----\n");
1481 __print_lock_name(unsafe_class
);
1482 printk(KERN_CONT
");\n");
1483 printk(" local_irq_disable();\n");
1485 __print_lock_name(safe_class
);
1486 printk(KERN_CONT
");\n");
1488 __print_lock_name(middle_class
);
1489 printk(KERN_CONT
");\n");
1490 printk(" <Interrupt>\n");
1492 __print_lock_name(safe_class
);
1493 printk(KERN_CONT
");\n");
1494 printk("\n *** DEADLOCK ***\n\n");
1498 print_bad_irq_dependency(struct task_struct
*curr
,
1499 struct lock_list
*prev_root
,
1500 struct lock_list
*next_root
,
1501 struct lock_list
*backwards_entry
,
1502 struct lock_list
*forwards_entry
,
1503 struct held_lock
*prev
,
1504 struct held_lock
*next
,
1505 enum lock_usage_bit bit1
,
1506 enum lock_usage_bit bit2
,
1507 const char *irqclass
)
1509 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1513 pr_warn("=====================================================\n");
1514 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
1515 irqclass
, irqclass
);
1516 print_kernel_ident();
1517 pr_warn("-----------------------------------------------------\n");
1518 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1519 curr
->comm
, task_pid_nr(curr
),
1520 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1521 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1522 curr
->hardirqs_enabled
,
1523 curr
->softirqs_enabled
);
1526 pr_warn("\nand this task is already holding:\n");
1528 pr_warn("which would create a new lock dependency:\n");
1529 print_lock_name(hlock_class(prev
));
1531 print_lock_name(hlock_class(next
));
1534 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
1536 print_lock_name(backwards_entry
->class);
1537 pr_warn("\n... which became %s-irq-safe at:\n", irqclass
);
1539 print_stack_trace(backwards_entry
->class->usage_traces
+ bit1
, 1);
1541 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass
);
1542 print_lock_name(forwards_entry
->class);
1543 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass
);
1546 print_stack_trace(forwards_entry
->class->usage_traces
+ bit2
, 1);
1548 pr_warn("\nother info that might help us debug this:\n\n");
1549 print_irq_lock_scenario(backwards_entry
, forwards_entry
,
1550 hlock_class(prev
), hlock_class(next
));
1552 lockdep_print_held_locks(curr
);
1554 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass
);
1555 if (!save_trace(&prev_root
->trace
))
1557 print_shortest_lock_dependencies(backwards_entry
, prev_root
);
1559 pr_warn("\nthe dependencies between the lock to be acquired");
1560 pr_warn(" and %s-irq-unsafe lock:\n", irqclass
);
1561 if (!save_trace(&next_root
->trace
))
1563 print_shortest_lock_dependencies(forwards_entry
, next_root
);
1565 pr_warn("\nstack backtrace:\n");
1572 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1573 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1574 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1577 struct lock_list
this, that
;
1578 struct lock_list
*uninitialized_var(target_entry
);
1579 struct lock_list
*uninitialized_var(target_entry1
);
1583 this.class = hlock_class(prev
);
1584 ret
= find_usage_backwards(&this, bit_backwards
, &target_entry
);
1586 return print_bfs_bug(ret
);
1591 that
.class = hlock_class(next
);
1592 ret
= find_usage_forwards(&that
, bit_forwards
, &target_entry1
);
1594 return print_bfs_bug(ret
);
1598 return print_bad_irq_dependency(curr
, &this, &that
,
1599 target_entry
, target_entry1
,
1601 bit_backwards
, bit_forwards
, irqclass
);
1604 static const char *state_names
[] = {
1605 #define LOCKDEP_STATE(__STATE) \
1606 __stringify(__STATE),
1607 #include "lockdep_states.h"
1608 #undef LOCKDEP_STATE
1611 static const char *state_rnames
[] = {
1612 #define LOCKDEP_STATE(__STATE) \
1613 __stringify(__STATE)"-READ",
1614 #include "lockdep_states.h"
1615 #undef LOCKDEP_STATE
1618 static inline const char *state_name(enum lock_usage_bit bit
)
1620 return (bit
& 1) ? state_rnames
[bit
>> 2] : state_names
[bit
>> 2];
1623 static int exclusive_bit(int new_bit
)
1631 * bit 0 - write/read
1632 * bit 1 - used_in/enabled
1636 int state
= new_bit
& ~3;
1637 int dir
= new_bit
& 2;
1640 * keep state, bit flip the direction and strip read.
1642 return state
| (dir
^ 2);
1645 static int check_irq_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1646 struct held_lock
*next
, enum lock_usage_bit bit
)
1649 * Prove that the new dependency does not connect a hardirq-safe
1650 * lock with a hardirq-unsafe lock - to achieve this we search
1651 * the backwards-subgraph starting at <prev>, and the
1652 * forwards-subgraph starting at <next>:
1654 if (!check_usage(curr
, prev
, next
, bit
,
1655 exclusive_bit(bit
), state_name(bit
)))
1661 * Prove that the new dependency does not connect a hardirq-safe-read
1662 * lock with a hardirq-unsafe lock - to achieve this we search
1663 * the backwards-subgraph starting at <prev>, and the
1664 * forwards-subgraph starting at <next>:
1666 if (!check_usage(curr
, prev
, next
, bit
,
1667 exclusive_bit(bit
), state_name(bit
)))
1674 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1675 struct held_lock
*next
)
1677 #define LOCKDEP_STATE(__STATE) \
1678 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1680 #include "lockdep_states.h"
1681 #undef LOCKDEP_STATE
1686 static void inc_chains(void)
1688 if (current
->hardirq_context
)
1689 nr_hardirq_chains
++;
1691 if (current
->softirq_context
)
1692 nr_softirq_chains
++;
1694 nr_process_chains
++;
1701 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1702 struct held_lock
*next
)
1707 static inline void inc_chains(void)
1709 nr_process_chains
++;
1715 print_deadlock_scenario(struct held_lock
*nxt
,
1716 struct held_lock
*prv
)
1718 struct lock_class
*next
= hlock_class(nxt
);
1719 struct lock_class
*prev
= hlock_class(prv
);
1721 printk(" Possible unsafe locking scenario:\n\n");
1725 __print_lock_name(prev
);
1726 printk(KERN_CONT
");\n");
1728 __print_lock_name(next
);
1729 printk(KERN_CONT
");\n");
1730 printk("\n *** DEADLOCK ***\n\n");
1731 printk(" May be due to missing lock nesting notation\n\n");
1735 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1736 struct held_lock
*next
)
1738 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1742 pr_warn("============================================\n");
1743 pr_warn("WARNING: possible recursive locking detected\n");
1744 print_kernel_ident();
1745 pr_warn("--------------------------------------------\n");
1746 pr_warn("%s/%d is trying to acquire lock:\n",
1747 curr
->comm
, task_pid_nr(curr
));
1749 pr_warn("\nbut task is already holding lock:\n");
1752 pr_warn("\nother info that might help us debug this:\n");
1753 print_deadlock_scenario(next
, prev
);
1754 lockdep_print_held_locks(curr
);
1756 pr_warn("\nstack backtrace:\n");
1763 * Check whether we are holding such a class already.
1765 * (Note that this has to be done separately, because the graph cannot
1766 * detect such classes of deadlocks.)
1768 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1771 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1772 struct lockdep_map
*next_instance
, int read
)
1774 struct held_lock
*prev
;
1775 struct held_lock
*nest
= NULL
;
1778 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1779 prev
= curr
->held_locks
+ i
;
1781 if (prev
->instance
== next
->nest_lock
)
1784 if (hlock_class(prev
) != hlock_class(next
))
1788 * Allow read-after-read recursion of the same
1789 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1791 if ((read
== 2) && prev
->read
)
1795 * We're holding the nest_lock, which serializes this lock's
1796 * nesting behaviour.
1801 return print_deadlock_bug(curr
, prev
, next
);
1807 * There was a chain-cache miss, and we are about to add a new dependency
1808 * to a previous lock. We recursively validate the following rules:
1810 * - would the adding of the <prev> -> <next> dependency create a
1811 * circular dependency in the graph? [== circular deadlock]
1813 * - does the new prev->next dependency connect any hardirq-safe lock
1814 * (in the full backwards-subgraph starting at <prev>) with any
1815 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1816 * <next>)? [== illegal lock inversion with hardirq contexts]
1818 * - does the new prev->next dependency connect any softirq-safe lock
1819 * (in the full backwards-subgraph starting at <prev>) with any
1820 * softirq-unsafe lock (in the full forwards-subgraph starting at
1821 * <next>)? [== illegal lock inversion with softirq contexts]
1823 * any of these scenarios could lead to a deadlock.
1825 * Then if all the validations pass, we add the forwards and backwards
1829 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1830 struct held_lock
*next
, int distance
, struct stack_trace
*trace
,
1831 int (*save
)(struct stack_trace
*trace
))
1833 struct lock_list
*uninitialized_var(target_entry
);
1834 struct lock_list
*entry
;
1835 struct lock_list
this;
1839 * Prove that the new <prev> -> <next> dependency would not
1840 * create a circular dependency in the graph. (We do this by
1841 * forward-recursing into the graph starting at <next>, and
1842 * checking whether we can reach <prev>.)
1844 * We are using global variables to control the recursion, to
1845 * keep the stackframe size of the recursive functions low:
1847 this.class = hlock_class(next
);
1849 ret
= check_noncircular(&this, hlock_class(prev
), &target_entry
);
1850 if (unlikely(!ret
)) {
1851 if (!trace
->entries
) {
1853 * If @save fails here, the printing might trigger
1854 * a WARN but because of the !nr_entries it should
1855 * not do bad things.
1859 return print_circular_bug(&this, target_entry
, next
, prev
, trace
);
1861 else if (unlikely(ret
< 0))
1862 return print_bfs_bug(ret
);
1864 if (!check_prev_add_irq(curr
, prev
, next
))
1868 * For recursive read-locks we do all the dependency checks,
1869 * but we dont store read-triggered dependencies (only
1870 * write-triggered dependencies). This ensures that only the
1871 * write-side dependencies matter, and that if for example a
1872 * write-lock never takes any other locks, then the reads are
1873 * equivalent to a NOP.
1875 if (next
->read
== 2 || prev
->read
== 2)
1878 * Is the <prev> -> <next> dependency already present?
1880 * (this may occur even though this is a new chain: consider
1881 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1882 * chains - the second one will be new, but L1 already has
1883 * L2 added to its dependency list, due to the first chain.)
1885 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1886 if (entry
->class == hlock_class(next
)) {
1888 entry
->distance
= 1;
1894 * Is the <prev> -> <next> link redundant?
1896 this.class = hlock_class(prev
);
1898 ret
= check_redundant(&this, hlock_class(next
), &target_entry
);
1900 debug_atomic_inc(nr_redundant
);
1904 return print_bfs_bug(ret
);
1907 if (!trace
->entries
&& !save(trace
))
1911 * Ok, all validations passed, add the new lock
1912 * to the previous lock's dependency list:
1914 ret
= add_lock_to_list(hlock_class(next
),
1915 &hlock_class(prev
)->locks_after
,
1916 next
->acquire_ip
, distance
, trace
);
1921 ret
= add_lock_to_list(hlock_class(prev
),
1922 &hlock_class(next
)->locks_before
,
1923 next
->acquire_ip
, distance
, trace
);
1931 * Add the dependency to all directly-previous locks that are 'relevant'.
1932 * The ones that are relevant are (in increasing distance from curr):
1933 * all consecutive trylock entries and the final non-trylock entry - or
1934 * the end of this context's lock-chain - whichever comes first.
1937 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1939 int depth
= curr
->lockdep_depth
;
1940 struct held_lock
*hlock
;
1941 struct stack_trace trace
= {
1951 * Depth must not be zero for a non-head lock:
1956 * At least two relevant locks must exist for this
1959 if (curr
->held_locks
[depth
].irq_context
!=
1960 curr
->held_locks
[depth
-1].irq_context
)
1964 int distance
= curr
->lockdep_depth
- depth
+ 1;
1965 hlock
= curr
->held_locks
+ depth
- 1;
1968 * Only non-recursive-read entries get new dependencies
1971 if (hlock
->read
!= 2 && hlock
->check
) {
1972 int ret
= check_prev_add(curr
, hlock
, next
, distance
, &trace
, save_trace
);
1977 * Stop after the first non-trylock entry,
1978 * as non-trylock entries have added their
1979 * own direct dependencies already, so this
1980 * lock is connected to them indirectly:
1982 if (!hlock
->trylock
)
1988 * End of lock-stack?
1993 * Stop the search if we cross into another context:
1995 if (curr
->held_locks
[depth
].irq_context
!=
1996 curr
->held_locks
[depth
-1].irq_context
)
2001 if (!debug_locks_off_graph_unlock())
2005 * Clearly we all shouldn't be here, but since we made it we
2006 * can reliable say we messed up our state. See the above two
2007 * gotos for reasons why we could possibly end up here.
2014 unsigned long nr_lock_chains
;
2015 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
2016 int nr_chain_hlocks
;
2017 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
2019 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
2021 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
2025 * Returns the index of the first held_lock of the current chain
2027 static inline int get_first_held_lock(struct task_struct
*curr
,
2028 struct held_lock
*hlock
)
2031 struct held_lock
*hlock_curr
;
2033 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
2034 hlock_curr
= curr
->held_locks
+ i
;
2035 if (hlock_curr
->irq_context
!= hlock
->irq_context
)
2043 #ifdef CONFIG_DEBUG_LOCKDEP
2045 * Returns the next chain_key iteration
2047 static u64
print_chain_key_iteration(int class_idx
, u64 chain_key
)
2049 u64 new_chain_key
= iterate_chain_key(chain_key
, class_idx
);
2051 printk(" class_idx:%d -> chain_key:%016Lx",
2053 (unsigned long long)new_chain_key
);
2054 return new_chain_key
;
2058 print_chain_keys_held_locks(struct task_struct
*curr
, struct held_lock
*hlock_next
)
2060 struct held_lock
*hlock
;
2062 int depth
= curr
->lockdep_depth
;
2065 printk("depth: %u\n", depth
+ 1);
2066 for (i
= get_first_held_lock(curr
, hlock_next
); i
< depth
; i
++) {
2067 hlock
= curr
->held_locks
+ i
;
2068 chain_key
= print_chain_key_iteration(hlock
->class_idx
, chain_key
);
2073 print_chain_key_iteration(hlock_next
->class_idx
, chain_key
);
2074 print_lock(hlock_next
);
2077 static void print_chain_keys_chain(struct lock_chain
*chain
)
2083 printk("depth: %u\n", chain
->depth
);
2084 for (i
= 0; i
< chain
->depth
; i
++) {
2085 class_id
= chain_hlocks
[chain
->base
+ i
];
2086 chain_key
= print_chain_key_iteration(class_id
+ 1, chain_key
);
2088 print_lock_name(lock_classes
+ class_id
);
2093 static void print_collision(struct task_struct
*curr
,
2094 struct held_lock
*hlock_next
,
2095 struct lock_chain
*chain
)
2098 pr_warn("============================\n");
2099 pr_warn("WARNING: chain_key collision\n");
2100 print_kernel_ident();
2101 pr_warn("----------------------------\n");
2102 pr_warn("%s/%d: ", current
->comm
, task_pid_nr(current
));
2103 pr_warn("Hash chain already cached but the contents don't match!\n");
2105 pr_warn("Held locks:");
2106 print_chain_keys_held_locks(curr
, hlock_next
);
2108 pr_warn("Locks in cached chain:");
2109 print_chain_keys_chain(chain
);
2111 pr_warn("\nstack backtrace:\n");
2117 * Checks whether the chain and the current held locks are consistent
2118 * in depth and also in content. If they are not it most likely means
2119 * that there was a collision during the calculation of the chain_key.
2120 * Returns: 0 not passed, 1 passed
2122 static int check_no_collision(struct task_struct
*curr
,
2123 struct held_lock
*hlock
,
2124 struct lock_chain
*chain
)
2126 #ifdef CONFIG_DEBUG_LOCKDEP
2129 i
= get_first_held_lock(curr
, hlock
);
2131 if (DEBUG_LOCKS_WARN_ON(chain
->depth
!= curr
->lockdep_depth
- (i
- 1))) {
2132 print_collision(curr
, hlock
, chain
);
2136 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2137 id
= curr
->held_locks
[i
].class_idx
- 1;
2139 if (DEBUG_LOCKS_WARN_ON(chain_hlocks
[chain
->base
+ j
] != id
)) {
2140 print_collision(curr
, hlock
, chain
);
2149 * This is for building a chain between just two different classes,
2150 * instead of adding a new hlock upon current, which is done by
2151 * add_chain_cache().
2153 * This can be called in any context with two classes, while
2154 * add_chain_cache() must be done within the lock owener's context
2155 * since it uses hlock which might be racy in another context.
2157 static inline int add_chain_cache_classes(unsigned int prev
,
2159 unsigned int irq_context
,
2162 struct hlist_head
*hash_head
= chainhashentry(chain_key
);
2163 struct lock_chain
*chain
;
2166 * Allocate a new chain entry from the static array, and add
2171 * We might need to take the graph lock, ensure we've got IRQs
2172 * disabled to make this an IRQ-safe lock.. for recursion reasons
2173 * lockdep won't complain about its own locking errors.
2175 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2178 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
2179 if (!debug_locks_off_graph_unlock())
2182 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2187 chain
= lock_chains
+ nr_lock_chains
++;
2188 chain
->chain_key
= chain_key
;
2189 chain
->irq_context
= irq_context
;
2191 if (likely(nr_chain_hlocks
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2192 chain
->base
= nr_chain_hlocks
;
2193 nr_chain_hlocks
+= chain
->depth
;
2194 chain_hlocks
[chain
->base
] = prev
- 1;
2195 chain_hlocks
[chain
->base
+ 1] = next
-1;
2197 #ifdef CONFIG_DEBUG_LOCKDEP
2199 * Important for check_no_collision().
2202 if (!debug_locks_off_graph_unlock())
2205 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2211 hlist_add_head_rcu(&chain
->entry
, hash_head
);
2212 debug_atomic_inc(chain_lookup_misses
);
2219 * Adds a dependency chain into chain hashtable. And must be called with
2222 * Return 0 if fail, and graph_lock is released.
2223 * Return 1 if succeed, with graph_lock held.
2225 static inline int add_chain_cache(struct task_struct
*curr
,
2226 struct held_lock
*hlock
,
2229 struct lock_class
*class = hlock_class(hlock
);
2230 struct hlist_head
*hash_head
= chainhashentry(chain_key
);
2231 struct lock_chain
*chain
;
2235 * Allocate a new chain entry from the static array, and add
2240 * We might need to take the graph lock, ensure we've got IRQs
2241 * disabled to make this an IRQ-safe lock.. for recursion reasons
2242 * lockdep won't complain about its own locking errors.
2244 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2247 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
2248 if (!debug_locks_off_graph_unlock())
2251 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2255 chain
= lock_chains
+ nr_lock_chains
++;
2256 chain
->chain_key
= chain_key
;
2257 chain
->irq_context
= hlock
->irq_context
;
2258 i
= get_first_held_lock(curr
, hlock
);
2259 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
2261 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks
));
2262 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr
->held_locks
));
2263 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks
[0])) <= ARRAY_SIZE(lock_classes
));
2265 if (likely(nr_chain_hlocks
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2266 chain
->base
= nr_chain_hlocks
;
2267 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2268 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
2269 chain_hlocks
[chain
->base
+ j
] = lock_id
;
2271 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
2274 if (nr_chain_hlocks
< MAX_LOCKDEP_CHAIN_HLOCKS
)
2275 nr_chain_hlocks
+= chain
->depth
;
2277 #ifdef CONFIG_DEBUG_LOCKDEP
2279 * Important for check_no_collision().
2281 if (unlikely(nr_chain_hlocks
> MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2282 if (!debug_locks_off_graph_unlock())
2285 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2291 hlist_add_head_rcu(&chain
->entry
, hash_head
);
2292 debug_atomic_inc(chain_lookup_misses
);
2299 * Look up a dependency chain.
2301 static inline struct lock_chain
*lookup_chain_cache(u64 chain_key
)
2303 struct hlist_head
*hash_head
= chainhashentry(chain_key
);
2304 struct lock_chain
*chain
;
2307 * We can walk it lock-free, because entries only get added
2310 hlist_for_each_entry_rcu(chain
, hash_head
, entry
) {
2311 if (chain
->chain_key
== chain_key
) {
2312 debug_atomic_inc(chain_lookup_hits
);
2320 * If the key is not present yet in dependency chain cache then
2321 * add it and return 1 - in this case the new dependency chain is
2322 * validated. If the key is already hashed, return 0.
2323 * (On return with 1 graph_lock is held.)
2325 static inline int lookup_chain_cache_add(struct task_struct
*curr
,
2326 struct held_lock
*hlock
,
2329 struct lock_class
*class = hlock_class(hlock
);
2330 struct lock_chain
*chain
= lookup_chain_cache(chain_key
);
2334 if (!check_no_collision(curr
, hlock
, chain
))
2337 if (very_verbose(class)) {
2338 printk("\nhash chain already cached, key: "
2339 "%016Lx tail class: [%p] %s\n",
2340 (unsigned long long)chain_key
,
2341 class->key
, class->name
);
2347 if (very_verbose(class)) {
2348 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2349 (unsigned long long)chain_key
, class->key
, class->name
);
2356 * We have to walk the chain again locked - to avoid duplicates:
2358 chain
= lookup_chain_cache(chain_key
);
2364 if (!add_chain_cache(curr
, hlock
, chain_key
))
2370 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
2371 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
2374 * Trylock needs to maintain the stack of held locks, but it
2375 * does not add new dependencies, because trylock can be done
2378 * We look up the chain_key and do the O(N^2) check and update of
2379 * the dependencies only if this is a new dependency chain.
2380 * (If lookup_chain_cache_add() return with 1 it acquires
2381 * graph_lock for us)
2383 if (!hlock
->trylock
&& hlock
->check
&&
2384 lookup_chain_cache_add(curr
, hlock
, chain_key
)) {
2386 * Check whether last held lock:
2388 * - is irq-safe, if this lock is irq-unsafe
2389 * - is softirq-safe, if this lock is hardirq-unsafe
2391 * And check whether the new lock's dependency graph
2392 * could lead back to the previous lock.
2394 * any of these scenarios could lead to a deadlock. If
2397 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
2402 * Mark recursive read, as we jump over it when
2403 * building dependencies (just like we jump over
2409 * Add dependency only if this lock is not the head
2410 * of the chain, and if it's not a secondary read-lock:
2412 if (!chain_head
&& ret
!= 2) {
2413 if (!check_prevs_add(curr
, hlock
))
2419 /* after lookup_chain_cache_add(): */
2420 if (unlikely(!debug_locks
))
2427 static inline int validate_chain(struct task_struct
*curr
,
2428 struct lockdep_map
*lock
, struct held_lock
*hlock
,
2429 int chain_head
, u64 chain_key
)
2436 * We are building curr_chain_key incrementally, so double-check
2437 * it from scratch, to make sure that it's done correctly:
2439 static void check_chain_key(struct task_struct
*curr
)
2441 #ifdef CONFIG_DEBUG_LOCKDEP
2442 struct held_lock
*hlock
, *prev_hlock
= NULL
;
2446 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2447 hlock
= curr
->held_locks
+ i
;
2448 if (chain_key
!= hlock
->prev_chain_key
) {
2451 * We got mighty confused, our chain keys don't match
2452 * with what we expect, someone trample on our task state?
2454 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2455 curr
->lockdep_depth
, i
,
2456 (unsigned long long)chain_key
,
2457 (unsigned long long)hlock
->prev_chain_key
);
2461 * Whoops ran out of static storage again?
2463 if (DEBUG_LOCKS_WARN_ON(hlock
->class_idx
> MAX_LOCKDEP_KEYS
))
2466 if (prev_hlock
&& (prev_hlock
->irq_context
!=
2467 hlock
->irq_context
))
2469 chain_key
= iterate_chain_key(chain_key
, hlock
->class_idx
);
2472 if (chain_key
!= curr
->curr_chain_key
) {
2475 * More smoking hash instead of calculating it, damn see these
2476 * numbers float.. I bet that a pink elephant stepped on my memory.
2478 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2479 curr
->lockdep_depth
, i
,
2480 (unsigned long long)chain_key
,
2481 (unsigned long long)curr
->curr_chain_key
);
2487 print_usage_bug_scenario(struct held_lock
*lock
)
2489 struct lock_class
*class = hlock_class(lock
);
2491 printk(" Possible unsafe locking scenario:\n\n");
2495 __print_lock_name(class);
2496 printk(KERN_CONT
");\n");
2497 printk(" <Interrupt>\n");
2499 __print_lock_name(class);
2500 printk(KERN_CONT
");\n");
2501 printk("\n *** DEADLOCK ***\n\n");
2505 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
2506 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
2508 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2512 pr_warn("================================\n");
2513 pr_warn("WARNING: inconsistent lock state\n");
2514 print_kernel_ident();
2515 pr_warn("--------------------------------\n");
2517 pr_warn("inconsistent {%s} -> {%s} usage.\n",
2518 usage_str
[prev_bit
], usage_str
[new_bit
]);
2520 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2521 curr
->comm
, task_pid_nr(curr
),
2522 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
2523 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
2524 trace_hardirqs_enabled(curr
),
2525 trace_softirqs_enabled(curr
));
2528 pr_warn("{%s} state was registered at:\n", usage_str
[prev_bit
]);
2529 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
2531 print_irqtrace_events(curr
);
2532 pr_warn("\nother info that might help us debug this:\n");
2533 print_usage_bug_scenario(this);
2535 lockdep_print_held_locks(curr
);
2537 pr_warn("\nstack backtrace:\n");
2544 * Print out an error if an invalid bit is set:
2547 valid_state(struct task_struct
*curr
, struct held_lock
*this,
2548 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
2550 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
2551 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
2555 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2556 enum lock_usage_bit new_bit
);
2558 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2561 * print irq inversion bug:
2564 print_irq_inversion_bug(struct task_struct
*curr
,
2565 struct lock_list
*root
, struct lock_list
*other
,
2566 struct held_lock
*this, int forwards
,
2567 const char *irqclass
)
2569 struct lock_list
*entry
= other
;
2570 struct lock_list
*middle
= NULL
;
2573 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2577 pr_warn("========================================================\n");
2578 pr_warn("WARNING: possible irq lock inversion dependency detected\n");
2579 print_kernel_ident();
2580 pr_warn("--------------------------------------------------------\n");
2581 pr_warn("%s/%d just changed the state of lock:\n",
2582 curr
->comm
, task_pid_nr(curr
));
2585 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass
);
2587 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass
);
2588 print_lock_name(other
->class);
2589 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2591 pr_warn("\nother info that might help us debug this:\n");
2593 /* Find a middle lock (if one exists) */
2594 depth
= get_lock_depth(other
);
2596 if (depth
== 0 && (entry
!= root
)) {
2597 pr_warn("lockdep:%s bad path found in chain graph\n", __func__
);
2601 entry
= get_lock_parent(entry
);
2603 } while (entry
&& entry
!= root
&& (depth
>= 0));
2605 print_irq_lock_scenario(root
, other
,
2606 middle
? middle
->class : root
->class, other
->class);
2608 print_irq_lock_scenario(other
, root
,
2609 middle
? middle
->class : other
->class, root
->class);
2611 lockdep_print_held_locks(curr
);
2613 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2614 if (!save_trace(&root
->trace
))
2616 print_shortest_lock_dependencies(other
, root
);
2618 pr_warn("\nstack backtrace:\n");
2625 * Prove that in the forwards-direction subgraph starting at <this>
2626 * there is no lock matching <mask>:
2629 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
2630 enum lock_usage_bit bit
, const char *irqclass
)
2633 struct lock_list root
;
2634 struct lock_list
*uninitialized_var(target_entry
);
2637 root
.class = hlock_class(this);
2638 ret
= find_usage_forwards(&root
, bit
, &target_entry
);
2640 return print_bfs_bug(ret
);
2644 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2649 * Prove that in the backwards-direction subgraph starting at <this>
2650 * there is no lock matching <mask>:
2653 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
2654 enum lock_usage_bit bit
, const char *irqclass
)
2657 struct lock_list root
;
2658 struct lock_list
*uninitialized_var(target_entry
);
2661 root
.class = hlock_class(this);
2662 ret
= find_usage_backwards(&root
, bit
, &target_entry
);
2664 return print_bfs_bug(ret
);
2668 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2672 void print_irqtrace_events(struct task_struct
*curr
)
2674 printk("irq event stamp: %u\n", curr
->irq_events
);
2675 printk("hardirqs last enabled at (%u): [<%p>] %pS\n",
2676 curr
->hardirq_enable_event
, (void *)curr
->hardirq_enable_ip
,
2677 (void *)curr
->hardirq_enable_ip
);
2678 printk("hardirqs last disabled at (%u): [<%p>] %pS\n",
2679 curr
->hardirq_disable_event
, (void *)curr
->hardirq_disable_ip
,
2680 (void *)curr
->hardirq_disable_ip
);
2681 printk("softirqs last enabled at (%u): [<%p>] %pS\n",
2682 curr
->softirq_enable_event
, (void *)curr
->softirq_enable_ip
,
2683 (void *)curr
->softirq_enable_ip
);
2684 printk("softirqs last disabled at (%u): [<%p>] %pS\n",
2685 curr
->softirq_disable_event
, (void *)curr
->softirq_disable_ip
,
2686 (void *)curr
->softirq_disable_ip
);
2689 static int HARDIRQ_verbose(struct lock_class
*class)
2692 return class_filter(class);
2697 static int SOFTIRQ_verbose(struct lock_class
*class)
2700 return class_filter(class);
2705 #define STRICT_READ_CHECKS 1
2707 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2708 #define LOCKDEP_STATE(__STATE) \
2710 #include "lockdep_states.h"
2711 #undef LOCKDEP_STATE
2714 static inline int state_verbose(enum lock_usage_bit bit
,
2715 struct lock_class
*class)
2717 return state_verbose_f
[bit
>> 2](class);
2720 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2721 enum lock_usage_bit bit
, const char *name
);
2724 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2725 enum lock_usage_bit new_bit
)
2727 int excl_bit
= exclusive_bit(new_bit
);
2728 int read
= new_bit
& 1;
2729 int dir
= new_bit
& 2;
2732 * mark USED_IN has to look forwards -- to ensure no dependency
2733 * has ENABLED state, which would allow recursion deadlocks.
2735 * mark ENABLED has to look backwards -- to ensure no dependee
2736 * has USED_IN state, which, again, would allow recursion deadlocks.
2738 check_usage_f usage
= dir
?
2739 check_usage_backwards
: check_usage_forwards
;
2742 * Validate that this particular lock does not have conflicting
2745 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2749 * Validate that the lock dependencies don't have conflicting usage
2752 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2753 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2757 * Check for read in write conflicts
2760 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2763 if (STRICT_READ_CHECKS
&&
2764 !usage(curr
, this, excl_bit
+ 1,
2765 state_name(new_bit
+ 1)))
2769 if (state_verbose(new_bit
, hlock_class(this)))
2776 #define LOCKDEP_STATE(__STATE) __STATE,
2777 #include "lockdep_states.h"
2778 #undef LOCKDEP_STATE
2782 * Mark all held locks with a usage bit:
2785 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2787 enum lock_usage_bit usage_bit
;
2788 struct held_lock
*hlock
;
2791 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2792 hlock
= curr
->held_locks
+ i
;
2794 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2796 usage_bit
+= 1; /* READ */
2798 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2803 if (!mark_lock(curr
, hlock
, usage_bit
))
2811 * Hardirqs will be enabled:
2813 static void __trace_hardirqs_on_caller(unsigned long ip
)
2815 struct task_struct
*curr
= current
;
2817 /* we'll do an OFF -> ON transition: */
2818 curr
->hardirqs_enabled
= 1;
2821 * We are going to turn hardirqs on, so set the
2822 * usage bit for all held locks:
2824 if (!mark_held_locks(curr
, HARDIRQ
))
2827 * If we have softirqs enabled, then set the usage
2828 * bit for all held locks. (disabled hardirqs prevented
2829 * this bit from being set before)
2831 if (curr
->softirqs_enabled
)
2832 if (!mark_held_locks(curr
, SOFTIRQ
))
2835 curr
->hardirq_enable_ip
= ip
;
2836 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2837 debug_atomic_inc(hardirqs_on_events
);
2840 __visible
void trace_hardirqs_on_caller(unsigned long ip
)
2842 time_hardirqs_on(CALLER_ADDR0
, ip
);
2844 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2847 if (unlikely(current
->hardirqs_enabled
)) {
2849 * Neither irq nor preemption are disabled here
2850 * so this is racy by nature but losing one hit
2851 * in a stat is not a big deal.
2853 __debug_atomic_inc(redundant_hardirqs_on
);
2858 * We're enabling irqs and according to our state above irqs weren't
2859 * already enabled, yet we find the hardware thinks they are in fact
2860 * enabled.. someone messed up their IRQ state tracing.
2862 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2866 * See the fine text that goes along with this variable definition.
2868 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled
)))
2872 * Can't allow enabling interrupts while in an interrupt handler,
2873 * that's general bad form and such. Recursion, limited stack etc..
2875 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2878 current
->lockdep_recursion
= 1;
2879 __trace_hardirqs_on_caller(ip
);
2880 current
->lockdep_recursion
= 0;
2882 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2884 void trace_hardirqs_on(void)
2886 trace_hardirqs_on_caller(CALLER_ADDR0
);
2888 EXPORT_SYMBOL(trace_hardirqs_on
);
2891 * Hardirqs were disabled:
2893 __visible
void trace_hardirqs_off_caller(unsigned long ip
)
2895 struct task_struct
*curr
= current
;
2897 time_hardirqs_off(CALLER_ADDR0
, ip
);
2899 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2903 * So we're supposed to get called after you mask local IRQs, but for
2904 * some reason the hardware doesn't quite think you did a proper job.
2906 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2909 if (curr
->hardirqs_enabled
) {
2911 * We have done an ON -> OFF transition:
2913 curr
->hardirqs_enabled
= 0;
2914 curr
->hardirq_disable_ip
= ip
;
2915 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2916 debug_atomic_inc(hardirqs_off_events
);
2918 debug_atomic_inc(redundant_hardirqs_off
);
2920 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2922 void trace_hardirqs_off(void)
2924 trace_hardirqs_off_caller(CALLER_ADDR0
);
2926 EXPORT_SYMBOL(trace_hardirqs_off
);
2929 * Softirqs will be enabled:
2931 void trace_softirqs_on(unsigned long ip
)
2933 struct task_struct
*curr
= current
;
2935 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2939 * We fancy IRQs being disabled here, see softirq.c, avoids
2940 * funny state and nesting things.
2942 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2945 if (curr
->softirqs_enabled
) {
2946 debug_atomic_inc(redundant_softirqs_on
);
2950 current
->lockdep_recursion
= 1;
2952 * We'll do an OFF -> ON transition:
2954 curr
->softirqs_enabled
= 1;
2955 curr
->softirq_enable_ip
= ip
;
2956 curr
->softirq_enable_event
= ++curr
->irq_events
;
2957 debug_atomic_inc(softirqs_on_events
);
2959 * We are going to turn softirqs on, so set the
2960 * usage bit for all held locks, if hardirqs are
2963 if (curr
->hardirqs_enabled
)
2964 mark_held_locks(curr
, SOFTIRQ
);
2965 current
->lockdep_recursion
= 0;
2969 * Softirqs were disabled:
2971 void trace_softirqs_off(unsigned long ip
)
2973 struct task_struct
*curr
= current
;
2975 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2979 * We fancy IRQs being disabled here, see softirq.c
2981 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2984 if (curr
->softirqs_enabled
) {
2986 * We have done an ON -> OFF transition:
2988 curr
->softirqs_enabled
= 0;
2989 curr
->softirq_disable_ip
= ip
;
2990 curr
->softirq_disable_event
= ++curr
->irq_events
;
2991 debug_atomic_inc(softirqs_off_events
);
2993 * Whoops, we wanted softirqs off, so why aren't they?
2995 DEBUG_LOCKS_WARN_ON(!softirq_count());
2997 debug_atomic_inc(redundant_softirqs_off
);
3000 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
3003 * If non-trylock use in a hardirq or softirq context, then
3004 * mark the lock as used in these contexts:
3006 if (!hlock
->trylock
) {
3008 if (curr
->hardirq_context
)
3009 if (!mark_lock(curr
, hlock
,
3010 LOCK_USED_IN_HARDIRQ_READ
))
3012 if (curr
->softirq_context
)
3013 if (!mark_lock(curr
, hlock
,
3014 LOCK_USED_IN_SOFTIRQ_READ
))
3017 if (curr
->hardirq_context
)
3018 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
3020 if (curr
->softirq_context
)
3021 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
3025 if (!hlock
->hardirqs_off
) {
3027 if (!mark_lock(curr
, hlock
,
3028 LOCK_ENABLED_HARDIRQ_READ
))
3030 if (curr
->softirqs_enabled
)
3031 if (!mark_lock(curr
, hlock
,
3032 LOCK_ENABLED_SOFTIRQ_READ
))
3035 if (!mark_lock(curr
, hlock
,
3036 LOCK_ENABLED_HARDIRQ
))
3038 if (curr
->softirqs_enabled
)
3039 if (!mark_lock(curr
, hlock
,
3040 LOCK_ENABLED_SOFTIRQ
))
3048 static inline unsigned int task_irq_context(struct task_struct
*task
)
3050 return 2 * !!task
->hardirq_context
+ !!task
->softirq_context
;
3053 static int separate_irq_context(struct task_struct
*curr
,
3054 struct held_lock
*hlock
)
3056 unsigned int depth
= curr
->lockdep_depth
;
3059 * Keep track of points where we cross into an interrupt context:
3062 struct held_lock
*prev_hlock
;
3064 prev_hlock
= curr
->held_locks
+ depth
-1;
3066 * If we cross into another context, reset the
3067 * hash key (this also prevents the checking and the
3068 * adding of the dependency to 'prev'):
3070 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
3076 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3079 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
3080 enum lock_usage_bit new_bit
)
3082 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
3086 static inline int mark_irqflags(struct task_struct
*curr
,
3087 struct held_lock
*hlock
)
3092 static inline unsigned int task_irq_context(struct task_struct
*task
)
3097 static inline int separate_irq_context(struct task_struct
*curr
,
3098 struct held_lock
*hlock
)
3103 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3106 * Mark a lock with a usage bit, and validate the state transition:
3108 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
3109 enum lock_usage_bit new_bit
)
3111 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
3114 * If already set then do not dirty the cacheline,
3115 * nor do any checks:
3117 if (likely(hlock_class(this)->usage_mask
& new_mask
))
3123 * Make sure we didn't race:
3125 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
3130 hlock_class(this)->usage_mask
|= new_mask
;
3132 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
3136 #define LOCKDEP_STATE(__STATE) \
3137 case LOCK_USED_IN_##__STATE: \
3138 case LOCK_USED_IN_##__STATE##_READ: \
3139 case LOCK_ENABLED_##__STATE: \
3140 case LOCK_ENABLED_##__STATE##_READ:
3141 #include "lockdep_states.h"
3142 #undef LOCKDEP_STATE
3143 ret
= mark_lock_irq(curr
, this, new_bit
);
3148 debug_atomic_dec(nr_unused_locks
);
3151 if (!debug_locks_off_graph_unlock())
3160 * We must printk outside of the graph_lock:
3163 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
3165 print_irqtrace_events(curr
);
3173 * Initialize a lock instance's lock-class mapping info:
3175 static void __lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
3176 struct lock_class_key
*key
, int subclass
)
3180 for (i
= 0; i
< NR_LOCKDEP_CACHING_CLASSES
; i
++)
3181 lock
->class_cache
[i
] = NULL
;
3183 #ifdef CONFIG_LOCK_STAT
3184 lock
->cpu
= raw_smp_processor_id();
3188 * Can't be having no nameless bastards around this place!
3190 if (DEBUG_LOCKS_WARN_ON(!name
)) {
3191 lock
->name
= "NULL";
3198 * No key, no joy, we need to hash something.
3200 if (DEBUG_LOCKS_WARN_ON(!key
))
3203 * Sanity check, the lock-class key must be persistent:
3205 if (!static_obj(key
)) {
3206 printk("BUG: key %p not in .data!\n", key
);
3208 * What it says above ^^^^^, I suggest you read it.
3210 DEBUG_LOCKS_WARN_ON(1);
3215 if (unlikely(!debug_locks
))
3219 unsigned long flags
;
3221 if (DEBUG_LOCKS_WARN_ON(current
->lockdep_recursion
))
3224 raw_local_irq_save(flags
);
3225 current
->lockdep_recursion
= 1;
3226 register_lock_class(lock
, subclass
, 1);
3227 current
->lockdep_recursion
= 0;
3228 raw_local_irq_restore(flags
);
3232 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
3233 struct lock_class_key
*key
, int subclass
)
3235 __lockdep_init_map(lock
, name
, key
, subclass
);
3237 EXPORT_SYMBOL_GPL(lockdep_init_map
);
3239 struct lock_class_key __lockdep_no_validate__
;
3240 EXPORT_SYMBOL_GPL(__lockdep_no_validate__
);
3243 print_lock_nested_lock_not_held(struct task_struct
*curr
,
3244 struct held_lock
*hlock
,
3247 if (!debug_locks_off())
3249 if (debug_locks_silent
)
3253 pr_warn("==================================\n");
3254 pr_warn("WARNING: Nested lock was not taken\n");
3255 print_kernel_ident();
3256 pr_warn("----------------------------------\n");
3258 pr_warn("%s/%d is trying to lock:\n", curr
->comm
, task_pid_nr(curr
));
3261 pr_warn("\nbut this task is not holding:\n");
3262 pr_warn("%s\n", hlock
->nest_lock
->name
);
3264 pr_warn("\nstack backtrace:\n");
3267 pr_warn("\nother info that might help us debug this:\n");
3268 lockdep_print_held_locks(curr
);
3270 pr_warn("\nstack backtrace:\n");
3276 static int __lock_is_held(struct lockdep_map
*lock
, int read
);
3279 * This gets called for every mutex_lock*()/spin_lock*() operation.
3280 * We maintain the dependency maps and validate the locking attempt:
3282 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3283 int trylock
, int read
, int check
, int hardirqs_off
,
3284 struct lockdep_map
*nest_lock
, unsigned long ip
,
3285 int references
, int pin_count
)
3287 struct task_struct
*curr
= current
;
3288 struct lock_class
*class = NULL
;
3289 struct held_lock
*hlock
;
3295 if (unlikely(!debug_locks
))
3299 * Lockdep should run with IRQs disabled, otherwise we could
3300 * get an interrupt which would want to take locks, which would
3301 * end up in lockdep and have you got a head-ache already?
3303 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3306 if (!prove_locking
|| lock
->key
== &__lockdep_no_validate__
)
3309 if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
3310 class = lock
->class_cache
[subclass
];
3314 if (unlikely(!class)) {
3315 class = register_lock_class(lock
, subclass
, 0);
3319 atomic_inc((atomic_t
*)&class->ops
);
3320 if (very_verbose(class)) {
3321 printk("\nacquire class [%p] %s", class->key
, class->name
);
3322 if (class->name_version
> 1)
3323 printk(KERN_CONT
"#%d", class->name_version
);
3324 printk(KERN_CONT
"\n");
3329 * Add the lock to the list of currently held locks.
3330 * (we dont increase the depth just yet, up until the
3331 * dependency checks are done)
3333 depth
= curr
->lockdep_depth
;
3335 * Ran out of static storage for our per-task lock stack again have we?
3337 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
3340 class_idx
= class - lock_classes
+ 1;
3343 hlock
= curr
->held_locks
+ depth
- 1;
3344 if (hlock
->class_idx
== class_idx
&& nest_lock
) {
3345 if (hlock
->references
) {
3347 * Check: unsigned int references:12, overflow.
3349 if (DEBUG_LOCKS_WARN_ON(hlock
->references
== (1 << 12)-1))
3352 hlock
->references
++;
3354 hlock
->references
= 2;
3361 hlock
= curr
->held_locks
+ depth
;
3363 * Plain impossible, we just registered it and checked it weren't no
3364 * NULL like.. I bet this mushroom I ate was good!
3366 if (DEBUG_LOCKS_WARN_ON(!class))
3368 hlock
->class_idx
= class_idx
;
3369 hlock
->acquire_ip
= ip
;
3370 hlock
->instance
= lock
;
3371 hlock
->nest_lock
= nest_lock
;
3372 hlock
->irq_context
= task_irq_context(curr
);
3373 hlock
->trylock
= trylock
;
3375 hlock
->check
= check
;
3376 hlock
->hardirqs_off
= !!hardirqs_off
;
3377 hlock
->references
= references
;
3378 #ifdef CONFIG_LOCK_STAT
3379 hlock
->waittime_stamp
= 0;
3380 hlock
->holdtime_stamp
= lockstat_clock();
3382 hlock
->pin_count
= pin_count
;
3384 if (check
&& !mark_irqflags(curr
, hlock
))
3387 /* mark it as used: */
3388 if (!mark_lock(curr
, hlock
, LOCK_USED
))
3392 * Calculate the chain hash: it's the combined hash of all the
3393 * lock keys along the dependency chain. We save the hash value
3394 * at every step so that we can get the current hash easily
3395 * after unlock. The chain hash is then used to cache dependency
3398 * The 'key ID' is what is the most compact key value to drive
3399 * the hash, not class->key.
3402 * Whoops, we did it again.. ran straight out of our static allocation.
3404 if (DEBUG_LOCKS_WARN_ON(class_idx
> MAX_LOCKDEP_KEYS
))
3407 chain_key
= curr
->curr_chain_key
;
3410 * How can we have a chain hash when we ain't got no keys?!
3412 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
3417 hlock
->prev_chain_key
= chain_key
;
3418 if (separate_irq_context(curr
, hlock
)) {
3422 chain_key
= iterate_chain_key(chain_key
, class_idx
);
3424 if (nest_lock
&& !__lock_is_held(nest_lock
, -1))
3425 return print_lock_nested_lock_not_held(curr
, hlock
, ip
);
3427 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
3430 curr
->curr_chain_key
= chain_key
;
3431 curr
->lockdep_depth
++;
3432 check_chain_key(curr
);
3433 #ifdef CONFIG_DEBUG_LOCKDEP
3434 if (unlikely(!debug_locks
))
3437 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
3439 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3440 printk(KERN_DEBUG
"depth: %i max: %lu!\n",
3441 curr
->lockdep_depth
, MAX_LOCK_DEPTH
);
3443 lockdep_print_held_locks(current
);
3444 debug_show_all_locks();
3450 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
3451 max_lockdep_depth
= curr
->lockdep_depth
;
3457 print_unlock_imbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3460 if (!debug_locks_off())
3462 if (debug_locks_silent
)
3466 pr_warn("=====================================\n");
3467 pr_warn("WARNING: bad unlock balance detected!\n");
3468 print_kernel_ident();
3469 pr_warn("-------------------------------------\n");
3470 pr_warn("%s/%d is trying to release lock (",
3471 curr
->comm
, task_pid_nr(curr
));
3472 print_lockdep_cache(lock
);
3475 pr_warn("but there are no more locks to release!\n");
3476 pr_warn("\nother info that might help us debug this:\n");
3477 lockdep_print_held_locks(curr
);
3479 pr_warn("\nstack backtrace:\n");
3485 static int match_held_lock(struct held_lock
*hlock
, struct lockdep_map
*lock
)
3487 if (hlock
->instance
== lock
)
3490 if (hlock
->references
) {
3491 struct lock_class
*class = lock
->class_cache
[0];
3494 class = look_up_lock_class(lock
, 0);
3497 * If look_up_lock_class() failed to find a class, we're trying
3498 * to test if we hold a lock that has never yet been acquired.
3499 * Clearly if the lock hasn't been acquired _ever_, we're not
3500 * holding it either, so report failure.
3502 if (IS_ERR_OR_NULL(class))
3506 * References, but not a lock we're actually ref-counting?
3507 * State got messed up, follow the sites that change ->references
3508 * and try to make sense of it.
3510 if (DEBUG_LOCKS_WARN_ON(!hlock
->nest_lock
))
3513 if (hlock
->class_idx
== class - lock_classes
+ 1)
3520 /* @depth must not be zero */
3521 static struct held_lock
*find_held_lock(struct task_struct
*curr
,
3522 struct lockdep_map
*lock
,
3523 unsigned int depth
, int *idx
)
3525 struct held_lock
*ret
, *hlock
, *prev_hlock
;
3529 hlock
= curr
->held_locks
+ i
;
3531 if (match_held_lock(hlock
, lock
))
3535 for (i
--, prev_hlock
= hlock
--;
3537 i
--, prev_hlock
= hlock
--) {
3539 * We must not cross into another context:
3541 if (prev_hlock
->irq_context
!= hlock
->irq_context
) {
3545 if (match_held_lock(hlock
, lock
)) {
3556 static int reacquire_held_locks(struct task_struct
*curr
, unsigned int depth
,
3559 struct held_lock
*hlock
;
3561 for (hlock
= curr
->held_locks
+ idx
; idx
< depth
; idx
++, hlock
++) {
3562 if (!__lock_acquire(hlock
->instance
,
3563 hlock_class(hlock
)->subclass
,
3565 hlock
->read
, hlock
->check
,
3566 hlock
->hardirqs_off
,
3567 hlock
->nest_lock
, hlock
->acquire_ip
,
3568 hlock
->references
, hlock
->pin_count
))
3575 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
3576 struct lock_class_key
*key
, unsigned int subclass
,
3579 struct task_struct
*curr
= current
;
3580 struct held_lock
*hlock
;
3581 struct lock_class
*class;
3585 depth
= curr
->lockdep_depth
;
3587 * This function is about (re)setting the class of a held lock,
3588 * yet we're not actually holding any locks. Naughty user!
3590 if (DEBUG_LOCKS_WARN_ON(!depth
))
3593 hlock
= find_held_lock(curr
, lock
, depth
, &i
);
3595 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3597 lockdep_init_map(lock
, name
, key
, 0);
3598 class = register_lock_class(lock
, subclass
, 0);
3599 hlock
->class_idx
= class - lock_classes
+ 1;
3601 curr
->lockdep_depth
= i
;
3602 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3604 if (reacquire_held_locks(curr
, depth
, i
))
3608 * I took it apart and put it back together again, except now I have
3609 * these 'spare' parts.. where shall I put them.
3611 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
3616 static int __lock_downgrade(struct lockdep_map
*lock
, unsigned long ip
)
3618 struct task_struct
*curr
= current
;
3619 struct held_lock
*hlock
;
3623 depth
= curr
->lockdep_depth
;
3625 * This function is about (re)setting the class of a held lock,
3626 * yet we're not actually holding any locks. Naughty user!
3628 if (DEBUG_LOCKS_WARN_ON(!depth
))
3631 hlock
= find_held_lock(curr
, lock
, depth
, &i
);
3633 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3635 curr
->lockdep_depth
= i
;
3636 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3638 WARN(hlock
->read
, "downgrading a read lock");
3640 hlock
->acquire_ip
= ip
;
3642 if (reacquire_held_locks(curr
, depth
, i
))
3646 * I took it apart and put it back together again, except now I have
3647 * these 'spare' parts.. where shall I put them.
3649 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
3655 * Remove the lock to the list of currently held locks - this gets
3656 * called on mutex_unlock()/spin_unlock*() (or on a failed
3657 * mutex_lock_interruptible()).
3659 * @nested is an hysterical artifact, needs a tree wide cleanup.
3662 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
3664 struct task_struct
*curr
= current
;
3665 struct held_lock
*hlock
;
3669 if (unlikely(!debug_locks
))
3672 depth
= curr
->lockdep_depth
;
3674 * So we're all set to release this lock.. wait what lock? We don't
3675 * own any locks, you've been drinking again?
3677 if (DEBUG_LOCKS_WARN_ON(depth
<= 0))
3678 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3681 * Check whether the lock exists in the current stack
3684 hlock
= find_held_lock(curr
, lock
, depth
, &i
);
3686 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3688 if (hlock
->instance
== lock
)
3689 lock_release_holdtime(hlock
);
3691 WARN(hlock
->pin_count
, "releasing a pinned lock\n");
3693 if (hlock
->references
) {
3694 hlock
->references
--;
3695 if (hlock
->references
) {
3697 * We had, and after removing one, still have
3698 * references, the current lock stack is still
3699 * valid. We're done!
3706 * We have the right lock to unlock, 'hlock' points to it.
3707 * Now we remove it from the stack, and add back the other
3708 * entries (if any), recalculating the hash along the way:
3711 curr
->lockdep_depth
= i
;
3712 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3714 if (reacquire_held_locks(curr
, depth
, i
+ 1))
3718 * We had N bottles of beer on the wall, we drank one, but now
3719 * there's not N-1 bottles of beer left on the wall...
3721 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
3727 static int __lock_is_held(struct lockdep_map
*lock
, int read
)
3729 struct task_struct
*curr
= current
;
3732 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3733 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3735 if (match_held_lock(hlock
, lock
)) {
3736 if (read
== -1 || hlock
->read
== read
)
3746 static struct pin_cookie
__lock_pin_lock(struct lockdep_map
*lock
)
3748 struct pin_cookie cookie
= NIL_COOKIE
;
3749 struct task_struct
*curr
= current
;
3752 if (unlikely(!debug_locks
))
3755 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3756 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3758 if (match_held_lock(hlock
, lock
)) {
3760 * Grab 16bits of randomness; this is sufficient to not
3761 * be guessable and still allows some pin nesting in
3762 * our u32 pin_count.
3764 cookie
.val
= 1 + (prandom_u32() >> 16);
3765 hlock
->pin_count
+= cookie
.val
;
3770 WARN(1, "pinning an unheld lock\n");
3774 static void __lock_repin_lock(struct lockdep_map
*lock
, struct pin_cookie cookie
)
3776 struct task_struct
*curr
= current
;
3779 if (unlikely(!debug_locks
))
3782 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3783 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3785 if (match_held_lock(hlock
, lock
)) {
3786 hlock
->pin_count
+= cookie
.val
;
3791 WARN(1, "pinning an unheld lock\n");
3794 static void __lock_unpin_lock(struct lockdep_map
*lock
, struct pin_cookie cookie
)
3796 struct task_struct
*curr
= current
;
3799 if (unlikely(!debug_locks
))
3802 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3803 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3805 if (match_held_lock(hlock
, lock
)) {
3806 if (WARN(!hlock
->pin_count
, "unpinning an unpinned lock\n"))
3809 hlock
->pin_count
-= cookie
.val
;
3811 if (WARN((int)hlock
->pin_count
< 0, "pin count corrupted\n"))
3812 hlock
->pin_count
= 0;
3818 WARN(1, "unpinning an unheld lock\n");
3822 * Check whether we follow the irq-flags state precisely:
3824 static void check_flags(unsigned long flags
)
3826 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3827 defined(CONFIG_TRACE_IRQFLAGS)
3831 if (irqs_disabled_flags(flags
)) {
3832 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
3833 printk("possible reason: unannotated irqs-off.\n");
3836 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
3837 printk("possible reason: unannotated irqs-on.\n");
3842 * We dont accurately track softirq state in e.g.
3843 * hardirq contexts (such as on 4KSTACKS), so only
3844 * check if not in hardirq contexts:
3846 if (!hardirq_count()) {
3847 if (softirq_count()) {
3848 /* like the above, but with softirqs */
3849 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
3851 /* lick the above, does it taste good? */
3852 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
3857 print_irqtrace_events(current
);
3861 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
3862 struct lock_class_key
*key
, unsigned int subclass
,
3865 unsigned long flags
;
3867 if (unlikely(current
->lockdep_recursion
))
3870 raw_local_irq_save(flags
);
3871 current
->lockdep_recursion
= 1;
3873 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
3874 check_chain_key(current
);
3875 current
->lockdep_recursion
= 0;
3876 raw_local_irq_restore(flags
);
3878 EXPORT_SYMBOL_GPL(lock_set_class
);
3880 void lock_downgrade(struct lockdep_map
*lock
, unsigned long ip
)
3882 unsigned long flags
;
3884 if (unlikely(current
->lockdep_recursion
))
3887 raw_local_irq_save(flags
);
3888 current
->lockdep_recursion
= 1;
3890 if (__lock_downgrade(lock
, ip
))
3891 check_chain_key(current
);
3892 current
->lockdep_recursion
= 0;
3893 raw_local_irq_restore(flags
);
3895 EXPORT_SYMBOL_GPL(lock_downgrade
);
3898 * We are not always called with irqs disabled - do that here,
3899 * and also avoid lockdep recursion:
3901 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3902 int trylock
, int read
, int check
,
3903 struct lockdep_map
*nest_lock
, unsigned long ip
)
3905 unsigned long flags
;
3907 if (unlikely(current
->lockdep_recursion
))
3910 raw_local_irq_save(flags
);
3913 current
->lockdep_recursion
= 1;
3914 trace_lock_acquire(lock
, subclass
, trylock
, read
, check
, nest_lock
, ip
);
3915 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
3916 irqs_disabled_flags(flags
), nest_lock
, ip
, 0, 0);
3917 current
->lockdep_recursion
= 0;
3918 raw_local_irq_restore(flags
);
3920 EXPORT_SYMBOL_GPL(lock_acquire
);
3922 void lock_release(struct lockdep_map
*lock
, int nested
,
3925 unsigned long flags
;
3927 if (unlikely(current
->lockdep_recursion
))
3930 raw_local_irq_save(flags
);
3932 current
->lockdep_recursion
= 1;
3933 trace_lock_release(lock
, ip
);
3934 if (__lock_release(lock
, nested
, ip
))
3935 check_chain_key(current
);
3936 current
->lockdep_recursion
= 0;
3937 raw_local_irq_restore(flags
);
3939 EXPORT_SYMBOL_GPL(lock_release
);
3941 int lock_is_held_type(struct lockdep_map
*lock
, int read
)
3943 unsigned long flags
;
3946 if (unlikely(current
->lockdep_recursion
))
3947 return 1; /* avoid false negative lockdep_assert_held() */
3949 raw_local_irq_save(flags
);
3952 current
->lockdep_recursion
= 1;
3953 ret
= __lock_is_held(lock
, read
);
3954 current
->lockdep_recursion
= 0;
3955 raw_local_irq_restore(flags
);
3959 EXPORT_SYMBOL_GPL(lock_is_held_type
);
3961 struct pin_cookie
lock_pin_lock(struct lockdep_map
*lock
)
3963 struct pin_cookie cookie
= NIL_COOKIE
;
3964 unsigned long flags
;
3966 if (unlikely(current
->lockdep_recursion
))
3969 raw_local_irq_save(flags
);
3972 current
->lockdep_recursion
= 1;
3973 cookie
= __lock_pin_lock(lock
);
3974 current
->lockdep_recursion
= 0;
3975 raw_local_irq_restore(flags
);
3979 EXPORT_SYMBOL_GPL(lock_pin_lock
);
3981 void lock_repin_lock(struct lockdep_map
*lock
, struct pin_cookie cookie
)
3983 unsigned long flags
;
3985 if (unlikely(current
->lockdep_recursion
))
3988 raw_local_irq_save(flags
);
3991 current
->lockdep_recursion
= 1;
3992 __lock_repin_lock(lock
, cookie
);
3993 current
->lockdep_recursion
= 0;
3994 raw_local_irq_restore(flags
);
3996 EXPORT_SYMBOL_GPL(lock_repin_lock
);
3998 void lock_unpin_lock(struct lockdep_map
*lock
, struct pin_cookie cookie
)
4000 unsigned long flags
;
4002 if (unlikely(current
->lockdep_recursion
))
4005 raw_local_irq_save(flags
);
4008 current
->lockdep_recursion
= 1;
4009 __lock_unpin_lock(lock
, cookie
);
4010 current
->lockdep_recursion
= 0;
4011 raw_local_irq_restore(flags
);
4013 EXPORT_SYMBOL_GPL(lock_unpin_lock
);
4015 #ifdef CONFIG_LOCK_STAT
4017 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
4020 if (!debug_locks_off())
4022 if (debug_locks_silent
)
4026 pr_warn("=================================\n");
4027 pr_warn("WARNING: bad contention detected!\n");
4028 print_kernel_ident();
4029 pr_warn("---------------------------------\n");
4030 pr_warn("%s/%d is trying to contend lock (",
4031 curr
->comm
, task_pid_nr(curr
));
4032 print_lockdep_cache(lock
);
4035 pr_warn("but there are no locks held!\n");
4036 pr_warn("\nother info that might help us debug this:\n");
4037 lockdep_print_held_locks(curr
);
4039 pr_warn("\nstack backtrace:\n");
4046 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
4048 struct task_struct
*curr
= current
;
4049 struct held_lock
*hlock
;
4050 struct lock_class_stats
*stats
;
4052 int i
, contention_point
, contending_point
;
4054 depth
= curr
->lockdep_depth
;
4056 * Whee, we contended on this lock, except it seems we're not
4057 * actually trying to acquire anything much at all..
4059 if (DEBUG_LOCKS_WARN_ON(!depth
))
4062 hlock
= find_held_lock(curr
, lock
, depth
, &i
);
4064 print_lock_contention_bug(curr
, lock
, ip
);
4068 if (hlock
->instance
!= lock
)
4071 hlock
->waittime_stamp
= lockstat_clock();
4073 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
4074 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
4077 stats
= get_lock_stats(hlock_class(hlock
));
4078 if (contention_point
< LOCKSTAT_POINTS
)
4079 stats
->contention_point
[contention_point
]++;
4080 if (contending_point
< LOCKSTAT_POINTS
)
4081 stats
->contending_point
[contending_point
]++;
4082 if (lock
->cpu
!= smp_processor_id())
4083 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
4084 put_lock_stats(stats
);
4088 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
4090 struct task_struct
*curr
= current
;
4091 struct held_lock
*hlock
;
4092 struct lock_class_stats
*stats
;
4094 u64 now
, waittime
= 0;
4097 depth
= curr
->lockdep_depth
;
4099 * Yay, we acquired ownership of this lock we didn't try to
4100 * acquire, how the heck did that happen?
4102 if (DEBUG_LOCKS_WARN_ON(!depth
))
4105 hlock
= find_held_lock(curr
, lock
, depth
, &i
);
4107 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
4111 if (hlock
->instance
!= lock
)
4114 cpu
= smp_processor_id();
4115 if (hlock
->waittime_stamp
) {
4116 now
= lockstat_clock();
4117 waittime
= now
- hlock
->waittime_stamp
;
4118 hlock
->holdtime_stamp
= now
;
4121 trace_lock_acquired(lock
, ip
);
4123 stats
= get_lock_stats(hlock_class(hlock
));
4126 lock_time_inc(&stats
->read_waittime
, waittime
);
4128 lock_time_inc(&stats
->write_waittime
, waittime
);
4130 if (lock
->cpu
!= cpu
)
4131 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
4132 put_lock_stats(stats
);
4138 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
4140 unsigned long flags
;
4142 if (unlikely(!lock_stat
))
4145 if (unlikely(current
->lockdep_recursion
))
4148 raw_local_irq_save(flags
);
4150 current
->lockdep_recursion
= 1;
4151 trace_lock_contended(lock
, ip
);
4152 __lock_contended(lock
, ip
);
4153 current
->lockdep_recursion
= 0;
4154 raw_local_irq_restore(flags
);
4156 EXPORT_SYMBOL_GPL(lock_contended
);
4158 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
4160 unsigned long flags
;
4162 if (unlikely(!lock_stat
))
4165 if (unlikely(current
->lockdep_recursion
))
4168 raw_local_irq_save(flags
);
4170 current
->lockdep_recursion
= 1;
4171 __lock_acquired(lock
, ip
);
4172 current
->lockdep_recursion
= 0;
4173 raw_local_irq_restore(flags
);
4175 EXPORT_SYMBOL_GPL(lock_acquired
);
4179 * Used by the testsuite, sanitize the validator state
4180 * after a simulated failure:
4183 void lockdep_reset(void)
4185 unsigned long flags
;
4188 raw_local_irq_save(flags
);
4189 current
->curr_chain_key
= 0;
4190 current
->lockdep_depth
= 0;
4191 current
->lockdep_recursion
= 0;
4192 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
4193 nr_hardirq_chains
= 0;
4194 nr_softirq_chains
= 0;
4195 nr_process_chains
= 0;
4197 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
4198 INIT_HLIST_HEAD(chainhash_table
+ i
);
4199 raw_local_irq_restore(flags
);
4202 static void zap_class(struct lock_class
*class)
4207 * Remove all dependencies this lock is
4210 for (i
= 0; i
< nr_list_entries
; i
++) {
4211 if (list_entries
[i
].class == class)
4212 list_del_rcu(&list_entries
[i
].entry
);
4215 * Unhash the class and remove it from the all_lock_classes list:
4217 hlist_del_rcu(&class->hash_entry
);
4218 list_del_rcu(&class->lock_entry
);
4220 RCU_INIT_POINTER(class->key
, NULL
);
4221 RCU_INIT_POINTER(class->name
, NULL
);
4224 static inline int within(const void *addr
, void *start
, unsigned long size
)
4226 return addr
>= start
&& addr
< start
+ size
;
4230 * Used in module.c to remove lock classes from memory that is going to be
4231 * freed; and possibly re-used by other modules.
4233 * We will have had one sync_sched() before getting here, so we're guaranteed
4234 * nobody will look up these exact classes -- they're properly dead but still
4237 void lockdep_free_key_range(void *start
, unsigned long size
)
4239 struct lock_class
*class;
4240 struct hlist_head
*head
;
4241 unsigned long flags
;
4245 raw_local_irq_save(flags
);
4246 locked
= graph_lock();
4249 * Unhash all classes that were created by this module:
4251 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
4252 head
= classhash_table
+ i
;
4253 hlist_for_each_entry_rcu(class, head
, hash_entry
) {
4254 if (within(class->key
, start
, size
))
4256 else if (within(class->name
, start
, size
))
4263 raw_local_irq_restore(flags
);
4266 * Wait for any possible iterators from look_up_lock_class() to pass
4267 * before continuing to free the memory they refer to.
4269 * sync_sched() is sufficient because the read-side is IRQ disable.
4271 synchronize_sched();
4274 * XXX at this point we could return the resources to the pool;
4275 * instead we leak them. We would need to change to bitmap allocators
4276 * instead of the linear allocators we have now.
4280 void lockdep_reset_lock(struct lockdep_map
*lock
)
4282 struct lock_class
*class;
4283 struct hlist_head
*head
;
4284 unsigned long flags
;
4288 raw_local_irq_save(flags
);
4291 * Remove all classes this lock might have:
4293 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
4295 * If the class exists we look it up and zap it:
4297 class = look_up_lock_class(lock
, j
);
4298 if (!IS_ERR_OR_NULL(class))
4302 * Debug check: in the end all mapped classes should
4305 locked
= graph_lock();
4306 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
4307 head
= classhash_table
+ i
;
4308 hlist_for_each_entry_rcu(class, head
, hash_entry
) {
4311 for (j
= 0; j
< NR_LOCKDEP_CACHING_CLASSES
; j
++)
4312 match
|= class == lock
->class_cache
[j
];
4314 if (unlikely(match
)) {
4315 if (debug_locks_off_graph_unlock()) {
4317 * We all just reset everything, how did it match?
4329 raw_local_irq_restore(flags
);
4332 void __init
lockdep_info(void)
4334 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4336 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
4337 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
4338 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
4339 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
4340 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
4341 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
4342 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
4344 printk(" memory used by lock dependency info: %lu kB\n",
4345 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
4346 sizeof(struct list_head
) * CLASSHASH_SIZE
+
4347 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
4348 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
4349 sizeof(struct list_head
) * CHAINHASH_SIZE
4350 #ifdef CONFIG_PROVE_LOCKING
4351 + sizeof(struct circular_queue
)
4356 printk(" per task-struct memory footprint: %lu bytes\n",
4357 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
4361 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
4362 const void *mem_to
, struct held_lock
*hlock
)
4364 if (!debug_locks_off())
4366 if (debug_locks_silent
)
4370 pr_warn("=========================\n");
4371 pr_warn("WARNING: held lock freed!\n");
4372 print_kernel_ident();
4373 pr_warn("-------------------------\n");
4374 pr_warn("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4375 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
4377 lockdep_print_held_locks(curr
);
4379 pr_warn("\nstack backtrace:\n");
4383 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
4384 const void* lock_from
, unsigned long lock_len
)
4386 return lock_from
+ lock_len
<= mem_from
||
4387 mem_from
+ mem_len
<= lock_from
;
4391 * Called when kernel memory is freed (or unmapped), or if a lock
4392 * is destroyed or reinitialized - this code checks whether there is
4393 * any held lock in the memory range of <from> to <to>:
4395 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
4397 struct task_struct
*curr
= current
;
4398 struct held_lock
*hlock
;
4399 unsigned long flags
;
4402 if (unlikely(!debug_locks
))
4405 local_irq_save(flags
);
4406 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
4407 hlock
= curr
->held_locks
+ i
;
4409 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
4410 sizeof(*hlock
->instance
)))
4413 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
4416 local_irq_restore(flags
);
4418 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
4420 static void print_held_locks_bug(void)
4422 if (!debug_locks_off())
4424 if (debug_locks_silent
)
4428 pr_warn("====================================\n");
4429 pr_warn("WARNING: %s/%d still has locks held!\n",
4430 current
->comm
, task_pid_nr(current
));
4431 print_kernel_ident();
4432 pr_warn("------------------------------------\n");
4433 lockdep_print_held_locks(current
);
4434 pr_warn("\nstack backtrace:\n");
4438 void debug_check_no_locks_held(void)
4440 if (unlikely(current
->lockdep_depth
> 0))
4441 print_held_locks_bug();
4443 EXPORT_SYMBOL_GPL(debug_check_no_locks_held
);
4446 void debug_show_all_locks(void)
4448 struct task_struct
*g
, *p
;
4452 if (unlikely(!debug_locks
)) {
4453 pr_warn("INFO: lockdep is turned off.\n");
4456 pr_warn("\nShowing all locks held in the system:\n");
4459 * Here we try to get the tasklist_lock as hard as possible,
4460 * if not successful after 2 seconds we ignore it (but keep
4461 * trying). This is to enable a debug printout even if a
4462 * tasklist_lock-holding task deadlocks or crashes.
4465 if (!read_trylock(&tasklist_lock
)) {
4467 pr_warn("hm, tasklist_lock locked, retrying... ");
4470 pr_cont(" #%d", 10-count
);
4474 pr_cont(" ignoring it.\n");
4478 pr_cont(" locked it.\n");
4481 do_each_thread(g
, p
) {
4483 * It's not reliable to print a task's held locks
4484 * if it's not sleeping (or if it's not the current
4487 if (p
->state
== TASK_RUNNING
&& p
!= current
)
4489 if (p
->lockdep_depth
)
4490 lockdep_print_held_locks(p
);
4492 if (read_trylock(&tasklist_lock
))
4494 touch_nmi_watchdog();
4495 } while_each_thread(g
, p
);
4498 pr_warn("=============================================\n\n");
4501 read_unlock(&tasklist_lock
);
4503 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
4507 * Careful: only use this function if you are sure that
4508 * the task cannot run in parallel!
4510 void debug_show_held_locks(struct task_struct
*task
)
4512 if (unlikely(!debug_locks
)) {
4513 printk("INFO: lockdep is turned off.\n");
4516 lockdep_print_held_locks(task
);
4518 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
4520 asmlinkage __visible
void lockdep_sys_exit(void)
4522 struct task_struct
*curr
= current
;
4524 if (unlikely(curr
->lockdep_depth
)) {
4525 if (!debug_locks_off())
4528 pr_warn("================================================\n");
4529 pr_warn("WARNING: lock held when returning to user space!\n");
4530 print_kernel_ident();
4531 pr_warn("------------------------------------------------\n");
4532 pr_warn("%s/%d is leaving the kernel with locks still held!\n",
4533 curr
->comm
, curr
->pid
);
4534 lockdep_print_held_locks(curr
);
4538 * The lock history for each syscall should be independent. So wipe the
4539 * slate clean on return to userspace.
4541 lockdep_invariant_state(false);
4544 void lockdep_rcu_suspicious(const char *file
, const int line
, const char *s
)
4546 struct task_struct
*curr
= current
;
4548 /* Note: the following can be executed concurrently, so be careful. */
4550 pr_warn("=============================\n");
4551 pr_warn("WARNING: suspicious RCU usage\n");
4552 print_kernel_ident();
4553 pr_warn("-----------------------------\n");
4554 pr_warn("%s:%d %s!\n", file
, line
, s
);
4555 pr_warn("\nother info that might help us debug this:\n\n");
4556 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4557 !rcu_lockdep_current_cpu_online()
4558 ? "RCU used illegally from offline CPU!\n"
4559 : !rcu_is_watching()
4560 ? "RCU used illegally from idle CPU!\n"
4562 rcu_scheduler_active
, debug_locks
);
4565 * If a CPU is in the RCU-free window in idle (ie: in the section
4566 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4567 * considers that CPU to be in an "extended quiescent state",
4568 * which means that RCU will be completely ignoring that CPU.
4569 * Therefore, rcu_read_lock() and friends have absolutely no
4570 * effect on a CPU running in that state. In other words, even if
4571 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4572 * delete data structures out from under it. RCU really has no
4573 * choice here: we need to keep an RCU-free window in idle where
4574 * the CPU may possibly enter into low power mode. This way we can
4575 * notice an extended quiescent state to other CPUs that started a grace
4576 * period. Otherwise we would delay any grace period as long as we run
4579 * So complain bitterly if someone does call rcu_read_lock(),
4580 * rcu_read_lock_bh() and so on from extended quiescent states.
4582 if (!rcu_is_watching())
4583 pr_warn("RCU used illegally from extended quiescent state!\n");
4585 lockdep_print_held_locks(curr
);
4586 pr_warn("\nstack backtrace:\n");
4589 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious
);