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 &this_cpu_ptr(cpu_lock_stats
)[class - lock_classes
];
254 static void lock_release_holdtime(struct held_lock
*hlock
)
256 struct lock_class_stats
*stats
;
262 holdtime
= lockstat_clock() - hlock
->holdtime_stamp
;
264 stats
= get_lock_stats(hlock_class(hlock
));
266 lock_time_inc(&stats
->read_holdtime
, holdtime
);
268 lock_time_inc(&stats
->write_holdtime
, holdtime
);
271 static inline void lock_release_holdtime(struct held_lock
*hlock
)
277 * We keep a global list of all lock classes. The list only grows,
278 * never shrinks. The list is only accessed with the lockdep
279 * spinlock lock held.
281 LIST_HEAD(all_lock_classes
);
284 * The lockdep classes are in a hash-table as well, for fast lookup:
286 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
287 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
288 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
289 #define classhashentry(key) (classhash_table + __classhashfn((key)))
291 static struct hlist_head classhash_table
[CLASSHASH_SIZE
];
294 * We put the lock dependency chains into a hash-table as well, to cache
297 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
298 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
299 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
300 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
302 static struct hlist_head chainhash_table
[CHAINHASH_SIZE
];
305 * The hash key of the lock dependency chains is a hash itself too:
306 * it's a hash of all locks taken up to that lock, including that lock.
307 * It's a 64-bit hash, because it's important for the keys to be
310 static inline u64
iterate_chain_key(u64 key
, u32 idx
)
312 u32 k0
= key
, k1
= key
>> 32;
314 __jhash_mix(idx
, k0
, k1
); /* Macro that modifies arguments! */
316 return k0
| (u64
)k1
<< 32;
319 void lockdep_off(void)
321 current
->lockdep_recursion
++;
323 EXPORT_SYMBOL(lockdep_off
);
325 void lockdep_on(void)
327 current
->lockdep_recursion
--;
329 EXPORT_SYMBOL(lockdep_on
);
332 * Debugging switches:
336 #define VERY_VERBOSE 0
339 # define HARDIRQ_VERBOSE 1
340 # define SOFTIRQ_VERBOSE 1
342 # define HARDIRQ_VERBOSE 0
343 # define SOFTIRQ_VERBOSE 0
346 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
348 * Quick filtering for interesting events:
350 static int class_filter(struct lock_class
*class)
354 if (class->name_version
== 1 &&
355 !strcmp(class->name
, "lockname"))
357 if (class->name_version
== 1 &&
358 !strcmp(class->name
, "&struct->lockfield"))
361 /* Filter everything else. 1 would be to allow everything else */
366 static int verbose(struct lock_class
*class)
369 return class_filter(class);
375 * Stack-trace: tightly packed array of stack backtrace
376 * addresses. Protected by the graph_lock.
378 unsigned long nr_stack_trace_entries
;
379 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
381 static void print_lockdep_off(const char *bug_msg
)
383 printk(KERN_DEBUG
"%s\n", bug_msg
);
384 printk(KERN_DEBUG
"turning off the locking correctness validator.\n");
385 #ifdef CONFIG_LOCK_STAT
386 printk(KERN_DEBUG
"Please attach the output of /proc/lock_stat to the bug report\n");
390 static int save_trace(struct stack_trace
*trace
)
392 trace
->nr_entries
= 0;
393 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
394 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
398 save_stack_trace(trace
);
401 * Some daft arches put -1 at the end to indicate its a full trace.
403 * <rant> this is buggy anyway, since it takes a whole extra entry so a
404 * complete trace that maxes out the entries provided will be reported
405 * as incomplete, friggin useless </rant>
407 if (trace
->nr_entries
!= 0 &&
408 trace
->entries
[trace
->nr_entries
-1] == ULONG_MAX
)
411 trace
->max_entries
= trace
->nr_entries
;
413 nr_stack_trace_entries
+= trace
->nr_entries
;
415 if (nr_stack_trace_entries
>= MAX_STACK_TRACE_ENTRIES
-1) {
416 if (!debug_locks_off_graph_unlock())
419 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
428 unsigned int nr_hardirq_chains
;
429 unsigned int nr_softirq_chains
;
430 unsigned int nr_process_chains
;
431 unsigned int max_lockdep_depth
;
433 #ifdef CONFIG_DEBUG_LOCKDEP
435 * Various lockdep statistics:
437 DEFINE_PER_CPU(struct lockdep_stats
, lockdep_stats
);
444 #define __USAGE(__STATE) \
445 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
446 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
447 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
448 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
450 static const char *usage_str
[] =
452 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
453 #include "lockdep_states.h"
455 [LOCK_USED
] = "INITIAL USE",
458 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
460 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
463 static inline unsigned long lock_flag(enum lock_usage_bit bit
)
468 static char get_usage_char(struct lock_class
*class, enum lock_usage_bit bit
)
472 if (class->usage_mask
& lock_flag(bit
+ 2))
474 if (class->usage_mask
& lock_flag(bit
)) {
476 if (class->usage_mask
& lock_flag(bit
+ 2))
483 void get_usage_chars(struct lock_class
*class, char usage
[LOCK_USAGE_CHARS
])
487 #define LOCKDEP_STATE(__STATE) \
488 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
489 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
490 #include "lockdep_states.h"
496 static void __print_lock_name(struct lock_class
*class)
498 char str
[KSYM_NAME_LEN
];
503 name
= __get_key_name(class->key
, str
);
504 printk(KERN_CONT
"%s", name
);
506 printk(KERN_CONT
"%s", name
);
507 if (class->name_version
> 1)
508 printk(KERN_CONT
"#%d", class->name_version
);
510 printk(KERN_CONT
"/%d", class->subclass
);
514 static void print_lock_name(struct lock_class
*class)
516 char usage
[LOCK_USAGE_CHARS
];
518 get_usage_chars(class, usage
);
520 printk(KERN_CONT
" (");
521 __print_lock_name(class);
522 printk(KERN_CONT
"){%s}", usage
);
525 static void print_lockdep_cache(struct lockdep_map
*lock
)
528 char str
[KSYM_NAME_LEN
];
532 name
= __get_key_name(lock
->key
->subkeys
, str
);
534 printk(KERN_CONT
"%s", name
);
537 static void print_lock(struct held_lock
*hlock
)
540 * We can be called locklessly through debug_show_all_locks() so be
541 * extra careful, the hlock might have been released and cleared.
543 unsigned int class_idx
= hlock
->class_idx
;
545 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
548 if (!class_idx
|| (class_idx
- 1) >= MAX_LOCKDEP_KEYS
) {
549 printk(KERN_CONT
"<RELEASED>\n");
553 printk(KERN_CONT
"%p", hlock
->instance
);
554 print_lock_name(lock_classes
+ class_idx
- 1);
555 printk(KERN_CONT
", at: %pS\n", (void *)hlock
->acquire_ip
);
558 static void lockdep_print_held_locks(struct task_struct
*p
)
560 int i
, depth
= READ_ONCE(p
->lockdep_depth
);
563 printk("no locks held by %s/%d.\n", p
->comm
, task_pid_nr(p
));
565 printk("%d lock%s held by %s/%d:\n", depth
,
566 depth
> 1 ? "s" : "", p
->comm
, task_pid_nr(p
));
568 * It's not reliable to print a task's held locks if it's not sleeping
569 * and it's not the current task.
571 if (p
->state
== TASK_RUNNING
&& p
!= current
)
573 for (i
= 0; i
< depth
; i
++) {
575 print_lock(p
->held_locks
+ i
);
579 static void print_kernel_ident(void)
581 printk("%s %.*s %s\n", init_utsname()->release
,
582 (int)strcspn(init_utsname()->version
, " "),
583 init_utsname()->version
,
587 static int very_verbose(struct lock_class
*class)
590 return class_filter(class);
596 * Is this the address of a static object:
599 static int static_obj(void *obj
)
601 unsigned long start
= (unsigned long) &_stext
,
602 end
= (unsigned long) &_end
,
603 addr
= (unsigned long) obj
;
608 if ((addr
>= start
) && (addr
< end
))
611 if (arch_is_kernel_data(addr
))
615 * in-kernel percpu var?
617 if (is_kernel_percpu_address(addr
))
621 * module static or percpu var?
623 return is_module_address(addr
) || is_module_percpu_address(addr
);
628 * To make lock name printouts unique, we calculate a unique
629 * class->name_version generation counter:
631 static int count_matching_names(struct lock_class
*new_class
)
633 struct lock_class
*class;
636 if (!new_class
->name
)
639 list_for_each_entry_rcu(class, &all_lock_classes
, lock_entry
) {
640 if (new_class
->key
- new_class
->subclass
== class->key
)
641 return class->name_version
;
642 if (class->name
&& !strcmp(class->name
, new_class
->name
))
643 count
= max(count
, class->name_version
);
649 static inline struct lock_class
*
650 look_up_lock_class(const struct lockdep_map
*lock
, unsigned int subclass
)
652 struct lockdep_subclass_key
*key
;
653 struct hlist_head
*hash_head
;
654 struct lock_class
*class;
656 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
659 "BUG: looking up invalid subclass: %u\n", subclass
);
661 "turning off the locking correctness validator.\n");
667 * If it is not initialised then it has never been locked,
668 * so it won't be present in the hash table.
670 if (unlikely(!lock
->key
))
674 * NOTE: the class-key must be unique. For dynamic locks, a static
675 * lock_class_key variable is passed in through the mutex_init()
676 * (or spin_lock_init()) call - which acts as the key. For static
677 * locks we use the lock object itself as the key.
679 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
680 sizeof(struct lockdep_map
));
682 key
= lock
->key
->subkeys
+ subclass
;
684 hash_head
= classhashentry(key
);
687 * We do an RCU walk of the hash, see lockdep_free_key_range().
689 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
692 hlist_for_each_entry_rcu(class, hash_head
, hash_entry
) {
693 if (class->key
== key
) {
695 * Huh! same key, different name? Did someone trample
696 * on some memory? We're most confused.
698 WARN_ON_ONCE(class->name
!= lock
->name
);
707 * Static locks do not have their class-keys yet - for them the key is
708 * the lock object itself. If the lock is in the per cpu area, the
709 * canonical address of the lock (per cpu offset removed) is used.
711 static bool assign_lock_key(struct lockdep_map
*lock
)
713 unsigned long can_addr
, addr
= (unsigned long)lock
;
715 if (__is_kernel_percpu_address(addr
, &can_addr
))
716 lock
->key
= (void *)can_addr
;
717 else if (__is_module_percpu_address(addr
, &can_addr
))
718 lock
->key
= (void *)can_addr
;
719 else if (static_obj(lock
))
720 lock
->key
= (void *)lock
;
722 /* Debug-check: all keys must be persistent! */
724 pr_err("INFO: trying to register non-static key.\n");
725 pr_err("the code is fine but needs lockdep annotation.\n");
726 pr_err("turning off the locking correctness validator.\n");
735 * Register a lock's class in the hash-table, if the class is not present
736 * yet. Otherwise we look it up. We cache the result in the lock object
737 * itself, so actual lookup of the hash should be once per lock object.
739 static struct lock_class
*
740 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
742 struct lockdep_subclass_key
*key
;
743 struct hlist_head
*hash_head
;
744 struct lock_class
*class;
746 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
748 class = look_up_lock_class(lock
, subclass
);
750 goto out_set_class_cache
;
753 if (!assign_lock_key(lock
))
755 } else if (!static_obj(lock
->key
)) {
759 key
= lock
->key
->subkeys
+ subclass
;
760 hash_head
= classhashentry(key
);
766 * We have to do the hash-walk again, to avoid races
769 hlist_for_each_entry_rcu(class, hash_head
, hash_entry
) {
770 if (class->key
== key
)
775 * Allocate a new key from the static array, and add it to
778 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
779 if (!debug_locks_off_graph_unlock()) {
783 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
787 class = lock_classes
+ nr_lock_classes
++;
788 debug_atomic_inc(nr_unused_locks
);
790 class->name
= lock
->name
;
791 class->subclass
= subclass
;
792 INIT_LIST_HEAD(&class->lock_entry
);
793 INIT_LIST_HEAD(&class->locks_before
);
794 INIT_LIST_HEAD(&class->locks_after
);
795 class->name_version
= count_matching_names(class);
797 * We use RCU's safe list-add method to make
798 * parallel walking of the hash-list safe:
800 hlist_add_head_rcu(&class->hash_entry
, hash_head
);
802 * Add it to the global list of classes:
804 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
806 if (verbose(class)) {
809 printk("\nnew class %px: %s", class->key
, class->name
);
810 if (class->name_version
> 1)
811 printk(KERN_CONT
"#%d", class->name_version
);
812 printk(KERN_CONT
"\n");
823 if (!subclass
|| force
)
824 lock
->class_cache
[0] = class;
825 else if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
826 lock
->class_cache
[subclass
] = class;
829 * Hash collision, did we smoke some? We found a class with a matching
830 * hash but the subclass -- which is hashed in -- didn't match.
832 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
838 #ifdef CONFIG_PROVE_LOCKING
840 * Allocate a lockdep entry. (assumes the graph_lock held, returns
841 * with NULL on failure)
843 static struct lock_list
*alloc_list_entry(void)
845 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
846 if (!debug_locks_off_graph_unlock())
849 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
853 return list_entries
+ nr_list_entries
++;
857 * Add a new dependency to the head of the list:
859 static int add_lock_to_list(struct lock_class
*this, struct list_head
*head
,
860 unsigned long ip
, int distance
,
861 struct stack_trace
*trace
)
863 struct lock_list
*entry
;
865 * Lock not present yet - get a new dependency struct and
866 * add it to the list:
868 entry
= alloc_list_entry();
873 entry
->distance
= distance
;
874 entry
->trace
= *trace
;
876 * Both allocation and removal are done under the graph lock; but
877 * iteration is under RCU-sched; see look_up_lock_class() and
878 * lockdep_free_key_range().
880 list_add_tail_rcu(&entry
->entry
, head
);
886 * For good efficiency of modular, we use power of 2
888 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
889 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
892 * The circular_queue and helpers is used to implement the
893 * breadth-first search(BFS)algorithem, by which we can build
894 * the shortest path from the next lock to be acquired to the
895 * previous held lock if there is a circular between them.
897 struct circular_queue
{
898 unsigned long element
[MAX_CIRCULAR_QUEUE_SIZE
];
899 unsigned int front
, rear
;
902 static struct circular_queue lock_cq
;
904 unsigned int max_bfs_queue_depth
;
906 static unsigned int lockdep_dependency_gen_id
;
908 static inline void __cq_init(struct circular_queue
*cq
)
910 cq
->front
= cq
->rear
= 0;
911 lockdep_dependency_gen_id
++;
914 static inline int __cq_empty(struct circular_queue
*cq
)
916 return (cq
->front
== cq
->rear
);
919 static inline int __cq_full(struct circular_queue
*cq
)
921 return ((cq
->rear
+ 1) & CQ_MASK
) == cq
->front
;
924 static inline int __cq_enqueue(struct circular_queue
*cq
, unsigned long elem
)
929 cq
->element
[cq
->rear
] = elem
;
930 cq
->rear
= (cq
->rear
+ 1) & CQ_MASK
;
934 static inline int __cq_dequeue(struct circular_queue
*cq
, unsigned long *elem
)
939 *elem
= cq
->element
[cq
->front
];
940 cq
->front
= (cq
->front
+ 1) & CQ_MASK
;
944 static inline unsigned int __cq_get_elem_count(struct circular_queue
*cq
)
946 return (cq
->rear
- cq
->front
) & CQ_MASK
;
949 static inline void mark_lock_accessed(struct lock_list
*lock
,
950 struct lock_list
*parent
)
954 nr
= lock
- list_entries
;
955 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
956 lock
->parent
= parent
;
957 lock
->class->dep_gen_id
= lockdep_dependency_gen_id
;
960 static inline unsigned long lock_accessed(struct lock_list
*lock
)
964 nr
= lock
- list_entries
;
965 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
966 return lock
->class->dep_gen_id
== lockdep_dependency_gen_id
;
969 static inline struct lock_list
*get_lock_parent(struct lock_list
*child
)
971 return child
->parent
;
974 static inline int get_lock_depth(struct lock_list
*child
)
977 struct lock_list
*parent
;
979 while ((parent
= get_lock_parent(child
))) {
986 static int __bfs(struct lock_list
*source_entry
,
988 int (*match
)(struct lock_list
*entry
, void *data
),
989 struct lock_list
**target_entry
,
992 struct lock_list
*entry
;
993 struct list_head
*head
;
994 struct circular_queue
*cq
= &lock_cq
;
997 if (match(source_entry
, data
)) {
998 *target_entry
= source_entry
;
1004 head
= &source_entry
->class->locks_after
;
1006 head
= &source_entry
->class->locks_before
;
1008 if (list_empty(head
))
1012 __cq_enqueue(cq
, (unsigned long)source_entry
);
1014 while (!__cq_empty(cq
)) {
1015 struct lock_list
*lock
;
1017 __cq_dequeue(cq
, (unsigned long *)&lock
);
1025 head
= &lock
->class->locks_after
;
1027 head
= &lock
->class->locks_before
;
1029 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1031 list_for_each_entry_rcu(entry
, head
, entry
) {
1032 if (!lock_accessed(entry
)) {
1033 unsigned int cq_depth
;
1034 mark_lock_accessed(entry
, lock
);
1035 if (match(entry
, data
)) {
1036 *target_entry
= entry
;
1041 if (__cq_enqueue(cq
, (unsigned long)entry
)) {
1045 cq_depth
= __cq_get_elem_count(cq
);
1046 if (max_bfs_queue_depth
< cq_depth
)
1047 max_bfs_queue_depth
= cq_depth
;
1055 static inline int __bfs_forwards(struct lock_list
*src_entry
,
1057 int (*match
)(struct lock_list
*entry
, void *data
),
1058 struct lock_list
**target_entry
)
1060 return __bfs(src_entry
, data
, match
, target_entry
, 1);
1064 static inline int __bfs_backwards(struct lock_list
*src_entry
,
1066 int (*match
)(struct lock_list
*entry
, void *data
),
1067 struct lock_list
**target_entry
)
1069 return __bfs(src_entry
, data
, match
, target_entry
, 0);
1074 * Recursive, forwards-direction lock-dependency checking, used for
1075 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1080 * Print a dependency chain entry (this is only done when a deadlock
1081 * has been detected):
1084 print_circular_bug_entry(struct lock_list
*target
, int depth
)
1086 if (debug_locks_silent
)
1088 printk("\n-> #%u", depth
);
1089 print_lock_name(target
->class);
1090 printk(KERN_CONT
":\n");
1091 print_stack_trace(&target
->trace
, 6);
1097 print_circular_lock_scenario(struct held_lock
*src
,
1098 struct held_lock
*tgt
,
1099 struct lock_list
*prt
)
1101 struct lock_class
*source
= hlock_class(src
);
1102 struct lock_class
*target
= hlock_class(tgt
);
1103 struct lock_class
*parent
= prt
->class;
1106 * A direct locking problem where unsafe_class lock is taken
1107 * directly by safe_class lock, then all we need to show
1108 * is the deadlock scenario, as it is obvious that the
1109 * unsafe lock is taken under the safe lock.
1111 * But if there is a chain instead, where the safe lock takes
1112 * an intermediate lock (middle_class) where this lock is
1113 * not the same as the safe lock, then the lock chain is
1114 * used to describe the problem. Otherwise we would need
1115 * to show a different CPU case for each link in the chain
1116 * from the safe_class lock to the unsafe_class lock.
1118 if (parent
!= source
) {
1119 printk("Chain exists of:\n ");
1120 __print_lock_name(source
);
1121 printk(KERN_CONT
" --> ");
1122 __print_lock_name(parent
);
1123 printk(KERN_CONT
" --> ");
1124 __print_lock_name(target
);
1125 printk(KERN_CONT
"\n\n");
1128 printk(" Possible unsafe locking scenario:\n\n");
1129 printk(" CPU0 CPU1\n");
1130 printk(" ---- ----\n");
1132 __print_lock_name(target
);
1133 printk(KERN_CONT
");\n");
1135 __print_lock_name(parent
);
1136 printk(KERN_CONT
");\n");
1138 __print_lock_name(target
);
1139 printk(KERN_CONT
");\n");
1141 __print_lock_name(source
);
1142 printk(KERN_CONT
");\n");
1143 printk("\n *** DEADLOCK ***\n\n");
1147 * When a circular dependency is detected, print the
1151 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
,
1152 struct held_lock
*check_src
,
1153 struct held_lock
*check_tgt
)
1155 struct task_struct
*curr
= current
;
1157 if (debug_locks_silent
)
1161 pr_warn("======================================================\n");
1162 pr_warn("WARNING: possible circular locking dependency detected\n");
1163 print_kernel_ident();
1164 pr_warn("------------------------------------------------------\n");
1165 pr_warn("%s/%d is trying to acquire lock:\n",
1166 curr
->comm
, task_pid_nr(curr
));
1167 print_lock(check_src
);
1169 pr_warn("\nbut task is already holding lock:\n");
1171 print_lock(check_tgt
);
1172 pr_warn("\nwhich lock already depends on the new lock.\n\n");
1173 pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1175 print_circular_bug_entry(entry
, depth
);
1180 static inline int class_equal(struct lock_list
*entry
, void *data
)
1182 return entry
->class == data
;
1185 static noinline
int print_circular_bug(struct lock_list
*this,
1186 struct lock_list
*target
,
1187 struct held_lock
*check_src
,
1188 struct held_lock
*check_tgt
,
1189 struct stack_trace
*trace
)
1191 struct task_struct
*curr
= current
;
1192 struct lock_list
*parent
;
1193 struct lock_list
*first_parent
;
1196 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1199 if (!save_trace(&this->trace
))
1202 depth
= get_lock_depth(target
);
1204 print_circular_bug_header(target
, depth
, check_src
, check_tgt
);
1206 parent
= get_lock_parent(target
);
1207 first_parent
= parent
;
1210 print_circular_bug_entry(parent
, --depth
);
1211 parent
= get_lock_parent(parent
);
1214 printk("\nother info that might help us debug this:\n\n");
1215 print_circular_lock_scenario(check_src
, check_tgt
,
1218 lockdep_print_held_locks(curr
);
1220 printk("\nstack backtrace:\n");
1226 static noinline
int print_bfs_bug(int ret
)
1228 if (!debug_locks_off_graph_unlock())
1232 * Breadth-first-search failed, graph got corrupted?
1234 WARN(1, "lockdep bfs error:%d\n", ret
);
1239 static int noop_count(struct lock_list
*entry
, void *data
)
1241 (*(unsigned long *)data
)++;
1245 static unsigned long __lockdep_count_forward_deps(struct lock_list
*this)
1247 unsigned long count
= 0;
1248 struct lock_list
*uninitialized_var(target_entry
);
1250 __bfs_forwards(this, (void *)&count
, noop_count
, &target_entry
);
1254 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1256 unsigned long ret
, flags
;
1257 struct lock_list
this;
1262 raw_local_irq_save(flags
);
1263 arch_spin_lock(&lockdep_lock
);
1264 ret
= __lockdep_count_forward_deps(&this);
1265 arch_spin_unlock(&lockdep_lock
);
1266 raw_local_irq_restore(flags
);
1271 static unsigned long __lockdep_count_backward_deps(struct lock_list
*this)
1273 unsigned long count
= 0;
1274 struct lock_list
*uninitialized_var(target_entry
);
1276 __bfs_backwards(this, (void *)&count
, noop_count
, &target_entry
);
1281 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1283 unsigned long ret
, flags
;
1284 struct lock_list
this;
1289 raw_local_irq_save(flags
);
1290 arch_spin_lock(&lockdep_lock
);
1291 ret
= __lockdep_count_backward_deps(&this);
1292 arch_spin_unlock(&lockdep_lock
);
1293 raw_local_irq_restore(flags
);
1299 * Prove that the dependency graph starting at <entry> can not
1300 * lead to <target>. Print an error and return 0 if it does.
1303 check_noncircular(struct lock_list
*root
, struct lock_class
*target
,
1304 struct lock_list
**target_entry
)
1308 debug_atomic_inc(nr_cyclic_checks
);
1310 result
= __bfs_forwards(root
, target
, class_equal
, target_entry
);
1316 check_redundant(struct lock_list
*root
, struct lock_class
*target
,
1317 struct lock_list
**target_entry
)
1321 debug_atomic_inc(nr_redundant_checks
);
1323 result
= __bfs_forwards(root
, target
, class_equal
, target_entry
);
1328 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1330 * Forwards and backwards subgraph searching, for the purposes of
1331 * proving that two subgraphs can be connected by a new dependency
1332 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1335 static inline int usage_match(struct lock_list
*entry
, void *bit
)
1337 return entry
->class->usage_mask
& (1 << (enum lock_usage_bit
)bit
);
1343 * Find a node in the forwards-direction dependency sub-graph starting
1344 * at @root->class that matches @bit.
1346 * Return 0 if such a node exists in the subgraph, and put that node
1347 * into *@target_entry.
1349 * Return 1 otherwise and keep *@target_entry unchanged.
1350 * Return <0 on error.
1353 find_usage_forwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1354 struct lock_list
**target_entry
)
1358 debug_atomic_inc(nr_find_usage_forwards_checks
);
1360 result
= __bfs_forwards(root
, (void *)bit
, usage_match
, target_entry
);
1366 * Find a node in the backwards-direction dependency sub-graph starting
1367 * at @root->class that matches @bit.
1369 * Return 0 if such a node exists in the subgraph, and put that node
1370 * into *@target_entry.
1372 * Return 1 otherwise and keep *@target_entry unchanged.
1373 * Return <0 on error.
1376 find_usage_backwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1377 struct lock_list
**target_entry
)
1381 debug_atomic_inc(nr_find_usage_backwards_checks
);
1383 result
= __bfs_backwards(root
, (void *)bit
, usage_match
, target_entry
);
1388 static void print_lock_class_header(struct lock_class
*class, int depth
)
1392 printk("%*s->", depth
, "");
1393 print_lock_name(class);
1394 printk(KERN_CONT
" ops: %lu", class->ops
);
1395 printk(KERN_CONT
" {\n");
1397 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
1398 if (class->usage_mask
& (1 << bit
)) {
1401 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
1402 len
+= printk(KERN_CONT
" at:\n");
1403 print_stack_trace(class->usage_traces
+ bit
, len
);
1406 printk("%*s }\n", depth
, "");
1408 printk("%*s ... key at: [<%px>] %pS\n",
1409 depth
, "", class->key
, class->key
);
1413 * printk the shortest lock dependencies from @start to @end in reverse order:
1416 print_shortest_lock_dependencies(struct lock_list
*leaf
,
1417 struct lock_list
*root
)
1419 struct lock_list
*entry
= leaf
;
1422 /*compute depth from generated tree by BFS*/
1423 depth
= get_lock_depth(leaf
);
1426 print_lock_class_header(entry
->class, depth
);
1427 printk("%*s ... acquired at:\n", depth
, "");
1428 print_stack_trace(&entry
->trace
, 2);
1431 if (depth
== 0 && (entry
!= root
)) {
1432 printk("lockdep:%s bad path found in chain graph\n", __func__
);
1436 entry
= get_lock_parent(entry
);
1438 } while (entry
&& (depth
>= 0));
1444 print_irq_lock_scenario(struct lock_list
*safe_entry
,
1445 struct lock_list
*unsafe_entry
,
1446 struct lock_class
*prev_class
,
1447 struct lock_class
*next_class
)
1449 struct lock_class
*safe_class
= safe_entry
->class;
1450 struct lock_class
*unsafe_class
= unsafe_entry
->class;
1451 struct lock_class
*middle_class
= prev_class
;
1453 if (middle_class
== safe_class
)
1454 middle_class
= next_class
;
1457 * A direct locking problem where unsafe_class lock is taken
1458 * directly by safe_class lock, then all we need to show
1459 * is the deadlock scenario, as it is obvious that the
1460 * unsafe lock is taken under the safe lock.
1462 * But if there is a chain instead, where the safe lock takes
1463 * an intermediate lock (middle_class) where this lock is
1464 * not the same as the safe lock, then the lock chain is
1465 * used to describe the problem. Otherwise we would need
1466 * to show a different CPU case for each link in the chain
1467 * from the safe_class lock to the unsafe_class lock.
1469 if (middle_class
!= unsafe_class
) {
1470 printk("Chain exists of:\n ");
1471 __print_lock_name(safe_class
);
1472 printk(KERN_CONT
" --> ");
1473 __print_lock_name(middle_class
);
1474 printk(KERN_CONT
" --> ");
1475 __print_lock_name(unsafe_class
);
1476 printk(KERN_CONT
"\n\n");
1479 printk(" Possible interrupt unsafe locking scenario:\n\n");
1480 printk(" CPU0 CPU1\n");
1481 printk(" ---- ----\n");
1483 __print_lock_name(unsafe_class
);
1484 printk(KERN_CONT
");\n");
1485 printk(" local_irq_disable();\n");
1487 __print_lock_name(safe_class
);
1488 printk(KERN_CONT
");\n");
1490 __print_lock_name(middle_class
);
1491 printk(KERN_CONT
");\n");
1492 printk(" <Interrupt>\n");
1494 __print_lock_name(safe_class
);
1495 printk(KERN_CONT
");\n");
1496 printk("\n *** DEADLOCK ***\n\n");
1500 print_bad_irq_dependency(struct task_struct
*curr
,
1501 struct lock_list
*prev_root
,
1502 struct lock_list
*next_root
,
1503 struct lock_list
*backwards_entry
,
1504 struct lock_list
*forwards_entry
,
1505 struct held_lock
*prev
,
1506 struct held_lock
*next
,
1507 enum lock_usage_bit bit1
,
1508 enum lock_usage_bit bit2
,
1509 const char *irqclass
)
1511 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1515 pr_warn("=====================================================\n");
1516 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
1517 irqclass
, irqclass
);
1518 print_kernel_ident();
1519 pr_warn("-----------------------------------------------------\n");
1520 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1521 curr
->comm
, task_pid_nr(curr
),
1522 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1523 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1524 curr
->hardirqs_enabled
,
1525 curr
->softirqs_enabled
);
1528 pr_warn("\nand this task is already holding:\n");
1530 pr_warn("which would create a new lock dependency:\n");
1531 print_lock_name(hlock_class(prev
));
1533 print_lock_name(hlock_class(next
));
1536 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
1538 print_lock_name(backwards_entry
->class);
1539 pr_warn("\n... which became %s-irq-safe at:\n", irqclass
);
1541 print_stack_trace(backwards_entry
->class->usage_traces
+ bit1
, 1);
1543 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass
);
1544 print_lock_name(forwards_entry
->class);
1545 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass
);
1548 print_stack_trace(forwards_entry
->class->usage_traces
+ bit2
, 1);
1550 pr_warn("\nother info that might help us debug this:\n\n");
1551 print_irq_lock_scenario(backwards_entry
, forwards_entry
,
1552 hlock_class(prev
), hlock_class(next
));
1554 lockdep_print_held_locks(curr
);
1556 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass
);
1557 if (!save_trace(&prev_root
->trace
))
1559 print_shortest_lock_dependencies(backwards_entry
, prev_root
);
1561 pr_warn("\nthe dependencies between the lock to be acquired");
1562 pr_warn(" and %s-irq-unsafe lock:\n", irqclass
);
1563 if (!save_trace(&next_root
->trace
))
1565 print_shortest_lock_dependencies(forwards_entry
, next_root
);
1567 pr_warn("\nstack backtrace:\n");
1574 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1575 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1576 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1579 struct lock_list
this, that
;
1580 struct lock_list
*uninitialized_var(target_entry
);
1581 struct lock_list
*uninitialized_var(target_entry1
);
1585 this.class = hlock_class(prev
);
1586 ret
= find_usage_backwards(&this, bit_backwards
, &target_entry
);
1588 return print_bfs_bug(ret
);
1593 that
.class = hlock_class(next
);
1594 ret
= find_usage_forwards(&that
, bit_forwards
, &target_entry1
);
1596 return print_bfs_bug(ret
);
1600 return print_bad_irq_dependency(curr
, &this, &that
,
1601 target_entry
, target_entry1
,
1603 bit_backwards
, bit_forwards
, irqclass
);
1606 static const char *state_names
[] = {
1607 #define LOCKDEP_STATE(__STATE) \
1608 __stringify(__STATE),
1609 #include "lockdep_states.h"
1610 #undef LOCKDEP_STATE
1613 static const char *state_rnames
[] = {
1614 #define LOCKDEP_STATE(__STATE) \
1615 __stringify(__STATE)"-READ",
1616 #include "lockdep_states.h"
1617 #undef LOCKDEP_STATE
1620 static inline const char *state_name(enum lock_usage_bit bit
)
1622 return (bit
& 1) ? state_rnames
[bit
>> 2] : state_names
[bit
>> 2];
1625 static int exclusive_bit(int new_bit
)
1633 * bit 0 - write/read
1634 * bit 1 - used_in/enabled
1638 int state
= new_bit
& ~3;
1639 int dir
= new_bit
& 2;
1642 * keep state, bit flip the direction and strip read.
1644 return state
| (dir
^ 2);
1647 static int check_irq_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1648 struct held_lock
*next
, enum lock_usage_bit bit
)
1651 * Prove that the new dependency does not connect a hardirq-safe
1652 * lock with a hardirq-unsafe lock - to achieve this we search
1653 * the backwards-subgraph starting at <prev>, and the
1654 * forwards-subgraph starting at <next>:
1656 if (!check_usage(curr
, prev
, next
, bit
,
1657 exclusive_bit(bit
), state_name(bit
)))
1663 * Prove that the new dependency does not connect a hardirq-safe-read
1664 * lock with a hardirq-unsafe lock - to achieve this we search
1665 * the backwards-subgraph starting at <prev>, and the
1666 * forwards-subgraph starting at <next>:
1668 if (!check_usage(curr
, prev
, next
, bit
,
1669 exclusive_bit(bit
), state_name(bit
)))
1676 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1677 struct held_lock
*next
)
1679 #define LOCKDEP_STATE(__STATE) \
1680 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1682 #include "lockdep_states.h"
1683 #undef LOCKDEP_STATE
1688 static void inc_chains(void)
1690 if (current
->hardirq_context
)
1691 nr_hardirq_chains
++;
1693 if (current
->softirq_context
)
1694 nr_softirq_chains
++;
1696 nr_process_chains
++;
1703 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1704 struct held_lock
*next
)
1709 static inline void inc_chains(void)
1711 nr_process_chains
++;
1717 print_deadlock_scenario(struct held_lock
*nxt
,
1718 struct held_lock
*prv
)
1720 struct lock_class
*next
= hlock_class(nxt
);
1721 struct lock_class
*prev
= hlock_class(prv
);
1723 printk(" Possible unsafe locking scenario:\n\n");
1727 __print_lock_name(prev
);
1728 printk(KERN_CONT
");\n");
1730 __print_lock_name(next
);
1731 printk(KERN_CONT
");\n");
1732 printk("\n *** DEADLOCK ***\n\n");
1733 printk(" May be due to missing lock nesting notation\n\n");
1737 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1738 struct held_lock
*next
)
1740 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1744 pr_warn("============================================\n");
1745 pr_warn("WARNING: possible recursive locking detected\n");
1746 print_kernel_ident();
1747 pr_warn("--------------------------------------------\n");
1748 pr_warn("%s/%d is trying to acquire lock:\n",
1749 curr
->comm
, task_pid_nr(curr
));
1751 pr_warn("\nbut task is already holding lock:\n");
1754 pr_warn("\nother info that might help us debug this:\n");
1755 print_deadlock_scenario(next
, prev
);
1756 lockdep_print_held_locks(curr
);
1758 pr_warn("\nstack backtrace:\n");
1765 * Check whether we are holding such a class already.
1767 * (Note that this has to be done separately, because the graph cannot
1768 * detect such classes of deadlocks.)
1770 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1773 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1774 struct lockdep_map
*next_instance
, int read
)
1776 struct held_lock
*prev
;
1777 struct held_lock
*nest
= NULL
;
1780 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1781 prev
= curr
->held_locks
+ i
;
1783 if (prev
->instance
== next
->nest_lock
)
1786 if (hlock_class(prev
) != hlock_class(next
))
1790 * Allow read-after-read recursion of the same
1791 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1793 if ((read
== 2) && prev
->read
)
1797 * We're holding the nest_lock, which serializes this lock's
1798 * nesting behaviour.
1803 return print_deadlock_bug(curr
, prev
, next
);
1809 * There was a chain-cache miss, and we are about to add a new dependency
1810 * to a previous lock. We recursively validate the following rules:
1812 * - would the adding of the <prev> -> <next> dependency create a
1813 * circular dependency in the graph? [== circular deadlock]
1815 * - does the new prev->next dependency connect any hardirq-safe lock
1816 * (in the full backwards-subgraph starting at <prev>) with any
1817 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1818 * <next>)? [== illegal lock inversion with hardirq contexts]
1820 * - does the new prev->next dependency connect any softirq-safe lock
1821 * (in the full backwards-subgraph starting at <prev>) with any
1822 * softirq-unsafe lock (in the full forwards-subgraph starting at
1823 * <next>)? [== illegal lock inversion with softirq contexts]
1825 * any of these scenarios could lead to a deadlock.
1827 * Then if all the validations pass, we add the forwards and backwards
1831 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1832 struct held_lock
*next
, int distance
, struct stack_trace
*trace
,
1833 int (*save
)(struct stack_trace
*trace
))
1835 struct lock_list
*uninitialized_var(target_entry
);
1836 struct lock_list
*entry
;
1837 struct lock_list
this;
1841 * Prove that the new <prev> -> <next> dependency would not
1842 * create a circular dependency in the graph. (We do this by
1843 * forward-recursing into the graph starting at <next>, and
1844 * checking whether we can reach <prev>.)
1846 * We are using global variables to control the recursion, to
1847 * keep the stackframe size of the recursive functions low:
1849 this.class = hlock_class(next
);
1851 ret
= check_noncircular(&this, hlock_class(prev
), &target_entry
);
1852 if (unlikely(!ret
)) {
1853 if (!trace
->entries
) {
1855 * If @save fails here, the printing might trigger
1856 * a WARN but because of the !nr_entries it should
1857 * not do bad things.
1861 return print_circular_bug(&this, target_entry
, next
, prev
, trace
);
1863 else if (unlikely(ret
< 0))
1864 return print_bfs_bug(ret
);
1866 if (!check_prev_add_irq(curr
, prev
, next
))
1870 * For recursive read-locks we do all the dependency checks,
1871 * but we dont store read-triggered dependencies (only
1872 * write-triggered dependencies). This ensures that only the
1873 * write-side dependencies matter, and that if for example a
1874 * write-lock never takes any other locks, then the reads are
1875 * equivalent to a NOP.
1877 if (next
->read
== 2 || prev
->read
== 2)
1880 * Is the <prev> -> <next> dependency already present?
1882 * (this may occur even though this is a new chain: consider
1883 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1884 * chains - the second one will be new, but L1 already has
1885 * L2 added to its dependency list, due to the first chain.)
1887 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1888 if (entry
->class == hlock_class(next
)) {
1890 entry
->distance
= 1;
1896 * Is the <prev> -> <next> link redundant?
1898 this.class = hlock_class(prev
);
1900 ret
= check_redundant(&this, hlock_class(next
), &target_entry
);
1902 debug_atomic_inc(nr_redundant
);
1906 return print_bfs_bug(ret
);
1909 if (!trace
->entries
&& !save(trace
))
1913 * Ok, all validations passed, add the new lock
1914 * to the previous lock's dependency list:
1916 ret
= add_lock_to_list(hlock_class(next
),
1917 &hlock_class(prev
)->locks_after
,
1918 next
->acquire_ip
, distance
, trace
);
1923 ret
= add_lock_to_list(hlock_class(prev
),
1924 &hlock_class(next
)->locks_before
,
1925 next
->acquire_ip
, distance
, trace
);
1933 * Add the dependency to all directly-previous locks that are 'relevant'.
1934 * The ones that are relevant are (in increasing distance from curr):
1935 * all consecutive trylock entries and the final non-trylock entry - or
1936 * the end of this context's lock-chain - whichever comes first.
1939 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1941 int depth
= curr
->lockdep_depth
;
1942 struct held_lock
*hlock
;
1943 struct stack_trace trace
= {
1953 * Depth must not be zero for a non-head lock:
1958 * At least two relevant locks must exist for this
1961 if (curr
->held_locks
[depth
].irq_context
!=
1962 curr
->held_locks
[depth
-1].irq_context
)
1966 int distance
= curr
->lockdep_depth
- depth
+ 1;
1967 hlock
= curr
->held_locks
+ depth
- 1;
1970 * Only non-recursive-read entries get new dependencies
1973 if (hlock
->read
!= 2 && hlock
->check
) {
1974 int ret
= check_prev_add(curr
, hlock
, next
, distance
, &trace
, save_trace
);
1979 * Stop after the first non-trylock entry,
1980 * as non-trylock entries have added their
1981 * own direct dependencies already, so this
1982 * lock is connected to them indirectly:
1984 if (!hlock
->trylock
)
1990 * End of lock-stack?
1995 * Stop the search if we cross into another context:
1997 if (curr
->held_locks
[depth
].irq_context
!=
1998 curr
->held_locks
[depth
-1].irq_context
)
2003 if (!debug_locks_off_graph_unlock())
2007 * Clearly we all shouldn't be here, but since we made it we
2008 * can reliable say we messed up our state. See the above two
2009 * gotos for reasons why we could possibly end up here.
2016 unsigned long nr_lock_chains
;
2017 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
2018 int nr_chain_hlocks
;
2019 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
2021 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
2023 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
2027 * Returns the index of the first held_lock of the current chain
2029 static inline int get_first_held_lock(struct task_struct
*curr
,
2030 struct held_lock
*hlock
)
2033 struct held_lock
*hlock_curr
;
2035 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
2036 hlock_curr
= curr
->held_locks
+ i
;
2037 if (hlock_curr
->irq_context
!= hlock
->irq_context
)
2045 #ifdef CONFIG_DEBUG_LOCKDEP
2047 * Returns the next chain_key iteration
2049 static u64
print_chain_key_iteration(int class_idx
, u64 chain_key
)
2051 u64 new_chain_key
= iterate_chain_key(chain_key
, class_idx
);
2053 printk(" class_idx:%d -> chain_key:%016Lx",
2055 (unsigned long long)new_chain_key
);
2056 return new_chain_key
;
2060 print_chain_keys_held_locks(struct task_struct
*curr
, struct held_lock
*hlock_next
)
2062 struct held_lock
*hlock
;
2064 int depth
= curr
->lockdep_depth
;
2067 printk("depth: %u\n", depth
+ 1);
2068 for (i
= get_first_held_lock(curr
, hlock_next
); i
< depth
; i
++) {
2069 hlock
= curr
->held_locks
+ i
;
2070 chain_key
= print_chain_key_iteration(hlock
->class_idx
, chain_key
);
2075 print_chain_key_iteration(hlock_next
->class_idx
, chain_key
);
2076 print_lock(hlock_next
);
2079 static void print_chain_keys_chain(struct lock_chain
*chain
)
2085 printk("depth: %u\n", chain
->depth
);
2086 for (i
= 0; i
< chain
->depth
; i
++) {
2087 class_id
= chain_hlocks
[chain
->base
+ i
];
2088 chain_key
= print_chain_key_iteration(class_id
+ 1, chain_key
);
2090 print_lock_name(lock_classes
+ class_id
);
2095 static void print_collision(struct task_struct
*curr
,
2096 struct held_lock
*hlock_next
,
2097 struct lock_chain
*chain
)
2100 pr_warn("============================\n");
2101 pr_warn("WARNING: chain_key collision\n");
2102 print_kernel_ident();
2103 pr_warn("----------------------------\n");
2104 pr_warn("%s/%d: ", current
->comm
, task_pid_nr(current
));
2105 pr_warn("Hash chain already cached but the contents don't match!\n");
2107 pr_warn("Held locks:");
2108 print_chain_keys_held_locks(curr
, hlock_next
);
2110 pr_warn("Locks in cached chain:");
2111 print_chain_keys_chain(chain
);
2113 pr_warn("\nstack backtrace:\n");
2119 * Checks whether the chain and the current held locks are consistent
2120 * in depth and also in content. If they are not it most likely means
2121 * that there was a collision during the calculation of the chain_key.
2122 * Returns: 0 not passed, 1 passed
2124 static int check_no_collision(struct task_struct
*curr
,
2125 struct held_lock
*hlock
,
2126 struct lock_chain
*chain
)
2128 #ifdef CONFIG_DEBUG_LOCKDEP
2131 i
= get_first_held_lock(curr
, hlock
);
2133 if (DEBUG_LOCKS_WARN_ON(chain
->depth
!= curr
->lockdep_depth
- (i
- 1))) {
2134 print_collision(curr
, hlock
, chain
);
2138 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2139 id
= curr
->held_locks
[i
].class_idx
- 1;
2141 if (DEBUG_LOCKS_WARN_ON(chain_hlocks
[chain
->base
+ j
] != id
)) {
2142 print_collision(curr
, hlock
, chain
);
2151 * This is for building a chain between just two different classes,
2152 * instead of adding a new hlock upon current, which is done by
2153 * add_chain_cache().
2155 * This can be called in any context with two classes, while
2156 * add_chain_cache() must be done within the lock owener's context
2157 * since it uses hlock which might be racy in another context.
2159 static inline int add_chain_cache_classes(unsigned int prev
,
2161 unsigned int irq_context
,
2164 struct hlist_head
*hash_head
= chainhashentry(chain_key
);
2165 struct lock_chain
*chain
;
2168 * Allocate a new chain entry from the static array, and add
2173 * We might need to take the graph lock, ensure we've got IRQs
2174 * disabled to make this an IRQ-safe lock.. for recursion reasons
2175 * lockdep won't complain about its own locking errors.
2177 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2180 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
2181 if (!debug_locks_off_graph_unlock())
2184 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2189 chain
= lock_chains
+ nr_lock_chains
++;
2190 chain
->chain_key
= chain_key
;
2191 chain
->irq_context
= irq_context
;
2193 if (likely(nr_chain_hlocks
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2194 chain
->base
= nr_chain_hlocks
;
2195 nr_chain_hlocks
+= chain
->depth
;
2196 chain_hlocks
[chain
->base
] = prev
- 1;
2197 chain_hlocks
[chain
->base
+ 1] = next
-1;
2199 #ifdef CONFIG_DEBUG_LOCKDEP
2201 * Important for check_no_collision().
2204 if (!debug_locks_off_graph_unlock())
2207 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2213 hlist_add_head_rcu(&chain
->entry
, hash_head
);
2214 debug_atomic_inc(chain_lookup_misses
);
2221 * Adds a dependency chain into chain hashtable. And must be called with
2224 * Return 0 if fail, and graph_lock is released.
2225 * Return 1 if succeed, with graph_lock held.
2227 static inline int add_chain_cache(struct task_struct
*curr
,
2228 struct held_lock
*hlock
,
2231 struct lock_class
*class = hlock_class(hlock
);
2232 struct hlist_head
*hash_head
= chainhashentry(chain_key
);
2233 struct lock_chain
*chain
;
2237 * Allocate a new chain entry from the static array, and add
2242 * We might need to take the graph lock, ensure we've got IRQs
2243 * disabled to make this an IRQ-safe lock.. for recursion reasons
2244 * lockdep won't complain about its own locking errors.
2246 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2249 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
2250 if (!debug_locks_off_graph_unlock())
2253 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2257 chain
= lock_chains
+ nr_lock_chains
++;
2258 chain
->chain_key
= chain_key
;
2259 chain
->irq_context
= hlock
->irq_context
;
2260 i
= get_first_held_lock(curr
, hlock
);
2261 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
2263 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks
));
2264 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr
->held_locks
));
2265 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks
[0])) <= ARRAY_SIZE(lock_classes
));
2267 if (likely(nr_chain_hlocks
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2268 chain
->base
= nr_chain_hlocks
;
2269 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2270 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
2271 chain_hlocks
[chain
->base
+ j
] = lock_id
;
2273 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
2276 if (nr_chain_hlocks
< MAX_LOCKDEP_CHAIN_HLOCKS
)
2277 nr_chain_hlocks
+= chain
->depth
;
2279 #ifdef CONFIG_DEBUG_LOCKDEP
2281 * Important for check_no_collision().
2283 if (unlikely(nr_chain_hlocks
> MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2284 if (!debug_locks_off_graph_unlock())
2287 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2293 hlist_add_head_rcu(&chain
->entry
, hash_head
);
2294 debug_atomic_inc(chain_lookup_misses
);
2301 * Look up a dependency chain.
2303 static inline struct lock_chain
*lookup_chain_cache(u64 chain_key
)
2305 struct hlist_head
*hash_head
= chainhashentry(chain_key
);
2306 struct lock_chain
*chain
;
2309 * We can walk it lock-free, because entries only get added
2312 hlist_for_each_entry_rcu(chain
, hash_head
, entry
) {
2313 if (chain
->chain_key
== chain_key
) {
2314 debug_atomic_inc(chain_lookup_hits
);
2322 * If the key is not present yet in dependency chain cache then
2323 * add it and return 1 - in this case the new dependency chain is
2324 * validated. If the key is already hashed, return 0.
2325 * (On return with 1 graph_lock is held.)
2327 static inline int lookup_chain_cache_add(struct task_struct
*curr
,
2328 struct held_lock
*hlock
,
2331 struct lock_class
*class = hlock_class(hlock
);
2332 struct lock_chain
*chain
= lookup_chain_cache(chain_key
);
2336 if (!check_no_collision(curr
, hlock
, chain
))
2339 if (very_verbose(class)) {
2340 printk("\nhash chain already cached, key: "
2341 "%016Lx tail class: [%px] %s\n",
2342 (unsigned long long)chain_key
,
2343 class->key
, class->name
);
2349 if (very_verbose(class)) {
2350 printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
2351 (unsigned long long)chain_key
, class->key
, class->name
);
2358 * We have to walk the chain again locked - to avoid duplicates:
2360 chain
= lookup_chain_cache(chain_key
);
2366 if (!add_chain_cache(curr
, hlock
, chain_key
))
2372 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
2373 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
2376 * Trylock needs to maintain the stack of held locks, but it
2377 * does not add new dependencies, because trylock can be done
2380 * We look up the chain_key and do the O(N^2) check and update of
2381 * the dependencies only if this is a new dependency chain.
2382 * (If lookup_chain_cache_add() return with 1 it acquires
2383 * graph_lock for us)
2385 if (!hlock
->trylock
&& hlock
->check
&&
2386 lookup_chain_cache_add(curr
, hlock
, chain_key
)) {
2388 * Check whether last held lock:
2390 * - is irq-safe, if this lock is irq-unsafe
2391 * - is softirq-safe, if this lock is hardirq-unsafe
2393 * And check whether the new lock's dependency graph
2394 * could lead back to the previous lock.
2396 * any of these scenarios could lead to a deadlock. If
2399 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
2404 * Mark recursive read, as we jump over it when
2405 * building dependencies (just like we jump over
2411 * Add dependency only if this lock is not the head
2412 * of the chain, and if it's not a secondary read-lock:
2414 if (!chain_head
&& ret
!= 2) {
2415 if (!check_prevs_add(curr
, hlock
))
2421 /* after lookup_chain_cache_add(): */
2422 if (unlikely(!debug_locks
))
2429 static inline int validate_chain(struct task_struct
*curr
,
2430 struct lockdep_map
*lock
, struct held_lock
*hlock
,
2431 int chain_head
, u64 chain_key
)
2438 * We are building curr_chain_key incrementally, so double-check
2439 * it from scratch, to make sure that it's done correctly:
2441 static void check_chain_key(struct task_struct
*curr
)
2443 #ifdef CONFIG_DEBUG_LOCKDEP
2444 struct held_lock
*hlock
, *prev_hlock
= NULL
;
2448 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2449 hlock
= curr
->held_locks
+ i
;
2450 if (chain_key
!= hlock
->prev_chain_key
) {
2453 * We got mighty confused, our chain keys don't match
2454 * with what we expect, someone trample on our task state?
2456 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2457 curr
->lockdep_depth
, i
,
2458 (unsigned long long)chain_key
,
2459 (unsigned long long)hlock
->prev_chain_key
);
2463 * Whoops ran out of static storage again?
2465 if (DEBUG_LOCKS_WARN_ON(hlock
->class_idx
> MAX_LOCKDEP_KEYS
))
2468 if (prev_hlock
&& (prev_hlock
->irq_context
!=
2469 hlock
->irq_context
))
2471 chain_key
= iterate_chain_key(chain_key
, hlock
->class_idx
);
2474 if (chain_key
!= curr
->curr_chain_key
) {
2477 * More smoking hash instead of calculating it, damn see these
2478 * numbers float.. I bet that a pink elephant stepped on my memory.
2480 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2481 curr
->lockdep_depth
, i
,
2482 (unsigned long long)chain_key
,
2483 (unsigned long long)curr
->curr_chain_key
);
2489 print_usage_bug_scenario(struct held_lock
*lock
)
2491 struct lock_class
*class = hlock_class(lock
);
2493 printk(" Possible unsafe locking scenario:\n\n");
2497 __print_lock_name(class);
2498 printk(KERN_CONT
");\n");
2499 printk(" <Interrupt>\n");
2501 __print_lock_name(class);
2502 printk(KERN_CONT
");\n");
2503 printk("\n *** DEADLOCK ***\n\n");
2507 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
2508 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
2510 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2514 pr_warn("================================\n");
2515 pr_warn("WARNING: inconsistent lock state\n");
2516 print_kernel_ident();
2517 pr_warn("--------------------------------\n");
2519 pr_warn("inconsistent {%s} -> {%s} usage.\n",
2520 usage_str
[prev_bit
], usage_str
[new_bit
]);
2522 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2523 curr
->comm
, task_pid_nr(curr
),
2524 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
2525 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
2526 trace_hardirqs_enabled(curr
),
2527 trace_softirqs_enabled(curr
));
2530 pr_warn("{%s} state was registered at:\n", usage_str
[prev_bit
]);
2531 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
2533 print_irqtrace_events(curr
);
2534 pr_warn("\nother info that might help us debug this:\n");
2535 print_usage_bug_scenario(this);
2537 lockdep_print_held_locks(curr
);
2539 pr_warn("\nstack backtrace:\n");
2546 * Print out an error if an invalid bit is set:
2549 valid_state(struct task_struct
*curr
, struct held_lock
*this,
2550 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
2552 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
2553 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
2557 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2558 enum lock_usage_bit new_bit
);
2560 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2563 * print irq inversion bug:
2566 print_irq_inversion_bug(struct task_struct
*curr
,
2567 struct lock_list
*root
, struct lock_list
*other
,
2568 struct held_lock
*this, int forwards
,
2569 const char *irqclass
)
2571 struct lock_list
*entry
= other
;
2572 struct lock_list
*middle
= NULL
;
2575 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2579 pr_warn("========================================================\n");
2580 pr_warn("WARNING: possible irq lock inversion dependency detected\n");
2581 print_kernel_ident();
2582 pr_warn("--------------------------------------------------------\n");
2583 pr_warn("%s/%d just changed the state of lock:\n",
2584 curr
->comm
, task_pid_nr(curr
));
2587 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass
);
2589 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass
);
2590 print_lock_name(other
->class);
2591 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2593 pr_warn("\nother info that might help us debug this:\n");
2595 /* Find a middle lock (if one exists) */
2596 depth
= get_lock_depth(other
);
2598 if (depth
== 0 && (entry
!= root
)) {
2599 pr_warn("lockdep:%s bad path found in chain graph\n", __func__
);
2603 entry
= get_lock_parent(entry
);
2605 } while (entry
&& entry
!= root
&& (depth
>= 0));
2607 print_irq_lock_scenario(root
, other
,
2608 middle
? middle
->class : root
->class, other
->class);
2610 print_irq_lock_scenario(other
, root
,
2611 middle
? middle
->class : other
->class, root
->class);
2613 lockdep_print_held_locks(curr
);
2615 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2616 if (!save_trace(&root
->trace
))
2618 print_shortest_lock_dependencies(other
, root
);
2620 pr_warn("\nstack backtrace:\n");
2627 * Prove that in the forwards-direction subgraph starting at <this>
2628 * there is no lock matching <mask>:
2631 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
2632 enum lock_usage_bit bit
, const char *irqclass
)
2635 struct lock_list root
;
2636 struct lock_list
*uninitialized_var(target_entry
);
2639 root
.class = hlock_class(this);
2640 ret
= find_usage_forwards(&root
, bit
, &target_entry
);
2642 return print_bfs_bug(ret
);
2646 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2651 * Prove that in the backwards-direction subgraph starting at <this>
2652 * there is no lock matching <mask>:
2655 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
2656 enum lock_usage_bit bit
, const char *irqclass
)
2659 struct lock_list root
;
2660 struct lock_list
*uninitialized_var(target_entry
);
2663 root
.class = hlock_class(this);
2664 ret
= find_usage_backwards(&root
, bit
, &target_entry
);
2666 return print_bfs_bug(ret
);
2670 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2674 void print_irqtrace_events(struct task_struct
*curr
)
2676 printk("irq event stamp: %u\n", curr
->irq_events
);
2677 printk("hardirqs last enabled at (%u): [<%px>] %pS\n",
2678 curr
->hardirq_enable_event
, (void *)curr
->hardirq_enable_ip
,
2679 (void *)curr
->hardirq_enable_ip
);
2680 printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
2681 curr
->hardirq_disable_event
, (void *)curr
->hardirq_disable_ip
,
2682 (void *)curr
->hardirq_disable_ip
);
2683 printk("softirqs last enabled at (%u): [<%px>] %pS\n",
2684 curr
->softirq_enable_event
, (void *)curr
->softirq_enable_ip
,
2685 (void *)curr
->softirq_enable_ip
);
2686 printk("softirqs last disabled at (%u): [<%px>] %pS\n",
2687 curr
->softirq_disable_event
, (void *)curr
->softirq_disable_ip
,
2688 (void *)curr
->softirq_disable_ip
);
2691 static int HARDIRQ_verbose(struct lock_class
*class)
2694 return class_filter(class);
2699 static int SOFTIRQ_verbose(struct lock_class
*class)
2702 return class_filter(class);
2707 #define STRICT_READ_CHECKS 1
2709 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2710 #define LOCKDEP_STATE(__STATE) \
2712 #include "lockdep_states.h"
2713 #undef LOCKDEP_STATE
2716 static inline int state_verbose(enum lock_usage_bit bit
,
2717 struct lock_class
*class)
2719 return state_verbose_f
[bit
>> 2](class);
2722 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2723 enum lock_usage_bit bit
, const char *name
);
2726 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2727 enum lock_usage_bit new_bit
)
2729 int excl_bit
= exclusive_bit(new_bit
);
2730 int read
= new_bit
& 1;
2731 int dir
= new_bit
& 2;
2734 * mark USED_IN has to look forwards -- to ensure no dependency
2735 * has ENABLED state, which would allow recursion deadlocks.
2737 * mark ENABLED has to look backwards -- to ensure no dependee
2738 * has USED_IN state, which, again, would allow recursion deadlocks.
2740 check_usage_f usage
= dir
?
2741 check_usage_backwards
: check_usage_forwards
;
2744 * Validate that this particular lock does not have conflicting
2747 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2751 * Validate that the lock dependencies don't have conflicting usage
2754 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2755 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2759 * Check for read in write conflicts
2762 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2765 if (STRICT_READ_CHECKS
&&
2766 !usage(curr
, this, excl_bit
+ 1,
2767 state_name(new_bit
+ 1)))
2771 if (state_verbose(new_bit
, hlock_class(this)))
2778 #define LOCKDEP_STATE(__STATE) __STATE,
2779 #include "lockdep_states.h"
2780 #undef LOCKDEP_STATE
2784 * Mark all held locks with a usage bit:
2787 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2789 enum lock_usage_bit usage_bit
;
2790 struct held_lock
*hlock
;
2793 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2794 hlock
= curr
->held_locks
+ i
;
2796 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2798 usage_bit
+= 1; /* READ */
2800 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2805 if (!mark_lock(curr
, hlock
, usage_bit
))
2813 * Hardirqs will be enabled:
2815 static void __trace_hardirqs_on_caller(unsigned long ip
)
2817 struct task_struct
*curr
= current
;
2819 /* we'll do an OFF -> ON transition: */
2820 curr
->hardirqs_enabled
= 1;
2823 * We are going to turn hardirqs on, so set the
2824 * usage bit for all held locks:
2826 if (!mark_held_locks(curr
, HARDIRQ
))
2829 * If we have softirqs enabled, then set the usage
2830 * bit for all held locks. (disabled hardirqs prevented
2831 * this bit from being set before)
2833 if (curr
->softirqs_enabled
)
2834 if (!mark_held_locks(curr
, SOFTIRQ
))
2837 curr
->hardirq_enable_ip
= ip
;
2838 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2839 debug_atomic_inc(hardirqs_on_events
);
2842 void lockdep_hardirqs_on(unsigned long 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;
2884 * Hardirqs were disabled:
2886 void lockdep_hardirqs_off(unsigned long ip
)
2888 struct task_struct
*curr
= current
;
2890 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2894 * So we're supposed to get called after you mask local IRQs, but for
2895 * some reason the hardware doesn't quite think you did a proper job.
2897 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2900 if (curr
->hardirqs_enabled
) {
2902 * We have done an ON -> OFF transition:
2904 curr
->hardirqs_enabled
= 0;
2905 curr
->hardirq_disable_ip
= ip
;
2906 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2907 debug_atomic_inc(hardirqs_off_events
);
2909 debug_atomic_inc(redundant_hardirqs_off
);
2913 * Softirqs will be enabled:
2915 void trace_softirqs_on(unsigned long ip
)
2917 struct task_struct
*curr
= current
;
2919 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2923 * We fancy IRQs being disabled here, see softirq.c, avoids
2924 * funny state and nesting things.
2926 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2929 if (curr
->softirqs_enabled
) {
2930 debug_atomic_inc(redundant_softirqs_on
);
2934 current
->lockdep_recursion
= 1;
2936 * We'll do an OFF -> ON transition:
2938 curr
->softirqs_enabled
= 1;
2939 curr
->softirq_enable_ip
= ip
;
2940 curr
->softirq_enable_event
= ++curr
->irq_events
;
2941 debug_atomic_inc(softirqs_on_events
);
2943 * We are going to turn softirqs on, so set the
2944 * usage bit for all held locks, if hardirqs are
2947 if (curr
->hardirqs_enabled
)
2948 mark_held_locks(curr
, SOFTIRQ
);
2949 current
->lockdep_recursion
= 0;
2953 * Softirqs were disabled:
2955 void trace_softirqs_off(unsigned long ip
)
2957 struct task_struct
*curr
= current
;
2959 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2963 * We fancy IRQs being disabled here, see softirq.c
2965 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2968 if (curr
->softirqs_enabled
) {
2970 * We have done an ON -> OFF transition:
2972 curr
->softirqs_enabled
= 0;
2973 curr
->softirq_disable_ip
= ip
;
2974 curr
->softirq_disable_event
= ++curr
->irq_events
;
2975 debug_atomic_inc(softirqs_off_events
);
2977 * Whoops, we wanted softirqs off, so why aren't they?
2979 DEBUG_LOCKS_WARN_ON(!softirq_count());
2981 debug_atomic_inc(redundant_softirqs_off
);
2984 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2987 * If non-trylock use in a hardirq or softirq context, then
2988 * mark the lock as used in these contexts:
2990 if (!hlock
->trylock
) {
2992 if (curr
->hardirq_context
)
2993 if (!mark_lock(curr
, hlock
,
2994 LOCK_USED_IN_HARDIRQ_READ
))
2996 if (curr
->softirq_context
)
2997 if (!mark_lock(curr
, hlock
,
2998 LOCK_USED_IN_SOFTIRQ_READ
))
3001 if (curr
->hardirq_context
)
3002 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
3004 if (curr
->softirq_context
)
3005 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
3009 if (!hlock
->hardirqs_off
) {
3011 if (!mark_lock(curr
, hlock
,
3012 LOCK_ENABLED_HARDIRQ_READ
))
3014 if (curr
->softirqs_enabled
)
3015 if (!mark_lock(curr
, hlock
,
3016 LOCK_ENABLED_SOFTIRQ_READ
))
3019 if (!mark_lock(curr
, hlock
,
3020 LOCK_ENABLED_HARDIRQ
))
3022 if (curr
->softirqs_enabled
)
3023 if (!mark_lock(curr
, hlock
,
3024 LOCK_ENABLED_SOFTIRQ
))
3032 static inline unsigned int task_irq_context(struct task_struct
*task
)
3034 return 2 * !!task
->hardirq_context
+ !!task
->softirq_context
;
3037 static int separate_irq_context(struct task_struct
*curr
,
3038 struct held_lock
*hlock
)
3040 unsigned int depth
= curr
->lockdep_depth
;
3043 * Keep track of points where we cross into an interrupt context:
3046 struct held_lock
*prev_hlock
;
3048 prev_hlock
= curr
->held_locks
+ depth
-1;
3050 * If we cross into another context, reset the
3051 * hash key (this also prevents the checking and the
3052 * adding of the dependency to 'prev'):
3054 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
3060 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3063 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
3064 enum lock_usage_bit new_bit
)
3066 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
3070 static inline int mark_irqflags(struct task_struct
*curr
,
3071 struct held_lock
*hlock
)
3076 static inline unsigned int task_irq_context(struct task_struct
*task
)
3081 static inline int separate_irq_context(struct task_struct
*curr
,
3082 struct held_lock
*hlock
)
3087 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3090 * Mark a lock with a usage bit, and validate the state transition:
3092 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
3093 enum lock_usage_bit new_bit
)
3095 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
3098 * If already set then do not dirty the cacheline,
3099 * nor do any checks:
3101 if (likely(hlock_class(this)->usage_mask
& new_mask
))
3107 * Make sure we didn't race:
3109 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
3114 hlock_class(this)->usage_mask
|= new_mask
;
3116 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
3120 #define LOCKDEP_STATE(__STATE) \
3121 case LOCK_USED_IN_##__STATE: \
3122 case LOCK_USED_IN_##__STATE##_READ: \
3123 case LOCK_ENABLED_##__STATE: \
3124 case LOCK_ENABLED_##__STATE##_READ:
3125 #include "lockdep_states.h"
3126 #undef LOCKDEP_STATE
3127 ret
= mark_lock_irq(curr
, this, new_bit
);
3132 debug_atomic_dec(nr_unused_locks
);
3135 if (!debug_locks_off_graph_unlock())
3144 * We must printk outside of the graph_lock:
3147 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
3149 print_irqtrace_events(curr
);
3157 * Initialize a lock instance's lock-class mapping info:
3159 static void __lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
3160 struct lock_class_key
*key
, int subclass
)
3164 for (i
= 0; i
< NR_LOCKDEP_CACHING_CLASSES
; i
++)
3165 lock
->class_cache
[i
] = NULL
;
3167 #ifdef CONFIG_LOCK_STAT
3168 lock
->cpu
= raw_smp_processor_id();
3172 * Can't be having no nameless bastards around this place!
3174 if (DEBUG_LOCKS_WARN_ON(!name
)) {
3175 lock
->name
= "NULL";
3182 * No key, no joy, we need to hash something.
3184 if (DEBUG_LOCKS_WARN_ON(!key
))
3187 * Sanity check, the lock-class key must be persistent:
3189 if (!static_obj(key
)) {
3190 printk("BUG: key %px not in .data!\n", key
);
3192 * What it says above ^^^^^, I suggest you read it.
3194 DEBUG_LOCKS_WARN_ON(1);
3199 if (unlikely(!debug_locks
))
3203 unsigned long flags
;
3205 if (DEBUG_LOCKS_WARN_ON(current
->lockdep_recursion
))
3208 raw_local_irq_save(flags
);
3209 current
->lockdep_recursion
= 1;
3210 register_lock_class(lock
, subclass
, 1);
3211 current
->lockdep_recursion
= 0;
3212 raw_local_irq_restore(flags
);
3216 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
3217 struct lock_class_key
*key
, int subclass
)
3219 __lockdep_init_map(lock
, name
, key
, subclass
);
3221 EXPORT_SYMBOL_GPL(lockdep_init_map
);
3223 struct lock_class_key __lockdep_no_validate__
;
3224 EXPORT_SYMBOL_GPL(__lockdep_no_validate__
);
3227 print_lock_nested_lock_not_held(struct task_struct
*curr
,
3228 struct held_lock
*hlock
,
3231 if (!debug_locks_off())
3233 if (debug_locks_silent
)
3237 pr_warn("==================================\n");
3238 pr_warn("WARNING: Nested lock was not taken\n");
3239 print_kernel_ident();
3240 pr_warn("----------------------------------\n");
3242 pr_warn("%s/%d is trying to lock:\n", curr
->comm
, task_pid_nr(curr
));
3245 pr_warn("\nbut this task is not holding:\n");
3246 pr_warn("%s\n", hlock
->nest_lock
->name
);
3248 pr_warn("\nstack backtrace:\n");
3251 pr_warn("\nother info that might help us debug this:\n");
3252 lockdep_print_held_locks(curr
);
3254 pr_warn("\nstack backtrace:\n");
3260 static int __lock_is_held(const struct lockdep_map
*lock
, int read
);
3263 * This gets called for every mutex_lock*()/spin_lock*() operation.
3264 * We maintain the dependency maps and validate the locking attempt:
3266 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3267 int trylock
, int read
, int check
, int hardirqs_off
,
3268 struct lockdep_map
*nest_lock
, unsigned long ip
,
3269 int references
, int pin_count
)
3271 struct task_struct
*curr
= current
;
3272 struct lock_class
*class = NULL
;
3273 struct held_lock
*hlock
;
3279 if (unlikely(!debug_locks
))
3283 * Lockdep should run with IRQs disabled, otherwise we could
3284 * get an interrupt which would want to take locks, which would
3285 * end up in lockdep and have you got a head-ache already?
3287 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3290 if (!prove_locking
|| lock
->key
== &__lockdep_no_validate__
)
3293 if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
3294 class = lock
->class_cache
[subclass
];
3298 if (unlikely(!class)) {
3299 class = register_lock_class(lock
, subclass
, 0);
3303 atomic_inc((atomic_t
*)&class->ops
);
3304 if (very_verbose(class)) {
3305 printk("\nacquire class [%px] %s", class->key
, class->name
);
3306 if (class->name_version
> 1)
3307 printk(KERN_CONT
"#%d", class->name_version
);
3308 printk(KERN_CONT
"\n");
3313 * Add the lock to the list of currently held locks.
3314 * (we dont increase the depth just yet, up until the
3315 * dependency checks are done)
3317 depth
= curr
->lockdep_depth
;
3319 * Ran out of static storage for our per-task lock stack again have we?
3321 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
3324 class_idx
= class - lock_classes
+ 1;
3327 hlock
= curr
->held_locks
+ depth
- 1;
3328 if (hlock
->class_idx
== class_idx
&& nest_lock
) {
3329 if (hlock
->references
) {
3331 * Check: unsigned int references:12, overflow.
3333 if (DEBUG_LOCKS_WARN_ON(hlock
->references
== (1 << 12)-1))
3336 hlock
->references
++;
3338 hlock
->references
= 2;
3345 hlock
= curr
->held_locks
+ depth
;
3347 * Plain impossible, we just registered it and checked it weren't no
3348 * NULL like.. I bet this mushroom I ate was good!
3350 if (DEBUG_LOCKS_WARN_ON(!class))
3352 hlock
->class_idx
= class_idx
;
3353 hlock
->acquire_ip
= ip
;
3354 hlock
->instance
= lock
;
3355 hlock
->nest_lock
= nest_lock
;
3356 hlock
->irq_context
= task_irq_context(curr
);
3357 hlock
->trylock
= trylock
;
3359 hlock
->check
= check
;
3360 hlock
->hardirqs_off
= !!hardirqs_off
;
3361 hlock
->references
= references
;
3362 #ifdef CONFIG_LOCK_STAT
3363 hlock
->waittime_stamp
= 0;
3364 hlock
->holdtime_stamp
= lockstat_clock();
3366 hlock
->pin_count
= pin_count
;
3368 if (check
&& !mark_irqflags(curr
, hlock
))
3371 /* mark it as used: */
3372 if (!mark_lock(curr
, hlock
, LOCK_USED
))
3376 * Calculate the chain hash: it's the combined hash of all the
3377 * lock keys along the dependency chain. We save the hash value
3378 * at every step so that we can get the current hash easily
3379 * after unlock. The chain hash is then used to cache dependency
3382 * The 'key ID' is what is the most compact key value to drive
3383 * the hash, not class->key.
3386 * Whoops, we did it again.. ran straight out of our static allocation.
3388 if (DEBUG_LOCKS_WARN_ON(class_idx
> MAX_LOCKDEP_KEYS
))
3391 chain_key
= curr
->curr_chain_key
;
3394 * How can we have a chain hash when we ain't got no keys?!
3396 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
3401 hlock
->prev_chain_key
= chain_key
;
3402 if (separate_irq_context(curr
, hlock
)) {
3406 chain_key
= iterate_chain_key(chain_key
, class_idx
);
3408 if (nest_lock
&& !__lock_is_held(nest_lock
, -1))
3409 return print_lock_nested_lock_not_held(curr
, hlock
, ip
);
3411 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
3414 curr
->curr_chain_key
= chain_key
;
3415 curr
->lockdep_depth
++;
3416 check_chain_key(curr
);
3417 #ifdef CONFIG_DEBUG_LOCKDEP
3418 if (unlikely(!debug_locks
))
3421 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
3423 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3424 printk(KERN_DEBUG
"depth: %i max: %lu!\n",
3425 curr
->lockdep_depth
, MAX_LOCK_DEPTH
);
3427 lockdep_print_held_locks(current
);
3428 debug_show_all_locks();
3434 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
3435 max_lockdep_depth
= curr
->lockdep_depth
;
3441 print_unlock_imbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3444 if (!debug_locks_off())
3446 if (debug_locks_silent
)
3450 pr_warn("=====================================\n");
3451 pr_warn("WARNING: bad unlock balance detected!\n");
3452 print_kernel_ident();
3453 pr_warn("-------------------------------------\n");
3454 pr_warn("%s/%d is trying to release lock (",
3455 curr
->comm
, task_pid_nr(curr
));
3456 print_lockdep_cache(lock
);
3459 pr_warn("but there are no more locks to release!\n");
3460 pr_warn("\nother info that might help us debug this:\n");
3461 lockdep_print_held_locks(curr
);
3463 pr_warn("\nstack backtrace:\n");
3469 static int match_held_lock(const struct held_lock
*hlock
,
3470 const struct lockdep_map
*lock
)
3472 if (hlock
->instance
== lock
)
3475 if (hlock
->references
) {
3476 const struct lock_class
*class = lock
->class_cache
[0];
3479 class = look_up_lock_class(lock
, 0);
3482 * If look_up_lock_class() failed to find a class, we're trying
3483 * to test if we hold a lock that has never yet been acquired.
3484 * Clearly if the lock hasn't been acquired _ever_, we're not
3485 * holding it either, so report failure.
3491 * References, but not a lock we're actually ref-counting?
3492 * State got messed up, follow the sites that change ->references
3493 * and try to make sense of it.
3495 if (DEBUG_LOCKS_WARN_ON(!hlock
->nest_lock
))
3498 if (hlock
->class_idx
== class - lock_classes
+ 1)
3505 /* @depth must not be zero */
3506 static struct held_lock
*find_held_lock(struct task_struct
*curr
,
3507 struct lockdep_map
*lock
,
3508 unsigned int depth
, int *idx
)
3510 struct held_lock
*ret
, *hlock
, *prev_hlock
;
3514 hlock
= curr
->held_locks
+ i
;
3516 if (match_held_lock(hlock
, lock
))
3520 for (i
--, prev_hlock
= hlock
--;
3522 i
--, prev_hlock
= hlock
--) {
3524 * We must not cross into another context:
3526 if (prev_hlock
->irq_context
!= hlock
->irq_context
) {
3530 if (match_held_lock(hlock
, lock
)) {
3541 static int reacquire_held_locks(struct task_struct
*curr
, unsigned int depth
,
3544 struct held_lock
*hlock
;
3546 for (hlock
= curr
->held_locks
+ idx
; idx
< depth
; idx
++, hlock
++) {
3547 if (!__lock_acquire(hlock
->instance
,
3548 hlock_class(hlock
)->subclass
,
3550 hlock
->read
, hlock
->check
,
3551 hlock
->hardirqs_off
,
3552 hlock
->nest_lock
, hlock
->acquire_ip
,
3553 hlock
->references
, hlock
->pin_count
))
3560 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
3561 struct lock_class_key
*key
, unsigned int subclass
,
3564 struct task_struct
*curr
= current
;
3565 struct held_lock
*hlock
;
3566 struct lock_class
*class;
3570 depth
= curr
->lockdep_depth
;
3572 * This function is about (re)setting the class of a held lock,
3573 * yet we're not actually holding any locks. Naughty user!
3575 if (DEBUG_LOCKS_WARN_ON(!depth
))
3578 hlock
= find_held_lock(curr
, lock
, depth
, &i
);
3580 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3582 lockdep_init_map(lock
, name
, key
, 0);
3583 class = register_lock_class(lock
, subclass
, 0);
3584 hlock
->class_idx
= class - lock_classes
+ 1;
3586 curr
->lockdep_depth
= i
;
3587 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3589 if (reacquire_held_locks(curr
, depth
, i
))
3593 * I took it apart and put it back together again, except now I have
3594 * these 'spare' parts.. where shall I put them.
3596 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
3601 static int __lock_downgrade(struct lockdep_map
*lock
, unsigned long ip
)
3603 struct task_struct
*curr
= current
;
3604 struct held_lock
*hlock
;
3608 depth
= curr
->lockdep_depth
;
3610 * This function is about (re)setting the class of a held lock,
3611 * yet we're not actually holding any locks. Naughty user!
3613 if (DEBUG_LOCKS_WARN_ON(!depth
))
3616 hlock
= find_held_lock(curr
, lock
, depth
, &i
);
3618 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3620 curr
->lockdep_depth
= i
;
3621 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3623 WARN(hlock
->read
, "downgrading a read lock");
3625 hlock
->acquire_ip
= ip
;
3627 if (reacquire_held_locks(curr
, depth
, i
))
3631 * I took it apart and put it back together again, except now I have
3632 * these 'spare' parts.. where shall I put them.
3634 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
3640 * Remove the lock to the list of currently held locks - this gets
3641 * called on mutex_unlock()/spin_unlock*() (or on a failed
3642 * mutex_lock_interruptible()).
3644 * @nested is an hysterical artifact, needs a tree wide cleanup.
3647 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
3649 struct task_struct
*curr
= current
;
3650 struct held_lock
*hlock
;
3654 if (unlikely(!debug_locks
))
3657 depth
= curr
->lockdep_depth
;
3659 * So we're all set to release this lock.. wait what lock? We don't
3660 * own any locks, you've been drinking again?
3662 if (DEBUG_LOCKS_WARN_ON(depth
<= 0))
3663 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3666 * Check whether the lock exists in the current stack
3669 hlock
= find_held_lock(curr
, lock
, depth
, &i
);
3671 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3673 if (hlock
->instance
== lock
)
3674 lock_release_holdtime(hlock
);
3676 WARN(hlock
->pin_count
, "releasing a pinned lock\n");
3678 if (hlock
->references
) {
3679 hlock
->references
--;
3680 if (hlock
->references
) {
3682 * We had, and after removing one, still have
3683 * references, the current lock stack is still
3684 * valid. We're done!
3691 * We have the right lock to unlock, 'hlock' points to it.
3692 * Now we remove it from the stack, and add back the other
3693 * entries (if any), recalculating the hash along the way:
3696 curr
->lockdep_depth
= i
;
3697 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3699 if (reacquire_held_locks(curr
, depth
, i
+ 1))
3703 * We had N bottles of beer on the wall, we drank one, but now
3704 * there's not N-1 bottles of beer left on the wall...
3706 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
3712 static int __lock_is_held(const struct lockdep_map
*lock
, int read
)
3714 struct task_struct
*curr
= current
;
3717 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3718 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3720 if (match_held_lock(hlock
, lock
)) {
3721 if (read
== -1 || hlock
->read
== read
)
3731 static struct pin_cookie
__lock_pin_lock(struct lockdep_map
*lock
)
3733 struct pin_cookie cookie
= NIL_COOKIE
;
3734 struct task_struct
*curr
= current
;
3737 if (unlikely(!debug_locks
))
3740 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3741 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3743 if (match_held_lock(hlock
, lock
)) {
3745 * Grab 16bits of randomness; this is sufficient to not
3746 * be guessable and still allows some pin nesting in
3747 * our u32 pin_count.
3749 cookie
.val
= 1 + (prandom_u32() >> 16);
3750 hlock
->pin_count
+= cookie
.val
;
3755 WARN(1, "pinning an unheld lock\n");
3759 static void __lock_repin_lock(struct lockdep_map
*lock
, struct pin_cookie cookie
)
3761 struct task_struct
*curr
= current
;
3764 if (unlikely(!debug_locks
))
3767 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3768 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3770 if (match_held_lock(hlock
, lock
)) {
3771 hlock
->pin_count
+= cookie
.val
;
3776 WARN(1, "pinning an unheld lock\n");
3779 static void __lock_unpin_lock(struct lockdep_map
*lock
, struct pin_cookie cookie
)
3781 struct task_struct
*curr
= current
;
3784 if (unlikely(!debug_locks
))
3787 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3788 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3790 if (match_held_lock(hlock
, lock
)) {
3791 if (WARN(!hlock
->pin_count
, "unpinning an unpinned lock\n"))
3794 hlock
->pin_count
-= cookie
.val
;
3796 if (WARN((int)hlock
->pin_count
< 0, "pin count corrupted\n"))
3797 hlock
->pin_count
= 0;
3803 WARN(1, "unpinning an unheld lock\n");
3807 * Check whether we follow the irq-flags state precisely:
3809 static void check_flags(unsigned long flags
)
3811 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3812 defined(CONFIG_TRACE_IRQFLAGS)
3816 if (irqs_disabled_flags(flags
)) {
3817 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
3818 printk("possible reason: unannotated irqs-off.\n");
3821 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
3822 printk("possible reason: unannotated irqs-on.\n");
3827 * We dont accurately track softirq state in e.g.
3828 * hardirq contexts (such as on 4KSTACKS), so only
3829 * check if not in hardirq contexts:
3831 if (!hardirq_count()) {
3832 if (softirq_count()) {
3833 /* like the above, but with softirqs */
3834 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
3836 /* lick the above, does it taste good? */
3837 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
3842 print_irqtrace_events(current
);
3846 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
3847 struct lock_class_key
*key
, unsigned int subclass
,
3850 unsigned long flags
;
3852 if (unlikely(current
->lockdep_recursion
))
3855 raw_local_irq_save(flags
);
3856 current
->lockdep_recursion
= 1;
3858 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
3859 check_chain_key(current
);
3860 current
->lockdep_recursion
= 0;
3861 raw_local_irq_restore(flags
);
3863 EXPORT_SYMBOL_GPL(lock_set_class
);
3865 void lock_downgrade(struct lockdep_map
*lock
, unsigned long ip
)
3867 unsigned long flags
;
3869 if (unlikely(current
->lockdep_recursion
))
3872 raw_local_irq_save(flags
);
3873 current
->lockdep_recursion
= 1;
3875 if (__lock_downgrade(lock
, ip
))
3876 check_chain_key(current
);
3877 current
->lockdep_recursion
= 0;
3878 raw_local_irq_restore(flags
);
3880 EXPORT_SYMBOL_GPL(lock_downgrade
);
3883 * We are not always called with irqs disabled - do that here,
3884 * and also avoid lockdep recursion:
3886 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3887 int trylock
, int read
, int check
,
3888 struct lockdep_map
*nest_lock
, unsigned long ip
)
3890 unsigned long flags
;
3892 if (unlikely(current
->lockdep_recursion
))
3895 raw_local_irq_save(flags
);
3898 current
->lockdep_recursion
= 1;
3899 trace_lock_acquire(lock
, subclass
, trylock
, read
, check
, nest_lock
, ip
);
3900 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
3901 irqs_disabled_flags(flags
), nest_lock
, ip
, 0, 0);
3902 current
->lockdep_recursion
= 0;
3903 raw_local_irq_restore(flags
);
3905 EXPORT_SYMBOL_GPL(lock_acquire
);
3907 void lock_release(struct lockdep_map
*lock
, int nested
,
3910 unsigned long flags
;
3912 if (unlikely(current
->lockdep_recursion
))
3915 raw_local_irq_save(flags
);
3917 current
->lockdep_recursion
= 1;
3918 trace_lock_release(lock
, ip
);
3919 if (__lock_release(lock
, nested
, ip
))
3920 check_chain_key(current
);
3921 current
->lockdep_recursion
= 0;
3922 raw_local_irq_restore(flags
);
3924 EXPORT_SYMBOL_GPL(lock_release
);
3926 int lock_is_held_type(const struct lockdep_map
*lock
, int read
)
3928 unsigned long flags
;
3931 if (unlikely(current
->lockdep_recursion
))
3932 return 1; /* avoid false negative lockdep_assert_held() */
3934 raw_local_irq_save(flags
);
3937 current
->lockdep_recursion
= 1;
3938 ret
= __lock_is_held(lock
, read
);
3939 current
->lockdep_recursion
= 0;
3940 raw_local_irq_restore(flags
);
3944 EXPORT_SYMBOL_GPL(lock_is_held_type
);
3946 struct pin_cookie
lock_pin_lock(struct lockdep_map
*lock
)
3948 struct pin_cookie cookie
= NIL_COOKIE
;
3949 unsigned long flags
;
3951 if (unlikely(current
->lockdep_recursion
))
3954 raw_local_irq_save(flags
);
3957 current
->lockdep_recursion
= 1;
3958 cookie
= __lock_pin_lock(lock
);
3959 current
->lockdep_recursion
= 0;
3960 raw_local_irq_restore(flags
);
3964 EXPORT_SYMBOL_GPL(lock_pin_lock
);
3966 void lock_repin_lock(struct lockdep_map
*lock
, struct pin_cookie cookie
)
3968 unsigned long flags
;
3970 if (unlikely(current
->lockdep_recursion
))
3973 raw_local_irq_save(flags
);
3976 current
->lockdep_recursion
= 1;
3977 __lock_repin_lock(lock
, cookie
);
3978 current
->lockdep_recursion
= 0;
3979 raw_local_irq_restore(flags
);
3981 EXPORT_SYMBOL_GPL(lock_repin_lock
);
3983 void lock_unpin_lock(struct lockdep_map
*lock
, struct pin_cookie cookie
)
3985 unsigned long flags
;
3987 if (unlikely(current
->lockdep_recursion
))
3990 raw_local_irq_save(flags
);
3993 current
->lockdep_recursion
= 1;
3994 __lock_unpin_lock(lock
, cookie
);
3995 current
->lockdep_recursion
= 0;
3996 raw_local_irq_restore(flags
);
3998 EXPORT_SYMBOL_GPL(lock_unpin_lock
);
4000 #ifdef CONFIG_LOCK_STAT
4002 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
4005 if (!debug_locks_off())
4007 if (debug_locks_silent
)
4011 pr_warn("=================================\n");
4012 pr_warn("WARNING: bad contention detected!\n");
4013 print_kernel_ident();
4014 pr_warn("---------------------------------\n");
4015 pr_warn("%s/%d is trying to contend lock (",
4016 curr
->comm
, task_pid_nr(curr
));
4017 print_lockdep_cache(lock
);
4020 pr_warn("but there are no locks held!\n");
4021 pr_warn("\nother info that might help us debug this:\n");
4022 lockdep_print_held_locks(curr
);
4024 pr_warn("\nstack backtrace:\n");
4031 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
4033 struct task_struct
*curr
= current
;
4034 struct held_lock
*hlock
;
4035 struct lock_class_stats
*stats
;
4037 int i
, contention_point
, contending_point
;
4039 depth
= curr
->lockdep_depth
;
4041 * Whee, we contended on this lock, except it seems we're not
4042 * actually trying to acquire anything much at all..
4044 if (DEBUG_LOCKS_WARN_ON(!depth
))
4047 hlock
= find_held_lock(curr
, lock
, depth
, &i
);
4049 print_lock_contention_bug(curr
, lock
, ip
);
4053 if (hlock
->instance
!= lock
)
4056 hlock
->waittime_stamp
= lockstat_clock();
4058 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
4059 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
4062 stats
= get_lock_stats(hlock_class(hlock
));
4063 if (contention_point
< LOCKSTAT_POINTS
)
4064 stats
->contention_point
[contention_point
]++;
4065 if (contending_point
< LOCKSTAT_POINTS
)
4066 stats
->contending_point
[contending_point
]++;
4067 if (lock
->cpu
!= smp_processor_id())
4068 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
4072 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
4074 struct task_struct
*curr
= current
;
4075 struct held_lock
*hlock
;
4076 struct lock_class_stats
*stats
;
4078 u64 now
, waittime
= 0;
4081 depth
= curr
->lockdep_depth
;
4083 * Yay, we acquired ownership of this lock we didn't try to
4084 * acquire, how the heck did that happen?
4086 if (DEBUG_LOCKS_WARN_ON(!depth
))
4089 hlock
= find_held_lock(curr
, lock
, depth
, &i
);
4091 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
4095 if (hlock
->instance
!= lock
)
4098 cpu
= smp_processor_id();
4099 if (hlock
->waittime_stamp
) {
4100 now
= lockstat_clock();
4101 waittime
= now
- hlock
->waittime_stamp
;
4102 hlock
->holdtime_stamp
= now
;
4105 trace_lock_acquired(lock
, ip
);
4107 stats
= get_lock_stats(hlock_class(hlock
));
4110 lock_time_inc(&stats
->read_waittime
, waittime
);
4112 lock_time_inc(&stats
->write_waittime
, waittime
);
4114 if (lock
->cpu
!= cpu
)
4115 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
4121 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
4123 unsigned long flags
;
4125 if (unlikely(!lock_stat
))
4128 if (unlikely(current
->lockdep_recursion
))
4131 raw_local_irq_save(flags
);
4133 current
->lockdep_recursion
= 1;
4134 trace_lock_contended(lock
, ip
);
4135 __lock_contended(lock
, ip
);
4136 current
->lockdep_recursion
= 0;
4137 raw_local_irq_restore(flags
);
4139 EXPORT_SYMBOL_GPL(lock_contended
);
4141 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
4143 unsigned long flags
;
4145 if (unlikely(!lock_stat
))
4148 if (unlikely(current
->lockdep_recursion
))
4151 raw_local_irq_save(flags
);
4153 current
->lockdep_recursion
= 1;
4154 __lock_acquired(lock
, ip
);
4155 current
->lockdep_recursion
= 0;
4156 raw_local_irq_restore(flags
);
4158 EXPORT_SYMBOL_GPL(lock_acquired
);
4162 * Used by the testsuite, sanitize the validator state
4163 * after a simulated failure:
4166 void lockdep_reset(void)
4168 unsigned long flags
;
4171 raw_local_irq_save(flags
);
4172 current
->curr_chain_key
= 0;
4173 current
->lockdep_depth
= 0;
4174 current
->lockdep_recursion
= 0;
4175 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
4176 nr_hardirq_chains
= 0;
4177 nr_softirq_chains
= 0;
4178 nr_process_chains
= 0;
4180 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
4181 INIT_HLIST_HEAD(chainhash_table
+ i
);
4182 raw_local_irq_restore(flags
);
4185 static void zap_class(struct lock_class
*class)
4190 * Remove all dependencies this lock is
4193 for (i
= 0; i
< nr_list_entries
; i
++) {
4194 if (list_entries
[i
].class == class)
4195 list_del_rcu(&list_entries
[i
].entry
);
4198 * Unhash the class and remove it from the all_lock_classes list:
4200 hlist_del_rcu(&class->hash_entry
);
4201 list_del_rcu(&class->lock_entry
);
4203 RCU_INIT_POINTER(class->key
, NULL
);
4204 RCU_INIT_POINTER(class->name
, NULL
);
4207 static inline int within(const void *addr
, void *start
, unsigned long size
)
4209 return addr
>= start
&& addr
< start
+ size
;
4213 * Used in module.c to remove lock classes from memory that is going to be
4214 * freed; and possibly re-used by other modules.
4216 * We will have had one sync_sched() before getting here, so we're guaranteed
4217 * nobody will look up these exact classes -- they're properly dead but still
4220 void lockdep_free_key_range(void *start
, unsigned long size
)
4222 struct lock_class
*class;
4223 struct hlist_head
*head
;
4224 unsigned long flags
;
4228 raw_local_irq_save(flags
);
4229 locked
= graph_lock();
4232 * Unhash all classes that were created by this module:
4234 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
4235 head
= classhash_table
+ i
;
4236 hlist_for_each_entry_rcu(class, head
, hash_entry
) {
4237 if (within(class->key
, start
, size
))
4239 else if (within(class->name
, start
, size
))
4246 raw_local_irq_restore(flags
);
4249 * Wait for any possible iterators from look_up_lock_class() to pass
4250 * before continuing to free the memory they refer to.
4252 * sync_sched() is sufficient because the read-side is IRQ disable.
4254 synchronize_sched();
4257 * XXX at this point we could return the resources to the pool;
4258 * instead we leak them. We would need to change to bitmap allocators
4259 * instead of the linear allocators we have now.
4263 void lockdep_reset_lock(struct lockdep_map
*lock
)
4265 struct lock_class
*class;
4266 struct hlist_head
*head
;
4267 unsigned long flags
;
4271 raw_local_irq_save(flags
);
4274 * Remove all classes this lock might have:
4276 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
4278 * If the class exists we look it up and zap it:
4280 class = look_up_lock_class(lock
, j
);
4285 * Debug check: in the end all mapped classes should
4288 locked
= graph_lock();
4289 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
4290 head
= classhash_table
+ i
;
4291 hlist_for_each_entry_rcu(class, head
, hash_entry
) {
4294 for (j
= 0; j
< NR_LOCKDEP_CACHING_CLASSES
; j
++)
4295 match
|= class == lock
->class_cache
[j
];
4297 if (unlikely(match
)) {
4298 if (debug_locks_off_graph_unlock()) {
4300 * We all just reset everything, how did it match?
4312 raw_local_irq_restore(flags
);
4315 void __init
lockdep_init(void)
4317 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4319 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
4320 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
4321 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
4322 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
4323 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
4324 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
4325 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
4327 printk(" memory used by lock dependency info: %lu kB\n",
4328 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
4329 sizeof(struct list_head
) * CLASSHASH_SIZE
+
4330 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
4331 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
4332 sizeof(struct list_head
) * CHAINHASH_SIZE
4333 #ifdef CONFIG_PROVE_LOCKING
4334 + sizeof(struct circular_queue
)
4339 printk(" per task-struct memory footprint: %lu bytes\n",
4340 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
4344 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
4345 const void *mem_to
, struct held_lock
*hlock
)
4347 if (!debug_locks_off())
4349 if (debug_locks_silent
)
4353 pr_warn("=========================\n");
4354 pr_warn("WARNING: held lock freed!\n");
4355 print_kernel_ident();
4356 pr_warn("-------------------------\n");
4357 pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
4358 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
4360 lockdep_print_held_locks(curr
);
4362 pr_warn("\nstack backtrace:\n");
4366 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
4367 const void* lock_from
, unsigned long lock_len
)
4369 return lock_from
+ lock_len
<= mem_from
||
4370 mem_from
+ mem_len
<= lock_from
;
4374 * Called when kernel memory is freed (or unmapped), or if a lock
4375 * is destroyed or reinitialized - this code checks whether there is
4376 * any held lock in the memory range of <from> to <to>:
4378 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
4380 struct task_struct
*curr
= current
;
4381 struct held_lock
*hlock
;
4382 unsigned long flags
;
4385 if (unlikely(!debug_locks
))
4388 raw_local_irq_save(flags
);
4389 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
4390 hlock
= curr
->held_locks
+ i
;
4392 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
4393 sizeof(*hlock
->instance
)))
4396 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
4399 raw_local_irq_restore(flags
);
4401 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
4403 static void print_held_locks_bug(void)
4405 if (!debug_locks_off())
4407 if (debug_locks_silent
)
4411 pr_warn("====================================\n");
4412 pr_warn("WARNING: %s/%d still has locks held!\n",
4413 current
->comm
, task_pid_nr(current
));
4414 print_kernel_ident();
4415 pr_warn("------------------------------------\n");
4416 lockdep_print_held_locks(current
);
4417 pr_warn("\nstack backtrace:\n");
4421 void debug_check_no_locks_held(void)
4423 if (unlikely(current
->lockdep_depth
> 0))
4424 print_held_locks_bug();
4426 EXPORT_SYMBOL_GPL(debug_check_no_locks_held
);
4429 void debug_show_all_locks(void)
4431 struct task_struct
*g
, *p
;
4433 if (unlikely(!debug_locks
)) {
4434 pr_warn("INFO: lockdep is turned off.\n");
4437 pr_warn("\nShowing all locks held in the system:\n");
4440 for_each_process_thread(g
, p
) {
4441 if (!p
->lockdep_depth
)
4443 lockdep_print_held_locks(p
);
4444 touch_nmi_watchdog();
4445 touch_all_softlockup_watchdogs();
4450 pr_warn("=============================================\n\n");
4452 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
4456 * Careful: only use this function if you are sure that
4457 * the task cannot run in parallel!
4459 void debug_show_held_locks(struct task_struct
*task
)
4461 if (unlikely(!debug_locks
)) {
4462 printk("INFO: lockdep is turned off.\n");
4465 lockdep_print_held_locks(task
);
4467 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
4469 asmlinkage __visible
void lockdep_sys_exit(void)
4471 struct task_struct
*curr
= current
;
4473 if (unlikely(curr
->lockdep_depth
)) {
4474 if (!debug_locks_off())
4477 pr_warn("================================================\n");
4478 pr_warn("WARNING: lock held when returning to user space!\n");
4479 print_kernel_ident();
4480 pr_warn("------------------------------------------------\n");
4481 pr_warn("%s/%d is leaving the kernel with locks still held!\n",
4482 curr
->comm
, curr
->pid
);
4483 lockdep_print_held_locks(curr
);
4487 * The lock history for each syscall should be independent. So wipe the
4488 * slate clean on return to userspace.
4490 lockdep_invariant_state(false);
4493 void lockdep_rcu_suspicious(const char *file
, const int line
, const char *s
)
4495 struct task_struct
*curr
= current
;
4497 /* Note: the following can be executed concurrently, so be careful. */
4499 pr_warn("=============================\n");
4500 pr_warn("WARNING: suspicious RCU usage\n");
4501 print_kernel_ident();
4502 pr_warn("-----------------------------\n");
4503 pr_warn("%s:%d %s!\n", file
, line
, s
);
4504 pr_warn("\nother info that might help us debug this:\n\n");
4505 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4506 !rcu_lockdep_current_cpu_online()
4507 ? "RCU used illegally from offline CPU!\n"
4508 : !rcu_is_watching()
4509 ? "RCU used illegally from idle CPU!\n"
4511 rcu_scheduler_active
, debug_locks
);
4514 * If a CPU is in the RCU-free window in idle (ie: in the section
4515 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4516 * considers that CPU to be in an "extended quiescent state",
4517 * which means that RCU will be completely ignoring that CPU.
4518 * Therefore, rcu_read_lock() and friends have absolutely no
4519 * effect on a CPU running in that state. In other words, even if
4520 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4521 * delete data structures out from under it. RCU really has no
4522 * choice here: we need to keep an RCU-free window in idle where
4523 * the CPU may possibly enter into low power mode. This way we can
4524 * notice an extended quiescent state to other CPUs that started a grace
4525 * period. Otherwise we would delay any grace period as long as we run
4528 * So complain bitterly if someone does call rcu_read_lock(),
4529 * rcu_read_lock_bh() and so on from extended quiescent states.
4531 if (!rcu_is_watching())
4532 pr_warn("RCU used illegally from extended quiescent state!\n");
4534 lockdep_print_held_locks(curr
);
4535 pr_warn("\nstack backtrace:\n");
4538 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious
);