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/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
47 #include <linux/kmemcheck.h>
48 #include <linux/random.h>
50 #include <asm/sections.h>
52 #include "lockdep_internals.h"
54 #define CREATE_TRACE_POINTS
55 #include <trace/events/lock.h>
57 #ifdef CONFIG_PROVE_LOCKING
58 int prove_locking
= 1;
59 module_param(prove_locking
, int, 0644);
61 #define prove_locking 0
64 #ifdef CONFIG_LOCK_STAT
66 module_param(lock_stat
, int, 0644);
72 * lockdep_lock: protects the lockdep graph, the hashes and the
73 * class/list/hash allocators.
75 * This is one of the rare exceptions where it's justified
76 * to use a raw spinlock - we really dont want the spinlock
77 * code to recurse back into the lockdep code...
79 static arch_spinlock_t lockdep_lock
= (arch_spinlock_t
)__ARCH_SPIN_LOCK_UNLOCKED
;
81 static int graph_lock(void)
83 arch_spin_lock(&lockdep_lock
);
85 * Make sure that if another CPU detected a bug while
86 * walking the graph we dont change it (while the other
87 * CPU is busy printing out stuff with the graph lock
91 arch_spin_unlock(&lockdep_lock
);
94 /* prevent any recursions within lockdep from causing deadlocks */
95 current
->lockdep_recursion
++;
99 static inline int graph_unlock(void)
101 if (debug_locks
&& !arch_spin_is_locked(&lockdep_lock
)) {
103 * The lockdep graph lock isn't locked while we expect it to
104 * be, we're confused now, bye!
106 return DEBUG_LOCKS_WARN_ON(1);
109 current
->lockdep_recursion
--;
110 arch_spin_unlock(&lockdep_lock
);
115 * Turn lock debugging off and return with 0 if it was off already,
116 * and also release the graph lock:
118 static inline int debug_locks_off_graph_unlock(void)
120 int ret
= debug_locks_off();
122 arch_spin_unlock(&lockdep_lock
);
127 unsigned long nr_list_entries
;
128 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
131 * All data structures here are protected by the global debug_lock.
133 * Mutex key structs only get allocated, once during bootup, and never
134 * get freed - this significantly simplifies the debugging code.
136 unsigned long nr_lock_classes
;
137 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
139 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
141 if (!hlock
->class_idx
) {
143 * Someone passed in garbage, we give up.
145 DEBUG_LOCKS_WARN_ON(1);
148 return lock_classes
+ hlock
->class_idx
- 1;
151 #ifdef CONFIG_LOCK_STAT
152 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
], cpu_lock_stats
);
154 static inline u64
lockstat_clock(void)
156 return local_clock();
159 static int lock_point(unsigned long points
[], unsigned long ip
)
163 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
164 if (points
[i
] == 0) {
175 static void lock_time_inc(struct lock_time
*lt
, u64 time
)
180 if (time
< lt
->min
|| !lt
->nr
)
187 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
192 if (src
->max
> dst
->max
)
195 if (src
->min
< dst
->min
|| !dst
->nr
)
198 dst
->total
+= src
->total
;
202 struct lock_class_stats
lock_stats(struct lock_class
*class)
204 struct lock_class_stats stats
;
207 memset(&stats
, 0, sizeof(struct lock_class_stats
));
208 for_each_possible_cpu(cpu
) {
209 struct lock_class_stats
*pcs
=
210 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
212 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
213 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
215 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
216 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
218 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
219 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
221 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
222 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
224 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
225 stats
.bounces
[i
] += pcs
->bounces
[i
];
231 void clear_lock_stats(struct lock_class
*class)
235 for_each_possible_cpu(cpu
) {
236 struct lock_class_stats
*cpu_stats
=
237 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
239 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
241 memset(class->contention_point
, 0, sizeof(class->contention_point
));
242 memset(class->contending_point
, 0, sizeof(class->contending_point
));
245 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
247 return &get_cpu_var(cpu_lock_stats
)[class - lock_classes
];
250 static void put_lock_stats(struct lock_class_stats
*stats
)
252 put_cpu_var(cpu_lock_stats
);
255 static void lock_release_holdtime(struct held_lock
*hlock
)
257 struct lock_class_stats
*stats
;
263 holdtime
= lockstat_clock() - hlock
->holdtime_stamp
;
265 stats
= get_lock_stats(hlock_class(hlock
));
267 lock_time_inc(&stats
->read_holdtime
, holdtime
);
269 lock_time_inc(&stats
->write_holdtime
, holdtime
);
270 put_lock_stats(stats
);
273 static inline void lock_release_holdtime(struct held_lock
*hlock
)
279 * We keep a global list of all lock classes. The list only grows,
280 * never shrinks. The list is only accessed with the lockdep
281 * spinlock lock held.
283 LIST_HEAD(all_lock_classes
);
286 * The lockdep classes are in a hash-table as well, for fast lookup:
288 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
289 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
290 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
291 #define classhashentry(key) (classhash_table + __classhashfn((key)))
293 static struct hlist_head classhash_table
[CLASSHASH_SIZE
];
296 * We put the lock dependency chains into a hash-table as well, to cache
299 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
300 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
301 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
302 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
304 static struct hlist_head chainhash_table
[CHAINHASH_SIZE
];
307 * The hash key of the lock dependency chains is a hash itself too:
308 * it's a hash of all locks taken up to that lock, including that lock.
309 * It's a 64-bit hash, because it's important for the keys to be
312 #define iterate_chain_key(key1, key2) \
313 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
314 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
317 void lockdep_off(void)
319 current
->lockdep_recursion
++;
321 EXPORT_SYMBOL(lockdep_off
);
323 void lockdep_on(void)
325 current
->lockdep_recursion
--;
327 EXPORT_SYMBOL(lockdep_on
);
330 * Debugging switches:
334 #define VERY_VERBOSE 0
337 # define HARDIRQ_VERBOSE 1
338 # define SOFTIRQ_VERBOSE 1
339 # define RECLAIM_VERBOSE 1
341 # define HARDIRQ_VERBOSE 0
342 # define SOFTIRQ_VERBOSE 0
343 # define RECLAIM_VERBOSE 0
346 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_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
);
507 if (class->name_version
> 1)
508 printk("#%d", class->name_version
);
510 printk("/%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
);
521 __print_lock_name(class);
522 printk("){%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
);
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("<RELEASED>\n");
553 print_lock_name(lock_classes
+ class_idx
- 1);
555 print_ip_sym(hlock
->acquire_ip
);
558 static void lockdep_print_held_locks(struct task_struct
*curr
)
560 int i
, depth
= curr
->lockdep_depth
;
563 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
566 printk("%d lock%s held by %s/%d:\n",
567 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
569 for (i
= 0; i
< depth
; i
++) {
571 print_lock(curr
->held_locks
+ i
);
575 static void print_kernel_ident(void)
577 printk("%s %.*s %s\n", init_utsname()->release
,
578 (int)strcspn(init_utsname()->version
, " "),
579 init_utsname()->version
,
583 static int very_verbose(struct lock_class
*class)
586 return class_filter(class);
592 * Is this the address of a static object:
595 static int static_obj(void *obj
)
597 unsigned long start
= (unsigned long) &_stext
,
598 end
= (unsigned long) &_end
,
599 addr
= (unsigned long) obj
;
604 if ((addr
>= start
) && (addr
< end
))
607 if (arch_is_kernel_data(addr
))
611 * in-kernel percpu var?
613 if (is_kernel_percpu_address(addr
))
617 * module static or percpu var?
619 return is_module_address(addr
) || is_module_percpu_address(addr
);
624 * To make lock name printouts unique, we calculate a unique
625 * class->name_version generation counter:
627 static int count_matching_names(struct lock_class
*new_class
)
629 struct lock_class
*class;
632 if (!new_class
->name
)
635 list_for_each_entry_rcu(class, &all_lock_classes
, lock_entry
) {
636 if (new_class
->key
- new_class
->subclass
== class->key
)
637 return class->name_version
;
638 if (class->name
&& !strcmp(class->name
, new_class
->name
))
639 count
= max(count
, class->name_version
);
646 * Register a lock's class in the hash-table, if the class is not present
647 * yet. Otherwise we look it up. We cache the result in the lock object
648 * itself, so actual lookup of the hash should be once per lock object.
650 static inline struct lock_class
*
651 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
653 struct lockdep_subclass_key
*key
;
654 struct hlist_head
*hash_head
;
655 struct lock_class
*class;
657 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
660 "BUG: looking up invalid subclass: %u\n", subclass
);
662 "turning off the locking correctness validator.\n");
668 * Static locks do not have their class-keys yet - for them the key
669 * is the lock object itself:
671 if (unlikely(!lock
->key
))
672 lock
->key
= (void *)lock
;
675 * NOTE: the class-key must be unique. For dynamic locks, a static
676 * lock_class_key variable is passed in through the mutex_init()
677 * (or spin_lock_init()) call - which acts as the key. For static
678 * locks we use the lock object itself as the key.
680 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
681 sizeof(struct lockdep_map
));
683 key
= lock
->key
->subkeys
+ subclass
;
685 hash_head
= classhashentry(key
);
688 * We do an RCU walk of the hash, see lockdep_free_key_range().
690 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
693 hlist_for_each_entry_rcu(class, hash_head
, hash_entry
) {
694 if (class->key
== key
) {
696 * Huh! same key, different name? Did someone trample
697 * on some memory? We're most confused.
699 WARN_ON_ONCE(class->name
!= lock
->name
);
708 * Register a lock's class in the hash-table, if the class is not present
709 * yet. Otherwise we look it up. We cache the result in the lock object
710 * itself, so actual lookup of the hash should be once per lock object.
712 static struct lock_class
*
713 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
715 struct lockdep_subclass_key
*key
;
716 struct hlist_head
*hash_head
;
717 struct lock_class
*class;
719 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
721 class = look_up_lock_class(lock
, subclass
);
723 goto out_set_class_cache
;
726 * Debug-check: all keys must be persistent!
728 if (!static_obj(lock
->key
)) {
730 printk("INFO: trying to register non-static key.\n");
731 printk("the code is fine but needs lockdep annotation.\n");
732 printk("turning off the locking correctness validator.\n");
738 key
= lock
->key
->subkeys
+ subclass
;
739 hash_head
= classhashentry(key
);
745 * We have to do the hash-walk again, to avoid races
748 hlist_for_each_entry_rcu(class, hash_head
, hash_entry
) {
749 if (class->key
== key
)
754 * Allocate a new key from the static array, and add it to
757 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
758 if (!debug_locks_off_graph_unlock()) {
762 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
766 class = lock_classes
+ nr_lock_classes
++;
767 debug_atomic_inc(nr_unused_locks
);
769 class->name
= lock
->name
;
770 class->subclass
= subclass
;
771 INIT_LIST_HEAD(&class->lock_entry
);
772 INIT_LIST_HEAD(&class->locks_before
);
773 INIT_LIST_HEAD(&class->locks_after
);
774 class->name_version
= count_matching_names(class);
776 * We use RCU's safe list-add method to make
777 * parallel walking of the hash-list safe:
779 hlist_add_head_rcu(&class->hash_entry
, hash_head
);
781 * Add it to the global list of classes:
783 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
785 if (verbose(class)) {
788 printk("\nnew class %p: %s", class->key
, class->name
);
789 if (class->name_version
> 1)
790 printk("#%d", class->name_version
);
802 if (!subclass
|| force
)
803 lock
->class_cache
[0] = class;
804 else if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
805 lock
->class_cache
[subclass
] = class;
808 * Hash collision, did we smoke some? We found a class with a matching
809 * hash but the subclass -- which is hashed in -- didn't match.
811 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
817 #ifdef CONFIG_PROVE_LOCKING
819 * Allocate a lockdep entry. (assumes the graph_lock held, returns
820 * with NULL on failure)
822 static struct lock_list
*alloc_list_entry(void)
824 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
825 if (!debug_locks_off_graph_unlock())
828 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
832 return list_entries
+ nr_list_entries
++;
836 * Add a new dependency to the head of the list:
838 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
839 struct list_head
*head
, unsigned long ip
,
840 int distance
, struct stack_trace
*trace
)
842 struct lock_list
*entry
;
844 * Lock not present yet - get a new dependency struct and
845 * add it to the list:
847 entry
= alloc_list_entry();
852 entry
->distance
= distance
;
853 entry
->trace
= *trace
;
855 * Both allocation and removal are done under the graph lock; but
856 * iteration is under RCU-sched; see look_up_lock_class() and
857 * lockdep_free_key_range().
859 list_add_tail_rcu(&entry
->entry
, head
);
865 * For good efficiency of modular, we use power of 2
867 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
868 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
871 * The circular_queue and helpers is used to implement the
872 * breadth-first search(BFS)algorithem, by which we can build
873 * the shortest path from the next lock to be acquired to the
874 * previous held lock if there is a circular between them.
876 struct circular_queue
{
877 unsigned long element
[MAX_CIRCULAR_QUEUE_SIZE
];
878 unsigned int front
, rear
;
881 static struct circular_queue lock_cq
;
883 unsigned int max_bfs_queue_depth
;
885 static unsigned int lockdep_dependency_gen_id
;
887 static inline void __cq_init(struct circular_queue
*cq
)
889 cq
->front
= cq
->rear
= 0;
890 lockdep_dependency_gen_id
++;
893 static inline int __cq_empty(struct circular_queue
*cq
)
895 return (cq
->front
== cq
->rear
);
898 static inline int __cq_full(struct circular_queue
*cq
)
900 return ((cq
->rear
+ 1) & CQ_MASK
) == cq
->front
;
903 static inline int __cq_enqueue(struct circular_queue
*cq
, unsigned long elem
)
908 cq
->element
[cq
->rear
] = elem
;
909 cq
->rear
= (cq
->rear
+ 1) & CQ_MASK
;
913 static inline int __cq_dequeue(struct circular_queue
*cq
, unsigned long *elem
)
918 *elem
= cq
->element
[cq
->front
];
919 cq
->front
= (cq
->front
+ 1) & CQ_MASK
;
923 static inline unsigned int __cq_get_elem_count(struct circular_queue
*cq
)
925 return (cq
->rear
- cq
->front
) & CQ_MASK
;
928 static inline void mark_lock_accessed(struct lock_list
*lock
,
929 struct lock_list
*parent
)
933 nr
= lock
- list_entries
;
934 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
935 lock
->parent
= parent
;
936 lock
->class->dep_gen_id
= lockdep_dependency_gen_id
;
939 static inline unsigned long lock_accessed(struct lock_list
*lock
)
943 nr
= lock
- list_entries
;
944 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
945 return lock
->class->dep_gen_id
== lockdep_dependency_gen_id
;
948 static inline struct lock_list
*get_lock_parent(struct lock_list
*child
)
950 return child
->parent
;
953 static inline int get_lock_depth(struct lock_list
*child
)
956 struct lock_list
*parent
;
958 while ((parent
= get_lock_parent(child
))) {
965 static int __bfs(struct lock_list
*source_entry
,
967 int (*match
)(struct lock_list
*entry
, void *data
),
968 struct lock_list
**target_entry
,
971 struct lock_list
*entry
;
972 struct list_head
*head
;
973 struct circular_queue
*cq
= &lock_cq
;
976 if (match(source_entry
, data
)) {
977 *target_entry
= source_entry
;
983 head
= &source_entry
->class->locks_after
;
985 head
= &source_entry
->class->locks_before
;
987 if (list_empty(head
))
991 __cq_enqueue(cq
, (unsigned long)source_entry
);
993 while (!__cq_empty(cq
)) {
994 struct lock_list
*lock
;
996 __cq_dequeue(cq
, (unsigned long *)&lock
);
1004 head
= &lock
->class->locks_after
;
1006 head
= &lock
->class->locks_before
;
1008 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1010 list_for_each_entry_rcu(entry
, head
, entry
) {
1011 if (!lock_accessed(entry
)) {
1012 unsigned int cq_depth
;
1013 mark_lock_accessed(entry
, lock
);
1014 if (match(entry
, data
)) {
1015 *target_entry
= entry
;
1020 if (__cq_enqueue(cq
, (unsigned long)entry
)) {
1024 cq_depth
= __cq_get_elem_count(cq
);
1025 if (max_bfs_queue_depth
< cq_depth
)
1026 max_bfs_queue_depth
= cq_depth
;
1034 static inline int __bfs_forwards(struct lock_list
*src_entry
,
1036 int (*match
)(struct lock_list
*entry
, void *data
),
1037 struct lock_list
**target_entry
)
1039 return __bfs(src_entry
, data
, match
, target_entry
, 1);
1043 static inline int __bfs_backwards(struct lock_list
*src_entry
,
1045 int (*match
)(struct lock_list
*entry
, void *data
),
1046 struct lock_list
**target_entry
)
1048 return __bfs(src_entry
, data
, match
, target_entry
, 0);
1053 * Recursive, forwards-direction lock-dependency checking, used for
1054 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1059 * Print a dependency chain entry (this is only done when a deadlock
1060 * has been detected):
1063 print_circular_bug_entry(struct lock_list
*target
, int depth
)
1065 if (debug_locks_silent
)
1067 printk("\n-> #%u", depth
);
1068 print_lock_name(target
->class);
1070 print_stack_trace(&target
->trace
, 6);
1076 print_circular_lock_scenario(struct held_lock
*src
,
1077 struct held_lock
*tgt
,
1078 struct lock_list
*prt
)
1080 struct lock_class
*source
= hlock_class(src
);
1081 struct lock_class
*target
= hlock_class(tgt
);
1082 struct lock_class
*parent
= prt
->class;
1085 * A direct locking problem where unsafe_class lock is taken
1086 * directly by safe_class lock, then all we need to show
1087 * is the deadlock scenario, as it is obvious that the
1088 * unsafe lock is taken under the safe lock.
1090 * But if there is a chain instead, where the safe lock takes
1091 * an intermediate lock (middle_class) where this lock is
1092 * not the same as the safe lock, then the lock chain is
1093 * used to describe the problem. Otherwise we would need
1094 * to show a different CPU case for each link in the chain
1095 * from the safe_class lock to the unsafe_class lock.
1097 if (parent
!= source
) {
1098 printk("Chain exists of:\n ");
1099 __print_lock_name(source
);
1101 __print_lock_name(parent
);
1103 __print_lock_name(target
);
1107 printk(" Possible unsafe locking scenario:\n\n");
1108 printk(" CPU0 CPU1\n");
1109 printk(" ---- ----\n");
1111 __print_lock_name(target
);
1114 __print_lock_name(parent
);
1117 __print_lock_name(target
);
1120 __print_lock_name(source
);
1122 printk("\n *** DEADLOCK ***\n\n");
1126 * When a circular dependency is detected, print the
1130 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
,
1131 struct held_lock
*check_src
,
1132 struct held_lock
*check_tgt
)
1134 struct task_struct
*curr
= current
;
1136 if (debug_locks_silent
)
1140 printk("======================================================\n");
1141 printk("[ INFO: possible circular locking dependency detected ]\n");
1142 print_kernel_ident();
1143 printk("-------------------------------------------------------\n");
1144 printk("%s/%d is trying to acquire lock:\n",
1145 curr
->comm
, task_pid_nr(curr
));
1146 print_lock(check_src
);
1147 printk("\nbut task is already holding lock:\n");
1148 print_lock(check_tgt
);
1149 printk("\nwhich lock already depends on the new lock.\n\n");
1150 printk("\nthe existing dependency chain (in reverse order) is:\n");
1152 print_circular_bug_entry(entry
, depth
);
1157 static inline int class_equal(struct lock_list
*entry
, void *data
)
1159 return entry
->class == data
;
1162 static noinline
int print_circular_bug(struct lock_list
*this,
1163 struct lock_list
*target
,
1164 struct held_lock
*check_src
,
1165 struct held_lock
*check_tgt
)
1167 struct task_struct
*curr
= current
;
1168 struct lock_list
*parent
;
1169 struct lock_list
*first_parent
;
1172 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1175 if (!save_trace(&this->trace
))
1178 depth
= get_lock_depth(target
);
1180 print_circular_bug_header(target
, depth
, check_src
, check_tgt
);
1182 parent
= get_lock_parent(target
);
1183 first_parent
= parent
;
1186 print_circular_bug_entry(parent
, --depth
);
1187 parent
= get_lock_parent(parent
);
1190 printk("\nother info that might help us debug this:\n\n");
1191 print_circular_lock_scenario(check_src
, check_tgt
,
1194 lockdep_print_held_locks(curr
);
1196 printk("\nstack backtrace:\n");
1202 static noinline
int print_bfs_bug(int ret
)
1204 if (!debug_locks_off_graph_unlock())
1208 * Breadth-first-search failed, graph got corrupted?
1210 WARN(1, "lockdep bfs error:%d\n", ret
);
1215 static int noop_count(struct lock_list
*entry
, void *data
)
1217 (*(unsigned long *)data
)++;
1221 static unsigned long __lockdep_count_forward_deps(struct lock_list
*this)
1223 unsigned long count
= 0;
1224 struct lock_list
*uninitialized_var(target_entry
);
1226 __bfs_forwards(this, (void *)&count
, noop_count
, &target_entry
);
1230 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1232 unsigned long ret
, flags
;
1233 struct lock_list
this;
1238 local_irq_save(flags
);
1239 arch_spin_lock(&lockdep_lock
);
1240 ret
= __lockdep_count_forward_deps(&this);
1241 arch_spin_unlock(&lockdep_lock
);
1242 local_irq_restore(flags
);
1247 static unsigned long __lockdep_count_backward_deps(struct lock_list
*this)
1249 unsigned long count
= 0;
1250 struct lock_list
*uninitialized_var(target_entry
);
1252 __bfs_backwards(this, (void *)&count
, noop_count
, &target_entry
);
1257 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1259 unsigned long ret
, flags
;
1260 struct lock_list
this;
1265 local_irq_save(flags
);
1266 arch_spin_lock(&lockdep_lock
);
1267 ret
= __lockdep_count_backward_deps(&this);
1268 arch_spin_unlock(&lockdep_lock
);
1269 local_irq_restore(flags
);
1275 * Prove that the dependency graph starting at <entry> can not
1276 * lead to <target>. Print an error and return 0 if it does.
1279 check_noncircular(struct lock_list
*root
, struct lock_class
*target
,
1280 struct lock_list
**target_entry
)
1284 debug_atomic_inc(nr_cyclic_checks
);
1286 result
= __bfs_forwards(root
, target
, class_equal
, target_entry
);
1291 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1293 * Forwards and backwards subgraph searching, for the purposes of
1294 * proving that two subgraphs can be connected by a new dependency
1295 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1298 static inline int usage_match(struct lock_list
*entry
, void *bit
)
1300 return entry
->class->usage_mask
& (1 << (enum lock_usage_bit
)bit
);
1306 * Find a node in the forwards-direction dependency sub-graph starting
1307 * at @root->class that matches @bit.
1309 * Return 0 if such a node exists in the subgraph, and put that node
1310 * into *@target_entry.
1312 * Return 1 otherwise and keep *@target_entry unchanged.
1313 * Return <0 on error.
1316 find_usage_forwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1317 struct lock_list
**target_entry
)
1321 debug_atomic_inc(nr_find_usage_forwards_checks
);
1323 result
= __bfs_forwards(root
, (void *)bit
, usage_match
, target_entry
);
1329 * Find a node in the backwards-direction dependency sub-graph starting
1330 * at @root->class that matches @bit.
1332 * Return 0 if such a node exists in the subgraph, and put that node
1333 * into *@target_entry.
1335 * Return 1 otherwise and keep *@target_entry unchanged.
1336 * Return <0 on error.
1339 find_usage_backwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1340 struct lock_list
**target_entry
)
1344 debug_atomic_inc(nr_find_usage_backwards_checks
);
1346 result
= __bfs_backwards(root
, (void *)bit
, usage_match
, target_entry
);
1351 static void print_lock_class_header(struct lock_class
*class, int depth
)
1355 printk("%*s->", depth
, "");
1356 print_lock_name(class);
1357 printk(" ops: %lu", class->ops
);
1360 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
1361 if (class->usage_mask
& (1 << bit
)) {
1364 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
1365 len
+= printk(" at:\n");
1366 print_stack_trace(class->usage_traces
+ bit
, len
);
1369 printk("%*s }\n", depth
, "");
1371 printk("%*s ... key at: ",depth
,"");
1372 print_ip_sym((unsigned long)class->key
);
1376 * printk the shortest lock dependencies from @start to @end in reverse order:
1379 print_shortest_lock_dependencies(struct lock_list
*leaf
,
1380 struct lock_list
*root
)
1382 struct lock_list
*entry
= leaf
;
1385 /*compute depth from generated tree by BFS*/
1386 depth
= get_lock_depth(leaf
);
1389 print_lock_class_header(entry
->class, depth
);
1390 printk("%*s ... acquired at:\n", depth
, "");
1391 print_stack_trace(&entry
->trace
, 2);
1394 if (depth
== 0 && (entry
!= root
)) {
1395 printk("lockdep:%s bad path found in chain graph\n", __func__
);
1399 entry
= get_lock_parent(entry
);
1401 } while (entry
&& (depth
>= 0));
1407 print_irq_lock_scenario(struct lock_list
*safe_entry
,
1408 struct lock_list
*unsafe_entry
,
1409 struct lock_class
*prev_class
,
1410 struct lock_class
*next_class
)
1412 struct lock_class
*safe_class
= safe_entry
->class;
1413 struct lock_class
*unsafe_class
= unsafe_entry
->class;
1414 struct lock_class
*middle_class
= prev_class
;
1416 if (middle_class
== safe_class
)
1417 middle_class
= next_class
;
1420 * A direct locking problem where unsafe_class lock is taken
1421 * directly by safe_class lock, then all we need to show
1422 * is the deadlock scenario, as it is obvious that the
1423 * unsafe lock is taken under the safe lock.
1425 * But if there is a chain instead, where the safe lock takes
1426 * an intermediate lock (middle_class) where this lock is
1427 * not the same as the safe lock, then the lock chain is
1428 * used to describe the problem. Otherwise we would need
1429 * to show a different CPU case for each link in the chain
1430 * from the safe_class lock to the unsafe_class lock.
1432 if (middle_class
!= unsafe_class
) {
1433 printk("Chain exists of:\n ");
1434 __print_lock_name(safe_class
);
1436 __print_lock_name(middle_class
);
1438 __print_lock_name(unsafe_class
);
1442 printk(" Possible interrupt unsafe locking scenario:\n\n");
1443 printk(" CPU0 CPU1\n");
1444 printk(" ---- ----\n");
1446 __print_lock_name(unsafe_class
);
1448 printk(" local_irq_disable();\n");
1450 __print_lock_name(safe_class
);
1453 __print_lock_name(middle_class
);
1455 printk(" <Interrupt>\n");
1457 __print_lock_name(safe_class
);
1459 printk("\n *** DEADLOCK ***\n\n");
1463 print_bad_irq_dependency(struct task_struct
*curr
,
1464 struct lock_list
*prev_root
,
1465 struct lock_list
*next_root
,
1466 struct lock_list
*backwards_entry
,
1467 struct lock_list
*forwards_entry
,
1468 struct held_lock
*prev
,
1469 struct held_lock
*next
,
1470 enum lock_usage_bit bit1
,
1471 enum lock_usage_bit bit2
,
1472 const char *irqclass
)
1474 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1478 printk("======================================================\n");
1479 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1480 irqclass
, irqclass
);
1481 print_kernel_ident();
1482 printk("------------------------------------------------------\n");
1483 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1484 curr
->comm
, task_pid_nr(curr
),
1485 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1486 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1487 curr
->hardirqs_enabled
,
1488 curr
->softirqs_enabled
);
1491 printk("\nand this task is already holding:\n");
1493 printk("which would create a new lock dependency:\n");
1494 print_lock_name(hlock_class(prev
));
1496 print_lock_name(hlock_class(next
));
1499 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1501 print_lock_name(backwards_entry
->class);
1502 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1504 print_stack_trace(backwards_entry
->class->usage_traces
+ bit1
, 1);
1506 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1507 print_lock_name(forwards_entry
->class);
1508 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1511 print_stack_trace(forwards_entry
->class->usage_traces
+ bit2
, 1);
1513 printk("\nother info that might help us debug this:\n\n");
1514 print_irq_lock_scenario(backwards_entry
, forwards_entry
,
1515 hlock_class(prev
), hlock_class(next
));
1517 lockdep_print_held_locks(curr
);
1519 printk("\nthe dependencies between %s-irq-safe lock", irqclass
);
1520 printk(" and the holding lock:\n");
1521 if (!save_trace(&prev_root
->trace
))
1523 print_shortest_lock_dependencies(backwards_entry
, prev_root
);
1525 printk("\nthe dependencies between the lock to be acquired");
1526 printk(" and %s-irq-unsafe lock:\n", irqclass
);
1527 if (!save_trace(&next_root
->trace
))
1529 print_shortest_lock_dependencies(forwards_entry
, next_root
);
1531 printk("\nstack backtrace:\n");
1538 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1539 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1540 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1543 struct lock_list
this, that
;
1544 struct lock_list
*uninitialized_var(target_entry
);
1545 struct lock_list
*uninitialized_var(target_entry1
);
1549 this.class = hlock_class(prev
);
1550 ret
= find_usage_backwards(&this, bit_backwards
, &target_entry
);
1552 return print_bfs_bug(ret
);
1557 that
.class = hlock_class(next
);
1558 ret
= find_usage_forwards(&that
, bit_forwards
, &target_entry1
);
1560 return print_bfs_bug(ret
);
1564 return print_bad_irq_dependency(curr
, &this, &that
,
1565 target_entry
, target_entry1
,
1567 bit_backwards
, bit_forwards
, irqclass
);
1570 static const char *state_names
[] = {
1571 #define LOCKDEP_STATE(__STATE) \
1572 __stringify(__STATE),
1573 #include "lockdep_states.h"
1574 #undef LOCKDEP_STATE
1577 static const char *state_rnames
[] = {
1578 #define LOCKDEP_STATE(__STATE) \
1579 __stringify(__STATE)"-READ",
1580 #include "lockdep_states.h"
1581 #undef LOCKDEP_STATE
1584 static inline const char *state_name(enum lock_usage_bit bit
)
1586 return (bit
& 1) ? state_rnames
[bit
>> 2] : state_names
[bit
>> 2];
1589 static int exclusive_bit(int new_bit
)
1597 * bit 0 - write/read
1598 * bit 1 - used_in/enabled
1602 int state
= new_bit
& ~3;
1603 int dir
= new_bit
& 2;
1606 * keep state, bit flip the direction and strip read.
1608 return state
| (dir
^ 2);
1611 static int check_irq_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1612 struct held_lock
*next
, enum lock_usage_bit bit
)
1615 * Prove that the new dependency does not connect a hardirq-safe
1616 * lock with a hardirq-unsafe lock - to achieve this we search
1617 * the backwards-subgraph starting at <prev>, and the
1618 * forwards-subgraph starting at <next>:
1620 if (!check_usage(curr
, prev
, next
, bit
,
1621 exclusive_bit(bit
), state_name(bit
)))
1627 * Prove that the new dependency does not connect a hardirq-safe-read
1628 * lock with a hardirq-unsafe lock - to achieve this we search
1629 * the backwards-subgraph starting at <prev>, and the
1630 * forwards-subgraph starting at <next>:
1632 if (!check_usage(curr
, prev
, next
, bit
,
1633 exclusive_bit(bit
), state_name(bit
)))
1640 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1641 struct held_lock
*next
)
1643 #define LOCKDEP_STATE(__STATE) \
1644 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1646 #include "lockdep_states.h"
1647 #undef LOCKDEP_STATE
1652 static void inc_chains(void)
1654 if (current
->hardirq_context
)
1655 nr_hardirq_chains
++;
1657 if (current
->softirq_context
)
1658 nr_softirq_chains
++;
1660 nr_process_chains
++;
1667 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1668 struct held_lock
*next
)
1673 static inline void inc_chains(void)
1675 nr_process_chains
++;
1681 print_deadlock_scenario(struct held_lock
*nxt
,
1682 struct held_lock
*prv
)
1684 struct lock_class
*next
= hlock_class(nxt
);
1685 struct lock_class
*prev
= hlock_class(prv
);
1687 printk(" Possible unsafe locking scenario:\n\n");
1691 __print_lock_name(prev
);
1694 __print_lock_name(next
);
1696 printk("\n *** DEADLOCK ***\n\n");
1697 printk(" May be due to missing lock nesting notation\n\n");
1701 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1702 struct held_lock
*next
)
1704 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1708 printk("=============================================\n");
1709 printk("[ INFO: possible recursive locking detected ]\n");
1710 print_kernel_ident();
1711 printk("---------------------------------------------\n");
1712 printk("%s/%d is trying to acquire lock:\n",
1713 curr
->comm
, task_pid_nr(curr
));
1715 printk("\nbut task is already holding lock:\n");
1718 printk("\nother info that might help us debug this:\n");
1719 print_deadlock_scenario(next
, prev
);
1720 lockdep_print_held_locks(curr
);
1722 printk("\nstack backtrace:\n");
1729 * Check whether we are holding such a class already.
1731 * (Note that this has to be done separately, because the graph cannot
1732 * detect such classes of deadlocks.)
1734 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1737 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1738 struct lockdep_map
*next_instance
, int read
)
1740 struct held_lock
*prev
;
1741 struct held_lock
*nest
= NULL
;
1744 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1745 prev
= curr
->held_locks
+ i
;
1747 if (prev
->instance
== next
->nest_lock
)
1750 if (hlock_class(prev
) != hlock_class(next
))
1754 * Allow read-after-read recursion of the same
1755 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1757 if ((read
== 2) && prev
->read
)
1761 * We're holding the nest_lock, which serializes this lock's
1762 * nesting behaviour.
1767 return print_deadlock_bug(curr
, prev
, next
);
1773 * There was a chain-cache miss, and we are about to add a new dependency
1774 * to a previous lock. We recursively validate the following rules:
1776 * - would the adding of the <prev> -> <next> dependency create a
1777 * circular dependency in the graph? [== circular deadlock]
1779 * - does the new prev->next dependency connect any hardirq-safe lock
1780 * (in the full backwards-subgraph starting at <prev>) with any
1781 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1782 * <next>)? [== illegal lock inversion with hardirq contexts]
1784 * - does the new prev->next dependency connect any softirq-safe lock
1785 * (in the full backwards-subgraph starting at <prev>) with any
1786 * softirq-unsafe lock (in the full forwards-subgraph starting at
1787 * <next>)? [== illegal lock inversion with softirq contexts]
1789 * any of these scenarios could lead to a deadlock.
1791 * Then if all the validations pass, we add the forwards and backwards
1795 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1796 struct held_lock
*next
, int distance
, int *stack_saved
)
1798 struct lock_list
*entry
;
1800 struct lock_list
this;
1801 struct lock_list
*uninitialized_var(target_entry
);
1803 * Static variable, serialized by the graph_lock().
1805 * We use this static variable to save the stack trace in case
1806 * we call into this function multiple times due to encountering
1807 * trylocks in the held lock stack.
1809 static struct stack_trace trace
;
1812 * Prove that the new <prev> -> <next> dependency would not
1813 * create a circular dependency in the graph. (We do this by
1814 * forward-recursing into the graph starting at <next>, and
1815 * checking whether we can reach <prev>.)
1817 * We are using global variables to control the recursion, to
1818 * keep the stackframe size of the recursive functions low:
1820 this.class = hlock_class(next
);
1822 ret
= check_noncircular(&this, hlock_class(prev
), &target_entry
);
1824 return print_circular_bug(&this, target_entry
, next
, prev
);
1825 else if (unlikely(ret
< 0))
1826 return print_bfs_bug(ret
);
1828 if (!check_prev_add_irq(curr
, prev
, next
))
1832 * For recursive read-locks we do all the dependency checks,
1833 * but we dont store read-triggered dependencies (only
1834 * write-triggered dependencies). This ensures that only the
1835 * write-side dependencies matter, and that if for example a
1836 * write-lock never takes any other locks, then the reads are
1837 * equivalent to a NOP.
1839 if (next
->read
== 2 || prev
->read
== 2)
1842 * Is the <prev> -> <next> dependency already present?
1844 * (this may occur even though this is a new chain: consider
1845 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1846 * chains - the second one will be new, but L1 already has
1847 * L2 added to its dependency list, due to the first chain.)
1849 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1850 if (entry
->class == hlock_class(next
)) {
1852 entry
->distance
= 1;
1857 if (!*stack_saved
) {
1858 if (!save_trace(&trace
))
1864 * Ok, all validations passed, add the new lock
1865 * to the previous lock's dependency list:
1867 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1868 &hlock_class(prev
)->locks_after
,
1869 next
->acquire_ip
, distance
, &trace
);
1874 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1875 &hlock_class(next
)->locks_before
,
1876 next
->acquire_ip
, distance
, &trace
);
1881 * Debugging printouts:
1883 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1884 /* We drop graph lock, so another thread can overwrite trace. */
1887 printk("\n new dependency: ");
1888 print_lock_name(hlock_class(prev
));
1890 print_lock_name(hlock_class(next
));
1893 return graph_lock();
1899 * Add the dependency to all directly-previous locks that are 'relevant'.
1900 * The ones that are relevant are (in increasing distance from curr):
1901 * all consecutive trylock entries and the final non-trylock entry - or
1902 * the end of this context's lock-chain - whichever comes first.
1905 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1907 int depth
= curr
->lockdep_depth
;
1908 int stack_saved
= 0;
1909 struct held_lock
*hlock
;
1914 * Depth must not be zero for a non-head lock:
1919 * At least two relevant locks must exist for this
1922 if (curr
->held_locks
[depth
].irq_context
!=
1923 curr
->held_locks
[depth
-1].irq_context
)
1927 int distance
= curr
->lockdep_depth
- depth
+ 1;
1928 hlock
= curr
->held_locks
+ depth
- 1;
1930 * Only non-recursive-read entries get new dependencies
1933 if (hlock
->read
!= 2 && hlock
->check
) {
1934 if (!check_prev_add(curr
, hlock
, next
,
1935 distance
, &stack_saved
))
1938 * Stop after the first non-trylock entry,
1939 * as non-trylock entries have added their
1940 * own direct dependencies already, so this
1941 * lock is connected to them indirectly:
1943 if (!hlock
->trylock
)
1948 * End of lock-stack?
1953 * Stop the search if we cross into another context:
1955 if (curr
->held_locks
[depth
].irq_context
!=
1956 curr
->held_locks
[depth
-1].irq_context
)
1961 if (!debug_locks_off_graph_unlock())
1965 * Clearly we all shouldn't be here, but since we made it we
1966 * can reliable say we messed up our state. See the above two
1967 * gotos for reasons why we could possibly end up here.
1974 unsigned long nr_lock_chains
;
1975 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1976 int nr_chain_hlocks
;
1977 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1979 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1981 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1985 * Returns the index of the first held_lock of the current chain
1987 static inline int get_first_held_lock(struct task_struct
*curr
,
1988 struct held_lock
*hlock
)
1991 struct held_lock
*hlock_curr
;
1993 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
1994 hlock_curr
= curr
->held_locks
+ i
;
1995 if (hlock_curr
->irq_context
!= hlock
->irq_context
)
2003 #ifdef CONFIG_DEBUG_LOCKDEP
2005 * Returns the next chain_key iteration
2007 static u64
print_chain_key_iteration(int class_idx
, u64 chain_key
)
2009 u64 new_chain_key
= iterate_chain_key(chain_key
, class_idx
);
2011 printk(" class_idx:%d -> chain_key:%016Lx",
2013 (unsigned long long)new_chain_key
);
2014 return new_chain_key
;
2018 print_chain_keys_held_locks(struct task_struct
*curr
, struct held_lock
*hlock_next
)
2020 struct held_lock
*hlock
;
2022 int depth
= curr
->lockdep_depth
;
2025 printk("depth: %u\n", depth
+ 1);
2026 for (i
= get_first_held_lock(curr
, hlock_next
); i
< depth
; i
++) {
2027 hlock
= curr
->held_locks
+ i
;
2028 chain_key
= print_chain_key_iteration(hlock
->class_idx
, chain_key
);
2033 print_chain_key_iteration(hlock_next
->class_idx
, chain_key
);
2034 print_lock(hlock_next
);
2037 static void print_chain_keys_chain(struct lock_chain
*chain
)
2043 printk("depth: %u\n", chain
->depth
);
2044 for (i
= 0; i
< chain
->depth
; i
++) {
2045 class_id
= chain_hlocks
[chain
->base
+ i
];
2046 chain_key
= print_chain_key_iteration(class_id
+ 1, chain_key
);
2048 print_lock_name(lock_classes
+ class_id
);
2053 static void print_collision(struct task_struct
*curr
,
2054 struct held_lock
*hlock_next
,
2055 struct lock_chain
*chain
)
2058 printk("======================\n");
2059 printk("[chain_key collision ]\n");
2060 print_kernel_ident();
2061 printk("----------------------\n");
2062 printk("%s/%d: ", current
->comm
, task_pid_nr(current
));
2063 printk("Hash chain already cached but the contents don't match!\n");
2065 printk("Held locks:");
2066 print_chain_keys_held_locks(curr
, hlock_next
);
2068 printk("Locks in cached chain:");
2069 print_chain_keys_chain(chain
);
2071 printk("\nstack backtrace:\n");
2077 * Checks whether the chain and the current held locks are consistent
2078 * in depth and also in content. If they are not it most likely means
2079 * that there was a collision during the calculation of the chain_key.
2080 * Returns: 0 not passed, 1 passed
2082 static int check_no_collision(struct task_struct
*curr
,
2083 struct held_lock
*hlock
,
2084 struct lock_chain
*chain
)
2086 #ifdef CONFIG_DEBUG_LOCKDEP
2089 i
= get_first_held_lock(curr
, hlock
);
2091 if (DEBUG_LOCKS_WARN_ON(chain
->depth
!= curr
->lockdep_depth
- (i
- 1))) {
2092 print_collision(curr
, hlock
, chain
);
2096 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2097 id
= curr
->held_locks
[i
].class_idx
- 1;
2099 if (DEBUG_LOCKS_WARN_ON(chain_hlocks
[chain
->base
+ j
] != id
)) {
2100 print_collision(curr
, hlock
, chain
);
2109 * Look up a dependency chain. If the key is not present yet then
2110 * add it and return 1 - in this case the new dependency chain is
2111 * validated. If the key is already hashed, return 0.
2112 * (On return with 1 graph_lock is held.)
2114 static inline int lookup_chain_cache(struct task_struct
*curr
,
2115 struct held_lock
*hlock
,
2118 struct lock_class
*class = hlock_class(hlock
);
2119 struct hlist_head
*hash_head
= chainhashentry(chain_key
);
2120 struct lock_chain
*chain
;
2124 * We might need to take the graph lock, ensure we've got IRQs
2125 * disabled to make this an IRQ-safe lock.. for recursion reasons
2126 * lockdep won't complain about its own locking errors.
2128 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2131 * We can walk it lock-free, because entries only get added
2134 hlist_for_each_entry_rcu(chain
, hash_head
, entry
) {
2135 if (chain
->chain_key
== chain_key
) {
2137 debug_atomic_inc(chain_lookup_hits
);
2138 if (!check_no_collision(curr
, hlock
, chain
))
2141 if (very_verbose(class))
2142 printk("\nhash chain already cached, key: "
2143 "%016Lx tail class: [%p] %s\n",
2144 (unsigned long long)chain_key
,
2145 class->key
, class->name
);
2149 if (very_verbose(class))
2150 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2151 (unsigned long long)chain_key
, class->key
, class->name
);
2153 * Allocate a new chain entry from the static array, and add
2159 * We have to walk the chain again locked - to avoid duplicates:
2161 hlist_for_each_entry(chain
, hash_head
, entry
) {
2162 if (chain
->chain_key
== chain_key
) {
2167 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
2168 if (!debug_locks_off_graph_unlock())
2171 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2175 chain
= lock_chains
+ nr_lock_chains
++;
2176 chain
->chain_key
= chain_key
;
2177 chain
->irq_context
= hlock
->irq_context
;
2178 i
= get_first_held_lock(curr
, hlock
);
2179 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
2181 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks
));
2182 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr
->held_locks
));
2183 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks
[0])) <= ARRAY_SIZE(lock_classes
));
2185 if (likely(nr_chain_hlocks
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2186 chain
->base
= nr_chain_hlocks
;
2187 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2188 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
2189 chain_hlocks
[chain
->base
+ j
] = lock_id
;
2191 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
2194 if (nr_chain_hlocks
< MAX_LOCKDEP_CHAIN_HLOCKS
)
2195 nr_chain_hlocks
+= chain
->depth
;
2197 #ifdef CONFIG_DEBUG_LOCKDEP
2199 * Important for check_no_collision().
2201 if (unlikely(nr_chain_hlocks
> MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2202 if (debug_locks_off_graph_unlock())
2205 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2211 hlist_add_head_rcu(&chain
->entry
, hash_head
);
2212 debug_atomic_inc(chain_lookup_misses
);
2218 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
2219 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
2222 * Trylock needs to maintain the stack of held locks, but it
2223 * does not add new dependencies, because trylock can be done
2226 * We look up the chain_key and do the O(N^2) check and update of
2227 * the dependencies only if this is a new dependency chain.
2228 * (If lookup_chain_cache() returns with 1 it acquires
2229 * graph_lock for us)
2231 if (!hlock
->trylock
&& hlock
->check
&&
2232 lookup_chain_cache(curr
, hlock
, chain_key
)) {
2234 * Check whether last held lock:
2236 * - is irq-safe, if this lock is irq-unsafe
2237 * - is softirq-safe, if this lock is hardirq-unsafe
2239 * And check whether the new lock's dependency graph
2240 * could lead back to the previous lock.
2242 * any of these scenarios could lead to a deadlock. If
2245 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
2250 * Mark recursive read, as we jump over it when
2251 * building dependencies (just like we jump over
2257 * Add dependency only if this lock is not the head
2258 * of the chain, and if it's not a secondary read-lock:
2260 if (!chain_head
&& ret
!= 2)
2261 if (!check_prevs_add(curr
, hlock
))
2265 /* after lookup_chain_cache(): */
2266 if (unlikely(!debug_locks
))
2272 static inline int validate_chain(struct task_struct
*curr
,
2273 struct lockdep_map
*lock
, struct held_lock
*hlock
,
2274 int chain_head
, u64 chain_key
)
2281 * We are building curr_chain_key incrementally, so double-check
2282 * it from scratch, to make sure that it's done correctly:
2284 static void check_chain_key(struct task_struct
*curr
)
2286 #ifdef CONFIG_DEBUG_LOCKDEP
2287 struct held_lock
*hlock
, *prev_hlock
= NULL
;
2291 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2292 hlock
= curr
->held_locks
+ i
;
2293 if (chain_key
!= hlock
->prev_chain_key
) {
2296 * We got mighty confused, our chain keys don't match
2297 * with what we expect, someone trample on our task state?
2299 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2300 curr
->lockdep_depth
, i
,
2301 (unsigned long long)chain_key
,
2302 (unsigned long long)hlock
->prev_chain_key
);
2306 * Whoops ran out of static storage again?
2308 if (DEBUG_LOCKS_WARN_ON(hlock
->class_idx
> MAX_LOCKDEP_KEYS
))
2311 if (prev_hlock
&& (prev_hlock
->irq_context
!=
2312 hlock
->irq_context
))
2314 chain_key
= iterate_chain_key(chain_key
, hlock
->class_idx
);
2317 if (chain_key
!= curr
->curr_chain_key
) {
2320 * More smoking hash instead of calculating it, damn see these
2321 * numbers float.. I bet that a pink elephant stepped on my memory.
2323 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2324 curr
->lockdep_depth
, i
,
2325 (unsigned long long)chain_key
,
2326 (unsigned long long)curr
->curr_chain_key
);
2332 print_usage_bug_scenario(struct held_lock
*lock
)
2334 struct lock_class
*class = hlock_class(lock
);
2336 printk(" Possible unsafe locking scenario:\n\n");
2340 __print_lock_name(class);
2342 printk(" <Interrupt>\n");
2344 __print_lock_name(class);
2346 printk("\n *** DEADLOCK ***\n\n");
2350 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
2351 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
2353 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2357 printk("=================================\n");
2358 printk("[ INFO: inconsistent lock state ]\n");
2359 print_kernel_ident();
2360 printk("---------------------------------\n");
2362 printk("inconsistent {%s} -> {%s} usage.\n",
2363 usage_str
[prev_bit
], usage_str
[new_bit
]);
2365 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2366 curr
->comm
, task_pid_nr(curr
),
2367 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
2368 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
2369 trace_hardirqs_enabled(curr
),
2370 trace_softirqs_enabled(curr
));
2373 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
2374 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
2376 print_irqtrace_events(curr
);
2377 printk("\nother info that might help us debug this:\n");
2378 print_usage_bug_scenario(this);
2380 lockdep_print_held_locks(curr
);
2382 printk("\nstack backtrace:\n");
2389 * Print out an error if an invalid bit is set:
2392 valid_state(struct task_struct
*curr
, struct held_lock
*this,
2393 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
2395 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
2396 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
2400 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2401 enum lock_usage_bit new_bit
);
2403 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2406 * print irq inversion bug:
2409 print_irq_inversion_bug(struct task_struct
*curr
,
2410 struct lock_list
*root
, struct lock_list
*other
,
2411 struct held_lock
*this, int forwards
,
2412 const char *irqclass
)
2414 struct lock_list
*entry
= other
;
2415 struct lock_list
*middle
= NULL
;
2418 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2422 printk("=========================================================\n");
2423 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2424 print_kernel_ident();
2425 printk("---------------------------------------------------------\n");
2426 printk("%s/%d just changed the state of lock:\n",
2427 curr
->comm
, task_pid_nr(curr
));
2430 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass
);
2432 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass
);
2433 print_lock_name(other
->class);
2434 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2436 printk("\nother info that might help us debug this:\n");
2438 /* Find a middle lock (if one exists) */
2439 depth
= get_lock_depth(other
);
2441 if (depth
== 0 && (entry
!= root
)) {
2442 printk("lockdep:%s bad path found in chain graph\n", __func__
);
2446 entry
= get_lock_parent(entry
);
2448 } while (entry
&& entry
!= root
&& (depth
>= 0));
2450 print_irq_lock_scenario(root
, other
,
2451 middle
? middle
->class : root
->class, other
->class);
2453 print_irq_lock_scenario(other
, root
,
2454 middle
? middle
->class : other
->class, root
->class);
2456 lockdep_print_held_locks(curr
);
2458 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2459 if (!save_trace(&root
->trace
))
2461 print_shortest_lock_dependencies(other
, root
);
2463 printk("\nstack backtrace:\n");
2470 * Prove that in the forwards-direction subgraph starting at <this>
2471 * there is no lock matching <mask>:
2474 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
2475 enum lock_usage_bit bit
, const char *irqclass
)
2478 struct lock_list root
;
2479 struct lock_list
*uninitialized_var(target_entry
);
2482 root
.class = hlock_class(this);
2483 ret
= find_usage_forwards(&root
, bit
, &target_entry
);
2485 return print_bfs_bug(ret
);
2489 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2494 * Prove that in the backwards-direction subgraph starting at <this>
2495 * there is no lock matching <mask>:
2498 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
2499 enum lock_usage_bit bit
, const char *irqclass
)
2502 struct lock_list root
;
2503 struct lock_list
*uninitialized_var(target_entry
);
2506 root
.class = hlock_class(this);
2507 ret
= find_usage_backwards(&root
, bit
, &target_entry
);
2509 return print_bfs_bug(ret
);
2513 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2517 void print_irqtrace_events(struct task_struct
*curr
)
2519 printk("irq event stamp: %u\n", curr
->irq_events
);
2520 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
2521 print_ip_sym(curr
->hardirq_enable_ip
);
2522 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
2523 print_ip_sym(curr
->hardirq_disable_ip
);
2524 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
2525 print_ip_sym(curr
->softirq_enable_ip
);
2526 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
2527 print_ip_sym(curr
->softirq_disable_ip
);
2530 static int HARDIRQ_verbose(struct lock_class
*class)
2533 return class_filter(class);
2538 static int SOFTIRQ_verbose(struct lock_class
*class)
2541 return class_filter(class);
2546 static int RECLAIM_FS_verbose(struct lock_class
*class)
2549 return class_filter(class);
2554 #define STRICT_READ_CHECKS 1
2556 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2557 #define LOCKDEP_STATE(__STATE) \
2559 #include "lockdep_states.h"
2560 #undef LOCKDEP_STATE
2563 static inline int state_verbose(enum lock_usage_bit bit
,
2564 struct lock_class
*class)
2566 return state_verbose_f
[bit
>> 2](class);
2569 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2570 enum lock_usage_bit bit
, const char *name
);
2573 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2574 enum lock_usage_bit new_bit
)
2576 int excl_bit
= exclusive_bit(new_bit
);
2577 int read
= new_bit
& 1;
2578 int dir
= new_bit
& 2;
2581 * mark USED_IN has to look forwards -- to ensure no dependency
2582 * has ENABLED state, which would allow recursion deadlocks.
2584 * mark ENABLED has to look backwards -- to ensure no dependee
2585 * has USED_IN state, which, again, would allow recursion deadlocks.
2587 check_usage_f usage
= dir
?
2588 check_usage_backwards
: check_usage_forwards
;
2591 * Validate that this particular lock does not have conflicting
2594 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2598 * Validate that the lock dependencies don't have conflicting usage
2601 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2602 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2606 * Check for read in write conflicts
2609 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2612 if (STRICT_READ_CHECKS
&&
2613 !usage(curr
, this, excl_bit
+ 1,
2614 state_name(new_bit
+ 1)))
2618 if (state_verbose(new_bit
, hlock_class(this)))
2625 #define LOCKDEP_STATE(__STATE) __STATE,
2626 #include "lockdep_states.h"
2627 #undef LOCKDEP_STATE
2631 * Mark all held locks with a usage bit:
2634 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2636 enum lock_usage_bit usage_bit
;
2637 struct held_lock
*hlock
;
2640 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2641 hlock
= curr
->held_locks
+ i
;
2643 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2645 usage_bit
+= 1; /* READ */
2647 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2652 if (!mark_lock(curr
, hlock
, usage_bit
))
2660 * Hardirqs will be enabled:
2662 static void __trace_hardirqs_on_caller(unsigned long ip
)
2664 struct task_struct
*curr
= current
;
2666 /* we'll do an OFF -> ON transition: */
2667 curr
->hardirqs_enabled
= 1;
2670 * We are going to turn hardirqs on, so set the
2671 * usage bit for all held locks:
2673 if (!mark_held_locks(curr
, HARDIRQ
))
2676 * If we have softirqs enabled, then set the usage
2677 * bit for all held locks. (disabled hardirqs prevented
2678 * this bit from being set before)
2680 if (curr
->softirqs_enabled
)
2681 if (!mark_held_locks(curr
, SOFTIRQ
))
2684 curr
->hardirq_enable_ip
= ip
;
2685 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2686 debug_atomic_inc(hardirqs_on_events
);
2689 __visible
void trace_hardirqs_on_caller(unsigned long ip
)
2691 time_hardirqs_on(CALLER_ADDR0
, ip
);
2693 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2696 if (unlikely(current
->hardirqs_enabled
)) {
2698 * Neither irq nor preemption are disabled here
2699 * so this is racy by nature but losing one hit
2700 * in a stat is not a big deal.
2702 __debug_atomic_inc(redundant_hardirqs_on
);
2707 * We're enabling irqs and according to our state above irqs weren't
2708 * already enabled, yet we find the hardware thinks they are in fact
2709 * enabled.. someone messed up their IRQ state tracing.
2711 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2715 * See the fine text that goes along with this variable definition.
2717 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled
)))
2721 * Can't allow enabling interrupts while in an interrupt handler,
2722 * that's general bad form and such. Recursion, limited stack etc..
2724 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2727 current
->lockdep_recursion
= 1;
2728 __trace_hardirqs_on_caller(ip
);
2729 current
->lockdep_recursion
= 0;
2731 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2733 void trace_hardirqs_on(void)
2735 trace_hardirqs_on_caller(CALLER_ADDR0
);
2737 EXPORT_SYMBOL(trace_hardirqs_on
);
2740 * Hardirqs were disabled:
2742 __visible
void trace_hardirqs_off_caller(unsigned long ip
)
2744 struct task_struct
*curr
= current
;
2746 time_hardirqs_off(CALLER_ADDR0
, ip
);
2748 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2752 * So we're supposed to get called after you mask local IRQs, but for
2753 * some reason the hardware doesn't quite think you did a proper job.
2755 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2758 if (curr
->hardirqs_enabled
) {
2760 * We have done an ON -> OFF transition:
2762 curr
->hardirqs_enabled
= 0;
2763 curr
->hardirq_disable_ip
= ip
;
2764 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2765 debug_atomic_inc(hardirqs_off_events
);
2767 debug_atomic_inc(redundant_hardirqs_off
);
2769 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2771 void trace_hardirqs_off(void)
2773 trace_hardirqs_off_caller(CALLER_ADDR0
);
2775 EXPORT_SYMBOL(trace_hardirqs_off
);
2778 * Softirqs will be enabled:
2780 void trace_softirqs_on(unsigned long ip
)
2782 struct task_struct
*curr
= current
;
2784 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2788 * We fancy IRQs being disabled here, see softirq.c, avoids
2789 * funny state and nesting things.
2791 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2794 if (curr
->softirqs_enabled
) {
2795 debug_atomic_inc(redundant_softirqs_on
);
2799 current
->lockdep_recursion
= 1;
2801 * We'll do an OFF -> ON transition:
2803 curr
->softirqs_enabled
= 1;
2804 curr
->softirq_enable_ip
= ip
;
2805 curr
->softirq_enable_event
= ++curr
->irq_events
;
2806 debug_atomic_inc(softirqs_on_events
);
2808 * We are going to turn softirqs on, so set the
2809 * usage bit for all held locks, if hardirqs are
2812 if (curr
->hardirqs_enabled
)
2813 mark_held_locks(curr
, SOFTIRQ
);
2814 current
->lockdep_recursion
= 0;
2818 * Softirqs were disabled:
2820 void trace_softirqs_off(unsigned long ip
)
2822 struct task_struct
*curr
= current
;
2824 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2828 * We fancy IRQs being disabled here, see softirq.c
2830 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2833 if (curr
->softirqs_enabled
) {
2835 * We have done an ON -> OFF transition:
2837 curr
->softirqs_enabled
= 0;
2838 curr
->softirq_disable_ip
= ip
;
2839 curr
->softirq_disable_event
= ++curr
->irq_events
;
2840 debug_atomic_inc(softirqs_off_events
);
2842 * Whoops, we wanted softirqs off, so why aren't they?
2844 DEBUG_LOCKS_WARN_ON(!softirq_count());
2846 debug_atomic_inc(redundant_softirqs_off
);
2849 static void __lockdep_trace_alloc(gfp_t gfp_mask
, unsigned long flags
)
2851 struct task_struct
*curr
= current
;
2853 if (unlikely(!debug_locks
))
2856 /* no reclaim without waiting on it */
2857 if (!(gfp_mask
& __GFP_DIRECT_RECLAIM
))
2860 /* this guy won't enter reclaim */
2861 if ((curr
->flags
& PF_MEMALLOC
) && !(gfp_mask
& __GFP_NOMEMALLOC
))
2864 /* We're only interested __GFP_FS allocations for now */
2865 if (!(gfp_mask
& __GFP_FS
))
2869 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2871 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags
)))
2874 mark_held_locks(curr
, RECLAIM_FS
);
2877 static void check_flags(unsigned long flags
);
2879 void lockdep_trace_alloc(gfp_t gfp_mask
)
2881 unsigned long flags
;
2883 if (unlikely(current
->lockdep_recursion
))
2886 raw_local_irq_save(flags
);
2888 current
->lockdep_recursion
= 1;
2889 __lockdep_trace_alloc(gfp_mask
, flags
);
2890 current
->lockdep_recursion
= 0;
2891 raw_local_irq_restore(flags
);
2894 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2897 * If non-trylock use in a hardirq or softirq context, then
2898 * mark the lock as used in these contexts:
2900 if (!hlock
->trylock
) {
2902 if (curr
->hardirq_context
)
2903 if (!mark_lock(curr
, hlock
,
2904 LOCK_USED_IN_HARDIRQ_READ
))
2906 if (curr
->softirq_context
)
2907 if (!mark_lock(curr
, hlock
,
2908 LOCK_USED_IN_SOFTIRQ_READ
))
2911 if (curr
->hardirq_context
)
2912 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2914 if (curr
->softirq_context
)
2915 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2919 if (!hlock
->hardirqs_off
) {
2921 if (!mark_lock(curr
, hlock
,
2922 LOCK_ENABLED_HARDIRQ_READ
))
2924 if (curr
->softirqs_enabled
)
2925 if (!mark_lock(curr
, hlock
,
2926 LOCK_ENABLED_SOFTIRQ_READ
))
2929 if (!mark_lock(curr
, hlock
,
2930 LOCK_ENABLED_HARDIRQ
))
2932 if (curr
->softirqs_enabled
)
2933 if (!mark_lock(curr
, hlock
,
2934 LOCK_ENABLED_SOFTIRQ
))
2940 * We reuse the irq context infrastructure more broadly as a general
2941 * context checking code. This tests GFP_FS recursion (a lock taken
2942 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2945 if (!hlock
->trylock
&& (curr
->lockdep_reclaim_gfp
& __GFP_FS
)) {
2947 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS_READ
))
2950 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS
))
2958 static inline unsigned int task_irq_context(struct task_struct
*task
)
2960 return 2 * !!task
->hardirq_context
+ !!task
->softirq_context
;
2963 static int separate_irq_context(struct task_struct
*curr
,
2964 struct held_lock
*hlock
)
2966 unsigned int depth
= curr
->lockdep_depth
;
2969 * Keep track of points where we cross into an interrupt context:
2972 struct held_lock
*prev_hlock
;
2974 prev_hlock
= curr
->held_locks
+ depth
-1;
2976 * If we cross into another context, reset the
2977 * hash key (this also prevents the checking and the
2978 * adding of the dependency to 'prev'):
2980 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2986 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2989 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2990 enum lock_usage_bit new_bit
)
2992 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2996 static inline int mark_irqflags(struct task_struct
*curr
,
2997 struct held_lock
*hlock
)
3002 static inline unsigned int task_irq_context(struct task_struct
*task
)
3007 static inline int separate_irq_context(struct task_struct
*curr
,
3008 struct held_lock
*hlock
)
3013 void lockdep_trace_alloc(gfp_t gfp_mask
)
3017 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3020 * Mark a lock with a usage bit, and validate the state transition:
3022 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
3023 enum lock_usage_bit new_bit
)
3025 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
3028 * If already set then do not dirty the cacheline,
3029 * nor do any checks:
3031 if (likely(hlock_class(this)->usage_mask
& new_mask
))
3037 * Make sure we didn't race:
3039 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
3044 hlock_class(this)->usage_mask
|= new_mask
;
3046 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
3050 #define LOCKDEP_STATE(__STATE) \
3051 case LOCK_USED_IN_##__STATE: \
3052 case LOCK_USED_IN_##__STATE##_READ: \
3053 case LOCK_ENABLED_##__STATE: \
3054 case LOCK_ENABLED_##__STATE##_READ:
3055 #include "lockdep_states.h"
3056 #undef LOCKDEP_STATE
3057 ret
= mark_lock_irq(curr
, this, new_bit
);
3062 debug_atomic_dec(nr_unused_locks
);
3065 if (!debug_locks_off_graph_unlock())
3074 * We must printk outside of the graph_lock:
3077 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
3079 print_irqtrace_events(curr
);
3087 * Initialize a lock instance's lock-class mapping info:
3089 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
3090 struct lock_class_key
*key
, int subclass
)
3094 kmemcheck_mark_initialized(lock
, sizeof(*lock
));
3096 for (i
= 0; i
< NR_LOCKDEP_CACHING_CLASSES
; i
++)
3097 lock
->class_cache
[i
] = NULL
;
3099 #ifdef CONFIG_LOCK_STAT
3100 lock
->cpu
= raw_smp_processor_id();
3104 * Can't be having no nameless bastards around this place!
3106 if (DEBUG_LOCKS_WARN_ON(!name
)) {
3107 lock
->name
= "NULL";
3114 * No key, no joy, we need to hash something.
3116 if (DEBUG_LOCKS_WARN_ON(!key
))
3119 * Sanity check, the lock-class key must be persistent:
3121 if (!static_obj(key
)) {
3122 printk("BUG: key %p not in .data!\n", key
);
3124 * What it says above ^^^^^, I suggest you read it.
3126 DEBUG_LOCKS_WARN_ON(1);
3131 if (unlikely(!debug_locks
))
3135 unsigned long flags
;
3137 if (DEBUG_LOCKS_WARN_ON(current
->lockdep_recursion
))
3140 raw_local_irq_save(flags
);
3141 current
->lockdep_recursion
= 1;
3142 register_lock_class(lock
, subclass
, 1);
3143 current
->lockdep_recursion
= 0;
3144 raw_local_irq_restore(flags
);
3147 EXPORT_SYMBOL_GPL(lockdep_init_map
);
3149 struct lock_class_key __lockdep_no_validate__
;
3150 EXPORT_SYMBOL_GPL(__lockdep_no_validate__
);
3153 print_lock_nested_lock_not_held(struct task_struct
*curr
,
3154 struct held_lock
*hlock
,
3157 if (!debug_locks_off())
3159 if (debug_locks_silent
)
3163 printk("==================================\n");
3164 printk("[ BUG: Nested lock was not taken ]\n");
3165 print_kernel_ident();
3166 printk("----------------------------------\n");
3168 printk("%s/%d is trying to lock:\n", curr
->comm
, task_pid_nr(curr
));
3171 printk("\nbut this task is not holding:\n");
3172 printk("%s\n", hlock
->nest_lock
->name
);
3174 printk("\nstack backtrace:\n");
3177 printk("\nother info that might help us debug this:\n");
3178 lockdep_print_held_locks(curr
);
3180 printk("\nstack backtrace:\n");
3186 static int __lock_is_held(struct lockdep_map
*lock
);
3189 * This gets called for every mutex_lock*()/spin_lock*() operation.
3190 * We maintain the dependency maps and validate the locking attempt:
3192 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3193 int trylock
, int read
, int check
, int hardirqs_off
,
3194 struct lockdep_map
*nest_lock
, unsigned long ip
,
3195 int references
, int pin_count
)
3197 struct task_struct
*curr
= current
;
3198 struct lock_class
*class = NULL
;
3199 struct held_lock
*hlock
;
3205 if (unlikely(!debug_locks
))
3209 * Lockdep should run with IRQs disabled, otherwise we could
3210 * get an interrupt which would want to take locks, which would
3211 * end up in lockdep and have you got a head-ache already?
3213 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3216 if (!prove_locking
|| lock
->key
== &__lockdep_no_validate__
)
3219 if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
3220 class = lock
->class_cache
[subclass
];
3224 if (unlikely(!class)) {
3225 class = register_lock_class(lock
, subclass
, 0);
3229 atomic_inc((atomic_t
*)&class->ops
);
3230 if (very_verbose(class)) {
3231 printk("\nacquire class [%p] %s", class->key
, class->name
);
3232 if (class->name_version
> 1)
3233 printk("#%d", class->name_version
);
3239 * Add the lock to the list of currently held locks.
3240 * (we dont increase the depth just yet, up until the
3241 * dependency checks are done)
3243 depth
= curr
->lockdep_depth
;
3245 * Ran out of static storage for our per-task lock stack again have we?
3247 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
3250 class_idx
= class - lock_classes
+ 1;
3253 hlock
= curr
->held_locks
+ depth
- 1;
3254 if (hlock
->class_idx
== class_idx
&& nest_lock
) {
3255 if (hlock
->references
)
3256 hlock
->references
++;
3258 hlock
->references
= 2;
3264 hlock
= curr
->held_locks
+ depth
;
3266 * Plain impossible, we just registered it and checked it weren't no
3267 * NULL like.. I bet this mushroom I ate was good!
3269 if (DEBUG_LOCKS_WARN_ON(!class))
3271 hlock
->class_idx
= class_idx
;
3272 hlock
->acquire_ip
= ip
;
3273 hlock
->instance
= lock
;
3274 hlock
->nest_lock
= nest_lock
;
3275 hlock
->irq_context
= task_irq_context(curr
);
3276 hlock
->trylock
= trylock
;
3278 hlock
->check
= check
;
3279 hlock
->hardirqs_off
= !!hardirqs_off
;
3280 hlock
->references
= references
;
3281 #ifdef CONFIG_LOCK_STAT
3282 hlock
->waittime_stamp
= 0;
3283 hlock
->holdtime_stamp
= lockstat_clock();
3285 hlock
->pin_count
= pin_count
;
3287 if (check
&& !mark_irqflags(curr
, hlock
))
3290 /* mark it as used: */
3291 if (!mark_lock(curr
, hlock
, LOCK_USED
))
3295 * Calculate the chain hash: it's the combined hash of all the
3296 * lock keys along the dependency chain. We save the hash value
3297 * at every step so that we can get the current hash easily
3298 * after unlock. The chain hash is then used to cache dependency
3301 * The 'key ID' is what is the most compact key value to drive
3302 * the hash, not class->key.
3305 * Whoops, we did it again.. ran straight out of our static allocation.
3307 if (DEBUG_LOCKS_WARN_ON(class_idx
> MAX_LOCKDEP_KEYS
))
3310 chain_key
= curr
->curr_chain_key
;
3313 * How can we have a chain hash when we ain't got no keys?!
3315 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
3320 hlock
->prev_chain_key
= chain_key
;
3321 if (separate_irq_context(curr
, hlock
)) {
3325 chain_key
= iterate_chain_key(chain_key
, class_idx
);
3327 if (nest_lock
&& !__lock_is_held(nest_lock
))
3328 return print_lock_nested_lock_not_held(curr
, hlock
, ip
);
3330 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
3333 curr
->curr_chain_key
= chain_key
;
3334 curr
->lockdep_depth
++;
3335 check_chain_key(curr
);
3336 #ifdef CONFIG_DEBUG_LOCKDEP
3337 if (unlikely(!debug_locks
))
3340 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
3342 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3343 printk(KERN_DEBUG
"depth: %i max: %lu!\n",
3344 curr
->lockdep_depth
, MAX_LOCK_DEPTH
);
3346 lockdep_print_held_locks(current
);
3347 debug_show_all_locks();
3353 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
3354 max_lockdep_depth
= curr
->lockdep_depth
;
3360 print_unlock_imbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3363 if (!debug_locks_off())
3365 if (debug_locks_silent
)
3369 printk("=====================================\n");
3370 printk("[ BUG: bad unlock balance detected! ]\n");
3371 print_kernel_ident();
3372 printk("-------------------------------------\n");
3373 printk("%s/%d is trying to release lock (",
3374 curr
->comm
, task_pid_nr(curr
));
3375 print_lockdep_cache(lock
);
3378 printk("but there are no more locks to release!\n");
3379 printk("\nother info that might help us debug this:\n");
3380 lockdep_print_held_locks(curr
);
3382 printk("\nstack backtrace:\n");
3388 static int match_held_lock(struct held_lock
*hlock
, struct lockdep_map
*lock
)
3390 if (hlock
->instance
== lock
)
3393 if (hlock
->references
) {
3394 struct lock_class
*class = lock
->class_cache
[0];
3397 class = look_up_lock_class(lock
, 0);
3400 * If look_up_lock_class() failed to find a class, we're trying
3401 * to test if we hold a lock that has never yet been acquired.
3402 * Clearly if the lock hasn't been acquired _ever_, we're not
3403 * holding it either, so report failure.
3409 * References, but not a lock we're actually ref-counting?
3410 * State got messed up, follow the sites that change ->references
3411 * and try to make sense of it.
3413 if (DEBUG_LOCKS_WARN_ON(!hlock
->nest_lock
))
3416 if (hlock
->class_idx
== class - lock_classes
+ 1)
3424 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
3425 struct lock_class_key
*key
, unsigned int subclass
,
3428 struct task_struct
*curr
= current
;
3429 struct held_lock
*hlock
, *prev_hlock
;
3430 struct lock_class
*class;
3434 depth
= curr
->lockdep_depth
;
3436 * This function is about (re)setting the class of a held lock,
3437 * yet we're not actually holding any locks. Naughty user!
3439 if (DEBUG_LOCKS_WARN_ON(!depth
))
3443 for (i
= depth
-1; i
>= 0; i
--) {
3444 hlock
= curr
->held_locks
+ i
;
3446 * We must not cross into another context:
3448 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3450 if (match_held_lock(hlock
, lock
))
3454 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3457 lockdep_init_map(lock
, name
, key
, 0);
3458 class = register_lock_class(lock
, subclass
, 0);
3459 hlock
->class_idx
= class - lock_classes
+ 1;
3461 curr
->lockdep_depth
= i
;
3462 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3464 for (; i
< depth
; i
++) {
3465 hlock
= curr
->held_locks
+ i
;
3466 if (!__lock_acquire(hlock
->instance
,
3467 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3468 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3469 hlock
->nest_lock
, hlock
->acquire_ip
,
3470 hlock
->references
, hlock
->pin_count
))
3475 * I took it apart and put it back together again, except now I have
3476 * these 'spare' parts.. where shall I put them.
3478 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
3484 * Remove the lock to the list of currently held locks - this gets
3485 * called on mutex_unlock()/spin_unlock*() (or on a failed
3486 * mutex_lock_interruptible()).
3488 * @nested is an hysterical artifact, needs a tree wide cleanup.
3491 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
3493 struct task_struct
*curr
= current
;
3494 struct held_lock
*hlock
, *prev_hlock
;
3498 if (unlikely(!debug_locks
))
3501 depth
= curr
->lockdep_depth
;
3503 * So we're all set to release this lock.. wait what lock? We don't
3504 * own any locks, you've been drinking again?
3506 if (DEBUG_LOCKS_WARN_ON(depth
<= 0))
3507 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3510 * Check whether the lock exists in the current stack
3514 for (i
= depth
-1; i
>= 0; i
--) {
3515 hlock
= curr
->held_locks
+ i
;
3517 * We must not cross into another context:
3519 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3521 if (match_held_lock(hlock
, lock
))
3525 return print_unlock_imbalance_bug(curr
, lock
, ip
);
3528 if (hlock
->instance
== lock
)
3529 lock_release_holdtime(hlock
);
3531 WARN(hlock
->pin_count
, "releasing a pinned lock\n");
3533 if (hlock
->references
) {
3534 hlock
->references
--;
3535 if (hlock
->references
) {
3537 * We had, and after removing one, still have
3538 * references, the current lock stack is still
3539 * valid. We're done!
3546 * We have the right lock to unlock, 'hlock' points to it.
3547 * Now we remove it from the stack, and add back the other
3548 * entries (if any), recalculating the hash along the way:
3551 curr
->lockdep_depth
= i
;
3552 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3554 for (i
++; i
< depth
; i
++) {
3555 hlock
= curr
->held_locks
+ i
;
3556 if (!__lock_acquire(hlock
->instance
,
3557 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3558 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3559 hlock
->nest_lock
, hlock
->acquire_ip
,
3560 hlock
->references
, hlock
->pin_count
))
3565 * We had N bottles of beer on the wall, we drank one, but now
3566 * there's not N-1 bottles of beer left on the wall...
3568 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
3574 static int __lock_is_held(struct lockdep_map
*lock
)
3576 struct task_struct
*curr
= current
;
3579 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3580 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3582 if (match_held_lock(hlock
, lock
))
3589 static struct pin_cookie
__lock_pin_lock(struct lockdep_map
*lock
)
3591 struct pin_cookie cookie
= NIL_COOKIE
;
3592 struct task_struct
*curr
= current
;
3595 if (unlikely(!debug_locks
))
3598 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3599 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3601 if (match_held_lock(hlock
, lock
)) {
3603 * Grab 16bits of randomness; this is sufficient to not
3604 * be guessable and still allows some pin nesting in
3605 * our u32 pin_count.
3607 cookie
.val
= 1 + (prandom_u32() >> 16);
3608 hlock
->pin_count
+= cookie
.val
;
3613 WARN(1, "pinning an unheld lock\n");
3617 static void __lock_repin_lock(struct lockdep_map
*lock
, struct pin_cookie cookie
)
3619 struct task_struct
*curr
= current
;
3622 if (unlikely(!debug_locks
))
3625 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3626 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3628 if (match_held_lock(hlock
, lock
)) {
3629 hlock
->pin_count
+= cookie
.val
;
3634 WARN(1, "pinning an unheld lock\n");
3637 static void __lock_unpin_lock(struct lockdep_map
*lock
, struct pin_cookie cookie
)
3639 struct task_struct
*curr
= current
;
3642 if (unlikely(!debug_locks
))
3645 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3646 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3648 if (match_held_lock(hlock
, lock
)) {
3649 if (WARN(!hlock
->pin_count
, "unpinning an unpinned lock\n"))
3652 hlock
->pin_count
-= cookie
.val
;
3654 if (WARN((int)hlock
->pin_count
< 0, "pin count corrupted\n"))
3655 hlock
->pin_count
= 0;
3661 WARN(1, "unpinning an unheld lock\n");
3665 * Check whether we follow the irq-flags state precisely:
3667 static void check_flags(unsigned long flags
)
3669 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3670 defined(CONFIG_TRACE_IRQFLAGS)
3674 if (irqs_disabled_flags(flags
)) {
3675 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
3676 printk("possible reason: unannotated irqs-off.\n");
3679 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
3680 printk("possible reason: unannotated irqs-on.\n");
3685 * We dont accurately track softirq state in e.g.
3686 * hardirq contexts (such as on 4KSTACKS), so only
3687 * check if not in hardirq contexts:
3689 if (!hardirq_count()) {
3690 if (softirq_count()) {
3691 /* like the above, but with softirqs */
3692 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
3694 /* lick the above, does it taste good? */
3695 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
3700 print_irqtrace_events(current
);
3704 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
3705 struct lock_class_key
*key
, unsigned int subclass
,
3708 unsigned long flags
;
3710 if (unlikely(current
->lockdep_recursion
))
3713 raw_local_irq_save(flags
);
3714 current
->lockdep_recursion
= 1;
3716 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
3717 check_chain_key(current
);
3718 current
->lockdep_recursion
= 0;
3719 raw_local_irq_restore(flags
);
3721 EXPORT_SYMBOL_GPL(lock_set_class
);
3724 * We are not always called with irqs disabled - do that here,
3725 * and also avoid lockdep recursion:
3727 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3728 int trylock
, int read
, int check
,
3729 struct lockdep_map
*nest_lock
, unsigned long ip
)
3731 unsigned long flags
;
3733 if (unlikely(current
->lockdep_recursion
))
3736 raw_local_irq_save(flags
);
3739 current
->lockdep_recursion
= 1;
3740 trace_lock_acquire(lock
, subclass
, trylock
, read
, check
, nest_lock
, ip
);
3741 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
3742 irqs_disabled_flags(flags
), nest_lock
, ip
, 0, 0);
3743 current
->lockdep_recursion
= 0;
3744 raw_local_irq_restore(flags
);
3746 EXPORT_SYMBOL_GPL(lock_acquire
);
3748 void lock_release(struct lockdep_map
*lock
, int nested
,
3751 unsigned long flags
;
3753 if (unlikely(current
->lockdep_recursion
))
3756 raw_local_irq_save(flags
);
3758 current
->lockdep_recursion
= 1;
3759 trace_lock_release(lock
, ip
);
3760 if (__lock_release(lock
, nested
, ip
))
3761 check_chain_key(current
);
3762 current
->lockdep_recursion
= 0;
3763 raw_local_irq_restore(flags
);
3765 EXPORT_SYMBOL_GPL(lock_release
);
3767 int lock_is_held(struct lockdep_map
*lock
)
3769 unsigned long flags
;
3772 if (unlikely(current
->lockdep_recursion
))
3773 return 1; /* avoid false negative lockdep_assert_held() */
3775 raw_local_irq_save(flags
);
3778 current
->lockdep_recursion
= 1;
3779 ret
= __lock_is_held(lock
);
3780 current
->lockdep_recursion
= 0;
3781 raw_local_irq_restore(flags
);
3785 EXPORT_SYMBOL_GPL(lock_is_held
);
3787 struct pin_cookie
lock_pin_lock(struct lockdep_map
*lock
)
3789 struct pin_cookie cookie
= NIL_COOKIE
;
3790 unsigned long flags
;
3792 if (unlikely(current
->lockdep_recursion
))
3795 raw_local_irq_save(flags
);
3798 current
->lockdep_recursion
= 1;
3799 cookie
= __lock_pin_lock(lock
);
3800 current
->lockdep_recursion
= 0;
3801 raw_local_irq_restore(flags
);
3805 EXPORT_SYMBOL_GPL(lock_pin_lock
);
3807 void lock_repin_lock(struct lockdep_map
*lock
, struct pin_cookie cookie
)
3809 unsigned long flags
;
3811 if (unlikely(current
->lockdep_recursion
))
3814 raw_local_irq_save(flags
);
3817 current
->lockdep_recursion
= 1;
3818 __lock_repin_lock(lock
, cookie
);
3819 current
->lockdep_recursion
= 0;
3820 raw_local_irq_restore(flags
);
3822 EXPORT_SYMBOL_GPL(lock_repin_lock
);
3824 void lock_unpin_lock(struct lockdep_map
*lock
, struct pin_cookie cookie
)
3826 unsigned long flags
;
3828 if (unlikely(current
->lockdep_recursion
))
3831 raw_local_irq_save(flags
);
3834 current
->lockdep_recursion
= 1;
3835 __lock_unpin_lock(lock
, cookie
);
3836 current
->lockdep_recursion
= 0;
3837 raw_local_irq_restore(flags
);
3839 EXPORT_SYMBOL_GPL(lock_unpin_lock
);
3841 void lockdep_set_current_reclaim_state(gfp_t gfp_mask
)
3843 current
->lockdep_reclaim_gfp
= gfp_mask
;
3846 void lockdep_clear_current_reclaim_state(void)
3848 current
->lockdep_reclaim_gfp
= 0;
3851 #ifdef CONFIG_LOCK_STAT
3853 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3856 if (!debug_locks_off())
3858 if (debug_locks_silent
)
3862 printk("=================================\n");
3863 printk("[ BUG: bad contention detected! ]\n");
3864 print_kernel_ident();
3865 printk("---------------------------------\n");
3866 printk("%s/%d is trying to contend lock (",
3867 curr
->comm
, task_pid_nr(curr
));
3868 print_lockdep_cache(lock
);
3871 printk("but there are no locks held!\n");
3872 printk("\nother info that might help us debug this:\n");
3873 lockdep_print_held_locks(curr
);
3875 printk("\nstack backtrace:\n");
3882 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3884 struct task_struct
*curr
= current
;
3885 struct held_lock
*hlock
, *prev_hlock
;
3886 struct lock_class_stats
*stats
;
3888 int i
, contention_point
, contending_point
;
3890 depth
= curr
->lockdep_depth
;
3892 * Whee, we contended on this lock, except it seems we're not
3893 * actually trying to acquire anything much at all..
3895 if (DEBUG_LOCKS_WARN_ON(!depth
))
3899 for (i
= depth
-1; i
>= 0; i
--) {
3900 hlock
= curr
->held_locks
+ i
;
3902 * We must not cross into another context:
3904 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3906 if (match_held_lock(hlock
, lock
))
3910 print_lock_contention_bug(curr
, lock
, ip
);
3914 if (hlock
->instance
!= lock
)
3917 hlock
->waittime_stamp
= lockstat_clock();
3919 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3920 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3923 stats
= get_lock_stats(hlock_class(hlock
));
3924 if (contention_point
< LOCKSTAT_POINTS
)
3925 stats
->contention_point
[contention_point
]++;
3926 if (contending_point
< LOCKSTAT_POINTS
)
3927 stats
->contending_point
[contending_point
]++;
3928 if (lock
->cpu
!= smp_processor_id())
3929 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3930 put_lock_stats(stats
);
3934 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3936 struct task_struct
*curr
= current
;
3937 struct held_lock
*hlock
, *prev_hlock
;
3938 struct lock_class_stats
*stats
;
3940 u64 now
, waittime
= 0;
3943 depth
= curr
->lockdep_depth
;
3945 * Yay, we acquired ownership of this lock we didn't try to
3946 * acquire, how the heck did that happen?
3948 if (DEBUG_LOCKS_WARN_ON(!depth
))
3952 for (i
= depth
-1; i
>= 0; i
--) {
3953 hlock
= curr
->held_locks
+ i
;
3955 * We must not cross into another context:
3957 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3959 if (match_held_lock(hlock
, lock
))
3963 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3967 if (hlock
->instance
!= lock
)
3970 cpu
= smp_processor_id();
3971 if (hlock
->waittime_stamp
) {
3972 now
= lockstat_clock();
3973 waittime
= now
- hlock
->waittime_stamp
;
3974 hlock
->holdtime_stamp
= now
;
3977 trace_lock_acquired(lock
, ip
);
3979 stats
= get_lock_stats(hlock_class(hlock
));
3982 lock_time_inc(&stats
->read_waittime
, waittime
);
3984 lock_time_inc(&stats
->write_waittime
, waittime
);
3986 if (lock
->cpu
!= cpu
)
3987 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3988 put_lock_stats(stats
);
3994 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3996 unsigned long flags
;
3998 if (unlikely(!lock_stat
))
4001 if (unlikely(current
->lockdep_recursion
))
4004 raw_local_irq_save(flags
);
4006 current
->lockdep_recursion
= 1;
4007 trace_lock_contended(lock
, ip
);
4008 __lock_contended(lock
, ip
);
4009 current
->lockdep_recursion
= 0;
4010 raw_local_irq_restore(flags
);
4012 EXPORT_SYMBOL_GPL(lock_contended
);
4014 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
4016 unsigned long flags
;
4018 if (unlikely(!lock_stat
))
4021 if (unlikely(current
->lockdep_recursion
))
4024 raw_local_irq_save(flags
);
4026 current
->lockdep_recursion
= 1;
4027 __lock_acquired(lock
, ip
);
4028 current
->lockdep_recursion
= 0;
4029 raw_local_irq_restore(flags
);
4031 EXPORT_SYMBOL_GPL(lock_acquired
);
4035 * Used by the testsuite, sanitize the validator state
4036 * after a simulated failure:
4039 void lockdep_reset(void)
4041 unsigned long flags
;
4044 raw_local_irq_save(flags
);
4045 current
->curr_chain_key
= 0;
4046 current
->lockdep_depth
= 0;
4047 current
->lockdep_recursion
= 0;
4048 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
4049 nr_hardirq_chains
= 0;
4050 nr_softirq_chains
= 0;
4051 nr_process_chains
= 0;
4053 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
4054 INIT_HLIST_HEAD(chainhash_table
+ i
);
4055 raw_local_irq_restore(flags
);
4058 static void zap_class(struct lock_class
*class)
4063 * Remove all dependencies this lock is
4066 for (i
= 0; i
< nr_list_entries
; i
++) {
4067 if (list_entries
[i
].class == class)
4068 list_del_rcu(&list_entries
[i
].entry
);
4071 * Unhash the class and remove it from the all_lock_classes list:
4073 hlist_del_rcu(&class->hash_entry
);
4074 list_del_rcu(&class->lock_entry
);
4076 RCU_INIT_POINTER(class->key
, NULL
);
4077 RCU_INIT_POINTER(class->name
, NULL
);
4080 static inline int within(const void *addr
, void *start
, unsigned long size
)
4082 return addr
>= start
&& addr
< start
+ size
;
4086 * Used in module.c to remove lock classes from memory that is going to be
4087 * freed; and possibly re-used by other modules.
4089 * We will have had one sync_sched() before getting here, so we're guaranteed
4090 * nobody will look up these exact classes -- they're properly dead but still
4093 void lockdep_free_key_range(void *start
, unsigned long size
)
4095 struct lock_class
*class;
4096 struct hlist_head
*head
;
4097 unsigned long flags
;
4101 raw_local_irq_save(flags
);
4102 locked
= graph_lock();
4105 * Unhash all classes that were created by this module:
4107 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
4108 head
= classhash_table
+ i
;
4109 hlist_for_each_entry_rcu(class, head
, hash_entry
) {
4110 if (within(class->key
, start
, size
))
4112 else if (within(class->name
, start
, size
))
4119 raw_local_irq_restore(flags
);
4122 * Wait for any possible iterators from look_up_lock_class() to pass
4123 * before continuing to free the memory they refer to.
4125 * sync_sched() is sufficient because the read-side is IRQ disable.
4127 synchronize_sched();
4130 * XXX at this point we could return the resources to the pool;
4131 * instead we leak them. We would need to change to bitmap allocators
4132 * instead of the linear allocators we have now.
4136 void lockdep_reset_lock(struct lockdep_map
*lock
)
4138 struct lock_class
*class;
4139 struct hlist_head
*head
;
4140 unsigned long flags
;
4144 raw_local_irq_save(flags
);
4147 * Remove all classes this lock might have:
4149 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
4151 * If the class exists we look it up and zap it:
4153 class = look_up_lock_class(lock
, j
);
4158 * Debug check: in the end all mapped classes should
4161 locked
= graph_lock();
4162 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
4163 head
= classhash_table
+ i
;
4164 hlist_for_each_entry_rcu(class, head
, hash_entry
) {
4167 for (j
= 0; j
< NR_LOCKDEP_CACHING_CLASSES
; j
++)
4168 match
|= class == lock
->class_cache
[j
];
4170 if (unlikely(match
)) {
4171 if (debug_locks_off_graph_unlock()) {
4173 * We all just reset everything, how did it match?
4185 raw_local_irq_restore(flags
);
4188 void __init
lockdep_info(void)
4190 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4192 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
4193 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
4194 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
4195 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
4196 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
4197 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
4198 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
4200 printk(" memory used by lock dependency info: %lu kB\n",
4201 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
4202 sizeof(struct list_head
) * CLASSHASH_SIZE
+
4203 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
4204 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
4205 sizeof(struct list_head
) * CHAINHASH_SIZE
4206 #ifdef CONFIG_PROVE_LOCKING
4207 + sizeof(struct circular_queue
)
4212 printk(" per task-struct memory footprint: %lu bytes\n",
4213 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
4217 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
4218 const void *mem_to
, struct held_lock
*hlock
)
4220 if (!debug_locks_off())
4222 if (debug_locks_silent
)
4226 printk("=========================\n");
4227 printk("[ BUG: held lock freed! ]\n");
4228 print_kernel_ident();
4229 printk("-------------------------\n");
4230 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4231 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
4233 lockdep_print_held_locks(curr
);
4235 printk("\nstack backtrace:\n");
4239 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
4240 const void* lock_from
, unsigned long lock_len
)
4242 return lock_from
+ lock_len
<= mem_from
||
4243 mem_from
+ mem_len
<= lock_from
;
4247 * Called when kernel memory is freed (or unmapped), or if a lock
4248 * is destroyed or reinitialized - this code checks whether there is
4249 * any held lock in the memory range of <from> to <to>:
4251 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
4253 struct task_struct
*curr
= current
;
4254 struct held_lock
*hlock
;
4255 unsigned long flags
;
4258 if (unlikely(!debug_locks
))
4261 local_irq_save(flags
);
4262 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
4263 hlock
= curr
->held_locks
+ i
;
4265 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
4266 sizeof(*hlock
->instance
)))
4269 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
4272 local_irq_restore(flags
);
4274 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
4276 static void print_held_locks_bug(void)
4278 if (!debug_locks_off())
4280 if (debug_locks_silent
)
4284 printk("=====================================\n");
4285 printk("[ BUG: %s/%d still has locks held! ]\n",
4286 current
->comm
, task_pid_nr(current
));
4287 print_kernel_ident();
4288 printk("-------------------------------------\n");
4289 lockdep_print_held_locks(current
);
4290 printk("\nstack backtrace:\n");
4294 void debug_check_no_locks_held(void)
4296 if (unlikely(current
->lockdep_depth
> 0))
4297 print_held_locks_bug();
4299 EXPORT_SYMBOL_GPL(debug_check_no_locks_held
);
4302 void debug_show_all_locks(void)
4304 struct task_struct
*g
, *p
;
4308 if (unlikely(!debug_locks
)) {
4309 printk("INFO: lockdep is turned off.\n");
4312 printk("\nShowing all locks held in the system:\n");
4315 * Here we try to get the tasklist_lock as hard as possible,
4316 * if not successful after 2 seconds we ignore it (but keep
4317 * trying). This is to enable a debug printout even if a
4318 * tasklist_lock-holding task deadlocks or crashes.
4321 if (!read_trylock(&tasklist_lock
)) {
4323 printk("hm, tasklist_lock locked, retrying... ");
4326 printk(" #%d", 10-count
);
4330 printk(" ignoring it.\n");
4334 printk(KERN_CONT
" locked it.\n");
4337 do_each_thread(g
, p
) {
4339 * It's not reliable to print a task's held locks
4340 * if it's not sleeping (or if it's not the current
4343 if (p
->state
== TASK_RUNNING
&& p
!= current
)
4345 if (p
->lockdep_depth
)
4346 lockdep_print_held_locks(p
);
4348 if (read_trylock(&tasklist_lock
))
4350 } while_each_thread(g
, p
);
4353 printk("=============================================\n\n");
4356 read_unlock(&tasklist_lock
);
4358 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
4362 * Careful: only use this function if you are sure that
4363 * the task cannot run in parallel!
4365 void debug_show_held_locks(struct task_struct
*task
)
4367 if (unlikely(!debug_locks
)) {
4368 printk("INFO: lockdep is turned off.\n");
4371 lockdep_print_held_locks(task
);
4373 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
4375 asmlinkage __visible
void lockdep_sys_exit(void)
4377 struct task_struct
*curr
= current
;
4379 if (unlikely(curr
->lockdep_depth
)) {
4380 if (!debug_locks_off())
4383 printk("================================================\n");
4384 printk("[ BUG: lock held when returning to user space! ]\n");
4385 print_kernel_ident();
4386 printk("------------------------------------------------\n");
4387 printk("%s/%d is leaving the kernel with locks still held!\n",
4388 curr
->comm
, curr
->pid
);
4389 lockdep_print_held_locks(curr
);
4393 void lockdep_rcu_suspicious(const char *file
, const int line
, const char *s
)
4395 struct task_struct
*curr
= current
;
4397 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4398 if (!debug_locks_off())
4400 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4401 /* Note: the following can be executed concurrently, so be careful. */
4403 printk("===============================\n");
4404 printk("[ INFO: suspicious RCU usage. ]\n");
4405 print_kernel_ident();
4406 printk("-------------------------------\n");
4407 printk("%s:%d %s!\n", file
, line
, s
);
4408 printk("\nother info that might help us debug this:\n\n");
4409 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4410 !rcu_lockdep_current_cpu_online()
4411 ? "RCU used illegally from offline CPU!\n"
4412 : !rcu_is_watching()
4413 ? "RCU used illegally from idle CPU!\n"
4415 rcu_scheduler_active
, debug_locks
);
4418 * If a CPU is in the RCU-free window in idle (ie: in the section
4419 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4420 * considers that CPU to be in an "extended quiescent state",
4421 * which means that RCU will be completely ignoring that CPU.
4422 * Therefore, rcu_read_lock() and friends have absolutely no
4423 * effect on a CPU running in that state. In other words, even if
4424 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4425 * delete data structures out from under it. RCU really has no
4426 * choice here: we need to keep an RCU-free window in idle where
4427 * the CPU may possibly enter into low power mode. This way we can
4428 * notice an extended quiescent state to other CPUs that started a grace
4429 * period. Otherwise we would delay any grace period as long as we run
4432 * So complain bitterly if someone does call rcu_read_lock(),
4433 * rcu_read_lock_bh() and so on from extended quiescent states.
4435 if (!rcu_is_watching())
4436 printk("RCU used illegally from extended quiescent state!\n");
4438 lockdep_print_held_locks(curr
);
4439 printk("\nstack backtrace:\n");
4442 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious
);