4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
47 #include <linux/kmemcheck.h>
49 #include <asm/sections.h>
51 #include "lockdep_internals.h"
53 #define CREATE_TRACE_POINTS
54 #include <trace/events/lock.h>
56 #ifdef CONFIG_PROVE_LOCKING
57 int prove_locking
= 1;
58 module_param(prove_locking
, int, 0644);
60 #define prove_locking 0
63 #ifdef CONFIG_LOCK_STAT
65 module_param(lock_stat
, int, 0644);
71 * lockdep_lock: protects the lockdep graph, the hashes and the
72 * class/list/hash allocators.
74 * This is one of the rare exceptions where it's justified
75 * to use a raw spinlock - we really dont want the spinlock
76 * code to recurse back into the lockdep code...
78 static arch_spinlock_t lockdep_lock
= (arch_spinlock_t
)__ARCH_SPIN_LOCK_UNLOCKED
;
80 static int graph_lock(void)
82 arch_spin_lock(&lockdep_lock
);
84 * Make sure that if another CPU detected a bug while
85 * walking the graph we dont change it (while the other
86 * CPU is busy printing out stuff with the graph lock
90 arch_spin_unlock(&lockdep_lock
);
93 /* prevent any recursions within lockdep from causing deadlocks */
94 current
->lockdep_recursion
++;
98 static inline int graph_unlock(void)
100 if (debug_locks
&& !arch_spin_is_locked(&lockdep_lock
)) {
102 * The lockdep graph lock isn't locked while we expect it to
103 * be, we're confused now, bye!
105 return DEBUG_LOCKS_WARN_ON(1);
108 current
->lockdep_recursion
--;
109 arch_spin_unlock(&lockdep_lock
);
114 * Turn lock debugging off and return with 0 if it was off already,
115 * and also release the graph lock:
117 static inline int debug_locks_off_graph_unlock(void)
119 int ret
= debug_locks_off();
121 arch_spin_unlock(&lockdep_lock
);
126 static int lockdep_initialized
;
128 unsigned long nr_list_entries
;
129 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
132 * All data structures here are protected by the global debug_lock.
134 * Mutex key structs only get allocated, once during bootup, and never
135 * get freed - this significantly simplifies the debugging code.
137 unsigned long nr_lock_classes
;
138 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
140 static inline struct lock_class
*hlock_class(struct held_lock
*hlock
)
142 if (!hlock
->class_idx
) {
144 * Someone passed in garbage, we give up.
146 DEBUG_LOCKS_WARN_ON(1);
149 return lock_classes
+ hlock
->class_idx
- 1;
152 #ifdef CONFIG_LOCK_STAT
153 static DEFINE_PER_CPU(struct lock_class_stats
[MAX_LOCKDEP_KEYS
],
156 static inline u64
lockstat_clock(void)
158 return local_clock();
161 static int lock_point(unsigned long points
[], unsigned long ip
)
165 for (i
= 0; i
< LOCKSTAT_POINTS
; i
++) {
166 if (points
[i
] == 0) {
177 static void lock_time_inc(struct lock_time
*lt
, u64 time
)
182 if (time
< lt
->min
|| !lt
->nr
)
189 static inline void lock_time_add(struct lock_time
*src
, struct lock_time
*dst
)
194 if (src
->max
> dst
->max
)
197 if (src
->min
< dst
->min
|| !dst
->nr
)
200 dst
->total
+= src
->total
;
204 struct lock_class_stats
lock_stats(struct lock_class
*class)
206 struct lock_class_stats stats
;
209 memset(&stats
, 0, sizeof(struct lock_class_stats
));
210 for_each_possible_cpu(cpu
) {
211 struct lock_class_stats
*pcs
=
212 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
214 for (i
= 0; i
< ARRAY_SIZE(stats
.contention_point
); i
++)
215 stats
.contention_point
[i
] += pcs
->contention_point
[i
];
217 for (i
= 0; i
< ARRAY_SIZE(stats
.contending_point
); i
++)
218 stats
.contending_point
[i
] += pcs
->contending_point
[i
];
220 lock_time_add(&pcs
->read_waittime
, &stats
.read_waittime
);
221 lock_time_add(&pcs
->write_waittime
, &stats
.write_waittime
);
223 lock_time_add(&pcs
->read_holdtime
, &stats
.read_holdtime
);
224 lock_time_add(&pcs
->write_holdtime
, &stats
.write_holdtime
);
226 for (i
= 0; i
< ARRAY_SIZE(stats
.bounces
); i
++)
227 stats
.bounces
[i
] += pcs
->bounces
[i
];
233 void clear_lock_stats(struct lock_class
*class)
237 for_each_possible_cpu(cpu
) {
238 struct lock_class_stats
*cpu_stats
=
239 &per_cpu(cpu_lock_stats
, cpu
)[class - lock_classes
];
241 memset(cpu_stats
, 0, sizeof(struct lock_class_stats
));
243 memset(class->contention_point
, 0, sizeof(class->contention_point
));
244 memset(class->contending_point
, 0, sizeof(class->contending_point
));
247 static struct lock_class_stats
*get_lock_stats(struct lock_class
*class)
249 return &get_cpu_var(cpu_lock_stats
)[class - lock_classes
];
252 static void put_lock_stats(struct lock_class_stats
*stats
)
254 put_cpu_var(cpu_lock_stats
);
257 static void lock_release_holdtime(struct held_lock
*hlock
)
259 struct lock_class_stats
*stats
;
265 holdtime
= lockstat_clock() - hlock
->holdtime_stamp
;
267 stats
= get_lock_stats(hlock_class(hlock
));
269 lock_time_inc(&stats
->read_holdtime
, holdtime
);
271 lock_time_inc(&stats
->write_holdtime
, holdtime
);
272 put_lock_stats(stats
);
275 static inline void lock_release_holdtime(struct held_lock
*hlock
)
281 * We keep a global list of all lock classes. The list only grows,
282 * never shrinks. The list is only accessed with the lockdep
283 * spinlock lock held.
285 LIST_HEAD(all_lock_classes
);
288 * The lockdep classes are in a hash-table as well, for fast lookup:
290 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
291 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
292 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
293 #define classhashentry(key) (classhash_table + __classhashfn((key)))
295 static struct list_head classhash_table
[CLASSHASH_SIZE
];
298 * We put the lock dependency chains into a hash-table as well, to cache
301 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
302 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
303 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
304 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
306 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
309 * The hash key of the lock dependency chains is a hash itself too:
310 * it's a hash of all locks taken up to that lock, including that lock.
311 * It's a 64-bit hash, because it's important for the keys to be
314 #define iterate_chain_key(key1, key2) \
315 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
316 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
319 void lockdep_off(void)
321 current
->lockdep_recursion
++;
323 EXPORT_SYMBOL(lockdep_off
);
325 void lockdep_on(void)
327 current
->lockdep_recursion
--;
329 EXPORT_SYMBOL(lockdep_on
);
332 * Debugging switches:
336 #define VERY_VERBOSE 0
339 # define HARDIRQ_VERBOSE 1
340 # define SOFTIRQ_VERBOSE 1
341 # define RECLAIM_VERBOSE 1
343 # define HARDIRQ_VERBOSE 0
344 # define SOFTIRQ_VERBOSE 0
345 # define RECLAIM_VERBOSE 0
348 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
350 * Quick filtering for interesting events:
352 static int class_filter(struct lock_class
*class)
356 if (class->name_version
== 1 &&
357 !strcmp(class->name
, "lockname"))
359 if (class->name_version
== 1 &&
360 !strcmp(class->name
, "&struct->lockfield"))
363 /* Filter everything else. 1 would be to allow everything else */
368 static int verbose(struct lock_class
*class)
371 return class_filter(class);
377 * Stack-trace: tightly packed array of stack backtrace
378 * addresses. Protected by the graph_lock.
380 unsigned long nr_stack_trace_entries
;
381 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
383 static int save_trace(struct stack_trace
*trace
)
385 trace
->nr_entries
= 0;
386 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
387 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
391 save_stack_trace(trace
);
394 * Some daft arches put -1 at the end to indicate its a full trace.
396 * <rant> this is buggy anyway, since it takes a whole extra entry so a
397 * complete trace that maxes out the entries provided will be reported
398 * as incomplete, friggin useless </rant>
400 if (trace
->nr_entries
!= 0 &&
401 trace
->entries
[trace
->nr_entries
-1] == ULONG_MAX
)
404 trace
->max_entries
= trace
->nr_entries
;
406 nr_stack_trace_entries
+= trace
->nr_entries
;
408 if (nr_stack_trace_entries
>= MAX_STACK_TRACE_ENTRIES
-1) {
409 if (!debug_locks_off_graph_unlock())
412 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
413 printk("turning off the locking correctness validator.\n");
422 unsigned int nr_hardirq_chains
;
423 unsigned int nr_softirq_chains
;
424 unsigned int nr_process_chains
;
425 unsigned int max_lockdep_depth
;
427 #ifdef CONFIG_DEBUG_LOCKDEP
429 * We cannot printk in early bootup code. Not even early_printk()
430 * might work. So we mark any initialization errors and printk
431 * about it later on, in lockdep_info().
433 static int lockdep_init_error
;
434 static unsigned long lockdep_init_trace_data
[20];
435 static struct stack_trace lockdep_init_trace
= {
436 .max_entries
= ARRAY_SIZE(lockdep_init_trace_data
),
437 .entries
= lockdep_init_trace_data
,
441 * Various lockdep statistics:
443 DEFINE_PER_CPU(struct lockdep_stats
, lockdep_stats
);
450 #define __USAGE(__STATE) \
451 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
452 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
453 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
454 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
456 static const char *usage_str
[] =
458 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
459 #include "lockdep_states.h"
461 [LOCK_USED
] = "INITIAL USE",
464 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
466 return kallsyms_lookup((unsigned long)key
, NULL
, NULL
, NULL
, str
);
469 static inline unsigned long lock_flag(enum lock_usage_bit bit
)
474 static char get_usage_char(struct lock_class
*class, enum lock_usage_bit bit
)
478 if (class->usage_mask
& lock_flag(bit
+ 2))
480 if (class->usage_mask
& lock_flag(bit
)) {
482 if (class->usage_mask
& lock_flag(bit
+ 2))
489 void get_usage_chars(struct lock_class
*class, char usage
[LOCK_USAGE_CHARS
])
493 #define LOCKDEP_STATE(__STATE) \
494 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
495 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
496 #include "lockdep_states.h"
502 static void __print_lock_name(struct lock_class
*class)
504 char str
[KSYM_NAME_LEN
];
509 name
= __get_key_name(class->key
, str
);
513 if (class->name_version
> 1)
514 printk("#%d", class->name_version
);
516 printk("/%d", class->subclass
);
520 static void print_lock_name(struct lock_class
*class)
522 char usage
[LOCK_USAGE_CHARS
];
524 get_usage_chars(class, usage
);
527 __print_lock_name(class);
528 printk("){%s}", usage
);
531 static void print_lockdep_cache(struct lockdep_map
*lock
)
534 char str
[KSYM_NAME_LEN
];
538 name
= __get_key_name(lock
->key
->subkeys
, str
);
543 static void print_lock(struct held_lock
*hlock
)
545 print_lock_name(hlock_class(hlock
));
547 print_ip_sym(hlock
->acquire_ip
);
550 static void lockdep_print_held_locks(struct task_struct
*curr
)
552 int i
, depth
= curr
->lockdep_depth
;
555 printk("no locks held by %s/%d.\n", curr
->comm
, task_pid_nr(curr
));
558 printk("%d lock%s held by %s/%d:\n",
559 depth
, depth
> 1 ? "s" : "", curr
->comm
, task_pid_nr(curr
));
561 for (i
= 0; i
< depth
; i
++) {
563 print_lock(curr
->held_locks
+ i
);
567 static void print_kernel_version(void)
569 printk("%s %.*s\n", init_utsname()->release
,
570 (int)strcspn(init_utsname()->version
, " "),
571 init_utsname()->version
);
574 static int very_verbose(struct lock_class
*class)
577 return class_filter(class);
583 * Is this the address of a static object:
585 static int static_obj(void *obj
)
587 unsigned long start
= (unsigned long) &_stext
,
588 end
= (unsigned long) &_end
,
589 addr
= (unsigned long) obj
;
594 if ((addr
>= start
) && (addr
< end
))
597 if (arch_is_kernel_data(addr
))
601 * in-kernel percpu var?
603 if (is_kernel_percpu_address(addr
))
607 * module static or percpu var?
609 return is_module_address(addr
) || is_module_percpu_address(addr
);
613 * To make lock name printouts unique, we calculate a unique
614 * class->name_version generation counter:
616 static int count_matching_names(struct lock_class
*new_class
)
618 struct lock_class
*class;
621 if (!new_class
->name
)
624 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
625 if (new_class
->key
- new_class
->subclass
== class->key
)
626 return class->name_version
;
627 if (class->name
&& !strcmp(class->name
, new_class
->name
))
628 count
= max(count
, class->name_version
);
635 * Register a lock's class in the hash-table, if the class is not present
636 * yet. Otherwise we look it up. We cache the result in the lock object
637 * itself, so actual lookup of the hash should be once per lock object.
639 static inline struct lock_class
*
640 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
642 struct lockdep_subclass_key
*key
;
643 struct list_head
*hash_head
;
644 struct lock_class
*class;
646 #ifdef CONFIG_DEBUG_LOCKDEP
648 * If the architecture calls into lockdep before initializing
649 * the hashes then we'll warn about it later. (we cannot printk
652 if (unlikely(!lockdep_initialized
)) {
654 lockdep_init_error
= 1;
655 save_stack_trace(&lockdep_init_trace
);
659 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
662 "BUG: looking up invalid subclass: %u\n", subclass
);
664 "turning off the locking correctness validator.\n");
670 * Static locks do not have their class-keys yet - for them the key
671 * is the lock object itself:
673 if (unlikely(!lock
->key
))
674 lock
->key
= (void *)lock
;
677 * NOTE: the class-key must be unique. For dynamic locks, a static
678 * lock_class_key variable is passed in through the mutex_init()
679 * (or spin_lock_init()) call - which acts as the key. For static
680 * locks we use the lock object itself as the key.
682 BUILD_BUG_ON(sizeof(struct lock_class_key
) >
683 sizeof(struct lockdep_map
));
685 key
= lock
->key
->subkeys
+ subclass
;
687 hash_head
= classhashentry(key
);
690 * We can walk the hash lockfree, because the hash only
691 * grows, and we are careful when adding entries to the end:
693 list_for_each_entry(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 inline struct lock_class
*
713 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
715 struct lockdep_subclass_key
*key
;
716 struct list_head
*hash_head
;
717 struct lock_class
*class;
720 class = look_up_lock_class(lock
, subclass
);
725 * Debug-check: all keys must be persistent!
727 if (!static_obj(lock
->key
)) {
729 printk("INFO: trying to register non-static key.\n");
730 printk("the code is fine but needs lockdep annotation.\n");
731 printk("turning off the locking correctness validator.\n");
737 key
= lock
->key
->subkeys
+ subclass
;
738 hash_head
= classhashentry(key
);
740 raw_local_irq_save(flags
);
742 raw_local_irq_restore(flags
);
746 * We have to do the hash-walk again, to avoid races
749 list_for_each_entry(class, hash_head
, hash_entry
)
750 if (class->key
== key
)
753 * Allocate a new key from the static array, and add it to
756 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
757 if (!debug_locks_off_graph_unlock()) {
758 raw_local_irq_restore(flags
);
761 raw_local_irq_restore(flags
);
763 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
764 printk("turning off the locking correctness validator.\n");
768 class = lock_classes
+ nr_lock_classes
++;
769 debug_atomic_inc(nr_unused_locks
);
771 class->name
= lock
->name
;
772 class->subclass
= subclass
;
773 INIT_LIST_HEAD(&class->lock_entry
);
774 INIT_LIST_HEAD(&class->locks_before
);
775 INIT_LIST_HEAD(&class->locks_after
);
776 class->name_version
= count_matching_names(class);
778 * We use RCU's safe list-add method to make
779 * parallel walking of the hash-list safe:
781 list_add_tail_rcu(&class->hash_entry
, hash_head
);
783 * Add it to the global list of classes:
785 list_add_tail_rcu(&class->lock_entry
, &all_lock_classes
);
787 if (verbose(class)) {
789 raw_local_irq_restore(flags
);
791 printk("\nnew class %p: %s", class->key
, class->name
);
792 if (class->name_version
> 1)
793 printk("#%d", class->name_version
);
797 raw_local_irq_save(flags
);
799 raw_local_irq_restore(flags
);
805 raw_local_irq_restore(flags
);
807 if (!subclass
|| force
)
808 lock
->class_cache
[0] = class;
809 else if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
810 lock
->class_cache
[subclass
] = class;
813 * Hash collision, did we smoke some? We found a class with a matching
814 * hash but the subclass -- which is hashed in -- didn't match.
816 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
822 #ifdef CONFIG_PROVE_LOCKING
824 * Allocate a lockdep entry. (assumes the graph_lock held, returns
825 * with NULL on failure)
827 static struct lock_list
*alloc_list_entry(void)
829 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
830 if (!debug_locks_off_graph_unlock())
833 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
834 printk("turning off the locking correctness validator.\n");
838 return list_entries
+ nr_list_entries
++;
842 * Add a new dependency to the head of the list:
844 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
845 struct list_head
*head
, unsigned long ip
,
846 int distance
, struct stack_trace
*trace
)
848 struct lock_list
*entry
;
850 * Lock not present yet - get a new dependency struct and
851 * add it to the list:
853 entry
= alloc_list_entry();
858 entry
->distance
= distance
;
859 entry
->trace
= *trace
;
861 * Since we never remove from the dependency list, the list can
862 * be walked lockless by other CPUs, it's only allocation
863 * that must be protected by the spinlock. But this also means
864 * we must make new entries visible only once writes to the
865 * entry become visible - hence the RCU op:
867 list_add_tail_rcu(&entry
->entry
, head
);
873 * For good efficiency of modular, we use power of 2
875 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
876 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
879 * The circular_queue and helpers is used to implement the
880 * breadth-first search(BFS)algorithem, by which we can build
881 * the shortest path from the next lock to be acquired to the
882 * previous held lock if there is a circular between them.
884 struct circular_queue
{
885 unsigned long element
[MAX_CIRCULAR_QUEUE_SIZE
];
886 unsigned int front
, rear
;
889 static struct circular_queue lock_cq
;
891 unsigned int max_bfs_queue_depth
;
893 static unsigned int lockdep_dependency_gen_id
;
895 static inline void __cq_init(struct circular_queue
*cq
)
897 cq
->front
= cq
->rear
= 0;
898 lockdep_dependency_gen_id
++;
901 static inline int __cq_empty(struct circular_queue
*cq
)
903 return (cq
->front
== cq
->rear
);
906 static inline int __cq_full(struct circular_queue
*cq
)
908 return ((cq
->rear
+ 1) & CQ_MASK
) == cq
->front
;
911 static inline int __cq_enqueue(struct circular_queue
*cq
, unsigned long elem
)
916 cq
->element
[cq
->rear
] = elem
;
917 cq
->rear
= (cq
->rear
+ 1) & CQ_MASK
;
921 static inline int __cq_dequeue(struct circular_queue
*cq
, unsigned long *elem
)
926 *elem
= cq
->element
[cq
->front
];
927 cq
->front
= (cq
->front
+ 1) & CQ_MASK
;
931 static inline unsigned int __cq_get_elem_count(struct circular_queue
*cq
)
933 return (cq
->rear
- cq
->front
) & CQ_MASK
;
936 static inline void mark_lock_accessed(struct lock_list
*lock
,
937 struct lock_list
*parent
)
941 nr
= lock
- list_entries
;
942 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
943 lock
->parent
= parent
;
944 lock
->class->dep_gen_id
= lockdep_dependency_gen_id
;
947 static inline unsigned long lock_accessed(struct lock_list
*lock
)
951 nr
= lock
- list_entries
;
952 WARN_ON(nr
>= nr_list_entries
); /* Out-of-bounds, input fail */
953 return lock
->class->dep_gen_id
== lockdep_dependency_gen_id
;
956 static inline struct lock_list
*get_lock_parent(struct lock_list
*child
)
958 return child
->parent
;
961 static inline int get_lock_depth(struct lock_list
*child
)
964 struct lock_list
*parent
;
966 while ((parent
= get_lock_parent(child
))) {
973 static int __bfs(struct lock_list
*source_entry
,
975 int (*match
)(struct lock_list
*entry
, void *data
),
976 struct lock_list
**target_entry
,
979 struct lock_list
*entry
;
980 struct list_head
*head
;
981 struct circular_queue
*cq
= &lock_cq
;
984 if (match(source_entry
, data
)) {
985 *target_entry
= source_entry
;
991 head
= &source_entry
->class->locks_after
;
993 head
= &source_entry
->class->locks_before
;
995 if (list_empty(head
))
999 __cq_enqueue(cq
, (unsigned long)source_entry
);
1001 while (!__cq_empty(cq
)) {
1002 struct lock_list
*lock
;
1004 __cq_dequeue(cq
, (unsigned long *)&lock
);
1012 head
= &lock
->class->locks_after
;
1014 head
= &lock
->class->locks_before
;
1016 list_for_each_entry(entry
, head
, entry
) {
1017 if (!lock_accessed(entry
)) {
1018 unsigned int cq_depth
;
1019 mark_lock_accessed(entry
, lock
);
1020 if (match(entry
, data
)) {
1021 *target_entry
= entry
;
1026 if (__cq_enqueue(cq
, (unsigned long)entry
)) {
1030 cq_depth
= __cq_get_elem_count(cq
);
1031 if (max_bfs_queue_depth
< cq_depth
)
1032 max_bfs_queue_depth
= cq_depth
;
1040 static inline int __bfs_forwards(struct lock_list
*src_entry
,
1042 int (*match
)(struct lock_list
*entry
, void *data
),
1043 struct lock_list
**target_entry
)
1045 return __bfs(src_entry
, data
, match
, target_entry
, 1);
1049 static inline int __bfs_backwards(struct lock_list
*src_entry
,
1051 int (*match
)(struct lock_list
*entry
, void *data
),
1052 struct lock_list
**target_entry
)
1054 return __bfs(src_entry
, data
, match
, target_entry
, 0);
1059 * Recursive, forwards-direction lock-dependency checking, used for
1060 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1065 * Print a dependency chain entry (this is only done when a deadlock
1066 * has been detected):
1069 print_circular_bug_entry(struct lock_list
*target
, int depth
)
1071 if (debug_locks_silent
)
1073 printk("\n-> #%u", depth
);
1074 print_lock_name(target
->class);
1076 print_stack_trace(&target
->trace
, 6);
1082 print_circular_lock_scenario(struct held_lock
*src
,
1083 struct held_lock
*tgt
,
1084 struct lock_list
*prt
)
1086 struct lock_class
*source
= hlock_class(src
);
1087 struct lock_class
*target
= hlock_class(tgt
);
1088 struct lock_class
*parent
= prt
->class;
1091 * A direct locking problem where unsafe_class lock is taken
1092 * directly by safe_class lock, then all we need to show
1093 * is the deadlock scenario, as it is obvious that the
1094 * unsafe lock is taken under the safe lock.
1096 * But if there is a chain instead, where the safe lock takes
1097 * an intermediate lock (middle_class) where this lock is
1098 * not the same as the safe lock, then the lock chain is
1099 * used to describe the problem. Otherwise we would need
1100 * to show a different CPU case for each link in the chain
1101 * from the safe_class lock to the unsafe_class lock.
1103 if (parent
!= source
) {
1104 printk("Chain exists of:\n ");
1105 __print_lock_name(source
);
1107 __print_lock_name(parent
);
1109 __print_lock_name(target
);
1113 printk(" Possible unsafe locking scenario:\n\n");
1114 printk(" CPU0 CPU1\n");
1115 printk(" ---- ----\n");
1117 __print_lock_name(target
);
1120 __print_lock_name(parent
);
1123 __print_lock_name(target
);
1126 __print_lock_name(source
);
1128 printk("\n *** DEADLOCK ***\n\n");
1132 * When a circular dependency is detected, print the
1136 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
,
1137 struct held_lock
*check_src
,
1138 struct held_lock
*check_tgt
)
1140 struct task_struct
*curr
= current
;
1142 if (debug_locks_silent
)
1146 printk("======================================================\n");
1147 printk("[ INFO: possible circular locking dependency detected ]\n");
1148 print_kernel_version();
1149 printk("-------------------------------------------------------\n");
1150 printk("%s/%d is trying to acquire lock:\n",
1151 curr
->comm
, task_pid_nr(curr
));
1152 print_lock(check_src
);
1153 printk("\nbut task is already holding lock:\n");
1154 print_lock(check_tgt
);
1155 printk("\nwhich lock already depends on the new lock.\n\n");
1156 printk("\nthe existing dependency chain (in reverse order) is:\n");
1158 print_circular_bug_entry(entry
, depth
);
1163 static inline int class_equal(struct lock_list
*entry
, void *data
)
1165 return entry
->class == data
;
1168 static noinline
int print_circular_bug(struct lock_list
*this,
1169 struct lock_list
*target
,
1170 struct held_lock
*check_src
,
1171 struct held_lock
*check_tgt
)
1173 struct task_struct
*curr
= current
;
1174 struct lock_list
*parent
;
1175 struct lock_list
*first_parent
;
1178 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1181 if (!save_trace(&this->trace
))
1184 depth
= get_lock_depth(target
);
1186 print_circular_bug_header(target
, depth
, check_src
, check_tgt
);
1188 parent
= get_lock_parent(target
);
1189 first_parent
= parent
;
1192 print_circular_bug_entry(parent
, --depth
);
1193 parent
= get_lock_parent(parent
);
1196 printk("\nother info that might help us debug this:\n\n");
1197 print_circular_lock_scenario(check_src
, check_tgt
,
1200 lockdep_print_held_locks(curr
);
1202 printk("\nstack backtrace:\n");
1208 static noinline
int print_bfs_bug(int ret
)
1210 if (!debug_locks_off_graph_unlock())
1214 * Breadth-first-search failed, graph got corrupted?
1216 WARN(1, "lockdep bfs error:%d\n", ret
);
1221 static int noop_count(struct lock_list
*entry
, void *data
)
1223 (*(unsigned long *)data
)++;
1227 unsigned long __lockdep_count_forward_deps(struct lock_list
*this)
1229 unsigned long count
= 0;
1230 struct lock_list
*uninitialized_var(target_entry
);
1232 __bfs_forwards(this, (void *)&count
, noop_count
, &target_entry
);
1236 unsigned long lockdep_count_forward_deps(struct lock_class
*class)
1238 unsigned long ret
, flags
;
1239 struct lock_list
this;
1244 local_irq_save(flags
);
1245 arch_spin_lock(&lockdep_lock
);
1246 ret
= __lockdep_count_forward_deps(&this);
1247 arch_spin_unlock(&lockdep_lock
);
1248 local_irq_restore(flags
);
1253 unsigned long __lockdep_count_backward_deps(struct lock_list
*this)
1255 unsigned long count
= 0;
1256 struct lock_list
*uninitialized_var(target_entry
);
1258 __bfs_backwards(this, (void *)&count
, noop_count
, &target_entry
);
1263 unsigned long lockdep_count_backward_deps(struct lock_class
*class)
1265 unsigned long ret
, flags
;
1266 struct lock_list
this;
1271 local_irq_save(flags
);
1272 arch_spin_lock(&lockdep_lock
);
1273 ret
= __lockdep_count_backward_deps(&this);
1274 arch_spin_unlock(&lockdep_lock
);
1275 local_irq_restore(flags
);
1281 * Prove that the dependency graph starting at <entry> can not
1282 * lead to <target>. Print an error and return 0 if it does.
1285 check_noncircular(struct lock_list
*root
, struct lock_class
*target
,
1286 struct lock_list
**target_entry
)
1290 debug_atomic_inc(nr_cyclic_checks
);
1292 result
= __bfs_forwards(root
, target
, class_equal
, target_entry
);
1297 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1299 * Forwards and backwards subgraph searching, for the purposes of
1300 * proving that two subgraphs can be connected by a new dependency
1301 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1304 static inline int usage_match(struct lock_list
*entry
, void *bit
)
1306 return entry
->class->usage_mask
& (1 << (enum lock_usage_bit
)bit
);
1312 * Find a node in the forwards-direction dependency sub-graph starting
1313 * at @root->class that matches @bit.
1315 * Return 0 if such a node exists in the subgraph, and put that node
1316 * into *@target_entry.
1318 * Return 1 otherwise and keep *@target_entry unchanged.
1319 * Return <0 on error.
1322 find_usage_forwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1323 struct lock_list
**target_entry
)
1327 debug_atomic_inc(nr_find_usage_forwards_checks
);
1329 result
= __bfs_forwards(root
, (void *)bit
, usage_match
, target_entry
);
1335 * Find a node in the backwards-direction dependency sub-graph starting
1336 * at @root->class that matches @bit.
1338 * Return 0 if such a node exists in the subgraph, and put that node
1339 * into *@target_entry.
1341 * Return 1 otherwise and keep *@target_entry unchanged.
1342 * Return <0 on error.
1345 find_usage_backwards(struct lock_list
*root
, enum lock_usage_bit bit
,
1346 struct lock_list
**target_entry
)
1350 debug_atomic_inc(nr_find_usage_backwards_checks
);
1352 result
= __bfs_backwards(root
, (void *)bit
, usage_match
, target_entry
);
1357 static void print_lock_class_header(struct lock_class
*class, int depth
)
1361 printk("%*s->", depth
, "");
1362 print_lock_name(class);
1363 printk(" ops: %lu", class->ops
);
1366 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
1367 if (class->usage_mask
& (1 << bit
)) {
1370 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
1371 len
+= printk(" at:\n");
1372 print_stack_trace(class->usage_traces
+ bit
, len
);
1375 printk("%*s }\n", depth
, "");
1377 printk("%*s ... key at: ",depth
,"");
1378 print_ip_sym((unsigned long)class->key
);
1382 * printk the shortest lock dependencies from @start to @end in reverse order:
1385 print_shortest_lock_dependencies(struct lock_list
*leaf
,
1386 struct lock_list
*root
)
1388 struct lock_list
*entry
= leaf
;
1391 /*compute depth from generated tree by BFS*/
1392 depth
= get_lock_depth(leaf
);
1395 print_lock_class_header(entry
->class, depth
);
1396 printk("%*s ... acquired at:\n", depth
, "");
1397 print_stack_trace(&entry
->trace
, 2);
1400 if (depth
== 0 && (entry
!= root
)) {
1401 printk("lockdep:%s bad path found in chain graph\n", __func__
);
1405 entry
= get_lock_parent(entry
);
1407 } while (entry
&& (depth
>= 0));
1413 print_irq_lock_scenario(struct lock_list
*safe_entry
,
1414 struct lock_list
*unsafe_entry
,
1415 struct lock_class
*prev_class
,
1416 struct lock_class
*next_class
)
1418 struct lock_class
*safe_class
= safe_entry
->class;
1419 struct lock_class
*unsafe_class
= unsafe_entry
->class;
1420 struct lock_class
*middle_class
= prev_class
;
1422 if (middle_class
== safe_class
)
1423 middle_class
= next_class
;
1426 * A direct locking problem where unsafe_class lock is taken
1427 * directly by safe_class lock, then all we need to show
1428 * is the deadlock scenario, as it is obvious that the
1429 * unsafe lock is taken under the safe lock.
1431 * But if there is a chain instead, where the safe lock takes
1432 * an intermediate lock (middle_class) where this lock is
1433 * not the same as the safe lock, then the lock chain is
1434 * used to describe the problem. Otherwise we would need
1435 * to show a different CPU case for each link in the chain
1436 * from the safe_class lock to the unsafe_class lock.
1438 if (middle_class
!= unsafe_class
) {
1439 printk("Chain exists of:\n ");
1440 __print_lock_name(safe_class
);
1442 __print_lock_name(middle_class
);
1444 __print_lock_name(unsafe_class
);
1448 printk(" Possible interrupt unsafe locking scenario:\n\n");
1449 printk(" CPU0 CPU1\n");
1450 printk(" ---- ----\n");
1452 __print_lock_name(unsafe_class
);
1454 printk(" local_irq_disable();\n");
1456 __print_lock_name(safe_class
);
1459 __print_lock_name(middle_class
);
1461 printk(" <Interrupt>\n");
1463 __print_lock_name(safe_class
);
1465 printk("\n *** DEADLOCK ***\n\n");
1469 print_bad_irq_dependency(struct task_struct
*curr
,
1470 struct lock_list
*prev_root
,
1471 struct lock_list
*next_root
,
1472 struct lock_list
*backwards_entry
,
1473 struct lock_list
*forwards_entry
,
1474 struct held_lock
*prev
,
1475 struct held_lock
*next
,
1476 enum lock_usage_bit bit1
,
1477 enum lock_usage_bit bit2
,
1478 const char *irqclass
)
1480 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1484 printk("======================================================\n");
1485 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1486 irqclass
, irqclass
);
1487 print_kernel_version();
1488 printk("------------------------------------------------------\n");
1489 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1490 curr
->comm
, task_pid_nr(curr
),
1491 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
1492 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
1493 curr
->hardirqs_enabled
,
1494 curr
->softirqs_enabled
);
1497 printk("\nand this task is already holding:\n");
1499 printk("which would create a new lock dependency:\n");
1500 print_lock_name(hlock_class(prev
));
1502 print_lock_name(hlock_class(next
));
1505 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1507 print_lock_name(backwards_entry
->class);
1508 printk("\n... which became %s-irq-safe at:\n", irqclass
);
1510 print_stack_trace(backwards_entry
->class->usage_traces
+ bit1
, 1);
1512 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
1513 print_lock_name(forwards_entry
->class);
1514 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
1517 print_stack_trace(forwards_entry
->class->usage_traces
+ bit2
, 1);
1519 printk("\nother info that might help us debug this:\n\n");
1520 print_irq_lock_scenario(backwards_entry
, forwards_entry
,
1521 hlock_class(prev
), hlock_class(next
));
1523 lockdep_print_held_locks(curr
);
1525 printk("\nthe dependencies between %s-irq-safe lock", irqclass
);
1526 printk(" and the holding lock:\n");
1527 if (!save_trace(&prev_root
->trace
))
1529 print_shortest_lock_dependencies(backwards_entry
, prev_root
);
1531 printk("\nthe dependencies between the lock to be acquired");
1532 printk(" and %s-irq-unsafe lock:\n", irqclass
);
1533 if (!save_trace(&next_root
->trace
))
1535 print_shortest_lock_dependencies(forwards_entry
, next_root
);
1537 printk("\nstack backtrace:\n");
1544 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1545 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
1546 enum lock_usage_bit bit_forwards
, const char *irqclass
)
1549 struct lock_list
this, that
;
1550 struct lock_list
*uninitialized_var(target_entry
);
1551 struct lock_list
*uninitialized_var(target_entry1
);
1555 this.class = hlock_class(prev
);
1556 ret
= find_usage_backwards(&this, bit_backwards
, &target_entry
);
1558 return print_bfs_bug(ret
);
1563 that
.class = hlock_class(next
);
1564 ret
= find_usage_forwards(&that
, bit_forwards
, &target_entry1
);
1566 return print_bfs_bug(ret
);
1570 return print_bad_irq_dependency(curr
, &this, &that
,
1571 target_entry
, target_entry1
,
1573 bit_backwards
, bit_forwards
, irqclass
);
1576 static const char *state_names
[] = {
1577 #define LOCKDEP_STATE(__STATE) \
1578 __stringify(__STATE),
1579 #include "lockdep_states.h"
1580 #undef LOCKDEP_STATE
1583 static const char *state_rnames
[] = {
1584 #define LOCKDEP_STATE(__STATE) \
1585 __stringify(__STATE)"-READ",
1586 #include "lockdep_states.h"
1587 #undef LOCKDEP_STATE
1590 static inline const char *state_name(enum lock_usage_bit bit
)
1592 return (bit
& 1) ? state_rnames
[bit
>> 2] : state_names
[bit
>> 2];
1595 static int exclusive_bit(int new_bit
)
1603 * bit 0 - write/read
1604 * bit 1 - used_in/enabled
1608 int state
= new_bit
& ~3;
1609 int dir
= new_bit
& 2;
1612 * keep state, bit flip the direction and strip read.
1614 return state
| (dir
^ 2);
1617 static int check_irq_usage(struct task_struct
*curr
, struct held_lock
*prev
,
1618 struct held_lock
*next
, enum lock_usage_bit bit
)
1621 * Prove that the new dependency does not connect a hardirq-safe
1622 * lock with a hardirq-unsafe lock - to achieve this we search
1623 * the backwards-subgraph starting at <prev>, and the
1624 * forwards-subgraph starting at <next>:
1626 if (!check_usage(curr
, prev
, next
, bit
,
1627 exclusive_bit(bit
), state_name(bit
)))
1633 * Prove that the new dependency does not connect a hardirq-safe-read
1634 * lock with a hardirq-unsafe lock - to achieve this we search
1635 * the backwards-subgraph starting at <prev>, and the
1636 * forwards-subgraph starting at <next>:
1638 if (!check_usage(curr
, prev
, next
, bit
,
1639 exclusive_bit(bit
), state_name(bit
)))
1646 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1647 struct held_lock
*next
)
1649 #define LOCKDEP_STATE(__STATE) \
1650 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1652 #include "lockdep_states.h"
1653 #undef LOCKDEP_STATE
1658 static void inc_chains(void)
1660 if (current
->hardirq_context
)
1661 nr_hardirq_chains
++;
1663 if (current
->softirq_context
)
1664 nr_softirq_chains
++;
1666 nr_process_chains
++;
1673 check_prev_add_irq(struct task_struct
*curr
, struct held_lock
*prev
,
1674 struct held_lock
*next
)
1679 static inline void inc_chains(void)
1681 nr_process_chains
++;
1687 print_deadlock_scenario(struct held_lock
*nxt
,
1688 struct held_lock
*prv
)
1690 struct lock_class
*next
= hlock_class(nxt
);
1691 struct lock_class
*prev
= hlock_class(prv
);
1693 printk(" Possible unsafe locking scenario:\n\n");
1697 __print_lock_name(prev
);
1700 __print_lock_name(next
);
1702 printk("\n *** DEADLOCK ***\n\n");
1703 printk(" May be due to missing lock nesting notation\n\n");
1707 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
1708 struct held_lock
*next
)
1710 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1714 printk("=============================================\n");
1715 printk("[ INFO: possible recursive locking detected ]\n");
1716 print_kernel_version();
1717 printk("---------------------------------------------\n");
1718 printk("%s/%d is trying to acquire lock:\n",
1719 curr
->comm
, task_pid_nr(curr
));
1721 printk("\nbut task is already holding lock:\n");
1724 printk("\nother info that might help us debug this:\n");
1725 print_deadlock_scenario(next
, prev
);
1726 lockdep_print_held_locks(curr
);
1728 printk("\nstack backtrace:\n");
1735 * Check whether we are holding such a class already.
1737 * (Note that this has to be done separately, because the graph cannot
1738 * detect such classes of deadlocks.)
1740 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1743 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
1744 struct lockdep_map
*next_instance
, int read
)
1746 struct held_lock
*prev
;
1747 struct held_lock
*nest
= NULL
;
1750 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1751 prev
= curr
->held_locks
+ i
;
1753 if (prev
->instance
== next
->nest_lock
)
1756 if (hlock_class(prev
) != hlock_class(next
))
1760 * Allow read-after-read recursion of the same
1761 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1763 if ((read
== 2) && prev
->read
)
1767 * We're holding the nest_lock, which serializes this lock's
1768 * nesting behaviour.
1773 return print_deadlock_bug(curr
, prev
, next
);
1779 * There was a chain-cache miss, and we are about to add a new dependency
1780 * to a previous lock. We recursively validate the following rules:
1782 * - would the adding of the <prev> -> <next> dependency create a
1783 * circular dependency in the graph? [== circular deadlock]
1785 * - does the new prev->next dependency connect any hardirq-safe lock
1786 * (in the full backwards-subgraph starting at <prev>) with any
1787 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1788 * <next>)? [== illegal lock inversion with hardirq contexts]
1790 * - does the new prev->next dependency connect any softirq-safe lock
1791 * (in the full backwards-subgraph starting at <prev>) with any
1792 * softirq-unsafe lock (in the full forwards-subgraph starting at
1793 * <next>)? [== illegal lock inversion with softirq contexts]
1795 * any of these scenarios could lead to a deadlock.
1797 * Then if all the validations pass, we add the forwards and backwards
1801 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
1802 struct held_lock
*next
, int distance
, int trylock_loop
)
1804 struct lock_list
*entry
;
1806 struct lock_list
this;
1807 struct lock_list
*uninitialized_var(target_entry
);
1809 * Static variable, serialized by the graph_lock().
1811 * We use this static variable to save the stack trace in case
1812 * we call into this function multiple times due to encountering
1813 * trylocks in the held lock stack.
1815 static struct stack_trace trace
;
1818 * Prove that the new <prev> -> <next> dependency would not
1819 * create a circular dependency in the graph. (We do this by
1820 * forward-recursing into the graph starting at <next>, and
1821 * checking whether we can reach <prev>.)
1823 * We are using global variables to control the recursion, to
1824 * keep the stackframe size of the recursive functions low:
1826 this.class = hlock_class(next
);
1828 ret
= check_noncircular(&this, hlock_class(prev
), &target_entry
);
1830 return print_circular_bug(&this, target_entry
, next
, prev
);
1831 else if (unlikely(ret
< 0))
1832 return print_bfs_bug(ret
);
1834 if (!check_prev_add_irq(curr
, prev
, next
))
1838 * For recursive read-locks we do all the dependency checks,
1839 * but we dont store read-triggered dependencies (only
1840 * write-triggered dependencies). This ensures that only the
1841 * write-side dependencies matter, and that if for example a
1842 * write-lock never takes any other locks, then the reads are
1843 * equivalent to a NOP.
1845 if (next
->read
== 2 || prev
->read
== 2)
1848 * Is the <prev> -> <next> dependency already present?
1850 * (this may occur even though this is a new chain: consider
1851 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1852 * chains - the second one will be new, but L1 already has
1853 * L2 added to its dependency list, due to the first chain.)
1855 list_for_each_entry(entry
, &hlock_class(prev
)->locks_after
, entry
) {
1856 if (entry
->class == hlock_class(next
)) {
1858 entry
->distance
= 1;
1863 if (!trylock_loop
&& !save_trace(&trace
))
1867 * Ok, all validations passed, add the new lock
1868 * to the previous lock's dependency list:
1870 ret
= add_lock_to_list(hlock_class(prev
), hlock_class(next
),
1871 &hlock_class(prev
)->locks_after
,
1872 next
->acquire_ip
, distance
, &trace
);
1877 ret
= add_lock_to_list(hlock_class(next
), hlock_class(prev
),
1878 &hlock_class(next
)->locks_before
,
1879 next
->acquire_ip
, distance
, &trace
);
1884 * Debugging printouts:
1886 if (verbose(hlock_class(prev
)) || verbose(hlock_class(next
))) {
1888 printk("\n new dependency: ");
1889 print_lock_name(hlock_class(prev
));
1891 print_lock_name(hlock_class(next
));
1894 return graph_lock();
1900 * Add the dependency to all directly-previous locks that are 'relevant'.
1901 * The ones that are relevant are (in increasing distance from curr):
1902 * all consecutive trylock entries and the final non-trylock entry - or
1903 * the end of this context's lock-chain - whichever comes first.
1906 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1908 int depth
= curr
->lockdep_depth
;
1909 int trylock_loop
= 0;
1910 struct held_lock
*hlock
;
1915 * Depth must not be zero for a non-head lock:
1920 * At least two relevant locks must exist for this
1923 if (curr
->held_locks
[depth
].irq_context
!=
1924 curr
->held_locks
[depth
-1].irq_context
)
1928 int distance
= curr
->lockdep_depth
- depth
+ 1;
1929 hlock
= curr
->held_locks
+ depth
-1;
1931 * Only non-recursive-read entries get new dependencies
1934 if (hlock
->read
!= 2) {
1935 if (!check_prev_add(curr
, hlock
, next
,
1936 distance
, trylock_loop
))
1939 * Stop after the first non-trylock entry,
1940 * as non-trylock entries have added their
1941 * own direct dependencies already, so this
1942 * lock is connected to them indirectly:
1944 if (!hlock
->trylock
)
1949 * End of lock-stack?
1954 * Stop the search if we cross into another context:
1956 if (curr
->held_locks
[depth
].irq_context
!=
1957 curr
->held_locks
[depth
-1].irq_context
)
1963 if (!debug_locks_off_graph_unlock())
1967 * Clearly we all shouldn't be here, but since we made it we
1968 * can reliable say we messed up our state. See the above two
1969 * gotos for reasons why we could possibly end up here.
1976 unsigned long nr_lock_chains
;
1977 struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
1978 int nr_chain_hlocks
;
1979 static u16 chain_hlocks
[MAX_LOCKDEP_CHAIN_HLOCKS
];
1981 struct lock_class
*lock_chain_get_class(struct lock_chain
*chain
, int i
)
1983 return lock_classes
+ chain_hlocks
[chain
->base
+ i
];
1987 * Look up a dependency chain. If the key is not present yet then
1988 * add it and return 1 - in this case the new dependency chain is
1989 * validated. If the key is already hashed, return 0.
1990 * (On return with 1 graph_lock is held.)
1992 static inline int lookup_chain_cache(struct task_struct
*curr
,
1993 struct held_lock
*hlock
,
1996 struct lock_class
*class = hlock_class(hlock
);
1997 struct list_head
*hash_head
= chainhashentry(chain_key
);
1998 struct lock_chain
*chain
;
1999 struct held_lock
*hlock_curr
, *hlock_next
;
2003 * We might need to take the graph lock, ensure we've got IRQs
2004 * disabled to make this an IRQ-safe lock.. for recursion reasons
2005 * lockdep won't complain about its own locking errors.
2007 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2010 * We can walk it lock-free, because entries only get added
2013 list_for_each_entry(chain
, hash_head
, entry
) {
2014 if (chain
->chain_key
== chain_key
) {
2016 debug_atomic_inc(chain_lookup_hits
);
2017 if (very_verbose(class))
2018 printk("\nhash chain already cached, key: "
2019 "%016Lx tail class: [%p] %s\n",
2020 (unsigned long long)chain_key
,
2021 class->key
, class->name
);
2025 if (very_verbose(class))
2026 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2027 (unsigned long long)chain_key
, class->key
, class->name
);
2029 * Allocate a new chain entry from the static array, and add
2035 * We have to walk the chain again locked - to avoid duplicates:
2037 list_for_each_entry(chain
, hash_head
, entry
) {
2038 if (chain
->chain_key
== chain_key
) {
2043 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
2044 if (!debug_locks_off_graph_unlock())
2047 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2048 printk("turning off the locking correctness validator.\n");
2052 chain
= lock_chains
+ nr_lock_chains
++;
2053 chain
->chain_key
= chain_key
;
2054 chain
->irq_context
= hlock
->irq_context
;
2055 /* Find the first held_lock of current chain */
2057 for (i
= curr
->lockdep_depth
- 1; i
>= 0; i
--) {
2058 hlock_curr
= curr
->held_locks
+ i
;
2059 if (hlock_curr
->irq_context
!= hlock_next
->irq_context
)
2064 chain
->depth
= curr
->lockdep_depth
+ 1 - i
;
2065 if (likely(nr_chain_hlocks
+ chain
->depth
<= MAX_LOCKDEP_CHAIN_HLOCKS
)) {
2066 chain
->base
= nr_chain_hlocks
;
2067 nr_chain_hlocks
+= chain
->depth
;
2068 for (j
= 0; j
< chain
->depth
- 1; j
++, i
++) {
2069 int lock_id
= curr
->held_locks
[i
].class_idx
- 1;
2070 chain_hlocks
[chain
->base
+ j
] = lock_id
;
2072 chain_hlocks
[chain
->base
+ j
] = class - lock_classes
;
2074 list_add_tail_rcu(&chain
->entry
, hash_head
);
2075 debug_atomic_inc(chain_lookup_misses
);
2081 static int validate_chain(struct task_struct
*curr
, struct lockdep_map
*lock
,
2082 struct held_lock
*hlock
, int chain_head
, u64 chain_key
)
2085 * Trylock needs to maintain the stack of held locks, but it
2086 * does not add new dependencies, because trylock can be done
2089 * We look up the chain_key and do the O(N^2) check and update of
2090 * the dependencies only if this is a new dependency chain.
2091 * (If lookup_chain_cache() returns with 1 it acquires
2092 * graph_lock for us)
2094 if (!hlock
->trylock
&& (hlock
->check
== 2) &&
2095 lookup_chain_cache(curr
, hlock
, chain_key
)) {
2097 * Check whether last held lock:
2099 * - is irq-safe, if this lock is irq-unsafe
2100 * - is softirq-safe, if this lock is hardirq-unsafe
2102 * And check whether the new lock's dependency graph
2103 * could lead back to the previous lock.
2105 * any of these scenarios could lead to a deadlock. If
2108 int ret
= check_deadlock(curr
, hlock
, lock
, hlock
->read
);
2113 * Mark recursive read, as we jump over it when
2114 * building dependencies (just like we jump over
2120 * Add dependency only if this lock is not the head
2121 * of the chain, and if it's not a secondary read-lock:
2123 if (!chain_head
&& ret
!= 2)
2124 if (!check_prevs_add(curr
, hlock
))
2128 /* after lookup_chain_cache(): */
2129 if (unlikely(!debug_locks
))
2135 static inline int validate_chain(struct task_struct
*curr
,
2136 struct lockdep_map
*lock
, struct held_lock
*hlock
,
2137 int chain_head
, u64 chain_key
)
2144 * We are building curr_chain_key incrementally, so double-check
2145 * it from scratch, to make sure that it's done correctly:
2147 static void check_chain_key(struct task_struct
*curr
)
2149 #ifdef CONFIG_DEBUG_LOCKDEP
2150 struct held_lock
*hlock
, *prev_hlock
= NULL
;
2154 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2155 hlock
= curr
->held_locks
+ i
;
2156 if (chain_key
!= hlock
->prev_chain_key
) {
2159 * We got mighty confused, our chain keys don't match
2160 * with what we expect, someone trample on our task state?
2162 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2163 curr
->lockdep_depth
, i
,
2164 (unsigned long long)chain_key
,
2165 (unsigned long long)hlock
->prev_chain_key
);
2168 id
= hlock
->class_idx
- 1;
2170 * Whoops ran out of static storage again?
2172 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2175 if (prev_hlock
&& (prev_hlock
->irq_context
!=
2176 hlock
->irq_context
))
2178 chain_key
= iterate_chain_key(chain_key
, id
);
2181 if (chain_key
!= curr
->curr_chain_key
) {
2184 * More smoking hash instead of calculating it, damn see these
2185 * numbers float.. I bet that a pink elephant stepped on my memory.
2187 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2188 curr
->lockdep_depth
, i
,
2189 (unsigned long long)chain_key
,
2190 (unsigned long long)curr
->curr_chain_key
);
2196 print_usage_bug_scenario(struct held_lock
*lock
)
2198 struct lock_class
*class = hlock_class(lock
);
2200 printk(" Possible unsafe locking scenario:\n\n");
2204 __print_lock_name(class);
2206 printk(" <Interrupt>\n");
2208 __print_lock_name(class);
2210 printk("\n *** DEADLOCK ***\n\n");
2214 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
2215 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
2217 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2221 printk("=================================\n");
2222 printk("[ INFO: inconsistent lock state ]\n");
2223 print_kernel_version();
2224 printk("---------------------------------\n");
2226 printk("inconsistent {%s} -> {%s} usage.\n",
2227 usage_str
[prev_bit
], usage_str
[new_bit
]);
2229 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2230 curr
->comm
, task_pid_nr(curr
),
2231 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
2232 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
2233 trace_hardirqs_enabled(curr
),
2234 trace_softirqs_enabled(curr
));
2237 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
2238 print_stack_trace(hlock_class(this)->usage_traces
+ prev_bit
, 1);
2240 print_irqtrace_events(curr
);
2241 printk("\nother info that might help us debug this:\n");
2242 print_usage_bug_scenario(this);
2244 lockdep_print_held_locks(curr
);
2246 printk("\nstack backtrace:\n");
2253 * Print out an error if an invalid bit is set:
2256 valid_state(struct task_struct
*curr
, struct held_lock
*this,
2257 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
2259 if (unlikely(hlock_class(this)->usage_mask
& (1 << bad_bit
)))
2260 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
2264 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2265 enum lock_usage_bit new_bit
);
2267 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2270 * print irq inversion bug:
2273 print_irq_inversion_bug(struct task_struct
*curr
,
2274 struct lock_list
*root
, struct lock_list
*other
,
2275 struct held_lock
*this, int forwards
,
2276 const char *irqclass
)
2278 struct lock_list
*entry
= other
;
2279 struct lock_list
*middle
= NULL
;
2282 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
2286 printk("=========================================================\n");
2287 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2288 print_kernel_version();
2289 printk("---------------------------------------------------------\n");
2290 printk("%s/%d just changed the state of lock:\n",
2291 curr
->comm
, task_pid_nr(curr
));
2294 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass
);
2296 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass
);
2297 print_lock_name(other
->class);
2298 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2300 printk("\nother info that might help us debug this:\n");
2302 /* Find a middle lock (if one exists) */
2303 depth
= get_lock_depth(other
);
2305 if (depth
== 0 && (entry
!= root
)) {
2306 printk("lockdep:%s bad path found in chain graph\n", __func__
);
2310 entry
= get_lock_parent(entry
);
2312 } while (entry
&& entry
!= root
&& (depth
>= 0));
2314 print_irq_lock_scenario(root
, other
,
2315 middle
? middle
->class : root
->class, other
->class);
2317 print_irq_lock_scenario(other
, root
,
2318 middle
? middle
->class : other
->class, root
->class);
2320 lockdep_print_held_locks(curr
);
2322 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2323 if (!save_trace(&root
->trace
))
2325 print_shortest_lock_dependencies(other
, root
);
2327 printk("\nstack backtrace:\n");
2334 * Prove that in the forwards-direction subgraph starting at <this>
2335 * there is no lock matching <mask>:
2338 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
2339 enum lock_usage_bit bit
, const char *irqclass
)
2342 struct lock_list root
;
2343 struct lock_list
*uninitialized_var(target_entry
);
2346 root
.class = hlock_class(this);
2347 ret
= find_usage_forwards(&root
, bit
, &target_entry
);
2349 return print_bfs_bug(ret
);
2353 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2358 * Prove that in the backwards-direction subgraph starting at <this>
2359 * there is no lock matching <mask>:
2362 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
2363 enum lock_usage_bit bit
, const char *irqclass
)
2366 struct lock_list root
;
2367 struct lock_list
*uninitialized_var(target_entry
);
2370 root
.class = hlock_class(this);
2371 ret
= find_usage_backwards(&root
, bit
, &target_entry
);
2373 return print_bfs_bug(ret
);
2377 return print_irq_inversion_bug(curr
, &root
, target_entry
,
2381 void print_irqtrace_events(struct task_struct
*curr
)
2383 printk("irq event stamp: %u\n", curr
->irq_events
);
2384 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
2385 print_ip_sym(curr
->hardirq_enable_ip
);
2386 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
2387 print_ip_sym(curr
->hardirq_disable_ip
);
2388 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
2389 print_ip_sym(curr
->softirq_enable_ip
);
2390 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
2391 print_ip_sym(curr
->softirq_disable_ip
);
2394 static int HARDIRQ_verbose(struct lock_class
*class)
2397 return class_filter(class);
2402 static int SOFTIRQ_verbose(struct lock_class
*class)
2405 return class_filter(class);
2410 static int RECLAIM_FS_verbose(struct lock_class
*class)
2413 return class_filter(class);
2418 #define STRICT_READ_CHECKS 1
2420 static int (*state_verbose_f
[])(struct lock_class
*class) = {
2421 #define LOCKDEP_STATE(__STATE) \
2423 #include "lockdep_states.h"
2424 #undef LOCKDEP_STATE
2427 static inline int state_verbose(enum lock_usage_bit bit
,
2428 struct lock_class
*class)
2430 return state_verbose_f
[bit
>> 2](class);
2433 typedef int (*check_usage_f
)(struct task_struct
*, struct held_lock
*,
2434 enum lock_usage_bit bit
, const char *name
);
2437 mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2438 enum lock_usage_bit new_bit
)
2440 int excl_bit
= exclusive_bit(new_bit
);
2441 int read
= new_bit
& 1;
2442 int dir
= new_bit
& 2;
2445 * mark USED_IN has to look forwards -- to ensure no dependency
2446 * has ENABLED state, which would allow recursion deadlocks.
2448 * mark ENABLED has to look backwards -- to ensure no dependee
2449 * has USED_IN state, which, again, would allow recursion deadlocks.
2451 check_usage_f usage
= dir
?
2452 check_usage_backwards
: check_usage_forwards
;
2455 * Validate that this particular lock does not have conflicting
2458 if (!valid_state(curr
, this, new_bit
, excl_bit
))
2462 * Validate that the lock dependencies don't have conflicting usage
2465 if ((!read
|| !dir
|| STRICT_READ_CHECKS
) &&
2466 !usage(curr
, this, excl_bit
, state_name(new_bit
& ~1)))
2470 * Check for read in write conflicts
2473 if (!valid_state(curr
, this, new_bit
, excl_bit
+ 1))
2476 if (STRICT_READ_CHECKS
&&
2477 !usage(curr
, this, excl_bit
+ 1,
2478 state_name(new_bit
+ 1)))
2482 if (state_verbose(new_bit
, hlock_class(this)))
2489 #define LOCKDEP_STATE(__STATE) __STATE,
2490 #include "lockdep_states.h"
2491 #undef LOCKDEP_STATE
2495 * Mark all held locks with a usage bit:
2498 mark_held_locks(struct task_struct
*curr
, enum mark_type mark
)
2500 enum lock_usage_bit usage_bit
;
2501 struct held_lock
*hlock
;
2504 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2505 hlock
= curr
->held_locks
+ i
;
2507 usage_bit
= 2 + (mark
<< 2); /* ENABLED */
2509 usage_bit
+= 1; /* READ */
2511 BUG_ON(usage_bit
>= LOCK_USAGE_STATES
);
2513 if (hlock_class(hlock
)->key
== __lockdep_no_validate__
.subkeys
)
2516 if (!mark_lock(curr
, hlock
, usage_bit
))
2524 * Hardirqs will be enabled:
2526 static void __trace_hardirqs_on_caller(unsigned long ip
)
2528 struct task_struct
*curr
= current
;
2530 /* we'll do an OFF -> ON transition: */
2531 curr
->hardirqs_enabled
= 1;
2534 * We are going to turn hardirqs on, so set the
2535 * usage bit for all held locks:
2537 if (!mark_held_locks(curr
, HARDIRQ
))
2540 * If we have softirqs enabled, then set the usage
2541 * bit for all held locks. (disabled hardirqs prevented
2542 * this bit from being set before)
2544 if (curr
->softirqs_enabled
)
2545 if (!mark_held_locks(curr
, SOFTIRQ
))
2548 curr
->hardirq_enable_ip
= ip
;
2549 curr
->hardirq_enable_event
= ++curr
->irq_events
;
2550 debug_atomic_inc(hardirqs_on_events
);
2553 void trace_hardirqs_on_caller(unsigned long ip
)
2555 time_hardirqs_on(CALLER_ADDR0
, ip
);
2557 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2560 if (unlikely(current
->hardirqs_enabled
)) {
2562 * Neither irq nor preemption are disabled here
2563 * so this is racy by nature but losing one hit
2564 * in a stat is not a big deal.
2566 __debug_atomic_inc(redundant_hardirqs_on
);
2571 * We're enabling irqs and according to our state above irqs weren't
2572 * already enabled, yet we find the hardware thinks they are in fact
2573 * enabled.. someone messed up their IRQ state tracing.
2575 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2579 * See the fine text that goes along with this variable definition.
2581 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled
)))
2585 * Can't allow enabling interrupts while in an interrupt handler,
2586 * that's general bad form and such. Recursion, limited stack etc..
2588 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
2591 current
->lockdep_recursion
= 1;
2592 __trace_hardirqs_on_caller(ip
);
2593 current
->lockdep_recursion
= 0;
2595 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
2597 void trace_hardirqs_on(void)
2599 trace_hardirqs_on_caller(CALLER_ADDR0
);
2601 EXPORT_SYMBOL(trace_hardirqs_on
);
2604 * Hardirqs were disabled:
2606 void trace_hardirqs_off_caller(unsigned long ip
)
2608 struct task_struct
*curr
= current
;
2610 time_hardirqs_off(CALLER_ADDR0
, ip
);
2612 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2616 * So we're supposed to get called after you mask local IRQs, but for
2617 * some reason the hardware doesn't quite think you did a proper job.
2619 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2622 if (curr
->hardirqs_enabled
) {
2624 * We have done an ON -> OFF transition:
2626 curr
->hardirqs_enabled
= 0;
2627 curr
->hardirq_disable_ip
= ip
;
2628 curr
->hardirq_disable_event
= ++curr
->irq_events
;
2629 debug_atomic_inc(hardirqs_off_events
);
2631 debug_atomic_inc(redundant_hardirqs_off
);
2633 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
2635 void trace_hardirqs_off(void)
2637 trace_hardirqs_off_caller(CALLER_ADDR0
);
2639 EXPORT_SYMBOL(trace_hardirqs_off
);
2642 * Softirqs will be enabled:
2644 void trace_softirqs_on(unsigned long ip
)
2646 struct task_struct
*curr
= current
;
2648 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2652 * We fancy IRQs being disabled here, see softirq.c, avoids
2653 * funny state and nesting things.
2655 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2658 if (curr
->softirqs_enabled
) {
2659 debug_atomic_inc(redundant_softirqs_on
);
2663 current
->lockdep_recursion
= 1;
2665 * We'll do an OFF -> ON transition:
2667 curr
->softirqs_enabled
= 1;
2668 curr
->softirq_enable_ip
= ip
;
2669 curr
->softirq_enable_event
= ++curr
->irq_events
;
2670 debug_atomic_inc(softirqs_on_events
);
2672 * We are going to turn softirqs on, so set the
2673 * usage bit for all held locks, if hardirqs are
2676 if (curr
->hardirqs_enabled
)
2677 mark_held_locks(curr
, SOFTIRQ
);
2678 current
->lockdep_recursion
= 0;
2682 * Softirqs were disabled:
2684 void trace_softirqs_off(unsigned long ip
)
2686 struct task_struct
*curr
= current
;
2688 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
2692 * We fancy IRQs being disabled here, see softirq.c
2694 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2697 if (curr
->softirqs_enabled
) {
2699 * We have done an ON -> OFF transition:
2701 curr
->softirqs_enabled
= 0;
2702 curr
->softirq_disable_ip
= ip
;
2703 curr
->softirq_disable_event
= ++curr
->irq_events
;
2704 debug_atomic_inc(softirqs_off_events
);
2706 * Whoops, we wanted softirqs off, so why aren't they?
2708 DEBUG_LOCKS_WARN_ON(!softirq_count());
2710 debug_atomic_inc(redundant_softirqs_off
);
2713 static void __lockdep_trace_alloc(gfp_t gfp_mask
, unsigned long flags
)
2715 struct task_struct
*curr
= current
;
2717 if (unlikely(!debug_locks
))
2720 /* no reclaim without waiting on it */
2721 if (!(gfp_mask
& __GFP_WAIT
))
2724 /* this guy won't enter reclaim */
2725 if ((curr
->flags
& PF_MEMALLOC
) && !(gfp_mask
& __GFP_NOMEMALLOC
))
2728 /* We're only interested __GFP_FS allocations for now */
2729 if (!(gfp_mask
& __GFP_FS
))
2733 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2735 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags
)))
2738 mark_held_locks(curr
, RECLAIM_FS
);
2741 static void check_flags(unsigned long flags
);
2743 void lockdep_trace_alloc(gfp_t gfp_mask
)
2745 unsigned long flags
;
2747 if (unlikely(current
->lockdep_recursion
))
2750 raw_local_irq_save(flags
);
2752 current
->lockdep_recursion
= 1;
2753 __lockdep_trace_alloc(gfp_mask
, flags
);
2754 current
->lockdep_recursion
= 0;
2755 raw_local_irq_restore(flags
);
2758 static int mark_irqflags(struct task_struct
*curr
, struct held_lock
*hlock
)
2761 * If non-trylock use in a hardirq or softirq context, then
2762 * mark the lock as used in these contexts:
2764 if (!hlock
->trylock
) {
2766 if (curr
->hardirq_context
)
2767 if (!mark_lock(curr
, hlock
,
2768 LOCK_USED_IN_HARDIRQ_READ
))
2770 if (curr
->softirq_context
)
2771 if (!mark_lock(curr
, hlock
,
2772 LOCK_USED_IN_SOFTIRQ_READ
))
2775 if (curr
->hardirq_context
)
2776 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
))
2778 if (curr
->softirq_context
)
2779 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
))
2783 if (!hlock
->hardirqs_off
) {
2785 if (!mark_lock(curr
, hlock
,
2786 LOCK_ENABLED_HARDIRQ_READ
))
2788 if (curr
->softirqs_enabled
)
2789 if (!mark_lock(curr
, hlock
,
2790 LOCK_ENABLED_SOFTIRQ_READ
))
2793 if (!mark_lock(curr
, hlock
,
2794 LOCK_ENABLED_HARDIRQ
))
2796 if (curr
->softirqs_enabled
)
2797 if (!mark_lock(curr
, hlock
,
2798 LOCK_ENABLED_SOFTIRQ
))
2804 * We reuse the irq context infrastructure more broadly as a general
2805 * context checking code. This tests GFP_FS recursion (a lock taken
2806 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2809 if (!hlock
->trylock
&& (curr
->lockdep_reclaim_gfp
& __GFP_FS
)) {
2811 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS_READ
))
2814 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_RECLAIM_FS
))
2822 static int separate_irq_context(struct task_struct
*curr
,
2823 struct held_lock
*hlock
)
2825 unsigned int depth
= curr
->lockdep_depth
;
2828 * Keep track of points where we cross into an interrupt context:
2830 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2831 curr
->softirq_context
;
2833 struct held_lock
*prev_hlock
;
2835 prev_hlock
= curr
->held_locks
+ depth
-1;
2837 * If we cross into another context, reset the
2838 * hash key (this also prevents the checking and the
2839 * adding of the dependency to 'prev'):
2841 if (prev_hlock
->irq_context
!= hlock
->irq_context
)
2847 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2850 int mark_lock_irq(struct task_struct
*curr
, struct held_lock
*this,
2851 enum lock_usage_bit new_bit
)
2853 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2857 static inline int mark_irqflags(struct task_struct
*curr
,
2858 struct held_lock
*hlock
)
2863 static inline int separate_irq_context(struct task_struct
*curr
,
2864 struct held_lock
*hlock
)
2869 void lockdep_trace_alloc(gfp_t gfp_mask
)
2873 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2876 * Mark a lock with a usage bit, and validate the state transition:
2878 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
2879 enum lock_usage_bit new_bit
)
2881 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
2884 * If already set then do not dirty the cacheline,
2885 * nor do any checks:
2887 if (likely(hlock_class(this)->usage_mask
& new_mask
))
2893 * Make sure we didn't race:
2895 if (unlikely(hlock_class(this)->usage_mask
& new_mask
)) {
2900 hlock_class(this)->usage_mask
|= new_mask
;
2902 if (!save_trace(hlock_class(this)->usage_traces
+ new_bit
))
2906 #define LOCKDEP_STATE(__STATE) \
2907 case LOCK_USED_IN_##__STATE: \
2908 case LOCK_USED_IN_##__STATE##_READ: \
2909 case LOCK_ENABLED_##__STATE: \
2910 case LOCK_ENABLED_##__STATE##_READ:
2911 #include "lockdep_states.h"
2912 #undef LOCKDEP_STATE
2913 ret
= mark_lock_irq(curr
, this, new_bit
);
2918 debug_atomic_dec(nr_unused_locks
);
2921 if (!debug_locks_off_graph_unlock())
2930 * We must printk outside of the graph_lock:
2933 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
2935 print_irqtrace_events(curr
);
2943 * Initialize a lock instance's lock-class mapping info:
2945 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
2946 struct lock_class_key
*key
, int subclass
)
2950 kmemcheck_mark_initialized(lock
, sizeof(*lock
));
2952 for (i
= 0; i
< NR_LOCKDEP_CACHING_CLASSES
; i
++)
2953 lock
->class_cache
[i
] = NULL
;
2955 #ifdef CONFIG_LOCK_STAT
2956 lock
->cpu
= raw_smp_processor_id();
2960 * Can't be having no nameless bastards around this place!
2962 if (DEBUG_LOCKS_WARN_ON(!name
)) {
2963 lock
->name
= "NULL";
2970 * No key, no joy, we need to hash something.
2972 if (DEBUG_LOCKS_WARN_ON(!key
))
2975 * Sanity check, the lock-class key must be persistent:
2977 if (!static_obj(key
)) {
2978 printk("BUG: key %p not in .data!\n", key
);
2980 * What it says above ^^^^^, I suggest you read it.
2982 DEBUG_LOCKS_WARN_ON(1);
2987 if (unlikely(!debug_locks
))
2991 register_lock_class(lock
, subclass
, 1);
2993 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2995 struct lock_class_key __lockdep_no_validate__
;
2998 * This gets called for every mutex_lock*()/spin_lock*() operation.
2999 * We maintain the dependency maps and validate the locking attempt:
3001 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3002 int trylock
, int read
, int check
, int hardirqs_off
,
3003 struct lockdep_map
*nest_lock
, unsigned long ip
,
3006 struct task_struct
*curr
= current
;
3007 struct lock_class
*class = NULL
;
3008 struct held_lock
*hlock
;
3009 unsigned int depth
, id
;
3017 if (unlikely(!debug_locks
))
3021 * Lockdep should run with IRQs disabled, otherwise we could
3022 * get an interrupt which would want to take locks, which would
3023 * end up in lockdep and have you got a head-ache already?
3025 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3028 if (lock
->key
== &__lockdep_no_validate__
)
3031 if (subclass
< NR_LOCKDEP_CACHING_CLASSES
)
3032 class = lock
->class_cache
[subclass
];
3036 if (unlikely(!class)) {
3037 class = register_lock_class(lock
, subclass
, 0);
3041 atomic_inc((atomic_t
*)&class->ops
);
3042 if (very_verbose(class)) {
3043 printk("\nacquire class [%p] %s", class->key
, class->name
);
3044 if (class->name_version
> 1)
3045 printk("#%d", class->name_version
);
3051 * Add the lock to the list of currently held locks.
3052 * (we dont increase the depth just yet, up until the
3053 * dependency checks are done)
3055 depth
= curr
->lockdep_depth
;
3057 * Ran out of static storage for our per-task lock stack again have we?
3059 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
3062 class_idx
= class - lock_classes
+ 1;
3065 hlock
= curr
->held_locks
+ depth
- 1;
3066 if (hlock
->class_idx
== class_idx
&& nest_lock
) {
3067 if (hlock
->references
)
3068 hlock
->references
++;
3070 hlock
->references
= 2;
3076 hlock
= curr
->held_locks
+ depth
;
3078 * Plain impossible, we just registered it and checked it weren't no
3079 * NULL like.. I bet this mushroom I ate was good!
3081 if (DEBUG_LOCKS_WARN_ON(!class))
3083 hlock
->class_idx
= class_idx
;
3084 hlock
->acquire_ip
= ip
;
3085 hlock
->instance
= lock
;
3086 hlock
->nest_lock
= nest_lock
;
3087 hlock
->trylock
= trylock
;
3089 hlock
->check
= check
;
3090 hlock
->hardirqs_off
= !!hardirqs_off
;
3091 hlock
->references
= references
;
3092 #ifdef CONFIG_LOCK_STAT
3093 hlock
->waittime_stamp
= 0;
3094 hlock
->holdtime_stamp
= lockstat_clock();
3097 if (check
== 2 && !mark_irqflags(curr
, hlock
))
3100 /* mark it as used: */
3101 if (!mark_lock(curr
, hlock
, LOCK_USED
))
3105 * Calculate the chain hash: it's the combined hash of all the
3106 * lock keys along the dependency chain. We save the hash value
3107 * at every step so that we can get the current hash easily
3108 * after unlock. The chain hash is then used to cache dependency
3111 * The 'key ID' is what is the most compact key value to drive
3112 * the hash, not class->key.
3114 id
= class - lock_classes
;
3116 * Whoops, we did it again.. ran straight out of our static allocation.
3118 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
3121 chain_key
= curr
->curr_chain_key
;
3124 * How can we have a chain hash when we ain't got no keys?!
3126 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
3131 hlock
->prev_chain_key
= chain_key
;
3132 if (separate_irq_context(curr
, hlock
)) {
3136 chain_key
= iterate_chain_key(chain_key
, id
);
3138 if (!validate_chain(curr
, lock
, hlock
, chain_head
, chain_key
))
3141 curr
->curr_chain_key
= chain_key
;
3142 curr
->lockdep_depth
++;
3143 check_chain_key(curr
);
3144 #ifdef CONFIG_DEBUG_LOCKDEP
3145 if (unlikely(!debug_locks
))
3148 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
3150 printk("BUG: MAX_LOCK_DEPTH too low!\n");
3151 printk("turning off the locking correctness validator.\n");
3156 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
3157 max_lockdep_depth
= curr
->lockdep_depth
;
3163 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3166 if (!debug_locks_off())
3168 if (debug_locks_silent
)
3172 printk("=====================================\n");
3173 printk("[ BUG: bad unlock balance detected! ]\n");
3174 printk("-------------------------------------\n");
3175 printk("%s/%d is trying to release lock (",
3176 curr
->comm
, task_pid_nr(curr
));
3177 print_lockdep_cache(lock
);
3180 printk("but there are no more locks to release!\n");
3181 printk("\nother info that might help us debug this:\n");
3182 lockdep_print_held_locks(curr
);
3184 printk("\nstack backtrace:\n");
3191 * Common debugging checks for both nested and non-nested unlock:
3193 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
3196 if (unlikely(!debug_locks
))
3199 * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
3201 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3204 if (curr
->lockdep_depth
<= 0)
3205 return print_unlock_inbalance_bug(curr
, lock
, ip
);
3210 static int match_held_lock(struct held_lock
*hlock
, struct lockdep_map
*lock
)
3212 if (hlock
->instance
== lock
)
3215 if (hlock
->references
) {
3216 struct lock_class
*class = lock
->class_cache
[0];
3219 class = look_up_lock_class(lock
, 0);
3222 * If look_up_lock_class() failed to find a class, we're trying
3223 * to test if we hold a lock that has never yet been acquired.
3224 * Clearly if the lock hasn't been acquired _ever_, we're not
3225 * holding it either, so report failure.
3231 * References, but not a lock we're actually ref-counting?
3232 * State got messed up, follow the sites that change ->references
3233 * and try to make sense of it.
3235 if (DEBUG_LOCKS_WARN_ON(!hlock
->nest_lock
))
3238 if (hlock
->class_idx
== class - lock_classes
+ 1)
3246 __lock_set_class(struct lockdep_map
*lock
, const char *name
,
3247 struct lock_class_key
*key
, unsigned int subclass
,
3250 struct task_struct
*curr
= current
;
3251 struct held_lock
*hlock
, *prev_hlock
;
3252 struct lock_class
*class;
3256 depth
= curr
->lockdep_depth
;
3258 * This function is about (re)setting the class of a held lock,
3259 * yet we're not actually holding any locks. Naughty user!
3261 if (DEBUG_LOCKS_WARN_ON(!depth
))
3265 for (i
= depth
-1; i
>= 0; i
--) {
3266 hlock
= curr
->held_locks
+ i
;
3268 * We must not cross into another context:
3270 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3272 if (match_held_lock(hlock
, lock
))
3276 return print_unlock_inbalance_bug(curr
, lock
, ip
);
3279 lockdep_init_map(lock
, name
, key
, 0);
3280 class = register_lock_class(lock
, subclass
, 0);
3281 hlock
->class_idx
= class - lock_classes
+ 1;
3283 curr
->lockdep_depth
= i
;
3284 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3286 for (; i
< depth
; i
++) {
3287 hlock
= curr
->held_locks
+ i
;
3288 if (!__lock_acquire(hlock
->instance
,
3289 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3290 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3291 hlock
->nest_lock
, hlock
->acquire_ip
,
3297 * I took it apart and put it back together again, except now I have
3298 * these 'spare' parts.. where shall I put them.
3300 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
))
3306 * Remove the lock to the list of currently held locks in a
3307 * potentially non-nested (out of order) manner. This is a
3308 * relatively rare operation, as all the unlock APIs default
3309 * to nested mode (which uses lock_release()):
3312 lock_release_non_nested(struct task_struct
*curr
,
3313 struct lockdep_map
*lock
, unsigned long ip
)
3315 struct held_lock
*hlock
, *prev_hlock
;
3320 * Check whether the lock exists in the current stack
3323 depth
= curr
->lockdep_depth
;
3325 * So we're all set to release this lock.. wait what lock? We don't
3326 * own any locks, you've been drinking again?
3328 if (DEBUG_LOCKS_WARN_ON(!depth
))
3332 for (i
= depth
-1; i
>= 0; i
--) {
3333 hlock
= curr
->held_locks
+ i
;
3335 * We must not cross into another context:
3337 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3339 if (match_held_lock(hlock
, lock
))
3343 return print_unlock_inbalance_bug(curr
, lock
, ip
);
3346 if (hlock
->instance
== lock
)
3347 lock_release_holdtime(hlock
);
3349 if (hlock
->references
) {
3350 hlock
->references
--;
3351 if (hlock
->references
) {
3353 * We had, and after removing one, still have
3354 * references, the current lock stack is still
3355 * valid. We're done!
3362 * We have the right lock to unlock, 'hlock' points to it.
3363 * Now we remove it from the stack, and add back the other
3364 * entries (if any), recalculating the hash along the way:
3367 curr
->lockdep_depth
= i
;
3368 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3370 for (i
++; i
< depth
; i
++) {
3371 hlock
= curr
->held_locks
+ i
;
3372 if (!__lock_acquire(hlock
->instance
,
3373 hlock_class(hlock
)->subclass
, hlock
->trylock
,
3374 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
3375 hlock
->nest_lock
, hlock
->acquire_ip
,
3381 * We had N bottles of beer on the wall, we drank one, but now
3382 * there's not N-1 bottles of beer left on the wall...
3384 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
3390 * Remove the lock to the list of currently held locks - this gets
3391 * called on mutex_unlock()/spin_unlock*() (or on a failed
3392 * mutex_lock_interruptible()). This is done for unlocks that nest
3393 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3395 static int lock_release_nested(struct task_struct
*curr
,
3396 struct lockdep_map
*lock
, unsigned long ip
)
3398 struct held_lock
*hlock
;
3402 * Pop off the top of the lock stack:
3404 depth
= curr
->lockdep_depth
- 1;
3405 hlock
= curr
->held_locks
+ depth
;
3408 * Is the unlock non-nested:
3410 if (hlock
->instance
!= lock
|| hlock
->references
)
3411 return lock_release_non_nested(curr
, lock
, ip
);
3412 curr
->lockdep_depth
--;
3415 * No more locks, but somehow we've got hash left over, who left it?
3417 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
3420 curr
->curr_chain_key
= hlock
->prev_chain_key
;
3422 lock_release_holdtime(hlock
);
3424 #ifdef CONFIG_DEBUG_LOCKDEP
3425 hlock
->prev_chain_key
= 0;
3426 hlock
->class_idx
= 0;
3427 hlock
->acquire_ip
= 0;
3428 hlock
->irq_context
= 0;
3434 * Remove the lock to the list of currently held locks - this gets
3435 * called on mutex_unlock()/spin_unlock*() (or on a failed
3436 * mutex_lock_interruptible()). This is done for unlocks that nest
3437 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3440 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
3442 struct task_struct
*curr
= current
;
3444 if (!check_unlock(curr
, lock
, ip
))
3448 if (!lock_release_nested(curr
, lock
, ip
))
3451 if (!lock_release_non_nested(curr
, lock
, ip
))
3455 check_chain_key(curr
);
3458 static int __lock_is_held(struct lockdep_map
*lock
)
3460 struct task_struct
*curr
= current
;
3463 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
3464 struct held_lock
*hlock
= curr
->held_locks
+ i
;
3466 if (match_held_lock(hlock
, lock
))
3474 * Check whether we follow the irq-flags state precisely:
3476 static void check_flags(unsigned long flags
)
3478 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3479 defined(CONFIG_TRACE_IRQFLAGS)
3483 if (irqs_disabled_flags(flags
)) {
3484 if (DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
)) {
3485 printk("possible reason: unannotated irqs-off.\n");
3488 if (DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
)) {
3489 printk("possible reason: unannotated irqs-on.\n");
3494 * We dont accurately track softirq state in e.g.
3495 * hardirq contexts (such as on 4KSTACKS), so only
3496 * check if not in hardirq contexts:
3498 if (!hardirq_count()) {
3499 if (softirq_count()) {
3500 /* like the above, but with softirqs */
3501 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
3503 /* lick the above, does it taste good? */
3504 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
3509 print_irqtrace_events(current
);
3513 void lock_set_class(struct lockdep_map
*lock
, const char *name
,
3514 struct lock_class_key
*key
, unsigned int subclass
,
3517 unsigned long flags
;
3519 if (unlikely(current
->lockdep_recursion
))
3522 raw_local_irq_save(flags
);
3523 current
->lockdep_recursion
= 1;
3525 if (__lock_set_class(lock
, name
, key
, subclass
, ip
))
3526 check_chain_key(current
);
3527 current
->lockdep_recursion
= 0;
3528 raw_local_irq_restore(flags
);
3530 EXPORT_SYMBOL_GPL(lock_set_class
);
3533 * We are not always called with irqs disabled - do that here,
3534 * and also avoid lockdep recursion:
3536 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
3537 int trylock
, int read
, int check
,
3538 struct lockdep_map
*nest_lock
, unsigned long ip
)
3540 unsigned long flags
;
3542 if (unlikely(current
->lockdep_recursion
))
3545 raw_local_irq_save(flags
);
3548 current
->lockdep_recursion
= 1;
3549 trace_lock_acquire(lock
, subclass
, trylock
, read
, check
, nest_lock
, ip
);
3550 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
3551 irqs_disabled_flags(flags
), nest_lock
, ip
, 0);
3552 current
->lockdep_recursion
= 0;
3553 raw_local_irq_restore(flags
);
3555 EXPORT_SYMBOL_GPL(lock_acquire
);
3557 void lock_release(struct lockdep_map
*lock
, int nested
,
3560 unsigned long flags
;
3562 if (unlikely(current
->lockdep_recursion
))
3565 raw_local_irq_save(flags
);
3567 current
->lockdep_recursion
= 1;
3568 trace_lock_release(lock
, ip
);
3569 __lock_release(lock
, nested
, ip
);
3570 current
->lockdep_recursion
= 0;
3571 raw_local_irq_restore(flags
);
3573 EXPORT_SYMBOL_GPL(lock_release
);
3575 int lock_is_held(struct lockdep_map
*lock
)
3577 unsigned long flags
;
3580 if (unlikely(current
->lockdep_recursion
))
3581 return 1; /* avoid false negative lockdep_assert_held() */
3583 raw_local_irq_save(flags
);
3586 current
->lockdep_recursion
= 1;
3587 ret
= __lock_is_held(lock
);
3588 current
->lockdep_recursion
= 0;
3589 raw_local_irq_restore(flags
);
3593 EXPORT_SYMBOL_GPL(lock_is_held
);
3595 void lockdep_set_current_reclaim_state(gfp_t gfp_mask
)
3597 current
->lockdep_reclaim_gfp
= gfp_mask
;
3600 void lockdep_clear_current_reclaim_state(void)
3602 current
->lockdep_reclaim_gfp
= 0;
3605 #ifdef CONFIG_LOCK_STAT
3607 print_lock_contention_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
3610 if (!debug_locks_off())
3612 if (debug_locks_silent
)
3616 printk("=================================\n");
3617 printk("[ BUG: bad contention detected! ]\n");
3618 printk("---------------------------------\n");
3619 printk("%s/%d is trying to contend lock (",
3620 curr
->comm
, task_pid_nr(curr
));
3621 print_lockdep_cache(lock
);
3624 printk("but there are no locks held!\n");
3625 printk("\nother info that might help us debug this:\n");
3626 lockdep_print_held_locks(curr
);
3628 printk("\nstack backtrace:\n");
3635 __lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3637 struct task_struct
*curr
= current
;
3638 struct held_lock
*hlock
, *prev_hlock
;
3639 struct lock_class_stats
*stats
;
3641 int i
, contention_point
, contending_point
;
3643 depth
= curr
->lockdep_depth
;
3645 * Whee, we contended on this lock, except it seems we're not
3646 * actually trying to acquire anything much at all..
3648 if (DEBUG_LOCKS_WARN_ON(!depth
))
3652 for (i
= depth
-1; i
>= 0; i
--) {
3653 hlock
= curr
->held_locks
+ i
;
3655 * We must not cross into another context:
3657 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3659 if (match_held_lock(hlock
, lock
))
3663 print_lock_contention_bug(curr
, lock
, ip
);
3667 if (hlock
->instance
!= lock
)
3670 hlock
->waittime_stamp
= lockstat_clock();
3672 contention_point
= lock_point(hlock_class(hlock
)->contention_point
, ip
);
3673 contending_point
= lock_point(hlock_class(hlock
)->contending_point
,
3676 stats
= get_lock_stats(hlock_class(hlock
));
3677 if (contention_point
< LOCKSTAT_POINTS
)
3678 stats
->contention_point
[contention_point
]++;
3679 if (contending_point
< LOCKSTAT_POINTS
)
3680 stats
->contending_point
[contending_point
]++;
3681 if (lock
->cpu
!= smp_processor_id())
3682 stats
->bounces
[bounce_contended
+ !!hlock
->read
]++;
3683 put_lock_stats(stats
);
3687 __lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3689 struct task_struct
*curr
= current
;
3690 struct held_lock
*hlock
, *prev_hlock
;
3691 struct lock_class_stats
*stats
;
3693 u64 now
, waittime
= 0;
3696 depth
= curr
->lockdep_depth
;
3698 * Yay, we acquired ownership of this lock we didn't try to
3699 * acquire, how the heck did that happen?
3701 if (DEBUG_LOCKS_WARN_ON(!depth
))
3705 for (i
= depth
-1; i
>= 0; i
--) {
3706 hlock
= curr
->held_locks
+ i
;
3708 * We must not cross into another context:
3710 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
3712 if (match_held_lock(hlock
, lock
))
3716 print_lock_contention_bug(curr
, lock
, _RET_IP_
);
3720 if (hlock
->instance
!= lock
)
3723 cpu
= smp_processor_id();
3724 if (hlock
->waittime_stamp
) {
3725 now
= lockstat_clock();
3726 waittime
= now
- hlock
->waittime_stamp
;
3727 hlock
->holdtime_stamp
= now
;
3730 trace_lock_acquired(lock
, ip
);
3732 stats
= get_lock_stats(hlock_class(hlock
));
3735 lock_time_inc(&stats
->read_waittime
, waittime
);
3737 lock_time_inc(&stats
->write_waittime
, waittime
);
3739 if (lock
->cpu
!= cpu
)
3740 stats
->bounces
[bounce_acquired
+ !!hlock
->read
]++;
3741 put_lock_stats(stats
);
3747 void lock_contended(struct lockdep_map
*lock
, unsigned long ip
)
3749 unsigned long flags
;
3751 if (unlikely(!lock_stat
))
3754 if (unlikely(current
->lockdep_recursion
))
3757 raw_local_irq_save(flags
);
3759 current
->lockdep_recursion
= 1;
3760 trace_lock_contended(lock
, ip
);
3761 __lock_contended(lock
, ip
);
3762 current
->lockdep_recursion
= 0;
3763 raw_local_irq_restore(flags
);
3765 EXPORT_SYMBOL_GPL(lock_contended
);
3767 void lock_acquired(struct lockdep_map
*lock
, unsigned long ip
)
3769 unsigned long flags
;
3771 if (unlikely(!lock_stat
))
3774 if (unlikely(current
->lockdep_recursion
))
3777 raw_local_irq_save(flags
);
3779 current
->lockdep_recursion
= 1;
3780 __lock_acquired(lock
, ip
);
3781 current
->lockdep_recursion
= 0;
3782 raw_local_irq_restore(flags
);
3784 EXPORT_SYMBOL_GPL(lock_acquired
);
3788 * Used by the testsuite, sanitize the validator state
3789 * after a simulated failure:
3792 void lockdep_reset(void)
3794 unsigned long flags
;
3797 raw_local_irq_save(flags
);
3798 current
->curr_chain_key
= 0;
3799 current
->lockdep_depth
= 0;
3800 current
->lockdep_recursion
= 0;
3801 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
3802 nr_hardirq_chains
= 0;
3803 nr_softirq_chains
= 0;
3804 nr_process_chains
= 0;
3806 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3807 INIT_LIST_HEAD(chainhash_table
+ i
);
3808 raw_local_irq_restore(flags
);
3811 static void zap_class(struct lock_class
*class)
3816 * Remove all dependencies this lock is
3819 for (i
= 0; i
< nr_list_entries
; i
++) {
3820 if (list_entries
[i
].class == class)
3821 list_del_rcu(&list_entries
[i
].entry
);
3824 * Unhash the class and remove it from the all_lock_classes list:
3826 list_del_rcu(&class->hash_entry
);
3827 list_del_rcu(&class->lock_entry
);
3832 static inline int within(const void *addr
, void *start
, unsigned long size
)
3834 return addr
>= start
&& addr
< start
+ size
;
3837 void lockdep_free_key_range(void *start
, unsigned long size
)
3839 struct lock_class
*class, *next
;
3840 struct list_head
*head
;
3841 unsigned long flags
;
3845 raw_local_irq_save(flags
);
3846 locked
= graph_lock();
3849 * Unhash all classes that were created by this module:
3851 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3852 head
= classhash_table
+ i
;
3853 if (list_empty(head
))
3855 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3856 if (within(class->key
, start
, size
))
3858 else if (within(class->name
, start
, size
))
3865 raw_local_irq_restore(flags
);
3868 void lockdep_reset_lock(struct lockdep_map
*lock
)
3870 struct lock_class
*class, *next
;
3871 struct list_head
*head
;
3872 unsigned long flags
;
3876 raw_local_irq_save(flags
);
3879 * Remove all classes this lock might have:
3881 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
3883 * If the class exists we look it up and zap it:
3885 class = look_up_lock_class(lock
, j
);
3890 * Debug check: in the end all mapped classes should
3893 locked
= graph_lock();
3894 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
3895 head
= classhash_table
+ i
;
3896 if (list_empty(head
))
3898 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
3901 for (j
= 0; j
< NR_LOCKDEP_CACHING_CLASSES
; j
++)
3902 match
|= class == lock
->class_cache
[j
];
3904 if (unlikely(match
)) {
3905 if (debug_locks_off_graph_unlock()) {
3907 * We all just reset everything, how did it match?
3919 raw_local_irq_restore(flags
);
3922 void lockdep_init(void)
3927 * Some architectures have their own start_kernel()
3928 * code which calls lockdep_init(), while we also
3929 * call lockdep_init() from the start_kernel() itself,
3930 * and we want to initialize the hashes only once:
3932 if (lockdep_initialized
)
3935 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
3936 INIT_LIST_HEAD(classhash_table
+ i
);
3938 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
3939 INIT_LIST_HEAD(chainhash_table
+ i
);
3941 lockdep_initialized
= 1;
3944 void __init
lockdep_info(void)
3946 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3948 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
3949 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
3950 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
3951 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
3952 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
3953 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
3954 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
3956 printk(" memory used by lock dependency info: %lu kB\n",
3957 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
3958 sizeof(struct list_head
) * CLASSHASH_SIZE
+
3959 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
3960 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
3961 sizeof(struct list_head
) * CHAINHASH_SIZE
3962 #ifdef CONFIG_PROVE_LOCKING
3963 + sizeof(struct circular_queue
)
3968 printk(" per task-struct memory footprint: %lu bytes\n",
3969 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
3971 #ifdef CONFIG_DEBUG_LOCKDEP
3972 if (lockdep_init_error
) {
3973 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3974 printk("Call stack leading to lockdep invocation was:\n");
3975 print_stack_trace(&lockdep_init_trace
, 0);
3981 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
3982 const void *mem_to
, struct held_lock
*hlock
)
3984 if (!debug_locks_off())
3986 if (debug_locks_silent
)
3990 printk("=========================\n");
3991 printk("[ BUG: held lock freed! ]\n");
3992 printk("-------------------------\n");
3993 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3994 curr
->comm
, task_pid_nr(curr
), mem_from
, mem_to
-1);
3996 lockdep_print_held_locks(curr
);
3998 printk("\nstack backtrace:\n");
4002 static inline int not_in_range(const void* mem_from
, unsigned long mem_len
,
4003 const void* lock_from
, unsigned long lock_len
)
4005 return lock_from
+ lock_len
<= mem_from
||
4006 mem_from
+ mem_len
<= lock_from
;
4010 * Called when kernel memory is freed (or unmapped), or if a lock
4011 * is destroyed or reinitialized - this code checks whether there is
4012 * any held lock in the memory range of <from> to <to>:
4014 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
4016 struct task_struct
*curr
= current
;
4017 struct held_lock
*hlock
;
4018 unsigned long flags
;
4021 if (unlikely(!debug_locks
))
4024 local_irq_save(flags
);
4025 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
4026 hlock
= curr
->held_locks
+ i
;
4028 if (not_in_range(mem_from
, mem_len
, hlock
->instance
,
4029 sizeof(*hlock
->instance
)))
4032 print_freed_lock_bug(curr
, mem_from
, mem_from
+ mem_len
, hlock
);
4035 local_irq_restore(flags
);
4037 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
4039 static void print_held_locks_bug(struct task_struct
*curr
)
4041 if (!debug_locks_off())
4043 if (debug_locks_silent
)
4047 printk("=====================================\n");
4048 printk("[ BUG: lock held at task exit time! ]\n");
4049 printk("-------------------------------------\n");
4050 printk("%s/%d is exiting with locks still held!\n",
4051 curr
->comm
, task_pid_nr(curr
));
4052 lockdep_print_held_locks(curr
);
4054 printk("\nstack backtrace:\n");
4058 void debug_check_no_locks_held(struct task_struct
*task
)
4060 if (unlikely(task
->lockdep_depth
> 0))
4061 print_held_locks_bug(task
);
4064 void debug_show_all_locks(void)
4066 struct task_struct
*g
, *p
;
4070 if (unlikely(!debug_locks
)) {
4071 printk("INFO: lockdep is turned off.\n");
4074 printk("\nShowing all locks held in the system:\n");
4077 * Here we try to get the tasklist_lock as hard as possible,
4078 * if not successful after 2 seconds we ignore it (but keep
4079 * trying). This is to enable a debug printout even if a
4080 * tasklist_lock-holding task deadlocks or crashes.
4083 if (!read_trylock(&tasklist_lock
)) {
4085 printk("hm, tasklist_lock locked, retrying... ");
4088 printk(" #%d", 10-count
);
4092 printk(" ignoring it.\n");
4096 printk(KERN_CONT
" locked it.\n");
4099 do_each_thread(g
, p
) {
4101 * It's not reliable to print a task's held locks
4102 * if it's not sleeping (or if it's not the current
4105 if (p
->state
== TASK_RUNNING
&& p
!= current
)
4107 if (p
->lockdep_depth
)
4108 lockdep_print_held_locks(p
);
4110 if (read_trylock(&tasklist_lock
))
4112 } while_each_thread(g
, p
);
4115 printk("=============================================\n\n");
4118 read_unlock(&tasklist_lock
);
4120 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
4123 * Careful: only use this function if you are sure that
4124 * the task cannot run in parallel!
4126 void debug_show_held_locks(struct task_struct
*task
)
4128 if (unlikely(!debug_locks
)) {
4129 printk("INFO: lockdep is turned off.\n");
4132 lockdep_print_held_locks(task
);
4134 EXPORT_SYMBOL_GPL(debug_show_held_locks
);
4136 void lockdep_sys_exit(void)
4138 struct task_struct
*curr
= current
;
4140 if (unlikely(curr
->lockdep_depth
)) {
4141 if (!debug_locks_off())
4144 printk("================================================\n");
4145 printk("[ BUG: lock held when returning to user space! ]\n");
4146 printk("------------------------------------------------\n");
4147 printk("%s/%d is leaving the kernel with locks still held!\n",
4148 curr
->comm
, curr
->pid
);
4149 lockdep_print_held_locks(curr
);
4153 void lockdep_rcu_suspicious(const char *file
, const int line
, const char *s
)
4155 struct task_struct
*curr
= current
;
4157 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4158 if (!debug_locks_off())
4160 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4161 /* Note: the following can be executed concurrently, so be careful. */
4163 printk("===============================\n");
4164 printk("[ INFO: suspicious RCU usage. ]\n");
4165 printk("-------------------------------\n");
4166 printk("%s:%d %s!\n", file
, line
, s
);
4167 printk("\nother info that might help us debug this:\n\n");
4168 printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active
, debug_locks
);
4169 lockdep_print_held_locks(curr
);
4170 printk("\nstack backtrace:\n");
4173 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious
);