4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
10 * this code maps all the lock dependencies as they occur in a live kernel
11 * and will warn about the following classes of locking bugs:
13 * - lock inversion scenarios
14 * - circular lock dependencies
15 * - hardirq/softirq safe/unsafe locking bugs
17 * Bugs are reported even if the current locking scenario does not cause
18 * any deadlock at this point.
20 * I.e. if anytime in the past two locks were taken in a different order,
21 * even if it happened for another task, even if those were different
22 * locks (but of the same class as this lock), this code will detect it.
24 * Thanks to Arjan van de Ven for coming up with the initial idea of
25 * mapping lock dependencies runtime.
27 #include <linux/mutex.h>
28 #include <linux/sched.h>
29 #include <linux/delay.h>
30 #include <linux/module.h>
31 #include <linux/proc_fs.h>
32 #include <linux/seq_file.h>
33 #include <linux/spinlock.h>
34 #include <linux/kallsyms.h>
35 #include <linux/interrupt.h>
36 #include <linux/stacktrace.h>
37 #include <linux/debug_locks.h>
38 #include <linux/irqflags.h>
39 #include <linux/utsname.h>
41 #include <asm/sections.h>
43 #include "lockdep_internals.h"
46 * hash_lock: protects the lockdep hashes and class/list/hash allocators.
48 * This is one of the rare exceptions where it's justified
49 * to use a raw spinlock - we really dont want the spinlock
50 * code to recurse back into the lockdep code.
52 static raw_spinlock_t hash_lock
= (raw_spinlock_t
)__RAW_SPIN_LOCK_UNLOCKED
;
54 static int lockdep_initialized
;
56 unsigned long nr_list_entries
;
57 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
60 * Allocate a lockdep entry. (assumes hash_lock held, returns
61 * with NULL on failure)
63 static struct lock_list
*alloc_list_entry(void)
65 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
66 __raw_spin_unlock(&hash_lock
);
68 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
69 printk("turning off the locking correctness validator.\n");
72 return list_entries
+ nr_list_entries
++;
76 * All data structures here are protected by the global debug_lock.
78 * Mutex key structs only get allocated, once during bootup, and never
79 * get freed - this significantly simplifies the debugging code.
81 unsigned long nr_lock_classes
;
82 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
85 * We keep a global list of all lock classes. The list only grows,
86 * never shrinks. The list is only accessed with the lockdep
89 LIST_HEAD(all_lock_classes
);
92 * The lockdep classes are in a hash-table as well, for fast lookup:
94 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
95 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
96 #define CLASSHASH_MASK (CLASSHASH_SIZE - 1)
97 #define __classhashfn(key) ((((unsigned long)key >> CLASSHASH_BITS) + (unsigned long)key) & CLASSHASH_MASK)
98 #define classhashentry(key) (classhash_table + __classhashfn((key)))
100 static struct list_head classhash_table
[CLASSHASH_SIZE
];
102 unsigned long nr_lock_chains
;
103 static struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
106 * We put the lock dependency chains into a hash-table as well, to cache
109 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
110 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
111 #define CHAINHASH_MASK (CHAINHASH_SIZE - 1)
112 #define __chainhashfn(chain) \
113 (((chain >> CHAINHASH_BITS) + chain) & CHAINHASH_MASK)
114 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
116 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
119 * The hash key of the lock dependency chains is a hash itself too:
120 * it's a hash of all locks taken up to that lock, including that lock.
121 * It's a 64-bit hash, because it's important for the keys to be
124 #define iterate_chain_key(key1, key2) \
125 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
126 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
129 void lockdep_off(void)
131 current
->lockdep_recursion
++;
134 EXPORT_SYMBOL(lockdep_off
);
136 void lockdep_on(void)
138 current
->lockdep_recursion
--;
141 EXPORT_SYMBOL(lockdep_on
);
144 * Debugging switches:
148 #define VERY_VERBOSE 0
151 # define HARDIRQ_VERBOSE 1
152 # define SOFTIRQ_VERBOSE 1
154 # define HARDIRQ_VERBOSE 0
155 # define SOFTIRQ_VERBOSE 0
158 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
160 * Quick filtering for interesting events:
162 static int class_filter(struct lock_class
*class)
166 if (class->name_version
== 1 &&
167 !strcmp(class->name
, "lockname"))
169 if (class->name_version
== 1 &&
170 !strcmp(class->name
, "&struct->lockfield"))
173 /* Filter everything else. 1 would be to allow everything else */
178 static int verbose(struct lock_class
*class)
181 return class_filter(class);
186 #ifdef CONFIG_TRACE_IRQFLAGS
188 static int hardirq_verbose(struct lock_class
*class)
191 return class_filter(class);
196 static int softirq_verbose(struct lock_class
*class)
199 return class_filter(class);
207 * Stack-trace: tightly packed array of stack backtrace
208 * addresses. Protected by the hash_lock.
210 unsigned long nr_stack_trace_entries
;
211 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
213 static int save_trace(struct stack_trace
*trace
)
215 trace
->nr_entries
= 0;
216 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
217 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
220 trace
->all_contexts
= 0;
222 save_stack_trace(trace
, NULL
);
224 trace
->max_entries
= trace
->nr_entries
;
226 nr_stack_trace_entries
+= trace
->nr_entries
;
227 if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries
> MAX_STACK_TRACE_ENTRIES
)) {
228 __raw_spin_unlock(&hash_lock
);
232 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
233 __raw_spin_unlock(&hash_lock
);
234 if (debug_locks_off()) {
235 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
236 printk("turning off the locking correctness validator.\n");
245 unsigned int nr_hardirq_chains
;
246 unsigned int nr_softirq_chains
;
247 unsigned int nr_process_chains
;
248 unsigned int max_lockdep_depth
;
249 unsigned int max_recursion_depth
;
251 #ifdef CONFIG_DEBUG_LOCKDEP
253 * We cannot printk in early bootup code. Not even early_printk()
254 * might work. So we mark any initialization errors and printk
255 * about it later on, in lockdep_info().
257 static int lockdep_init_error
;
260 * Various lockdep statistics:
262 atomic_t chain_lookup_hits
;
263 atomic_t chain_lookup_misses
;
264 atomic_t hardirqs_on_events
;
265 atomic_t hardirqs_off_events
;
266 atomic_t redundant_hardirqs_on
;
267 atomic_t redundant_hardirqs_off
;
268 atomic_t softirqs_on_events
;
269 atomic_t softirqs_off_events
;
270 atomic_t redundant_softirqs_on
;
271 atomic_t redundant_softirqs_off
;
272 atomic_t nr_unused_locks
;
273 atomic_t nr_cyclic_checks
;
274 atomic_t nr_cyclic_check_recursions
;
275 atomic_t nr_find_usage_forwards_checks
;
276 atomic_t nr_find_usage_forwards_recursions
;
277 atomic_t nr_find_usage_backwards_checks
;
278 atomic_t nr_find_usage_backwards_recursions
;
279 # define debug_atomic_inc(ptr) atomic_inc(ptr)
280 # define debug_atomic_dec(ptr) atomic_dec(ptr)
281 # define debug_atomic_read(ptr) atomic_read(ptr)
283 # define debug_atomic_inc(ptr) do { } while (0)
284 # define debug_atomic_dec(ptr) do { } while (0)
285 # define debug_atomic_read(ptr) 0
292 static const char *usage_str
[] =
294 [LOCK_USED
] = "initial-use ",
295 [LOCK_USED_IN_HARDIRQ
] = "in-hardirq-W",
296 [LOCK_USED_IN_SOFTIRQ
] = "in-softirq-W",
297 [LOCK_ENABLED_SOFTIRQS
] = "softirq-on-W",
298 [LOCK_ENABLED_HARDIRQS
] = "hardirq-on-W",
299 [LOCK_USED_IN_HARDIRQ_READ
] = "in-hardirq-R",
300 [LOCK_USED_IN_SOFTIRQ_READ
] = "in-softirq-R",
301 [LOCK_ENABLED_SOFTIRQS_READ
] = "softirq-on-R",
302 [LOCK_ENABLED_HARDIRQS_READ
] = "hardirq-on-R",
305 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
307 unsigned long offs
, size
;
310 return kallsyms_lookup((unsigned long)key
, &size
, &offs
, &modname
, str
);
314 get_usage_chars(struct lock_class
*class, char *c1
, char *c2
, char *c3
, char *c4
)
316 *c1
= '.', *c2
= '.', *c3
= '.', *c4
= '.';
318 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ
)
321 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS
)
324 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ
)
327 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS
)
330 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
332 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ_READ
) {
334 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
338 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
340 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ_READ
) {
342 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
347 static void print_lock_name(struct lock_class
*class)
349 char str
[KSYM_NAME_LEN
+ 1], c1
, c2
, c3
, c4
;
352 get_usage_chars(class, &c1
, &c2
, &c3
, &c4
);
356 name
= __get_key_name(class->key
, str
);
357 printk(" (%s", name
);
359 printk(" (%s", name
);
360 if (class->name_version
> 1)
361 printk("#%d", class->name_version
);
363 printk("/%d", class->subclass
);
365 printk("){%c%c%c%c}", c1
, c2
, c3
, c4
);
368 static void print_lockdep_cache(struct lockdep_map
*lock
)
371 char str
[KSYM_NAME_LEN
+ 1];
375 name
= __get_key_name(lock
->key
->subkeys
, str
);
380 static void print_lock(struct held_lock
*hlock
)
382 print_lock_name(hlock
->class);
384 print_ip_sym(hlock
->acquire_ip
);
387 static void lockdep_print_held_locks(struct task_struct
*curr
)
389 int i
, depth
= curr
->lockdep_depth
;
392 printk("no locks held by %s/%d.\n", curr
->comm
, curr
->pid
);
395 printk("%d lock%s held by %s/%d:\n",
396 depth
, depth
> 1 ? "s" : "", curr
->comm
, curr
->pid
);
398 for (i
= 0; i
< depth
; i
++) {
400 print_lock(curr
->held_locks
+ i
);
404 static void print_lock_class_header(struct lock_class
*class, int depth
)
408 printk("%*s->", depth
, "");
409 print_lock_name(class);
410 printk(" ops: %lu", class->ops
);
413 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
414 if (class->usage_mask
& (1 << bit
)) {
417 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
418 len
+= printk(" at:\n");
419 print_stack_trace(class->usage_traces
+ bit
, len
);
422 printk("%*s }\n", depth
, "");
424 printk("%*s ... key at: ",depth
,"");
425 print_ip_sym((unsigned long)class->key
);
429 * printk all lock dependencies starting at <entry>:
431 static void print_lock_dependencies(struct lock_class
*class, int depth
)
433 struct lock_list
*entry
;
435 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
438 print_lock_class_header(class, depth
);
440 list_for_each_entry(entry
, &class->locks_after
, entry
) {
441 if (DEBUG_LOCKS_WARN_ON(!entry
->class))
444 print_lock_dependencies(entry
->class, depth
+ 1);
446 printk("%*s ... acquired at:\n",depth
,"");
447 print_stack_trace(&entry
->trace
, 2);
453 * Add a new dependency to the head of the list:
455 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
456 struct list_head
*head
, unsigned long ip
)
458 struct lock_list
*entry
;
460 * Lock not present yet - get a new dependency struct and
461 * add it to the list:
463 entry
= alloc_list_entry();
468 if (!save_trace(&entry
->trace
))
472 * Since we never remove from the dependency list, the list can
473 * be walked lockless by other CPUs, it's only allocation
474 * that must be protected by the spinlock. But this also means
475 * we must make new entries visible only once writes to the
476 * entry become visible - hence the RCU op:
478 list_add_tail_rcu(&entry
->entry
, head
);
484 * Recursive, forwards-direction lock-dependency checking, used for
485 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
488 * (to keep the stackframe of the recursive functions small we
489 * use these global variables, and we also mark various helper
490 * functions as noinline.)
492 static struct held_lock
*check_source
, *check_target
;
495 * Print a dependency chain entry (this is only done when a deadlock
496 * has been detected):
499 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
501 if (debug_locks_silent
)
503 printk("\n-> #%u", depth
);
504 print_lock_name(target
->class);
506 print_stack_trace(&target
->trace
, 6);
511 static void print_kernel_version(void)
513 printk("%s %.*s\n", init_utsname()->release
,
514 (int)strcspn(init_utsname()->version
, " "),
515 init_utsname()->version
);
519 * When a circular dependency is detected, print the
523 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
)
525 struct task_struct
*curr
= current
;
527 __raw_spin_unlock(&hash_lock
);
529 if (debug_locks_silent
)
532 printk("\n=======================================================\n");
533 printk( "[ INFO: possible circular locking dependency detected ]\n");
534 print_kernel_version();
535 printk( "-------------------------------------------------------\n");
536 printk("%s/%d is trying to acquire lock:\n",
537 curr
->comm
, curr
->pid
);
538 print_lock(check_source
);
539 printk("\nbut task is already holding lock:\n");
540 print_lock(check_target
);
541 printk("\nwhich lock already depends on the new lock.\n\n");
542 printk("\nthe existing dependency chain (in reverse order) is:\n");
544 print_circular_bug_entry(entry
, depth
);
549 static noinline
int print_circular_bug_tail(void)
551 struct task_struct
*curr
= current
;
552 struct lock_list
this;
554 if (debug_locks_silent
)
557 /* hash_lock unlocked by the header */
558 __raw_spin_lock(&hash_lock
);
559 this.class = check_source
->class;
560 if (!save_trace(&this.trace
))
562 __raw_spin_unlock(&hash_lock
);
563 print_circular_bug_entry(&this, 0);
565 printk("\nother info that might help us debug this:\n\n");
566 lockdep_print_held_locks(curr
);
568 printk("\nstack backtrace:\n");
574 #define RECURSION_LIMIT 40
576 static int noinline
print_infinite_recursion_bug(void)
578 __raw_spin_unlock(&hash_lock
);
579 DEBUG_LOCKS_WARN_ON(1);
585 * Prove that the dependency graph starting at <entry> can not
586 * lead to <target>. Print an error and return 0 if it does.
589 check_noncircular(struct lock_class
*source
, unsigned int depth
)
591 struct lock_list
*entry
;
593 debug_atomic_inc(&nr_cyclic_check_recursions
);
594 if (depth
> max_recursion_depth
)
595 max_recursion_depth
= depth
;
596 if (depth
>= RECURSION_LIMIT
)
597 return print_infinite_recursion_bug();
599 * Check this lock's dependency list:
601 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
602 if (entry
->class == check_target
->class)
603 return print_circular_bug_header(entry
, depth
+1);
604 debug_atomic_inc(&nr_cyclic_checks
);
605 if (!check_noncircular(entry
->class, depth
+1))
606 return print_circular_bug_entry(entry
, depth
+1);
611 static int very_verbose(struct lock_class
*class)
614 return class_filter(class);
618 #ifdef CONFIG_TRACE_IRQFLAGS
621 * Forwards and backwards subgraph searching, for the purposes of
622 * proving that two subgraphs can be connected by a new dependency
623 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
625 static enum lock_usage_bit find_usage_bit
;
626 static struct lock_class
*forwards_match
, *backwards_match
;
629 * Find a node in the forwards-direction dependency sub-graph starting
630 * at <source> that matches <find_usage_bit>.
632 * Return 2 if such a node exists in the subgraph, and put that node
633 * into <forwards_match>.
635 * Return 1 otherwise and keep <forwards_match> unchanged.
639 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
641 struct lock_list
*entry
;
644 if (depth
> max_recursion_depth
)
645 max_recursion_depth
= depth
;
646 if (depth
>= RECURSION_LIMIT
)
647 return print_infinite_recursion_bug();
649 debug_atomic_inc(&nr_find_usage_forwards_checks
);
650 if (source
->usage_mask
& (1 << find_usage_bit
)) {
651 forwards_match
= source
;
656 * Check this lock's dependency list:
658 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
659 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
660 ret
= find_usage_forwards(entry
->class, depth
+1);
661 if (ret
== 2 || ret
== 0)
668 * Find a node in the backwards-direction dependency sub-graph starting
669 * at <source> that matches <find_usage_bit>.
671 * Return 2 if such a node exists in the subgraph, and put that node
672 * into <backwards_match>.
674 * Return 1 otherwise and keep <backwards_match> unchanged.
678 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
680 struct lock_list
*entry
;
683 if (depth
> max_recursion_depth
)
684 max_recursion_depth
= depth
;
685 if (depth
>= RECURSION_LIMIT
)
686 return print_infinite_recursion_bug();
688 debug_atomic_inc(&nr_find_usage_backwards_checks
);
689 if (source
->usage_mask
& (1 << find_usage_bit
)) {
690 backwards_match
= source
;
695 * Check this lock's dependency list:
697 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
698 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
699 ret
= find_usage_backwards(entry
->class, depth
+1);
700 if (ret
== 2 || ret
== 0)
707 print_bad_irq_dependency(struct task_struct
*curr
,
708 struct held_lock
*prev
,
709 struct held_lock
*next
,
710 enum lock_usage_bit bit1
,
711 enum lock_usage_bit bit2
,
712 const char *irqclass
)
714 __raw_spin_unlock(&hash_lock
);
716 if (debug_locks_silent
)
719 printk("\n======================================================\n");
720 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
722 print_kernel_version();
723 printk( "------------------------------------------------------\n");
724 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
725 curr
->comm
, curr
->pid
,
726 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
727 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
728 curr
->hardirqs_enabled
,
729 curr
->softirqs_enabled
);
732 printk("\nand this task is already holding:\n");
734 printk("which would create a new lock dependency:\n");
735 print_lock_name(prev
->class);
737 print_lock_name(next
->class);
740 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
742 print_lock_name(backwards_match
);
743 printk("\n... which became %s-irq-safe at:\n", irqclass
);
745 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
747 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
748 print_lock_name(forwards_match
);
749 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
752 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
754 printk("\nother info that might help us debug this:\n\n");
755 lockdep_print_held_locks(curr
);
757 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
758 print_lock_dependencies(backwards_match
, 0);
760 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
761 print_lock_dependencies(forwards_match
, 0);
763 printk("\nstack backtrace:\n");
770 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
771 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
772 enum lock_usage_bit bit_forwards
, const char *irqclass
)
776 find_usage_bit
= bit_backwards
;
777 /* fills in <backwards_match> */
778 ret
= find_usage_backwards(prev
->class, 0);
779 if (!ret
|| ret
== 1)
782 find_usage_bit
= bit_forwards
;
783 ret
= find_usage_forwards(next
->class, 0);
784 if (!ret
|| ret
== 1)
787 return print_bad_irq_dependency(curr
, prev
, next
,
788 bit_backwards
, bit_forwards
, irqclass
);
794 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
795 struct held_lock
*next
)
798 __raw_spin_unlock(&hash_lock
);
799 if (debug_locks_silent
)
802 printk("\n=============================================\n");
803 printk( "[ INFO: possible recursive locking detected ]\n");
804 print_kernel_version();
805 printk( "---------------------------------------------\n");
806 printk("%s/%d is trying to acquire lock:\n",
807 curr
->comm
, curr
->pid
);
809 printk("\nbut task is already holding lock:\n");
812 printk("\nother info that might help us debug this:\n");
813 lockdep_print_held_locks(curr
);
815 printk("\nstack backtrace:\n");
822 * Check whether we are holding such a class already.
824 * (Note that this has to be done separately, because the graph cannot
825 * detect such classes of deadlocks.)
827 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
830 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
831 struct lockdep_map
*next_instance
, int read
)
833 struct held_lock
*prev
;
836 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
837 prev
= curr
->held_locks
+ i
;
838 if (prev
->class != next
->class)
841 * Allow read-after-read recursion of the same
842 * lock class (i.e. read_lock(lock)+read_lock(lock)):
844 if ((read
== 2) && prev
->read
)
846 return print_deadlock_bug(curr
, prev
, next
);
852 * There was a chain-cache miss, and we are about to add a new dependency
853 * to a previous lock. We recursively validate the following rules:
855 * - would the adding of the <prev> -> <next> dependency create a
856 * circular dependency in the graph? [== circular deadlock]
858 * - does the new prev->next dependency connect any hardirq-safe lock
859 * (in the full backwards-subgraph starting at <prev>) with any
860 * hardirq-unsafe lock (in the full forwards-subgraph starting at
861 * <next>)? [== illegal lock inversion with hardirq contexts]
863 * - does the new prev->next dependency connect any softirq-safe lock
864 * (in the full backwards-subgraph starting at <prev>) with any
865 * softirq-unsafe lock (in the full forwards-subgraph starting at
866 * <next>)? [== illegal lock inversion with softirq contexts]
868 * any of these scenarios could lead to a deadlock.
870 * Then if all the validations pass, we add the forwards and backwards
874 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
875 struct held_lock
*next
)
877 struct lock_list
*entry
;
881 * Prove that the new <prev> -> <next> dependency would not
882 * create a circular dependency in the graph. (We do this by
883 * forward-recursing into the graph starting at <next>, and
884 * checking whether we can reach <prev>.)
886 * We are using global variables to control the recursion, to
887 * keep the stackframe size of the recursive functions low:
891 if (!(check_noncircular(next
->class, 0)))
892 return print_circular_bug_tail();
894 #ifdef CONFIG_TRACE_IRQFLAGS
896 * Prove that the new dependency does not connect a hardirq-safe
897 * lock with a hardirq-unsafe lock - to achieve this we search
898 * the backwards-subgraph starting at <prev>, and the
899 * forwards-subgraph starting at <next>:
901 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ
,
902 LOCK_ENABLED_HARDIRQS
, "hard"))
906 * Prove that the new dependency does not connect a hardirq-safe-read
907 * lock with a hardirq-unsafe lock - to achieve this we search
908 * the backwards-subgraph starting at <prev>, and the
909 * forwards-subgraph starting at <next>:
911 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ_READ
,
912 LOCK_ENABLED_HARDIRQS
, "hard-read"))
916 * Prove that the new dependency does not connect a softirq-safe
917 * lock with a softirq-unsafe lock - to achieve this we search
918 * the backwards-subgraph starting at <prev>, and the
919 * forwards-subgraph starting at <next>:
921 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ
,
922 LOCK_ENABLED_SOFTIRQS
, "soft"))
925 * Prove that the new dependency does not connect a softirq-safe-read
926 * lock with a softirq-unsafe lock - to achieve this we search
927 * the backwards-subgraph starting at <prev>, and the
928 * forwards-subgraph starting at <next>:
930 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ_READ
,
931 LOCK_ENABLED_SOFTIRQS
, "soft"))
935 * For recursive read-locks we do all the dependency checks,
936 * but we dont store read-triggered dependencies (only
937 * write-triggered dependencies). This ensures that only the
938 * write-side dependencies matter, and that if for example a
939 * write-lock never takes any other locks, then the reads are
940 * equivalent to a NOP.
942 if (next
->read
== 2 || prev
->read
== 2)
945 * Is the <prev> -> <next> dependency already present?
947 * (this may occur even though this is a new chain: consider
948 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
949 * chains - the second one will be new, but L1 already has
950 * L2 added to its dependency list, due to the first chain.)
952 list_for_each_entry(entry
, &prev
->class->locks_after
, entry
) {
953 if (entry
->class == next
->class)
958 * Ok, all validations passed, add the new lock
959 * to the previous lock's dependency list:
961 ret
= add_lock_to_list(prev
->class, next
->class,
962 &prev
->class->locks_after
, next
->acquire_ip
);
966 ret
= add_lock_to_list(next
->class, prev
->class,
967 &next
->class->locks_before
, next
->acquire_ip
);
972 * Debugging printouts:
974 if (verbose(prev
->class) || verbose(next
->class)) {
975 __raw_spin_unlock(&hash_lock
);
976 printk("\n new dependency: ");
977 print_lock_name(prev
->class);
979 print_lock_name(next
->class);
982 __raw_spin_lock(&hash_lock
);
988 * Add the dependency to all directly-previous locks that are 'relevant'.
989 * The ones that are relevant are (in increasing distance from curr):
990 * all consecutive trylock entries and the final non-trylock entry - or
991 * the end of this context's lock-chain - whichever comes first.
994 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
996 int depth
= curr
->lockdep_depth
;
997 struct held_lock
*hlock
;
1002 * Depth must not be zero for a non-head lock:
1007 * At least two relevant locks must exist for this
1010 if (curr
->held_locks
[depth
].irq_context
!=
1011 curr
->held_locks
[depth
-1].irq_context
)
1015 hlock
= curr
->held_locks
+ depth
-1;
1017 * Only non-recursive-read entries get new dependencies
1020 if (hlock
->read
!= 2) {
1021 if (!check_prev_add(curr
, hlock
, next
))
1024 * Stop after the first non-trylock entry,
1025 * as non-trylock entries have added their
1026 * own direct dependencies already, so this
1027 * lock is connected to them indirectly:
1029 if (!hlock
->trylock
)
1034 * End of lock-stack?
1039 * Stop the search if we cross into another context:
1041 if (curr
->held_locks
[depth
].irq_context
!=
1042 curr
->held_locks
[depth
-1].irq_context
)
1047 __raw_spin_unlock(&hash_lock
);
1048 DEBUG_LOCKS_WARN_ON(1);
1055 * Is this the address of a static object:
1057 static int static_obj(void *obj
)
1059 unsigned long start
= (unsigned long) &_stext
,
1060 end
= (unsigned long) &_end
,
1061 addr
= (unsigned long) obj
;
1069 if ((addr
>= start
) && (addr
< end
))
1076 for_each_possible_cpu(i
) {
1077 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
1078 end
= (unsigned long) &__per_cpu_start
+ PERCPU_ENOUGH_ROOM
1079 + per_cpu_offset(i
);
1081 if ((addr
>= start
) && (addr
< end
))
1089 return is_module_address(addr
);
1093 * To make lock name printouts unique, we calculate a unique
1094 * class->name_version generation counter:
1096 static int count_matching_names(struct lock_class
*new_class
)
1098 struct lock_class
*class;
1101 if (!new_class
->name
)
1104 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
1105 if (new_class
->key
- new_class
->subclass
== class->key
)
1106 return class->name_version
;
1107 if (class->name
&& !strcmp(class->name
, new_class
->name
))
1108 count
= max(count
, class->name_version
);
1115 * Register a lock's class in the hash-table, if the class is not present
1116 * yet. Otherwise we look it up. We cache the result in the lock object
1117 * itself, so actual lookup of the hash should be once per lock object.
1119 static inline struct lock_class
*
1120 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
1122 struct lockdep_subclass_key
*key
;
1123 struct list_head
*hash_head
;
1124 struct lock_class
*class;
1126 #ifdef CONFIG_DEBUG_LOCKDEP
1128 * If the architecture calls into lockdep before initializing
1129 * the hashes then we'll warn about it later. (we cannot printk
1132 if (unlikely(!lockdep_initialized
)) {
1134 lockdep_init_error
= 1;
1139 * Static locks do not have their class-keys yet - for them the key
1140 * is the lock object itself:
1142 if (unlikely(!lock
->key
))
1143 lock
->key
= (void *)lock
;
1146 * NOTE: the class-key must be unique. For dynamic locks, a static
1147 * lock_class_key variable is passed in through the mutex_init()
1148 * (or spin_lock_init()) call - which acts as the key. For static
1149 * locks we use the lock object itself as the key.
1151 BUILD_BUG_ON(sizeof(struct lock_class_key
) > sizeof(struct lock_class
));
1153 key
= lock
->key
->subkeys
+ subclass
;
1155 hash_head
= classhashentry(key
);
1158 * We can walk the hash lockfree, because the hash only
1159 * grows, and we are careful when adding entries to the end:
1161 list_for_each_entry(class, hash_head
, hash_entry
)
1162 if (class->key
== key
)
1169 * Register a lock's class in the hash-table, if the class is not present
1170 * yet. Otherwise we look it up. We cache the result in the lock object
1171 * itself, so actual lookup of the hash should be once per lock object.
1173 static inline struct lock_class
*
1174 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
1176 struct lockdep_subclass_key
*key
;
1177 struct list_head
*hash_head
;
1178 struct lock_class
*class;
1179 unsigned long flags
;
1181 class = look_up_lock_class(lock
, subclass
);
1186 * Debug-check: all keys must be persistent!
1188 if (!static_obj(lock
->key
)) {
1190 printk("INFO: trying to register non-static key.\n");
1191 printk("the code is fine but needs lockdep annotation.\n");
1192 printk("turning off the locking correctness validator.\n");
1198 key
= lock
->key
->subkeys
+ subclass
;
1199 hash_head
= classhashentry(key
);
1201 raw_local_irq_save(flags
);
1202 __raw_spin_lock(&hash_lock
);
1204 * We have to do the hash-walk again, to avoid races
1207 list_for_each_entry(class, hash_head
, hash_entry
)
1208 if (class->key
== key
)
1209 goto out_unlock_set
;
1211 * Allocate a new key from the static array, and add it to
1214 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
1215 __raw_spin_unlock(&hash_lock
);
1216 raw_local_irq_restore(flags
);
1218 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
1219 printk("turning off the locking correctness validator.\n");
1222 class = lock_classes
+ nr_lock_classes
++;
1223 debug_atomic_inc(&nr_unused_locks
);
1225 class->name
= lock
->name
;
1226 class->subclass
= subclass
;
1227 INIT_LIST_HEAD(&class->lock_entry
);
1228 INIT_LIST_HEAD(&class->locks_before
);
1229 INIT_LIST_HEAD(&class->locks_after
);
1230 class->name_version
= count_matching_names(class);
1232 * We use RCU's safe list-add method to make
1233 * parallel walking of the hash-list safe:
1235 list_add_tail_rcu(&class->hash_entry
, hash_head
);
1237 if (verbose(class)) {
1238 __raw_spin_unlock(&hash_lock
);
1239 raw_local_irq_restore(flags
);
1240 printk("\nnew class %p: %s", class->key
, class->name
);
1241 if (class->name_version
> 1)
1242 printk("#%d", class->name_version
);
1245 raw_local_irq_save(flags
);
1246 __raw_spin_lock(&hash_lock
);
1249 __raw_spin_unlock(&hash_lock
);
1250 raw_local_irq_restore(flags
);
1252 if (!subclass
|| force
)
1253 lock
->class_cache
= class;
1255 DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
);
1261 * Look up a dependency chain. If the key is not present yet then
1262 * add it and return 0 - in this case the new dependency chain is
1263 * validated. If the key is already hashed, return 1.
1265 static inline int lookup_chain_cache(u64 chain_key
, struct lock_class
*class)
1267 struct list_head
*hash_head
= chainhashentry(chain_key
);
1268 struct lock_chain
*chain
;
1270 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1272 * We can walk it lock-free, because entries only get added
1275 list_for_each_entry(chain
, hash_head
, entry
) {
1276 if (chain
->chain_key
== chain_key
) {
1278 debug_atomic_inc(&chain_lookup_hits
);
1280 * In the debugging case, force redundant checking
1283 #ifdef CONFIG_DEBUG_LOCKDEP
1284 __raw_spin_lock(&hash_lock
);
1287 if (very_verbose(class))
1288 printk("\nhash chain already cached, key: %016Lx tail class: [%p] %s\n", chain_key
, class->key
, class->name
);
1292 if (very_verbose(class))
1293 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", chain_key
, class->key
, class->name
);
1295 * Allocate a new chain entry from the static array, and add
1298 __raw_spin_lock(&hash_lock
);
1300 * We have to walk the chain again locked - to avoid duplicates:
1302 list_for_each_entry(chain
, hash_head
, entry
) {
1303 if (chain
->chain_key
== chain_key
) {
1304 __raw_spin_unlock(&hash_lock
);
1308 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1309 __raw_spin_unlock(&hash_lock
);
1311 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1312 printk("turning off the locking correctness validator.\n");
1315 chain
= lock_chains
+ nr_lock_chains
++;
1316 chain
->chain_key
= chain_key
;
1317 list_add_tail_rcu(&chain
->entry
, hash_head
);
1318 debug_atomic_inc(&chain_lookup_misses
);
1319 #ifdef CONFIG_TRACE_IRQFLAGS
1320 if (current
->hardirq_context
)
1321 nr_hardirq_chains
++;
1323 if (current
->softirq_context
)
1324 nr_softirq_chains
++;
1326 nr_process_chains
++;
1329 nr_process_chains
++;
1336 * We are building curr_chain_key incrementally, so double-check
1337 * it from scratch, to make sure that it's done correctly:
1339 static void check_chain_key(struct task_struct
*curr
)
1341 #ifdef CONFIG_DEBUG_LOCKDEP
1342 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1346 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1347 hlock
= curr
->held_locks
+ i
;
1348 if (chain_key
!= hlock
->prev_chain_key
) {
1350 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1351 curr
->lockdep_depth
, i
,
1352 (unsigned long long)chain_key
,
1353 (unsigned long long)hlock
->prev_chain_key
);
1357 id
= hlock
->class - lock_classes
;
1358 DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
);
1359 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1360 hlock
->irq_context
))
1362 chain_key
= iterate_chain_key(chain_key
, id
);
1365 if (chain_key
!= curr
->curr_chain_key
) {
1367 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1368 curr
->lockdep_depth
, i
,
1369 (unsigned long long)chain_key
,
1370 (unsigned long long)curr
->curr_chain_key
);
1376 #ifdef CONFIG_TRACE_IRQFLAGS
1379 * print irq inversion bug:
1382 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
1383 struct held_lock
*this, int forwards
,
1384 const char *irqclass
)
1386 __raw_spin_unlock(&hash_lock
);
1388 if (debug_locks_silent
)
1391 printk("\n=========================================================\n");
1392 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1393 print_kernel_version();
1394 printk( "---------------------------------------------------------\n");
1395 printk("%s/%d just changed the state of lock:\n",
1396 curr
->comm
, curr
->pid
);
1399 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass
);
1401 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass
);
1402 print_lock_name(other
);
1403 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1405 printk("\nother info that might help us debug this:\n");
1406 lockdep_print_held_locks(curr
);
1408 printk("\nthe first lock's dependencies:\n");
1409 print_lock_dependencies(this->class, 0);
1411 printk("\nthe second lock's dependencies:\n");
1412 print_lock_dependencies(other
, 0);
1414 printk("\nstack backtrace:\n");
1421 * Prove that in the forwards-direction subgraph starting at <this>
1422 * there is no lock matching <mask>:
1425 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
1426 enum lock_usage_bit bit
, const char *irqclass
)
1430 find_usage_bit
= bit
;
1431 /* fills in <forwards_match> */
1432 ret
= find_usage_forwards(this->class, 0);
1433 if (!ret
|| ret
== 1)
1436 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
1440 * Prove that in the backwards-direction subgraph starting at <this>
1441 * there is no lock matching <mask>:
1444 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
1445 enum lock_usage_bit bit
, const char *irqclass
)
1449 find_usage_bit
= bit
;
1450 /* fills in <backwards_match> */
1451 ret
= find_usage_backwards(this->class, 0);
1452 if (!ret
|| ret
== 1)
1455 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
1458 static inline void print_irqtrace_events(struct task_struct
*curr
)
1460 printk("irq event stamp: %u\n", curr
->irq_events
);
1461 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
1462 print_ip_sym(curr
->hardirq_enable_ip
);
1463 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
1464 print_ip_sym(curr
->hardirq_disable_ip
);
1465 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
1466 print_ip_sym(curr
->softirq_enable_ip
);
1467 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
1468 print_ip_sym(curr
->softirq_disable_ip
);
1472 static inline void print_irqtrace_events(struct task_struct
*curr
)
1478 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1479 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1481 __raw_spin_unlock(&hash_lock
);
1483 if (debug_locks_silent
)
1486 printk("\n=================================\n");
1487 printk( "[ INFO: inconsistent lock state ]\n");
1488 print_kernel_version();
1489 printk( "---------------------------------\n");
1491 printk("inconsistent {%s} -> {%s} usage.\n",
1492 usage_str
[prev_bit
], usage_str
[new_bit
]);
1494 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1495 curr
->comm
, curr
->pid
,
1496 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1497 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1498 trace_hardirqs_enabled(curr
),
1499 trace_softirqs_enabled(curr
));
1502 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1503 print_stack_trace(this->class->usage_traces
+ prev_bit
, 1);
1505 print_irqtrace_events(curr
);
1506 printk("\nother info that might help us debug this:\n");
1507 lockdep_print_held_locks(curr
);
1509 printk("\nstack backtrace:\n");
1516 * Print out an error if an invalid bit is set:
1519 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1520 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1522 if (unlikely(this->class->usage_mask
& (1 << bad_bit
)))
1523 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1527 #define STRICT_READ_CHECKS 1
1530 * Mark a lock with a usage bit, and validate the state transition:
1532 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1533 enum lock_usage_bit new_bit
, unsigned long ip
)
1535 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
1538 * If already set then do not dirty the cacheline,
1539 * nor do any checks:
1541 if (likely(this->class->usage_mask
& new_mask
))
1544 __raw_spin_lock(&hash_lock
);
1546 * Make sure we didnt race:
1548 if (unlikely(this->class->usage_mask
& new_mask
)) {
1549 __raw_spin_unlock(&hash_lock
);
1553 this->class->usage_mask
|= new_mask
;
1555 #ifdef CONFIG_TRACE_IRQFLAGS
1556 if (new_bit
== LOCK_ENABLED_HARDIRQS
||
1557 new_bit
== LOCK_ENABLED_HARDIRQS_READ
)
1558 ip
= curr
->hardirq_enable_ip
;
1559 else if (new_bit
== LOCK_ENABLED_SOFTIRQS
||
1560 new_bit
== LOCK_ENABLED_SOFTIRQS_READ
)
1561 ip
= curr
->softirq_enable_ip
;
1563 if (!save_trace(this->class->usage_traces
+ new_bit
))
1567 #ifdef CONFIG_TRACE_IRQFLAGS
1568 case LOCK_USED_IN_HARDIRQ
:
1569 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1571 if (!valid_state(curr
, this, new_bit
,
1572 LOCK_ENABLED_HARDIRQS_READ
))
1575 * just marked it hardirq-safe, check that this lock
1576 * took no hardirq-unsafe lock in the past:
1578 if (!check_usage_forwards(curr
, this,
1579 LOCK_ENABLED_HARDIRQS
, "hard"))
1581 #if STRICT_READ_CHECKS
1583 * just marked it hardirq-safe, check that this lock
1584 * took no hardirq-unsafe-read lock in the past:
1586 if (!check_usage_forwards(curr
, this,
1587 LOCK_ENABLED_HARDIRQS_READ
, "hard-read"))
1590 if (hardirq_verbose(this->class))
1593 case LOCK_USED_IN_SOFTIRQ
:
1594 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1596 if (!valid_state(curr
, this, new_bit
,
1597 LOCK_ENABLED_SOFTIRQS_READ
))
1600 * just marked it softirq-safe, check that this lock
1601 * took no softirq-unsafe lock in the past:
1603 if (!check_usage_forwards(curr
, this,
1604 LOCK_ENABLED_SOFTIRQS
, "soft"))
1606 #if STRICT_READ_CHECKS
1608 * just marked it softirq-safe, check that this lock
1609 * took no softirq-unsafe-read lock in the past:
1611 if (!check_usage_forwards(curr
, this,
1612 LOCK_ENABLED_SOFTIRQS_READ
, "soft-read"))
1615 if (softirq_verbose(this->class))
1618 case LOCK_USED_IN_HARDIRQ_READ
:
1619 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1622 * just marked it hardirq-read-safe, check that this lock
1623 * took no hardirq-unsafe lock in the past:
1625 if (!check_usage_forwards(curr
, this,
1626 LOCK_ENABLED_HARDIRQS
, "hard"))
1628 if (hardirq_verbose(this->class))
1631 case LOCK_USED_IN_SOFTIRQ_READ
:
1632 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1635 * just marked it softirq-read-safe, check that this lock
1636 * took no softirq-unsafe lock in the past:
1638 if (!check_usage_forwards(curr
, this,
1639 LOCK_ENABLED_SOFTIRQS
, "soft"))
1641 if (softirq_verbose(this->class))
1644 case LOCK_ENABLED_HARDIRQS
:
1645 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1647 if (!valid_state(curr
, this, new_bit
,
1648 LOCK_USED_IN_HARDIRQ_READ
))
1651 * just marked it hardirq-unsafe, check that no hardirq-safe
1652 * lock in the system ever took it in the past:
1654 if (!check_usage_backwards(curr
, this,
1655 LOCK_USED_IN_HARDIRQ
, "hard"))
1657 #if STRICT_READ_CHECKS
1659 * just marked it hardirq-unsafe, check that no
1660 * hardirq-safe-read lock in the system ever took
1663 if (!check_usage_backwards(curr
, this,
1664 LOCK_USED_IN_HARDIRQ_READ
, "hard-read"))
1667 if (hardirq_verbose(this->class))
1670 case LOCK_ENABLED_SOFTIRQS
:
1671 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1673 if (!valid_state(curr
, this, new_bit
,
1674 LOCK_USED_IN_SOFTIRQ_READ
))
1677 * just marked it softirq-unsafe, check that no softirq-safe
1678 * lock in the system ever took it in the past:
1680 if (!check_usage_backwards(curr
, this,
1681 LOCK_USED_IN_SOFTIRQ
, "soft"))
1683 #if STRICT_READ_CHECKS
1685 * just marked it softirq-unsafe, check that no
1686 * softirq-safe-read lock in the system ever took
1689 if (!check_usage_backwards(curr
, this,
1690 LOCK_USED_IN_SOFTIRQ_READ
, "soft-read"))
1693 if (softirq_verbose(this->class))
1696 case LOCK_ENABLED_HARDIRQS_READ
:
1697 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1699 #if STRICT_READ_CHECKS
1701 * just marked it hardirq-read-unsafe, check that no
1702 * hardirq-safe lock in the system ever took it in the past:
1704 if (!check_usage_backwards(curr
, this,
1705 LOCK_USED_IN_HARDIRQ
, "hard"))
1708 if (hardirq_verbose(this->class))
1711 case LOCK_ENABLED_SOFTIRQS_READ
:
1712 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1714 #if STRICT_READ_CHECKS
1716 * just marked it softirq-read-unsafe, check that no
1717 * softirq-safe lock in the system ever took it in the past:
1719 if (!check_usage_backwards(curr
, this,
1720 LOCK_USED_IN_SOFTIRQ
, "soft"))
1723 if (softirq_verbose(this->class))
1729 * Add it to the global list of classes:
1731 list_add_tail_rcu(&this->class->lock_entry
, &all_lock_classes
);
1732 debug_atomic_dec(&nr_unused_locks
);
1735 __raw_spin_unlock(&hash_lock
);
1741 __raw_spin_unlock(&hash_lock
);
1744 * We must printk outside of the hash_lock:
1747 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
1749 print_irqtrace_events(curr
);
1756 #ifdef CONFIG_TRACE_IRQFLAGS
1758 * Mark all held locks with a usage bit:
1761 mark_held_locks(struct task_struct
*curr
, int hardirq
, unsigned long ip
)
1763 enum lock_usage_bit usage_bit
;
1764 struct held_lock
*hlock
;
1767 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1768 hlock
= curr
->held_locks
+ i
;
1772 usage_bit
= LOCK_ENABLED_HARDIRQS_READ
;
1774 usage_bit
= LOCK_ENABLED_HARDIRQS
;
1777 usage_bit
= LOCK_ENABLED_SOFTIRQS_READ
;
1779 usage_bit
= LOCK_ENABLED_SOFTIRQS
;
1781 if (!mark_lock(curr
, hlock
, usage_bit
, ip
))
1789 * Debugging helper: via this flag we know that we are in
1790 * 'early bootup code', and will warn about any invalid irqs-on event:
1792 static int early_boot_irqs_enabled
;
1794 void early_boot_irqs_off(void)
1796 early_boot_irqs_enabled
= 0;
1799 void early_boot_irqs_on(void)
1801 early_boot_irqs_enabled
= 1;
1805 * Hardirqs will be enabled:
1807 void trace_hardirqs_on(void)
1809 struct task_struct
*curr
= current
;
1812 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
1815 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
1818 if (unlikely(curr
->hardirqs_enabled
)) {
1819 debug_atomic_inc(&redundant_hardirqs_on
);
1822 /* we'll do an OFF -> ON transition: */
1823 curr
->hardirqs_enabled
= 1;
1824 ip
= (unsigned long) __builtin_return_address(0);
1826 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1828 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
1831 * We are going to turn hardirqs on, so set the
1832 * usage bit for all held locks:
1834 if (!mark_held_locks(curr
, 1, ip
))
1837 * If we have softirqs enabled, then set the usage
1838 * bit for all held locks. (disabled hardirqs prevented
1839 * this bit from being set before)
1841 if (curr
->softirqs_enabled
)
1842 if (!mark_held_locks(curr
, 0, ip
))
1845 curr
->hardirq_enable_ip
= ip
;
1846 curr
->hardirq_enable_event
= ++curr
->irq_events
;
1847 debug_atomic_inc(&hardirqs_on_events
);
1850 EXPORT_SYMBOL(trace_hardirqs_on
);
1853 * Hardirqs were disabled:
1855 void trace_hardirqs_off(void)
1857 struct task_struct
*curr
= current
;
1859 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
1862 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1865 if (curr
->hardirqs_enabled
) {
1867 * We have done an ON -> OFF transition:
1869 curr
->hardirqs_enabled
= 0;
1870 curr
->hardirq_disable_ip
= _RET_IP_
;
1871 curr
->hardirq_disable_event
= ++curr
->irq_events
;
1872 debug_atomic_inc(&hardirqs_off_events
);
1874 debug_atomic_inc(&redundant_hardirqs_off
);
1877 EXPORT_SYMBOL(trace_hardirqs_off
);
1880 * Softirqs will be enabled:
1882 void trace_softirqs_on(unsigned long ip
)
1884 struct task_struct
*curr
= current
;
1886 if (unlikely(!debug_locks
))
1889 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1892 if (curr
->softirqs_enabled
) {
1893 debug_atomic_inc(&redundant_softirqs_on
);
1898 * We'll do an OFF -> ON transition:
1900 curr
->softirqs_enabled
= 1;
1901 curr
->softirq_enable_ip
= ip
;
1902 curr
->softirq_enable_event
= ++curr
->irq_events
;
1903 debug_atomic_inc(&softirqs_on_events
);
1905 * We are going to turn softirqs on, so set the
1906 * usage bit for all held locks, if hardirqs are
1909 if (curr
->hardirqs_enabled
)
1910 mark_held_locks(curr
, 0, ip
);
1914 * Softirqs were disabled:
1916 void trace_softirqs_off(unsigned long ip
)
1918 struct task_struct
*curr
= current
;
1920 if (unlikely(!debug_locks
))
1923 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1926 if (curr
->softirqs_enabled
) {
1928 * We have done an ON -> OFF transition:
1930 curr
->softirqs_enabled
= 0;
1931 curr
->softirq_disable_ip
= ip
;
1932 curr
->softirq_disable_event
= ++curr
->irq_events
;
1933 debug_atomic_inc(&softirqs_off_events
);
1934 DEBUG_LOCKS_WARN_ON(!softirq_count());
1936 debug_atomic_inc(&redundant_softirqs_off
);
1942 * Initialize a lock instance's lock-class mapping info:
1944 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
1945 struct lock_class_key
*key
, int subclass
)
1947 if (unlikely(!debug_locks
))
1950 if (DEBUG_LOCKS_WARN_ON(!key
))
1952 if (DEBUG_LOCKS_WARN_ON(!name
))
1955 * Sanity check, the lock-class key must be persistent:
1957 if (!static_obj(key
)) {
1958 printk("BUG: key %p not in .data!\n", key
);
1959 DEBUG_LOCKS_WARN_ON(1);
1964 lock
->class_cache
= NULL
;
1966 register_lock_class(lock
, subclass
, 1);
1969 EXPORT_SYMBOL_GPL(lockdep_init_map
);
1972 * This gets called for every mutex_lock*()/spin_lock*() operation.
1973 * We maintain the dependency maps and validate the locking attempt:
1975 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
1976 int trylock
, int read
, int check
, int hardirqs_off
,
1979 struct task_struct
*curr
= current
;
1980 struct lock_class
*class = NULL
;
1981 struct held_lock
*hlock
;
1982 unsigned int depth
, id
;
1986 if (unlikely(!debug_locks
))
1989 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1992 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
1994 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
1995 printk("turning off the locking correctness validator.\n");
2000 class = lock
->class_cache
;
2002 * Not cached yet or subclass?
2004 if (unlikely(!class)) {
2005 class = register_lock_class(lock
, subclass
, 0);
2009 debug_atomic_inc((atomic_t
*)&class->ops
);
2010 if (very_verbose(class)) {
2011 printk("\nacquire class [%p] %s", class->key
, class->name
);
2012 if (class->name_version
> 1)
2013 printk("#%d", class->name_version
);
2019 * Add the lock to the list of currently held locks.
2020 * (we dont increase the depth just yet, up until the
2021 * dependency checks are done)
2023 depth
= curr
->lockdep_depth
;
2024 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2027 hlock
= curr
->held_locks
+ depth
;
2029 hlock
->class = class;
2030 hlock
->acquire_ip
= ip
;
2031 hlock
->instance
= lock
;
2032 hlock
->trylock
= trylock
;
2034 hlock
->check
= check
;
2035 hlock
->hardirqs_off
= hardirqs_off
;
2039 #ifdef CONFIG_TRACE_IRQFLAGS
2041 * If non-trylock use in a hardirq or softirq context, then
2042 * mark the lock as used in these contexts:
2046 if (curr
->hardirq_context
)
2047 if (!mark_lock(curr
, hlock
,
2048 LOCK_USED_IN_HARDIRQ_READ
, ip
))
2050 if (curr
->softirq_context
)
2051 if (!mark_lock(curr
, hlock
,
2052 LOCK_USED_IN_SOFTIRQ_READ
, ip
))
2055 if (curr
->hardirq_context
)
2056 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
, ip
))
2058 if (curr
->softirq_context
)
2059 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
, ip
))
2063 if (!hardirqs_off
) {
2065 if (!mark_lock(curr
, hlock
,
2066 LOCK_ENABLED_HARDIRQS_READ
, ip
))
2068 if (curr
->softirqs_enabled
)
2069 if (!mark_lock(curr
, hlock
,
2070 LOCK_ENABLED_SOFTIRQS_READ
, ip
))
2073 if (!mark_lock(curr
, hlock
,
2074 LOCK_ENABLED_HARDIRQS
, ip
))
2076 if (curr
->softirqs_enabled
)
2077 if (!mark_lock(curr
, hlock
,
2078 LOCK_ENABLED_SOFTIRQS
, ip
))
2083 /* mark it as used: */
2084 if (!mark_lock(curr
, hlock
, LOCK_USED
, ip
))
2088 * Calculate the chain hash: it's the combined has of all the
2089 * lock keys along the dependency chain. We save the hash value
2090 * at every step so that we can get the current hash easily
2091 * after unlock. The chain hash is then used to cache dependency
2094 * The 'key ID' is what is the most compact key value to drive
2095 * the hash, not class->key.
2097 id
= class - lock_classes
;
2098 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2101 chain_key
= curr
->curr_chain_key
;
2103 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2108 hlock
->prev_chain_key
= chain_key
;
2110 #ifdef CONFIG_TRACE_IRQFLAGS
2112 * Keep track of points where we cross into an interrupt context:
2114 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2115 curr
->softirq_context
;
2117 struct held_lock
*prev_hlock
;
2119 prev_hlock
= curr
->held_locks
+ depth
-1;
2121 * If we cross into another context, reset the
2122 * hash key (this also prevents the checking and the
2123 * adding of the dependency to 'prev'):
2125 if (prev_hlock
->irq_context
!= hlock
->irq_context
) {
2131 chain_key
= iterate_chain_key(chain_key
, id
);
2132 curr
->curr_chain_key
= chain_key
;
2135 * Trylock needs to maintain the stack of held locks, but it
2136 * does not add new dependencies, because trylock can be done
2139 * We look up the chain_key and do the O(N^2) check and update of
2140 * the dependencies only if this is a new dependency chain.
2141 * (If lookup_chain_cache() returns with 1 it acquires
2144 if (!trylock
&& (check
== 2) && lookup_chain_cache(chain_key
, class)) {
2146 * Check whether last held lock:
2148 * - is irq-safe, if this lock is irq-unsafe
2149 * - is softirq-safe, if this lock is hardirq-unsafe
2151 * And check whether the new lock's dependency graph
2152 * could lead back to the previous lock.
2154 * any of these scenarios could lead to a deadlock. If
2157 int ret
= check_deadlock(curr
, hlock
, lock
, read
);
2162 * Mark recursive read, as we jump over it when
2163 * building dependencies (just like we jump over
2169 * Add dependency only if this lock is not the head
2170 * of the chain, and if it's not a secondary read-lock:
2172 if (!chain_head
&& ret
!= 2)
2173 if (!check_prevs_add(curr
, hlock
))
2175 __raw_spin_unlock(&hash_lock
);
2177 curr
->lockdep_depth
++;
2178 check_chain_key(curr
);
2179 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2181 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2182 printk("turning off the locking correctness validator.\n");
2185 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2186 max_lockdep_depth
= curr
->lockdep_depth
;
2192 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2195 if (!debug_locks_off())
2197 if (debug_locks_silent
)
2200 printk("\n=====================================\n");
2201 printk( "[ BUG: bad unlock balance detected! ]\n");
2202 printk( "-------------------------------------\n");
2203 printk("%s/%d is trying to release lock (",
2204 curr
->comm
, curr
->pid
);
2205 print_lockdep_cache(lock
);
2208 printk("but there are no more locks to release!\n");
2209 printk("\nother info that might help us debug this:\n");
2210 lockdep_print_held_locks(curr
);
2212 printk("\nstack backtrace:\n");
2219 * Common debugging checks for both nested and non-nested unlock:
2221 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2224 if (unlikely(!debug_locks
))
2226 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2229 if (curr
->lockdep_depth
<= 0)
2230 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2236 * Remove the lock to the list of currently held locks in a
2237 * potentially non-nested (out of order) manner. This is a
2238 * relatively rare operation, as all the unlock APIs default
2239 * to nested mode (which uses lock_release()):
2242 lock_release_non_nested(struct task_struct
*curr
,
2243 struct lockdep_map
*lock
, unsigned long ip
)
2245 struct held_lock
*hlock
, *prev_hlock
;
2250 * Check whether the lock exists in the current stack
2253 depth
= curr
->lockdep_depth
;
2254 if (DEBUG_LOCKS_WARN_ON(!depth
))
2258 for (i
= depth
-1; i
>= 0; i
--) {
2259 hlock
= curr
->held_locks
+ i
;
2261 * We must not cross into another context:
2263 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2265 if (hlock
->instance
== lock
)
2269 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2273 * We have the right lock to unlock, 'hlock' points to it.
2274 * Now we remove it from the stack, and add back the other
2275 * entries (if any), recalculating the hash along the way:
2277 curr
->lockdep_depth
= i
;
2278 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2280 for (i
++; i
< depth
; i
++) {
2281 hlock
= curr
->held_locks
+ i
;
2282 if (!__lock_acquire(hlock
->instance
,
2283 hlock
->class->subclass
, hlock
->trylock
,
2284 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2289 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2295 * Remove the lock to the list of currently held locks - this gets
2296 * called on mutex_unlock()/spin_unlock*() (or on a failed
2297 * mutex_lock_interruptible()). This is done for unlocks that nest
2298 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2300 static int lock_release_nested(struct task_struct
*curr
,
2301 struct lockdep_map
*lock
, unsigned long ip
)
2303 struct held_lock
*hlock
;
2307 * Pop off the top of the lock stack:
2309 depth
= curr
->lockdep_depth
- 1;
2310 hlock
= curr
->held_locks
+ depth
;
2313 * Is the unlock non-nested:
2315 if (hlock
->instance
!= lock
)
2316 return lock_release_non_nested(curr
, lock
, ip
);
2317 curr
->lockdep_depth
--;
2319 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2322 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2324 #ifdef CONFIG_DEBUG_LOCKDEP
2325 hlock
->prev_chain_key
= 0;
2326 hlock
->class = NULL
;
2327 hlock
->acquire_ip
= 0;
2328 hlock
->irq_context
= 0;
2334 * Remove the lock to the list of currently held locks - this gets
2335 * called on mutex_unlock()/spin_unlock*() (or on a failed
2336 * mutex_lock_interruptible()). This is done for unlocks that nest
2337 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2340 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2342 struct task_struct
*curr
= current
;
2344 if (!check_unlock(curr
, lock
, ip
))
2348 if (!lock_release_nested(curr
, lock
, ip
))
2351 if (!lock_release_non_nested(curr
, lock
, ip
))
2355 check_chain_key(curr
);
2359 * Check whether we follow the irq-flags state precisely:
2361 static void check_flags(unsigned long flags
)
2363 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2367 if (irqs_disabled_flags(flags
))
2368 DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
);
2370 DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
);
2373 * We dont accurately track softirq state in e.g.
2374 * hardirq contexts (such as on 4KSTACKS), so only
2375 * check if not in hardirq contexts:
2377 if (!hardirq_count()) {
2378 if (softirq_count())
2379 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
2381 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
2385 print_irqtrace_events(current
);
2390 * We are not always called with irqs disabled - do that here,
2391 * and also avoid lockdep recursion:
2393 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2394 int trylock
, int read
, int check
, unsigned long ip
)
2396 unsigned long flags
;
2398 if (unlikely(current
->lockdep_recursion
))
2401 raw_local_irq_save(flags
);
2404 current
->lockdep_recursion
= 1;
2405 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
2406 irqs_disabled_flags(flags
), ip
);
2407 current
->lockdep_recursion
= 0;
2408 raw_local_irq_restore(flags
);
2411 EXPORT_SYMBOL_GPL(lock_acquire
);
2413 void lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2415 unsigned long flags
;
2417 if (unlikely(current
->lockdep_recursion
))
2420 raw_local_irq_save(flags
);
2422 current
->lockdep_recursion
= 1;
2423 __lock_release(lock
, nested
, ip
);
2424 current
->lockdep_recursion
= 0;
2425 raw_local_irq_restore(flags
);
2428 EXPORT_SYMBOL_GPL(lock_release
);
2431 * Used by the testsuite, sanitize the validator state
2432 * after a simulated failure:
2435 void lockdep_reset(void)
2437 unsigned long flags
;
2440 raw_local_irq_save(flags
);
2441 current
->curr_chain_key
= 0;
2442 current
->lockdep_depth
= 0;
2443 current
->lockdep_recursion
= 0;
2444 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
2445 nr_hardirq_chains
= 0;
2446 nr_softirq_chains
= 0;
2447 nr_process_chains
= 0;
2449 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
2450 INIT_LIST_HEAD(chainhash_table
+ i
);
2451 raw_local_irq_restore(flags
);
2454 static void zap_class(struct lock_class
*class)
2459 * Remove all dependencies this lock is
2462 for (i
= 0; i
< nr_list_entries
; i
++) {
2463 if (list_entries
[i
].class == class)
2464 list_del_rcu(&list_entries
[i
].entry
);
2467 * Unhash the class and remove it from the all_lock_classes list:
2469 list_del_rcu(&class->hash_entry
);
2470 list_del_rcu(&class->lock_entry
);
2474 static inline int within(void *addr
, void *start
, unsigned long size
)
2476 return addr
>= start
&& addr
< start
+ size
;
2479 void lockdep_free_key_range(void *start
, unsigned long size
)
2481 struct lock_class
*class, *next
;
2482 struct list_head
*head
;
2483 unsigned long flags
;
2486 raw_local_irq_save(flags
);
2487 __raw_spin_lock(&hash_lock
);
2490 * Unhash all classes that were created by this module:
2492 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
2493 head
= classhash_table
+ i
;
2494 if (list_empty(head
))
2496 list_for_each_entry_safe(class, next
, head
, hash_entry
)
2497 if (within(class->key
, start
, size
))
2501 __raw_spin_unlock(&hash_lock
);
2502 raw_local_irq_restore(flags
);
2505 void lockdep_reset_lock(struct lockdep_map
*lock
)
2507 struct lock_class
*class, *next
;
2508 struct list_head
*head
;
2509 unsigned long flags
;
2512 raw_local_irq_save(flags
);
2515 * Remove all classes this lock might have:
2517 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
2519 * If the class exists we look it up and zap it:
2521 class = look_up_lock_class(lock
, j
);
2526 * Debug check: in the end all mapped classes should
2529 __raw_spin_lock(&hash_lock
);
2530 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
2531 head
= classhash_table
+ i
;
2532 if (list_empty(head
))
2534 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
2535 if (unlikely(class == lock
->class_cache
)) {
2536 __raw_spin_unlock(&hash_lock
);
2537 DEBUG_LOCKS_WARN_ON(1);
2542 __raw_spin_unlock(&hash_lock
);
2545 raw_local_irq_restore(flags
);
2548 void __init
lockdep_init(void)
2553 * Some architectures have their own start_kernel()
2554 * code which calls lockdep_init(), while we also
2555 * call lockdep_init() from the start_kernel() itself,
2556 * and we want to initialize the hashes only once:
2558 if (lockdep_initialized
)
2561 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
2562 INIT_LIST_HEAD(classhash_table
+ i
);
2564 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
2565 INIT_LIST_HEAD(chainhash_table
+ i
);
2567 lockdep_initialized
= 1;
2570 void __init
lockdep_info(void)
2572 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
2574 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
2575 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
2576 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
2577 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
2578 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
2579 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
2580 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
2582 printk(" memory used by lock dependency info: %lu kB\n",
2583 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
2584 sizeof(struct list_head
) * CLASSHASH_SIZE
+
2585 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
2586 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
2587 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
2589 printk(" per task-struct memory footprint: %lu bytes\n",
2590 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
2592 #ifdef CONFIG_DEBUG_LOCKDEP
2593 if (lockdep_init_error
)
2594 printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n");
2598 static inline int in_range(const void *start
, const void *addr
, const void *end
)
2600 return addr
>= start
&& addr
<= end
;
2604 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
2605 const void *mem_to
, struct held_lock
*hlock
)
2607 if (!debug_locks_off())
2609 if (debug_locks_silent
)
2612 printk("\n=========================\n");
2613 printk( "[ BUG: held lock freed! ]\n");
2614 printk( "-------------------------\n");
2615 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
2616 curr
->comm
, curr
->pid
, mem_from
, mem_to
-1);
2618 lockdep_print_held_locks(curr
);
2620 printk("\nstack backtrace:\n");
2625 * Called when kernel memory is freed (or unmapped), or if a lock
2626 * is destroyed or reinitialized - this code checks whether there is
2627 * any held lock in the memory range of <from> to <to>:
2629 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
2631 const void *mem_to
= mem_from
+ mem_len
, *lock_from
, *lock_to
;
2632 struct task_struct
*curr
= current
;
2633 struct held_lock
*hlock
;
2634 unsigned long flags
;
2637 if (unlikely(!debug_locks
))
2640 local_irq_save(flags
);
2641 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2642 hlock
= curr
->held_locks
+ i
;
2644 lock_from
= (void *)hlock
->instance
;
2645 lock_to
= (void *)(hlock
->instance
+ 1);
2647 if (!in_range(mem_from
, lock_from
, mem_to
) &&
2648 !in_range(mem_from
, lock_to
, mem_to
))
2651 print_freed_lock_bug(curr
, mem_from
, mem_to
, hlock
);
2654 local_irq_restore(flags
);
2656 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
2658 static void print_held_locks_bug(struct task_struct
*curr
)
2660 if (!debug_locks_off())
2662 if (debug_locks_silent
)
2665 printk("\n=====================================\n");
2666 printk( "[ BUG: lock held at task exit time! ]\n");
2667 printk( "-------------------------------------\n");
2668 printk("%s/%d is exiting with locks still held!\n",
2669 curr
->comm
, curr
->pid
);
2670 lockdep_print_held_locks(curr
);
2672 printk("\nstack backtrace:\n");
2676 void debug_check_no_locks_held(struct task_struct
*task
)
2678 if (unlikely(task
->lockdep_depth
> 0))
2679 print_held_locks_bug(task
);
2682 void debug_show_all_locks(void)
2684 struct task_struct
*g
, *p
;
2688 printk("\nShowing all locks held in the system:\n");
2691 * Here we try to get the tasklist_lock as hard as possible,
2692 * if not successful after 2 seconds we ignore it (but keep
2693 * trying). This is to enable a debug printout even if a
2694 * tasklist_lock-holding task deadlocks or crashes.
2697 if (!read_trylock(&tasklist_lock
)) {
2699 printk("hm, tasklist_lock locked, retrying... ");
2702 printk(" #%d", 10-count
);
2706 printk(" ignoring it.\n");
2710 printk(" locked it.\n");
2712 do_each_thread(g
, p
) {
2713 if (p
->lockdep_depth
)
2714 lockdep_print_held_locks(p
);
2716 if (read_trylock(&tasklist_lock
))
2718 } while_each_thread(g
, p
);
2721 printk("=============================================\n\n");
2724 read_unlock(&tasklist_lock
);
2727 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
2729 void debug_show_held_locks(struct task_struct
*task
)
2731 lockdep_print_held_locks(task
);
2734 EXPORT_SYMBOL_GPL(debug_show_held_locks
);