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
);
1279 if (very_verbose(class))
1280 printk("\nhash chain already cached, key: %016Lx tail class: [%p] %s\n", chain_key
, class->key
, class->name
);
1284 if (very_verbose(class))
1285 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", chain_key
, class->key
, class->name
);
1287 * Allocate a new chain entry from the static array, and add
1290 __raw_spin_lock(&hash_lock
);
1292 * We have to walk the chain again locked - to avoid duplicates:
1294 list_for_each_entry(chain
, hash_head
, entry
) {
1295 if (chain
->chain_key
== chain_key
) {
1296 __raw_spin_unlock(&hash_lock
);
1300 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1301 __raw_spin_unlock(&hash_lock
);
1303 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1304 printk("turning off the locking correctness validator.\n");
1307 chain
= lock_chains
+ nr_lock_chains
++;
1308 chain
->chain_key
= chain_key
;
1309 list_add_tail_rcu(&chain
->entry
, hash_head
);
1310 debug_atomic_inc(&chain_lookup_misses
);
1311 #ifdef CONFIG_TRACE_IRQFLAGS
1312 if (current
->hardirq_context
)
1313 nr_hardirq_chains
++;
1315 if (current
->softirq_context
)
1316 nr_softirq_chains
++;
1318 nr_process_chains
++;
1321 nr_process_chains
++;
1328 * We are building curr_chain_key incrementally, so double-check
1329 * it from scratch, to make sure that it's done correctly:
1331 static void check_chain_key(struct task_struct
*curr
)
1333 #ifdef CONFIG_DEBUG_LOCKDEP
1334 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1338 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1339 hlock
= curr
->held_locks
+ i
;
1340 if (chain_key
!= hlock
->prev_chain_key
) {
1342 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1343 curr
->lockdep_depth
, i
,
1344 (unsigned long long)chain_key
,
1345 (unsigned long long)hlock
->prev_chain_key
);
1349 id
= hlock
->class - lock_classes
;
1350 DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
);
1351 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1352 hlock
->irq_context
))
1354 chain_key
= iterate_chain_key(chain_key
, id
);
1357 if (chain_key
!= curr
->curr_chain_key
) {
1359 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1360 curr
->lockdep_depth
, i
,
1361 (unsigned long long)chain_key
,
1362 (unsigned long long)curr
->curr_chain_key
);
1368 #ifdef CONFIG_TRACE_IRQFLAGS
1371 * print irq inversion bug:
1374 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
1375 struct held_lock
*this, int forwards
,
1376 const char *irqclass
)
1378 __raw_spin_unlock(&hash_lock
);
1380 if (debug_locks_silent
)
1383 printk("\n=========================================================\n");
1384 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1385 print_kernel_version();
1386 printk( "---------------------------------------------------------\n");
1387 printk("%s/%d just changed the state of lock:\n",
1388 curr
->comm
, curr
->pid
);
1391 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass
);
1393 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass
);
1394 print_lock_name(other
);
1395 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1397 printk("\nother info that might help us debug this:\n");
1398 lockdep_print_held_locks(curr
);
1400 printk("\nthe first lock's dependencies:\n");
1401 print_lock_dependencies(this->class, 0);
1403 printk("\nthe second lock's dependencies:\n");
1404 print_lock_dependencies(other
, 0);
1406 printk("\nstack backtrace:\n");
1413 * Prove that in the forwards-direction subgraph starting at <this>
1414 * there is no lock matching <mask>:
1417 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
1418 enum lock_usage_bit bit
, const char *irqclass
)
1422 find_usage_bit
= bit
;
1423 /* fills in <forwards_match> */
1424 ret
= find_usage_forwards(this->class, 0);
1425 if (!ret
|| ret
== 1)
1428 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
1432 * Prove that in the backwards-direction subgraph starting at <this>
1433 * there is no lock matching <mask>:
1436 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
1437 enum lock_usage_bit bit
, const char *irqclass
)
1441 find_usage_bit
= bit
;
1442 /* fills in <backwards_match> */
1443 ret
= find_usage_backwards(this->class, 0);
1444 if (!ret
|| ret
== 1)
1447 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
1450 static inline void print_irqtrace_events(struct task_struct
*curr
)
1452 printk("irq event stamp: %u\n", curr
->irq_events
);
1453 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
1454 print_ip_sym(curr
->hardirq_enable_ip
);
1455 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
1456 print_ip_sym(curr
->hardirq_disable_ip
);
1457 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
1458 print_ip_sym(curr
->softirq_enable_ip
);
1459 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
1460 print_ip_sym(curr
->softirq_disable_ip
);
1464 static inline void print_irqtrace_events(struct task_struct
*curr
)
1470 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1471 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1473 __raw_spin_unlock(&hash_lock
);
1475 if (debug_locks_silent
)
1478 printk("\n=================================\n");
1479 printk( "[ INFO: inconsistent lock state ]\n");
1480 print_kernel_version();
1481 printk( "---------------------------------\n");
1483 printk("inconsistent {%s} -> {%s} usage.\n",
1484 usage_str
[prev_bit
], usage_str
[new_bit
]);
1486 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1487 curr
->comm
, curr
->pid
,
1488 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1489 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1490 trace_hardirqs_enabled(curr
),
1491 trace_softirqs_enabled(curr
));
1494 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1495 print_stack_trace(this->class->usage_traces
+ prev_bit
, 1);
1497 print_irqtrace_events(curr
);
1498 printk("\nother info that might help us debug this:\n");
1499 lockdep_print_held_locks(curr
);
1501 printk("\nstack backtrace:\n");
1508 * Print out an error if an invalid bit is set:
1511 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1512 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1514 if (unlikely(this->class->usage_mask
& (1 << bad_bit
)))
1515 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1519 #define STRICT_READ_CHECKS 1
1522 * Mark a lock with a usage bit, and validate the state transition:
1524 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1525 enum lock_usage_bit new_bit
, unsigned long ip
)
1527 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
1530 * If already set then do not dirty the cacheline,
1531 * nor do any checks:
1533 if (likely(this->class->usage_mask
& new_mask
))
1536 __raw_spin_lock(&hash_lock
);
1538 * Make sure we didnt race:
1540 if (unlikely(this->class->usage_mask
& new_mask
)) {
1541 __raw_spin_unlock(&hash_lock
);
1545 this->class->usage_mask
|= new_mask
;
1547 #ifdef CONFIG_TRACE_IRQFLAGS
1548 if (new_bit
== LOCK_ENABLED_HARDIRQS
||
1549 new_bit
== LOCK_ENABLED_HARDIRQS_READ
)
1550 ip
= curr
->hardirq_enable_ip
;
1551 else if (new_bit
== LOCK_ENABLED_SOFTIRQS
||
1552 new_bit
== LOCK_ENABLED_SOFTIRQS_READ
)
1553 ip
= curr
->softirq_enable_ip
;
1555 if (!save_trace(this->class->usage_traces
+ new_bit
))
1559 #ifdef CONFIG_TRACE_IRQFLAGS
1560 case LOCK_USED_IN_HARDIRQ
:
1561 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1563 if (!valid_state(curr
, this, new_bit
,
1564 LOCK_ENABLED_HARDIRQS_READ
))
1567 * just marked it hardirq-safe, check that this lock
1568 * took no hardirq-unsafe lock in the past:
1570 if (!check_usage_forwards(curr
, this,
1571 LOCK_ENABLED_HARDIRQS
, "hard"))
1573 #if STRICT_READ_CHECKS
1575 * just marked it hardirq-safe, check that this lock
1576 * took no hardirq-unsafe-read lock in the past:
1578 if (!check_usage_forwards(curr
, this,
1579 LOCK_ENABLED_HARDIRQS_READ
, "hard-read"))
1582 if (hardirq_verbose(this->class))
1585 case LOCK_USED_IN_SOFTIRQ
:
1586 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1588 if (!valid_state(curr
, this, new_bit
,
1589 LOCK_ENABLED_SOFTIRQS_READ
))
1592 * just marked it softirq-safe, check that this lock
1593 * took no softirq-unsafe lock in the past:
1595 if (!check_usage_forwards(curr
, this,
1596 LOCK_ENABLED_SOFTIRQS
, "soft"))
1598 #if STRICT_READ_CHECKS
1600 * just marked it softirq-safe, check that this lock
1601 * took no softirq-unsafe-read lock in the past:
1603 if (!check_usage_forwards(curr
, this,
1604 LOCK_ENABLED_SOFTIRQS_READ
, "soft-read"))
1607 if (softirq_verbose(this->class))
1610 case LOCK_USED_IN_HARDIRQ_READ
:
1611 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1614 * just marked it hardirq-read-safe, check that this lock
1615 * took no hardirq-unsafe lock in the past:
1617 if (!check_usage_forwards(curr
, this,
1618 LOCK_ENABLED_HARDIRQS
, "hard"))
1620 if (hardirq_verbose(this->class))
1623 case LOCK_USED_IN_SOFTIRQ_READ
:
1624 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1627 * just marked it softirq-read-safe, check that this lock
1628 * took no softirq-unsafe lock in the past:
1630 if (!check_usage_forwards(curr
, this,
1631 LOCK_ENABLED_SOFTIRQS
, "soft"))
1633 if (softirq_verbose(this->class))
1636 case LOCK_ENABLED_HARDIRQS
:
1637 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1639 if (!valid_state(curr
, this, new_bit
,
1640 LOCK_USED_IN_HARDIRQ_READ
))
1643 * just marked it hardirq-unsafe, check that no hardirq-safe
1644 * lock in the system ever took it in the past:
1646 if (!check_usage_backwards(curr
, this,
1647 LOCK_USED_IN_HARDIRQ
, "hard"))
1649 #if STRICT_READ_CHECKS
1651 * just marked it hardirq-unsafe, check that no
1652 * hardirq-safe-read lock in the system ever took
1655 if (!check_usage_backwards(curr
, this,
1656 LOCK_USED_IN_HARDIRQ_READ
, "hard-read"))
1659 if (hardirq_verbose(this->class))
1662 case LOCK_ENABLED_SOFTIRQS
:
1663 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1665 if (!valid_state(curr
, this, new_bit
,
1666 LOCK_USED_IN_SOFTIRQ_READ
))
1669 * just marked it softirq-unsafe, check that no softirq-safe
1670 * lock in the system ever took it in the past:
1672 if (!check_usage_backwards(curr
, this,
1673 LOCK_USED_IN_SOFTIRQ
, "soft"))
1675 #if STRICT_READ_CHECKS
1677 * just marked it softirq-unsafe, check that no
1678 * softirq-safe-read lock in the system ever took
1681 if (!check_usage_backwards(curr
, this,
1682 LOCK_USED_IN_SOFTIRQ_READ
, "soft-read"))
1685 if (softirq_verbose(this->class))
1688 case LOCK_ENABLED_HARDIRQS_READ
:
1689 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1691 #if STRICT_READ_CHECKS
1693 * just marked it hardirq-read-unsafe, check that no
1694 * hardirq-safe lock in the system ever took it in the past:
1696 if (!check_usage_backwards(curr
, this,
1697 LOCK_USED_IN_HARDIRQ
, "hard"))
1700 if (hardirq_verbose(this->class))
1703 case LOCK_ENABLED_SOFTIRQS_READ
:
1704 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1706 #if STRICT_READ_CHECKS
1708 * just marked it softirq-read-unsafe, check that no
1709 * softirq-safe lock in the system ever took it in the past:
1711 if (!check_usage_backwards(curr
, this,
1712 LOCK_USED_IN_SOFTIRQ
, "soft"))
1715 if (softirq_verbose(this->class))
1721 * Add it to the global list of classes:
1723 list_add_tail_rcu(&this->class->lock_entry
, &all_lock_classes
);
1724 debug_atomic_dec(&nr_unused_locks
);
1727 __raw_spin_unlock(&hash_lock
);
1733 __raw_spin_unlock(&hash_lock
);
1736 * We must printk outside of the hash_lock:
1739 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
1741 print_irqtrace_events(curr
);
1748 #ifdef CONFIG_TRACE_IRQFLAGS
1750 * Mark all held locks with a usage bit:
1753 mark_held_locks(struct task_struct
*curr
, int hardirq
, unsigned long ip
)
1755 enum lock_usage_bit usage_bit
;
1756 struct held_lock
*hlock
;
1759 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1760 hlock
= curr
->held_locks
+ i
;
1764 usage_bit
= LOCK_ENABLED_HARDIRQS_READ
;
1766 usage_bit
= LOCK_ENABLED_HARDIRQS
;
1769 usage_bit
= LOCK_ENABLED_SOFTIRQS_READ
;
1771 usage_bit
= LOCK_ENABLED_SOFTIRQS
;
1773 if (!mark_lock(curr
, hlock
, usage_bit
, ip
))
1781 * Debugging helper: via this flag we know that we are in
1782 * 'early bootup code', and will warn about any invalid irqs-on event:
1784 static int early_boot_irqs_enabled
;
1786 void early_boot_irqs_off(void)
1788 early_boot_irqs_enabled
= 0;
1791 void early_boot_irqs_on(void)
1793 early_boot_irqs_enabled
= 1;
1797 * Hardirqs will be enabled:
1799 void trace_hardirqs_on(void)
1801 struct task_struct
*curr
= current
;
1804 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
1807 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
1810 if (unlikely(curr
->hardirqs_enabled
)) {
1811 debug_atomic_inc(&redundant_hardirqs_on
);
1814 /* we'll do an OFF -> ON transition: */
1815 curr
->hardirqs_enabled
= 1;
1816 ip
= (unsigned long) __builtin_return_address(0);
1818 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1820 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
1823 * We are going to turn hardirqs on, so set the
1824 * usage bit for all held locks:
1826 if (!mark_held_locks(curr
, 1, ip
))
1829 * If we have softirqs enabled, then set the usage
1830 * bit for all held locks. (disabled hardirqs prevented
1831 * this bit from being set before)
1833 if (curr
->softirqs_enabled
)
1834 if (!mark_held_locks(curr
, 0, ip
))
1837 curr
->hardirq_enable_ip
= ip
;
1838 curr
->hardirq_enable_event
= ++curr
->irq_events
;
1839 debug_atomic_inc(&hardirqs_on_events
);
1842 EXPORT_SYMBOL(trace_hardirqs_on
);
1845 * Hardirqs were disabled:
1847 void trace_hardirqs_off(void)
1849 struct task_struct
*curr
= current
;
1851 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
1854 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1857 if (curr
->hardirqs_enabled
) {
1859 * We have done an ON -> OFF transition:
1861 curr
->hardirqs_enabled
= 0;
1862 curr
->hardirq_disable_ip
= _RET_IP_
;
1863 curr
->hardirq_disable_event
= ++curr
->irq_events
;
1864 debug_atomic_inc(&hardirqs_off_events
);
1866 debug_atomic_inc(&redundant_hardirqs_off
);
1869 EXPORT_SYMBOL(trace_hardirqs_off
);
1872 * Softirqs will be enabled:
1874 void trace_softirqs_on(unsigned long ip
)
1876 struct task_struct
*curr
= current
;
1878 if (unlikely(!debug_locks
))
1881 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1884 if (curr
->softirqs_enabled
) {
1885 debug_atomic_inc(&redundant_softirqs_on
);
1890 * We'll do an OFF -> ON transition:
1892 curr
->softirqs_enabled
= 1;
1893 curr
->softirq_enable_ip
= ip
;
1894 curr
->softirq_enable_event
= ++curr
->irq_events
;
1895 debug_atomic_inc(&softirqs_on_events
);
1897 * We are going to turn softirqs on, so set the
1898 * usage bit for all held locks, if hardirqs are
1901 if (curr
->hardirqs_enabled
)
1902 mark_held_locks(curr
, 0, ip
);
1906 * Softirqs were disabled:
1908 void trace_softirqs_off(unsigned long ip
)
1910 struct task_struct
*curr
= current
;
1912 if (unlikely(!debug_locks
))
1915 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1918 if (curr
->softirqs_enabled
) {
1920 * We have done an ON -> OFF transition:
1922 curr
->softirqs_enabled
= 0;
1923 curr
->softirq_disable_ip
= ip
;
1924 curr
->softirq_disable_event
= ++curr
->irq_events
;
1925 debug_atomic_inc(&softirqs_off_events
);
1926 DEBUG_LOCKS_WARN_ON(!softirq_count());
1928 debug_atomic_inc(&redundant_softirqs_off
);
1934 * Initialize a lock instance's lock-class mapping info:
1936 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
1937 struct lock_class_key
*key
, int subclass
)
1939 if (unlikely(!debug_locks
))
1942 if (DEBUG_LOCKS_WARN_ON(!key
))
1944 if (DEBUG_LOCKS_WARN_ON(!name
))
1947 * Sanity check, the lock-class key must be persistent:
1949 if (!static_obj(key
)) {
1950 printk("BUG: key %p not in .data!\n", key
);
1951 DEBUG_LOCKS_WARN_ON(1);
1956 lock
->class_cache
= NULL
;
1958 register_lock_class(lock
, subclass
, 1);
1961 EXPORT_SYMBOL_GPL(lockdep_init_map
);
1964 * This gets called for every mutex_lock*()/spin_lock*() operation.
1965 * We maintain the dependency maps and validate the locking attempt:
1967 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
1968 int trylock
, int read
, int check
, int hardirqs_off
,
1971 struct task_struct
*curr
= current
;
1972 struct lock_class
*class = NULL
;
1973 struct held_lock
*hlock
;
1974 unsigned int depth
, id
;
1978 if (unlikely(!debug_locks
))
1981 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1984 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
1986 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
1987 printk("turning off the locking correctness validator.\n");
1992 class = lock
->class_cache
;
1994 * Not cached yet or subclass?
1996 if (unlikely(!class)) {
1997 class = register_lock_class(lock
, subclass
, 0);
2001 debug_atomic_inc((atomic_t
*)&class->ops
);
2002 if (very_verbose(class)) {
2003 printk("\nacquire class [%p] %s", class->key
, class->name
);
2004 if (class->name_version
> 1)
2005 printk("#%d", class->name_version
);
2011 * Add the lock to the list of currently held locks.
2012 * (we dont increase the depth just yet, up until the
2013 * dependency checks are done)
2015 depth
= curr
->lockdep_depth
;
2016 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2019 hlock
= curr
->held_locks
+ depth
;
2021 hlock
->class = class;
2022 hlock
->acquire_ip
= ip
;
2023 hlock
->instance
= lock
;
2024 hlock
->trylock
= trylock
;
2026 hlock
->check
= check
;
2027 hlock
->hardirqs_off
= hardirqs_off
;
2031 #ifdef CONFIG_TRACE_IRQFLAGS
2033 * If non-trylock use in a hardirq or softirq context, then
2034 * mark the lock as used in these contexts:
2038 if (curr
->hardirq_context
)
2039 if (!mark_lock(curr
, hlock
,
2040 LOCK_USED_IN_HARDIRQ_READ
, ip
))
2042 if (curr
->softirq_context
)
2043 if (!mark_lock(curr
, hlock
,
2044 LOCK_USED_IN_SOFTIRQ_READ
, ip
))
2047 if (curr
->hardirq_context
)
2048 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
, ip
))
2050 if (curr
->softirq_context
)
2051 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
, ip
))
2055 if (!hardirqs_off
) {
2057 if (!mark_lock(curr
, hlock
,
2058 LOCK_ENABLED_HARDIRQS_READ
, ip
))
2060 if (curr
->softirqs_enabled
)
2061 if (!mark_lock(curr
, hlock
,
2062 LOCK_ENABLED_SOFTIRQS_READ
, ip
))
2065 if (!mark_lock(curr
, hlock
,
2066 LOCK_ENABLED_HARDIRQS
, ip
))
2068 if (curr
->softirqs_enabled
)
2069 if (!mark_lock(curr
, hlock
,
2070 LOCK_ENABLED_SOFTIRQS
, ip
))
2075 /* mark it as used: */
2076 if (!mark_lock(curr
, hlock
, LOCK_USED
, ip
))
2080 * Calculate the chain hash: it's the combined has of all the
2081 * lock keys along the dependency chain. We save the hash value
2082 * at every step so that we can get the current hash easily
2083 * after unlock. The chain hash is then used to cache dependency
2086 * The 'key ID' is what is the most compact key value to drive
2087 * the hash, not class->key.
2089 id
= class - lock_classes
;
2090 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2093 chain_key
= curr
->curr_chain_key
;
2095 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2100 hlock
->prev_chain_key
= chain_key
;
2102 #ifdef CONFIG_TRACE_IRQFLAGS
2104 * Keep track of points where we cross into an interrupt context:
2106 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2107 curr
->softirq_context
;
2109 struct held_lock
*prev_hlock
;
2111 prev_hlock
= curr
->held_locks
+ depth
-1;
2113 * If we cross into another context, reset the
2114 * hash key (this also prevents the checking and the
2115 * adding of the dependency to 'prev'):
2117 if (prev_hlock
->irq_context
!= hlock
->irq_context
) {
2123 chain_key
= iterate_chain_key(chain_key
, id
);
2124 curr
->curr_chain_key
= chain_key
;
2127 * Trylock needs to maintain the stack of held locks, but it
2128 * does not add new dependencies, because trylock can be done
2131 * We look up the chain_key and do the O(N^2) check and update of
2132 * the dependencies only if this is a new dependency chain.
2133 * (If lookup_chain_cache() returns with 1 it acquires
2136 if (!trylock
&& (check
== 2) && lookup_chain_cache(chain_key
, class)) {
2138 * Check whether last held lock:
2140 * - is irq-safe, if this lock is irq-unsafe
2141 * - is softirq-safe, if this lock is hardirq-unsafe
2143 * And check whether the new lock's dependency graph
2144 * could lead back to the previous lock.
2146 * any of these scenarios could lead to a deadlock. If
2149 int ret
= check_deadlock(curr
, hlock
, lock
, read
);
2154 * Mark recursive read, as we jump over it when
2155 * building dependencies (just like we jump over
2161 * Add dependency only if this lock is not the head
2162 * of the chain, and if it's not a secondary read-lock:
2164 if (!chain_head
&& ret
!= 2)
2165 if (!check_prevs_add(curr
, hlock
))
2167 __raw_spin_unlock(&hash_lock
);
2169 curr
->lockdep_depth
++;
2170 check_chain_key(curr
);
2171 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2173 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2174 printk("turning off the locking correctness validator.\n");
2177 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2178 max_lockdep_depth
= curr
->lockdep_depth
;
2184 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2187 if (!debug_locks_off())
2189 if (debug_locks_silent
)
2192 printk("\n=====================================\n");
2193 printk( "[ BUG: bad unlock balance detected! ]\n");
2194 printk( "-------------------------------------\n");
2195 printk("%s/%d is trying to release lock (",
2196 curr
->comm
, curr
->pid
);
2197 print_lockdep_cache(lock
);
2200 printk("but there are no more locks to release!\n");
2201 printk("\nother info that might help us debug this:\n");
2202 lockdep_print_held_locks(curr
);
2204 printk("\nstack backtrace:\n");
2211 * Common debugging checks for both nested and non-nested unlock:
2213 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2216 if (unlikely(!debug_locks
))
2218 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2221 if (curr
->lockdep_depth
<= 0)
2222 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2228 * Remove the lock to the list of currently held locks in a
2229 * potentially non-nested (out of order) manner. This is a
2230 * relatively rare operation, as all the unlock APIs default
2231 * to nested mode (which uses lock_release()):
2234 lock_release_non_nested(struct task_struct
*curr
,
2235 struct lockdep_map
*lock
, unsigned long ip
)
2237 struct held_lock
*hlock
, *prev_hlock
;
2242 * Check whether the lock exists in the current stack
2245 depth
= curr
->lockdep_depth
;
2246 if (DEBUG_LOCKS_WARN_ON(!depth
))
2250 for (i
= depth
-1; i
>= 0; i
--) {
2251 hlock
= curr
->held_locks
+ i
;
2253 * We must not cross into another context:
2255 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2257 if (hlock
->instance
== lock
)
2261 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2265 * We have the right lock to unlock, 'hlock' points to it.
2266 * Now we remove it from the stack, and add back the other
2267 * entries (if any), recalculating the hash along the way:
2269 curr
->lockdep_depth
= i
;
2270 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2272 for (i
++; i
< depth
; i
++) {
2273 hlock
= curr
->held_locks
+ i
;
2274 if (!__lock_acquire(hlock
->instance
,
2275 hlock
->class->subclass
, hlock
->trylock
,
2276 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2281 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2287 * Remove the lock to the list of currently held locks - this gets
2288 * called on mutex_unlock()/spin_unlock*() (or on a failed
2289 * mutex_lock_interruptible()). This is done for unlocks that nest
2290 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2292 static int lock_release_nested(struct task_struct
*curr
,
2293 struct lockdep_map
*lock
, unsigned long ip
)
2295 struct held_lock
*hlock
;
2299 * Pop off the top of the lock stack:
2301 depth
= curr
->lockdep_depth
- 1;
2302 hlock
= curr
->held_locks
+ depth
;
2305 * Is the unlock non-nested:
2307 if (hlock
->instance
!= lock
)
2308 return lock_release_non_nested(curr
, lock
, ip
);
2309 curr
->lockdep_depth
--;
2311 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2314 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2316 #ifdef CONFIG_DEBUG_LOCKDEP
2317 hlock
->prev_chain_key
= 0;
2318 hlock
->class = NULL
;
2319 hlock
->acquire_ip
= 0;
2320 hlock
->irq_context
= 0;
2326 * Remove the lock to the list of currently held locks - this gets
2327 * called on mutex_unlock()/spin_unlock*() (or on a failed
2328 * mutex_lock_interruptible()). This is done for unlocks that nest
2329 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2332 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2334 struct task_struct
*curr
= current
;
2336 if (!check_unlock(curr
, lock
, ip
))
2340 if (!lock_release_nested(curr
, lock
, ip
))
2343 if (!lock_release_non_nested(curr
, lock
, ip
))
2347 check_chain_key(curr
);
2351 * Check whether we follow the irq-flags state precisely:
2353 static void check_flags(unsigned long flags
)
2355 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2359 if (irqs_disabled_flags(flags
))
2360 DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
);
2362 DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
);
2365 * We dont accurately track softirq state in e.g.
2366 * hardirq contexts (such as on 4KSTACKS), so only
2367 * check if not in hardirq contexts:
2369 if (!hardirq_count()) {
2370 if (softirq_count())
2371 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
2373 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
2377 print_irqtrace_events(current
);
2382 * We are not always called with irqs disabled - do that here,
2383 * and also avoid lockdep recursion:
2385 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2386 int trylock
, int read
, int check
, unsigned long ip
)
2388 unsigned long flags
;
2390 if (unlikely(current
->lockdep_recursion
))
2393 raw_local_irq_save(flags
);
2396 current
->lockdep_recursion
= 1;
2397 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
2398 irqs_disabled_flags(flags
), ip
);
2399 current
->lockdep_recursion
= 0;
2400 raw_local_irq_restore(flags
);
2403 EXPORT_SYMBOL_GPL(lock_acquire
);
2405 void lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2407 unsigned long flags
;
2409 if (unlikely(current
->lockdep_recursion
))
2412 raw_local_irq_save(flags
);
2414 current
->lockdep_recursion
= 1;
2415 __lock_release(lock
, nested
, ip
);
2416 current
->lockdep_recursion
= 0;
2417 raw_local_irq_restore(flags
);
2420 EXPORT_SYMBOL_GPL(lock_release
);
2423 * Used by the testsuite, sanitize the validator state
2424 * after a simulated failure:
2427 void lockdep_reset(void)
2429 unsigned long flags
;
2432 raw_local_irq_save(flags
);
2433 current
->curr_chain_key
= 0;
2434 current
->lockdep_depth
= 0;
2435 current
->lockdep_recursion
= 0;
2436 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
2437 nr_hardirq_chains
= 0;
2438 nr_softirq_chains
= 0;
2439 nr_process_chains
= 0;
2441 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
2442 INIT_LIST_HEAD(chainhash_table
+ i
);
2443 raw_local_irq_restore(flags
);
2446 static void zap_class(struct lock_class
*class)
2451 * Remove all dependencies this lock is
2454 for (i
= 0; i
< nr_list_entries
; i
++) {
2455 if (list_entries
[i
].class == class)
2456 list_del_rcu(&list_entries
[i
].entry
);
2459 * Unhash the class and remove it from the all_lock_classes list:
2461 list_del_rcu(&class->hash_entry
);
2462 list_del_rcu(&class->lock_entry
);
2466 static inline int within(void *addr
, void *start
, unsigned long size
)
2468 return addr
>= start
&& addr
< start
+ size
;
2471 void lockdep_free_key_range(void *start
, unsigned long size
)
2473 struct lock_class
*class, *next
;
2474 struct list_head
*head
;
2475 unsigned long flags
;
2478 raw_local_irq_save(flags
);
2479 __raw_spin_lock(&hash_lock
);
2482 * Unhash all classes that were created by this module:
2484 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
2485 head
= classhash_table
+ i
;
2486 if (list_empty(head
))
2488 list_for_each_entry_safe(class, next
, head
, hash_entry
)
2489 if (within(class->key
, start
, size
))
2493 __raw_spin_unlock(&hash_lock
);
2494 raw_local_irq_restore(flags
);
2497 void lockdep_reset_lock(struct lockdep_map
*lock
)
2499 struct lock_class
*class, *next
;
2500 struct list_head
*head
;
2501 unsigned long flags
;
2504 raw_local_irq_save(flags
);
2507 * Remove all classes this lock might have:
2509 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
2511 * If the class exists we look it up and zap it:
2513 class = look_up_lock_class(lock
, j
);
2518 * Debug check: in the end all mapped classes should
2521 __raw_spin_lock(&hash_lock
);
2522 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
2523 head
= classhash_table
+ i
;
2524 if (list_empty(head
))
2526 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
2527 if (unlikely(class == lock
->class_cache
)) {
2528 __raw_spin_unlock(&hash_lock
);
2529 DEBUG_LOCKS_WARN_ON(1);
2534 __raw_spin_unlock(&hash_lock
);
2537 raw_local_irq_restore(flags
);
2540 void __init
lockdep_init(void)
2545 * Some architectures have their own start_kernel()
2546 * code which calls lockdep_init(), while we also
2547 * call lockdep_init() from the start_kernel() itself,
2548 * and we want to initialize the hashes only once:
2550 if (lockdep_initialized
)
2553 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
2554 INIT_LIST_HEAD(classhash_table
+ i
);
2556 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
2557 INIT_LIST_HEAD(chainhash_table
+ i
);
2559 lockdep_initialized
= 1;
2562 void __init
lockdep_info(void)
2564 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
2566 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
2567 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
2568 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
2569 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
2570 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
2571 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
2572 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
2574 printk(" memory used by lock dependency info: %lu kB\n",
2575 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
2576 sizeof(struct list_head
) * CLASSHASH_SIZE
+
2577 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
2578 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
2579 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
2581 printk(" per task-struct memory footprint: %lu bytes\n",
2582 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
2584 #ifdef CONFIG_DEBUG_LOCKDEP
2585 if (lockdep_init_error
)
2586 printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n");
2590 static inline int in_range(const void *start
, const void *addr
, const void *end
)
2592 return addr
>= start
&& addr
<= end
;
2596 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
2597 const void *mem_to
, struct held_lock
*hlock
)
2599 if (!debug_locks_off())
2601 if (debug_locks_silent
)
2604 printk("\n=========================\n");
2605 printk( "[ BUG: held lock freed! ]\n");
2606 printk( "-------------------------\n");
2607 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
2608 curr
->comm
, curr
->pid
, mem_from
, mem_to
-1);
2610 lockdep_print_held_locks(curr
);
2612 printk("\nstack backtrace:\n");
2617 * Called when kernel memory is freed (or unmapped), or if a lock
2618 * is destroyed or reinitialized - this code checks whether there is
2619 * any held lock in the memory range of <from> to <to>:
2621 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
2623 const void *mem_to
= mem_from
+ mem_len
, *lock_from
, *lock_to
;
2624 struct task_struct
*curr
= current
;
2625 struct held_lock
*hlock
;
2626 unsigned long flags
;
2629 if (unlikely(!debug_locks
))
2632 local_irq_save(flags
);
2633 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2634 hlock
= curr
->held_locks
+ i
;
2636 lock_from
= (void *)hlock
->instance
;
2637 lock_to
= (void *)(hlock
->instance
+ 1);
2639 if (!in_range(mem_from
, lock_from
, mem_to
) &&
2640 !in_range(mem_from
, lock_to
, mem_to
))
2643 print_freed_lock_bug(curr
, mem_from
, mem_to
, hlock
);
2646 local_irq_restore(flags
);
2648 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
2650 static void print_held_locks_bug(struct task_struct
*curr
)
2652 if (!debug_locks_off())
2654 if (debug_locks_silent
)
2657 printk("\n=====================================\n");
2658 printk( "[ BUG: lock held at task exit time! ]\n");
2659 printk( "-------------------------------------\n");
2660 printk("%s/%d is exiting with locks still held!\n",
2661 curr
->comm
, curr
->pid
);
2662 lockdep_print_held_locks(curr
);
2664 printk("\nstack backtrace:\n");
2668 void debug_check_no_locks_held(struct task_struct
*task
)
2670 if (unlikely(task
->lockdep_depth
> 0))
2671 print_held_locks_bug(task
);
2674 void debug_show_all_locks(void)
2676 struct task_struct
*g
, *p
;
2680 printk("\nShowing all locks held in the system:\n");
2683 * Here we try to get the tasklist_lock as hard as possible,
2684 * if not successful after 2 seconds we ignore it (but keep
2685 * trying). This is to enable a debug printout even if a
2686 * tasklist_lock-holding task deadlocks or crashes.
2689 if (!read_trylock(&tasklist_lock
)) {
2691 printk("hm, tasklist_lock locked, retrying... ");
2694 printk(" #%d", 10-count
);
2698 printk(" ignoring it.\n");
2702 printk(" locked it.\n");
2704 do_each_thread(g
, p
) {
2705 if (p
->lockdep_depth
)
2706 lockdep_print_held_locks(p
);
2708 if (read_trylock(&tasklist_lock
))
2710 } while_each_thread(g
, p
);
2713 printk("=============================================\n\n");
2716 read_unlock(&tasklist_lock
);
2719 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
2721 void debug_show_held_locks(struct task_struct
*task
)
2723 lockdep_print_held_locks(task
);
2726 EXPORT_SYMBOL_GPL(debug_show_held_locks
);