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>
40 #include <asm/sections.h>
42 #include "lockdep_internals.h"
45 * hash_lock: protects the lockdep hashes and class/list/hash allocators.
47 * This is one of the rare exceptions where it's justified
48 * to use a raw spinlock - we really dont want the spinlock
49 * code to recurse back into the lockdep code.
51 static raw_spinlock_t hash_lock
= (raw_spinlock_t
)__RAW_SPIN_LOCK_UNLOCKED
;
53 static int lockdep_initialized
;
55 unsigned long nr_list_entries
;
56 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
59 * Allocate a lockdep entry. (assumes hash_lock held, returns
60 * with NULL on failure)
62 static struct lock_list
*alloc_list_entry(void)
64 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
65 __raw_spin_unlock(&hash_lock
);
67 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
68 printk("turning off the locking correctness validator.\n");
71 return list_entries
+ nr_list_entries
++;
75 * All data structures here are protected by the global debug_lock.
77 * Mutex key structs only get allocated, once during bootup, and never
78 * get freed - this significantly simplifies the debugging code.
80 unsigned long nr_lock_classes
;
81 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
84 * We keep a global list of all lock classes. The list only grows,
85 * never shrinks. The list is only accessed with the lockdep
88 LIST_HEAD(all_lock_classes
);
91 * The lockdep classes are in a hash-table as well, for fast lookup:
93 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
94 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
95 #define CLASSHASH_MASK (CLASSHASH_SIZE - 1)
96 #define __classhashfn(key) ((((unsigned long)key >> CLASSHASH_BITS) + (unsigned long)key) & CLASSHASH_MASK)
97 #define classhashentry(key) (classhash_table + __classhashfn((key)))
99 static struct list_head classhash_table
[CLASSHASH_SIZE
];
101 unsigned long nr_lock_chains
;
102 static struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
105 * We put the lock dependency chains into a hash-table as well, to cache
108 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
109 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
110 #define CHAINHASH_MASK (CHAINHASH_SIZE - 1)
111 #define __chainhashfn(chain) \
112 (((chain >> CHAINHASH_BITS) + chain) & CHAINHASH_MASK)
113 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
115 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
118 * The hash key of the lock dependency chains is a hash itself too:
119 * it's a hash of all locks taken up to that lock, including that lock.
120 * It's a 64-bit hash, because it's important for the keys to be
123 #define iterate_chain_key(key1, key2) \
124 (((key1) << MAX_LOCKDEP_KEYS_BITS/2) ^ \
125 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS/2)) ^ \
128 void lockdep_off(void)
130 current
->lockdep_recursion
++;
133 EXPORT_SYMBOL(lockdep_off
);
135 void lockdep_on(void)
137 current
->lockdep_recursion
--;
140 EXPORT_SYMBOL(lockdep_on
);
142 int lockdep_internal(void)
144 return current
->lockdep_recursion
!= 0;
147 EXPORT_SYMBOL(lockdep_internal
);
150 * Debugging switches:
155 # define VERY_VERBOSE 0
159 # define HARDIRQ_VERBOSE 1
160 # define SOFTIRQ_VERBOSE 1
162 # define HARDIRQ_VERBOSE 0
163 # define SOFTIRQ_VERBOSE 0
166 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
168 * Quick filtering for interesting events:
170 static int class_filter(struct lock_class
*class)
174 if (class->name_version
== 1 &&
175 !strcmp(class->name
, "lockname"))
177 if (class->name_version
== 1 &&
178 !strcmp(class->name
, "&struct->lockfield"))
181 /* Allow everything else. 0 would be filter everything else */
186 static int verbose(struct lock_class
*class)
189 return class_filter(class);
194 #ifdef CONFIG_TRACE_IRQFLAGS
196 static int hardirq_verbose(struct lock_class
*class)
199 return class_filter(class);
204 static int softirq_verbose(struct lock_class
*class)
207 return class_filter(class);
215 * Stack-trace: tightly packed array of stack backtrace
216 * addresses. Protected by the hash_lock.
218 unsigned long nr_stack_trace_entries
;
219 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
221 static int save_trace(struct stack_trace
*trace
)
223 trace
->nr_entries
= 0;
224 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
225 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
228 trace
->all_contexts
= 0;
230 save_stack_trace(trace
, NULL
);
232 trace
->max_entries
= trace
->nr_entries
;
234 nr_stack_trace_entries
+= trace
->nr_entries
;
235 if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries
> MAX_STACK_TRACE_ENTRIES
))
238 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
239 __raw_spin_unlock(&hash_lock
);
240 if (debug_locks_off()) {
241 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
242 printk("turning off the locking correctness validator.\n");
251 unsigned int nr_hardirq_chains
;
252 unsigned int nr_softirq_chains
;
253 unsigned int nr_process_chains
;
254 unsigned int max_lockdep_depth
;
255 unsigned int max_recursion_depth
;
257 #ifdef CONFIG_DEBUG_LOCKDEP
259 * We cannot printk in early bootup code. Not even early_printk()
260 * might work. So we mark any initialization errors and printk
261 * about it later on, in lockdep_info().
263 static int lockdep_init_error
;
266 * Various lockdep statistics:
268 atomic_t chain_lookup_hits
;
269 atomic_t chain_lookup_misses
;
270 atomic_t hardirqs_on_events
;
271 atomic_t hardirqs_off_events
;
272 atomic_t redundant_hardirqs_on
;
273 atomic_t redundant_hardirqs_off
;
274 atomic_t softirqs_on_events
;
275 atomic_t softirqs_off_events
;
276 atomic_t redundant_softirqs_on
;
277 atomic_t redundant_softirqs_off
;
278 atomic_t nr_unused_locks
;
279 atomic_t nr_cyclic_checks
;
280 atomic_t nr_cyclic_check_recursions
;
281 atomic_t nr_find_usage_forwards_checks
;
282 atomic_t nr_find_usage_forwards_recursions
;
283 atomic_t nr_find_usage_backwards_checks
;
284 atomic_t nr_find_usage_backwards_recursions
;
285 # define debug_atomic_inc(ptr) atomic_inc(ptr)
286 # define debug_atomic_dec(ptr) atomic_dec(ptr)
287 # define debug_atomic_read(ptr) atomic_read(ptr)
289 # define debug_atomic_inc(ptr) do { } while (0)
290 # define debug_atomic_dec(ptr) do { } while (0)
291 # define debug_atomic_read(ptr) 0
298 static const char *usage_str
[] =
300 [LOCK_USED
] = "initial-use ",
301 [LOCK_USED_IN_HARDIRQ
] = "in-hardirq-W",
302 [LOCK_USED_IN_SOFTIRQ
] = "in-softirq-W",
303 [LOCK_ENABLED_SOFTIRQS
] = "softirq-on-W",
304 [LOCK_ENABLED_HARDIRQS
] = "hardirq-on-W",
305 [LOCK_USED_IN_HARDIRQ_READ
] = "in-hardirq-R",
306 [LOCK_USED_IN_SOFTIRQ_READ
] = "in-softirq-R",
307 [LOCK_ENABLED_SOFTIRQS_READ
] = "softirq-on-R",
308 [LOCK_ENABLED_HARDIRQS_READ
] = "hardirq-on-R",
311 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
313 unsigned long offs
, size
;
316 return kallsyms_lookup((unsigned long)key
, &size
, &offs
, &modname
, str
);
320 get_usage_chars(struct lock_class
*class, char *c1
, char *c2
, char *c3
, char *c4
)
322 *c1
= '.', *c2
= '.', *c3
= '.', *c4
= '.';
324 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ
)
327 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS
)
330 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ
)
333 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS
)
336 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
338 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ_READ
) {
340 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
344 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
346 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ_READ
) {
348 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
353 static void print_lock_name(struct lock_class
*class)
355 char str
[128], c1
, c2
, c3
, c4
;
358 get_usage_chars(class, &c1
, &c2
, &c3
, &c4
);
362 name
= __get_key_name(class->key
, str
);
363 printk(" (%s", name
);
365 printk(" (%s", name
);
366 if (class->name_version
> 1)
367 printk("#%d", class->name_version
);
369 printk("/%d", class->subclass
);
371 printk("){%c%c%c%c}", c1
, c2
, c3
, c4
);
374 static void print_lockdep_cache(struct lockdep_map
*lock
)
381 name
= __get_key_name(lock
->key
->subkeys
, str
);
386 static void print_lock(struct held_lock
*hlock
)
388 print_lock_name(hlock
->class);
390 print_ip_sym(hlock
->acquire_ip
);
393 static void lockdep_print_held_locks(struct task_struct
*curr
)
395 int i
, depth
= curr
->lockdep_depth
;
398 printk("no locks held by %s/%d.\n", curr
->comm
, curr
->pid
);
401 printk("%d lock%s held by %s/%d:\n",
402 depth
, depth
> 1 ? "s" : "", curr
->comm
, curr
->pid
);
404 for (i
= 0; i
< depth
; i
++) {
406 print_lock(curr
->held_locks
+ i
);
410 static void print_lock_class_header(struct lock_class
*class, int depth
)
414 printk("%*s->", depth
, "");
415 print_lock_name(class);
416 printk(" ops: %lu", class->ops
);
419 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
420 if (class->usage_mask
& (1 << bit
)) {
423 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
424 len
+= printk(" at:\n");
425 print_stack_trace(class->usage_traces
+ bit
, len
);
428 printk("%*s }\n", depth
, "");
430 printk("%*s ... key at: ",depth
,"");
431 print_ip_sym((unsigned long)class->key
);
435 * printk all lock dependencies starting at <entry>:
437 static void print_lock_dependencies(struct lock_class
*class, int depth
)
439 struct lock_list
*entry
;
441 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
444 print_lock_class_header(class, depth
);
446 list_for_each_entry(entry
, &class->locks_after
, entry
) {
447 DEBUG_LOCKS_WARN_ON(!entry
->class);
448 print_lock_dependencies(entry
->class, depth
+ 1);
450 printk("%*s ... acquired at:\n",depth
,"");
451 print_stack_trace(&entry
->trace
, 2);
457 * Add a new dependency to the head of the list:
459 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
460 struct list_head
*head
, unsigned long ip
)
462 struct lock_list
*entry
;
464 * Lock not present yet - get a new dependency struct and
465 * add it to the list:
467 entry
= alloc_list_entry();
472 save_trace(&entry
->trace
);
475 * Since we never remove from the dependency list, the list can
476 * be walked lockless by other CPUs, it's only allocation
477 * that must be protected by the spinlock. But this also means
478 * we must make new entries visible only once writes to the
479 * entry become visible - hence the RCU op:
481 list_add_tail_rcu(&entry
->entry
, head
);
487 * Recursive, forwards-direction lock-dependency checking, used for
488 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
491 * (to keep the stackframe of the recursive functions small we
492 * use these global variables, and we also mark various helper
493 * functions as noinline.)
495 static struct held_lock
*check_source
, *check_target
;
498 * Print a dependency chain entry (this is only done when a deadlock
499 * has been detected):
502 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
504 if (debug_locks_silent
)
506 printk("\n-> #%u", depth
);
507 print_lock_name(target
->class);
509 print_stack_trace(&target
->trace
, 6);
515 * When a circular dependency is detected, print the
519 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
)
521 struct task_struct
*curr
= current
;
523 __raw_spin_unlock(&hash_lock
);
525 if (debug_locks_silent
)
528 printk("\n=======================================================\n");
529 printk( "[ INFO: possible circular locking dependency detected ]\n");
530 printk( "-------------------------------------------------------\n");
531 printk("%s/%d is trying to acquire lock:\n",
532 curr
->comm
, curr
->pid
);
533 print_lock(check_source
);
534 printk("\nbut task is already holding lock:\n");
535 print_lock(check_target
);
536 printk("\nwhich lock already depends on the new lock.\n\n");
537 printk("\nthe existing dependency chain (in reverse order) is:\n");
539 print_circular_bug_entry(entry
, depth
);
544 static noinline
int print_circular_bug_tail(void)
546 struct task_struct
*curr
= current
;
547 struct lock_list
this;
549 if (debug_locks_silent
)
552 this.class = check_source
->class;
553 save_trace(&this.trace
);
554 print_circular_bug_entry(&this, 0);
556 printk("\nother info that might help us debug this:\n\n");
557 lockdep_print_held_locks(curr
);
559 printk("\nstack backtrace:\n");
565 static int noinline
print_infinite_recursion_bug(void)
567 __raw_spin_unlock(&hash_lock
);
568 DEBUG_LOCKS_WARN_ON(1);
574 * Prove that the dependency graph starting at <entry> can not
575 * lead to <target>. Print an error and return 0 if it does.
578 check_noncircular(struct lock_class
*source
, unsigned int depth
)
580 struct lock_list
*entry
;
582 debug_atomic_inc(&nr_cyclic_check_recursions
);
583 if (depth
> max_recursion_depth
)
584 max_recursion_depth
= depth
;
586 return print_infinite_recursion_bug();
588 * Check this lock's dependency list:
590 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
591 if (entry
->class == check_target
->class)
592 return print_circular_bug_header(entry
, depth
+1);
593 debug_atomic_inc(&nr_cyclic_checks
);
594 if (!check_noncircular(entry
->class, depth
+1))
595 return print_circular_bug_entry(entry
, depth
+1);
600 static int very_verbose(struct lock_class
*class)
603 return class_filter(class);
607 #ifdef CONFIG_TRACE_IRQFLAGS
610 * Forwards and backwards subgraph searching, for the purposes of
611 * proving that two subgraphs can be connected by a new dependency
612 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
614 static enum lock_usage_bit find_usage_bit
;
615 static struct lock_class
*forwards_match
, *backwards_match
;
618 * Find a node in the forwards-direction dependency sub-graph starting
619 * at <source> that matches <find_usage_bit>.
621 * Return 2 if such a node exists in the subgraph, and put that node
622 * into <forwards_match>.
624 * Return 1 otherwise and keep <forwards_match> unchanged.
628 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
630 struct lock_list
*entry
;
633 if (depth
> max_recursion_depth
)
634 max_recursion_depth
= depth
;
636 return print_infinite_recursion_bug();
638 debug_atomic_inc(&nr_find_usage_forwards_checks
);
639 if (source
->usage_mask
& (1 << find_usage_bit
)) {
640 forwards_match
= source
;
645 * Check this lock's dependency list:
647 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
648 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
649 ret
= find_usage_forwards(entry
->class, depth
+1);
650 if (ret
== 2 || ret
== 0)
657 * Find a node in the backwards-direction dependency sub-graph starting
658 * at <source> that matches <find_usage_bit>.
660 * Return 2 if such a node exists in the subgraph, and put that node
661 * into <backwards_match>.
663 * Return 1 otherwise and keep <backwards_match> unchanged.
667 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
669 struct lock_list
*entry
;
672 if (depth
> max_recursion_depth
)
673 max_recursion_depth
= depth
;
675 return print_infinite_recursion_bug();
677 debug_atomic_inc(&nr_find_usage_backwards_checks
);
678 if (source
->usage_mask
& (1 << find_usage_bit
)) {
679 backwards_match
= source
;
684 * Check this lock's dependency list:
686 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
687 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
688 ret
= find_usage_backwards(entry
->class, depth
+1);
689 if (ret
== 2 || ret
== 0)
696 print_bad_irq_dependency(struct task_struct
*curr
,
697 struct held_lock
*prev
,
698 struct held_lock
*next
,
699 enum lock_usage_bit bit1
,
700 enum lock_usage_bit bit2
,
701 const char *irqclass
)
703 __raw_spin_unlock(&hash_lock
);
705 if (debug_locks_silent
)
708 printk("\n======================================================\n");
709 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
711 printk( "------------------------------------------------------\n");
712 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
713 curr
->comm
, curr
->pid
,
714 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
715 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
716 curr
->hardirqs_enabled
,
717 curr
->softirqs_enabled
);
720 printk("\nand this task is already holding:\n");
722 printk("which would create a new lock dependency:\n");
723 print_lock_name(prev
->class);
725 print_lock_name(next
->class);
728 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
730 print_lock_name(backwards_match
);
731 printk("\n... which became %s-irq-safe at:\n", irqclass
);
733 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
735 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
736 print_lock_name(forwards_match
);
737 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
740 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
742 printk("\nother info that might help us debug this:\n\n");
743 lockdep_print_held_locks(curr
);
745 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
746 print_lock_dependencies(backwards_match
, 0);
748 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
749 print_lock_dependencies(forwards_match
, 0);
751 printk("\nstack backtrace:\n");
758 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
759 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
760 enum lock_usage_bit bit_forwards
, const char *irqclass
)
764 find_usage_bit
= bit_backwards
;
765 /* fills in <backwards_match> */
766 ret
= find_usage_backwards(prev
->class, 0);
767 if (!ret
|| ret
== 1)
770 find_usage_bit
= bit_forwards
;
771 ret
= find_usage_forwards(next
->class, 0);
772 if (!ret
|| ret
== 1)
775 return print_bad_irq_dependency(curr
, prev
, next
,
776 bit_backwards
, bit_forwards
, irqclass
);
782 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
783 struct held_lock
*next
)
786 __raw_spin_unlock(&hash_lock
);
787 if (debug_locks_silent
)
790 printk("\n=============================================\n");
791 printk( "[ INFO: possible recursive locking detected ]\n");
792 printk( "---------------------------------------------\n");
793 printk("%s/%d is trying to acquire lock:\n",
794 curr
->comm
, curr
->pid
);
796 printk("\nbut task is already holding lock:\n");
799 printk("\nother info that might help us debug this:\n");
800 lockdep_print_held_locks(curr
);
802 printk("\nstack backtrace:\n");
809 * Check whether we are holding such a class already.
811 * (Note that this has to be done separately, because the graph cannot
812 * detect such classes of deadlocks.)
814 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
817 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
818 struct lockdep_map
*next_instance
, int read
)
820 struct held_lock
*prev
;
823 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
824 prev
= curr
->held_locks
+ i
;
825 if (prev
->class != next
->class)
828 * Allow read-after-read recursion of the same
829 * lock class (i.e. read_lock(lock)+read_lock(lock)):
831 if ((read
== 2) && prev
->read
)
833 return print_deadlock_bug(curr
, prev
, next
);
839 * There was a chain-cache miss, and we are about to add a new dependency
840 * to a previous lock. We recursively validate the following rules:
842 * - would the adding of the <prev> -> <next> dependency create a
843 * circular dependency in the graph? [== circular deadlock]
845 * - does the new prev->next dependency connect any hardirq-safe lock
846 * (in the full backwards-subgraph starting at <prev>) with any
847 * hardirq-unsafe lock (in the full forwards-subgraph starting at
848 * <next>)? [== illegal lock inversion with hardirq contexts]
850 * - does the new prev->next dependency connect any softirq-safe lock
851 * (in the full backwards-subgraph starting at <prev>) with any
852 * softirq-unsafe lock (in the full forwards-subgraph starting at
853 * <next>)? [== illegal lock inversion with softirq contexts]
855 * any of these scenarios could lead to a deadlock.
857 * Then if all the validations pass, we add the forwards and backwards
861 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
862 struct held_lock
*next
)
864 struct lock_list
*entry
;
868 * Prove that the new <prev> -> <next> dependency would not
869 * create a circular dependency in the graph. (We do this by
870 * forward-recursing into the graph starting at <next>, and
871 * checking whether we can reach <prev>.)
873 * We are using global variables to control the recursion, to
874 * keep the stackframe size of the recursive functions low:
878 if (!(check_noncircular(next
->class, 0)))
879 return print_circular_bug_tail();
881 #ifdef CONFIG_TRACE_IRQFLAGS
883 * Prove that the new dependency does not connect a hardirq-safe
884 * lock with a hardirq-unsafe lock - to achieve this we search
885 * the backwards-subgraph starting at <prev>, and the
886 * forwards-subgraph starting at <next>:
888 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ
,
889 LOCK_ENABLED_HARDIRQS
, "hard"))
893 * Prove that the new dependency does not connect a hardirq-safe-read
894 * lock with a hardirq-unsafe lock - to achieve this we search
895 * the backwards-subgraph starting at <prev>, and the
896 * forwards-subgraph starting at <next>:
898 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ_READ
,
899 LOCK_ENABLED_HARDIRQS
, "hard-read"))
903 * Prove that the new dependency does not connect a softirq-safe
904 * lock with a softirq-unsafe lock - to achieve this we search
905 * the backwards-subgraph starting at <prev>, and the
906 * forwards-subgraph starting at <next>:
908 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ
,
909 LOCK_ENABLED_SOFTIRQS
, "soft"))
912 * Prove that the new dependency does not connect a softirq-safe-read
913 * lock with a softirq-unsafe lock - to achieve this we search
914 * the backwards-subgraph starting at <prev>, and the
915 * forwards-subgraph starting at <next>:
917 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ_READ
,
918 LOCK_ENABLED_SOFTIRQS
, "soft"))
922 * For recursive read-locks we do all the dependency checks,
923 * but we dont store read-triggered dependencies (only
924 * write-triggered dependencies). This ensures that only the
925 * write-side dependencies matter, and that if for example a
926 * write-lock never takes any other locks, then the reads are
927 * equivalent to a NOP.
929 if (next
->read
== 2 || prev
->read
== 2)
932 * Is the <prev> -> <next> dependency already present?
934 * (this may occur even though this is a new chain: consider
935 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
936 * chains - the second one will be new, but L1 already has
937 * L2 added to its dependency list, due to the first chain.)
939 list_for_each_entry(entry
, &prev
->class->locks_after
, entry
) {
940 if (entry
->class == next
->class)
945 * Ok, all validations passed, add the new lock
946 * to the previous lock's dependency list:
948 ret
= add_lock_to_list(prev
->class, next
->class,
949 &prev
->class->locks_after
, next
->acquire_ip
);
953 * Return value of 2 signals 'dependency already added',
954 * in that case we dont have to add the backlink either.
958 ret
= add_lock_to_list(next
->class, prev
->class,
959 &next
->class->locks_before
, next
->acquire_ip
);
962 * Debugging printouts:
964 if (verbose(prev
->class) || verbose(next
->class)) {
965 __raw_spin_unlock(&hash_lock
);
966 printk("\n new dependency: ");
967 print_lock_name(prev
->class);
969 print_lock_name(next
->class);
972 __raw_spin_lock(&hash_lock
);
978 * Add the dependency to all directly-previous locks that are 'relevant'.
979 * The ones that are relevant are (in increasing distance from curr):
980 * all consecutive trylock entries and the final non-trylock entry - or
981 * the end of this context's lock-chain - whichever comes first.
984 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
986 int depth
= curr
->lockdep_depth
;
987 struct held_lock
*hlock
;
992 * Depth must not be zero for a non-head lock:
997 * At least two relevant locks must exist for this
1000 if (curr
->held_locks
[depth
].irq_context
!=
1001 curr
->held_locks
[depth
-1].irq_context
)
1005 hlock
= curr
->held_locks
+ depth
-1;
1007 * Only non-recursive-read entries get new dependencies
1010 if (hlock
->read
!= 2) {
1011 check_prev_add(curr
, hlock
, next
);
1013 * Stop after the first non-trylock entry,
1014 * as non-trylock entries have added their
1015 * own direct dependencies already, so this
1016 * lock is connected to them indirectly:
1018 if (!hlock
->trylock
)
1023 * End of lock-stack?
1028 * Stop the search if we cross into another context:
1030 if (curr
->held_locks
[depth
].irq_context
!=
1031 curr
->held_locks
[depth
-1].irq_context
)
1036 __raw_spin_unlock(&hash_lock
);
1037 DEBUG_LOCKS_WARN_ON(1);
1044 * Is this the address of a static object:
1046 static int static_obj(void *obj
)
1048 unsigned long start
= (unsigned long) &_stext
,
1049 end
= (unsigned long) &_end
,
1050 addr
= (unsigned long) obj
;
1058 if ((addr
>= start
) && (addr
< end
))
1065 for_each_possible_cpu(i
) {
1066 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
1067 end
= (unsigned long) &__per_cpu_end
+ per_cpu_offset(i
);
1069 if ((addr
>= start
) && (addr
< end
))
1077 return is_module_address(addr
);
1081 * To make lock name printouts unique, we calculate a unique
1082 * class->name_version generation counter:
1084 static int count_matching_names(struct lock_class
*new_class
)
1086 struct lock_class
*class;
1089 if (!new_class
->name
)
1092 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
1093 if (new_class
->key
- new_class
->subclass
== class->key
)
1094 return class->name_version
;
1095 if (class->name
&& !strcmp(class->name
, new_class
->name
))
1096 count
= max(count
, class->name_version
);
1102 extern void __error_too_big_MAX_LOCKDEP_SUBCLASSES(void);
1105 * Register a lock's class in the hash-table, if the class is not present
1106 * yet. Otherwise we look it up. We cache the result in the lock object
1107 * itself, so actual lookup of the hash should be once per lock object.
1109 static inline struct lock_class
*
1110 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
1112 struct lockdep_subclass_key
*key
;
1113 struct list_head
*hash_head
;
1114 struct lock_class
*class;
1116 #ifdef CONFIG_DEBUG_LOCKDEP
1118 * If the architecture calls into lockdep before initializing
1119 * the hashes then we'll warn about it later. (we cannot printk
1122 if (unlikely(!lockdep_initialized
)) {
1124 lockdep_init_error
= 1;
1129 * Static locks do not have their class-keys yet - for them the key
1130 * is the lock object itself:
1132 if (unlikely(!lock
->key
))
1133 lock
->key
= (void *)lock
;
1136 * NOTE: the class-key must be unique. For dynamic locks, a static
1137 * lock_class_key variable is passed in through the mutex_init()
1138 * (or spin_lock_init()) call - which acts as the key. For static
1139 * locks we use the lock object itself as the key.
1141 if (sizeof(struct lock_class_key
) > sizeof(struct lock_class
))
1142 __error_too_big_MAX_LOCKDEP_SUBCLASSES();
1144 key
= lock
->key
->subkeys
+ subclass
;
1146 hash_head
= classhashentry(key
);
1149 * We can walk the hash lockfree, because the hash only
1150 * grows, and we are careful when adding entries to the end:
1152 list_for_each_entry(class, hash_head
, hash_entry
)
1153 if (class->key
== key
)
1160 * Register a lock's class in the hash-table, if the class is not present
1161 * yet. Otherwise we look it up. We cache the result in the lock object
1162 * itself, so actual lookup of the hash should be once per lock object.
1164 static inline struct lock_class
*
1165 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
1167 struct lockdep_subclass_key
*key
;
1168 struct list_head
*hash_head
;
1169 struct lock_class
*class;
1171 class = look_up_lock_class(lock
, subclass
);
1176 * Debug-check: all keys must be persistent!
1178 if (!static_obj(lock
->key
)) {
1180 printk("INFO: trying to register non-static key.\n");
1181 printk("the code is fine but needs lockdep annotation.\n");
1182 printk("turning off the locking correctness validator.\n");
1188 key
= lock
->key
->subkeys
+ subclass
;
1189 hash_head
= classhashentry(key
);
1191 __raw_spin_lock(&hash_lock
);
1193 * We have to do the hash-walk again, to avoid races
1196 list_for_each_entry(class, hash_head
, hash_entry
)
1197 if (class->key
== key
)
1198 goto out_unlock_set
;
1200 * Allocate a new key from the static array, and add it to
1203 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
1204 __raw_spin_unlock(&hash_lock
);
1206 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
1207 printk("turning off the locking correctness validator.\n");
1210 class = lock_classes
+ nr_lock_classes
++;
1211 debug_atomic_inc(&nr_unused_locks
);
1213 class->name
= lock
->name
;
1214 class->subclass
= subclass
;
1215 INIT_LIST_HEAD(&class->lock_entry
);
1216 INIT_LIST_HEAD(&class->locks_before
);
1217 INIT_LIST_HEAD(&class->locks_after
);
1218 class->name_version
= count_matching_names(class);
1220 * We use RCU's safe list-add method to make
1221 * parallel walking of the hash-list safe:
1223 list_add_tail_rcu(&class->hash_entry
, hash_head
);
1225 if (verbose(class)) {
1226 __raw_spin_unlock(&hash_lock
);
1227 printk("\nnew class %p: %s", class->key
, class->name
);
1228 if (class->name_version
> 1)
1229 printk("#%d", class->name_version
);
1232 __raw_spin_lock(&hash_lock
);
1235 __raw_spin_unlock(&hash_lock
);
1238 lock
->class_cache
= class;
1240 DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
);
1246 * Look up a dependency chain. If the key is not present yet then
1247 * add it and return 0 - in this case the new dependency chain is
1248 * validated. If the key is already hashed, return 1.
1250 static inline int lookup_chain_cache(u64 chain_key
)
1252 struct list_head
*hash_head
= chainhashentry(chain_key
);
1253 struct lock_chain
*chain
;
1255 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1257 * We can walk it lock-free, because entries only get added
1260 list_for_each_entry(chain
, hash_head
, entry
) {
1261 if (chain
->chain_key
== chain_key
) {
1263 debug_atomic_inc(&chain_lookup_hits
);
1265 * In the debugging case, force redundant checking
1268 #ifdef CONFIG_DEBUG_LOCKDEP
1269 __raw_spin_lock(&hash_lock
);
1276 * Allocate a new chain entry from the static array, and add
1279 __raw_spin_lock(&hash_lock
);
1281 * We have to walk the chain again locked - to avoid duplicates:
1283 list_for_each_entry(chain
, hash_head
, entry
) {
1284 if (chain
->chain_key
== chain_key
) {
1285 __raw_spin_unlock(&hash_lock
);
1289 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1290 __raw_spin_unlock(&hash_lock
);
1292 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1293 printk("turning off the locking correctness validator.\n");
1296 chain
= lock_chains
+ nr_lock_chains
++;
1297 chain
->chain_key
= chain_key
;
1298 list_add_tail_rcu(&chain
->entry
, hash_head
);
1299 debug_atomic_inc(&chain_lookup_misses
);
1300 #ifdef CONFIG_TRACE_IRQFLAGS
1301 if (current
->hardirq_context
)
1302 nr_hardirq_chains
++;
1304 if (current
->softirq_context
)
1305 nr_softirq_chains
++;
1307 nr_process_chains
++;
1310 nr_process_chains
++;
1317 * We are building curr_chain_key incrementally, so double-check
1318 * it from scratch, to make sure that it's done correctly:
1320 static void check_chain_key(struct task_struct
*curr
)
1322 #ifdef CONFIG_DEBUG_LOCKDEP
1323 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1327 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1328 hlock
= curr
->held_locks
+ i
;
1329 if (chain_key
!= hlock
->prev_chain_key
) {
1331 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1332 curr
->lockdep_depth
, i
,
1333 (unsigned long long)chain_key
,
1334 (unsigned long long)hlock
->prev_chain_key
);
1338 id
= hlock
->class - lock_classes
;
1339 DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
);
1340 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1341 hlock
->irq_context
))
1343 chain_key
= iterate_chain_key(chain_key
, id
);
1346 if (chain_key
!= curr
->curr_chain_key
) {
1348 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1349 curr
->lockdep_depth
, i
,
1350 (unsigned long long)chain_key
,
1351 (unsigned long long)curr
->curr_chain_key
);
1357 #ifdef CONFIG_TRACE_IRQFLAGS
1360 * print irq inversion bug:
1363 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
1364 struct held_lock
*this, int forwards
,
1365 const char *irqclass
)
1367 __raw_spin_unlock(&hash_lock
);
1369 if (debug_locks_silent
)
1372 printk("\n=========================================================\n");
1373 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1374 printk( "---------------------------------------------------------\n");
1375 printk("%s/%d just changed the state of lock:\n",
1376 curr
->comm
, curr
->pid
);
1379 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass
);
1381 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass
);
1382 print_lock_name(other
);
1383 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1385 printk("\nother info that might help us debug this:\n");
1386 lockdep_print_held_locks(curr
);
1388 printk("\nthe first lock's dependencies:\n");
1389 print_lock_dependencies(this->class, 0);
1391 printk("\nthe second lock's dependencies:\n");
1392 print_lock_dependencies(other
, 0);
1394 printk("\nstack backtrace:\n");
1401 * Prove that in the forwards-direction subgraph starting at <this>
1402 * there is no lock matching <mask>:
1405 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
1406 enum lock_usage_bit bit
, const char *irqclass
)
1410 find_usage_bit
= bit
;
1411 /* fills in <forwards_match> */
1412 ret
= find_usage_forwards(this->class, 0);
1413 if (!ret
|| ret
== 1)
1416 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
1420 * Prove that in the backwards-direction subgraph starting at <this>
1421 * there is no lock matching <mask>:
1424 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
1425 enum lock_usage_bit bit
, const char *irqclass
)
1429 find_usage_bit
= bit
;
1430 /* fills in <backwards_match> */
1431 ret
= find_usage_backwards(this->class, 0);
1432 if (!ret
|| ret
== 1)
1435 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
1438 static inline void print_irqtrace_events(struct task_struct
*curr
)
1440 printk("irq event stamp: %u\n", curr
->irq_events
);
1441 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
1442 print_ip_sym(curr
->hardirq_enable_ip
);
1443 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
1444 print_ip_sym(curr
->hardirq_disable_ip
);
1445 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
1446 print_ip_sym(curr
->softirq_enable_ip
);
1447 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
1448 print_ip_sym(curr
->softirq_disable_ip
);
1452 static inline void print_irqtrace_events(struct task_struct
*curr
)
1458 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1459 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1461 __raw_spin_unlock(&hash_lock
);
1463 if (debug_locks_silent
)
1466 printk("\n=================================\n");
1467 printk( "[ INFO: inconsistent lock state ]\n");
1468 printk( "---------------------------------\n");
1470 printk("inconsistent {%s} -> {%s} usage.\n",
1471 usage_str
[prev_bit
], usage_str
[new_bit
]);
1473 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1474 curr
->comm
, curr
->pid
,
1475 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1476 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1477 trace_hardirqs_enabled(curr
),
1478 trace_softirqs_enabled(curr
));
1481 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1482 print_stack_trace(this->class->usage_traces
+ prev_bit
, 1);
1484 print_irqtrace_events(curr
);
1485 printk("\nother info that might help us debug this:\n");
1486 lockdep_print_held_locks(curr
);
1488 printk("\nstack backtrace:\n");
1495 * Print out an error if an invalid bit is set:
1498 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1499 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1501 if (unlikely(this->class->usage_mask
& (1 << bad_bit
)))
1502 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1506 #define STRICT_READ_CHECKS 1
1509 * Mark a lock with a usage bit, and validate the state transition:
1511 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1512 enum lock_usage_bit new_bit
, unsigned long ip
)
1514 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
1517 * If already set then do not dirty the cacheline,
1518 * nor do any checks:
1520 if (likely(this->class->usage_mask
& new_mask
))
1523 __raw_spin_lock(&hash_lock
);
1525 * Make sure we didnt race:
1527 if (unlikely(this->class->usage_mask
& new_mask
)) {
1528 __raw_spin_unlock(&hash_lock
);
1532 this->class->usage_mask
|= new_mask
;
1534 #ifdef CONFIG_TRACE_IRQFLAGS
1535 if (new_bit
== LOCK_ENABLED_HARDIRQS
||
1536 new_bit
== LOCK_ENABLED_HARDIRQS_READ
)
1537 ip
= curr
->hardirq_enable_ip
;
1538 else if (new_bit
== LOCK_ENABLED_SOFTIRQS
||
1539 new_bit
== LOCK_ENABLED_SOFTIRQS_READ
)
1540 ip
= curr
->softirq_enable_ip
;
1542 if (!save_trace(this->class->usage_traces
+ new_bit
))
1546 #ifdef CONFIG_TRACE_IRQFLAGS
1547 case LOCK_USED_IN_HARDIRQ
:
1548 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1550 if (!valid_state(curr
, this, new_bit
,
1551 LOCK_ENABLED_HARDIRQS_READ
))
1554 * just marked it hardirq-safe, check that this lock
1555 * took no hardirq-unsafe lock in the past:
1557 if (!check_usage_forwards(curr
, this,
1558 LOCK_ENABLED_HARDIRQS
, "hard"))
1560 #if STRICT_READ_CHECKS
1562 * just marked it hardirq-safe, check that this lock
1563 * took no hardirq-unsafe-read lock in the past:
1565 if (!check_usage_forwards(curr
, this,
1566 LOCK_ENABLED_HARDIRQS_READ
, "hard-read"))
1569 if (hardirq_verbose(this->class))
1572 case LOCK_USED_IN_SOFTIRQ
:
1573 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1575 if (!valid_state(curr
, this, new_bit
,
1576 LOCK_ENABLED_SOFTIRQS_READ
))
1579 * just marked it softirq-safe, check that this lock
1580 * took no softirq-unsafe lock in the past:
1582 if (!check_usage_forwards(curr
, this,
1583 LOCK_ENABLED_SOFTIRQS
, "soft"))
1585 #if STRICT_READ_CHECKS
1587 * just marked it softirq-safe, check that this lock
1588 * took no softirq-unsafe-read lock in the past:
1590 if (!check_usage_forwards(curr
, this,
1591 LOCK_ENABLED_SOFTIRQS_READ
, "soft-read"))
1594 if (softirq_verbose(this->class))
1597 case LOCK_USED_IN_HARDIRQ_READ
:
1598 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1601 * just marked it hardirq-read-safe, check that this lock
1602 * took no hardirq-unsafe lock in the past:
1604 if (!check_usage_forwards(curr
, this,
1605 LOCK_ENABLED_HARDIRQS
, "hard"))
1607 if (hardirq_verbose(this->class))
1610 case LOCK_USED_IN_SOFTIRQ_READ
:
1611 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1614 * just marked it softirq-read-safe, check that this lock
1615 * took no softirq-unsafe lock in the past:
1617 if (!check_usage_forwards(curr
, this,
1618 LOCK_ENABLED_SOFTIRQS
, "soft"))
1620 if (softirq_verbose(this->class))
1623 case LOCK_ENABLED_HARDIRQS
:
1624 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1626 if (!valid_state(curr
, this, new_bit
,
1627 LOCK_USED_IN_HARDIRQ_READ
))
1630 * just marked it hardirq-unsafe, check that no hardirq-safe
1631 * lock in the system ever took it in the past:
1633 if (!check_usage_backwards(curr
, this,
1634 LOCK_USED_IN_HARDIRQ
, "hard"))
1636 #if STRICT_READ_CHECKS
1638 * just marked it hardirq-unsafe, check that no
1639 * hardirq-safe-read lock in the system ever took
1642 if (!check_usage_backwards(curr
, this,
1643 LOCK_USED_IN_HARDIRQ_READ
, "hard-read"))
1646 if (hardirq_verbose(this->class))
1649 case LOCK_ENABLED_SOFTIRQS
:
1650 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1652 if (!valid_state(curr
, this, new_bit
,
1653 LOCK_USED_IN_SOFTIRQ_READ
))
1656 * just marked it softirq-unsafe, check that no softirq-safe
1657 * lock in the system ever took it in the past:
1659 if (!check_usage_backwards(curr
, this,
1660 LOCK_USED_IN_SOFTIRQ
, "soft"))
1662 #if STRICT_READ_CHECKS
1664 * just marked it softirq-unsafe, check that no
1665 * softirq-safe-read lock in the system ever took
1668 if (!check_usage_backwards(curr
, this,
1669 LOCK_USED_IN_SOFTIRQ_READ
, "soft-read"))
1672 if (softirq_verbose(this->class))
1675 case LOCK_ENABLED_HARDIRQS_READ
:
1676 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1678 #if STRICT_READ_CHECKS
1680 * just marked it hardirq-read-unsafe, check that no
1681 * hardirq-safe lock in the system ever took it in the past:
1683 if (!check_usage_backwards(curr
, this,
1684 LOCK_USED_IN_HARDIRQ
, "hard"))
1687 if (hardirq_verbose(this->class))
1690 case LOCK_ENABLED_SOFTIRQS_READ
:
1691 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1693 #if STRICT_READ_CHECKS
1695 * just marked it softirq-read-unsafe, check that no
1696 * softirq-safe lock in the system ever took it in the past:
1698 if (!check_usage_backwards(curr
, this,
1699 LOCK_USED_IN_SOFTIRQ
, "soft"))
1702 if (softirq_verbose(this->class))
1708 * Add it to the global list of classes:
1710 list_add_tail_rcu(&this->class->lock_entry
, &all_lock_classes
);
1711 debug_atomic_dec(&nr_unused_locks
);
1719 __raw_spin_unlock(&hash_lock
);
1722 * We must printk outside of the hash_lock:
1725 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
1727 print_irqtrace_events(curr
);
1734 #ifdef CONFIG_TRACE_IRQFLAGS
1736 * Mark all held locks with a usage bit:
1739 mark_held_locks(struct task_struct
*curr
, int hardirq
, unsigned long ip
)
1741 enum lock_usage_bit usage_bit
;
1742 struct held_lock
*hlock
;
1745 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1746 hlock
= curr
->held_locks
+ i
;
1750 usage_bit
= LOCK_ENABLED_HARDIRQS_READ
;
1752 usage_bit
= LOCK_ENABLED_HARDIRQS
;
1755 usage_bit
= LOCK_ENABLED_SOFTIRQS_READ
;
1757 usage_bit
= LOCK_ENABLED_SOFTIRQS
;
1759 if (!mark_lock(curr
, hlock
, usage_bit
, ip
))
1767 * Debugging helper: via this flag we know that we are in
1768 * 'early bootup code', and will warn about any invalid irqs-on event:
1770 static int early_boot_irqs_enabled
;
1772 void early_boot_irqs_off(void)
1774 early_boot_irqs_enabled
= 0;
1777 void early_boot_irqs_on(void)
1779 early_boot_irqs_enabled
= 1;
1783 * Hardirqs will be enabled:
1785 void trace_hardirqs_on(void)
1787 struct task_struct
*curr
= current
;
1790 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
1793 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
1796 if (unlikely(curr
->hardirqs_enabled
)) {
1797 debug_atomic_inc(&redundant_hardirqs_on
);
1800 /* we'll do an OFF -> ON transition: */
1801 curr
->hardirqs_enabled
= 1;
1802 ip
= (unsigned long) __builtin_return_address(0);
1804 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1806 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
1809 * We are going to turn hardirqs on, so set the
1810 * usage bit for all held locks:
1812 if (!mark_held_locks(curr
, 1, ip
))
1815 * If we have softirqs enabled, then set the usage
1816 * bit for all held locks. (disabled hardirqs prevented
1817 * this bit from being set before)
1819 if (curr
->softirqs_enabled
)
1820 if (!mark_held_locks(curr
, 0, ip
))
1823 curr
->hardirq_enable_ip
= ip
;
1824 curr
->hardirq_enable_event
= ++curr
->irq_events
;
1825 debug_atomic_inc(&hardirqs_on_events
);
1828 EXPORT_SYMBOL(trace_hardirqs_on
);
1831 * Hardirqs were disabled:
1833 void trace_hardirqs_off(void)
1835 struct task_struct
*curr
= current
;
1837 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
1840 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1843 if (curr
->hardirqs_enabled
) {
1845 * We have done an ON -> OFF transition:
1847 curr
->hardirqs_enabled
= 0;
1848 curr
->hardirq_disable_ip
= _RET_IP_
;
1849 curr
->hardirq_disable_event
= ++curr
->irq_events
;
1850 debug_atomic_inc(&hardirqs_off_events
);
1852 debug_atomic_inc(&redundant_hardirqs_off
);
1855 EXPORT_SYMBOL(trace_hardirqs_off
);
1858 * Softirqs will be enabled:
1860 void trace_softirqs_on(unsigned long ip
)
1862 struct task_struct
*curr
= current
;
1864 if (unlikely(!debug_locks
))
1867 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1870 if (curr
->softirqs_enabled
) {
1871 debug_atomic_inc(&redundant_softirqs_on
);
1876 * We'll do an OFF -> ON transition:
1878 curr
->softirqs_enabled
= 1;
1879 curr
->softirq_enable_ip
= ip
;
1880 curr
->softirq_enable_event
= ++curr
->irq_events
;
1881 debug_atomic_inc(&softirqs_on_events
);
1883 * We are going to turn softirqs on, so set the
1884 * usage bit for all held locks, if hardirqs are
1887 if (curr
->hardirqs_enabled
)
1888 mark_held_locks(curr
, 0, ip
);
1892 * Softirqs were disabled:
1894 void trace_softirqs_off(unsigned long ip
)
1896 struct task_struct
*curr
= current
;
1898 if (unlikely(!debug_locks
))
1901 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1904 if (curr
->softirqs_enabled
) {
1906 * We have done an ON -> OFF transition:
1908 curr
->softirqs_enabled
= 0;
1909 curr
->softirq_disable_ip
= ip
;
1910 curr
->softirq_disable_event
= ++curr
->irq_events
;
1911 debug_atomic_inc(&softirqs_off_events
);
1912 DEBUG_LOCKS_WARN_ON(!softirq_count());
1914 debug_atomic_inc(&redundant_softirqs_off
);
1920 * Initialize a lock instance's lock-class mapping info:
1922 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
1923 struct lock_class_key
*key
)
1925 if (unlikely(!debug_locks
))
1928 if (DEBUG_LOCKS_WARN_ON(!key
))
1930 if (DEBUG_LOCKS_WARN_ON(!name
))
1933 * Sanity check, the lock-class key must be persistent:
1935 if (!static_obj(key
)) {
1936 printk("BUG: key %p not in .data!\n", key
);
1937 DEBUG_LOCKS_WARN_ON(1);
1942 lock
->class_cache
= NULL
;
1945 EXPORT_SYMBOL_GPL(lockdep_init_map
);
1948 * This gets called for every mutex_lock*()/spin_lock*() operation.
1949 * We maintain the dependency maps and validate the locking attempt:
1951 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
1952 int trylock
, int read
, int check
, int hardirqs_off
,
1955 struct task_struct
*curr
= current
;
1956 struct lock_class
*class = NULL
;
1957 struct held_lock
*hlock
;
1958 unsigned int depth
, id
;
1962 if (unlikely(!debug_locks
))
1965 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1968 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
1970 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
1971 printk("turning off the locking correctness validator.\n");
1976 class = lock
->class_cache
;
1978 * Not cached yet or subclass?
1980 if (unlikely(!class)) {
1981 class = register_lock_class(lock
, subclass
);
1985 debug_atomic_inc((atomic_t
*)&class->ops
);
1986 if (very_verbose(class)) {
1987 printk("\nacquire class [%p] %s", class->key
, class->name
);
1988 if (class->name_version
> 1)
1989 printk("#%d", class->name_version
);
1995 * Add the lock to the list of currently held locks.
1996 * (we dont increase the depth just yet, up until the
1997 * dependency checks are done)
1999 depth
= curr
->lockdep_depth
;
2000 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2003 hlock
= curr
->held_locks
+ depth
;
2005 hlock
->class = class;
2006 hlock
->acquire_ip
= ip
;
2007 hlock
->instance
= lock
;
2008 hlock
->trylock
= trylock
;
2010 hlock
->check
= check
;
2011 hlock
->hardirqs_off
= hardirqs_off
;
2015 #ifdef CONFIG_TRACE_IRQFLAGS
2017 * If non-trylock use in a hardirq or softirq context, then
2018 * mark the lock as used in these contexts:
2022 if (curr
->hardirq_context
)
2023 if (!mark_lock(curr
, hlock
,
2024 LOCK_USED_IN_HARDIRQ_READ
, ip
))
2026 if (curr
->softirq_context
)
2027 if (!mark_lock(curr
, hlock
,
2028 LOCK_USED_IN_SOFTIRQ_READ
, ip
))
2031 if (curr
->hardirq_context
)
2032 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
, ip
))
2034 if (curr
->softirq_context
)
2035 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
, ip
))
2039 if (!hardirqs_off
) {
2041 if (!mark_lock(curr
, hlock
,
2042 LOCK_ENABLED_HARDIRQS_READ
, ip
))
2044 if (curr
->softirqs_enabled
)
2045 if (!mark_lock(curr
, hlock
,
2046 LOCK_ENABLED_SOFTIRQS_READ
, ip
))
2049 if (!mark_lock(curr
, hlock
,
2050 LOCK_ENABLED_HARDIRQS
, ip
))
2052 if (curr
->softirqs_enabled
)
2053 if (!mark_lock(curr
, hlock
,
2054 LOCK_ENABLED_SOFTIRQS
, ip
))
2059 /* mark it as used: */
2060 if (!mark_lock(curr
, hlock
, LOCK_USED
, ip
))
2064 * Calculate the chain hash: it's the combined has of all the
2065 * lock keys along the dependency chain. We save the hash value
2066 * at every step so that we can get the current hash easily
2067 * after unlock. The chain hash is then used to cache dependency
2070 * The 'key ID' is what is the most compact key value to drive
2071 * the hash, not class->key.
2073 id
= class - lock_classes
;
2074 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2077 chain_key
= curr
->curr_chain_key
;
2079 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2084 hlock
->prev_chain_key
= chain_key
;
2086 #ifdef CONFIG_TRACE_IRQFLAGS
2088 * Keep track of points where we cross into an interrupt context:
2090 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2091 curr
->softirq_context
;
2093 struct held_lock
*prev_hlock
;
2095 prev_hlock
= curr
->held_locks
+ depth
-1;
2097 * If we cross into another context, reset the
2098 * hash key (this also prevents the checking and the
2099 * adding of the dependency to 'prev'):
2101 if (prev_hlock
->irq_context
!= hlock
->irq_context
) {
2107 chain_key
= iterate_chain_key(chain_key
, id
);
2108 curr
->curr_chain_key
= chain_key
;
2111 * Trylock needs to maintain the stack of held locks, but it
2112 * does not add new dependencies, because trylock can be done
2115 * We look up the chain_key and do the O(N^2) check and update of
2116 * the dependencies only if this is a new dependency chain.
2117 * (If lookup_chain_cache() returns with 1 it acquires
2120 if (!trylock
&& (check
== 2) && lookup_chain_cache(chain_key
)) {
2122 * Check whether last held lock:
2124 * - is irq-safe, if this lock is irq-unsafe
2125 * - is softirq-safe, if this lock is hardirq-unsafe
2127 * And check whether the new lock's dependency graph
2128 * could lead back to the previous lock.
2130 * any of these scenarios could lead to a deadlock. If
2133 int ret
= check_deadlock(curr
, hlock
, lock
, read
);
2138 * Mark recursive read, as we jump over it when
2139 * building dependencies (just like we jump over
2145 * Add dependency only if this lock is not the head
2146 * of the chain, and if it's not a secondary read-lock:
2148 if (!chain_head
&& ret
!= 2)
2149 if (!check_prevs_add(curr
, hlock
))
2151 __raw_spin_unlock(&hash_lock
);
2153 curr
->lockdep_depth
++;
2154 check_chain_key(curr
);
2155 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2157 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2158 printk("turning off the locking correctness validator.\n");
2161 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2162 max_lockdep_depth
= curr
->lockdep_depth
;
2168 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2171 if (!debug_locks_off())
2173 if (debug_locks_silent
)
2176 printk("\n=====================================\n");
2177 printk( "[ BUG: bad unlock balance detected! ]\n");
2178 printk( "-------------------------------------\n");
2179 printk("%s/%d is trying to release lock (",
2180 curr
->comm
, curr
->pid
);
2181 print_lockdep_cache(lock
);
2184 printk("but there are no more locks to release!\n");
2185 printk("\nother info that might help us debug this:\n");
2186 lockdep_print_held_locks(curr
);
2188 printk("\nstack backtrace:\n");
2195 * Common debugging checks for both nested and non-nested unlock:
2197 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2200 if (unlikely(!debug_locks
))
2202 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2205 if (curr
->lockdep_depth
<= 0)
2206 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2212 * Remove the lock to the list of currently held locks in a
2213 * potentially non-nested (out of order) manner. This is a
2214 * relatively rare operation, as all the unlock APIs default
2215 * to nested mode (which uses lock_release()):
2218 lock_release_non_nested(struct task_struct
*curr
,
2219 struct lockdep_map
*lock
, unsigned long ip
)
2221 struct held_lock
*hlock
, *prev_hlock
;
2226 * Check whether the lock exists in the current stack
2229 depth
= curr
->lockdep_depth
;
2230 if (DEBUG_LOCKS_WARN_ON(!depth
))
2234 for (i
= depth
-1; i
>= 0; i
--) {
2235 hlock
= curr
->held_locks
+ i
;
2237 * We must not cross into another context:
2239 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2241 if (hlock
->instance
== lock
)
2245 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2249 * We have the right lock to unlock, 'hlock' points to it.
2250 * Now we remove it from the stack, and add back the other
2251 * entries (if any), recalculating the hash along the way:
2253 curr
->lockdep_depth
= i
;
2254 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2256 for (i
++; i
< depth
; i
++) {
2257 hlock
= curr
->held_locks
+ i
;
2258 if (!__lock_acquire(hlock
->instance
,
2259 hlock
->class->subclass
, hlock
->trylock
,
2260 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2265 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2271 * Remove the lock to the list of currently held locks - this gets
2272 * called on mutex_unlock()/spin_unlock*() (or on a failed
2273 * mutex_lock_interruptible()). This is done for unlocks that nest
2274 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2276 static int lock_release_nested(struct task_struct
*curr
,
2277 struct lockdep_map
*lock
, unsigned long ip
)
2279 struct held_lock
*hlock
;
2283 * Pop off the top of the lock stack:
2285 depth
= curr
->lockdep_depth
- 1;
2286 hlock
= curr
->held_locks
+ depth
;
2289 * Is the unlock non-nested:
2291 if (hlock
->instance
!= lock
)
2292 return lock_release_non_nested(curr
, lock
, ip
);
2293 curr
->lockdep_depth
--;
2295 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2298 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2300 #ifdef CONFIG_DEBUG_LOCKDEP
2301 hlock
->prev_chain_key
= 0;
2302 hlock
->class = NULL
;
2303 hlock
->acquire_ip
= 0;
2304 hlock
->irq_context
= 0;
2310 * Remove the lock to the list of currently held locks - this gets
2311 * called on mutex_unlock()/spin_unlock*() (or on a failed
2312 * mutex_lock_interruptible()). This is done for unlocks that nest
2313 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2316 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2318 struct task_struct
*curr
= current
;
2320 if (!check_unlock(curr
, lock
, ip
))
2324 if (!lock_release_nested(curr
, lock
, ip
))
2327 if (!lock_release_non_nested(curr
, lock
, ip
))
2331 check_chain_key(curr
);
2335 * Check whether we follow the irq-flags state precisely:
2337 static void check_flags(unsigned long flags
)
2339 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2343 if (irqs_disabled_flags(flags
))
2344 DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
);
2346 DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
);
2349 * We dont accurately track softirq state in e.g.
2350 * hardirq contexts (such as on 4KSTACKS), so only
2351 * check if not in hardirq contexts:
2353 if (!hardirq_count()) {
2354 if (softirq_count())
2355 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
2357 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
2361 print_irqtrace_events(current
);
2366 * We are not always called with irqs disabled - do that here,
2367 * and also avoid lockdep recursion:
2369 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2370 int trylock
, int read
, int check
, unsigned long ip
)
2372 unsigned long flags
;
2374 if (unlikely(current
->lockdep_recursion
))
2377 raw_local_irq_save(flags
);
2380 current
->lockdep_recursion
= 1;
2381 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
2382 irqs_disabled_flags(flags
), ip
);
2383 current
->lockdep_recursion
= 0;
2384 raw_local_irq_restore(flags
);
2387 EXPORT_SYMBOL_GPL(lock_acquire
);
2389 void lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2391 unsigned long flags
;
2393 if (unlikely(current
->lockdep_recursion
))
2396 raw_local_irq_save(flags
);
2398 current
->lockdep_recursion
= 1;
2399 __lock_release(lock
, nested
, ip
);
2400 current
->lockdep_recursion
= 0;
2401 raw_local_irq_restore(flags
);
2404 EXPORT_SYMBOL_GPL(lock_release
);
2407 * Used by the testsuite, sanitize the validator state
2408 * after a simulated failure:
2411 void lockdep_reset(void)
2413 unsigned long flags
;
2415 raw_local_irq_save(flags
);
2416 current
->curr_chain_key
= 0;
2417 current
->lockdep_depth
= 0;
2418 current
->lockdep_recursion
= 0;
2419 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
2420 nr_hardirq_chains
= 0;
2421 nr_softirq_chains
= 0;
2422 nr_process_chains
= 0;
2424 raw_local_irq_restore(flags
);
2427 static void zap_class(struct lock_class
*class)
2432 * Remove all dependencies this lock is
2435 for (i
= 0; i
< nr_list_entries
; i
++) {
2436 if (list_entries
[i
].class == class)
2437 list_del_rcu(&list_entries
[i
].entry
);
2440 * Unhash the class and remove it from the all_lock_classes list:
2442 list_del_rcu(&class->hash_entry
);
2443 list_del_rcu(&class->lock_entry
);
2447 static inline int within(void *addr
, void *start
, unsigned long size
)
2449 return addr
>= start
&& addr
< start
+ size
;
2452 void lockdep_free_key_range(void *start
, unsigned long size
)
2454 struct lock_class
*class, *next
;
2455 struct list_head
*head
;
2456 unsigned long flags
;
2459 raw_local_irq_save(flags
);
2460 __raw_spin_lock(&hash_lock
);
2463 * Unhash all classes that were created by this module:
2465 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
2466 head
= classhash_table
+ i
;
2467 if (list_empty(head
))
2469 list_for_each_entry_safe(class, next
, head
, hash_entry
)
2470 if (within(class->key
, start
, size
))
2474 __raw_spin_unlock(&hash_lock
);
2475 raw_local_irq_restore(flags
);
2478 void lockdep_reset_lock(struct lockdep_map
*lock
)
2480 struct lock_class
*class, *next
;
2481 struct list_head
*head
;
2482 unsigned long flags
;
2485 raw_local_irq_save(flags
);
2488 * Remove all classes this lock might have:
2490 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
2492 * If the class exists we look it up and zap it:
2494 class = look_up_lock_class(lock
, j
);
2499 * Debug check: in the end all mapped classes should
2502 __raw_spin_lock(&hash_lock
);
2503 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
2504 head
= classhash_table
+ i
;
2505 if (list_empty(head
))
2507 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
2508 if (unlikely(class == lock
->class_cache
)) {
2509 __raw_spin_unlock(&hash_lock
);
2510 DEBUG_LOCKS_WARN_ON(1);
2515 __raw_spin_unlock(&hash_lock
);
2518 raw_local_irq_restore(flags
);
2521 void __init
lockdep_init(void)
2526 * Some architectures have their own start_kernel()
2527 * code which calls lockdep_init(), while we also
2528 * call lockdep_init() from the start_kernel() itself,
2529 * and we want to initialize the hashes only once:
2531 if (lockdep_initialized
)
2534 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
2535 INIT_LIST_HEAD(classhash_table
+ i
);
2537 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
2538 INIT_LIST_HEAD(chainhash_table
+ i
);
2540 lockdep_initialized
= 1;
2543 void __init
lockdep_info(void)
2545 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
2547 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
2548 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
2549 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
2550 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
2551 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
2552 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
2553 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
2555 printk(" memory used by lock dependency info: %lu kB\n",
2556 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
2557 sizeof(struct list_head
) * CLASSHASH_SIZE
+
2558 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
2559 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
2560 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
2562 printk(" per task-struct memory footprint: %lu bytes\n",
2563 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
2565 #ifdef CONFIG_DEBUG_LOCKDEP
2566 if (lockdep_init_error
)
2567 printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n");
2571 static inline int in_range(const void *start
, const void *addr
, const void *end
)
2573 return addr
>= start
&& addr
<= end
;
2577 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
2578 const void *mem_to
, struct held_lock
*hlock
)
2580 if (!debug_locks_off())
2582 if (debug_locks_silent
)
2585 printk("\n=========================\n");
2586 printk( "[ BUG: held lock freed! ]\n");
2587 printk( "-------------------------\n");
2588 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
2589 curr
->comm
, curr
->pid
, mem_from
, mem_to
-1);
2591 lockdep_print_held_locks(curr
);
2593 printk("\nstack backtrace:\n");
2598 * Called when kernel memory is freed (or unmapped), or if a lock
2599 * is destroyed or reinitialized - this code checks whether there is
2600 * any held lock in the memory range of <from> to <to>:
2602 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
2604 const void *mem_to
= mem_from
+ mem_len
, *lock_from
, *lock_to
;
2605 struct task_struct
*curr
= current
;
2606 struct held_lock
*hlock
;
2607 unsigned long flags
;
2610 if (unlikely(!debug_locks
))
2613 local_irq_save(flags
);
2614 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2615 hlock
= curr
->held_locks
+ i
;
2617 lock_from
= (void *)hlock
->instance
;
2618 lock_to
= (void *)(hlock
->instance
+ 1);
2620 if (!in_range(mem_from
, lock_from
, mem_to
) &&
2621 !in_range(mem_from
, lock_to
, mem_to
))
2624 print_freed_lock_bug(curr
, mem_from
, mem_to
, hlock
);
2627 local_irq_restore(flags
);
2630 static void print_held_locks_bug(struct task_struct
*curr
)
2632 if (!debug_locks_off())
2634 if (debug_locks_silent
)
2637 printk("\n=====================================\n");
2638 printk( "[ BUG: lock held at task exit time! ]\n");
2639 printk( "-------------------------------------\n");
2640 printk("%s/%d is exiting with locks still held!\n",
2641 curr
->comm
, curr
->pid
);
2642 lockdep_print_held_locks(curr
);
2644 printk("\nstack backtrace:\n");
2648 void debug_check_no_locks_held(struct task_struct
*task
)
2650 if (unlikely(task
->lockdep_depth
> 0))
2651 print_held_locks_bug(task
);
2654 void debug_show_all_locks(void)
2656 struct task_struct
*g
, *p
;
2660 printk("\nShowing all locks held in the system:\n");
2663 * Here we try to get the tasklist_lock as hard as possible,
2664 * if not successful after 2 seconds we ignore it (but keep
2665 * trying). This is to enable a debug printout even if a
2666 * tasklist_lock-holding task deadlocks or crashes.
2669 if (!read_trylock(&tasklist_lock
)) {
2671 printk("hm, tasklist_lock locked, retrying... ");
2674 printk(" #%d", 10-count
);
2678 printk(" ignoring it.\n");
2682 printk(" locked it.\n");
2684 do_each_thread(g
, p
) {
2685 if (p
->lockdep_depth
)
2686 lockdep_print_held_locks(p
);
2688 if (read_trylock(&tasklist_lock
))
2690 } while_each_thread(g
, p
);
2693 printk("=============================================\n\n");
2696 read_unlock(&tasklist_lock
);
2699 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
2701 void debug_show_held_locks(struct task_struct
*task
)
2703 lockdep_print_held_locks(task
);
2706 EXPORT_SYMBOL_GPL(debug_show_held_locks
);