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 * lockdep_lock: protects the lockdep graph, the hashes and the
47 * class/list/hash allocators.
49 * This is one of the rare exceptions where it's justified
50 * to use a raw spinlock - we really dont want the spinlock
51 * code to recurse back into the lockdep code...
53 static raw_spinlock_t lockdep_lock
= (raw_spinlock_t
)__RAW_SPIN_LOCK_UNLOCKED
;
55 static int graph_lock(void)
57 __raw_spin_lock(&lockdep_lock
);
59 * Make sure that if another CPU detected a bug while
60 * walking the graph we dont change it (while the other
61 * CPU is busy printing out stuff with the graph lock
65 __raw_spin_unlock(&lockdep_lock
);
71 static inline int graph_unlock(void)
73 if (debug_locks
&& !__raw_spin_is_locked(&lockdep_lock
))
74 return DEBUG_LOCKS_WARN_ON(1);
76 __raw_spin_unlock(&lockdep_lock
);
81 * Turn lock debugging off and return with 0 if it was off already,
82 * and also release the graph lock:
84 static inline int debug_locks_off_graph_unlock(void)
86 int ret
= debug_locks_off();
88 __raw_spin_unlock(&lockdep_lock
);
93 static int lockdep_initialized
;
95 unsigned long nr_list_entries
;
96 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
99 * Allocate a lockdep entry. (assumes the graph_lock held, returns
100 * with NULL on failure)
102 static struct lock_list
*alloc_list_entry(void)
104 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
105 if (!debug_locks_off_graph_unlock())
108 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
109 printk("turning off the locking correctness validator.\n");
112 return list_entries
+ nr_list_entries
++;
116 * All data structures here are protected by the global debug_lock.
118 * Mutex key structs only get allocated, once during bootup, and never
119 * get freed - this significantly simplifies the debugging code.
121 unsigned long nr_lock_classes
;
122 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
125 * We keep a global list of all lock classes. The list only grows,
126 * never shrinks. The list is only accessed with the lockdep
127 * spinlock lock held.
129 LIST_HEAD(all_lock_classes
);
132 * The lockdep classes are in a hash-table as well, for fast lookup:
134 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
135 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
136 #define CLASSHASH_MASK (CLASSHASH_SIZE - 1)
137 #define __classhashfn(key) ((((unsigned long)key >> CLASSHASH_BITS) + (unsigned long)key) & CLASSHASH_MASK)
138 #define classhashentry(key) (classhash_table + __classhashfn((key)))
140 static struct list_head classhash_table
[CLASSHASH_SIZE
];
142 unsigned long nr_lock_chains
;
143 static struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
146 * We put the lock dependency chains into a hash-table as well, to cache
149 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
150 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
151 #define CHAINHASH_MASK (CHAINHASH_SIZE - 1)
152 #define __chainhashfn(chain) \
153 (((chain >> CHAINHASH_BITS) + chain) & CHAINHASH_MASK)
154 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
156 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
159 * The hash key of the lock dependency chains is a hash itself too:
160 * it's a hash of all locks taken up to that lock, including that lock.
161 * It's a 64-bit hash, because it's important for the keys to be
164 #define iterate_chain_key(key1, key2) \
165 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
166 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
169 void lockdep_off(void)
171 current
->lockdep_recursion
++;
174 EXPORT_SYMBOL(lockdep_off
);
176 void lockdep_on(void)
178 current
->lockdep_recursion
--;
181 EXPORT_SYMBOL(lockdep_on
);
184 * Debugging switches:
188 #define VERY_VERBOSE 0
191 # define HARDIRQ_VERBOSE 1
192 # define SOFTIRQ_VERBOSE 1
194 # define HARDIRQ_VERBOSE 0
195 # define SOFTIRQ_VERBOSE 0
198 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
200 * Quick filtering for interesting events:
202 static int class_filter(struct lock_class
*class)
206 if (class->name_version
== 1 &&
207 !strcmp(class->name
, "lockname"))
209 if (class->name_version
== 1 &&
210 !strcmp(class->name
, "&struct->lockfield"))
213 /* Filter everything else. 1 would be to allow everything else */
218 static int verbose(struct lock_class
*class)
221 return class_filter(class);
226 #ifdef CONFIG_TRACE_IRQFLAGS
228 static int hardirq_verbose(struct lock_class
*class)
231 return class_filter(class);
236 static int softirq_verbose(struct lock_class
*class)
239 return class_filter(class);
247 * Stack-trace: tightly packed array of stack backtrace
248 * addresses. Protected by the graph_lock.
250 unsigned long nr_stack_trace_entries
;
251 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
253 static int save_trace(struct stack_trace
*trace
)
255 trace
->nr_entries
= 0;
256 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
257 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
261 save_stack_trace(trace
);
263 trace
->max_entries
= trace
->nr_entries
;
265 nr_stack_trace_entries
+= trace
->nr_entries
;
267 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
268 if (!debug_locks_off_graph_unlock())
271 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
272 printk("turning off the locking correctness validator.\n");
281 unsigned int nr_hardirq_chains
;
282 unsigned int nr_softirq_chains
;
283 unsigned int nr_process_chains
;
284 unsigned int max_lockdep_depth
;
285 unsigned int max_recursion_depth
;
287 #ifdef CONFIG_DEBUG_LOCKDEP
289 * We cannot printk in early bootup code. Not even early_printk()
290 * might work. So we mark any initialization errors and printk
291 * about it later on, in lockdep_info().
293 static int lockdep_init_error
;
296 * Various lockdep statistics:
298 atomic_t chain_lookup_hits
;
299 atomic_t chain_lookup_misses
;
300 atomic_t hardirqs_on_events
;
301 atomic_t hardirqs_off_events
;
302 atomic_t redundant_hardirqs_on
;
303 atomic_t redundant_hardirqs_off
;
304 atomic_t softirqs_on_events
;
305 atomic_t softirqs_off_events
;
306 atomic_t redundant_softirqs_on
;
307 atomic_t redundant_softirqs_off
;
308 atomic_t nr_unused_locks
;
309 atomic_t nr_cyclic_checks
;
310 atomic_t nr_cyclic_check_recursions
;
311 atomic_t nr_find_usage_forwards_checks
;
312 atomic_t nr_find_usage_forwards_recursions
;
313 atomic_t nr_find_usage_backwards_checks
;
314 atomic_t nr_find_usage_backwards_recursions
;
315 # define debug_atomic_inc(ptr) atomic_inc(ptr)
316 # define debug_atomic_dec(ptr) atomic_dec(ptr)
317 # define debug_atomic_read(ptr) atomic_read(ptr)
319 # define debug_atomic_inc(ptr) do { } while (0)
320 # define debug_atomic_dec(ptr) do { } while (0)
321 # define debug_atomic_read(ptr) 0
328 static const char *usage_str
[] =
330 [LOCK_USED
] = "initial-use ",
331 [LOCK_USED_IN_HARDIRQ
] = "in-hardirq-W",
332 [LOCK_USED_IN_SOFTIRQ
] = "in-softirq-W",
333 [LOCK_ENABLED_SOFTIRQS
] = "softirq-on-W",
334 [LOCK_ENABLED_HARDIRQS
] = "hardirq-on-W",
335 [LOCK_USED_IN_HARDIRQ_READ
] = "in-hardirq-R",
336 [LOCK_USED_IN_SOFTIRQ_READ
] = "in-softirq-R",
337 [LOCK_ENABLED_SOFTIRQS_READ
] = "softirq-on-R",
338 [LOCK_ENABLED_HARDIRQS_READ
] = "hardirq-on-R",
341 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
343 unsigned long offs
, size
;
346 return kallsyms_lookup((unsigned long)key
, &size
, &offs
, &modname
, str
);
350 get_usage_chars(struct lock_class
*class, char *c1
, char *c2
, char *c3
, char *c4
)
352 *c1
= '.', *c2
= '.', *c3
= '.', *c4
= '.';
354 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ
)
357 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS
)
360 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ
)
363 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS
)
366 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
368 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ_READ
) {
370 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
374 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
376 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ_READ
) {
378 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
383 static void print_lock_name(struct lock_class
*class)
385 char str
[KSYM_NAME_LEN
+ 1], c1
, c2
, c3
, c4
;
388 get_usage_chars(class, &c1
, &c2
, &c3
, &c4
);
392 name
= __get_key_name(class->key
, str
);
393 printk(" (%s", name
);
395 printk(" (%s", name
);
396 if (class->name_version
> 1)
397 printk("#%d", class->name_version
);
399 printk("/%d", class->subclass
);
401 printk("){%c%c%c%c}", c1
, c2
, c3
, c4
);
404 static void print_lockdep_cache(struct lockdep_map
*lock
)
407 char str
[KSYM_NAME_LEN
+ 1];
411 name
= __get_key_name(lock
->key
->subkeys
, str
);
416 static void print_lock(struct held_lock
*hlock
)
418 print_lock_name(hlock
->class);
420 print_ip_sym(hlock
->acquire_ip
);
423 static void lockdep_print_held_locks(struct task_struct
*curr
)
425 int i
, depth
= curr
->lockdep_depth
;
428 printk("no locks held by %s/%d.\n", curr
->comm
, curr
->pid
);
431 printk("%d lock%s held by %s/%d:\n",
432 depth
, depth
> 1 ? "s" : "", curr
->comm
, curr
->pid
);
434 for (i
= 0; i
< depth
; i
++) {
436 print_lock(curr
->held_locks
+ i
);
440 static void print_lock_class_header(struct lock_class
*class, int depth
)
444 printk("%*s->", depth
, "");
445 print_lock_name(class);
446 printk(" ops: %lu", class->ops
);
449 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
450 if (class->usage_mask
& (1 << bit
)) {
453 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
454 len
+= printk(" at:\n");
455 print_stack_trace(class->usage_traces
+ bit
, len
);
458 printk("%*s }\n", depth
, "");
460 printk("%*s ... key at: ",depth
,"");
461 print_ip_sym((unsigned long)class->key
);
465 * printk all lock dependencies starting at <entry>:
467 static void print_lock_dependencies(struct lock_class
*class, int depth
)
469 struct lock_list
*entry
;
471 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
474 print_lock_class_header(class, depth
);
476 list_for_each_entry(entry
, &class->locks_after
, entry
) {
477 if (DEBUG_LOCKS_WARN_ON(!entry
->class))
480 print_lock_dependencies(entry
->class, depth
+ 1);
482 printk("%*s ... acquired at:\n",depth
,"");
483 print_stack_trace(&entry
->trace
, 2);
489 * Add a new dependency to the head of the list:
491 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
492 struct list_head
*head
, unsigned long ip
, int distance
)
494 struct lock_list
*entry
;
496 * Lock not present yet - get a new dependency struct and
497 * add it to the list:
499 entry
= alloc_list_entry();
504 entry
->distance
= distance
;
505 if (!save_trace(&entry
->trace
))
509 * Since we never remove from the dependency list, the list can
510 * be walked lockless by other CPUs, it's only allocation
511 * that must be protected by the spinlock. But this also means
512 * we must make new entries visible only once writes to the
513 * entry become visible - hence the RCU op:
515 list_add_tail_rcu(&entry
->entry
, head
);
521 * Recursive, forwards-direction lock-dependency checking, used for
522 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
525 * (to keep the stackframe of the recursive functions small we
526 * use these global variables, and we also mark various helper
527 * functions as noinline.)
529 static struct held_lock
*check_source
, *check_target
;
532 * Print a dependency chain entry (this is only done when a deadlock
533 * has been detected):
536 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
538 if (debug_locks_silent
)
540 printk("\n-> #%u", depth
);
541 print_lock_name(target
->class);
543 print_stack_trace(&target
->trace
, 6);
548 static void print_kernel_version(void)
550 printk("%s %.*s\n", init_utsname()->release
,
551 (int)strcspn(init_utsname()->version
, " "),
552 init_utsname()->version
);
556 * When a circular dependency is detected, print the
560 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
)
562 struct task_struct
*curr
= current
;
564 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
567 printk("\n=======================================================\n");
568 printk( "[ INFO: possible circular locking dependency detected ]\n");
569 print_kernel_version();
570 printk( "-------------------------------------------------------\n");
571 printk("%s/%d is trying to acquire lock:\n",
572 curr
->comm
, curr
->pid
);
573 print_lock(check_source
);
574 printk("\nbut task is already holding lock:\n");
575 print_lock(check_target
);
576 printk("\nwhich lock already depends on the new lock.\n\n");
577 printk("\nthe existing dependency chain (in reverse order) is:\n");
579 print_circular_bug_entry(entry
, depth
);
584 static noinline
int print_circular_bug_tail(void)
586 struct task_struct
*curr
= current
;
587 struct lock_list
this;
589 if (debug_locks_silent
)
592 this.class = check_source
->class;
593 if (!save_trace(&this.trace
))
596 print_circular_bug_entry(&this, 0);
598 printk("\nother info that might help us debug this:\n\n");
599 lockdep_print_held_locks(curr
);
601 printk("\nstack backtrace:\n");
607 #define RECURSION_LIMIT 40
609 static int noinline
print_infinite_recursion_bug(void)
611 if (!debug_locks_off_graph_unlock())
620 * Prove that the dependency graph starting at <entry> can not
621 * lead to <target>. Print an error and return 0 if it does.
624 check_noncircular(struct lock_class
*source
, unsigned int depth
)
626 struct lock_list
*entry
;
628 debug_atomic_inc(&nr_cyclic_check_recursions
);
629 if (depth
> max_recursion_depth
)
630 max_recursion_depth
= depth
;
631 if (depth
>= RECURSION_LIMIT
)
632 return print_infinite_recursion_bug();
634 * Check this lock's dependency list:
636 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
637 if (entry
->class == check_target
->class)
638 return print_circular_bug_header(entry
, depth
+1);
639 debug_atomic_inc(&nr_cyclic_checks
);
640 if (!check_noncircular(entry
->class, depth
+1))
641 return print_circular_bug_entry(entry
, depth
+1);
646 static int very_verbose(struct lock_class
*class)
649 return class_filter(class);
653 #ifdef CONFIG_TRACE_IRQFLAGS
656 * Forwards and backwards subgraph searching, for the purposes of
657 * proving that two subgraphs can be connected by a new dependency
658 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
660 static enum lock_usage_bit find_usage_bit
;
661 static struct lock_class
*forwards_match
, *backwards_match
;
664 * Find a node in the forwards-direction dependency sub-graph starting
665 * at <source> that matches <find_usage_bit>.
667 * Return 2 if such a node exists in the subgraph, and put that node
668 * into <forwards_match>.
670 * Return 1 otherwise and keep <forwards_match> unchanged.
674 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
676 struct lock_list
*entry
;
679 if (depth
> max_recursion_depth
)
680 max_recursion_depth
= depth
;
681 if (depth
>= RECURSION_LIMIT
)
682 return print_infinite_recursion_bug();
684 debug_atomic_inc(&nr_find_usage_forwards_checks
);
685 if (source
->usage_mask
& (1 << find_usage_bit
)) {
686 forwards_match
= source
;
691 * Check this lock's dependency list:
693 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
694 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
695 ret
= find_usage_forwards(entry
->class, depth
+1);
696 if (ret
== 2 || ret
== 0)
703 * Find a node in the backwards-direction dependency sub-graph starting
704 * at <source> that matches <find_usage_bit>.
706 * Return 2 if such a node exists in the subgraph, and put that node
707 * into <backwards_match>.
709 * Return 1 otherwise and keep <backwards_match> unchanged.
713 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
715 struct lock_list
*entry
;
718 if (!__raw_spin_is_locked(&lockdep_lock
))
719 return DEBUG_LOCKS_WARN_ON(1);
721 if (depth
> max_recursion_depth
)
722 max_recursion_depth
= depth
;
723 if (depth
>= RECURSION_LIMIT
)
724 return print_infinite_recursion_bug();
726 debug_atomic_inc(&nr_find_usage_backwards_checks
);
727 if (source
->usage_mask
& (1 << find_usage_bit
)) {
728 backwards_match
= source
;
733 * Check this lock's dependency list:
735 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
736 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
737 ret
= find_usage_backwards(entry
->class, depth
+1);
738 if (ret
== 2 || ret
== 0)
745 print_bad_irq_dependency(struct task_struct
*curr
,
746 struct held_lock
*prev
,
747 struct held_lock
*next
,
748 enum lock_usage_bit bit1
,
749 enum lock_usage_bit bit2
,
750 const char *irqclass
)
752 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
755 printk("\n======================================================\n");
756 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
758 print_kernel_version();
759 printk( "------------------------------------------------------\n");
760 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
761 curr
->comm
, curr
->pid
,
762 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
763 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
764 curr
->hardirqs_enabled
,
765 curr
->softirqs_enabled
);
768 printk("\nand this task is already holding:\n");
770 printk("which would create a new lock dependency:\n");
771 print_lock_name(prev
->class);
773 print_lock_name(next
->class);
776 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
778 print_lock_name(backwards_match
);
779 printk("\n... which became %s-irq-safe at:\n", irqclass
);
781 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
783 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
784 print_lock_name(forwards_match
);
785 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
788 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
790 printk("\nother info that might help us debug this:\n\n");
791 lockdep_print_held_locks(curr
);
793 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
794 print_lock_dependencies(backwards_match
, 0);
796 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
797 print_lock_dependencies(forwards_match
, 0);
799 printk("\nstack backtrace:\n");
806 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
807 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
808 enum lock_usage_bit bit_forwards
, const char *irqclass
)
812 find_usage_bit
= bit_backwards
;
813 /* fills in <backwards_match> */
814 ret
= find_usage_backwards(prev
->class, 0);
815 if (!ret
|| ret
== 1)
818 find_usage_bit
= bit_forwards
;
819 ret
= find_usage_forwards(next
->class, 0);
820 if (!ret
|| ret
== 1)
823 return print_bad_irq_dependency(curr
, prev
, next
,
824 bit_backwards
, bit_forwards
, irqclass
);
830 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
831 struct held_lock
*next
)
833 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
836 printk("\n=============================================\n");
837 printk( "[ INFO: possible recursive locking detected ]\n");
838 print_kernel_version();
839 printk( "---------------------------------------------\n");
840 printk("%s/%d is trying to acquire lock:\n",
841 curr
->comm
, curr
->pid
);
843 printk("\nbut task is already holding lock:\n");
846 printk("\nother info that might help us debug this:\n");
847 lockdep_print_held_locks(curr
);
849 printk("\nstack backtrace:\n");
856 * Check whether we are holding such a class already.
858 * (Note that this has to be done separately, because the graph cannot
859 * detect such classes of deadlocks.)
861 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
864 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
865 struct lockdep_map
*next_instance
, int read
)
867 struct held_lock
*prev
;
870 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
871 prev
= curr
->held_locks
+ i
;
872 if (prev
->class != next
->class)
875 * Allow read-after-read recursion of the same
876 * lock class (i.e. read_lock(lock)+read_lock(lock)):
878 if ((read
== 2) && prev
->read
)
880 return print_deadlock_bug(curr
, prev
, next
);
886 * There was a chain-cache miss, and we are about to add a new dependency
887 * to a previous lock. We recursively validate the following rules:
889 * - would the adding of the <prev> -> <next> dependency create a
890 * circular dependency in the graph? [== circular deadlock]
892 * - does the new prev->next dependency connect any hardirq-safe lock
893 * (in the full backwards-subgraph starting at <prev>) with any
894 * hardirq-unsafe lock (in the full forwards-subgraph starting at
895 * <next>)? [== illegal lock inversion with hardirq contexts]
897 * - does the new prev->next dependency connect any softirq-safe lock
898 * (in the full backwards-subgraph starting at <prev>) with any
899 * softirq-unsafe lock (in the full forwards-subgraph starting at
900 * <next>)? [== illegal lock inversion with softirq contexts]
902 * any of these scenarios could lead to a deadlock.
904 * Then if all the validations pass, we add the forwards and backwards
908 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
909 struct held_lock
*next
, int distance
)
911 struct lock_list
*entry
;
915 * Prove that the new <prev> -> <next> dependency would not
916 * create a circular dependency in the graph. (We do this by
917 * forward-recursing into the graph starting at <next>, and
918 * checking whether we can reach <prev>.)
920 * We are using global variables to control the recursion, to
921 * keep the stackframe size of the recursive functions low:
925 if (!(check_noncircular(next
->class, 0)))
926 return print_circular_bug_tail();
928 #ifdef CONFIG_TRACE_IRQFLAGS
930 * Prove that the new dependency does not connect a hardirq-safe
931 * lock with a hardirq-unsafe lock - to achieve this we search
932 * the backwards-subgraph starting at <prev>, and the
933 * forwards-subgraph starting at <next>:
935 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ
,
936 LOCK_ENABLED_HARDIRQS
, "hard"))
940 * Prove that the new dependency does not connect a hardirq-safe-read
941 * lock with a hardirq-unsafe lock - to achieve this we search
942 * the backwards-subgraph starting at <prev>, and the
943 * forwards-subgraph starting at <next>:
945 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ_READ
,
946 LOCK_ENABLED_HARDIRQS
, "hard-read"))
950 * Prove that the new dependency does not connect a softirq-safe
951 * lock with a softirq-unsafe lock - to achieve this we search
952 * the backwards-subgraph starting at <prev>, and the
953 * forwards-subgraph starting at <next>:
955 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ
,
956 LOCK_ENABLED_SOFTIRQS
, "soft"))
959 * Prove that the new dependency does not connect a softirq-safe-read
960 * lock with a softirq-unsafe lock - to achieve this we search
961 * the backwards-subgraph starting at <prev>, and the
962 * forwards-subgraph starting at <next>:
964 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ_READ
,
965 LOCK_ENABLED_SOFTIRQS
, "soft"))
969 * For recursive read-locks we do all the dependency checks,
970 * but we dont store read-triggered dependencies (only
971 * write-triggered dependencies). This ensures that only the
972 * write-side dependencies matter, and that if for example a
973 * write-lock never takes any other locks, then the reads are
974 * equivalent to a NOP.
976 if (next
->read
== 2 || prev
->read
== 2)
979 * Is the <prev> -> <next> dependency already present?
981 * (this may occur even though this is a new chain: consider
982 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
983 * chains - the second one will be new, but L1 already has
984 * L2 added to its dependency list, due to the first chain.)
986 list_for_each_entry(entry
, &prev
->class->locks_after
, entry
) {
987 if (entry
->class == next
->class) {
995 * Ok, all validations passed, add the new lock
996 * to the previous lock's dependency list:
998 ret
= add_lock_to_list(prev
->class, next
->class,
999 &prev
->class->locks_after
, next
->acquire_ip
, distance
);
1004 ret
= add_lock_to_list(next
->class, prev
->class,
1005 &next
->class->locks_before
, next
->acquire_ip
, distance
);
1010 * Debugging printouts:
1012 if (verbose(prev
->class) || verbose(next
->class)) {
1014 printk("\n new dependency: ");
1015 print_lock_name(prev
->class);
1017 print_lock_name(next
->class);
1020 return graph_lock();
1026 * Add the dependency to all directly-previous locks that are 'relevant'.
1027 * The ones that are relevant are (in increasing distance from curr):
1028 * all consecutive trylock entries and the final non-trylock entry - or
1029 * the end of this context's lock-chain - whichever comes first.
1032 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1034 int depth
= curr
->lockdep_depth
;
1035 struct held_lock
*hlock
;
1040 * Depth must not be zero for a non-head lock:
1045 * At least two relevant locks must exist for this
1048 if (curr
->held_locks
[depth
].irq_context
!=
1049 curr
->held_locks
[depth
-1].irq_context
)
1053 int distance
= curr
->lockdep_depth
- depth
+ 1;
1054 hlock
= curr
->held_locks
+ depth
-1;
1056 * Only non-recursive-read entries get new dependencies
1059 if (hlock
->read
!= 2) {
1060 if (!check_prev_add(curr
, hlock
, next
, distance
))
1063 * Stop after the first non-trylock entry,
1064 * as non-trylock entries have added their
1065 * own direct dependencies already, so this
1066 * lock is connected to them indirectly:
1068 if (!hlock
->trylock
)
1073 * End of lock-stack?
1078 * Stop the search if we cross into another context:
1080 if (curr
->held_locks
[depth
].irq_context
!=
1081 curr
->held_locks
[depth
-1].irq_context
)
1086 if (!debug_locks_off_graph_unlock())
1096 * Is this the address of a static object:
1098 static int static_obj(void *obj
)
1100 unsigned long start
= (unsigned long) &_stext
,
1101 end
= (unsigned long) &_end
,
1102 addr
= (unsigned long) obj
;
1110 if ((addr
>= start
) && (addr
< end
))
1117 for_each_possible_cpu(i
) {
1118 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
1119 end
= (unsigned long) &__per_cpu_start
+ PERCPU_ENOUGH_ROOM
1120 + per_cpu_offset(i
);
1122 if ((addr
>= start
) && (addr
< end
))
1130 return is_module_address(addr
);
1134 * To make lock name printouts unique, we calculate a unique
1135 * class->name_version generation counter:
1137 static int count_matching_names(struct lock_class
*new_class
)
1139 struct lock_class
*class;
1142 if (!new_class
->name
)
1145 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
1146 if (new_class
->key
- new_class
->subclass
== class->key
)
1147 return class->name_version
;
1148 if (class->name
&& !strcmp(class->name
, new_class
->name
))
1149 count
= max(count
, class->name_version
);
1156 * Register a lock's class in the hash-table, if the class is not present
1157 * yet. Otherwise we look it up. We cache the result in the lock object
1158 * itself, so actual lookup of the hash should be once per lock object.
1160 static inline struct lock_class
*
1161 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
1163 struct lockdep_subclass_key
*key
;
1164 struct list_head
*hash_head
;
1165 struct lock_class
*class;
1167 #ifdef CONFIG_DEBUG_LOCKDEP
1169 * If the architecture calls into lockdep before initializing
1170 * the hashes then we'll warn about it later. (we cannot printk
1173 if (unlikely(!lockdep_initialized
)) {
1175 lockdep_init_error
= 1;
1180 * Static locks do not have their class-keys yet - for them the key
1181 * is the lock object itself:
1183 if (unlikely(!lock
->key
))
1184 lock
->key
= (void *)lock
;
1187 * NOTE: the class-key must be unique. For dynamic locks, a static
1188 * lock_class_key variable is passed in through the mutex_init()
1189 * (or spin_lock_init()) call - which acts as the key. For static
1190 * locks we use the lock object itself as the key.
1192 BUILD_BUG_ON(sizeof(struct lock_class_key
) > sizeof(struct lock_class
));
1194 key
= lock
->key
->subkeys
+ subclass
;
1196 hash_head
= classhashentry(key
);
1199 * We can walk the hash lockfree, because the hash only
1200 * grows, and we are careful when adding entries to the end:
1202 list_for_each_entry(class, hash_head
, hash_entry
)
1203 if (class->key
== key
)
1210 * Register a lock's class in the hash-table, if the class is not present
1211 * yet. Otherwise we look it up. We cache the result in the lock object
1212 * itself, so actual lookup of the hash should be once per lock object.
1214 static inline struct lock_class
*
1215 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
, int force
)
1217 struct lockdep_subclass_key
*key
;
1218 struct list_head
*hash_head
;
1219 struct lock_class
*class;
1220 unsigned long flags
;
1222 class = look_up_lock_class(lock
, subclass
);
1227 * Debug-check: all keys must be persistent!
1229 if (!static_obj(lock
->key
)) {
1231 printk("INFO: trying to register non-static key.\n");
1232 printk("the code is fine but needs lockdep annotation.\n");
1233 printk("turning off the locking correctness validator.\n");
1239 key
= lock
->key
->subkeys
+ subclass
;
1240 hash_head
= classhashentry(key
);
1242 raw_local_irq_save(flags
);
1243 if (!graph_lock()) {
1244 raw_local_irq_restore(flags
);
1248 * We have to do the hash-walk again, to avoid races
1251 list_for_each_entry(class, hash_head
, hash_entry
)
1252 if (class->key
== key
)
1253 goto out_unlock_set
;
1255 * Allocate a new key from the static array, and add it to
1258 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
1259 if (!debug_locks_off_graph_unlock()) {
1260 raw_local_irq_restore(flags
);
1263 raw_local_irq_restore(flags
);
1265 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
1266 printk("turning off the locking correctness validator.\n");
1269 class = lock_classes
+ nr_lock_classes
++;
1270 debug_atomic_inc(&nr_unused_locks
);
1272 class->name
= lock
->name
;
1273 class->subclass
= subclass
;
1274 INIT_LIST_HEAD(&class->lock_entry
);
1275 INIT_LIST_HEAD(&class->locks_before
);
1276 INIT_LIST_HEAD(&class->locks_after
);
1277 class->name_version
= count_matching_names(class);
1279 * We use RCU's safe list-add method to make
1280 * parallel walking of the hash-list safe:
1282 list_add_tail_rcu(&class->hash_entry
, hash_head
);
1284 if (verbose(class)) {
1286 raw_local_irq_restore(flags
);
1288 printk("\nnew class %p: %s", class->key
, class->name
);
1289 if (class->name_version
> 1)
1290 printk("#%d", class->name_version
);
1294 raw_local_irq_save(flags
);
1295 if (!graph_lock()) {
1296 raw_local_irq_restore(flags
);
1302 raw_local_irq_restore(flags
);
1304 if (!subclass
|| force
)
1305 lock
->class_cache
= class;
1307 if (DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
))
1314 * Look up a dependency chain. If the key is not present yet then
1315 * add it and return 0 - in this case the new dependency chain is
1316 * validated. If the key is already hashed, return 1.
1318 static inline int lookup_chain_cache(u64 chain_key
, struct lock_class
*class)
1320 struct list_head
*hash_head
= chainhashentry(chain_key
);
1321 struct lock_chain
*chain
;
1323 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1326 * We can walk it lock-free, because entries only get added
1329 list_for_each_entry(chain
, hash_head
, entry
) {
1330 if (chain
->chain_key
== chain_key
) {
1332 debug_atomic_inc(&chain_lookup_hits
);
1333 if (very_verbose(class))
1334 printk("\nhash chain already cached, key: "
1335 "%016Lx tail class: [%p] %s\n",
1336 (unsigned long long)chain_key
,
1337 class->key
, class->name
);
1341 if (very_verbose(class))
1342 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1343 (unsigned long long)chain_key
, class->key
, class->name
);
1345 * Allocate a new chain entry from the static array, and add
1351 * We have to walk the chain again locked - to avoid duplicates:
1353 list_for_each_entry(chain
, hash_head
, entry
) {
1354 if (chain
->chain_key
== chain_key
) {
1359 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1360 if (!debug_locks_off_graph_unlock())
1363 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1364 printk("turning off the locking correctness validator.\n");
1367 chain
= lock_chains
+ nr_lock_chains
++;
1368 chain
->chain_key
= chain_key
;
1369 list_add_tail_rcu(&chain
->entry
, hash_head
);
1370 debug_atomic_inc(&chain_lookup_misses
);
1371 #ifdef CONFIG_TRACE_IRQFLAGS
1372 if (current
->hardirq_context
)
1373 nr_hardirq_chains
++;
1375 if (current
->softirq_context
)
1376 nr_softirq_chains
++;
1378 nr_process_chains
++;
1381 nr_process_chains
++;
1388 * We are building curr_chain_key incrementally, so double-check
1389 * it from scratch, to make sure that it's done correctly:
1391 static void check_chain_key(struct task_struct
*curr
)
1393 #ifdef CONFIG_DEBUG_LOCKDEP
1394 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1398 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1399 hlock
= curr
->held_locks
+ i
;
1400 if (chain_key
!= hlock
->prev_chain_key
) {
1402 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1403 curr
->lockdep_depth
, i
,
1404 (unsigned long long)chain_key
,
1405 (unsigned long long)hlock
->prev_chain_key
);
1409 id
= hlock
->class - lock_classes
;
1410 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
1413 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1414 hlock
->irq_context
))
1416 chain_key
= iterate_chain_key(chain_key
, id
);
1419 if (chain_key
!= curr
->curr_chain_key
) {
1421 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1422 curr
->lockdep_depth
, i
,
1423 (unsigned long long)chain_key
,
1424 (unsigned long long)curr
->curr_chain_key
);
1430 #ifdef CONFIG_TRACE_IRQFLAGS
1433 * print irq inversion bug:
1436 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
1437 struct held_lock
*this, int forwards
,
1438 const char *irqclass
)
1440 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1443 printk("\n=========================================================\n");
1444 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1445 print_kernel_version();
1446 printk( "---------------------------------------------------------\n");
1447 printk("%s/%d just changed the state of lock:\n",
1448 curr
->comm
, curr
->pid
);
1451 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass
);
1453 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass
);
1454 print_lock_name(other
);
1455 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1457 printk("\nother info that might help us debug this:\n");
1458 lockdep_print_held_locks(curr
);
1460 printk("\nthe first lock's dependencies:\n");
1461 print_lock_dependencies(this->class, 0);
1463 printk("\nthe second lock's dependencies:\n");
1464 print_lock_dependencies(other
, 0);
1466 printk("\nstack backtrace:\n");
1473 * Prove that in the forwards-direction subgraph starting at <this>
1474 * there is no lock matching <mask>:
1477 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
1478 enum lock_usage_bit bit
, const char *irqclass
)
1482 find_usage_bit
= bit
;
1483 /* fills in <forwards_match> */
1484 ret
= find_usage_forwards(this->class, 0);
1485 if (!ret
|| ret
== 1)
1488 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
1492 * Prove that in the backwards-direction subgraph starting at <this>
1493 * there is no lock matching <mask>:
1496 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
1497 enum lock_usage_bit bit
, const char *irqclass
)
1501 find_usage_bit
= bit
;
1502 /* fills in <backwards_match> */
1503 ret
= find_usage_backwards(this->class, 0);
1504 if (!ret
|| ret
== 1)
1507 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
1510 void print_irqtrace_events(struct task_struct
*curr
)
1512 printk("irq event stamp: %u\n", curr
->irq_events
);
1513 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
1514 print_ip_sym(curr
->hardirq_enable_ip
);
1515 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
1516 print_ip_sym(curr
->hardirq_disable_ip
);
1517 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
1518 print_ip_sym(curr
->softirq_enable_ip
);
1519 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
1520 print_ip_sym(curr
->softirq_disable_ip
);
1526 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1527 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1529 if (!debug_locks_off_graph_unlock() || debug_locks_silent
)
1532 printk("\n=================================\n");
1533 printk( "[ INFO: inconsistent lock state ]\n");
1534 print_kernel_version();
1535 printk( "---------------------------------\n");
1537 printk("inconsistent {%s} -> {%s} usage.\n",
1538 usage_str
[prev_bit
], usage_str
[new_bit
]);
1540 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1541 curr
->comm
, curr
->pid
,
1542 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1543 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1544 trace_hardirqs_enabled(curr
),
1545 trace_softirqs_enabled(curr
));
1548 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1549 print_stack_trace(this->class->usage_traces
+ prev_bit
, 1);
1551 print_irqtrace_events(curr
);
1552 printk("\nother info that might help us debug this:\n");
1553 lockdep_print_held_locks(curr
);
1555 printk("\nstack backtrace:\n");
1562 * Print out an error if an invalid bit is set:
1565 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1566 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1568 if (unlikely(this->class->usage_mask
& (1 << bad_bit
)))
1569 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1573 #define STRICT_READ_CHECKS 1
1576 * Mark a lock with a usage bit, and validate the state transition:
1578 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1579 enum lock_usage_bit new_bit
, unsigned long ip
)
1581 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
1584 * If already set then do not dirty the cacheline,
1585 * nor do any checks:
1587 if (likely(this->class->usage_mask
& new_mask
))
1593 * Make sure we didnt race:
1595 if (unlikely(this->class->usage_mask
& new_mask
)) {
1600 this->class->usage_mask
|= new_mask
;
1602 #ifdef CONFIG_TRACE_IRQFLAGS
1603 if (new_bit
== LOCK_ENABLED_HARDIRQS
||
1604 new_bit
== LOCK_ENABLED_HARDIRQS_READ
)
1605 ip
= curr
->hardirq_enable_ip
;
1606 else if (new_bit
== LOCK_ENABLED_SOFTIRQS
||
1607 new_bit
== LOCK_ENABLED_SOFTIRQS_READ
)
1608 ip
= curr
->softirq_enable_ip
;
1610 if (!save_trace(this->class->usage_traces
+ new_bit
))
1614 #ifdef CONFIG_TRACE_IRQFLAGS
1615 case LOCK_USED_IN_HARDIRQ
:
1616 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1618 if (!valid_state(curr
, this, new_bit
,
1619 LOCK_ENABLED_HARDIRQS_READ
))
1622 * just marked it hardirq-safe, check that this lock
1623 * took no hardirq-unsafe lock in the past:
1625 if (!check_usage_forwards(curr
, this,
1626 LOCK_ENABLED_HARDIRQS
, "hard"))
1628 #if STRICT_READ_CHECKS
1630 * just marked it hardirq-safe, check that this lock
1631 * took no hardirq-unsafe-read lock in the past:
1633 if (!check_usage_forwards(curr
, this,
1634 LOCK_ENABLED_HARDIRQS_READ
, "hard-read"))
1637 if (hardirq_verbose(this->class))
1640 case LOCK_USED_IN_SOFTIRQ
:
1641 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1643 if (!valid_state(curr
, this, new_bit
,
1644 LOCK_ENABLED_SOFTIRQS_READ
))
1647 * just marked it softirq-safe, check that this lock
1648 * took no softirq-unsafe lock in the past:
1650 if (!check_usage_forwards(curr
, this,
1651 LOCK_ENABLED_SOFTIRQS
, "soft"))
1653 #if STRICT_READ_CHECKS
1655 * just marked it softirq-safe, check that this lock
1656 * took no softirq-unsafe-read lock in the past:
1658 if (!check_usage_forwards(curr
, this,
1659 LOCK_ENABLED_SOFTIRQS_READ
, "soft-read"))
1662 if (softirq_verbose(this->class))
1665 case LOCK_USED_IN_HARDIRQ_READ
:
1666 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1669 * just marked it hardirq-read-safe, check that this lock
1670 * took no hardirq-unsafe lock in the past:
1672 if (!check_usage_forwards(curr
, this,
1673 LOCK_ENABLED_HARDIRQS
, "hard"))
1675 if (hardirq_verbose(this->class))
1678 case LOCK_USED_IN_SOFTIRQ_READ
:
1679 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1682 * just marked it softirq-read-safe, check that this lock
1683 * took no softirq-unsafe lock in the past:
1685 if (!check_usage_forwards(curr
, this,
1686 LOCK_ENABLED_SOFTIRQS
, "soft"))
1688 if (softirq_verbose(this->class))
1691 case LOCK_ENABLED_HARDIRQS
:
1692 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1694 if (!valid_state(curr
, this, new_bit
,
1695 LOCK_USED_IN_HARDIRQ_READ
))
1698 * just marked it hardirq-unsafe, check that no hardirq-safe
1699 * lock in the system ever took it in the past:
1701 if (!check_usage_backwards(curr
, this,
1702 LOCK_USED_IN_HARDIRQ
, "hard"))
1704 #if STRICT_READ_CHECKS
1706 * just marked it hardirq-unsafe, check that no
1707 * hardirq-safe-read lock in the system ever took
1710 if (!check_usage_backwards(curr
, this,
1711 LOCK_USED_IN_HARDIRQ_READ
, "hard-read"))
1714 if (hardirq_verbose(this->class))
1717 case LOCK_ENABLED_SOFTIRQS
:
1718 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1720 if (!valid_state(curr
, this, new_bit
,
1721 LOCK_USED_IN_SOFTIRQ_READ
))
1724 * just marked it softirq-unsafe, check that no softirq-safe
1725 * lock in the system ever took it in the past:
1727 if (!check_usage_backwards(curr
, this,
1728 LOCK_USED_IN_SOFTIRQ
, "soft"))
1730 #if STRICT_READ_CHECKS
1732 * just marked it softirq-unsafe, check that no
1733 * softirq-safe-read lock in the system ever took
1736 if (!check_usage_backwards(curr
, this,
1737 LOCK_USED_IN_SOFTIRQ_READ
, "soft-read"))
1740 if (softirq_verbose(this->class))
1743 case LOCK_ENABLED_HARDIRQS_READ
:
1744 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1746 #if STRICT_READ_CHECKS
1748 * just marked it hardirq-read-unsafe, check that no
1749 * hardirq-safe lock in the system ever took it in the past:
1751 if (!check_usage_backwards(curr
, this,
1752 LOCK_USED_IN_HARDIRQ
, "hard"))
1755 if (hardirq_verbose(this->class))
1758 case LOCK_ENABLED_SOFTIRQS_READ
:
1759 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1761 #if STRICT_READ_CHECKS
1763 * just marked it softirq-read-unsafe, check that no
1764 * softirq-safe lock in the system ever took it in the past:
1766 if (!check_usage_backwards(curr
, this,
1767 LOCK_USED_IN_SOFTIRQ
, "soft"))
1770 if (softirq_verbose(this->class))
1776 * Add it to the global list of classes:
1778 list_add_tail_rcu(&this->class->lock_entry
, &all_lock_classes
);
1779 debug_atomic_dec(&nr_unused_locks
);
1782 if (!debug_locks_off_graph_unlock())
1791 * We must printk outside of the graph_lock:
1794 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
1796 print_irqtrace_events(curr
);
1803 #ifdef CONFIG_TRACE_IRQFLAGS
1805 * Mark all held locks with a usage bit:
1808 mark_held_locks(struct task_struct
*curr
, int hardirq
, unsigned long ip
)
1810 enum lock_usage_bit usage_bit
;
1811 struct held_lock
*hlock
;
1814 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1815 hlock
= curr
->held_locks
+ i
;
1819 usage_bit
= LOCK_ENABLED_HARDIRQS_READ
;
1821 usage_bit
= LOCK_ENABLED_HARDIRQS
;
1824 usage_bit
= LOCK_ENABLED_SOFTIRQS_READ
;
1826 usage_bit
= LOCK_ENABLED_SOFTIRQS
;
1828 if (!mark_lock(curr
, hlock
, usage_bit
, ip
))
1836 * Debugging helper: via this flag we know that we are in
1837 * 'early bootup code', and will warn about any invalid irqs-on event:
1839 static int early_boot_irqs_enabled
;
1841 void early_boot_irqs_off(void)
1843 early_boot_irqs_enabled
= 0;
1846 void early_boot_irqs_on(void)
1848 early_boot_irqs_enabled
= 1;
1852 * Hardirqs will be enabled:
1854 void trace_hardirqs_on(void)
1856 struct task_struct
*curr
= current
;
1859 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
1862 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
1865 if (unlikely(curr
->hardirqs_enabled
)) {
1866 debug_atomic_inc(&redundant_hardirqs_on
);
1869 /* we'll do an OFF -> ON transition: */
1870 curr
->hardirqs_enabled
= 1;
1871 ip
= (unsigned long) __builtin_return_address(0);
1873 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1875 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
1878 * We are going to turn hardirqs on, so set the
1879 * usage bit for all held locks:
1881 if (!mark_held_locks(curr
, 1, ip
))
1884 * If we have softirqs enabled, then set the usage
1885 * bit for all held locks. (disabled hardirqs prevented
1886 * this bit from being set before)
1888 if (curr
->softirqs_enabled
)
1889 if (!mark_held_locks(curr
, 0, ip
))
1892 curr
->hardirq_enable_ip
= ip
;
1893 curr
->hardirq_enable_event
= ++curr
->irq_events
;
1894 debug_atomic_inc(&hardirqs_on_events
);
1897 EXPORT_SYMBOL(trace_hardirqs_on
);
1900 * Hardirqs were disabled:
1902 void trace_hardirqs_off(void)
1904 struct task_struct
*curr
= current
;
1906 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
1909 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1912 if (curr
->hardirqs_enabled
) {
1914 * We have done an ON -> OFF transition:
1916 curr
->hardirqs_enabled
= 0;
1917 curr
->hardirq_disable_ip
= _RET_IP_
;
1918 curr
->hardirq_disable_event
= ++curr
->irq_events
;
1919 debug_atomic_inc(&hardirqs_off_events
);
1921 debug_atomic_inc(&redundant_hardirqs_off
);
1924 EXPORT_SYMBOL(trace_hardirqs_off
);
1927 * Softirqs will be enabled:
1929 void trace_softirqs_on(unsigned long ip
)
1931 struct task_struct
*curr
= current
;
1933 if (unlikely(!debug_locks
))
1936 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1939 if (curr
->softirqs_enabled
) {
1940 debug_atomic_inc(&redundant_softirqs_on
);
1945 * We'll do an OFF -> ON transition:
1947 curr
->softirqs_enabled
= 1;
1948 curr
->softirq_enable_ip
= ip
;
1949 curr
->softirq_enable_event
= ++curr
->irq_events
;
1950 debug_atomic_inc(&softirqs_on_events
);
1952 * We are going to turn softirqs on, so set the
1953 * usage bit for all held locks, if hardirqs are
1956 if (curr
->hardirqs_enabled
)
1957 mark_held_locks(curr
, 0, ip
);
1961 * Softirqs were disabled:
1963 void trace_softirqs_off(unsigned long ip
)
1965 struct task_struct
*curr
= current
;
1967 if (unlikely(!debug_locks
))
1970 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1973 if (curr
->softirqs_enabled
) {
1975 * We have done an ON -> OFF transition:
1977 curr
->softirqs_enabled
= 0;
1978 curr
->softirq_disable_ip
= ip
;
1979 curr
->softirq_disable_event
= ++curr
->irq_events
;
1980 debug_atomic_inc(&softirqs_off_events
);
1981 DEBUG_LOCKS_WARN_ON(!softirq_count());
1983 debug_atomic_inc(&redundant_softirqs_off
);
1989 * Initialize a lock instance's lock-class mapping info:
1991 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
1992 struct lock_class_key
*key
, int subclass
)
1994 if (unlikely(!debug_locks
))
1997 if (DEBUG_LOCKS_WARN_ON(!key
))
1999 if (DEBUG_LOCKS_WARN_ON(!name
))
2002 * Sanity check, the lock-class key must be persistent:
2004 if (!static_obj(key
)) {
2005 printk("BUG: key %p not in .data!\n", key
);
2006 DEBUG_LOCKS_WARN_ON(1);
2011 lock
->class_cache
= NULL
;
2013 register_lock_class(lock
, subclass
, 1);
2016 EXPORT_SYMBOL_GPL(lockdep_init_map
);
2019 * This gets called for every mutex_lock*()/spin_lock*() operation.
2020 * We maintain the dependency maps and validate the locking attempt:
2022 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2023 int trylock
, int read
, int check
, int hardirqs_off
,
2026 struct task_struct
*curr
= current
;
2027 struct lock_class
*class = NULL
;
2028 struct held_lock
*hlock
;
2029 unsigned int depth
, id
;
2033 if (unlikely(!debug_locks
))
2036 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2039 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
2041 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2042 printk("turning off the locking correctness validator.\n");
2047 class = lock
->class_cache
;
2049 * Not cached yet or subclass?
2051 if (unlikely(!class)) {
2052 class = register_lock_class(lock
, subclass
, 0);
2056 debug_atomic_inc((atomic_t
*)&class->ops
);
2057 if (very_verbose(class)) {
2058 printk("\nacquire class [%p] %s", class->key
, class->name
);
2059 if (class->name_version
> 1)
2060 printk("#%d", class->name_version
);
2066 * Add the lock to the list of currently held locks.
2067 * (we dont increase the depth just yet, up until the
2068 * dependency checks are done)
2070 depth
= curr
->lockdep_depth
;
2071 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2074 hlock
= curr
->held_locks
+ depth
;
2076 hlock
->class = class;
2077 hlock
->acquire_ip
= ip
;
2078 hlock
->instance
= lock
;
2079 hlock
->trylock
= trylock
;
2081 hlock
->check
= check
;
2082 hlock
->hardirqs_off
= hardirqs_off
;
2086 #ifdef CONFIG_TRACE_IRQFLAGS
2088 * If non-trylock use in a hardirq or softirq context, then
2089 * mark the lock as used in these contexts:
2093 if (curr
->hardirq_context
)
2094 if (!mark_lock(curr
, hlock
,
2095 LOCK_USED_IN_HARDIRQ_READ
, ip
))
2097 if (curr
->softirq_context
)
2098 if (!mark_lock(curr
, hlock
,
2099 LOCK_USED_IN_SOFTIRQ_READ
, ip
))
2102 if (curr
->hardirq_context
)
2103 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
, ip
))
2105 if (curr
->softirq_context
)
2106 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
, ip
))
2110 if (!hardirqs_off
) {
2112 if (!mark_lock(curr
, hlock
,
2113 LOCK_ENABLED_HARDIRQS_READ
, ip
))
2115 if (curr
->softirqs_enabled
)
2116 if (!mark_lock(curr
, hlock
,
2117 LOCK_ENABLED_SOFTIRQS_READ
, ip
))
2120 if (!mark_lock(curr
, hlock
,
2121 LOCK_ENABLED_HARDIRQS
, ip
))
2123 if (curr
->softirqs_enabled
)
2124 if (!mark_lock(curr
, hlock
,
2125 LOCK_ENABLED_SOFTIRQS
, ip
))
2130 /* mark it as used: */
2131 if (!mark_lock(curr
, hlock
, LOCK_USED
, ip
))
2135 * Calculate the chain hash: it's the combined has of all the
2136 * lock keys along the dependency chain. We save the hash value
2137 * at every step so that we can get the current hash easily
2138 * after unlock. The chain hash is then used to cache dependency
2141 * The 'key ID' is what is the most compact key value to drive
2142 * the hash, not class->key.
2144 id
= class - lock_classes
;
2145 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2148 chain_key
= curr
->curr_chain_key
;
2150 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2155 hlock
->prev_chain_key
= chain_key
;
2157 #ifdef CONFIG_TRACE_IRQFLAGS
2159 * Keep track of points where we cross into an interrupt context:
2161 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2162 curr
->softirq_context
;
2164 struct held_lock
*prev_hlock
;
2166 prev_hlock
= curr
->held_locks
+ depth
-1;
2168 * If we cross into another context, reset the
2169 * hash key (this also prevents the checking and the
2170 * adding of the dependency to 'prev'):
2172 if (prev_hlock
->irq_context
!= hlock
->irq_context
) {
2178 chain_key
= iterate_chain_key(chain_key
, id
);
2179 curr
->curr_chain_key
= chain_key
;
2182 * Trylock needs to maintain the stack of held locks, but it
2183 * does not add new dependencies, because trylock can be done
2186 * We look up the chain_key and do the O(N^2) check and update of
2187 * the dependencies only if this is a new dependency chain.
2188 * (If lookup_chain_cache() returns with 1 it acquires
2189 * graph_lock for us)
2191 if (!trylock
&& (check
== 2) && lookup_chain_cache(chain_key
, class)) {
2193 * Check whether last held lock:
2195 * - is irq-safe, if this lock is irq-unsafe
2196 * - is softirq-safe, if this lock is hardirq-unsafe
2198 * And check whether the new lock's dependency graph
2199 * could lead back to the previous lock.
2201 * any of these scenarios could lead to a deadlock. If
2204 int ret
= check_deadlock(curr
, hlock
, lock
, read
);
2209 * Mark recursive read, as we jump over it when
2210 * building dependencies (just like we jump over
2216 * Add dependency only if this lock is not the head
2217 * of the chain, and if it's not a secondary read-lock:
2219 if (!chain_head
&& ret
!= 2)
2220 if (!check_prevs_add(curr
, hlock
))
2224 /* after lookup_chain_cache(): */
2225 if (unlikely(!debug_locks
))
2228 curr
->lockdep_depth
++;
2229 check_chain_key(curr
);
2230 #ifdef CONFIG_DEBUG_LOCKDEP
2231 if (unlikely(!debug_locks
))
2234 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2236 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2237 printk("turning off the locking correctness validator.\n");
2241 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2242 max_lockdep_depth
= curr
->lockdep_depth
;
2248 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2251 if (!debug_locks_off())
2253 if (debug_locks_silent
)
2256 printk("\n=====================================\n");
2257 printk( "[ BUG: bad unlock balance detected! ]\n");
2258 printk( "-------------------------------------\n");
2259 printk("%s/%d is trying to release lock (",
2260 curr
->comm
, curr
->pid
);
2261 print_lockdep_cache(lock
);
2264 printk("but there are no more locks to release!\n");
2265 printk("\nother info that might help us debug this:\n");
2266 lockdep_print_held_locks(curr
);
2268 printk("\nstack backtrace:\n");
2275 * Common debugging checks for both nested and non-nested unlock:
2277 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2280 if (unlikely(!debug_locks
))
2282 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2285 if (curr
->lockdep_depth
<= 0)
2286 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2292 * Remove the lock to the list of currently held locks in a
2293 * potentially non-nested (out of order) manner. This is a
2294 * relatively rare operation, as all the unlock APIs default
2295 * to nested mode (which uses lock_release()):
2298 lock_release_non_nested(struct task_struct
*curr
,
2299 struct lockdep_map
*lock
, unsigned long ip
)
2301 struct held_lock
*hlock
, *prev_hlock
;
2306 * Check whether the lock exists in the current stack
2309 depth
= curr
->lockdep_depth
;
2310 if (DEBUG_LOCKS_WARN_ON(!depth
))
2314 for (i
= depth
-1; i
>= 0; i
--) {
2315 hlock
= curr
->held_locks
+ i
;
2317 * We must not cross into another context:
2319 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2321 if (hlock
->instance
== lock
)
2325 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2329 * We have the right lock to unlock, 'hlock' points to it.
2330 * Now we remove it from the stack, and add back the other
2331 * entries (if any), recalculating the hash along the way:
2333 curr
->lockdep_depth
= i
;
2334 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2336 for (i
++; i
< depth
; i
++) {
2337 hlock
= curr
->held_locks
+ i
;
2338 if (!__lock_acquire(hlock
->instance
,
2339 hlock
->class->subclass
, hlock
->trylock
,
2340 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2345 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2351 * Remove the lock to the list of currently held locks - this gets
2352 * called on mutex_unlock()/spin_unlock*() (or on a failed
2353 * mutex_lock_interruptible()). This is done for unlocks that nest
2354 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2356 static int lock_release_nested(struct task_struct
*curr
,
2357 struct lockdep_map
*lock
, unsigned long ip
)
2359 struct held_lock
*hlock
;
2363 * Pop off the top of the lock stack:
2365 depth
= curr
->lockdep_depth
- 1;
2366 hlock
= curr
->held_locks
+ depth
;
2369 * Is the unlock non-nested:
2371 if (hlock
->instance
!= lock
)
2372 return lock_release_non_nested(curr
, lock
, ip
);
2373 curr
->lockdep_depth
--;
2375 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2378 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2380 #ifdef CONFIG_DEBUG_LOCKDEP
2381 hlock
->prev_chain_key
= 0;
2382 hlock
->class = NULL
;
2383 hlock
->acquire_ip
= 0;
2384 hlock
->irq_context
= 0;
2390 * Remove the lock to the list of currently held locks - this gets
2391 * called on mutex_unlock()/spin_unlock*() (or on a failed
2392 * mutex_lock_interruptible()). This is done for unlocks that nest
2393 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2396 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2398 struct task_struct
*curr
= current
;
2400 if (!check_unlock(curr
, lock
, ip
))
2404 if (!lock_release_nested(curr
, lock
, ip
))
2407 if (!lock_release_non_nested(curr
, lock
, ip
))
2411 check_chain_key(curr
);
2415 * Check whether we follow the irq-flags state precisely:
2417 static void check_flags(unsigned long flags
)
2419 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2423 if (irqs_disabled_flags(flags
))
2424 DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
);
2426 DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
);
2429 * We dont accurately track softirq state in e.g.
2430 * hardirq contexts (such as on 4KSTACKS), so only
2431 * check if not in hardirq contexts:
2433 if (!hardirq_count()) {
2434 if (softirq_count())
2435 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
2437 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
2441 print_irqtrace_events(current
);
2446 * We are not always called with irqs disabled - do that here,
2447 * and also avoid lockdep recursion:
2449 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2450 int trylock
, int read
, int check
, unsigned long ip
)
2452 unsigned long flags
;
2454 if (unlikely(current
->lockdep_recursion
))
2457 raw_local_irq_save(flags
);
2460 current
->lockdep_recursion
= 1;
2461 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
2462 irqs_disabled_flags(flags
), ip
);
2463 current
->lockdep_recursion
= 0;
2464 raw_local_irq_restore(flags
);
2467 EXPORT_SYMBOL_GPL(lock_acquire
);
2469 void lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2471 unsigned long flags
;
2473 if (unlikely(current
->lockdep_recursion
))
2476 raw_local_irq_save(flags
);
2478 current
->lockdep_recursion
= 1;
2479 __lock_release(lock
, nested
, ip
);
2480 current
->lockdep_recursion
= 0;
2481 raw_local_irq_restore(flags
);
2484 EXPORT_SYMBOL_GPL(lock_release
);
2487 * Used by the testsuite, sanitize the validator state
2488 * after a simulated failure:
2491 void lockdep_reset(void)
2493 unsigned long flags
;
2496 raw_local_irq_save(flags
);
2497 current
->curr_chain_key
= 0;
2498 current
->lockdep_depth
= 0;
2499 current
->lockdep_recursion
= 0;
2500 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
2501 nr_hardirq_chains
= 0;
2502 nr_softirq_chains
= 0;
2503 nr_process_chains
= 0;
2505 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
2506 INIT_LIST_HEAD(chainhash_table
+ i
);
2507 raw_local_irq_restore(flags
);
2510 static void zap_class(struct lock_class
*class)
2515 * Remove all dependencies this lock is
2518 for (i
= 0; i
< nr_list_entries
; i
++) {
2519 if (list_entries
[i
].class == class)
2520 list_del_rcu(&list_entries
[i
].entry
);
2523 * Unhash the class and remove it from the all_lock_classes list:
2525 list_del_rcu(&class->hash_entry
);
2526 list_del_rcu(&class->lock_entry
);
2530 static inline int within(void *addr
, void *start
, unsigned long size
)
2532 return addr
>= start
&& addr
< start
+ size
;
2535 void lockdep_free_key_range(void *start
, unsigned long size
)
2537 struct lock_class
*class, *next
;
2538 struct list_head
*head
;
2539 unsigned long flags
;
2542 raw_local_irq_save(flags
);
2546 * Unhash all classes that were created by this module:
2548 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
2549 head
= classhash_table
+ i
;
2550 if (list_empty(head
))
2552 list_for_each_entry_safe(class, next
, head
, hash_entry
)
2553 if (within(class->key
, start
, size
))
2558 raw_local_irq_restore(flags
);
2561 void lockdep_reset_lock(struct lockdep_map
*lock
)
2563 struct lock_class
*class, *next
;
2564 struct list_head
*head
;
2565 unsigned long flags
;
2568 raw_local_irq_save(flags
);
2571 * Remove all classes this lock might have:
2573 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
2575 * If the class exists we look it up and zap it:
2577 class = look_up_lock_class(lock
, j
);
2582 * Debug check: in the end all mapped classes should
2586 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
2587 head
= classhash_table
+ i
;
2588 if (list_empty(head
))
2590 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
2591 if (unlikely(class == lock
->class_cache
)) {
2592 if (debug_locks_off_graph_unlock())
2601 raw_local_irq_restore(flags
);
2604 void lockdep_init(void)
2609 * Some architectures have their own start_kernel()
2610 * code which calls lockdep_init(), while we also
2611 * call lockdep_init() from the start_kernel() itself,
2612 * and we want to initialize the hashes only once:
2614 if (lockdep_initialized
)
2617 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
2618 INIT_LIST_HEAD(classhash_table
+ i
);
2620 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
2621 INIT_LIST_HEAD(chainhash_table
+ i
);
2623 lockdep_initialized
= 1;
2626 void __init
lockdep_info(void)
2628 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
2630 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
2631 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
2632 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
2633 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
2634 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
2635 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
2636 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
2638 printk(" memory used by lock dependency info: %lu kB\n",
2639 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
2640 sizeof(struct list_head
) * CLASSHASH_SIZE
+
2641 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
2642 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
2643 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
2645 printk(" per task-struct memory footprint: %lu bytes\n",
2646 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
2648 #ifdef CONFIG_DEBUG_LOCKDEP
2649 if (lockdep_init_error
)
2650 printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n");
2654 static inline int in_range(const void *start
, const void *addr
, const void *end
)
2656 return addr
>= start
&& addr
<= end
;
2660 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
2661 const void *mem_to
, struct held_lock
*hlock
)
2663 if (!debug_locks_off())
2665 if (debug_locks_silent
)
2668 printk("\n=========================\n");
2669 printk( "[ BUG: held lock freed! ]\n");
2670 printk( "-------------------------\n");
2671 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
2672 curr
->comm
, curr
->pid
, mem_from
, mem_to
-1);
2674 lockdep_print_held_locks(curr
);
2676 printk("\nstack backtrace:\n");
2681 * Called when kernel memory is freed (or unmapped), or if a lock
2682 * is destroyed or reinitialized - this code checks whether there is
2683 * any held lock in the memory range of <from> to <to>:
2685 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
2687 const void *mem_to
= mem_from
+ mem_len
, *lock_from
, *lock_to
;
2688 struct task_struct
*curr
= current
;
2689 struct held_lock
*hlock
;
2690 unsigned long flags
;
2693 if (unlikely(!debug_locks
))
2696 local_irq_save(flags
);
2697 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2698 hlock
= curr
->held_locks
+ i
;
2700 lock_from
= (void *)hlock
->instance
;
2701 lock_to
= (void *)(hlock
->instance
+ 1);
2703 if (!in_range(mem_from
, lock_from
, mem_to
) &&
2704 !in_range(mem_from
, lock_to
, mem_to
))
2707 print_freed_lock_bug(curr
, mem_from
, mem_to
, hlock
);
2710 local_irq_restore(flags
);
2712 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed
);
2714 static void print_held_locks_bug(struct task_struct
*curr
)
2716 if (!debug_locks_off())
2718 if (debug_locks_silent
)
2721 printk("\n=====================================\n");
2722 printk( "[ BUG: lock held at task exit time! ]\n");
2723 printk( "-------------------------------------\n");
2724 printk("%s/%d is exiting with locks still held!\n",
2725 curr
->comm
, curr
->pid
);
2726 lockdep_print_held_locks(curr
);
2728 printk("\nstack backtrace:\n");
2732 void debug_check_no_locks_held(struct task_struct
*task
)
2734 if (unlikely(task
->lockdep_depth
> 0))
2735 print_held_locks_bug(task
);
2738 void debug_show_all_locks(void)
2740 struct task_struct
*g
, *p
;
2744 if (unlikely(!debug_locks
)) {
2745 printk("INFO: lockdep is turned off.\n");
2748 printk("\nShowing all locks held in the system:\n");
2751 * Here we try to get the tasklist_lock as hard as possible,
2752 * if not successful after 2 seconds we ignore it (but keep
2753 * trying). This is to enable a debug printout even if a
2754 * tasklist_lock-holding task deadlocks or crashes.
2757 if (!read_trylock(&tasklist_lock
)) {
2759 printk("hm, tasklist_lock locked, retrying... ");
2762 printk(" #%d", 10-count
);
2766 printk(" ignoring it.\n");
2770 printk(" locked it.\n");
2772 do_each_thread(g
, p
) {
2773 if (p
->lockdep_depth
)
2774 lockdep_print_held_locks(p
);
2776 if (read_trylock(&tasklist_lock
))
2778 } while_each_thread(g
, p
);
2781 printk("=============================================\n\n");
2784 read_unlock(&tasklist_lock
);
2787 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
2789 void debug_show_held_locks(struct task_struct
*task
)
2791 if (unlikely(!debug_locks
)) {
2792 printk("INFO: lockdep is turned off.\n");
2795 lockdep_print_held_locks(task
);
2798 EXPORT_SYMBOL_GPL(debug_show_held_locks
);