4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
10 * this code maps all the lock dependencies as they occur in a live kernel
11 * and will warn about the following classes of locking bugs:
13 * - lock inversion scenarios
14 * - circular lock dependencies
15 * - hardirq/softirq safe/unsafe locking bugs
17 * Bugs are reported even if the current locking scenario does not cause
18 * any deadlock at this point.
20 * I.e. if anytime in the past two locks were taken in a different order,
21 * even if it happened for another task, even if those were different
22 * locks (but of the same class as this lock), this code will detect it.
24 * Thanks to Arjan van de Ven for coming up with the initial idea of
25 * mapping lock dependencies runtime.
27 #include <linux/mutex.h>
28 #include <linux/sched.h>
29 #include <linux/delay.h>
30 #include <linux/module.h>
31 #include <linux/proc_fs.h>
32 #include <linux/seq_file.h>
33 #include <linux/spinlock.h>
34 #include <linux/kallsyms.h>
35 #include <linux/interrupt.h>
36 #include <linux/stacktrace.h>
37 #include <linux/debug_locks.h>
38 #include <linux/irqflags.h>
39 #include <linux/utsname.h>
41 #include <asm/sections.h>
43 #include "lockdep_internals.h"
46 * hash_lock: protects the lockdep hashes and class/list/hash allocators.
48 * This is one of the rare exceptions where it's justified
49 * to use a raw spinlock - we really dont want the spinlock
50 * code to recurse back into the lockdep code.
52 static raw_spinlock_t hash_lock
= (raw_spinlock_t
)__RAW_SPIN_LOCK_UNLOCKED
;
54 static int lockdep_initialized
;
56 unsigned long nr_list_entries
;
57 static struct lock_list list_entries
[MAX_LOCKDEP_ENTRIES
];
60 * Allocate a lockdep entry. (assumes hash_lock held, returns
61 * with NULL on failure)
63 static struct lock_list
*alloc_list_entry(void)
65 if (nr_list_entries
>= MAX_LOCKDEP_ENTRIES
) {
66 __raw_spin_unlock(&hash_lock
);
68 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
69 printk("turning off the locking correctness validator.\n");
72 return list_entries
+ nr_list_entries
++;
76 * All data structures here are protected by the global debug_lock.
78 * Mutex key structs only get allocated, once during bootup, and never
79 * get freed - this significantly simplifies the debugging code.
81 unsigned long nr_lock_classes
;
82 static struct lock_class lock_classes
[MAX_LOCKDEP_KEYS
];
85 * We keep a global list of all lock classes. The list only grows,
86 * never shrinks. The list is only accessed with the lockdep
89 LIST_HEAD(all_lock_classes
);
92 * The lockdep classes are in a hash-table as well, for fast lookup:
94 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
95 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
96 #define CLASSHASH_MASK (CLASSHASH_SIZE - 1)
97 #define __classhashfn(key) ((((unsigned long)key >> CLASSHASH_BITS) + (unsigned long)key) & CLASSHASH_MASK)
98 #define classhashentry(key) (classhash_table + __classhashfn((key)))
100 static struct list_head classhash_table
[CLASSHASH_SIZE
];
102 unsigned long nr_lock_chains
;
103 static struct lock_chain lock_chains
[MAX_LOCKDEP_CHAINS
];
106 * We put the lock dependency chains into a hash-table as well, to cache
109 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
110 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
111 #define CHAINHASH_MASK (CHAINHASH_SIZE - 1)
112 #define __chainhashfn(chain) \
113 (((chain >> CHAINHASH_BITS) + chain) & CHAINHASH_MASK)
114 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
116 static struct list_head chainhash_table
[CHAINHASH_SIZE
];
119 * The hash key of the lock dependency chains is a hash itself too:
120 * it's a hash of all locks taken up to that lock, including that lock.
121 * It's a 64-bit hash, because it's important for the keys to be
124 #define iterate_chain_key(key1, key2) \
125 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
126 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
129 void lockdep_off(void)
131 current
->lockdep_recursion
++;
134 EXPORT_SYMBOL(lockdep_off
);
136 void lockdep_on(void)
138 current
->lockdep_recursion
--;
141 EXPORT_SYMBOL(lockdep_on
);
143 int lockdep_internal(void)
145 return current
->lockdep_recursion
!= 0;
148 EXPORT_SYMBOL(lockdep_internal
);
151 * Debugging switches:
156 # define VERY_VERBOSE 0
160 # define HARDIRQ_VERBOSE 1
161 # define SOFTIRQ_VERBOSE 1
163 # define HARDIRQ_VERBOSE 0
164 # define SOFTIRQ_VERBOSE 0
167 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
169 * Quick filtering for interesting events:
171 static int class_filter(struct lock_class
*class)
175 if (class->name_version
== 1 &&
176 !strcmp(class->name
, "lockname"))
178 if (class->name_version
== 1 &&
179 !strcmp(class->name
, "&struct->lockfield"))
182 /* Allow everything else. 0 would be filter everything else */
187 static int verbose(struct lock_class
*class)
190 return class_filter(class);
195 #ifdef CONFIG_TRACE_IRQFLAGS
197 static int hardirq_verbose(struct lock_class
*class)
200 return class_filter(class);
205 static int softirq_verbose(struct lock_class
*class)
208 return class_filter(class);
216 * Stack-trace: tightly packed array of stack backtrace
217 * addresses. Protected by the hash_lock.
219 unsigned long nr_stack_trace_entries
;
220 static unsigned long stack_trace
[MAX_STACK_TRACE_ENTRIES
];
222 static int save_trace(struct stack_trace
*trace
)
224 trace
->nr_entries
= 0;
225 trace
->max_entries
= MAX_STACK_TRACE_ENTRIES
- nr_stack_trace_entries
;
226 trace
->entries
= stack_trace
+ nr_stack_trace_entries
;
229 trace
->all_contexts
= 0;
231 /* Make sure to not recurse in case the the unwinder needs to tak
234 save_stack_trace(trace
, NULL
);
237 trace
->max_entries
= trace
->nr_entries
;
239 nr_stack_trace_entries
+= trace
->nr_entries
;
240 if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries
> MAX_STACK_TRACE_ENTRIES
))
243 if (nr_stack_trace_entries
== MAX_STACK_TRACE_ENTRIES
) {
244 __raw_spin_unlock(&hash_lock
);
245 if (debug_locks_off()) {
246 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
247 printk("turning off the locking correctness validator.\n");
256 unsigned int nr_hardirq_chains
;
257 unsigned int nr_softirq_chains
;
258 unsigned int nr_process_chains
;
259 unsigned int max_lockdep_depth
;
260 unsigned int max_recursion_depth
;
262 #ifdef CONFIG_DEBUG_LOCKDEP
264 * We cannot printk in early bootup code. Not even early_printk()
265 * might work. So we mark any initialization errors and printk
266 * about it later on, in lockdep_info().
268 static int lockdep_init_error
;
271 * Various lockdep statistics:
273 atomic_t chain_lookup_hits
;
274 atomic_t chain_lookup_misses
;
275 atomic_t hardirqs_on_events
;
276 atomic_t hardirqs_off_events
;
277 atomic_t redundant_hardirqs_on
;
278 atomic_t redundant_hardirqs_off
;
279 atomic_t softirqs_on_events
;
280 atomic_t softirqs_off_events
;
281 atomic_t redundant_softirqs_on
;
282 atomic_t redundant_softirqs_off
;
283 atomic_t nr_unused_locks
;
284 atomic_t nr_cyclic_checks
;
285 atomic_t nr_cyclic_check_recursions
;
286 atomic_t nr_find_usage_forwards_checks
;
287 atomic_t nr_find_usage_forwards_recursions
;
288 atomic_t nr_find_usage_backwards_checks
;
289 atomic_t nr_find_usage_backwards_recursions
;
290 # define debug_atomic_inc(ptr) atomic_inc(ptr)
291 # define debug_atomic_dec(ptr) atomic_dec(ptr)
292 # define debug_atomic_read(ptr) atomic_read(ptr)
294 # define debug_atomic_inc(ptr) do { } while (0)
295 # define debug_atomic_dec(ptr) do { } while (0)
296 # define debug_atomic_read(ptr) 0
303 static const char *usage_str
[] =
305 [LOCK_USED
] = "initial-use ",
306 [LOCK_USED_IN_HARDIRQ
] = "in-hardirq-W",
307 [LOCK_USED_IN_SOFTIRQ
] = "in-softirq-W",
308 [LOCK_ENABLED_SOFTIRQS
] = "softirq-on-W",
309 [LOCK_ENABLED_HARDIRQS
] = "hardirq-on-W",
310 [LOCK_USED_IN_HARDIRQ_READ
] = "in-hardirq-R",
311 [LOCK_USED_IN_SOFTIRQ_READ
] = "in-softirq-R",
312 [LOCK_ENABLED_SOFTIRQS_READ
] = "softirq-on-R",
313 [LOCK_ENABLED_HARDIRQS_READ
] = "hardirq-on-R",
316 const char * __get_key_name(struct lockdep_subclass_key
*key
, char *str
)
318 unsigned long offs
, size
;
321 return kallsyms_lookup((unsigned long)key
, &size
, &offs
, &modname
, str
);
325 get_usage_chars(struct lock_class
*class, char *c1
, char *c2
, char *c3
, char *c4
)
327 *c1
= '.', *c2
= '.', *c3
= '.', *c4
= '.';
329 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ
)
332 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS
)
335 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ
)
338 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS
)
341 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
343 if (class->usage_mask
& LOCKF_USED_IN_HARDIRQ_READ
) {
345 if (class->usage_mask
& LOCKF_ENABLED_HARDIRQS_READ
)
349 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
351 if (class->usage_mask
& LOCKF_USED_IN_SOFTIRQ_READ
) {
353 if (class->usage_mask
& LOCKF_ENABLED_SOFTIRQS_READ
)
358 static void print_lock_name(struct lock_class
*class)
360 char str
[128], c1
, c2
, c3
, c4
;
363 get_usage_chars(class, &c1
, &c2
, &c3
, &c4
);
367 name
= __get_key_name(class->key
, str
);
368 printk(" (%s", name
);
370 printk(" (%s", name
);
371 if (class->name_version
> 1)
372 printk("#%d", class->name_version
);
374 printk("/%d", class->subclass
);
376 printk("){%c%c%c%c}", c1
, c2
, c3
, c4
);
379 static void print_lockdep_cache(struct lockdep_map
*lock
)
386 name
= __get_key_name(lock
->key
->subkeys
, str
);
391 static void print_lock(struct held_lock
*hlock
)
393 print_lock_name(hlock
->class);
395 print_ip_sym(hlock
->acquire_ip
);
398 static void lockdep_print_held_locks(struct task_struct
*curr
)
400 int i
, depth
= curr
->lockdep_depth
;
403 printk("no locks held by %s/%d.\n", curr
->comm
, curr
->pid
);
406 printk("%d lock%s held by %s/%d:\n",
407 depth
, depth
> 1 ? "s" : "", curr
->comm
, curr
->pid
);
409 for (i
= 0; i
< depth
; i
++) {
411 print_lock(curr
->held_locks
+ i
);
415 static void print_lock_class_header(struct lock_class
*class, int depth
)
419 printk("%*s->", depth
, "");
420 print_lock_name(class);
421 printk(" ops: %lu", class->ops
);
424 for (bit
= 0; bit
< LOCK_USAGE_STATES
; bit
++) {
425 if (class->usage_mask
& (1 << bit
)) {
428 len
+= printk("%*s %s", depth
, "", usage_str
[bit
]);
429 len
+= printk(" at:\n");
430 print_stack_trace(class->usage_traces
+ bit
, len
);
433 printk("%*s }\n", depth
, "");
435 printk("%*s ... key at: ",depth
,"");
436 print_ip_sym((unsigned long)class->key
);
440 * printk all lock dependencies starting at <entry>:
442 static void print_lock_dependencies(struct lock_class
*class, int depth
)
444 struct lock_list
*entry
;
446 if (DEBUG_LOCKS_WARN_ON(depth
>= 20))
449 print_lock_class_header(class, depth
);
451 list_for_each_entry(entry
, &class->locks_after
, entry
) {
452 DEBUG_LOCKS_WARN_ON(!entry
->class);
453 print_lock_dependencies(entry
->class, depth
+ 1);
455 printk("%*s ... acquired at:\n",depth
,"");
456 print_stack_trace(&entry
->trace
, 2);
462 * Add a new dependency to the head of the list:
464 static int add_lock_to_list(struct lock_class
*class, struct lock_class
*this,
465 struct list_head
*head
, unsigned long ip
)
467 struct lock_list
*entry
;
469 * Lock not present yet - get a new dependency struct and
470 * add it to the list:
472 entry
= alloc_list_entry();
477 save_trace(&entry
->trace
);
480 * Since we never remove from the dependency list, the list can
481 * be walked lockless by other CPUs, it's only allocation
482 * that must be protected by the spinlock. But this also means
483 * we must make new entries visible only once writes to the
484 * entry become visible - hence the RCU op:
486 list_add_tail_rcu(&entry
->entry
, head
);
492 * Recursive, forwards-direction lock-dependency checking, used for
493 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
496 * (to keep the stackframe of the recursive functions small we
497 * use these global variables, and we also mark various helper
498 * functions as noinline.)
500 static struct held_lock
*check_source
, *check_target
;
503 * Print a dependency chain entry (this is only done when a deadlock
504 * has been detected):
507 print_circular_bug_entry(struct lock_list
*target
, unsigned int depth
)
509 if (debug_locks_silent
)
511 printk("\n-> #%u", depth
);
512 print_lock_name(target
->class);
514 print_stack_trace(&target
->trace
, 6);
519 static void print_kernel_version(void)
521 printk("%s %.*s\n", init_utsname()->release
,
522 (int)strcspn(init_utsname()->version
, " "),
523 init_utsname()->version
);
527 * When a circular dependency is detected, print the
531 print_circular_bug_header(struct lock_list
*entry
, unsigned int depth
)
533 struct task_struct
*curr
= current
;
535 __raw_spin_unlock(&hash_lock
);
537 if (debug_locks_silent
)
540 printk("\n=======================================================\n");
541 printk( "[ INFO: possible circular locking dependency detected ]\n");
542 print_kernel_version();
543 printk( "-------------------------------------------------------\n");
544 printk("%s/%d is trying to acquire lock:\n",
545 curr
->comm
, curr
->pid
);
546 print_lock(check_source
);
547 printk("\nbut task is already holding lock:\n");
548 print_lock(check_target
);
549 printk("\nwhich lock already depends on the new lock.\n\n");
550 printk("\nthe existing dependency chain (in reverse order) is:\n");
552 print_circular_bug_entry(entry
, depth
);
557 static noinline
int print_circular_bug_tail(void)
559 struct task_struct
*curr
= current
;
560 struct lock_list
this;
562 if (debug_locks_silent
)
565 this.class = check_source
->class;
566 save_trace(&this.trace
);
567 print_circular_bug_entry(&this, 0);
569 printk("\nother info that might help us debug this:\n\n");
570 lockdep_print_held_locks(curr
);
572 printk("\nstack backtrace:\n");
578 static int noinline
print_infinite_recursion_bug(void)
580 __raw_spin_unlock(&hash_lock
);
581 DEBUG_LOCKS_WARN_ON(1);
587 * Prove that the dependency graph starting at <entry> can not
588 * lead to <target>. Print an error and return 0 if it does.
591 check_noncircular(struct lock_class
*source
, unsigned int depth
)
593 struct lock_list
*entry
;
595 debug_atomic_inc(&nr_cyclic_check_recursions
);
596 if (depth
> max_recursion_depth
)
597 max_recursion_depth
= depth
;
599 return print_infinite_recursion_bug();
601 * Check this lock's dependency list:
603 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
604 if (entry
->class == check_target
->class)
605 return print_circular_bug_header(entry
, depth
+1);
606 debug_atomic_inc(&nr_cyclic_checks
);
607 if (!check_noncircular(entry
->class, depth
+1))
608 return print_circular_bug_entry(entry
, depth
+1);
613 static int very_verbose(struct lock_class
*class)
616 return class_filter(class);
620 #ifdef CONFIG_TRACE_IRQFLAGS
623 * Forwards and backwards subgraph searching, for the purposes of
624 * proving that two subgraphs can be connected by a new dependency
625 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
627 static enum lock_usage_bit find_usage_bit
;
628 static struct lock_class
*forwards_match
, *backwards_match
;
631 * Find a node in the forwards-direction dependency sub-graph starting
632 * at <source> that matches <find_usage_bit>.
634 * Return 2 if such a node exists in the subgraph, and put that node
635 * into <forwards_match>.
637 * Return 1 otherwise and keep <forwards_match> unchanged.
641 find_usage_forwards(struct lock_class
*source
, unsigned int depth
)
643 struct lock_list
*entry
;
646 if (depth
> max_recursion_depth
)
647 max_recursion_depth
= depth
;
649 return print_infinite_recursion_bug();
651 debug_atomic_inc(&nr_find_usage_forwards_checks
);
652 if (source
->usage_mask
& (1 << find_usage_bit
)) {
653 forwards_match
= source
;
658 * Check this lock's dependency list:
660 list_for_each_entry(entry
, &source
->locks_after
, entry
) {
661 debug_atomic_inc(&nr_find_usage_forwards_recursions
);
662 ret
= find_usage_forwards(entry
->class, depth
+1);
663 if (ret
== 2 || ret
== 0)
670 * Find a node in the backwards-direction dependency sub-graph starting
671 * at <source> that matches <find_usage_bit>.
673 * Return 2 if such a node exists in the subgraph, and put that node
674 * into <backwards_match>.
676 * Return 1 otherwise and keep <backwards_match> unchanged.
680 find_usage_backwards(struct lock_class
*source
, unsigned int depth
)
682 struct lock_list
*entry
;
685 if (depth
> max_recursion_depth
)
686 max_recursion_depth
= depth
;
688 return print_infinite_recursion_bug();
690 debug_atomic_inc(&nr_find_usage_backwards_checks
);
691 if (source
->usage_mask
& (1 << find_usage_bit
)) {
692 backwards_match
= source
;
697 * Check this lock's dependency list:
699 list_for_each_entry(entry
, &source
->locks_before
, entry
) {
700 debug_atomic_inc(&nr_find_usage_backwards_recursions
);
701 ret
= find_usage_backwards(entry
->class, depth
+1);
702 if (ret
== 2 || ret
== 0)
709 print_bad_irq_dependency(struct task_struct
*curr
,
710 struct held_lock
*prev
,
711 struct held_lock
*next
,
712 enum lock_usage_bit bit1
,
713 enum lock_usage_bit bit2
,
714 const char *irqclass
)
716 __raw_spin_unlock(&hash_lock
);
718 if (debug_locks_silent
)
721 printk("\n======================================================\n");
722 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
724 print_kernel_version();
725 printk( "------------------------------------------------------\n");
726 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
727 curr
->comm
, curr
->pid
,
728 curr
->hardirq_context
, hardirq_count() >> HARDIRQ_SHIFT
,
729 curr
->softirq_context
, softirq_count() >> SOFTIRQ_SHIFT
,
730 curr
->hardirqs_enabled
,
731 curr
->softirqs_enabled
);
734 printk("\nand this task is already holding:\n");
736 printk("which would create a new lock dependency:\n");
737 print_lock_name(prev
->class);
739 print_lock_name(next
->class);
742 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
744 print_lock_name(backwards_match
);
745 printk("\n... which became %s-irq-safe at:\n", irqclass
);
747 print_stack_trace(backwards_match
->usage_traces
+ bit1
, 1);
749 printk("\nto a %s-irq-unsafe lock:\n", irqclass
);
750 print_lock_name(forwards_match
);
751 printk("\n... which became %s-irq-unsafe at:\n", irqclass
);
754 print_stack_trace(forwards_match
->usage_traces
+ bit2
, 1);
756 printk("\nother info that might help us debug this:\n\n");
757 lockdep_print_held_locks(curr
);
759 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass
);
760 print_lock_dependencies(backwards_match
, 0);
762 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass
);
763 print_lock_dependencies(forwards_match
, 0);
765 printk("\nstack backtrace:\n");
772 check_usage(struct task_struct
*curr
, struct held_lock
*prev
,
773 struct held_lock
*next
, enum lock_usage_bit bit_backwards
,
774 enum lock_usage_bit bit_forwards
, const char *irqclass
)
778 find_usage_bit
= bit_backwards
;
779 /* fills in <backwards_match> */
780 ret
= find_usage_backwards(prev
->class, 0);
781 if (!ret
|| ret
== 1)
784 find_usage_bit
= bit_forwards
;
785 ret
= find_usage_forwards(next
->class, 0);
786 if (!ret
|| ret
== 1)
789 return print_bad_irq_dependency(curr
, prev
, next
,
790 bit_backwards
, bit_forwards
, irqclass
);
796 print_deadlock_bug(struct task_struct
*curr
, struct held_lock
*prev
,
797 struct held_lock
*next
)
800 __raw_spin_unlock(&hash_lock
);
801 if (debug_locks_silent
)
804 printk("\n=============================================\n");
805 printk( "[ INFO: possible recursive locking detected ]\n");
806 print_kernel_version();
807 printk( "---------------------------------------------\n");
808 printk("%s/%d is trying to acquire lock:\n",
809 curr
->comm
, curr
->pid
);
811 printk("\nbut task is already holding lock:\n");
814 printk("\nother info that might help us debug this:\n");
815 lockdep_print_held_locks(curr
);
817 printk("\nstack backtrace:\n");
824 * Check whether we are holding such a class already.
826 * (Note that this has to be done separately, because the graph cannot
827 * detect such classes of deadlocks.)
829 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
832 check_deadlock(struct task_struct
*curr
, struct held_lock
*next
,
833 struct lockdep_map
*next_instance
, int read
)
835 struct held_lock
*prev
;
838 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
839 prev
= curr
->held_locks
+ i
;
840 if (prev
->class != next
->class)
843 * Allow read-after-read recursion of the same
844 * lock class (i.e. read_lock(lock)+read_lock(lock)):
846 if ((read
== 2) && prev
->read
)
848 return print_deadlock_bug(curr
, prev
, next
);
854 * There was a chain-cache miss, and we are about to add a new dependency
855 * to a previous lock. We recursively validate the following rules:
857 * - would the adding of the <prev> -> <next> dependency create a
858 * circular dependency in the graph? [== circular deadlock]
860 * - does the new prev->next dependency connect any hardirq-safe lock
861 * (in the full backwards-subgraph starting at <prev>) with any
862 * hardirq-unsafe lock (in the full forwards-subgraph starting at
863 * <next>)? [== illegal lock inversion with hardirq contexts]
865 * - does the new prev->next dependency connect any softirq-safe lock
866 * (in the full backwards-subgraph starting at <prev>) with any
867 * softirq-unsafe lock (in the full forwards-subgraph starting at
868 * <next>)? [== illegal lock inversion with softirq contexts]
870 * any of these scenarios could lead to a deadlock.
872 * Then if all the validations pass, we add the forwards and backwards
876 check_prev_add(struct task_struct
*curr
, struct held_lock
*prev
,
877 struct held_lock
*next
)
879 struct lock_list
*entry
;
883 * Prove that the new <prev> -> <next> dependency would not
884 * create a circular dependency in the graph. (We do this by
885 * forward-recursing into the graph starting at <next>, and
886 * checking whether we can reach <prev>.)
888 * We are using global variables to control the recursion, to
889 * keep the stackframe size of the recursive functions low:
893 if (!(check_noncircular(next
->class, 0)))
894 return print_circular_bug_tail();
896 #ifdef CONFIG_TRACE_IRQFLAGS
898 * Prove that the new dependency does not connect a hardirq-safe
899 * lock with a hardirq-unsafe lock - to achieve this we search
900 * the backwards-subgraph starting at <prev>, and the
901 * forwards-subgraph starting at <next>:
903 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ
,
904 LOCK_ENABLED_HARDIRQS
, "hard"))
908 * Prove that the new dependency does not connect a hardirq-safe-read
909 * lock with a hardirq-unsafe lock - to achieve this we search
910 * the backwards-subgraph starting at <prev>, and the
911 * forwards-subgraph starting at <next>:
913 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_HARDIRQ_READ
,
914 LOCK_ENABLED_HARDIRQS
, "hard-read"))
918 * Prove that the new dependency does not connect a softirq-safe
919 * lock with a softirq-unsafe lock - to achieve this we search
920 * the backwards-subgraph starting at <prev>, and the
921 * forwards-subgraph starting at <next>:
923 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ
,
924 LOCK_ENABLED_SOFTIRQS
, "soft"))
927 * Prove that the new dependency does not connect a softirq-safe-read
928 * lock with a softirq-unsafe lock - to achieve this we search
929 * the backwards-subgraph starting at <prev>, and the
930 * forwards-subgraph starting at <next>:
932 if (!check_usage(curr
, prev
, next
, LOCK_USED_IN_SOFTIRQ_READ
,
933 LOCK_ENABLED_SOFTIRQS
, "soft"))
937 * For recursive read-locks we do all the dependency checks,
938 * but we dont store read-triggered dependencies (only
939 * write-triggered dependencies). This ensures that only the
940 * write-side dependencies matter, and that if for example a
941 * write-lock never takes any other locks, then the reads are
942 * equivalent to a NOP.
944 if (next
->read
== 2 || prev
->read
== 2)
947 * Is the <prev> -> <next> dependency already present?
949 * (this may occur even though this is a new chain: consider
950 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
951 * chains - the second one will be new, but L1 already has
952 * L2 added to its dependency list, due to the first chain.)
954 list_for_each_entry(entry
, &prev
->class->locks_after
, entry
) {
955 if (entry
->class == next
->class)
960 * Ok, all validations passed, add the new lock
961 * to the previous lock's dependency list:
963 ret
= add_lock_to_list(prev
->class, next
->class,
964 &prev
->class->locks_after
, next
->acquire_ip
);
968 * Return value of 2 signals 'dependency already added',
969 * in that case we dont have to add the backlink either.
973 ret
= add_lock_to_list(next
->class, prev
->class,
974 &next
->class->locks_before
, next
->acquire_ip
);
977 * Debugging printouts:
979 if (verbose(prev
->class) || verbose(next
->class)) {
980 __raw_spin_unlock(&hash_lock
);
981 printk("\n new dependency: ");
982 print_lock_name(prev
->class);
984 print_lock_name(next
->class);
987 __raw_spin_lock(&hash_lock
);
993 * Add the dependency to all directly-previous locks that are 'relevant'.
994 * The ones that are relevant are (in increasing distance from curr):
995 * all consecutive trylock entries and the final non-trylock entry - or
996 * the end of this context's lock-chain - whichever comes first.
999 check_prevs_add(struct task_struct
*curr
, struct held_lock
*next
)
1001 int depth
= curr
->lockdep_depth
;
1002 struct held_lock
*hlock
;
1007 * Depth must not be zero for a non-head lock:
1012 * At least two relevant locks must exist for this
1015 if (curr
->held_locks
[depth
].irq_context
!=
1016 curr
->held_locks
[depth
-1].irq_context
)
1020 hlock
= curr
->held_locks
+ depth
-1;
1022 * Only non-recursive-read entries get new dependencies
1025 if (hlock
->read
!= 2) {
1026 check_prev_add(curr
, hlock
, next
);
1028 * Stop after the first non-trylock entry,
1029 * as non-trylock entries have added their
1030 * own direct dependencies already, so this
1031 * lock is connected to them indirectly:
1033 if (!hlock
->trylock
)
1038 * End of lock-stack?
1043 * Stop the search if we cross into another context:
1045 if (curr
->held_locks
[depth
].irq_context
!=
1046 curr
->held_locks
[depth
-1].irq_context
)
1051 __raw_spin_unlock(&hash_lock
);
1052 DEBUG_LOCKS_WARN_ON(1);
1059 * Is this the address of a static object:
1061 static int static_obj(void *obj
)
1063 unsigned long start
= (unsigned long) &_stext
,
1064 end
= (unsigned long) &_end
,
1065 addr
= (unsigned long) obj
;
1073 if ((addr
>= start
) && (addr
< end
))
1080 for_each_possible_cpu(i
) {
1081 start
= (unsigned long) &__per_cpu_start
+ per_cpu_offset(i
);
1082 end
= (unsigned long) &__per_cpu_end
+ per_cpu_offset(i
);
1084 if ((addr
>= start
) && (addr
< end
))
1092 return is_module_address(addr
);
1096 * To make lock name printouts unique, we calculate a unique
1097 * class->name_version generation counter:
1099 static int count_matching_names(struct lock_class
*new_class
)
1101 struct lock_class
*class;
1104 if (!new_class
->name
)
1107 list_for_each_entry(class, &all_lock_classes
, lock_entry
) {
1108 if (new_class
->key
- new_class
->subclass
== class->key
)
1109 return class->name_version
;
1110 if (class->name
&& !strcmp(class->name
, new_class
->name
))
1111 count
= max(count
, class->name_version
);
1118 * Register a lock's class in the hash-table, if the class is not present
1119 * yet. Otherwise we look it up. We cache the result in the lock object
1120 * itself, so actual lookup of the hash should be once per lock object.
1122 static inline struct lock_class
*
1123 look_up_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
1125 struct lockdep_subclass_key
*key
;
1126 struct list_head
*hash_head
;
1127 struct lock_class
*class;
1129 #ifdef CONFIG_DEBUG_LOCKDEP
1131 * If the architecture calls into lockdep before initializing
1132 * the hashes then we'll warn about it later. (we cannot printk
1135 if (unlikely(!lockdep_initialized
)) {
1137 lockdep_init_error
= 1;
1142 * Static locks do not have their class-keys yet - for them the key
1143 * is the lock object itself:
1145 if (unlikely(!lock
->key
))
1146 lock
->key
= (void *)lock
;
1149 * NOTE: the class-key must be unique. For dynamic locks, a static
1150 * lock_class_key variable is passed in through the mutex_init()
1151 * (or spin_lock_init()) call - which acts as the key. For static
1152 * locks we use the lock object itself as the key.
1154 BUILD_BUG_ON(sizeof(struct lock_class_key
) > sizeof(struct lock_class
));
1156 key
= lock
->key
->subkeys
+ subclass
;
1158 hash_head
= classhashentry(key
);
1161 * We can walk the hash lockfree, because the hash only
1162 * grows, and we are careful when adding entries to the end:
1164 list_for_each_entry(class, hash_head
, hash_entry
)
1165 if (class->key
== key
)
1172 * Register a lock's class in the hash-table, if the class is not present
1173 * yet. Otherwise we look it up. We cache the result in the lock object
1174 * itself, so actual lookup of the hash should be once per lock object.
1176 static inline struct lock_class
*
1177 register_lock_class(struct lockdep_map
*lock
, unsigned int subclass
)
1179 struct lockdep_subclass_key
*key
;
1180 struct list_head
*hash_head
;
1181 struct lock_class
*class;
1183 class = look_up_lock_class(lock
, subclass
);
1188 * Debug-check: all keys must be persistent!
1190 if (!static_obj(lock
->key
)) {
1192 printk("INFO: trying to register non-static key.\n");
1193 printk("the code is fine but needs lockdep annotation.\n");
1194 printk("turning off the locking correctness validator.\n");
1200 key
= lock
->key
->subkeys
+ subclass
;
1201 hash_head
= classhashentry(key
);
1203 __raw_spin_lock(&hash_lock
);
1205 * We have to do the hash-walk again, to avoid races
1208 list_for_each_entry(class, hash_head
, hash_entry
)
1209 if (class->key
== key
)
1210 goto out_unlock_set
;
1212 * Allocate a new key from the static array, and add it to
1215 if (nr_lock_classes
>= MAX_LOCKDEP_KEYS
) {
1216 __raw_spin_unlock(&hash_lock
);
1218 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
1219 printk("turning off the locking correctness validator.\n");
1222 class = lock_classes
+ nr_lock_classes
++;
1223 debug_atomic_inc(&nr_unused_locks
);
1225 class->name
= lock
->name
;
1226 class->subclass
= subclass
;
1227 INIT_LIST_HEAD(&class->lock_entry
);
1228 INIT_LIST_HEAD(&class->locks_before
);
1229 INIT_LIST_HEAD(&class->locks_after
);
1230 class->name_version
= count_matching_names(class);
1232 * We use RCU's safe list-add method to make
1233 * parallel walking of the hash-list safe:
1235 list_add_tail_rcu(&class->hash_entry
, hash_head
);
1237 if (verbose(class)) {
1238 __raw_spin_unlock(&hash_lock
);
1239 printk("\nnew class %p: %s", class->key
, class->name
);
1240 if (class->name_version
> 1)
1241 printk("#%d", class->name_version
);
1244 __raw_spin_lock(&hash_lock
);
1247 __raw_spin_unlock(&hash_lock
);
1250 lock
->class_cache
= class;
1252 DEBUG_LOCKS_WARN_ON(class->subclass
!= subclass
);
1258 * Look up a dependency chain. If the key is not present yet then
1259 * add it and return 0 - in this case the new dependency chain is
1260 * validated. If the key is already hashed, return 1.
1262 static inline int lookup_chain_cache(u64 chain_key
)
1264 struct list_head
*hash_head
= chainhashentry(chain_key
);
1265 struct lock_chain
*chain
;
1267 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1269 * We can walk it lock-free, because entries only get added
1272 list_for_each_entry(chain
, hash_head
, entry
) {
1273 if (chain
->chain_key
== chain_key
) {
1275 debug_atomic_inc(&chain_lookup_hits
);
1277 * In the debugging case, force redundant checking
1280 #ifdef CONFIG_DEBUG_LOCKDEP
1281 __raw_spin_lock(&hash_lock
);
1288 * Allocate a new chain entry from the static array, and add
1291 __raw_spin_lock(&hash_lock
);
1293 * We have to walk the chain again locked - to avoid duplicates:
1295 list_for_each_entry(chain
, hash_head
, entry
) {
1296 if (chain
->chain_key
== chain_key
) {
1297 __raw_spin_unlock(&hash_lock
);
1301 if (unlikely(nr_lock_chains
>= MAX_LOCKDEP_CHAINS
)) {
1302 __raw_spin_unlock(&hash_lock
);
1304 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1305 printk("turning off the locking correctness validator.\n");
1308 chain
= lock_chains
+ nr_lock_chains
++;
1309 chain
->chain_key
= chain_key
;
1310 list_add_tail_rcu(&chain
->entry
, hash_head
);
1311 debug_atomic_inc(&chain_lookup_misses
);
1312 #ifdef CONFIG_TRACE_IRQFLAGS
1313 if (current
->hardirq_context
)
1314 nr_hardirq_chains
++;
1316 if (current
->softirq_context
)
1317 nr_softirq_chains
++;
1319 nr_process_chains
++;
1322 nr_process_chains
++;
1329 * We are building curr_chain_key incrementally, so double-check
1330 * it from scratch, to make sure that it's done correctly:
1332 static void check_chain_key(struct task_struct
*curr
)
1334 #ifdef CONFIG_DEBUG_LOCKDEP
1335 struct held_lock
*hlock
, *prev_hlock
= NULL
;
1339 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1340 hlock
= curr
->held_locks
+ i
;
1341 if (chain_key
!= hlock
->prev_chain_key
) {
1343 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1344 curr
->lockdep_depth
, i
,
1345 (unsigned long long)chain_key
,
1346 (unsigned long long)hlock
->prev_chain_key
);
1350 id
= hlock
->class - lock_classes
;
1351 DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
);
1352 if (prev_hlock
&& (prev_hlock
->irq_context
!=
1353 hlock
->irq_context
))
1355 chain_key
= iterate_chain_key(chain_key
, id
);
1358 if (chain_key
!= curr
->curr_chain_key
) {
1360 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1361 curr
->lockdep_depth
, i
,
1362 (unsigned long long)chain_key
,
1363 (unsigned long long)curr
->curr_chain_key
);
1369 #ifdef CONFIG_TRACE_IRQFLAGS
1372 * print irq inversion bug:
1375 print_irq_inversion_bug(struct task_struct
*curr
, struct lock_class
*other
,
1376 struct held_lock
*this, int forwards
,
1377 const char *irqclass
)
1379 __raw_spin_unlock(&hash_lock
);
1381 if (debug_locks_silent
)
1384 printk("\n=========================================================\n");
1385 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1386 print_kernel_version();
1387 printk( "---------------------------------------------------------\n");
1388 printk("%s/%d just changed the state of lock:\n",
1389 curr
->comm
, curr
->pid
);
1392 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass
);
1394 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass
);
1395 print_lock_name(other
);
1396 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1398 printk("\nother info that might help us debug this:\n");
1399 lockdep_print_held_locks(curr
);
1401 printk("\nthe first lock's dependencies:\n");
1402 print_lock_dependencies(this->class, 0);
1404 printk("\nthe second lock's dependencies:\n");
1405 print_lock_dependencies(other
, 0);
1407 printk("\nstack backtrace:\n");
1414 * Prove that in the forwards-direction subgraph starting at <this>
1415 * there is no lock matching <mask>:
1418 check_usage_forwards(struct task_struct
*curr
, struct held_lock
*this,
1419 enum lock_usage_bit bit
, const char *irqclass
)
1423 find_usage_bit
= bit
;
1424 /* fills in <forwards_match> */
1425 ret
= find_usage_forwards(this->class, 0);
1426 if (!ret
|| ret
== 1)
1429 return print_irq_inversion_bug(curr
, forwards_match
, this, 1, irqclass
);
1433 * Prove that in the backwards-direction subgraph starting at <this>
1434 * there is no lock matching <mask>:
1437 check_usage_backwards(struct task_struct
*curr
, struct held_lock
*this,
1438 enum lock_usage_bit bit
, const char *irqclass
)
1442 find_usage_bit
= bit
;
1443 /* fills in <backwards_match> */
1444 ret
= find_usage_backwards(this->class, 0);
1445 if (!ret
|| ret
== 1)
1448 return print_irq_inversion_bug(curr
, backwards_match
, this, 0, irqclass
);
1451 static inline void print_irqtrace_events(struct task_struct
*curr
)
1453 printk("irq event stamp: %u\n", curr
->irq_events
);
1454 printk("hardirqs last enabled at (%u): ", curr
->hardirq_enable_event
);
1455 print_ip_sym(curr
->hardirq_enable_ip
);
1456 printk("hardirqs last disabled at (%u): ", curr
->hardirq_disable_event
);
1457 print_ip_sym(curr
->hardirq_disable_ip
);
1458 printk("softirqs last enabled at (%u): ", curr
->softirq_enable_event
);
1459 print_ip_sym(curr
->softirq_enable_ip
);
1460 printk("softirqs last disabled at (%u): ", curr
->softirq_disable_event
);
1461 print_ip_sym(curr
->softirq_disable_ip
);
1465 static inline void print_irqtrace_events(struct task_struct
*curr
)
1471 print_usage_bug(struct task_struct
*curr
, struct held_lock
*this,
1472 enum lock_usage_bit prev_bit
, enum lock_usage_bit new_bit
)
1474 __raw_spin_unlock(&hash_lock
);
1476 if (debug_locks_silent
)
1479 printk("\n=================================\n");
1480 printk( "[ INFO: inconsistent lock state ]\n");
1481 print_kernel_version();
1482 printk( "---------------------------------\n");
1484 printk("inconsistent {%s} -> {%s} usage.\n",
1485 usage_str
[prev_bit
], usage_str
[new_bit
]);
1487 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1488 curr
->comm
, curr
->pid
,
1489 trace_hardirq_context(curr
), hardirq_count() >> HARDIRQ_SHIFT
,
1490 trace_softirq_context(curr
), softirq_count() >> SOFTIRQ_SHIFT
,
1491 trace_hardirqs_enabled(curr
),
1492 trace_softirqs_enabled(curr
));
1495 printk("{%s} state was registered at:\n", usage_str
[prev_bit
]);
1496 print_stack_trace(this->class->usage_traces
+ prev_bit
, 1);
1498 print_irqtrace_events(curr
);
1499 printk("\nother info that might help us debug this:\n");
1500 lockdep_print_held_locks(curr
);
1502 printk("\nstack backtrace:\n");
1509 * Print out an error if an invalid bit is set:
1512 valid_state(struct task_struct
*curr
, struct held_lock
*this,
1513 enum lock_usage_bit new_bit
, enum lock_usage_bit bad_bit
)
1515 if (unlikely(this->class->usage_mask
& (1 << bad_bit
)))
1516 return print_usage_bug(curr
, this, bad_bit
, new_bit
);
1520 #define STRICT_READ_CHECKS 1
1523 * Mark a lock with a usage bit, and validate the state transition:
1525 static int mark_lock(struct task_struct
*curr
, struct held_lock
*this,
1526 enum lock_usage_bit new_bit
, unsigned long ip
)
1528 unsigned int new_mask
= 1 << new_bit
, ret
= 1;
1531 * If already set then do not dirty the cacheline,
1532 * nor do any checks:
1534 if (likely(this->class->usage_mask
& new_mask
))
1537 __raw_spin_lock(&hash_lock
);
1539 * Make sure we didnt race:
1541 if (unlikely(this->class->usage_mask
& new_mask
)) {
1542 __raw_spin_unlock(&hash_lock
);
1546 this->class->usage_mask
|= new_mask
;
1548 #ifdef CONFIG_TRACE_IRQFLAGS
1549 if (new_bit
== LOCK_ENABLED_HARDIRQS
||
1550 new_bit
== LOCK_ENABLED_HARDIRQS_READ
)
1551 ip
= curr
->hardirq_enable_ip
;
1552 else if (new_bit
== LOCK_ENABLED_SOFTIRQS
||
1553 new_bit
== LOCK_ENABLED_SOFTIRQS_READ
)
1554 ip
= curr
->softirq_enable_ip
;
1556 if (!save_trace(this->class->usage_traces
+ new_bit
))
1560 #ifdef CONFIG_TRACE_IRQFLAGS
1561 case LOCK_USED_IN_HARDIRQ
:
1562 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1564 if (!valid_state(curr
, this, new_bit
,
1565 LOCK_ENABLED_HARDIRQS_READ
))
1568 * just marked it hardirq-safe, check that this lock
1569 * took no hardirq-unsafe lock in the past:
1571 if (!check_usage_forwards(curr
, this,
1572 LOCK_ENABLED_HARDIRQS
, "hard"))
1574 #if STRICT_READ_CHECKS
1576 * just marked it hardirq-safe, check that this lock
1577 * took no hardirq-unsafe-read lock in the past:
1579 if (!check_usage_forwards(curr
, this,
1580 LOCK_ENABLED_HARDIRQS_READ
, "hard-read"))
1583 if (hardirq_verbose(this->class))
1586 case LOCK_USED_IN_SOFTIRQ
:
1587 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1589 if (!valid_state(curr
, this, new_bit
,
1590 LOCK_ENABLED_SOFTIRQS_READ
))
1593 * just marked it softirq-safe, check that this lock
1594 * took no softirq-unsafe lock in the past:
1596 if (!check_usage_forwards(curr
, this,
1597 LOCK_ENABLED_SOFTIRQS
, "soft"))
1599 #if STRICT_READ_CHECKS
1601 * just marked it softirq-safe, check that this lock
1602 * took no softirq-unsafe-read lock in the past:
1604 if (!check_usage_forwards(curr
, this,
1605 LOCK_ENABLED_SOFTIRQS_READ
, "soft-read"))
1608 if (softirq_verbose(this->class))
1611 case LOCK_USED_IN_HARDIRQ_READ
:
1612 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_HARDIRQS
))
1615 * just marked it hardirq-read-safe, check that this lock
1616 * took no hardirq-unsafe lock in the past:
1618 if (!check_usage_forwards(curr
, this,
1619 LOCK_ENABLED_HARDIRQS
, "hard"))
1621 if (hardirq_verbose(this->class))
1624 case LOCK_USED_IN_SOFTIRQ_READ
:
1625 if (!valid_state(curr
, this, new_bit
, LOCK_ENABLED_SOFTIRQS
))
1628 * just marked it softirq-read-safe, check that this lock
1629 * took no softirq-unsafe lock in the past:
1631 if (!check_usage_forwards(curr
, this,
1632 LOCK_ENABLED_SOFTIRQS
, "soft"))
1634 if (softirq_verbose(this->class))
1637 case LOCK_ENABLED_HARDIRQS
:
1638 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1640 if (!valid_state(curr
, this, new_bit
,
1641 LOCK_USED_IN_HARDIRQ_READ
))
1644 * just marked it hardirq-unsafe, check that no hardirq-safe
1645 * lock in the system ever took it in the past:
1647 if (!check_usage_backwards(curr
, this,
1648 LOCK_USED_IN_HARDIRQ
, "hard"))
1650 #if STRICT_READ_CHECKS
1652 * just marked it hardirq-unsafe, check that no
1653 * hardirq-safe-read lock in the system ever took
1656 if (!check_usage_backwards(curr
, this,
1657 LOCK_USED_IN_HARDIRQ_READ
, "hard-read"))
1660 if (hardirq_verbose(this->class))
1663 case LOCK_ENABLED_SOFTIRQS
:
1664 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1666 if (!valid_state(curr
, this, new_bit
,
1667 LOCK_USED_IN_SOFTIRQ_READ
))
1670 * just marked it softirq-unsafe, check that no softirq-safe
1671 * lock in the system ever took it in the past:
1673 if (!check_usage_backwards(curr
, this,
1674 LOCK_USED_IN_SOFTIRQ
, "soft"))
1676 #if STRICT_READ_CHECKS
1678 * just marked it softirq-unsafe, check that no
1679 * softirq-safe-read lock in the system ever took
1682 if (!check_usage_backwards(curr
, this,
1683 LOCK_USED_IN_SOFTIRQ_READ
, "soft-read"))
1686 if (softirq_verbose(this->class))
1689 case LOCK_ENABLED_HARDIRQS_READ
:
1690 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_HARDIRQ
))
1692 #if STRICT_READ_CHECKS
1694 * just marked it hardirq-read-unsafe, check that no
1695 * hardirq-safe lock in the system ever took it in the past:
1697 if (!check_usage_backwards(curr
, this,
1698 LOCK_USED_IN_HARDIRQ
, "hard"))
1701 if (hardirq_verbose(this->class))
1704 case LOCK_ENABLED_SOFTIRQS_READ
:
1705 if (!valid_state(curr
, this, new_bit
, LOCK_USED_IN_SOFTIRQ
))
1707 #if STRICT_READ_CHECKS
1709 * just marked it softirq-read-unsafe, check that no
1710 * softirq-safe lock in the system ever took it in the past:
1712 if (!check_usage_backwards(curr
, this,
1713 LOCK_USED_IN_SOFTIRQ
, "soft"))
1716 if (softirq_verbose(this->class))
1722 * Add it to the global list of classes:
1724 list_add_tail_rcu(&this->class->lock_entry
, &all_lock_classes
);
1725 debug_atomic_dec(&nr_unused_locks
);
1733 __raw_spin_unlock(&hash_lock
);
1736 * We must printk outside of the hash_lock:
1739 printk("\nmarked lock as {%s}:\n", usage_str
[new_bit
]);
1741 print_irqtrace_events(curr
);
1748 #ifdef CONFIG_TRACE_IRQFLAGS
1750 * Mark all held locks with a usage bit:
1753 mark_held_locks(struct task_struct
*curr
, int hardirq
, unsigned long ip
)
1755 enum lock_usage_bit usage_bit
;
1756 struct held_lock
*hlock
;
1759 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
1760 hlock
= curr
->held_locks
+ i
;
1764 usage_bit
= LOCK_ENABLED_HARDIRQS_READ
;
1766 usage_bit
= LOCK_ENABLED_HARDIRQS
;
1769 usage_bit
= LOCK_ENABLED_SOFTIRQS_READ
;
1771 usage_bit
= LOCK_ENABLED_SOFTIRQS
;
1773 if (!mark_lock(curr
, hlock
, usage_bit
, ip
))
1781 * Debugging helper: via this flag we know that we are in
1782 * 'early bootup code', and will warn about any invalid irqs-on event:
1784 static int early_boot_irqs_enabled
;
1786 void early_boot_irqs_off(void)
1788 early_boot_irqs_enabled
= 0;
1791 void early_boot_irqs_on(void)
1793 early_boot_irqs_enabled
= 1;
1797 * Hardirqs will be enabled:
1799 void trace_hardirqs_on(void)
1801 struct task_struct
*curr
= current
;
1804 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
1807 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled
)))
1810 if (unlikely(curr
->hardirqs_enabled
)) {
1811 debug_atomic_inc(&redundant_hardirqs_on
);
1814 /* we'll do an OFF -> ON transition: */
1815 curr
->hardirqs_enabled
= 1;
1816 ip
= (unsigned long) __builtin_return_address(0);
1818 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1820 if (DEBUG_LOCKS_WARN_ON(current
->hardirq_context
))
1823 * We are going to turn hardirqs on, so set the
1824 * usage bit for all held locks:
1826 if (!mark_held_locks(curr
, 1, ip
))
1829 * If we have softirqs enabled, then set the usage
1830 * bit for all held locks. (disabled hardirqs prevented
1831 * this bit from being set before)
1833 if (curr
->softirqs_enabled
)
1834 if (!mark_held_locks(curr
, 0, ip
))
1837 curr
->hardirq_enable_ip
= ip
;
1838 curr
->hardirq_enable_event
= ++curr
->irq_events
;
1839 debug_atomic_inc(&hardirqs_on_events
);
1842 EXPORT_SYMBOL(trace_hardirqs_on
);
1845 * Hardirqs were disabled:
1847 void trace_hardirqs_off(void)
1849 struct task_struct
*curr
= current
;
1851 if (unlikely(!debug_locks
|| current
->lockdep_recursion
))
1854 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1857 if (curr
->hardirqs_enabled
) {
1859 * We have done an ON -> OFF transition:
1861 curr
->hardirqs_enabled
= 0;
1862 curr
->hardirq_disable_ip
= _RET_IP_
;
1863 curr
->hardirq_disable_event
= ++curr
->irq_events
;
1864 debug_atomic_inc(&hardirqs_off_events
);
1866 debug_atomic_inc(&redundant_hardirqs_off
);
1869 EXPORT_SYMBOL(trace_hardirqs_off
);
1872 * Softirqs will be enabled:
1874 void trace_softirqs_on(unsigned long ip
)
1876 struct task_struct
*curr
= current
;
1878 if (unlikely(!debug_locks
))
1881 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1884 if (curr
->softirqs_enabled
) {
1885 debug_atomic_inc(&redundant_softirqs_on
);
1890 * We'll do an OFF -> ON transition:
1892 curr
->softirqs_enabled
= 1;
1893 curr
->softirq_enable_ip
= ip
;
1894 curr
->softirq_enable_event
= ++curr
->irq_events
;
1895 debug_atomic_inc(&softirqs_on_events
);
1897 * We are going to turn softirqs on, so set the
1898 * usage bit for all held locks, if hardirqs are
1901 if (curr
->hardirqs_enabled
)
1902 mark_held_locks(curr
, 0, ip
);
1906 * Softirqs were disabled:
1908 void trace_softirqs_off(unsigned long ip
)
1910 struct task_struct
*curr
= current
;
1912 if (unlikely(!debug_locks
))
1915 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1918 if (curr
->softirqs_enabled
) {
1920 * We have done an ON -> OFF transition:
1922 curr
->softirqs_enabled
= 0;
1923 curr
->softirq_disable_ip
= ip
;
1924 curr
->softirq_disable_event
= ++curr
->irq_events
;
1925 debug_atomic_inc(&softirqs_off_events
);
1926 DEBUG_LOCKS_WARN_ON(!softirq_count());
1928 debug_atomic_inc(&redundant_softirqs_off
);
1934 * Initialize a lock instance's lock-class mapping info:
1936 void lockdep_init_map(struct lockdep_map
*lock
, const char *name
,
1937 struct lock_class_key
*key
)
1939 if (unlikely(!debug_locks
))
1942 if (DEBUG_LOCKS_WARN_ON(!key
))
1944 if (DEBUG_LOCKS_WARN_ON(!name
))
1947 * Sanity check, the lock-class key must be persistent:
1949 if (!static_obj(key
)) {
1950 printk("BUG: key %p not in .data!\n", key
);
1951 DEBUG_LOCKS_WARN_ON(1);
1956 lock
->class_cache
= NULL
;
1959 EXPORT_SYMBOL_GPL(lockdep_init_map
);
1962 * This gets called for every mutex_lock*()/spin_lock*() operation.
1963 * We maintain the dependency maps and validate the locking attempt:
1965 static int __lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
1966 int trylock
, int read
, int check
, int hardirqs_off
,
1969 struct task_struct
*curr
= current
;
1970 struct lock_class
*class = NULL
;
1971 struct held_lock
*hlock
;
1972 unsigned int depth
, id
;
1976 if (unlikely(!debug_locks
))
1979 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1982 if (unlikely(subclass
>= MAX_LOCKDEP_SUBCLASSES
)) {
1984 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
1985 printk("turning off the locking correctness validator.\n");
1990 class = lock
->class_cache
;
1992 * Not cached yet or subclass?
1994 if (unlikely(!class)) {
1995 class = register_lock_class(lock
, subclass
);
1999 debug_atomic_inc((atomic_t
*)&class->ops
);
2000 if (very_verbose(class)) {
2001 printk("\nacquire class [%p] %s", class->key
, class->name
);
2002 if (class->name_version
> 1)
2003 printk("#%d", class->name_version
);
2009 * Add the lock to the list of currently held locks.
2010 * (we dont increase the depth just yet, up until the
2011 * dependency checks are done)
2013 depth
= curr
->lockdep_depth
;
2014 if (DEBUG_LOCKS_WARN_ON(depth
>= MAX_LOCK_DEPTH
))
2017 hlock
= curr
->held_locks
+ depth
;
2019 hlock
->class = class;
2020 hlock
->acquire_ip
= ip
;
2021 hlock
->instance
= lock
;
2022 hlock
->trylock
= trylock
;
2024 hlock
->check
= check
;
2025 hlock
->hardirqs_off
= hardirqs_off
;
2029 #ifdef CONFIG_TRACE_IRQFLAGS
2031 * If non-trylock use in a hardirq or softirq context, then
2032 * mark the lock as used in these contexts:
2036 if (curr
->hardirq_context
)
2037 if (!mark_lock(curr
, hlock
,
2038 LOCK_USED_IN_HARDIRQ_READ
, ip
))
2040 if (curr
->softirq_context
)
2041 if (!mark_lock(curr
, hlock
,
2042 LOCK_USED_IN_SOFTIRQ_READ
, ip
))
2045 if (curr
->hardirq_context
)
2046 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_HARDIRQ
, ip
))
2048 if (curr
->softirq_context
)
2049 if (!mark_lock(curr
, hlock
, LOCK_USED_IN_SOFTIRQ
, ip
))
2053 if (!hardirqs_off
) {
2055 if (!mark_lock(curr
, hlock
,
2056 LOCK_ENABLED_HARDIRQS_READ
, ip
))
2058 if (curr
->softirqs_enabled
)
2059 if (!mark_lock(curr
, hlock
,
2060 LOCK_ENABLED_SOFTIRQS_READ
, ip
))
2063 if (!mark_lock(curr
, hlock
,
2064 LOCK_ENABLED_HARDIRQS
, ip
))
2066 if (curr
->softirqs_enabled
)
2067 if (!mark_lock(curr
, hlock
,
2068 LOCK_ENABLED_SOFTIRQS
, ip
))
2073 /* mark it as used: */
2074 if (!mark_lock(curr
, hlock
, LOCK_USED
, ip
))
2078 * Calculate the chain hash: it's the combined has of all the
2079 * lock keys along the dependency chain. We save the hash value
2080 * at every step so that we can get the current hash easily
2081 * after unlock. The chain hash is then used to cache dependency
2084 * The 'key ID' is what is the most compact key value to drive
2085 * the hash, not class->key.
2087 id
= class - lock_classes
;
2088 if (DEBUG_LOCKS_WARN_ON(id
>= MAX_LOCKDEP_KEYS
))
2091 chain_key
= curr
->curr_chain_key
;
2093 if (DEBUG_LOCKS_WARN_ON(chain_key
!= 0))
2098 hlock
->prev_chain_key
= chain_key
;
2100 #ifdef CONFIG_TRACE_IRQFLAGS
2102 * Keep track of points where we cross into an interrupt context:
2104 hlock
->irq_context
= 2*(curr
->hardirq_context
? 1 : 0) +
2105 curr
->softirq_context
;
2107 struct held_lock
*prev_hlock
;
2109 prev_hlock
= curr
->held_locks
+ depth
-1;
2111 * If we cross into another context, reset the
2112 * hash key (this also prevents the checking and the
2113 * adding of the dependency to 'prev'):
2115 if (prev_hlock
->irq_context
!= hlock
->irq_context
) {
2121 chain_key
= iterate_chain_key(chain_key
, id
);
2122 curr
->curr_chain_key
= chain_key
;
2125 * Trylock needs to maintain the stack of held locks, but it
2126 * does not add new dependencies, because trylock can be done
2129 * We look up the chain_key and do the O(N^2) check and update of
2130 * the dependencies only if this is a new dependency chain.
2131 * (If lookup_chain_cache() returns with 1 it acquires
2134 if (!trylock
&& (check
== 2) && lookup_chain_cache(chain_key
)) {
2136 * Check whether last held lock:
2138 * - is irq-safe, if this lock is irq-unsafe
2139 * - is softirq-safe, if this lock is hardirq-unsafe
2141 * And check whether the new lock's dependency graph
2142 * could lead back to the previous lock.
2144 * any of these scenarios could lead to a deadlock. If
2147 int ret
= check_deadlock(curr
, hlock
, lock
, read
);
2152 * Mark recursive read, as we jump over it when
2153 * building dependencies (just like we jump over
2159 * Add dependency only if this lock is not the head
2160 * of the chain, and if it's not a secondary read-lock:
2162 if (!chain_head
&& ret
!= 2)
2163 if (!check_prevs_add(curr
, hlock
))
2165 __raw_spin_unlock(&hash_lock
);
2167 curr
->lockdep_depth
++;
2168 check_chain_key(curr
);
2169 if (unlikely(curr
->lockdep_depth
>= MAX_LOCK_DEPTH
)) {
2171 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2172 printk("turning off the locking correctness validator.\n");
2175 if (unlikely(curr
->lockdep_depth
> max_lockdep_depth
))
2176 max_lockdep_depth
= curr
->lockdep_depth
;
2182 print_unlock_inbalance_bug(struct task_struct
*curr
, struct lockdep_map
*lock
,
2185 if (!debug_locks_off())
2187 if (debug_locks_silent
)
2190 printk("\n=====================================\n");
2191 printk( "[ BUG: bad unlock balance detected! ]\n");
2192 printk( "-------------------------------------\n");
2193 printk("%s/%d is trying to release lock (",
2194 curr
->comm
, curr
->pid
);
2195 print_lockdep_cache(lock
);
2198 printk("but there are no more locks to release!\n");
2199 printk("\nother info that might help us debug this:\n");
2200 lockdep_print_held_locks(curr
);
2202 printk("\nstack backtrace:\n");
2209 * Common debugging checks for both nested and non-nested unlock:
2211 static int check_unlock(struct task_struct
*curr
, struct lockdep_map
*lock
,
2214 if (unlikely(!debug_locks
))
2216 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2219 if (curr
->lockdep_depth
<= 0)
2220 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2226 * Remove the lock to the list of currently held locks in a
2227 * potentially non-nested (out of order) manner. This is a
2228 * relatively rare operation, as all the unlock APIs default
2229 * to nested mode (which uses lock_release()):
2232 lock_release_non_nested(struct task_struct
*curr
,
2233 struct lockdep_map
*lock
, unsigned long ip
)
2235 struct held_lock
*hlock
, *prev_hlock
;
2240 * Check whether the lock exists in the current stack
2243 depth
= curr
->lockdep_depth
;
2244 if (DEBUG_LOCKS_WARN_ON(!depth
))
2248 for (i
= depth
-1; i
>= 0; i
--) {
2249 hlock
= curr
->held_locks
+ i
;
2251 * We must not cross into another context:
2253 if (prev_hlock
&& prev_hlock
->irq_context
!= hlock
->irq_context
)
2255 if (hlock
->instance
== lock
)
2259 return print_unlock_inbalance_bug(curr
, lock
, ip
);
2263 * We have the right lock to unlock, 'hlock' points to it.
2264 * Now we remove it from the stack, and add back the other
2265 * entries (if any), recalculating the hash along the way:
2267 curr
->lockdep_depth
= i
;
2268 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2270 for (i
++; i
< depth
; i
++) {
2271 hlock
= curr
->held_locks
+ i
;
2272 if (!__lock_acquire(hlock
->instance
,
2273 hlock
->class->subclass
, hlock
->trylock
,
2274 hlock
->read
, hlock
->check
, hlock
->hardirqs_off
,
2279 if (DEBUG_LOCKS_WARN_ON(curr
->lockdep_depth
!= depth
- 1))
2285 * Remove the lock to the list of currently held locks - this gets
2286 * called on mutex_unlock()/spin_unlock*() (or on a failed
2287 * mutex_lock_interruptible()). This is done for unlocks that nest
2288 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2290 static int lock_release_nested(struct task_struct
*curr
,
2291 struct lockdep_map
*lock
, unsigned long ip
)
2293 struct held_lock
*hlock
;
2297 * Pop off the top of the lock stack:
2299 depth
= curr
->lockdep_depth
- 1;
2300 hlock
= curr
->held_locks
+ depth
;
2303 * Is the unlock non-nested:
2305 if (hlock
->instance
!= lock
)
2306 return lock_release_non_nested(curr
, lock
, ip
);
2307 curr
->lockdep_depth
--;
2309 if (DEBUG_LOCKS_WARN_ON(!depth
&& (hlock
->prev_chain_key
!= 0)))
2312 curr
->curr_chain_key
= hlock
->prev_chain_key
;
2314 #ifdef CONFIG_DEBUG_LOCKDEP
2315 hlock
->prev_chain_key
= 0;
2316 hlock
->class = NULL
;
2317 hlock
->acquire_ip
= 0;
2318 hlock
->irq_context
= 0;
2324 * Remove the lock to the list of currently held locks - this gets
2325 * called on mutex_unlock()/spin_unlock*() (or on a failed
2326 * mutex_lock_interruptible()). This is done for unlocks that nest
2327 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2330 __lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2332 struct task_struct
*curr
= current
;
2334 if (!check_unlock(curr
, lock
, ip
))
2338 if (!lock_release_nested(curr
, lock
, ip
))
2341 if (!lock_release_non_nested(curr
, lock
, ip
))
2345 check_chain_key(curr
);
2349 * Check whether we follow the irq-flags state precisely:
2351 static void check_flags(unsigned long flags
)
2353 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2357 if (irqs_disabled_flags(flags
))
2358 DEBUG_LOCKS_WARN_ON(current
->hardirqs_enabled
);
2360 DEBUG_LOCKS_WARN_ON(!current
->hardirqs_enabled
);
2363 * We dont accurately track softirq state in e.g.
2364 * hardirq contexts (such as on 4KSTACKS), so only
2365 * check if not in hardirq contexts:
2367 if (!hardirq_count()) {
2368 if (softirq_count())
2369 DEBUG_LOCKS_WARN_ON(current
->softirqs_enabled
);
2371 DEBUG_LOCKS_WARN_ON(!current
->softirqs_enabled
);
2375 print_irqtrace_events(current
);
2380 * We are not always called with irqs disabled - do that here,
2381 * and also avoid lockdep recursion:
2383 void lock_acquire(struct lockdep_map
*lock
, unsigned int subclass
,
2384 int trylock
, int read
, int check
, unsigned long ip
)
2386 unsigned long flags
;
2388 if (unlikely(current
->lockdep_recursion
))
2391 raw_local_irq_save(flags
);
2394 current
->lockdep_recursion
= 1;
2395 __lock_acquire(lock
, subclass
, trylock
, read
, check
,
2396 irqs_disabled_flags(flags
), ip
);
2397 current
->lockdep_recursion
= 0;
2398 raw_local_irq_restore(flags
);
2401 EXPORT_SYMBOL_GPL(lock_acquire
);
2403 void lock_release(struct lockdep_map
*lock
, int nested
, unsigned long ip
)
2405 unsigned long flags
;
2407 if (unlikely(current
->lockdep_recursion
))
2410 raw_local_irq_save(flags
);
2412 current
->lockdep_recursion
= 1;
2413 __lock_release(lock
, nested
, ip
);
2414 current
->lockdep_recursion
= 0;
2415 raw_local_irq_restore(flags
);
2418 EXPORT_SYMBOL_GPL(lock_release
);
2421 * Used by the testsuite, sanitize the validator state
2422 * after a simulated failure:
2425 void lockdep_reset(void)
2427 unsigned long flags
;
2429 raw_local_irq_save(flags
);
2430 current
->curr_chain_key
= 0;
2431 current
->lockdep_depth
= 0;
2432 current
->lockdep_recursion
= 0;
2433 memset(current
->held_locks
, 0, MAX_LOCK_DEPTH
*sizeof(struct held_lock
));
2434 nr_hardirq_chains
= 0;
2435 nr_softirq_chains
= 0;
2436 nr_process_chains
= 0;
2438 raw_local_irq_restore(flags
);
2441 static void zap_class(struct lock_class
*class)
2446 * Remove all dependencies this lock is
2449 for (i
= 0; i
< nr_list_entries
; i
++) {
2450 if (list_entries
[i
].class == class)
2451 list_del_rcu(&list_entries
[i
].entry
);
2454 * Unhash the class and remove it from the all_lock_classes list:
2456 list_del_rcu(&class->hash_entry
);
2457 list_del_rcu(&class->lock_entry
);
2461 static inline int within(void *addr
, void *start
, unsigned long size
)
2463 return addr
>= start
&& addr
< start
+ size
;
2466 void lockdep_free_key_range(void *start
, unsigned long size
)
2468 struct lock_class
*class, *next
;
2469 struct list_head
*head
;
2470 unsigned long flags
;
2473 raw_local_irq_save(flags
);
2474 __raw_spin_lock(&hash_lock
);
2477 * Unhash all classes that were created by this module:
2479 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
2480 head
= classhash_table
+ i
;
2481 if (list_empty(head
))
2483 list_for_each_entry_safe(class, next
, head
, hash_entry
)
2484 if (within(class->key
, start
, size
))
2488 __raw_spin_unlock(&hash_lock
);
2489 raw_local_irq_restore(flags
);
2492 void lockdep_reset_lock(struct lockdep_map
*lock
)
2494 struct lock_class
*class, *next
;
2495 struct list_head
*head
;
2496 unsigned long flags
;
2499 raw_local_irq_save(flags
);
2502 * Remove all classes this lock might have:
2504 for (j
= 0; j
< MAX_LOCKDEP_SUBCLASSES
; j
++) {
2506 * If the class exists we look it up and zap it:
2508 class = look_up_lock_class(lock
, j
);
2513 * Debug check: in the end all mapped classes should
2516 __raw_spin_lock(&hash_lock
);
2517 for (i
= 0; i
< CLASSHASH_SIZE
; i
++) {
2518 head
= classhash_table
+ i
;
2519 if (list_empty(head
))
2521 list_for_each_entry_safe(class, next
, head
, hash_entry
) {
2522 if (unlikely(class == lock
->class_cache
)) {
2523 __raw_spin_unlock(&hash_lock
);
2524 DEBUG_LOCKS_WARN_ON(1);
2529 __raw_spin_unlock(&hash_lock
);
2532 raw_local_irq_restore(flags
);
2535 void __init
lockdep_init(void)
2540 * Some architectures have their own start_kernel()
2541 * code which calls lockdep_init(), while we also
2542 * call lockdep_init() from the start_kernel() itself,
2543 * and we want to initialize the hashes only once:
2545 if (lockdep_initialized
)
2548 for (i
= 0; i
< CLASSHASH_SIZE
; i
++)
2549 INIT_LIST_HEAD(classhash_table
+ i
);
2551 for (i
= 0; i
< CHAINHASH_SIZE
; i
++)
2552 INIT_LIST_HEAD(chainhash_table
+ i
);
2554 lockdep_initialized
= 1;
2557 void __init
lockdep_info(void)
2559 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
2561 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES
);
2562 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH
);
2563 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS
);
2564 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE
);
2565 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES
);
2566 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS
);
2567 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE
);
2569 printk(" memory used by lock dependency info: %lu kB\n",
2570 (sizeof(struct lock_class
) * MAX_LOCKDEP_KEYS
+
2571 sizeof(struct list_head
) * CLASSHASH_SIZE
+
2572 sizeof(struct lock_list
) * MAX_LOCKDEP_ENTRIES
+
2573 sizeof(struct lock_chain
) * MAX_LOCKDEP_CHAINS
+
2574 sizeof(struct list_head
) * CHAINHASH_SIZE
) / 1024);
2576 printk(" per task-struct memory footprint: %lu bytes\n",
2577 sizeof(struct held_lock
) * MAX_LOCK_DEPTH
);
2579 #ifdef CONFIG_DEBUG_LOCKDEP
2580 if (lockdep_init_error
)
2581 printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n");
2585 static inline int in_range(const void *start
, const void *addr
, const void *end
)
2587 return addr
>= start
&& addr
<= end
;
2591 print_freed_lock_bug(struct task_struct
*curr
, const void *mem_from
,
2592 const void *mem_to
, struct held_lock
*hlock
)
2594 if (!debug_locks_off())
2596 if (debug_locks_silent
)
2599 printk("\n=========================\n");
2600 printk( "[ BUG: held lock freed! ]\n");
2601 printk( "-------------------------\n");
2602 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
2603 curr
->comm
, curr
->pid
, mem_from
, mem_to
-1);
2605 lockdep_print_held_locks(curr
);
2607 printk("\nstack backtrace:\n");
2612 * Called when kernel memory is freed (or unmapped), or if a lock
2613 * is destroyed or reinitialized - this code checks whether there is
2614 * any held lock in the memory range of <from> to <to>:
2616 void debug_check_no_locks_freed(const void *mem_from
, unsigned long mem_len
)
2618 const void *mem_to
= mem_from
+ mem_len
, *lock_from
, *lock_to
;
2619 struct task_struct
*curr
= current
;
2620 struct held_lock
*hlock
;
2621 unsigned long flags
;
2624 if (unlikely(!debug_locks
))
2627 local_irq_save(flags
);
2628 for (i
= 0; i
< curr
->lockdep_depth
; i
++) {
2629 hlock
= curr
->held_locks
+ i
;
2631 lock_from
= (void *)hlock
->instance
;
2632 lock_to
= (void *)(hlock
->instance
+ 1);
2634 if (!in_range(mem_from
, lock_from
, mem_to
) &&
2635 !in_range(mem_from
, lock_to
, mem_to
))
2638 print_freed_lock_bug(curr
, mem_from
, mem_to
, hlock
);
2641 local_irq_restore(flags
);
2644 static void print_held_locks_bug(struct task_struct
*curr
)
2646 if (!debug_locks_off())
2648 if (debug_locks_silent
)
2651 printk("\n=====================================\n");
2652 printk( "[ BUG: lock held at task exit time! ]\n");
2653 printk( "-------------------------------------\n");
2654 printk("%s/%d is exiting with locks still held!\n",
2655 curr
->comm
, curr
->pid
);
2656 lockdep_print_held_locks(curr
);
2658 printk("\nstack backtrace:\n");
2662 void debug_check_no_locks_held(struct task_struct
*task
)
2664 if (unlikely(task
->lockdep_depth
> 0))
2665 print_held_locks_bug(task
);
2668 void debug_show_all_locks(void)
2670 struct task_struct
*g
, *p
;
2674 printk("\nShowing all locks held in the system:\n");
2677 * Here we try to get the tasklist_lock as hard as possible,
2678 * if not successful after 2 seconds we ignore it (but keep
2679 * trying). This is to enable a debug printout even if a
2680 * tasklist_lock-holding task deadlocks or crashes.
2683 if (!read_trylock(&tasklist_lock
)) {
2685 printk("hm, tasklist_lock locked, retrying... ");
2688 printk(" #%d", 10-count
);
2692 printk(" ignoring it.\n");
2696 printk(" locked it.\n");
2698 do_each_thread(g
, p
) {
2699 if (p
->lockdep_depth
)
2700 lockdep_print_held_locks(p
);
2702 if (read_trylock(&tasklist_lock
))
2704 } while_each_thread(g
, p
);
2707 printk("=============================================\n\n");
2710 read_unlock(&tasklist_lock
);
2713 EXPORT_SYMBOL_GPL(debug_show_all_locks
);
2715 void debug_show_held_locks(struct task_struct
*task
)
2717 lockdep_print_held_locks(task
);
2720 EXPORT_SYMBOL_GPL(debug_show_held_locks
);