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"
45 #ifdef CONFIG_PROVE_LOCKING
46 int prove_locking = 1;
47 module_param(prove_locking, int, 0644);
49 #define prove_locking 0
52 #ifdef CONFIG_LOCK_STAT
54 module_param(lock_stat, int, 0644);
60 * lockdep_lock: protects the lockdep graph, the hashes and the
61 * class/list/hash allocators.
63 * This is one of the rare exceptions where it's justified
64 * to use a raw spinlock - we really dont want the spinlock
65 * code to recurse back into the lockdep code...
67 static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
69 static int graph_lock(void)
71 __raw_spin_lock(&lockdep_lock);
73 * Make sure that if another CPU detected a bug while
74 * walking the graph we dont change it (while the other
75 * CPU is busy printing out stuff with the graph lock
79 __raw_spin_unlock(&lockdep_lock);
85 static inline int graph_unlock(void)
87 if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
88 return DEBUG_LOCKS_WARN_ON(1);
90 __raw_spin_unlock(&lockdep_lock);
95 * Turn lock debugging off and return with 0 if it was off already,
96 * and also release the graph lock:
98 static inline int debug_locks_off_graph_unlock(void)
100 int ret = debug_locks_off();
102 __raw_spin_unlock(&lockdep_lock);
107 static int lockdep_initialized;
109 unsigned long nr_list_entries;
110 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
113 * All data structures here are protected by the global debug_lock.
115 * Mutex key structs only get allocated, once during bootup, and never
116 * get freed - this significantly simplifies the debugging code.
118 unsigned long nr_lock_classes;
119 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
121 #ifdef CONFIG_LOCK_STAT
122 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
124 static int lock_contention_point(struct lock_class *class, unsigned long ip)
128 for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {
129 if (class->contention_point[i] == 0) {
130 class->contention_point[i] = ip;
133 if (class->contention_point[i] == ip)
140 static void lock_time_inc(struct lock_time *lt, s64 time)
145 if (time < lt->min || !lt->min)
152 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
154 return &get_cpu_var(lock_stats)[class - lock_classes];
157 static void put_lock_stats(struct lock_class_stats *stats)
159 put_cpu_var(lock_stats);
162 static void lock_release_holdtime(struct held_lock *hlock)
164 struct lock_class_stats *stats;
170 holdtime = sched_clock() - hlock->holdtime_stamp;
172 stats = get_lock_stats(hlock->class);
174 lock_time_inc(&stats->read_holdtime, holdtime);
176 lock_time_inc(&stats->write_holdtime, holdtime);
177 put_lock_stats(stats);
180 static inline void lock_release_holdtime(struct held_lock *hlock)
186 * We keep a global list of all lock classes. The list only grows,
187 * never shrinks. The list is only accessed with the lockdep
188 * spinlock lock held.
190 LIST_HEAD(all_lock_classes);
193 * The lockdep classes are in a hash-table as well, for fast lookup:
195 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
196 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
197 #define CLASSHASH_MASK (CLASSHASH_SIZE - 1)
198 #define __classhashfn(key) ((((unsigned long)key >> CLASSHASH_BITS) + (unsigned long)key) & CLASSHASH_MASK)
199 #define classhashentry(key) (classhash_table + __classhashfn((key)))
201 static struct list_head classhash_table[CLASSHASH_SIZE];
204 * We put the lock dependency chains into a hash-table as well, to cache
207 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
208 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
209 #define CHAINHASH_MASK (CHAINHASH_SIZE - 1)
210 #define __chainhashfn(chain) \
211 (((chain >> CHAINHASH_BITS) + chain) & CHAINHASH_MASK)
212 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
214 static struct list_head chainhash_table[CHAINHASH_SIZE];
217 * The hash key of the lock dependency chains is a hash itself too:
218 * it's a hash of all locks taken up to that lock, including that lock.
219 * It's a 64-bit hash, because it's important for the keys to be
222 #define iterate_chain_key(key1, key2) \
223 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
224 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
227 void lockdep_off(void)
229 current->lockdep_recursion++;
232 EXPORT_SYMBOL(lockdep_off);
234 void lockdep_on(void)
236 current->lockdep_recursion--;
239 EXPORT_SYMBOL(lockdep_on);
242 * Debugging switches:
246 #define VERY_VERBOSE 0
249 # define HARDIRQ_VERBOSE 1
250 # define SOFTIRQ_VERBOSE 1
252 # define HARDIRQ_VERBOSE 0
253 # define SOFTIRQ_VERBOSE 0
256 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
258 * Quick filtering for interesting events:
260 static int class_filter(struct lock_class *class)
264 if (class->name_version == 1 &&
265 !strcmp(class->name, "lockname"))
267 if (class->name_version == 1 &&
268 !strcmp(class->name, "&struct->lockfield"))
271 /* Filter everything else. 1 would be to allow everything else */
276 static int verbose(struct lock_class *class)
279 return class_filter(class);
285 * Stack-trace: tightly packed array of stack backtrace
286 * addresses. Protected by the graph_lock.
288 unsigned long nr_stack_trace_entries;
289 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
291 static int save_trace(struct stack_trace *trace)
293 trace->nr_entries = 0;
294 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
295 trace->entries = stack_trace + nr_stack_trace_entries;
299 save_stack_trace(trace);
301 trace->max_entries = trace->nr_entries;
303 nr_stack_trace_entries += trace->nr_entries;
305 if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
306 if (!debug_locks_off_graph_unlock())
309 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
310 printk("turning off the locking correctness validator.\n");
319 unsigned int nr_hardirq_chains;
320 unsigned int nr_softirq_chains;
321 unsigned int nr_process_chains;
322 unsigned int max_lockdep_depth;
323 unsigned int max_recursion_depth;
325 #ifdef CONFIG_DEBUG_LOCKDEP
327 * We cannot printk in early bootup code. Not even early_printk()
328 * might work. So we mark any initialization errors and printk
329 * about it later on, in lockdep_info().
331 static int lockdep_init_error;
334 * Various lockdep statistics:
336 atomic_t chain_lookup_hits;
337 atomic_t chain_lookup_misses;
338 atomic_t hardirqs_on_events;
339 atomic_t hardirqs_off_events;
340 atomic_t redundant_hardirqs_on;
341 atomic_t redundant_hardirqs_off;
342 atomic_t softirqs_on_events;
343 atomic_t softirqs_off_events;
344 atomic_t redundant_softirqs_on;
345 atomic_t redundant_softirqs_off;
346 atomic_t nr_unused_locks;
347 atomic_t nr_cyclic_checks;
348 atomic_t nr_cyclic_check_recursions;
349 atomic_t nr_find_usage_forwards_checks;
350 atomic_t nr_find_usage_forwards_recursions;
351 atomic_t nr_find_usage_backwards_checks;
352 atomic_t nr_find_usage_backwards_recursions;
353 # define debug_atomic_inc(ptr) atomic_inc(ptr)
354 # define debug_atomic_dec(ptr) atomic_dec(ptr)
355 # define debug_atomic_read(ptr) atomic_read(ptr)
357 # define debug_atomic_inc(ptr) do { } while (0)
358 # define debug_atomic_dec(ptr) do { } while (0)
359 # define debug_atomic_read(ptr) 0
366 static const char *usage_str[] =
368 [LOCK_USED] = "initial-use ",
369 [LOCK_USED_IN_HARDIRQ] = "in-hardirq-W",
370 [LOCK_USED_IN_SOFTIRQ] = "in-softirq-W",
371 [LOCK_ENABLED_SOFTIRQS] = "softirq-on-W",
372 [LOCK_ENABLED_HARDIRQS] = "hardirq-on-W",
373 [LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R",
374 [LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R",
375 [LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R",
376 [LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R",
379 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
381 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
385 get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
387 *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
389 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
392 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
395 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
398 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
401 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
403 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
405 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
409 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
411 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
413 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
418 static void print_lock_name(struct lock_class *class)
420 char str[KSYM_NAME_LEN], c1, c2, c3, c4;
423 get_usage_chars(class, &c1, &c2, &c3, &c4);
427 name = __get_key_name(class->key, str);
428 printk(" (%s", name);
430 printk(" (%s", name);
431 if (class->name_version > 1)
432 printk("#%d", class->name_version);
434 printk("/%d", class->subclass);
436 printk("){%c%c%c%c}", c1, c2, c3, c4);
439 static void print_lockdep_cache(struct lockdep_map *lock)
442 char str[KSYM_NAME_LEN];
446 name = __get_key_name(lock->key->subkeys, str);
451 static void print_lock(struct held_lock *hlock)
453 print_lock_name(hlock->class);
455 print_ip_sym(hlock->acquire_ip);
458 static void lockdep_print_held_locks(struct task_struct *curr)
460 int i, depth = curr->lockdep_depth;
463 printk("no locks held by %s/%d.\n", curr->comm, curr->pid);
466 printk("%d lock%s held by %s/%d:\n",
467 depth, depth > 1 ? "s" : "", curr->comm, curr->pid);
469 for (i = 0; i < depth; i++) {
471 print_lock(curr->held_locks + i);
475 static void print_lock_class_header(struct lock_class *class, int depth)
479 printk("%*s->", depth, "");
480 print_lock_name(class);
481 printk(" ops: %lu", class->ops);
484 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
485 if (class->usage_mask & (1 << bit)) {
488 len += printk("%*s %s", depth, "", usage_str[bit]);
489 len += printk(" at:\n");
490 print_stack_trace(class->usage_traces + bit, len);
493 printk("%*s }\n", depth, "");
495 printk("%*s ... key at: ",depth,"");
496 print_ip_sym((unsigned long)class->key);
500 * printk all lock dependencies starting at <entry>:
502 static void print_lock_dependencies(struct lock_class *class, int depth)
504 struct lock_list *entry;
506 if (DEBUG_LOCKS_WARN_ON(depth >= 20))
509 print_lock_class_header(class, depth);
511 list_for_each_entry(entry, &class->locks_after, entry) {
512 if (DEBUG_LOCKS_WARN_ON(!entry->class))
515 print_lock_dependencies(entry->class, depth + 1);
517 printk("%*s ... acquired at:\n",depth,"");
518 print_stack_trace(&entry->trace, 2);
523 static void print_kernel_version(void)
525 printk("%s %.*s\n", init_utsname()->release,
526 (int)strcspn(init_utsname()->version, " "),
527 init_utsname()->version);
530 static int very_verbose(struct lock_class *class)
533 return class_filter(class);
539 * Is this the address of a static object:
541 static int static_obj(void *obj)
543 unsigned long start = (unsigned long) &_stext,
544 end = (unsigned long) &_end,
545 addr = (unsigned long) obj;
553 if ((addr >= start) && (addr < end))
560 for_each_possible_cpu(i) {
561 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
562 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
565 if ((addr >= start) && (addr < end))
573 return is_module_address(addr);
577 * To make lock name printouts unique, we calculate a unique
578 * class->name_version generation counter:
580 static int count_matching_names(struct lock_class *new_class)
582 struct lock_class *class;
585 if (!new_class->name)
588 list_for_each_entry(class, &all_lock_classes, lock_entry) {
589 if (new_class->key - new_class->subclass == class->key)
590 return class->name_version;
591 if (class->name && !strcmp(class->name, new_class->name))
592 count = max(count, class->name_version);
599 * Register a lock's class in the hash-table, if the class is not present
600 * yet. Otherwise we look it up. We cache the result in the lock object
601 * itself, so actual lookup of the hash should be once per lock object.
603 static inline struct lock_class *
604 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
606 struct lockdep_subclass_key *key;
607 struct list_head *hash_head;
608 struct lock_class *class;
610 #ifdef CONFIG_DEBUG_LOCKDEP
612 * If the architecture calls into lockdep before initializing
613 * the hashes then we'll warn about it later. (we cannot printk
616 if (unlikely(!lockdep_initialized)) {
618 lockdep_init_error = 1;
623 * Static locks do not have their class-keys yet - for them the key
624 * is the lock object itself:
626 if (unlikely(!lock->key))
627 lock->key = (void *)lock;
630 * NOTE: the class-key must be unique. For dynamic locks, a static
631 * lock_class_key variable is passed in through the mutex_init()
632 * (or spin_lock_init()) call - which acts as the key. For static
633 * locks we use the lock object itself as the key.
635 BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(struct lock_class));
637 key = lock->key->subkeys + subclass;
639 hash_head = classhashentry(key);
642 * We can walk the hash lockfree, because the hash only
643 * grows, and we are careful when adding entries to the end:
645 list_for_each_entry(class, hash_head, hash_entry)
646 if (class->key == key)
653 * Register a lock's class in the hash-table, if the class is not present
654 * yet. Otherwise we look it up. We cache the result in the lock object
655 * itself, so actual lookup of the hash should be once per lock object.
657 static inline struct lock_class *
658 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
660 struct lockdep_subclass_key *key;
661 struct list_head *hash_head;
662 struct lock_class *class;
665 class = look_up_lock_class(lock, subclass);
670 * Debug-check: all keys must be persistent!
672 if (!static_obj(lock->key)) {
674 printk("INFO: trying to register non-static key.\n");
675 printk("the code is fine but needs lockdep annotation.\n");
676 printk("turning off the locking correctness validator.\n");
682 key = lock->key->subkeys + subclass;
683 hash_head = classhashentry(key);
685 raw_local_irq_save(flags);
687 raw_local_irq_restore(flags);
691 * We have to do the hash-walk again, to avoid races
694 list_for_each_entry(class, hash_head, hash_entry)
695 if (class->key == key)
698 * Allocate a new key from the static array, and add it to
701 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
702 if (!debug_locks_off_graph_unlock()) {
703 raw_local_irq_restore(flags);
706 raw_local_irq_restore(flags);
708 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
709 printk("turning off the locking correctness validator.\n");
712 class = lock_classes + nr_lock_classes++;
713 debug_atomic_inc(&nr_unused_locks);
715 class->name = lock->name;
716 class->subclass = subclass;
717 INIT_LIST_HEAD(&class->lock_entry);
718 INIT_LIST_HEAD(&class->locks_before);
719 INIT_LIST_HEAD(&class->locks_after);
720 class->name_version = count_matching_names(class);
722 * We use RCU's safe list-add method to make
723 * parallel walking of the hash-list safe:
725 list_add_tail_rcu(&class->hash_entry, hash_head);
727 if (verbose(class)) {
729 raw_local_irq_restore(flags);
731 printk("\nnew class %p: %s", class->key, class->name);
732 if (class->name_version > 1)
733 printk("#%d", class->name_version);
737 raw_local_irq_save(flags);
739 raw_local_irq_restore(flags);
745 raw_local_irq_restore(flags);
747 if (!subclass || force)
748 lock->class_cache = class;
750 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
756 #ifdef CONFIG_PROVE_LOCKING
758 * Allocate a lockdep entry. (assumes the graph_lock held, returns
759 * with NULL on failure)
761 static struct lock_list *alloc_list_entry(void)
763 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
764 if (!debug_locks_off_graph_unlock())
767 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
768 printk("turning off the locking correctness validator.\n");
771 return list_entries + nr_list_entries++;
775 * Add a new dependency to the head of the list:
777 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
778 struct list_head *head, unsigned long ip, int distance)
780 struct lock_list *entry;
782 * Lock not present yet - get a new dependency struct and
783 * add it to the list:
785 entry = alloc_list_entry();
790 entry->distance = distance;
791 if (!save_trace(&entry->trace))
795 * Since we never remove from the dependency list, the list can
796 * be walked lockless by other CPUs, it's only allocation
797 * that must be protected by the spinlock. But this also means
798 * we must make new entries visible only once writes to the
799 * entry become visible - hence the RCU op:
801 list_add_tail_rcu(&entry->entry, head);
807 * Recursive, forwards-direction lock-dependency checking, used for
808 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
811 * (to keep the stackframe of the recursive functions small we
812 * use these global variables, and we also mark various helper
813 * functions as noinline.)
815 static struct held_lock *check_source, *check_target;
818 * Print a dependency chain entry (this is only done when a deadlock
819 * has been detected):
822 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
824 if (debug_locks_silent)
826 printk("\n-> #%u", depth);
827 print_lock_name(target->class);
829 print_stack_trace(&target->trace, 6);
835 * When a circular dependency is detected, print the
839 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
841 struct task_struct *curr = current;
843 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
846 printk("\n=======================================================\n");
847 printk( "[ INFO: possible circular locking dependency detected ]\n");
848 print_kernel_version();
849 printk( "-------------------------------------------------------\n");
850 printk("%s/%d is trying to acquire lock:\n",
851 curr->comm, curr->pid);
852 print_lock(check_source);
853 printk("\nbut task is already holding lock:\n");
854 print_lock(check_target);
855 printk("\nwhich lock already depends on the new lock.\n\n");
856 printk("\nthe existing dependency chain (in reverse order) is:\n");
858 print_circular_bug_entry(entry, depth);
863 static noinline int print_circular_bug_tail(void)
865 struct task_struct *curr = current;
866 struct lock_list this;
868 if (debug_locks_silent)
871 this.class = check_source->class;
872 if (!save_trace(&this.trace))
875 print_circular_bug_entry(&this, 0);
877 printk("\nother info that might help us debug this:\n\n");
878 lockdep_print_held_locks(curr);
880 printk("\nstack backtrace:\n");
886 #define RECURSION_LIMIT 40
888 static int noinline print_infinite_recursion_bug(void)
890 if (!debug_locks_off_graph_unlock())
899 * Prove that the dependency graph starting at <entry> can not
900 * lead to <target>. Print an error and return 0 if it does.
903 check_noncircular(struct lock_class *source, unsigned int depth)
905 struct lock_list *entry;
907 debug_atomic_inc(&nr_cyclic_check_recursions);
908 if (depth > max_recursion_depth)
909 max_recursion_depth = depth;
910 if (depth >= RECURSION_LIMIT)
911 return print_infinite_recursion_bug();
913 * Check this lock's dependency list:
915 list_for_each_entry(entry, &source->locks_after, entry) {
916 if (entry->class == check_target->class)
917 return print_circular_bug_header(entry, depth+1);
918 debug_atomic_inc(&nr_cyclic_checks);
919 if (!check_noncircular(entry->class, depth+1))
920 return print_circular_bug_entry(entry, depth+1);
925 #ifdef CONFIG_TRACE_IRQFLAGS
927 * Forwards and backwards subgraph searching, for the purposes of
928 * proving that two subgraphs can be connected by a new dependency
929 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
931 static enum lock_usage_bit find_usage_bit;
932 static struct lock_class *forwards_match, *backwards_match;
935 * Find a node in the forwards-direction dependency sub-graph starting
936 * at <source> that matches <find_usage_bit>.
938 * Return 2 if such a node exists in the subgraph, and put that node
939 * into <forwards_match>.
941 * Return 1 otherwise and keep <forwards_match> unchanged.
945 find_usage_forwards(struct lock_class *source, unsigned int depth)
947 struct lock_list *entry;
950 if (depth > max_recursion_depth)
951 max_recursion_depth = depth;
952 if (depth >= RECURSION_LIMIT)
953 return print_infinite_recursion_bug();
955 debug_atomic_inc(&nr_find_usage_forwards_checks);
956 if (source->usage_mask & (1 << find_usage_bit)) {
957 forwards_match = source;
962 * Check this lock's dependency list:
964 list_for_each_entry(entry, &source->locks_after, entry) {
965 debug_atomic_inc(&nr_find_usage_forwards_recursions);
966 ret = find_usage_forwards(entry->class, depth+1);
967 if (ret == 2 || ret == 0)
974 * Find a node in the backwards-direction dependency sub-graph starting
975 * at <source> that matches <find_usage_bit>.
977 * Return 2 if such a node exists in the subgraph, and put that node
978 * into <backwards_match>.
980 * Return 1 otherwise and keep <backwards_match> unchanged.
984 find_usage_backwards(struct lock_class *source, unsigned int depth)
986 struct lock_list *entry;
989 if (!__raw_spin_is_locked(&lockdep_lock))
990 return DEBUG_LOCKS_WARN_ON(1);
992 if (depth > max_recursion_depth)
993 max_recursion_depth = depth;
994 if (depth >= RECURSION_LIMIT)
995 return print_infinite_recursion_bug();
997 debug_atomic_inc(&nr_find_usage_backwards_checks);
998 if (source->usage_mask & (1 << find_usage_bit)) {
999 backwards_match = source;
1004 * Check this lock's dependency list:
1006 list_for_each_entry(entry, &source->locks_before, entry) {
1007 debug_atomic_inc(&nr_find_usage_backwards_recursions);
1008 ret = find_usage_backwards(entry->class, depth+1);
1009 if (ret == 2 || ret == 0)
1016 print_bad_irq_dependency(struct task_struct *curr,
1017 struct held_lock *prev,
1018 struct held_lock *next,
1019 enum lock_usage_bit bit1,
1020 enum lock_usage_bit bit2,
1021 const char *irqclass)
1023 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1026 printk("\n======================================================\n");
1027 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1028 irqclass, irqclass);
1029 print_kernel_version();
1030 printk( "------------------------------------------------------\n");
1031 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1032 curr->comm, curr->pid,
1033 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1034 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1035 curr->hardirqs_enabled,
1036 curr->softirqs_enabled);
1039 printk("\nand this task is already holding:\n");
1041 printk("which would create a new lock dependency:\n");
1042 print_lock_name(prev->class);
1044 print_lock_name(next->class);
1047 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1049 print_lock_name(backwards_match);
1050 printk("\n... which became %s-irq-safe at:\n", irqclass);
1052 print_stack_trace(backwards_match->usage_traces + bit1, 1);
1054 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1055 print_lock_name(forwards_match);
1056 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1059 print_stack_trace(forwards_match->usage_traces + bit2, 1);
1061 printk("\nother info that might help us debug this:\n\n");
1062 lockdep_print_held_locks(curr);
1064 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1065 print_lock_dependencies(backwards_match, 0);
1067 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1068 print_lock_dependencies(forwards_match, 0);
1070 printk("\nstack backtrace:\n");
1077 check_usage(struct task_struct *curr, struct held_lock *prev,
1078 struct held_lock *next, enum lock_usage_bit bit_backwards,
1079 enum lock_usage_bit bit_forwards, const char *irqclass)
1083 find_usage_bit = bit_backwards;
1084 /* fills in <backwards_match> */
1085 ret = find_usage_backwards(prev->class, 0);
1086 if (!ret || ret == 1)
1089 find_usage_bit = bit_forwards;
1090 ret = find_usage_forwards(next->class, 0);
1091 if (!ret || ret == 1)
1094 return print_bad_irq_dependency(curr, prev, next,
1095 bit_backwards, bit_forwards, irqclass);
1099 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1100 struct held_lock *next)
1103 * Prove that the new dependency does not connect a hardirq-safe
1104 * lock with a hardirq-unsafe lock - to achieve this we search
1105 * the backwards-subgraph starting at <prev>, and the
1106 * forwards-subgraph starting at <next>:
1108 if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
1109 LOCK_ENABLED_HARDIRQS, "hard"))
1113 * Prove that the new dependency does not connect a hardirq-safe-read
1114 * lock with a hardirq-unsafe lock - to achieve this we search
1115 * the backwards-subgraph starting at <prev>, and the
1116 * forwards-subgraph starting at <next>:
1118 if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
1119 LOCK_ENABLED_HARDIRQS, "hard-read"))
1123 * Prove that the new dependency does not connect a softirq-safe
1124 * lock with a softirq-unsafe lock - to achieve this we search
1125 * the backwards-subgraph starting at <prev>, and the
1126 * forwards-subgraph starting at <next>:
1128 if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
1129 LOCK_ENABLED_SOFTIRQS, "soft"))
1132 * Prove that the new dependency does not connect a softirq-safe-read
1133 * lock with a softirq-unsafe lock - to achieve this we search
1134 * the backwards-subgraph starting at <prev>, and the
1135 * forwards-subgraph starting at <next>:
1137 if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
1138 LOCK_ENABLED_SOFTIRQS, "soft"))
1144 static void inc_chains(void)
1146 if (current->hardirq_context)
1147 nr_hardirq_chains++;
1149 if (current->softirq_context)
1150 nr_softirq_chains++;
1152 nr_process_chains++;
1159 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1160 struct held_lock *next)
1165 static inline void inc_chains(void)
1167 nr_process_chains++;
1173 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1174 struct held_lock *next)
1176 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1179 printk("\n=============================================\n");
1180 printk( "[ INFO: possible recursive locking detected ]\n");
1181 print_kernel_version();
1182 printk( "---------------------------------------------\n");
1183 printk("%s/%d is trying to acquire lock:\n",
1184 curr->comm, curr->pid);
1186 printk("\nbut task is already holding lock:\n");
1189 printk("\nother info that might help us debug this:\n");
1190 lockdep_print_held_locks(curr);
1192 printk("\nstack backtrace:\n");
1199 * Check whether we are holding such a class already.
1201 * (Note that this has to be done separately, because the graph cannot
1202 * detect such classes of deadlocks.)
1204 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1207 check_deadlock(struct task_struct *curr, struct held_lock *next,
1208 struct lockdep_map *next_instance, int read)
1210 struct held_lock *prev;
1213 for (i = 0; i < curr->lockdep_depth; i++) {
1214 prev = curr->held_locks + i;
1215 if (prev->class != next->class)
1218 * Allow read-after-read recursion of the same
1219 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1221 if ((read == 2) && prev->read)
1223 return print_deadlock_bug(curr, prev, next);
1229 * There was a chain-cache miss, and we are about to add a new dependency
1230 * to a previous lock. We recursively validate the following rules:
1232 * - would the adding of the <prev> -> <next> dependency create a
1233 * circular dependency in the graph? [== circular deadlock]
1235 * - does the new prev->next dependency connect any hardirq-safe lock
1236 * (in the full backwards-subgraph starting at <prev>) with any
1237 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1238 * <next>)? [== illegal lock inversion with hardirq contexts]
1240 * - does the new prev->next dependency connect any softirq-safe lock
1241 * (in the full backwards-subgraph starting at <prev>) with any
1242 * softirq-unsafe lock (in the full forwards-subgraph starting at
1243 * <next>)? [== illegal lock inversion with softirq contexts]
1245 * any of these scenarios could lead to a deadlock.
1247 * Then if all the validations pass, we add the forwards and backwards
1251 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1252 struct held_lock *next, int distance)
1254 struct lock_list *entry;
1258 * Prove that the new <prev> -> <next> dependency would not
1259 * create a circular dependency in the graph. (We do this by
1260 * forward-recursing into the graph starting at <next>, and
1261 * checking whether we can reach <prev>.)
1263 * We are using global variables to control the recursion, to
1264 * keep the stackframe size of the recursive functions low:
1266 check_source = next;
1267 check_target = prev;
1268 if (!(check_noncircular(next->class, 0)))
1269 return print_circular_bug_tail();
1271 if (!check_prev_add_irq(curr, prev, next))
1275 * For recursive read-locks we do all the dependency checks,
1276 * but we dont store read-triggered dependencies (only
1277 * write-triggered dependencies). This ensures that only the
1278 * write-side dependencies matter, and that if for example a
1279 * write-lock never takes any other locks, then the reads are
1280 * equivalent to a NOP.
1282 if (next->read == 2 || prev->read == 2)
1285 * Is the <prev> -> <next> dependency already present?
1287 * (this may occur even though this is a new chain: consider
1288 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1289 * chains - the second one will be new, but L1 already has
1290 * L2 added to its dependency list, due to the first chain.)
1292 list_for_each_entry(entry, &prev->class->locks_after, entry) {
1293 if (entry->class == next->class) {
1295 entry->distance = 1;
1301 * Ok, all validations passed, add the new lock
1302 * to the previous lock's dependency list:
1304 ret = add_lock_to_list(prev->class, next->class,
1305 &prev->class->locks_after, next->acquire_ip, distance);
1310 ret = add_lock_to_list(next->class, prev->class,
1311 &next->class->locks_before, next->acquire_ip, distance);
1316 * Debugging printouts:
1318 if (verbose(prev->class) || verbose(next->class)) {
1320 printk("\n new dependency: ");
1321 print_lock_name(prev->class);
1323 print_lock_name(next->class);
1326 return graph_lock();
1332 * Add the dependency to all directly-previous locks that are 'relevant'.
1333 * The ones that are relevant are (in increasing distance from curr):
1334 * all consecutive trylock entries and the final non-trylock entry - or
1335 * the end of this context's lock-chain - whichever comes first.
1338 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1340 int depth = curr->lockdep_depth;
1341 struct held_lock *hlock;
1346 * Depth must not be zero for a non-head lock:
1351 * At least two relevant locks must exist for this
1354 if (curr->held_locks[depth].irq_context !=
1355 curr->held_locks[depth-1].irq_context)
1359 int distance = curr->lockdep_depth - depth + 1;
1360 hlock = curr->held_locks + depth-1;
1362 * Only non-recursive-read entries get new dependencies
1365 if (hlock->read != 2) {
1366 if (!check_prev_add(curr, hlock, next, distance))
1369 * Stop after the first non-trylock entry,
1370 * as non-trylock entries have added their
1371 * own direct dependencies already, so this
1372 * lock is connected to them indirectly:
1374 if (!hlock->trylock)
1379 * End of lock-stack?
1384 * Stop the search if we cross into another context:
1386 if (curr->held_locks[depth].irq_context !=
1387 curr->held_locks[depth-1].irq_context)
1392 if (!debug_locks_off_graph_unlock())
1400 unsigned long nr_lock_chains;
1401 static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1404 * Look up a dependency chain. If the key is not present yet then
1405 * add it and return 1 - in this case the new dependency chain is
1406 * validated. If the key is already hashed, return 0.
1407 * (On return with 1 graph_lock is held.)
1409 static inline int lookup_chain_cache(u64 chain_key, struct lock_class *class)
1411 struct list_head *hash_head = chainhashentry(chain_key);
1412 struct lock_chain *chain;
1414 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1417 * We can walk it lock-free, because entries only get added
1420 list_for_each_entry(chain, hash_head, entry) {
1421 if (chain->chain_key == chain_key) {
1423 debug_atomic_inc(&chain_lookup_hits);
1424 if (very_verbose(class))
1425 printk("\nhash chain already cached, key: "
1426 "%016Lx tail class: [%p] %s\n",
1427 (unsigned long long)chain_key,
1428 class->key, class->name);
1432 if (very_verbose(class))
1433 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1434 (unsigned long long)chain_key, class->key, class->name);
1436 * Allocate a new chain entry from the static array, and add
1442 * We have to walk the chain again locked - to avoid duplicates:
1444 list_for_each_entry(chain, hash_head, entry) {
1445 if (chain->chain_key == chain_key) {
1450 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1451 if (!debug_locks_off_graph_unlock())
1454 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1455 printk("turning off the locking correctness validator.\n");
1458 chain = lock_chains + nr_lock_chains++;
1459 chain->chain_key = chain_key;
1460 list_add_tail_rcu(&chain->entry, hash_head);
1461 debug_atomic_inc(&chain_lookup_misses);
1467 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1468 struct held_lock *hlock, int chain_head)
1471 * Trylock needs to maintain the stack of held locks, but it
1472 * does not add new dependencies, because trylock can be done
1475 * We look up the chain_key and do the O(N^2) check and update of
1476 * the dependencies only if this is a new dependency chain.
1477 * (If lookup_chain_cache() returns with 1 it acquires
1478 * graph_lock for us)
1480 if (!hlock->trylock && (hlock->check == 2) &&
1481 lookup_chain_cache(curr->curr_chain_key, hlock->class)) {
1483 * Check whether last held lock:
1485 * - is irq-safe, if this lock is irq-unsafe
1486 * - is softirq-safe, if this lock is hardirq-unsafe
1488 * And check whether the new lock's dependency graph
1489 * could lead back to the previous lock.
1491 * any of these scenarios could lead to a deadlock. If
1494 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1499 * Mark recursive read, as we jump over it when
1500 * building dependencies (just like we jump over
1506 * Add dependency only if this lock is not the head
1507 * of the chain, and if it's not a secondary read-lock:
1509 if (!chain_head && ret != 2)
1510 if (!check_prevs_add(curr, hlock))
1514 /* after lookup_chain_cache(): */
1515 if (unlikely(!debug_locks))
1521 static inline int validate_chain(struct task_struct *curr,
1522 struct lockdep_map *lock, struct held_lock *hlock,
1530 * We are building curr_chain_key incrementally, so double-check
1531 * it from scratch, to make sure that it's done correctly:
1533 static void check_chain_key(struct task_struct *curr)
1535 #ifdef CONFIG_DEBUG_LOCKDEP
1536 struct held_lock *hlock, *prev_hlock = NULL;
1540 for (i = 0; i < curr->lockdep_depth; i++) {
1541 hlock = curr->held_locks + i;
1542 if (chain_key != hlock->prev_chain_key) {
1544 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1545 curr->lockdep_depth, i,
1546 (unsigned long long)chain_key,
1547 (unsigned long long)hlock->prev_chain_key);
1551 id = hlock->class - lock_classes;
1552 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1555 if (prev_hlock && (prev_hlock->irq_context !=
1556 hlock->irq_context))
1558 chain_key = iterate_chain_key(chain_key, id);
1561 if (chain_key != curr->curr_chain_key) {
1563 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1564 curr->lockdep_depth, i,
1565 (unsigned long long)chain_key,
1566 (unsigned long long)curr->curr_chain_key);
1573 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1574 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1576 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1579 printk("\n=================================\n");
1580 printk( "[ INFO: inconsistent lock state ]\n");
1581 print_kernel_version();
1582 printk( "---------------------------------\n");
1584 printk("inconsistent {%s} -> {%s} usage.\n",
1585 usage_str[prev_bit], usage_str[new_bit]);
1587 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1588 curr->comm, curr->pid,
1589 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1590 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1591 trace_hardirqs_enabled(curr),
1592 trace_softirqs_enabled(curr));
1595 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1596 print_stack_trace(this->class->usage_traces + prev_bit, 1);
1598 print_irqtrace_events(curr);
1599 printk("\nother info that might help us debug this:\n");
1600 lockdep_print_held_locks(curr);
1602 printk("\nstack backtrace:\n");
1609 * Print out an error if an invalid bit is set:
1612 valid_state(struct task_struct *curr, struct held_lock *this,
1613 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1615 if (unlikely(this->class->usage_mask & (1 << bad_bit)))
1616 return print_usage_bug(curr, this, bad_bit, new_bit);
1620 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1621 enum lock_usage_bit new_bit);
1623 #ifdef CONFIG_TRACE_IRQFLAGS
1626 * print irq inversion bug:
1629 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1630 struct held_lock *this, int forwards,
1631 const char *irqclass)
1633 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1636 printk("\n=========================================================\n");
1637 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
1638 print_kernel_version();
1639 printk( "---------------------------------------------------------\n");
1640 printk("%s/%d just changed the state of lock:\n",
1641 curr->comm, curr->pid);
1644 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1646 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1647 print_lock_name(other);
1648 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1650 printk("\nother info that might help us debug this:\n");
1651 lockdep_print_held_locks(curr);
1653 printk("\nthe first lock's dependencies:\n");
1654 print_lock_dependencies(this->class, 0);
1656 printk("\nthe second lock's dependencies:\n");
1657 print_lock_dependencies(other, 0);
1659 printk("\nstack backtrace:\n");
1666 * Prove that in the forwards-direction subgraph starting at <this>
1667 * there is no lock matching <mask>:
1670 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1671 enum lock_usage_bit bit, const char *irqclass)
1675 find_usage_bit = bit;
1676 /* fills in <forwards_match> */
1677 ret = find_usage_forwards(this->class, 0);
1678 if (!ret || ret == 1)
1681 return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1685 * Prove that in the backwards-direction subgraph starting at <this>
1686 * there is no lock matching <mask>:
1689 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1690 enum lock_usage_bit bit, const char *irqclass)
1694 find_usage_bit = bit;
1695 /* fills in <backwards_match> */
1696 ret = find_usage_backwards(this->class, 0);
1697 if (!ret || ret == 1)
1700 return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1703 void print_irqtrace_events(struct task_struct *curr)
1705 printk("irq event stamp: %u\n", curr->irq_events);
1706 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
1707 print_ip_sym(curr->hardirq_enable_ip);
1708 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1709 print_ip_sym(curr->hardirq_disable_ip);
1710 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
1711 print_ip_sym(curr->softirq_enable_ip);
1712 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1713 print_ip_sym(curr->softirq_disable_ip);
1716 static int hardirq_verbose(struct lock_class *class)
1719 return class_filter(class);
1724 static int softirq_verbose(struct lock_class *class)
1727 return class_filter(class);
1732 #define STRICT_READ_CHECKS 1
1734 static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
1735 enum lock_usage_bit new_bit)
1740 case LOCK_USED_IN_HARDIRQ:
1741 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1743 if (!valid_state(curr, this, new_bit,
1744 LOCK_ENABLED_HARDIRQS_READ))
1747 * just marked it hardirq-safe, check that this lock
1748 * took no hardirq-unsafe lock in the past:
1750 if (!check_usage_forwards(curr, this,
1751 LOCK_ENABLED_HARDIRQS, "hard"))
1753 #if STRICT_READ_CHECKS
1755 * just marked it hardirq-safe, check that this lock
1756 * took no hardirq-unsafe-read lock in the past:
1758 if (!check_usage_forwards(curr, this,
1759 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1762 if (hardirq_verbose(this->class))
1765 case LOCK_USED_IN_SOFTIRQ:
1766 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1768 if (!valid_state(curr, this, new_bit,
1769 LOCK_ENABLED_SOFTIRQS_READ))
1772 * just marked it softirq-safe, check that this lock
1773 * took no softirq-unsafe lock in the past:
1775 if (!check_usage_forwards(curr, this,
1776 LOCK_ENABLED_SOFTIRQS, "soft"))
1778 #if STRICT_READ_CHECKS
1780 * just marked it softirq-safe, check that this lock
1781 * took no softirq-unsafe-read lock in the past:
1783 if (!check_usage_forwards(curr, this,
1784 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
1787 if (softirq_verbose(this->class))
1790 case LOCK_USED_IN_HARDIRQ_READ:
1791 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1794 * just marked it hardirq-read-safe, check that this lock
1795 * took no hardirq-unsafe lock in the past:
1797 if (!check_usage_forwards(curr, this,
1798 LOCK_ENABLED_HARDIRQS, "hard"))
1800 if (hardirq_verbose(this->class))
1803 case LOCK_USED_IN_SOFTIRQ_READ:
1804 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1807 * just marked it softirq-read-safe, check that this lock
1808 * took no softirq-unsafe lock in the past:
1810 if (!check_usage_forwards(curr, this,
1811 LOCK_ENABLED_SOFTIRQS, "soft"))
1813 if (softirq_verbose(this->class))
1816 case LOCK_ENABLED_HARDIRQS:
1817 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1819 if (!valid_state(curr, this, new_bit,
1820 LOCK_USED_IN_HARDIRQ_READ))
1823 * just marked it hardirq-unsafe, check that no hardirq-safe
1824 * lock in the system ever took it in the past:
1826 if (!check_usage_backwards(curr, this,
1827 LOCK_USED_IN_HARDIRQ, "hard"))
1829 #if STRICT_READ_CHECKS
1831 * just marked it hardirq-unsafe, check that no
1832 * hardirq-safe-read lock in the system ever took
1835 if (!check_usage_backwards(curr, this,
1836 LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
1839 if (hardirq_verbose(this->class))
1842 case LOCK_ENABLED_SOFTIRQS:
1843 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1845 if (!valid_state(curr, this, new_bit,
1846 LOCK_USED_IN_SOFTIRQ_READ))
1849 * just marked it softirq-unsafe, check that no softirq-safe
1850 * lock in the system ever took it in the past:
1852 if (!check_usage_backwards(curr, this,
1853 LOCK_USED_IN_SOFTIRQ, "soft"))
1855 #if STRICT_READ_CHECKS
1857 * just marked it softirq-unsafe, check that no
1858 * softirq-safe-read lock in the system ever took
1861 if (!check_usage_backwards(curr, this,
1862 LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
1865 if (softirq_verbose(this->class))
1868 case LOCK_ENABLED_HARDIRQS_READ:
1869 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1871 #if STRICT_READ_CHECKS
1873 * just marked it hardirq-read-unsafe, check that no
1874 * hardirq-safe lock in the system ever took it in the past:
1876 if (!check_usage_backwards(curr, this,
1877 LOCK_USED_IN_HARDIRQ, "hard"))
1880 if (hardirq_verbose(this->class))
1883 case LOCK_ENABLED_SOFTIRQS_READ:
1884 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1886 #if STRICT_READ_CHECKS
1888 * just marked it softirq-read-unsafe, check that no
1889 * softirq-safe lock in the system ever took it in the past:
1891 if (!check_usage_backwards(curr, this,
1892 LOCK_USED_IN_SOFTIRQ, "soft"))
1895 if (softirq_verbose(this->class))
1907 * Mark all held locks with a usage bit:
1910 mark_held_locks(struct task_struct *curr, int hardirq)
1912 enum lock_usage_bit usage_bit;
1913 struct held_lock *hlock;
1916 for (i = 0; i < curr->lockdep_depth; i++) {
1917 hlock = curr->held_locks + i;
1921 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
1923 usage_bit = LOCK_ENABLED_HARDIRQS;
1926 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
1928 usage_bit = LOCK_ENABLED_SOFTIRQS;
1930 if (!mark_lock(curr, hlock, usage_bit))
1938 * Debugging helper: via this flag we know that we are in
1939 * 'early bootup code', and will warn about any invalid irqs-on event:
1941 static int early_boot_irqs_enabled;
1943 void early_boot_irqs_off(void)
1945 early_boot_irqs_enabled = 0;
1948 void early_boot_irqs_on(void)
1950 early_boot_irqs_enabled = 1;
1954 * Hardirqs will be enabled:
1956 void trace_hardirqs_on(void)
1958 struct task_struct *curr = current;
1961 if (unlikely(!debug_locks || current->lockdep_recursion))
1964 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
1967 if (unlikely(curr->hardirqs_enabled)) {
1968 debug_atomic_inc(&redundant_hardirqs_on);
1971 /* we'll do an OFF -> ON transition: */
1972 curr->hardirqs_enabled = 1;
1973 ip = (unsigned long) __builtin_return_address(0);
1975 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1977 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
1980 * We are going to turn hardirqs on, so set the
1981 * usage bit for all held locks:
1983 if (!mark_held_locks(curr, 1))
1986 * If we have softirqs enabled, then set the usage
1987 * bit for all held locks. (disabled hardirqs prevented
1988 * this bit from being set before)
1990 if (curr->softirqs_enabled)
1991 if (!mark_held_locks(curr, 0))
1994 curr->hardirq_enable_ip = ip;
1995 curr->hardirq_enable_event = ++curr->irq_events;
1996 debug_atomic_inc(&hardirqs_on_events);
1999 EXPORT_SYMBOL(trace_hardirqs_on);
2002 * Hardirqs were disabled:
2004 void trace_hardirqs_off(void)
2006 struct task_struct *curr = current;
2008 if (unlikely(!debug_locks || current->lockdep_recursion))
2011 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2014 if (curr->hardirqs_enabled) {
2016 * We have done an ON -> OFF transition:
2018 curr->hardirqs_enabled = 0;
2019 curr->hardirq_disable_ip = _RET_IP_;
2020 curr->hardirq_disable_event = ++curr->irq_events;
2021 debug_atomic_inc(&hardirqs_off_events);
2023 debug_atomic_inc(&redundant_hardirqs_off);
2026 EXPORT_SYMBOL(trace_hardirqs_off);
2029 * Softirqs will be enabled:
2031 void trace_softirqs_on(unsigned long ip)
2033 struct task_struct *curr = current;
2035 if (unlikely(!debug_locks))
2038 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2041 if (curr->softirqs_enabled) {
2042 debug_atomic_inc(&redundant_softirqs_on);
2047 * We'll do an OFF -> ON transition:
2049 curr->softirqs_enabled = 1;
2050 curr->softirq_enable_ip = ip;
2051 curr->softirq_enable_event = ++curr->irq_events;
2052 debug_atomic_inc(&softirqs_on_events);
2054 * We are going to turn softirqs on, so set the
2055 * usage bit for all held locks, if hardirqs are
2058 if (curr->hardirqs_enabled)
2059 mark_held_locks(curr, 0);
2063 * Softirqs were disabled:
2065 void trace_softirqs_off(unsigned long ip)
2067 struct task_struct *curr = current;
2069 if (unlikely(!debug_locks))
2072 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2075 if (curr->softirqs_enabled) {
2077 * We have done an ON -> OFF transition:
2079 curr->softirqs_enabled = 0;
2080 curr->softirq_disable_ip = ip;
2081 curr->softirq_disable_event = ++curr->irq_events;
2082 debug_atomic_inc(&softirqs_off_events);
2083 DEBUG_LOCKS_WARN_ON(!softirq_count());
2085 debug_atomic_inc(&redundant_softirqs_off);
2088 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2091 * If non-trylock use in a hardirq or softirq context, then
2092 * mark the lock as used in these contexts:
2094 if (!hlock->trylock) {
2096 if (curr->hardirq_context)
2097 if (!mark_lock(curr, hlock,
2098 LOCK_USED_IN_HARDIRQ_READ))
2100 if (curr->softirq_context)
2101 if (!mark_lock(curr, hlock,
2102 LOCK_USED_IN_SOFTIRQ_READ))
2105 if (curr->hardirq_context)
2106 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2108 if (curr->softirq_context)
2109 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2113 if (!hlock->hardirqs_off) {
2115 if (!mark_lock(curr, hlock,
2116 LOCK_ENABLED_HARDIRQS_READ))
2118 if (curr->softirqs_enabled)
2119 if (!mark_lock(curr, hlock,
2120 LOCK_ENABLED_SOFTIRQS_READ))
2123 if (!mark_lock(curr, hlock,
2124 LOCK_ENABLED_HARDIRQS))
2126 if (curr->softirqs_enabled)
2127 if (!mark_lock(curr, hlock,
2128 LOCK_ENABLED_SOFTIRQS))
2136 static int separate_irq_context(struct task_struct *curr,
2137 struct held_lock *hlock)
2139 unsigned int depth = curr->lockdep_depth;
2142 * Keep track of points where we cross into an interrupt context:
2144 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2145 curr->softirq_context;
2147 struct held_lock *prev_hlock;
2149 prev_hlock = curr->held_locks + depth-1;
2151 * If we cross into another context, reset the
2152 * hash key (this also prevents the checking and the
2153 * adding of the dependency to 'prev'):
2155 if (prev_hlock->irq_context != hlock->irq_context)
2164 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2165 enum lock_usage_bit new_bit)
2171 static inline int mark_irqflags(struct task_struct *curr,
2172 struct held_lock *hlock)
2177 static inline int separate_irq_context(struct task_struct *curr,
2178 struct held_lock *hlock)
2186 * Mark a lock with a usage bit, and validate the state transition:
2188 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2189 enum lock_usage_bit new_bit)
2191 unsigned int new_mask = 1 << new_bit, ret = 1;
2194 * If already set then do not dirty the cacheline,
2195 * nor do any checks:
2197 if (likely(this->class->usage_mask & new_mask))
2203 * Make sure we didnt race:
2205 if (unlikely(this->class->usage_mask & new_mask)) {
2210 this->class->usage_mask |= new_mask;
2212 if (!save_trace(this->class->usage_traces + new_bit))
2216 case LOCK_USED_IN_HARDIRQ:
2217 case LOCK_USED_IN_SOFTIRQ:
2218 case LOCK_USED_IN_HARDIRQ_READ:
2219 case LOCK_USED_IN_SOFTIRQ_READ:
2220 case LOCK_ENABLED_HARDIRQS:
2221 case LOCK_ENABLED_SOFTIRQS:
2222 case LOCK_ENABLED_HARDIRQS_READ:
2223 case LOCK_ENABLED_SOFTIRQS_READ:
2224 ret = mark_lock_irq(curr, this, new_bit);
2230 * Add it to the global list of classes:
2232 list_add_tail_rcu(&this->class->lock_entry, &all_lock_classes);
2233 debug_atomic_dec(&nr_unused_locks);
2236 if (!debug_locks_off_graph_unlock())
2245 * We must printk outside of the graph_lock:
2248 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2250 print_irqtrace_events(curr);
2258 * Initialize a lock instance's lock-class mapping info:
2260 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2261 struct lock_class_key *key, int subclass)
2263 if (unlikely(!debug_locks))
2266 if (DEBUG_LOCKS_WARN_ON(!key))
2268 if (DEBUG_LOCKS_WARN_ON(!name))
2271 * Sanity check, the lock-class key must be persistent:
2273 if (!static_obj(key)) {
2274 printk("BUG: key %p not in .data!\n", key);
2275 DEBUG_LOCKS_WARN_ON(1);
2280 lock->class_cache = NULL;
2282 register_lock_class(lock, subclass, 1);
2285 EXPORT_SYMBOL_GPL(lockdep_init_map);
2288 * This gets called for every mutex_lock*()/spin_lock*() operation.
2289 * We maintain the dependency maps and validate the locking attempt:
2291 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2292 int trylock, int read, int check, int hardirqs_off,
2295 struct task_struct *curr = current;
2296 struct lock_class *class = NULL;
2297 struct held_lock *hlock;
2298 unsigned int depth, id;
2305 if (unlikely(!debug_locks))
2308 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2311 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2313 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2314 printk("turning off the locking correctness validator.\n");
2319 class = lock->class_cache;
2321 * Not cached yet or subclass?
2323 if (unlikely(!class)) {
2324 class = register_lock_class(lock, subclass, 0);
2328 debug_atomic_inc((atomic_t *)&class->ops);
2329 if (very_verbose(class)) {
2330 printk("\nacquire class [%p] %s", class->key, class->name);
2331 if (class->name_version > 1)
2332 printk("#%d", class->name_version);
2338 * Add the lock to the list of currently held locks.
2339 * (we dont increase the depth just yet, up until the
2340 * dependency checks are done)
2342 depth = curr->lockdep_depth;
2343 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2346 hlock = curr->held_locks + depth;
2348 hlock->class = class;
2349 hlock->acquire_ip = ip;
2350 hlock->instance = lock;
2351 hlock->trylock = trylock;
2353 hlock->check = check;
2354 hlock->hardirqs_off = hardirqs_off;
2355 #ifdef CONFIG_LOCK_STAT
2356 hlock->waittime_stamp = 0;
2357 hlock->holdtime_stamp = sched_clock();
2360 if (check == 2 && !mark_irqflags(curr, hlock))
2363 /* mark it as used: */
2364 if (!mark_lock(curr, hlock, LOCK_USED))
2368 * Calculate the chain hash: it's the combined has of all the
2369 * lock keys along the dependency chain. We save the hash value
2370 * at every step so that we can get the current hash easily
2371 * after unlock. The chain hash is then used to cache dependency
2374 * The 'key ID' is what is the most compact key value to drive
2375 * the hash, not class->key.
2377 id = class - lock_classes;
2378 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2381 chain_key = curr->curr_chain_key;
2383 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2388 hlock->prev_chain_key = chain_key;
2389 if (separate_irq_context(curr, hlock)) {
2393 chain_key = iterate_chain_key(chain_key, id);
2394 curr->curr_chain_key = chain_key;
2396 if (!validate_chain(curr, lock, hlock, chain_head))
2399 curr->lockdep_depth++;
2400 check_chain_key(curr);
2401 #ifdef CONFIG_DEBUG_LOCKDEP
2402 if (unlikely(!debug_locks))
2405 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2407 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2408 printk("turning off the locking correctness validator.\n");
2412 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2413 max_lockdep_depth = curr->lockdep_depth;
2419 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2422 if (!debug_locks_off())
2424 if (debug_locks_silent)
2427 printk("\n=====================================\n");
2428 printk( "[ BUG: bad unlock balance detected! ]\n");
2429 printk( "-------------------------------------\n");
2430 printk("%s/%d is trying to release lock (",
2431 curr->comm, curr->pid);
2432 print_lockdep_cache(lock);
2435 printk("but there are no more locks to release!\n");
2436 printk("\nother info that might help us debug this:\n");
2437 lockdep_print_held_locks(curr);
2439 printk("\nstack backtrace:\n");
2446 * Common debugging checks for both nested and non-nested unlock:
2448 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2451 if (unlikely(!debug_locks))
2453 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2456 if (curr->lockdep_depth <= 0)
2457 return print_unlock_inbalance_bug(curr, lock, ip);
2463 * Remove the lock to the list of currently held locks in a
2464 * potentially non-nested (out of order) manner. This is a
2465 * relatively rare operation, as all the unlock APIs default
2466 * to nested mode (which uses lock_release()):
2469 lock_release_non_nested(struct task_struct *curr,
2470 struct lockdep_map *lock, unsigned long ip)
2472 struct held_lock *hlock, *prev_hlock;
2477 * Check whether the lock exists in the current stack
2480 depth = curr->lockdep_depth;
2481 if (DEBUG_LOCKS_WARN_ON(!depth))
2485 for (i = depth-1; i >= 0; i--) {
2486 hlock = curr->held_locks + i;
2488 * We must not cross into another context:
2490 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2492 if (hlock->instance == lock)
2496 return print_unlock_inbalance_bug(curr, lock, ip);
2499 lock_release_holdtime(hlock);
2502 * We have the right lock to unlock, 'hlock' points to it.
2503 * Now we remove it from the stack, and add back the other
2504 * entries (if any), recalculating the hash along the way:
2506 curr->lockdep_depth = i;
2507 curr->curr_chain_key = hlock->prev_chain_key;
2509 for (i++; i < depth; i++) {
2510 hlock = curr->held_locks + i;
2511 if (!__lock_acquire(hlock->instance,
2512 hlock->class->subclass, hlock->trylock,
2513 hlock->read, hlock->check, hlock->hardirqs_off,
2518 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2524 * Remove the lock to the list of currently held locks - this gets
2525 * called on mutex_unlock()/spin_unlock*() (or on a failed
2526 * mutex_lock_interruptible()). This is done for unlocks that nest
2527 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2529 static int lock_release_nested(struct task_struct *curr,
2530 struct lockdep_map *lock, unsigned long ip)
2532 struct held_lock *hlock;
2536 * Pop off the top of the lock stack:
2538 depth = curr->lockdep_depth - 1;
2539 hlock = curr->held_locks + depth;
2542 * Is the unlock non-nested:
2544 if (hlock->instance != lock)
2545 return lock_release_non_nested(curr, lock, ip);
2546 curr->lockdep_depth--;
2548 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2551 curr->curr_chain_key = hlock->prev_chain_key;
2553 lock_release_holdtime(hlock);
2555 #ifdef CONFIG_DEBUG_LOCKDEP
2556 hlock->prev_chain_key = 0;
2557 hlock->class = NULL;
2558 hlock->acquire_ip = 0;
2559 hlock->irq_context = 0;
2565 * Remove the lock to the list of currently held locks - this gets
2566 * called on mutex_unlock()/spin_unlock*() (or on a failed
2567 * mutex_lock_interruptible()). This is done for unlocks that nest
2568 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2571 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2573 struct task_struct *curr = current;
2575 if (!check_unlock(curr, lock, ip))
2579 if (!lock_release_nested(curr, lock, ip))
2582 if (!lock_release_non_nested(curr, lock, ip))
2586 check_chain_key(curr);
2590 * Check whether we follow the irq-flags state precisely:
2592 static void check_flags(unsigned long flags)
2594 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2598 if (irqs_disabled_flags(flags))
2599 DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled);
2601 DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled);
2604 * We dont accurately track softirq state in e.g.
2605 * hardirq contexts (such as on 4KSTACKS), so only
2606 * check if not in hardirq contexts:
2608 if (!hardirq_count()) {
2609 if (softirq_count())
2610 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2612 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2616 print_irqtrace_events(current);
2621 * We are not always called with irqs disabled - do that here,
2622 * and also avoid lockdep recursion:
2624 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2625 int trylock, int read, int check, unsigned long ip)
2627 unsigned long flags;
2629 if (unlikely(!lock_stat && !prove_locking))
2632 if (unlikely(current->lockdep_recursion))
2635 raw_local_irq_save(flags);
2638 current->lockdep_recursion = 1;
2639 __lock_acquire(lock, subclass, trylock, read, check,
2640 irqs_disabled_flags(flags), ip);
2641 current->lockdep_recursion = 0;
2642 raw_local_irq_restore(flags);
2645 EXPORT_SYMBOL_GPL(lock_acquire);
2647 void lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2649 unsigned long flags;
2651 if (unlikely(!lock_stat && !prove_locking))
2654 if (unlikely(current->lockdep_recursion))
2657 raw_local_irq_save(flags);
2659 current->lockdep_recursion = 1;
2660 __lock_release(lock, nested, ip);
2661 current->lockdep_recursion = 0;
2662 raw_local_irq_restore(flags);
2665 EXPORT_SYMBOL_GPL(lock_release);
2667 #ifdef CONFIG_LOCK_STAT
2669 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
2672 if (!debug_locks_off())
2674 if (debug_locks_silent)
2677 printk("\n=================================\n");
2678 printk( "[ BUG: bad contention detected! ]\n");
2679 printk( "---------------------------------\n");
2680 printk("%s/%d is trying to contend lock (",
2681 curr->comm, curr->pid);
2682 print_lockdep_cache(lock);
2685 printk("but there are no locks held!\n");
2686 printk("\nother info that might help us debug this:\n");
2687 lockdep_print_held_locks(curr);
2689 printk("\nstack backtrace:\n");
2696 __lock_contended(struct lockdep_map *lock, unsigned long ip)
2698 struct task_struct *curr = current;
2699 struct held_lock *hlock, *prev_hlock;
2700 struct lock_class_stats *stats;
2704 depth = curr->lockdep_depth;
2705 if (DEBUG_LOCKS_WARN_ON(!depth))
2709 for (i = depth-1; i >= 0; i--) {
2710 hlock = curr->held_locks + i;
2712 * We must not cross into another context:
2714 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2716 if (hlock->instance == lock)
2720 print_lock_contention_bug(curr, lock, ip);
2724 hlock->waittime_stamp = sched_clock();
2726 point = lock_contention_point(hlock->class, ip);
2728 stats = get_lock_stats(hlock->class);
2729 if (point < ARRAY_SIZE(stats->contention_point))
2730 stats->contention_point[i]++;
2731 put_lock_stats(stats);
2735 __lock_acquired(struct lockdep_map *lock)
2737 struct task_struct *curr = current;
2738 struct held_lock *hlock, *prev_hlock;
2739 struct lock_class_stats *stats;
2745 depth = curr->lockdep_depth;
2746 if (DEBUG_LOCKS_WARN_ON(!depth))
2750 for (i = depth-1; i >= 0; i--) {
2751 hlock = curr->held_locks + i;
2753 * We must not cross into another context:
2755 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2757 if (hlock->instance == lock)
2761 print_lock_contention_bug(curr, lock, _RET_IP_);
2765 if (!hlock->waittime_stamp)
2768 now = sched_clock();
2769 waittime = now - hlock->waittime_stamp;
2770 hlock->holdtime_stamp = now;
2772 stats = get_lock_stats(hlock->class);
2774 lock_time_inc(&stats->read_waittime, waittime);
2776 lock_time_inc(&stats->write_waittime, waittime);
2777 put_lock_stats(stats);
2780 void lock_contended(struct lockdep_map *lock, unsigned long ip)
2782 unsigned long flags;
2784 if (unlikely(!lock_stat))
2787 if (unlikely(current->lockdep_recursion))
2790 raw_local_irq_save(flags);
2792 current->lockdep_recursion = 1;
2793 __lock_contended(lock, ip);
2794 current->lockdep_recursion = 0;
2795 raw_local_irq_restore(flags);
2797 EXPORT_SYMBOL_GPL(lock_contended);
2799 void lock_acquired(struct lockdep_map *lock)
2801 unsigned long flags;
2803 if (unlikely(!lock_stat))
2806 if (unlikely(current->lockdep_recursion))
2809 raw_local_irq_save(flags);
2811 current->lockdep_recursion = 1;
2812 __lock_acquired(lock);
2813 current->lockdep_recursion = 0;
2814 raw_local_irq_restore(flags);
2816 EXPORT_SYMBOL_GPL(lock_acquired);
2820 * Used by the testsuite, sanitize the validator state
2821 * after a simulated failure:
2824 void lockdep_reset(void)
2826 unsigned long flags;
2829 raw_local_irq_save(flags);
2830 current->curr_chain_key = 0;
2831 current->lockdep_depth = 0;
2832 current->lockdep_recursion = 0;
2833 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
2834 nr_hardirq_chains = 0;
2835 nr_softirq_chains = 0;
2836 nr_process_chains = 0;
2838 for (i = 0; i < CHAINHASH_SIZE; i++)
2839 INIT_LIST_HEAD(chainhash_table + i);
2840 raw_local_irq_restore(flags);
2843 static void zap_class(struct lock_class *class)
2848 * Remove all dependencies this lock is
2851 for (i = 0; i < nr_list_entries; i++) {
2852 if (list_entries[i].class == class)
2853 list_del_rcu(&list_entries[i].entry);
2856 * Unhash the class and remove it from the all_lock_classes list:
2858 list_del_rcu(&class->hash_entry);
2859 list_del_rcu(&class->lock_entry);
2863 static inline int within(void *addr, void *start, unsigned long size)
2865 return addr >= start && addr < start + size;
2868 void lockdep_free_key_range(void *start, unsigned long size)
2870 struct lock_class *class, *next;
2871 struct list_head *head;
2872 unsigned long flags;
2875 raw_local_irq_save(flags);
2879 * Unhash all classes that were created by this module:
2881 for (i = 0; i < CLASSHASH_SIZE; i++) {
2882 head = classhash_table + i;
2883 if (list_empty(head))
2885 list_for_each_entry_safe(class, next, head, hash_entry)
2886 if (within(class->key, start, size))
2891 raw_local_irq_restore(flags);
2894 void lockdep_reset_lock(struct lockdep_map *lock)
2896 struct lock_class *class, *next;
2897 struct list_head *head;
2898 unsigned long flags;
2901 raw_local_irq_save(flags);
2904 * Remove all classes this lock might have:
2906 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
2908 * If the class exists we look it up and zap it:
2910 class = look_up_lock_class(lock, j);
2915 * Debug check: in the end all mapped classes should
2919 for (i = 0; i < CLASSHASH_SIZE; i++) {
2920 head = classhash_table + i;
2921 if (list_empty(head))
2923 list_for_each_entry_safe(class, next, head, hash_entry) {
2924 if (unlikely(class == lock->class_cache)) {
2925 if (debug_locks_off_graph_unlock())
2934 raw_local_irq_restore(flags);
2937 void lockdep_init(void)
2942 * Some architectures have their own start_kernel()
2943 * code which calls lockdep_init(), while we also
2944 * call lockdep_init() from the start_kernel() itself,
2945 * and we want to initialize the hashes only once:
2947 if (lockdep_initialized)
2950 for (i = 0; i < CLASSHASH_SIZE; i++)
2951 INIT_LIST_HEAD(classhash_table + i);
2953 for (i = 0; i < CHAINHASH_SIZE; i++)
2954 INIT_LIST_HEAD(chainhash_table + i);
2956 lockdep_initialized = 1;
2959 void __init lockdep_info(void)
2961 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
2963 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
2964 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
2965 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
2966 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
2967 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
2968 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
2969 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
2971 printk(" memory used by lock dependency info: %lu kB\n",
2972 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
2973 sizeof(struct list_head) * CLASSHASH_SIZE +
2974 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
2975 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
2976 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
2978 printk(" per task-struct memory footprint: %lu bytes\n",
2979 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
2981 #ifdef CONFIG_DEBUG_LOCKDEP
2982 if (lockdep_init_error)
2983 printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n");
2987 static inline int in_range(const void *start, const void *addr, const void *end)
2989 return addr >= start && addr <= end;
2993 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
2994 const void *mem_to, struct held_lock *hlock)
2996 if (!debug_locks_off())
2998 if (debug_locks_silent)
3001 printk("\n=========================\n");
3002 printk( "[ BUG: held lock freed! ]\n");
3003 printk( "-------------------------\n");
3004 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3005 curr->comm, curr->pid, mem_from, mem_to-1);
3007 lockdep_print_held_locks(curr);
3009 printk("\nstack backtrace:\n");
3014 * Called when kernel memory is freed (or unmapped), or if a lock
3015 * is destroyed or reinitialized - this code checks whether there is
3016 * any held lock in the memory range of <from> to <to>:
3018 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3020 const void *mem_to = mem_from + mem_len, *lock_from, *lock_to;
3021 struct task_struct *curr = current;
3022 struct held_lock *hlock;
3023 unsigned long flags;
3026 if (unlikely(!debug_locks))
3029 local_irq_save(flags);
3030 for (i = 0; i < curr->lockdep_depth; i++) {
3031 hlock = curr->held_locks + i;
3033 lock_from = (void *)hlock->instance;
3034 lock_to = (void *)(hlock->instance + 1);
3036 if (!in_range(mem_from, lock_from, mem_to) &&
3037 !in_range(mem_from, lock_to, mem_to))
3040 print_freed_lock_bug(curr, mem_from, mem_to, hlock);
3043 local_irq_restore(flags);
3045 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3047 static void print_held_locks_bug(struct task_struct *curr)
3049 if (!debug_locks_off())
3051 if (debug_locks_silent)
3054 printk("\n=====================================\n");
3055 printk( "[ BUG: lock held at task exit time! ]\n");
3056 printk( "-------------------------------------\n");
3057 printk("%s/%d is exiting with locks still held!\n",
3058 curr->comm, curr->pid);
3059 lockdep_print_held_locks(curr);
3061 printk("\nstack backtrace:\n");
3065 void debug_check_no_locks_held(struct task_struct *task)
3067 if (unlikely(task->lockdep_depth > 0))
3068 print_held_locks_bug(task);
3071 void debug_show_all_locks(void)
3073 struct task_struct *g, *p;
3077 if (unlikely(!debug_locks)) {
3078 printk("INFO: lockdep is turned off.\n");
3081 printk("\nShowing all locks held in the system:\n");
3084 * Here we try to get the tasklist_lock as hard as possible,
3085 * if not successful after 2 seconds we ignore it (but keep
3086 * trying). This is to enable a debug printout even if a
3087 * tasklist_lock-holding task deadlocks or crashes.
3090 if (!read_trylock(&tasklist_lock)) {
3092 printk("hm, tasklist_lock locked, retrying... ");
3095 printk(" #%d", 10-count);
3099 printk(" ignoring it.\n");
3103 printk(" locked it.\n");
3105 do_each_thread(g, p) {
3106 if (p->lockdep_depth)
3107 lockdep_print_held_locks(p);
3109 if (read_trylock(&tasklist_lock))
3111 } while_each_thread(g, p);
3114 printk("=============================================\n\n");
3117 read_unlock(&tasklist_lock);
3120 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3122 void debug_show_held_locks(struct task_struct *task)
3124 if (unlikely(!debug_locks)) {
3125 printk("INFO: lockdep is turned off.\n");
3128 lockdep_print_held_locks(task);
3131 EXPORT_SYMBOL_GPL(debug_show_held_locks);