4 * Runtime locking correctness validator
6 * Started by Ingo Molnar:
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
47 #include <linux/kmemcheck.h>
49 #include <asm/sections.h>
51 #include "lockdep_internals.h"
53 #define CREATE_TRACE_POINTS
54 #include <trace/events/lock.h>
56 #ifdef CONFIG_PROVE_LOCKING
57 int prove_locking = 1;
58 module_param(prove_locking, int, 0644);
60 #define prove_locking 0
63 #ifdef CONFIG_LOCK_STAT
65 module_param(lock_stat, int, 0644);
71 * lockdep_lock: protects the lockdep graph, the hashes and the
72 * class/list/hash allocators.
74 * This is one of the rare exceptions where it's justified
75 * to use a raw spinlock - we really dont want the spinlock
76 * code to recurse back into the lockdep code...
78 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
80 static int graph_lock(void)
82 arch_spin_lock(&lockdep_lock);
84 * Make sure that if another CPU detected a bug while
85 * walking the graph we dont change it (while the other
86 * CPU is busy printing out stuff with the graph lock
90 arch_spin_unlock(&lockdep_lock);
93 /* prevent any recursions within lockdep from causing deadlocks */
94 current->lockdep_recursion++;
98 static inline int graph_unlock(void)
100 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
102 * The lockdep graph lock isn't locked while we expect it to
103 * be, we're confused now, bye!
105 return DEBUG_LOCKS_WARN_ON(1);
108 current->lockdep_recursion--;
109 arch_spin_unlock(&lockdep_lock);
114 * Turn lock debugging off and return with 0 if it was off already,
115 * and also release the graph lock:
117 static inline int debug_locks_off_graph_unlock(void)
119 int ret = debug_locks_off();
121 arch_spin_unlock(&lockdep_lock);
126 static int lockdep_initialized;
128 unsigned long nr_list_entries;
129 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
132 * All data structures here are protected by the global debug_lock.
134 * Mutex key structs only get allocated, once during bootup, and never
135 * get freed - this significantly simplifies the debugging code.
137 unsigned long nr_lock_classes;
138 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
140 static inline struct lock_class *hlock_class(struct held_lock *hlock)
142 if (!hlock->class_idx) {
144 * Someone passed in garbage, we give up.
146 DEBUG_LOCKS_WARN_ON(1);
149 return lock_classes + hlock->class_idx - 1;
152 #ifdef CONFIG_LOCK_STAT
153 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
156 static inline u64 lockstat_clock(void)
158 return local_clock();
161 static int lock_point(unsigned long points[], unsigned long ip)
165 for (i = 0; i < LOCKSTAT_POINTS; i++) {
166 if (points[i] == 0) {
177 static void lock_time_inc(struct lock_time *lt, u64 time)
182 if (time < lt->min || !lt->nr)
189 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
194 if (src->max > dst->max)
197 if (src->min < dst->min || !dst->nr)
200 dst->total += src->total;
204 struct lock_class_stats lock_stats(struct lock_class *class)
206 struct lock_class_stats stats;
209 memset(&stats, 0, sizeof(struct lock_class_stats));
210 for_each_possible_cpu(cpu) {
211 struct lock_class_stats *pcs =
212 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
214 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
215 stats.contention_point[i] += pcs->contention_point[i];
217 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
218 stats.contending_point[i] += pcs->contending_point[i];
220 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
221 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
223 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
224 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
226 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
227 stats.bounces[i] += pcs->bounces[i];
233 void clear_lock_stats(struct lock_class *class)
237 for_each_possible_cpu(cpu) {
238 struct lock_class_stats *cpu_stats =
239 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
241 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
243 memset(class->contention_point, 0, sizeof(class->contention_point));
244 memset(class->contending_point, 0, sizeof(class->contending_point));
247 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
249 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
252 static void put_lock_stats(struct lock_class_stats *stats)
254 put_cpu_var(cpu_lock_stats);
257 static void lock_release_holdtime(struct held_lock *hlock)
259 struct lock_class_stats *stats;
265 holdtime = lockstat_clock() - hlock->holdtime_stamp;
267 stats = get_lock_stats(hlock_class(hlock));
269 lock_time_inc(&stats->read_holdtime, holdtime);
271 lock_time_inc(&stats->write_holdtime, holdtime);
272 put_lock_stats(stats);
275 static inline void lock_release_holdtime(struct held_lock *hlock)
281 * We keep a global list of all lock classes. The list only grows,
282 * never shrinks. The list is only accessed with the lockdep
283 * spinlock lock held.
285 LIST_HEAD(all_lock_classes);
288 * The lockdep classes are in a hash-table as well, for fast lookup:
290 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
291 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
292 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
293 #define classhashentry(key) (classhash_table + __classhashfn((key)))
295 static struct list_head classhash_table[CLASSHASH_SIZE];
298 * We put the lock dependency chains into a hash-table as well, to cache
301 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
302 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
303 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
304 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
306 static struct list_head chainhash_table[CHAINHASH_SIZE];
309 * The hash key of the lock dependency chains is a hash itself too:
310 * it's a hash of all locks taken up to that lock, including that lock.
311 * It's a 64-bit hash, because it's important for the keys to be
314 #define iterate_chain_key(key1, key2) \
315 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
316 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
319 void lockdep_off(void)
321 current->lockdep_recursion++;
323 EXPORT_SYMBOL(lockdep_off);
325 void lockdep_on(void)
327 current->lockdep_recursion--;
329 EXPORT_SYMBOL(lockdep_on);
332 * Debugging switches:
336 #define VERY_VERBOSE 0
339 # define HARDIRQ_VERBOSE 1
340 # define SOFTIRQ_VERBOSE 1
341 # define RECLAIM_VERBOSE 1
343 # define HARDIRQ_VERBOSE 0
344 # define SOFTIRQ_VERBOSE 0
345 # define RECLAIM_VERBOSE 0
348 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
350 * Quick filtering for interesting events:
352 static int class_filter(struct lock_class *class)
356 if (class->name_version == 1 &&
357 !strcmp(class->name, "lockname"))
359 if (class->name_version == 1 &&
360 !strcmp(class->name, "&struct->lockfield"))
363 /* Filter everything else. 1 would be to allow everything else */
368 static int verbose(struct lock_class *class)
371 return class_filter(class);
377 * Stack-trace: tightly packed array of stack backtrace
378 * addresses. Protected by the graph_lock.
380 unsigned long nr_stack_trace_entries;
381 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
383 static int save_trace(struct stack_trace *trace)
385 trace->nr_entries = 0;
386 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
387 trace->entries = stack_trace + nr_stack_trace_entries;
391 save_stack_trace(trace);
394 * Some daft arches put -1 at the end to indicate its a full trace.
396 * <rant> this is buggy anyway, since it takes a whole extra entry so a
397 * complete trace that maxes out the entries provided will be reported
398 * as incomplete, friggin useless </rant>
400 if (trace->nr_entries != 0 &&
401 trace->entries[trace->nr_entries-1] == ULONG_MAX)
404 trace->max_entries = trace->nr_entries;
406 nr_stack_trace_entries += trace->nr_entries;
408 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
409 if (!debug_locks_off_graph_unlock())
412 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
413 printk("turning off the locking correctness validator.\n");
422 unsigned int nr_hardirq_chains;
423 unsigned int nr_softirq_chains;
424 unsigned int nr_process_chains;
425 unsigned int max_lockdep_depth;
427 #ifdef CONFIG_DEBUG_LOCKDEP
429 * We cannot printk in early bootup code. Not even early_printk()
430 * might work. So we mark any initialization errors and printk
431 * about it later on, in lockdep_info().
433 static int lockdep_init_error;
434 static const char *lock_init_error;
435 static unsigned long lockdep_init_trace_data[20];
436 static struct stack_trace lockdep_init_trace = {
437 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
438 .entries = lockdep_init_trace_data,
442 * Various lockdep statistics:
444 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
451 #define __USAGE(__STATE) \
452 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
453 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
454 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
455 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
457 static const char *usage_str[] =
459 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
460 #include "lockdep_states.h"
462 [LOCK_USED] = "INITIAL USE",
465 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
467 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
470 static inline unsigned long lock_flag(enum lock_usage_bit bit)
475 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
479 if (class->usage_mask & lock_flag(bit + 2))
481 if (class->usage_mask & lock_flag(bit)) {
483 if (class->usage_mask & lock_flag(bit + 2))
490 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
494 #define LOCKDEP_STATE(__STATE) \
495 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
496 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
497 #include "lockdep_states.h"
503 static int __print_lock_name(struct lock_class *class)
505 char str[KSYM_NAME_LEN];
510 name = __get_key_name(class->key, str);
512 return printk("%s", name);
515 static void print_lock_name(struct lock_class *class)
517 char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
520 get_usage_chars(class, usage);
524 name = __get_key_name(class->key, str);
525 printk(" (%s", name);
527 printk(" (%s", name);
528 if (class->name_version > 1)
529 printk("#%d", class->name_version);
531 printk("/%d", class->subclass);
533 printk("){%s}", usage);
536 static void print_lockdep_cache(struct lockdep_map *lock)
539 char str[KSYM_NAME_LEN];
543 name = __get_key_name(lock->key->subkeys, str);
548 static void print_lock(struct held_lock *hlock)
550 print_lock_name(hlock_class(hlock));
552 print_ip_sym(hlock->acquire_ip);
555 static void lockdep_print_held_locks(struct task_struct *curr)
557 int i, depth = curr->lockdep_depth;
560 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
563 printk("%d lock%s held by %s/%d:\n",
564 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
566 for (i = 0; i < depth; i++) {
568 print_lock(curr->held_locks + i);
572 static void print_kernel_ident(void)
574 printk("%s %.*s %s\n", init_utsname()->release,
575 (int)strcspn(init_utsname()->version, " "),
576 init_utsname()->version,
580 static int very_verbose(struct lock_class *class)
583 return class_filter(class);
589 * Is this the address of a static object:
591 static int static_obj(void *obj)
593 unsigned long start = (unsigned long) &_stext,
594 end = (unsigned long) &_end,
595 addr = (unsigned long) obj;
600 if ((addr >= start) && (addr < end))
603 if (arch_is_kernel_data(addr))
607 * in-kernel percpu var?
609 if (is_kernel_percpu_address(addr))
613 * module static or percpu var?
615 return is_module_address(addr) || is_module_percpu_address(addr);
619 * To make lock name printouts unique, we calculate a unique
620 * class->name_version generation counter:
622 static int count_matching_names(struct lock_class *new_class)
624 struct lock_class *class;
627 if (!new_class->name)
630 list_for_each_entry(class, &all_lock_classes, lock_entry) {
631 if (new_class->key - new_class->subclass == class->key)
632 return class->name_version;
633 if (class->name && !strcmp(class->name, new_class->name))
634 count = max(count, class->name_version);
641 * Register a lock's class in the hash-table, if the class is not present
642 * yet. Otherwise we look it up. We cache the result in the lock object
643 * itself, so actual lookup of the hash should be once per lock object.
645 static inline struct lock_class *
646 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
648 struct lockdep_subclass_key *key;
649 struct list_head *hash_head;
650 struct lock_class *class;
652 #ifdef CONFIG_DEBUG_LOCKDEP
654 * If the architecture calls into lockdep before initializing
655 * the hashes then we'll warn about it later. (we cannot printk
658 if (unlikely(!lockdep_initialized)) {
660 lockdep_init_error = 1;
661 lock_init_error = lock->name;
662 save_stack_trace(&lockdep_init_trace);
666 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
669 "BUG: looking up invalid subclass: %u\n", subclass);
671 "turning off the locking correctness validator.\n");
677 * Static locks do not have their class-keys yet - for them the key
678 * is the lock object itself:
680 if (unlikely(!lock->key))
681 lock->key = (void *)lock;
684 * NOTE: the class-key must be unique. For dynamic locks, a static
685 * lock_class_key variable is passed in through the mutex_init()
686 * (or spin_lock_init()) call - which acts as the key. For static
687 * locks we use the lock object itself as the key.
689 BUILD_BUG_ON(sizeof(struct lock_class_key) >
690 sizeof(struct lockdep_map));
692 key = lock->key->subkeys + subclass;
694 hash_head = classhashentry(key);
697 * We can walk the hash lockfree, because the hash only
698 * grows, and we are careful when adding entries to the end:
700 list_for_each_entry(class, hash_head, hash_entry) {
701 if (class->key == key) {
703 * Huh! same key, different name? Did someone trample
704 * on some memory? We're most confused.
706 WARN_ON_ONCE(class->name != lock->name);
715 * Register a lock's class in the hash-table, if the class is not present
716 * yet. Otherwise we look it up. We cache the result in the lock object
717 * itself, so actual lookup of the hash should be once per lock object.
719 static inline struct lock_class *
720 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
722 struct lockdep_subclass_key *key;
723 struct list_head *hash_head;
724 struct lock_class *class;
727 class = look_up_lock_class(lock, subclass);
729 goto out_set_class_cache;
732 * Debug-check: all keys must be persistent!
734 if (!static_obj(lock->key)) {
736 printk("INFO: trying to register non-static key.\n");
737 printk("the code is fine but needs lockdep annotation.\n");
738 printk("turning off the locking correctness validator.\n");
744 key = lock->key->subkeys + subclass;
745 hash_head = classhashentry(key);
747 raw_local_irq_save(flags);
749 raw_local_irq_restore(flags);
753 * We have to do the hash-walk again, to avoid races
756 list_for_each_entry(class, hash_head, hash_entry)
757 if (class->key == key)
760 * Allocate a new key from the static array, and add it to
763 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
764 if (!debug_locks_off_graph_unlock()) {
765 raw_local_irq_restore(flags);
768 raw_local_irq_restore(flags);
770 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
771 printk("turning off the locking correctness validator.\n");
775 class = lock_classes + nr_lock_classes++;
776 debug_atomic_inc(nr_unused_locks);
778 class->name = lock->name;
779 class->subclass = subclass;
780 INIT_LIST_HEAD(&class->lock_entry);
781 INIT_LIST_HEAD(&class->locks_before);
782 INIT_LIST_HEAD(&class->locks_after);
783 class->name_version = count_matching_names(class);
785 * We use RCU's safe list-add method to make
786 * parallel walking of the hash-list safe:
788 list_add_tail_rcu(&class->hash_entry, hash_head);
790 * Add it to the global list of classes:
792 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
794 if (verbose(class)) {
796 raw_local_irq_restore(flags);
798 printk("\nnew class %p: %s", class->key, class->name);
799 if (class->name_version > 1)
800 printk("#%d", class->name_version);
804 raw_local_irq_save(flags);
806 raw_local_irq_restore(flags);
812 raw_local_irq_restore(flags);
815 if (!subclass || force)
816 lock->class_cache[0] = class;
817 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
818 lock->class_cache[subclass] = class;
821 * Hash collision, did we smoke some? We found a class with a matching
822 * hash but the subclass -- which is hashed in -- didn't match.
824 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
830 #ifdef CONFIG_PROVE_LOCKING
832 * Allocate a lockdep entry. (assumes the graph_lock held, returns
833 * with NULL on failure)
835 static struct lock_list *alloc_list_entry(void)
837 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
838 if (!debug_locks_off_graph_unlock())
841 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
842 printk("turning off the locking correctness validator.\n");
846 return list_entries + nr_list_entries++;
850 * Add a new dependency to the head of the list:
852 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
853 struct list_head *head, unsigned long ip,
854 int distance, struct stack_trace *trace)
856 struct lock_list *entry;
858 * Lock not present yet - get a new dependency struct and
859 * add it to the list:
861 entry = alloc_list_entry();
866 entry->distance = distance;
867 entry->trace = *trace;
869 * Since we never remove from the dependency list, the list can
870 * be walked lockless by other CPUs, it's only allocation
871 * that must be protected by the spinlock. But this also means
872 * we must make new entries visible only once writes to the
873 * entry become visible - hence the RCU op:
875 list_add_tail_rcu(&entry->entry, head);
881 * For good efficiency of modular, we use power of 2
883 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
884 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
887 * The circular_queue and helpers is used to implement the
888 * breadth-first search(BFS)algorithem, by which we can build
889 * the shortest path from the next lock to be acquired to the
890 * previous held lock if there is a circular between them.
892 struct circular_queue {
893 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
894 unsigned int front, rear;
897 static struct circular_queue lock_cq;
899 unsigned int max_bfs_queue_depth;
901 static unsigned int lockdep_dependency_gen_id;
903 static inline void __cq_init(struct circular_queue *cq)
905 cq->front = cq->rear = 0;
906 lockdep_dependency_gen_id++;
909 static inline int __cq_empty(struct circular_queue *cq)
911 return (cq->front == cq->rear);
914 static inline int __cq_full(struct circular_queue *cq)
916 return ((cq->rear + 1) & CQ_MASK) == cq->front;
919 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
924 cq->element[cq->rear] = elem;
925 cq->rear = (cq->rear + 1) & CQ_MASK;
929 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
934 *elem = cq->element[cq->front];
935 cq->front = (cq->front + 1) & CQ_MASK;
939 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
941 return (cq->rear - cq->front) & CQ_MASK;
944 static inline void mark_lock_accessed(struct lock_list *lock,
945 struct lock_list *parent)
949 nr = lock - list_entries;
950 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
951 lock->parent = parent;
952 lock->class->dep_gen_id = lockdep_dependency_gen_id;
955 static inline unsigned long lock_accessed(struct lock_list *lock)
959 nr = lock - list_entries;
960 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
961 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
964 static inline struct lock_list *get_lock_parent(struct lock_list *child)
966 return child->parent;
969 static inline int get_lock_depth(struct lock_list *child)
972 struct lock_list *parent;
974 while ((parent = get_lock_parent(child))) {
981 static int __bfs(struct lock_list *source_entry,
983 int (*match)(struct lock_list *entry, void *data),
984 struct lock_list **target_entry,
987 struct lock_list *entry;
988 struct list_head *head;
989 struct circular_queue *cq = &lock_cq;
992 if (match(source_entry, data)) {
993 *target_entry = source_entry;
999 head = &source_entry->class->locks_after;
1001 head = &source_entry->class->locks_before;
1003 if (list_empty(head))
1007 __cq_enqueue(cq, (unsigned long)source_entry);
1009 while (!__cq_empty(cq)) {
1010 struct lock_list *lock;
1012 __cq_dequeue(cq, (unsigned long *)&lock);
1020 head = &lock->class->locks_after;
1022 head = &lock->class->locks_before;
1024 list_for_each_entry(entry, head, entry) {
1025 if (!lock_accessed(entry)) {
1026 unsigned int cq_depth;
1027 mark_lock_accessed(entry, lock);
1028 if (match(entry, data)) {
1029 *target_entry = entry;
1034 if (__cq_enqueue(cq, (unsigned long)entry)) {
1038 cq_depth = __cq_get_elem_count(cq);
1039 if (max_bfs_queue_depth < cq_depth)
1040 max_bfs_queue_depth = cq_depth;
1048 static inline int __bfs_forwards(struct lock_list *src_entry,
1050 int (*match)(struct lock_list *entry, void *data),
1051 struct lock_list **target_entry)
1053 return __bfs(src_entry, data, match, target_entry, 1);
1057 static inline int __bfs_backwards(struct lock_list *src_entry,
1059 int (*match)(struct lock_list *entry, void *data),
1060 struct lock_list **target_entry)
1062 return __bfs(src_entry, data, match, target_entry, 0);
1067 * Recursive, forwards-direction lock-dependency checking, used for
1068 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1073 * Print a dependency chain entry (this is only done when a deadlock
1074 * has been detected):
1077 print_circular_bug_entry(struct lock_list *target, int depth)
1079 if (debug_locks_silent)
1081 printk("\n-> #%u", depth);
1082 print_lock_name(target->class);
1084 print_stack_trace(&target->trace, 6);
1090 print_circular_lock_scenario(struct held_lock *src,
1091 struct held_lock *tgt,
1092 struct lock_list *prt)
1094 struct lock_class *source = hlock_class(src);
1095 struct lock_class *target = hlock_class(tgt);
1096 struct lock_class *parent = prt->class;
1099 * A direct locking problem where unsafe_class lock is taken
1100 * directly by safe_class lock, then all we need to show
1101 * is the deadlock scenario, as it is obvious that the
1102 * unsafe lock is taken under the safe lock.
1104 * But if there is a chain instead, where the safe lock takes
1105 * an intermediate lock (middle_class) where this lock is
1106 * not the same as the safe lock, then the lock chain is
1107 * used to describe the problem. Otherwise we would need
1108 * to show a different CPU case for each link in the chain
1109 * from the safe_class lock to the unsafe_class lock.
1111 if (parent != source) {
1112 printk("Chain exists of:\n ");
1113 __print_lock_name(source);
1115 __print_lock_name(parent);
1117 __print_lock_name(target);
1121 printk(" Possible unsafe locking scenario:\n\n");
1122 printk(" CPU0 CPU1\n");
1123 printk(" ---- ----\n");
1125 __print_lock_name(target);
1128 __print_lock_name(parent);
1131 __print_lock_name(target);
1134 __print_lock_name(source);
1136 printk("\n *** DEADLOCK ***\n\n");
1140 * When a circular dependency is detected, print the
1144 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1145 struct held_lock *check_src,
1146 struct held_lock *check_tgt)
1148 struct task_struct *curr = current;
1150 if (debug_locks_silent)
1154 printk("======================================================\n");
1155 printk("[ INFO: possible circular locking dependency detected ]\n");
1156 print_kernel_ident();
1157 printk("-------------------------------------------------------\n");
1158 printk("%s/%d is trying to acquire lock:\n",
1159 curr->comm, task_pid_nr(curr));
1160 print_lock(check_src);
1161 printk("\nbut task is already holding lock:\n");
1162 print_lock(check_tgt);
1163 printk("\nwhich lock already depends on the new lock.\n\n");
1164 printk("\nthe existing dependency chain (in reverse order) is:\n");
1166 print_circular_bug_entry(entry, depth);
1171 static inline int class_equal(struct lock_list *entry, void *data)
1173 return entry->class == data;
1176 static noinline int print_circular_bug(struct lock_list *this,
1177 struct lock_list *target,
1178 struct held_lock *check_src,
1179 struct held_lock *check_tgt)
1181 struct task_struct *curr = current;
1182 struct lock_list *parent;
1183 struct lock_list *first_parent;
1186 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1189 if (!save_trace(&this->trace))
1192 depth = get_lock_depth(target);
1194 print_circular_bug_header(target, depth, check_src, check_tgt);
1196 parent = get_lock_parent(target);
1197 first_parent = parent;
1200 print_circular_bug_entry(parent, --depth);
1201 parent = get_lock_parent(parent);
1204 printk("\nother info that might help us debug this:\n\n");
1205 print_circular_lock_scenario(check_src, check_tgt,
1208 lockdep_print_held_locks(curr);
1210 printk("\nstack backtrace:\n");
1216 static noinline int print_bfs_bug(int ret)
1218 if (!debug_locks_off_graph_unlock())
1222 * Breadth-first-search failed, graph got corrupted?
1224 WARN(1, "lockdep bfs error:%d\n", ret);
1229 static int noop_count(struct lock_list *entry, void *data)
1231 (*(unsigned long *)data)++;
1235 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1237 unsigned long count = 0;
1238 struct lock_list *uninitialized_var(target_entry);
1240 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1244 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1246 unsigned long ret, flags;
1247 struct lock_list this;
1252 local_irq_save(flags);
1253 arch_spin_lock(&lockdep_lock);
1254 ret = __lockdep_count_forward_deps(&this);
1255 arch_spin_unlock(&lockdep_lock);
1256 local_irq_restore(flags);
1261 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1263 unsigned long count = 0;
1264 struct lock_list *uninitialized_var(target_entry);
1266 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1271 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1273 unsigned long ret, flags;
1274 struct lock_list this;
1279 local_irq_save(flags);
1280 arch_spin_lock(&lockdep_lock);
1281 ret = __lockdep_count_backward_deps(&this);
1282 arch_spin_unlock(&lockdep_lock);
1283 local_irq_restore(flags);
1289 * Prove that the dependency graph starting at <entry> can not
1290 * lead to <target>. Print an error and return 0 if it does.
1293 check_noncircular(struct lock_list *root, struct lock_class *target,
1294 struct lock_list **target_entry)
1298 debug_atomic_inc(nr_cyclic_checks);
1300 result = __bfs_forwards(root, target, class_equal, target_entry);
1305 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1307 * Forwards and backwards subgraph searching, for the purposes of
1308 * proving that two subgraphs can be connected by a new dependency
1309 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1312 static inline int usage_match(struct lock_list *entry, void *bit)
1314 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1320 * Find a node in the forwards-direction dependency sub-graph starting
1321 * at @root->class that matches @bit.
1323 * Return 0 if such a node exists in the subgraph, and put that node
1324 * into *@target_entry.
1326 * Return 1 otherwise and keep *@target_entry unchanged.
1327 * Return <0 on error.
1330 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1331 struct lock_list **target_entry)
1335 debug_atomic_inc(nr_find_usage_forwards_checks);
1337 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1343 * Find a node in the backwards-direction dependency sub-graph starting
1344 * at @root->class that matches @bit.
1346 * Return 0 if such a node exists in the subgraph, and put that node
1347 * into *@target_entry.
1349 * Return 1 otherwise and keep *@target_entry unchanged.
1350 * Return <0 on error.
1353 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1354 struct lock_list **target_entry)
1358 debug_atomic_inc(nr_find_usage_backwards_checks);
1360 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1365 static void print_lock_class_header(struct lock_class *class, int depth)
1369 printk("%*s->", depth, "");
1370 print_lock_name(class);
1371 printk(" ops: %lu", class->ops);
1374 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1375 if (class->usage_mask & (1 << bit)) {
1378 len += printk("%*s %s", depth, "", usage_str[bit]);
1379 len += printk(" at:\n");
1380 print_stack_trace(class->usage_traces + bit, len);
1383 printk("%*s }\n", depth, "");
1385 printk("%*s ... key at: ",depth,"");
1386 print_ip_sym((unsigned long)class->key);
1390 * printk the shortest lock dependencies from @start to @end in reverse order:
1393 print_shortest_lock_dependencies(struct lock_list *leaf,
1394 struct lock_list *root)
1396 struct lock_list *entry = leaf;
1399 /*compute depth from generated tree by BFS*/
1400 depth = get_lock_depth(leaf);
1403 print_lock_class_header(entry->class, depth);
1404 printk("%*s ... acquired at:\n", depth, "");
1405 print_stack_trace(&entry->trace, 2);
1408 if (depth == 0 && (entry != root)) {
1409 printk("lockdep:%s bad path found in chain graph\n", __func__);
1413 entry = get_lock_parent(entry);
1415 } while (entry && (depth >= 0));
1421 print_irq_lock_scenario(struct lock_list *safe_entry,
1422 struct lock_list *unsafe_entry,
1423 struct lock_class *prev_class,
1424 struct lock_class *next_class)
1426 struct lock_class *safe_class = safe_entry->class;
1427 struct lock_class *unsafe_class = unsafe_entry->class;
1428 struct lock_class *middle_class = prev_class;
1430 if (middle_class == safe_class)
1431 middle_class = next_class;
1434 * A direct locking problem where unsafe_class lock is taken
1435 * directly by safe_class lock, then all we need to show
1436 * is the deadlock scenario, as it is obvious that the
1437 * unsafe lock is taken under the safe lock.
1439 * But if there is a chain instead, where the safe lock takes
1440 * an intermediate lock (middle_class) where this lock is
1441 * not the same as the safe lock, then the lock chain is
1442 * used to describe the problem. Otherwise we would need
1443 * to show a different CPU case for each link in the chain
1444 * from the safe_class lock to the unsafe_class lock.
1446 if (middle_class != unsafe_class) {
1447 printk("Chain exists of:\n ");
1448 __print_lock_name(safe_class);
1450 __print_lock_name(middle_class);
1452 __print_lock_name(unsafe_class);
1456 printk(" Possible interrupt unsafe locking scenario:\n\n");
1457 printk(" CPU0 CPU1\n");
1458 printk(" ---- ----\n");
1460 __print_lock_name(unsafe_class);
1462 printk(" local_irq_disable();\n");
1464 __print_lock_name(safe_class);
1467 __print_lock_name(middle_class);
1469 printk(" <Interrupt>\n");
1471 __print_lock_name(safe_class);
1473 printk("\n *** DEADLOCK ***\n\n");
1477 print_bad_irq_dependency(struct task_struct *curr,
1478 struct lock_list *prev_root,
1479 struct lock_list *next_root,
1480 struct lock_list *backwards_entry,
1481 struct lock_list *forwards_entry,
1482 struct held_lock *prev,
1483 struct held_lock *next,
1484 enum lock_usage_bit bit1,
1485 enum lock_usage_bit bit2,
1486 const char *irqclass)
1488 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1492 printk("======================================================\n");
1493 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1494 irqclass, irqclass);
1495 print_kernel_ident();
1496 printk("------------------------------------------------------\n");
1497 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1498 curr->comm, task_pid_nr(curr),
1499 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1500 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1501 curr->hardirqs_enabled,
1502 curr->softirqs_enabled);
1505 printk("\nand this task is already holding:\n");
1507 printk("which would create a new lock dependency:\n");
1508 print_lock_name(hlock_class(prev));
1510 print_lock_name(hlock_class(next));
1513 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1515 print_lock_name(backwards_entry->class);
1516 printk("\n... which became %s-irq-safe at:\n", irqclass);
1518 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1520 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1521 print_lock_name(forwards_entry->class);
1522 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1525 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1527 printk("\nother info that might help us debug this:\n\n");
1528 print_irq_lock_scenario(backwards_entry, forwards_entry,
1529 hlock_class(prev), hlock_class(next));
1531 lockdep_print_held_locks(curr);
1533 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1534 printk(" and the holding lock:\n");
1535 if (!save_trace(&prev_root->trace))
1537 print_shortest_lock_dependencies(backwards_entry, prev_root);
1539 printk("\nthe dependencies between the lock to be acquired");
1540 printk(" and %s-irq-unsafe lock:\n", irqclass);
1541 if (!save_trace(&next_root->trace))
1543 print_shortest_lock_dependencies(forwards_entry, next_root);
1545 printk("\nstack backtrace:\n");
1552 check_usage(struct task_struct *curr, struct held_lock *prev,
1553 struct held_lock *next, enum lock_usage_bit bit_backwards,
1554 enum lock_usage_bit bit_forwards, const char *irqclass)
1557 struct lock_list this, that;
1558 struct lock_list *uninitialized_var(target_entry);
1559 struct lock_list *uninitialized_var(target_entry1);
1563 this.class = hlock_class(prev);
1564 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1566 return print_bfs_bug(ret);
1571 that.class = hlock_class(next);
1572 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1574 return print_bfs_bug(ret);
1578 return print_bad_irq_dependency(curr, &this, &that,
1579 target_entry, target_entry1,
1581 bit_backwards, bit_forwards, irqclass);
1584 static const char *state_names[] = {
1585 #define LOCKDEP_STATE(__STATE) \
1586 __stringify(__STATE),
1587 #include "lockdep_states.h"
1588 #undef LOCKDEP_STATE
1591 static const char *state_rnames[] = {
1592 #define LOCKDEP_STATE(__STATE) \
1593 __stringify(__STATE)"-READ",
1594 #include "lockdep_states.h"
1595 #undef LOCKDEP_STATE
1598 static inline const char *state_name(enum lock_usage_bit bit)
1600 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1603 static int exclusive_bit(int new_bit)
1611 * bit 0 - write/read
1612 * bit 1 - used_in/enabled
1616 int state = new_bit & ~3;
1617 int dir = new_bit & 2;
1620 * keep state, bit flip the direction and strip read.
1622 return state | (dir ^ 2);
1625 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1626 struct held_lock *next, enum lock_usage_bit bit)
1629 * Prove that the new dependency does not connect a hardirq-safe
1630 * lock with a hardirq-unsafe lock - to achieve this we search
1631 * the backwards-subgraph starting at <prev>, and the
1632 * forwards-subgraph starting at <next>:
1634 if (!check_usage(curr, prev, next, bit,
1635 exclusive_bit(bit), state_name(bit)))
1641 * Prove that the new dependency does not connect a hardirq-safe-read
1642 * lock with a hardirq-unsafe lock - to achieve this we search
1643 * the backwards-subgraph starting at <prev>, and the
1644 * forwards-subgraph starting at <next>:
1646 if (!check_usage(curr, prev, next, bit,
1647 exclusive_bit(bit), state_name(bit)))
1654 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1655 struct held_lock *next)
1657 #define LOCKDEP_STATE(__STATE) \
1658 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1660 #include "lockdep_states.h"
1661 #undef LOCKDEP_STATE
1666 static void inc_chains(void)
1668 if (current->hardirq_context)
1669 nr_hardirq_chains++;
1671 if (current->softirq_context)
1672 nr_softirq_chains++;
1674 nr_process_chains++;
1681 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1682 struct held_lock *next)
1687 static inline void inc_chains(void)
1689 nr_process_chains++;
1695 print_deadlock_scenario(struct held_lock *nxt,
1696 struct held_lock *prv)
1698 struct lock_class *next = hlock_class(nxt);
1699 struct lock_class *prev = hlock_class(prv);
1701 printk(" Possible unsafe locking scenario:\n\n");
1705 __print_lock_name(prev);
1708 __print_lock_name(next);
1710 printk("\n *** DEADLOCK ***\n\n");
1711 printk(" May be due to missing lock nesting notation\n\n");
1715 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1716 struct held_lock *next)
1718 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1722 printk("=============================================\n");
1723 printk("[ INFO: possible recursive locking detected ]\n");
1724 print_kernel_ident();
1725 printk("---------------------------------------------\n");
1726 printk("%s/%d is trying to acquire lock:\n",
1727 curr->comm, task_pid_nr(curr));
1729 printk("\nbut task is already holding lock:\n");
1732 printk("\nother info that might help us debug this:\n");
1733 print_deadlock_scenario(next, prev);
1734 lockdep_print_held_locks(curr);
1736 printk("\nstack backtrace:\n");
1743 * Check whether we are holding such a class already.
1745 * (Note that this has to be done separately, because the graph cannot
1746 * detect such classes of deadlocks.)
1748 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1751 check_deadlock(struct task_struct *curr, struct held_lock *next,
1752 struct lockdep_map *next_instance, int read)
1754 struct held_lock *prev;
1755 struct held_lock *nest = NULL;
1758 for (i = 0; i < curr->lockdep_depth; i++) {
1759 prev = curr->held_locks + i;
1761 if (prev->instance == next->nest_lock)
1764 if (hlock_class(prev) != hlock_class(next))
1768 * Allow read-after-read recursion of the same
1769 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1771 if ((read == 2) && prev->read)
1775 * We're holding the nest_lock, which serializes this lock's
1776 * nesting behaviour.
1781 return print_deadlock_bug(curr, prev, next);
1787 * There was a chain-cache miss, and we are about to add a new dependency
1788 * to a previous lock. We recursively validate the following rules:
1790 * - would the adding of the <prev> -> <next> dependency create a
1791 * circular dependency in the graph? [== circular deadlock]
1793 * - does the new prev->next dependency connect any hardirq-safe lock
1794 * (in the full backwards-subgraph starting at <prev>) with any
1795 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1796 * <next>)? [== illegal lock inversion with hardirq contexts]
1798 * - does the new prev->next dependency connect any softirq-safe lock
1799 * (in the full backwards-subgraph starting at <prev>) with any
1800 * softirq-unsafe lock (in the full forwards-subgraph starting at
1801 * <next>)? [== illegal lock inversion with softirq contexts]
1803 * any of these scenarios could lead to a deadlock.
1805 * Then if all the validations pass, we add the forwards and backwards
1809 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1810 struct held_lock *next, int distance, int trylock_loop)
1812 struct lock_list *entry;
1814 struct lock_list this;
1815 struct lock_list *uninitialized_var(target_entry);
1817 * Static variable, serialized by the graph_lock().
1819 * We use this static variable to save the stack trace in case
1820 * we call into this function multiple times due to encountering
1821 * trylocks in the held lock stack.
1823 static struct stack_trace trace;
1826 * Prove that the new <prev> -> <next> dependency would not
1827 * create a circular dependency in the graph. (We do this by
1828 * forward-recursing into the graph starting at <next>, and
1829 * checking whether we can reach <prev>.)
1831 * We are using global variables to control the recursion, to
1832 * keep the stackframe size of the recursive functions low:
1834 this.class = hlock_class(next);
1836 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1838 return print_circular_bug(&this, target_entry, next, prev);
1839 else if (unlikely(ret < 0))
1840 return print_bfs_bug(ret);
1842 if (!check_prev_add_irq(curr, prev, next))
1846 * For recursive read-locks we do all the dependency checks,
1847 * but we dont store read-triggered dependencies (only
1848 * write-triggered dependencies). This ensures that only the
1849 * write-side dependencies matter, and that if for example a
1850 * write-lock never takes any other locks, then the reads are
1851 * equivalent to a NOP.
1853 if (next->read == 2 || prev->read == 2)
1856 * Is the <prev> -> <next> dependency already present?
1858 * (this may occur even though this is a new chain: consider
1859 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1860 * chains - the second one will be new, but L1 already has
1861 * L2 added to its dependency list, due to the first chain.)
1863 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1864 if (entry->class == hlock_class(next)) {
1866 entry->distance = 1;
1871 if (!trylock_loop && !save_trace(&trace))
1875 * Ok, all validations passed, add the new lock
1876 * to the previous lock's dependency list:
1878 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1879 &hlock_class(prev)->locks_after,
1880 next->acquire_ip, distance, &trace);
1885 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1886 &hlock_class(next)->locks_before,
1887 next->acquire_ip, distance, &trace);
1892 * Debugging printouts:
1894 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1896 printk("\n new dependency: ");
1897 print_lock_name(hlock_class(prev));
1899 print_lock_name(hlock_class(next));
1902 return graph_lock();
1908 * Add the dependency to all directly-previous locks that are 'relevant'.
1909 * The ones that are relevant are (in increasing distance from curr):
1910 * all consecutive trylock entries and the final non-trylock entry - or
1911 * the end of this context's lock-chain - whichever comes first.
1914 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1916 int depth = curr->lockdep_depth;
1917 int trylock_loop = 0;
1918 struct held_lock *hlock;
1923 * Depth must not be zero for a non-head lock:
1928 * At least two relevant locks must exist for this
1931 if (curr->held_locks[depth].irq_context !=
1932 curr->held_locks[depth-1].irq_context)
1936 int distance = curr->lockdep_depth - depth + 1;
1937 hlock = curr->held_locks + depth-1;
1939 * Only non-recursive-read entries get new dependencies
1942 if (hlock->read != 2) {
1943 if (!check_prev_add(curr, hlock, next,
1944 distance, trylock_loop))
1947 * Stop after the first non-trylock entry,
1948 * as non-trylock entries have added their
1949 * own direct dependencies already, so this
1950 * lock is connected to them indirectly:
1952 if (!hlock->trylock)
1957 * End of lock-stack?
1962 * Stop the search if we cross into another context:
1964 if (curr->held_locks[depth].irq_context !=
1965 curr->held_locks[depth-1].irq_context)
1971 if (!debug_locks_off_graph_unlock())
1975 * Clearly we all shouldn't be here, but since we made it we
1976 * can reliable say we messed up our state. See the above two
1977 * gotos for reasons why we could possibly end up here.
1984 unsigned long nr_lock_chains;
1985 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1986 int nr_chain_hlocks;
1987 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1989 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1991 return lock_classes + chain_hlocks[chain->base + i];
1995 * Look up a dependency chain. If the key is not present yet then
1996 * add it and return 1 - in this case the new dependency chain is
1997 * validated. If the key is already hashed, return 0.
1998 * (On return with 1 graph_lock is held.)
2000 static inline int lookup_chain_cache(struct task_struct *curr,
2001 struct held_lock *hlock,
2004 struct lock_class *class = hlock_class(hlock);
2005 struct list_head *hash_head = chainhashentry(chain_key);
2006 struct lock_chain *chain;
2007 struct held_lock *hlock_curr, *hlock_next;
2011 * We might need to take the graph lock, ensure we've got IRQs
2012 * disabled to make this an IRQ-safe lock.. for recursion reasons
2013 * lockdep won't complain about its own locking errors.
2015 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2018 * We can walk it lock-free, because entries only get added
2021 list_for_each_entry(chain, hash_head, entry) {
2022 if (chain->chain_key == chain_key) {
2024 debug_atomic_inc(chain_lookup_hits);
2025 if (very_verbose(class))
2026 printk("\nhash chain already cached, key: "
2027 "%016Lx tail class: [%p] %s\n",
2028 (unsigned long long)chain_key,
2029 class->key, class->name);
2033 if (very_verbose(class))
2034 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2035 (unsigned long long)chain_key, class->key, class->name);
2037 * Allocate a new chain entry from the static array, and add
2043 * We have to walk the chain again locked - to avoid duplicates:
2045 list_for_each_entry(chain, hash_head, entry) {
2046 if (chain->chain_key == chain_key) {
2051 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2052 if (!debug_locks_off_graph_unlock())
2055 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2056 printk("turning off the locking correctness validator.\n");
2060 chain = lock_chains + nr_lock_chains++;
2061 chain->chain_key = chain_key;
2062 chain->irq_context = hlock->irq_context;
2063 /* Find the first held_lock of current chain */
2065 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2066 hlock_curr = curr->held_locks + i;
2067 if (hlock_curr->irq_context != hlock_next->irq_context)
2072 chain->depth = curr->lockdep_depth + 1 - i;
2073 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2074 chain->base = nr_chain_hlocks;
2075 nr_chain_hlocks += chain->depth;
2076 for (j = 0; j < chain->depth - 1; j++, i++) {
2077 int lock_id = curr->held_locks[i].class_idx - 1;
2078 chain_hlocks[chain->base + j] = lock_id;
2080 chain_hlocks[chain->base + j] = class - lock_classes;
2082 list_add_tail_rcu(&chain->entry, hash_head);
2083 debug_atomic_inc(chain_lookup_misses);
2089 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2090 struct held_lock *hlock, int chain_head, u64 chain_key)
2093 * Trylock needs to maintain the stack of held locks, but it
2094 * does not add new dependencies, because trylock can be done
2097 * We look up the chain_key and do the O(N^2) check and update of
2098 * the dependencies only if this is a new dependency chain.
2099 * (If lookup_chain_cache() returns with 1 it acquires
2100 * graph_lock for us)
2102 if (!hlock->trylock && (hlock->check == 2) &&
2103 lookup_chain_cache(curr, hlock, chain_key)) {
2105 * Check whether last held lock:
2107 * - is irq-safe, if this lock is irq-unsafe
2108 * - is softirq-safe, if this lock is hardirq-unsafe
2110 * And check whether the new lock's dependency graph
2111 * could lead back to the previous lock.
2113 * any of these scenarios could lead to a deadlock. If
2116 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2121 * Mark recursive read, as we jump over it when
2122 * building dependencies (just like we jump over
2128 * Add dependency only if this lock is not the head
2129 * of the chain, and if it's not a secondary read-lock:
2131 if (!chain_head && ret != 2)
2132 if (!check_prevs_add(curr, hlock))
2136 /* after lookup_chain_cache(): */
2137 if (unlikely(!debug_locks))
2143 static inline int validate_chain(struct task_struct *curr,
2144 struct lockdep_map *lock, struct held_lock *hlock,
2145 int chain_head, u64 chain_key)
2152 * We are building curr_chain_key incrementally, so double-check
2153 * it from scratch, to make sure that it's done correctly:
2155 static void check_chain_key(struct task_struct *curr)
2157 #ifdef CONFIG_DEBUG_LOCKDEP
2158 struct held_lock *hlock, *prev_hlock = NULL;
2162 for (i = 0; i < curr->lockdep_depth; i++) {
2163 hlock = curr->held_locks + i;
2164 if (chain_key != hlock->prev_chain_key) {
2167 * We got mighty confused, our chain keys don't match
2168 * with what we expect, someone trample on our task state?
2170 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2171 curr->lockdep_depth, i,
2172 (unsigned long long)chain_key,
2173 (unsigned long long)hlock->prev_chain_key);
2176 id = hlock->class_idx - 1;
2178 * Whoops ran out of static storage again?
2180 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2183 if (prev_hlock && (prev_hlock->irq_context !=
2184 hlock->irq_context))
2186 chain_key = iterate_chain_key(chain_key, id);
2189 if (chain_key != curr->curr_chain_key) {
2192 * More smoking hash instead of calculating it, damn see these
2193 * numbers float.. I bet that a pink elephant stepped on my memory.
2195 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2196 curr->lockdep_depth, i,
2197 (unsigned long long)chain_key,
2198 (unsigned long long)curr->curr_chain_key);
2204 print_usage_bug_scenario(struct held_lock *lock)
2206 struct lock_class *class = hlock_class(lock);
2208 printk(" Possible unsafe locking scenario:\n\n");
2212 __print_lock_name(class);
2214 printk(" <Interrupt>\n");
2216 __print_lock_name(class);
2218 printk("\n *** DEADLOCK ***\n\n");
2222 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2223 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2225 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2229 printk("=================================\n");
2230 printk("[ INFO: inconsistent lock state ]\n");
2231 print_kernel_ident();
2232 printk("---------------------------------\n");
2234 printk("inconsistent {%s} -> {%s} usage.\n",
2235 usage_str[prev_bit], usage_str[new_bit]);
2237 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2238 curr->comm, task_pid_nr(curr),
2239 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2240 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2241 trace_hardirqs_enabled(curr),
2242 trace_softirqs_enabled(curr));
2245 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2246 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2248 print_irqtrace_events(curr);
2249 printk("\nother info that might help us debug this:\n");
2250 print_usage_bug_scenario(this);
2252 lockdep_print_held_locks(curr);
2254 printk("\nstack backtrace:\n");
2261 * Print out an error if an invalid bit is set:
2264 valid_state(struct task_struct *curr, struct held_lock *this,
2265 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2267 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2268 return print_usage_bug(curr, this, bad_bit, new_bit);
2272 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2273 enum lock_usage_bit new_bit);
2275 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2278 * print irq inversion bug:
2281 print_irq_inversion_bug(struct task_struct *curr,
2282 struct lock_list *root, struct lock_list *other,
2283 struct held_lock *this, int forwards,
2284 const char *irqclass)
2286 struct lock_list *entry = other;
2287 struct lock_list *middle = NULL;
2290 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2294 printk("=========================================================\n");
2295 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2296 print_kernel_ident();
2297 printk("---------------------------------------------------------\n");
2298 printk("%s/%d just changed the state of lock:\n",
2299 curr->comm, task_pid_nr(curr));
2302 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2304 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2305 print_lock_name(other->class);
2306 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2308 printk("\nother info that might help us debug this:\n");
2310 /* Find a middle lock (if one exists) */
2311 depth = get_lock_depth(other);
2313 if (depth == 0 && (entry != root)) {
2314 printk("lockdep:%s bad path found in chain graph\n", __func__);
2318 entry = get_lock_parent(entry);
2320 } while (entry && entry != root && (depth >= 0));
2322 print_irq_lock_scenario(root, other,
2323 middle ? middle->class : root->class, other->class);
2325 print_irq_lock_scenario(other, root,
2326 middle ? middle->class : other->class, root->class);
2328 lockdep_print_held_locks(curr);
2330 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2331 if (!save_trace(&root->trace))
2333 print_shortest_lock_dependencies(other, root);
2335 printk("\nstack backtrace:\n");
2342 * Prove that in the forwards-direction subgraph starting at <this>
2343 * there is no lock matching <mask>:
2346 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2347 enum lock_usage_bit bit, const char *irqclass)
2350 struct lock_list root;
2351 struct lock_list *uninitialized_var(target_entry);
2354 root.class = hlock_class(this);
2355 ret = find_usage_forwards(&root, bit, &target_entry);
2357 return print_bfs_bug(ret);
2361 return print_irq_inversion_bug(curr, &root, target_entry,
2366 * Prove that in the backwards-direction subgraph starting at <this>
2367 * there is no lock matching <mask>:
2370 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2371 enum lock_usage_bit bit, const char *irqclass)
2374 struct lock_list root;
2375 struct lock_list *uninitialized_var(target_entry);
2378 root.class = hlock_class(this);
2379 ret = find_usage_backwards(&root, bit, &target_entry);
2381 return print_bfs_bug(ret);
2385 return print_irq_inversion_bug(curr, &root, target_entry,
2389 void print_irqtrace_events(struct task_struct *curr)
2391 printk("irq event stamp: %u\n", curr->irq_events);
2392 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2393 print_ip_sym(curr->hardirq_enable_ip);
2394 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2395 print_ip_sym(curr->hardirq_disable_ip);
2396 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2397 print_ip_sym(curr->softirq_enable_ip);
2398 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2399 print_ip_sym(curr->softirq_disable_ip);
2402 static int HARDIRQ_verbose(struct lock_class *class)
2405 return class_filter(class);
2410 static int SOFTIRQ_verbose(struct lock_class *class)
2413 return class_filter(class);
2418 static int RECLAIM_FS_verbose(struct lock_class *class)
2421 return class_filter(class);
2426 #define STRICT_READ_CHECKS 1
2428 static int (*state_verbose_f[])(struct lock_class *class) = {
2429 #define LOCKDEP_STATE(__STATE) \
2431 #include "lockdep_states.h"
2432 #undef LOCKDEP_STATE
2435 static inline int state_verbose(enum lock_usage_bit bit,
2436 struct lock_class *class)
2438 return state_verbose_f[bit >> 2](class);
2441 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2442 enum lock_usage_bit bit, const char *name);
2445 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2446 enum lock_usage_bit new_bit)
2448 int excl_bit = exclusive_bit(new_bit);
2449 int read = new_bit & 1;
2450 int dir = new_bit & 2;
2453 * mark USED_IN has to look forwards -- to ensure no dependency
2454 * has ENABLED state, which would allow recursion deadlocks.
2456 * mark ENABLED has to look backwards -- to ensure no dependee
2457 * has USED_IN state, which, again, would allow recursion deadlocks.
2459 check_usage_f usage = dir ?
2460 check_usage_backwards : check_usage_forwards;
2463 * Validate that this particular lock does not have conflicting
2466 if (!valid_state(curr, this, new_bit, excl_bit))
2470 * Validate that the lock dependencies don't have conflicting usage
2473 if ((!read || !dir || STRICT_READ_CHECKS) &&
2474 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2478 * Check for read in write conflicts
2481 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2484 if (STRICT_READ_CHECKS &&
2485 !usage(curr, this, excl_bit + 1,
2486 state_name(new_bit + 1)))
2490 if (state_verbose(new_bit, hlock_class(this)))
2497 #define LOCKDEP_STATE(__STATE) __STATE,
2498 #include "lockdep_states.h"
2499 #undef LOCKDEP_STATE
2503 * Mark all held locks with a usage bit:
2506 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2508 enum lock_usage_bit usage_bit;
2509 struct held_lock *hlock;
2512 for (i = 0; i < curr->lockdep_depth; i++) {
2513 hlock = curr->held_locks + i;
2515 usage_bit = 2 + (mark << 2); /* ENABLED */
2517 usage_bit += 1; /* READ */
2519 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2521 if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
2524 if (!mark_lock(curr, hlock, usage_bit))
2532 * Hardirqs will be enabled:
2534 static void __trace_hardirqs_on_caller(unsigned long ip)
2536 struct task_struct *curr = current;
2538 /* we'll do an OFF -> ON transition: */
2539 curr->hardirqs_enabled = 1;
2542 * We are going to turn hardirqs on, so set the
2543 * usage bit for all held locks:
2545 if (!mark_held_locks(curr, HARDIRQ))
2548 * If we have softirqs enabled, then set the usage
2549 * bit for all held locks. (disabled hardirqs prevented
2550 * this bit from being set before)
2552 if (curr->softirqs_enabled)
2553 if (!mark_held_locks(curr, SOFTIRQ))
2556 curr->hardirq_enable_ip = ip;
2557 curr->hardirq_enable_event = ++curr->irq_events;
2558 debug_atomic_inc(hardirqs_on_events);
2561 void trace_hardirqs_on_caller(unsigned long ip)
2563 time_hardirqs_on(CALLER_ADDR0, ip);
2565 if (unlikely(!debug_locks || current->lockdep_recursion))
2568 if (unlikely(current->hardirqs_enabled)) {
2570 * Neither irq nor preemption are disabled here
2571 * so this is racy by nature but losing one hit
2572 * in a stat is not a big deal.
2574 __debug_atomic_inc(redundant_hardirqs_on);
2579 * We're enabling irqs and according to our state above irqs weren't
2580 * already enabled, yet we find the hardware thinks they are in fact
2581 * enabled.. someone messed up their IRQ state tracing.
2583 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2587 * See the fine text that goes along with this variable definition.
2589 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2593 * Can't allow enabling interrupts while in an interrupt handler,
2594 * that's general bad form and such. Recursion, limited stack etc..
2596 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2599 current->lockdep_recursion = 1;
2600 __trace_hardirqs_on_caller(ip);
2601 current->lockdep_recursion = 0;
2603 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2605 void trace_hardirqs_on(void)
2607 trace_hardirqs_on_caller(CALLER_ADDR0);
2609 EXPORT_SYMBOL(trace_hardirqs_on);
2612 * Hardirqs were disabled:
2614 void trace_hardirqs_off_caller(unsigned long ip)
2616 struct task_struct *curr = current;
2618 time_hardirqs_off(CALLER_ADDR0, ip);
2620 if (unlikely(!debug_locks || current->lockdep_recursion))
2624 * So we're supposed to get called after you mask local IRQs, but for
2625 * some reason the hardware doesn't quite think you did a proper job.
2627 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2630 if (curr->hardirqs_enabled) {
2632 * We have done an ON -> OFF transition:
2634 curr->hardirqs_enabled = 0;
2635 curr->hardirq_disable_ip = ip;
2636 curr->hardirq_disable_event = ++curr->irq_events;
2637 debug_atomic_inc(hardirqs_off_events);
2639 debug_atomic_inc(redundant_hardirqs_off);
2641 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2643 void trace_hardirqs_off(void)
2645 trace_hardirqs_off_caller(CALLER_ADDR0);
2647 EXPORT_SYMBOL(trace_hardirqs_off);
2650 * Softirqs will be enabled:
2652 void trace_softirqs_on(unsigned long ip)
2654 struct task_struct *curr = current;
2656 if (unlikely(!debug_locks || current->lockdep_recursion))
2660 * We fancy IRQs being disabled here, see softirq.c, avoids
2661 * funny state and nesting things.
2663 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2666 if (curr->softirqs_enabled) {
2667 debug_atomic_inc(redundant_softirqs_on);
2671 current->lockdep_recursion = 1;
2673 * We'll do an OFF -> ON transition:
2675 curr->softirqs_enabled = 1;
2676 curr->softirq_enable_ip = ip;
2677 curr->softirq_enable_event = ++curr->irq_events;
2678 debug_atomic_inc(softirqs_on_events);
2680 * We are going to turn softirqs on, so set the
2681 * usage bit for all held locks, if hardirqs are
2684 if (curr->hardirqs_enabled)
2685 mark_held_locks(curr, SOFTIRQ);
2686 current->lockdep_recursion = 0;
2690 * Softirqs were disabled:
2692 void trace_softirqs_off(unsigned long ip)
2694 struct task_struct *curr = current;
2696 if (unlikely(!debug_locks || current->lockdep_recursion))
2700 * We fancy IRQs being disabled here, see softirq.c
2702 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2705 if (curr->softirqs_enabled) {
2707 * We have done an ON -> OFF transition:
2709 curr->softirqs_enabled = 0;
2710 curr->softirq_disable_ip = ip;
2711 curr->softirq_disable_event = ++curr->irq_events;
2712 debug_atomic_inc(softirqs_off_events);
2714 * Whoops, we wanted softirqs off, so why aren't they?
2716 DEBUG_LOCKS_WARN_ON(!softirq_count());
2718 debug_atomic_inc(redundant_softirqs_off);
2721 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2723 struct task_struct *curr = current;
2725 if (unlikely(!debug_locks))
2728 /* no reclaim without waiting on it */
2729 if (!(gfp_mask & __GFP_WAIT))
2732 /* this guy won't enter reclaim */
2733 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2736 /* We're only interested __GFP_FS allocations for now */
2737 if (!(gfp_mask & __GFP_FS))
2741 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2743 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2746 mark_held_locks(curr, RECLAIM_FS);
2749 static void check_flags(unsigned long flags);
2751 void lockdep_trace_alloc(gfp_t gfp_mask)
2753 unsigned long flags;
2755 if (unlikely(current->lockdep_recursion))
2758 raw_local_irq_save(flags);
2760 current->lockdep_recursion = 1;
2761 __lockdep_trace_alloc(gfp_mask, flags);
2762 current->lockdep_recursion = 0;
2763 raw_local_irq_restore(flags);
2766 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2769 * If non-trylock use in a hardirq or softirq context, then
2770 * mark the lock as used in these contexts:
2772 if (!hlock->trylock) {
2774 if (curr->hardirq_context)
2775 if (!mark_lock(curr, hlock,
2776 LOCK_USED_IN_HARDIRQ_READ))
2778 if (curr->softirq_context)
2779 if (!mark_lock(curr, hlock,
2780 LOCK_USED_IN_SOFTIRQ_READ))
2783 if (curr->hardirq_context)
2784 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2786 if (curr->softirq_context)
2787 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2791 if (!hlock->hardirqs_off) {
2793 if (!mark_lock(curr, hlock,
2794 LOCK_ENABLED_HARDIRQ_READ))
2796 if (curr->softirqs_enabled)
2797 if (!mark_lock(curr, hlock,
2798 LOCK_ENABLED_SOFTIRQ_READ))
2801 if (!mark_lock(curr, hlock,
2802 LOCK_ENABLED_HARDIRQ))
2804 if (curr->softirqs_enabled)
2805 if (!mark_lock(curr, hlock,
2806 LOCK_ENABLED_SOFTIRQ))
2812 * We reuse the irq context infrastructure more broadly as a general
2813 * context checking code. This tests GFP_FS recursion (a lock taken
2814 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2817 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2819 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2822 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2830 static int separate_irq_context(struct task_struct *curr,
2831 struct held_lock *hlock)
2833 unsigned int depth = curr->lockdep_depth;
2836 * Keep track of points where we cross into an interrupt context:
2838 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2839 curr->softirq_context;
2841 struct held_lock *prev_hlock;
2843 prev_hlock = curr->held_locks + depth-1;
2845 * If we cross into another context, reset the
2846 * hash key (this also prevents the checking and the
2847 * adding of the dependency to 'prev'):
2849 if (prev_hlock->irq_context != hlock->irq_context)
2855 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2858 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2859 enum lock_usage_bit new_bit)
2861 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2865 static inline int mark_irqflags(struct task_struct *curr,
2866 struct held_lock *hlock)
2871 static inline int separate_irq_context(struct task_struct *curr,
2872 struct held_lock *hlock)
2877 void lockdep_trace_alloc(gfp_t gfp_mask)
2881 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2884 * Mark a lock with a usage bit, and validate the state transition:
2886 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2887 enum lock_usage_bit new_bit)
2889 unsigned int new_mask = 1 << new_bit, ret = 1;
2892 * If already set then do not dirty the cacheline,
2893 * nor do any checks:
2895 if (likely(hlock_class(this)->usage_mask & new_mask))
2901 * Make sure we didn't race:
2903 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2908 hlock_class(this)->usage_mask |= new_mask;
2910 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2914 #define LOCKDEP_STATE(__STATE) \
2915 case LOCK_USED_IN_##__STATE: \
2916 case LOCK_USED_IN_##__STATE##_READ: \
2917 case LOCK_ENABLED_##__STATE: \
2918 case LOCK_ENABLED_##__STATE##_READ:
2919 #include "lockdep_states.h"
2920 #undef LOCKDEP_STATE
2921 ret = mark_lock_irq(curr, this, new_bit);
2926 debug_atomic_dec(nr_unused_locks);
2929 if (!debug_locks_off_graph_unlock())
2938 * We must printk outside of the graph_lock:
2941 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2943 print_irqtrace_events(curr);
2951 * Initialize a lock instance's lock-class mapping info:
2953 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2954 struct lock_class_key *key, int subclass)
2958 kmemcheck_mark_initialized(lock, sizeof(*lock));
2960 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2961 lock->class_cache[i] = NULL;
2963 #ifdef CONFIG_LOCK_STAT
2964 lock->cpu = raw_smp_processor_id();
2968 * Can't be having no nameless bastards around this place!
2970 if (DEBUG_LOCKS_WARN_ON(!name)) {
2971 lock->name = "NULL";
2978 * No key, no joy, we need to hash something.
2980 if (DEBUG_LOCKS_WARN_ON(!key))
2983 * Sanity check, the lock-class key must be persistent:
2985 if (!static_obj(key)) {
2986 printk("BUG: key %p not in .data!\n", key);
2988 * What it says above ^^^^^, I suggest you read it.
2990 DEBUG_LOCKS_WARN_ON(1);
2995 if (unlikely(!debug_locks))
2999 register_lock_class(lock, subclass, 1);
3001 EXPORT_SYMBOL_GPL(lockdep_init_map);
3003 struct lock_class_key __lockdep_no_validate__;
3006 * This gets called for every mutex_lock*()/spin_lock*() operation.
3007 * We maintain the dependency maps and validate the locking attempt:
3009 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3010 int trylock, int read, int check, int hardirqs_off,
3011 struct lockdep_map *nest_lock, unsigned long ip,
3014 struct task_struct *curr = current;
3015 struct lock_class *class = NULL;
3016 struct held_lock *hlock;
3017 unsigned int depth, id;
3025 if (unlikely(!debug_locks))
3029 * Lockdep should run with IRQs disabled, otherwise we could
3030 * get an interrupt which would want to take locks, which would
3031 * end up in lockdep and have you got a head-ache already?
3033 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3036 if (lock->key == &__lockdep_no_validate__)
3039 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3040 class = lock->class_cache[subclass];
3044 if (unlikely(!class)) {
3045 class = register_lock_class(lock, subclass, 0);
3049 atomic_inc((atomic_t *)&class->ops);
3050 if (very_verbose(class)) {
3051 printk("\nacquire class [%p] %s", class->key, class->name);
3052 if (class->name_version > 1)
3053 printk("#%d", class->name_version);
3059 * Add the lock to the list of currently held locks.
3060 * (we dont increase the depth just yet, up until the
3061 * dependency checks are done)
3063 depth = curr->lockdep_depth;
3065 * Ran out of static storage for our per-task lock stack again have we?
3067 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3070 class_idx = class - lock_classes + 1;
3073 hlock = curr->held_locks + depth - 1;
3074 if (hlock->class_idx == class_idx && nest_lock) {
3075 if (hlock->references)
3076 hlock->references++;
3078 hlock->references = 2;
3084 hlock = curr->held_locks + depth;
3086 * Plain impossible, we just registered it and checked it weren't no
3087 * NULL like.. I bet this mushroom I ate was good!
3089 if (DEBUG_LOCKS_WARN_ON(!class))
3091 hlock->class_idx = class_idx;
3092 hlock->acquire_ip = ip;
3093 hlock->instance = lock;
3094 hlock->nest_lock = nest_lock;
3095 hlock->trylock = trylock;
3097 hlock->check = check;
3098 hlock->hardirqs_off = !!hardirqs_off;
3099 hlock->references = references;
3100 #ifdef CONFIG_LOCK_STAT
3101 hlock->waittime_stamp = 0;
3102 hlock->holdtime_stamp = lockstat_clock();
3105 if (check == 2 && !mark_irqflags(curr, hlock))
3108 /* mark it as used: */
3109 if (!mark_lock(curr, hlock, LOCK_USED))
3113 * Calculate the chain hash: it's the combined hash of all the
3114 * lock keys along the dependency chain. We save the hash value
3115 * at every step so that we can get the current hash easily
3116 * after unlock. The chain hash is then used to cache dependency
3119 * The 'key ID' is what is the most compact key value to drive
3120 * the hash, not class->key.
3122 id = class - lock_classes;
3124 * Whoops, we did it again.. ran straight out of our static allocation.
3126 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3129 chain_key = curr->curr_chain_key;
3132 * How can we have a chain hash when we ain't got no keys?!
3134 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3139 hlock->prev_chain_key = chain_key;
3140 if (separate_irq_context(curr, hlock)) {
3144 chain_key = iterate_chain_key(chain_key, id);
3146 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3149 curr->curr_chain_key = chain_key;
3150 curr->lockdep_depth++;
3151 check_chain_key(curr);
3152 #ifdef CONFIG_DEBUG_LOCKDEP
3153 if (unlikely(!debug_locks))
3156 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3158 printk("BUG: MAX_LOCK_DEPTH too low!\n");
3159 printk("turning off the locking correctness validator.\n");
3164 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3165 max_lockdep_depth = curr->lockdep_depth;
3171 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3174 if (!debug_locks_off())
3176 if (debug_locks_silent)
3180 printk("=====================================\n");
3181 printk("[ BUG: bad unlock balance detected! ]\n");
3182 print_kernel_ident();
3183 printk("-------------------------------------\n");
3184 printk("%s/%d is trying to release lock (",
3185 curr->comm, task_pid_nr(curr));
3186 print_lockdep_cache(lock);
3189 printk("but there are no more locks to release!\n");
3190 printk("\nother info that might help us debug this:\n");
3191 lockdep_print_held_locks(curr);
3193 printk("\nstack backtrace:\n");
3200 * Common debugging checks for both nested and non-nested unlock:
3202 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3205 if (unlikely(!debug_locks))
3208 * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
3210 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3213 if (curr->lockdep_depth <= 0)
3214 return print_unlock_inbalance_bug(curr, lock, ip);
3219 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3221 if (hlock->instance == lock)
3224 if (hlock->references) {
3225 struct lock_class *class = lock->class_cache[0];
3228 class = look_up_lock_class(lock, 0);
3231 * If look_up_lock_class() failed to find a class, we're trying
3232 * to test if we hold a lock that has never yet been acquired.
3233 * Clearly if the lock hasn't been acquired _ever_, we're not
3234 * holding it either, so report failure.
3240 * References, but not a lock we're actually ref-counting?
3241 * State got messed up, follow the sites that change ->references
3242 * and try to make sense of it.
3244 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3247 if (hlock->class_idx == class - lock_classes + 1)
3255 __lock_set_class(struct lockdep_map *lock, const char *name,
3256 struct lock_class_key *key, unsigned int subclass,
3259 struct task_struct *curr = current;
3260 struct held_lock *hlock, *prev_hlock;
3261 struct lock_class *class;
3265 depth = curr->lockdep_depth;
3267 * This function is about (re)setting the class of a held lock,
3268 * yet we're not actually holding any locks. Naughty user!
3270 if (DEBUG_LOCKS_WARN_ON(!depth))
3274 for (i = depth-1; i >= 0; i--) {
3275 hlock = curr->held_locks + i;
3277 * We must not cross into another context:
3279 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3281 if (match_held_lock(hlock, lock))
3285 return print_unlock_inbalance_bug(curr, lock, ip);
3288 lockdep_init_map(lock, name, key, 0);
3289 class = register_lock_class(lock, subclass, 0);
3290 hlock->class_idx = class - lock_classes + 1;
3292 curr->lockdep_depth = i;
3293 curr->curr_chain_key = hlock->prev_chain_key;
3295 for (; i < depth; i++) {
3296 hlock = curr->held_locks + i;
3297 if (!__lock_acquire(hlock->instance,
3298 hlock_class(hlock)->subclass, hlock->trylock,
3299 hlock->read, hlock->check, hlock->hardirqs_off,
3300 hlock->nest_lock, hlock->acquire_ip,
3306 * I took it apart and put it back together again, except now I have
3307 * these 'spare' parts.. where shall I put them.
3309 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3315 * Remove the lock to the list of currently held locks in a
3316 * potentially non-nested (out of order) manner. This is a
3317 * relatively rare operation, as all the unlock APIs default
3318 * to nested mode (which uses lock_release()):
3321 lock_release_non_nested(struct task_struct *curr,
3322 struct lockdep_map *lock, unsigned long ip)
3324 struct held_lock *hlock, *prev_hlock;
3329 * Check whether the lock exists in the current stack
3332 depth = curr->lockdep_depth;
3334 * So we're all set to release this lock.. wait what lock? We don't
3335 * own any locks, you've been drinking again?
3337 if (DEBUG_LOCKS_WARN_ON(!depth))
3341 for (i = depth-1; i >= 0; i--) {
3342 hlock = curr->held_locks + i;
3344 * We must not cross into another context:
3346 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3348 if (match_held_lock(hlock, lock))
3352 return print_unlock_inbalance_bug(curr, lock, ip);
3355 if (hlock->instance == lock)
3356 lock_release_holdtime(hlock);
3358 if (hlock->references) {
3359 hlock->references--;
3360 if (hlock->references) {
3362 * We had, and after removing one, still have
3363 * references, the current lock stack is still
3364 * valid. We're done!
3371 * We have the right lock to unlock, 'hlock' points to it.
3372 * Now we remove it from the stack, and add back the other
3373 * entries (if any), recalculating the hash along the way:
3376 curr->lockdep_depth = i;
3377 curr->curr_chain_key = hlock->prev_chain_key;
3379 for (i++; i < depth; i++) {
3380 hlock = curr->held_locks + i;
3381 if (!__lock_acquire(hlock->instance,
3382 hlock_class(hlock)->subclass, hlock->trylock,
3383 hlock->read, hlock->check, hlock->hardirqs_off,
3384 hlock->nest_lock, hlock->acquire_ip,
3390 * We had N bottles of beer on the wall, we drank one, but now
3391 * there's not N-1 bottles of beer left on the wall...
3393 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3399 * Remove the lock to the list of currently held locks - this gets
3400 * called on mutex_unlock()/spin_unlock*() (or on a failed
3401 * mutex_lock_interruptible()). This is done for unlocks that nest
3402 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3404 static int lock_release_nested(struct task_struct *curr,
3405 struct lockdep_map *lock, unsigned long ip)
3407 struct held_lock *hlock;
3411 * Pop off the top of the lock stack:
3413 depth = curr->lockdep_depth - 1;
3414 hlock = curr->held_locks + depth;
3417 * Is the unlock non-nested:
3419 if (hlock->instance != lock || hlock->references)
3420 return lock_release_non_nested(curr, lock, ip);
3421 curr->lockdep_depth--;
3424 * No more locks, but somehow we've got hash left over, who left it?
3426 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3429 curr->curr_chain_key = hlock->prev_chain_key;
3431 lock_release_holdtime(hlock);
3433 #ifdef CONFIG_DEBUG_LOCKDEP
3434 hlock->prev_chain_key = 0;
3435 hlock->class_idx = 0;
3436 hlock->acquire_ip = 0;
3437 hlock->irq_context = 0;
3443 * Remove the lock to the list of currently held locks - this gets
3444 * called on mutex_unlock()/spin_unlock*() (or on a failed
3445 * mutex_lock_interruptible()). This is done for unlocks that nest
3446 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3449 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3451 struct task_struct *curr = current;
3453 if (!check_unlock(curr, lock, ip))
3457 if (!lock_release_nested(curr, lock, ip))
3460 if (!lock_release_non_nested(curr, lock, ip))
3464 check_chain_key(curr);
3467 static int __lock_is_held(struct lockdep_map *lock)
3469 struct task_struct *curr = current;
3472 for (i = 0; i < curr->lockdep_depth; i++) {
3473 struct held_lock *hlock = curr->held_locks + i;
3475 if (match_held_lock(hlock, lock))
3483 * Check whether we follow the irq-flags state precisely:
3485 static void check_flags(unsigned long flags)
3487 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3488 defined(CONFIG_TRACE_IRQFLAGS)
3492 if (irqs_disabled_flags(flags)) {
3493 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3494 printk("possible reason: unannotated irqs-off.\n");
3497 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3498 printk("possible reason: unannotated irqs-on.\n");
3503 * We dont accurately track softirq state in e.g.
3504 * hardirq contexts (such as on 4KSTACKS), so only
3505 * check if not in hardirq contexts:
3507 if (!hardirq_count()) {
3508 if (softirq_count()) {
3509 /* like the above, but with softirqs */
3510 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3512 /* lick the above, does it taste good? */
3513 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3518 print_irqtrace_events(current);
3522 void lock_set_class(struct lockdep_map *lock, const char *name,
3523 struct lock_class_key *key, unsigned int subclass,
3526 unsigned long flags;
3528 if (unlikely(current->lockdep_recursion))
3531 raw_local_irq_save(flags);
3532 current->lockdep_recursion = 1;
3534 if (__lock_set_class(lock, name, key, subclass, ip))
3535 check_chain_key(current);
3536 current->lockdep_recursion = 0;
3537 raw_local_irq_restore(flags);
3539 EXPORT_SYMBOL_GPL(lock_set_class);
3542 * We are not always called with irqs disabled - do that here,
3543 * and also avoid lockdep recursion:
3545 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3546 int trylock, int read, int check,
3547 struct lockdep_map *nest_lock, unsigned long ip)
3549 unsigned long flags;
3551 if (unlikely(current->lockdep_recursion))
3554 raw_local_irq_save(flags);
3557 current->lockdep_recursion = 1;
3558 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3559 __lock_acquire(lock, subclass, trylock, read, check,
3560 irqs_disabled_flags(flags), nest_lock, ip, 0);
3561 current->lockdep_recursion = 0;
3562 raw_local_irq_restore(flags);
3564 EXPORT_SYMBOL_GPL(lock_acquire);
3566 void lock_release(struct lockdep_map *lock, int nested,
3569 unsigned long flags;
3571 if (unlikely(current->lockdep_recursion))
3574 raw_local_irq_save(flags);
3576 current->lockdep_recursion = 1;
3577 trace_lock_release(lock, ip);
3578 __lock_release(lock, nested, ip);
3579 current->lockdep_recursion = 0;
3580 raw_local_irq_restore(flags);
3582 EXPORT_SYMBOL_GPL(lock_release);
3584 int lock_is_held(struct lockdep_map *lock)
3586 unsigned long flags;
3589 if (unlikely(current->lockdep_recursion))
3590 return 1; /* avoid false negative lockdep_assert_held() */
3592 raw_local_irq_save(flags);
3595 current->lockdep_recursion = 1;
3596 ret = __lock_is_held(lock);
3597 current->lockdep_recursion = 0;
3598 raw_local_irq_restore(flags);
3602 EXPORT_SYMBOL_GPL(lock_is_held);
3604 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3606 current->lockdep_reclaim_gfp = gfp_mask;
3609 void lockdep_clear_current_reclaim_state(void)
3611 current->lockdep_reclaim_gfp = 0;
3614 #ifdef CONFIG_LOCK_STAT
3616 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3619 if (!debug_locks_off())
3621 if (debug_locks_silent)
3625 printk("=================================\n");
3626 printk("[ BUG: bad contention detected! ]\n");
3627 print_kernel_ident();
3628 printk("---------------------------------\n");
3629 printk("%s/%d is trying to contend lock (",
3630 curr->comm, task_pid_nr(curr));
3631 print_lockdep_cache(lock);
3634 printk("but there are no locks held!\n");
3635 printk("\nother info that might help us debug this:\n");
3636 lockdep_print_held_locks(curr);
3638 printk("\nstack backtrace:\n");
3645 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3647 struct task_struct *curr = current;
3648 struct held_lock *hlock, *prev_hlock;
3649 struct lock_class_stats *stats;
3651 int i, contention_point, contending_point;
3653 depth = curr->lockdep_depth;
3655 * Whee, we contended on this lock, except it seems we're not
3656 * actually trying to acquire anything much at all..
3658 if (DEBUG_LOCKS_WARN_ON(!depth))
3662 for (i = depth-1; i >= 0; i--) {
3663 hlock = curr->held_locks + i;
3665 * We must not cross into another context:
3667 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3669 if (match_held_lock(hlock, lock))
3673 print_lock_contention_bug(curr, lock, ip);
3677 if (hlock->instance != lock)
3680 hlock->waittime_stamp = lockstat_clock();
3682 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3683 contending_point = lock_point(hlock_class(hlock)->contending_point,
3686 stats = get_lock_stats(hlock_class(hlock));
3687 if (contention_point < LOCKSTAT_POINTS)
3688 stats->contention_point[contention_point]++;
3689 if (contending_point < LOCKSTAT_POINTS)
3690 stats->contending_point[contending_point]++;
3691 if (lock->cpu != smp_processor_id())
3692 stats->bounces[bounce_contended + !!hlock->read]++;
3693 put_lock_stats(stats);
3697 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3699 struct task_struct *curr = current;
3700 struct held_lock *hlock, *prev_hlock;
3701 struct lock_class_stats *stats;
3703 u64 now, waittime = 0;
3706 depth = curr->lockdep_depth;
3708 * Yay, we acquired ownership of this lock we didn't try to
3709 * acquire, how the heck did that happen?
3711 if (DEBUG_LOCKS_WARN_ON(!depth))
3715 for (i = depth-1; i >= 0; i--) {
3716 hlock = curr->held_locks + i;
3718 * We must not cross into another context:
3720 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3722 if (match_held_lock(hlock, lock))
3726 print_lock_contention_bug(curr, lock, _RET_IP_);
3730 if (hlock->instance != lock)
3733 cpu = smp_processor_id();
3734 if (hlock->waittime_stamp) {
3735 now = lockstat_clock();
3736 waittime = now - hlock->waittime_stamp;
3737 hlock->holdtime_stamp = now;
3740 trace_lock_acquired(lock, ip);
3742 stats = get_lock_stats(hlock_class(hlock));
3745 lock_time_inc(&stats->read_waittime, waittime);
3747 lock_time_inc(&stats->write_waittime, waittime);
3749 if (lock->cpu != cpu)
3750 stats->bounces[bounce_acquired + !!hlock->read]++;
3751 put_lock_stats(stats);
3757 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3759 unsigned long flags;
3761 if (unlikely(!lock_stat))
3764 if (unlikely(current->lockdep_recursion))
3767 raw_local_irq_save(flags);
3769 current->lockdep_recursion = 1;
3770 trace_lock_contended(lock, ip);
3771 __lock_contended(lock, ip);
3772 current->lockdep_recursion = 0;
3773 raw_local_irq_restore(flags);
3775 EXPORT_SYMBOL_GPL(lock_contended);
3777 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3779 unsigned long flags;
3781 if (unlikely(!lock_stat))
3784 if (unlikely(current->lockdep_recursion))
3787 raw_local_irq_save(flags);
3789 current->lockdep_recursion = 1;
3790 __lock_acquired(lock, ip);
3791 current->lockdep_recursion = 0;
3792 raw_local_irq_restore(flags);
3794 EXPORT_SYMBOL_GPL(lock_acquired);
3798 * Used by the testsuite, sanitize the validator state
3799 * after a simulated failure:
3802 void lockdep_reset(void)
3804 unsigned long flags;
3807 raw_local_irq_save(flags);
3808 current->curr_chain_key = 0;
3809 current->lockdep_depth = 0;
3810 current->lockdep_recursion = 0;
3811 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3812 nr_hardirq_chains = 0;
3813 nr_softirq_chains = 0;
3814 nr_process_chains = 0;
3816 for (i = 0; i < CHAINHASH_SIZE; i++)
3817 INIT_LIST_HEAD(chainhash_table + i);
3818 raw_local_irq_restore(flags);
3821 static void zap_class(struct lock_class *class)
3826 * Remove all dependencies this lock is
3829 for (i = 0; i < nr_list_entries; i++) {
3830 if (list_entries[i].class == class)
3831 list_del_rcu(&list_entries[i].entry);
3834 * Unhash the class and remove it from the all_lock_classes list:
3836 list_del_rcu(&class->hash_entry);
3837 list_del_rcu(&class->lock_entry);
3842 static inline int within(const void *addr, void *start, unsigned long size)
3844 return addr >= start && addr < start + size;
3847 void lockdep_free_key_range(void *start, unsigned long size)
3849 struct lock_class *class, *next;
3850 struct list_head *head;
3851 unsigned long flags;
3855 raw_local_irq_save(flags);
3856 locked = graph_lock();
3859 * Unhash all classes that were created by this module:
3861 for (i = 0; i < CLASSHASH_SIZE; i++) {
3862 head = classhash_table + i;
3863 if (list_empty(head))
3865 list_for_each_entry_safe(class, next, head, hash_entry) {
3866 if (within(class->key, start, size))
3868 else if (within(class->name, start, size))
3875 raw_local_irq_restore(flags);
3878 void lockdep_reset_lock(struct lockdep_map *lock)
3880 struct lock_class *class, *next;
3881 struct list_head *head;
3882 unsigned long flags;
3886 raw_local_irq_save(flags);
3889 * Remove all classes this lock might have:
3891 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3893 * If the class exists we look it up and zap it:
3895 class = look_up_lock_class(lock, j);
3900 * Debug check: in the end all mapped classes should
3903 locked = graph_lock();
3904 for (i = 0; i < CLASSHASH_SIZE; i++) {
3905 head = classhash_table + i;
3906 if (list_empty(head))
3908 list_for_each_entry_safe(class, next, head, hash_entry) {
3911 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3912 match |= class == lock->class_cache[j];
3914 if (unlikely(match)) {
3915 if (debug_locks_off_graph_unlock()) {
3917 * We all just reset everything, how did it match?
3929 raw_local_irq_restore(flags);
3932 void lockdep_init(void)
3937 * Some architectures have their own start_kernel()
3938 * code which calls lockdep_init(), while we also
3939 * call lockdep_init() from the start_kernel() itself,
3940 * and we want to initialize the hashes only once:
3942 if (lockdep_initialized)
3945 for (i = 0; i < CLASSHASH_SIZE; i++)
3946 INIT_LIST_HEAD(classhash_table + i);
3948 for (i = 0; i < CHAINHASH_SIZE; i++)
3949 INIT_LIST_HEAD(chainhash_table + i);
3951 lockdep_initialized = 1;
3954 void __init lockdep_info(void)
3956 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3958 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3959 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3960 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3961 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3962 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3963 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3964 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3966 printk(" memory used by lock dependency info: %lu kB\n",
3967 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3968 sizeof(struct list_head) * CLASSHASH_SIZE +
3969 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3970 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3971 sizeof(struct list_head) * CHAINHASH_SIZE
3972 #ifdef CONFIG_PROVE_LOCKING
3973 + sizeof(struct circular_queue)
3978 printk(" per task-struct memory footprint: %lu bytes\n",
3979 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3981 #ifdef CONFIG_DEBUG_LOCKDEP
3982 if (lockdep_init_error) {
3983 printk("WARNING: lockdep init error! lock-%s was acquired"
3984 "before lockdep_init\n", lock_init_error);
3985 printk("Call stack leading to lockdep invocation was:\n");
3986 print_stack_trace(&lockdep_init_trace, 0);
3992 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3993 const void *mem_to, struct held_lock *hlock)
3995 if (!debug_locks_off())
3997 if (debug_locks_silent)
4001 printk("=========================\n");
4002 printk("[ BUG: held lock freed! ]\n");
4003 print_kernel_ident();
4004 printk("-------------------------\n");
4005 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4006 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4008 lockdep_print_held_locks(curr);
4010 printk("\nstack backtrace:\n");
4014 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4015 const void* lock_from, unsigned long lock_len)
4017 return lock_from + lock_len <= mem_from ||
4018 mem_from + mem_len <= lock_from;
4022 * Called when kernel memory is freed (or unmapped), or if a lock
4023 * is destroyed or reinitialized - this code checks whether there is
4024 * any held lock in the memory range of <from> to <to>:
4026 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4028 struct task_struct *curr = current;
4029 struct held_lock *hlock;
4030 unsigned long flags;
4033 if (unlikely(!debug_locks))
4036 local_irq_save(flags);
4037 for (i = 0; i < curr->lockdep_depth; i++) {
4038 hlock = curr->held_locks + i;
4040 if (not_in_range(mem_from, mem_len, hlock->instance,
4041 sizeof(*hlock->instance)))
4044 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4047 local_irq_restore(flags);
4049 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4051 static void print_held_locks_bug(struct task_struct *curr)
4053 if (!debug_locks_off())
4055 if (debug_locks_silent)
4059 printk("=====================================\n");
4060 printk("[ BUG: lock held at task exit time! ]\n");
4061 print_kernel_ident();
4062 printk("-------------------------------------\n");
4063 printk("%s/%d is exiting with locks still held!\n",
4064 curr->comm, task_pid_nr(curr));
4065 lockdep_print_held_locks(curr);
4067 printk("\nstack backtrace:\n");
4071 void debug_check_no_locks_held(struct task_struct *task)
4073 if (unlikely(task->lockdep_depth > 0))
4074 print_held_locks_bug(task);
4077 void debug_show_all_locks(void)
4079 struct task_struct *g, *p;
4083 if (unlikely(!debug_locks)) {
4084 printk("INFO: lockdep is turned off.\n");
4087 printk("\nShowing all locks held in the system:\n");
4090 * Here we try to get the tasklist_lock as hard as possible,
4091 * if not successful after 2 seconds we ignore it (but keep
4092 * trying). This is to enable a debug printout even if a
4093 * tasklist_lock-holding task deadlocks or crashes.
4096 if (!read_trylock(&tasklist_lock)) {
4098 printk("hm, tasklist_lock locked, retrying... ");
4101 printk(" #%d", 10-count);
4105 printk(" ignoring it.\n");
4109 printk(KERN_CONT " locked it.\n");
4112 do_each_thread(g, p) {
4114 * It's not reliable to print a task's held locks
4115 * if it's not sleeping (or if it's not the current
4118 if (p->state == TASK_RUNNING && p != current)
4120 if (p->lockdep_depth)
4121 lockdep_print_held_locks(p);
4123 if (read_trylock(&tasklist_lock))
4125 } while_each_thread(g, p);
4128 printk("=============================================\n\n");
4131 read_unlock(&tasklist_lock);
4133 EXPORT_SYMBOL_GPL(debug_show_all_locks);
4136 * Careful: only use this function if you are sure that
4137 * the task cannot run in parallel!
4139 void debug_show_held_locks(struct task_struct *task)
4141 if (unlikely(!debug_locks)) {
4142 printk("INFO: lockdep is turned off.\n");
4145 lockdep_print_held_locks(task);
4147 EXPORT_SYMBOL_GPL(debug_show_held_locks);
4149 void lockdep_sys_exit(void)
4151 struct task_struct *curr = current;
4153 if (unlikely(curr->lockdep_depth)) {
4154 if (!debug_locks_off())
4157 printk("================================================\n");
4158 printk("[ BUG: lock held when returning to user space! ]\n");
4159 print_kernel_ident();
4160 printk("------------------------------------------------\n");
4161 printk("%s/%d is leaving the kernel with locks still held!\n",
4162 curr->comm, curr->pid);
4163 lockdep_print_held_locks(curr);
4167 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4169 struct task_struct *curr = current;
4171 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4172 if (!debug_locks_off())
4174 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4175 /* Note: the following can be executed concurrently, so be careful. */
4177 printk("===============================\n");
4178 printk("[ INFO: suspicious RCU usage. ]\n");
4179 print_kernel_ident();
4180 printk("-------------------------------\n");
4181 printk("%s:%d %s!\n", file, line, s);
4182 printk("\nother info that might help us debug this:\n\n");
4183 printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
4186 * If a CPU is in the RCU-free window in idle (ie: in the section
4187 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4188 * considers that CPU to be in an "extended quiescent state",
4189 * which means that RCU will be completely ignoring that CPU.
4190 * Therefore, rcu_read_lock() and friends have absolutely no
4191 * effect on a CPU running in that state. In other words, even if
4192 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4193 * delete data structures out from under it. RCU really has no
4194 * choice here: we need to keep an RCU-free window in idle where
4195 * the CPU may possibly enter into low power mode. This way we can
4196 * notice an extended quiescent state to other CPUs that started a grace
4197 * period. Otherwise we would delay any grace period as long as we run
4200 * So complain bitterly if someone does call rcu_read_lock(),
4201 * rcu_read_lock_bh() and so on from extended quiescent states.
4203 if (rcu_is_cpu_idle())
4204 printk("RCU used illegally from extended quiescent state!\n");
4206 lockdep_print_held_locks(curr);
4207 printk("\nstack backtrace:\n");
4210 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);