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>
48 #include <asm/sections.h>
50 #include "lockdep_internals.h"
52 #define CREATE_TRACE_POINTS
53 #include <trace/events/lock.h>
55 #ifdef CONFIG_PROVE_LOCKING
56 int prove_locking = 1;
57 module_param(prove_locking, int, 0644);
59 #define prove_locking 0
62 #ifdef CONFIG_LOCK_STAT
64 module_param(lock_stat, int, 0644);
70 * lockdep_lock: protects the lockdep graph, the hashes and the
71 * class/list/hash allocators.
73 * This is one of the rare exceptions where it's justified
74 * to use a raw spinlock - we really dont want the spinlock
75 * code to recurse back into the lockdep code...
77 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
79 static int graph_lock(void)
81 arch_spin_lock(&lockdep_lock);
83 * Make sure that if another CPU detected a bug while
84 * walking the graph we dont change it (while the other
85 * CPU is busy printing out stuff with the graph lock
89 arch_spin_unlock(&lockdep_lock);
92 /* prevent any recursions within lockdep from causing deadlocks */
93 current->lockdep_recursion++;
97 static inline int graph_unlock(void)
99 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
101 * The lockdep graph lock isn't locked while we expect it to
102 * be, we're confused now, bye!
104 return DEBUG_LOCKS_WARN_ON(1);
107 current->lockdep_recursion--;
108 arch_spin_unlock(&lockdep_lock);
113 * Turn lock debugging off and return with 0 if it was off already,
114 * and also release the graph lock:
116 static inline int debug_locks_off_graph_unlock(void)
118 int ret = debug_locks_off();
120 arch_spin_unlock(&lockdep_lock);
125 static int lockdep_initialized;
127 unsigned long nr_list_entries;
128 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
131 * All data structures here are protected by the global debug_lock.
133 * Mutex key structs only get allocated, once during bootup, and never
134 * get freed - this significantly simplifies the debugging code.
136 unsigned long nr_lock_classes;
137 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
139 static inline struct lock_class *hlock_class(struct held_lock *hlock)
141 if (!hlock->class_idx) {
143 * Someone passed in garbage, we give up.
145 DEBUG_LOCKS_WARN_ON(1);
148 return lock_classes + hlock->class_idx - 1;
151 #ifdef CONFIG_LOCK_STAT
152 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
155 static inline u64 lockstat_clock(void)
157 return local_clock();
160 static int lock_point(unsigned long points[], unsigned long ip)
164 for (i = 0; i < LOCKSTAT_POINTS; i++) {
165 if (points[i] == 0) {
176 static void lock_time_inc(struct lock_time *lt, u64 time)
181 if (time < lt->min || !lt->nr)
188 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
193 if (src->max > dst->max)
196 if (src->min < dst->min || !dst->nr)
199 dst->total += src->total;
203 struct lock_class_stats lock_stats(struct lock_class *class)
205 struct lock_class_stats stats;
208 memset(&stats, 0, sizeof(struct lock_class_stats));
209 for_each_possible_cpu(cpu) {
210 struct lock_class_stats *pcs =
211 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
213 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
214 stats.contention_point[i] += pcs->contention_point[i];
216 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
217 stats.contending_point[i] += pcs->contending_point[i];
219 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
220 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
222 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
223 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
225 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
226 stats.bounces[i] += pcs->bounces[i];
232 void clear_lock_stats(struct lock_class *class)
236 for_each_possible_cpu(cpu) {
237 struct lock_class_stats *cpu_stats =
238 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
240 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
242 memset(class->contention_point, 0, sizeof(class->contention_point));
243 memset(class->contending_point, 0, sizeof(class->contending_point));
246 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
248 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
251 static void put_lock_stats(struct lock_class_stats *stats)
253 put_cpu_var(cpu_lock_stats);
256 static void lock_release_holdtime(struct held_lock *hlock)
258 struct lock_class_stats *stats;
264 holdtime = lockstat_clock() - hlock->holdtime_stamp;
266 stats = get_lock_stats(hlock_class(hlock));
268 lock_time_inc(&stats->read_holdtime, holdtime);
270 lock_time_inc(&stats->write_holdtime, holdtime);
271 put_lock_stats(stats);
274 static inline void lock_release_holdtime(struct held_lock *hlock)
280 * We keep a global list of all lock classes. The list only grows,
281 * never shrinks. The list is only accessed with the lockdep
282 * spinlock lock held.
284 LIST_HEAD(all_lock_classes);
287 * The lockdep classes are in a hash-table as well, for fast lookup:
289 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
290 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
291 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
292 #define classhashentry(key) (classhash_table + __classhashfn((key)))
294 static struct list_head classhash_table[CLASSHASH_SIZE];
297 * We put the lock dependency chains into a hash-table as well, to cache
300 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
301 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
302 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
303 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
305 static struct list_head chainhash_table[CHAINHASH_SIZE];
308 * The hash key of the lock dependency chains is a hash itself too:
309 * it's a hash of all locks taken up to that lock, including that lock.
310 * It's a 64-bit hash, because it's important for the keys to be
313 #define iterate_chain_key(key1, key2) \
314 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
315 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
318 void lockdep_off(void)
320 current->lockdep_recursion++;
322 EXPORT_SYMBOL(lockdep_off);
324 void lockdep_on(void)
326 current->lockdep_recursion--;
328 EXPORT_SYMBOL(lockdep_on);
331 * Debugging switches:
335 #define VERY_VERBOSE 0
338 # define HARDIRQ_VERBOSE 1
339 # define SOFTIRQ_VERBOSE 1
340 # define RECLAIM_VERBOSE 1
342 # define HARDIRQ_VERBOSE 0
343 # define SOFTIRQ_VERBOSE 0
344 # define RECLAIM_VERBOSE 0
347 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
349 * Quick filtering for interesting events:
351 static int class_filter(struct lock_class *class)
355 if (class->name_version == 1 &&
356 !strcmp(class->name, "lockname"))
358 if (class->name_version == 1 &&
359 !strcmp(class->name, "&struct->lockfield"))
362 /* Filter everything else. 1 would be to allow everything else */
367 static int verbose(struct lock_class *class)
370 return class_filter(class);
376 * Stack-trace: tightly packed array of stack backtrace
377 * addresses. Protected by the graph_lock.
379 unsigned long nr_stack_trace_entries;
380 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
382 static int save_trace(struct stack_trace *trace)
384 trace->nr_entries = 0;
385 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
386 trace->entries = stack_trace + nr_stack_trace_entries;
390 save_stack_trace(trace);
393 * Some daft arches put -1 at the end to indicate its a full trace.
395 * <rant> this is buggy anyway, since it takes a whole extra entry so a
396 * complete trace that maxes out the entries provided will be reported
397 * as incomplete, friggin useless </rant>
399 if (trace->nr_entries != 0 &&
400 trace->entries[trace->nr_entries-1] == ULONG_MAX)
403 trace->max_entries = trace->nr_entries;
405 nr_stack_trace_entries += trace->nr_entries;
407 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
408 if (!debug_locks_off_graph_unlock())
411 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
412 printk("turning off the locking correctness validator.\n");
421 unsigned int nr_hardirq_chains;
422 unsigned int nr_softirq_chains;
423 unsigned int nr_process_chains;
424 unsigned int max_lockdep_depth;
426 #ifdef CONFIG_DEBUG_LOCKDEP
428 * We cannot printk in early bootup code. Not even early_printk()
429 * might work. So we mark any initialization errors and printk
430 * about it later on, in lockdep_info().
432 static int lockdep_init_error;
433 static unsigned long lockdep_init_trace_data[20];
434 static struct stack_trace lockdep_init_trace = {
435 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
436 .entries = lockdep_init_trace_data,
440 * Various lockdep statistics:
442 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
449 #define __USAGE(__STATE) \
450 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
451 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
452 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
453 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
455 static const char *usage_str[] =
457 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
458 #include "lockdep_states.h"
460 [LOCK_USED] = "INITIAL USE",
463 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
465 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
468 static inline unsigned long lock_flag(enum lock_usage_bit bit)
473 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
477 if (class->usage_mask & lock_flag(bit + 2))
479 if (class->usage_mask & lock_flag(bit)) {
481 if (class->usage_mask & lock_flag(bit + 2))
488 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
492 #define LOCKDEP_STATE(__STATE) \
493 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
494 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
495 #include "lockdep_states.h"
501 static void __print_lock_name(struct lock_class *class)
503 char str[KSYM_NAME_LEN];
508 name = __get_key_name(class->key, str);
512 if (class->name_version > 1)
513 printk("#%d", class->name_version);
515 printk("/%d", class->subclass);
519 static void print_lock_name(struct lock_class *class)
521 char usage[LOCK_USAGE_CHARS];
523 get_usage_chars(class, usage);
526 __print_lock_name(class);
527 printk("){%s}", usage);
530 static void print_lockdep_cache(struct lockdep_map *lock)
533 char str[KSYM_NAME_LEN];
537 name = __get_key_name(lock->key->subkeys, str);
542 static void print_lock(struct held_lock *hlock)
544 print_lock_name(hlock_class(hlock));
546 print_ip_sym(hlock->acquire_ip);
549 static void lockdep_print_held_locks(struct task_struct *curr)
551 int i, depth = curr->lockdep_depth;
554 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
557 printk("%d lock%s held by %s/%d:\n",
558 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
560 for (i = 0; i < depth; i++) {
562 print_lock(curr->held_locks + i);
566 static void print_kernel_version(void)
568 printk("%s %.*s\n", init_utsname()->release,
569 (int)strcspn(init_utsname()->version, " "),
570 init_utsname()->version);
573 static int very_verbose(struct lock_class *class)
576 return class_filter(class);
582 * Is this the address of a static object:
584 static int static_obj(void *obj)
586 unsigned long start = (unsigned long) &_stext,
587 end = (unsigned long) &_end,
588 addr = (unsigned long) obj;
593 if ((addr >= start) && (addr < end))
596 if (arch_is_kernel_data(addr))
600 * in-kernel percpu var?
602 if (is_kernel_percpu_address(addr))
606 * module static or percpu var?
608 return is_module_address(addr) || is_module_percpu_address(addr);
612 * To make lock name printouts unique, we calculate a unique
613 * class->name_version generation counter:
615 static int count_matching_names(struct lock_class *new_class)
617 struct lock_class *class;
620 if (!new_class->name)
623 list_for_each_entry(class, &all_lock_classes, lock_entry) {
624 if (new_class->key - new_class->subclass == class->key)
625 return class->name_version;
626 if (class->name && !strcmp(class->name, new_class->name))
627 count = max(count, class->name_version);
634 * Register a lock's class in the hash-table, if the class is not present
635 * yet. Otherwise we look it up. We cache the result in the lock object
636 * itself, so actual lookup of the hash should be once per lock object.
638 static inline struct lock_class *
639 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
641 struct lockdep_subclass_key *key;
642 struct list_head *hash_head;
643 struct lock_class *class;
645 #ifdef CONFIG_DEBUG_LOCKDEP
647 * If the architecture calls into lockdep before initializing
648 * the hashes then we'll warn about it later. (we cannot printk
651 if (unlikely(!lockdep_initialized)) {
653 lockdep_init_error = 1;
654 save_stack_trace(&lockdep_init_trace);
658 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
661 "BUG: looking up invalid subclass: %u\n", subclass);
663 "turning off the locking correctness validator.\n");
669 * Static locks do not have their class-keys yet - for them the key
670 * is the lock object itself:
672 if (unlikely(!lock->key))
673 lock->key = (void *)lock;
676 * NOTE: the class-key must be unique. For dynamic locks, a static
677 * lock_class_key variable is passed in through the mutex_init()
678 * (or spin_lock_init()) call - which acts as the key. For static
679 * locks we use the lock object itself as the key.
681 BUILD_BUG_ON(sizeof(struct lock_class_key) >
682 sizeof(struct lockdep_map));
684 key = lock->key->subkeys + subclass;
686 hash_head = classhashentry(key);
689 * We can walk the hash lockfree, because the hash only
690 * grows, and we are careful when adding entries to the end:
692 list_for_each_entry(class, hash_head, hash_entry) {
693 if (class->key == key) {
695 * Huh! same key, different name? Did someone trample
696 * on some memory? We're most confused.
698 WARN_ON_ONCE(class->name != lock->name);
707 * Register a lock's class in the hash-table, if the class is not present
708 * yet. Otherwise we look it up. We cache the result in the lock object
709 * itself, so actual lookup of the hash should be once per lock object.
711 static inline struct lock_class *
712 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
714 struct lockdep_subclass_key *key;
715 struct list_head *hash_head;
716 struct lock_class *class;
719 class = look_up_lock_class(lock, subclass);
724 * Debug-check: all keys must be persistent!
726 if (!static_obj(lock->key)) {
728 printk("INFO: trying to register non-static key.\n");
729 printk("the code is fine but needs lockdep annotation.\n");
730 printk("turning off the locking correctness validator.\n");
736 key = lock->key->subkeys + subclass;
737 hash_head = classhashentry(key);
739 raw_local_irq_save(flags);
741 raw_local_irq_restore(flags);
745 * We have to do the hash-walk again, to avoid races
748 list_for_each_entry(class, hash_head, hash_entry)
749 if (class->key == key)
752 * Allocate a new key from the static array, and add it to
755 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
756 if (!debug_locks_off_graph_unlock()) {
757 raw_local_irq_restore(flags);
760 raw_local_irq_restore(flags);
762 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
763 printk("turning off the locking correctness validator.\n");
767 class = lock_classes + nr_lock_classes++;
768 debug_atomic_inc(nr_unused_locks);
770 class->name = lock->name;
771 class->subclass = subclass;
772 INIT_LIST_HEAD(&class->lock_entry);
773 INIT_LIST_HEAD(&class->locks_before);
774 INIT_LIST_HEAD(&class->locks_after);
775 class->name_version = count_matching_names(class);
777 * We use RCU's safe list-add method to make
778 * parallel walking of the hash-list safe:
780 list_add_tail_rcu(&class->hash_entry, hash_head);
782 * Add it to the global list of classes:
784 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
786 if (verbose(class)) {
788 raw_local_irq_restore(flags);
790 printk("\nnew class %p: %s", class->key, class->name);
791 if (class->name_version > 1)
792 printk("#%d", class->name_version);
796 raw_local_irq_save(flags);
798 raw_local_irq_restore(flags);
804 raw_local_irq_restore(flags);
806 if (!subclass || force)
807 lock->class_cache[0] = class;
808 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
809 lock->class_cache[subclass] = class;
812 * Hash collision, did we smoke some? We found a class with a matching
813 * hash but the subclass -- which is hashed in -- didn't match.
815 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
821 #ifdef CONFIG_PROVE_LOCKING
823 * Allocate a lockdep entry. (assumes the graph_lock held, returns
824 * with NULL on failure)
826 static struct lock_list *alloc_list_entry(void)
828 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
829 if (!debug_locks_off_graph_unlock())
832 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
833 printk("turning off the locking correctness validator.\n");
837 return list_entries + nr_list_entries++;
841 * Add a new dependency to the head of the list:
843 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
844 struct list_head *head, unsigned long ip,
845 int distance, struct stack_trace *trace)
847 struct lock_list *entry;
849 * Lock not present yet - get a new dependency struct and
850 * add it to the list:
852 entry = alloc_list_entry();
857 entry->distance = distance;
858 entry->trace = *trace;
860 * Since we never remove from the dependency list, the list can
861 * be walked lockless by other CPUs, it's only allocation
862 * that must be protected by the spinlock. But this also means
863 * we must make new entries visible only once writes to the
864 * entry become visible - hence the RCU op:
866 list_add_tail_rcu(&entry->entry, head);
872 * For good efficiency of modular, we use power of 2
874 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
875 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
878 * The circular_queue and helpers is used to implement the
879 * breadth-first search(BFS)algorithem, by which we can build
880 * the shortest path from the next lock to be acquired to the
881 * previous held lock if there is a circular between them.
883 struct circular_queue {
884 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
885 unsigned int front, rear;
888 static struct circular_queue lock_cq;
890 unsigned int max_bfs_queue_depth;
892 static unsigned int lockdep_dependency_gen_id;
894 static inline void __cq_init(struct circular_queue *cq)
896 cq->front = cq->rear = 0;
897 lockdep_dependency_gen_id++;
900 static inline int __cq_empty(struct circular_queue *cq)
902 return (cq->front == cq->rear);
905 static inline int __cq_full(struct circular_queue *cq)
907 return ((cq->rear + 1) & CQ_MASK) == cq->front;
910 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
915 cq->element[cq->rear] = elem;
916 cq->rear = (cq->rear + 1) & CQ_MASK;
920 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
925 *elem = cq->element[cq->front];
926 cq->front = (cq->front + 1) & CQ_MASK;
930 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
932 return (cq->rear - cq->front) & CQ_MASK;
935 static inline void mark_lock_accessed(struct lock_list *lock,
936 struct lock_list *parent)
940 nr = lock - list_entries;
941 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
942 lock->parent = parent;
943 lock->class->dep_gen_id = lockdep_dependency_gen_id;
946 static inline unsigned long lock_accessed(struct lock_list *lock)
950 nr = lock - list_entries;
951 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
952 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
955 static inline struct lock_list *get_lock_parent(struct lock_list *child)
957 return child->parent;
960 static inline int get_lock_depth(struct lock_list *child)
963 struct lock_list *parent;
965 while ((parent = get_lock_parent(child))) {
972 static int __bfs(struct lock_list *source_entry,
974 int (*match)(struct lock_list *entry, void *data),
975 struct lock_list **target_entry,
978 struct lock_list *entry;
979 struct list_head *head;
980 struct circular_queue *cq = &lock_cq;
983 if (match(source_entry, data)) {
984 *target_entry = source_entry;
990 head = &source_entry->class->locks_after;
992 head = &source_entry->class->locks_before;
994 if (list_empty(head))
998 __cq_enqueue(cq, (unsigned long)source_entry);
1000 while (!__cq_empty(cq)) {
1001 struct lock_list *lock;
1003 __cq_dequeue(cq, (unsigned long *)&lock);
1011 head = &lock->class->locks_after;
1013 head = &lock->class->locks_before;
1015 list_for_each_entry(entry, head, entry) {
1016 if (!lock_accessed(entry)) {
1017 unsigned int cq_depth;
1018 mark_lock_accessed(entry, lock);
1019 if (match(entry, data)) {
1020 *target_entry = entry;
1025 if (__cq_enqueue(cq, (unsigned long)entry)) {
1029 cq_depth = __cq_get_elem_count(cq);
1030 if (max_bfs_queue_depth < cq_depth)
1031 max_bfs_queue_depth = cq_depth;
1039 static inline int __bfs_forwards(struct lock_list *src_entry,
1041 int (*match)(struct lock_list *entry, void *data),
1042 struct lock_list **target_entry)
1044 return __bfs(src_entry, data, match, target_entry, 1);
1048 static inline int __bfs_backwards(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, 0);
1058 * Recursive, forwards-direction lock-dependency checking, used for
1059 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1064 * Print a dependency chain entry (this is only done when a deadlock
1065 * has been detected):
1068 print_circular_bug_entry(struct lock_list *target, int depth)
1070 if (debug_locks_silent)
1072 printk("\n-> #%u", depth);
1073 print_lock_name(target->class);
1075 print_stack_trace(&target->trace, 6);
1081 print_circular_lock_scenario(struct held_lock *src,
1082 struct held_lock *tgt,
1083 struct lock_list *prt)
1085 struct lock_class *source = hlock_class(src);
1086 struct lock_class *target = hlock_class(tgt);
1087 struct lock_class *parent = prt->class;
1090 * A direct locking problem where unsafe_class lock is taken
1091 * directly by safe_class lock, then all we need to show
1092 * is the deadlock scenario, as it is obvious that the
1093 * unsafe lock is taken under the safe lock.
1095 * But if there is a chain instead, where the safe lock takes
1096 * an intermediate lock (middle_class) where this lock is
1097 * not the same as the safe lock, then the lock chain is
1098 * used to describe the problem. Otherwise we would need
1099 * to show a different CPU case for each link in the chain
1100 * from the safe_class lock to the unsafe_class lock.
1102 if (parent != source) {
1103 printk("Chain exists of:\n ");
1104 __print_lock_name(source);
1106 __print_lock_name(parent);
1108 __print_lock_name(target);
1112 printk(" Possible unsafe locking scenario:\n\n");
1113 printk(" CPU0 CPU1\n");
1114 printk(" ---- ----\n");
1116 __print_lock_name(target);
1119 __print_lock_name(parent);
1122 __print_lock_name(target);
1125 __print_lock_name(source);
1127 printk("\n *** DEADLOCK ***\n\n");
1131 * When a circular dependency is detected, print the
1135 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1136 struct held_lock *check_src,
1137 struct held_lock *check_tgt)
1139 struct task_struct *curr = current;
1141 if (debug_locks_silent)
1145 printk("======================================================\n");
1146 printk("[ INFO: possible circular locking dependency detected ]\n");
1147 print_kernel_version();
1148 printk("-------------------------------------------------------\n");
1149 printk("%s/%d is trying to acquire lock:\n",
1150 curr->comm, task_pid_nr(curr));
1151 print_lock(check_src);
1152 printk("\nbut task is already holding lock:\n");
1153 print_lock(check_tgt);
1154 printk("\nwhich lock already depends on the new lock.\n\n");
1155 printk("\nthe existing dependency chain (in reverse order) is:\n");
1157 print_circular_bug_entry(entry, depth);
1162 static inline int class_equal(struct lock_list *entry, void *data)
1164 return entry->class == data;
1167 static noinline int print_circular_bug(struct lock_list *this,
1168 struct lock_list *target,
1169 struct held_lock *check_src,
1170 struct held_lock *check_tgt)
1172 struct task_struct *curr = current;
1173 struct lock_list *parent;
1174 struct lock_list *first_parent;
1177 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1180 if (!save_trace(&this->trace))
1183 depth = get_lock_depth(target);
1185 print_circular_bug_header(target, depth, check_src, check_tgt);
1187 parent = get_lock_parent(target);
1188 first_parent = parent;
1191 print_circular_bug_entry(parent, --depth);
1192 parent = get_lock_parent(parent);
1195 printk("\nother info that might help us debug this:\n\n");
1196 print_circular_lock_scenario(check_src, check_tgt,
1199 lockdep_print_held_locks(curr);
1201 printk("\nstack backtrace:\n");
1207 static noinline int print_bfs_bug(int ret)
1209 if (!debug_locks_off_graph_unlock())
1213 * Breadth-first-search failed, graph got corrupted?
1215 WARN(1, "lockdep bfs error:%d\n", ret);
1220 static int noop_count(struct lock_list *entry, void *data)
1222 (*(unsigned long *)data)++;
1226 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1228 unsigned long count = 0;
1229 struct lock_list *uninitialized_var(target_entry);
1231 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1235 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1237 unsigned long ret, flags;
1238 struct lock_list this;
1243 local_irq_save(flags);
1244 arch_spin_lock(&lockdep_lock);
1245 ret = __lockdep_count_forward_deps(&this);
1246 arch_spin_unlock(&lockdep_lock);
1247 local_irq_restore(flags);
1252 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1254 unsigned long count = 0;
1255 struct lock_list *uninitialized_var(target_entry);
1257 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1262 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1264 unsigned long ret, flags;
1265 struct lock_list this;
1270 local_irq_save(flags);
1271 arch_spin_lock(&lockdep_lock);
1272 ret = __lockdep_count_backward_deps(&this);
1273 arch_spin_unlock(&lockdep_lock);
1274 local_irq_restore(flags);
1280 * Prove that the dependency graph starting at <entry> can not
1281 * lead to <target>. Print an error and return 0 if it does.
1284 check_noncircular(struct lock_list *root, struct lock_class *target,
1285 struct lock_list **target_entry)
1289 debug_atomic_inc(nr_cyclic_checks);
1291 result = __bfs_forwards(root, target, class_equal, target_entry);
1296 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1298 * Forwards and backwards subgraph searching, for the purposes of
1299 * proving that two subgraphs can be connected by a new dependency
1300 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1303 static inline int usage_match(struct lock_list *entry, void *bit)
1305 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1311 * Find a node in the forwards-direction dependency sub-graph starting
1312 * at @root->class that matches @bit.
1314 * Return 0 if such a node exists in the subgraph, and put that node
1315 * into *@target_entry.
1317 * Return 1 otherwise and keep *@target_entry unchanged.
1318 * Return <0 on error.
1321 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1322 struct lock_list **target_entry)
1326 debug_atomic_inc(nr_find_usage_forwards_checks);
1328 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1334 * Find a node in the backwards-direction dependency sub-graph starting
1335 * at @root->class that matches @bit.
1337 * Return 0 if such a node exists in the subgraph, and put that node
1338 * into *@target_entry.
1340 * Return 1 otherwise and keep *@target_entry unchanged.
1341 * Return <0 on error.
1344 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1345 struct lock_list **target_entry)
1349 debug_atomic_inc(nr_find_usage_backwards_checks);
1351 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1356 static void print_lock_class_header(struct lock_class *class, int depth)
1360 printk("%*s->", depth, "");
1361 print_lock_name(class);
1362 printk(" ops: %lu", class->ops);
1365 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1366 if (class->usage_mask & (1 << bit)) {
1369 len += printk("%*s %s", depth, "", usage_str[bit]);
1370 len += printk(" at:\n");
1371 print_stack_trace(class->usage_traces + bit, len);
1374 printk("%*s }\n", depth, "");
1376 printk("%*s ... key at: ",depth,"");
1377 print_ip_sym((unsigned long)class->key);
1381 * printk the shortest lock dependencies from @start to @end in reverse order:
1384 print_shortest_lock_dependencies(struct lock_list *leaf,
1385 struct lock_list *root)
1387 struct lock_list *entry = leaf;
1390 /*compute depth from generated tree by BFS*/
1391 depth = get_lock_depth(leaf);
1394 print_lock_class_header(entry->class, depth);
1395 printk("%*s ... acquired at:\n", depth, "");
1396 print_stack_trace(&entry->trace, 2);
1399 if (depth == 0 && (entry != root)) {
1400 printk("lockdep:%s bad path found in chain graph\n", __func__);
1404 entry = get_lock_parent(entry);
1406 } while (entry && (depth >= 0));
1412 print_irq_lock_scenario(struct lock_list *safe_entry,
1413 struct lock_list *unsafe_entry,
1414 struct lock_class *prev_class,
1415 struct lock_class *next_class)
1417 struct lock_class *safe_class = safe_entry->class;
1418 struct lock_class *unsafe_class = unsafe_entry->class;
1419 struct lock_class *middle_class = prev_class;
1421 if (middle_class == safe_class)
1422 middle_class = next_class;
1425 * A direct locking problem where unsafe_class lock is taken
1426 * directly by safe_class lock, then all we need to show
1427 * is the deadlock scenario, as it is obvious that the
1428 * unsafe lock is taken under the safe lock.
1430 * But if there is a chain instead, where the safe lock takes
1431 * an intermediate lock (middle_class) where this lock is
1432 * not the same as the safe lock, then the lock chain is
1433 * used to describe the problem. Otherwise we would need
1434 * to show a different CPU case for each link in the chain
1435 * from the safe_class lock to the unsafe_class lock.
1437 if (middle_class != unsafe_class) {
1438 printk("Chain exists of:\n ");
1439 __print_lock_name(safe_class);
1441 __print_lock_name(middle_class);
1443 __print_lock_name(unsafe_class);
1447 printk(" Possible interrupt unsafe locking scenario:\n\n");
1448 printk(" CPU0 CPU1\n");
1449 printk(" ---- ----\n");
1451 __print_lock_name(unsafe_class);
1453 printk(" local_irq_disable();\n");
1455 __print_lock_name(safe_class);
1458 __print_lock_name(middle_class);
1460 printk(" <Interrupt>\n");
1462 __print_lock_name(safe_class);
1464 printk("\n *** DEADLOCK ***\n\n");
1468 print_bad_irq_dependency(struct task_struct *curr,
1469 struct lock_list *prev_root,
1470 struct lock_list *next_root,
1471 struct lock_list *backwards_entry,
1472 struct lock_list *forwards_entry,
1473 struct held_lock *prev,
1474 struct held_lock *next,
1475 enum lock_usage_bit bit1,
1476 enum lock_usage_bit bit2,
1477 const char *irqclass)
1479 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1483 printk("======================================================\n");
1484 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1485 irqclass, irqclass);
1486 print_kernel_version();
1487 printk("------------------------------------------------------\n");
1488 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1489 curr->comm, task_pid_nr(curr),
1490 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1491 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1492 curr->hardirqs_enabled,
1493 curr->softirqs_enabled);
1496 printk("\nand this task is already holding:\n");
1498 printk("which would create a new lock dependency:\n");
1499 print_lock_name(hlock_class(prev));
1501 print_lock_name(hlock_class(next));
1504 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1506 print_lock_name(backwards_entry->class);
1507 printk("\n... which became %s-irq-safe at:\n", irqclass);
1509 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1511 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1512 print_lock_name(forwards_entry->class);
1513 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1516 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1518 printk("\nother info that might help us debug this:\n\n");
1519 print_irq_lock_scenario(backwards_entry, forwards_entry,
1520 hlock_class(prev), hlock_class(next));
1522 lockdep_print_held_locks(curr);
1524 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1525 printk(" and the holding lock:\n");
1526 if (!save_trace(&prev_root->trace))
1528 print_shortest_lock_dependencies(backwards_entry, prev_root);
1530 printk("\nthe dependencies between the lock to be acquired");
1531 printk(" and %s-irq-unsafe lock:\n", irqclass);
1532 if (!save_trace(&next_root->trace))
1534 print_shortest_lock_dependencies(forwards_entry, next_root);
1536 printk("\nstack backtrace:\n");
1543 check_usage(struct task_struct *curr, struct held_lock *prev,
1544 struct held_lock *next, enum lock_usage_bit bit_backwards,
1545 enum lock_usage_bit bit_forwards, const char *irqclass)
1548 struct lock_list this, that;
1549 struct lock_list *uninitialized_var(target_entry);
1550 struct lock_list *uninitialized_var(target_entry1);
1554 this.class = hlock_class(prev);
1555 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1557 return print_bfs_bug(ret);
1562 that.class = hlock_class(next);
1563 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1565 return print_bfs_bug(ret);
1569 return print_bad_irq_dependency(curr, &this, &that,
1570 target_entry, target_entry1,
1572 bit_backwards, bit_forwards, irqclass);
1575 static const char *state_names[] = {
1576 #define LOCKDEP_STATE(__STATE) \
1577 __stringify(__STATE),
1578 #include "lockdep_states.h"
1579 #undef LOCKDEP_STATE
1582 static const char *state_rnames[] = {
1583 #define LOCKDEP_STATE(__STATE) \
1584 __stringify(__STATE)"-READ",
1585 #include "lockdep_states.h"
1586 #undef LOCKDEP_STATE
1589 static inline const char *state_name(enum lock_usage_bit bit)
1591 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1594 static int exclusive_bit(int new_bit)
1602 * bit 0 - write/read
1603 * bit 1 - used_in/enabled
1607 int state = new_bit & ~3;
1608 int dir = new_bit & 2;
1611 * keep state, bit flip the direction and strip read.
1613 return state | (dir ^ 2);
1616 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1617 struct held_lock *next, enum lock_usage_bit bit)
1620 * Prove that the new dependency does not connect a hardirq-safe
1621 * lock with a hardirq-unsafe lock - to achieve this we search
1622 * the backwards-subgraph starting at <prev>, and the
1623 * forwards-subgraph starting at <next>:
1625 if (!check_usage(curr, prev, next, bit,
1626 exclusive_bit(bit), state_name(bit)))
1632 * Prove that the new dependency does not connect a hardirq-safe-read
1633 * lock with a hardirq-unsafe lock - to achieve this we search
1634 * the backwards-subgraph starting at <prev>, and the
1635 * forwards-subgraph starting at <next>:
1637 if (!check_usage(curr, prev, next, bit,
1638 exclusive_bit(bit), state_name(bit)))
1645 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1646 struct held_lock *next)
1648 #define LOCKDEP_STATE(__STATE) \
1649 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1651 #include "lockdep_states.h"
1652 #undef LOCKDEP_STATE
1657 static void inc_chains(void)
1659 if (current->hardirq_context)
1660 nr_hardirq_chains++;
1662 if (current->softirq_context)
1663 nr_softirq_chains++;
1665 nr_process_chains++;
1672 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1673 struct held_lock *next)
1678 static inline void inc_chains(void)
1680 nr_process_chains++;
1686 print_deadlock_scenario(struct held_lock *nxt,
1687 struct held_lock *prv)
1689 struct lock_class *next = hlock_class(nxt);
1690 struct lock_class *prev = hlock_class(prv);
1692 printk(" Possible unsafe locking scenario:\n\n");
1696 __print_lock_name(prev);
1699 __print_lock_name(next);
1701 printk("\n *** DEADLOCK ***\n\n");
1702 printk(" May be due to missing lock nesting notation\n\n");
1706 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1707 struct held_lock *next)
1709 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1713 printk("=============================================\n");
1714 printk("[ INFO: possible recursive locking detected ]\n");
1715 print_kernel_version();
1716 printk("---------------------------------------------\n");
1717 printk("%s/%d is trying to acquire lock:\n",
1718 curr->comm, task_pid_nr(curr));
1720 printk("\nbut task is already holding lock:\n");
1723 printk("\nother info that might help us debug this:\n");
1724 print_deadlock_scenario(next, prev);
1725 lockdep_print_held_locks(curr);
1727 printk("\nstack backtrace:\n");
1734 * Check whether we are holding such a class already.
1736 * (Note that this has to be done separately, because the graph cannot
1737 * detect such classes of deadlocks.)
1739 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1742 check_deadlock(struct task_struct *curr, struct held_lock *next,
1743 struct lockdep_map *next_instance, int read)
1745 struct held_lock *prev;
1746 struct held_lock *nest = NULL;
1749 for (i = 0; i < curr->lockdep_depth; i++) {
1750 prev = curr->held_locks + i;
1752 if (prev->instance == next->nest_lock)
1755 if (hlock_class(prev) != hlock_class(next))
1759 * Allow read-after-read recursion of the same
1760 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1762 if ((read == 2) && prev->read)
1766 * We're holding the nest_lock, which serializes this lock's
1767 * nesting behaviour.
1772 return print_deadlock_bug(curr, prev, next);
1778 * There was a chain-cache miss, and we are about to add a new dependency
1779 * to a previous lock. We recursively validate the following rules:
1781 * - would the adding of the <prev> -> <next> dependency create a
1782 * circular dependency in the graph? [== circular deadlock]
1784 * - does the new prev->next dependency connect any hardirq-safe lock
1785 * (in the full backwards-subgraph starting at <prev>) with any
1786 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1787 * <next>)? [== illegal lock inversion with hardirq contexts]
1789 * - does the new prev->next dependency connect any softirq-safe lock
1790 * (in the full backwards-subgraph starting at <prev>) with any
1791 * softirq-unsafe lock (in the full forwards-subgraph starting at
1792 * <next>)? [== illegal lock inversion with softirq contexts]
1794 * any of these scenarios could lead to a deadlock.
1796 * Then if all the validations pass, we add the forwards and backwards
1800 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1801 struct held_lock *next, int distance, int trylock_loop)
1803 struct lock_list *entry;
1805 struct lock_list this;
1806 struct lock_list *uninitialized_var(target_entry);
1808 * Static variable, serialized by the graph_lock().
1810 * We use this static variable to save the stack trace in case
1811 * we call into this function multiple times due to encountering
1812 * trylocks in the held lock stack.
1814 static struct stack_trace trace;
1817 * Prove that the new <prev> -> <next> dependency would not
1818 * create a circular dependency in the graph. (We do this by
1819 * forward-recursing into the graph starting at <next>, and
1820 * checking whether we can reach <prev>.)
1822 * We are using global variables to control the recursion, to
1823 * keep the stackframe size of the recursive functions low:
1825 this.class = hlock_class(next);
1827 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1829 return print_circular_bug(&this, target_entry, next, prev);
1830 else if (unlikely(ret < 0))
1831 return print_bfs_bug(ret);
1833 if (!check_prev_add_irq(curr, prev, next))
1837 * For recursive read-locks we do all the dependency checks,
1838 * but we dont store read-triggered dependencies (only
1839 * write-triggered dependencies). This ensures that only the
1840 * write-side dependencies matter, and that if for example a
1841 * write-lock never takes any other locks, then the reads are
1842 * equivalent to a NOP.
1844 if (next->read == 2 || prev->read == 2)
1847 * Is the <prev> -> <next> dependency already present?
1849 * (this may occur even though this is a new chain: consider
1850 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1851 * chains - the second one will be new, but L1 already has
1852 * L2 added to its dependency list, due to the first chain.)
1854 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1855 if (entry->class == hlock_class(next)) {
1857 entry->distance = 1;
1862 if (!trylock_loop && !save_trace(&trace))
1866 * Ok, all validations passed, add the new lock
1867 * to the previous lock's dependency list:
1869 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1870 &hlock_class(prev)->locks_after,
1871 next->acquire_ip, distance, &trace);
1876 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1877 &hlock_class(next)->locks_before,
1878 next->acquire_ip, distance, &trace);
1883 * Debugging printouts:
1885 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1887 printk("\n new dependency: ");
1888 print_lock_name(hlock_class(prev));
1890 print_lock_name(hlock_class(next));
1893 return graph_lock();
1899 * Add the dependency to all directly-previous locks that are 'relevant'.
1900 * The ones that are relevant are (in increasing distance from curr):
1901 * all consecutive trylock entries and the final non-trylock entry - or
1902 * the end of this context's lock-chain - whichever comes first.
1905 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1907 int depth = curr->lockdep_depth;
1908 int trylock_loop = 0;
1909 struct held_lock *hlock;
1914 * Depth must not be zero for a non-head lock:
1919 * At least two relevant locks must exist for this
1922 if (curr->held_locks[depth].irq_context !=
1923 curr->held_locks[depth-1].irq_context)
1927 int distance = curr->lockdep_depth - depth + 1;
1928 hlock = curr->held_locks + depth-1;
1930 * Only non-recursive-read entries get new dependencies
1933 if (hlock->read != 2) {
1934 if (!check_prev_add(curr, hlock, next,
1935 distance, trylock_loop))
1938 * Stop after the first non-trylock entry,
1939 * as non-trylock entries have added their
1940 * own direct dependencies already, so this
1941 * lock is connected to them indirectly:
1943 if (!hlock->trylock)
1948 * End of lock-stack?
1953 * Stop the search if we cross into another context:
1955 if (curr->held_locks[depth].irq_context !=
1956 curr->held_locks[depth-1].irq_context)
1962 if (!debug_locks_off_graph_unlock())
1966 * Clearly we all shouldn't be here, but since we made it we
1967 * can reliable say we messed up our state. See the above two
1968 * gotos for reasons why we could possibly end up here.
1975 unsigned long nr_lock_chains;
1976 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1977 int nr_chain_hlocks;
1978 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1980 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1982 return lock_classes + chain_hlocks[chain->base + i];
1986 * Look up a dependency chain. If the key is not present yet then
1987 * add it and return 1 - in this case the new dependency chain is
1988 * validated. If the key is already hashed, return 0.
1989 * (On return with 1 graph_lock is held.)
1991 static inline int lookup_chain_cache(struct task_struct *curr,
1992 struct held_lock *hlock,
1995 struct lock_class *class = hlock_class(hlock);
1996 struct list_head *hash_head = chainhashentry(chain_key);
1997 struct lock_chain *chain;
1998 struct held_lock *hlock_curr, *hlock_next;
2002 * We might need to take the graph lock, ensure we've got IRQs
2003 * disabled to make this an IRQ-safe lock.. for recursion reasons
2004 * lockdep won't complain about its own locking errors.
2006 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2009 * We can walk it lock-free, because entries only get added
2012 list_for_each_entry(chain, hash_head, entry) {
2013 if (chain->chain_key == chain_key) {
2015 debug_atomic_inc(chain_lookup_hits);
2016 if (very_verbose(class))
2017 printk("\nhash chain already cached, key: "
2018 "%016Lx tail class: [%p] %s\n",
2019 (unsigned long long)chain_key,
2020 class->key, class->name);
2024 if (very_verbose(class))
2025 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2026 (unsigned long long)chain_key, class->key, class->name);
2028 * Allocate a new chain entry from the static array, and add
2034 * We have to walk the chain again locked - to avoid duplicates:
2036 list_for_each_entry(chain, hash_head, entry) {
2037 if (chain->chain_key == chain_key) {
2042 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2043 if (!debug_locks_off_graph_unlock())
2046 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2047 printk("turning off the locking correctness validator.\n");
2051 chain = lock_chains + nr_lock_chains++;
2052 chain->chain_key = chain_key;
2053 chain->irq_context = hlock->irq_context;
2054 /* Find the first held_lock of current chain */
2056 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2057 hlock_curr = curr->held_locks + i;
2058 if (hlock_curr->irq_context != hlock_next->irq_context)
2063 chain->depth = curr->lockdep_depth + 1 - i;
2064 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2065 chain->base = nr_chain_hlocks;
2066 nr_chain_hlocks += chain->depth;
2067 for (j = 0; j < chain->depth - 1; j++, i++) {
2068 int lock_id = curr->held_locks[i].class_idx - 1;
2069 chain_hlocks[chain->base + j] = lock_id;
2071 chain_hlocks[chain->base + j] = class - lock_classes;
2073 list_add_tail_rcu(&chain->entry, hash_head);
2074 debug_atomic_inc(chain_lookup_misses);
2080 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2081 struct held_lock *hlock, int chain_head, u64 chain_key)
2084 * Trylock needs to maintain the stack of held locks, but it
2085 * does not add new dependencies, because trylock can be done
2088 * We look up the chain_key and do the O(N^2) check and update of
2089 * the dependencies only if this is a new dependency chain.
2090 * (If lookup_chain_cache() returns with 1 it acquires
2091 * graph_lock for us)
2093 if (!hlock->trylock && (hlock->check == 2) &&
2094 lookup_chain_cache(curr, hlock, chain_key)) {
2096 * Check whether last held lock:
2098 * - is irq-safe, if this lock is irq-unsafe
2099 * - is softirq-safe, if this lock is hardirq-unsafe
2101 * And check whether the new lock's dependency graph
2102 * could lead back to the previous lock.
2104 * any of these scenarios could lead to a deadlock. If
2107 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2112 * Mark recursive read, as we jump over it when
2113 * building dependencies (just like we jump over
2119 * Add dependency only if this lock is not the head
2120 * of the chain, and if it's not a secondary read-lock:
2122 if (!chain_head && ret != 2)
2123 if (!check_prevs_add(curr, hlock))
2127 /* after lookup_chain_cache(): */
2128 if (unlikely(!debug_locks))
2134 static inline int validate_chain(struct task_struct *curr,
2135 struct lockdep_map *lock, struct held_lock *hlock,
2136 int chain_head, u64 chain_key)
2143 * We are building curr_chain_key incrementally, so double-check
2144 * it from scratch, to make sure that it's done correctly:
2146 static void check_chain_key(struct task_struct *curr)
2148 #ifdef CONFIG_DEBUG_LOCKDEP
2149 struct held_lock *hlock, *prev_hlock = NULL;
2153 for (i = 0; i < curr->lockdep_depth; i++) {
2154 hlock = curr->held_locks + i;
2155 if (chain_key != hlock->prev_chain_key) {
2158 * We got mighty confused, our chain keys don't match
2159 * with what we expect, someone trample on our task state?
2161 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2162 curr->lockdep_depth, i,
2163 (unsigned long long)chain_key,
2164 (unsigned long long)hlock->prev_chain_key);
2167 id = hlock->class_idx - 1;
2169 * Whoops ran out of static storage again?
2171 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2174 if (prev_hlock && (prev_hlock->irq_context !=
2175 hlock->irq_context))
2177 chain_key = iterate_chain_key(chain_key, id);
2180 if (chain_key != curr->curr_chain_key) {
2183 * More smoking hash instead of calculating it, damn see these
2184 * numbers float.. I bet that a pink elephant stepped on my memory.
2186 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2187 curr->lockdep_depth, i,
2188 (unsigned long long)chain_key,
2189 (unsigned long long)curr->curr_chain_key);
2195 print_usage_bug_scenario(struct held_lock *lock)
2197 struct lock_class *class = hlock_class(lock);
2199 printk(" Possible unsafe locking scenario:\n\n");
2203 __print_lock_name(class);
2205 printk(" <Interrupt>\n");
2207 __print_lock_name(class);
2209 printk("\n *** DEADLOCK ***\n\n");
2213 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2214 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2216 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2220 printk("=================================\n");
2221 printk("[ INFO: inconsistent lock state ]\n");
2222 print_kernel_version();
2223 printk("---------------------------------\n");
2225 printk("inconsistent {%s} -> {%s} usage.\n",
2226 usage_str[prev_bit], usage_str[new_bit]);
2228 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2229 curr->comm, task_pid_nr(curr),
2230 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2231 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2232 trace_hardirqs_enabled(curr),
2233 trace_softirqs_enabled(curr));
2236 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2237 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2239 print_irqtrace_events(curr);
2240 printk("\nother info that might help us debug this:\n");
2241 print_usage_bug_scenario(this);
2243 lockdep_print_held_locks(curr);
2245 printk("\nstack backtrace:\n");
2252 * Print out an error if an invalid bit is set:
2255 valid_state(struct task_struct *curr, struct held_lock *this,
2256 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2258 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2259 return print_usage_bug(curr, this, bad_bit, new_bit);
2263 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2264 enum lock_usage_bit new_bit);
2266 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2269 * print irq inversion bug:
2272 print_irq_inversion_bug(struct task_struct *curr,
2273 struct lock_list *root, struct lock_list *other,
2274 struct held_lock *this, int forwards,
2275 const char *irqclass)
2277 struct lock_list *entry = other;
2278 struct lock_list *middle = NULL;
2281 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2285 printk("=========================================================\n");
2286 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2287 print_kernel_version();
2288 printk("---------------------------------------------------------\n");
2289 printk("%s/%d just changed the state of lock:\n",
2290 curr->comm, task_pid_nr(curr));
2293 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2295 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2296 print_lock_name(other->class);
2297 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2299 printk("\nother info that might help us debug this:\n");
2301 /* Find a middle lock (if one exists) */
2302 depth = get_lock_depth(other);
2304 if (depth == 0 && (entry != root)) {
2305 printk("lockdep:%s bad path found in chain graph\n", __func__);
2309 entry = get_lock_parent(entry);
2311 } while (entry && entry != root && (depth >= 0));
2313 print_irq_lock_scenario(root, other,
2314 middle ? middle->class : root->class, other->class);
2316 print_irq_lock_scenario(other, root,
2317 middle ? middle->class : other->class, root->class);
2319 lockdep_print_held_locks(curr);
2321 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2322 if (!save_trace(&root->trace))
2324 print_shortest_lock_dependencies(other, root);
2326 printk("\nstack backtrace:\n");
2333 * Prove that in the forwards-direction subgraph starting at <this>
2334 * there is no lock matching <mask>:
2337 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2338 enum lock_usage_bit bit, const char *irqclass)
2341 struct lock_list root;
2342 struct lock_list *uninitialized_var(target_entry);
2345 root.class = hlock_class(this);
2346 ret = find_usage_forwards(&root, bit, &target_entry);
2348 return print_bfs_bug(ret);
2352 return print_irq_inversion_bug(curr, &root, target_entry,
2357 * Prove that in the backwards-direction subgraph starting at <this>
2358 * there is no lock matching <mask>:
2361 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2362 enum lock_usage_bit bit, const char *irqclass)
2365 struct lock_list root;
2366 struct lock_list *uninitialized_var(target_entry);
2369 root.class = hlock_class(this);
2370 ret = find_usage_backwards(&root, bit, &target_entry);
2372 return print_bfs_bug(ret);
2376 return print_irq_inversion_bug(curr, &root, target_entry,
2380 void print_irqtrace_events(struct task_struct *curr)
2382 printk("irq event stamp: %u\n", curr->irq_events);
2383 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2384 print_ip_sym(curr->hardirq_enable_ip);
2385 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2386 print_ip_sym(curr->hardirq_disable_ip);
2387 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2388 print_ip_sym(curr->softirq_enable_ip);
2389 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2390 print_ip_sym(curr->softirq_disable_ip);
2393 static int HARDIRQ_verbose(struct lock_class *class)
2396 return class_filter(class);
2401 static int SOFTIRQ_verbose(struct lock_class *class)
2404 return class_filter(class);
2409 static int RECLAIM_FS_verbose(struct lock_class *class)
2412 return class_filter(class);
2417 #define STRICT_READ_CHECKS 1
2419 static int (*state_verbose_f[])(struct lock_class *class) = {
2420 #define LOCKDEP_STATE(__STATE) \
2422 #include "lockdep_states.h"
2423 #undef LOCKDEP_STATE
2426 static inline int state_verbose(enum lock_usage_bit bit,
2427 struct lock_class *class)
2429 return state_verbose_f[bit >> 2](class);
2432 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2433 enum lock_usage_bit bit, const char *name);
2436 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2437 enum lock_usage_bit new_bit)
2439 int excl_bit = exclusive_bit(new_bit);
2440 int read = new_bit & 1;
2441 int dir = new_bit & 2;
2444 * mark USED_IN has to look forwards -- to ensure no dependency
2445 * has ENABLED state, which would allow recursion deadlocks.
2447 * mark ENABLED has to look backwards -- to ensure no dependee
2448 * has USED_IN state, which, again, would allow recursion deadlocks.
2450 check_usage_f usage = dir ?
2451 check_usage_backwards : check_usage_forwards;
2454 * Validate that this particular lock does not have conflicting
2457 if (!valid_state(curr, this, new_bit, excl_bit))
2461 * Validate that the lock dependencies don't have conflicting usage
2464 if ((!read || !dir || STRICT_READ_CHECKS) &&
2465 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2469 * Check for read in write conflicts
2472 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2475 if (STRICT_READ_CHECKS &&
2476 !usage(curr, this, excl_bit + 1,
2477 state_name(new_bit + 1)))
2481 if (state_verbose(new_bit, hlock_class(this)))
2488 #define LOCKDEP_STATE(__STATE) __STATE,
2489 #include "lockdep_states.h"
2490 #undef LOCKDEP_STATE
2494 * Mark all held locks with a usage bit:
2497 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2499 enum lock_usage_bit usage_bit;
2500 struct held_lock *hlock;
2503 for (i = 0; i < curr->lockdep_depth; i++) {
2504 hlock = curr->held_locks + i;
2506 usage_bit = 2 + (mark << 2); /* ENABLED */
2508 usage_bit += 1; /* READ */
2510 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2512 if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
2515 if (!mark_lock(curr, hlock, usage_bit))
2523 * Hardirqs will be enabled:
2525 static void __trace_hardirqs_on_caller(unsigned long ip)
2527 struct task_struct *curr = current;
2529 /* we'll do an OFF -> ON transition: */
2530 curr->hardirqs_enabled = 1;
2533 * We are going to turn hardirqs on, so set the
2534 * usage bit for all held locks:
2536 if (!mark_held_locks(curr, HARDIRQ))
2539 * If we have softirqs enabled, then set the usage
2540 * bit for all held locks. (disabled hardirqs prevented
2541 * this bit from being set before)
2543 if (curr->softirqs_enabled)
2544 if (!mark_held_locks(curr, SOFTIRQ))
2547 curr->hardirq_enable_ip = ip;
2548 curr->hardirq_enable_event = ++curr->irq_events;
2549 debug_atomic_inc(hardirqs_on_events);
2552 void trace_hardirqs_on_caller(unsigned long ip)
2554 time_hardirqs_on(CALLER_ADDR0, ip);
2556 if (unlikely(!debug_locks || current->lockdep_recursion))
2559 if (unlikely(current->hardirqs_enabled)) {
2561 * Neither irq nor preemption are disabled here
2562 * so this is racy by nature but losing one hit
2563 * in a stat is not a big deal.
2565 __debug_atomic_inc(redundant_hardirqs_on);
2570 * We're enabling irqs and according to our state above irqs weren't
2571 * already enabled, yet we find the hardware thinks they are in fact
2572 * enabled.. someone messed up their IRQ state tracing.
2574 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2578 * See the fine text that goes along with this variable definition.
2580 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2584 * Can't allow enabling interrupts while in an interrupt handler,
2585 * that's general bad form and such. Recursion, limited stack etc..
2587 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2590 current->lockdep_recursion = 1;
2591 __trace_hardirqs_on_caller(ip);
2592 current->lockdep_recursion = 0;
2594 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2596 void trace_hardirqs_on(void)
2598 trace_hardirqs_on_caller(CALLER_ADDR0);
2600 EXPORT_SYMBOL(trace_hardirqs_on);
2603 * Hardirqs were disabled:
2605 void trace_hardirqs_off_caller(unsigned long ip)
2607 struct task_struct *curr = current;
2609 time_hardirqs_off(CALLER_ADDR0, ip);
2611 if (unlikely(!debug_locks || current->lockdep_recursion))
2615 * So we're supposed to get called after you mask local IRQs, but for
2616 * some reason the hardware doesn't quite think you did a proper job.
2618 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2621 if (curr->hardirqs_enabled) {
2623 * We have done an ON -> OFF transition:
2625 curr->hardirqs_enabled = 0;
2626 curr->hardirq_disable_ip = ip;
2627 curr->hardirq_disable_event = ++curr->irq_events;
2628 debug_atomic_inc(hardirqs_off_events);
2630 debug_atomic_inc(redundant_hardirqs_off);
2632 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2634 void trace_hardirqs_off(void)
2636 trace_hardirqs_off_caller(CALLER_ADDR0);
2638 EXPORT_SYMBOL(trace_hardirqs_off);
2641 * Softirqs will be enabled:
2643 void trace_softirqs_on(unsigned long ip)
2645 struct task_struct *curr = current;
2647 if (unlikely(!debug_locks || current->lockdep_recursion))
2651 * We fancy IRQs being disabled here, see softirq.c, avoids
2652 * funny state and nesting things.
2654 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2657 if (curr->softirqs_enabled) {
2658 debug_atomic_inc(redundant_softirqs_on);
2662 current->lockdep_recursion = 1;
2664 * We'll do an OFF -> ON transition:
2666 curr->softirqs_enabled = 1;
2667 curr->softirq_enable_ip = ip;
2668 curr->softirq_enable_event = ++curr->irq_events;
2669 debug_atomic_inc(softirqs_on_events);
2671 * We are going to turn softirqs on, so set the
2672 * usage bit for all held locks, if hardirqs are
2675 if (curr->hardirqs_enabled)
2676 mark_held_locks(curr, SOFTIRQ);
2677 current->lockdep_recursion = 0;
2681 * Softirqs were disabled:
2683 void trace_softirqs_off(unsigned long ip)
2685 struct task_struct *curr = current;
2687 if (unlikely(!debug_locks || current->lockdep_recursion))
2691 * We fancy IRQs being disabled here, see softirq.c
2693 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2696 if (curr->softirqs_enabled) {
2698 * We have done an ON -> OFF transition:
2700 curr->softirqs_enabled = 0;
2701 curr->softirq_disable_ip = ip;
2702 curr->softirq_disable_event = ++curr->irq_events;
2703 debug_atomic_inc(softirqs_off_events);
2705 * Whoops, we wanted softirqs off, so why aren't they?
2707 DEBUG_LOCKS_WARN_ON(!softirq_count());
2709 debug_atomic_inc(redundant_softirqs_off);
2712 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2714 struct task_struct *curr = current;
2716 if (unlikely(!debug_locks))
2719 /* no reclaim without waiting on it */
2720 if (!(gfp_mask & __GFP_WAIT))
2723 /* this guy won't enter reclaim */
2724 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2727 /* We're only interested __GFP_FS allocations for now */
2728 if (!(gfp_mask & __GFP_FS))
2732 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2734 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2737 mark_held_locks(curr, RECLAIM_FS);
2740 static void check_flags(unsigned long flags);
2742 void lockdep_trace_alloc(gfp_t gfp_mask)
2744 unsigned long flags;
2746 if (unlikely(current->lockdep_recursion))
2749 raw_local_irq_save(flags);
2751 current->lockdep_recursion = 1;
2752 __lockdep_trace_alloc(gfp_mask, flags);
2753 current->lockdep_recursion = 0;
2754 raw_local_irq_restore(flags);
2757 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2760 * If non-trylock use in a hardirq or softirq context, then
2761 * mark the lock as used in these contexts:
2763 if (!hlock->trylock) {
2765 if (curr->hardirq_context)
2766 if (!mark_lock(curr, hlock,
2767 LOCK_USED_IN_HARDIRQ_READ))
2769 if (curr->softirq_context)
2770 if (!mark_lock(curr, hlock,
2771 LOCK_USED_IN_SOFTIRQ_READ))
2774 if (curr->hardirq_context)
2775 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2777 if (curr->softirq_context)
2778 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2782 if (!hlock->hardirqs_off) {
2784 if (!mark_lock(curr, hlock,
2785 LOCK_ENABLED_HARDIRQ_READ))
2787 if (curr->softirqs_enabled)
2788 if (!mark_lock(curr, hlock,
2789 LOCK_ENABLED_SOFTIRQ_READ))
2792 if (!mark_lock(curr, hlock,
2793 LOCK_ENABLED_HARDIRQ))
2795 if (curr->softirqs_enabled)
2796 if (!mark_lock(curr, hlock,
2797 LOCK_ENABLED_SOFTIRQ))
2803 * We reuse the irq context infrastructure more broadly as a general
2804 * context checking code. This tests GFP_FS recursion (a lock taken
2805 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2808 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2810 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2813 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2821 static int separate_irq_context(struct task_struct *curr,
2822 struct held_lock *hlock)
2824 unsigned int depth = curr->lockdep_depth;
2827 * Keep track of points where we cross into an interrupt context:
2829 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2830 curr->softirq_context;
2832 struct held_lock *prev_hlock;
2834 prev_hlock = curr->held_locks + depth-1;
2836 * If we cross into another context, reset the
2837 * hash key (this also prevents the checking and the
2838 * adding of the dependency to 'prev'):
2840 if (prev_hlock->irq_context != hlock->irq_context)
2846 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2849 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2850 enum lock_usage_bit new_bit)
2852 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2856 static inline int mark_irqflags(struct task_struct *curr,
2857 struct held_lock *hlock)
2862 static inline int separate_irq_context(struct task_struct *curr,
2863 struct held_lock *hlock)
2868 void lockdep_trace_alloc(gfp_t gfp_mask)
2872 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2875 * Mark a lock with a usage bit, and validate the state transition:
2877 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2878 enum lock_usage_bit new_bit)
2880 unsigned int new_mask = 1 << new_bit, ret = 1;
2883 * If already set then do not dirty the cacheline,
2884 * nor do any checks:
2886 if (likely(hlock_class(this)->usage_mask & new_mask))
2892 * Make sure we didn't race:
2894 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2899 hlock_class(this)->usage_mask |= new_mask;
2901 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2905 #define LOCKDEP_STATE(__STATE) \
2906 case LOCK_USED_IN_##__STATE: \
2907 case LOCK_USED_IN_##__STATE##_READ: \
2908 case LOCK_ENABLED_##__STATE: \
2909 case LOCK_ENABLED_##__STATE##_READ:
2910 #include "lockdep_states.h"
2911 #undef LOCKDEP_STATE
2912 ret = mark_lock_irq(curr, this, new_bit);
2917 debug_atomic_dec(nr_unused_locks);
2920 if (!debug_locks_off_graph_unlock())
2929 * We must printk outside of the graph_lock:
2932 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2934 print_irqtrace_events(curr);
2942 * Initialize a lock instance's lock-class mapping info:
2944 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2945 struct lock_class_key *key, int subclass)
2947 memset(lock, 0, sizeof(*lock));
2949 #ifdef CONFIG_LOCK_STAT
2950 lock->cpu = raw_smp_processor_id();
2954 * Can't be having no nameless bastards around this place!
2956 if (DEBUG_LOCKS_WARN_ON(!name)) {
2957 lock->name = "NULL";
2964 * No key, no joy, we need to hash something.
2966 if (DEBUG_LOCKS_WARN_ON(!key))
2969 * Sanity check, the lock-class key must be persistent:
2971 if (!static_obj(key)) {
2972 printk("BUG: key %p not in .data!\n", key);
2974 * What it says above ^^^^^, I suggest you read it.
2976 DEBUG_LOCKS_WARN_ON(1);
2981 if (unlikely(!debug_locks))
2985 register_lock_class(lock, subclass, 1);
2987 EXPORT_SYMBOL_GPL(lockdep_init_map);
2989 struct lock_class_key __lockdep_no_validate__;
2992 * This gets called for every mutex_lock*()/spin_lock*() operation.
2993 * We maintain the dependency maps and validate the locking attempt:
2995 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2996 int trylock, int read, int check, int hardirqs_off,
2997 struct lockdep_map *nest_lock, unsigned long ip,
3000 struct task_struct *curr = current;
3001 struct lock_class *class = NULL;
3002 struct held_lock *hlock;
3003 unsigned int depth, id;
3011 if (unlikely(!debug_locks))
3015 * Lockdep should run with IRQs disabled, otherwise we could
3016 * get an interrupt which would want to take locks, which would
3017 * end up in lockdep and have you got a head-ache already?
3019 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3022 if (lock->key == &__lockdep_no_validate__)
3025 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3026 class = lock->class_cache[subclass];
3030 if (unlikely(!class)) {
3031 class = register_lock_class(lock, subclass, 0);
3035 atomic_inc((atomic_t *)&class->ops);
3036 if (very_verbose(class)) {
3037 printk("\nacquire class [%p] %s", class->key, class->name);
3038 if (class->name_version > 1)
3039 printk("#%d", class->name_version);
3045 * Add the lock to the list of currently held locks.
3046 * (we dont increase the depth just yet, up until the
3047 * dependency checks are done)
3049 depth = curr->lockdep_depth;
3051 * Ran out of static storage for our per-task lock stack again have we?
3053 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3056 class_idx = class - lock_classes + 1;
3059 hlock = curr->held_locks + depth - 1;
3060 if (hlock->class_idx == class_idx && nest_lock) {
3061 if (hlock->references)
3062 hlock->references++;
3064 hlock->references = 2;
3070 hlock = curr->held_locks + depth;
3072 * Plain impossible, we just registered it and checked it weren't no
3073 * NULL like.. I bet this mushroom I ate was good!
3075 if (DEBUG_LOCKS_WARN_ON(!class))
3077 hlock->class_idx = class_idx;
3078 hlock->acquire_ip = ip;
3079 hlock->instance = lock;
3080 hlock->nest_lock = nest_lock;
3081 hlock->trylock = trylock;
3083 hlock->check = check;
3084 hlock->hardirqs_off = !!hardirqs_off;
3085 hlock->references = references;
3086 #ifdef CONFIG_LOCK_STAT
3087 hlock->waittime_stamp = 0;
3088 hlock->holdtime_stamp = lockstat_clock();
3091 if (check == 2 && !mark_irqflags(curr, hlock))
3094 /* mark it as used: */
3095 if (!mark_lock(curr, hlock, LOCK_USED))
3099 * Calculate the chain hash: it's the combined hash of all the
3100 * lock keys along the dependency chain. We save the hash value
3101 * at every step so that we can get the current hash easily
3102 * after unlock. The chain hash is then used to cache dependency
3105 * The 'key ID' is what is the most compact key value to drive
3106 * the hash, not class->key.
3108 id = class - lock_classes;
3110 * Whoops, we did it again.. ran straight out of our static allocation.
3112 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3115 chain_key = curr->curr_chain_key;
3118 * How can we have a chain hash when we ain't got no keys?!
3120 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3125 hlock->prev_chain_key = chain_key;
3126 if (separate_irq_context(curr, hlock)) {
3130 chain_key = iterate_chain_key(chain_key, id);
3132 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3135 curr->curr_chain_key = chain_key;
3136 curr->lockdep_depth++;
3137 check_chain_key(curr);
3138 #ifdef CONFIG_DEBUG_LOCKDEP
3139 if (unlikely(!debug_locks))
3142 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3144 printk("BUG: MAX_LOCK_DEPTH too low!\n");
3145 printk("turning off the locking correctness validator.\n");
3150 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3151 max_lockdep_depth = curr->lockdep_depth;
3157 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3160 if (!debug_locks_off())
3162 if (debug_locks_silent)
3166 printk("=====================================\n");
3167 printk("[ BUG: bad unlock balance detected! ]\n");
3168 printk("-------------------------------------\n");
3169 printk("%s/%d is trying to release lock (",
3170 curr->comm, task_pid_nr(curr));
3171 print_lockdep_cache(lock);
3174 printk("but there are no more locks to release!\n");
3175 printk("\nother info that might help us debug this:\n");
3176 lockdep_print_held_locks(curr);
3178 printk("\nstack backtrace:\n");
3185 * Common debugging checks for both nested and non-nested unlock:
3187 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3190 if (unlikely(!debug_locks))
3193 * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
3195 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3198 if (curr->lockdep_depth <= 0)
3199 return print_unlock_inbalance_bug(curr, lock, ip);
3204 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3206 if (hlock->instance == lock)
3209 if (hlock->references) {
3210 struct lock_class *class = lock->class_cache[0];
3213 class = look_up_lock_class(lock, 0);
3216 * If look_up_lock_class() failed to find a class, we're trying
3217 * to test if we hold a lock that has never yet been acquired.
3218 * Clearly if the lock hasn't been acquired _ever_, we're not
3219 * holding it either, so report failure.
3225 * References, but not a lock we're actually ref-counting?
3226 * State got messed up, follow the sites that change ->references
3227 * and try to make sense of it.
3229 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3232 if (hlock->class_idx == class - lock_classes + 1)
3240 __lock_set_class(struct lockdep_map *lock, const char *name,
3241 struct lock_class_key *key, unsigned int subclass,
3244 struct task_struct *curr = current;
3245 struct held_lock *hlock, *prev_hlock;
3246 struct lock_class *class;
3250 depth = curr->lockdep_depth;
3252 * This function is about (re)setting the class of a held lock,
3253 * yet we're not actually holding any locks. Naughty user!
3255 if (DEBUG_LOCKS_WARN_ON(!depth))
3259 for (i = depth-1; i >= 0; i--) {
3260 hlock = curr->held_locks + i;
3262 * We must not cross into another context:
3264 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3266 if (match_held_lock(hlock, lock))
3270 return print_unlock_inbalance_bug(curr, lock, ip);
3273 lockdep_init_map(lock, name, key, 0);
3274 class = register_lock_class(lock, subclass, 0);
3275 hlock->class_idx = class - lock_classes + 1;
3277 curr->lockdep_depth = i;
3278 curr->curr_chain_key = hlock->prev_chain_key;
3280 for (; i < depth; i++) {
3281 hlock = curr->held_locks + i;
3282 if (!__lock_acquire(hlock->instance,
3283 hlock_class(hlock)->subclass, hlock->trylock,
3284 hlock->read, hlock->check, hlock->hardirqs_off,
3285 hlock->nest_lock, hlock->acquire_ip,
3291 * I took it apart and put it back together again, except now I have
3292 * these 'spare' parts.. where shall I put them.
3294 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3300 * Remove the lock to the list of currently held locks in a
3301 * potentially non-nested (out of order) manner. This is a
3302 * relatively rare operation, as all the unlock APIs default
3303 * to nested mode (which uses lock_release()):
3306 lock_release_non_nested(struct task_struct *curr,
3307 struct lockdep_map *lock, unsigned long ip)
3309 struct held_lock *hlock, *prev_hlock;
3314 * Check whether the lock exists in the current stack
3317 depth = curr->lockdep_depth;
3319 * So we're all set to release this lock.. wait what lock? We don't
3320 * own any locks, you've been drinking again?
3322 if (DEBUG_LOCKS_WARN_ON(!depth))
3326 for (i = depth-1; i >= 0; i--) {
3327 hlock = curr->held_locks + i;
3329 * We must not cross into another context:
3331 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3333 if (match_held_lock(hlock, lock))
3337 return print_unlock_inbalance_bug(curr, lock, ip);
3340 if (hlock->instance == lock)
3341 lock_release_holdtime(hlock);
3343 if (hlock->references) {
3344 hlock->references--;
3345 if (hlock->references) {
3347 * We had, and after removing one, still have
3348 * references, the current lock stack is still
3349 * valid. We're done!
3356 * We have the right lock to unlock, 'hlock' points to it.
3357 * Now we remove it from the stack, and add back the other
3358 * entries (if any), recalculating the hash along the way:
3361 curr->lockdep_depth = i;
3362 curr->curr_chain_key = hlock->prev_chain_key;
3364 for (i++; i < depth; i++) {
3365 hlock = curr->held_locks + i;
3366 if (!__lock_acquire(hlock->instance,
3367 hlock_class(hlock)->subclass, hlock->trylock,
3368 hlock->read, hlock->check, hlock->hardirqs_off,
3369 hlock->nest_lock, hlock->acquire_ip,
3375 * We had N bottles of beer on the wall, we drank one, but now
3376 * there's not N-1 bottles of beer left on the wall...
3378 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3384 * Remove the lock to the list of currently held locks - this gets
3385 * called on mutex_unlock()/spin_unlock*() (or on a failed
3386 * mutex_lock_interruptible()). This is done for unlocks that nest
3387 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3389 static int lock_release_nested(struct task_struct *curr,
3390 struct lockdep_map *lock, unsigned long ip)
3392 struct held_lock *hlock;
3396 * Pop off the top of the lock stack:
3398 depth = curr->lockdep_depth - 1;
3399 hlock = curr->held_locks + depth;
3402 * Is the unlock non-nested:
3404 if (hlock->instance != lock || hlock->references)
3405 return lock_release_non_nested(curr, lock, ip);
3406 curr->lockdep_depth--;
3409 * No more locks, but somehow we've got hash left over, who left it?
3411 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3414 curr->curr_chain_key = hlock->prev_chain_key;
3416 lock_release_holdtime(hlock);
3418 #ifdef CONFIG_DEBUG_LOCKDEP
3419 hlock->prev_chain_key = 0;
3420 hlock->class_idx = 0;
3421 hlock->acquire_ip = 0;
3422 hlock->irq_context = 0;
3428 * Remove the lock to the list of currently held locks - this gets
3429 * called on mutex_unlock()/spin_unlock*() (or on a failed
3430 * mutex_lock_interruptible()). This is done for unlocks that nest
3431 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3434 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3436 struct task_struct *curr = current;
3438 if (!check_unlock(curr, lock, ip))
3442 if (!lock_release_nested(curr, lock, ip))
3445 if (!lock_release_non_nested(curr, lock, ip))
3449 check_chain_key(curr);
3452 static int __lock_is_held(struct lockdep_map *lock)
3454 struct task_struct *curr = current;
3457 for (i = 0; i < curr->lockdep_depth; i++) {
3458 struct held_lock *hlock = curr->held_locks + i;
3460 if (match_held_lock(hlock, lock))
3468 * Check whether we follow the irq-flags state precisely:
3470 static void check_flags(unsigned long flags)
3472 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3473 defined(CONFIG_TRACE_IRQFLAGS)
3477 if (irqs_disabled_flags(flags)) {
3478 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3479 printk("possible reason: unannotated irqs-off.\n");
3482 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3483 printk("possible reason: unannotated irqs-on.\n");
3488 * We dont accurately track softirq state in e.g.
3489 * hardirq contexts (such as on 4KSTACKS), so only
3490 * check if not in hardirq contexts:
3492 if (!hardirq_count()) {
3493 if (softirq_count()) {
3494 /* like the above, but with softirqs */
3495 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3497 /* lick the above, does it taste good? */
3498 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3503 print_irqtrace_events(current);
3507 void lock_set_class(struct lockdep_map *lock, const char *name,
3508 struct lock_class_key *key, unsigned int subclass,
3511 unsigned long flags;
3513 if (unlikely(current->lockdep_recursion))
3516 raw_local_irq_save(flags);
3517 current->lockdep_recursion = 1;
3519 if (__lock_set_class(lock, name, key, subclass, ip))
3520 check_chain_key(current);
3521 current->lockdep_recursion = 0;
3522 raw_local_irq_restore(flags);
3524 EXPORT_SYMBOL_GPL(lock_set_class);
3527 * We are not always called with irqs disabled - do that here,
3528 * and also avoid lockdep recursion:
3530 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3531 int trylock, int read, int check,
3532 struct lockdep_map *nest_lock, unsigned long ip)
3534 unsigned long flags;
3536 if (unlikely(current->lockdep_recursion))
3539 raw_local_irq_save(flags);
3542 current->lockdep_recursion = 1;
3543 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3544 __lock_acquire(lock, subclass, trylock, read, check,
3545 irqs_disabled_flags(flags), nest_lock, ip, 0);
3546 current->lockdep_recursion = 0;
3547 raw_local_irq_restore(flags);
3549 EXPORT_SYMBOL_GPL(lock_acquire);
3551 void lock_release(struct lockdep_map *lock, int nested,
3554 unsigned long flags;
3556 if (unlikely(current->lockdep_recursion))
3559 raw_local_irq_save(flags);
3561 current->lockdep_recursion = 1;
3562 trace_lock_release(lock, ip);
3563 __lock_release(lock, nested, ip);
3564 current->lockdep_recursion = 0;
3565 raw_local_irq_restore(flags);
3567 EXPORT_SYMBOL_GPL(lock_release);
3569 int lock_is_held(struct lockdep_map *lock)
3571 unsigned long flags;
3574 if (unlikely(current->lockdep_recursion))
3575 return 1; /* avoid false negative lockdep_assert_held() */
3577 raw_local_irq_save(flags);
3580 current->lockdep_recursion = 1;
3581 ret = __lock_is_held(lock);
3582 current->lockdep_recursion = 0;
3583 raw_local_irq_restore(flags);
3587 EXPORT_SYMBOL_GPL(lock_is_held);
3589 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3591 current->lockdep_reclaim_gfp = gfp_mask;
3594 void lockdep_clear_current_reclaim_state(void)
3596 current->lockdep_reclaim_gfp = 0;
3599 #ifdef CONFIG_LOCK_STAT
3601 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3604 if (!debug_locks_off())
3606 if (debug_locks_silent)
3610 printk("=================================\n");
3611 printk("[ BUG: bad contention detected! ]\n");
3612 printk("---------------------------------\n");
3613 printk("%s/%d is trying to contend lock (",
3614 curr->comm, task_pid_nr(curr));
3615 print_lockdep_cache(lock);
3618 printk("but there are no locks held!\n");
3619 printk("\nother info that might help us debug this:\n");
3620 lockdep_print_held_locks(curr);
3622 printk("\nstack backtrace:\n");
3629 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3631 struct task_struct *curr = current;
3632 struct held_lock *hlock, *prev_hlock;
3633 struct lock_class_stats *stats;
3635 int i, contention_point, contending_point;
3637 depth = curr->lockdep_depth;
3639 * Whee, we contended on this lock, except it seems we're not
3640 * actually trying to acquire anything much at all..
3642 if (DEBUG_LOCKS_WARN_ON(!depth))
3646 for (i = depth-1; i >= 0; i--) {
3647 hlock = curr->held_locks + i;
3649 * We must not cross into another context:
3651 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3653 if (match_held_lock(hlock, lock))
3657 print_lock_contention_bug(curr, lock, ip);
3661 if (hlock->instance != lock)
3664 hlock->waittime_stamp = lockstat_clock();
3666 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3667 contending_point = lock_point(hlock_class(hlock)->contending_point,
3670 stats = get_lock_stats(hlock_class(hlock));
3671 if (contention_point < LOCKSTAT_POINTS)
3672 stats->contention_point[contention_point]++;
3673 if (contending_point < LOCKSTAT_POINTS)
3674 stats->contending_point[contending_point]++;
3675 if (lock->cpu != smp_processor_id())
3676 stats->bounces[bounce_contended + !!hlock->read]++;
3677 put_lock_stats(stats);
3681 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3683 struct task_struct *curr = current;
3684 struct held_lock *hlock, *prev_hlock;
3685 struct lock_class_stats *stats;
3687 u64 now, waittime = 0;
3690 depth = curr->lockdep_depth;
3692 * Yay, we acquired ownership of this lock we didn't try to
3693 * acquire, how the heck did that happen?
3695 if (DEBUG_LOCKS_WARN_ON(!depth))
3699 for (i = depth-1; i >= 0; i--) {
3700 hlock = curr->held_locks + i;
3702 * We must not cross into another context:
3704 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3706 if (match_held_lock(hlock, lock))
3710 print_lock_contention_bug(curr, lock, _RET_IP_);
3714 if (hlock->instance != lock)
3717 cpu = smp_processor_id();
3718 if (hlock->waittime_stamp) {
3719 now = lockstat_clock();
3720 waittime = now - hlock->waittime_stamp;
3721 hlock->holdtime_stamp = now;
3724 trace_lock_acquired(lock, ip);
3726 stats = get_lock_stats(hlock_class(hlock));
3729 lock_time_inc(&stats->read_waittime, waittime);
3731 lock_time_inc(&stats->write_waittime, waittime);
3733 if (lock->cpu != cpu)
3734 stats->bounces[bounce_acquired + !!hlock->read]++;
3735 put_lock_stats(stats);
3741 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3743 unsigned long flags;
3745 if (unlikely(!lock_stat))
3748 if (unlikely(current->lockdep_recursion))
3751 raw_local_irq_save(flags);
3753 current->lockdep_recursion = 1;
3754 trace_lock_contended(lock, ip);
3755 __lock_contended(lock, ip);
3756 current->lockdep_recursion = 0;
3757 raw_local_irq_restore(flags);
3759 EXPORT_SYMBOL_GPL(lock_contended);
3761 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3763 unsigned long flags;
3765 if (unlikely(!lock_stat))
3768 if (unlikely(current->lockdep_recursion))
3771 raw_local_irq_save(flags);
3773 current->lockdep_recursion = 1;
3774 __lock_acquired(lock, ip);
3775 current->lockdep_recursion = 0;
3776 raw_local_irq_restore(flags);
3778 EXPORT_SYMBOL_GPL(lock_acquired);
3782 * Used by the testsuite, sanitize the validator state
3783 * after a simulated failure:
3786 void lockdep_reset(void)
3788 unsigned long flags;
3791 raw_local_irq_save(flags);
3792 current->curr_chain_key = 0;
3793 current->lockdep_depth = 0;
3794 current->lockdep_recursion = 0;
3795 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3796 nr_hardirq_chains = 0;
3797 nr_softirq_chains = 0;
3798 nr_process_chains = 0;
3800 for (i = 0; i < CHAINHASH_SIZE; i++)
3801 INIT_LIST_HEAD(chainhash_table + i);
3802 raw_local_irq_restore(flags);
3805 static void zap_class(struct lock_class *class)
3810 * Remove all dependencies this lock is
3813 for (i = 0; i < nr_list_entries; i++) {
3814 if (list_entries[i].class == class)
3815 list_del_rcu(&list_entries[i].entry);
3818 * Unhash the class and remove it from the all_lock_classes list:
3820 list_del_rcu(&class->hash_entry);
3821 list_del_rcu(&class->lock_entry);
3826 static inline int within(const void *addr, void *start, unsigned long size)
3828 return addr >= start && addr < start + size;
3831 void lockdep_free_key_range(void *start, unsigned long size)
3833 struct lock_class *class, *next;
3834 struct list_head *head;
3835 unsigned long flags;
3839 raw_local_irq_save(flags);
3840 locked = graph_lock();
3843 * Unhash all classes that were created by this module:
3845 for (i = 0; i < CLASSHASH_SIZE; i++) {
3846 head = classhash_table + i;
3847 if (list_empty(head))
3849 list_for_each_entry_safe(class, next, head, hash_entry) {
3850 if (within(class->key, start, size))
3852 else if (within(class->name, start, size))
3859 raw_local_irq_restore(flags);
3862 void lockdep_reset_lock(struct lockdep_map *lock)
3864 struct lock_class *class, *next;
3865 struct list_head *head;
3866 unsigned long flags;
3870 raw_local_irq_save(flags);
3873 * Remove all classes this lock might have:
3875 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3877 * If the class exists we look it up and zap it:
3879 class = look_up_lock_class(lock, j);
3884 * Debug check: in the end all mapped classes should
3887 locked = graph_lock();
3888 for (i = 0; i < CLASSHASH_SIZE; i++) {
3889 head = classhash_table + i;
3890 if (list_empty(head))
3892 list_for_each_entry_safe(class, next, head, hash_entry) {
3895 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3896 match |= class == lock->class_cache[j];
3898 if (unlikely(match)) {
3899 if (debug_locks_off_graph_unlock()) {
3901 * We all just reset everything, how did it match?
3913 raw_local_irq_restore(flags);
3916 void lockdep_init(void)
3921 * Some architectures have their own start_kernel()
3922 * code which calls lockdep_init(), while we also
3923 * call lockdep_init() from the start_kernel() itself,
3924 * and we want to initialize the hashes only once:
3926 if (lockdep_initialized)
3929 for (i = 0; i < CLASSHASH_SIZE; i++)
3930 INIT_LIST_HEAD(classhash_table + i);
3932 for (i = 0; i < CHAINHASH_SIZE; i++)
3933 INIT_LIST_HEAD(chainhash_table + i);
3935 lockdep_initialized = 1;
3938 void __init lockdep_info(void)
3940 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3942 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3943 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3944 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3945 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3946 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3947 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3948 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3950 printk(" memory used by lock dependency info: %lu kB\n",
3951 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3952 sizeof(struct list_head) * CLASSHASH_SIZE +
3953 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3954 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3955 sizeof(struct list_head) * CHAINHASH_SIZE
3956 #ifdef CONFIG_PROVE_LOCKING
3957 + sizeof(struct circular_queue)
3962 printk(" per task-struct memory footprint: %lu bytes\n",
3963 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3965 #ifdef CONFIG_DEBUG_LOCKDEP
3966 if (lockdep_init_error) {
3967 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3968 printk("Call stack leading to lockdep invocation was:\n");
3969 print_stack_trace(&lockdep_init_trace, 0);
3975 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3976 const void *mem_to, struct held_lock *hlock)
3978 if (!debug_locks_off())
3980 if (debug_locks_silent)
3984 printk("=========================\n");
3985 printk("[ BUG: held lock freed! ]\n");
3986 printk("-------------------------\n");
3987 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3988 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3990 lockdep_print_held_locks(curr);
3992 printk("\nstack backtrace:\n");
3996 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3997 const void* lock_from, unsigned long lock_len)
3999 return lock_from + lock_len <= mem_from ||
4000 mem_from + mem_len <= lock_from;
4004 * Called when kernel memory is freed (or unmapped), or if a lock
4005 * is destroyed or reinitialized - this code checks whether there is
4006 * any held lock in the memory range of <from> to <to>:
4008 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4010 struct task_struct *curr = current;
4011 struct held_lock *hlock;
4012 unsigned long flags;
4015 if (unlikely(!debug_locks))
4018 local_irq_save(flags);
4019 for (i = 0; i < curr->lockdep_depth; i++) {
4020 hlock = curr->held_locks + i;
4022 if (not_in_range(mem_from, mem_len, hlock->instance,
4023 sizeof(*hlock->instance)))
4026 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4029 local_irq_restore(flags);
4031 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4033 static void print_held_locks_bug(struct task_struct *curr)
4035 if (!debug_locks_off())
4037 if (debug_locks_silent)
4041 printk("=====================================\n");
4042 printk("[ BUG: lock held at task exit time! ]\n");
4043 printk("-------------------------------------\n");
4044 printk("%s/%d is exiting with locks still held!\n",
4045 curr->comm, task_pid_nr(curr));
4046 lockdep_print_held_locks(curr);
4048 printk("\nstack backtrace:\n");
4052 void debug_check_no_locks_held(struct task_struct *task)
4054 if (unlikely(task->lockdep_depth > 0))
4055 print_held_locks_bug(task);
4058 void debug_show_all_locks(void)
4060 struct task_struct *g, *p;
4064 if (unlikely(!debug_locks)) {
4065 printk("INFO: lockdep is turned off.\n");
4068 printk("\nShowing all locks held in the system:\n");
4071 * Here we try to get the tasklist_lock as hard as possible,
4072 * if not successful after 2 seconds we ignore it (but keep
4073 * trying). This is to enable a debug printout even if a
4074 * tasklist_lock-holding task deadlocks or crashes.
4077 if (!read_trylock(&tasklist_lock)) {
4079 printk("hm, tasklist_lock locked, retrying... ");
4082 printk(" #%d", 10-count);
4086 printk(" ignoring it.\n");
4090 printk(KERN_CONT " locked it.\n");
4093 do_each_thread(g, p) {
4095 * It's not reliable to print a task's held locks
4096 * if it's not sleeping (or if it's not the current
4099 if (p->state == TASK_RUNNING && p != current)
4101 if (p->lockdep_depth)
4102 lockdep_print_held_locks(p);
4104 if (read_trylock(&tasklist_lock))
4106 } while_each_thread(g, p);
4109 printk("=============================================\n\n");
4112 read_unlock(&tasklist_lock);
4114 EXPORT_SYMBOL_GPL(debug_show_all_locks);
4117 * Careful: only use this function if you are sure that
4118 * the task cannot run in parallel!
4120 void debug_show_held_locks(struct task_struct *task)
4122 if (unlikely(!debug_locks)) {
4123 printk("INFO: lockdep is turned off.\n");
4126 lockdep_print_held_locks(task);
4128 EXPORT_SYMBOL_GPL(debug_show_held_locks);
4130 void lockdep_sys_exit(void)
4132 struct task_struct *curr = current;
4134 if (unlikely(curr->lockdep_depth)) {
4135 if (!debug_locks_off())
4138 printk("================================================\n");
4139 printk("[ BUG: lock held when returning to user space! ]\n");
4140 printk("------------------------------------------------\n");
4141 printk("%s/%d is leaving the kernel with locks still held!\n",
4142 curr->comm, curr->pid);
4143 lockdep_print_held_locks(curr);
4147 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4149 struct task_struct *curr = current;
4151 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4152 if (!debug_locks_off())
4154 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4155 /* Note: the following can be executed concurrently, so be careful. */
4157 printk("===============================\n");
4158 printk("[ INFO: suspicious RCU usage. ]\n");
4159 printk("-------------------------------\n");
4160 printk("%s:%d %s!\n", file, line, s);
4161 printk("\nother info that might help us debug this:\n\n");
4162 printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
4163 lockdep_print_held_locks(curr);
4164 printk("\nstack backtrace:\n");
4167 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);