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
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
47 #include <linux/kmemcheck.h>
49 #include <asm/sections.h>
51 #include "lockdep_internals.h"
53 #define CREATE_TRACE_POINTS
54 #include <trace/events/lock.h>
56 #ifdef CONFIG_PROVE_LOCKING
57 int prove_locking = 1;
58 module_param(prove_locking, int, 0644);
60 #define prove_locking 0
63 #ifdef CONFIG_LOCK_STAT
65 module_param(lock_stat, int, 0644);
71 * lockdep_lock: protects the lockdep graph, the hashes and the
72 * class/list/hash allocators.
74 * This is one of the rare exceptions where it's justified
75 * to use a raw spinlock - we really dont want the spinlock
76 * code to recurse back into the lockdep code...
78 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
80 static int graph_lock(void)
82 arch_spin_lock(&lockdep_lock);
84 * Make sure that if another CPU detected a bug while
85 * walking the graph we dont change it (while the other
86 * CPU is busy printing out stuff with the graph lock
90 arch_spin_unlock(&lockdep_lock);
93 /* prevent any recursions within lockdep from causing deadlocks */
94 current->lockdep_recursion++;
98 static inline int graph_unlock(void)
100 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
102 * The lockdep graph lock isn't locked while we expect it to
103 * be, we're confused now, bye!
105 return DEBUG_LOCKS_WARN_ON(1);
108 current->lockdep_recursion--;
109 arch_spin_unlock(&lockdep_lock);
114 * Turn lock debugging off and return with 0 if it was off already,
115 * and also release the graph lock:
117 static inline int debug_locks_off_graph_unlock(void)
119 int ret = debug_locks_off();
121 arch_spin_unlock(&lockdep_lock);
126 unsigned long nr_list_entries;
127 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
130 * All data structures here are protected by the global debug_lock.
132 * Mutex key structs only get allocated, once during bootup, and never
133 * get freed - this significantly simplifies the debugging code.
135 unsigned long nr_lock_classes;
136 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
138 static inline struct lock_class *hlock_class(struct held_lock *hlock)
140 if (!hlock->class_idx) {
142 * Someone passed in garbage, we give up.
144 DEBUG_LOCKS_WARN_ON(1);
147 return lock_classes + hlock->class_idx - 1;
150 #ifdef CONFIG_LOCK_STAT
151 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
154 static inline u64 lockstat_clock(void)
156 return local_clock();
159 static int lock_point(unsigned long points[], unsigned long ip)
163 for (i = 0; i < LOCKSTAT_POINTS; i++) {
164 if (points[i] == 0) {
175 static void lock_time_inc(struct lock_time *lt, u64 time)
180 if (time < lt->min || !lt->nr)
187 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
192 if (src->max > dst->max)
195 if (src->min < dst->min || !dst->nr)
198 dst->total += src->total;
202 struct lock_class_stats lock_stats(struct lock_class *class)
204 struct lock_class_stats stats;
207 memset(&stats, 0, sizeof(struct lock_class_stats));
208 for_each_possible_cpu(cpu) {
209 struct lock_class_stats *pcs =
210 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
212 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
213 stats.contention_point[i] += pcs->contention_point[i];
215 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
216 stats.contending_point[i] += pcs->contending_point[i];
218 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
219 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
221 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
222 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
224 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
225 stats.bounces[i] += pcs->bounces[i];
231 void clear_lock_stats(struct lock_class *class)
235 for_each_possible_cpu(cpu) {
236 struct lock_class_stats *cpu_stats =
237 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
239 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
241 memset(class->contention_point, 0, sizeof(class->contention_point));
242 memset(class->contending_point, 0, sizeof(class->contending_point));
245 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
247 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
250 static void put_lock_stats(struct lock_class_stats *stats)
252 put_cpu_var(cpu_lock_stats);
255 static void lock_release_holdtime(struct held_lock *hlock)
257 struct lock_class_stats *stats;
263 holdtime = lockstat_clock() - hlock->holdtime_stamp;
265 stats = get_lock_stats(hlock_class(hlock));
267 lock_time_inc(&stats->read_holdtime, holdtime);
269 lock_time_inc(&stats->write_holdtime, holdtime);
270 put_lock_stats(stats);
273 static inline void lock_release_holdtime(struct held_lock *hlock)
279 * We keep a global list of all lock classes. The list only grows,
280 * never shrinks. The list is only accessed with the lockdep
281 * spinlock lock held.
283 LIST_HEAD(all_lock_classes);
286 * The lockdep classes are in a hash-table as well, for fast lookup:
288 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
289 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
290 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
291 #define classhashentry(key) (classhash_table + __classhashfn((key)))
293 static struct hlist_head classhash_table[CLASSHASH_SIZE];
296 * We put the lock dependency chains into a hash-table as well, to cache
299 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
300 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
301 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
302 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
304 static struct hlist_head chainhash_table[CHAINHASH_SIZE];
307 * The hash key of the lock dependency chains is a hash itself too:
308 * it's a hash of all locks taken up to that lock, including that lock.
309 * It's a 64-bit hash, because it's important for the keys to be
312 #define iterate_chain_key(key1, key2) \
313 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
314 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
317 void lockdep_off(void)
319 current->lockdep_recursion++;
321 EXPORT_SYMBOL(lockdep_off);
323 void lockdep_on(void)
325 current->lockdep_recursion--;
327 EXPORT_SYMBOL(lockdep_on);
330 * Debugging switches:
334 #define VERY_VERBOSE 0
337 # define HARDIRQ_VERBOSE 1
338 # define SOFTIRQ_VERBOSE 1
339 # define RECLAIM_VERBOSE 1
341 # define HARDIRQ_VERBOSE 0
342 # define SOFTIRQ_VERBOSE 0
343 # define RECLAIM_VERBOSE 0
346 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
348 * Quick filtering for interesting events:
350 static int class_filter(struct lock_class *class)
354 if (class->name_version == 1 &&
355 !strcmp(class->name, "lockname"))
357 if (class->name_version == 1 &&
358 !strcmp(class->name, "&struct->lockfield"))
361 /* Filter everything else. 1 would be to allow everything else */
366 static int verbose(struct lock_class *class)
369 return class_filter(class);
375 * Stack-trace: tightly packed array of stack backtrace
376 * addresses. Protected by the graph_lock.
378 unsigned long nr_stack_trace_entries;
379 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
381 static void print_lockdep_off(const char *bug_msg)
383 printk(KERN_DEBUG "%s\n", bug_msg);
384 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
385 #ifdef CONFIG_LOCK_STAT
386 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
390 static int save_trace(struct stack_trace *trace)
392 trace->nr_entries = 0;
393 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
394 trace->entries = stack_trace + nr_stack_trace_entries;
398 save_stack_trace(trace);
401 * Some daft arches put -1 at the end to indicate its a full trace.
403 * <rant> this is buggy anyway, since it takes a whole extra entry so a
404 * complete trace that maxes out the entries provided will be reported
405 * as incomplete, friggin useless </rant>
407 if (trace->nr_entries != 0 &&
408 trace->entries[trace->nr_entries-1] == ULONG_MAX)
411 trace->max_entries = trace->nr_entries;
413 nr_stack_trace_entries += trace->nr_entries;
415 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
416 if (!debug_locks_off_graph_unlock())
419 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
428 unsigned int nr_hardirq_chains;
429 unsigned int nr_softirq_chains;
430 unsigned int nr_process_chains;
431 unsigned int max_lockdep_depth;
433 #ifdef CONFIG_DEBUG_LOCKDEP
435 * Various lockdep statistics:
437 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
444 #define __USAGE(__STATE) \
445 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
446 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
447 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
448 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
450 static const char *usage_str[] =
452 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
453 #include "lockdep_states.h"
455 [LOCK_USED] = "INITIAL USE",
458 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
460 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
463 static inline unsigned long lock_flag(enum lock_usage_bit bit)
468 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
472 if (class->usage_mask & lock_flag(bit + 2))
474 if (class->usage_mask & lock_flag(bit)) {
476 if (class->usage_mask & lock_flag(bit + 2))
483 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
487 #define LOCKDEP_STATE(__STATE) \
488 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
489 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
490 #include "lockdep_states.h"
496 static void __print_lock_name(struct lock_class *class)
498 char str[KSYM_NAME_LEN];
503 name = __get_key_name(class->key, str);
507 if (class->name_version > 1)
508 printk("#%d", class->name_version);
510 printk("/%d", class->subclass);
514 static void print_lock_name(struct lock_class *class)
516 char usage[LOCK_USAGE_CHARS];
518 get_usage_chars(class, usage);
521 __print_lock_name(class);
522 printk("){%s}", usage);
525 static void print_lockdep_cache(struct lockdep_map *lock)
528 char str[KSYM_NAME_LEN];
532 name = __get_key_name(lock->key->subkeys, str);
537 static void print_lock(struct held_lock *hlock)
540 * We can be called locklessly through debug_show_all_locks() so be
541 * extra careful, the hlock might have been released and cleared.
543 unsigned int class_idx = hlock->class_idx;
545 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
548 if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
549 printk("<RELEASED>\n");
553 print_lock_name(lock_classes + class_idx - 1);
555 print_ip_sym(hlock->acquire_ip);
558 static void lockdep_print_held_locks(struct task_struct *curr)
560 int i, depth = curr->lockdep_depth;
563 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
566 printk("%d lock%s held by %s/%d:\n",
567 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
569 for (i = 0; i < depth; i++) {
571 print_lock(curr->held_locks + i);
575 static void print_kernel_ident(void)
577 printk("%s %.*s %s\n", init_utsname()->release,
578 (int)strcspn(init_utsname()->version, " "),
579 init_utsname()->version,
583 static int very_verbose(struct lock_class *class)
586 return class_filter(class);
592 * Is this the address of a static object:
595 static int static_obj(void *obj)
597 unsigned long start = (unsigned long) &_stext,
598 end = (unsigned long) &_end,
599 addr = (unsigned long) obj;
604 if ((addr >= start) && (addr < end))
607 if (arch_is_kernel_data(addr))
611 * in-kernel percpu var?
613 if (is_kernel_percpu_address(addr))
617 * module static or percpu var?
619 return is_module_address(addr) || is_module_percpu_address(addr);
624 * To make lock name printouts unique, we calculate a unique
625 * class->name_version generation counter:
627 static int count_matching_names(struct lock_class *new_class)
629 struct lock_class *class;
632 if (!new_class->name)
635 list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
636 if (new_class->key - new_class->subclass == class->key)
637 return class->name_version;
638 if (class->name && !strcmp(class->name, new_class->name))
639 count = max(count, class->name_version);
646 * Register a lock's class in the hash-table, if the class is not present
647 * yet. Otherwise we look it up. We cache the result in the lock object
648 * itself, so actual lookup of the hash should be once per lock object.
650 static inline struct lock_class *
651 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
653 struct lockdep_subclass_key *key;
654 struct hlist_head *hash_head;
655 struct lock_class *class;
657 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
660 "BUG: looking up invalid subclass: %u\n", subclass);
662 "turning off the locking correctness validator.\n");
668 * Static locks do not have their class-keys yet - for them the key
669 * is the lock object itself:
671 if (unlikely(!lock->key))
672 lock->key = (void *)lock;
675 * NOTE: the class-key must be unique. For dynamic locks, a static
676 * lock_class_key variable is passed in through the mutex_init()
677 * (or spin_lock_init()) call - which acts as the key. For static
678 * locks we use the lock object itself as the key.
680 BUILD_BUG_ON(sizeof(struct lock_class_key) >
681 sizeof(struct lockdep_map));
683 key = lock->key->subkeys + subclass;
685 hash_head = classhashentry(key);
688 * We do an RCU walk of the hash, see lockdep_free_key_range().
690 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
693 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
694 if (class->key == key) {
696 * Huh! same key, different name? Did someone trample
697 * on some memory? We're most confused.
699 WARN_ON_ONCE(class->name != lock->name);
708 * Register a lock's class in the hash-table, if the class is not present
709 * yet. Otherwise we look it up. We cache the result in the lock object
710 * itself, so actual lookup of the hash should be once per lock object.
712 static inline struct lock_class *
713 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
715 struct lockdep_subclass_key *key;
716 struct hlist_head *hash_head;
717 struct lock_class *class;
719 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
721 class = look_up_lock_class(lock, subclass);
723 goto out_set_class_cache;
726 * Debug-check: all keys must be persistent!
728 if (!static_obj(lock->key)) {
730 printk("INFO: trying to register non-static key.\n");
731 printk("the code is fine but needs lockdep annotation.\n");
732 printk("turning off the locking correctness validator.\n");
738 key = lock->key->subkeys + subclass;
739 hash_head = classhashentry(key);
745 * We have to do the hash-walk again, to avoid races
748 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
749 if (class->key == key)
754 * Allocate a new key from the static array, and add it to
757 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
758 if (!debug_locks_off_graph_unlock()) {
762 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
766 class = lock_classes + nr_lock_classes++;
767 debug_atomic_inc(nr_unused_locks);
769 class->name = lock->name;
770 class->subclass = subclass;
771 INIT_LIST_HEAD(&class->lock_entry);
772 INIT_LIST_HEAD(&class->locks_before);
773 INIT_LIST_HEAD(&class->locks_after);
774 class->name_version = count_matching_names(class);
776 * We use RCU's safe list-add method to make
777 * parallel walking of the hash-list safe:
779 hlist_add_head_rcu(&class->hash_entry, hash_head);
781 * Add it to the global list of classes:
783 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
785 if (verbose(class)) {
788 printk("\nnew class %p: %s", class->key, class->name);
789 if (class->name_version > 1)
790 printk("#%d", class->name_version);
802 if (!subclass || force)
803 lock->class_cache[0] = class;
804 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
805 lock->class_cache[subclass] = class;
808 * Hash collision, did we smoke some? We found a class with a matching
809 * hash but the subclass -- which is hashed in -- didn't match.
811 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
817 #ifdef CONFIG_PROVE_LOCKING
819 * Allocate a lockdep entry. (assumes the graph_lock held, returns
820 * with NULL on failure)
822 static struct lock_list *alloc_list_entry(void)
824 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
825 if (!debug_locks_off_graph_unlock())
828 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
832 return list_entries + nr_list_entries++;
836 * Add a new dependency to the head of the list:
838 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
839 struct list_head *head, unsigned long ip,
840 int distance, struct stack_trace *trace)
842 struct lock_list *entry;
844 * Lock not present yet - get a new dependency struct and
845 * add it to the list:
847 entry = alloc_list_entry();
852 entry->distance = distance;
853 entry->trace = *trace;
855 * Both allocation and removal are done under the graph lock; but
856 * iteration is under RCU-sched; see look_up_lock_class() and
857 * lockdep_free_key_range().
859 list_add_tail_rcu(&entry->entry, head);
865 * For good efficiency of modular, we use power of 2
867 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
868 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
871 * The circular_queue and helpers is used to implement the
872 * breadth-first search(BFS)algorithem, by which we can build
873 * the shortest path from the next lock to be acquired to the
874 * previous held lock if there is a circular between them.
876 struct circular_queue {
877 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
878 unsigned int front, rear;
881 static struct circular_queue lock_cq;
883 unsigned int max_bfs_queue_depth;
885 static unsigned int lockdep_dependency_gen_id;
887 static inline void __cq_init(struct circular_queue *cq)
889 cq->front = cq->rear = 0;
890 lockdep_dependency_gen_id++;
893 static inline int __cq_empty(struct circular_queue *cq)
895 return (cq->front == cq->rear);
898 static inline int __cq_full(struct circular_queue *cq)
900 return ((cq->rear + 1) & CQ_MASK) == cq->front;
903 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
908 cq->element[cq->rear] = elem;
909 cq->rear = (cq->rear + 1) & CQ_MASK;
913 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
918 *elem = cq->element[cq->front];
919 cq->front = (cq->front + 1) & CQ_MASK;
923 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
925 return (cq->rear - cq->front) & CQ_MASK;
928 static inline void mark_lock_accessed(struct lock_list *lock,
929 struct lock_list *parent)
933 nr = lock - list_entries;
934 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
935 lock->parent = parent;
936 lock->class->dep_gen_id = lockdep_dependency_gen_id;
939 static inline unsigned long lock_accessed(struct lock_list *lock)
943 nr = lock - list_entries;
944 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
945 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
948 static inline struct lock_list *get_lock_parent(struct lock_list *child)
950 return child->parent;
953 static inline int get_lock_depth(struct lock_list *child)
956 struct lock_list *parent;
958 while ((parent = get_lock_parent(child))) {
965 static int __bfs(struct lock_list *source_entry,
967 int (*match)(struct lock_list *entry, void *data),
968 struct lock_list **target_entry,
971 struct lock_list *entry;
972 struct list_head *head;
973 struct circular_queue *cq = &lock_cq;
976 if (match(source_entry, data)) {
977 *target_entry = source_entry;
983 head = &source_entry->class->locks_after;
985 head = &source_entry->class->locks_before;
987 if (list_empty(head))
991 __cq_enqueue(cq, (unsigned long)source_entry);
993 while (!__cq_empty(cq)) {
994 struct lock_list *lock;
996 __cq_dequeue(cq, (unsigned long *)&lock);
1004 head = &lock->class->locks_after;
1006 head = &lock->class->locks_before;
1008 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1010 list_for_each_entry_rcu(entry, head, entry) {
1011 if (!lock_accessed(entry)) {
1012 unsigned int cq_depth;
1013 mark_lock_accessed(entry, lock);
1014 if (match(entry, data)) {
1015 *target_entry = entry;
1020 if (__cq_enqueue(cq, (unsigned long)entry)) {
1024 cq_depth = __cq_get_elem_count(cq);
1025 if (max_bfs_queue_depth < cq_depth)
1026 max_bfs_queue_depth = cq_depth;
1034 static inline int __bfs_forwards(struct lock_list *src_entry,
1036 int (*match)(struct lock_list *entry, void *data),
1037 struct lock_list **target_entry)
1039 return __bfs(src_entry, data, match, target_entry, 1);
1043 static inline int __bfs_backwards(struct lock_list *src_entry,
1045 int (*match)(struct lock_list *entry, void *data),
1046 struct lock_list **target_entry)
1048 return __bfs(src_entry, data, match, target_entry, 0);
1053 * Recursive, forwards-direction lock-dependency checking, used for
1054 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1059 * Print a dependency chain entry (this is only done when a deadlock
1060 * has been detected):
1063 print_circular_bug_entry(struct lock_list *target, int depth)
1065 if (debug_locks_silent)
1067 printk("\n-> #%u", depth);
1068 print_lock_name(target->class);
1070 print_stack_trace(&target->trace, 6);
1076 print_circular_lock_scenario(struct held_lock *src,
1077 struct held_lock *tgt,
1078 struct lock_list *prt)
1080 struct lock_class *source = hlock_class(src);
1081 struct lock_class *target = hlock_class(tgt);
1082 struct lock_class *parent = prt->class;
1085 * A direct locking problem where unsafe_class lock is taken
1086 * directly by safe_class lock, then all we need to show
1087 * is the deadlock scenario, as it is obvious that the
1088 * unsafe lock is taken under the safe lock.
1090 * But if there is a chain instead, where the safe lock takes
1091 * an intermediate lock (middle_class) where this lock is
1092 * not the same as the safe lock, then the lock chain is
1093 * used to describe the problem. Otherwise we would need
1094 * to show a different CPU case for each link in the chain
1095 * from the safe_class lock to the unsafe_class lock.
1097 if (parent != source) {
1098 printk("Chain exists of:\n ");
1099 __print_lock_name(source);
1101 __print_lock_name(parent);
1103 __print_lock_name(target);
1107 printk(" Possible unsafe locking scenario:\n\n");
1108 printk(" CPU0 CPU1\n");
1109 printk(" ---- ----\n");
1111 __print_lock_name(target);
1114 __print_lock_name(parent);
1117 __print_lock_name(target);
1120 __print_lock_name(source);
1122 printk("\n *** DEADLOCK ***\n\n");
1126 * When a circular dependency is detected, print the
1130 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1131 struct held_lock *check_src,
1132 struct held_lock *check_tgt)
1134 struct task_struct *curr = current;
1136 if (debug_locks_silent)
1140 printk("======================================================\n");
1141 printk("[ INFO: possible circular locking dependency detected ]\n");
1142 print_kernel_ident();
1143 printk("-------------------------------------------------------\n");
1144 printk("%s/%d is trying to acquire lock:\n",
1145 curr->comm, task_pid_nr(curr));
1146 print_lock(check_src);
1147 printk("\nbut task is already holding lock:\n");
1148 print_lock(check_tgt);
1149 printk("\nwhich lock already depends on the new lock.\n\n");
1150 printk("\nthe existing dependency chain (in reverse order) is:\n");
1152 print_circular_bug_entry(entry, depth);
1157 static inline int class_equal(struct lock_list *entry, void *data)
1159 return entry->class == data;
1162 static noinline int print_circular_bug(struct lock_list *this,
1163 struct lock_list *target,
1164 struct held_lock *check_src,
1165 struct held_lock *check_tgt)
1167 struct task_struct *curr = current;
1168 struct lock_list *parent;
1169 struct lock_list *first_parent;
1172 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1175 if (!save_trace(&this->trace))
1178 depth = get_lock_depth(target);
1180 print_circular_bug_header(target, depth, check_src, check_tgt);
1182 parent = get_lock_parent(target);
1183 first_parent = parent;
1186 print_circular_bug_entry(parent, --depth);
1187 parent = get_lock_parent(parent);
1190 printk("\nother info that might help us debug this:\n\n");
1191 print_circular_lock_scenario(check_src, check_tgt,
1194 lockdep_print_held_locks(curr);
1196 printk("\nstack backtrace:\n");
1202 static noinline int print_bfs_bug(int ret)
1204 if (!debug_locks_off_graph_unlock())
1208 * Breadth-first-search failed, graph got corrupted?
1210 WARN(1, "lockdep bfs error:%d\n", ret);
1215 static int noop_count(struct lock_list *entry, void *data)
1217 (*(unsigned long *)data)++;
1221 static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1223 unsigned long count = 0;
1224 struct lock_list *uninitialized_var(target_entry);
1226 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1230 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1232 unsigned long ret, flags;
1233 struct lock_list this;
1238 local_irq_save(flags);
1239 arch_spin_lock(&lockdep_lock);
1240 ret = __lockdep_count_forward_deps(&this);
1241 arch_spin_unlock(&lockdep_lock);
1242 local_irq_restore(flags);
1247 static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1249 unsigned long count = 0;
1250 struct lock_list *uninitialized_var(target_entry);
1252 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1257 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1259 unsigned long ret, flags;
1260 struct lock_list this;
1265 local_irq_save(flags);
1266 arch_spin_lock(&lockdep_lock);
1267 ret = __lockdep_count_backward_deps(&this);
1268 arch_spin_unlock(&lockdep_lock);
1269 local_irq_restore(flags);
1275 * Prove that the dependency graph starting at <entry> can not
1276 * lead to <target>. Print an error and return 0 if it does.
1279 check_noncircular(struct lock_list *root, struct lock_class *target,
1280 struct lock_list **target_entry)
1284 debug_atomic_inc(nr_cyclic_checks);
1286 result = __bfs_forwards(root, target, class_equal, target_entry);
1291 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1293 * Forwards and backwards subgraph searching, for the purposes of
1294 * proving that two subgraphs can be connected by a new dependency
1295 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1298 static inline int usage_match(struct lock_list *entry, void *bit)
1300 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1306 * Find a node in the forwards-direction dependency sub-graph starting
1307 * at @root->class that matches @bit.
1309 * Return 0 if such a node exists in the subgraph, and put that node
1310 * into *@target_entry.
1312 * Return 1 otherwise and keep *@target_entry unchanged.
1313 * Return <0 on error.
1316 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1317 struct lock_list **target_entry)
1321 debug_atomic_inc(nr_find_usage_forwards_checks);
1323 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1329 * Find a node in the backwards-direction dependency sub-graph starting
1330 * at @root->class that matches @bit.
1332 * Return 0 if such a node exists in the subgraph, and put that node
1333 * into *@target_entry.
1335 * Return 1 otherwise and keep *@target_entry unchanged.
1336 * Return <0 on error.
1339 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1340 struct lock_list **target_entry)
1344 debug_atomic_inc(nr_find_usage_backwards_checks);
1346 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1351 static void print_lock_class_header(struct lock_class *class, int depth)
1355 printk("%*s->", depth, "");
1356 print_lock_name(class);
1357 printk(" ops: %lu", class->ops);
1360 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1361 if (class->usage_mask & (1 << bit)) {
1364 len += printk("%*s %s", depth, "", usage_str[bit]);
1365 len += printk(" at:\n");
1366 print_stack_trace(class->usage_traces + bit, len);
1369 printk("%*s }\n", depth, "");
1371 printk("%*s ... key at: ",depth,"");
1372 print_ip_sym((unsigned long)class->key);
1376 * printk the shortest lock dependencies from @start to @end in reverse order:
1379 print_shortest_lock_dependencies(struct lock_list *leaf,
1380 struct lock_list *root)
1382 struct lock_list *entry = leaf;
1385 /*compute depth from generated tree by BFS*/
1386 depth = get_lock_depth(leaf);
1389 print_lock_class_header(entry->class, depth);
1390 printk("%*s ... acquired at:\n", depth, "");
1391 print_stack_trace(&entry->trace, 2);
1394 if (depth == 0 && (entry != root)) {
1395 printk("lockdep:%s bad path found in chain graph\n", __func__);
1399 entry = get_lock_parent(entry);
1401 } while (entry && (depth >= 0));
1407 print_irq_lock_scenario(struct lock_list *safe_entry,
1408 struct lock_list *unsafe_entry,
1409 struct lock_class *prev_class,
1410 struct lock_class *next_class)
1412 struct lock_class *safe_class = safe_entry->class;
1413 struct lock_class *unsafe_class = unsafe_entry->class;
1414 struct lock_class *middle_class = prev_class;
1416 if (middle_class == safe_class)
1417 middle_class = next_class;
1420 * A direct locking problem where unsafe_class lock is taken
1421 * directly by safe_class lock, then all we need to show
1422 * is the deadlock scenario, as it is obvious that the
1423 * unsafe lock is taken under the safe lock.
1425 * But if there is a chain instead, where the safe lock takes
1426 * an intermediate lock (middle_class) where this lock is
1427 * not the same as the safe lock, then the lock chain is
1428 * used to describe the problem. Otherwise we would need
1429 * to show a different CPU case for each link in the chain
1430 * from the safe_class lock to the unsafe_class lock.
1432 if (middle_class != unsafe_class) {
1433 printk("Chain exists of:\n ");
1434 __print_lock_name(safe_class);
1436 __print_lock_name(middle_class);
1438 __print_lock_name(unsafe_class);
1442 printk(" Possible interrupt unsafe locking scenario:\n\n");
1443 printk(" CPU0 CPU1\n");
1444 printk(" ---- ----\n");
1446 __print_lock_name(unsafe_class);
1448 printk(" local_irq_disable();\n");
1450 __print_lock_name(safe_class);
1453 __print_lock_name(middle_class);
1455 printk(" <Interrupt>\n");
1457 __print_lock_name(safe_class);
1459 printk("\n *** DEADLOCK ***\n\n");
1463 print_bad_irq_dependency(struct task_struct *curr,
1464 struct lock_list *prev_root,
1465 struct lock_list *next_root,
1466 struct lock_list *backwards_entry,
1467 struct lock_list *forwards_entry,
1468 struct held_lock *prev,
1469 struct held_lock *next,
1470 enum lock_usage_bit bit1,
1471 enum lock_usage_bit bit2,
1472 const char *irqclass)
1474 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1478 printk("======================================================\n");
1479 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1480 irqclass, irqclass);
1481 print_kernel_ident();
1482 printk("------------------------------------------------------\n");
1483 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1484 curr->comm, task_pid_nr(curr),
1485 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1486 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1487 curr->hardirqs_enabled,
1488 curr->softirqs_enabled);
1491 printk("\nand this task is already holding:\n");
1493 printk("which would create a new lock dependency:\n");
1494 print_lock_name(hlock_class(prev));
1496 print_lock_name(hlock_class(next));
1499 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1501 print_lock_name(backwards_entry->class);
1502 printk("\n... which became %s-irq-safe at:\n", irqclass);
1504 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1506 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1507 print_lock_name(forwards_entry->class);
1508 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1511 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1513 printk("\nother info that might help us debug this:\n\n");
1514 print_irq_lock_scenario(backwards_entry, forwards_entry,
1515 hlock_class(prev), hlock_class(next));
1517 lockdep_print_held_locks(curr);
1519 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1520 printk(" and the holding lock:\n");
1521 if (!save_trace(&prev_root->trace))
1523 print_shortest_lock_dependencies(backwards_entry, prev_root);
1525 printk("\nthe dependencies between the lock to be acquired");
1526 printk(" and %s-irq-unsafe lock:\n", irqclass);
1527 if (!save_trace(&next_root->trace))
1529 print_shortest_lock_dependencies(forwards_entry, next_root);
1531 printk("\nstack backtrace:\n");
1538 check_usage(struct task_struct *curr, struct held_lock *prev,
1539 struct held_lock *next, enum lock_usage_bit bit_backwards,
1540 enum lock_usage_bit bit_forwards, const char *irqclass)
1543 struct lock_list this, that;
1544 struct lock_list *uninitialized_var(target_entry);
1545 struct lock_list *uninitialized_var(target_entry1);
1549 this.class = hlock_class(prev);
1550 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1552 return print_bfs_bug(ret);
1557 that.class = hlock_class(next);
1558 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1560 return print_bfs_bug(ret);
1564 return print_bad_irq_dependency(curr, &this, &that,
1565 target_entry, target_entry1,
1567 bit_backwards, bit_forwards, irqclass);
1570 static const char *state_names[] = {
1571 #define LOCKDEP_STATE(__STATE) \
1572 __stringify(__STATE),
1573 #include "lockdep_states.h"
1574 #undef LOCKDEP_STATE
1577 static const char *state_rnames[] = {
1578 #define LOCKDEP_STATE(__STATE) \
1579 __stringify(__STATE)"-READ",
1580 #include "lockdep_states.h"
1581 #undef LOCKDEP_STATE
1584 static inline const char *state_name(enum lock_usage_bit bit)
1586 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1589 static int exclusive_bit(int new_bit)
1597 * bit 0 - write/read
1598 * bit 1 - used_in/enabled
1602 int state = new_bit & ~3;
1603 int dir = new_bit & 2;
1606 * keep state, bit flip the direction and strip read.
1608 return state | (dir ^ 2);
1611 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1612 struct held_lock *next, enum lock_usage_bit bit)
1615 * Prove that the new dependency does not connect a hardirq-safe
1616 * lock with a hardirq-unsafe lock - to achieve this we search
1617 * the backwards-subgraph starting at <prev>, and the
1618 * forwards-subgraph starting at <next>:
1620 if (!check_usage(curr, prev, next, bit,
1621 exclusive_bit(bit), state_name(bit)))
1627 * Prove that the new dependency does not connect a hardirq-safe-read
1628 * lock with a hardirq-unsafe lock - to achieve this we search
1629 * the backwards-subgraph starting at <prev>, and the
1630 * forwards-subgraph starting at <next>:
1632 if (!check_usage(curr, prev, next, bit,
1633 exclusive_bit(bit), state_name(bit)))
1640 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1641 struct held_lock *next)
1643 #define LOCKDEP_STATE(__STATE) \
1644 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1646 #include "lockdep_states.h"
1647 #undef LOCKDEP_STATE
1652 static void inc_chains(void)
1654 if (current->hardirq_context)
1655 nr_hardirq_chains++;
1657 if (current->softirq_context)
1658 nr_softirq_chains++;
1660 nr_process_chains++;
1667 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1668 struct held_lock *next)
1673 static inline void inc_chains(void)
1675 nr_process_chains++;
1681 print_deadlock_scenario(struct held_lock *nxt,
1682 struct held_lock *prv)
1684 struct lock_class *next = hlock_class(nxt);
1685 struct lock_class *prev = hlock_class(prv);
1687 printk(" Possible unsafe locking scenario:\n\n");
1691 __print_lock_name(prev);
1694 __print_lock_name(next);
1696 printk("\n *** DEADLOCK ***\n\n");
1697 printk(" May be due to missing lock nesting notation\n\n");
1701 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1702 struct held_lock *next)
1704 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1708 printk("=============================================\n");
1709 printk("[ INFO: possible recursive locking detected ]\n");
1710 print_kernel_ident();
1711 printk("---------------------------------------------\n");
1712 printk("%s/%d is trying to acquire lock:\n",
1713 curr->comm, task_pid_nr(curr));
1715 printk("\nbut task is already holding lock:\n");
1718 printk("\nother info that might help us debug this:\n");
1719 print_deadlock_scenario(next, prev);
1720 lockdep_print_held_locks(curr);
1722 printk("\nstack backtrace:\n");
1729 * Check whether we are holding such a class already.
1731 * (Note that this has to be done separately, because the graph cannot
1732 * detect such classes of deadlocks.)
1734 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1737 check_deadlock(struct task_struct *curr, struct held_lock *next,
1738 struct lockdep_map *next_instance, int read)
1740 struct held_lock *prev;
1741 struct held_lock *nest = NULL;
1744 for (i = 0; i < curr->lockdep_depth; i++) {
1745 prev = curr->held_locks + i;
1747 if (prev->instance == next->nest_lock)
1750 if (hlock_class(prev) != hlock_class(next))
1754 * Allow read-after-read recursion of the same
1755 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1757 if ((read == 2) && prev->read)
1761 * We're holding the nest_lock, which serializes this lock's
1762 * nesting behaviour.
1767 return print_deadlock_bug(curr, prev, next);
1773 * There was a chain-cache miss, and we are about to add a new dependency
1774 * to a previous lock. We recursively validate the following rules:
1776 * - would the adding of the <prev> -> <next> dependency create a
1777 * circular dependency in the graph? [== circular deadlock]
1779 * - does the new prev->next dependency connect any hardirq-safe lock
1780 * (in the full backwards-subgraph starting at <prev>) with any
1781 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1782 * <next>)? [== illegal lock inversion with hardirq contexts]
1784 * - does the new prev->next dependency connect any softirq-safe lock
1785 * (in the full backwards-subgraph starting at <prev>) with any
1786 * softirq-unsafe lock (in the full forwards-subgraph starting at
1787 * <next>)? [== illegal lock inversion with softirq contexts]
1789 * any of these scenarios could lead to a deadlock.
1791 * Then if all the validations pass, we add the forwards and backwards
1795 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1796 struct held_lock *next, int distance, int *stack_saved)
1798 struct lock_list *entry;
1800 struct lock_list this;
1801 struct lock_list *uninitialized_var(target_entry);
1803 * Static variable, serialized by the graph_lock().
1805 * We use this static variable to save the stack trace in case
1806 * we call into this function multiple times due to encountering
1807 * trylocks in the held lock stack.
1809 static struct stack_trace trace;
1812 * Prove that the new <prev> -> <next> dependency would not
1813 * create a circular dependency in the graph. (We do this by
1814 * forward-recursing into the graph starting at <next>, and
1815 * checking whether we can reach <prev>.)
1817 * We are using global variables to control the recursion, to
1818 * keep the stackframe size of the recursive functions low:
1820 this.class = hlock_class(next);
1822 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1824 return print_circular_bug(&this, target_entry, next, prev);
1825 else if (unlikely(ret < 0))
1826 return print_bfs_bug(ret);
1828 if (!check_prev_add_irq(curr, prev, next))
1832 * For recursive read-locks we do all the dependency checks,
1833 * but we dont store read-triggered dependencies (only
1834 * write-triggered dependencies). This ensures that only the
1835 * write-side dependencies matter, and that if for example a
1836 * write-lock never takes any other locks, then the reads are
1837 * equivalent to a NOP.
1839 if (next->read == 2 || prev->read == 2)
1842 * Is the <prev> -> <next> dependency already present?
1844 * (this may occur even though this is a new chain: consider
1845 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1846 * chains - the second one will be new, but L1 already has
1847 * L2 added to its dependency list, due to the first chain.)
1849 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1850 if (entry->class == hlock_class(next)) {
1852 entry->distance = 1;
1857 if (!*stack_saved) {
1858 if (!save_trace(&trace))
1864 * Ok, all validations passed, add the new lock
1865 * to the previous lock's dependency list:
1867 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1868 &hlock_class(prev)->locks_after,
1869 next->acquire_ip, distance, &trace);
1874 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1875 &hlock_class(next)->locks_before,
1876 next->acquire_ip, distance, &trace);
1881 * Debugging printouts:
1883 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1884 /* We drop graph lock, so another thread can overwrite trace. */
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 stack_saved = 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 && hlock->check) {
1934 if (!check_prev_add(curr, hlock, next,
1935 distance, &stack_saved))
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)
1961 if (!debug_locks_off_graph_unlock())
1965 * Clearly we all shouldn't be here, but since we made it we
1966 * can reliable say we messed up our state. See the above two
1967 * gotos for reasons why we could possibly end up here.
1974 unsigned long nr_lock_chains;
1975 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1976 int nr_chain_hlocks;
1977 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1979 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1981 return lock_classes + chain_hlocks[chain->base + i];
1985 * Look up a dependency chain. If the key is not present yet then
1986 * add it and return 1 - in this case the new dependency chain is
1987 * validated. If the key is already hashed, return 0.
1988 * (On return with 1 graph_lock is held.)
1990 static inline int lookup_chain_cache(struct task_struct *curr,
1991 struct held_lock *hlock,
1994 struct lock_class *class = hlock_class(hlock);
1995 struct hlist_head *hash_head = chainhashentry(chain_key);
1996 struct lock_chain *chain;
1997 struct held_lock *hlock_curr;
2001 * We might need to take the graph lock, ensure we've got IRQs
2002 * disabled to make this an IRQ-safe lock.. for recursion reasons
2003 * lockdep won't complain about its own locking errors.
2005 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2008 * We can walk it lock-free, because entries only get added
2011 hlist_for_each_entry_rcu(chain, hash_head, entry) {
2012 if (chain->chain_key == chain_key) {
2014 debug_atomic_inc(chain_lookup_hits);
2015 if (very_verbose(class))
2016 printk("\nhash chain already cached, key: "
2017 "%016Lx tail class: [%p] %s\n",
2018 (unsigned long long)chain_key,
2019 class->key, class->name);
2023 if (very_verbose(class))
2024 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2025 (unsigned long long)chain_key, class->key, class->name);
2027 * Allocate a new chain entry from the static array, and add
2033 * We have to walk the chain again locked - to avoid duplicates:
2035 hlist_for_each_entry(chain, hash_head, entry) {
2036 if (chain->chain_key == chain_key) {
2041 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2042 if (!debug_locks_off_graph_unlock())
2045 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2049 chain = lock_chains + nr_lock_chains++;
2050 chain->chain_key = chain_key;
2051 chain->irq_context = hlock->irq_context;
2052 /* Find the first held_lock of current chain */
2053 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2054 hlock_curr = curr->held_locks + i;
2055 if (hlock_curr->irq_context != hlock->irq_context)
2059 chain->depth = curr->lockdep_depth + 1 - i;
2060 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2061 chain->base = nr_chain_hlocks;
2062 nr_chain_hlocks += chain->depth;
2063 for (j = 0; j < chain->depth - 1; j++, i++) {
2064 int lock_id = curr->held_locks[i].class_idx - 1;
2065 chain_hlocks[chain->base + j] = lock_id;
2067 chain_hlocks[chain->base + j] = class - lock_classes;
2069 hlist_add_head_rcu(&chain->entry, hash_head);
2070 debug_atomic_inc(chain_lookup_misses);
2076 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2077 struct held_lock *hlock, int chain_head, u64 chain_key)
2080 * Trylock needs to maintain the stack of held locks, but it
2081 * does not add new dependencies, because trylock can be done
2084 * We look up the chain_key and do the O(N^2) check and update of
2085 * the dependencies only if this is a new dependency chain.
2086 * (If lookup_chain_cache() returns with 1 it acquires
2087 * graph_lock for us)
2089 if (!hlock->trylock && hlock->check &&
2090 lookup_chain_cache(curr, hlock, chain_key)) {
2092 * Check whether last held lock:
2094 * - is irq-safe, if this lock is irq-unsafe
2095 * - is softirq-safe, if this lock is hardirq-unsafe
2097 * And check whether the new lock's dependency graph
2098 * could lead back to the previous lock.
2100 * any of these scenarios could lead to a deadlock. If
2103 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2108 * Mark recursive read, as we jump over it when
2109 * building dependencies (just like we jump over
2115 * Add dependency only if this lock is not the head
2116 * of the chain, and if it's not a secondary read-lock:
2118 if (!chain_head && ret != 2)
2119 if (!check_prevs_add(curr, hlock))
2123 /* after lookup_chain_cache(): */
2124 if (unlikely(!debug_locks))
2130 static inline int validate_chain(struct task_struct *curr,
2131 struct lockdep_map *lock, struct held_lock *hlock,
2132 int chain_head, u64 chain_key)
2139 * We are building curr_chain_key incrementally, so double-check
2140 * it from scratch, to make sure that it's done correctly:
2142 static void check_chain_key(struct task_struct *curr)
2144 #ifdef CONFIG_DEBUG_LOCKDEP
2145 struct held_lock *hlock, *prev_hlock = NULL;
2149 for (i = 0; i < curr->lockdep_depth; i++) {
2150 hlock = curr->held_locks + i;
2151 if (chain_key != hlock->prev_chain_key) {
2154 * We got mighty confused, our chain keys don't match
2155 * with what we expect, someone trample on our task state?
2157 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2158 curr->lockdep_depth, i,
2159 (unsigned long long)chain_key,
2160 (unsigned long long)hlock->prev_chain_key);
2163 id = hlock->class_idx - 1;
2165 * Whoops ran out of static storage again?
2167 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2170 if (prev_hlock && (prev_hlock->irq_context !=
2171 hlock->irq_context))
2173 chain_key = iterate_chain_key(chain_key, id);
2176 if (chain_key != curr->curr_chain_key) {
2179 * More smoking hash instead of calculating it, damn see these
2180 * numbers float.. I bet that a pink elephant stepped on my memory.
2182 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2183 curr->lockdep_depth, i,
2184 (unsigned long long)chain_key,
2185 (unsigned long long)curr->curr_chain_key);
2191 print_usage_bug_scenario(struct held_lock *lock)
2193 struct lock_class *class = hlock_class(lock);
2195 printk(" Possible unsafe locking scenario:\n\n");
2199 __print_lock_name(class);
2201 printk(" <Interrupt>\n");
2203 __print_lock_name(class);
2205 printk("\n *** DEADLOCK ***\n\n");
2209 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2210 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2212 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2216 printk("=================================\n");
2217 printk("[ INFO: inconsistent lock state ]\n");
2218 print_kernel_ident();
2219 printk("---------------------------------\n");
2221 printk("inconsistent {%s} -> {%s} usage.\n",
2222 usage_str[prev_bit], usage_str[new_bit]);
2224 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2225 curr->comm, task_pid_nr(curr),
2226 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2227 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2228 trace_hardirqs_enabled(curr),
2229 trace_softirqs_enabled(curr));
2232 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2233 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2235 print_irqtrace_events(curr);
2236 printk("\nother info that might help us debug this:\n");
2237 print_usage_bug_scenario(this);
2239 lockdep_print_held_locks(curr);
2241 printk("\nstack backtrace:\n");
2248 * Print out an error if an invalid bit is set:
2251 valid_state(struct task_struct *curr, struct held_lock *this,
2252 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2254 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2255 return print_usage_bug(curr, this, bad_bit, new_bit);
2259 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2260 enum lock_usage_bit new_bit);
2262 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2265 * print irq inversion bug:
2268 print_irq_inversion_bug(struct task_struct *curr,
2269 struct lock_list *root, struct lock_list *other,
2270 struct held_lock *this, int forwards,
2271 const char *irqclass)
2273 struct lock_list *entry = other;
2274 struct lock_list *middle = NULL;
2277 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2281 printk("=========================================================\n");
2282 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2283 print_kernel_ident();
2284 printk("---------------------------------------------------------\n");
2285 printk("%s/%d just changed the state of lock:\n",
2286 curr->comm, task_pid_nr(curr));
2289 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2291 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2292 print_lock_name(other->class);
2293 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2295 printk("\nother info that might help us debug this:\n");
2297 /* Find a middle lock (if one exists) */
2298 depth = get_lock_depth(other);
2300 if (depth == 0 && (entry != root)) {
2301 printk("lockdep:%s bad path found in chain graph\n", __func__);
2305 entry = get_lock_parent(entry);
2307 } while (entry && entry != root && (depth >= 0));
2309 print_irq_lock_scenario(root, other,
2310 middle ? middle->class : root->class, other->class);
2312 print_irq_lock_scenario(other, root,
2313 middle ? middle->class : other->class, root->class);
2315 lockdep_print_held_locks(curr);
2317 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2318 if (!save_trace(&root->trace))
2320 print_shortest_lock_dependencies(other, root);
2322 printk("\nstack backtrace:\n");
2329 * Prove that in the forwards-direction subgraph starting at <this>
2330 * there is no lock matching <mask>:
2333 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2334 enum lock_usage_bit bit, const char *irqclass)
2337 struct lock_list root;
2338 struct lock_list *uninitialized_var(target_entry);
2341 root.class = hlock_class(this);
2342 ret = find_usage_forwards(&root, bit, &target_entry);
2344 return print_bfs_bug(ret);
2348 return print_irq_inversion_bug(curr, &root, target_entry,
2353 * Prove that in the backwards-direction subgraph starting at <this>
2354 * there is no lock matching <mask>:
2357 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2358 enum lock_usage_bit bit, const char *irqclass)
2361 struct lock_list root;
2362 struct lock_list *uninitialized_var(target_entry);
2365 root.class = hlock_class(this);
2366 ret = find_usage_backwards(&root, bit, &target_entry);
2368 return print_bfs_bug(ret);
2372 return print_irq_inversion_bug(curr, &root, target_entry,
2376 void print_irqtrace_events(struct task_struct *curr)
2378 printk("irq event stamp: %u\n", curr->irq_events);
2379 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2380 print_ip_sym(curr->hardirq_enable_ip);
2381 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2382 print_ip_sym(curr->hardirq_disable_ip);
2383 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2384 print_ip_sym(curr->softirq_enable_ip);
2385 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2386 print_ip_sym(curr->softirq_disable_ip);
2389 static int HARDIRQ_verbose(struct lock_class *class)
2392 return class_filter(class);
2397 static int SOFTIRQ_verbose(struct lock_class *class)
2400 return class_filter(class);
2405 static int RECLAIM_FS_verbose(struct lock_class *class)
2408 return class_filter(class);
2413 #define STRICT_READ_CHECKS 1
2415 static int (*state_verbose_f[])(struct lock_class *class) = {
2416 #define LOCKDEP_STATE(__STATE) \
2418 #include "lockdep_states.h"
2419 #undef LOCKDEP_STATE
2422 static inline int state_verbose(enum lock_usage_bit bit,
2423 struct lock_class *class)
2425 return state_verbose_f[bit >> 2](class);
2428 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2429 enum lock_usage_bit bit, const char *name);
2432 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2433 enum lock_usage_bit new_bit)
2435 int excl_bit = exclusive_bit(new_bit);
2436 int read = new_bit & 1;
2437 int dir = new_bit & 2;
2440 * mark USED_IN has to look forwards -- to ensure no dependency
2441 * has ENABLED state, which would allow recursion deadlocks.
2443 * mark ENABLED has to look backwards -- to ensure no dependee
2444 * has USED_IN state, which, again, would allow recursion deadlocks.
2446 check_usage_f usage = dir ?
2447 check_usage_backwards : check_usage_forwards;
2450 * Validate that this particular lock does not have conflicting
2453 if (!valid_state(curr, this, new_bit, excl_bit))
2457 * Validate that the lock dependencies don't have conflicting usage
2460 if ((!read || !dir || STRICT_READ_CHECKS) &&
2461 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2465 * Check for read in write conflicts
2468 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2471 if (STRICT_READ_CHECKS &&
2472 !usage(curr, this, excl_bit + 1,
2473 state_name(new_bit + 1)))
2477 if (state_verbose(new_bit, hlock_class(this)))
2484 #define LOCKDEP_STATE(__STATE) __STATE,
2485 #include "lockdep_states.h"
2486 #undef LOCKDEP_STATE
2490 * Mark all held locks with a usage bit:
2493 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2495 enum lock_usage_bit usage_bit;
2496 struct held_lock *hlock;
2499 for (i = 0; i < curr->lockdep_depth; i++) {
2500 hlock = curr->held_locks + i;
2502 usage_bit = 2 + (mark << 2); /* ENABLED */
2504 usage_bit += 1; /* READ */
2506 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2511 if (!mark_lock(curr, hlock, usage_bit))
2519 * Hardirqs will be enabled:
2521 static void __trace_hardirqs_on_caller(unsigned long ip)
2523 struct task_struct *curr = current;
2525 /* we'll do an OFF -> ON transition: */
2526 curr->hardirqs_enabled = 1;
2529 * We are going to turn hardirqs on, so set the
2530 * usage bit for all held locks:
2532 if (!mark_held_locks(curr, HARDIRQ))
2535 * If we have softirqs enabled, then set the usage
2536 * bit for all held locks. (disabled hardirqs prevented
2537 * this bit from being set before)
2539 if (curr->softirqs_enabled)
2540 if (!mark_held_locks(curr, SOFTIRQ))
2543 curr->hardirq_enable_ip = ip;
2544 curr->hardirq_enable_event = ++curr->irq_events;
2545 debug_atomic_inc(hardirqs_on_events);
2548 __visible void trace_hardirqs_on_caller(unsigned long ip)
2550 time_hardirqs_on(CALLER_ADDR0, ip);
2552 if (unlikely(!debug_locks || current->lockdep_recursion))
2555 if (unlikely(current->hardirqs_enabled)) {
2557 * Neither irq nor preemption are disabled here
2558 * so this is racy by nature but losing one hit
2559 * in a stat is not a big deal.
2561 __debug_atomic_inc(redundant_hardirqs_on);
2566 * We're enabling irqs and according to our state above irqs weren't
2567 * already enabled, yet we find the hardware thinks they are in fact
2568 * enabled.. someone messed up their IRQ state tracing.
2570 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2574 * See the fine text that goes along with this variable definition.
2576 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2580 * Can't allow enabling interrupts while in an interrupt handler,
2581 * that's general bad form and such. Recursion, limited stack etc..
2583 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2586 current->lockdep_recursion = 1;
2587 __trace_hardirqs_on_caller(ip);
2588 current->lockdep_recursion = 0;
2590 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2592 void trace_hardirqs_on(void)
2594 trace_hardirqs_on_caller(CALLER_ADDR0);
2596 EXPORT_SYMBOL(trace_hardirqs_on);
2599 * Hardirqs were disabled:
2601 __visible void trace_hardirqs_off_caller(unsigned long ip)
2603 struct task_struct *curr = current;
2605 time_hardirqs_off(CALLER_ADDR0, ip);
2607 if (unlikely(!debug_locks || current->lockdep_recursion))
2611 * So we're supposed to get called after you mask local IRQs, but for
2612 * some reason the hardware doesn't quite think you did a proper job.
2614 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2617 if (curr->hardirqs_enabled) {
2619 * We have done an ON -> OFF transition:
2621 curr->hardirqs_enabled = 0;
2622 curr->hardirq_disable_ip = ip;
2623 curr->hardirq_disable_event = ++curr->irq_events;
2624 debug_atomic_inc(hardirqs_off_events);
2626 debug_atomic_inc(redundant_hardirqs_off);
2628 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2630 void trace_hardirqs_off(void)
2632 trace_hardirqs_off_caller(CALLER_ADDR0);
2634 EXPORT_SYMBOL(trace_hardirqs_off);
2637 * Softirqs will be enabled:
2639 void trace_softirqs_on(unsigned long ip)
2641 struct task_struct *curr = current;
2643 if (unlikely(!debug_locks || current->lockdep_recursion))
2647 * We fancy IRQs being disabled here, see softirq.c, avoids
2648 * funny state and nesting things.
2650 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2653 if (curr->softirqs_enabled) {
2654 debug_atomic_inc(redundant_softirqs_on);
2658 current->lockdep_recursion = 1;
2660 * We'll do an OFF -> ON transition:
2662 curr->softirqs_enabled = 1;
2663 curr->softirq_enable_ip = ip;
2664 curr->softirq_enable_event = ++curr->irq_events;
2665 debug_atomic_inc(softirqs_on_events);
2667 * We are going to turn softirqs on, so set the
2668 * usage bit for all held locks, if hardirqs are
2671 if (curr->hardirqs_enabled)
2672 mark_held_locks(curr, SOFTIRQ);
2673 current->lockdep_recursion = 0;
2677 * Softirqs were disabled:
2679 void trace_softirqs_off(unsigned long ip)
2681 struct task_struct *curr = current;
2683 if (unlikely(!debug_locks || current->lockdep_recursion))
2687 * We fancy IRQs being disabled here, see softirq.c
2689 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2692 if (curr->softirqs_enabled) {
2694 * We have done an ON -> OFF transition:
2696 curr->softirqs_enabled = 0;
2697 curr->softirq_disable_ip = ip;
2698 curr->softirq_disable_event = ++curr->irq_events;
2699 debug_atomic_inc(softirqs_off_events);
2701 * Whoops, we wanted softirqs off, so why aren't they?
2703 DEBUG_LOCKS_WARN_ON(!softirq_count());
2705 debug_atomic_inc(redundant_softirqs_off);
2708 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2710 struct task_struct *curr = current;
2712 if (unlikely(!debug_locks))
2715 /* no reclaim without waiting on it */
2716 if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
2719 /* this guy won't enter reclaim */
2720 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2723 /* We're only interested __GFP_FS allocations for now */
2724 if (!(gfp_mask & __GFP_FS))
2728 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2730 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2733 mark_held_locks(curr, RECLAIM_FS);
2736 static void check_flags(unsigned long flags);
2738 void lockdep_trace_alloc(gfp_t gfp_mask)
2740 unsigned long flags;
2742 if (unlikely(current->lockdep_recursion))
2745 raw_local_irq_save(flags);
2747 current->lockdep_recursion = 1;
2748 __lockdep_trace_alloc(gfp_mask, flags);
2749 current->lockdep_recursion = 0;
2750 raw_local_irq_restore(flags);
2753 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2756 * If non-trylock use in a hardirq or softirq context, then
2757 * mark the lock as used in these contexts:
2759 if (!hlock->trylock) {
2761 if (curr->hardirq_context)
2762 if (!mark_lock(curr, hlock,
2763 LOCK_USED_IN_HARDIRQ_READ))
2765 if (curr->softirq_context)
2766 if (!mark_lock(curr, hlock,
2767 LOCK_USED_IN_SOFTIRQ_READ))
2770 if (curr->hardirq_context)
2771 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2773 if (curr->softirq_context)
2774 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2778 if (!hlock->hardirqs_off) {
2780 if (!mark_lock(curr, hlock,
2781 LOCK_ENABLED_HARDIRQ_READ))
2783 if (curr->softirqs_enabled)
2784 if (!mark_lock(curr, hlock,
2785 LOCK_ENABLED_SOFTIRQ_READ))
2788 if (!mark_lock(curr, hlock,
2789 LOCK_ENABLED_HARDIRQ))
2791 if (curr->softirqs_enabled)
2792 if (!mark_lock(curr, hlock,
2793 LOCK_ENABLED_SOFTIRQ))
2799 * We reuse the irq context infrastructure more broadly as a general
2800 * context checking code. This tests GFP_FS recursion (a lock taken
2801 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2804 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2806 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2809 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2817 static int separate_irq_context(struct task_struct *curr,
2818 struct held_lock *hlock)
2820 unsigned int depth = curr->lockdep_depth;
2823 * Keep track of points where we cross into an interrupt context:
2825 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2826 curr->softirq_context;
2828 struct held_lock *prev_hlock;
2830 prev_hlock = curr->held_locks + depth-1;
2832 * If we cross into another context, reset the
2833 * hash key (this also prevents the checking and the
2834 * adding of the dependency to 'prev'):
2836 if (prev_hlock->irq_context != hlock->irq_context)
2842 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2845 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2846 enum lock_usage_bit new_bit)
2848 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2852 static inline int mark_irqflags(struct task_struct *curr,
2853 struct held_lock *hlock)
2858 static inline int separate_irq_context(struct task_struct *curr,
2859 struct held_lock *hlock)
2864 void lockdep_trace_alloc(gfp_t gfp_mask)
2868 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2871 * Mark a lock with a usage bit, and validate the state transition:
2873 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2874 enum lock_usage_bit new_bit)
2876 unsigned int new_mask = 1 << new_bit, ret = 1;
2879 * If already set then do not dirty the cacheline,
2880 * nor do any checks:
2882 if (likely(hlock_class(this)->usage_mask & new_mask))
2888 * Make sure we didn't race:
2890 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2895 hlock_class(this)->usage_mask |= new_mask;
2897 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2901 #define LOCKDEP_STATE(__STATE) \
2902 case LOCK_USED_IN_##__STATE: \
2903 case LOCK_USED_IN_##__STATE##_READ: \
2904 case LOCK_ENABLED_##__STATE: \
2905 case LOCK_ENABLED_##__STATE##_READ:
2906 #include "lockdep_states.h"
2907 #undef LOCKDEP_STATE
2908 ret = mark_lock_irq(curr, this, new_bit);
2913 debug_atomic_dec(nr_unused_locks);
2916 if (!debug_locks_off_graph_unlock())
2925 * We must printk outside of the graph_lock:
2928 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2930 print_irqtrace_events(curr);
2938 * Initialize a lock instance's lock-class mapping info:
2940 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2941 struct lock_class_key *key, int subclass)
2945 kmemcheck_mark_initialized(lock, sizeof(*lock));
2947 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2948 lock->class_cache[i] = NULL;
2950 #ifdef CONFIG_LOCK_STAT
2951 lock->cpu = raw_smp_processor_id();
2955 * Can't be having no nameless bastards around this place!
2957 if (DEBUG_LOCKS_WARN_ON(!name)) {
2958 lock->name = "NULL";
2965 * No key, no joy, we need to hash something.
2967 if (DEBUG_LOCKS_WARN_ON(!key))
2970 * Sanity check, the lock-class key must be persistent:
2972 if (!static_obj(key)) {
2973 printk("BUG: key %p not in .data!\n", key);
2975 * What it says above ^^^^^, I suggest you read it.
2977 DEBUG_LOCKS_WARN_ON(1);
2982 if (unlikely(!debug_locks))
2986 unsigned long flags;
2988 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
2991 raw_local_irq_save(flags);
2992 current->lockdep_recursion = 1;
2993 register_lock_class(lock, subclass, 1);
2994 current->lockdep_recursion = 0;
2995 raw_local_irq_restore(flags);
2998 EXPORT_SYMBOL_GPL(lockdep_init_map);
3000 struct lock_class_key __lockdep_no_validate__;
3001 EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3004 print_lock_nested_lock_not_held(struct task_struct *curr,
3005 struct held_lock *hlock,
3008 if (!debug_locks_off())
3010 if (debug_locks_silent)
3014 printk("==================================\n");
3015 printk("[ BUG: Nested lock was not taken ]\n");
3016 print_kernel_ident();
3017 printk("----------------------------------\n");
3019 printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3022 printk("\nbut this task is not holding:\n");
3023 printk("%s\n", hlock->nest_lock->name);
3025 printk("\nstack backtrace:\n");
3028 printk("\nother info that might help us debug this:\n");
3029 lockdep_print_held_locks(curr);
3031 printk("\nstack backtrace:\n");
3037 static int __lock_is_held(struct lockdep_map *lock);
3040 * This gets called for every mutex_lock*()/spin_lock*() operation.
3041 * We maintain the dependency maps and validate the locking attempt:
3043 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3044 int trylock, int read, int check, int hardirqs_off,
3045 struct lockdep_map *nest_lock, unsigned long ip,
3046 int references, int pin_count)
3048 struct task_struct *curr = current;
3049 struct lock_class *class = NULL;
3050 struct held_lock *hlock;
3051 unsigned int depth, id;
3056 if (unlikely(!debug_locks))
3060 * Lockdep should run with IRQs disabled, otherwise we could
3061 * get an interrupt which would want to take locks, which would
3062 * end up in lockdep and have you got a head-ache already?
3064 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3067 if (!prove_locking || lock->key == &__lockdep_no_validate__)
3070 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3071 class = lock->class_cache[subclass];
3075 if (unlikely(!class)) {
3076 class = register_lock_class(lock, subclass, 0);
3080 atomic_inc((atomic_t *)&class->ops);
3081 if (very_verbose(class)) {
3082 printk("\nacquire class [%p] %s", class->key, class->name);
3083 if (class->name_version > 1)
3084 printk("#%d", class->name_version);
3090 * Add the lock to the list of currently held locks.
3091 * (we dont increase the depth just yet, up until the
3092 * dependency checks are done)
3094 depth = curr->lockdep_depth;
3096 * Ran out of static storage for our per-task lock stack again have we?
3098 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3101 class_idx = class - lock_classes + 1;
3104 hlock = curr->held_locks + depth - 1;
3105 if (hlock->class_idx == class_idx && nest_lock) {
3106 if (hlock->references)
3107 hlock->references++;
3109 hlock->references = 2;
3115 hlock = curr->held_locks + depth;
3117 * Plain impossible, we just registered it and checked it weren't no
3118 * NULL like.. I bet this mushroom I ate was good!
3120 if (DEBUG_LOCKS_WARN_ON(!class))
3122 hlock->class_idx = class_idx;
3123 hlock->acquire_ip = ip;
3124 hlock->instance = lock;
3125 hlock->nest_lock = nest_lock;
3126 hlock->trylock = trylock;
3128 hlock->check = check;
3129 hlock->hardirqs_off = !!hardirqs_off;
3130 hlock->references = references;
3131 #ifdef CONFIG_LOCK_STAT
3132 hlock->waittime_stamp = 0;
3133 hlock->holdtime_stamp = lockstat_clock();
3135 hlock->pin_count = pin_count;
3137 if (check && !mark_irqflags(curr, hlock))
3140 /* mark it as used: */
3141 if (!mark_lock(curr, hlock, LOCK_USED))
3145 * Calculate the chain hash: it's the combined hash of all the
3146 * lock keys along the dependency chain. We save the hash value
3147 * at every step so that we can get the current hash easily
3148 * after unlock. The chain hash is then used to cache dependency
3151 * The 'key ID' is what is the most compact key value to drive
3152 * the hash, not class->key.
3154 id = class - lock_classes;
3156 * Whoops, we did it again.. ran straight out of our static allocation.
3158 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3161 chain_key = curr->curr_chain_key;
3164 * How can we have a chain hash when we ain't got no keys?!
3166 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3171 hlock->prev_chain_key = chain_key;
3172 if (separate_irq_context(curr, hlock)) {
3176 chain_key = iterate_chain_key(chain_key, id);
3178 if (nest_lock && !__lock_is_held(nest_lock))
3179 return print_lock_nested_lock_not_held(curr, hlock, ip);
3181 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3184 curr->curr_chain_key = chain_key;
3185 curr->lockdep_depth++;
3186 check_chain_key(curr);
3187 #ifdef CONFIG_DEBUG_LOCKDEP
3188 if (unlikely(!debug_locks))
3191 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3193 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3194 printk(KERN_DEBUG "depth: %i max: %lu!\n",
3195 curr->lockdep_depth, MAX_LOCK_DEPTH);
3197 lockdep_print_held_locks(current);
3198 debug_show_all_locks();
3204 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3205 max_lockdep_depth = curr->lockdep_depth;
3211 print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3214 if (!debug_locks_off())
3216 if (debug_locks_silent)
3220 printk("=====================================\n");
3221 printk("[ BUG: bad unlock balance detected! ]\n");
3222 print_kernel_ident();
3223 printk("-------------------------------------\n");
3224 printk("%s/%d is trying to release lock (",
3225 curr->comm, task_pid_nr(curr));
3226 print_lockdep_cache(lock);
3229 printk("but there are no more locks to release!\n");
3230 printk("\nother info that might help us debug this:\n");
3231 lockdep_print_held_locks(curr);
3233 printk("\nstack backtrace:\n");
3239 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3241 if (hlock->instance == lock)
3244 if (hlock->references) {
3245 struct lock_class *class = lock->class_cache[0];
3248 class = look_up_lock_class(lock, 0);
3251 * If look_up_lock_class() failed to find a class, we're trying
3252 * to test if we hold a lock that has never yet been acquired.
3253 * Clearly if the lock hasn't been acquired _ever_, we're not
3254 * holding it either, so report failure.
3260 * References, but not a lock we're actually ref-counting?
3261 * State got messed up, follow the sites that change ->references
3262 * and try to make sense of it.
3264 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3267 if (hlock->class_idx == class - lock_classes + 1)
3275 __lock_set_class(struct lockdep_map *lock, const char *name,
3276 struct lock_class_key *key, unsigned int subclass,
3279 struct task_struct *curr = current;
3280 struct held_lock *hlock, *prev_hlock;
3281 struct lock_class *class;
3285 depth = curr->lockdep_depth;
3287 * This function is about (re)setting the class of a held lock,
3288 * yet we're not actually holding any locks. Naughty user!
3290 if (DEBUG_LOCKS_WARN_ON(!depth))
3294 for (i = depth-1; i >= 0; i--) {
3295 hlock = curr->held_locks + i;
3297 * We must not cross into another context:
3299 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3301 if (match_held_lock(hlock, lock))
3305 return print_unlock_imbalance_bug(curr, lock, ip);
3308 lockdep_init_map(lock, name, key, 0);
3309 class = register_lock_class(lock, subclass, 0);
3310 hlock->class_idx = class - lock_classes + 1;
3312 curr->lockdep_depth = i;
3313 curr->curr_chain_key = hlock->prev_chain_key;
3315 for (; i < depth; i++) {
3316 hlock = curr->held_locks + i;
3317 if (!__lock_acquire(hlock->instance,
3318 hlock_class(hlock)->subclass, hlock->trylock,
3319 hlock->read, hlock->check, hlock->hardirqs_off,
3320 hlock->nest_lock, hlock->acquire_ip,
3321 hlock->references, hlock->pin_count))
3326 * I took it apart and put it back together again, except now I have
3327 * these 'spare' parts.. where shall I put them.
3329 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3335 * Remove the lock to the list of currently held locks - this gets
3336 * called on mutex_unlock()/spin_unlock*() (or on a failed
3337 * mutex_lock_interruptible()).
3339 * @nested is an hysterical artifact, needs a tree wide cleanup.
3342 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3344 struct task_struct *curr = current;
3345 struct held_lock *hlock, *prev_hlock;
3349 if (unlikely(!debug_locks))
3352 depth = curr->lockdep_depth;
3354 * So we're all set to release this lock.. wait what lock? We don't
3355 * own any locks, you've been drinking again?
3357 if (DEBUG_LOCKS_WARN_ON(depth <= 0))
3358 return print_unlock_imbalance_bug(curr, lock, ip);
3361 * Check whether the lock exists in the current stack
3365 for (i = depth-1; i >= 0; i--) {
3366 hlock = curr->held_locks + i;
3368 * We must not cross into another context:
3370 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3372 if (match_held_lock(hlock, lock))
3376 return print_unlock_imbalance_bug(curr, lock, ip);
3379 if (hlock->instance == lock)
3380 lock_release_holdtime(hlock);
3382 WARN(hlock->pin_count, "releasing a pinned lock\n");
3384 if (hlock->references) {
3385 hlock->references--;
3386 if (hlock->references) {
3388 * We had, and after removing one, still have
3389 * references, the current lock stack is still
3390 * valid. We're done!
3397 * We have the right lock to unlock, 'hlock' points to it.
3398 * Now we remove it from the stack, and add back the other
3399 * entries (if any), recalculating the hash along the way:
3402 curr->lockdep_depth = i;
3403 curr->curr_chain_key = hlock->prev_chain_key;
3405 for (i++; i < depth; i++) {
3406 hlock = curr->held_locks + i;
3407 if (!__lock_acquire(hlock->instance,
3408 hlock_class(hlock)->subclass, hlock->trylock,
3409 hlock->read, hlock->check, hlock->hardirqs_off,
3410 hlock->nest_lock, hlock->acquire_ip,
3411 hlock->references, hlock->pin_count))
3416 * We had N bottles of beer on the wall, we drank one, but now
3417 * there's not N-1 bottles of beer left on the wall...
3419 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3425 static int __lock_is_held(struct lockdep_map *lock)
3427 struct task_struct *curr = current;
3430 for (i = 0; i < curr->lockdep_depth; i++) {
3431 struct held_lock *hlock = curr->held_locks + i;
3433 if (match_held_lock(hlock, lock))
3440 static void __lock_pin_lock(struct lockdep_map *lock)
3442 struct task_struct *curr = current;
3445 if (unlikely(!debug_locks))
3448 for (i = 0; i < curr->lockdep_depth; i++) {
3449 struct held_lock *hlock = curr->held_locks + i;
3451 if (match_held_lock(hlock, lock)) {
3457 WARN(1, "pinning an unheld lock\n");
3460 static void __lock_unpin_lock(struct lockdep_map *lock)
3462 struct task_struct *curr = current;
3465 if (unlikely(!debug_locks))
3468 for (i = 0; i < curr->lockdep_depth; i++) {
3469 struct held_lock *hlock = curr->held_locks + i;
3471 if (match_held_lock(hlock, lock)) {
3472 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
3480 WARN(1, "unpinning an unheld lock\n");
3484 * Check whether we follow the irq-flags state precisely:
3486 static void check_flags(unsigned long flags)
3488 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3489 defined(CONFIG_TRACE_IRQFLAGS)
3493 if (irqs_disabled_flags(flags)) {
3494 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3495 printk("possible reason: unannotated irqs-off.\n");
3498 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3499 printk("possible reason: unannotated irqs-on.\n");
3504 * We dont accurately track softirq state in e.g.
3505 * hardirq contexts (such as on 4KSTACKS), so only
3506 * check if not in hardirq contexts:
3508 if (!hardirq_count()) {
3509 if (softirq_count()) {
3510 /* like the above, but with softirqs */
3511 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3513 /* lick the above, does it taste good? */
3514 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3519 print_irqtrace_events(current);
3523 void lock_set_class(struct lockdep_map *lock, const char *name,
3524 struct lock_class_key *key, unsigned int subclass,
3527 unsigned long flags;
3529 if (unlikely(current->lockdep_recursion))
3532 raw_local_irq_save(flags);
3533 current->lockdep_recursion = 1;
3535 if (__lock_set_class(lock, name, key, subclass, ip))
3536 check_chain_key(current);
3537 current->lockdep_recursion = 0;
3538 raw_local_irq_restore(flags);
3540 EXPORT_SYMBOL_GPL(lock_set_class);
3543 * We are not always called with irqs disabled - do that here,
3544 * and also avoid lockdep recursion:
3546 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3547 int trylock, int read, int check,
3548 struct lockdep_map *nest_lock, unsigned long ip)
3550 unsigned long flags;
3552 if (unlikely(current->lockdep_recursion))
3555 raw_local_irq_save(flags);
3558 current->lockdep_recursion = 1;
3559 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3560 __lock_acquire(lock, subclass, trylock, read, check,
3561 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
3562 current->lockdep_recursion = 0;
3563 raw_local_irq_restore(flags);
3565 EXPORT_SYMBOL_GPL(lock_acquire);
3567 void lock_release(struct lockdep_map *lock, int nested,
3570 unsigned long flags;
3572 if (unlikely(current->lockdep_recursion))
3575 raw_local_irq_save(flags);
3577 current->lockdep_recursion = 1;
3578 trace_lock_release(lock, ip);
3579 if (__lock_release(lock, nested, ip))
3580 check_chain_key(current);
3581 current->lockdep_recursion = 0;
3582 raw_local_irq_restore(flags);
3584 EXPORT_SYMBOL_GPL(lock_release);
3586 int lock_is_held(struct lockdep_map *lock)
3588 unsigned long flags;
3591 if (unlikely(current->lockdep_recursion))
3592 return 1; /* avoid false negative lockdep_assert_held() */
3594 raw_local_irq_save(flags);
3597 current->lockdep_recursion = 1;
3598 ret = __lock_is_held(lock);
3599 current->lockdep_recursion = 0;
3600 raw_local_irq_restore(flags);
3604 EXPORT_SYMBOL_GPL(lock_is_held);
3606 void lock_pin_lock(struct lockdep_map *lock)
3608 unsigned long flags;
3610 if (unlikely(current->lockdep_recursion))
3613 raw_local_irq_save(flags);
3616 current->lockdep_recursion = 1;
3617 __lock_pin_lock(lock);
3618 current->lockdep_recursion = 0;
3619 raw_local_irq_restore(flags);
3621 EXPORT_SYMBOL_GPL(lock_pin_lock);
3623 void lock_unpin_lock(struct lockdep_map *lock)
3625 unsigned long flags;
3627 if (unlikely(current->lockdep_recursion))
3630 raw_local_irq_save(flags);
3633 current->lockdep_recursion = 1;
3634 __lock_unpin_lock(lock);
3635 current->lockdep_recursion = 0;
3636 raw_local_irq_restore(flags);
3638 EXPORT_SYMBOL_GPL(lock_unpin_lock);
3640 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3642 current->lockdep_reclaim_gfp = gfp_mask;
3645 void lockdep_clear_current_reclaim_state(void)
3647 current->lockdep_reclaim_gfp = 0;
3650 #ifdef CONFIG_LOCK_STAT
3652 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3655 if (!debug_locks_off())
3657 if (debug_locks_silent)
3661 printk("=================================\n");
3662 printk("[ BUG: bad contention detected! ]\n");
3663 print_kernel_ident();
3664 printk("---------------------------------\n");
3665 printk("%s/%d is trying to contend lock (",
3666 curr->comm, task_pid_nr(curr));
3667 print_lockdep_cache(lock);
3670 printk("but there are no locks held!\n");
3671 printk("\nother info that might help us debug this:\n");
3672 lockdep_print_held_locks(curr);
3674 printk("\nstack backtrace:\n");
3681 __lock_contended(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 int i, contention_point, contending_point;
3689 depth = curr->lockdep_depth;
3691 * Whee, we contended on this lock, except it seems we're not
3692 * actually trying to acquire anything much at all..
3694 if (DEBUG_LOCKS_WARN_ON(!depth))
3698 for (i = depth-1; i >= 0; i--) {
3699 hlock = curr->held_locks + i;
3701 * We must not cross into another context:
3703 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3705 if (match_held_lock(hlock, lock))
3709 print_lock_contention_bug(curr, lock, ip);
3713 if (hlock->instance != lock)
3716 hlock->waittime_stamp = lockstat_clock();
3718 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3719 contending_point = lock_point(hlock_class(hlock)->contending_point,
3722 stats = get_lock_stats(hlock_class(hlock));
3723 if (contention_point < LOCKSTAT_POINTS)
3724 stats->contention_point[contention_point]++;
3725 if (contending_point < LOCKSTAT_POINTS)
3726 stats->contending_point[contending_point]++;
3727 if (lock->cpu != smp_processor_id())
3728 stats->bounces[bounce_contended + !!hlock->read]++;
3729 put_lock_stats(stats);
3733 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3735 struct task_struct *curr = current;
3736 struct held_lock *hlock, *prev_hlock;
3737 struct lock_class_stats *stats;
3739 u64 now, waittime = 0;
3742 depth = curr->lockdep_depth;
3744 * Yay, we acquired ownership of this lock we didn't try to
3745 * acquire, how the heck did that happen?
3747 if (DEBUG_LOCKS_WARN_ON(!depth))
3751 for (i = depth-1; i >= 0; i--) {
3752 hlock = curr->held_locks + i;
3754 * We must not cross into another context:
3756 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3758 if (match_held_lock(hlock, lock))
3762 print_lock_contention_bug(curr, lock, _RET_IP_);
3766 if (hlock->instance != lock)
3769 cpu = smp_processor_id();
3770 if (hlock->waittime_stamp) {
3771 now = lockstat_clock();
3772 waittime = now - hlock->waittime_stamp;
3773 hlock->holdtime_stamp = now;
3776 trace_lock_acquired(lock, ip);
3778 stats = get_lock_stats(hlock_class(hlock));
3781 lock_time_inc(&stats->read_waittime, waittime);
3783 lock_time_inc(&stats->write_waittime, waittime);
3785 if (lock->cpu != cpu)
3786 stats->bounces[bounce_acquired + !!hlock->read]++;
3787 put_lock_stats(stats);
3793 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3795 unsigned long flags;
3797 if (unlikely(!lock_stat))
3800 if (unlikely(current->lockdep_recursion))
3803 raw_local_irq_save(flags);
3805 current->lockdep_recursion = 1;
3806 trace_lock_contended(lock, ip);
3807 __lock_contended(lock, ip);
3808 current->lockdep_recursion = 0;
3809 raw_local_irq_restore(flags);
3811 EXPORT_SYMBOL_GPL(lock_contended);
3813 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3815 unsigned long flags;
3817 if (unlikely(!lock_stat))
3820 if (unlikely(current->lockdep_recursion))
3823 raw_local_irq_save(flags);
3825 current->lockdep_recursion = 1;
3826 __lock_acquired(lock, ip);
3827 current->lockdep_recursion = 0;
3828 raw_local_irq_restore(flags);
3830 EXPORT_SYMBOL_GPL(lock_acquired);
3834 * Used by the testsuite, sanitize the validator state
3835 * after a simulated failure:
3838 void lockdep_reset(void)
3840 unsigned long flags;
3843 raw_local_irq_save(flags);
3844 current->curr_chain_key = 0;
3845 current->lockdep_depth = 0;
3846 current->lockdep_recursion = 0;
3847 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3848 nr_hardirq_chains = 0;
3849 nr_softirq_chains = 0;
3850 nr_process_chains = 0;
3852 for (i = 0; i < CHAINHASH_SIZE; i++)
3853 INIT_HLIST_HEAD(chainhash_table + i);
3854 raw_local_irq_restore(flags);
3857 static void zap_class(struct lock_class *class)
3862 * Remove all dependencies this lock is
3865 for (i = 0; i < nr_list_entries; i++) {
3866 if (list_entries[i].class == class)
3867 list_del_rcu(&list_entries[i].entry);
3870 * Unhash the class and remove it from the all_lock_classes list:
3872 hlist_del_rcu(&class->hash_entry);
3873 list_del_rcu(&class->lock_entry);
3875 RCU_INIT_POINTER(class->key, NULL);
3876 RCU_INIT_POINTER(class->name, NULL);
3879 static inline int within(const void *addr, void *start, unsigned long size)
3881 return addr >= start && addr < start + size;
3885 * Used in module.c to remove lock classes from memory that is going to be
3886 * freed; and possibly re-used by other modules.
3888 * We will have had one sync_sched() before getting here, so we're guaranteed
3889 * nobody will look up these exact classes -- they're properly dead but still
3892 void lockdep_free_key_range(void *start, unsigned long size)
3894 struct lock_class *class;
3895 struct hlist_head *head;
3896 unsigned long flags;
3900 raw_local_irq_save(flags);
3901 locked = graph_lock();
3904 * Unhash all classes that were created by this module:
3906 for (i = 0; i < CLASSHASH_SIZE; i++) {
3907 head = classhash_table + i;
3908 hlist_for_each_entry_rcu(class, head, hash_entry) {
3909 if (within(class->key, start, size))
3911 else if (within(class->name, start, size))
3918 raw_local_irq_restore(flags);
3921 * Wait for any possible iterators from look_up_lock_class() to pass
3922 * before continuing to free the memory they refer to.
3924 * sync_sched() is sufficient because the read-side is IRQ disable.
3926 synchronize_sched();
3929 * XXX at this point we could return the resources to the pool;
3930 * instead we leak them. We would need to change to bitmap allocators
3931 * instead of the linear allocators we have now.
3935 void lockdep_reset_lock(struct lockdep_map *lock)
3937 struct lock_class *class;
3938 struct hlist_head *head;
3939 unsigned long flags;
3943 raw_local_irq_save(flags);
3946 * Remove all classes this lock might have:
3948 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3950 * If the class exists we look it up and zap it:
3952 class = look_up_lock_class(lock, j);
3957 * Debug check: in the end all mapped classes should
3960 locked = graph_lock();
3961 for (i = 0; i < CLASSHASH_SIZE; i++) {
3962 head = classhash_table + i;
3963 hlist_for_each_entry_rcu(class, head, hash_entry) {
3966 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3967 match |= class == lock->class_cache[j];
3969 if (unlikely(match)) {
3970 if (debug_locks_off_graph_unlock()) {
3972 * We all just reset everything, how did it match?
3984 raw_local_irq_restore(flags);
3987 void __init lockdep_info(void)
3989 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3991 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3992 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3993 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3994 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3995 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3996 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3997 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3999 printk(" memory used by lock dependency info: %lu kB\n",
4000 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4001 sizeof(struct list_head) * CLASSHASH_SIZE +
4002 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4003 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4004 sizeof(struct list_head) * CHAINHASH_SIZE
4005 #ifdef CONFIG_PROVE_LOCKING
4006 + sizeof(struct circular_queue)
4011 printk(" per task-struct memory footprint: %lu bytes\n",
4012 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4016 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4017 const void *mem_to, struct held_lock *hlock)
4019 if (!debug_locks_off())
4021 if (debug_locks_silent)
4025 printk("=========================\n");
4026 printk("[ BUG: held lock freed! ]\n");
4027 print_kernel_ident();
4028 printk("-------------------------\n");
4029 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4030 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4032 lockdep_print_held_locks(curr);
4034 printk("\nstack backtrace:\n");
4038 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4039 const void* lock_from, unsigned long lock_len)
4041 return lock_from + lock_len <= mem_from ||
4042 mem_from + mem_len <= lock_from;
4046 * Called when kernel memory is freed (or unmapped), or if a lock
4047 * is destroyed or reinitialized - this code checks whether there is
4048 * any held lock in the memory range of <from> to <to>:
4050 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4052 struct task_struct *curr = current;
4053 struct held_lock *hlock;
4054 unsigned long flags;
4057 if (unlikely(!debug_locks))
4060 local_irq_save(flags);
4061 for (i = 0; i < curr->lockdep_depth; i++) {
4062 hlock = curr->held_locks + i;
4064 if (not_in_range(mem_from, mem_len, hlock->instance,
4065 sizeof(*hlock->instance)))
4068 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4071 local_irq_restore(flags);
4073 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4075 static void print_held_locks_bug(void)
4077 if (!debug_locks_off())
4079 if (debug_locks_silent)
4083 printk("=====================================\n");
4084 printk("[ BUG: %s/%d still has locks held! ]\n",
4085 current->comm, task_pid_nr(current));
4086 print_kernel_ident();
4087 printk("-------------------------------------\n");
4088 lockdep_print_held_locks(current);
4089 printk("\nstack backtrace:\n");
4093 void debug_check_no_locks_held(void)
4095 if (unlikely(current->lockdep_depth > 0))
4096 print_held_locks_bug();
4098 EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
4101 void debug_show_all_locks(void)
4103 struct task_struct *g, *p;
4107 if (unlikely(!debug_locks)) {
4108 printk("INFO: lockdep is turned off.\n");
4111 printk("\nShowing all locks held in the system:\n");
4114 * Here we try to get the tasklist_lock as hard as possible,
4115 * if not successful after 2 seconds we ignore it (but keep
4116 * trying). This is to enable a debug printout even if a
4117 * tasklist_lock-holding task deadlocks or crashes.
4120 if (!read_trylock(&tasklist_lock)) {
4122 printk("hm, tasklist_lock locked, retrying... ");
4125 printk(" #%d", 10-count);
4129 printk(" ignoring it.\n");
4133 printk(KERN_CONT " locked it.\n");
4136 do_each_thread(g, p) {
4138 * It's not reliable to print a task's held locks
4139 * if it's not sleeping (or if it's not the current
4142 if (p->state == TASK_RUNNING && p != current)
4144 if (p->lockdep_depth)
4145 lockdep_print_held_locks(p);
4147 if (read_trylock(&tasklist_lock))
4149 } while_each_thread(g, p);
4152 printk("=============================================\n\n");
4155 read_unlock(&tasklist_lock);
4157 EXPORT_SYMBOL_GPL(debug_show_all_locks);
4161 * Careful: only use this function if you are sure that
4162 * the task cannot run in parallel!
4164 void debug_show_held_locks(struct task_struct *task)
4166 if (unlikely(!debug_locks)) {
4167 printk("INFO: lockdep is turned off.\n");
4170 lockdep_print_held_locks(task);
4172 EXPORT_SYMBOL_GPL(debug_show_held_locks);
4174 asmlinkage __visible void lockdep_sys_exit(void)
4176 struct task_struct *curr = current;
4178 if (unlikely(curr->lockdep_depth)) {
4179 if (!debug_locks_off())
4182 printk("================================================\n");
4183 printk("[ BUG: lock held when returning to user space! ]\n");
4184 print_kernel_ident();
4185 printk("------------------------------------------------\n");
4186 printk("%s/%d is leaving the kernel with locks still held!\n",
4187 curr->comm, curr->pid);
4188 lockdep_print_held_locks(curr);
4192 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4194 struct task_struct *curr = current;
4196 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4197 if (!debug_locks_off())
4199 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4200 /* Note: the following can be executed concurrently, so be careful. */
4202 printk("===============================\n");
4203 printk("[ INFO: suspicious RCU usage. ]\n");
4204 print_kernel_ident();
4205 printk("-------------------------------\n");
4206 printk("%s:%d %s!\n", file, line, s);
4207 printk("\nother info that might help us debug this:\n\n");
4208 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4209 !rcu_lockdep_current_cpu_online()
4210 ? "RCU used illegally from offline CPU!\n"
4211 : !rcu_is_watching()
4212 ? "RCU used illegally from idle CPU!\n"
4214 rcu_scheduler_active, debug_locks);
4217 * If a CPU is in the RCU-free window in idle (ie: in the section
4218 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4219 * considers that CPU to be in an "extended quiescent state",
4220 * which means that RCU will be completely ignoring that CPU.
4221 * Therefore, rcu_read_lock() and friends have absolutely no
4222 * effect on a CPU running in that state. In other words, even if
4223 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4224 * delete data structures out from under it. RCU really has no
4225 * choice here: we need to keep an RCU-free window in idle where
4226 * the CPU may possibly enter into low power mode. This way we can
4227 * notice an extended quiescent state to other CPUs that started a grace
4228 * period. Otherwise we would delay any grace period as long as we run
4231 * So complain bitterly if someone does call rcu_read_lock(),
4232 * rcu_read_lock_bh() and so on from extended quiescent states.
4234 if (!rcu_is_watching())
4235 printk("RCU used illegally from extended quiescent state!\n");
4237 lockdep_print_held_locks(curr);
4238 printk("\nstack backtrace:\n");
4241 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);